Dietary change among hominins and cercopithecids in Ethiopia during the early Pliocene

NASA Astrophysics Data System (ADS)

Levin, Naomi E.; Haile-Selassie, Yohannes; Frost, Stephen R.; Saylor, Beverly Z.

2015-10-01

The incorporation of C4 resources into hominin diet signifies increased dietary breadth within hominins and divergence from the dietary patterns of other great apes. Morphological evidence indicates that hominin diet became increasingly diverse by 4.2 million years ago but may not have included large proportions of C4 foods until 800 thousand years later, given the available isotopic evidence. Here we use carbon isotope data from early to mid Pliocene hominin and cercopithecid fossils from Woranso-Mille (central Afar, Ethiopia) to constrain the timing of this dietary change and its ecological context. We show that both hominins and some papionins expanded their diets to include C4 resources as early as 3.76 Ma. Among hominins, this dietary expansion postdates the major dentognathic morphological changes that distinguish Australopithecus from Ardipithecus, but it occurs amid a continuum of adaptations to diets of tougher, harder foods and to committed terrestrial bipedality. In contrast, carbon isotope data from cercopithecids indicate that C4-dominated diets of the earliest members of the Theropithecus oswaldi lineage preceded the dental specialization for grazing but occurred after they were fully terrestrial. The combined data indicate that the inclusion of C4 foods in hominin diet occurred as part of broader ecological changes in African primate communities.

Dietary change among hominins and cercopithecids in Ethiopia during the early Pliocene

PubMed Central

Levin, Naomi E.; Haile-Selassie, Yohannes; Frost, Stephen R.; Saylor, Beverly Z.

2015-01-01

The incorporation of C4 resources into hominin diet signifies increased dietary breadth within hominins and divergence from the dietary patterns of other great apes. Morphological evidence indicates that hominin diet became increasingly diverse by 4.2 million years ago but may not have included large proportions of C4 foods until 800 thousand years later, given the available isotopic evidence. Here we use carbon isotope data from early to mid Pliocene hominin and cercopithecid fossils from Woranso-Mille (central Afar, Ethiopia) to constrain the timing of this dietary change and its ecological context. We show that both hominins and some papionins expanded their diets to include C4 resources as early as 3.76 Ma. Among hominins, this dietary expansion postdates the major dentognathic morphological changes that distinguish Australopithecus from Ardipithecus, but it occurs amid a continuum of adaptations to diets of tougher, harder foods and to committed terrestrial bipedality. In contrast, carbon isotope data from cercopithecids indicate that C4-dominated diets of the earliest members of the Theropithecus oswaldi lineage preceded the dental specialization for grazing but occurred after they were fully terrestrial. The combined data indicate that the inclusion of C4 foods in hominin diet occurred as part of broader ecological changes in African primate communities. PMID:26371308

Hominin life history: reconstruction and evolution

PubMed Central

Robson, Shannen L; Wood, Bernard

2008-01-01

In this review we attempt to reconstruct the evolutionary history of hominin life history from extant and fossil evidence. We utilize demographic life history theory and distinguish life history variables, traits such as weaning, age at sexual maturity, and life span, from life history-related variables such as body mass, brain growth, and dental development. The latter are either linked with, or can be used to make inferences about, life history, thus providing an opportunity for estimating life history parameters in fossil taxa. We compare the life history variables of modern great apes and identify traits that are likely to be shared by the last common ancestor of Pan-Homo and those likely to be derived in hominins. All great apes exhibit slow life histories and we infer this to be true of the last common ancestor of Pan-Homo and the stem hominin. Modern human life histories are even slower, exhibiting distinctively long post-menopausal life spans and later ages at maturity, pointing to a reduction in adult mortality since the Pan-Homo split. We suggest that lower adult mortality, distinctively short interbirth intervals, and early weaning characteristic of modern humans are derived features resulting from cooperative breeding. We evaluate the fidelity of three life history-related variables, body mass, brain growth and dental development, with the life history parameters of living great apes. We found that body mass is the best predictor of great ape life history events. Brain growth trajectories and dental development and eruption are weakly related proxies and inferences from them should be made with caution. We evaluate the evidence of life history-related variables available for extinct species and find that prior to the transitional hominins there is no evidence of any hominin taxon possessing a body size, brain size or aspects of dental development much different from what we assume to be the primitive life history pattern for the Pan-Homo clade. Data for

An Early Pleistocene hominin mandible from Atapuerca-TD6, Spain

PubMed Central

Carbonell, E.; Bermúdez de Castro, J. M.; Arsuaga, J. L.; Allue, E.; Bastir, M.; Benito, A.; Cáceres, I.; Canals, T.; Díez, J. C.; van der Made, J.; Mosquera, M.; Ollé, A.; Pérez-González, A.; Rodríguez, J.; Rodríguez, X. P.; Rosas, A.; Rosell, J.; Sala, R.; Vallverdú, J.; Vergés, J. M.

2005-01-01

We present a mandible recovered in 2003 from the Aurora Stratum of the TD6 level of the Gran Dolina site (Sierra de Atapuerca, northern Spain). The specimen, catalogued as ATD6-96, adds to the hominin sample recovered from this site in 1994–1996, and assigned to Homo antecessor. ATD6-96 is the left half of a gracile mandible belonging to a probably female adult individual with premolars and molars in place. This mandible shows a primitive structural pattern shared with all African and Asian Homo species. However, it is small and exhibits a remarkable gracility, a trait shared only with the Early and Middle Pleistocene Chinese hominins. Furthermore, none of the mandibular features considered apomorphic in the European Middle and Early Upper Pleistocene hominin lineage are present in ATD6-96. This evidence reinforces the taxonomic identity of H. antecessor and is consistent with the hypothesis of a close relationship between this species and Homo sapiens. PMID:15824320

The first hominin from the early Pleistocene paleocave of Haasgat, South Africa.

PubMed

Leece, A B; Kegley, Anthony D T; Lacruz, Rodrigo S; Herries, Andy I R; Hemingway, Jason; Kgasi, Lazarus; Potze, Stephany; Adams, Justin W

2016-01-01

Haasgat is a primate-rich fossil locality in the northeastern part of the Fossil Hominid Sites of South Africa UNESCO World Heritage Site. Here we report the first hominin identified from Haasgat, a partial maxillary molar (HGT 500), that was recovered from an ex situ calcified sediment block sampled from the locality. The in situ fossil bearing deposits of the Haasgat paleokarstic deposits are estimated to date to slightly older than 1.95 Ma based on magnetobiostratigraphy. This places the hominin specimen at a critical time period in South Africa that marks the last occurrence of Australopithecus around 1.98 Ma and the first evidence of Paranthropus and Homo in the region between ∼2.0 and 1.8 Ma. A comprehensive morphological evaluation of the Haasgat hominin molar was conducted against the current South African catalogue of hominin dental remains and imaging analyses using micro-CT, electron and confocal microscopy. The preserved occlusal morphology is most similar to Australopithecus africanus or early Homo specimens but different from Paranthropus. Occlusal linear enamel thickness measured from micro-CT scans provides an average of ∼2.0 mm consistent with Australopithecus and early Homo. Analysis of the enamel microstructure suggests an estimated periodicity of 7-9 days. Hunter-Schreger bands appear long and straight as in some Paranthropus, but contrast with this genus in the short shape of the striae of Retzius. Taken together, these data suggests that the maxillary fragment recovered from Haasgat best fits within the Australopithecus-early Homo hypodigms to the exclusion of the genus Paranthropus. At ∼1.95 Ma this specimen would either represent another example of late occurring Australopithecus or one of the earliest examples of Homo in the region. While the identification of this first hominin specimen from Haasgat is not unexpected given the composition of other South African penecontemporaneous site deposits, it represents one of the few hominin

Multi-level human evolution: ecological patterns in hominin phylogeny.

PubMed

Parravicini, Andrea; Pievani, Telmo

2016-06-20

Evolution is a process that occurs at many different levels, from genes to ecosystems. Genetic variations and ecological pressures are hence two sides of the same coin; but due both to fragmentary evidence and to the influence of a gene-centered and gradualistic approach to evolutionary phenomena, the field of paleoanthropology has been slow to take the role of macro-evolutionary patterns (i.e. ecological and biogeographical at large scale) seriously. However, several very recent findings in paleoanthropology stress both climate instability and ecological disturbance as key factors affecting the highly branching hominin phylogeny, from the earliest hominins to the appearance of cognitively modern humans. Allopatric speciation due to geographic displacement, turnover-pulses of species, adaptive radiation, mosaic evolution of traits in several coeval species, bursts of behavioral innovation, serial dispersals out of Africa, are just some of the macro-evolutionary patterns emerging from the field. The multilevel approach to evolution proposed by paleontologist Niles Eldredge is adopted here as interpretative tool, and has yielded a larger picture of human evolution that integrates different levels of evolutionary change, from local adaptations in limited ecological niches to dispersal phenotypes able to colonize an unprecedented range of ecosystems. Changes in global climate and Earth's surface most greatly affected human evolution. Precisely because it is cognitively hard for us to appreciate the long-term common destiny we share with the whole biosphere, it is particularly valuable to highlight the accumulating evidence that human evolution has been deeply affected by global ecological changes that transformed our African continent of origin.

First Early Hominin from Central Africa (Ishango, Democratic Republic of Congo)

PubMed Central

Crevecoeur, Isabelle; Skinner, Matthew M.; Bailey, Shara E.; Gunz, Philipp; Bortoluzzi, Silvia; Brooks, Alison S.; Burlet, Christian; Cornelissen, Els; De Clerck, Nora; Maureille, Bruno; Semal, Patrick; Vanbrabant, Yves; Wood, Bernard

2014-01-01

Despite uncontested evidence for fossils belonging to the early hominin genus Australopithecus in East Africa from at least 4.2 million years ago (Ma), and from Chad by 3.5 Ma, thus far there has been no convincing evidence of Australopithecus, Paranthropus or early Homo from the western (Albertine) branch of the Rift Valley. Here we report the discovery of an isolated upper molar (#Ish25) from the Western Rift Valley site of Ishango in Central Africa in a derived context, overlying beds dated to between ca. 2.6 to 2.0 Ma. We used µCT imaging to compare its external and internal macro-morphology to upper molars of australopiths, and fossil and recent Homo. We show that the size and shape of the enamel-dentine junction (EDJ) surface discriminate between Plio-Pleistocene and post-Lower Pleistocene hominins, and that the Ishango molar clusters with australopiths and early Homo from East and southern Africa. A reassessment of the archaeological context of the specimen is consistent with the morphological evidence and suggest that early hominins were occupying this region by at least 2 Ma. PMID:24427292

Early hominins in Europe: The Galerian migration hypothesis

NASA Astrophysics Data System (ADS)

Muttoni, Giovanni; Scardia, Giancarlo; Kent, Dennis V.

2018-01-01

Our updated review of sites bearing hominin remains and/or tools from Europe, including new findings from the Balkans, still indicates that the only compelling evidence of main hominin presence in these regions was only since ∼0.9 million years ago (Ma), bracketed by the end of the Jaramillo geomagnetic polarity subchron (0.99 Ma) and the Brunhes-Matuyama polarity chron boundary (0.78 Ma). This time window straddled the late Early Pleistocene climate transition (EPT) at the onset of enhanced glacial/interglacial activity that reverberated worldwide. Europe may have become initially populated during the EPT when, possibly for the first time in the Pleistocene, vast and exploitable ecosystems were generated along the eustatically emergent Po-Danube terrestrial conduit. These newly formed settings, characterized by stable terrestrial lowlands with open grasslands and reduced woody cover especially during glacial/interglacial transitions, are regarded as optimal ecosystems for several large Galerian immigrant mammals such as African and Asian megaherbivores, possibly linked with hominins in a common food web, to expand into en route to Europe. The question of when hominins first arrived in Europe thus places the issue in the context of changes in climate, paleogeography and faunal associations as potential environmental drivers and controlling agents in a specific time frame, a key feature of the Galerian migration hypothesis.

Early hominins in Europe: The Galerian migration hypothesis

NASA Astrophysics Data System (ADS)

Muttoni, G.; Scardia, G.; Kent, D.

2017-12-01

Our updated review of sites bearing hominin remains and/or tools from Europe, including new findings from the Balkans, still indicates that the only compelling evidence of hominin presence in these regions was only since 0.9 Ma (million-years-ago), bracketed by the end of the Jaramillo geomagnetic polarity subchron (0.99 Ma) and the Brunhes-Matuyama polarity boundary (0.78 Ma). This time window straddled the late Early Pleistocene climate transition (EPR) at the onset of enhanced glacial/interglacial activity that reverberated worldwide. Europe may have become initially populated during the EPR when, possibly for the first time in the Pleistocene, vast and exploitable ecosystems were generated along the eustatically emergent Danube-Po migration gateway. These newly formed settings, characterized by lowlands with open grasslands and reduced woody cover during glacial/interglacial transitions, represented the closest analogues to the savanna environment to which several large Galerian immigrant mammals (e.g., African and Asian megaherbivores) linked with hominins in a common food web were adapted and could expand into en route to Europe. The question of when hominins first arrived in Europe thus places the issue in the context of changes in climate, paleogeography and faunal associations as potential environmental drivers and controlling agents in a specific time frame, a key feature of the Galerian migration hypothesis.

Measures of maturation in early fossil hominins: events at the first transition from australopiths to early Homo

PubMed Central

Dean, M. Christopher

2016-01-01

An important question in palaeoanthropology is whether, among the australopiths and the first fossil hominins attributed to early Homo, there was a shift towards a more prolonged period of growth that can be distinguished from that of the living great apes and whether between the end of weaning and the beginning of puberty there was a slow period of growth as there is in modern humans. Evidence for the pace of growth in early fossil hominins comes from preserved tooth microstructure. A record of incremental growth in enamel and dentine persists, which allows us to reconstruct tooth growth and compare key measures of dental maturation with modern humans and living great apes. Despite their diverse diets and way of life, it is currently difficult to identify any clear differences in the timing of dental development among living great apes, australopiths and the earliest hominins attributed to the genus Homo. There is, however, limited evidence that some early hominins may have attained a greater proportion of their body mass and stature relatively earlier in the growth period than is typical of modern humans today. This article is part of the themed issue ‘Major transitions in human evolution’. PMID:27298465

Hominin Hip Biomechanics: Changing Perspectives.

PubMed

Warrener, Anna G

2017-05-01

The shape of the human pelvis reflects the unique demands placed on the hip abductor muscles (gluteus medius and gluteus minimus), which stabilize the body in the frontal plane during bipedal locomotion. This morphological shift occurred early in hominin evolution, yet important shape differences between hominin species have led to significant disagreement about abductor function and locomotor capability in these extinct taxa. A static biomechanical model that relies on a close association between skeletal measurements of the pelvis and femur has traditionally been used to reconstruct hip biomechanics in these species. However, experimental biomechanical approaches have highlighted the dynamic nature of mediolateral balance in walking and running, challenging the assumptions of the static hip model. This article reviews traditional approaches for understanding hip abductor function, shows how they have been applied to the fossil hominin record, and discusses new techniques that integrate the dynamic nature of mediolateral balance during human locomotion. Anat Rec, 300:932-945, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Early Pleistocene third metacarpal from Kenya and the evolution of modern human-like hand morphology

PubMed Central

Ward, Carol V.; Tocheri, Matthew W.; Plavcan, J. Michael; Brown, Francis H.; Manthi, Fredrick Kyalo

2014-01-01

Despite discoveries of relatively complete hands from two early hominin species (Ardipithecus ramidus and Australopithecus sediba) and partial hands from another (Australopithecus afarensis), fundamental questions remain about the evolution of human-like hand anatomy and function. These questions are driven by the paucity of hand fossils in the hominin fossil record between 800,000 and 1.8 My old, a time interval well documented for the emergence and subsequent proliferation of Acheulian technology (shaped bifacial stone tools). Modern and Middle to Late Pleistocene humans share a suite of derived features in the thumb, wrist, and radial carpometacarpal joints that is noticeably absent in early hominins. Here we show that one of the most distinctive features of this suite in the Middle Pleistocene to recent human hand, the third metacarpal styloid process, was present ∼1.42 Mya in an East African hominin from Kaitio, West Turkana, Kenya. This fossil thus provides the earliest unambiguous evidence for the evolution of a key shared derived characteristic of modern human and Neandertal hand morphology and suggests that the distinctive complex of radial carpometacarpal joint features in the human hand arose early in the evolution of the genus Homo and probably in Homo erectus sensu lato. PMID:24344276

Hominin footprints from early Pleistocene deposits at Happisburgh, UK.

PubMed

Ashton, Nick; Lewis, Simon G; De Groote, Isabelle; Duffy, Sarah M; Bates, Martin; Bates, Richard; Hoare, Peter; Lewis, Mark; Parfitt, Simon A; Peglar, Sylvia; Williams, Craig; Stringer, Chris

2014-01-01

Investigations at Happisburgh, UK, have revealed the oldest known hominin footprint surface outside Africa at between ca. 1 million and 0.78 million years ago. The site has long been recognised for the preservation of sediments containing Early Pleistocene fauna and flora, but since 2005 has also yielded humanly made flint artefacts, extending the record of human occupation of northern Europe by at least 350,000 years. The sediments consist of sands, gravels and laminated silts laid down by a large river within the upper reaches of its estuary. In May 2013 extensive areas of the laminated sediments were exposed on the foreshore. On the surface of one of the laminated silt horizons a series of hollows was revealed in an area of ca. 12 m(2). The surface was recorded using multi-image photogrammetry which showed that the hollows are distinctly elongated and the majority fall within the range of juvenile to adult hominin foot sizes. In many cases the arch and front/back of the foot can be identified and in one case the impression of toes can be seen. Using foot length to stature ratios, the hominins are estimated to have been between ca. 0.93 and 1.73 m in height, suggestive of a group of mixed ages. The orientation of the prints indicates movement in a southerly direction on mud-flats along the river edge. Early Pleistocene human fossils are extremely rare in Europe, with no evidence from the UK. The only known species in western Europe of a similar age is Homo antecessor, whose fossil remains have been found at Atapuerca, Spain. The foot sizes and estimated stature of the hominins from Happisburgh fall within the range derived from the fossil evidence of Homo antecessor.

Modelling the role of groundwater hydro-refugia in East African hominin evolution and dispersal

PubMed Central

Cuthbert, M. O.; Gleeson, T.; Reynolds, S. C.; Bennett, M. R.; Newton, A. C.; McCormack, C. J.; Ashley, G. M.

2017-01-01

Water is a fundamental resource, yet its spatiotemporal availability in East Africa is poorly understood. This is the area where most hominin first occurrences are located, and consequently the potential role of water in hominin evolution and dispersal remains unresolved. Here, we show that hundreds of springs currently distributed across East Africa could function as persistent groundwater hydro-refugia through orbital-scale climate cycles. Groundwater buffers climate variability according to spatially variable groundwater response times determined by geology and topography. Using an agent-based model, grounded on the present day landscape, we show that groundwater availability would have been critical to supporting isolated networks of hydro-refugia during dry periods when potable surface water was scarce. This may have facilitated unexpected variations in isolation and dispersal of hominin populations in the past. Our results therefore provide a new environmental framework in which to understand how patterns of taxonomic diversity in hominins may have developed. PMID:28556825

Modelling the role of groundwater hydro-refugia in East African hominin evolution and dispersal

NASA Astrophysics Data System (ADS)

Cuthbert, M. O.; Gleeson, T.; Reynolds, S. C.; Bennett, M. R.; Newton, A. C.; McCormack, C. J.; Ashley, G. M.

2017-05-01

Water is a fundamental resource, yet its spatiotemporal availability in East Africa is poorly understood. This is the area where most hominin first occurrences are located, and consequently the potential role of water in hominin evolution and dispersal remains unresolved. Here, we show that hundreds of springs currently distributed across East Africa could function as persistent groundwater hydro-refugia through orbital-scale climate cycles. Groundwater buffers climate variability according to spatially variable groundwater response times determined by geology and topography. Using an agent-based model, grounded on the present day landscape, we show that groundwater availability would have been critical to supporting isolated networks of hydro-refugia during dry periods when potable surface water was scarce. This may have facilitated unexpected variations in isolation and dispersal of hominin populations in the past. Our results therefore provide a new environmental framework in which to understand how patterns of taxonomic diversity in hominins may have developed.

The Evolution and Functional Impact of Human Deletion Variants Shared with Archaic Hominin Genomes

PubMed Central

Lin, Yen-Lung; Pavlidis, Pavlos; Karakoc, Emre; Ajay, Jerry; Gokcumen, Omer

2015-01-01

Allele sharing between modern and archaic hominin genomes has been variously interpreted to have originated from ancestral genetic structure or through non-African introgression from archaic hominins. However, evolution of polymorphic human deletions that are shared with archaic hominin genomes has yet to be studied. We identified 427 polymorphic human deletions that are shared with archaic hominin genomes, approximately 87% of which originated before the Human–Neandertal divergence (ancient) and only approximately 9% of which have been introgressed from Neandertals (introgressed). Recurrence, incomplete lineage sorting between human and chimp lineages, and hominid-specific insertions constitute the remaining approximately 4% of allele sharing between humans and archaic hominins. We observed that ancient deletions correspond to more than 13% of all common (>5% allele frequency) deletion variation among modern humans. Our analyses indicate that the genomic landscapes of both ancient and introgressed deletion variants were primarily shaped by purifying selection, eliminating large and exonic variants. We found 17 exonic deletions that are shared with archaic hominin genomes, including those leading to three fusion transcripts. The affected genes are involved in metabolism of external and internal compounds, growth and sperm formation, as well as susceptibility to psoriasis and Crohn’s disease. Our analyses suggest that these “exonic” deletion variants have evolved through different adaptive forces, including balancing and population-specific positive selection. Our findings reveal that genomic structural variants that are shared between humans and archaic hominin genomes are common among modern humans and can influence biomedically and evolutionarily important phenotypes. PMID:25556237

Measure, Then Show: Grasping Human Evolution Through an Inquiry-Based, Data-driven Hominin Skulls Lab.

PubMed

Bayer, Chris N; Luberda, Michael

2016-01-01

Incomprehension and denial of the theory of evolution among high school students has been observed to also occur when teachers are not equipped to deliver a compelling case also for human evolution based on fossil evidence. This paper assesses the outcomes of a novel inquiry-based paleoanthropology lab teaching human evolution to high-school students. The inquiry-based Be a Paleoanthropologist for a Day lab placed a dozen hominin skulls into the hands of high-school students. Upon measuring three variables of human evolution, students explain what they have observed and discuss findings. In the 2013/14 school year, 11 biology classes in 7 schools in the Greater New Orleans area participated in this lab. The interviewed teacher cohort unanimously agreed that the lab featuring hominin skull replicas and stimulating student inquiry was a pedagogically excellent method of delivering the subject of human evolution. First, the lab's learning path of transforming facts to data, information to knowledge, and knowledge to acceptance empowered students to themselves execute part of the science that underpins our understanding of deep time hominin evolution. Second, although challenging, the hands-on format of the lab was accessible to high-school students, most of whom were readily able to engage the lab's scientific process. Third, the lab's exciting and compelling pedagogy unlocked higher order thinking skills, effectively activating the cognitive, psychomotor and affected learning domains as defined in Bloom's taxonomy. Lastly, the lab afforded students a formative experience with a high degree of retention and epistemic depth. Further study is warranted to gauge the degree of these effects.

Homo naledi and Pleistocene hominin evolution in subequatorial Africa

PubMed Central

Berger, Lee R; Hawks, John; Dirks, Paul HGM; Elliott, Marina; Roberts, Eric M

2017-01-01

New discoveries and dating of fossil remains from the Rising Star cave system, Cradle of Humankind, South Africa, have strong implications for our understanding of Pleistocene human evolution in Africa. Direct dating of Homo naledi fossils from the Dinaledi Chamber (Berger et al., 2015) shows that they were deposited between about 236 ka and 335 ka (Dirks et al., 2017), placing H. naledi in the later Middle Pleistocene. Hawks and colleagues (Hawks et al., 2017) report the discovery of a second chamber within the Rising Star system (Dirks et al., 2015) that contains H. naledi remains. Previously, only large-brained modern humans or their close relatives had been demonstrated to exist at this late time in Africa, but the fossil evidence for any hominins in subequatorial Africa was very sparse. It is now evident that a diversity of hominin lineages existed in this region, with some divergent lineages contributing DNA to living humans and at least H. naledi representing a survivor from the earliest stages of diversification within Homo. The existence of a diverse array of hominins in subequatorial comports with our present knowledge of diversity across other savanna-adapted species, as well as with palaeoclimate and paleoenvironmental data. H. naledi casts the fossil and archaeological records into a new light, as we cannot exclude that this lineage was responsible for the production of Acheulean or Middle Stone Age tool industries. DOI: http://dx.doi.org/10.7554/eLife.24234.001 PMID:28483041

Measure, Then Show: Grasping Human Evolution Through an Inquiry-Based, Data-driven Hominin Skulls Lab

PubMed Central

Luberda, Michael

2016-01-01

Incomprehension and denial of the theory of evolution among high school students has been observed to also occur when teachers are not equipped to deliver a compelling case also for human evolution based on fossil evidence. This paper assesses the outcomes of a novel inquiry-based paleoanthropology lab teaching human evolution to high-school students. The inquiry-based Be a Paleoanthropologist for a Day lab placed a dozen hominin skulls into the hands of high-school students. Upon measuring three variables of human evolution, students explain what they have observed and discuss findings. In the 2013/14 school year, 11 biology classes in 7 schools in the Greater New Orleans area participated in this lab. The interviewed teacher cohort unanimously agreed that the lab featuring hominin skull replicas and stimulating student inquiry was a pedagogically excellent method of delivering the subject of human evolution. First, the lab’s learning path of transforming facts to data, information to knowledge, and knowledge to acceptance empowered students to themselves execute part of the science that underpins our understanding of deep time hominin evolution. Second, although challenging, the hands-on format of the lab was accessible to high-school students, most of whom were readily able to engage the lab’s scientific process. Third, the lab’s exciting and compelling pedagogy unlocked higher order thinking skills, effectively activating the cognitive, psychomotor and affected learning domains as defined in Bloom’s taxonomy. Lastly, the lab afforded students a formative experience with a high degree of retention and epistemic depth. Further study is warranted to gauge the degree of these effects. PMID:27513927

Viewpoints: diet and dietary adaptations in early hominins: the hard food perspective.

PubMed

Strait, David S; Constantino, Paul; Lucas, Peter W; Richmond, Brian G; Spencer, Mark A; Dechow, Paul C; Ross, Callum F; Grosse, Ian R; Wright, Barth W; Wood, Bernard A; Weber, Gerhard W; Wang, Qian; Byron, Craig; Slice, Dennis E; Chalk, Janine; Smith, Amanda L; Smith, Leslie C; Wood, Sarah; Berthaume, Michael; Benazzi, Stefano; Dzialo, Christine; Tamvada, Kelli; Ledogar, Justin A

2013-07-01

Recent biomechanical analyses examining the feeding adaptations of early hominins have yielded results consistent with the hypothesis that hard foods exerted a selection pressure that influenced the evolution of australopith morphology. However, this hypothesis appears inconsistent with recent reconstructions of early hominin diet based on dental microwear and stable isotopes. Thus, it is likely that either the diets of some australopiths included a high proportion of foods these taxa were poorly adapted to consume (i.e., foods that they would not have processed efficiently), or that aspects of what we thought we knew about the functional morphology of teeth must be wrong. Evaluation of these possibilities requires a recognition that analyses based on microwear, isotopes, finite element modeling, and enamel chips and cracks each test different types of hypotheses and allow different types of inferences. Microwear and isotopic analyses are best suited to reconstructing broad dietary patterns, but are limited in their ability to falsify specific hypotheses about morphological adaptation. Conversely, finite element analysis is a tool for evaluating the mechanical basis of form-function relationships, but says little about the frequency with which specific behaviors were performed or the particular types of food that were consumed. Enamel chip and crack analyses are means of both reconstructing diet and examining biomechanics. We suggest that current evidence is consistent with the hypothesis that certain derived australopith traits are adaptations for consuming hard foods, but that australopiths had generalized diets that could include high proportions of foods that were both compliant and tough. Copyright © 2013 Wiley Periodicals, Inc.

Body mass estimates of hominin fossils and the evolution of human body size.

PubMed

Grabowski, Mark; Hatala, Kevin G; Jungers, William L; Richmond, Brian G

2015-08-01

Body size directly influences an animal's place in the natural world, including its energy requirements, home range size, relative brain size, locomotion, diet, life history, and behavior. Thus, an understanding of the biology of extinct organisms, including species in our own lineage, requires accurate estimates of body size. Since the last major review of hominin body size based on postcranial morphology over 20 years ago, new fossils have been discovered, species attributions have been clarified, and methods improved. Here, we present the most comprehensive and thoroughly vetted set of individual fossil hominin body mass predictions to date, and estimation equations based on a large (n = 220) sample of modern humans of known body masses. We also present species averages based exclusively on fossils with reliable taxonomic attributions, estimates of species averages by sex, and a metric for levels of sexual dimorphism. Finally, we identify individual traits that appear to be the most reliable for mass estimation for each fossil species, for use when only one measurement is available for a fossil. Our results show that many early hominins were generally smaller-bodied than previously thought, an outcome likely due to larger estimates in previous studies resulting from the use of large-bodied modern human reference samples. Current evidence indicates that modern human-like large size first appeared by at least 3-3.5 Ma in some Australopithecus afarensis individuals. Our results challenge an evolutionary model arguing that body size increased from Australopithecus to early Homo. Instead, we show that there is no reliable evidence that the body size of non-erectus early Homo differed from that of australopiths, and confirm that Homo erectus evolved larger average body size than earlier hominins. Copyright © 2015 Elsevier Ltd. All rights reserved.

Long-term patterns of body mass and stature evolution within the hominin lineage.

PubMed

Will, Manuel; Pablos, Adrián; Stock, Jay T

2017-11-01

Body size is a central determinant of a species' biology and adaptive strategy, but the number of reliable estimates of hominin body mass and stature have been insufficient to determine long-term patterns and subtle interactions in these size components within our lineage. Here, we analyse 254 body mass and 204 stature estimates from a total of 311 hominin specimens dating from 4.4 Ma to the Holocene using multi-level chronological and taxonomic analytical categories. The results demonstrate complex temporal patterns of body size variation with phases of relative stasis intermitted by periods of rapid increases. The observed trajectories could result from punctuated increases at speciation events, but also differential proliferation of large-bodied taxa or the extinction of small-bodied populations. Combined taxonomic and temporal analyses show that in relation to australopithecines, early Homo is characterized by significantly larger average body mass and stature but retains considerable diversity, including small body sizes. Within later Homo , stature and body mass evolution follow different trajectories: average modern stature is maintained from ca 1.6 Ma, while consistently higher body masses are not established until the Middle Pleistocene at ca 0.5-0.4 Ma, likely caused by directional selection related to colonizing higher latitudes. Selection against small-bodied individuals (less than 40 kg; less than 140 cm) after 1.4 Ma is associated with a decrease in relative size variability in later Homo species compared with earlier Homo and australopithecines. The isolated small-bodied individuals of Homo naledi ( ca 0.3 Ma) and Homo floresiensis ( ca 100-60 ka) constitute important exceptions to these general patterns, adding further layers of complexity to the evolution of body size within the genus Homo . At the end of the Late Pleistocene and Holocene, body size in Homo sapiens declines on average, but also extends to lower limits not seen in

Long-term patterns of body mass and stature evolution within the hominin lineage

PubMed Central

Pablos, Adrián; Stock, Jay T.

2017-01-01

Body size is a central determinant of a species' biology and adaptive strategy, but the number of reliable estimates of hominin body mass and stature have been insufficient to determine long-term patterns and subtle interactions in these size components within our lineage. Here, we analyse 254 body mass and 204 stature estimates from a total of 311 hominin specimens dating from 4.4 Ma to the Holocene using multi-level chronological and taxonomic analytical categories. The results demonstrate complex temporal patterns of body size variation with phases of relative stasis intermitted by periods of rapid increases. The observed trajectories could result from punctuated increases at speciation events, but also differential proliferation of large-bodied taxa or the extinction of small-bodied populations. Combined taxonomic and temporal analyses show that in relation to australopithecines, early Homo is characterized by significantly larger average body mass and stature but retains considerable diversity, including small body sizes. Within later Homo, stature and body mass evolution follow different trajectories: average modern stature is maintained from ca 1.6 Ma, while consistently higher body masses are not established until the Middle Pleistocene at ca 0.5–0.4 Ma, likely caused by directional selection related to colonizing higher latitudes. Selection against small-bodied individuals (less than 40 kg; less than 140 cm) after 1.4 Ma is associated with a decrease in relative size variability in later Homo species compared with earlier Homo and australopithecines. The isolated small-bodied individuals of Homo naledi (ca 0.3 Ma) and Homo floresiensis (ca 100–60 ka) constitute important exceptions to these general patterns, adding further layers of complexity to the evolution of body size within the genus Homo. At the end of the Late Pleistocene and Holocene, body size in Homo sapiens declines on average, but also extends to lower limits not seen in

Brief communication: Lumbar lordosis in extinct hominins: implications of the pelvic incidence.

PubMed

Been, Ella; Gómez-Olivencia, Asier; Kramer, Patricia A

2014-06-01

Recently, interest has peaked regarding the posture of extinct hominins. Here, we present a new method of reconstructing lordosis angles of extinct hominin specimens based on pelvic morphology, more specifically the orientation of the sacrum in relation to the acetabulum (pelvic incidence). Two regression models based on the correlation between pelvic incidence and lordosis angle in living hominoids have been developed. The mean values of the calculated lordosis angles based on these models are 36°-45° for australopithecines, 45°-47° for Homo erectus, 27°-34° for the Neandertals and the Sima de los Huesos hominins, and 49°-51° for fossil H. sapiens. The newly calculated lordosis values are consistent with previously published values of extinct hominins (Been et al.: Am J Phys Anthropol 147 (2012) 64-77). If the mean values of the present nonhuman hominoids are representative of the pelvic and lumbar morphology of the last common ancestor between humans and nonhuman hominoids, then both pelvic incidence and lordosis angle dramatically increased during hominin evolution from 27° ± 5 to 22° ± 3 (respectively) in nonhuman hominoids to 54° ± 10 and 51° ± 11 in modern humans. This change to a more human-like configuration appeared early in the hominin evolution as the pelvis and spines of both australopithecines and H. erectus show a higher pelvic incidence and lordosis angle than nonhuman hominoids. The Sima de los Huesos hominins and Neandertals show a derived configuration with a low pelvic incidence and lordosis angle. Copyright © 2014 Wiley Periodicals, Inc.

New dating evidence of the early presence of hominins in Southern Europe.

PubMed

Michel, Véronique; Shen, Chuan-Chou; Woodhead, Jon; Hu, Hsun-Ming; Wu, Chung-Che; Moullé, Pierre-Élie; Khatib, Samir; Cauche, Dominique; Moncel, Marie-Hélène; Valensi, Patricia; Chou, Yu-Min; Gallet, Sylvain; Echassoux, Anna; Orange, François; de Lumley, Henry

2017-08-30

The first "Out of Africa" migrations represent a seminal event in the history of humankind. At the gates of Europe, the first appearance of Hominins is recorded in Georgia, 1.8 million years ago (Ma); however, the picture of migration across the continent remains incomplete. Vallonnet Cave (France) is a Lower Paleolithic prehistoric site with traces of hominin activities including lithic remains and cut-marks on mammal bones. Here, we apply the uranium-lead (U-Pb) methods to two flowstones to date the intervening archaeological levels. The U-Pb data, coupled with paleomagnetic constraints, provide an age range from 1.2 to 1.1 Ma. The results conclusively demonstrate that Vallonnet Cave is one of the oldest European prehistoric sites in France with early hominin occupations associated with an Epivillafranchian fauna. Combined with data from other archaeological sites, the new precise chronology suggests a widespread occupation the Northern Mediterranean to Southwestern Europe at ~1.2 Ma.

New footprints from Laetoli (Tanzania) provide evidence for marked body size variation in early hominins

PubMed Central

Masao, Fidelis T; Ichumbaki, Elgidius B; Cherin, Marco; Barili, Angelo; Boschian, Giovanni; Iurino, Dawid A; Menconero, Sofia; Moggi-Cecchi, Jacopo; Manzi, Giorgio

2016-01-01

Laetoli is a well-known palaeontological locality in northern Tanzania whose outstanding record includes the earliest hominin footprints in the world (3.66 million years old), discovered in 1978 at Site G and attributed to Australopithecus afarensis. Here, we report hominin tracks unearthed in the new Site S at Laetoli and referred to two bipedal individuals (S1 and S2) moving on the same palaeosurface and in the same direction as the three hominins documented at Site G. The stature estimates for S1 greatly exceed those previously reconstructed for Au. afarensis from both skeletal material and footprint data. In combination with a comparative reappraisal of the Site G footprints, the evidence collected here embodies very important additions to the Pliocene record of hominin behaviour and morphology. Our results are consistent with considerable body size variation and, probably, degree of sexual dimorphism within a single species of bipedal hominins as early as 3.66 million years ago. DOI: http://dx.doi.org/10.7554/eLife.19568.001 PMID:27964778

Archaeogenomic insights into the adaptation of plants to the human environment: pushing plant-hominin co-evolution back to the Pliocene.

PubMed

Allaby, Robin G; Kistler, Logan; Gutaker, Rafal M; Ware, Roselyn; Kitchen, James L; Smith, Oliver; Clarke, Andrew C

2015-02-01

The colonization of the human environment by plants, and the consequent evolution of domesticated forms is increasingly being viewed as a co-evolutionary plant-human process that occurred over a long time period, with evidence for the co-evolutionary relationship between plants and humans reaching ever deeper into the hominin past. This developing view is characterized by a change in emphasis on the drivers of evolution in the case of plants. Rather than individual species being passive recipients of artificial selection pressures and ultimately becoming domesticates, entire plant communities adapted to the human environment. This evolutionary scenario leads to systems level genetic expectations from models that can be explored through ancient DNA and Next Generation Sequencing approaches. Emerging evidence suggests that domesticated genomes fit well with these expectations, with periods of stable complex evolution characterized by large amounts of change associated with relatively small selective value, punctuated by periods in which changes in one-half of the plant-hominin relationship cause rapid, low-complexity adaptation in the other. A corollary of a single plant-hominin co-evolutionary process is that clues about the initiation of the domestication process may well lie deep within the hominin lineage. Copyright © 2014 The Authors. Published by Elsevier Ltd.. All rights reserved.

The Hominin Sites and Paleolakes Drilling Project: inferring the environmental context of human evolution from eastern African rift lake deposits

NASA Astrophysics Data System (ADS)

Cohen, A.; Campisano, C.; Arrowsmith, R.; Asrat, A.; Behrensmeyer, A. K.; Deino, A.; Feibel, C.; Hill, A.; Johnson, R.; Kingston, J.; Lamb, H.; Lowenstein, T.; Noren, A.; Olago, D.; Owen, R. B.; Potts, R.; Reed, K.; Renaut, R.; Schäbitz, F.; Tiercelin, J.-J.; Trauth, M. H.; Wynn, J.; Ivory, S.; Brady, K.; O'Grady, R.; Rodysill, J.; Githiri, J.; Russell, J.; Foerster, V.; Dommain, R.; Rucina, S.; Deocampo, D.; Russell, J.; Billingsley, A.; Beck, C.; Dorenbeck, G.; Dullo, L.; Feary, D.; Garello, D.; Gromig, R.; Johnson, T.; Junginger, A.; Karanja, M.; Kimburi, E.; Mbuthia, A.; McCartney, T.; McNulty, E.; Muiruri, V.; Nambiro, E.; Negash, E. W.; Njagi, D.; Wilson, J. N.; Rabideaux, N.; Raub, T.; Sier, M. J.; Smith, P.; Urban, J.; Warren, M.; Yadeta, M.; Yost, C.; Zinaye, B.

2016-02-01

The role that climate and environmental history may have played in influencing human evolution has been the focus of considerable interest and controversy among paleoanthropologists for decades. Prior attempts to understand the environmental history side of this equation have centered around the study of outcrop sediments and fossils adjacent to where fossil hominins (ancestors or close relatives of modern humans) are found, or from the study of deep sea drill cores. However, outcrop sediments are often highly weathered and thus are unsuitable for some types of paleoclimatic records, and deep sea core records come from long distances away from the actual fossil and stone tool remains. The Hominin Sites and Paleolakes Drilling Project (HSPDP) was developed to address these issues. The project has focused its efforts on the eastern African Rift Valley, where much of the evidence for early hominins has been recovered. We have collected about 2 km of sediment drill core from six basins in Kenya and Ethiopia, in lake deposits immediately adjacent to important fossil hominin and archaeological sites. Collectively these cores cover in time many of the key transitions and critical intervals in human evolutionary history over the last 4 Ma, such as the earliest stone tools, the origin of our own genus Homo, and the earliest anatomically modern Homo sapiens. Here we document the initial field, physical property, and core description results of the 2012-2014 HSPDP coring campaign.

Oldest Evidence of Toolmaking Hominins in a Grassland-Dominated Ecosystem

PubMed Central

Plummer, Thomas W.; Ditchfield, Peter W.; Bishop, Laura C.; Kingston, John D.; Ferraro, Joseph V.; Braun, David R.; Hertel, Fritz; Potts, Richard

2009-01-01

Background Major biological and cultural innovations in late Pliocene hominin evolution are frequently linked to the spread or fluctuating presence of C4 grass in African ecosystems. Whereas the deep sea record of global climatic change provides indirect evidence for an increase in C4 vegetation with a shift towards a cooler, drier and more variable global climatic regime beginning approximately 3 million years ago (Ma), evidence for grassland-dominated ecosystems in continental Africa and hominin activities within such ecosystems have been lacking. Methodology/Principal Findings We report stable isotopic analyses of pedogenic carbonates and ungulate enamel, as well as faunal data from ∼2.0 Ma archeological occurrences at Kanjera South, Kenya. These document repeated hominin activities within a grassland-dominated ecosystem. Conclusions/Significance These data demonstrate what hitherto had been speculated based on indirect evidence: that grassland-dominated ecosystems did in fact exist during the Plio-Pleistocene, and that early Homo was active in open settings. Comparison with other Oldowan occurrences indicates that by 2.0 Ma hominins, almost certainly of the genus Homo, used a broad spectrum of habitats in East Africa, from open grassland to riparian forest. This strongly contrasts with the habitat usage of Australopithecus, and may signal an important shift in hominin landscape usage. PMID:19844568

Locomotion and posture from the common hominoid ancestor to fully modern hominins, with special reference to the last common panin/hominin ancestor

PubMed Central

Crompton, R H; Vereecke, E E; Thorpe, S K S

2008-01-01

Based on our knowledge of locomotor biomechanics and ecology we predict the locomotion and posture of the last common ancestors of (a) great and lesser apes and their close fossil relatives (hominoids); (b) chimpanzees, bonobos and modern humans (hominines); and (c) modern humans and their fossil relatives (hominins). We evaluate our propositions against the fossil record in the context of a broader review of evolution of the locomotor system from the earliest hominoids of modern aspect (crown hominoids) to early modern Homo sapiens. While some early East African stem hominoids were pronograde, it appears that the adaptations which best characterize the crown hominoids are orthogrady and an ability to abduct the arm above the shoulder – rather than, as is often thought, manual suspension sensu stricto. At 7–9 Ma (not much earlier than the likely 4–8 Ma divergence date for panins and hominins, see Bradley, 2008) there were crown hominoids in southern Europe which were adapted to moving in an orthograde posture, supported primarily on the hindlimb, in an arboreal, and possibly for Oreopithecus, a terrestrial context. By 7 Ma, Sahelanthropus provides evidence of a Central African hominin, panin or possibly gorilline adapted to orthogrady, and both orthogrady and habitually highly extended postures of the hip are evident in the arboreal East African protohominin Orrorin at 6 Ma. If the traditional idea that hominins passed through a terrestrial ‘knuckle-walking’ phase is correct, not only does it have to be explained how a quadrupedal gait typified by flexed postures of the hindlimb could have preadapted the body for the hominin acquisition of straight-legged erect bipedality, but we would have to accept a transition from stem-hominoid pronogrady to crown hominoid orthogrady, back again to pronogrady in the African apes and then back to orthogrady in hominins. Hand-assisted arboreal bipedality, which is part of a continuum of orthograde behaviours, is used by

Spinal cord evolution in early Homo.

PubMed

Meyer, Marc R; Haeusler, Martin

2015-11-01

The discovery at Nariokotome of the Homo erectus skeleton KNM-WT 15000, with a narrow spinal canal, seemed to show that this relatively large-brained hominin retained the primitive spinal cord size of African apes and that brain size expansion preceded postcranial neurological evolution. Here we compare the size and shape of the KNM-WT 15000 spinal canal with modern and fossil taxa including H. erectus from Dmanisi, Homo antecessor, the European middle Pleistocene hominins from Sima de los Huesos, and Pan troglodytes. In terms of shape and absolute and relative size of the spinal canal, we find all of the Dmanisi and most of the vertebrae of KNM-WT 15000 are within the human range of variation except for the C7, T2, and T3 of KNM-WT 15000, which are constricted, suggesting spinal stenosis. While additional fossils might definitively indicate whether H. erectus had evolved a human-like enlarged spinal canal, the evidence from the Dmanisi spinal canal and the unaffected levels of KNM-WT 15000 show that unlike Australopithecus, H. erectus had a spinal canal size and shape equivalent to that of modern humans. Subadult status is unlikely to affect our results, as spinal canal growth is complete in both individuals. We contest the notion that vertebrae yield information about respiratory control or language evolution, but suggest that, like H. antecessor and European middle Pleistocene hominins from Sima de los Huesos, early Homo possessed a postcranial neurological endowment roughly commensurate to modern humans, with implications for neurological, structural, and vascular improvements over Pan and Australopithecus. Copyright © 2015 Elsevier Ltd. All rights reserved.

Alternating high and low climate variability: The context of natural selection and speciation in Plio-Pleistocene hominin evolution.

PubMed

Potts, Richard; Faith, J Tyler

2015-10-01

Interaction of orbital insolation cycles defines a predictive model of alternating phases of high- and low-climate variability for tropical East Africa over the past 5 million years. This model, which is described in terms of climate variability stages, implies repeated increases in landscape/resource instability and intervening periods of stability in East Africa. It predicts eight prolonged (>192 kyr) eras of intensified habitat instability (high variability stages) in which hominin evolutionary innovations are likely to have occurred, potentially by variability selection. The prediction that repeated shifts toward high climate variability affected paleoenvironments and evolution is tested in three ways. In the first test, deep-sea records of northeast African terrigenous dust flux (Sites 721/722) and eastern Mediterranean sapropels (Site 967A) show increased and decreased variability in concert with predicted shifts in climate variability. These regional measurements of climate dynamics are complemented by stratigraphic observations in five basins with lengthy stratigraphic and paleoenvironmental records: the mid-Pleistocene Olorgesailie Basin, the Plio-Pleistocene Turkana and Olduvai Basins, and the Pliocene Tugen Hills sequence and Hadar Basin--all of which show that highly variable landscapes inhabited by hominin populations were indeed concentrated in predicted stages of prolonged high climate variability. Second, stringent null-model tests demonstrate a significant association of currently known first and last appearance datums (FADs and LADs) of the major hominin lineages, suites of technological behaviors, and dispersal events with the predicted intervals of prolonged high climate variability. Palynological study in the Nihewan Basin, China, provides a third test, which shows the occupation of highly diverse habitats in eastern Asia, consistent with the predicted increase in adaptability in dispersing Oldowan hominins. Integration of fossil, archeological

Carnivoran Remains from the Malapa Hominin Site, South Africa

PubMed Central

Kuhn, Brian F.; Werdelin, Lars; Hartstone-Rose, Adam; Lacruz, Rodrigo S.; Berger, Lee R.

2011-01-01

Recent discoveries at the new hominin-bearing deposits of Malapa, South Africa, have yielded a rich faunal assemblage associated with the newly described hominin taxon Australopithecus sediba. Dating of this deposit using U-Pb and palaeomagnetic methods has provided an age of 1.977 Ma, being one of the most accurately dated, time constrained deposits in the Plio-Pleistocene of southern Africa. To date, 81 carnivoran specimens have been identified at this site including members of the families Canidae, Viverridae, Herpestidae, Hyaenidae and Felidae. Of note is the presence of the extinct taxon Dinofelis cf. D. barlowi that may represent the last appearance date for this species. Extant large carnivores are represented by specimens of leopard (Panthera pardus) and brown hyaena (Parahyaena brunnea). Smaller carnivores are also represented, and include the genera Atilax and Genetta, as well as Vulpes cf. V. chama. Malapa may also represent the first appearance date for Felis nigripes (Black-footed cat). The geochronological age of Malapa and the associated hominin taxa and carnivoran remains provide a window of research into mammalian evolution during a relatively unknown period in South Africa and elsewhere. In particular, the fauna represented at Malapa has the potential to elucidate aspects of the evolution of Dinofelis and may help resolve competing hypotheses about faunal exchange between East and Southern Africa during the late Pliocene or early Pleistocene. PMID:22073222

Carnivoran remains from the Malapa hominin site, South Africa.

PubMed

Kuhn, Brian F; Werdelin, Lars; Hartstone-Rose, Adam; Lacruz, Rodrigo S; Berger, Lee R

2011-01-01

Recent discoveries at the new hominin-bearing deposits of Malapa, South Africa, have yielded a rich faunal assemblage associated with the newly described hominin taxon Australopithecus sediba. Dating of this deposit using U-Pb and palaeomagnetic methods has provided an age of 1.977 Ma, being one of the most accurately dated, time constrained deposits in the Plio-Pleistocene of southern Africa. To date, 81 carnivoran specimens have been identified at this site including members of the families Canidae, Viverridae, Herpestidae, Hyaenidae and Felidae. Of note is the presence of the extinct taxon Dinofelis cf. D. barlowi that may represent the last appearance date for this species. Extant large carnivores are represented by specimens of leopard (Panthera pardus) and brown hyaena (Parahyaena brunnea). Smaller carnivores are also represented, and include the genera Atilax and Genetta, as well as Vulpes cf. V. chama. Malapa may also represent the first appearance date for Felis nigripes (Black-footed cat). The geochronological age of Malapa and the associated hominin taxa and carnivoran remains provide a window of research into mammalian evolution during a relatively unknown period in South Africa and elsewhere. In particular, the fauna represented at Malapa has the potential to elucidate aspects of the evolution of Dinofelis and may help resolve competing hypotheses about faunal exchange between East and Southern Africa during the late Pliocene or early Pleistocene.

Landscapes of human evolution: models and methods of tectonic geomorphology and the reconstruction of hominin landscapes.

PubMed

Bailey, Geoffrey N; Reynolds, Sally C; King, Geoffrey C P

2011-03-01

This paper examines the relationship between complex and tectonically active landscapes and patterns of human evolution. We show how active tectonics can produce dynamic landscapes with geomorphological and topographic features that may be critical to long-term patterns of hominin land use, but which are not typically addressed in landscape reconstructions based on existing geological and paleoenvironmental principles. We describe methods of representing topography at a range of scales using measures of roughness based on digital elevation data, and combine the resulting maps with satellite imagery and ground observations to reconstruct features of the wider landscape as they existed at the time of hominin occupation and activity. We apply these methods to sites in South Africa, where relatively stable topography facilitates reconstruction. We demonstrate the presence of previously unrecognized tectonic effects and their implications for the interpretation of hominin habitats and land use. In parts of the East African Rift, reconstruction is more difficult because of dramatic changes since the time of hominin occupation, while fossils are often found in places where activity has now almost ceased. However, we show that original, dynamic landscape features can be assessed by analogy with parts of the Rift that are currently active and indicate how this approach can complement other sources of information to add new insights and pose new questions for future investigation of hominin land use and habitats. Copyright © 2010 Elsevier Ltd. All rights reserved.

The role of character displacement in the molarization of hominin mandibular premolars.

PubMed

Schroer, Kes; Wood, Bernard

2015-06-01

Closely related species are likely to experience resource competition in areas where their ranges overlap. Fossil evidence suggests that hominins in East Africa c. 2-1.5 million years ago may have lived synchronically and sympatrically, and that competition may have contributed to the different tooth sizes observed in Homo and Paranthropus. To assess the likelihood that these taxa overlapped, we applied a character displacement model to the postcanine tooth size of fossil hominins and validated this model in populations of living primates. Mandibular fourth premolar (P4 ) crown size was measured from fossil taxa and from living primate species where dietary overlap is established. Dimensions of the P4 crown were fitted to a character matrix and described as the response variables of a generalized linear model that took taxon and location as input variables. The model recovered significant divergence in samples of closely related, living primates. When applied to fossil hominins the same model detected strong indications of character displacement between early Homo and Paranthropus (P = 0.002) on the basis of their P4 crown size. Our study is an example of how ecologically informed morphologies measured in appropriate extant referents can provide a comparative context for assessing community and ecological evolution in the fossil record. © 2015 The Author(s). Evolution © 2015 The Society for the Study of Evolution.

A synthesis of Plio-Pleistocene leaf wax biomarker records of hydrological variation in East Africa and their relationship with hominin evolution

NASA Astrophysics Data System (ADS)

Lupien, R.; Russell, J. M.; Campisano, C. J.; Feibel, C. S.; Deino, A. L.; Kingston, J.; Potts, R.; Cohen, A. S.

2017-12-01

Climate change is thought to play a critical role in human evolution. However, the mechanisms behind this relationship are difficult to test due to a lack of long, high-quality paleoclimate records from hominin fossil locales. We improve the understanding of this relationship by examining Plio-Pleistocene lake sediment cores from East Africa that were drilled by the Hominin Sites and Paleolakes Drilling Project, an international effort to study the environment in which our hominin ancestors evolved and dispersed. We have analyzed organic geochemical signals of climate from drill cores from Ethiopia and Kenya spanning the Pliocene to recent time (from north to south: paleolake Hadar, Lake Turkana, Lake Baringo, and paleolake Koora). Specifically, we analyzed the hydrogen isotopic composition of terrestrial leaf waxes, which records changes in regional atmospheric circulation and hydrology. We reconstructed quantitative records of rainfall amount at each of the study sites, which host sediment spanning different geologic times and regions. By compiling these records, we test hominin evolutionary hypotheses as well as crucial questions about climate trend and variability. We find that there is a gradual or step-wise enrichment in δDwax, signifying a trend from a wet to dry climate, from the Pliocene to the Pleistocene, perhaps implying an influence of global temperature, ice sheet extent, and/or atmospheric greenhouse gas concentrations on East African climate. However, the shift is small relative to the amplitude of orbital-scale isotopic variations. The records indicate a strong influence of eccentricity-modulated orbital precession, and imply that local insolation effects are the likely cause of East African precipitation. Several of the intervals of high isotopic variability coincide with key hominin fossil or technological transitions, suggesting that climate variability plays a key role in hominin evolution.

Early hominins in north-west Europe: A punctuated long chronology?

NASA Astrophysics Data System (ADS)

Hosfield, Rob; Cole, James

2018-06-01

In light of changing views regarding the identity and evolutionary positions of Europe's Lower Palaeolithic hominins, a re-consideration of the hominin occupation of north-west Europe from c. 1 million years ago (mya) to c. 400 thousand years ago (kya) is timely. A change in the scale and character of the overall European Palaeolithic record around c. 800-600 kya has been well documented and argued over since the mid-1990s. Hominin expansion into the European north-west, potentially from southern Europe, Africa or south-western Asia, has been linked to the introduction of a new lithic technology in the form of the biface. We evaluate three potential drivers for this northern range expansion: changing palaeo-climatic conditions, the emergence of an essentially modern human life history, and greater hominin behavioural plasticity. Our evaluation suggests no major changes in these three factors during the c. 800-600 kya period other than enhanced behavioural plasticity suggested by the appearance of the biface. We offer here a model of hominin occupation for north-west Europe termed the 'punctuated long chronology' and suggest that the major changes in the European Lower Palaeolithic record that occur at a species-wide level may post-date, rather than precede, the Anglian Glaciation (marine isotope stage (MIS) 12).

Bovid mortality profiles in paleoecological context falsify hypotheses of endurance running-hunting and passive scavenging by early Pleistocene hominins

NASA Astrophysics Data System (ADS)

Bunn, Henry T.; Pickering, Travis Rayne

2010-11-01

The world's first archaeological traces from 2.6 million years ago (Ma) at Gona, in Ethiopia, include sharp-edged cutting tools and cut-marked animal bones, which indicate consumption of skeletal muscle by early hominin butchers. From that point, evidence of hominin meat-eating becomes increasingly more common throughout the Pleistocene archaeological record. Thus, the substantive debate about hominin meat-eating now centers on mode(s) of carcass resource acquisition. Two prominent hypotheses suggest, alternatively, (1) that early Homo hunted ungulate prey by running them to physiological failure and then dispatching them, or (2) that early Homo was relegated to passively scavenging carcass residues abandoned by carnivore predators. Various paleontologically testable predictions can be formulated for both hypotheses. Here we test four predictions concerning age-frequency distributions for bovids that contributed carcass remains to the 1.8 Ma. old FLK 22 Zinjanthropus (FLK Zinj, Olduvai Gorge, Tanzania) fauna, which zooarchaeological and taphonomic data indicate was formed predominantly by early Homo. In all but one case, the bovid mortality data from FLK Zinj violate test predictions of the endurance running-hunting and passive scavenging hypotheses. When combined with other taphonomic data, these results falsify both hypotheses, and lead to the hypothesis that early Homo operated successfully as an ambush predator.

Palaeoenvironmental evolution at Plio-Pleistocene Hominin sites in Western Kenya: Preliminary results

NASA Astrophysics Data System (ADS)

Vincent, Thomas; Whitfield, Elizabeth; Bishop, Laura; Plummer, Thomas; Ditchfield, Peter; Blumenthal, Scott; Finestone, Emma; Kiriakoulakis, Kostas

2017-04-01

This research uses a multiproxy approach to create detailed reconstructions of Plio-Pleistocene hominin landscapes and environments on the Homa Peninsula, western Kenya. Sedimentary sequences associated with this time period, containing hominin archaeological traces and faunal remains, are studied using analyses of particle size, phytoliths and lipid biomarkers. Reconstructing the palaeoenvironmental substrate here is critical in developing an understanding of the activity and behaviour of previous hominin inhabitants. Three archaeological sites exist in the region that form the bases of this research; these include Kanjera South, Nyayanga and Sare River. Research at Kanjera began in the early 20th century, but systematic investigation of the artefact and faunal assemblages of the southern exposures (Kanjera South), dating to ca. 2 Ma, did not begin until 1995. Field investigations and isotopic analyses of palaeosol carbonate nodules and fauna suggested that Kanjera South sediments were deposited in alluvial and lake marginal environments, on a grassy plain between wooded slopes and a permanent water body. Nyayanga and Sare River are new sites which have been little studied until present. Sediments at Nyayanga are thought to be ca. 2.6 Ma, whilst those at Sare River are ca. 1.77 Ma in age. This research refines previous reconstructions of the depositional environment at Kanjera South using analyses of particle size and end member mixing. These suggest that deposition occurred mainly through low-energy, ephemeral flows in a marginal lacustrine environment, with high energy, hyper-concentrated and viscous flows occurring intermittently. In contrast, these same techniques and field investigations at Nyayanga suggest there was a more consistent energy regime here than at Kanjera South, with sediments being deposited under low-energy conditions. Sediment samples at Sare River are undergoing similar analyses. Through detailed analyses of sediments at three archaeological

Social organization and the evolution of cumulative technology in apes and hominins.

PubMed

Pradhan, Gauri R; Tennie, Claudio; van Schaik, Carel P

2012-07-01

Culturally supported accumulation (or ratcheting) of technological complexity is widely seen as characterizing hominin technology relative to that of the extant great apes, and thus as representing a threshold in cultural evolution. To explain this divide, we modeled the process of cultural accumulation of technology, which we defined as adding new actions to existing ones to create new functional combinations, based on a model for great ape tool use. The model shows that intraspecific and interspecific variation in the presence of simple and cumulative technology among extant orangutans and chimpanzees is largely due to variation in sociability, and hence opportunities for social learning. The model also suggests that the adoption of extensive allomaternal care (cooperative breeding) in early Pleistocene Homo, which led to an increase in sociability and to teaching, and hence increased efficiency of social learning, was enough to facilitate technological ratcheting. Hence, socioecological changes, rather than advances in cognitive abilities, can account for the cumulative cultural changes seen until the origin of the Acheulean. The consequent increase in the reliance on technology could have served as the pacemaker for increased cognitive abilities. Our results also suggest that a more important watershed in cultural evolution was the rise of donated culture (technology or concepts), in which technology or concepts was transferred to naïve individuals, allowing them to skip many learning steps, and specialization arose, which allowed individuals to learn only a subset of the population's skills. Copyright © 2012 Elsevier Ltd. All rights reserved.

Shallow-water habitats as sources of fallback foods for hominins.

PubMed

Wrangham, Richard; Cheney, Dorothy; Seyfarth, Robert; Sarmiento, Esteban

2009-12-01

Underground storage organs (USOs) have been proposed as critical fallback foods for early hominins in savanna, but there has been little discussion as to which habitats would have been important sources of USOs. USOs consumed by hominins could have included both underwater and underground storage organs, i.e., from both aquatic and terrestrial habitats. Shallow aquatic habitats tend to offer high plant growth rates, high USO densities, and relatively continuous USO availability throughout the year. Baboons in the Okavango delta use aquatic USOs as a fallback food, and aquatic or semiaquatic USOs support high-density human populations in various parts of the world. As expected given fossilization requisites, the African early- to mid-Pleistocene shows an association of Homo and Paranthropus fossils with shallow-water and flooded habitats where high densities of plant-bearing USOs are likely to have occurred. Given that early hominins in the tropics lived in relatively dry habitats, while others occupied temperate latitudes, ripe, fleshy fruits of the type preferred by African apes would not normally have been available year round. We therefore suggest that water-associated USOs were likely to have been key fallback foods, and that dry-season access to aquatic habitats would have been an important predictor of hominin home range quality. This study differs from traditional savanna chimpanzee models of hominin origins by proposing that access to aquatic habitats was a necessary condition for adaptation to savanna habitats. It also raises the possibility that harvesting efficiency in shallow water promoted adaptations for habitual bipedality in early hominins.

Evolution of Siglec-11 and Siglec-16 Genes in Hominins

PubMed Central

Wang, Xiaoxia; Mitra, Nivedita; Cruz, Pedro; Deng, Liwen; Varki, Nissi; Angata, Takashi; Green, Eric D.; Mullikin, Jim; Hayakawa, Toshiyuki; Varki, Ajit

2012-01-01

We previously reported a human-specific gene conversion of SIGLEC11 by an adjacent paralogous pseudogene (SIGLEC16P), generating a uniquely human form of the Siglec-11 protein, which is expressed in the human brain. Here, we show that Siglec-11 is expressed exclusively in microglia in all human brains studied—a finding of potential relevance to brain evolution, as microglia modulate neuronal survival, and Siglec-11 recruits SHP-1, a tyrosine phosphatase that modulates microglial biology. Following the recent finding of a functional SIGLEC16 allele in human populations, further analysis of the human SIGLEC11 and SIGLEC16/P sequences revealed an unusual series of gene conversion events between two loci. Two tandem and likely simultaneous gene conversions occurred from SIGLEC16P to SIGLEC11 with a potentially deleterious intervening short segment happening to be excluded. One of the conversion events also changed the 5′ untranslated sequence, altering predicted transcription factor binding sites. Both of the gene conversions have been dated to ∼1–1.2 Ma, after the emergence of the genus Homo, but prior to the emergence of the common ancestor of Denisovans and modern humans about 800,000 years ago, thus suggesting involvement in later stages of hominin brain evolution. In keeping with this, recombinant soluble Siglec-11 binds ligands in the human brain. We also address a second-round more recent gene conversion from SIGLEC11 to SIGLEC16, with the latter showing an allele frequency of ∼0.1–0.3 in a worldwide population study. Initial pseudogenization of SIGLEC16 was estimated to occur at least 3 Ma, which thus preceded the gene conversion of SIGLEC11 by SIGLEC16P. As gene conversion usually disrupts the converted gene, the fact that ORFs of hSIGLEC11 and hSIGLEC16 have been maintained after an unusual series of very complex gene conversion events suggests that these events may have been subject to hominin-specific selection forces. PMID:22383531

Evidence of fatal skeletal injuries on Malapa Hominins 1 and 2

PubMed Central

L’Abbé, Ericka N.; Symes, Steven A.; Pokines, James T.; Cabo, Luis L.; Stull, Kyra E.; Kuo, Sharon; Raymond, David E.; Randolph-Quinney, Patrick S.; Berger, Lee R.

2015-01-01

Malapa is one of the richest early hominin sites in Africa and the discovery site of the hominin species, Australopithecus sediba. The holotype and paratype (Malapa Hominin 1 and 2, or MH1 and MH2, respectively) skeletons are among the most complete in the early hominin record. Dating to approximately two million years BP, MH1 and MH2 are hypothesized to have fallen into a natural pit trap. All fractures evident on MH1 and MH2 skeletons were evaluated and separated based on wet and dry bone fracture morphology/characteristics. Most observed fractures are post-depositional, but those in the right upper limb of the adult hominin strongly indicate active resistance to an impact, while those in the juvenile hominin mandible are consistent with a blow to the face. The presence of skeletal trauma independently supports the falling hypothesis and supplies the first evidence for the manner of death of an australopith in the fossil record that is not attributed to predation or natural death. PMID:26459912

Luminescence dating and palaeomagnetic age constraint on hominins from Sima de los Huesos, Atapuerca, Spain.

PubMed

Arnold, Lee J; Demuro, Martina; Parés, Josep M; Arsuaga, Juan Luis; Aranburu, Arantza; Bermúdez de Castro, José María; Carbonell, Eudald

2014-02-01

Establishing a reliable chronology on the extensive hominin remains at Sima de los Huesos is critical for an improved understanding of the complex evolutionary histories and phylogenetic relationships of the European Middle Pleistocene hominin record. In this study, we use a combination of 'extended-range' luminescence dating techniques and palaeomagnetism to provide new age constraint on sedimentary infills that are unambiguously associated with the Sima fossil assemblage. Post-infrared-infrared stimulated luminescence (pIR-IR) dating of K-feldspars and thermally transferred optically stimulated luminescence (TT-OSL) dating of individual quartz grains provide weighted mean ages of 433 ± 15 ka (thousands of years) and 416 ± 19 ka, respectively, for allochthonous sedimentary horizons overlying the hominin-bearing clay breccia. The six replicate luminescence ages obtained for this deposit are reproducible and provide a combined minimum age estimate of 427 ± 12 ka for the underlying hominin fossils. Palaeomagnetic directions for the luminescence dated sediment horizon and underlying fossiliferous clays display exclusively normal polarities. These findings are consistent with the luminescence dating results and confirm that the hominin fossil horizon accumulated during the Brunhes Chron, i.e., within the last 780 ka. The new bracketing age constraint for the Sima hominins is in broad agreement with radiometrically dated Homo heidelbergensis fossil sites, such as Mauer and Arago, and suggests that the split of the H. neanderthalensis and H. sapiens lineages took place during the early Middle Pleistocene. More widespread numerical dating of key Early and Middle Pleistocene fossil sites across Europe is needed to test and refine competing models of hominin evolution. The new luminescence chronologies presented in this study demonstrate the versatility of TT-OSL and pIR-IR techniques and the potential role they could play in helping to refine evolutionary

The evolution of body size and shape in the human career.

PubMed

Jungers, William L; Grabowski, Mark; Hatala, Kevin G; Richmond, Brian G

2016-07-05

Body size is a fundamental biological property of organisms, and documenting body size variation in hominin evolution is an important goal of palaeoanthropology. Estimating body mass appears deceptively simple but is laden with theoretical and pragmatic assumptions about best predictors and the most appropriate reference samples. Modern human training samples with known masses are arguably the 'best' for estimating size in early bipedal hominins such as the australopiths and all members of the genus Homo, but it is not clear if they are the most appropriate priors for reconstructing the size of the earliest putative hominins such as Orrorin and Ardipithecus The trajectory of body size evolution in the early part of the human career is reviewed here and found to be complex and nonlinear. Australopith body size varies enormously across both space and time. The pre-erectus early Homo fossil record from Africa is poor and dominated by relatively small-bodied individuals, implying that the emergence of the genus Homo is probably not linked to an increase in body size or unprecedented increases in size variation. Body size differences alone cannot explain the observed variation in hominin body shape, especially when examined in the context of small fossil hominins and pygmy modern humans.This article is part of the themed issue 'Major transitions in human evolution'. © 2016 The Author(s).

Retrieving chronological age from dental remains of early fossil hominins to reconstruct human growth in the past.

PubMed

Dean, M Christopher

2010-10-27

A chronology of dental development in Pan troglodytes is arguably the best available model with which to compare and contrast reconstructed dental chronologies of the earliest fossil hominins. Establishing a time scale for growth is a requirement for being able to make further comparative observations about timing and rate during both dento-skeletal growth and brain growth. The absolute timing of anterior tooth crown and root formation appears not to reflect the period of somatic growth. In contrast, the molar dentition best reflects changes to the total growth period. Earlier initiation of molar mineralization, shorter crown formation times, less root length formed at gingival emergence into functional occlusion are cumulatively expressed as earlier ages at molar eruption. Things that are similar in modern humans and Pan, such as the total length of time taken to form individual teeth, raise expectations that these would also have been the same in fossil hominins. The best evidence there is from the youngest fossil hominin specimens suggests a close resemblance to the model for Pan but also hints that Gorilla may be a better developmental model for some. A mosaic of great ape-like features currently best describes the timing of early hominin dental development.

Retrieving chronological age from dental remains of early fossil hominins to reconstruct human growth in the past

PubMed Central

Dean, M. Christopher

2010-01-01

A chronology of dental development in Pan troglodytes is arguably the best available model with which to compare and contrast reconstructed dental chronologies of the earliest fossil hominins. Establishing a time scale for growth is a requirement for being able to make further comparative observations about timing and rate during both dento-skeletal growth and brain growth. The absolute timing of anterior tooth crown and root formation appears not to reflect the period of somatic growth. In contrast, the molar dentition best reflects changes to the total growth period. Earlier initiation of molar mineralization, shorter crown formation times, less root length formed at gingival emergence into functional occlusion are cumulatively expressed as earlier ages at molar eruption. Things that are similar in modern humans and Pan, such as the total length of time taken to form individual teeth, raise expectations that these would also have been the same in fossil hominins. The best evidence there is from the youngest fossil hominin specimens suggests a close resemblance to the model for Pan but also hints that Gorilla may be a better developmental model for some. A mosaic of great ape-like features currently best describes the timing of early hominin dental development. PMID:20855313

Complex Tasks Force Hand Laterality and Technological Behaviour in Naturalistically Housed Chimpanzees: Inferences in Hominin Evolution

PubMed Central

Mosquera, M.; Geribàs, N.; Bargalló, A.; Llorente, M.; Riba, D.

2012-01-01

Clear hand laterality patterns in humans are widely accepted. However, humans only elicit a significant hand laterality pattern when performing complementary role differentiation (CRD) tasks. Meanwhile, hand laterality in chimpanzees is weaker and controversial. Here we have reevaluated our results on hand laterality in chimpanzees housed in naturalistic environments at Fundació Mona (Spain) and Chimfunshi Wild Orphanage (Zambia). Our results show that the difference between hand laterality in humans and chimpanzees is not as great as once thought. Furthermore, we found a link between hand laterality and task complexity and also an even more interesting connection: CRD tasks elicited not only the hand laterality but also the use of tools. This paper aims to turn attention to the importance of this threefold connection in human evolution: the link between CRD tasks, hand laterality, and tool use, which has important evolutionary implications that may explain the development of complex behaviour in early hominins. PMID:22550466

Complex tasks force hand laterality and technological behaviour in naturalistically housed chimpanzees: inferences in hominin evolution.

PubMed

Mosquera, M; Geribàs, N; Bargalló, A; Llorente, M; Riba, D

2012-01-01

Clear hand laterality patterns in humans are widely accepted. However, humans only elicit a significant hand laterality pattern when performing complementary role differentiation (CRD) tasks. Meanwhile, hand laterality in chimpanzees is weaker and controversial. Here we have reevaluated our results on hand laterality in chimpanzees housed in naturalistic environments at Fundació Mona (Spain) and Chimfunshi Wild Orphanage (Zambia). Our results show that the difference between hand laterality in humans and chimpanzees is not as great as once thought. Furthermore, we found a link between hand laterality and task complexity and also an even more interesting connection: CRD tasks elicited not only the hand laterality but also the use of tools. This paper aims to turn attention to the importance of this threefold connection in human evolution: the link between CRD tasks, hand laterality, and tool use, which has important evolutionary implications that may explain the development of complex behaviour in early hominins.

An updated age for the Xujiayao hominin from the Nihewan Basin, North China: implications for Middle Pleistocene human evolution in East Asia

NASA Astrophysics Data System (ADS)

Ao, H.

2017-12-01

With an inventory of >60 early Paleolithic sites, >100,000 in situ stone tools, and tons of mammal fossils, the Nihewan Basin in North China is one of the most important Paleolithic areas in East Asia. The Xujiayao site in the northwestern margin of Nihewan Basin is one of the most important Paleolithic sites worldwide. Twenty archaic Homo fossils have been excavated along with more than 30,000 lithic artifacts and 5000 mammalian fossil specimens. Dating of the Xujiayao hominin has been pursued since its excavation in the 1970s, but its age has remained controversial because of limitations of the previous dating techniques that have been applied to available materials. Here, we report new ages for the Xujiayao hominin based on combined electron spin resonance (ESR) dating of quartz in the sediments and high-resolution magnetostratigraphy of the fluvio-lacustrine sequence. The magnetostratigraphy suggests that the upper Matuyama and Brunhes polarity chrons are recorded at Xujiayao. The ESR dating results indicate a pooled average age of 260, 370 ka for the Homo-bearing layer, which is consistent with its position within the middle Brunhes normal polarity chron indicated by magnetostratigraphy. This age estimate makes the Xujiayao hominin among the oldest mid-Pleistocene hominins with derived Neanderthal traits in East Asia. Our updated age and the Neanderthal-like traits of the Xujiayao Homo fossils, particularly the Denisovan-like molar teeth, make it possible that the Xujiayao hominin could represent an early Denisovan, a sister group of Neanderthals. If this Homo species affiliation is documented by DNA study, it will imply that Neanderthals expanded to East Asia as early as 370 ka, just 60 ka after the origin of Neanderthals in West Europe at 430 ka, and then they further involved into typical Denisovans under local climatic and demographic pressure.

Mosaic evolution and the pattern of transitions in the hominin lineage.

PubMed

Foley, Robert A

2016-07-05

Humans are uniquely unique, in terms of the extreme differences between them and other living organisms, and the impact they are having on the biosphere. The evolution of humans can be seen, as has been proposed, as one of the major transitions in evolution, on a par with the origins of multicellular organisms or the eukaryotic cell (Maynard Smith & Szathmáry 1997 Major transitions in evolution). Major transitions require the evolution of greater complexity and the emergence of new evolutionary levels or processes. Does human evolution meet these conditions? I explore the diversity of evidence on the nature of transitions in human evolution. Four levels of transition are proposed-baseline, novel taxa, novel adaptive zones and major transitions-and the pattern of human evolution considered in the light of these. The primary conclusions are that changes in human evolution occur continuously and cumulatively; that novel taxa and the appearance of new adaptations are not clustered very tightly in particular periods, although there are three broad transitional phases (Pliocene, Plio-Pleistocene and later Quaternary). Each phase is distinctive, with the first based on ranging and energetics, the second on technology and niche expansion, and the third on cognition and cultural processes. I discuss whether this constitutes a 'major transition' in the context of the evolutionary processes more broadly; the role of behaviour in evolution; and the opportunity provided by the rich genetic, phenotypic (fossil morphology) and behavioural (archaeological) record to examine in detail major transitions and the microevolutionary patterns underlying macroevolutionary change. It is suggested that the evolution of the hominin lineage is consistent with a mosaic pattern of change.This article is part of the themed issue 'Major transitions in human evolution'. © 2016 The Author(s).

Geological and edaphic constraints on early hominin landscape exploitation in the Kenya Rift

NASA Astrophysics Data System (ADS)

Kuebler, S.; King, G. C. P.; Rucina, S.

2017-12-01

Our study in the Kenya Rift shows that soil edaphics and active rift structures play a key role in present day animal movements as well as the for the location of early hominin sites. Based on studying the relationship between the geology, tectonics and soil development we identified 'good' and 'bad' regions both in terms of edaphics and accessibility for grazing animals. We created palaeoenvironmental reconstructions for interpreting human land use and exploitation of large mammals in the Kenya Rift for the relevant time frame of 1 Ma BP. At Olorgesailie the hominin site is located in lacustrine sediments at the southern edge of a playa that extends north and northwest of Mt. Olorgesailie. Lakebeds are now tilted and eroded by motion on two north-south striking faults. The lake was trapped by volcanic flows and alluvial fans from Mt. Olorgesailie and was released by fault motion leading to deep river incision and exposure of the site. To the west and the north steep fault scarps bound the playa forming a natural barrier for animals. Field observations and information from local shepherds suggest that the abundant trachytes at the valley floor produce poor soils whereas the soils developed on lacustrine and alluvial sediments close to the hominin site provide much more attractive grazing sites for present-day animals. This is supported by our soil analysis. With a lake in the past the Olorgesailie site represents an key example of how early hominins may have used the landscape for their strategic advantage. At Kariandusi site we investigated the tectonic and volcanic history of the region, and the system of lakes that have undergone periodic expansion and contraction during the Pleistocene in response to climatic and tectonic controls. We used this information to reconstruct topographic features as they would have existed at different periods of the past and their likely influence on patterns of large-mammal movements, and linked this with information from soil

Ichnotaxonomy of the Laetoli trackways: The earliest hominin footprints

NASA Astrophysics Data System (ADS)

Meldrum, D. J.; Lockley, Martin G.; Lucas, Spencer G.; Musiba, Charles

2011-04-01

At 3.6 Ma, the Laetoli Pliocene hominin trackways are the earliest direct evidence of hominin bipedalism. Three decades since their discovery, not only is the question of their attribution still discussed, but marked differences in interpretation concerning the footprints' qualitative features and the inferred nature of the early hominin foot morphology remain. Here, we establish a novel ichnotaxon, Praehominipes laetoliensis, for these tracks and clarify the distinctions of these footprints from those of later hominins, especially modern humans. We also contrast hominin, human, and ape footprints to establish morphological features of these footprints correlated with a midtarsal break versus a stiff longitudinal arch. Original photos, including stereo photographs, and casts of footprints from the 1978 Laetoli excavation, confirm midtarsal flexibility, and repeatedly indicate an associated midfoot pressure ridge. In contrast, the modern human footprint reflects the derived arched-foot architecture, combined with a stiff-legged striding gait. Fossilized footprints of unshod modern human pedestrians in Hawaii and Nicaragua unambiguously illustrate these contrasts. Some points of comparisons with ape footprints are complicated by a variable hallucal position and the distinct manner of ape facultative bipedalism. In contrast to the comparatively rigid platform of the modern human foot, midtarsal flexibility is present in the chimpanzee foot. In ape locomotion, flexion at the transverse tarsal joint, referred to as the "midtarsal break," uncouples the respective functions of the prehensile forefoot and the propulsive hindfoot during grasp-climbing. At some point after the transition to habitual bipedalism, these grasp-climb adaptations, presumed to be present in the last common ancestor of apes and humans, were initially compromised by the loss of divergence of the hallux. An analogous trajectory is evident along an array of increasingly terrestrial extant ape species

A fish is not a fish: patterns in fatty acid composition of aquatic food may have had implications for hominin evolution.

PubMed

Joordens, Josephine C A; Kuipers, Remko S; Wanink, Jan H; Muskiet, Frits A J

2014-12-01

From c. 2 Ma (millions of years ago) onwards, hominin brain size and cognition increased in an unprecedented fashion. The exploitation of high-quality food resources, notably from aquatic ecosystems, may have been a facilitator or driver of this phenomenon. The aim of this study is to contribute to the ongoing debate on the possible role of aquatic resources in hominin evolution by providing a more detailed nutritional context. So far, the debate has focused on the relative importance of terrestrial versus aquatic resources while no distinction has been made between different types of aquatic resources. Here we show that Indian Ocean reef fish and eastern African lake fish yield on average similarly high amounts of eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and arachidonic acid (AA). Hence a shift from exploiting tropical marine to freshwater ecosystems (or vice versa) would entail no material difference in dietary long-chain polyunsaturated fatty acid (LC-PUFA) availability. However, a shift to marine ecosystems would likely mean a major increase in access to brain-selective micronutrients such as iodine. Fatty fish from marine temperate/cold waters yield twice as much DHA and four times as much EPA as tropical fish, demonstrating that a latitudinal shift in exploitation of African coastal ecosystems could constitute a significant difference in LC-PUFA availability with possible implications for brain development and functioning. We conclude that exploitation of aquatic food resources could have facilitated the initial moderate hominin brain increase as observed in fossils dated to c. 2 Ma, but not the exceptional brain increase in later stages of hominin evolution. We propose that the significant expansion in hominin brain size and cognition later on may have been aided by strong directional selecting forces such as runaway sexual selection of intelligence, and nutritionally supported by exploitation of high-quality food resources in stable and

Mosaic evolution and the pattern of transitions in the hominin lineage

PubMed Central

Foley, Robert A.

2016-01-01

Humans are uniquely unique, in terms of the extreme differences between them and other living organisms, and the impact they are having on the biosphere. The evolution of humans can be seen, as has been proposed, as one of the major transitions in evolution, on a par with the origins of multicellular organisms or the eukaryotic cell (Maynard Smith & Szathmáry 1997 Major transitions in evolution). Major transitions require the evolution of greater complexity and the emergence of new evolutionary levels or processes. Does human evolution meet these conditions? I explore the diversity of evidence on the nature of transitions in human evolution. Four levels of transition are proposed—baseline, novel taxa, novel adaptive zones and major transitions—and the pattern of human evolution considered in the light of these. The primary conclusions are that changes in human evolution occur continuously and cumulatively; that novel taxa and the appearance of new adaptations are not clustered very tightly in particular periods, although there are three broad transitional phases (Pliocene, Plio-Pleistocene and later Quaternary). Each phase is distinctive, with the first based on ranging and energetics, the second on technology and niche expansion, and the third on cognition and cultural processes. I discuss whether this constitutes a ‘major transition’ in the context of the evolutionary processes more broadly; the role of behaviour in evolution; and the opportunity provided by the rich genetic, phenotypic (fossil morphology) and behavioural (archaeological) record to examine in detail major transitions and the microevolutionary patterns underlying macroevolutionary change. It is suggested that the evolution of the hominin lineage is consistent with a mosaic pattern of change. This article is part of the themed issue ‘Major transitions in human evolution’. PMID:27298474

Vertebral numbers and human evolution.

PubMed

Williams, Scott A; Middleton, Emily R; Villamil, Catalina I; Shattuck, Milena R

2016-01-01

Ever since Tyson (1699), anatomists have noted and compared differences in the regional numbers of vertebrae among humans and other hominoids. Subsequent workers interpreted these differences in phylogenetic, functional, and behavioral frameworks and speculated on the history of vertebral numbers during human evolution. Even in a modern phylogenetic framework and with greatly expanded sample sizes of hominoid species, researchers' conclusions vary drastically, positing that hominins evolved from either a "long-backed" (numerically long lumbar column) or a "short-backed" (numerically short lumbar column) ancestor. We show that these disparate interpretations are due in part to the use of different criteria for what defines a lumbar vertebra, but argue that, regardless of which lumbar definition is used, hominins are similar to their great ape relatives in possessing a short trunk, a rare occurrence in mammals and one that defines the clade Hominoidea. Furthermore, we address the recent claim that the early hominin thoracolumbar configuration is not distinct from that of modern humans and conclude that early hominins show evidence of "cranial shifting," which might explain the anomalous morphology of several early hominin fossils. Finally, we evaluate the competing hypotheses on numbers of vertebrae and argue that the current data support a hominin ancestor with an African ape-like short trunk and lower back. © 2016 Wiley Periodicals, Inc.

Early Human Evolution in the Western Palaearctic: Ecological Scenarios

NASA Astrophysics Data System (ADS)

Carrión, José S.; Rose, James; Stringer, Chris

2011-06-01

This review presents the themes of a special issue dealing with environmental scenarios of human evolution during the Early Pleistocene (2.6-0.78 Ma; MIS 103-MIS 19) and early Middle Pleistocene (0.78-0.47 Ma; MIS 19-base of MIS 12) within the western Palaearctic. This period is one of dramatic changes in the climates and the distribution of Palaearctic biota. These changes have played their role in generating adaptive and phyletic patterns within the human ancestry, involving several species such as Homo habilis, "Homo georgicus", Homo erectus, Homo antecessor and Homo heidelbergensis. In the archaeological record, these species include the Oldowan (Mode 1) and Acheulian (Mode 2) lithic technologies. Taphonomic considerations of palaeoecological research in hominin-bearing sites are provided and evaluated. Syntheses are provided for north Africa, western Asia, the Mediterranean Basin, Britain, and continental Europe. Palaeoenvironmental reconstructions based on multidisciplinary data are given for Ain Boucherit, Ain Hanech and El-Kherba in Algeria, Dmanisi in Georgia, Atapuerca, Cueva Negra, and the Orce Basin in Spain, Monte Poggiolo and Pirro Nord in Italy, Pont-de-Lavaud in France, and Mauer in Germany. The state of the art with the Out of Africa 1 dispersal model is reviewed. A source-sink dynamics model for Palaeolithic Europe is described to explain the morphological disparity of H. heidelbergensis (we will sometimes use the informal name "Heidelbergs") and early Neanderthals. Other aspects debated here are the selective value of habitat mosaics including reconstructions based on mammal and avian databases, and the role of geological instability combined with topographic complexity. This review is completed by addressing the question of whether the appearance of evolutionary trends within hominins is concentrated in regions of highest worldwide biological diversity (biodiversity hotspots). It is concluded that the keys for the activation of evolutionary

New Middle Pleistocene hominin cranium from Gruta da Aroeira (Portugal).

PubMed

Daura, Joan; Sanz, Montserrat; Arsuaga, Juan Luis; Hoffmann, Dirk L; Quam, Rolf M; Ortega, María Cruz; Santos, Elena; Gómez, Sandra; Rubio, Angel; Villaescusa, Lucía; Souto, Pedro; Mauricio, João; Rodrigues, Filipa; Ferreira, Artur; Godinho, Paulo; Trinkaus, Erik; Zilhão, João

2017-03-28

The Middle Pleistocene is a crucial time period for studying human evolution in Europe, because it marks the appearance of both fossil hominins ancestral to the later Neandertals and the Acheulean technology. Nevertheless, European sites containing well-dated human remains associated with an Acheulean toolkit remain scarce. The earliest European hominin crania associated with Acheulean handaxes are at the sites of Arago, Atapuerca Sima de los Huesos (SH), and Swanscombe, dating to 400-500 ka (Marine Isotope Stage 11-12). The Atapuerca (SH) fossils and the Swanscombe cranium belong to the Neandertal clade, whereas the Arago hominins have been attributed to an incipient stage of Neandertal evolution, to Homo heidelbergensis , or to a subspecies of Homo erectus A recently discovered cranium (Aroeira 3) from the Gruta da Aroeira (Almonda karst system, Portugal) dating to 390-436 ka provides important evidence on the earliest European Acheulean-bearing hominins. This cranium is represented by most of the right half of a calvarium (with the exception of the missing occipital bone) and a fragmentary right maxilla preserving part of the nasal floor and two fragmentary molars. The combination of traits in the Aroeira 3 cranium augments the previously documented diversity in the European Middle Pleistocene fossil record.

New Middle Pleistocene hominin cranium from Gruta da Aroeira (Portugal)

PubMed Central

Daura, Joan; Sanz, Montserrat; Arsuaga, Juan Luis; Hoffmann, Dirk L.; Quam, Rolf M.; Ortega, María Cruz; Santos, Elena; Gómez, Sandra; Rubio, Angel; Villaescusa, Lucía; Souto, Pedro; Mauricio, João; Rodrigues, Filipa; Ferreira, Artur; Godinho, Paulo; Trinkaus, Erik

2017-01-01

The Middle Pleistocene is a crucial time period for studying human evolution in Europe, because it marks the appearance of both fossil hominins ancestral to the later Neandertals and the Acheulean technology. Nevertheless, European sites containing well-dated human remains associated with an Acheulean toolkit remain scarce. The earliest European hominin crania associated with Acheulean handaxes are at the sites of Arago, Atapuerca Sima de los Huesos (SH), and Swanscombe, dating to 400–500 ka (Marine Isotope Stage 11–12). The Atapuerca (SH) fossils and the Swanscombe cranium belong to the Neandertal clade, whereas the Arago hominins have been attributed to an incipient stage of Neandertal evolution, to Homo heidelbergensis, or to a subspecies of Homo erectus. A recently discovered cranium (Aroeira 3) from the Gruta da Aroeira (Almonda karst system, Portugal) dating to 390–436 ka provides important evidence on the earliest European Acheulean-bearing hominins. This cranium is represented by most of the right half of a calvarium (with the exception of the missing occipital bone) and a fragmentary right maxilla preserving part of the nasal floor and two fragmentary molars. The combination of traits in the Aroeira 3 cranium augments the previously documented diversity in the European Middle Pleistocene fossil record. PMID:28289213

Inferences regarding the diet of extinct hominins: structural and functional trends in dental and mandibular morphology within the hominin clade

PubMed Central

Lucas, Peter W; Constantino, Paul J; Wood, Bernard A

2008-01-01

This contribution investigates the evolution of diet in the Pan–Homo and hominin clades. It does this by focusing on 12 variables (nine dental and three mandibular) for which data are available about extant chimpanzees, modern humans and most extinct hominins. Previous analyses of this type have approached the interpretation of dental and gnathic function by focusing on the identification of the food consumed (i.e. fruits, leaves, etc.) rather than on the physical properties (i.e. hardness, toughness, etc.) of those foods, and they have not specifically addressed the role that the physical properties of foods play in determining dental adaptations. We take the available evidence for the 12 variables, and set out what the expression of each of those variables is in extant chimpanzees, the earliest hominins, archaic hominins, megadont archaic hominins, and an inclusive grouping made up of transitional hominins and pre-modern Homo. We then present hypotheses about what the states of these variables would be in the last common ancestor of the Pan–Homo clade and in the stem hominin. We review the physical properties of food and suggest how these physical properties can be used to investigate the functional morphology of the dentition. We show what aspects of anterior tooth morphology are critical for food preparation (e.g. peeling fruit) prior to its ingestion, which features of the postcanine dentition (e.g. overall and relative size of the crowns) are related to the reduction in the particle size of food, and how information about the macrostructure (e.g. enamel thickness) and microstructure (e.g. extent and location of enamel prism decussation) of the enamel cap might be used to make predictions about the types of foods consumed by extinct hominins. Specifically, we show how thick enamel can protect against the generation and propagation of cracks in the enamel that begin at the enamel–dentine junction and move towards the outer enamel surface. PMID:18380867

Dental evidence on the hominin dispersals during the Pleistocene

PubMed Central

Martinón-Torres, M.; Bermúdez de Castro, J. M.; Gómez-Robles, A.; Arsuaga, J. L.; Carbonell, E.; Lordkipanidze, D.; Manzi, G.; Margvelashvili, A.

2007-01-01

A common assumption in the evolutionary scenario of the first Eurasian hominin populations is that they all had an African origin. This assumption also seems to apply for the Early and Middle Pleistocene populations, whose presence in Europe has been largely explained by a discontinuous flow of African emigrant waves. Only recently, some voices have speculated about the possibility of Asia being a center of speciation. However, no hard evidence has been presented to support this hypothesis. We present evidence from the most complete and up-to-date analysis of the hominin permanent dentition from Africa and Eurasia. The results show important morphological differences between the hominins found in both continents during the Pleistocene, suggesting that their evolutionary courses were relatively independent. We propose that the genetic impact of Asia in the colonization of Europe during the Early and Middle Pleistocene was stronger than that of Africa. PMID:17684093

Hydrologic and Agent-based Modelling of Hydro-refugia in East Africa, Insights into the Importance of Water Resources in Hominin Evolution and Dispersal

NASA Astrophysics Data System (ADS)

Ashley, G. M.; Cuthbert, M. O.; Gleeson, T. P.; Reynolds, S. R.; Bennett, M. R.; Newton, A. C.; McCormack, C. J.

2017-12-01

Hominin evolution and climate variability have often been linked because of the apparent coincidence of climate fluctuations and speciation or extinctions, although the cause and effect of climate on natural selection is not clear. Climate in the EARS (East African Rift System) where most hominin first occurrences are located experienced an overall drying over the last 7 myr. Superimposed on this trend, Milankovitch cycles generated wet-dry precession cycles ( 23 kyr) that changed both water and food resource availability. During dry periods, lakes became more alkaline and rivers ephemeral but, groundwater, buffered from surface climate effects, remained a potential resource during the driest of times. The possibility of widespread groundwater sources hydro-refugia, such as springs, wetlands and groundwater-fed perennial streams has received little attention with respect to the paleoenvironmental context of hominin evolution or dispersal. We demonstrate that hydrogeological modelling of the modern landscape in East Africa coupled with ABM (agent-based modelling) of hominin movement yields new insight into potential correlates of hominin survival and dispersal. Digitized hydrological mapping of present day rivers, lakes and springs along the EARS (2000 km) from northern Tanzania to Ethiopia provided the modelling framework. Present day conditions are considered analogous to past dry periods; wet period conditions are an expanded hydrologic network including all surface water bodies. Our focus was on perennial springs discharging at 1,000 m3/y (volume to sustain a small wetland). 450 such springs occur and were found to be significantly controlled by geology, not just climate. The ABM was designed to determine if it was possible for humans to walk between hydro-refugia in 3 days. Four climate scenarios were run on ABM: wet, wet-to-dry, dry and dry-to-wet. During dry periods our results suggest that groundwater availability would have been critical to supporting

Interpreting sulci on hominin endocasts: old hypotheses and new findings

PubMed Central

Falk, Dean

2014-01-01

Paleoneurologists analyze internal casts (endocasts) of fossilized braincases, which provide information about the size, shape and, to a limited degree, sulcal patterns reproduced from impressions left by the surface of the brain. When interpreted in light of comparative data from the brains of living apes and humans, sulcal patterns reproduced on hominin endocasts provide important information for studying the evolution of the cerebral cortex and cognition in human ancestors. Here, new evidence is discussed for the evolution of sulcal patterns associated with cortical reorganization in three parts of the hominin brain: (1) the parietotemporo-occipital association cortex, (2) Broca's speech area, and (3) dorsolateral prefrontal association cortex. Of the three regions, the evidence regarding the last is the clearest. Compared to great apes, Australopithecus endocasts reproduce a clear middle frontal sulcus in the dorsolateral prefrontal cortex that is derived toward the human condition. This finding is consistent with data from comparative cytoarchitectural studies of ape and human brains as well as shape analyses of australopithecine endocasts. The comparative and direct evidence for all three regions suggests that hominin brain reorganization was underway by at least the time of Australopithecus africanus (~2.5 to 3.0 mya), despite the ape-sized brains of these hominins, and that it entailed expansion of both rostral and caudal association cortices. PMID:24822043

The evolution of body size and shape in the human career

PubMed Central

Grabowski, Mark; Hatala, Kevin G.; Richmond, Brian G.

2016-01-01

Body size is a fundamental biological property of organisms, and documenting body size variation in hominin evolution is an important goal of palaeoanthropology. Estimating body mass appears deceptively simple but is laden with theoretical and pragmatic assumptions about best predictors and the most appropriate reference samples. Modern human training samples with known masses are arguably the ‘best’ for estimating size in early bipedal hominins such as the australopiths and all members of the genus Homo, but it is not clear if they are the most appropriate priors for reconstructing the size of the earliest putative hominins such as Orrorin and Ardipithecus. The trajectory of body size evolution in the early part of the human career is reviewed here and found to be complex and nonlinear. Australopith body size varies enormously across both space and time. The pre-erectus early Homo fossil record from Africa is poor and dominated by relatively small-bodied individuals, implying that the emergence of the genus Homo is probably not linked to an increase in body size or unprecedented increases in size variation. Body size differences alone cannot explain the observed variation in hominin body shape, especially when examined in the context of small fossil hominins and pygmy modern humans. This article is part of the themed issue ‘Major transitions in human evolution’. PMID:27298459

Age and context of the oldest known hominin fossils from Flores.

PubMed

Brumm, Adam; van den Bergh, Gerrit D; Storey, Michael; Kurniawan, Iwan; Alloway, Brent V; Setiawan, Ruly; Setiyabudi, Erick; Grün, Rainer; Moore, Mark W; Yurnaldi, Dida; Puspaningrum, Mika R; Wibowo, Unggul P; Insani, Halmi; Sutisna, Indra; Westgate, John A; Pearce, Nick J G; Duval, Mathieu; Meijer, Hanneke J M; Aziz, Fachroel; Sutikna, Thomas; van der Kaars, Sander; Flude, Stephanie; Morwood, Michael J

2016-06-09

Recent excavations at the early Middle Pleistocene site of Mata Menge in the So'a Basin of central Flores, Indonesia, have yielded hominin fossils attributed to a population ancestral to Late Pleistocene Homo floresiensis. Here we describe the age and context of the Mata Menge hominin specimens and associated archaeological findings. The fluvial sandstone layer from which the in situ fossils were excavated in 2014 was deposited in a small valley stream around 700 thousand years ago, as indicated by (40)Ar/(39)Ar and fission track dates on stratigraphically bracketing volcanic ash and pyroclastic density current deposits, in combination with coupled uranium-series and electron spin resonance dating of fossil teeth. Palaeoenvironmental data indicate a relatively dry climate in the So'a Basin during the early Middle Pleistocene, while various lines of evidence suggest the hominins inhabited a savannah-like open grassland habitat with a wetland component. The hominin fossils occur alongside the remains of an insular fauna and a simple stone technology that is markedly similar to that associated with Late Pleistocene H. floresiensis.

New early Pleistocene hominin teeth from the Swartkrans Formation, South Africa.

PubMed

Pickering, Travis Rayne; Heaton, Jason L; Sutton, Morris B; Clarke, Ron J; Kuman, Kathleen; Senjem, Jess Hutton; Brain, C K

2016-11-01

We describe 14 hominin teeth and tooth fragments excavated recently from Swartkrans Cave (South Africa). The fossils derive from Members 1 (Lower Bank) and 3, from the Member 2/3 interface and from two deposits not yet assigned to member (the "Talus Cone Deposit" and the "Underground North Excavation" [UNE]) of the Swartkrans Formation, and include the first hominin fossil from the UNE, the two smallest Paranthropus robustus deciduous maxillary second molars in the entire hominin fossil record, and one of the smallest P. robustus permanent maxillary second molars from Swartkrans. The small permanent molar is accompanied by another tooth from a different individual but from the same stratigraphic level of the Swartkrans Formation; this second tooth is among, if not, the largest P. robustus permanent maxillary first molars known from anywhere-lending credence to assertions that degrees of body size sexual dimorphism previously ascribed to this species may be underestimated. It is more equivocal whether this evidence also supports hypotheses proposing that P. robustus assemblages from Swartkrans (as well as those from other South African cave sites) formed through the taphonomically biasing actions of large carnivores. Copyright © 2016 Elsevier Ltd. All rights reserved.

Tool making, hand morphology and fossil hominins

PubMed Central

Marzke, Mary W.

2013-01-01

Was stone tool making a factor in the evolution of human hand morphology? Is it possible to find evidence in fossil hominin hands for this capability? These questions are being addressed with increasingly sophisticated studies that are testing two hypotheses; (i) that humans have unique patterns of grip and hand movement capabilities compatible with effective stone tool making and use of the tools and, if this is the case, (ii) that there exist unique patterns of morphology in human hands that are consistent with these capabilities. Comparative analyses of human stone tool behaviours and chimpanzee feeding behaviours have revealed a distinctive set of forceful pinch grips by humans that are effective in the control of stones by one hand during manufacture and use of the tools. Comparative dissections, kinematic analyses and biomechanical studies indicate that humans do have a unique pattern of muscle architecture and joint surface form and functions consistent with the derived capabilities. A major remaining challenge is to identify skeletal features that reflect the full morphological pattern, and therefore may serve as clues to fossil hominin manipulative capabilities. Hominin fossils are evaluated for evidence of patterns of derived human grip and stress-accommodation features. PMID:24101624

Tool making, hand morphology and fossil hominins.

PubMed

Marzke, Mary W

2013-11-19

Was stone tool making a factor in the evolution of human hand morphology? Is it possible to find evidence in fossil hominin hands for this capability? These questions are being addressed with increasingly sophisticated studies that are testing two hypotheses; (i) that humans have unique patterns of grip and hand movement capabilities compatible with effective stone tool making and use of the tools and, if this is the case, (ii) that there exist unique patterns of morphology in human hands that are consistent with these capabilities. Comparative analyses of human stone tool behaviours and chimpanzee feeding behaviours have revealed a distinctive set of forceful pinch grips by humans that are effective in the control of stones by one hand during manufacture and use of the tools. Comparative dissections, kinematic analyses and biomechanical studies indicate that humans do have a unique pattern of muscle architecture and joint surface form and functions consistent with the derived capabilities. A major remaining challenge is to identify skeletal features that reflect the full morphological pattern, and therefore may serve as clues to fossil hominin manipulative capabilities. Hominin fossils are evaluated for evidence of patterns of derived human grip and stress-accommodation features.

Consistent C3 plant habitat of hominins during 400-300 ka at the Longyadong Cave site (Luonan Basin, central China) revealed by stable carbon isotope analyses of loess deposits

NASA Astrophysics Data System (ADS)

Zhang, Hongyan; Lu, Huayu; Wang, Shejiang

2017-04-01

The proportions of woody and grassland taxa in terrestrial ecosystems played an important role in the origin and evolution of early Palaeolithic hominins. However the influence of ecosystem changes on hominin behavior and adaptations in Asia has not been studied in detail. Hominins have exploited the Luonan Basin in the Eastern Qinling Mountains, central China, since the early Paleolithic. Dated sites, consisting of alternating loess and soil deposits with in situ artefacts, are common in the region, and provide a detailed record of Early to Middle Pleistocene hominin environments. Here, we present the results of measurements of the stable carbon isotopic composition of soil organic matter (δ13C) in the loess-paleosol sequences from the Longyadong Cave site. Our analyses of δ13C show that for at least 400 ka the Longyadong Cave site and its surroundings were dominated by C3 woody plants, whereas the nearby Liuwan site was dominated by C4 and C3 mixed grassland or woody grassland vegetation. These findings demonstrate that between 400 and 300 ka in the Luonan Basin, hominins occupied a habitat consisting of a mosaic of grassland and woodland/forest. Although the vegetation of the region changed in response to the glacial-interglacial climatic cycles, patches of woody vegetation in landscapes such as at Longyadong Cave site persisted continuously. Such environments seem to be have been favored by hominins living in the Luonan Basin, possibly because they provided a diverse range of food resources during both glacial and interglacial intervals of the Middle Pleistocene, when most of northern China was experiencing an increasing trend of drying and cooling and steppe environments were expanding. Thus, the Luonan Basin would have served as a refugium for hominin occupation in China during the Middle Pleistocene.

The Nature of Culture: an eight-grade model for the evolution and expansion of cultural capacities in hominins and other animals.

PubMed

Haidle, Miriam Noël; Bolus, Michael; Collard, Mark; Conard, Nicholas; Garofoli, Duilio; Lombard, Marlize; Nowell, April; Tennie, Claudio; Whiten, Andrew

2015-07-20

Tracing the evolution of human culture through time is arguably one of the most controversial and complex scholarly endeavors, and a broad evolutionary analysis of how symbolic, linguistic, and cultural capacities emerged and developed in our species is lacking. Here we present a model that, in broad terms, aims to explain the evolution and portray the expansion of human cultural capacities (the EECC model), that can be used as a point of departure for further multidisciplinary discussion and more detailed investigation. The EECC model is designed to be flexible, and can be refined to accommodate future archaeological, paleoanthropological, genetic or evolutionary psychology/behavioral analyses and discoveries. Our proposed concept of cultural behavior differentiates between empirically traceable behavioral performances and behavioral capacities that are theoretical constructs. Based largely on archaeological data (the 'black box' that most directly opens up hominin cultural evolution), and on the extension of observable problem-solution distances, we identify eight grades of cultural capacity. Each of these grades is considered within evolutionary-biological and historical-social trajectories. Importantly, the model does not imply an inevitable progression, but focuses on expansion of cultural capacities based on the integration of earlier achievements. We conclude that there is not a single cultural capacity or a single set of abilities that enabled human culture; rather, several grades of cultural capacity in animals and hominins expanded during our evolution to shape who we are today.

Middle Pleistocene Hominin Teeth from Longtan Cave, Hexian, China

PubMed Central

Xing, Song; Martinón-Torres, María; Bermúdez de Castro, José María; Zhang, Yingqi; Fan, Xiaoxiao; Zheng, Longting; Huang, Wanbo; Liu, Wu

2014-01-01

Excavations at the Longtan Cave, Hexian, Anhui Province of Eastern China, have yielded several hominin fossils including crania, mandibular fragments, and teeth currently dated to 412±25 ka. While previous studies have focused on the cranial remains, there are no detailed analyses of the dental evidence. In this study, we provide metric and morphological descriptions and comparisons of ten teeth recovered from Hexian, including microcomputed tomography analyses. Our results indicate that the Hexian teeth are metrically and morphologically primitive and overlap with H. ergaster and East Asian Early and mid-Middle Pleistocene hominins in their large dimensions and occlusal complexities. However, the Hexian teeth differ from H. ergaster in features such as conspicuous vertical grooves on the labial/buccal surfaces of the central incisor and the upper premolar, the crown outline shapes of upper and lower molars and the numbers, shapes, and divergences of the roots. Despite their close geological ages, the Hexian teeth are also more primitive than Zhoukoudian specimens, and resemble Sangiran Early Pleistocene teeth. In addition, no typical Neanderthal features have been identified in the Hexian sample. Our study highlights the metrical and morphological primitive status of the Hexian sample in comparison to contemporaneous or even earlier populations of Asia. Based on this finding, we suggest that the primitive-derived gradients of the Asian hominins cannot be satisfactorily fitted along a chronological sequence, suggesting complex evolutionary scenarios with the coexistence and/or survival of different lineages in Eurasia. Hexian could represent the persistence in time of a H. erectus group that would have retained primitive features that were lost in other Asian populations such as Zhoukoudian or Panxian Dadong. Our study expands the metrical and morphological variations known for the East Asian hominins before the mid-Middle Pleistocene and warns about the

Megadontia, striae periodicity and patterns of enamel secretion in Plio-Pleistocene fossil hominins

PubMed Central

Lacruz, Rodrigo S; Dean, M Christopher; Ramirez-Rozzi, Fernando; Bromage, Timothy G

2008-01-01

Early hominins formed large and thick-enamelled cheek-teeth within relatively short growth periods as compared with modern humans. To understand better the developmental basis of this process, we measured daily enamel increments, or cross striations, in 17 molars of Plio-Pleistocene hominins representing seven different species, including specimens attributed to early Homo. Our results show considerable variation across species, although all specimens conformed to the known pattern characterised by greater values in outer than inner enamel, and greater cuspal than cervical values. We then compared our results with the megadontia index, which represents tooth size in relation to body mass, for each species to assess the effect of daily growth rates on tooth size. Our results indicate that larger toothed (megadont) taxa display higher rates or faster forming enamel than smaller toothed hominins. By forming enamel quickly, large tooth crowns were able to develop within the constraints of shorter growth periods. Besides daily increments, many animals express long-period markings (striae of Retzius) in their enamel. We report periodicity values (number of cross striations between adjacent striae) in 14 new specimens of Australopithecus afarensis, Paranthropus aethiopicus, Paranthropus boisei, Homo habilis, Homo rudolfensis and Homo erectus, and show that long-period striae express a strong association with male and average male–female body mass. Our results for Plio-Pleistocene hominins show that the biological rhythms that give rise to long-period striae are encompassed within the range of variation known for modern humans, but show a lower mean and modal value of 7 days in australopithecines. In our sample of early Homo, mean and modal periodicity values were 8 days, and therefore similar to modern humans. These new data on daily rates of enamel formation and periodicity provide a better framework to interpret surface manifestations of internal growth markings on

Megadontia, striae periodicity and patterns of enamel secretion in Plio-Pleistocene fossil hominins.

PubMed

Lacruz, Rodrigo S; Dean, M Christopher; Ramirez-Rozzi, Fernando; Bromage, Timothy G

2008-08-01

Early hominins formed large and thick-enamelled cheek-teeth within relatively short growth periods as compared with modern humans. To understand better the developmental basis of this process, we measured daily enamel increments, or cross striations, in 17 molars of Plio-Pleistocene hominins representing seven different species, including specimens attributed to early Homo. Our results show considerable variation across species, although all specimens conformed to the known pattern characterised by greater values in outer than inner enamel, and greater cuspal than cervical values. We then compared our results with the megadontia index, which represents tooth size in relation to body mass, for each species to assess the effect of daily growth rates on tooth size. Our results indicate that larger toothed (megadont) taxa display higher rates or faster forming enamel than smaller toothed hominins. By forming enamel quickly, large tooth crowns were able to develop within the constraints of shorter growth periods. Besides daily increments, many animals express long-period markings (striae of Retzius) in their enamel. We report periodicity values (number of cross striations between adjacent striae) in 14 new specimens of Australopithecus afarensis, Paranthropus aethiopicus, Paranthropus boisei, Homo habilis, Homo rudolfensis and Homo erectus, and show that long-period striae express a strong association with male and average male-female body mass. Our results for Plio-Pleistocene hominins show that the biological rhythms that give rise to long-period striae are encompassed within the range of variation known for modern humans, but show a lower mean and modal value of 7 days in australopithecines. In our sample of early Homo, mean and modal periodicity values were 8 days, and therefore similar to modern humans. These new data on daily rates of enamel formation and periodicity provide a better framework to interpret surface manifestations of internal growth markings on

The late Middle Pleistocene hominin fossil record of eastern Asia: synthesis and review.

PubMed

Bae, Christopher J

2010-01-01

Traditionally, Middle Pleistocene hominin fossils that cannot be allocated to Homo erectus sensu lato or modern H. sapiens have been assigned to different specific taxa. For example, in eastern Asia, these hominin fossils have been classified as archaic, early, or premodern H. sapiens. An increasing number of Middle Pleistocene hominin fossils are currently being assigned to H. heidelbergensis. This is particularly the case for the African and European Middle Pleistocene hominin fossil record. There have been suggestions that perhaps the eastern Asian late Middle Pleistocene hominins can also be allocated to the H. heidelbergensis hypodigm. In this article, I review the current state of the late Middle Pleistocene hominin fossil record from eastern Asia and examine the various arguments for assigning these hominins to the different specific taxa. The two primary conclusions drawn from this review are as follows: 1) little evidence currently exists in the eastern Asian Middle Pleistocene hominin fossil record to support their assignment to H. heidelbergensis; and 2) rather than add to the growing list of hominin fossil taxa by using taxonomic names like H. daliensis for northeast Asian fossils and H. mabaensis for Southeast Asian fossils, it is better to err on the side of caution and continue to use the term archaic H. sapiens to represent all of these hominin fossils. What should be evident from this review is the need for an increase in the quality and quantity of the eastern Asian hominin fossil data set. Fortunately, with the increasing number of large-scale multidisciplinary paleoanthropological field and laboratory research projects in eastern Asia, the record is quickly becoming better understood. Copyright © 2010 Wiley-Liss, Inc.

Earliest Porotic Hyperostosis on a 1.5-Million-Year-Old Hominin, Olduvai Gorge, Tanzania

PubMed Central

Domínguez-Rodrigo, Manuel; Pickering, Travis Rayne; Diez-Martín, Fernando; Mabulla, Audax; Musiba, Charles; Trancho, Gonzalo; Baquedano, Enrique; Bunn, Henry T.; Barboni, Doris; Santonja, Manuel; Uribelarrea, David; Ashley, Gail M.; Martínez-Ávila, María del Sol; Barba, Rebeca; Gidna, Agness; Yravedra, José; Arriaza, Carmen

2012-01-01

Meat-eating was an important factor affecting early hominin brain expansion, social organization and geographic movement. Stone tool butchery marks on ungulate fossils in several African archaeological assemblages demonstrate a significant level of carnivory by Pleistocene hominins, but the discovery at Olduvai Gorge of a child's pathological cranial fragments indicates that some hominins probably experienced scarcity of animal foods during various stages of their life histories. The child's parietal fragments, excavated from 1.5-million-year-old sediments, show porotic hyperostosis, a pathology associated with anemia. Nutritional deficiencies, including anemia, are most common at weaning, when children lose passive immunity received through their mothers' milk. Our results suggest, alternatively, that (1) the developmentally disruptive potential of weaning reached far beyond sedentary Holocene food-producing societies and into the early Pleistocene, or that (2) a hominin mother's meat-deficient diet negatively altered the nutritional content of her breast milk to the extent that her nursing child ultimately died from malnourishment. Either way, this discovery highlights that by at least 1.5 million years ago early human physiology was already adapted to a diet that included the regular consumption of meat. PMID:23056303

Manual Loading Distribution During Carrying Behaviors: Implications for the Evolution of the Hominin Hand

PubMed Central

Key, Alastair J. M.

2016-01-01

The human hand is unparalleled amongst primates in its ability to manipulate objects forcefully and dexterously. Previous research has predominantly sought to explain the evolution of these capabilities through an adaptive relationship between more modern human-like anatomical features in the upper limb and increased stone tool production and use proficiency. To date, however, we know little about the influence that other manipulatively demanding behaviors may have had upon the evolution of the human hand. The present study addresses one aspect of this deficiency by examining the recruitment of the distal phalanges during a range of manual transportation (i.e., carrying) events related to hominin behavioral repertoires during the Plio-Pleistocene. Specifically, forces on the volar pad of each digit are recorded during the transportation of stones and wooden branches that vary in weight and size. Results indicate that in most instances, the index and middle fingers are recruited to a significantly greater extent than the other three digits during carrying events. Relative force differences between digits were, however, dependent upon the size and weight of the object transported. Carrying behaviors therefore appear unlikely to have contributed to the evolution of the robust thumb anatomy observed in the human hand. Rather, results suggest that the manual transportation of objects may plausibly have influenced the evolution of the human gripping capabilities and the 3rd metacarpal styloid process. PMID:27695044

A mitochondrial genome sequence of a hominin from Sima de los Huesos.

PubMed

Meyer, Matthias; Fu, Qiaomei; Aximu-Petri, Ayinuer; Glocke, Isabelle; Nickel, Birgit; Arsuaga, Juan-Luis; Martínez, Ignacio; Gracia, Ana; de Castro, José María Bermúdez; Carbonell, Eudald; Pääbo, Svante

2014-01-16

Excavations of a complex of caves in the Sierra de Atapuerca in northern Spain have unearthed hominin fossils that range in age from the early Pleistocene to the Holocene. One of these sites, the 'Sima de los Huesos' ('pit of bones'), has yielded the world's largest assemblage of Middle Pleistocene hominin fossils, consisting of at least 28 individuals dated to over 300,000 years ago. The skeletal remains share a number of morphological features with fossils classified as Homo heidelbergensis and also display distinct Neanderthal-derived traits. Here we determine an almost complete mitochondrial genome sequence of a hominin from Sima de los Huesos and show that it is closely related to the lineage leading to mitochondrial genomes of Denisovans, an eastern Eurasian sister group to Neanderthals. Our results pave the way for DNA research on hominins from the Middle Pleistocene.

Early Human Speciation, Brain Expansion and Dispersal Influenced by African Climate Pulses

PubMed Central

Shultz, Susanne; Maslin, Mark

2013-01-01

Early human evolution is characterised by pulsed speciation and dispersal events that cannot be explained fully by global or continental paleoclimate records. We propose that the collated record of ephemeral East African Rift System (EARS) lakes could be a proxy for the regional paleoclimate conditions experienced by early hominins. Here we show that the presence of these lakes is associated with low levels of dust deposition in both West African and Mediterranean records, but is not associated with long-term global cooling and aridification of East Africa. Hominin expansion and diversification seem to be associated with climate pulses characterized by the precession-forced appearance and disappearance of deep EARS lakes. The most profound period for hominin evolution occurs at about 1.9 Ma; with the highest recorded diversity of hominin species, the appearance of Homo (sensu stricto) and major dispersal events out of East Africa into Eurasia. During this period, ephemeral deep-freshwater lakes appeared along the whole length of the EARS, fundamentally changing the local environment. The relationship between the local environment and hominin brain expansion is less clear. The major step-wise expansion in brain size around 1.9 Ma when Homo appeared was coeval with the occurrence of ephemeral deep lakes. Subsequent incremental increases in brain size are associated with dry periods with few if any lakes. Plio-Pleistocene East African climate pulses as evinced by the paleo-lake records seem, therefore, fundamental to hominin speciation, encephalisation and migration. PMID:24146922

Early human speciation, brain expansion and dispersal influenced by African climate pulses.

PubMed

Shultz, Susanne; Maslin, Mark

2013-01-01

Early human evolution is characterised by pulsed speciation and dispersal events that cannot be explained fully by global or continental paleoclimate records. We propose that the collated record of ephemeral East African Rift System (EARS) lakes could be a proxy for the regional paleoclimate conditions experienced by early hominins. Here we show that the presence of these lakes is associated with low levels of dust deposition in both West African and Mediterranean records, but is not associated with long-term global cooling and aridification of East Africa. Hominin expansion and diversification seem to be associated with climate pulses characterized by the precession-forced appearance and disappearance of deep EARS lakes. The most profound period for hominin evolution occurs at about 1.9 Ma; with the highest recorded diversity of hominin species, the appearance of Homo (sensu stricto) and major dispersal events out of East Africa into Eurasia. During this period, ephemeral deep-freshwater lakes appeared along the whole length of the EARS, fundamentally changing the local environment. The relationship between the local environment and hominin brain expansion is less clear. The major step-wise expansion in brain size around 1.9 Ma when Homo appeared was coeval with the occurrence of ephemeral deep lakes. Subsequent incremental increases in brain size are associated with dry periods with few if any lakes. Plio-Pleistocene East African climate pulses as evinced by the paleo-lake records seem, therefore, fundamental to hominin speciation, encephalisation and migration.

Investigating the Signature of Aquatic Resource Use within Pleistocene Hominin Dietary Adaptations

PubMed Central

Archer, Will; Braun, David R.

2013-01-01

There is general agreement that the diet of early hominins underwent dramatic changes shortly after the appearance of stone tools in the archaeological record. It is often assumed that this change is associated with dietary expansion to incorporate large mammal resources. Although other aspects of the hominin diet, such as aquatic or vegetal resources, are assumed to be a part of hominin subsistence, identifying evidence of these adaptations has proved difficult. Here we present a series of analyses that provide methodological support for the inclusion of aquatic resources in hominin dietary reconstructions. We suggest that bone surface modifications in aquatic species are morphologically distinguishable from bone surface modifications on terrestrial taxa. We relate these findings to differences that we document in the surface mechanical properties of the two types of bone, as reflected by significant differences in bone surface microhardness values between aquatic and terrestrial species. We hypothesize that the characteristics of bone surface modifications on aquatic taxa inhibit the ability of zooarchaeologists to consistently diagnose them correctly. Contingently, this difficulty influences correspondence levels between zooarchaeologists, and may therefore result in misinterpretation of the taphonomic history of early Pleistocene aquatic faunal assemblages. A blind test using aquatic specimens and a select group of 9 experienced zooarchaeologists as participants was designed to test this hypothesis. Investigation of 4 different possible explanations for blind test results suggest the dominant factors explaining patterning relate to (1) the specific methodologies employed to diagnose modifications on aquatic specimens and (2) the relative experience of participants with modifications on aquatic bone surfaces. Consequently we argue that an important component of early hominin diets may have hitherto been overlooked as a result of (a) the paucity of referential

Was monogamy a key step on the hominin road? Reevaluating the monogamy hypothesis in the evolution of cooperative breeding.

PubMed

Kramer, Karen L; Russell, Andrew F

2015-01-01

Because human mothers routinely rely on others to help raise their young, humans have been characterized as cooperative breeders.(1-9) Several large-scale phylogenetic analyses have presented compelling evidence that monogamy preceded the evolution of cooperative breeding in a wide variety of nonhuman animals.(10-14) These studies have suggested that monogamy provides a general rule (the monogamy hypothesis) for explaining evolutionary transitions to cooperative breeding.(15) Given the prevalence of cooperative breeding in contemporary human societies, we evaluate whether this suggests a monogamous hominin past. © 2015 Wiley Periodicals, Inc.

Vocal Development as a Guide to Modeling the Evolution of Language.

PubMed

Oller, D Kimbrough; Griebel, Ulrike; Warlaumont, Anne S

2016-04-01

Modeling of evolution and development of language has principally utilized mature units of spoken language, phonemes and words, as both targets and inputs. This approach cannot address the earliest phases of development because young infants are unable to produce such language features. We argue that units of early vocal development-protophones and their primitive illocutionary/perlocutionary forces-should be targeted in evolutionary modeling because they suggest likely units of hominin vocalization/communication shortly after the split from the chimpanzee/bonobo lineage, and because early development of spontaneous vocal capability is a logically necessary step toward vocal language, a root capability without which other crucial steps toward vocal language capability are impossible. Modeling of language evolution/development must account for dynamic change in early communicative units of form/function across time. We argue for interactive contributions of sender/infants and receiver/caregivers in a feedback loop involving both development and evolution and propose to begin computational modeling at the hominin break from the primate communicative background. Copyright © 2016 Cognitive Science Society, Inc.

Phonation takes precedence over articulation in development as well as evolution of language.

PubMed

Oller, D Kimbrough

2014-12-01

Early human vocal development is characterized first by emerging control of phonation and later by prosodic and supraglottal articulation. The target article has missed the opportunity to use these facts in the characterization of evolution in language-specific brain mechanisms. Phonation appears to be the initial human-specific brain change for language, and it was presumably a key target of selection in early hominin evolution.

‘Captivity bias’ in animal tool use and its implications for the evolution of hominin technology

PubMed Central

Haslam, Michael

2013-01-01

Animals in captive or laboratory settings may outperform wild animals of the same species in both frequency and diversity of tool use, a phenomenon here termed ‘captivity bias’. Although speculative at this stage, a logical conclusion from this concept is that animals whose tool-use behaviour is observed solely under natural conditions may be judged cognitively or physically inferior than if they had also been tested or observed under controlled captive conditions. In turn, this situation creates a potential problem for studies of the behaviour of extinct members of the human family tree—the hominins—as hominin cognitive abilities are often judged on material evidence of tool-use behaviour left in the archaeological record. In this review, potential factors contributing to captivity bias in primates (including increased contact between individuals engaged in tool use, guidance or shaping of tool-use behaviour by other tool-users and increased free time and energy) are identified and assessed for their possible effects on the behaviour of the Late Pleistocene hominin Homo floresiensis. The captivity bias concept provides one way to uncouple hominin tool use from cognition, by considering hominins as subject to the same adaptive influences as other tool-using animals. PMID:24101629

Microbial osteolysis in an Early Pleistocene hominin (Paranthropus robustus) from Swartkrans, South Africa.

PubMed

Grine, Frederick E; Bromage, Timothy G; Daegling, David J; Burr, David B; Brain, Charles K

2015-08-01

Microbiological degradation is one of the most important factors responsible for the destruction of bone in archaeological contexts. Microscopic focal destruction (MFD) is the most prevalent form of microbial tunneling and is encountered very commonly in human bones from archaeological sites, whereas animal bones from these same sites show significantly better preservation if they were deposited in a fragmentary (e.g., butchered) state. Similarly, most fossils show either no evidence or only minor traces of bacterial osteolysis. These observations and experimental evidence point to an endogenous origin for osteolytic bacteria, suggesting that bone bioerosion could potentially aid in reconstructing early taphonomic events. We here report extensive MFD in the mandibular corpus of a small (presumptive female) individual of the hominin Paranthropus robustus from the Early Pleistocene site of Swartkrans, South Africa. The specimen (SKX 5013) derives in situ from the Member 2 deposit, which is dated to ca. 1.5-1.0 Ma. Examination of sections from the corpus by backscattered electron microscopy reveals numerous small linear longitudinal and budded tunneling cavities, which tend to be concentrated around Haversian canals and are more abundant closer to the endosteal aspect of the section. The taphonomy of Swartkrans has been the subject of intense investigation, and given the possibility that different agents of accumulation may have been responsible for the faunal and hominin fossils in the different members at the site, the observation that a specimen of P. robustus from Member 2 displays significant microbial osteolysis is of potential interest. A study of the prevalence of this process in adequately large samples of the animal bones from these units may yield novel insights and provide refinement of our understanding of their taphonomic histories. Such observations might well reveal differences among the various members that could provide another valuable source of

Potential hominin affinities of Graecopithecus from the Late Miocene of Europe

PubMed Central

Fuss, Jochen; Spassov, Nikolai; Begun, David R.

2017-01-01

The split of our own clade from the Panini is undocumented in the fossil record. To fill this gap we investigated the dentognathic morphology of Graecopithecus freybergi from Pyrgos Vassilissis (Greece) and cf. Graecopithecus sp. from Azmaka (Bulgaria), using new μCT and 3D reconstructions of the two known specimens. Pyrgos Vassilissis and Azmaka are currently dated to the early Messinian at 7.175 Ma and 7.24 Ma. Mainly based on its external preservation and the previously vague dating, Graecopithecus is often referred to as nomen dubium. The examination of its previously unknown dental root and pulp canal morphology confirms the taxonomic distinction from the significantly older northern Greek hominine Ouranopithecus. Furthermore, it shows features that point to a possible phylogenetic affinity with hominins. G. freybergi uniquely shares p4 partial root fusion and a possible canine root reduction with this tribe and therefore, provides intriguing evidence of what could be the oldest known hominin. PMID:28531170

Aridity and hominin environments

NASA Astrophysics Data System (ADS)

Blumenthal, Scott A.; Levin, Naomi E.; Brown, Francis H.; Brugal, Jean-Philip; Chritz, Kendra L.; Harris, John M.; Jehle, Glynis E.; Cerling, Thure E.

2017-07-01

Aridification is often considered a major driver of long-term ecological change and hominin evolution in eastern Africa during the Plio-Pleistocene; however, this hypothesis remains inadequately tested owing to difficulties in reconstructing terrestrial paleoclimate. We present a revised aridity index for quantifying water deficit (WD) in terrestrial environments using tooth enamel δ18O values, and use this approach to address paleoaridity over the past 4.4 million years in eastern Africa. We find no long-term trend in WD, consistent with other terrestrial climate indicators in the Omo-Turkana Basin, and no relationship between paleoaridity and herbivore paleodiet structure among fossil collections meeting the criteria for WD estimation. Thus, we suggest that changes in the abundance of C4 grass and grazing herbivores in eastern Africa during the Pliocene and Pleistocene may have been decoupled from aridity. As in modern African ecosystems, other factors, such as rainfall seasonality or ecological interactions among plants and mammals, may be important for understanding the evolution of C4 grass- and grazer-dominated biomes.

Oldowan hominin behavior and ecology at Kanjera South,Kenya.

PubMed

Plummer, Thomas; Bishop, Laura

2016-06-20

The Early Stone Age archaeological record does not become persistent and widespread until approximately 2.0-1.7 million years ago, when Oldowan sites spread across Africa and ultimately into Eurasia. However, good records of hominin behavior from this important time interval are uncommon. Here we describe recent findings from the two million year old Oldowan site of Kanjera South, on the Homa Peninsula of southwestern Kenya. Kanjera South is the oldest Oldowan site with large assemblages of stone artifacts and well-preserved archaeological fauna. Our research indicates that hominin activities were situated in an open habitat within a grassland dominated ecosystem, the first documentation of an archaeological site in such an open setting. Hominins selectively collected and transported stone materials (30% of the lithic assemblage) over longer distances (at least 10 km) than is typical for the Oldowan, reflecting their preference for hard, easily-flaked lithologies unavailable on the northern half of the Homa Peninsula. They deployed different technological strategies to more intensively utilize these hard, non-local raw materials. Artifacts were used for a variety of tasks, including butchering small antelopes probably obtained by hunting, working wood, working soft plant material, and processing underground storage organs. These data suggest that the Kanjera hominins utilized a technological system that allowed them to extract nutrient dense animal and plant foods from their environment. This shift towards the acquisition of nutritious, hard-to-acquire foods in packets large enough to be shared may have facilitated brain and body size expansion in the genus Homo.

The femur of Orrorin tugenensis exhibits morphometric affinities with both Miocene apes and later hominins.

PubMed

Almécija, Sergio; Tallman, Melissa; Alba, David M; Pina, Marta; Moyà-Solà, Salvador; Jungers, William L

2013-01-01

Orrorin tugenensis (Kenya, ca. 6 Ma) is one of the earliest putative hominins. Its proximal femur, BAR 1002'00, was originally described as being very human-like, although later multivariate analyses showed an australopith pattern. However, some of its traits (for example, laterally protruding greater trochanter, medially oriented lesser trochanter and presence of third trochanter) are also present in earlier Miocene apes. Here, we use geometric morphometrics to reassess the morphological affinities of BAR 1002'00 within a large sample of anthropoids (including fossil apes and hominins) and reconstruct hominoid proximal femur evolution using squared-change parsimony. Our results indicate that both hominin and modern great ape femora evolved in different directions from a primitive morphology represented by some fossil apes. Orrorin appears intermediate between Miocene apes and australopiths in shape space. This evidence is consistent with femoral shape similarities in extant great apes being derived and homoplastic and has profound implications for understanding the origins of human bipedalism.

Fire, Lava Flows, and Human Evolution

NASA Astrophysics Data System (ADS)

Medler, M. J.

2015-12-01

Richard Wrangham and others argue that cooked food has been obligate for our ancestors since the time of Homo erectus. This hypothesis provides a particularly compelling explanation for the smaller mouths and teeth, shorter intestines, and larger brains that separate us from other hominins. However, natural ignitions are infrequent and it is unclear how earlier hominins may have adapted to cooked food and fire before they developed the necessary intelligence to make or control fire. To address this conundrum, we present cartographical evidence that the massive and long lasting lava flows in the African Rift could have provided our ancestors with episodic access to heat and fire as the front edges of these flows formed ephemeral pockets of heat and ignition and other geothermal features. For the last several million years major lava flows have been infilling the African Rift. After major eruptions there were likely more slowly advancing lava fronts creating small areas with very specific adaptive pressures and opportunities for small isolated groups of hominins. Some of these episodes of isolation may have extended for millennia allowing these groups of early hominins to develop the adaptations Wrangham links to fire and cooked food. To examine the potential veracity of this proposal, we developed a series of maps that overlay the locations of prominent hominin dig sites with contemporaneous lava flows. These maps indicate that many important developments in hominin evolution were occurring in rough spatial and temporal proximity to active lava flows. These maps indicate it is worth considering that over the last several million years small isolated populations of hominins may have experienced unique adaptive conditions while living near the front edges of these slowly advancing lava flows.

Chimpanzee fauna isotopes provide new interpretations of fossil ape and hominin ecologies

PubMed Central

Nelson, Sherry V.

2013-01-01

Carbon and oxygen stable isotopes within modern and fossil tooth enamel record the aspects of an animal's diet and habitat use. This investigation reports the first isotopic analyses of enamel from a large chimpanzee community and associated fauna, thus providing a means of comparing fossil ape and early hominin palaeoecologies with those of a modern ape. Within Kibale National Park forest, oxygen isotopes differentiate primate niches, allowing for the first isotopic reconstructions of degree of frugivory versus folivory as well as use of arboreal versus terrestrial resources. In a comparison of modern and fossil community isotopic profiles, results indicate that Sivapithecus, a Miocene ape from Pakistan, fed in the forest canopy, as do chimpanzees, but inhabited a forest with less continuous canopy or fed more on leaves. Ardipithecus, an early hominin from Ethiopia, fed both arboreally and terrestrially in a more open habitat than inhabited by chimpanzees. PMID:24197413

A synthesis of the theories and concepts of early human evolution.

PubMed

Maslin, Mark A; Shultz, Susanne; Trauth, Martin H

2015-03-05

Current evidence suggests that many of the major events in hominin evolution occurred in East Africa. Hence, over the past two decades, there has been intensive work undertaken to understand African palaeoclimate and tectonics in order to put together a coherent picture of how the environment of Africa has varied over the past 10 Myr. A new consensus is emerging that suggests the unusual geology and climate of East Africa created a complex, environmentally very variable setting. This new understanding of East African climate has led to the pulsed climate variability hypothesis that suggests the long-term drying trend in East Africa was punctuated by episodes of short alternating periods of extreme humidity and aridity which may have driven hominin speciation, encephalization and dispersals out of Africa. This hypothesis is unique as it provides a conceptual framework within which other evolutionary theories can be examined: first, at macro-scale comparing phylogenetic gradualism and punctuated equilibrium; second, at a more focused level of human evolution comparing allopatric speciation, aridity hypothesis, turnover pulse hypothesis, variability selection hypothesis, Red Queen hypothesis and sympatric speciation based on sexual selection. It is proposed that each one of these mechanisms may have been acting on hominins during these short periods of climate variability, which then produce a range of different traits that led to the emergence of new species. In the case of Homo erectus (sensu lato), it is not just brain size that changes but life history (shortened inter-birth intervals, delayed development), body size and dimorphism, shoulder morphology to allow thrown projectiles, adaptation to long-distance running, ecological flexibility and social behaviour. The future of evolutionary research should be to create evidence-based meta-narratives, which encompass multiple mechanisms that select for different traits leading ultimately to speciation.

A synthesis of the theories and concepts of early human evolution

PubMed Central

Maslin, Mark A.; Shultz, Susanne; Trauth, Martin H.

2015-01-01

Current evidence suggests that many of the major events in hominin evolution occurred in East Africa. Hence, over the past two decades, there has been intensive work undertaken to understand African palaeoclimate and tectonics in order to put together a coherent picture of how the environment of Africa has varied over the past 10 Myr. A new consensus is emerging that suggests the unusual geology and climate of East Africa created a complex, environmentally very variable setting. This new understanding of East African climate has led to the pulsed climate variability hypothesis that suggests the long-term drying trend in East Africa was punctuated by episodes of short alternating periods of extreme humidity and aridity which may have driven hominin speciation, encephalization and dispersals out of Africa. This hypothesis is unique as it provides a conceptual framework within which other evolutionary theories can be examined: first, at macro-scale comparing phylogenetic gradualism and punctuated equilibrium; second, at a more focused level of human evolution comparing allopatric speciation, aridity hypothesis, turnover pulse hypothesis, variability selection hypothesis, Red Queen hypothesis and sympatric speciation based on sexual selection. It is proposed that each one of these mechanisms may have been acting on hominins during these short periods of climate variability, which then produce a range of different traits that led to the emergence of new species. In the case of Homo erectus (sensu lato), it is not just brain size that changes but life history (shortened inter-birth intervals, delayed development), body size and dimorphism, shoulder morphology to allow thrown projectiles, adaptation to long-distance running, ecological flexibility and social behaviour. The future of evolutionary research should be to create evidence-based meta-narratives, which encompass multiple mechanisms that select for different traits leading ultimately to speciation. PMID:25602068

Early Pleistocene hominin deciduous teeth from the Homo antecessor Gran Dolina-TD6 bearing level (Sierra de Atapuerca, Spain).

PubMed

Bermúdez de Castro, José María; Martinón-Torres, María; Martín-Francés, Laura; Martínez de Pinillos, Marina; Modesto-Mata, Mario; García-Campos, Cecilia; Wu, Xiujie; Xing, Song; Liu, Wu

2017-07-01

During the last 13 years, the late Early Pleistocene Gran Dolina-TD6-2 level (Sierra de Atapuerca, northern Spain) has yielded an additional sample of 26 dental specimens attributed to Homo antecessor. In this report, we present a descriptive and comparative study of the six deciduous teeth. We provide external and internal morphological descriptions following classical terminology, as well as the mesiodistal and buccolingual measurements of the teeth. The internal morphology was described by means of micro-CT technique. The TD6 deciduous teeth preserve primitive features regarding the Homo clade, such as the presence of styles in lower and upper canines and developed anterior and posterior foveae in the dm 2 . However, other features related to the complexity of the crown morphology (e.g., cingulum) are not present in this sample. Furthermore, the great reduction of the talonid of the dm 1 s is also noteworthy. Despite the limited comparative evidence, the presence of a remarkably well-developed tuberculum molare in the dm 1 and dm 1 s from TD6 can be also considered a derived feature in the genus Homo. The TD6 hominins exhibit dental dimensions similar to those of other Pleistocene hominins. The dm 1 s are buccolingually elongated and the buccolingual diameter of ATD6-93 is the largest recorded so far in the Homo fossil record. This study expands the list of plesiomorphic features of H. antecessor, and provides some information on the evolutionary status of this species. However, the identification of some advanced traits evinces a step towards the derived morphology of European Pleistocene teeth. The study of the deciduous dentition confirms the mosaic pattern of H. antecessor morphology revealed in previous studies of this hominin sample. © 2017 Wiley Periodicals, Inc.

The top of the Olduvai subchron in a high-resolution magnetostratigraphy from the West Turkana core WTK13, Hominin Sites and Paleolakes Drilling Project (HSPDP)

NASA Astrophysics Data System (ADS)

Sier, Mark; Langereis, Cor; Dupont-Nivet, Guillaume; Feibel, Craig; Jordeens, Jose; van der Lubbe, Jeroen; Beck, Catherine; Olago, Daniel; Cohen, Andrew

2017-04-01

One of the major challenges in understanding the evolution of our own species is identifying the role climate change has played in the evolution of earlier hominin species. To clarify the influence of climate, we need long and continuous high-resolution paleoclimate records, preferably obtained from hominin-bearing sediments, that are well-dated by tephro- and magnetostratigraphy and other methods. This is hindered, however, by the fact that fossil-bearing sediments are often discontinuous, and subject to weathering, which may lead to oxidation and remagnetization. To obtain fresh, unweathered sediments, the Hominin Sites and Paleolakes Drilling Project (HSPDP) collected a 216- meter core (WTK13) in 2013 from deposits of Early Pleistocene paleolake Lorenyang in the western Turkana Basin (Kenya). Here, we present the magnetostratigraphy of the core. Rock magnetic analyses reveal the presence of iron sulphides carrying the remanent magnetizations. To recover polarity orientation from the near-equatorial WTK13 core drilled at 5°N, we developed and successfully applied two independent drill-core reorientation methods taking advantage of (1) the sedimentary fabric as expressed in the Anisotropy of Magnetic Susceptibility (AMS) and (2) the occurrence of a viscous component oriented in the present day field. The reoriented directions reveal a normal to reversed polarity reversal identified as the top of the Olduvai subchron. From this excellent record, we find no evidence for the 'Vrica subchron' previously reported in the area. We suggest that outcrop-based interpretations supporting the presence of the Vrica subchron have been affected by the oxidation of iron sulphides initially present in the sediments as evident in the core record, and by subsequent remagnetization. Based on our new high-resolution magnetostratigraphy and stratigraphic markers, we provide constraints for an initial age model of the WTK13 core. We discuss the implications of the observed geomagnetic

Hominin expansion into Central Asia during the last interglacial

NASA Astrophysics Data System (ADS)

Asmerom, Yemane; Polyak, Victor J.; Wagner, Jennifer D. M.; Jonathan Patchett, P.

2018-07-01

Central Asia was a likely gateway for hominin expansion. Obi-Rakhmat Grotto, northeastern Uzbekistan, has a deposit that contains the remains of a hominin child (OR-1) and more than 60,000 Paleolithic artifacts, making it one of the most important archaeological sites in Central Asia. Regionally, genetic data suggest hominin presence and human-Neanderthal interbreeding as far back as 100 ka, although, to date, absolute ages of hominin remains that old have not been known in the region. We present new uranium-series dates that constrain the age of the Obi-Rakhmat deposit to 98 ka towards the top and 109 ka for the layer containing OR-1, pushing hominin expansion into Central Asia minimally to 109 ± 2 ka, to a time, based on the genetic clock, of Neanderthal-modern human interbreeding. Our chronology establishes a minimum age of 98 ka for the well-developed lithic industry in Central Asia. The period covering the deposition of the sediments containing the artifacts and specimen OR-1 coincides with a warm and one of the most humid intervals of Marine Isotope Stage (MIS) 5 and last glacial period in the region, providing support for climate-driven hominin expansion.

The Mystery of the Skulls: What Can Old Bones Tell Us about Hominin Evolution?

ERIC Educational Resources Information Center

Yerky, Mike Darwin; Wilczynski, Carolyn J.

2014-01-01

In this activity, students examine nine hominin skulls for specialized features and take measurements that will enable them to determine the relatedness of these species. They will ultimately place each specimen on a basic phylogenetic tree that also reveals the geological time frame in which each species lived. On the basis of their data, and…

Evaluating morphometric body mass prediction equations with a juvenile human test sample: accuracy and applicability to small-bodied hominins.

PubMed

Walker, Christopher S; Yapuncich, Gabriel S; Sridhar, Shilpa; Cameron, Noël; Churchill, Steven E

2018-02-01

Body mass is an ecologically and biomechanically important variable in the study of hominin biology. Regression equations derived from recent human samples allow for the reasonable prediction of body mass of later, more human-like, and generally larger hominins from hip joint dimensions, but potential differences in hip biomechanics across hominin taxa render their use questionable with some earlier taxa (i.e., Australopithecus spp.). Morphometric prediction equations using stature and bi-iliac breadth avoid this problem, but their applicability to early hominins, some of which differ in both size and proportions from modern adult humans, has not been demonstrated. Here we use mean stature, bi-iliac breadth, and body mass from a global sample of human juveniles ranging in age from 6 to 12 years (n = 530 age- and sex-specific group annual means from 33 countries/regions) to evaluate the accuracy of several published morphometric prediction equations when applied to small humans. Though the body proportions of modern human juveniles likely differ from those of small-bodied early hominins, human juveniles (like fossil hominins) often differ in size and proportions from adult human reference samples and, accordingly, serve as a useful model for assessing the robustness of morphometric prediction equations. Morphometric equations based on adults systematically underpredict body mass in the youngest age groups and moderately overpredict body mass in the older groups, which fall in the body size range of adult Australopithecus (∼26-46 kg). Differences in body proportions, notably the ratio of lower limb length to stature, influence predictive accuracy. Ontogenetic changes in these body proportions likely influence the shift in prediction error (from under- to overprediction). However, because morphometric equations are reasonably accurate when applied to this juvenile test sample, we argue these equations may be used to predict body mass in small-bodied hominins

Paleoclimatic and paleoenvironmental context of the Early Pleistocene hominins from Dmanisi (Georgia, Lesser Caucasus) inferred from the herpetofaunal assemblage

NASA Astrophysics Data System (ADS)

Blain, Hugues-Alexandre; Agustí, Jordi; Lordkipanidze, David; Rook, Lorenzo; Delfino, Massimo

2014-12-01

Dmanisi is currently the oldest Early Palaeolithic site discovered out of Africa. It has produced over 40 hominin remains, including a set of very informative skulls, in direct association with faunal remains and numerous lithic artifacts. Given the relevance of this locality, every effort is being made to reconstruct the landscapes where these hominins once lived. Amphibian and reptile remains from Dmanisi are here described for the first time and used as paleoclimatic and paleoenvironmental proxies. They comprise at least six taxa: a green toad (Bufo gr. Bufo viridis), the Greek tortoise (Testudo graeca), a green lizard (Lacerta gr. Lacerta viridis), a four-lined snake (Elaphe gr. Elaphe quatuorlineata), an indeterminate colubrid and a water snake (Natrix sp.). As these taxa are not extinct and their ecology can be directly studied, they can contribute to the reconstruction of the landscape and climate. The application of the Mutual Climatic Range method provides quantitative data indicating that during the hominin presence at Dmanisi climate was warm and dry, similar to the present-day Mediterranean climate. In comparison with today climate of Dmanisi, estimated mean annual temperature was 3.1 °C higher, with a greater increase of temperature in summer (+7.1 °C) than in winter (+4.7 °C). The mean annual precipitation was slightly lower (-65 mm) than the current level, with precipitation higher than current one during winter (+104 mm) but strongly lower during the other seasons, suggesting a stronger contrast in the rainfall regime during the year. From a paleoenvironmental point of view, fossil amphibians and reptiles all suggest the predominance of arid environments, from steppe or semi-desert to open Mediterranean forest, with stony or rocky substrate and bushy areas. The presence of permanent aquatic environments is also documented. These results mainly agree with those for large mammals, small mammals and the archaeobotanical analysis that indicate an

Major transitions in human evolution.

PubMed

Foley, Robert A; Martin, Lawrence; Mirazón Lahr, Marta; Stringer, Chris

2016-07-05

Evolutionary problems are often considered in terms of 'origins', and research in human evolution seen as a search for human origins. However, evolution, including human evolution, is a process of transitions from one state to another, and so questions are best put in terms of understanding the nature of those transitions. This paper discusses how the contributions to the themed issue 'Major transitions in human evolution' throw light on the pattern of change in hominin evolution. Four questions are addressed: (1) Is there a major divide between early (australopithecine) and later (Homo) evolution? (2) Does the pattern of change fit a model of short transformations, or gradual evolution? (3) Why is the role of Africa so prominent? (4) How are different aspects of adaptation-genes, phenotypes and behaviour-integrated across the transitions? The importance of developing technologies and approaches and the enduring role of fieldwork are emphasized.This article is part of the themed issue 'Major transitions in human evolution'. © 2016 The Author(s).

A geometric morphometric analysis of hominin lower molars: Evolutionary implications and overview of postcanine dental variation.

PubMed

Gómez-Robles, Aida; Bermúdez de Castro, José María; Martinón-Torres, María; Prado-Simón, Leyre; Arsuaga, Juan Luis

2015-05-01

Lower molars have been extensively studied in the context of hominin evolution using classic and geometric morphometric analyses, 2D and 3D approaches, evaluations of the external (outer enamel surface) and internal anatomy (dentine, pulp chamber, and radicular canals), and studies of the crown and root variation. In this study, we present a 2D geometric morphometric analysis of the crown anatomy of lower first, second, and third molars of a broad sample of hominins, including Pliocene and Lower, Middle, and Upper Pleistocene species coming from Africa, Asia, and Europe. We show that shape variability increases from first to second and third molars. While first molars tend to retain a relatively stable 5-cusped conformation throughout the hominin fossil record, second and third molars show marked distal reductions in later Homo species. This trend to distal reduction is similar to that observed in previous studies of premolars and upper second and third molars, and points to a correlated reduction of distal areas across the whole postcanine dentition. Results on lower molar variation, as well as on other postcanine teeth, show certain trends in European Pleistocene populations from the Atapuerca sites. Middle Pleistocene hominins from Sima de los Huesos show Neanderthal affinities and strong dental reduction, especially in the most distal molars. The degree of dental reduction in this population is stronger than that observed in classic Neanderthals. Homo antecessor hominins from Gran Dolina-TD6 have primitive lower teeth that contrast with their more derived upper teeth. The evolutionary implications of these dental affinities are discussed in light of recent paleogenetic studies. Copyright © 2015 Elsevier Ltd. All rights reserved.

A critical review of the German Paleolithic hominin record.

PubMed

Street, Martin; Terberger, Thomas; Orschiedt, Jörg

2006-12-01

We review the hominin fossil record from western Central Europe in light of the recent major revisions of the geochronological context. The mandible from Mauer (Homo heidelbergensis), dated to circa 500,000 years ago, continues to represent the earliest German hominin and may coincide with the occupation of Europe north of the high alpine mountain chains. Only limited new evidence is available for the Middle Pleistocene, mostly in the form of skull fragments, a pattern that may relate to taphonomic processes. These finds and their ages suggest the gradual evolution of a suite of Neandertal features during this period. Despite new finds of classic Neandertals, there is no clear proof for Neandertal burial from Germany. Alternatively, cut marks on a skull fragment from the Neandertal type site suggest special treatment of that individual. New Accelerator Mass Spectrometry (AMS) radiocarbon dates of previous finds leave little reliably dated evidence for anatomically modern humans (AMH) in Europe before 30,000 BP; the remains from Hahnöfersand, Binshof-Speyer, Paderborn-Sande, and Vogelherd are now of Holocene age. Thus, a correlation of AMH with the Aurignacian remains to be proven, and the general idea of a long coexistence of Neandertals and AMH in Europe may be questioned. In western Central Europe, evidence of Gravettian human fossils is also very limited, although a new double grave from lower Austria may be relevant. The only dated burial from the German Upper Paleolithic (from Mittlere Klause) falls into a time period (circa 18,600 BP) represented by only a few occupation sites in western Central Europe. A number of human remains at Magdalenian sites appear to result from variable (secondary) burial practices. In contrast, the Final Paleolithic (circa 12,000-9600 cal. BC) yields an increase of hominin finds, including multiple burials (Bonn-Oberkassel, Neuwied-Irlich), similar to the situation in western and southern Europe.

Could plant extracts have enabled hominins to acquire honey before the control of fire?

PubMed

Kraft, Thomas S; Venkataraman, Vivek V

2015-08-01

Honey is increasingly recognized as an important food item in human evolution, but it remains unclear whether extinct hominins could have overcome the formidable collective stinging defenses of honey bees during honey acquisition. The utility of smoke for this purpose is widely recognized, but little research has explored alternative methods of sting deterrence such as the use of plant secondary compounds. To consider whether hominins could have used plant extracts as a precursor or alternative to smoke, we review the ethnographic, ethnobotanical, and plant chemical ecology literature to examine how humans use plants in combination with, and independently of, smoke during honey collection. Plant secondary compounds are diverse in their physiological and behavioral effects on bees and differ fundamentally from those of smoke. Plants containing these chemicals are widespread and prove to be remarkably effective in facilitating honey collection by honey hunters and beekeepers worldwide. While smoke may be superior as a deterrent to bees, plant extracts represent a plausible precursor or alternative to the use of smoke during honey collection by hominins. Smoke is a sufficient but not necessary condition for acquiring honey in amounts exceeding those typically obtained by chimpanzees, suggesting that significant honey consumption could have predated the control of fire. Copyright © 2015 Elsevier Ltd. All rights reserved.

The evolutionary history of the hominin hand since the last common ancestor of Pan and Homo

PubMed Central

Tocheri, Matthew W; Orr, Caley M; Jacofsky, Marc C; Marzke, Mary W

2008-01-01

Molecular evidence indicates that the last common ancestor of the genus Pan and the hominin clade existed between 8 and 4 million years ago (Ma). The current fossil record indicates the Pan-Homo last common ancestor existed at least 5 Ma and most likely between 6 and 7 Ma. Together, the molecular and fossil evidence has important consequences for interpreting the evolutionary history of the hand within the tribe Hominini (hominins). Firstly, parsimony supports the hypothesis that the hand of the last common ancestor most likely resembled that of an extant great ape overall (Pan, Gorilla, and Pongo), and that of an African ape in particular. Second, it provides a context for interpreting the derived changes to the hand that have evolved in various hominins. For example, the Australopithecus afarensis hand is likely derived in comparison with that of the Pan–Homo last common ancestor in having shorter fingers relative to thumb length and more proximo-distally oriented joints between its capitate, second metacarpal, and trapezium. This evidence suggests that these derived features evolved prior to the intensification of stone tool-related hominin behaviors beginning around 2.5 Ma. However, a majority of primitive features most likely present in the Pan-Homo last common ancestor are retained in the hands of Australopithecus, Paranthropus/early Homo, and Homo floresiensis. This evidence suggests that further derived changes to the hands of other hominins such as modern humans and Neandertals did not evolve until after 2.5 Ma and possibly even later than 1.5 Ma, which is currently the earliest evidence of Acheulian technology. The derived hands of modern humans and Neandertals may indicate a morphological commitment to tool-related manipulative behaviors beyond that observed in other hominins, including those (e.g. H. floresiensis) which may be descended from earlier tool-making species. PMID:18380869

Major transitions in human evolution

PubMed Central

Foley, Robert A.; Martin, Lawrence; Mirazón Lahr, Marta; Stringer, Chris

2016-01-01

Evolutionary problems are often considered in terms of ‘origins', and research in human evolution seen as a search for human origins. However, evolution, including human evolution, is a process of transitions from one state to another, and so questions are best put in terms of understanding the nature of those transitions. This paper discusses how the contributions to the themed issue ‘Major transitions in human evolution’ throw light on the pattern of change in hominin evolution. Four questions are addressed: (1) Is there a major divide between early (australopithecine) and later (Homo) evolution? (2) Does the pattern of change fit a model of short transformations, or gradual evolution? (3) Why is the role of Africa so prominent? (4) How are different aspects of adaptation—genes, phenotypes and behaviour—integrated across the transitions? The importance of developing technologies and approaches and the enduring role of fieldwork are emphasized. This article is part of the themed issue ‘Major transitions in human evolution’. PMID:27298461

A Spring Forward for Human Evolution in East Africa?

NASA Astrophysics Data System (ADS)

Cuthbert, M. O.; Ashley, G. M.

2014-12-01

The current consensus is that humans evolved in Africa and then migrated in waves to other parts of the world starting as early as 2 Ma. The climate was both cooling and drying. One of the major unknowns connected with human survival in this climatically turbulent environment is the availability of resources, particularly water. A growing body of geological evidence shows an association between springs, stone tools and hominin fossils at a number of sites in the East African Rift System (EARS) during a critical period for hominin evolution (from 1.8 Ma). The springs may have been vulnerable to climate variability, thus the role that groundwater availability may have played in human evolution and migration to other continents is not known. Using palaeogeological reconstruction and groundwater modelling of the paleo-catchment of one such EARS site, Olduvai Gorge (3°S), we show how spring discharge was likely linked to climate variability of annual to Milankovitch cycle timescales. Under decadal to centennial timescales, spring flow would have been relatively invariant providing good water resource resilience through long droughts. For multi-millennial periods, modelled spring flows lag groundwater recharge by 100s to 1000 years. Our results show how groundwater would have provided 'drought proof' water supply and habitats during arid phases as potable surface water from rivers or lakes became increasingly scarce. Localized groundwater systems are likely to have been widespread within the EARS providing refugia and intense competition during dry periods. Thus, springs and associated wetlands may have been important factors in natural selection and evolution, as well as a vital resource during dispersal within and out of Africa. While further exploration is needed to test the geographical extent of groundwater use by early humans, we propose that groundwater flow systems produced in the EARS played a significant role in the evolution and dispersal of early humans.

Carrying capacity, carnivoran richness and hominin survival in Europe.

PubMed

Rodríguez, Jesús; Mateos, Ana

2018-05-01

Carrying capacity, the maximum biomass that an ecosystem can sustain over the long term, strongly influences several ecological processes and it is also one of the main determinants of biodiversity. Here, we estimate the carrying capacity (CC) of the late Early and early Middle Pleistocene ecosystems of Europe, using equations describing the relationship between CC and climatic variables observed in the present, as well as maps of inferred paleotemperature and paleoprecipitation. Maps of paleoclimate values were interpolated from the composite benthic stable oxygen isotope ratios and a transfer function was used to estimate ungulate carrying capacity (CC U ) from the interpolated mean annual temperature and annual precipitation values. Carnivoran carrying capacity was subsequently estimated from ungulate carrying capacity and the effect of CC on the carnivoran faunas was analyzed in 12 paleocommunities from Southern Europe. Our results show that carnivoran species richness is strongly related to ungulate carrying capacity in recent ecosystems, but the late Early Pleistocene paleocommunities from Southern Europe included much richer carnivore guilds than would be expected for a recent community with a similar ungulate carrying capacity. Thus, those late Early Pleistocene ecosystems supported a high number of carnivoran species, but the carnivoran biomass they could support was relatively low. Consequently, carnivorans occurred at low densities in Southern Europe compared to the recent African savanna ecosystems, but likely also compared to coeval East African ecosystems. Consequently, the first Homo populations that arrived in Europe at the end of the late Early Pleistocene found mammal communities consisting of a low number of prey species, which accounted for a moderate herbivore biomass, as well as a diverse but not very abundant carnivore guild. This relatively low carnivoran density implies that the hominin-carnivore encounter rate was lower in the European

Complex and changing patterns of natural selection explain the evolution of the human hip.

PubMed

Grabowski, Mark; Roseman, Charles C

2015-08-01

Causal explanations for the dramatic changes that occurred during the evolution of the human hip focus largely on selection for bipedal function and locomotor efficiency. These hypotheses rest on two critical assumptions. The first-that these anatomical changes served functional roles in bipedalism-has been supported in numerous analyses showing how postcranial changes likely affected locomotion. The second-that morphological changes that did play functional roles in bipedalism were the result of selection for that behavior-has not been previously explored and represents a major gap in our understanding of hominin hip evolution. Here we use evolutionary quantitative genetic models to test the hypothesis that strong directional selection on many individual aspects of morphology was responsible for the large differences observed across a sample of fossil hominin hips spanning the Plio-Pleistocene. Our approach uses covariance among traits and the differences between relatively complete fossils to estimate the net selection pressures that drove the major transitions in hominin hip evolution. Our findings show a complex and changing pattern of natural selection drove hominin hip evolution, and that many, but not all, traits hypothesized to play functional roles in bipedalism evolved as a direct result of natural selection. While the rate of evolutionary change for all transitions explored here does not exceed the amount expected if evolution was occurring solely through neutral processes, it was far above rates of evolution for morphological traits in other mammalian groups. Given that stasis is the norm in the mammalian fossil record, our results suggest that large shifts in the adaptive landscape drove hominin evolution. Copyright © 2015 Elsevier Ltd. All rights reserved.

Evolution of group-wise cooperation: Is direct reciprocity insufficient?

PubMed

Kurokawa, Shun; Ihara, Yasuo

2017-02-21

Group-wise cooperation, or cooperation among three or more individuals, is an integral part of human societies. It is likely that group-wise cooperation also played a crucial role in the survival of early hominins, who were confronted with novel environmental challenges, long before the emergence of Homo sapiens. However, previous theoretical and empirical studies, focusing mainly on modern humans, have tended to suggest that evolution of cooperation in sizable groups cannot be explained by simple direct reciprocity and requires some additional mechanisms (reputation, punishment, etc.), which are cognitively too demanding for early hominins. As a partial resolution of the paradox, our recent analysis of a stochastic evolutionary model, which considers the effect of random drift, has revealed that evolution of group-wise cooperation is more likely to occur in larger groups when an individual's share of the benefit produced by one cooperator does not decrease with increasing group size (i.e., goods are non-rivalrous). In this paper, we further extend our previous analysis to explore possible consequences of introducing rare mistakes in behavior or imperfect information about behavior of others on the model outcome. Analyses of the extended models show that evolution of group-wise cooperation can be facilitated by large group size even when individuals intending to cooperate sometimes fail to do so or when all the information about the past behavior of group members is not available. We argue, therefore, that evolution of cooperation in sizable groups does not necessarily require other mechanisms than direct reciprocity if the goods to be produced via group-wise cooperation are non-rivalrous. Copyright © 2016 Elsevier Ltd. All rights reserved.

Termites in the hominin diet: a meta-analysis of termite genera, species and castes as a dietary supplement for South African robust australopithecines.

PubMed

Lesnik, Julie J

2014-06-01

Termite foraging by chimpanzees and present-day modern humans is a well-documented phenomenon, making it a plausible hypothesis that early hominins were also utilizing this resource. Hominin termite foraging has been credited by some to be the explanation for the unexpected carbon isotope signatures present in South African hominin teeth, which suggest the diet was different from that of extant non-human great apes, consisting of a significant amount of resources that are not from woody-plants. Grass-eating termites are one potential resource that could contribute to the carbon signature. However, not all termites eat grasses, and in fact, the termites that are most widely consumed by chimpanzees and by many present-day human populations at best have a mixed diet that includes small amounts of grasses. Here I review the ecology of termites and how it affects their desirability as a food resource for hominins, and conduct a meta-analysis of nutritional values for various genera, species and castes from the literature. Termites are very diverse, even within species, and this variability affects both their carbon signatures and nutritional value, hindering generalizations regarding the contribution of termites to the hominin diet. It is concluded here that a combination of soldiers and alates of the genus Macrotermes be used to model the insectivory component of the Plio-Pleistocene hominin diet due to their significant amounts of energy-yielding nutrients and potential role as a critical resource for supporting larger-brained hominins. Copyright © 2014. Published by Elsevier Ltd.

Hominin teeth from the Middle Pleistocene site of Yiyuan, Eastern China.

PubMed

Xing, Song; Sun, Chengkai; Martinón-Torres, María; Bermúdez de Castro, José María; Han, Fei; Zhang, Yingqi; Liu, Wu

2016-06-01

In 1981-1982, some hominin fossils, including a relatively complete skull and seven isolated teeth, were recovered from the Middle Pleistocene site of Yiyuan in Eastern China. In the present study we provide a detailed metric and morphological comparison of the Yiyuan dental sample in order to characterize better the variability of the human populations that inhabited China during the Middle Pleistocene. Aside from taxonomic and phylogenetic questions, the lack of understanding and/or knowledge about the morphological variability of these populations have caused concern about the human versus non-human nature of some of the hominin dental remains found in East Asia during the Early and the Middle Pleistocene. Thus, our study aims to present a detailed description and comparison of the Yiyuan isolated teeth to 1) discuss and support their human nature and 2) to explore their taxonomic affinities with regard to other penecontemporaneous populations from Asia. Our results clearly differentiate the Yiyuan sample from Pongo specimens and support a human attribution for the Yiyuan material. Our analyses also suggest that the Yiyuan teeth form a morphologically coherent group together with samples from Zhoukoudian, Chaoxian and Hexian. They are different from the more derived specimens from Panxian Dadong, suggesting a pattern of biogeographic isolation and different evolutionary trends between northern and southern China during the Middle Pleistocene. In addition, and despite sharing a common morphological bauplan with Homo erectus sensu stricto (s.s.), the Yiyuan, Zhoukoudian and Hexian teeth are also different from the Indonesian Early Pleistocene samples. In particular, the expression of a highly crenulated or dendritic enamel-dentine surface could be unique to these groups. Our study supports the notion that the taxonomy of the Pleistocene hominins from Asia may have been oversimplified. Future studies should explore the variability of the Asian specimens and

Hominin skeletal part abundances and claims of deliberate disposal of corpses in the Middle Pleistocene.

PubMed

Egeland, Charles P; Domínguez-Rodrigo, Manuel; Pickering, Travis Rayne; Menter, Colin G; Heaton, Jason L

2018-05-01

Humans are set apart from other organisms by the realization of their own mortality. Thus, determining the prehistoric emergence of this capacity is of significant interest to understanding the uniqueness of the human animal. Tracing that capacity chronologically is possible through archaeological investigations that focus on physical markers that reflect "mortality salience." Among these markers is the deliberate and culturally mediated disposal of corpses. Some Neandertal bone assemblages are among the earliest reasonable claims for the deliberate disposal of hominins, but even these are vigorously debated. More dramatic assertions center on the Middle Pleistocene sites of Sima de los Huesos (SH, Spain) and the Dinaledi Chamber (DC, South Africa), where the remains of multiple hominin individuals were found in deep caves, and under reported taphonomic circumstances that seem to discount the possibility that nonhominin actors and processes contributed to their formation. These claims, with significant implications for charting the evolution of the "human condition," deserve scrutiny. We test these assertions through machine-learning analyses of hominin skeletal part representation in the SH and DC assemblages. Our results indicate that nonanthropogenic agents and abiotic processes cannot yet be ruled out as significant contributors to the ultimate condition of both collections. This finding does not falsify hypotheses of deliberate disposal for the SH and DC corpses, but does indicate that the data also support partially or completely nonanthropogenic formational histories.

Terrestrial nest-building by wild chimpanzees (Pan troglodytes): implications for the tree-to-ground sleep transition in early hominins.

PubMed

Koops, Kathelijne; McGrew, William C; Matsuzawa, Tetsuro; Knapp, Leslie A

2012-07-01

Nest-building is a great ape universal and arboreal nesting in chimpanzees and bonobos suggests that the common ancestor of Pan and Homo also nested in trees. It has been proposed that arboreal nest-building remained the prevailing pattern until Homo erectus, a fully terrestrial biped, emerged. We investigated the unusual occurrence of ground-nesting in chimpanzees (Pan troglodytes), which may inform on factors influencing the tree-to-ground sleep transition in the hominin lineage. We used a novel genetic approach to examine ground-nesting in unhabituated chimpanzees at Seringbara in the Nimba Mountains, Guinea. Previous research showed that ground-nesting at Seringbara was not ecologically determined. Here, we tested a possible mate-guarding function of ground-nesting by analyzing DNA from shed hairs collected from ground nests and tree nests found in close proximity. We examined whether or not ground-nesting was a group-level behavioral pattern and whether or not it occurred in more than one community. We used multiple genetic markers to identify sex and to examine variation in mitochondrial DNA control region (HV1, HV2) sequences. Ground-nesting was a male-biased behavior and males constructed more elaborate ("night") nests than simple ("day") nests on the ground. The mate-guarding hypothesis was not supported, as ground and associated tree nests were built either by maternally-related males or possibly by the same individuals. Ground-nesting was widespread and likely habitual in two communities. We suggest that terrestrial nest-building may have already occurred in arboreally-adapted early hominins before the emergence of H. erectus. Copyright © 2012 Wiley Periodicals, Inc.

Experimental Insights into the Cognitive Significance of Early Stone Tools

PubMed Central

Perston, Yinika

2016-01-01

Stone-flaking technology is the most enduring evidence for the evolving cognitive abilities of our early ancestors. Flake-making was mastered by African hominins ~3.3 ma, followed by the appearance of handaxes ~1.75 ma and complex stone reduction strategies by ~1.6 ma. Handaxes are stones flaked on two opposed faces (‘bifacially’), creating a robust, sharp-edged tool, and complex reduction strategies are reflected in strategic prior flaking to prepare or ‘predetermine’ the nature of a later flake removal that served as a tool blank. These technologies are interpreted as major milestones in hominin evolution that reflect the development of higher-order cognitive abilities, and the presence and nature of these technologies are used to track movements of early hominin species or ‘cultures’ in the archaeological record. However, the warranting argument that certain variations in stone tool morphologies are caused by differences in cognitive abilities relies on analogy with technical replications by skilled modern stoneworkers, and this raises the possibility that researchers are projecting modern approaches to technical problems onto our non-modern hominin ancestors. Here we present the results of novel experiments that randomise flake removal and disrupt the modern stoneworker’s inclination to use higher-order reasoning to guide the stone reduction process. Although our protocols prevented goal-directed replication of stone tool types, the experimental assemblage is morphologically standardised and includes handaxe-like ‘protobifaces’ and cores with apparently ‘predetermined’ flake removals. This shows that the geometrical constraints of fracture mechanics can give rise to what appear to be highly-designed stoneworking products and techniques when multiple flakes are removed randomly from a stone core. PMID:27392022

Fossils, feet and the evolution of human bipedal locomotion

PubMed Central

Harcourt-Smith, W E H; Aiello, L C

2004-01-01

We review the evolution of human bipedal locomotion with a particular emphasis on the evolution of the foot. We begin in the early twentieth century and focus particularly on hypotheses of an ape-like ancestor for humans and human bipedal locomotion put forward by a succession of Gregory, Keith, Morton and Schultz. We give consideration to Morton's (1935) synthesis of foot evolution, in which he argues that the foot of the common ancestor of modern humans and the African apes would be intermediate between the foot of Pan and Hylobates whereas the foot of a hypothetical early hominin would be intermediate between that of a gorilla and a modern human. From this base rooted in comparative anatomy of living primates we trace changing ideas about the evolution of human bipedalism as increasing amounts of postcranial fossil material were discovered. Attention is given to the work of John Napier and John Robinson who were pioneers in the interpretation of Plio-Pleistocene hominin skeletons in the 1960s. This is the period when the wealth of evidence from the southern African australopithecine sites was beginning to be appreciated and Olduvai Gorge was revealing its first evidence for Homo habilis. In more recent years, the discovery of the Laetoli footprint trail, the AL 288-1 (A. afarensis) skeleton, the wealth of postcranial material from Koobi Fora, the Nariokotome Homo ergaster skeleton, Little Foot (Stw 573) from Sterkfontein in South Africa, and more recently tantalizing material assigned to the new and very early taxa Orrorin tugenensis, Ardipithecus ramidus and Sahelanthropus tchadensis has fuelled debate and speculation. The varying interpretations based on this material, together with changing theoretical insights and analytical approaches, is discussed and assessed in the context of new three-dimensional morphometric analyses of australopithecine and Homo foot bones, suggesting that there may have been greater diversity in human bipedalism in the earlier phases

Hominin responses to environmental changes during the Middle Pleistocene in central and southern Italy

NASA Astrophysics Data System (ADS)

Orain, R.; Lebreton, V.; Russo Ermolli, E.; Sémah, A.-M.; Nomade, S.; Shao, Q.; Bahain, J.-J.; Thun Hohenstein, U.; Peretto, C.

2013-03-01

The palaeobotanical record of early Palaeolithic sites from Western Europe indicates that hominins settled in different kinds of environments. During the "mid-Pleistocene transition (MPT)", from about 1 to 0.6 Ma, the transition from 41- to 100-ka dominant climatic oscillations, occurring within a long-term cooling trend, was associated with an aridity crisis which strongly modified the ecosystems. Starting from the MPT the more favourable climate of central and southern Italy provided propitious environmental conditions for long-term human occupations even during the glacial times. In fact, the human strategy of territory occupation was certainly driven by the availabilities of resources. Prehistoric sites such as Notarchirico (ca. 680-600 ka), La Pineta (ca. 600-620 ka), Guado San Nicola (ca. 380-350 ka) or Ceprano (ca. 345-355 ka) testify to a preferential occupation of the central and southern Apennines valleys during interglacial phases, while later interglacial occupations were oriented towards the coastal plains, as attested by the numerous settlements of the Roma Basin (ca. 300 ka). Faunal remains indicate that human subsistence behaviours benefited from a diversity of exploitable ecosystems, from semi-open to closed environments. In central and southern Italy, several palynological records have already illustrated the regional- and local-scale vegetation dynamic trends. During the Middle Pleistocene climate cycles, mixed mesophytic forests developed during the interglacial periods and withdrew in response to increasing aridity during the glacial episodes. New pollen data from the Boiano Basin (Molise, Italy) attest to the evolution of vegetation and climate between MIS 13 and 9 (ca. 500 to 300 ka). In this basin the persistence of high edaphic humidity, even during the glacial phases, could have favoured the establishment of a refuge area for the arboreal flora and provided subsistence resources for the animal and hominin communities during the Middle

Hominin responses to environmental changes during the Middle Pleistocene in Central and Southern Italy

NASA Astrophysics Data System (ADS)

Orain, R.; Lebreton, V.; Russo Ermolli, E.; Sémah, A.-M.; Nomade, S.; Shao, Q.; Bahain, J.-J.; Thun Hohenstein, U.; Peretto, C.

2012-10-01

The palaeobotanical record of early Palaeolithic sites from Western Europe indicates that hominins settled in different kinds of environments. During the "Mid-Pleistocene Transition (MPT)", from about 1 to 0.6 Ma, the transition from 41-ka to 100-ka dominant climatic oscillations, occurring within a long-term cooling trend, was associated with an aridity crisis which strongly modified the ecosystems. Starting from the MPT the more favorable climate of central and southern Italy provided propitious environmental conditions for long-term human occupations even during the glacial times. In fact, the human strategy of territory occupation was certainly driven by the availabilities of resources. Prehistoric sites such as Notarchirico (ca. 680-600 ka), La Pineta (ca. 600-620 ka), Gaudo San Nicola (ca. 380-350 ka) or Ceprano (ca. 345-355 ka) testify to a preferential occupation of the central and southern Apennines valleys during interglacial phases, while later interglacial occupations were oriented towards the coastal plains, as attested by the numerous settlements of the Roma basin (ca. 300 ka). Faunal remains indicate that human subsistence behaviors benefited of a diversity of exploitable ecosystems, from semi-open to closed environments. In central and southern Italy, several palynological records have already illustrated the regional and local scale vegetation dynamic trends. During the Middle Pleistocene climate cycles, mixed mesophytic forests developed during the interglacial periods and withdrew in response to increasing aridity during the glacial episodes. New pollen data from the Boiano basin (Molise, Italy), attest to the evolution of vegetation and climate between OIS 13 and 9 (ca. 500 to 300 ka). In this basin, the persistence of high edaphic humidity, even during the glacial phases, could have favored the establishment of a refuge area for the arboreal flora and provided subsistence resources for the animal and hominin communities during the Middle

Evolution of brain and culture: the neurological and cognitive journey from Australopithecus to Albert Einstein.

PubMed

Falk, Dean

2016-06-20

Fossil and comparative primatological evidence suggest that alterations in the development of prehistoric hominin infants kindled three consecutive evolutionary-developmental (evo-devo) trends that, ultimately, paved the way for the evolution of the human brain and cognition. In the earliest trend, infants' development of posture and locomotion became delayed because of anatomical changes that accompanied the prolonged evolution of bipedalism. Because modern humans have inherited these changes, our babies are much slower than other primates to reach developmental milestones such as standing, crawling, and walking. The delay in ancestral babies' physical development eventually precipitated an evolutionary reversal in which they became increasing unable to cling independently to their mothers. For the first time in prehistory, babies were, thus, periodically deprived of direct physical contact with their mothers. This prompted the emergence of a second evo-devo trend in which infants sought contact comfort from caregivers using evolved signals, including new ways of crying that are conserved in modern babies. Such signaling stimulated intense reciprocal interactions between prehistoric mothers and infants that seeded the eventual emergence of motherese and, subsequently, protolanguage. The third trend was for an extreme acceleration in brain growth that began prior to the last trimester of gestation and continued through infants' first postnatal year (early "brain spurt"). Conservation of this trend in modern babies explains why human brains reach adult sizes that are over three times those of chimpanzees. The fossil record of hominin cranial capacities together with comparative neuroanatomical data suggest that, around 3 million years ago, early brain spurts began to facilitate an evolutionary trajectory for increasingly large adult brains in association with neurological reorganization. The prehistoric increase in brain size eventually caused parturition to become

New immature hominin fossil from European Lower Pleistocene shows the earliest evidence of a modern human dental development pattern

PubMed Central

Bermúdez de Castro, José María; Martinón-Torres, María; Prado, Leyre; Gómez-Robles, Aida; Rosell, Jordi; López-Polín, Lucía; Arsuaga, Juan Luís; Carbonell, Eudald

2010-01-01

Here we present data concerning the pattern of dental development derived from the microcomputed tomography (microCT) study of a recently discovered immature hominin mandible with a mixed dentition recovered from the TD6 level of the Gran Dolina Lower Pleistocene cave site in Sierra de Atapuerca, northern Spain. These data confirm our previous results that nearly 1 million years ago at least one European hominin species had a fully modern pattern of dental development with a clear slowdown in the development of the molar field regarding the anterior dental field. Furthermore, using available information about enamel formation times and root extension rates in chimpanzees, early hominins, and modern humans, we have estimated that the formation time of the upper and lower first molars of individual 5 (H5) from TD6, which had just erupted at the time of the death of this individual, ranges between 5.3 and 6.6 y. Therefore, the eruption time of the first permanent molars (M1) in the TD6 hominins was within the range of variation of modern human populations. Because the time of M1 eruption in primates is a robust marker of life history, we suggest, as a working hypothesis, that these hominins had a prolonged childhood in the range of the variation of modern humans. If this hypothesis is true, it implies that the appearance in Homo of this important developmental biological feature and an associated increase in brain size preceded the development of the neocortical areas leading to the cognitive capabilities that are thought to be exclusive to Homo sapiens. PMID:20547843

A geometric morphometric analysis of hominin upper second and third molars, with particular emphasis on European Pleistocene populations.

PubMed

Gómez-Robles, Aida; Bermúdez de Castro, José María; Martinón-Torres, María; Prado-Simón, Leyre; Arsuaga, Juan Luis

2012-09-01

The study of dental morphology by means of geometric morphometric methods allows for a detailed and quantitative comparison of hominin species that is useful for taxonomic assignment and phylogenetic reconstruction. Upper second and third molars have been studied in a comprehensive sample of Plio- and Pleistocene hominins from African, Asian and European sites in order to complete our analysis of the upper postcanine dentition. Intraspecific variation in these two molars is high, but some interspecific trends can be identified. Both molars exhibit a strong reduction of the distal cusps in recent hominin species, namely European Homo heidelbergensis, Homo neanderthalensis and Homo sapiens, but this reduction shows specific patterns and proportions in the three groups. Second molars tend to show four well developed cusps in earlier hominin species and their morphology is only marginally affected by allometric effects. Third molars can be incipiently reduced in earlier species and they evince a significant allometric component, identified both inter- and intraspecifically. European Middle Pleistocene fossils from Sima de los Huesos (SH) show a very strong reduction of these two molars, even more marked than the reduction observed in Neanderthals and in modern human populations. The highly derived shape of SH molars points to an early acquisition of typical Neanderthal dental traits by pre-Neanderthal populations and to a deviation of this population from mean morphologies of other European Middle Pleistocene groups. Copyright © 2012 Elsevier Ltd. All rights reserved.

Divergent Ah Receptor Ligand Selectivity during Hominin Evolution

PubMed Central

Hubbard, Troy D.; Murray, Iain A.; Bisson, William H.; Sullivan, Alexis P.; Sebastian, Aswathy; Perry, George H.; Jablonski, Nina G.; Perdew, Gary H.

2016-01-01

We have identified a fixed nonsynonymous sequence difference between humans (Val381; derived variant) and Neandertals (Ala381; ancestral variant) in the ligand-binding domain of the aryl hydrocarbon receptor (AHR) gene. In an exome sequence analysis of four Neandertal and Denisovan individuals compared with nine modern humans, there are only 90 total nucleotide sites genome-wide for which archaic hominins are fixed for the ancestral nonsynonymous variant and the modern humans are fixed for the derived variant. Of those sites, only 27, including Val381 in the AHR, also have no reported variability in the human dbSNP database, further suggesting that this highly conserved functional variant is a rare event. Functional analysis of the amino acid variant Ala381 within the AHR carried by Neandertals and nonhuman primates indicate enhanced polycyclic aromatic hydrocarbon (PAH) binding, DNA binding capacity, and AHR mediated transcriptional activity compared with the human AHR. Also relative to human AHR, the Neandertal AHR exhibited 150–1000 times greater sensitivity to induction of Cyp1a1 and Cyp1b1 expression by PAHs (e.g., benzo(a)pyrene). The resulting CYP1A1/CYP1B1 enzymes are responsible for PAH first pass metabolism, which can result in the generation of toxic intermediates and perhaps AHR-associated toxicities. In contrast, the human AHR retains the ancestral sensitivity observed in primates to nontoxic endogenous AHR ligands (e.g., indole, indoxyl sulfate). Our findings reveal that a functionally significant change in the AHR occurred uniquely in humans, relative to other primates, that would attenuate the response to many environmental pollutants, including chemicals present in smoke from fire use during cooking. PMID:27486223

Late Middle Pleistocene hominin teeth from Panxian Dadong, South China.

PubMed

Liu, Wu; Schepartz, Lynne A; Xing, Song; Miller-Antonio, Sari; Wu, Xiujie; Trinkaus, Erik; Martinón-Torres, María

2013-05-01

The hominin teeth and evidence of hominin activities recovered from 1991 to 2005 at the Panxian Dadong site in South China are dated to the late Middle Pleistocene (MIS 8-6 or ca. 130-300 ka), a period for which very little is known about the morphology of Asian populations. The present study provides the first detailed morphometric description and comparisons of four hominin teeth (I(1), C1, P(3) and P3) from this site. Our study shows that the Panxian Dadong teeth combine archaic and derived features that align them with Middle and Upper Pleistocene fossils from East and West Asia and Europe. These teeth do not display any typical Neanderthal features and they are generally more derived than other contemporaneous populations from Asia and Africa. However, the derived traits are not diagnostic enough to specifically link the Panxian Dadong teeth to Homo sapiens, a common problem when analyzing the Middle Pleistocene dental record from Africa and Asia. These findings are contextualized in the discussion of the evolutionary course of Asian Middle Pleistocene hominins, and they highlight the necessity of incorporating the Asian fossil record in the still open debate about the origin of H. sapiens. Copyright © 2013 Elsevier Ltd. All rights reserved.

Embodied niche construction in the hominin lineage: semiotic structure and sustained attention in human embodied cognition

PubMed Central

Stutz, Aaron J.

2014-01-01

Human evolution unfolded through a rather distinctive, dynamically constructed ecological niche. The human niche is not only generally terrestrial in habitat, while being flexibly and extensively heterotrophic in food-web connections. It is also defined by semiotically structured and structuring embodied cognitive interfaces, connecting the individual organism with the wider environment. The embodied dimensions of niche-population co-evolution have long involved semiotic system construction, which I hypothesize to be an evolutionarily primitive aspect of learning and higher-level cognitive integration and attention in the great apes and humans alike. A clearly pre-linguistic form of semiotic cognitive structuration is suggested to involve recursively learned and constructed object icons. Higher-level cognitive iconic representation of visually, auditorily, or haptically perceived extrasomatic objects would be learned and evoked through indexical connections to proprioceptive and affective somatic states. Thus, private cognitive signs would be defined, not only by their learned and perceived extrasomatic referents, but also by their associations to iconically represented somatic states. This evolutionary modification of animal associative learning is suggested to be adaptive in ecological niches occupied by long-lived, large-bodied ape species, facilitating memory construction and recall in highly varied foraging and social contexts, while sustaining selective attention during goal-directed behavioral sequences. The embodied niche construction (ENC) hypothesis of human evolution posits that in the early hominin lineage, natural selection further modified the ancestral ape semiotic adaptations, favoring the recursive structuration of concise iconic narratives of embodied interaction with the environment. PMID:25136323

Embodied niche construction in the hominin lineage: semiotic structure and sustained attention in human embodied cognition.

PubMed

Stutz, Aaron J

2014-01-01

Human evolution unfolded through a rather distinctive, dynamically constructed ecological niche. The human niche is not only generally terrestrial in habitat, while being flexibly and extensively heterotrophic in food-web connections. It is also defined by semiotically structured and structuring embodied cognitive interfaces, connecting the individual organism with the wider environment. The embodied dimensions of niche-population co-evolution have long involved semiotic system construction, which I hypothesize to be an evolutionarily primitive aspect of learning and higher-level cognitive integration and attention in the great apes and humans alike. A clearly pre-linguistic form of semiotic cognitive structuration is suggested to involve recursively learned and constructed object icons. Higher-level cognitive iconic representation of visually, auditorily, or haptically perceived extrasomatic objects would be learned and evoked through indexical connections to proprioceptive and affective somatic states. Thus, private cognitive signs would be defined, not only by their learned and perceived extrasomatic referents, but also by their associations to iconically represented somatic states. This evolutionary modification of animal associative learning is suggested to be adaptive in ecological niches occupied by long-lived, large-bodied ape species, facilitating memory construction and recall in highly varied foraging and social contexts, while sustaining selective attention during goal-directed behavioral sequences. The embodied niche construction (ENC) hypothesis of human evolution posits that in the early hominin lineage, natural selection further modified the ancestral ape semiotic adaptations, favoring the recursive structuration of concise iconic narratives of embodied interaction with the environment.

Hominin track assemblages from Okote Member deposits near Ileret, Kenya, and their implications for understanding fossil hominin paleobiology at 1.5 Ma.

PubMed

Hatala, Kevin G; Roach, Neil T; Ostrofsky, Kelly R; Wunderlich, Roshna E; Dingwall, Heather L; Villmoare, Brian A; Green, David J; Braun, David R; Harris, John W K; Behrensmeyer, Anna K; Richmond, Brian G

2017-11-01

Tracks can provide unique, direct records of behaviors of fossil organisms moving across their landscapes millions of years ago. While track discoveries have been rare in the human fossil record, over the last decade our team has uncovered multiple sediment surfaces within the Okote Member of the Koobi Fora Formation near Ileret, Kenya that contain large assemblages of ∼1.5 Ma fossil hominin tracks. Here, we provide detailed information on the context and nature of each of these discoveries, and we outline the specific data that are preserved on the Ileret hominin track surfaces. We analyze previously unpublished data to refine and expand upon earlier hypotheses regarding implications for hominin anatomy and social behavior. While each of the track surfaces discovered at Ileret preserves a different amount of data that must be handled in particular ways, general patterns are evident. Overall, the analyses presented here support earlier interpretations of the ∼1.5 Ma Ileret track assemblages, providing further evidence of large, human-like body sizes and possibly evidence of a group composition that could support the emergence of certain human-like patterns of social behavior. These data, used in concert with other forms of paleontological and archaeological evidence that are deposited on different temporal scales, offer unique windows through which we can broaden our understanding of the paleobiology of hominins living in East Africa at ∼1.5 Ma. Copyright © 2017 Elsevier Ltd. All rights reserved.

Network analysis of the hominin origin of Herpes Simplex virus 2 from fossil data

PubMed Central

Underdown, Simon J.; Kumar, Krishna

2017-01-01

Abstract Herpes simplex virus 2 (HSV2) is a human herpesvirus found worldwide that causes genital lesions and more rarely causes encephalitis. This pathogen is most common in Africa, and particularly in central and east Africa, an area of particular significance for the evolution of modern humans. Unlike HSV1, HSV2 has not simply co-speciated with humans from their last common ancestor with primates. HSV2 jumped the species barrier between 1.4 and 3 MYA, most likely through intermediate but unknown hominin species. In this article, we use probability-based network analysis to determine the most probable transmission path between intermediate hosts of HSV2, from the ancestors of chimpanzees to the ancestors of modern humans, using paleo-environmental data on the distribution of African tropical rainforest over the last 3 million years and data on the age and distribution of fossil species of hominin present in Africa between 1.4 and 3 MYA. Our model identifies Paranthropus boisei as the most likely intermediate host of HSV2, while Homo habilis may also have played a role in the initial transmission of HSV2 from the ancestors of chimpanzees to P.boisei. PMID:28979799

Network analysis of the hominin origin of Herpes Simplex virus 2 from fossil data.

PubMed

Underdown, Simon J; Kumar, Krishna; Houldcroft, Charlotte

2017-07-01

Herpes simplex virus 2 (HSV2) is a human herpesvirus found worldwide that causes genital lesions and more rarely causes encephalitis. This pathogen is most common in Africa, and particularly in central and east Africa, an area of particular significance for the evolution of modern humans. Unlike HSV1, HSV2 has not simply co-speciated with humans from their last common ancestor with primates. HSV2 jumped the species barrier between 1.4 and 3 MYA, most likely through intermediate but unknown hominin species. In this article, we use probability-based network analysis to determine the most probable transmission path between intermediate hosts of HSV2, from the ancestors of chimpanzees to the ancestors of modern humans, using paleo-environmental data on the distribution of African tropical rainforest over the last 3 million years and data on the age and distribution of fossil species of hominin present in Africa between 1.4 and 3 MYA. Our model identifies Paranthropus boisei as the most likely intermediate host of HSV2, while Homo habilis may also have played a role in the initial transmission of HSV2 from the ancestors of chimpanzees to P.boisei .

Edaphics, active tectonics and animal movements in the Kenyan Rift - implications for early human evolution and dispersal

NASA Astrophysics Data System (ADS)

Kübler, Simon; Owenga, Peter; Rucina, Stephen; King, Geoffrey C. P.

2014-05-01

The quality of soils (edaphics) and the associated vegetation strongly controls the health of grazing animals. Until now, this has hardly been appreciated by paleo-anthropologists who only take into account the availability of water and vegetation in landscape reconstruction attempts. A lack of understanding the importance of the edaphics of a region greatly limits interpretations of the relation between our ancestors and animals over the last few million years. If a region lacks vital trace elements then wild grazing and browsing animals will avoid it and go to considerable length and take major risks to seek out better pasture. As a consequence animals must move around the landscape at different times of the year. In complex landscapes, such as tectonically active rifts, hominins can use advanced group behaviour to gain strategic advantage for hunting. Our study in the southern Kenya rift in the Lake Magadi region shows that the edaphics and active rift structures play a key role in present day animal movements as well as the for the location of an early hominin site at Mt. Olorgesailie. We carried out field analysis based on studying the relationship between the geology and soil development as well as the tectonic geomorphology to identify 'good' and 'bad' regions both in terms of edaphics and accessibility for grazing animals. We further sampled different soils that developed on the volcanic bedrock and sediment sources of the region and interviewed the local Maasai shepherds to learn about present-day good and bad grazing sites. At the Olorgesailie site the rift valley floor is covered with flood trachytes; basalts only occur at Mt. Olorgesailie and farther east up the rift flank. The hominin site is located in lacustrine sediments at the southern edge of a playa that extends north and northwest of Mt. Olorgesailie. The lakebeds are now tilted and eroded by motion on two north-south striking faults. The lake was trapped by basalt flows from Mt. Olorgesailie

Plio-Pleistocene vegetation response on orbitally forced climatic cycles in Southern Europe - implications for early human environments

NASA Astrophysics Data System (ADS)

Bruch, Angela; Bertini, Adele

2013-04-01

The pace and causes of the early human colonization, in one or several migratory waves from Africa in new environments of the Eurasian continent during the Early Pleistocene, are still a matter of debate. However, climate change is considered a major driving factor of hominin evolution and dispersal patterns. In fact directly or indirectly by its severe influence on vegetation, physiography of landscape, and animal distribution, climate modulates the availability of resources. Plant fossils usually are rare or even absent at hominin sites. Thus, direct evidence on local vegetation and environment is generally missing. Independent from such localities, pollen profiles from the Mediterranean realm show the response of regional vegetation on global climate changes and cyclicity, with distinct spatial and temporal differences. Furthermore, plant fossils provide proxies for climate quantification that can be compared to the global signal, and add data to understanding the regional differentiation of Mediterranean environments. In this presentation we will discuss various palaeobotanical data from Southern Europe to assess Early Pleistocene climate and vegetation in time and space as part of the environment during the first expansions of early humans out of Africa.

Key cognitive preconditions for the evolution of language.

PubMed

Donald, Merlin

2017-02-01

Languages are socially constructed systems of expression, generated interactively in social networks, which can be assimilated by the individual brain as it develops. Languages co-evolved with culture, reflecting the changing complexity of human culture as it acquired the properties of a distributed cognitive system. Two key preconditions set the stage for the evolution of such cultures: a very general ability to rehearse and refine skills (evident early in hominin evolution in toolmaking), and the emergence of material culture as an external (to the brain) memory record that could retain and accumulate knowledge across generations. The ability to practice and rehearse skill provided immediate survival-related benefits in that it expanded the physical powers of early hominins, but the same adaptation also provided the imaginative substrate for a system of "mimetic" expression, such as found in ritual and pantomime, and in proto-words, which performed an expressive function somewhat like the home signs of deaf non-signers. The hominid brain continued to adapt to the increasing importance and complexity of culture as human interactions with material culture became more complex; above all, this entailed a gradual expansion in the integrative systems of the brain, especially those involved in the metacognitive supervision of self-performances. This supported a style of embodied mimetic imagination that improved the coordination of shared activities such as fire tending, but also in rituals and reciprocal mimetic games. The time-depth of this mimetic adaptation, and its role in both the construction and acquisition of languages, explains the importance of mimetic expression in the media, religion, and politics. Spoken language evolved out of voco-mimesis, and emerged long after the more basic abilities needed to refine skill and share intentions, probably coinciding with the common ancestor of sapient humans. Self-monitoring and self-supervised practice were necessary

Kinematics of the anthropoid os centrale and the functional consequences of scaphoid-centrale fusion in African apes and hominins.

PubMed

Orr, Caley M

2018-01-01

In most primates, the os centrale is interposed between the scaphoid, trapezoid, trapezium, and head of the capitate, thus constituting a component of the wrist's midcarpal complex. Scaphoid-centrale fusion is among the clearest morphological synapomorphies of African apes and hominins. Although it might facilitate knuckle-walking by increasing the rigidity and stability of the radial side of the wrist, the exact functional significance of scaphoid-centrale fusion is unclear. If fusion acts to produce a more rigid radial wrist that stabilizes the hand and limits shearing stresses, then in taxa with a free centrale, it should anchor ligaments that check extension and radial deviation, but exhibit motion independent of the scaphoid. Moreover, because the centrale sits between the scaphoid and capitate (a major stabilizing articulation), scaphoid-centrale mobility should correlate with scaphocapitate mobility in extension and radial deviation. To test these hypotheses, the centrale's ligamentous binding was investigated via dissection in Pongo and Papio, and the kinematics of the centrale were quantified in a cadaveric sample of anthropoids (Pongo sp., Ateles geoffroyi, Colobus guereza, Macaca mulatta, and Papio anubis) using a computed-tomography-based method to track wrist-bone motion. Results indicate that the centrale rotates freely relative to the scaphoid in all taxa. However, centrale mobility is only correlated with scaphocapitate mobility during extension in Pongo-possibly due to differences in overall wrist configuration between apes and monkeys. If an extant ape-like wrist characterized early ancestors of African apes and hominins, then scaphoid-centrale fusion would have increased midcarpal rigidity in extension relative to the primitive condition. Although biomechanically consistent with a knuckle-walking hominin ancestor, this assumes that the trait evolved specifically for that biological role, which must be squared with contradictory interpretations of

Influence of Plio-Pleistocene basin hydrology on the Turkana hominin enamel carbonate δ(18)O values.

PubMed

Quinn, Rhonda L

2015-09-01

Stable oxygen isotopes of hominin enamel carbonate (δ(18)OEC) provide a window into aspects of past drinking behavior and diet, body size, breastfeeding and weaning, mobility, and paleoclimate. It is tempting to compare all hominins across time and space in order to gauge species-level adaptations to changing environments and niche separation between those living sympatrically. Basinal, sub-basinal, and micro-environmental differences, however, may exert an influence on variation in enamel carbonate isotopic values that must be reconciled before hominin species across Africa can be meaningfully compared. Plio-Pleistocene Turkana hominin δ(18)OEC values show a considerable spread, potentially revealing many intrinsic and extrinsic contributing factors operating on different scales. In this study, I examine Turkana hominin δ(18)OEC values relative to identity (taxon, tooth type and number, body size of taxon), dietary (δ(13)C value, Turkana coeval and modern mammalian δ(18)OEC values), and contextual (time, depositional environment) information of each specimen and collection locality and discuss various potential influences. Turkana hominin δ(18)OEC values may primarily reflect differences in imbibed water sources (lake vs. river) as a function of evolving basin hydrology. Copyright © 2015 Elsevier Ltd. All rights reserved.

Intra-individual metameric variation expressed at the enamel-dentine junction of lower post-canine dentition of South African fossil hominins and modern humans.

PubMed

Pan, Lei; Thackeray, John Francis; Dumoncel, Jean; Zanolli, Clément; Oettlé, Anna; de Beer, Frikkie; Hoffman, Jakobus; Duployer, Benjamin; Tenailleau, Christophe; Braga, José

2017-08-01

The aim of this study is to compare the degree and patterning of inter- and intra-individual metameric variation in South African australopiths, early Homo and modern humans. Metameric variation likely reflects developmental and taxonomical issues, and could also be used to infer ecological and functional adaptations. However, its patterning along the early hominin postcanine dentition, particularly among South African fossil hominins, remains unexplored. Using microfocus X-ray computed tomography (µXCT) and geometric morphometric tools, we studied the enamel-dentine junction (EDJ) morphology and we investigated the intra- and inter-individual EDJ metameric variation among eight australopiths and two early Homo specimens from South Africa, as well as 32 modern humans. Along post-canine dentition, shape changes between metameres represented by relative positions and height of dentine horns, outlines of the EDJ occlusal table are reported in modern and fossil taxa. Comparisons of EDJ mean shapes and multivariate analyses reveal substantial variation in the direction and magnitude of metameric shape changes among taxa, but some common trends can be found. In modern humans, both the direction and magnitude of metameric shape change show increased variability in M 2 -M 3 compared to M 1 -M 2 . Fossil specimens are clustered together showing similar magnitudes of shape change. Along M 2 -M 3 , the lengths of their metameric vectors are not as variable as those of modern humans, but they display considerable variability in the direction of shape change. The distalward increase of metameric variation along the modern human molar row is consistent with the odontogenetic models of molar row structure (inhibitory cascade model). Though much remains to be tested, the variable trends and magnitudes in metamerism in fossil hominins reported here, together with differences in the scale of shape change between modern humans and fossil hominins may provide valuable information

A leaf wax biomarker record of early Pleistocene hydroclimate from West Turkana, Kenya

NASA Astrophysics Data System (ADS)

Lupien, R. L.; Russell, J. M.; Feibel, C.; Beck, C.; Castañeda, I.; Deino, A.; Cohen, A. S.

2018-04-01

Climate is thought to play a critical role in human evolution; however, this hypothesis is difficult to test due to a lack of long, high-quality paleoclimate records from key hominin fossil locales. To address this issue, we analyzed organic geochemical indicators of climate in a drill core from West Turkana, Kenya that spans ∼1.9-1.4 Ma, an interval that includes several important hominin evolutionary transitions. We analyzed the hydrogen isotopic composition of terrestrial plant waxes (δDwax) to reconstruct orbital-timescale changes in regional hydrology and their relationship with global climate forcings and the hominin fossil record. Our data indicate little change in the long-term mean hydroclimate during this interval, in contrast to inferred changes in the level of Lake Turkana, suggesting that lake level may be responding dominantly to deltaic progradation or tectonically-driven changes in basin configuration as opposed to hydroclimate. Time-series spectral analyses of the isotopic data reveal strong precession-band (21 kyr) periodicity, indicating that regional hydroclimate was strongly affected by changes in insolation. We observe an interval of particularly high-amplitude hydrologic variation at ∼1.7 Ma, which occurs during a time of high orbital eccentricity hence large changes in processionally-driven insolation amplitude. This interval overlaps with multiple hominin species turnovers, the appearance of new stone tool technology, and hominin dispersal out of Africa, supporting the notion that climate variability played an important role in hominin evolution.

Homo floresiensis-like fossils from the early Middle Pleistocene of Flores.

PubMed

van den Bergh, Gerrit D; Kaifu, Yousuke; Kurniawan, Iwan; Kono, Reiko T; Brumm, Adam; Setiyabudi, Erick; Aziz, Fachroel; Morwood, Michael J

2016-06-09

The evolutionary origin of Homo floresiensis, a diminutive hominin species previously known only by skeletal remains from Liang Bua in western Flores, Indonesia, has been intensively debated. It is a matter of controversy whether this primitive form, dated to the Late Pleistocene, evolved from early Asian Homo erectus and represents a unique and striking case of evolutionary reversal in hominin body and brain size within an insular environment. The alternative hypothesis is that H. floresiensis derived from an older, smaller-brained member of our genus, such as Homo habilis, or perhaps even late Australopithecus, signalling a hitherto undocumented dispersal of hominins from Africa into eastern Asia by two million years ago (2 Ma). Here we describe hominin fossils excavated in 2014 from an early Middle Pleistocene site (Mata Menge) in the So'a Basin of central Flores. These specimens comprise a mandible fragment and six isolated teeth belonging to at least three small-jawed and small-toothed individuals. Dating to ~0.7 Ma, these fossils now constitute the oldest hominin remains from Flores. The Mata Menge mandible and teeth are similar in dimensions and morphological characteristics to those of H. floresiensis from Liang Bua. The exception is the mandibular first molar, which retains a more primitive condition. Notably, the Mata Menge mandible and molar are even smaller in size than those of the two existing H. floresiensis individuals from Liang Bua. The Mata Menge fossils are derived compared with Australopithecus and H. habilis, and so tend to support the view that H. floresiensis is a dwarfed descendent of early Asian H. erectus. Our findings suggest that hominins on Flores had acquired extremely small body size and other morphological traits specific to H. floresiensis at an unexpectedly early time.

Early Pleistocene 40Ar/39Ar ages for Bapang Formation hominins, Central Jawa, Indonesia

PubMed Central

Larick, Roy; Ciochon, Russell L.; Zaim, Yahdi; Sudijono; Suminto; Rizal, Yan; Aziz, Fachroel; Reagan, Mark; Heizler, Matthew

2001-01-01

The Sangiran dome is the primary stratigraphic window for the Plio-Pleistocene deposits of the Solo basin of Central Jawa. The dome has yielded nearly 80 Homo erectus fossils, around 50 of which have known findspots. With a hornblende 40Ar/39Ar plateau age of 1.66 ± 0.04 mega-annum (Ma) reportedly associated with two fossils [Swisher, C.C., III, Curtis, G. H., Jacob, T., Getty, A. G., Suprijo, A. & Widiasmoro (1994) Science 263, 1118–1121), the dome offers evidence that early Homo dispersed to East Asia during the earliest Pleistocene. Unfortunately, the hornblende pumice was sampled at Jokotingkir Hill, a central locality with complex lithostratigraphic deformation and dubious specimen provenance. To address the antiquity of Sangiran H. erectus more systematically, we investigate the sedimentary framework and hornblende 40Ar/39Ar age for volcanic deposits in the southeast quadrant of the dome. In this sector, Bapang (Kabuh) sediments have their largest exposure, least deformation, and most complete tephrostratigraphy. At five locations, we identify a sequence of sedimentary cycles in which H. erectus fossils are associated with epiclastic pumice. From sampled pumice, eight hornblende separates produced 40Ar/39Ar plateau ages ranging from 1.51 ± 0.08 Ma at the Bapang/Sangiran Formation contact, to 1.02 ± 0.06 Ma, at a point above the hominin-bearing sequence. The chronological sequence of 40Ar/39Ar ages follows stratigraphic order across the southeast quadrant. An intermediate level yielding four nearly complete crania has an age of about 1.25 Ma. PMID:11309488

Early Pleistocene 40Ar/39Ar ages for Bapang Formation hominins, Central Jawa, Indonesia.

PubMed

Larick, R; Ciochon, R L; Zaim, Y; Sudijono; Suminto; Rizal, Y; Aziz, F; Reagan, M; Heizler, M

2001-04-24

The Sangiran dome is the primary stratigraphic window for the Plio-Pleistocene deposits of the Solo basin of Central Jawa. The dome has yielded nearly 80 Homo erectus fossils, around 50 of which have known findspots. With a hornblende (40)Ar/(39)Ar plateau age of 1.66 +/- 0.04 mega-annum (Ma) reportedly associated with two fossils [Swisher, C.C., III, Curtis, G. H., Jacob, T., Getty, A. G., Suprijo, A. & Widiasmoro (1994) Science 263, 1118-1121), the dome offers evidence that early Homo dispersed to East Asia during the earliest Pleistocene. Unfortunately, the hornblende pumice was sampled at Jokotingkir Hill, a central locality with complex lithostratigraphic deformation and dubious specimen provenance. To address the antiquity of Sangiran H. erectus more systematically, we investigate the sedimentary framework and hornblende (40)Ar/(39)Ar age for volcanic deposits in the southeast quadrant of the dome. In this sector, Bapang (Kabuh) sediments have their largest exposure, least deformation, and most complete tephrostratigraphy. At five locations, we identify a sequence of sedimentary cycles in which H. erectus fossils are associated with epiclastic pumice. From sampled pumice, eight hornblende separates produced (40)Ar/(39)Ar plateau ages ranging from 1.51 +/- 0.08 Ma at the Bapang/Sangiran Formation contact, to 1.02 +/- 0.06 Ma, at a point above the hominin-bearing sequence. The chronological sequence of (40)Ar/(39)Ar ages follows stratigraphic order across the southeast quadrant. An intermediate level yielding four nearly complete crania has an age of about 1.25 Ma.

The evolution of human and ape hand proportions.

PubMed

Almécija, Sergio; Smaers, Jeroen B; Jungers, William L

2015-07-14

Human hands are distinguished from apes by possessing longer thumbs relative to fingers. However, this simple ape-human dichotomy fails to provide an adequate framework for testing competing hypotheses of human evolution and for reconstructing the morphology of the last common ancestor (LCA) of humans and chimpanzees. We inspect human and ape hand-length proportions using phylogenetically informed morphometric analyses and test alternative models of evolution along the anthropoid tree of life, including fossils like the plesiomorphic ape Proconsul heseloni and the hominins Ardipithecus ramidus and Australopithecus sediba. Our results reveal high levels of hand disparity among modern hominoids, which are explained by different evolutionary processes: autapomorphic evolution in hylobatids (extreme digital and thumb elongation), convergent adaptation between chimpanzees and orangutans (digital elongation) and comparatively little change in gorillas and hominins. The human (and australopith) high thumb-to-digits ratio required little change since the LCA, and was acquired convergently with other highly dexterous anthropoids.

The evolution of human and ape hand proportions

PubMed Central

Almécija, Sergio; Smaers, Jeroen B.; Jungers, William L.

2015-01-01

Human hands are distinguished from apes by possessing longer thumbs relative to fingers. However, this simple ape-human dichotomy fails to provide an adequate framework for testing competing hypotheses of human evolution and for reconstructing the morphology of the last common ancestor (LCA) of humans and chimpanzees. We inspect human and ape hand-length proportions using phylogenetically informed morphometric analyses and test alternative models of evolution along the anthropoid tree of life, including fossils like the plesiomorphic ape Proconsul heseloni and the hominins Ardipithecus ramidus and Australopithecus sediba. Our results reveal high levels of hand disparity among modern hominoids, which are explained by different evolutionary processes: autapomorphic evolution in hylobatids (extreme digital and thumb elongation), convergent adaptation between chimpanzees and orangutans (digital elongation) and comparatively little change in gorillas and hominins. The human (and australopith) high thumb-to-digits ratio required little change since the LCA, and was acquired convergently with other highly dexterous anthropoids. PMID:26171589

The Middle Pleistocene archaeological record of Greece and the role of the Aegean in hominin dispersals: new data and interpretations

NASA Astrophysics Data System (ADS)

Tourloukis, Vangelis; Karkanas, Panagiotis

2012-06-01

In the debate about hominin dispersals, Greece is expected to have been among the core areas for the peopling of Eurasia, serving as a 'refugium' and source region for (re)colonizations. Yet, its early Pleistocene record is still scarce, forming a conspicuous 'gap' in the early human geography of the Mediterranean. Here we investigate this gap and provide for the first time a synthesis of the Lower Palaeolithic record of Greece. Our study adopts a geoarchaeological approach to explain the current status of the record and argues that the 'absence of evidence' should be understood as the result of the biasing effects of erosional geomorphic processes and not as an indication of a former absence of hominins. In this line, the potential for archaeological preservation and recovery is assessed as a function of landscape dynamics. Climatic seasonality, tectonic activity, high relief and marine inundations have altogether contributed to significant reworking and/or total loss of archaeological sites: in spatial terms, only about 2-5% of the Lower Palaeolithic record of Greece may have survived up to the present. On the other hand, we interpret recent geological data, which show that half of the Aegean Sea would have been subaerially exposed for most of the early Pleistocene. Our results emphasize the potentially central role of the Aegean region in hominin dispersals, both as a biogeographical landbridge and as a highly productive landscape for occupation. This conclusion opens up new prospects for future fieldwork in an area that was hitherto essentially neglected. Finally, in showing how geomorphic processes bias site distribution patterns, the results and methodological perspective developed here can be seen as having implications that are wider than the geographical limits of the Greek Peninsula: they are pertinent to the investigation and interpretation of the early Pleistocene archaeological records in the highly dynamic landscapes of southern Europe - if not in

New radiometric ages for the BH-1 hominin from Balanica (Serbia): implications for understanding the role of the Balkans in Middle Pleistocene human evolution.

PubMed

Rink, William J; Mercier, Norbert; Mihailović, Dušan; Morley, Mike W; Thompson, Jeroen W; Roksandic, Mirjana

2013-01-01

Newly obtained ages, based on electron spin resonance combined with uranium series isotopic analysis, and infrared/post-infrared luminescence dating, provide a minimum age that lies between 397 and 525 ka for the hominin mandible BH-1 from Mala Balanica cave, Serbia. This confirms it as the easternmost hominin specimen in Europe dated to the Middle Pleistocene. Inferences drawn from the morphology of the mandible BH-1 place it outside currently observed variation of European Homo heidelbergensis. The lack of derived Neandertal traits in BH-1 and its contemporary specimens in Southeast Europe, such as Kocabaş, Vasogliano and Ceprano, coupled with Middle Pleistocene synapomorphies, suggests different evolutionary forces acting in the east of the continent where isolation did not play such an important role during glaciations.

The Advantage of Standing Up to Fight and the Evolution of Habitual Bipedalism in Hominins

PubMed Central

Carrier, David R.

2011-01-01

Background Many quadrupedal species stand bipedally on their hindlimbs to fight. This posture may provide a performance advantage by allowing the forelimbs to strike an opponent with the range of motion that is intrinsic to high-speed running, jumping, rapid braking and turning; the range of motion over which peak force and power can be produced. Methodology/Principal Findings To test the hypothesis that bipedal (i.e., orthograde) posture provides a performance advantage when striking with the forelimbs, I measured the force and energy produced when human subjects struck from “quadrupedal” (i.e., pronograde) and bipedal postures. Downward and upward directed striking energy was measured with a custom designed pendulum transducer. Side and forward strikes were measured with a punching bag instrumented with an accelerometer. When subjects struck downward from a bipedal posture the work was 43.70±12.59% (mean ± S.E.) greater than when they struck from a quadrupedal posture. Similarly, 47.49±17.95% more work was produced when subjects struck upward from a bipedal stance compared to a quadrupedal stance. Importantly, subjects did 229.69±44.19% more work in downward than upward directed strikes. During side and forward strikes the force impulses were 30.12±3.68 and 43.04±9.00% greater from a bipedal posture than a quadrupedal posture, respectively. Conclusions/Significance These results indicate that bipedal posture does provide a performance advantage for striking with the forelimbs. The mating systems of great apes are characterized by intense male-male competition in which conflict is resolved through force or the threat of force. Great apes often fight from bipedal posture, striking with both the fore- and hindlimbs. These observations, plus the findings of this study, suggest that sexual selection contributed to the evolution of habitual bipedalism in hominins. PMID:21611167

Preserving the Impossible: Conservation of Soft-Sediment Hominin Footprint Sites and Strategies for Three-Dimensional Digital Data Capture

PubMed Central

Bennett, Matthew R.; Falkingham, Peter; Morse, Sarita A.; Bates, Karl; Crompton, Robin H.

2013-01-01

Human footprints provide some of the most publically emotive and tangible evidence of our ancestors. To the scientific community they provide evidence of stature, presence, behaviour and in the case of early hominins potential evidence with respect to the evolution of gait. While rare in the geological record the number of footprint sites has increased in recent years along with the analytical tools available for their study. Many of these sites are at risk from rapid erosion, including the Ileret footprints in northern Kenya which are second only in age to those at Laetoli (Tanzania). Unlithified, soft-sediment footprint sites such these pose a significant geoconservation challenge. In the first part of this paper conservation and preservation options are explored leading to the conclusion that to ‘record and digitally rescue’ provides the only viable approach. Key to such strategies is the increasing availability of three-dimensional data capture either via optical laser scanning and/or digital photogrammetry. Within the discipline there is a developing schism between those that favour one approach over the other and a requirement from geoconservationists and the scientific community for some form of objective appraisal of these alternatives is necessary. Consequently in the second part of this paper we evaluate these alternative approaches and the role they can play in a ‘record and digitally rescue’ conservation strategy. Using modern footprint data, digital models created via optical laser scanning are compared to those generated by state-of-the-art photogrammetry. Both methods give comparable although subtly different results. This data is evaluated alongside a review of field deployment issues to provide guidance to the community with respect to the factors which need to be considered in digital conservation of human/hominin footprints. PMID:23613743

Spatial organization of hominin activities at Gesher Benot Ya'aqov, Israel.

PubMed

Alperson-Afil, Nira; Sharon, Gonen; Kislev, Mordechai; Melamed, Yoel; Zohar, Irit; Ashkenazi, Shosh; Rabinovich, Rivka; Biton, Rebecca; Werker, Ella; Hartman, Gideon; Feibel, Craig; Goren-Inbar, Naama

2009-12-18

The spatial designation of discrete areas for different activities reflects formalized conceptualization of a living space. The results of spatial analyses of a Middle Pleistocene Acheulian archaeological horizon (about 750,000 years ago) at Gesher Benot Ya'aqov, Israel, indicate that hominins differentiated their activities (stone knapping, tool use, floral and faunal processing and consumption) across space. These were organized in two main areas, including multiple activities around a hearth. The diversity of human activities and the distinctive patterning with which they are organized implies advanced organizational skills of the Gesher Benot Ya'aqov hominins.

The bony labyrinth of the middle Pleistocene Sima de los Huesos hominins (Sierra de Atapuerca, Spain).

PubMed

Quam, Rolf; Lorenzo, Carlos; Martínez, Ignacio; Gracia-Téllez, Ana; Arsuaga, Juan Luis

2016-01-01

We performed 3D virtual reconstructions based on CT scans to study the bony labyrinth morphology in 14 individuals from the large middle Pleistocene hominin sample from the site of the Sima de los Huesos (SH) in the Sierra de Atapuerca in northern Spain. The Atapuerca (SH) hominins represent early members of the Neandertal clade and provide an opportunity to compare the data with the later in time Neandertals, as well as Pleistocene and recent humans more broadly. The Atapuerca (SH) hominins do not differ from the Neandertals in any of the variables related to the absolute and relative sizes and shape of the semicircular canals. Indeed, the entire Neandertal clade seems to be characterized by a derived pattern of canal proportions, including a relatively small posterior canal and a relatively large lateral canal. In contrast, one of the most distinctive features observed in Neandertals, the low placement of the posterior canal (i.e., high sagittal labyrinthine index), is generally not present in the Atapuerca (SH) hominins. This low placement is considered a derived feature in Neandertals and is correlated with a more vertical orientation of the ampullar line (LSCm < APA), posterior surface of the petrous pyramid (LSCm > PPp), and third part of the facial canal (LSCm < FC3). Some variation is present within the Atapuerca (SH) sample, however, with a few individuals approaching the Neandertal condition more closely. In addition, the cochlear shape index in the Atapuerca (SH) hominins is low, indicating a reduction in the height of the cochlea. Although the phylogenetic polarity of this feature is less clear, the low shape index in the Atapuerca (SH) hominins may be a derived feature. Regardless, cochlear height subsequently increased in Neandertals. In contrast to previous suggestions, the expanded data in the present study indicate no difference across the genus Homo in the angle of inclination of the cochlear basal turn (COs < LSCm). Principal components

Oxygen and Early Animal Evolution

NASA Astrophysics Data System (ADS)

Xiao, S.

2012-12-01

It is often hypothesized that the rise of animals was triggered by an increase in O2 levels in the atmosphere and oceans. However, this hypothesis is remarkably difficult to test, because the timing of animal divergences is poorly resolved, the physiology of early animals is often unknown, estimates of past pO2 levels come with large error bars, and causal relationships between oxygenation and animal evolution are difficult to establish. Nonetheless, existing phylogenetic, paleontological, and geochemical data indicate that the evolution of macroscopic animals and motile macrometazoans with energetically expensive lifestyles may be temporally coupled with ocean oxygenation events in the Ediacaran Period. Thus, it is plausible that ocean oxygenation may have been a limiting factor in the early evolution of macroscopic, complex, and metabolically aggressive animals (particularly bilaterian animals). However, ocean oxygenation and animal evolution were likely engaged in two-way interactions: Ediacaran oxygenation may have initially lifted a physiological barrier for the evolution of animal size, motility, and active lifestyles, but subsequent animal diversification in the Paleozoic may have also changed oceanic redox structures. Viewed in a broader context, the early evolutionary history of animals was contingent upon a series of events, including genetic preparation (developmental genetics), environmental facilitation (oceanic oxygenation), and ecological escalation (Cambrian explosion), but the rise of animals to ecological importance also had important geobiological impacts on oceanic redox structures, sedimentary fabrics, and global geochemical cycles.

Earliest hominin occupation of Sulawesi, Indonesia

NASA Astrophysics Data System (ADS)

van den Bergh, Gerrit D.; Li, Bo; Brumm, Adam; Grün, Rainer; Yurnaldi, Dida; Moore, Mark W.; Kurniawan, Iwan; Setiawan, Ruly; Aziz, Fachroel; Roberts, Richard G.; Suyono; Storey, Michael; Setiabudi, Erick; Morwood, Michael J.

2016-01-01

Sulawesi is the largest and oldest island within Wallacea, a vast zone of oceanic islands separating continental Asia from the Pleistocene landmass of Australia and Papua (Sahul). By one million years ago an unknown hominin lineage had colonized Flores immediately to the south, and by about 50 thousand years ago, modern humans (Homo sapiens) had crossed to Sahul. On the basis of position, oceanic currents and biogeographical context, Sulawesi probably played a pivotal part in these dispersals. Uranium-series dating of speleothem deposits associated with rock art in the limestone karst region of Maros in southwest Sulawesi has revealed that humans were living on the island at least 40 thousand years ago (ref. 5). Here we report new excavations at Talepu in the Walanae Basin northeast of Maros, where in situ stone artefacts associated with fossil remains of megafauna (Bubalus sp., Stegodon and Celebochoerus) have been recovered from stratified deposits that accumulated from before 200 thousand years ago until about 100 thousand years ago. Our findings suggest that Sulawesi, like Flores, was host to a long-established population of archaic hominins, the ancestral origins and taxonomic status of which remain elusive.

New Radiometric Ages for the BH-1 Hominin from Balanica (Serbia): Implications for Understanding the Role of the Balkans in Middle Pleistocene Human Evolution

PubMed Central

Rink, William J.; Mercier, Norbert; Mihailović, Dušan; Morley, Mike W.; Thompson, Jeroen W.; Roksandic, Mirjana

2013-01-01

Newly obtained ages, based on electron spin resonance combined with uranium series isotopic analysis, and infrared/post-infrared luminescence dating, provide a minimum age that lies between 397 and 525 ka for the hominin mandible BH-1 from Mala Balanica cave, Serbia. This confirms it as the easternmost hominin specimen in Europe dated to the Middle Pleistocene. Inferences drawn from the morphology of the mandible BH-1 place it outside currently observed variation of European Homo heidelbergensis. The lack of derived Neandertal traits in BH-1 and its contemporary specimens in Southeast Europe, such as Kocabaş, Vasogliano and Ceprano, coupled with Middle Pleistocene synapomorphies, suggests different evolutionary forces acting in the east of the continent where isolation did not play such an important role during glaciations. PMID:23405085

Nuclear DNA sequences from the Middle Pleistocene Sima de los Huesos hominins.

PubMed

Meyer, Matthias; Arsuaga, Juan-Luis; de Filippo, Cesare; Nagel, Sarah; Aximu-Petri, Ayinuer; Nickel, Birgit; Martínez, Ignacio; Gracia, Ana; Bermúdez de Castro, José María; Carbonell, Eudald; Viola, Bence; Kelso, Janet; Prüfer, Kay; Pääbo, Svante

2016-03-24

A unique assemblage of 28 hominin individuals, found in Sima de los Huesos in the Sierra de Atapuerca in Spain, has recently been dated to approximately 430,000 years ago. An interesting question is how these Middle Pleistocene hominins were related to those who lived in the Late Pleistocene epoch, in particular to Neanderthals in western Eurasia and to Denisovans, a sister group of Neanderthals so far known only from southern Siberia. While the Sima de los Huesos hominins share some derived morphological features with Neanderthals, the mitochondrial genome retrieved from one individual from Sima de los Huesos is more closely related to the mitochondrial DNA of Denisovans than to that of Neanderthals. However, since the mitochondrial DNA does not reveal the full picture of relationships among populations, we have investigated DNA preservation in several individuals found at Sima de los Huesos. Here we recover nuclear DNA sequences from two specimens, which show that the Sima de los Huesos hominins were related to Neanderthals rather than to Denisovans, indicating that the population divergence between Neanderthals and Denisovans predates 430,000 years ago. A mitochondrial DNA recovered from one of the specimens shares the previously described relationship to Denisovan mitochondrial DNAs, suggesting, among other possibilities, that the mitochondrial DNA gene pool of Neanderthals turned over later in their history.

Geological and taphonomic context for the new hominin species Homo naledi from the Dinaledi Chamber, South Africa

PubMed Central

Dirks, Paul HGM; Berger, Lee R; Roberts, Eric M; Kramers, Jan D; Hawks, John; Randolph-Quinney, Patrick S; Elliott, Marina; Musiba, Charles M; Churchill, Steven E; de Ruiter, Darryl J; Schmid, Peter; Backwell, Lucinda R; Belyanin, Georgy A; Boshoff, Pedro; Hunter, K Lindsay; Feuerriegel, Elen M; Gurtov, Alia; Harrison, James du G; Hunter, Rick; Kruger, Ashley; Morris, Hannah; Makhubela, Tebogo V; Peixotto, Becca; Tucker, Steven

2015-01-01

We describe the physical context of the Dinaledi Chamber within the Rising Star cave, South Africa, which contains the fossils of Homo naledi. Approximately 1550 specimens of hominin remains have been recovered from at least 15 individuals, representing a small portion of the total fossil content. Macro-vertebrate fossils are exclusively H. naledi, and occur within clay-rich sediments derived from in situ weathering, and exogenous clay and silt, which entered the chamber through fractures that prevented passage of coarser-grained material. The chamber was always in the dark zone, and not accessible to non-hominins. Bone taphonomy indicates that hominin individuals reached the chamber complete, with disarticulation occurring during/after deposition. Hominins accumulated over time as older laminated mudstone units and sediment along the cave floor were eroded. Preliminary evidence is consistent with deliberate body disposal in a single location, by a hominin species other than Homo sapiens, at an as-yet unknown date. DOI: http://dx.doi.org/10.7554/eLife.09561.001 PMID:26354289

Plio-Pleistocene facies environments from the KBS Member, Koobi Fora Formation: implications for climate controls on the development of lake-margin hominin habitats in the northeast Turkana Basin (northwest Kenya).

PubMed

Lepre, Christopher J; Quinn, Rhonda L; Joordens, Josephine C A; Swisher, Carl C; Feibel, Craig S

2007-11-01

Climate change is hypothesized as a cause of major events of Plio-Pleistocene East African hominin evolution, but the vertically discontinuous and laterally confined nature of the relevant geological records has led to difficulties with assessing probable links between the two. High-resolution sedimentary sequences from lacustrine settings can provide comprehensive data of environmental changes and detailed correlations with well-established orbital and marine records of climate. Hominin-bearing deposits from Koobi Fora Ridge localities in the northeast Turkana Basin of Kenya are an archive of Plio-Pleistocene lake-margin sedimentation though significant developmental junctures of northern African climates, East African environments, and hominin evolution. This study examines alluvial channel and floodplain, nearshore lacustrine, and offshore lacustrine facies environments for the approximately 136-m-thick KBS Member (Koobi Fora Formation) exposed at the Koobi Fora Ridge. Aspects of the facies environments record information on the changing hydrosedimentary dynamics of the lake margin and give insights into potential climatic controls. Seasonal/yearly climate changes are represented by the varve-like laminations in offshore mudstones and the slickensides, dish-shaped fractures, and other paleosol features overprinted on floodplain strata. Vertical shifts between facies environments, however, are interpreted to indicate lake-level fluctuations deriving from longer-term, dry-wet periods in monsoonal rainfall. Recurrence periods for the inferred lake-level changes range from about 10,000 to 50,000 years, and several are consistent with the average estimated timescales of orbital precession ( approximately 20,000 years) and obliquity ( approximately 40,000 years). KBS Member facies environments from the Koobi Fora Ridge document the development of lake-margin hominin habitats in the northeast Turkana Basin. Environmental changes in these habitats may be a result of

A morphometric analysis of maxillary molar crowns of Middle-Late Pleistocene hominins.

PubMed

Bailey, Shara E

2004-09-01

This study explores the significance of shape differences in the maxillary first molar crowns of Neandertals and anatomically modern humans. It uses morphometric analysis to quantify these differences and to investigate how the orientation of major cusps, relative cusp base areas and occlusal polygon area influence crown shape. The aims of this study were to 1) quantify these data to test whether the tooth shapes of Neandertals and anatomically modern humans differ significantly and 2) to explore if either of the shapes is derived relative to earlier fossil hominins. Data were collected from digital occlusal photographs using image-processing software. Cusp angles, relative cusp base areas and occlusal polygon areas were measured on Neandertals (n=15), contemporary modern humans (n=62), Upper Paleolithic humans (n=6), early anatomically modern humans (n=3) and Homo erectus (n=3). Univariate and multivariate statistical tests were used to evaluate the differences between contemporary modern humans and Neandertals, while the much sparser data sets from the other fossil samples were included primarily for comparison. Statistically significant differences reflecting overall crown shape and internal placement of the crown apices were found. Neandertals are distinguished from contemporary humans by possessing maxillary first molars that 1) are markedly skewed; 2) possess a narrower distal segment of the occlusal polygon compared to the mesial segment; 3) possess a significantly smaller metacone and a significantly larger hypocone; and 4) possess a significantly smaller relative occlusal polygon area reflecting internally placed cusps. Differences in relative cusp base areas of the hypocone and metacone may contribute to the shape differences observed in Neandertals. However, early anatomically modern humans possessing a pattern of relative cusp base areas similar to Neandertals lack their unusual shape. That the morphology observed in non-Neandertal fossil hominins is

Energetic and nutritional constraints on infant brain development: implications for brain expansion during human evolution.

PubMed

Cunnane, Stephen C; Crawford, Michael A

2014-12-01

The human brain confronts two major challenges during its development: (i) meeting a very high energy requirement, and (ii) reliably accessing an adequate dietary source of specific brain selective nutrients needed for its structure and function. Implicitly, these energetic and nutritional constraints to normal brain development today would also have been constraints on human brain evolution. The energetic constraint was solved in large measure by the evolution in hominins of a unique and significant layer of body fat on the fetus starting during the third trimester of gestation. By providing fatty acids for ketone production that are needed as brain fuel, this fat layer supports the brain's high energy needs well into childhood. This fat layer also contains an important reserve of the brain selective omega-3 fatty acid, docosahexaenoic acid (DHA), not available in other primates. Foremost amongst the brain selective minerals are iodine and iron, with zinc, copper and selenium also being important. A shore-based diet, i.e., fish, molluscs, crustaceans, frogs, bird's eggs and aquatic plants, provides the richest known dietary sources of brain selective nutrients. Regular access to these foods by the early hominin lineage that evolved into humans would therefore have helped free the nutritional constraint on primate brain development and function. Inadequate dietary supply of brain selective nutrients still has a deleterious impact on human brain development on a global scale today, demonstrating the brain's ongoing vulnerability. The core of the shore-based paradigm of human brain evolution proposes that sustained access by certain groups of early Homo to freshwater and marine food resources would have helped surmount both the nutritional as well as the energetic constraints on mammalian brain development. Copyright © 2014 Elsevier Ltd. All rights reserved.

Dating Trinil: towards establishing an age framework for the hominin-bearing deposits at the Homo erectus site Trinil (Indonesia)

NASA Astrophysics Data System (ADS)

Joordens, Josephine; Adhityatama, Shinatria; Yurnaldi, Dida; Reimann, Tony; Rahayu Ekowati, Dian; Huffman, Frank; Barianto, Didit; Sutisna, Indra; Pop, Eduard; Alink, Gerrit; Kuiper, Klaudia; Priyatno, Hadi; Simanjuntak, Truman; Verpoorte, Alexander

2017-04-01

In the 1890s, the anatomist Eugène Dubois found the first fossils of our extinct relative Homo erectus at Trinil on Java (Indonesia). Since then, one of the major questions of humankind has been to find out "what made us human". H. erectus was morphologically in many ways like us, and the first hominin species to spread, from about 1.8 Ma onwards, over Africa, Eurasia and Southeast Asia. However, it is still unknown what behavioural and lifestyle characteristics allowed H. erectus to achieve this cosmopolitan distribution, and reach the island of Java at 1.5 Ma. Dating of Javanese hominin sites is notoriously difficult, yet crucial to resolve the climatic-environmental backdrop and biogeography of hominin species in the region. At present, there is still a lack of well-constrained ages for the important hominin-bearing Hauptknochenschicht (HK) at Trinil. Moreover, the fossiliferous layers above the HK have not been dated at all. Also, there is a paucity of climatic-environmental data on the HK and overlying layers. This hampers the reconstruction of a climatic-environmental framework with temporal correlations to hominin fossils from Trinil, and placement Trinil layers in the context of Asian hominin biogeography. Here, we report on our pilot fieldwork at Trinil in August 2016, as part of an ongoing collaborative project of the ARKENAS Jakarta (Indonesia) and the Faculty of Archaeology, Leiden University (The Netherlands). We have collected geochronological sediment samples from a number of carefully measured and described stratigraphic sections covering the HK and overlying layers, for the application of three dating methods (OSL, Ar/Ar, paleomagnetism). The aim is to provide a first reliable age model for the hominin-bearing and other fossiliferous layers at Trinil. We will present preliminary fieldwork results and discuss the implications for dispersal of fauna (including hominins).

Earliest evidence of modern human life history in North African early Homo sapiens.

PubMed

Smith, Tanya M; Tafforeau, Paul; Reid, Donald J; Grün, Rainer; Eggins, Stephen; Boutakiout, Mohamed; Hublin, Jean-Jacques

2007-04-10

Recent developmental studies demonstrate that early fossil hominins possessed shorter growth periods than living humans, implying disparate life histories. Analyses of incremental features in teeth provide an accurate means of assessing the age at death of developing dentitions, facilitating direct comparisons with fossil and modern humans. It is currently unknown when and where the prolonged modern human developmental condition originated. Here, an application of x-ray synchrotron microtomography reveals that an early Homo sapiens juvenile from Morocco dated at 160,000 years before present displays an equivalent degree of tooth development to modern European children at the same age. Crown formation times in the juvenile's macrodont dentition are higher than modern human mean values, whereas root development is accelerated relative to modern humans but is less than living apes and some fossil hominins. The juvenile from Jebel Irhoud is currently the oldest-known member of Homo with a developmental pattern (degree of eruption, developmental stage, and crown formation time) that is more similar to modern H. sapiens than to earlier members of Homo. This study also underscores the continuing importance of North Africa for understanding the origins of human anatomical and behavioral modernity. Corresponding biological and cultural changes may have appeared relatively late in the course of human evolution.

Early bioenergetic evolution

PubMed Central

Sousa, Filipa L.; Thiergart, Thorsten; Landan, Giddy; Nelson-Sathi, Shijulal; Pereira, Inês A. C.; Allen, John F.; Lane, Nick; Martin, William F.

2013-01-01

Life is the harnessing of chemical energy in such a way that the energy-harnessing device makes a copy of itself. This paper outlines an energetically feasible path from a particular inorganic setting for the origin of life to the first free-living cells. The sources of energy available to early organic synthesis, early evolving systems and early cells stand in the foreground, as do the possible mechanisms of their conversion into harnessable chemical energy for synthetic reactions. With regard to the possible temporal sequence of events, we focus on: (i) alkaline hydrothermal vents as the far-from-equilibrium setting, (ii) the Wood–Ljungdahl (acetyl-CoA) pathway as the route that could have underpinned carbon assimilation for these processes, (iii) biochemical divergence, within the naturally formed inorganic compartments at a hydrothermal mound, of geochemically confined replicating entities with a complexity below that of free-living prokaryotes, and (iv) acetogenesis and methanogenesis as the ancestral forms of carbon and energy metabolism in the first free-living ancestors of the eubacteria and archaebacteria, respectively. In terms of the main evolutionary transitions in early bioenergetic evolution, we focus on: (i) thioester-dependent substrate-level phosphorylations, (ii) harnessing of naturally existing proton gradients at the vent–ocean interface via the ATP synthase, (iii) harnessing of Na+ gradients generated by H+/Na+ antiporters, (iv) flavin-based bifurcation-dependent gradient generation, and finally (v) quinone-based (and Q-cycle-dependent) proton gradient generation. Of those five transitions, the first four are posited to have taken place at the vent. Ultimately, all of these bioenergetic processes depend, even today, upon CO2 reduction with low-potential ferredoxin (Fd), generated either chemosynthetically or photosynthetically, suggesting a reaction of the type ‘reduced iron → reduced carbon’ at the beginning of bioenergetic evolution

Out of Africa: modern human origins special feature: middle and later Pleistocene hominins in Africa and Southwest Asia.

PubMed

Rightmire, G Philip

2009-09-22

Approximately 700,000 years ago, Homo erectus in Africa was giving way to populations with larger brains accompanied by structural adjustments to the vault, cranial base, and face. Such early Middle Pleistocene hominins were not anatomically modern. Their skulls display strong supraorbital tori above projecting faces, flattened frontals, and less parietal expansion than is the case for Homo sapiens. Postcranial remains seem also to have archaic features. Subsequently, some groups evolved advanced skeletal morphology, and by ca. 200,000 years ago, individuals more similar to recent humans are present in the African record. These fossils are associated with Middle Stone Age lithic assemblages and, in some cases, Acheulean tools. Crania from Herto in Ethiopia carry defleshing cutmarks and superficial scoring that may be indicative of mortuary practices. Despite these signs of behavioral innovation, neither the Herto hominins, nor others from Late Pleistocene sites such as Klasies River in southern Africa and Skhūl/Qafzeh in Israel, can be matched in living populations. Skulls are quite robust, and it is only after approximately 35,000 years ago that people with more gracile, fully modern morphology make their appearance. Not surprisingly, many questions concerning this evolutionary history have been raised. Attention has centered on systematics of the mid-Pleistocene hominins, their paleobiology, and the timing of dispersals that spread H. sapiens out of Africa and across the Old World. In this report, I discuss structural changes characterizing the skulls from different time periods, possible regional differences in morphology, and the bearing of this evidence on recognizing distinct species.

Taphonomic interpretations of a new Plio-Pleistocene hominin-bearing assemblage at Kromdraai (Gauteng, South Africa)

NASA Astrophysics Data System (ADS)

Fourvel, Jean-Baptiste; Thackeray, John Francis; Brink, James S.; O'Regan, Hannah; Braga, José

2018-06-01

Within the past 80 years, the Kromdraai site in South Africa has provided a diverse Early Pleistocene fauna (notably bovids, carnivores, primates, large rodents, birds, proboscidea). Since 2014, the Kromdraai bone accumulation has been the focus of intensive fieldwork that demonstrated that the site is much larger than previously recognised. In the present taphonomic study of a new and large faunal sample including more than 2400 remains, stratigraphically controlled, we aim to test previous interpretations of the Kromdraai assemblage as representing a death trap or a carnivore lair. In particular, we aim to discuss the relationships between faunal communities in the context of carnivores, either predator-prey or predator-predator interactions. We investigate the relative abundance of anatomical elements and their fragmentation, the mortality profiles and tooth-mark frequency. We conclude that carnivores (particularly felids and hyenids) played a major role in the accumulation of fauna from Member 2, which (thus far) is the oldest depositional period investigated at Kromdraai. However, the high species diversity suggests that the secondary predators (scavengers) could have modified the bone deposit produced by the primary predators. The presence of hominin remains is also questioned. Our results shed new light on the palaeoecology of the Kromdraai Member 2 hominins, in terms of opportunistic predators and/or prey of large carnivores.

Taphonomic Analysis of the Faunal Assemblage Associated with the Hominins (Australopithecus sediba) from the Early Pleistocene Cave Deposits of Malapa, South Africa

PubMed Central

Val, Aurore; Dirks, Paul H. G. M.; Backwell, Lucinda R.; d’Errico, Francesco; Berger, Lee R.

2015-01-01

Here we present the results of a taphonomic study of the faunal assemblage associated with the hominin fossils (Australopithecus sediba) from the Malapa site. Results include estimation of body part representation, mortality profiles, type of fragmentation, identification of breakage patterns, and microscopic analysis of bone surfaces. The diversity of the faunal spectrum, presence of animals with climbing proclivities, abundance of complete and/or articulated specimens, occurrence of antimeric sets of elements, and lack of carnivore-modified bones, indicate that animals accumulated via a natural death trap leading to an area of the cave system with no access to mammalian scavengers. The co-occurrence of well preserved fossils, carnivore coprolites, deciduous teeth of brown hyaena, and some highly fragmented and poorly preserved remains supports the hypothesis of a mixing of sediments coming from distinct chambers, which collected at the bottom of the cave system through the action of periodic water flow. This combination of taphonomic features explains the remarkable state of preservation of the hominin fossils as well as some of the associated faunal material. PMID:26061082

The early stages of duplicate gene evolution

PubMed Central

Moore, Richard C.; Purugganan, Michael D.

2003-01-01

Gene duplications are one of the primary driving forces in the evolution of genomes and genetic systems. Gene duplicates account for 8–20% of the genes in eukaryotic genomes, and the rates of gene duplication are estimated at between 0.2% and 2% per gene per million years. Duplicate genes are believed to be a major mechanism for the establishment of new gene functions and the generation of evolutionary novelty, yet very little is known about the early stages of the evolution of duplicated gene pairs. It is unclear, for example, to what extent selection, rather than neutral genetic drift, drives the fixation and early evolution of duplicate loci. Analysis of recently duplicated genes in the Arabidopsis thaliana genome reveals significantly reduced species-wide levels of nucleotide polymorphisms in the progenitor and/or duplicate gene copies, suggesting that selective sweeps accompany the initial stages of the evolution of these duplicated gene pairs. Our results support recent theoretical work that indicates that fates of duplicate gene pairs may be determined in the initial phases of duplicate gene evolution and that positive selection plays a prominent role in the evolutionary dynamics of the very early histories of duplicate nuclear genes. PMID:14671323

Fossil skulls reveal that blood flow rate to the brain increased faster than brain volume during human evolution

NASA Astrophysics Data System (ADS)

Seymour, Roger S.; Bosiocic, Vanya; Snelling, Edward P.

2016-08-01

The evolution of human cognition has been inferred from anthropological discoveries and estimates of brain size from fossil skulls. A more direct measure of cognition would be cerebral metabolic rate, which is proportional to cerebral blood flow rate (perfusion). The hominin cerebrum is supplied almost exclusively by the internal carotid arteries. The sizes of the foramina that transmitted these vessels in life can be measured in hominin fossil skulls and used to calculate cerebral perfusion rate. Perfusion in 11 species of hominin ancestors, from Australopithecus to archaic Homo sapiens, increases disproportionately when scaled against brain volume (the allometric exponent is 1.41). The high exponent indicates an increase in the metabolic intensity of cerebral tissue in later Homo species, rather than remaining constant (1.0) as expected by a linear increase in neuron number, or decreasing according to Kleiber's Law (0.75). During 3 Myr of hominin evolution, cerebral tissue perfusion increased 1.7-fold, which, when multiplied by a 3.5-fold increase in brain size, indicates a 6.0-fold increase in total cerebral blood flow rate. This is probably associated with increased interneuron connectivity, synaptic activity and cognitive function, which all ultimately depend on cerebral metabolic rate.

Excavations at Schöningen and paradigm shifts in human evolution.

PubMed

Conard, Nicholas J; Serangeli, Jordi; Böhner, Utz; Starkovich, Britt M; Miller, Christopher E; Urban, Brigitte; Van Kolfschoten, Thijs

2015-12-01

The exceptional preservation at Schöningen together with a mixture of perseverance, hard work, and sheer luck led to the recovery of unique finds in an exceptional context. The 1995 discovery of numerous wooden artifacts, most notably at least 10 carefully made spears together with the skeletons of at least 20 to 25 butchered horses, brought the debate about hunting versus scavenging among late archaic hominins and analogous arguments about the purportedly primitive behavior of Homo heidelbergensis and Neanderthals to an end. Work under H. Thieme's lead from 1992 to 2008 and results from the current team since 2008 demonstrate that late H. heidelbergensis or early Neanderthals used sophisticated artifacts made from floral and faunal materials, in addition to lithic artifacts more typically recovered at Lower Paleolithic sites. The finds from the famous Horse Butchery Site and two dozen other archaeological horizons from the edges of the open-cast mine at Schöningen provide many new insights into the technology and behavioral patterns of hominins about 300 ka BP during MIS 9 on the Northern European Plain. An analysis of the finds from Schöningen and their contexts shows that the inhabitants of the site were skilled hunters at the top of the food chain and exhibited a high level of planning depth. These hominins had command of effective means of communication about the here and now, and the past and the future, that allowed them to repeatedly execute well-coordinated and successful group activities that likely culminated in a division of labor and social and economic patterns radically different from those of all non-human primates. The unique preservation and high quality excavations have led to a major paradigm shift or "Schöningen Effect" that changed our views of human evolution during the late Lower Paleolithic. In this respect, we can view the behaviors documented at Schöningen as a plausible baseline for the behavioral sophistication of archaic hominins

Early Pleistocene occurrence of Acheulian technology in North China

NASA Astrophysics Data System (ADS)

Li, Xingwen; Ao, Hong; Dekkers, Mark J.; Roberts, Andrew P.; Zhang, Peng; Lin, Shan; Huang, Weiwen; Hou, Yamei; Zhang, Weihua; An, Zhisheng

2017-01-01

Acheulian tools with their associated level of cognizance heralded a major threshold in the evolution of hominin technology, culture and behavior. Thus, unraveling occurrence ages of Acheulian technology across different regions worldwide constitutes a key aspect of understanding the archeology of early human evolution. Here we present a magneto-cyclochronology for the Acheulian assemblage from Sanmenxia Basin, Loess Plateau, North China. Our results place a sequence of stable normal and reversed paleomagnetic polarities within a regional lithostratigraphic context. The Acheulian assemblage is dated to be older than the Matuyama-Brunhes boundary at 0.78 Ma, and is found in strata that are probably equivalent to a weak paleosol subunit within loess layer L9 in the Chinese loess-paleosol sequence, which corresponds to marine isotope stage (MIS) 23, a relatively subdued interglacial period with age range of ∼0.89-0.92 Ma. This age of ∼0.9 Ma implies that Acheulian stone tools were unambiguously present in North China during the Early Pleistocene. It distinctly enlarges the geographic distribution of Acheulian technology and brings its occurrence in North China back into the Early Pleistocene, which is contemporaneous with its first emergence in Europe. Combined with other archeological records, the larger area over which Acheulian technology existed in East Asia during the terminal Early Pleistocene has important implications for understanding early human occupation of North China.

Re-appraisal of the stratigraphy and determination of new U-Pb dates for the Sterkfontein hominin site, South Africa.

PubMed

Pickering, Robyn; Kramers, Jan D

2010-07-01

Sterkfontein Caves is the single richest early hominin site in the world with deposits yielding one or more species of Australopithecus and possible early Homo, as well as an extensive faunal collection. The inability to date the southern African cave sites accurately or precisely has hindered attempts to integrate the hominin fossil evidence into pan-African scenarios about human evolutionary history, and especially hominin biogeography. We have used U-Pb and U-Th techniques to date sheets of calcium carbonate flowstone inter-bedded between the fossiliferous sediments. For the first time, absolute age ranges can be assigned to the fossil-bearing deposits: Member 2 is between 2.8 +/- 0.28 and 2.6 +/- 0.30 Ma and Member 4 between 2.65 +/- 0.30 and 2.01 +/- 0.05 Ma. The age of 2.01 +/- 0.05 Ma for the top of Member 4 constrains the last appearance of Australopithecus africanus to 2 Ma. In the Silberberg Grotto we have reproduced the U-Pb age of approximately 2.2 Ma of for the flowstones associated with StW573. We believe that these deposits, including the fossil and the flowstones, accumulated rapidly around 2.2 Ma. The stratigraphy of the site is complex as sediments are exposed both in the underground chambers and at surface. We present a new interpretation of the stratigraphy based on surface mapping, boreholes logs and U-Pb ages. Every effort was made to retain the Member system, however, only Members 2 and 4 are recognized in the boreholes. We propose that the deposits formally known as Member 3 are in fact the distal equivalents of Member 4. The sediments of Members 2 and 4 consisted of cone-like deposits and probably never filled up the cave. The U-Th ages show that there are substantial deposits younger than 400 ka in the underground cave, underlying the older deposits, highlighting again that these cave fills are not simple layer-cakes.

The medial pterygoid tubercle in the Atapuerca Early and Middle Pleistocene mandibles: evolutionary implications.

PubMed

Bermúdez de Castro, José-María; Quam, Rolf; Martinón-Torres, María; Martínez, Ignacio; Gracia-Téllez, Ana; Arsuaga, Juan Luís; Carbonell, Eudald

2015-01-01

Numerous studies have attempted to identify the presence of uniquely derived (autoapomorphic) Neandertal features. Here, we deal with the medial pterygoid tubercle (MTP), which is usually present on the internal face of the ascending ramus of Neandertal specimens. Our study stems from the identification of a hypertrophied tubercle in ATD6-96, an Early Pleistocene mandible recovered from the TD6 level of the Atapuerca-Gran Dolina site and attributed to Homo antecessor. Our review of the literature and study of numerous original fossil specimens and high quality replicas confirm that the MTP occurs at a high frequency in Neandertals (ca. 89%) and is also present in over half (ca. 55%) of the Middle Pleistocene Sima de los Huesos (SH) hominins. In contrast, it is generally absent or minimally developed in other extinct hominins, but can be found in variable frequencies (hominins and Neandertals. Since the TD6 hominins have been attributed either to MIS 21 or to MIS 25, it seems that a suite of assumed derived Neandertal features appeared in the Early Pleistocene, and they should be interpreted as synapomorphies shared among different taxa. We suggest that H. antecessor, the SH hominins and Neandertals shared a common ancestor in which these features appeared during the Early Pleistocene. The presence of the MTP in taxa other than H. neanderthalensis precludes this feature from being a Neandertal autapomorphy. © 2014 Wiley Periodicals, Inc.

Effect of ancient population structure on the degree of polymorphism shared between modern human populations and ancient hominins.

PubMed

Eriksson, Anders; Manica, Andrea

2012-08-28

Recent comparisons between anatomically modern humans and ancient genomes of other hominins have raised the tantalizing, and hotly debated, possibility of hybridization. Although several tests of hybridization have been devised, they all rely on the degree to which different modern populations share genetic polymorphisms with the ancient genomes of other hominins. However, spatial population structure is expected to generate genetic patterns similar to those that might be attributed to hybridization. To investigate this problem, we take Neanderthals as a case study, and build a spatially explicit model of the shared history of anatomically modern humans and this hominin. We show that the excess polymorphism shared between Eurasians and Neanderthals is compatible with scenarios in which no hybridization occurred, and is strongly linked to the strength of population structure in ancient populations. Thus, we recommend caution in inferring admixture from geographic patterns of shared polymorphisms, and argue that future attempts to investigate ancient hybridization between humans and other hominins should explicitly account for population structure.

Solar Radiation as Driving Force In Early Evolution

NASA Technical Reports Server (NTRS)

Rothschild, Lynn J.; Peterson, David L. (Technical Monitor)

2002-01-01

Ultraviolet radiation (UVR) has provided an evolutionary challenge to life on Earth in that it is both an agent of mutation and as well as a selective force. Today surface fluxes of UVR vary diurnally, seasonally, etc. Still, the UVR flux was probably substantially higher during the early phases of evolution, suggesting that its role in evolution was even more prominent during this time. In this presentation, the creative role of UVR in evolution is discussed, specifically in connection with the role that UVR may have played in the evolution of early microbial ecosystems. The presentation will include discussions of the direct influence of UVR on such processes as photosynthesis and genetic damage, as well as the indirect influence of UVR as mediated through the production of reactive oxygen species. These biological effects of UVR will be viewed against the backdrop of the physical nature of the early Earth, surely a very different place then than now.

Early Homo and the role of the genus in paleoanthropology.

PubMed

Villmoare, Brian

2018-01-01

The history of the discovery of early fossils attributed to the genus Homo has been contentious, with scholars disagreeing over the generic assignment of fossils proposed as members of our genus. In this manuscript I review the history of discovery and debate over early Homo and evaluate the various taxonomic hypotheses for the genus. To get a sense of how hominin taxonomy compares to taxonomic practice outside paleoanthropology, I compare the diversity of Homo to genera in other vertebrate clades. Finally, I propose a taxonomic model that hews closely to current models for hominin phylogeny and is consistent with taxonomic practice across evolutionary biology. © 2018 American Association of Physical Anthropologists.

Messinian age and savannah environment of the possible hominin Graecopithecus from Europe.

PubMed

Böhme, Madelaine; Spassov, Nikolai; Ebner, Martin; Geraads, Denis; Hristova, Latinka; Kirscher, Uwe; Kötter, Sabine; Linnemann, Ulf; Prieto, Jérôme; Roussiakis, Socrates; Theodorou, George; Uhlig, Gregor; Winklhofer, Michael

2017-01-01

Dating fossil hominids and reconstructing their environments is critically important for understanding human evolution. Here we date the potentially oldest hominin, Graecopithecus freybergi from Europe and constrain the environmental conditions under which it thrived. For the Graecopithecus-bearing Pikermi Formation of Attica/Greece, a saline aeolian dust deposit of North African (Sahara) provenance, we obtain an age of 7.37-7.11 Ma, which is coeval with a dramatic cooling in the Mediterranean region at the Tortonian-Messinian transition. Palaeobotanic proxies demonstrate C4-grass dominated wooded grassland-to-woodland habitats of a savannah biome for the Pikermi Formation. Faunal turnover at the Tortonian-Messinian transition led to the spread of new mammalian taxa along with Graecopithecus into Europe. The type mandible of G. freybergi from Pyrgos (7.175 Ma) and the single tooth (7.24 Ma) from Azmaka (Bulgaria) represent the first hominids of Messinian age from continental Europe. Our results suggest that major splits in the hominid family occurred outside Africa.

Messinian age and savannah environment of the possible hominin Graecopithecus from Europe

PubMed Central

Spassov, Nikolai; Ebner, Martin; Geraads, Denis; Hristova, Latinka; Kirscher, Uwe; Kötter, Sabine; Linnemann, Ulf; Prieto, Jérôme; Roussiakis, Socrates; Theodorou, George; Uhlig, Gregor; Winklhofer, Michael

2017-01-01

Dating fossil hominids and reconstructing their environments is critically important for understanding human evolution. Here we date the potentially oldest hominin, Graecopithecus freybergi from Europe and constrain the environmental conditions under which it thrived. For the Graecopithecus-bearing Pikermi Formation of Attica/Greece, a saline aeolian dust deposit of North African (Sahara) provenance, we obtain an age of 7.37–7.11 Ma, which is coeval with a dramatic cooling in the Mediterranean region at the Tortonian-Messinian transition. Palaeobotanic proxies demonstrate C4-grass dominated wooded grassland-to-woodland habitats of a savannah biome for the Pikermi Formation. Faunal turnover at the Tortonian-Messinian transition led to the spread of new mammalian taxa along with Graecopithecus into Europe. The type mandible of G. freybergi from Pyrgos (7.175 Ma) and the single tooth (7.24 Ma) from Azmaka (Bulgaria) represent the first hominids of Messinian age from continental Europe. Our results suggest that major splits in the hominid family occurred outside Africa. PMID:28531204

Palaeoproteomic evidence identifies archaic hominins associated with the Châtelperronian at the Grotte du Renne

PubMed Central

Welker, Frido; Hajdinjak, Mateja; Talamo, Sahra; Jaouen, Klervia; Dannemann, Michael; David, Francine; Julien, Michèle; Meyer, Matthias; Barnes, Ian; Brace, Selina; Kamminga, Pepijn; Fischer, Roman; Kessler, Benedikt M.; Stewart, John R.; Pääbo, Svante; Collins, Matthew J.; Hublin, Jean-Jacques

2016-01-01

In Western Europe, the Middle to Upper Paleolithic transition is associated with the disappearance of Neandertals and the spread of anatomically modern humans (AMHs). Current chronological, behavioral, and biological models of this transitional period hinge on the Châtelperronian technocomplex. At the site of the Grotte du Renne, Arcy-sur-Cure, morphological Neandertal specimens are not directly dated but are contextually associated with the Châtelperronian, which contains bone points and beads. The association between Neandertals and this “transitional” assemblage has been controversial because of the lack either of a direct hominin radiocarbon date or of molecular confirmation of the Neandertal affiliation. Here we provide further evidence for a Neandertal–Châtelperronian association at the Grotte du Renne through biomolecular and chronological analysis. We identified 28 additional hominin specimens through zooarchaeology by mass spectrometry (ZooMS) screening of morphologically uninformative bone specimens from Châtelperronian layers at the Grotte du Renne. Next, we obtain an ancient hominin bone proteome through liquid chromatography-MS/MS analysis and error-tolerant amino acid sequence analysis. Analysis of this palaeoproteome allows us to provide phylogenetic and physiological information on these ancient hominin specimens. We distinguish Late Pleistocene clades within the genus Homo based on ancient protein evidence through the identification of an archaic-derived amino acid sequence for the collagen type X, alpha-1 (COL10α1) protein. We support this by obtaining ancient mtDNA sequences, which indicate a Neandertal ancestry for these specimens. Direct accelerator mass spectometry radiocarbon dating and Bayesian modeling confirm that the hominin specimens date to the Châtelperronian at the Grotte du Renne. PMID:27638212

Palaeoproteomic evidence identifies archaic hominins associated with the Châtelperronian at the Grotte du Renne.

PubMed

Welker, Frido; Hajdinjak, Mateja; Talamo, Sahra; Jaouen, Klervia; Dannemann, Michael; David, Francine; Julien, Michèle; Meyer, Matthias; Kelso, Janet; Barnes, Ian; Brace, Selina; Kamminga, Pepijn; Fischer, Roman; Kessler, Benedikt M; Stewart, John R; Pääbo, Svante; Collins, Matthew J; Hublin, Jean-Jacques

2016-10-04

In Western Europe, the Middle to Upper Paleolithic transition is associated with the disappearance of Neandertals and the spread of anatomically modern humans (AMHs). Current chronological, behavioral, and biological models of this transitional period hinge on the Châtelperronian technocomplex. At the site of the Grotte du Renne, Arcy-sur-Cure, morphological Neandertal specimens are not directly dated but are contextually associated with the Châtelperronian, which contains bone points and beads. The association between Neandertals and this "transitional" assemblage has been controversial because of the lack either of a direct hominin radiocarbon date or of molecular confirmation of the Neandertal affiliation. Here we provide further evidence for a Neandertal-Châtelperronian association at the Grotte du Renne through biomolecular and chronological analysis. We identified 28 additional hominin specimens through zooarchaeology by mass spectrometry (ZooMS) screening of morphologically uninformative bone specimens from Châtelperronian layers at the Grotte du Renne. Next, we obtain an ancient hominin bone proteome through liquid chromatography-MS/MS analysis and error-tolerant amino acid sequence analysis. Analysis of this palaeoproteome allows us to provide phylogenetic and physiological information on these ancient hominin specimens. We distinguish Late Pleistocene clades within the genus Homo based on ancient protein evidence through the identification of an archaic-derived amino acid sequence for the collagen type X, alpha-1 (COL10α1) protein. We support this by obtaining ancient mtDNA sequences, which indicate a Neandertal ancestry for these specimens. Direct accelerator mass spectometry radiocarbon dating and Bayesian modeling confirm that the hominin specimens date to the Châtelperronian at the Grotte du Renne.

Demonstration and Pantomime in the Evolution of Teaching.

PubMed

Gärdenfors, Peter

2017-01-01

Donald proposes that early Homo evolved mimesis as a new form of cognition. This article investigates the mimesis hypothesis in relation to the evolution of teaching. The fundamental capacities that distinguish hominin teaching from that of other animals are demonstration and pantomime. A conceptual analysis of the instructional and communicative functions of demonstration and pantomime is presented. Archaeological evidence that demonstration was used for transmitting the Oldowan technology is summarized. It is argued that pantomime develops out of demonstration so that the primary objective of pantomime is that the onlooker learns the motoric patterns shown in the pantomime. The communicative use of pantomime is judged to be secondary. This use of pantomime is also contrasted with other forms of gestures. A key feature of the analysis is that the meaning of a pantomime is characterized by the force patterns of the movements. These force patterns form the core of a model of the cognitive mechanism behind pantomime. Finally, the role of pantomime in the evolution of language is also discussed.

Demonstration and Pantomime in the Evolution of Teaching

PubMed Central

Gärdenfors, Peter

2017-01-01

Donald proposes that early Homo evolved mimesis as a new form of cognition. This article investigates the mimesis hypothesis in relation to the evolution of teaching. The fundamental capacities that distinguish hominin teaching from that of other animals are demonstration and pantomime. A conceptual analysis of the instructional and communicative functions of demonstration and pantomime is presented. Archaeological evidence that demonstration was used for transmitting the Oldowan technology is summarized. It is argued that pantomime develops out of demonstration so that the primary objective of pantomime is that the onlooker learns the motoric patterns shown in the pantomime. The communicative use of pantomime is judged to be secondary. This use of pantomime is also contrasted with other forms of gestures. A key feature of the analysis is that the meaning of a pantomime is characterized by the force patterns of the movements. These force patterns form the core of a model of the cognitive mechanism behind pantomime. Finally, the role of pantomime in the evolution of language is also discussed. PMID:28382011

The manual pressures of stone tool behaviors and their implications for the evolution of the human hand.

PubMed

Williams-Hatala, Erin Marie; Hatala, Kevin G; Gordon, McKenzie; Key, Alastair; Kasper, Margaret; Kivell, Tracy L

2018-06-01

It is widely agreed that biomechanical stresses imposed by stone tool behaviors influenced the evolution of the human hand. Though archaeological evidence suggests that early hominins participated in a variety of tool behaviors, it is unlikely that all behaviors equally influenced modern human hand anatomy. It is more probable that a behavior's likelihood of exerting a selective pressure was a weighted function of the magnitude of stresses associated with that behavior, the benefits received from it, and the amount of time spent performing it. Based on this premise, we focused on the first part of that equation and evaluated magnitudes of stresses associated with stone tool behaviors thought to have been commonly practiced by early hominins, to determine which placed the greatest loads on the digits. Manual pressure data were gathered from 39 human subjects using a Novel Pliance ® manual pressure system while they participated in multiple Plio-Pleistocene tool behaviors: nut-cracking, marrow acquisition with a hammerstone, flake production with a hammerstone, and handaxe and flake use. Manual pressure distributions varied significantly according to behavior, though there was a tendency for regions of the hand subject to the lowest pressures (e.g., proximal phalanges) to be affected less by behavior type. Hammerstone use during marrow acquisition and flake production consistently placed the greatest loads on the digits collectively, on each digit and on each phalanx. Our results suggest that, based solely on the magnitudes of stresses, hammerstone use during marrow acquisition and flake production are the most likely of the assessed behaviors to have influenced the anatomical and functional evolution of the human hand. Copyright © 2018 Elsevier Ltd. All rights reserved.

Early evolution of transversally thermalized partons

NASA Astrophysics Data System (ADS)

Bialas, Andrzej; Chojnacki, Mikolaj; Florkowski, Wojciech

2008-03-01

The idea that the parton system created in relativistic heavy-ion collisions (i) emerges in a state with transverse momenta close to thermodynamic equilibrium and (ii) its evolution at early times is dominated by the 2-dimensional (transverse) hydrodynamics of the ideal fluid is investigated. It is argued that this mechanism may help to solve the problem of early equilibration.

Speech, stone tool-making and the evolution of language.

PubMed

Cataldo, Dana Michelle; Migliano, Andrea Bamberg; Vinicius, Lucio

2018-01-01

The 'technological hypothesis' proposes that gestural language evolved in early hominins to enable the cultural transmission of stone tool-making skills, with speech appearing later in response to the complex lithic industries of more recent hominins. However, no flintknapping study has assessed the efficiency of speech alone (unassisted by gesture) as a tool-making transmission aid. Here we show that subjects instructed by speech alone underperform in stone tool-making experiments in comparison to subjects instructed through either gesture alone or 'full language' (gesture plus speech), and also report lower satisfaction with their received instruction. The results provide evidence that gesture was likely to be selected over speech as a teaching aid in the earliest hominin tool-makers; that speech could not have replaced gesturing as a tool-making teaching aid in later hominins, possibly explaining the functional retention of gesturing in the full language of modern humans; and that speech may have evolved for reasons unrelated to tool-making. We conclude that speech is unlikely to have evolved as tool-making teaching aid superior to gesture, as claimed by the technological hypothesis, and therefore alternative views should be considered. For example, gestural language may have evolved to enable tool-making in earlier hominins, while speech may have later emerged as a response to increased trade and more complex inter- and intra-group interactions in Middle Pleistocene ancestors of Neanderthals and Homo sapiens; or gesture and speech may have evolved in parallel rather than in sequence.

The effectiveness of using carbonate isotope measurements of body tissues to infer diet in human evolution: Evidence from wild western chimpanzees (Pan troglodytes verus).

PubMed

Fahy, Geraldine E; Boesch, Christophe; Hublin, Jean-Jacques; Richards, Michael P

2015-11-01

Changes in diet throughout hominin evolution have been linked with important evolutionary changes. Stable carbon isotope analysis of inorganic apatite carbonate is the main isotopic method used to reconstruct fossil hominin diets; to test its effectiveness as a paleodietary indicator we present bone and enamel carbonate carbon isotope data from a well-studied population of modern wild western chimpanzees (Pan troglodytes verus) of known sex and age from Taï, Cote d'Ivoire. We found a significant effect of age class on bone carbonate values, with adult chimpanzees being more (13)C- and (18)O-depleted compared to juveniles. Further, to investigate habitat effects, we compared our data to existing apatite data on eastern chimpanzees (P. troglodytes schweinfurthii) and found that the Taï chimpanzees are significantly more depleted in enamel δ(13)Cap and δ(18)Oap compared to their eastern counterparts. Our data are the first to present a range of tissue-specific isotope data from the same group of wild western chimpanzees and, as such, add new data to the growing number of modern non-human primate comparative isotope datasets providing valuable information for the interpretation of diet throughout hominin evolution. By comparing our data to published isotope data on fossil hominins we found that our modern chimpanzee bone and enamel data support hypotheses that the trend towards increased consumption of C4 foods after 4 Ma (millions of years ago) is unique to hominins. Copyright © 2015 Elsevier Ltd. All rights reserved.

Unraveling hominin behavior at another anthropogenic site from Olduvai Gorge (Tanzania): new archaeological and taphonomic research at BK, Upper Bed II.

PubMed

Domínguez-Rodrigo, M; Mabulla, A; Bunn, H T; Barba, R; Diez-Martín, F; Egeland, C P; Espílez, E; Egeland, A; Yravedra, J; Sánchez, P

2009-09-01

New archaeological excavations and research at BK, Upper Bed II (Olduvai Gorge, Tanzania) have yielded a rich and unbiased collection of fossil bones. These new excavations show that BK is a stratified deposit formed in a riverine setting close to an alluvial plain. The present taphonomic study reveals the second-largest collection of hominin-modified bones from Olduvai, with abundant cut marks found on most of the anatomical areas preserved. Meat and marrow exploitation is reconstructed using the taphonomic signatures left on the bones by hominins. Highly cut-marked long limb shafts, especially those of upper limb bones, suggest that hominins at BK were actively engaged in acquiring small and middle-sized animals using strategies other than passive scavenging. The exploitation of large-sized game (Pelorovis) by Lower Pleistocene hominins, as suggested by previous researchers, is supported by the present study.

Reading the landscape: Legible environments and hominin dispersals.

PubMed

Guiducci, Dario; Burke, Ariane

2016-05-06

Wayfinding, or the ability to plan and navigate a course over the landscape, is a subject of investigation in geography, neurophysiology, psychology, urban planning, and landscape design. With the prevalence of GPS-assisted navigation systems, or "wayfinders," computer scientists are also increasingly interested in understanding how people plan their movements and guide others. However, the importance of wayfinding as a process that regulates human mobility has only recently been incorporated into archeological research design. Hominin groups were able to disperse widely during the course of prehistory. The scope of these dispersals speaks to the innate navigation abilities of hominins. Their long-term success must have depended on an ability to communicate spatial information effectively. Here, we consider the extent to which some landscapes may have been more conducive to wayfinding than others. We also describe a tool we have created for quantifying landscape legibility (sensu Gollege), a complex and under-explored concept in archeology, with a view to investigating the impact of landscape structure on human wayfinding and thus, patterns of dispersal during prehistory. To this end, we have developed a method for quantifying legibility using a Geographic Information System (GIS) and apply it to a test case in prehistoric Iberia. © 2016 Wiley Periodicals, Inc.

The environment of the Ethiopian highlands at the Mid Pleistocene Transition: Fauna, flora and hominins in the 850-700 ka sequence of Gombore II (Melka Kunture)

NASA Astrophysics Data System (ADS)

Mussi, M.; Altamura, F.; Bonnefille, R.; De Rita, D.; Melis, R. T.

2016-10-01

Environment, climatic change and human evolution have been debated over the last 50 years giving special attention to the Plio-Pleistocene sites of the Rift Valley. In this paper we discuss the environment and the limits of hominin adaptability based on evidence from Melka Kunture, at 2000 m asl on the Ethiopian highlands, and specifically on the ∼850 ka to ∼700 ka sequence at sub-site Gombore II. Human fossils and multiple Acheulean occurrences, as well as hippo remains and footprints, combined with palynological analysis, provide a highly detailed chronological resolution of the changing local environmental conditions during the last ∼150 ka of the MPT (Mid Pleistocene Transition), including the sequence of events after a volcanic eruption. Layers containing footprints and fossils are evidence of near-continuous occupation by hippos and their recolonization of the area after a disruptive volcanic eruption. Conversely, Acheulean implements and human fossils suggest that peopling by hominins occurred at a different and discontinuous pace even when the flora and fauna were re-established and the environment was rather stable. Most notably, the assembled evidence points to the limits of Homo erectus s.l. adaptability. Apparently, this hominin could no longer live at 2000 m asl when the climate deteriorated during glacial isotopic stage 20, becoming markedly colder than it is today, but re-colonized the area when the climate turned warmer again during isotopic stage 19.

Tree climbing and human evolution

PubMed Central

Venkataraman, Vivek V.; Kraft, Thomas S.; Dominy, Nathaniel J.

2013-01-01

Paleoanthropologists have long argued—often contentiously—about the climbing abilities of early hominins and whether a foot adapted to terrestrial bipedalism constrained regular access to trees. However, some modern humans climb tall trees routinely in pursuit of honey, fruit, and game, often without the aid of tools or support systems. Mortality and morbidity associated with facultative arboreality is expected to favor behaviors and anatomies that facilitate safe and efficient climbing. Here we show that Twa hunter–gatherers use extraordinary ankle dorsiflexion (>45°) during climbing, similar to the degree observed in wild chimpanzees. Although we did not detect a skeletal signature of dorsiflexion in museum specimens of climbing hunter–gatherers from the Ituri forest, we did find that climbing by the Twa is associated with longer fibers in the gastrocnemius muscle relative to those of neighboring, nonclimbing agriculturalists. This result suggests that a more excursive calf muscle facilitates climbing with a bipedally adapted ankle and foot by positioning the climber closer to the tree, and it might be among the mechanisms that allow hunter–gatherers to access the canopy safely. Given that we did not find a skeletal correlate for this observed behavior, our results imply that derived aspects of the hominin ankle associated with bipedalism remain compatible with vertical climbing and arboreal resource acquisition. Our findings challenge the persistent arboreal–terrestrial dichotomy that has informed behavioral reconstructions of fossil hominins and highlight the value of using modern humans as models for inferring the limits of hominin arboreality. PMID:23277565

The evolution of the human pelvis: changing adaptations to bipedalism, obstetrics and thermoregulation

PubMed Central

Gruss, Laura Tobias; Schmitt, Daniel

2015-01-01

The fossil record of the human pelvis reveals the selective priorities acting on hominin anatomy at different points in our evolutionary history, during which mechanical requirements for locomotion, childbirth and thermoregulation often conflicted. In our earliest upright ancestors, fundamental alterations of the pelvis compared with non-human primates facilitated bipedal walking. Further changes early in hominin evolution produced a platypelloid birth canal in a pelvis that was wide overall, with flaring ilia. This pelvic form was maintained over 3–4 Myr with only moderate changes in response to greater habitat diversity, changes in locomotor behaviour and increases in brain size. It was not until Homo sapiens evolved in Africa and the Middle East 200 000 years ago that the narrow anatomically modern pelvis with a more circular birth canal emerged. This major change appears to reflect selective pressures for further increases in neonatal brain size and for a narrow body shape associated with heat dissipation in warm environments. The advent of the modern birth canal, the shape and alignment of which require fetal rotation during birth, allowed the earliest members of our species to deal obstetrically with increases in encephalization while maintaining a narrow body to meet thermoregulatory demands and enhance locomotor performance. PMID:25602067

The Path of Human Evolution

NASA Astrophysics Data System (ADS)

Feibel, C. S.

2004-12-01

A complex series of evolutionary steps, contingent upon a dynamic environmental context and a long biological heritage, have led to the ascent of Homo sapiens as a dominant component of the modern biosphere. In a field where missing links still abound and new discoveries regularly overturn theoretical paradigms, our understanding of the path of human evolution has made tremendous advances in recent years. Two major trends characterize the development of the hominin clade subsequent to its origins with the advent of upright bipedalism in the Late Miocene of Africa. One is a diversification into two prominent morphological branches, each with a series of 'twigs' representing evolutionary experimentation at the species or subspecies level. The second important trend, which in its earliest manifestations cannot clearly be ascribed to one or the other branch, is the behavioral complexity of an increasing reliance on technology to expand upon limited inherent morphological specializations and to buffer the organism from its environment. This technological dependence is directly associated with the expansion of hominin range outside Africa by the genus Homo, and is accelerated in the sole extant form Homo sapiens through the last 100 Ka. There are interesting correlates between the evolutionary and behavioral patterns seen in the hominin clade and environmental dynamics of the Neogene. In particular, the tempo of morphological and behavioral innovation may be tracking major events in Neogene climatic development as well as reflecting intervals of variability or stability. Major improvements in analytical techniques, coupled with important new collections and a growing body of contextual data are now making possible the integration of global, regional and local environmental archives with an improved biological understanding of the hominin clade to address questions of coincidence and causality.

Possible paleohydrologic and paleoclimatic effects on hominin migration and occupation of the Levantine Middle Paleolithic.

PubMed

Frumkin, Amos; Bar-Yosef, Ofer; Schwarcz, Henry P

2011-04-01

This paper explores the impact of major glacial/interglacial paleohydrologic variations in the Middle-Paleolithic Levant on hominin migration and occupation. The climatic reconstruction is based primarily on the most straight-forward paleohydrologic records recently published. These terrestrial proxies convey direct paleoenvironmental signals of effective precipitation and aquifer recharge. The two main proxies are temporal changes of terminal lake levels in the Dead Sea basin and periods of deposition or non-deposition of speleothems. Other records, such as stable isotopes, if interpreted correctly, correspond well with these two direct proxies. All the records consistently indicate that the last two glacial periods in the central Levant were generally wet and cool, while the last two interglacials were dry and warm, so more water was available for the ecosystem and thus hominins during glacial periods than during interglacials. Some proxies indicate that the higher precipitation/evaporation ratio during glacial periods involved higher precipitation rather than only reduced evaporation. Beyond the general mean glacial/interglacial climate suggested here, variations occurred at all temporal scales throughout glacial or interglacial periods. In the Sahara-Negev arid barrier, moister conditions occurred during Marine Isotope Stage (MIS) 6a-5e, when Anatomically Modern Humans apparently migrated out of Africa. We suggest that this migration, as well as the later Neanderthal expansion from Southeast Europe or the Anatolian plateau into the Levant during early MIS 4, could be facilitated by the observed major climatic variations. Copyright © 2010 Elsevier Ltd. All rights reserved.

Evidence for chronic omega-3 fatty acids and ascorbic acid deficiency in Palaeolithic hominins in Europe at the emergence of cannibalism

NASA Astrophysics Data System (ADS)

Guil-Guerrero, J. L.

2017-02-01

At the Middle-Upper Palaeolithic (M/UP) transition in Western Europe, hominins depended mostly on terrestrial mammals for subsistence, being pointed out that reliance on reindeer (Rangifer tarandus) would have promoted declines in human population densities during that period. Food-composition tables have been compiled for hominins at the M/UP transition, listing protein, fat, energy, different omega-3 fatty acids and ascorbic acid concentrations. These data were used to compute the regular relations between fatty and lean tissues of the main hunted food-animals to meet hominin energy needs. Then, with daily protein intake considered critical, the optimal contribution of the different omega-3 fatty acids from different hunted species to hominin diets were computed. Several faunal assemblages from different human sites at different M/UP periods were used to assess the overall daily intake of the various omega-3 fatty acid classes. The results of the calculations made in this work are quite clear; hominins at the M/UP transition had a deficit of both omega-3 fatty acids and ascorbic acid. Data on human organs summarized here are also conclusive: these contain such nutrients in amounts much higher than reached in the corresponding mammal organs consumed, and thus could have been alternative sources of those nutrients for Palaeolithic hominins. Therefore, nutritional cannibalism detected at such times could have had the function of alleviating these deficits. The evolutionary advantages gained by the consumption of the various omega-3 fatty acids of human origin are also discussed.

The evolution of vertebral formulae in Hominoidea.

PubMed

Thompson, Nathan E; Almécija, Sergio

2017-09-01

Primate vertebral formulae have long been investigated because of their link to locomotor behavior and overall body plan. Knowledge of the ancestral vertebral formulae in the hominoid tree of life is necessary to interpret the pattern of evolution among apes, and to critically evaluate the morphological adaptations involved in the transition to hominin bipedalism. Though many evolutionary hypotheses have been proposed based on living and fossil species, the application of quantitative phylogenetic methods for thoroughly reconstructing ancestral vertebral formulae and formally testing patterns of vertebral evolution is lacking. To estimate the most probable scenarios of hominoid vertebral evolution, we utilized an iterative ancestral state reconstruction approach to determine likely ancestral vertebral counts in apes, humans, and other anthropoid out-groups. All available ape and hominin fossil taxa with an inferred regional vertebral count were included in the analysis. Sensitivity iterations were performed both by changing the phylogenetic position of fossil taxa with a contentious placement, and by changing the inferred number of vertebrae in taxa with uncertain morphology. Our ancestral state reconstruction results generally support a short-backed hypothesis of human evolution, with a Pan-Homo last common ancestor possessing a vertebral formulae of 7:13:4:6 (cervical:thoracic:lumbar:sacral). Our results indicate that an initial reduction in lumbar vertebral count and increase in sacral count is a synapomorphy of crown hominoids (supporting an intermediate-backed hypothesis for the origins of the great ape-human clade). Further reduction in lumbar count occurs independently in orangutans and African apes. Our results highlight the complexity and homoplastic nature of vertebral count evolution, and give little support to the long-backed hypothesis of human evolution. Copyright © 2017 Elsevier Ltd. All rights reserved.

Selection to outsmart the germs: The evolution of disease recognition and social cognition.

PubMed

Kessler, Sharon E; Bonnell, Tyler R; Byrne, Richard W; Chapman, Colin A

2017-07-01

The emergence of providing care to diseased conspecifics must have been a turning point during the evolution of hominin sociality. On a population level, care may have minimized the costs of socially transmitted diseases at a time of increasing social complexity, although individual care-givers probably incurred increased transmission risks. We propose that care-giving likely originated within kin networks, where the costs may have been balanced by fitness increases obtained through caring for ill kin. We test a novel hypothesis of hominin cognitive evolution in which disease may have selected for the cognitive ability to recognize when a conspecific is infected. Because diseases may produce symptoms that are likely detectable via the perceptual-cognitive pathways integral to social cognition, we suggest that disease recognition and social cognition may have evolved together. Using agent-based modeling, we test 1) under what conditions disease can select for increasing disease recognition and care-giving among kin, 2) whether providing care produces greater selection for cognition than an avoidance strategy, and 3) whether care-giving alters the progression of the disease through the population. The greatest selection was produced by diseases with lower risks to the care-giver and prevalences low enough not to disrupt the kin networks. When care-giving and avoidance strategies were compared, only care-giving reduced the severity of the disease outbreaks and subsequent population crashes. The greatest selection for increased cognitive abilities occurred early in the model runs when the outbreaks and population crashes were most severe. Therefore, over the course of human evolution, repeated introductions of novel diseases into naïve populations could have produced sustained selection for increased disease recognition and care-giving behavior, leading to the evolution of increased cognition, social complexity, and, eventually, medical care in humans. Finally, we lay

Origin and early evolution of photosynthesis

NASA Technical Reports Server (NTRS)

Blankenship, R. E.

1992-01-01

Photosynthesis was well-established on the earth at least 3.5 thousand million years ago, and it is widely believed that these ancient organisms had similar metabolic capabilities to modern cyanobacteria. This requires that development of two photosystems and the oxygen evolution capability occurred very early in the earth's history, and that a presumed phase of evolution involving non-oxygen evolving photosynthetic organisms took place even earlier. The evolutionary relationships of the reaction center complexes found in all the classes of currently existing organisms have been analyzed using sequence analysis and biophysical measurements. The results indicate that all reaction centers fall into two basic groups, those with pheophytin and a pair of quinones as early acceptors, and those with iron sulfur clusters as early acceptors. No simple linear branching evolutionary scheme can account for the distribution patterns of reaction centers in existing photosynthetic organisms, and lateral transfer of genetic information is considered as a likely possibility. Possible scenarios for the development of primitive reaction centers into the heterodimeric protein structures found in existing reaction centers and for the development of organisms with two linked photosystems are presented.

The evolution of early vertebrate photoreceptors.

PubMed

Collin, Shaun P; Davies, Wayne L; Hart, Nathan S; Hunt, David M

2009-10-12

Meeting the challenge of sampling an ancient aquatic landscape by the early vertebrates was crucial to their survival and would establish a retinal bauplan to be used by all subsequent vertebrate descendents. Image-forming eyes were under tremendous selection pressure and the ability to identify suitable prey and detect potential predators was thought to be one of the major drivers of speciation in the Early Cambrian. Based on the fossil record, we know that hagfishes, lampreys, holocephalans, elasmobranchs and lungfishes occupy critical stages in vertebrate evolution, having remained relatively unchanged over hundreds of millions of years. Now using extant representatives of these 'living fossils', we are able to piece together the evolution of vertebrate photoreception. While photoreception in hagfishes appears to be based on light detection and controlling circadian rhythms, rather than image formation, the photoreceptors of lampreys fall into five distinct classes and represent a critical stage in the dichotomy of rods and cones. At least four types of retinal cones sample the visual environment in lampreys mediating photopic (and potentially colour) vision, a sampling strategy retained by lungfishes, some modern teleosts, reptiles and birds. Trichromacy is retained in cartilaginous fishes (at least in batoids and holocephalans), where it is predicted that true scotopic (dim light) vision evolved in the common ancestor of all living gnathostomes. The capacity to discriminate colour and balance the tradeoff between resolution and sensitivity in the early vertebrates was an important driver of eye evolution, where many of the ocular features evolved were retained as vertebrates progressed on to land.

The early thermal evolution of Mars

NASA Astrophysics Data System (ADS)

Bhatia, G. K.; Sahijpal, S.

2016-01-01

Hf-W isotopic systematics of Martian meteorites have provided evidence for the early accretion and rapid core formation of Mars. We present the results of numerical simulations performed to study the early thermal evolution and planetary scale differentiation of Mars. The simulations are confined to the initial 50 Myr (Ma) of the formation of solar system. The accretion energy produced during the growth of Mars and the decay energy due to the short-lived radio-nuclides 26Al, 60Fe, and the long-lived nuclides, 40K, 235U, 238U, and 232Th are incorporated as the heat sources for the thermal evolution of Mars. During the core-mantle differentiation of Mars, the molten metallic blobs were numerically moved using Stoke's law toward the center with descent velocity that depends on the local acceleration due to gravity. Apart from the accretion and the radioactive heat energies, the gravitational energy produced during the differentiation of Mars and the associated heat transfer is also parametrically incorporated in the present work to make an assessment of its contribution to the early thermal evolution of Mars. We conclude that the accretion energy alone cannot produce widespread melting and differentiation of Mars even with an efficient consumption of the accretion energy. This makes 26Al the prime source for the heating and planetary scale differentiation of Mars. We demonstrate a rapid accretion and core-mantle differentiation of Mars within the initial ~1.5 Myr. This is consistent with the chronological records of Martian meteorites.

Foot use during vertical climbing in chimpanzees (Pan troglodytes).

PubMed

Wunderlich, R E; Ischinger, S B

2017-08-01

Upright bipedalism is a hallmark of hominin locomotion, however debates continue regarding the extent of arboreal locomotion and the nature of bipedalism practiced by early hominins. Pedal form and function play a prominent role in these debates, as the foot is the element that directly interacts with the locomotor substrate. Recent finds have substantially increased the availability of associated foot remains of early hominins and emphasized the enigmatic nature of the early evolution of human bipedalism. New discoveries of associated forefoot remains have afforded the opportunity to assess relative proportions across the forefoot of fossil hominins and illuminated the need for data on relative loading across the forefoot in extant hominoids. In order to provide functional data with which to examine the relationship between bony features and load distribution across the forefoot during climbing, we present the first analysis of plantar pressure distribution across the forefoot of chimpanzees climbing a vertical support. Chimpanzees load the medial metatarsals and first toe disproportionately during vertical climbing. Peak pressures on these elements occur at the end of stance phase during climbing and are higher than on any other elements of the foot. Toe pressures are considerably higher during vertical climbing than during knuckle-walking or movement on horizontal poles, supporting the notion that the plantarly-broad and dorsally-narrow metatarsal heads in chimpanzees and some early hominins are associated with close-packing of the metatarsophalangeal joint during climbing. Copyright © 2017 Elsevier Ltd. All rights reserved.

Genetic history of an archaic hominin group from Denisova Cave in Siberia

PubMed Central

Reich, David; Green, Richard E.; Kircher, Martin; Krause, Johannes; Patterson, Nick; Durand, Eric Y.; Viola, Bence; Briggs, Adrian W.; Stenzel, Udo; Johnson, Philip L. F.; Maricic, Tomislav; Good, Jeffrey M.; Marques-Bonet, Tomas; Alkan, Can; Fu, Qiaomei; Mallick, Swapan; Li, Heng; Meyer, Matthias; Eichler, Evan E.; Stoneking, Mark; Richards, Michael; Talamo, Sahra; Shunkov, Michael V.; Derevianko, Anatoli P.; Hublin, Jean-Jacques; Kelso, Janet; Slatkin, Montgomery; Pääbo, Svante

2015-01-01

Using DNA extracted from a finger bone found in Denisova Cave in southern Siberia, we have sequenced the genome of an archaic hominin to about 1.9-fold coverage. This individual is from a group that shares a common origin with Neanderthals. This population was not involved in the putative gene flow from Neanderthals into Eurasians; however, the data suggest that it contributed 4–6% of its genetic material to the genomes of present-day Melanesians. We designate this hominin population ‘Denisovans’ and suggest that it may have been widespread in Asia during the Late Pleistocene epoch. A tooth found in Denisova Cave carries a mitochondrial genome highly similar to that of the finger bone. This tooth shares no derived morphological features with Neanderthals or modern humans, further indicating that Denisovans have an evolutionary history distinct from Neanderthals and modern humans. PMID:21179161

Early Precambrian crustal evolution of south India

NASA Technical Reports Server (NTRS)

Srinivasan, R.

1986-01-01

The Early Precambrian sequence in Karnataka, South India provides evidences for a distinct trend of evolution which differs from trends exhibited in many other Early Precambrian regions of the world. The supracrustal rock associations preserved in greenstone belts and as inclusions in gneisses and granulites suggest the evolution of the terrain from a stable to a mobile regime. The stable regime is represented by (1) layered ultramafic-mafic complexes, (2) orthoquartzite-basalt-rhyodacite-iron formation, and (30 ortho-quartzite-carbonate-Mn-Fe formation. The mobile regime, which can be shown on sedimentological grounds to have succeeded the stable regime, witnessed the accumulation of a greywacke-pillow basalt-dacite-rhyolite-iron formation association. Detrital sediments of the stable zone accumulated dominantly in fluvial environment and the associated volcanics are ubaerial. The volcanics of the stable regime are tholeiites derived from a zirconium and LREE-enriched sources. The greywackes of the mobile regime are turbidities, and the volcanic rocks possess continental margin (island-arc or back-arc) affinity; they show a LREE depleted to slightly LREE-enriched pattern. The evolution from a stable to a mobile regime is in contrast to the trend seen in most other regions of the world, where an early dominantly volcanic association of a mobile regime gives way upward in the sequence to sediments characteristic of a stable regime.

The cheetah Acinonyx pardinensis (Croizet et Jobert, 1828) s.l. at the hominin site of Dmanisi (Georgia) - A potential prime meat supplier in Early Pleistocene ecosystems

NASA Astrophysics Data System (ADS)

Hemmer, Helmut; Kahlke, Ralf-Dietrich; Vekua, Abesalom K.

2011-09-01

The fossil site of Dmanisi (southern Georgia) has yielded a significant amount of hominin remains dated to around 1.8 Ma, in addition to a rich contemporaneous faunal record. Based on topographic information combined with an updated list of the vertebrate faunal assemblage, the corresponding palaeo-landscape has been reconstructed. Over a distance of some kilometres the landscape pattern changed from that of a forested valley floor, to tree savannah and open grasslands, thus providing typical habitats for carnivores hunting in open spaces. Morphological analysis of the elements from a nearly complete cat's foreleg reveals the existence of a large and stoutly built cheetah, Acinonyx pardinensis (Croizet et Jobert, 1828) s.l., in the Dmanisi faunal assemblage. Body mass estimations based on the humerus and metacarpals point to a cat of around 100 kg. The amount of pure meat and associated leftovers produced by the cheetah's hunting activity available for other consumers has been estimated. Within Early Pleistocene ecosystems, the cheetah must be considered as a potential fresh prime meat supplier, above that of any other felid.

Form and function of the human and chimpanzee forefoot: implications for early hominin bipedalism

PubMed Central

Fernández, Peter J.; Holowka, Nicholas B.; Demes, Brigitte; Jungers, William L.

2016-01-01

During bipedal walking, modern humans dorsiflex their forefoot at the metatarsophalangeal joints (MTPJs) prior to push off, which tightens the plantar soft tissues to convert the foot into a stiff propulsive lever. Particular features of metatarsal head morphology such as “dorsal doming” are thought to facilitate this stiffening mechanism. In contrast, chimpanzees are believed to possess MTPJ morphology that precludes high dorsiflexion excursions during terrestrial locomotion. The morphological affinity of the metatarsal heads has been used to reconstruct locomotor behavior in fossil hominins, but few studies have provided detailed empirical data to validate the assumed link between morphology and function at the MTPJs. Using three-dimensional kinematic and morphometric analyses, we show that humans push off with greater peak dorsiflexion angles at all MTPJs than do chimpanzees during bipedal and quadrupedal walking, with the greatest disparity occurring at MTPJ 1. Among MTPJs 2–5, both species exhibit decreasing peak angles from medial to lateral. This kinematic pattern is mirrored in the morphometric analyses of metatarsal head shape. Analyses of Australopithecus afarensis metatarsals reveal morphology intermediate between humans and chimpanzees, suggesting that this species used different bipedal push-off kinematics than modern humans, perhaps resulting in a less efficient form of bipedalism. PMID:27464580

Form and function of the human and chimpanzee forefoot: implications for early hominin bipedalism.

PubMed

Fernández, Peter J; Holowka, Nicholas B; Demes, Brigitte; Jungers, William L

2016-07-28

During bipedal walking, modern humans dorsiflex their forefoot at the metatarsophalangeal joints (MTPJs) prior to push off, which tightens the plantar soft tissues to convert the foot into a stiff propulsive lever. Particular features of metatarsal head morphology such as "dorsal doming" are thought to facilitate this stiffening mechanism. In contrast, chimpanzees are believed to possess MTPJ morphology that precludes high dorsiflexion excursions during terrestrial locomotion. The morphological affinity of the metatarsal heads has been used to reconstruct locomotor behavior in fossil hominins, but few studies have provided detailed empirical data to validate the assumed link between morphology and function at the MTPJs. Using three-dimensional kinematic and morphometric analyses, we show that humans push off with greater peak dorsiflexion angles at all MTPJs than do chimpanzees during bipedal and quadrupedal walking, with the greatest disparity occurring at MTPJ 1. Among MTPJs 2-5, both species exhibit decreasing peak angles from medial to lateral. This kinematic pattern is mirrored in the morphometric analyses of metatarsal head shape. Analyses of Australopithecus afarensis metatarsals reveal morphology intermediate between humans and chimpanzees, suggesting that this species used different bipedal push-off kinematics than modern humans, perhaps resulting in a less efficient form of bipedalism.

Tectonic uplift-influenced monsoonal changes promoted hominin occupation of the Luonan Basin: Insights from a loess-paleosol sequence, eastern Qinling Mountains, central China

NASA Astrophysics Data System (ADS)

Fang, Qian; Hong, Hanlie; Zhao, Lulu; Furnes, Harald; Lu, Huayu; Han, Wen; Liu, Yao; Jia, Zhuoyue; Wang, Chaowen; Yin, Ke; Algeo, Thomas J.

2017-08-01

Quaternary soil deposits from northern and southern China are distinctly different, reflecting variability of the East Asian monsoon north and south of the Qinling Mountains. Coeval sediments from the transitional climatic zone of central China, which are little studied to date, have the potential to improve our understanding of Quaternary monsoon changes and associated influences on hominin occupation of this region. Here, we investigate in detail a well-preserved and continuous Quaternary loess-paleosol sequence (Shangbaichuan) from the Luonan Basin, using a variety of weathering indices including major and trace element ratios, clay mineralogy, and Fe-oxide mineralogy. The whole-rock samples display similar rare earth element patterns characterized by upper continental crustal ratios: (La/Yb)N ≈ 9.5 and Eu/Eu* ≈ 0.65. Elemental data such as (La/Yb)N, La/Th and Eu/Eu* ratios show a high degree of homogeneity, suggesting that dust in the source region may have been thoroughly mixed and recycled, resulting in all samples having a uniform initial composition. Indices for pedogenic weathering such as Na/K, Ba/Sr, Rb/Sr, CIA, CIW, CPA, PIA, kaolinite/illite, (kaolinite + smectite)/illite, and hematite/(hematite + goethite) exhibit similar secular trends and reveal a four-stage accumulation history. The indices also indicate that the climate was warmer and wetter during the most recent interglacial stage, compared with coeval environments of the Chinese Loess Plateau. Secular changes in weathering intensity can be related to stepwise uplift of the Qinling Mountains and variation in East Asian monsoon intensity, both of which played significant roles in controlling climate evolution in the Luonan Basin. Furthermore, intensified aridity and winter monsoon strength in dust source areas, as evidenced by mineralogic and geochemical changes, may have been due to the mid-Pleistocene climate transition. Based on temporal correlation of warmer and wetter climatic conditions

Early evolution without a tree of life.

PubMed

Martin, William F

2011-06-30

Life is a chemical reaction. Three major transitions in early evolution are considered without recourse to a tree of life. The origin of prokaryotes required a steady supply of energy and electrons, probably in the form of molecular hydrogen stemming from serpentinization. Microbial genome evolution is not a treelike process because of lateral gene transfer and the endosymbiotic origins of organelles. The lack of true intermediates in the prokaryote-to-eukaryote transition has a bioenergetic cause.

MEVTV study: Early tectonic evolution of Mars: Crustal dichotomy to Valles Marineris

NASA Technical Reports Server (NTRS)

Frey, Herbert V.; Schultz, Richard A.

1990-01-01

Several fundamental problems were addressed in the early impact, tectonic, and volcanic evolution of the martian lithosphere: (1) origin and evolution of the fundamental crustal dichotomy, including development of the highland/lowland transition zone; (2) growth and evolution of the Valles Marineris; and (3) nature and role of major resurfacing events in early martian history. The results in these areas are briefly summarized.

The evolution of the human pelvis: changing adaptations to bipedalism, obstetrics and thermoregulation.

PubMed

Gruss, Laura Tobias; Schmitt, Daniel

2015-03-05

The fossil record of the human pelvis reveals the selective priorities acting on hominin anatomy at different points in our evolutionary history, during which mechanical requirements for locomotion, childbirth and thermoregulation often conflicted. In our earliest upright ancestors, fundamental alterations of the pelvis compared with non-human primates facilitated bipedal walking. Further changes early in hominin evolution produced a platypelloid birth canal in a pelvis that was wide overall, with flaring ilia. This pelvic form was maintained over 3-4 Myr with only moderate changes in response to greater habitat diversity, changes in locomotor behaviour and increases in brain size. It was not until Homo sapiens evolved in Africa and the Middle East 200 000 years ago that the narrow anatomically modern pelvis with a more circular birth canal emerged. This major change appears to reflect selective pressures for further increases in neonatal brain size and for a narrow body shape associated with heat dissipation in warm environments. The advent of the modern birth canal, the shape and alignment of which require fetal rotation during birth, allowed the earliest members of our species to deal obstetrically with increases in encephalization while maintaining a narrow body to meet thermoregulatory demands and enhance locomotor performance. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

Evolution of middle-late Pleistocene human cranio-facial form: a 3-D approach.

PubMed

Harvati, Katerina; Hublin, Jean-Jacques; Gunz, Philipp

2010-11-01

The classification and phylogenetic relationships of the middle Pleistocene human fossil record remains one of the most intractable problems in paleoanthropology. Several authors have noted broad resemblances between European and African fossils from this period, suggesting a single taxon ancestral to both modern humans and Neanderthals. Others point out 'incipient' Neanderthal features in the morphology of the European sample and have argued for their inclusion in the Neanderthal lineage exclusively, following a model of accretionary evolution of Neanderthals. We approach these questions using geometric morphometric methods which allow the intuitive visualization and quantification of features previously described qualitatively. We apply these techniques to evaluate proposed cranio-facial 'incipient' facial, vault, and basicranial traits in a middle-late Pleistocene European hominin sample when compared to a sample of the same time depth from Africa. Some of the features examined followed the predictions of the accretion model and relate the middle Pleistocene European material to the later Neanderthals. However, although our analysis showed a clear separation between Neanderthals and early/recent modern humans and morphological proximity between European specimens from OIS 7 to 3, it also shows that the European hominins from the first half of the middle Pleistocene still shared most of their cranio-facial architecture with their African contemporaries. Copyright © 2010 Elsevier Ltd. All rights reserved.

Cranial base topology and basic trends in the facial evolution of Homo.

PubMed

Bastir, Markus; Rosas, Antonio

2016-02-01

Facial prognathism and projection are important characteristics in human evolution but their three-dimensional (3D) architectonic relationships to basicranial morphology are not clear. We used geometric morphometrics and measured 51 3D-landmarks in a comparative sample of modern humans (N = 78) and fossil Pleistocene hominins (N = 10) to investigate the spatial features of covariation between basicranial and facial elements. The study reveals complex morphological integration patterns in craniofacial evolution of Middle and Late Pleistocene hominins. A downwards-orientated cranial base correlates with alveolar maxillary prognathism, relatively larger faces, and relatively larger distances between the anterior cranial base and the frontal bone (projection). This upper facial projection correlates with increased overall relative size of the maxillary alveolar process. Vertical facial height is associated with tall nasal cavities and is accommodated by an elevated anterior cranial base, possibly because of relations between the cribriform and the nasal cavity in relation to body size and energetics. Variation in upper- and mid-facial projection can further be produced by basicranial topology in which the midline base and nasal cavity are shifted anteriorly relative to retracted lateral parts of the base and the face. The zygomatics and the middle cranial fossae act together as bilateral vertical systems that are either projected or retracted relative to the midline facial elements, causing either midfacial flatness or midfacial projection correspondingly. We propose that facial flatness and facial projection reflect classical principles of craniofacial growth counterparts, while facial orientation relative to the basicranium as well as facial proportions reflect the complex interplay of head-body integration in the light of encephalization and body size decrease in Middle to Late Pleistocene hominin evolution. Developmental and evolutionary patterns of integration may

The Origin and Early Evolution of Membrane Proteins

NASA Technical Reports Server (NTRS)

Pohorille, Andrew; Schweighofter, Karl; Wilson, Michael A.

2006-01-01

The origin and early evolution of membrane proteins, and in particular ion channels, are considered from the point of view that the transmembrane segments of membrane proteins are structurally quite simple and do not require specific sequences to fold. We argue that the transport of solute species, especially ions, required an early evolution of efficient transport mechanisms, and that the emergence of simple ion channels was protobiologically plausible. We also argue that, despite their simple structure, such channels could possess properties that, at the first sight, appear to require markedly larger complexity. These properties can be subtly modulated by local modifications to the sequence rather than global changes in molecular architecture. In order to address the evolution and development of ion channels, we focus on identifying those protein domains that are commonly associated with ion channel proteins and are conserved throughout the three main domains of life (Eukarya, Prokarya, and Archaea). We discuss the potassium-sodium-calcium superfamily of voltage-gated ion channels, mechanosensitive channels, porins, and ABC-transporters and argue that these families of membrane channels have sufficiently universal architectures that they can readily adapt to the diverse functional demands arising during evolution.

Shape Ontogeny of the Distal Femur in the Hominidae with Implications for the Evolution of Bipedality

PubMed Central

Tallman, Melissa

2016-01-01

Heterochrony has been invoked to explain differences in the morphology of modern humans as compared to other great apes. The distal femur is one area where heterochrony has been hypothesized to explain morphological differentiation among Plio-Pleistocene hominins. This hypothesis is evaluated here using geometric morphometric data to describe the ontogenetic shape trajectories of extant hominine distal femora and place Plio-Pleistocene hominins within that context. Results of multivariate statistical analyses showed that in both Homo and Gorilla, the shape of the distal femur changes significantly over the course of development, whereas that of Pan changes very little. Development of the distal femur of Homo is characterized by an elongation of the condyles, and a greater degree of enlargement of the medial condyle relative to the lateral condyle, whereas Gorilla are characterized by a greater degree of enlargement of the lateral condyle, relative to the medial. Early Homo and Australopithecus africanus fossils fell on the modern human ontogenetic shape trajectory and were most similar to either adult or adolescent modern humans while specimens of Australopithecus afarensis were more similar to Gorilla/Pan. These results indicate that shape differences among the distal femora of Plio-Pleistocene hominins and humans cannot be accounted for by heterochrony alone; heterochrony could explain a transition from the distal femoral shape of early Homo/A. africanus to modern Homo, but not a transition from A. afarensis to Homo. That change could be the result of genetic or epigenetic factors. PMID:26886416

Laetoli footprints reveal bipedal gait biomechanics different from those of modern humans and chimpanzees

PubMed Central

Demes, Brigitte; Richmond, Brian G.

2016-01-01

Bipedalism is a key adaptation that shaped human evolution, yet the timing and nature of its evolution remain unclear. Here we use new experimentally based approaches to investigate the locomotor mechanics preserved by the famous Pliocene hominin footprints from Laetoli, Tanzania. We conducted footprint formation experiments with habitually barefoot humans and with chimpanzees to quantitatively compare their footprints to those preserved at Laetoli. Our results show that the Laetoli footprints are morphologically distinct from those of both chimpanzees and habitually barefoot modern humans. By analysing biomechanical data that were collected during the human experiments we, for the first time, directly link differences between the Laetoli and modern human footprints to specific biomechanical variables. We find that the Laetoli hominin probably used a more flexed limb posture at foot strike than modern humans when walking bipedally. The Laetoli footprints provide a clear snapshot of an early hominin bipedal gait that probably involved a limb posture that was slightly but significantly different from our own, and these data support the hypothesis that important evolutionary changes to hominin bipedalism occurred within the past 3.66 Myr. PMID:27488647

Discovering Hominins - Application of Medical Computed Tomography (CT) to Fossil-Bearing Rocks from the Site of Malapa, South Africa.

PubMed

Smilg, Jacqueline S; Berger, Lee R

2015-01-01

In the South African context, computed tomography (CT) has been used applied to individually prepared fossils and small rocks containing fossils, but has not been utilized on large breccia blocks as a means of discovering fossils, and particularly fossil hominins. Previous attempts at CT imaging of rocks from other South African sites for this purpose yielded disappointing results. For this study, 109 fossil- bearing rocks from the site of Malapa, South Africa were scanned with medical CT prior to manual preparation. The resultant images were assessed for accuracy of fossil identification and characterization against the standard of manual preparation. The accurate identification of fossils, including those of early hominins, that were not visible on the surface of individual blocks, is shown to be possible. The discovery of unexpected fossils is reduced, thus lowering the potential that fossils could be damaged through accidental encounter during routine preparation, or even entirely missed. This study should significantly change the way fossil discovery, recovery and preparation is done in the South African context and has potential for application in other palaeontological situations. Medical CT imaging is shown to be reliable, readily available, cost effective and accurate in finding fossils within matrix conglomerates. Improvements in CT equipment and in CT image quality are such that medical CT is now a viable imaging modality for this palaeontological application.

Discovering Hominins - Application of Medical Computed Tomography (CT) to Fossil-Bearing Rocks from the Site of Malapa, South Africa

PubMed Central

Smilg, Jacqueline S.; Berger, Lee R.

2015-01-01

In the South African context, computed tomography (CT) has been used applied to individually prepared fossils and small rocks containing fossils, but has not been utilized on large breccia blocks as a means of discovering fossils, and particularly fossil hominins. Previous attempts at CT imaging of rocks from other South African sites for this purpose yielded disappointing results. For this study, 109 fossil- bearing rocks from the site of Malapa, South Africa were scanned with medical CT prior to manual preparation. The resultant images were assessed for accuracy of fossil identification and characterization against the standard of manual preparation. The accurate identification of fossils, including those of early hominins, that were not visible on the surface of individual blocks, is shown to be possible. The discovery of unexpected fossils is reduced, thus lowering the potential that fossils could be damaged through accidental encounter during routine preparation, or even entirely missed. This study should significantly change the way fossil discovery, recovery and preparation is done in the South African context and has potential for application in other palaeontological situations. Medical CT imaging is shown to be reliable, readily available, cost effective and accurate in finding fossils within matrix conglomerates. Improvements in CT equipment and in CT image quality are such that medical CT is now a viable imaging modality for this palaeontological application. PMID:26684299

Extant ape dental topography and its implications for reconstructing the emergence of early Homo.

PubMed

Berthaume, Michael A; Schroer, Kes

2017-11-01

Dental topography reflects diet accurately in several extant and extinct mammalian clades. However, dental topographic dietary reconstructions have high success rates only when closely related taxa are compared. Given the dietary breadth that exists among extant apes and likely existed among fossil hominins, dental topographic values from many species and subspecies of great apes are necessary for making dietary inferences about the hominin fossil record. Here, we present the results of one metric of dental topography, Dirichlet normal energy (DNE), for seven groups of great apes (Pongo pygmaeus pygmaeus, Pan paniscus, Pan troglodytes troglodytes and schweinfurthii, Gorilla gorilla gorilla, Gorilla beringei graueri and beringei). Dirichlet normal energy was inadequate at differentiating folivores from frugivores, but was adequate at predicting which groups had more fibrous diets among sympatric African apes. Character displacement analyses confirmed there is substantial dental topographic and relative molar size (M 1 :M 2 ratio; length, width, and area) divergence in sympatric apes when compared to their allopatric counterparts, but character displacement is only present in relative molar size when DNE is also considered. Presence of character displacement is likely due to indirect competition over similar food resources. Assuming similar ecological conditions in the Plio-Pleistocene, the derived masticatory apparatuses of the robust australopiths and early Homo may be due to indirect competition over dietary resources between the taxa, causing dietary niche partitioning. Our results imply that dental topography cannot be used to predict dietary categories in fossil hominins without consideration of ecological factors, such as dietary and geographic overlap. In addition, our results may open new avenues for understanding the community compositions of early hominins and the formation of specific ecological niches among hominin taxa. Copyright © 2017 Elsevier Ltd

Early evolution without a tree of life

PubMed Central

2011-01-01

Life is a chemical reaction. Three major transitions in early evolution are considered without recourse to a tree of life. The origin of prokaryotes required a steady supply of energy and electrons, probably in the form of molecular hydrogen stemming from serpentinization. Microbial genome evolution is not a treelike process because of lateral gene transfer and the endosymbiotic origins of organelles. The lack of true intermediates in the prokaryote-to-eukaryote transition has a bioenergetic cause. This article was reviewed by Dan Graur, W. Ford Doolittle, Eugene V. Koonin and Christophe Malaterre. PMID:21714942

Further morphological evidence on South African earliest Homo lower postcanine dentition: Enamel thickness and enamel dentine junction.

PubMed

Pan, Lei; Dumoncel, Jean; de Beer, Frikkie; Hoffman, Jakobus; Thackeray, John Francis; Duployer, Benjamin; Tenailleau, Christophe; Braga, José

2016-07-01

The appearance of the earliest members of the genus Homo in South Africa represents a key event in human evolution. Although enamel thickness and enamel dentine junction (EDJ) morphology preserve important information about hominin systematics and dietary adaptation, these features have not been sufficiently studied with regard to early Homo. We used micro-CT to compare enamel thickness and EDJ morphology among the mandibular postcanine dentitions of South African early hominins (N = 30) and extant Homo sapiens (N = 26), with special reference to early members of the genus Homo. We found that South African early Homo shows a similar enamel thickness distribution pattern to modern humans, although three-dimensional average and relative enamel thicknesses do not distinguish australopiths, early Homo, and modern humans particularly well. Based on enamel thickness distributions, our study suggests that a dietary shift occurred between australopiths and the origin of the Homo lineage. We also observed that South African early Homo postcanine EDJ combined primitive traits seen in australopith molars with derived features observed in modern human premolars. Our results confirm that some dental morphological patterns in later Homo actually occurred early in the Homo lineage, and highlight the taxonomic value of premolar EDJ morphology in hominin species. Copyright © 2016 Elsevier Ltd. All rights reserved.

Elucidation of cross-species proteomic effects in human and hominin bone proteome identification through a bioinformatics experiment.

PubMed

Welker, F

2018-02-20

The study of ancient protein sequences is increasingly focused on the analysis of older samples, including those of ancient hominins. The analysis of such ancient proteomes thereby potentially suffers from "cross-species proteomic effects": the loss of peptide and protein identifications at increased evolutionary distances due to a larger number of protein sequence differences between the database sequence and the analyzed organism. Error-tolerant proteomic search algorithms should theoretically overcome this problem at both the peptide and protein level; however, this has not been demonstrated. If error-tolerant searches do not overcome the cross-species proteomic issue then there might be inherent biases in the identified proteomes. Here, a bioinformatics experiment is performed to test this using a set of modern human bone proteomes and three independent searches against sequence databases at increasing evolutionary distances: the human (0 Ma), chimpanzee (6-8 Ma) and orangutan (16-17 Ma) reference proteomes, respectively. Incorrectly suggested amino acid substitutions are absent when employing adequate filtering criteria for mutable Peptide Spectrum Matches (PSMs), but roughly half of the mutable PSMs were not recovered. As a result, peptide and protein identification rates are higher in error-tolerant mode compared to non-error-tolerant searches but did not recover protein identifications completely. Data indicates that peptide length and the number of mutations between the target and database sequences are the main factors influencing mutable PSM identification. The error-tolerant results suggest that the cross-species proteomics problem is not overcome at increasing evolutionary distances, even at the protein level. Peptide and protein loss has the potential to significantly impact divergence dating and proteome comparisons when using ancient samples as there is a bias towards the identification of conserved sequences and proteins. Effects are minimized

Bone taphonomy of the Schöningen "Spear Horizon South" and its implications for site formation and hominin meat provisioning.

PubMed

Starkovich, Britt M; Conard, Nicholas J

2015-12-01

This paper presents the faunal remains from the new excavation area at the Lower Paleolithic site of Schöningen. The focus of the study is on the southern extension of the main find horizon (Spear Horizon South), which includes the layer that yielded the famous Schöningen spears (13 II-4). Taxonomic data corroborate previous studies, that hominins primarily hunted Equus mosbachensis, a large Pleistocene horse. Equid body part representation at the site suggests that the animals were hunted and butchered locally. There is no evidence for density-mediated attrition in the assemblage. Weathering damage is uncommon, though there is ample evidence that carnivores had access to the bone. Carnivore bite sizes were measured and compared to experimental data provided by previous authors. Based on relationships between bite size and carnivore behavior and body size, we conclude that the primary modifying agents were large carnivores (i.e., wolves or saber-toothed cats). Previous studies show that carnivores often had secondary access to the remains, after hominins. Cut marks are commonly arranged haphazardly on the bones. This may indicate that multiple hominins participated in the butchery of horse skeletons, or that they were butchered over the course of hours or days. Cut marks on axial elements are more "orderly," which probably reflects the physical logistics of orienting one's body in relation to a large carcass. These data differ from sites formed by Middle and Upper Paleolithic hominins, which might suggest that in later times, a system of organized meat provisioning was already in place. Taken together, the faunal evidence from the Spear Horizon South indicates that late Lower Paleolithic hominins using the site understood the behaviors of different prey species, hunted socially to take down large game, and successfully competed with large carnivores on the landscape for primary access to ungulate remains. Copyright © 2015 Elsevier Ltd. All rights reserved.

Storytelling, behavior planning, and language evolution in context.

PubMed

McBride, Glen

2014-01-01

An attempt is made to specify the structure of the hominin bands that began steps to language. Storytelling could evolve without need for language yet be strongly subject to natural selection and could provide a major feedback process in evolving language. A storytelling model is examined, including its effects on the evolution of consciousness and the possible timing of language evolution. Behavior planning is presented as a model of language evolution from storytelling. The behavior programming mechanism in both directions provide a model of creating and understanding behavior and language. Culture began with societies, then family evolution, family life in troops, but storytelling created a culture of experiences, a final step in the long process of achieving experienced adults by natural selection. Most language evolution occurred in conversations where evolving non-verbal feedback ensured mutual agreements on understanding. Natural language evolved in conversations with feedback providing understanding of changes.

Storytelling, behavior planning, and language evolution in context

PubMed Central

McBride, Glen

2014-01-01

An attempt is made to specify the structure of the hominin bands that began steps to language. Storytelling could evolve without need for language yet be strongly subject to natural selection and could provide a major feedback process in evolving language. A storytelling model is examined, including its effects on the evolution of consciousness and the possible timing of language evolution. Behavior planning is presented as a model of language evolution from storytelling. The behavior programming mechanism in both directions provide a model of creating and understanding behavior and language. Culture began with societies, then family evolution, family life in troops, but storytelling created a culture of experiences, a final step in the long process of achieving experienced adults by natural selection. Most language evolution occurred in conversations where evolving non-verbal feedback ensured mutual agreements on understanding. Natural language evolved in conversations with feedback providing understanding of changes. PMID:25360123

Taphonomy of fossils from the hominin-bearing deposits at Dikika, Ethiopia.

PubMed

Thompson, Jessica C; McPherron, Shannon P; Bobe, René; Reed, Denné; Barr, W Andrew; Wynn, Jonathan G; Marean, Curtis W; Geraads, Denis; Alemseged, Zeresenay

2015-09-01

Two fossil specimens from the DIK-55 locality in the Hadar Formation at Dikika, Ethiopia, are contemporaneous with the earliest documented stone tools, and they collectively bear twelve marks interpreted to be characteristic of stone tool butchery damage. An alternative interpretation of the marks has been that they were caused by trampling animals and do not provide evidence of stone tool use or large ungulate exploitation by Australopithecus-grade hominins. Thus, resolving which agents created marks on fossils in deposits from Dikika is an essential step in understanding the ecological and taphonomic contexts of the hominin-bearing deposits in this region and establishing their relevance for investigations of the earliest stone tool use. This paper presents results of microscopic scrutiny of all non-hominin fossils collected from the Hadar Formation at Dikika, including additional fossils from DIK-55, and describes in detail seven assemblages from sieved surface sediment samples. The study is the first taphonomic description of Pliocene fossil assemblages from open-air deposits in Africa that were collected without using only methods that emphasize the selective retention of taxonomically-informative specimens. The sieved assemblages show distinctive differences in faunal representation and taphonomic modifications that suggest they sample a range of depositional environments in the Pliocene Hadar Lake Basin, and have implications for how landscape-based taphonomy can be used to infer past microhabitats. The surface modification data show that no marks on any other fossils resemble in size or shape those on the two specimens from DIK-55 that were interpreted to bear stone tool inflicted damage. A large sample of marks from the sieved collections has characteristics that match modern trampling damage, but these marks are significantly smaller than those on the DIK-55 specimens and have different suites of characteristics. Most are not visible without magnification

The lithic industry of Sima del Elefante (Atapuerca, Burgos, Spain) in the context of Early and Middle Pleistocene technology in Europe.

PubMed

de Lombera-Hermida, Arturo; Bargalló, Amèlia; Terradillos-Bernal, Marcos; Huguet, Rosa; Vallverdú, Josep; García-Antón, Maria-Dolores; Mosquera, Marina; Ollé, Andreu; Sala, Robert; Carbonell, Eudald; Rodríguez-Álvarez, Xosé-Pedro

2015-05-01

This paper presents the lithic assemblages documented at Sima del Elefante (TE) and their importance in the context of the Early and Middle Pleistocene human occupation of Europe. We also study changes in human behaviour within the context of the palaeoenvironmental evolution of the Sierra de Atapuerca. This site has characteristics that are of great value for the study of human evolution. The lower levels of TE (Units TE7-TE14) are an essential reference for understanding the early stages of the colonization of Europe. The TE9c level has provided stone tools (Mode 1), faunal remains, and human fossils dated to 1.22 Ma (millions of years ago). Moreover, this is one of the few European sites with a stratigraphic sequence that includes remains of human occupations predating the Jaramillo subchron (Early Pleistocene) and from the Late Middle Pleistocene (Units TE18-TE19). Despite this, the presence of archaeologically sterile units (TE15-17) prevents us from establishing a continuous relationship between the Early and Middle Pleistocene human settlements and, consequently, between their technological and behavioural differences. We can, however compare the technological and palaeoeconomic strategies adopted by different species of hominins during two key phases of the occupation of Europe. Copyright © 2015 Elsevier Ltd. All rights reserved.

The Hominin Sites and Paleolakes Drilling Project (HSPDP): Understanding the paleoenvironmental and paleoclimatic context of human origins through continental drilling

NASA Astrophysics Data System (ADS)

Cohen, Andrew S.; Campisano, Christopher; Asrat, Asfawossen; Arrowsmith, Ramon; Deino, Alan; Feibel, Craig; Hill, Andrew; Kingston, John; Lamb, Henry; Lowenstein, Tim; Olago, Daniel; Bernhart Owen, R.; Renaut, Robin; Schabitz, Frank; Trauth, Martin

2015-04-01

The influence of climate and environmental history on human evolution is an existential question that continues to be hotly debated, in part because of the paucity of high resolution records collected in close proximity to the key fossil and archaeological evidence. To address this issue and transform the scientific debate, the HSPDP was developed to collect lacustrine sediment drill cores from basins in Kenya and Ethiopia that collectively encompass critical time intervals and locations for Plio-Quaternary human evolution in East Africa. After a 17 month campaign, drilling was completed in November, 2014, with over 1750m of core collected from 11 boreholes from five areas (1930m total drilling length, avg. 91% recovery). The sites, from oldest to youngest, include 1) N. Awash, Ethiopia (~3.5-2.9Ma core interval); 2) Baringo-Tugen Hills, Kenya (~3.3-2.5Ma); 3) West Turkana, Kenya (~1.9-1.4Ma); L. Magadi, Kenya (0.8-0Ma) and the Chew Bahir Basin, Ethiopia (~0.5-0Ma). Initial core description (ICD) and sampling for geochronology, geochemistry and paleoecology studies had been completed by mid2014, with the two remaining sites (Magadi and Chew Bahir) scheduled for ICD work in early 2015. Whereas the primary scientific targets were the lacustrine deposits from the hominin-bearing basin depocenters, many intervals of paleosols (representative of low lake stands and probable arid periods) were also encountered in drill cores. Preliminary analyses of drill core sedimentology and geochemistry show both long-term lake level changes and cyclic variability in lake levels, both of which may be indicative of climatic forcing events of interest to paleoanthropologists. Authors of this abstract also include the entire HSPDP field team.

Dietary options and behavior suggested by plant biomarker evidence in an early human habitat

NASA Astrophysics Data System (ADS)

Magill, Clayton R.; Ashley, Gail M.; Domínguez-Rodrigo, Manuel; Freeman, Katherine H.

2016-03-01

The availability of plants and freshwater shapes the diets and social behavior of chimpanzees, our closest living relative. However, limited evidence about the spatial relationships shared between ancestral human (hominin) remains, edible resources, refuge, and freshwater leaves the influence of local resources on our species' evolution open to debate. Exceptionally well-preserved organic geochemical fossils-biomarkers-preserved in a soil horizon resolve different plant communities at meter scales across a contiguous 25,000 m2 archaeological land surface at Olduvai Gorge from about 2 Ma. Biomarkers reveal hominins had access to aquatic plants and protective woods in a patchwork landscape, which included a spring-fed wetland near a woodland that both were surrounded by open grassland. Numerous cut-marked animal bones are located within the wooded area, and within meters of wetland vegetation delineated by biomarkers for ferns and sedges. Taken together, plant biomarkers, clustered bone debris, and hominin remains define a clear spatial pattern that places animal butchery amid the refuge of an isolated forest patch and near freshwater with diverse edible resources.

Age and date for early arrival of the Acheulian in Europe (Barranc de la Boella, la Canonja, Spain).

PubMed

Vallverdú, Josep; Saladié, Palmira; Rosas, Antonio; Huguet, Rosa; Cáceres, Isabel; Mosquera, Marina; Garcia-Tabernero, Antonio; Estalrrich, Almudena; Lozano-Fernández, Iván; Pineda-Alcalá, Antonio; Carrancho, Ángel; Villalaín, Juan José; Bourlès, Didier; Braucher, Régis; Lebatard, Anne; Vilalta, Jaume; Esteban-Nadal, Montserrat; Bennàsar, Maria Lluc; Bastir, Marcus; López-Polín, Lucía; Ollé, Andreu; Vergés, Josep Maria; Ros-Montoya, Sergio; Martínez-Navarro, Bienvenido; García, Ana; Martinell, Jordi; Expósito, Isabel; Burjachs, Francesc; Agustí, Jordi; Carbonell, Eudald

2014-01-01

The first arrivals of hominin populations into Eurasia during the Early Pleistocene are currently considered to have occurred as short and poorly dated biological dispersions. Questions as to the tempo and mode of these early prehistoric settlements have given rise to debates concerning the taxonomic significance of the lithic assemblages, as trace fossils, and the geographical distribution of the technological traditions found in the Lower Palaeolithic record. Here, we report on the Barranc de la Boella site which has yielded a lithic assemblage dating to ∼1 million years ago that includes large cutting tools (LCT). We argue that distinct technological traditions coexisted in the Iberian archaeological repertoires of the late Early Pleistocene age in a similar way to the earliest sub-Saharan African artefact assemblages. These differences between stone tool assemblages may be attributed to the different chronologies of hominin dispersal events. The archaeological record of Barranc de la Boella completes the geographical distribution of LCT assemblages across southern Eurasia during the EMPT (Early-Middle Pleistocene Transition, circa 942 to 641 kyr). Up to now, chronology of the earliest European LCT assemblages is based on the abundant Palaeolithic record found in terrace river sequences which have been dated to the end of the EMPT and later. However, the findings at Barranc de la Boella suggest that early LCT lithic assemblages appeared in the SW of Europe during earlier hominin dispersal episodes before the definitive colonization of temperate Eurasia took place.

Age and Date for Early Arrival of the Acheulian in Europe (Barranc de la Boella, la Canonja, Spain)

PubMed Central

Vallverdú, Josep; Saladié, Palmira; Rosas, Antonio; Huguet, Rosa; Cáceres, Isabel; Mosquera, Marina; Garcia-Tabernero, Antonio; Estalrrich, Almudena; Lozano-Fernández, Iván; Pineda-Alcalá, Antonio; Carrancho, Ángel; Villalaín, Juan José; Bourlès, Didier; Braucher, Régis; Lebatard, Anne; Vilalta, Jaume; Esteban-Nadal, Montserrat; Bennàsar, Maria Lluc; Bastir, Marcus; López-Polín, Lucía; Ollé, Andreu; Vergés, Josep Maria; Ros-Montoya, Sergio; Martínez-Navarro, Bienvenido; García, Ana; Martinell, Jordi; Expósito, Isabel; Burjachs, Francesc; Agustí, Jordi; Carbonell, Eudald

2014-01-01

The first arrivals of hominin populations into Eurasia during the Early Pleistocene are currently considered to have occurred as short and poorly dated biological dispersions. Questions as to the tempo and mode of these early prehistoric settlements have given rise to debates concerning the taxonomic significance of the lithic assemblages, as trace fossils, and the geographical distribution of the technological traditions found in the Lower Palaeolithic record. Here, we report on the Barranc de la Boella site which has yielded a lithic assemblage dating to ∼1 million years ago that includes large cutting tools (LCT). We argue that distinct technological traditions coexisted in the Iberian archaeological repertoires of the late Early Pleistocene age in a similar way to the earliest sub-Saharan African artefact assemblages. These differences between stone tool assemblages may be attributed to the different chronologies of hominin dispersal events. The archaeological record of Barranc de la Boella completes the geographical distribution of LCT assemblages across southern Eurasia during the EMPT (Early-Middle Pleistocene Transition, circa 942 to 641 kyr). Up to now, chronology of the earliest European LCT assemblages is based on the abundant Palaeolithic record found in terrace river sequences which have been dated to the end of the EMPT and later. However, the findings at Barranc de la Boella suggest that early LCT lithic assemblages appeared in the SW of Europe during earlier hominin dispersal episodes before the definitive colonization of temperate Eurasia took place. PMID:25076416

Seasonality, extractive foraging and the evolution of primate sensorimotor intelligence.

PubMed

Melin, Amanda D; Young, Hilary C; Mosdossy, Krisztina N; Fedigan, Linda M

2014-06-01

The parallel evolution of increased sensorimotor intelligence in humans and capuchins has been linked to the cognitive and manual demands of seasonal extractive faunivory. This hypothesis is attractive on theoretical grounds, but it has eluded widespread acceptance due to lack of empirical data. For instance, the effects of seasonality on the extractive foraging behaviors of capuchins are largely unknown. Here we report foraging observations on four groups of wild capuchins (Cebus capucinus) inhabiting a seasonally dry tropical forest. We also measured intra-annual variation in temperature, rainfall, and food abundance. We found that the exploitation of embedded or mechanically protected invertebrates was concentrated during periods of fruit scarcity. Such a pattern suggests that embedded insects are best characterized as a fallback food for capuchins. We discuss the implications of seasonal extractive faunivory for the evolution of sensorimotor intelligence (SMI) in capuchins and hominins and suggest that the suite of features associated with SMI, including increased manual dexterity, tool use, and innovative problem solving are cognitive adaptations among frugivores that fall back seasonally on extractable foods. The selective pressures acting on SMI are predicted to be strongest among primates living in the most seasonal environments. This model is proffered to explain the differences in tool use between capuchin lineages, and SMI as an adaptation to extractive foraging is suggested to play an important role in hominin evolution. Copyright © 2014 Elsevier Ltd. All rights reserved.

Geoarchaeological approaches to Palaeolithic surface artefact distributions and hominin landscape use in SW Saudi Arabia

NASA Astrophysics Data System (ADS)

Inglis, Robyn; Sinclair, Anthony; Fanning, Patricia; Alsharekh, Abdullah; Bailey, Geoff

2017-04-01

The vast majority of Palaeolithic archaeological material in arid and semi-arid regions exists in the form of scatters of stone tools across the surface of present-day landscapes. This is particularly the case in the Saharo-Arabian desert belt, a region vital to understanding the global dispersal of hominins from Africa. These surface artefacts possess little stratigraphic context, but comprise the only record we possess to examine spatial behavioural patterning and landscape use by hominin populations. Interpretation of the observed spatial distribution of artefacts is far from straightforward. Surface artefact distributions result from a complex interplay of varying human behaviours over time. Also, geomorphological processes affect the preservation, exposure and visibility of the artefacts, as well as alter the presence and location of attractive resources. The SURFACE project employs an interdisciplinary approach to understanding the distribution of Palaeolithic artefacts in SW Saudi Arabia. By combining remote sensing, geomorphological fieldwork, archaeological survey and GIS analyses, the project is developing a geomorphological context for the artefacts that guides survey to areas of high archaeological potential, as well as allowing the robust interpretation of the observed artefact distribution in a dynamic landscape in terms of past landscape use. This paper will present the ongoing multi-scalar approaches employed by the project to Palaeolithic landscapes, particularly focussing on the site of Wadi Dabsa, Asir Province, where Lower and Middle Palaeolithic artefacts have been found in association with extensive tufa deposits. Investigation in early 2017 at the site will apply SURFACE's methods to understand the present-day artefact distributions at the exposure, and their relationship to the tufa deposition, as well as their potential to inform on Palaeolithic activity and landscape use at the site.

Evolution of the Human Pelvis.

PubMed

Rosenberg, Karen R; DeSilva, Jeremy M

2017-05-01

No bone in the human postcranial skeleton differs more dramatically from its match in an ape skeleton than the pelvis. Humans have evolved a specialized pelvis, well-adapted for the rigors of bipedal locomotion. Precisely how this happened has been the subject of great interest and contention in the paleoanthropological literature. In part, this is because of the fragility of the pelvis and its resulting rarity in the human fossil record. However, new discoveries from Miocene hominoids and Plio-Pleistocene hominins have reenergized debates about human pelvic evolution and shed new light on the competing roles of bipedal locomotion and obstetrics in shaping pelvic anatomy. In this issue, 13 papers address the evolution of the human pelvis. Here, we summarize these new contributions to our understanding of pelvic evolution, and share our own thoughts on the progress the field has made, and the questions that still remain. Anat Rec, 300:789-797, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Pleistocene Hominins as a Resource for Carnivores: A c. 500,000-Year-Old Human Femur Bearing Tooth-Marks in North Africa (Thomas Quarry I, Morocco)

PubMed Central

Daujeard, Camille; Geraads, Denis; Gallotti, Rosalia; Lefèvre, David; Mohib, Abderrahim; Raynal, Jean-Paul; Hublin, Jean-Jacques

2016-01-01

In many Middle Pleistocene sites, the co-occurrence of hominins with carnivores, who both contributed to faunal accumulations, suggests competition for resources as well as for living spaces. Despite this, there is very little evidence of direct interaction between them to-date. Recently, a human femoral diaphysis has been recognized in South-West of Casablanca (Morocco), in the locality called Thomas Quarry I. This site is famous for its Middle Pleistocene fossil hominins considered representatives of Homo rhodesiensis. The bone was discovered in Unit 4 of the Grotte à Hominidés (GH), dated to c. 500 ky and was associated with Acheulean artefacts and a rich mammalian fauna. Anatomically, it fits well within the group of known early Middle Pleistocene Homo, but its chief point of interest is that the diaphyseal ends display numerous tooth marks showing that it had been consumed shortly after death by a large carnivore, probably a hyena. This bone represents the first evidence of consumption of human remains by carnivores in the cave. Whether predated or scavenged, this chewed femur indicates that humans were a resource for carnivores, underlining their close relationships during the Middle Pleistocene in Atlantic Morocco. PMID:27120202

A new hypothesis of dinosaur relationships and early dinosaur evolution.

PubMed

Baron, Matthew G; Norman, David B; Barrett, Paul M

2017-03-22

For 130 years, dinosaurs have been divided into two distinct clades-Ornithischia and Saurischia. Here we present a hypothesis for the phylogenetic relationships of the major dinosaurian groups that challenges the current consensus concerning early dinosaur evolution and highlights problematic aspects of current cladistic definitions. Our study has found a sister-group relationship between Ornithischia and Theropoda (united in the new clade Ornithoscelida), with Sauropodomorpha and Herrerasauridae (as the redefined Saurischia) forming its monophyletic outgroup. This new tree topology requires redefinition and rediagnosis of Dinosauria and the subsidiary dinosaurian clades. In addition, it forces re-evaluations of early dinosaur cladogenesis and character evolution, suggests that hypercarnivory was acquired independently in herrerasaurids and theropods, and offers an explanation for many of the anatomical features previously regarded as notable convergences between theropods and early ornithischians.

Metric and geometric morphometric analysis of new hominin fossils from Maba (Guangdong, China).

PubMed

Xiao, Dongfang; Bae, Christopher J; Shen, Guanjun; Delson, Eric; Jin, Jennie J H; Webb, Nicole M; Qiu, Licheng

2014-09-01

We present an analysis of a set of previously unreported hominin fossils from Maba (Guangdong, China), a cave site that is best known for the presence of a partial hominin cranium currently assigned as mid-Pleistocene Homo and that has been traditionally dated to around the Middle-Late Pleistocene transition. A more recent set of Uranium series dates indicate that the Maba travertine may date to >237 ka (thousands of years ago), as opposed to the original U-series date, which placed Maba at 135-129 ka. The fossils under study include five upper first and second molars and a partial left mandible with a socketed m3, all recovered from different parts of the site than the cranium or the dated sediments. The results of our metric and 2D geometric morphometric ('GM') study suggest that the upper first molars are likely from modern humans, suggesting a more recent origin. The upper second molars align more closely with modern humans, though the minimum spanning tree from the 2D GM analysis also connects Maba to Homo neanderthalensis. The patterning in the M2s is not as clear as with the M1s. The m3 and partial mandible are morphometrically intermediate between Holocene modern humans and older Homo sapiens. However, a minimum spanning tree indicates that both the partial mandible and m3 align most closely with Holocene modern humans, and they also may be substantially younger than the cranium. Because questions exist regarding the context and the relationship of the dated travertine with the hominin fossils, we suggest caution is warranted in interpreting the Maba specimens. Copyright © 2014 Elsevier Ltd. All rights reserved.

Early School-Leaving in Spain: Evolution, Intensity and Determinants

ERIC Educational Resources Information Center

Fernandez-Macias, Enrique; Anton, Jose-Ignacio; Brana, Francisco-Javier; De Bustillo, Rafael Munoz

2013-01-01

Spain has one of the highest levels of early school leaving and educational failure of the European Union. The purpose of this paper is to analyse the anatomy of early school leaving in Spain and its characteristics. In order to do so, in the first part we discuss the measurement problems related with this concept and the evolution of drop-out…

A 400,000-year-old mitochondrial genome questions phylogenetic relationships amongst archaic hominins: using the latest advances in ancient genomics, the mitochondrial genome sequence of a 400,000-year-old hominin has been deciphered.

PubMed

Orlando, Ludovic

2014-06-01

By combining state-of-the-art approaches in ancient genomics, Meyer and co-workers have reconstructed the mitochondrial sequence of an archaic hominin that lived at Sierra de Atapuerca, Spain about 400,000 years ago. This achievement follows recent advances in molecular anthropology that delivered the genome sequence of younger archaic hominins, such as Neanderthals and Denisovans. Molecular phylogenetic reconstructions placed the Atapuercan as a sister group to Denisovans, although its morphology suggested closer affinities with Neanderthals. In addition to possibly challenging our interpretation of the fossil record, this study confirms that genomic information can be recovered from extremely damaged DNA molecules, even in the presence of significant levels of human contamination. Together with the recent characterization of a 700,000-year-old horse genome, this study opens the Middle Pleistocene to genomics, thereby extending the scope of ancient DNA to the last million years. © 2014 WILEY Periodicals, Inc.

Postcranial morphology of the middle Pleistocene humans from Sima de los Huesos, Spain.

PubMed

Arsuaga, Juan Luis; Carretero, José-Miguel; Lorenzo, Carlos; Gómez-Olivencia, Asier; Pablos, Adrián; Rodríguez, Laura; García-González, Rebeca; Bonmatí, Alejandro; Quam, Rolf M; Pantoja-Pérez, Ana; Martínez, Ignacio; Aranburu, Arantza; Gracia-Téllez, Ana; Poza-Rey, Eva; Sala, Nohemi; García, Nuria; Alcázar de Velasco, Almudena; Cuenca-Bescós, Gloria; Bermúdez de Castro, José María; Carbonell, Eudald

2015-09-15

Current knowledge of the evolution of the postcranial skeleton in the genus Homo is hampered by a geographically and chronologically scattered fossil record. Here we present a complete characterization of the postcranium of the middle Pleistocene paleodeme from the Sima de los Huesos (SH) and its paleobiological implications. The SH hominins show the following: (i) wide bodies, a plesiomorphic character in the genus Homo inherited from their early hominin ancestors; (ii) statures that can be found in modern human middle-latitude populations that first appeared 1.6-1.5 Mya; and (iii) large femoral heads in some individuals, a trait that first appeared during the middle Pleistocene in Africa and Europe. The intrapopulational size variation in SH shows that the level of dimorphism was similar to modern humans (MH), but the SH hominins were less encephalized than Neandertals. SH shares many postcranial anatomical features with Neandertals. Although most of these features appear to be either plesiomorphic retentions or are of uncertain phylogenetic polarity, a few represent Neandertal apomorphies. Nevertheless, the full suite of Neandertal-derived features is not yet present in the SH population. The postcranial evidence is consistent with the hypothesis based on the cranial morphology that the SH hominins are a sister group to the later Neandertals. Comparison of the SH postcranial skeleton to other hominins suggests that the evolution of the postcranium occurred in a mosaic mode, both at a general and at a detailed level.

Postcranial morphology of the middle Pleistocene humans from Sima de los Huesos, Spain

PubMed Central

Arsuaga, Juan Luis; Carretero, José-Miguel; Lorenzo, Carlos; Gómez-Olivencia, Asier; Pablos, Adrián; Rodríguez, Laura; García-González, Rebeca; Bonmatí, Alejandro; Quam, Rolf M.; Pantoja-Pérez, Ana; Martínez, Ignacio; Aranburu, Arantza; Gracia-Téllez, Ana; Poza-Rey, Eva; Sala, Nohemi; García, Nuria; Alcázar de Velasco, Almudena; Cuenca-Bescós, Gloria; Bermúdez de Castro, José María; Carbonell, Eudald

2015-01-01

Current knowledge of the evolution of the postcranial skeleton in the genus Homo is hampered by a geographically and chronologically scattered fossil record. Here we present a complete characterization of the postcranium of the middle Pleistocene paleodeme from the Sima de los Huesos (SH) and its paleobiological implications. The SH hominins show the following: (i) wide bodies, a plesiomorphic character in the genus Homo inherited from their early hominin ancestors; (ii) statures that can be found in modern human middle-latitude populations that first appeared 1.6–1.5 Mya; and (iii) large femoral heads in some individuals, a trait that first appeared during the middle Pleistocene in Africa and Europe. The intrapopulational size variation in SH shows that the level of dimorphism was similar to modern humans (MH), but the SH hominins were less encephalized than Neandertals. SH shares many postcranial anatomical features with Neandertals. Although most of these features appear to be either plesiomorphic retentions or are of uncertain phylogenetic polarity, a few represent Neandertal apomorphies. Nevertheless, the full suite of Neandertal-derived features is not yet present in the SH population. The postcranial evidence is consistent with the hypothesis based on the cranial morphology that the SH hominins are a sister group to the later Neandertals. Comparison of the SH postcranial skeleton to other hominins suggests that the evolution of the postcranium occurred in a mosaic mode, both at a general and at a detailed level. PMID:26324920

Quantum Field Theory in Curved Spacetime

NASA Astrophysics Data System (ADS)

Reynolds, Sally C.; Gallagher, Andrew

2012-03-01

List of contributors; Foreword J. T. Francis Thackeray; 1. African genesis: an evolving paradigm Sally C. Reynolds; 2. Academic genealogy Peter Ungar and Phillip V. Tobias; Part I. In Search of Origins: Evolutionary Theory, New Species, and Paths into the Past: 3. Speciation in hominin evolution Colin Groves; 4. Searching for a new paradigm for hominid origins in Chad (Central Africa) Michel Brunet; 5. From hominoid arboreality to hominid bipedalism Brigitte Senut; 6. Orrorin and the African ape/hominid dichotomy Martin Pickford; 7. A brief history and results of 40 years of Sterkfontein excavations Ronald J. Clarke; Part II. Hominin Morphology Through Time: Brains, Bodies and Teeth: 8. Hominin brain evolution, 1925-2011: an emerging overview Dean Falk; 9. The issue of brain reorganisation in Australopithecus and early hominids: Dart had it right Ralph L. Holloway; 10. The mass of the human brain: is it a spandrel? Paul R. Manger, Jason Hemingway, Muhammad Spocter and Andrew Gallagher; 11. Origin and diversity of early hominin bipedalism Henry M. McHenry; 12. Forelimb adaptations in Australopithecus afarensis Michelle S. M. Drapeau; 13. Hominin proximal femur morphology from the Tugen Hills to Flores Brian G. Richmond and William L. Jungers; 14. Daily rates of dentine formation and root extension rates in Paranthropus boisei, KNM-ER 1817, from Koobi Fora, Kenya M. Christopher Dean; 15. On the evolutionary development of early hominid molar teeth and the Gondolin Paranthropus molar Kevin L. Kuykendall; 16. Digital South African fossils: morphological studies using reference-based reconstruction and electronic preparation Gerhard W. Weber, Philipp Gunz, Simon Neubauer, Philipp Mitteroecker and Fred L. Bookstein; Part III. Modern Human Origins: Patterns, and Processes: 17. Body size in African Middle Pleistocene Homo Steven E. Churchill, Lee R. Berger, Adam Hartstone-Rose and Headman Zondo; 18. The African origin of recent humanity Milford H. Wolpoff and Sang-Hee Lee

Taphonomic analysis of the hominin remains from Swabian Jura and their implications for the mortuary practices during the Upper Paleolithic

NASA Astrophysics Data System (ADS)

Sala, Nohemi; Conard, Nicholas

2016-10-01

The symbolic behavior of human beings usually is manifested in different ways such as figurative art, musical traditions, spoken language or complex funerary behavior. The Paleolithic sites of the Swabian Jura contain a rich archaeological record including the oldest evidence of musical instruments and figurative art which indicates complex cognitive abilities of the Paleolithic Homo sapiens that colonized Europe. Nevertheless, there is no evidence for burials in the Swabian caves during the Paleolithic. This raises questions regarding the kind of mortuary practices that existed in this region during the Paleolithic. In this paper, we address these questions from a taphonomic perspective by analyzing the hominin remains recovered in caves of the Swabian Jura. Whatever the funerary behavior was during the Early and Middle Upper Paleolithic, we have no evidence to document these practices. The Magdalenian hominin remains from Brillenhöhle, however, display anthropic modifications that have been hotly debated in the past. Our taphonomic analysis indicates that the assemblage displays traces of butchery similar to those recorded in the faunal remains. In addition to the cut marks, we have documented intentional breakage and human tooth marks, suggesting that the consumption of human corpses took place during the Magdalenian at Brillenhöhle. Similar anthropic modifications have also been documented in Magdalenian horizon at Hohle Fels. This suggests that the cannibalism practices during the Magdalenian were more common than previously expected during the Magdalenian in the Swabian Jura.

On the origin and early evolution of biological catalysis and other studies on chemical evolution

NASA Technical Reports Server (NTRS)

Oro, J.; Lazcano, A.

1991-01-01

One of the lines of research in molecular evolution which we have developed for the past three years is related to the experimental and theoretical study of the origin and early evolution of biological catalysis. In an attempt to understand the nature of the first peptidic catalysts and coenzymes, we have achieved the non-enzymatic synthesis of the coenzymes ADPG, GDPG, and CDP-ethanolamine, under conditions considered to have been prevalent on the primitive Earth. We have also accomplished the prebiotic synthesis of histidine, as well as histidyl-histidine, and we have measured the enhancing effects of this catalytic dipeptide on the dephosphorylation of deoxyribonucleotide monophosphates, the hydrolysis of oligo A, and the oligomerization 2', 3' cAMP. We reviewed and further developed the hypothesis that RNA preceded double stranded DNA molecules as a reservoir of cellular genetic information. This led us to undertake the study of extant RNA polymerases in an attempt to discover vestigial sequences preserved from early Archean times. In addition, we continued our studies of on the chemical evolution of organic compounds in the solar system and beyond.

Hominins without fellow travellers? First appearances and inferred dispersals of Afro-Eurasian large-mammals in the Plio-Pleistocene

NASA Astrophysics Data System (ADS)

O'Regan, H. J.; Turner, A.; Bishop, L. C.; Elton, S.; Lamb, A. L.

2011-06-01

Discoveries of fossil Homo outside Africa predating 1.0 Ma have generated much discussion about hominin dispersal routes. However, tool-using bipeds were only one element of the inter-continental mammalian dispersals that occurred during the climatic changes of the Pliocene and Pleistocene. This paper will place hominin movements in the context of those of the wider mammalian fauna, which includes carnivores, bovids and non-human primates. The distribution of these different taxa suggests that species moved individually when the environmental conditions were right for them, rather than in multi-species waves of dispersal, and allows evaluation of the contextual evidence for the newly emerging 'Out of Asia' paradigm as well as the established 'Out of Africa' model.

Archean komatiite volcanism controlled by the evolution of early continents.

PubMed

Mole, David R; Fiorentini, Marco L; Thebaud, Nicolas; Cassidy, Kevin F; McCuaig, T Campbell; Kirkland, Christopher L; Romano, Sandra S; Doublier, Michael P; Belousova, Elena A; Barnes, Stephen J; Miller, John

2014-07-15

The generation and evolution of Earth's continental crust has played a fundamental role in the development of the planet. Its formation modified the composition of the mantle, contributed to the establishment of the atmosphere, and led to the creation of ecological niches important for early life. Here we show that in the Archean, the formation and stabilization of continents also controlled the location, geochemistry, and volcanology of the hottest preserved lavas on Earth: komatiites. These magmas typically represent 50-30% partial melting of the mantle and subsequently record important information on the thermal and chemical evolution of the Archean-Proterozoic Earth. As a result, it is vital to constrain and understand the processes that govern their localization and emplacement. Here, we combined Lu-Hf isotopes and U-Pb geochronology to map the four-dimensional evolution of the Yilgarn Craton, Western Australia, and reveal the progressive development of an Archean microcontinent. Our results show that in the early Earth, relatively small crustal blocks, analogous to modern microplates, progressively amalgamated to form larger continental masses, and eventually the first cratons. This cratonization process drove the hottest and most voluminous komatiite eruptions to the edge of established continental blocks. The dynamic evolution of the early continents thus directly influenced the addition of deep mantle material to the Archean crust, oceans, and atmosphere, while also providing a fundamental control on the distribution of major magmatic ore deposits.

Archean komatiite volcanism controlled by the evolution of early continents

PubMed Central

Mole, David R.; Fiorentini, Marco L.; Thebaud, Nicolas; Cassidy, Kevin F.; McCuaig, T. Campbell; Kirkland, Christopher L.; Romano, Sandra S.; Doublier, Michael P.; Belousova, Elena A.; Barnes, Stephen J.; Miller, John

2014-01-01

The generation and evolution of Earth’s continental crust has played a fundamental role in the development of the planet. Its formation modified the composition of the mantle, contributed to the establishment of the atmosphere, and led to the creation of ecological niches important for early life. Here we show that in the Archean, the formation and stabilization of continents also controlled the location, geochemistry, and volcanology of the hottest preserved lavas on Earth: komatiites. These magmas typically represent 50–30% partial melting of the mantle and subsequently record important information on the thermal and chemical evolution of the Archean–Proterozoic Earth. As a result, it is vital to constrain and understand the processes that govern their localization and emplacement. Here, we combined Lu-Hf isotopes and U-Pb geochronology to map the four-dimensional evolution of the Yilgarn Craton, Western Australia, and reveal the progressive development of an Archean microcontinent. Our results show that in the early Earth, relatively small crustal blocks, analogous to modern microplates, progressively amalgamated to form larger continental masses, and eventually the first cratons. This cratonization process drove the hottest and most voluminous komatiite eruptions to the edge of established continental blocks. The dynamic evolution of the early continents thus directly influenced the addition of deep mantle material to the Archean crust, oceans, and atmosphere, while also providing a fundamental control on the distribution of major magmatic ore deposits. PMID:24958873

A new tephrochronology for early diverse stone tool technologies and long-distance raw material transport in the Middle to Late Pleistocene Kapthurin Formation, East Africa.

PubMed

Blegen, Nick; Jicha, Brian R; McBrearty, Sally

2018-05-09

The Middle to Late Pleistocene (780-10 ka) of East Africa records evidence of significant behavioral change, early fossils of Homo sapiens, and the dispersals of our species across and out of Africa. Studying human evolution in this time period thus requires an extensive and precise chronology relating behavioral evidence from archaeological sequences to aspects of hominin biology and evidence of past environments from fossils and geological sequences. Tephrochronology provides the chronostratigraphic resolution to achieve this through correlation and dating of volcanic ashes. The tephrochronology of the Kapthurin Formation presented here, based on tephra correlations and 40 Ar/ 39 Ar dates, provides new ages between 395.6 ± 3.5 ka and 465.3 ± 1.0 ka for nine sites showing diverse blade and Levallois methods of core reduction. These are >110 kyr older than previously known in East Africa. New 40 Ar/ 39 Ar dates provide a refined age of 222.5 ± 0.6 ka for early evidence of long-distance (166 km) obsidian transport at the Sibilo School Road Site. A tephra correlation between the Baringo and Victoria basins also provides a new date of ∼100 ka for the Middle Stone Age site of Keraswanin. By providing new and older dates for 11 sites containing several important aspects of hominin behavior and extending the chronology of the Kapthurin Formation forward by ∼130,000 years, the tephrochronology presented here contributes one of the longest and most refined chronostratigraphic frameworks of Middle through Late Pleistocene East Africa. This tephrochronology thus provides the foundation to understand the process of modern human behavioral evolution as it relates to biological and paleoenvironmental circumstances. Copyright © 2018 Elsevier Ltd. All rights reserved.

Abrasive, Silica Phytoliths and the Evolution of Thick Molar Enamel in Primates, with Implications for the Diet of Paranthropus boisei

PubMed Central

Rabenold, Diana; Pearson, Osbjorn M.

2011-01-01

Background Primates—including fossil species of apes and hominins—show variation in their degree of molar enamel thickness, a trait long thought to reflect a diet of hard or tough foods. The early hominins demonstrated molar enamel thickness of moderate to extreme degrees, which suggested to most researchers that they ate hard foods obtained on or near the ground, such as nuts, seeds, tubers, and roots. We propose an alternative hypothesis—that the amount of phytoliths in foods correlates with the evolution of thick molar enamel in primates, although this effect is constrained by a species' degree of folivory. Methodology/Principal Findings From a combination of dietary data and evidence for the levels of phytoliths in plant families in the literature, we calculated the percentage of plant foods rich in phytoliths in the diets of twelve extant primates with wide variation in their molar enamel thickness. Additional dietary data from the literature provided the percentage of each primate's diet made up of plants and of leaves. A statistical analysis of these variables showed that the amount of abrasive silica phytoliths in the diets of our sample primates correlated positively with the thickness of their molar enamel, constrained by the amount of leaves in their diet (R2 = 0.875; p<.0006). Conclusions/Significance The need to resist abrasion from phytoliths appears to be a key selective force behind the evolution of thick molar enamel in primates. The extreme molar enamel thickness of the teeth of the East African hominin Paranthropus boisei, long thought to suggest a diet comprising predominantly hard objects, instead appears to indicate a diet with plants high in abrasive silica phytoliths. PMID:22163299

New evidence on the tool-assisted hunting exhibited by chimpanzees (Pan troglodytes verus) in a savannah habitat at Fongoli, Sénégal.

PubMed

Pruetz, J D; Bertolani, P; Ontl, K Boyer; Lindshield, S; Shelley, M; Wessling, E G

2015-04-01

For anthropologists, meat eating by primates like chimpanzees (Pan troglodytes) warrants examination given the emphasis on hunting in human evolutionary history. As referential models, apes provide insight into the evolution of hominin hunting, given their phylogenetic relatedness and challenges reconstructing extinct hominin behaviour from palaeoanthropological evidence. Among chimpanzees, adult males are usually the main hunters, capturing vertebrate prey by hand. Savannah chimpanzees (P. t. verus) at Fongoli, Sénégal are the only known non-human population that systematically hunts vertebrate prey with tools, making them an important source for hypotheses of early hominin behaviour based on analogy. Here, we test the hypothesis that sex and age patterns in tool-assisted hunting (n=308 cases) at Fongoli occur and differ from chimpanzees elsewhere, and we compare tool-assisted hunting to the overall hunting pattern. Males accounted for 70% of all captures but hunted with tools less than expected based on their representation on hunting days. Females accounted for most tool-assisted hunting. We propose that social tolerance at Fongoli, along with the tool-assisted hunting method, permits individuals other than adult males to capture and retain control of prey, which is uncommon for chimpanzees. We assert that tool-assisted hunting could have similarly been important for early hominins.

Fossil evidence for the early ant evolution

NASA Astrophysics Data System (ADS)

Perrichot, Vincent; Lacau, Sébastien; Néraudeau, Didier; Nel, André

2008-02-01

Ants are one of the most studied insects in the world; and the literature devoted to their origin and evolution, systematics, ecology, or interactions with plants, fungi and other organisms is prolific. However, no consensus yet exists on the age estimate of the first Formicidae or on the origin of their eusociality. We review the fossil and biogeographical record of all known Cretaceous ants. We discuss the possible origin of the Formicidae with emphasis on the most primitive subfamily Sphecomyrminae according to its distribution and the Early Cretaceous palaeogeography. And we review the evidence of true castes and eusociality of the early ants regarding their morphological features and their manner of preservation in amber. The mid-Cretaceous amber forest from south-western France where some of the oldest known ants lived, corresponded to a moist tropical forest close to the shore with a dominance of gymnosperm trees but where angiosperms (flowering plants) were already diversified. This palaeoenvironmental reconstruction supports an initial radiation of ants in forest ground litter coincident with the rise of angiosperms, as recently proposed as an ecological explanation for their origin and successful evolution.

Pair-bonding, romantic love, and evolution: the curious case of Homo sapiens.

PubMed

Fletcher, Garth J O; Simpson, Jeffry A; Campbell, Lorne; Overall, Nickola C

2015-01-01

This article evaluates a thesis containing three interconnected propositions. First, romantic love is a "commitment device" for motivating pair-bonding in humans. Second, pair-bonding facilitated the idiosyncratic life history of hominins, helping to provide the massive investment required to rear children. Third, managing long-term pair bonds (along with family relationships) facilitated the evolution of social intelligence and cooperative skills. We evaluate this thesis by integrating evidence from a broad range of scientific disciplines. First, consistent with the claim that romantic love is an evolved commitment device, our review suggests that it is universal; suppresses mate-search mechanisms; has specific behavioral, hormonal, and neuropsychological signatures; and is linked to better health and survival. Second, we consider challenges to this thesis posed by the existence of arranged marriage, polygyny, divorce, and infidelity. Third, we show how the intimate relationship mind seems to be built to regulate and monitor relationships. Fourth, we review comparative evidence concerning links among mating systems, reproductive biology, and brain size. Finally, we discuss evidence regarding the evolutionary timing of shifts to pair-bonding in hominins. We conclude there is interdisciplinary support for the claim that romantic love and pair-bonding, along with alloparenting, played critical roles in the evolution of Homo sapiens. © The Author(s) 2014.

Comparative morphological and morphometric description of the hominin calvaria from Bukuran (Sangiran, Central Java, Indonesia).

PubMed

Grimaud-Hervé, Dominique; Widianto, Harry; Détroit, Florent; Sémah, François

2012-11-01

We describe the hominin skull (called here "Bukuran") discovered in the lower Kabuh (or "Bapang") series near Sendangbusik, from the Bukuran area in the Sangiran dome. The fossil, heavily mineralized, consists of the parieto-occipital and the left temporal, and the frontal bones. When combined, those two cranial parts represent a rather complete and well-preserved calvaria. Its stratigraphic position was established after the discovery. A detailed description is presented of the morphological and metric features of the Bukuran calvaria, and comparisons are made with Asian Homo erectus from Indonesia and China. The estimated cranial capacity of Bukuran, the general shape of its cranial vault, its ectocranial structures, and its morphological and metrical characters are in the range of Asian Homo erectus, and show clear affinities with other Indonesian members of the species. We discuss the evolutionary status of the Bukuran calvaria and its implication for hominin history on Java. Copyright © 2012 Elsevier Ltd. All rights reserved.

Intergroup cannibalism in the European Early Pleistocene: the range expansion and imbalance of power hypotheses.

PubMed

Saladié, Palmira; Huguet, Rosa; Rodríguez-Hidalgo, Antonio; Cáceres, Isabel; Esteban-Nadal, Montserrat; Arsuaga, Juan Luis; Bermúdez de Castro, José María; Carbonell, Eudald

2012-11-01

In this paper, we compare cannibalism in chimpanzees, modern humans, and in archaeological cases with cannibalism inferred from evidence from the Early Pleistocene assemblage of level TD6 of Gran Dolina (Sierra de Atapuerca, Spain). The cannibalism documented in level TD6 mainly involves the consumption of infants and other immature individuals. The human induced modifications on Homo antecessor and deer remains suggest that butchering processes were similar for both taxa, and the remains were discarded on the living floor in the same way. This finding implies that a group of hominins that used the Gran Dolina cave periodically hunted and consumed individuals from another group. However, the age distribution of the cannibalized hominins in the TD6 assemblage is not consistent with that from other cases of exo-cannibalism by human/hominin groups. Instead, it is similar to the age profiles seen in cannibalism associated with intergroup aggression in chimpanzees. For this reason, we use an analogy with chimpanzees to propose that the TD6 hominins mounted low-risk attacks on members of other groups to defend access to resources within their own territories and to try and expand their territories at the expense of neighboring groups. Copyright © 2012 Elsevier Ltd. All rights reserved.

The role of carnivores and their relationship to hominin settlements in the TD6-2 level from Gran Dolina (Sierra de Atapuerca, Spain)

NASA Astrophysics Data System (ADS)

Saladié, Palmira; Rodríguez-Hidalgo, Antonio; Huguet, Rosa; Cáceres, Isabel; Díez, Carlos; Vallverdú, Josep; Canals, Antoni; Soto, María; Santander, Boris; Bermúdez de Castro, José María; Arsuaga, Juan Luis; Carbonell, Eudald

2014-06-01

Pleistocene level TD6-2 of the Gran Dolina site (Sierra de Atapuerca, Spain) is the result of anthropogenic accumulation. Hominin groups occupied the cave as a home base, where they brought in, butchered and consumed the carcasses of ungulates and other hominins. In this paper, we reassess the role of carnivores in the formation and/or modification of the assemblage. We employed different methods to explore the scenario in which the TD6-2 assemblage was formed: (1) identifying the actor responsible for tooth marks; (2) determining the frequency of carnivore tooth marks and their distribution; (3) identifying the co-occurrence of modifications (butchering marks and carnivore tooth marks); (4) calculating the percentage of change and the epiphysis to shaft ratio. Carnivore tooth marks are scarce, as is the co-occurrence of hominin and carnivore modifications. However, not all tooth marks have been attributed to a particular agent due to the high equifinality between human and carnivore tooth marks. For these reasons, the frequency of tooth marks and the co-occurrence of modifications have been of little help in interpreting the role of carnivores. Axial skeletal remains and the epiphyses of the long bones are in large part missing. The percentage of change and the epiphysis to shaft ratio suggest moderate carnivore ravaging activity. Our data indicate that the role of carnivores in TD6-2 seems to have had an impact on the original assemblage after hominins had extracted a large amount of nutrients from the carcasses. Cannibalized hominin remains showed no carnivore tooth marks and have a greater presence of low survival bones compared to ungulate remains. These findings point to a different taphonomic history suggesting that TD6-2 represents a succession of settlements having different characteristics.

Multiplicity in Early Stellar Evolution

NASA Astrophysics Data System (ADS)

Reipurth, B.; Clarke, C. J.; Boss, A. P.; Goodwin, S. P.; Rodríguez, L. F.; Stassun, K. G.; Tokovinin, A.; Zinnecker, H.

Observations from optical to centimeter wavelengths have demonstrated that multiple systems of two or more bodies is the norm at all stellar evolutionary stages. Multiple systems are widely agreed to result from the collapse and fragmentation of cloud cores, despite the inhibiting influence of magnetic fields. Surveys of class 0 protostars with millimeter interferometers have revealed a very high multiplicity frequency of about 2/3, even though there are observational difficulties in resolving close protobinaries, thus supporting the possibility that all stars could be born in multiple systems. Near-infrared adaptive optics observations of class I protostars show a lower binary frequency relative to the class 0 phase, a declining trend that continues through the class II/III stages to the field population. This loss of companions is a natural consequence of dynamical interplay in small multiple systems, leading to ejection of members. We discuss observational consequences of this dynamical evolution, and its influence on circumstellar disks, and we review the evolution of circumbinary disks and their role in defining binary mass ratios. Special attention is paid to eclipsing PMS binaries, which allow for observational tests of evolutionary models of early stellar evolution. Many stars are born in clusters and small groups, and we discuss how interactions in dense stellar environments can significantly alter the distribution of binary separations through dissolution of wider binaries. The binaries and multiples we find in the field are the survivors of these internal and external destructive processes, and we provide a detailed overview of the multiplicity statistics of the field, which form a boundary condition for all models of binary evolution. Finally, we discuss various formation mechanisms for massive binaries, and the properties of massive trapezia.

A ~600 kyr duration Early Pleistocene record from the West Turkana (Kenya) HSPDP drill site: elemental XRF variability to reconstruct climate change in Turkana Boy's backyard

NASA Astrophysics Data System (ADS)

Stockhecke, M.; Beck, C. C.; Brown, E. T.; Cohen, A.; Deino, A. L.; Feibel, C. S.; Sier, M.

2015-12-01

Outcrops in the Kenyan and Ethiopian rift valleys document repeated occurrences of freshwater lakes and wooded landscapes over the past 4 million years at locations that are currently seasonally-dry savanna. Studies of the rich fossil records, in combination with outcropping lacustrine sequences, led to major breakthroughs in our knowledge of driving factors in human evolution. However, study of continuous drill core from ancient lake basins provides a basis for to unravel East African climate dynamics in an unseen fashion. The Hominin Sites and Paleolakes Drilling Project (HSPDP), and the related Olorgesailie Drilling Project, recovered ~2 km of drill core since 2012. A major project goal is characterization of East African paleoclimate in order to evaluate its impact on hominin evolution. XRF core scanning data provide a means of evaluating records of past environmental conditions continuously and at high resolution. However, the HSPDP records contain complex lithologies reflecting repeated episodes of inundation and desiccation of the lake basins. Nevertheless, careful data evaluation based on detailed lithostratigraphy, which includes smear-slide microscopic analyses and X-radiographic images, allows disentanglement of complex signals and robust identification of continuous sequences for any cyclostratigraphic and statistical analysis. At the HSPDP Turkana Basin site a 175.6 m-long core the covers the Early Pleistocene time window during which hominids first expanded out of Africa and marine records document reorganization of tropical climate and the development of the strong Walker circulation. This drill site carries particular interest as it is located in only 2.5 km from the location of one of the most complete hominin skeletons ever recovered (Turkana Boy). Here we present a methodological approach to address the highly variable lithostratigraphy of the East African records to establish comprehensive and environmentally meaningful paleoclimate timeseries

A geometric morphometric analysis of hominin upper premolars. Shape variation and morphological integration.

PubMed

Gómez-Robles, Aida; Martinón-Torres, María; Bermúdez de Castro, José María; Prado-Simón, Leyre; Arsuaga, Juan Luis

2011-12-01

This paper continues the series of articles initiated in 2006 that analyse hominin dental crown morphology by means of geometric morphometric techniques. The detailed study of both upper premolar occlusal morphologies in a comprehensive sample of hominin fossils, including those coming from the Gran Dolina-TD6 and Sima de los Huesos sites from Atapuerca, Spain, complement previous works on lower first and second premolars and upper first molars. A morphological gradient consisting of the change from asymmetric to symmetric upper premolars and a marked reduction of the lingual cusp in recent Homo species has been observed in both premolars. Although percentages of correct classification based on upper premolar morphologies are not very high, significant morphological differences between Neanderthals (and European middle Pleistocene fossils) and modern humans have been identified, especially in upper second premolars. The study of morphological integration between premolar morphologies reveals significant correlations that are weaker between upper premolars than between lower ones and significant correlations between antagonists. These results have important implications for understanding the genetic and functional factors underlying dental phenotypic variation and covariation. Copyright © 2011 Elsevier Ltd. All rights reserved.

Early evolution of Tubulogenerina during the Paleogene of Europe

USGS Publications Warehouse

Gibson, T.G.; Barbin, V.; Poignant, A.; Sztrakos, K.

1991-01-01

The early evolution of Tubulogenerina took place in Europe where eight species occur in lower Eocene to uppermost Oligocene or lower Miocene strata. Species diversity within Tubulogenerina dropped significantly in the early Oligocne; only a single species persisted from the late Eocene, and it became extinct before the end of the early Oligocene. Morphologic changes during the European phylogeny of Tubulogenerina include (1) the development of costate and more complex tubulopore ornamentation, and (2) the change from a single elongated apertural slit with a single toothplate to multiple apertures and toothplates. Three new Tubulogenerina species are described. -from Authors

Hominin reactions to herbivore distribution in the Lower Palaeolithic of the Southern Levant

NASA Astrophysics Data System (ADS)

Devès, Maud; Sturdy, Derek; Godet, Nan; King, Geoffrey C. P.; Bailey, Geoffrey N.

2014-07-01

We explore the relationship between the edaphic potential of soils and the mineral properties of the underlying geology as a means of mapping the differential productivity of different areas of the Pleistocene landscape for large herbivores. These factors strongly control the health of grazing animals irrespective of the particular types of vegetation growing on them, but they have generally been neglected in palaeoanthropological studies in favour of a more general emphasis on water and vegetation, which provide an incomplete picture. Taking the Carmel-Galilee-Golan region as an example, we show how an understanding of edaphic potential provides insight into how animals might have exploited the environment. In order to simplify the analysis, we concentrate on the Lower Palaeolithic period and the very large animals that dominate the archaeofaunal assemblages of this period. Topography and the ability of soils to retain water also contribute to the differential productivity and accessibility of different regions and to patterns of seasonal movements of the animals, which are essential to ensure a supply of healthy fodder throughout the year, especially for large animals such as elephants, which require substantial regions of good grazing and browsing. Other animals migrating in groups have similar needs. The complex topography of the Southern Levant with frequent sudden and severe changes in gradient, and a wide variety of landforms including rocky outcrops, cliffs, gorges, and ridges, places major limits on these patterns of seasonal movements. We develop methods of mapping these variables, based on the geology and our substantial field experience, in order to create a framework of landscape variation that can be compared with the locations and contents of archaeological sites to suggest ways in which early hominins used the variable features of the landscape to target animal prey, and extend the analysis to the consideration of smaller mammals that were exploited

Open Listening: Creative Evolution in Early Childhood Settings

ERIC Educational Resources Information Center

Davies, Bronwyn

2011-01-01

This article sketches out a philosophy and practice of open listening, linking open listening to Bergson's (1998) concept of creative evolution. I draw on examples of small children at play from a variety of sources, including Reggio-Emilia-inspired preschools in Sweden. The article offers a challenge to early childhood educators to listen and to…

Functional mastery of percussive technology in nut-cracking and stone-flaking actions: experimental comparison and implications for the evolution of the human brain

PubMed Central

Bril, Blandine; Smaers, Jeroen; Steele, James; Rein, Robert; Nonaka, Tetsushi; Dietrich, Gilles; Biryukova, Elena; Hirata, Satoshi; Roux, Valentine

2012-01-01

Various authors have suggested behavioural similarities between tool use in early hominins and chimpanzee nut cracking, where nut cracking might be interpreted as a precursor of more complex stone flaking. In this paper, we bring together and review two separate strands of research on chimpanzee and human tool use and cognitive abilities. Firstly, and in the greatest detail, we review our recent experimental work on behavioural organization and skill acquisition in nut-cracking and stone-knapping tasks, highlighting similarities and differences between the two tasks that may be informative for the interpretation of stone tools in the early archaeological record. Secondly, and more briefly, we outline a model of the comparative neuropsychology of primate tool use and discuss recent descriptive anatomical and statistical analyses of anthropoid primate brain evolution, focusing on cortico-cerebellar systems. By juxtaposing these two strands of research, we are able to identify unsolved problems that can usefully be addressed by future research in each of these two research areas. PMID:22106427

Vestibular evidence for the evolution of aquatic behaviour in early cetaceans.

PubMed

Spoor, F; Bajpai, S; Hussain, S T; Kumar, K; Thewissen, J G M

2002-05-09

Early cetaceans evolved from terrestrial quadrupeds to obligate swimmers, a change that is traditionally studied by functional analysis of the postcranial skeleton. Here we assess the evolution of cetacean locomotor behaviour from an independent perspective by looking at the semicircular canal system, one of the main sense organs involved in neural control of locomotion. Extant cetaceans are found to be unique in that their canal arc size, corrected for body mass, is approximately three times smaller than in other mammals. This reduces the sensitivity of the canal system, most plausibly to match the fast body rotations that characterize cetacean behaviour. Eocene fossils show that the new sensory regime, incompatible with terrestrial competence, developed quickly and early in cetacean evolution, as soon as the taxa are associated with marine environments. Dedicated agile swimming of cetaceans thus appeared to have originated as a rapid and fundamental shift in locomotion rather than as the gradual transition suggested by postcranial evidence. We hypothesize that the unparalleled modification of the semicircular canal system represented a key 'point of no return' event in early cetacean evolution, leading to full independence from life on land.

Early dynamical evolution of substructured stellar clusters

NASA Astrophysics Data System (ADS)

Dorval, Julien; Boily, Christian

2015-08-01

It is now widely accepted that stellar clusters form with a high level of substructure (Kuhn et al. 2014, Bate 2009), inherited from the molecular cloud and the star formation process. Evidence from observations and simulations also indicate the stars in such young clusters form a subvirial system (Kirk et al. 2007, Maschberger et al. 2010). The subsequent dynamical evolution can cause important mass loss, ejecting a large part of the birth population in the field. It can also imprint the stellar population and still be inferred from observations of evolved clusters. Nbody simulations allow a better understanding of these early twists and turns, given realistic initial conditions. Nowadays, substructured, clumpy young clusters are usually obtained through pseudo-fractal growth (Goodwin et al. 2004) and velocity inheritance. Such models are visually realistics and are very useful, they are however somewhat artificial in their velocity distribution. I introduce a new way to create clumpy initial conditions through a "Hubble expansion" which naturally produces self consistent clumps, velocity-wise. A velocity distribution analysis shows the new method produces realistic models, consistent with the dynamical state of the newly created cores in hydrodynamic simulation of cluster formation (Klessen & Burkert 2000). I use these initial conditions to investigate the dynamical evolution of young subvirial clusters, up to 80000 stars. I find an overall soft evolution, with hierarchical merging leading to a high level of mass segregation. I investigate the influence of the mass function on the fate of the cluster, specifically on the amount of mass loss induced by the early violent relaxation. Using a new binary detection algorithm, I also find a strong processing of the native binary population.

A New Tephrochronology for Early Diverse Stone Tool Technologies and Long-Distance Raw Material Transport in the Middle-Late Pleistocene Kapthurin Formation, East Africa.

NASA Astrophysics Data System (ADS)

Blegen, N.; Jicha, B.

2017-12-01

The Middle to Late Pleistocene (780-10 ka) of East Africa records significant behavioral change, the earliest fossils of Homo sapiens and the dispersals of our species across and out of Africa. Studying human evolution in the Middle to Late Pleistocene thus requires an extensive and precise chronology relating the appearances of various behaviors preserved in archaeological sequences to aspects of hominin biology and evidence of past environments preserved in the fossils and geological sequences. Tephrochronology provides the chronostratigraphic resolution to achieve this through correlation and dating of volcanic ashes. The tephrochronology of the Kapthurin Formation presented here, based on tephra correlations and 40Ar/ 39Ar dates, provides new ages between 396.3 ± 3.4 ka and 465.3 ± 1.0 ka for nine sites showing some of the earliest evidence of diverse blade and Levallois methods of core reduction. These are >110 kyr older than previously known in East Africa. New 40Ar/ 39Ar dates provide a refined age of 222.5 ± 0.6 ka for early evidence of long-distance obsidian transport at the Sibilo School Road Site. Long-distance tephra correlation between the Baringo and Lake Victoria basins also provides a new date of 100 ka for the Middle Stone Age site of Keraswanin. By providing new or older dates for 11 sites containing several important aspects of hominin behavior and extending the chronology of the Kapthurin Formation forward by 130,000 years, the tephrochronology presented here contributes one of the longest and most refined chronostratigraphic frameworks relevant to modern human evolution. In conjunction with recent archaeological and paleoenvironmental data, this tephrochronology provides the foundation to understand the process of modern human behavioral evolution through the East African Middle and Late Pleistocene as it relates to biological and paleoenvironmental circumstances.

Exploring the Potential of Laser Ablation Carbon Isotope Analysis for Examining Ecology during the Ontogeny of Middle Pleistocene Hominins from Sima de los Huesos (Northern Spain).

PubMed

Garcia, Nuria; Feranec, Robert S; Passey, Benjamin H; Cerling, Thure E; Arsuaga, Juan Luis

2015-01-01

Laser ablation of tooth enamel was used to analyze stable carbon isotope compositions of teeth of hominins, red deer, and bears from middle Pleistocene sites in the Sierra de Atapuerca in northern Spain, to investigate the possibility that this technique could be used as an additional tool to identify periods of physiological change that are not detectable as changes in tooth morphology. Most of the specimens were found to have minimal intra-tooth variation in carbon isotopes (< 2.3‰), suggesting isotopically uniform diets through time and revealing no obvious periods of physiological change. However, one of the two sampled hominin teeth displayed a temporal carbon isotope shift (3.2‰) that was significantly greater than observed for co-occurring specimens. The δ13C value of this individual averaged about -16‰ early in life, and -13‰ later in life. This isotopic change occurred on the canine crown about 4.2 mm from the root, which corresponds to an approximate age of two to four years old in modern humans. Our dataset is perforce small owing to the precious nature of hominid teeth, but it demonstrates the potential utility of the intra-tooth isotope profile method for extracting ontogenetic histories of human ancestors.

Exploring the Potential of Laser Ablation Carbon Isotope Analysis for Examining Ecology during the Ontogeny of Middle Pleistocene Hominins from Sima de los Huesos (Northern Spain)

PubMed Central

Garcia, Nuria; Feranec, Robert S.; Passey, Benjamin H.; Cerling, Thure E.; Arsuaga, Juan Luis

2015-01-01

Laser ablation of tooth enamel was used to analyze stable carbon isotope compositions of teeth of hominins, red deer, and bears from middle Pleistocene sites in the Sierra de Atapuerca in northern Spain, to investigate the possibility that this technique could be used as an additional tool to identify periods of physiological change that are not detectable as changes in tooth morphology. Most of the specimens were found to have minimal intra-tooth variation in carbon isotopes (< 2.3‰), suggesting isotopically uniform diets through time and revealing no obvious periods of physiological change. However, one of the two sampled hominin teeth displayed a temporal carbon isotope shift (3.2‰) that was significantly greater than observed for co-occurring specimens. The δ13C value of this individual averaged about -16‰ early in life, and -13‰ later in life. This isotopic change occurred on the canine crown about 4.2 mm from the root, which corresponds to an approximate age of two to four years old in modern humans. Our dataset is perforce small owing to the precious nature of hominid teeth, but it demonstrates the potential utility of the intra-tooth isotope profile method for extracting ontogenetic histories of human ancestors. PMID:26673156

Sedimentary Basin Structure of the Hadar Formation's Lacustrine-Dominated Depocenter (Ledi-Geraru, Afar, Ethiopia) and its Relevance for Investigating Hominin Paleoenvironments

NASA Astrophysics Data System (ADS)

Dimaggio, E. N.; Campisano, C. J.; Arrowsmith, J. R.; Dupont-Nivet, G.; Johnson, R. A.; Warren, M. B.

2008-12-01

Sedimentary sequences preserved in East African rift basins record the long-term response of past depositional environments to climatic and tectonic forcing. Motivations for recent field investigations at the Ledi-Geraru site, part of the greater Hadar sedimentary basin in the Afar region of Ethiopia, stem from a need to characterize local basin structure and expand and refine interpretations of the complex mid-late Pliocene history of local and regional-scale landscape change during a time of critical importance for understanding hominin evolution. Detailed geologic mapping (1:7,000), measured stratigraphic sections, and seismic reflection surveys provide the datasets necessary for basin evaluation. The Ledi-Geraru sedimentary sequence (>250m thick) exposes nearly the entirety of the hominin-bearing Hadar Formation of west- central Afar. Both primary unmodified lake deposits and intervals modified by subsequent subaerial exposure and pedogenesis are well-exposed. The lacustrine-dominated signature is indicated by the prevalence of laminated silty clays that contain leaf impressions, fish scales, and gastropod shells, undisturbed laminated diatomite and clays, and pedogenically modified diatomaceous silts. The sequence is generally flat lying, with low bedding dips ranging from 0-2° NNW to <1° NNE and minor NNW trending faults with <5 m vertical offset. Whereas coeval fluvio-lacustrine sediments associated with hominin and archaeological sites west of Ledi-Geraru (e.g., Hadar and Gona) are marked by comparatively slow and episodic sedimentation, sedimentation rates in the Ledi-Geraru sequence are extremely high and consistent, on the order of ~0.9-1.0mm/yr. Laterally extensive tephra marker beds and paleomagnetic records provide excellent age control for sedimentation rate estimates and correlation to nearby fossil-rich sequences. As the Hadar basin sediments preserve a rich paleoanthropologic and archaeological record, this work provides the geologic framework

Human evolution. Evolution of early Homo: an integrated biological perspective.

PubMed

Antón, Susan C; Potts, Richard; Aiello, Leslie C

2014-07-04

Integration of evidence over the past decade has revised understandings about the major adaptations underlying the origin and early evolution of the genus Homo. Many features associated with Homo sapiens, including our large linear bodies, elongated hind limbs, large energy-expensive brains, reduced sexual dimorphism, increased carnivory, and unique life history traits, were once thought to have evolved near the origin of the genus in response to heightened aridity and open habitats in Africa. However, recent analyses of fossil, archaeological, and environmental data indicate that such traits did not arise as a single package. Instead, some arose substantially earlier and some later than previously thought. From ~2.5 to 1.5 million years ago, three lineages of early Homo evolved in a context of habitat instability and fragmentation on seasonal, intergenerational, and evolutionary time scales. These contexts gave a selective advantage to traits, such as dietary flexibility and larger body size, that facilitated survival in shifting environments. Copyright © 2014, American Association for the Advancement of Science.

Niche partitioning in sympatric Gorilla and Pan from Cameroon: implications for life history strategies and for reconstructing the evolution of hominin life history.

PubMed

Macho, Gabriele A; Lee-Thorp, Julia A

2014-01-01

Factors influencing the hominoid life histories are poorly understood, and little is known about how ecological conditions modulate the pace of their development. Yet our limited understanding of these interactions underpins life history interpretations in extinct hominins. Here we determined the synchronisation of dental mineralization/eruption with brain size in a 20th century museum collection of sympatric Gorilla gorilla and Pan troglodytes from Central Cameroon. Using δ13C and δ15N of individuals' hair, we assessed whether and how differences in diet and habitat use may have impacted on ape development. The results show that, overall, gorilla hair δ13C and δ15N values are more variable than those of chimpanzees, and that gorillas are consistently lower in δ13C and δ15N compared to chimpanzees. Within a restricted, isotopically-constrained area, gorilla brain development appears delayed relative to dental mineralization/eruption [or dental development is accelerated relative to brains]: only about 87.8% of adult brain size is attained by the time first permanent molars come into occlusion, whereas it is 92.3% in chimpanzees. Even when M1s are already in full functional occlusion, gorilla brains lag behind those of chimpanzee (91% versus 96.4%), relative to tooth development. Both bootstrap analyses and stable isotope results confirm that these results are unlikely due to sampling error. Rather, δ15N values imply that gorillas are not fully weaned (physiologically mature) until well after M1 are in full functional occlusion. In chimpanzees the transition from infant to adult feeding appears (a) more gradual and (b) earlier relative to somatic development. Taken together, the findings are consistent with life history theory that predicts delayed development when non-density dependent mortality is low, i.e. in closed habitats, and with the "risk aversion" hypothesis for frugivorous species as a means to avert starvation. Furthermore, the results highlight

Niche Partitioning in Sympatric Gorilla and Pan from Cameroon: Implications for Life History Strategies and for Reconstructing the Evolution of Hominin Life History

PubMed Central

Macho, Gabriele A.; Lee-Thorp, Julia A.

2014-01-01

Factors influencing the hominoid life histories are poorly understood, and little is known about how ecological conditions modulate the pace of their development. Yet our limited understanding of these interactions underpins life history interpretations in extinct hominins. Here we determined the synchronisation of dental mineralization/eruption with brain size in a 20th century museum collection of sympatric Gorilla gorilla and Pan troglodytes from Central Cameroon. Using δ13C and δ15N of individuals’ hair, we assessed whether and how differences in diet and habitat use may have impacted on ape development. The results show that, overall, gorilla hair δ13C and δ15N values are more variable than those of chimpanzees, and that gorillas are consistently lower in δ13C and δ15N compared to chimpanzees. Within a restricted, isotopically-constrained area, gorilla brain development appears delayed relative to dental mineralization/eruption [or dental development is accelerated relative to brains]: only about 87.8% of adult brain size is attained by the time first permanent molars come into occlusion, whereas it is 92.3% in chimpanzees. Even when M1s are already in full functional occlusion, gorilla brains lag behind those of chimpanzee (91% versus 96.4%), relative to tooth development. Both bootstrap analyses and stable isotope results confirm that these results are unlikely due to sampling error. Rather, δ15N values imply that gorillas are not fully weaned (physiologically mature) until well after M1 are in full functional occlusion. In chimpanzees the transition from infant to adult feeding appears (a) more gradual and (b) earlier relative to somatic development. Taken together, the findings are consistent with life history theory that predicts delayed development when non-density dependent mortality is low, i.e. in closed habitats, and with the “risk aversion” hypothesis for frugivorous species as a means to avert starvation. Furthermore, the results

Triadic (ecological, neural, cognitive) niche construction: a scenario of human brain evolution extrapolating tool use and language from the control of reaching actions

PubMed Central

Iriki, Atsushi; Taoka, Miki

2012-01-01

Hominin evolution has involved a continuous process of addition of new kinds of cognitive capacity, including those relating to manufacture and use of tools and to the establishment of linguistic faculties. The dramatic expansion of the brain that accompanied additions of new functional areas would have supported such continuous evolution. Extended brain functions would have driven rapid and drastic changes in the hominin ecological niche, which in turn demanded further brain resources to adapt to it. In this way, humans have constructed a novel niche in each of the ecological, cognitive and neural domains, whose interactions accelerated their individual evolution through a process of triadic niche construction. Human higher cognitive activity can therefore be viewed holistically as one component in a terrestrial ecosystem. The brain's functional characteristics seem to play a key role in this triadic interaction. We advance a speculative argument about the origins of its neurobiological mechanisms, as an extension (with wider scope) of the evolutionary principles of adaptive function in the animal nervous system. The brain mechanisms that subserve tool use may bridge the gap between gesture and language—the site of such integration seems to be the parietal and extending opercular cortices. PMID:22106423

Triadic (ecological, neural, cognitive) niche construction: a scenario of human brain evolution extrapolating tool use and language from the control of reaching actions.

PubMed

Iriki, Atsushi; Taoka, Miki

2012-01-12

Hominin evolution has involved a continuous process of addition of new kinds of cognitive capacity, including those relating to manufacture and use of tools and to the establishment of linguistic faculties. The dramatic expansion of the brain that accompanied additions of new functional areas would have supported such continuous evolution. Extended brain functions would have driven rapid and drastic changes in the hominin ecological niche, which in turn demanded further brain resources to adapt to it. In this way, humans have constructed a novel niche in each of the ecological, cognitive and neural domains, whose interactions accelerated their individual evolution through a process of triadic niche construction. Human higher cognitive activity can therefore be viewed holistically as one component in a terrestrial ecosystem. The brain's functional characteristics seem to play a key role in this triadic interaction. We advance a speculative argument about the origins of its neurobiological mechanisms, as an extension (with wider scope) of the evolutionary principles of adaptive function in the animal nervous system. The brain mechanisms that subserve tool use may bridge the gap between gesture and language--the site of such integration seems to be the parietal and extending opercular cortices.

Island Rule, quantitative genetics and brain–body size evolution in Homo floresiensis

PubMed Central

2017-01-01

Colonization of islands often activate a complex chain of adaptive events that, over a relatively short evolutionary time, may drive strong shifts in body size, a pattern known as the Island Rule. It is arguably difficult to perform a direct analysis of the natural selection forces behind such a change in body size. Here, we used quantitative evolutionary genetic models, coupled with simulations and pattern-oriented modelling, to analyse the evolution of brain and body size in Homo floresiensis, a diminutive hominin species that appeared around 700 kya and survived up to relatively recent times (60–90 kya) on Flores Island, Indonesia. The hypothesis of neutral evolution was rejected in 97% of the simulations, and estimated selection gradients are within the range found in living natural populations. We showed that insularity may have triggered slightly different evolutionary trajectories for body and brain size, which means explaining the exceedingly small cranial volume of H. floresiensis requires additional selective forces acting on brain size alone. Our analyses also support previous conclusions that H. floresiensis may be most likely derived from an early Indonesian H. erectus, which is coherent with currently accepted biogeographical scenario for Homo expansion out of Africa. PMID:28637851

Island Rule, quantitative genetics and brain-body size evolution in Homo floresiensis.

PubMed

Diniz-Filho, José Alexandre Felizola; Raia, Pasquale

2017-06-28

Colonization of islands often activate a complex chain of adaptive events that, over a relatively short evolutionary time, may drive strong shifts in body size, a pattern known as the Island Rule. It is arguably difficult to perform a direct analysis of the natural selection forces behind such a change in body size. Here, we used quantitative evolutionary genetic models, coupled with simulations and pattern-oriented modelling, to analyse the evolution of brain and body size in Homo floresiensis , a diminutive hominin species that appeared around 700 kya and survived up to relatively recent times (60-90 kya) on Flores Island, Indonesia. The hypothesis of neutral evolution was rejected in 97% of the simulations, and estimated selection gradients are within the range found in living natural populations. We showed that insularity may have triggered slightly different evolutionary trajectories for body and brain size, which means explaining the exceedingly small cranial volume of H. floresiensis requires additional selective forces acting on brain size alone. Our analyses also support previous conclusions that H. floresiensis may be most likely derived from an early Indonesian H. erectus , which is coherent with currently accepted biogeographical scenario for Homo expansion out of Africa. © 2017 The Author(s).

Mechanisms and causes of wear in tooth enamel: implications for hominin diets

PubMed Central

Lucas, Peter W.; Omar, Ridwaan; Al-Fadhalah, Khaled; Almusallam, Abdulwahab S.; Henry, Amanda G.; Michael, Shaji; Thai, Lidia Arockia; Watzke, Jörg; Strait, David S.; Atkins, Anthony G.

2013-01-01

The wear of teeth is a major factor limiting mammalian lifespans in the wild. One method of describing worn surfaces, dental microwear texture analysis, has proved powerful for reconstructing the diets of extinct vertebrates, but has yielded unexpected results in early hominins. In particular, although australopiths exhibit derived craniodental features interpreted as adaptations for eating hard foods, most do not exhibit microwear signals indicative of this diet. However, no experiments have yet demonstrated the fundamental mechanisms and causes of this wear. Here, we report nanowear experiments where individual dust particles, phytoliths and enamel chips were slid across a flat enamel surface. Microwear features produced were influenced strongly by interacting mechanical properties and particle geometry. Quartz dust was a rigid abrasive, capable of fracturing and removing enamel pieces. By contrast, phytoliths and enamel chips deformed during sliding, forming U-shaped grooves or flat troughs in enamel, without tissue loss. Other plant tissues seem too soft to mark enamel, acting as particle transporters. We conclude that dust has overwhelming importance as a wear agent and that dietary signals preserved in dental microwear are indirect. Nanowear studies should resolve controversies over adaptive trends in mammals like enamel thickening or hypsodonty that delay functional dental loss. PMID:23303220

Mechanisms and causes of wear in tooth enamel: implications for hominin diets.

PubMed

Lucas, Peter W; Omar, Ridwaan; Al-Fadhalah, Khaled; Almusallam, Abdulwahab S; Henry, Amanda G; Michael, Shaji; Thai, Lidia Arockia; Watzke, Jörg; Strait, David S; Atkins, Anthony G

2013-03-06

The wear of teeth is a major factor limiting mammalian lifespans in the wild. One method of describing worn surfaces, dental microwear texture analysis, has proved powerful for reconstructing the diets of extinct vertebrates, but has yielded unexpected results in early hominins. In particular, although australopiths exhibit derived craniodental features interpreted as adaptations for eating hard foods, most do not exhibit microwear signals indicative of this diet. However, no experiments have yet demonstrated the fundamental mechanisms and causes of this wear. Here, we report nanowear experiments where individual dust particles, phytoliths and enamel chips were slid across a flat enamel surface. Microwear features produced were influenced strongly by interacting mechanical properties and particle geometry. Quartz dust was a rigid abrasive, capable of fracturing and removing enamel pieces. By contrast, phytoliths and enamel chips deformed during sliding, forming U-shaped grooves or flat troughs in enamel, without tissue loss. Other plant tissues seem too soft to mark enamel, acting as particle transporters. We conclude that dust has overwhelming importance as a wear agent and that dietary signals preserved in dental microwear are indirect. Nanowear studies should resolve controversies over adaptive trends in mammals like enamel thickening or hypsodonty that delay functional dental loss.

Enhanced transcription and translation in clay hydrogel and implications for early life evolution

PubMed Central

Yang, Dayong; Peng, Songming; Hartman, Mark R.; Gupton-Campolongo, Tiffany; Rice, Edward J.; Chang, Anna Kathryn; Gu, Zi; Lu, G. Q. (Max); Luo, Dan

2013-01-01

In most contemporary life forms, the confinement of cell membranes provides localized concentration and protection for biomolecules, leading to efficient biochemical reactions. Similarly, confinement may have also played an important role for prebiotic compartmentalization in early life evolution when the cell membrane had not yet formed. It remains an open question how biochemical reactions developed without the confinement of cell membranes. Here we mimic the confinement function of cells by creating a hydrogel made from geological clay minerals, which provides an efficient confinement environment for biomolecules. We also show that nucleic acids were concentrated in the clay hydrogel and were protected against nuclease, and that transcription and translation reactions were consistently enhanced. Taken together, our results support the importance of localized concentration and protection of biomolecules in early life evolution, and also implicate a clay hydrogel environment for biochemical reactions during early life evolution. PMID:24196527

Palaeohydrological corridors for hominin dispersals in the Middle East ∼250-70,000 years ago

NASA Astrophysics Data System (ADS)

Breeze, Paul S.; Groucutt, Huw S.; Drake, Nick A.; White, Tom S.; Jennings, Richard P.; Petraglia, Michael D.

2016-07-01

The timing and extent of palaeoenvironmental connections between northeast Africa, the Levant and the Arabian Peninsula during the Middle and Late Pleistocene are critical to debates surrounding dispersals of hominins, including movements of Homo sapiens out of Africa. Although there is evidence that synchronous episodes of climatic amelioration during the late Middle and Late Pleistocene may have allowed connections to form between northern Africa and western Asia, a number of palaeoclimate models indicate the continued existence of an arid barrier between northern Arabia and the Levant. Here we evaluate the palaeoenvironmental setting for hominin dispersals between, and within, northeast Africa and southwest Asia during Marine Isotope Stages (MIS) 7-5 using reconstructions of surface freshwater availability as an environmental proxy. We use remotely sensed data to map palaeohydrological features (lakes, wetlands and rivers) across the presently hyper-arid areas of northern Arabia and surrounding regions, integrating these results with palaeoclimate models, palaeoenvironmental proxy data and absolute dating to determine when these features were active. Our analyses suggest limited potential for dispersals during MIS 7 and 6, but indicate the formation of a palaeohydrological corridor (the 'Tabuk Corridor') between the Levant and the Arabian interior during the MIS 6-5e glacial-interglacial transition and during MIS 5e. A recurrence of this corridor, following a slightly different route, also occurred during MIS 5a. These palaeohydrological and terrestrial data can be used to establish when proposed routes for hominin dispersals became viable. Furthermore, the distribution of Arabian archaeological sites with affinities to Levantine assemblages, some of which are associated with Homo sapiens fossils, and the relative density of Middle Palaeolithic assemblages within the Tabuk Corridor, are consistent with it being utilised for dispersals at various times.

MEVTV Workshop on Early Tectonic and Volcanic Evolution of Mars

NASA Technical Reports Server (NTRS)

Frey, H. (Editor)

1988-01-01

Although not ignored, the problems of the early tectonic and volcanic evolution of Mars have generally received less attention than those later in the evolution of the planet. Specifically, much attention was devoted to the evolution of the Tharsis region of Mars and to the planet itself at the time following the establishment of this major tectonic and volcanic province. By contrast, little attention was directed at fundamental questions, such as the conditions that led to the development of Tharsis and the cause of the basic fundamental dichotomy of the Martian crust. It was to address these and related questions of the earliest evolution of Mars that a workshop was organized under the auspices of the Mars: Evolution of Volcanism, Tectonism, and Volatiles (MEVTV) Program. Four sessions were held: crustal dichotomy; crustal differentiation/volcanism; Tharsis, Elysium, and Valles Marineris; and ridges and fault tectonics.

The Acheulian site of Gesher Benot Ya'aqov, Israel: environment, hominin culture, subsistence and adaptation on the shores of the paleo-Hula Lake

NASA Astrophysics Data System (ADS)

Goren-Inbar, N.

2014-12-01

The Acheulian site of Gesher Benot Ya'aqov (GBY), located in the Hula Valley, northern sector of the Dead Sea transform, stretches along 3.5 km of the Jordan River and its banks. The accumulation of tilted lake-margin sediments interfingered with basalt flows began 1.1 Ma and ended after 0.6 Ma. The excavations (1989-1997) exposed 34 m thick deposits that provide unique data sets on climate, environment, biology, culture and hominin behavior. Hominin presence is known throughout the sequence, providing information on Acheulian technology and cognition along the time trajectory, but the richest sites (15 in number) occur above the M/B Chron Boundary. Reconstructions of paleoenvironment and habitats are based on fossil remains yielding an extremely rich typically Mediterranean biomass of diverse biogeographic origins. Macro and micro organic material (over 140 identified taxa) exhibits a typical Mediterranean environment similar to the extant flora, with few extinctions (20 species). The rich fossil faunal include molluscs, ostracods, fish, amphibians, reptiles, birds, micromammals and medium-sized to large mammals (over 237 taxa), predominantly Palearctic in biogeographic origin. Many of these taxa are still extant, attesting to stable habitats and paleoclimatic conditions. Hominin occupations are documented by thousands of lithic artifacts (flint, limestone and basalt), all assigned to the Large Flake Acheulian culture. These assemblages show a continuous cultural tradition of the same tool kit along the time trajectory. The lithic reduction required developed cognitive abilities and communication abilities, interpreted as language. Evidence of hominin subsistence includes data on carcass processing including extraction of marrow, with a preference for consumption of fallow deer, elephant, hippopotamus and fish. Edible plant remains include nuts, USO, fruits, seeds and vegetables in association with stone artifacts and animal bones. Fire, present throughout, was

Early dynamical evolution of young substructured clusters

NASA Astrophysics Data System (ADS)

Dorval, Julien; Boily, Christian

2017-03-01

Stellar clusters form with a high level of substructure, inherited from the molecular cloud and the star formation process. Evidence from observations and simulations also indicate the stars in such young clusters form a subvirial system. The subsequent dynamical evolution can cause important mass loss, ejecting a large part of the birth population in the field. It can also imprint the stellar population and still be inferred from observations of evolved clusters. Nbody simulations allow a better understanding of these early twists and turns, given realistic initial conditions. Nowadays, substructured, clumpy young clusters are usually obtained through pseudo-fractal growth and velocity inheritance. We introduce a new way to create clumpy initial conditions through a ''Hubble expansion'' which naturally produces self consistent clumps, velocity-wise. In depth analysis of the resulting clumps shows consistency with hydrodynamical simulations of young star clusters. We use these initial conditions to investigate the dynamical evolution of young subvirial clusters. We find the collapse to be soft, with hierarchical merging leading to a high level of mass segregation. The subsequent evolution is less pronounced than the equilibrium achieved from a cold collapse formation scenario.

Late Pliocene and Early Pleistocene Temperature Reconstructions from Paleolakes of the West Turkana and North Awash Basins, East Africa

NASA Astrophysics Data System (ADS)

Castañeda, I. S.; Thompson-Munson, M.; Lupien, R.; Russell, J. M.

2015-12-01

The Hominin Sites and Paleolakes Drilling Project (HSPDP) aims to reconstruct past environments of the East African Rift Valley from locations in close proximity to some of the world's most important fossil hominin and artifact sites. In this study, we investigate sediments from the West Turkana and North Awash Basins, which were recently drilled as part of the HSPDP. The North Awash Basin contains abundant early hominin fossils and the lakebeds of the Hadar Formation (~3.6 to ~2.9 Ma) will provide a record of climate variability during the Pliocene, prior to the intensification of Northern Hemisphere glaciation at ~2.7 Ma. The lakebeds of the Turkana Basin are Early Pleistocene in age (~1.9 to ~1.45 Ma) and span the interval that includes some the earliest fossils of Homo rudolfensis and H. ergaster/erectus. Here we examine the organic geochemistry of West Turkana and North Awash Basin sediments and investigate the use of proxies based on isoprenoid and branched glycerol dialkyl glycerol tetraethers (GDGTs) to reconstruct temperature, including TEX86 and the methylation and cyclization (MBT and CBT) ratios and relative abundances of branched GDGTs. We also examine variability in the abundances and ratios of plant leaf waxes (n-alkanes) to provide insight into past vegetation changes on the East African landscape.

The evolution of the complex sensory and motor systems of the human brain.

PubMed

Kaas, Jon H

2008-03-18

Inferences about how the complex sensory and motor systems of the human brain evolved are based on the results of comparative studies of brain organization across a range of mammalian species, and evidence from the endocasts of fossil skulls of key extinct species. The endocasts of the skulls of early mammals indicate that they had small brains with little neocortex. Evidence from comparative studies of cortical organization from small-brained mammals of the six major branches of mammalian evolution supports the conclusion that the small neocortex of early mammals was divided into roughly 20-25 cortical areas, including primary and secondary sensory fields. In early primates, vision was the dominant sense, and cortical areas associated with vision in temporal and occipital cortex underwent a significant expansion. Comparative studies indicate that early primates had 10 or more visual areas, and somatosensory areas with expanded representations of the forepaw. Posterior parietal cortex was also expanded, with a caudal half dominated by visual inputs, and a rostral half dominated by somatosensory inputs with outputs to an array of seven or more motor and visuomotor areas of the frontal lobe. Somatosensory areas and posterior parietal cortex became further differentiated in early anthropoid primates. As larger brains evolved in early apes and in our hominin ancestors, the number of cortical areas increased to reach an estimated 200 or so in present day humans, and hemispheric specializations emerged. The large human brain grew primarily by increasing neuron number rather than increasing average neuron size.

The evolution of the complex sensory and motor systems of the human brain

PubMed Central

Kaas, Jon H.

2008-01-01

Inferences about how the complex sensory and motor systems of the human brain evolved are based on the results of comparative studies of brain organization across a range of mammalian species, and evidence from the endocasts of fossil skulls of key extinct species. The endocasts of the skulls of early mammals indicate that they had small brains with little neocortex. Evidence from comparative studies of cortical organization from small-brained mammals of the six major branches of mammalian evolution supports the conclusion that the small neocortex of early mammals was divided into roughly 20–25 cortical areas, including primary and secondary sensory fields. In early primates, vision was the dominant sense, and cortical areas associated with vision in temporal and occipital cortex underwent a significant expansion. Comparative studies indicate that early primates had 10 or more visual areas, and somatosensory areas with expanded representations of the forepaw. Posterior parietal cortex was also expanded, with a caudal half dominated by visual inputs, and a rostral half dominated by somatosensory inputs with outputs to an array of seven or more motor and visuomotor areas of the frontal lobe. Somatosensory areas and posterior parietal cortex became further differentiated in early anthropoid primates. As larger brains evolved in early apes and in our hominin ancestors, the number of cortical areas increased to reach an estimated 200 or so in present day humans, and hemispheric specializations emerged. The large human brain grew primarily by increasing neuron number rather than increasing average neuron size. PMID:18331903

Conference on Early Mars: Geologic and Hydrologic Evolution, Physical and Chemical Environments, and the Implications for Life

NASA Technical Reports Server (NTRS)

Clifford, S. M. (Editor); Treiman, A. H. (Editor); Newsom, H. E. (Editor); Farmer, J. D. (Editor)

1997-01-01

Topics considered include: Geology alteration and life in an extreme environment; developing a chemical code to identify magnetic biominerals; effect of impacts on early Martin geologic evolution; spectroscopic identification of minerals in Hematite-bearing soils and sediments; exopaleontology and the search for a Fossil record on Mars; geochemical evolution of the crust of Mars; geological evolution of the early earth;solar-wind-induced erosion of the Mars atmosphere. Also included geological evolution of the crust of Mars.

Modeling the early evolution of Vesta

NASA Astrophysics Data System (ADS)

Weisfeiler, Marie; Turcotte, Donald L.; Kellogg, Louise H.

2017-05-01

The early evolution of the asteroid Vesta has been extensively studied because of the availability of relevant data, especially important new studies of HED meteorites which originated from Vesta and the Dawn mission to Vesta in 2011-2012. These studies have concluded that an early melting episode led to the differentiation of Vesta into crust, mantle, and core. This melting episode is attributed to the decay of 26Al, which has a half-life of 7.17 × 105 yr. This heating produced a global magma ocean. Surface cooling of this magma ocean will produce a solid crust. In this paper, we propose a convective heat-transfer mechanism that effectively cools the asteroid when the degree of melting reaches about 50%. We propose that a cool solid surface crust, which is gravitationally unstable, will founder into the solid-liquid mix beneath and will very effectively transfer heat that prevents further melting of the interior. In this paper, we quantify this process. If Vesta had a very early formation, melting would commence at an age of about 1,30,000 yr, and solidification would occur at an age of about 10 Myr. If Vesta formed with a time delay greater than about 2 Myr, no melting would have occurred. An important result of our model is that the early melting episode is restricted to the first 10 Myr. This result is in good agreement with the radiometric ages of the HED meteorites.

Hypothesis: brain size and skull shape as criteria for a new hominin family tree.

PubMed

Chardin, Pierre

2014-10-01

Today, gorillas and chimpanzees live in tropical forests, where acid soils do not favor fossilization. It is thus widely believed that there are no fossils of chimpanzees or gorillas. However, four teeth of a 0.5-million-year (Ma)-old chimpanzee were discovered in the rift valley of Kenya (McBrearty and Jablonski, 2005), and a handful of teeth of a 10-Ma-old gorilla-like creature were found in Ethiopia (Suwa et al., 2007), close to the major sites of Homo discoveries. These discoveries indicate that chimpanzees and gorillas once shared their range with early Homo. However, the thousands of hominin fossils discovered in the past century have all been attributed to the Homo line. Thus far, our family tree looks like a bush with many dead-branches. If one admits the possibility that the australopithecines can also be the ancestors of African great apes, one can place Paranthropus on the side of gorilla ancestors and divide the remaining Australopithecus based on the brain size into the two main lines of humans and chimpanzees, thereby resulting in a coherent family tree. Copyright © 2014 Elsevier GmbH. All rights reserved.

Paleoenvironmental basis of cognitive evolution in great apes.

PubMed

Potts, Richard

2004-03-01

A bias favoring tree-dominated habitats and ripe-fruit frugivory has persisted in great ape evolution since the early Miocene. This bias is indicated by fossil ape paleoenvironments, molar morphology, dental microwear, the geographic pattern of extinctions, and extant apes' reliance on wooded settings. The ephemeral aspect of high-quality fruit has placed a premium on cognitive and social means of finding and defending food sources, and appears related to great apes' affinity since the Miocene for wooded, fruit-rich environments. These habitats have, however, undergone a severe withdrawal toward the low latitudes of Africa and Southeast Asia since the late Miocene, corresponding to a decline in the diversity of great apes beginning 9.5 million years ago. Plio-Pleistocene records imply that wooded settings of Africa and SE Asia were prone to substantial fragmentation and coalescence. Once apes were confined to equatorial settings, therefore, habitat instability heightened the spatial/temporal uncertainty of ripe-fruit sources. Prolonged learning, the assignment of attributes to distant places, mental representation, and reliance on fallback foods were all favored in this dynamic environmental context. These abilities helped sustain forest frugivory in most lineages. Fluid social grouping afforded the animals opportunities to locate ephemeral foods in continuous and fragmented forests. Fission-fusion grouping also magnified the problems of object impermanence (of individuals) and dispersion manifested by food sources in the ecological realm. Thus the spatial and temporal dynamics of fruit and wooded habitats since the Miocene are reflected in important components of great ape cognition, foraging, and sociality. In contrast to great apes, cercopithecoid monkeys have increased their plant dietary options and diversified in seasonal environments since the late Miocene. Early hominins eventually severed the habitat bias that characterized the evolution of great apes, and

Early Stages of the Evolution of Life: a Cybernetic Approach

NASA Astrophysics Data System (ADS)

Melkikh, Alexey V.; Seleznev, Vladimir D.

2008-08-01

Early stages of the evolution of life are considered in terms of control theory. A model is proposed for the transport of substances in a protocell possessing the property of robustness with regard to changes in the environmental concentration of a substance.

Early stages of the evolution of life: a cybernetic approach.

PubMed

Melkikh, Alexey V; Seleznev, Vladimir D

2008-08-01

Early stages of the evolution of life are considered in terms of control theory. A model is proposed for the transport of substances in a protocell possessing the property of robustness with regard to changes in the environmental concentration of a substance.

Revised stratigraphy of Area 123, Koobi Fora, Kenya, and new age estimates of its fossil mammals, including hominins.

PubMed

Gathogo, Patrick N; Brown, Francis H

2006-11-01

Recent geologic study shows that all hominins and nearly all other published mammalian fossils from Paleontological Collection Area 123, Koobi Fora, Kenya, derive from levels between the KBS Tuff (1.87+/-0.02 Ma) and the Lower Ileret Tuff (1.53+/-0.01 Ma). More specifically, the fossils derive from 53 m of section below the Lower Ileret Tuff, an interval in which beds vary markedly laterally, especially those units containing molluscs and algal stromatolites. The upper Burgi Member (approximately 2.00-1.87 Ma) crops out only in the southwestern part of Area 123. Adjacent Area 110 contains larger exposures of the member, and there the KBS Tuff is preserved as an airfall ash in lacustrine deposits and also as a fluvially redeposited ash. We observed no mammalian fossils in situ in this member in Area 123, but surface specimens have been documented in some monographic treatments. Fossil hominins from Area 123 were attributed to strata above the KBS Tuff in the 1970s, but later they were assigned to strata below the KBS Tuff (now called the upper Burgi Member). This study definitively places the Area 123 hominins in the KBS Member. Most of these hominins are between 1.60 and 1.65 myr in age, but the youngest may date to only 1.53 Ma, and the oldest, to 1.75 Ma. All are 0.15-0.30 myr younger than previously estimated. The new age estimates, in conjunction with published taxonomic attributions of fossils, suggest that at least two species of Homo coexisted in the region along with A. boisei until at least 1.65 Ma. Comparison of crania KNM-ER 1813 and KNM-ER 1470, which were believed to be of comparable age, is at the focus of the debate over whether Homo habilis sensu lato is in fact composed of two species: Homo habilis and Homo rudolfensis. These two crania are separated in time by approximately 0.25 myr, and therefore, arguments for their conspecificity no longer need to confront the issue of unusually high contemporaneous variation within a single species.

Fossil hominin radii from the Sima de los Huesos Middle Pleistocene site (Sierra de Atapuerca, Spain).

PubMed

Rodríguez, Laura; Carretero, José Miguel; García-González, Rebeca; Lorenzo, Carlos; Gómez-Olivencia, Asier; Quam, Rolf; Martínez, Ignacio; Gracia-Téllez, Ana; Arsuaga, Juan Luis

2016-01-01

Complete radii in the fossil record preceding recent humans and Neandertals are very scarce. Here we introduce the radial remains recovered from the Sima de los Huesos (SH) site in the Sierra de Atapuerca between 1976 and 2011 and which have been dated in excess of 430 ky (thousands of years) ago. The sample comprises 89 specimens, 49 of which are attributed to adults representing a minimum of seven individuals. All elements are described anatomically and metrically, and compared with other fossil hominins and recent humans in order to examine the phylogenetic polarity of certain radial features. Radial remains from SH have some traits that differentiate them from those of recent humans and make them more similar to Neandertals, including strongly curved shafts, anteroposterior expanded radial heads and both absolutely and relatively long necks. In contrast, the SH sample differs from Neandertals in showing a high overall gracility as well as a high frequency (80%) of an anteriorly oriented radial tuberosity. Thus, like the cranial and dental remains from the SH site, characteristic Neandertal radial morphology is not present fully in the SH radii. We also analyzed the cross-sectional properties of the SH radial sample at two different levels: mid-shaft and at the midpoint of the neck length. When standardized by shaft length, no difference in the mid-shaft cross-sectional properties were found between the SH hominins, Neandertals and recent humans. Nevertheless, due to their long neck length, the SH hominins show a higher lever efficiency than either Neandertals or recent humans. Functionally, the SH radial morphology is consistent with more efficient pronation-supination and flexion-extension movements. The particular trait composition in the SH sample and Neandertals resembles more closely morphology evident in recent human males. Copyright © 2015 Elsevier Ltd. All rights reserved.

Early Microbial Evolution: The Age of Anaerobes

PubMed Central

Martin, William F.; Sousa, Filipa L.

2016-01-01

In this article, the term “early microbial evolution” refers to the phase of biological history from the emergence of life to the diversification of the first microbial lineages. In the modern era (since we knew about archaea), three debates have emerged on the subject that deserve discussion: (1) thermophilic origins versus mesophilic origins, (2) autotrophic origins versus heterotrophic origins, and (3) how do eukaryotes figure into early evolution. Here, we revisit those debates from the standpoint of newer data. We also consider the perhaps more pressing issue that molecular phylogenies need to recover anaerobic lineages at the base of prokaryotic trees, because O2 is a product of biological evolution; hence, the first microbes had to be anaerobes. If molecular phylogenies do not recover anaerobes basal, something is wrong. Among the anaerobes, hydrogen-dependent autotrophs—acetogens and methanogens—look like good candidates for the ancestral state of physiology in the bacteria and archaea, respectively. New trees tend to indicate that eukaryote cytosolic ribosomes branch within their archaeal homologs, not as sisters to them and, furthermore tend to root archaea within the methanogens. These are major changes in the tree of life, and open up new avenues of thought. Geochemical methane synthesis occurs as a spontaneous, abiotic exergonic reaction at hydrothermal vents. The overall similarity between that reaction and biological methanogenesis fits well with the concept of a methanogenic root for archaea and an autotrophic origin of microbial physiology. PMID:26684184

Long-term climate record inferred from early-middle Pleistocene amphibian and squamate reptile assemblages at the Gran Dolina Cave, Atapuerca, Spain.

PubMed

Blain, Hugues-Alexandre; Bailon, Salvador; Cuenca-Bescós, Gloria; Arsuaga, Juan Luis; Bermúdez de Castro, José Maria; Carbonell, Eudald

2009-01-01

The Gran Dolina cave site is famous for having delivered some of the oldest hominin remains of Western Europe (Homo antecessor, ca. 960 ka). Moreover, the evidence of lithic industries throughout the long vertical section suggests occupation on the part of hominins from the latest early Pleistocene (levels TD3/4, TD5, and TD6) to the late middle Pleistocene (level TD10). The Gran Dolina Sondeo Sur (TDS) has furnished a great number of small-vertebrate remains; among them some 40,000 bones are attributed to amphibians and squamates. Although they do not differ specifically from the extant herpetofauna of the Iberian Peninsula, the overlap of their current distribution areas (= mutual climatic range method) in Spain can provide mean annual temperatures (MAT), the mean temperatures of the coldest (MTC) and warmest (MTW) months, and mean annual precipitation (MAP) estimations for each sub-level, and their change can be studied throughout the sequence. Results from the squamate and amphibian study indicate that during hominin occupation the MAT (10-13 degrees C) was always slightly warmer than at present in the vicinity of the Gran Dolina Cave, and the MAP (800-1000mm) was greater than today in the Burgos area. Climatic differences between "glacial" and "interglacial" phases are poorly marked. Summer temperatures (MTW) show stronger oscillations than winter temperatures (MTC), but seasonality remains almost unchanged throughout the sequence. These results are compared with those for large mammals, small mammals, and pollen analysis, giving a scenario for the palaeoclimatic conditions that occurred during the early to middle Pleistocene in Atapuerca, and hence a scenario for the hominins that once lived in the Sierra de Atapuerca.

Reticulate evolution and the human past: an anthropological perspective.

PubMed

Winder, Isabelle C; Winder, Nick P

2014-01-01

The evidence is mounting that reticulate (web-like) evolution has shaped the biological histories of many macroscopic plants and animals, including non-human primates closely related to Homo sapiens, but the implications of this non-hierarchical evolution for anthropological enquiry are not yet fully understood. When they are understood, the result may be a paradigm shift in evolutionary anthropology. This paper reviews the evidence for reticulated evolution in the non-human primates and human lineage. Then it makes the case for extrapolating this sort of patterning to Homo sapiens and other hominins and explores the implications this would have for research design, method and understandings of evolution in anthropology. Reticulation was significant in human evolutionary history and continues to influence societies today. Anthropologists and human scientists-whether working on ancient or modern populations-thus need to consider the implications of non-hierarchic evolution, particularly where molecular clocks, mathematical models and simplifying assumptions about evolutionary processes are used. This is not just a problem for palaeoanthropology. The simple fact of different mating systems among modern human groups, for example, may demand that more attention is paid to the potential for complexity in human genetic and cultural histories.

Identifying Major Transitions in the Evolution of Lithic Cutting Edge Production Rates

PubMed Central

Clarkson, Chris

2016-01-01

The notion that the evolution of core reduction strategies involved increasing efficiency in cutting edge production is prevalent in narratives of hominin technological evolution. Yet a number of studies comparing two different knapping technologies have found no significant differences in edge production. Using digital analysis methods we present an investigation of raw material efficiency in eight core technologies broadly representative of the long-term evolution of lithic technology. These are bipolar, multiplatform, discoidal, biface, Levallois, prismatic blade, punch blade and pressure blade production. Raw material efficiency is assessed by the ratio of cutting edge length to original core mass. We also examine which flake attributes contribute to maximising raw material efficiency, as well as compare the difference between expert and intermediate knappers in terms of cutting edge produced per gram of core. We identify a gradual increase in raw material efficiency over the broad sweep of lithic technological evolution. The results indicate that the most significant transition in efficiency likely took place with the introduction of small foliate biface, Levallois and prismatic blade knapping, all introduced in the Middle Stone Age / Middle Palaeolithic among early Homo sapiens and Neanderthals. This suggests that no difference in raw material efficiency existed between these species. With prismatic blade technology securely dated to the Middle Palaeolithic, by including the more recent punch and pressure blade technology our results dispel the notion that the transition to the Upper Palaeolithic was accompanied by an increase in efficiency. However, further increases in cutting edge efficiency are evident, with pressure blades possessing the highest efficiency in this study, indicating that late/epi-Palaeolithic and Neolithic blade technologies further increased efficiency. PMID:27936135

Identifying Major Transitions in the Evolution of Lithic Cutting Edge Production Rates.

PubMed

Muller, Antoine; Clarkson, Chris

2016-01-01

The notion that the evolution of core reduction strategies involved increasing efficiency in cutting edge production is prevalent in narratives of hominin technological evolution. Yet a number of studies comparing two different knapping technologies have found no significant differences in edge production. Using digital analysis methods we present an investigation of raw material efficiency in eight core technologies broadly representative of the long-term evolution of lithic technology. These are bipolar, multiplatform, discoidal, biface, Levallois, prismatic blade, punch blade and pressure blade production. Raw material efficiency is assessed by the ratio of cutting edge length to original core mass. We also examine which flake attributes contribute to maximising raw material efficiency, as well as compare the difference between expert and intermediate knappers in terms of cutting edge produced per gram of core. We identify a gradual increase in raw material efficiency over the broad sweep of lithic technological evolution. The results indicate that the most significant transition in efficiency likely took place with the introduction of small foliate biface, Levallois and prismatic blade knapping, all introduced in the Middle Stone Age / Middle Palaeolithic among early Homo sapiens and Neanderthals. This suggests that no difference in raw material efficiency existed between these species. With prismatic blade technology securely dated to the Middle Palaeolithic, by including the more recent punch and pressure blade technology our results dispel the notion that the transition to the Upper Palaeolithic was accompanied by an increase in efficiency. However, further increases in cutting edge efficiency are evident, with pressure blades possessing the highest efficiency in this study, indicating that late/epi-Palaeolithic and Neolithic blade technologies further increased efficiency.

Evolution of early embryogenesis in rhabditid nematodes

PubMed Central

Brauchle, Michael; Kiontke, Karin; MacMenamin, Philip; Fitch, David H. A.; Piano, Fabio

2009-01-01

The cell biological events that guide early embryonic development occur with great precision within species but can be quite diverse across species. How these cellular processes evolve and which molecular components underlie evolutionary changes is poorly understood. To begin to address these questions, we systematically investigated early embryogenesis, from the one- to the four-cell embryo, in 34 nematode species related to C. elegans. We found 40 cell-biological characters that captured the phenotypic differences between these species. By tracing the evolutionary changes on a molecular phylogeny, we found that these characters evolved multiple times and independently of one another. Strikingly, all these phenotypes are mimicked by single-gene RNAi experiments in C. elegans. We use these comparisons to hypothesize the molecular mechanisms underlying the evolutionary changes. For example, we predict that a cell polarity module was altered during the evolution of the Protorhabditis group and show that PAR-1, a kinase localized asymmetrically in C. elegans early embryos, is symmetrically localized in the one-cell stage of Protorhabditis group species. Our genome-wide approach identifies candidate molecules—and thereby modules—associated with evolutionary changes in cell-biological phenotypes. PMID:19643102

New fossils of Australopithecus anamensis from Kanapoi, West Turkana, Kenya (2003-2008).

PubMed

Ward, C V; Manthi, F K; Plavcan, J M

2013-11-01

Renewed fieldwork from 2003 through 2008 at the Australopithecus anamensis type-site of Kanapoi, Kenya, yielded nine new fossils attributable to this species. These fossils all date to between 4.195 and 4.108 million years ago. Most were recovered from the lower fluvial sequence at the site, with one from the lacustrine sequence deltaic sands that overlie the lower fluvial deposits but are still below the Kanapoi Tuff. The new specimens include a partial edentulous mandible, partial maxillary dentition, two partial mandibular dentitions, and five isolated teeth. The new Kanapoi hominin fossils increase the sample known from the earliest Australopithecus, and provide new insights into morphology within this taxon. They support the distinctiveness of the early A. anamensis fossils relative to earlier hominins and to the later Australopithecus afarensis. The new fossils do not appreciably extend the range of observed variation in A. anamensis from Kanapoi, with the exception of some slightly larger molars, and a canine tooth root that is the largest in the hominin fossil record. All of the Kanapoi hominins share a distinctive morphology of the canine-premolar complex, typical early hominin low canine crowns but with mesiodistally longer honing teeth than seen in A. afarensis, and large, probably dimorphic, canine tooth roots. The new Kanapoi specimens support the observation that canine crown height, morphology, root size and dimorphism were not altered from a primitive ape-like condition as part of a single event in human evolution, and that there may have been an adaptive difference in canine function between A. anamensis and A. afarensis. Copyright © 2013 Elsevier Ltd. All rights reserved.

Early time evolution of a chemically produced electron depletion

NASA Technical Reports Server (NTRS)

Scales, W. A.; Bernhardt, P. A.; Ganguli, G.

1995-01-01

The early time evolution of an ionospheric electron depletion produced by a radially expanding electron attachment chemical release is studied with a two-dimensional simulation model. The model includes electron attachment chemistry, incorporates fluid electrons, particle ions and neutrals, and considers the evolution in a plane perpendicular to the geomagnetic field for a low beta plasma. Timescales considered are of the order of or less than the cyclotron period of the negative ions that result as a by-product of the electron attacment reaction. This corresponds to time periods of tenths of seconds during recent experiemts. Simulation results show that a highly sheared azimuthal electron flow velocity develops in the radially expanding depletion boundary. This sheared electron flow velocity and the steep density gradients in the boundary give rise to small-scale irregulatities in the form of electron density cavities and spikes. The nonlinear evolution of these irregularities results in trapping and ultimately turbulent heating of the negative ions.

When felids and hominins ruled at Olduvai Gorge: A machine learning analysis of the skeletal profiles of the non-anthropogenic Bed I sites

NASA Astrophysics Data System (ADS)

Arriaza, Mari Carmen; Domínguez-Rodrigo, Manuel

2016-05-01

In the past twenty years, skeletal part profiles, which are prone to equifinality, have not occupied a prominent role in the interpretation of early Pleistocene sites on Africa. Alternatively, taphonomic studies on bone surface modifications and bone breakage patterns, have provided heuristic interpretations of some of the best preserved archaeological record of this period; namely, the Olduvai Bed I sites. The most recent and comprehensive taphonomic study of these sites (Domínguez-Rodrigo et al., 2007a) showed that FLK Zinj was an anthropogenic assemblage in which hominins acquired carcasses via primary access. That study also showed that the other sites were palimpsests with minimal or no intervention by hominins. The FLK N, FLK NN and DK sequence seemed to be dominated by single-agent (mostly, felid) or multiple-agent (mostly, felid-hyenid) processes. The present study re-analyzes the Bed I sites focusing on skeletal part profiles. Machine learning methods, which incorporate complex algorithms, are powerful predictive and classification methods and have the potential to better extract information from skeletal part representation than past approaches. Here, multiple algorithms (via decision trees, neural networks, random forests and support vector machines) are combined to produce a solid interpretation of bone accumulation agency at the Olduvai Bed I sites. This new approach virtually coincides with previous taphonomic interpretations on a site by site basis and shows that felids were dominant accumulating agents over hyenas during Bed I times. The recent discovery of possibly a modern lion-accumulated assemblage at Olduvai Gorge (Arriaza et al., submitted) provides a very timely analog for this interpretation.

Tectonics, orbital forcing, global climate change, and human evolution in Africa: introduction to the African paleoclimate special volume.

PubMed

Maslin, Mark A; Christensen, Beth

2007-11-01

becomes locally sensitive to precessional forcing, resulting in rapid shifts from wet to dry conditions. These periods of extreme climate variability may have provided a catalyst for evolutionary change and driven key speciation and dispersal events amongst mammals and hominins in Africa. In particular, hominin species seem to differentially originate and go extinct during periods of extreme climate variability. Results presented in this volume may represent the basis of a new theory of early human evolution in Africa.

The early evolution of feathers: fossil evidence from Cretaceous amber of France

PubMed Central

Perrichot, Vincent; Marion, Loïc; Néraudeau, Didier; Vullo, Romain; Tafforeau, Paul

2008-01-01

The developmental stages of feathers are of major importance in the evolution of body covering and the origin of avian flight. Until now, there were significant gaps in knowledge of early morphologies in theoretical stages of feathers as well as in palaeontological material. Here we report fossil evidence of an intermediate and critical stage in the incremental evolution of feathers which has been predicted by developmental theories but hitherto undocumented by evidence from both the recent and the fossil records. Seven feathers have been found in an Early Cretaceous (Late Albian, ca 100 Myr) amber of western France, which display a flattened shaft composed by the still distinct and incompletely fused bases of the barbs forming two irregular vanes. Considering their remarkably primitive features, and since recent discoveries have yielded feathers of modern type in some derived theropod dinosaurs, the Albian feathers from France might have been derived either from an early bird or from a non-avian dinosaur. PMID:18285280

The Origin and Early Evolution of Membrane Proteins

NASA Technical Reports Server (NTRS)

Pohorille, Andrew; Schweighofer, Karl; Wilson, Michael A.

2005-01-01

Membrane proteins mediate functions that are essential to all cells. These functions include transport of ions, nutrients and waste products across cell walls, capture of energy and its transduction into the form usable in chemical reactions, transmission of environmental signals to the interior of the cell, cellular growth and cell volume regulation. In the absence of membrane proteins, ancestors of cell (protocells), would have had only very limited capabilities to communicate with their environment. Thus, it is not surprising that membrane proteins are quite common even in simplest prokaryotic cells. Considering that contemporary membrane channels are large and complex, both structurally and functionally, a question arises how their presumably much simpler ancestors could have emerged, perform functions and diversify in early protobiological evolution. Remarkably, despite their overall complexity, structural motifs in membrane proteins are quite simple, with a-helices being most common. This suggests that these proteins might have evolved from simple building blocks. To explain how these blocks could have organized into functional structures, we performed large-scale, accurate computer simulations of folding peptides at a water-membrane interface, their insertion into the membrane, self-assembly into higher-order structures and function. The results of these simulations, combined with analysis of structural and functional experimental data led to the first integrated view of the origin and early evolution of membrane proteins.

Robust regression and posterior predictive simulation increase power to detect early bursts of trait evolution.

PubMed

Slater, Graham J; Pennell, Matthew W

2014-05-01

A central prediction of much theory on adaptive radiations is that traits should evolve rapidly during the early stages of a clade's history and subsequently slowdown in rate as niches become saturated--a so-called "Early Burst." Although a common pattern in the fossil record, evidence for early bursts of trait evolution in phylogenetic comparative data has been equivocal at best. We show here that this may not necessarily be due to the absence of this pattern in nature. Rather, commonly used methods to infer its presence perform poorly when when the strength of the burst--the rate at which phenotypic evolution declines--is small, and when some morphological convergence is present within the clade. We present two modifications to existing comparative methods that allow greater power to detect early bursts in simulated datasets. First, we develop posterior predictive simulation approaches and show that they outperform maximum likelihood approaches at identifying early bursts at moderate strength. Second, we use a robust regression procedure that allows for the identification and down-weighting of convergent taxa, leading to moderate increases in method performance. We demonstrate the utility and power of these approach by investigating the evolution of body size in cetaceans. Model fitting using maximum likelihood is equivocal with regards the mode of cetacean body size evolution. However, posterior predictive simulation combined with a robust node height test return low support for Brownian motion or rate shift models, but not the early burst model. While the jury is still out on whether early bursts are actually common in nature, our approach will hopefully facilitate more robust testing of this hypothesis. We advocate the adoption of similar posterior predictive approaches to improve the fit and to assess the adequacy of macroevolutionary models in general.

The evolution of Homo sapiens denisova and Homo sapiens neanderthalensis miRNA targeting genes in the prenatal and postnatal brain.

PubMed

Gunbin, Konstantin V; Afonnikov, Dmitry A; Kolchanov, Nikolay A; Derevianko, Anatoly P; Rogaev, Eugeny I

2015-01-01

As the evolution of miRNA genes has been found to be one of the important factors in formation of the modern type of man, we performed a comparative analysis of the evolution of miRNA genes in two archaic hominines, Homo sapiens neanderthalensis and Homo sapiens denisova, and elucidated the expression of their target mRNAs in bain. A comparative analysis of the genomes of primates, including species in the genus Homo, identified a group of miRNA genes having fixed substitutions with important implications for the evolution of Homo sapiens neanderthalensis and Homo sapiens denisova. The mRNAs targeted by miRNAs with mutations specific for Homo sapiens denisova exhibited enhanced expression during postnatal brain development in modern humans. By contrast, the expression of mRNAs targeted by miRNAs bearing variations specific for Homo sapiens neanderthalensis was shown to be enhanced in prenatal brain development. Our results highlight the importance of changes in miRNA gene sequences in the course of Homo sapiens denisova and Homo sapiens neanderthalensis evolution. The genetic alterations of miRNAs regulating the spatiotemporal expression of multiple genes in the prenatal and postnatal brain may contribute to the progressive evolution of brain function, which is consistent with the observations of fine technical and typological properties of tools and decorative items reported from archaeological Denisovan sites. The data also suggest that differential spatial-temporal regulation of gene products promoted by the subspecies-specific mutations in the miRNA genes might have occurred in the brains of Homo sapiens denisova and Homo sapiens neanderthalensis, potentially contributing to the cultural differences between these two archaic hominines.

The evolution of Homo sapiens denisova and Homo sapiens neanderthalensis miRNA targeting genes in the prenatal and postnatal brain

PubMed Central

2015-01-01

Background As the evolution of miRNA genes has been found to be one of the important factors in formation of the modern type of man, we performed a comparative analysis of the evolution of miRNA genes in two archaic hominines, Homo sapiens neanderthalensis and Homo sapiens denisova, and elucidated the expression of their target mRNAs in bain. Results A comparative analysis of the genomes of primates, including species in the genus Homo, identified a group of miRNA genes having fixed substitutions with important implications for the evolution of Homo sapiens neanderthalensis and Homo sapiens denisova. The mRNAs targeted by miRNAs with mutations specific for Homo sapiens denisova exhibited enhanced expression during postnatal brain development in modern humans. By contrast, the expression of mRNAs targeted by miRNAs bearing variations specific for Homo sapiens neanderthalensis was shown to be enhanced in prenatal brain development. Conclusions Our results highlight the importance of changes in miRNA gene sequences in the course of Homo sapiens denisova and Homo sapiens neanderthalensis evolution. The genetic alterations of miRNAs regulating the spatiotemporal expression of multiple genes in the prenatal and postnatal brain may contribute to the progressive evolution of brain function, which is consistent with the observations of fine technical and typological properties of tools and decorative items reported from archaeological Denisovan sites. The data also suggest that differential spatial-temporal regulation of gene products promoted by the subspecies-specific mutations in the miRNA genes might have occurred in the brains of Homo sapiens denisova and Homo sapiens neanderthalensis, potentially contributing to the cultural differences between these two archaic hominines. PMID:26693966

A New Basal Sauropod Dinosaur from the Middle Jurassic of Niger and the Early Evolution of Sauropoda

PubMed Central

Remes, Kristian; Ortega, Francisco; Fierro, Ignacio; Joger, Ulrich; Kosma, Ralf; Marín Ferrer, José Manuel; Ide, Oumarou Amadou; Maga, Abdoulaye

2009-01-01

Background The early evolution of sauropod dinosaurs is poorly understood because of a highly incomplete fossil record. New discoveries of Early and Middle Jurassic sauropods have a great potential to lead to a better understanding of early sauropod evolution and to reevaluate the patterns of sauropod diversification. Principal Findings A new sauropod from the Middle Jurassic of Niger, Spinophorosaurus nigerensis n. gen. et sp., is the most complete basal sauropod currently known. The taxon shares many anatomical characters with Middle Jurassic East Asian sauropods, while it is strongly dissimilar to Lower and Middle Jurassic South American and Indian forms. A possible explanation for this pattern is a separation of Laurasian and South Gondwanan Middle Jurassic sauropod faunas by geographic barriers. Integration of phylogenetic analyses and paleogeographic data reveals congruence between early sauropod evolution and hypotheses about Jurassic paleoclimate and phytogeography. Conclusions Spinophorosaurus demonstrates that many putatively derived characters of Middle Jurassic East Asian sauropods are plesiomorphic for eusauropods, while South Gondwanan eusauropods may represent a specialized line. The anatomy of Spinophorosaurus indicates that key innovations in Jurassic sauropod evolution might have taken place in North Africa, an area close to the equator with summer-wet climate at that time. Jurassic climatic zones and phytogeography possibly controlled early sauropod diversification. PMID:19756139

The waiting time problem in a model hominin population.

PubMed

Sanford, John; Brewer, Wesley; Smith, Franzine; Baumgardner, John

2015-09-17

Functional information is normally communicated using specific, context-dependent strings of symbolic characters. This is true within the human realm (texts and computer programs), and also within the biological realm (nucleic acids and proteins). In biology, strings of nucleotides encode much of the information within living cells. How do such information-bearing nucleotide strings arise and become established? This paper uses comprehensive numerical simulation to understand what types of nucleotide strings can realistically be established via the mutation/selection process, given a reasonable timeframe. The program Mendel's Accountant realistically simulates the mutation/selection process, and was modified so that a starting string of nucleotides could be specified, and a corresponding target string of nucleotides could be specified. We simulated a classic pre-human hominin population of at least 10,000 individuals, with a generation time of 20 years, and with very strong selection (50% selective elimination). Random point mutations were generated within the starting string. Whenever an instance of the target string arose, all individuals carrying the target string were assigned a specified reproductive advantage. When natural selection had successfully amplified an instance of the target string to the point of fixation, the experiment was halted, and the waiting time statistics were tabulated. Using this methodology we tested the effect of mutation rate, string length, fitness benefit, and population size on waiting time to fixation. Biologically realistic numerical simulations revealed that a population of this type required inordinately long waiting times to establish even the shortest nucleotide strings. To establish a string of two nucleotides required on average 84 million years. To establish a string of five nucleotides required on average 2 billion years. We found that waiting times were reduced by higher mutation rates, stronger fitness benefits, and

Distinct growth of the nasomaxillary complex in Au. sediba.

PubMed

Lacruz, Rodrigo S; Bromage, Timothy G; O'Higgins, Paul; Toro-Ibacache, Viviana; Warshaw, Johanna; Berger, Lee R

2015-10-15

Studies of facial ontogeny in immature hominins have contributed significantly to understanding the evolution of human growth and development. The recently discovered hominin species Autralopithecus sediba is represented by a well-preserved and nearly complete facial skeleton of a juvenile (MH1) which shows a derived facial anatomy. We examined MH1 using high radiation synchrotron to interpret features of the oronasal complex pertinent to facial growth. We also analyzed bone surface microanatomy to identify and map fields of bone deposition and bone resorption, which affect the development of the facial skeleton. The oronasal anatomy (premaxilla-palate-vomer architecture) is similar to other Australopithecus species. However surface growth remodeling of the midface (nasomaxillary complex) differs markedly from Australopithecus, Paranthropus, early Homo and from KNM-WT 15000 (H. erectus/ergaster) showing a distinct distribution of vertically disposed alternating depository and resorptive fields in relation to anterior dental roots and the subnasal region. The ontogeny of the MH1 midface superficially resembles some H. sapiens in the distribution of remodeling fields. The facial growth of MH1 appears unique among early hominins representing an evolutionary modification in facial ontogeny at 1.9 my, or to changes in masticatory system loading associated with diet.

Nonlinear detection of paleoclimate-variability transitions possibly related to human evolution

NASA Astrophysics Data System (ADS)

Donges, J. F.; Donner, R. V.; Trauth, M. H.; Marwan, N.; Schellnhuber, H. J.; Kurths, J.

2012-04-01

Potential paleoclimatic driving mechanisms acting on human evolution present an open problem of cross-disciplinary scientific interest. The analysis of paleoclimate archives encoding the environmental variability in East Africa during the last 5 Ma (million years) has triggered an ongoing debate about possible candidate processes and evolutionary mechanisms. In this work, we apply a novel nonlinear statistical technique, recurrence network analysis, to three distinct marine records of terrigenous dust flux. Our method enables us to identify three epochs with transitions between qualitatively different types of environmental variability in North and East Africa during the (i) Mid-Pliocene (3.35-3.15 Ma BP (before present)), (ii) Early Pleistocene (2.25-1.6 Ma BP), and (iii) Mid-Pleistocene (1.1-0.7 Ma BP). A deeper examination of these transition periods reveals potential climatic drivers, including (i) large-scale changes in ocean currents due to a spatial shift of the Indonesian throughflow in combination with an intensification of Northern Hemisphere glaciation, (ii) a global reorganization of the atmospheric Walker circulation induced in the tropical Pacific and Indian Ocean, and (iii) shifts in the dominating temporal variability pattern of glacial activity during the Mid-Pleistocene, respectively. A reexamination of the available fossil record demonstrates statistically significant coincidences between the detected transition periods and major steps in hominin evolution. This suggests that the observed shifts between more regular and more erratic environmental variability may have acted as a trigger for rapid change in the development of humankind in Africa.

Continuity or discontinuity in the European Early Pleistocene human settlement: the Atapuerca evidence

NASA Astrophysics Data System (ADS)

Bermúdez de Castro, José María; Martinón-Torres, María; Blasco, Ruth; Rosell, Jordi; Carbonell, Eudald

2013-09-01

The nature, timing, pattern, favourable circumstances and impediments of the human occupation of the European continent during the Early Pleistocene are hot topics in Quaternary studies. In particular, the problem of the (dis) continuity of the settlement of Europe in this period is an important matter of discussion, which has been approached in the last decade from different points of view. The Gran Dolina (TD) and Sima del Elefante (TE) cave sites in the Sierra de Atapuerca, (Spain) include large and quasi-continuous stratigraphic sequences that stretch back from at least 1.2 million years ago (Ma) to the Matuyama/Brunhes boundary. The archaeological and paleontological record from these sites can help to test different hypotheses about the character of the human settlement in this region and period. Furthermore, the TD6 level has yielded a large collection of human fossil remains attributed to Homo antecessor. According to different geochronological methods, as well as to paleomagnetic and biostratigraphical analyses, these hominins belong to an age range of 0.96-0.80 Ma. Unfortunately, the finding in 2007 of some human fossil remains in the TE9 level, dated to about 1.22 Ma, was not enough to conclude whether H. antecessor had deep roots in the European Early Pleistocene. A set of derived features of H. antecessor shared with both the Neanderthal lineage and modern humans suggests that this species is related, and not far, from the most recent common ancestor (MRCA) of Homo neanderthalensis and Homo sapiens. If we assume that there was a lineal biological relationship between the TE9 and TD6 hominins, we should reconsider many of the conclusions achieved in previous paleontological and genetic studies. In addition, we would be obliged to build a highly complicated paleogeographical scenario for the origin of the MRCA. Although continuity in the settlement of Europe during the entire late Early Pleistocene is not discarded (e.g. in refuge areas), it seems that

The Iberian Peninsula corridor or cul-de-sac? Mammalian faunal change and possible routes of dispersal in the last 2 million years

NASA Astrophysics Data System (ADS)

O'Regan, Hannah J.

2008-11-01

The Iberian Peninsula is almost surrounded by the sea and is topographically and ecologically variable. These factors will have impacted on both the distribution and dispersal patterns of large mammals (including hominins) within Iberia, and are considered in detail in this paper. There are two routes of mammalian dispersal into Iberia: across the Pyrenees and across the Gibraltar Strait. With an increasing interest in the possible use of coastlines by early hominins the latter route has been the focus of much discussion. However, the arguments are limited by the relative lack of hominin remains and archaeology from the Early Pleistocene. This paper takes a wider perspective to hominin dispersals by examining what is known of the evolution and movements of other taxa in Iberia and how these may inform our understanding of the hominin fossil record. Beginning by briefly reviewing the present day and Pleistocene glacial and interglacial vegetation of Iberia, it then considers the large-mammal fauna. Particular attention is paid to the potential routes of movement for terrestrial animals in and out of the peninsula, and the evidence for each route is assessed. Iberia was a refuge for temperate species during the Quaternary glacial cycles and movements of Quaternary faunas are reviewed in the light of modern phylogeographic analyses and studies of fossil assemblages. Iberian faunas are highly variable, with some absences of otherwise widespread European animals, but cold-phase taxa such as reindeer and woolly rhinoceros did cross the Pyrenees. It seems that the large mountain ranges were less a barrier for the dispersal of these taxa than the line which today forms the limit of the summer drought. Iberia also provided the last refuge for extinct species such as the Neanderthals and endangered extant species such as the Iberian lynx.

Early animal evolution: emerging views from comparative biology and geology

NASA Technical Reports Server (NTRS)

Knoll, A. H.; Carroll, S. B.

1999-01-01

The Cambrian appearance of fossils representing diverse phyla has long inspired hypotheses about possible genetic or environmental catalysts of early animal evolution. Only recently, however, have data begun to emerge that can resolve the sequence of genetic and morphological innovations, environmental events, and ecological interactions that collectively shaped Cambrian evolution. Assembly of the modern genetic tool kit for development and the initial divergence of major animal clades occurred during the Proterozoic Eon. Crown group morphologies diversified in the Cambrian through changes in the genetic regulatory networks that organize animal ontogeny. Cambrian radiation may have been triggered by environmental perturbation near the Proterozoic-Cambrian boundary and subsequently amplified by ecological interactions within reorganized ecosystems.

Preferential access to genetic information from endogenous hominin ancient DNA and accurate quantitative SNP-typing via SPEX

PubMed Central

Brotherton, Paul; Sanchez, Juan J.; Cooper, Alan; Endicott, Phillip

2010-01-01

The analysis of targeted genetic loci from ancient, forensic and clinical samples is usually built upon polymerase chain reaction (PCR)-generated sequence data. However, many studies have shown that PCR amplification from poor-quality DNA templates can create sequence artefacts at significant levels. With hominin (human and other hominid) samples, the pervasive presence of highly PCR-amplifiable human DNA contaminants in the vast majority of samples can lead to the creation of recombinant hybrids and other non-authentic artefacts. The resulting PCR-generated sequences can then be difficult, if not impossible, to authenticate. In contrast, single primer extension (SPEX)-based approaches can genotype single nucleotide polymorphisms from ancient fragments of DNA as accurately as modern DNA. A single SPEX-type assay can amplify just one of the duplex DNA strands at target loci and generate a multi-fold depth-of-coverage, with non-authentic recombinant hybrids reduced to undetectable levels. Crucially, SPEX-type approaches can preferentially access genetic information from damaged and degraded endogenous ancient DNA templates over modern human DNA contaminants. The development of SPEX-type assays offers the potential for highly accurate, quantitative genotyping from ancient hominin samples. PMID:19864251

Molecular clocks and the early evolution of metazoan nervous systems.

PubMed

Wray, Gregory A

2015-12-19

The timing of early animal evolution remains poorly resolved, yet remains critical for understanding nervous system evolution. Methods for estimating divergence times from sequence data have improved considerably, providing a more refined understanding of key divergences. The best molecular estimates point to the origin of metazoans and bilaterians tens to hundreds of millions of years earlier than their first appearances in the fossil record. Both the molecular and fossil records are compatible, however, with the possibility of tiny, unskeletonized, low energy budget animals during the Proterozoic that had planktonic, benthic, or meiofaunal lifestyles. Such animals would likely have had relatively simple nervous systems equipped primarily to detect food, avoid inhospitable environments and locate mates. The appearance of the first macropredators during the Cambrian would have changed the selective landscape dramatically, likely driving the evolution of complex sense organs, sophisticated sensory processing systems, and diverse effector systems involved in capturing prey and avoiding predation. © 2015 The Author(s).

Does Environmental Knowledge Inhibit Hominin Dispersal?

PubMed

Wren, Colin D; Costopoulos, Andre

2015-07-01

We investigated the relationship between the dispersal potential of a hominin population, its local-scale foraging strategies, and the characteristics of the resource environment using an agent-based modeling approach. In previous work we demonstrated that natural selection can favor a relatively low capacity for assessing and predicting the quality of the resource environment, especially when the distribution of resources is highly clustered. That work also suggested that the more knowledge foraging populations had about their environment, the less likely they were to abandon the landscape they know and disperse into novel territory. The present study gives agents new individual and social strategies for learning about their environment. For both individual and social learning, natural selection favors decreased levels of environmental knowledge, particularly in low-heterogeneity environments. Social acquisition of detailed environmental knowledge results in crowding of agents, which reduces available reproductive space and relative fitness. Agents with less environmental knowledge move away from resource clusters and into areas with more space available for reproduction. These results suggest that, rather than being a requirement for successful dispersal, environmental knowledge strengthens the ties to particular locations and significantly reduces the dispersal potential as a result. The evolved level of environmental knowledge in a population depends on the characteristics of the resource environment and affects the dispersal capacity of the population.

Evolutionary anthropology and genes: investigating the genetics of human evolution from excavated skeletal remains.

PubMed

Anastasiou, Evilena; Mitchell, Piers D

2013-10-01

The development of molecular tools for the extraction, analysis and interpretation of DNA from the remains of ancient organisms (paleogenetics) has revolutionised a range of disciplines as diverse as the fields of human evolution, bioarchaeology, epidemiology, microbiology, taxonomy and population genetics. The paper draws attention to some of the challenges associated with the extraction and interpretation of ancient DNA from archaeological material, and then reviews the influence of paleogenetics on the field of human evolution. It discusses the main contributions of molecular studies to reconstructing the evolutionary and phylogenetic relationships between extinct hominins (human ancestors) and anatomically modern humans. It also explores the evidence for evolutionary changes in the genetic structure of anatomically modern humans in recent millennia. This breadth of research has led to discoveries that would never have been possible using traditional approaches to human evolution. Copyright © 2013 Elsevier B.V. All rights reserved.

Could Martian Strawberries Be? -- Prebiotic Chemical Evolution on an Early Wet Mars

NASA Astrophysics Data System (ADS)

Lerman, L.

2005-03-01

The universality of chemical physics dictates the ubiquity of bubbles, aerosols, and droplets on planets with water and simple amphiphiles. Their ability to functionally support prebiotic chemical evolution seems critical: on the early Earth and Mars, and quite likely for Titan and Europa.

Recent origin of low trabecular bone density in modern humans

PubMed Central

Chirchir, Habiba; Kivell, Tracy L.; Ruff, Christopher B.; Hublin, Jean-Jacques; Carlson, Kristian J.; Zipfel, Bernhard; Richmond, Brian G.

2015-01-01

Humans are unique, compared with our closest living relatives (chimpanzees) and early fossil hominins, in having an enlarged body size and lower limb joint surfaces in combination with a relatively gracile skeleton (i.e., lower bone mass for our body size). Some analyses have observed that in at least a few anatomical regions modern humans today appear to have relatively low trabecular density, but little is known about how that density varies throughout the human skeleton and across species or how and when the present trabecular patterns emerged over the course of human evolution. Here, we test the hypotheses that (i) recent modern humans have low trabecular density throughout the upper and lower limbs compared with other primate taxa and (ii) the reduction in trabecular density first occurred in early Homo erectus, consistent with the shift toward a modern human locomotor anatomy, or more recently in concert with diaphyseal gracilization in Holocene humans. We used peripheral quantitative CT and microtomography to measure trabecular bone of limb epiphyses (long bone articular ends) in modern humans and chimpanzees and in fossil hominins attributed to Australopithecus africanus, Paranthropus robustus/early Homo from Swartkrans, Homo neanderthalensis, and early Homo sapiens. Results show that only recent modern humans have low trabecular density throughout the limb joints. Extinct hominins, including pre-Holocene Homo sapiens, retain the high levels seen in nonhuman primates. Thus, the low trabecular density of the recent modern human skeleton evolved late in our evolutionary history, potentially resulting from increased sedentism and reliance on technological and cultural innovations. PMID:25535354

Recent origin of low trabecular bone density in modern humans.

PubMed

Chirchir, Habiba; Kivell, Tracy L; Ruff, Christopher B; Hublin, Jean-Jacques; Carlson, Kristian J; Zipfel, Bernhard; Richmond, Brian G

2015-01-13

Humans are unique, compared with our closest living relatives (chimpanzees) and early fossil hominins, in having an enlarged body size and lower limb joint surfaces in combination with a relatively gracile skeleton (i.e., lower bone mass for our body size). Some analyses have observed that in at least a few anatomical regions modern humans today appear to have relatively low trabecular density, but little is known about how that density varies throughout the human skeleton and across species or how and when the present trabecular patterns emerged over the course of human evolution. Here, we test the hypotheses that (i) recent modern humans have low trabecular density throughout the upper and lower limbs compared with other primate taxa and (ii) the reduction in trabecular density first occurred in early Homo erectus, consistent with the shift toward a modern human locomotor anatomy, or more recently in concert with diaphyseal gracilization in Holocene humans. We used peripheral quantitative CT and microtomography to measure trabecular bone of limb epiphyses (long bone articular ends) in modern humans and chimpanzees and in fossil hominins attributed to Australopithecus africanus, Paranthropus robustus/early Homo from Swartkrans, Homo neanderthalensis, and early Homo sapiens. Results show that only recent modern humans have low trabecular density throughout the limb joints. Extinct hominins, including pre-Holocene Homo sapiens, retain the high levels seen in nonhuman primates. Thus, the low trabecular density of the recent modern human skeleton evolved late in our evolutionary history, potentially resulting from increased sedentism and reliance on technological and cultural innovations.

Contributions of Planetary Science to Studies of Early Biosphere Evolution

NASA Technical Reports Server (NTRS)

Farmer, Jack D.; Chang, Sherwood (Technical Monitor)

1995-01-01

The history of impact cratering on the Moon, and extrapolations of crater chronologies to the inner planets, suggests that the late accretionary history of the Earth overlapped with other crucial events in the its history, including the origin of terrestrial life. This evidence, acquired from studies of other planetary bodies in the inner solar system, has profoundly affected how we view the early history of the Earth and evolution of the biosphere. Pre-biotic chemical evolution and the origin of life would have been delayed by the probable existence of a global magma ocean until -4.2 Ga. The early crust was largely destroyed by recycling, thus accounting for the sparse Archean record on Earth. Once life had developed, large impacts may have extinguished it several times before it finally gained a foothold. Potentially sterilizing impacts could have occurred as late as 3.7 Ga. At the very least, large impacts would have forced the biosphere through major environmental "bottlenecks" thereby canalizing its subsequent evolution. One legacy of these early events may be the structure of the present RNA-tree which indicates that extreme thermophiles are primitive within the Archaea, and may be the last common ancestors of life. By 3.5 Ga, marine sedimentary sequences contain unequivocal microbial fossils that attest to the presence of a terrestrial biosphere. The diversity of microbial forms present in these earliest fossil assemblages implies a preceding interval of evolution during which major evolutionary advances (e.g. photosynthesis) could have taken place. Evidence cited above places the origin of life within the interval 3.5 and 4.2 Ga, a period of 700 Ma. Thus, it appears that terrestrial life not only evolved rapidly, but perhaps more than once. This expands the possibilities that life may have also developed elsewhere. Of the other planets in our solar system, Mars holds the greatest chance of having developed life. But, the present surface of Mars is hostile

Trabecular architecture in the StW 352 fossil hominin calcaneus.

PubMed

Zeininger, Angel; Patel, Biren A; Zipfel, Bernhard; Carlson, Kristian J

2016-08-01

Australopithecus africanus has been interpreted as having a rigid lateral foot. One mechanism contributing to a rigid foot during push-off in humans is a calcaneocuboid joint (CCJ) with limited dorsiflexion and a "close-packed" talocalcaneal joint (TCJ). In contrast, apes likely have a greater CCJ range of motion and lack a close-packed TCJ. Differences in tarsal arthrokinematics may result in different joint loading environments. In Homo sapiens, we tested the hypothesis that dorsal and plantar CCJ and the TCJ show evidence of predictable habitual loading. In Pan troglodytes, Gorilla gorilla, Gorilla beringei, and Papio ursinus, we tested the hypothesis that only the dorsal CCJ shows evidence of predictable loading. Specifically, we predicted similarity in trabecular properties across the dorsal and plantar CCJ in H. sapiens, but dissimilarity in non-humans. Additionally, we investigated trabecular properties of an A. africanus calcaneus (StW 352) to evaluate joint loading patterns in this hominin and ultimately address the evolution of these properties in H. sapiens. Contrary to predictions, the H. sapiens dorsal CCJ has a significantly higher elongation index, bone volume fraction, trabecular thickness, and trabecular number than the plantar CCJ, while trabecular properties in non-humans do not always differ as predicted between regions. H. sapiens exhibits trabecular morphology indicative of less variable TCJ loading than other groups, having the most anisotropic and rod-like struts oriented in line with predicted principal loads. Multivariate analysis shows that the StW 352 dorsal CCJ matches P. ursinus best, while the plantar CCJ matches G. beringei best and the TCJ matches that of G. gorilla best. Overall patterns suggest that the StW 352 calcaneus experienced more variable loading than H. sapiens, but less variable loading than P. troglodytes, G. gorilla, G. beringei, and P. ursinus, consistent with a large range of foot movements, probably

Early-late life trade-offs and the evolution of ageing in the wild.

PubMed

Lemaître, Jean-François; Berger, Vérane; Bonenfant, Christophe; Douhard, Mathieu; Gamelon, Marlène; Plard, Floriane; Gaillard, Jean-Michel

2015-05-07

Empirical evidence for declines in fitness components (survival and reproductive performance) with age has recently accumulated in wild populations, highlighting that the process of senescence is nearly ubiquitous in the living world. Senescence patterns are highly variable among species and current evolutionary theories of ageing propose that such variation can be accounted for by differences in allocation to growth and reproduction during early life. Here, we compiled 26 studies of free-ranging vertebrate populations that explicitly tested for a trade-off between performance in early and late life. Our review brings overall support for the presence of early-late life trade-offs, suggesting that the limitation of available resources leads individuals to trade somatic maintenance later in life for high allocation to reproduction early in life. We discuss our results in the light of two closely related theories of ageing-the disposable soma and the antagonistic pleiotropy theories-and propose that the principle of energy allocation roots the ageing process in the evolution of life-history strategies. Finally, we outline research topics that should be investigated in future studies, including the importance of natal environmental conditions in the study of trade-offs between early- and late-life performance and the evolution of sex-differences in ageing patterns. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

The Dramatic Size and Kinematic Evolution of Massive Early-type Galaxies

NASA Astrophysics Data System (ADS)

Lapi, A.; Pantoni, L.; Zanisi, L.; Shi, J.; Mancuso, C.; Massardi, M.; Shankar, F.; Bressan, A.; Danese, L.

2018-04-01

We aim to provide a holistic view on the typical size and kinematic evolution of massive early-type galaxies (ETGs) that encompasses their high-z star-forming progenitors, their high-z quiescent counterparts, and their configurations in the local Universe. Our investigation covers the main processes playing a relevant role in the cosmic evolution of ETGs. Specifically, their early fast evolution comprises biased collapse of the low angular momentum gaseous baryons located in the inner regions of the host dark matter halo; cooling, fragmentation, and infall of the gas down to the radius set by the centrifugal barrier; further rapid compaction via clump/gas migration toward the galaxy center, where strong heavily dust-enshrouded star formation takes place and most of the stellar mass is accumulated; and ejection of substantial gas amount from the inner regions by feedback processes, which causes a dramatic puffing-up of the stellar component. In the late slow evolution, passive aging of stellar populations and mass additions by dry merger events occur. We describe these processes relying on prescriptions inspired by basic physical arguments and by numerical simulations to derive new analytical estimates of the relevant sizes, timescales, and kinematic properties for individual galaxies along their evolution. Then we obtain quantitative results as a function of galaxy mass and redshift, and compare them to recent observational constraints on half-light size R e , on the ratio v/σ between rotation velocity and velocity dispersion (for gas and stars) and on the specific angular momentum j ⋆ of the stellar component; we find good consistency with the available multiband data in average values and dispersion, both for local ETGs and for their z ∼ 1–2 star-forming and quiescent progenitors. The outcomes of our analysis can provide hints to gauge sub-grid recipes implemented in simulations, to tune numerical experiments focused on specific processes, and to plan

Rates of anterior tooth wear in Middle Pleistocene hominins from Sima de los Huesos (Sierra de Atapuerca, Spain).

PubMed

Bermúdez de Castro, J M; Martinón-Torres, M; Sarmiento, S; Lozano, M; Arsuaga, J L; Carbonell, E

2003-10-14

This study presents quantitative data on the rates of anterior tooth wear in a Pleistocene human population. The data were obtained for the hominin sample of the Sima de los Huesos site in Atapuerca, Spain. The fossil record belongs to a minimum of 28 individuals of the same biological population, assigned to the species Homo heidelbergensis. We have estimated the original and the preserved crown height of the mandibular incisors (I1 and I2) of 11 individuals, whose age at death can be ascertained from the mineralization stage and tooth eruption. Results provide a range of 0.276-0.348 and 0.288-0.360 mm per year for the mean wear rate of the mandibular I1 and I2, respectively, in individuals approximately 16-18 years old. These data suggest that incisors' crowns would be totally worn out toward the fifth decade of life. Thus, we expect the life expectancy of this population to be seriously limited. These data, which could be contrasted with results obtained on hominins at other sites, could be of interest for estimating the death age of adult individuals.

Rates of anterior tooth wear in Middle Pleistocene hominins from Sima de los Huesos (Sierra de Atapuerca, Spain)

PubMed Central

de Castro, J. M. Bermúdez; Martinón-Torres, M.; Sarmiento, S.; Lozano, M.; Arsuaga, J. L.; Carbonell, E.

2003-01-01

This study presents quantitative data on the rates of anterior tooth wear in a Pleistocene human population. The data were obtained for the hominin sample of the Sima de los Huesos site in Atapuerca, Spain. The fossil record belongs to a minimum of 28 individuals of the same biological population, assigned to the species Homo heidelbergensis. We have estimated the original and the preserved crown height of the mandibular incisors (I1 and I2) of 11 individuals, whose age at death can be ascertained from the mineralization stage and tooth eruption. Results provide a range of 0.276–0.348 and 0.288–0.360 mm per year for the mean wear rate of the mandibular I1 and I2, respectively, in individuals ≈16–18 years old. These data suggest that incisors' crowns would be totally worn out toward the fifth decade of life. Thus, we expect the life expectancy of this population to be seriously limited. These data, which could be contrasted with results obtained on hominins at other sites, could be of interest for estimating the death age of adult individuals. PMID:14528001

Origin and evolution of the atmospheres of early Venus, Earth and Mars

NASA Astrophysics Data System (ADS)

Lammer, Helmut; Zerkle, Aubrey L.; Gebauer, Stefanie; Tosi, Nicola; Noack, Lena; Scherf, Manuel; Pilat-Lohinger, Elke; Güdel, Manuel; Grenfell, John Lee; Godolt, Mareike; Nikolaou, Athanasia

2018-05-01

We review the origin and evolution of the atmospheres of Earth, Venus and Mars from the time when their accreting bodies were released from the protoplanetary disk a few million years after the origin of the Sun. If the accreting planetary cores reached masses ≥ 0.5 M_Earth before the gas in the disk disappeared, primordial atmospheres consisting mainly of H_2 form around the young planetary body, contrary to late-stage planet formation, where terrestrial planets accrete material after the nebula phase of the disk. The differences between these two scenarios are explored by investigating non-radiogenic atmospheric noble gas isotope anomalies observed on the three terrestrial planets. The role of the young Sun's more efficient EUV radiation and of the plasma environment into the escape of early atmospheres is also addressed. We discuss the catastrophic outgassing of volatiles and the formation and cooling of steam atmospheres after the solidification of magma oceans and we describe the geochemical evidence for additional delivery of volatile-rich chondritic materials during the main stages of terrestrial planet formation. The evolution scenario of early Earth is then compared with the atmospheric evolution of planets where no active plate tectonics emerged like on Venus and Mars. We look at the diversity between early Earth, Venus and Mars, which is found to be related to their differing geochemical, geodynamical and geophysical conditions, including plate tectonics, crust and mantle oxidation processes and their involvement in degassing processes of secondary N_2 atmospheres. The buildup of atmospheric N_2, O_2, and the role of greenhouse gases such as CO_2 and CH_4 to counter the Faint Young Sun Paradox (FYSP), when the earliest life forms on Earth originated until the Great Oxidation Event ≈ 2.3 Gyr ago, are addressed. This review concludes with a discussion on the implications of understanding Earth's geophysical and related atmospheric evolution in relation

A climate and environmental context for hominid evolution: Preliminary biomarker and compound specific isotope data from Lake Magadi, Kenya

NASA Astrophysics Data System (ADS)

Werne, J. P.; Ferland, T.; Cohen, A. S.; Lowenstein, T. K.; Deocampo, D.; Renaut, R.; Bernhart, O. R.

2016-12-01

The Hominid Sites and Paleolakes Drilling Project (HSPDP) seeks to understand the paleoclimatic and paleoenvironmental context of human evolution and development by analysis of paleolacustrine cores taken near key hominin fossil and artifact localities in Kenya and Ethiopia. Here, we present biomarker and compound specific isotope data from a 200 m drill core from Lake Magadi, Kenya. Located 20 km from the Koora Plain in the southern Kenya Rift, and adjacent to the Olorgesailie basin, Lake Magadi is in one of the richest Early-Late Pleistocene archaeological localities in Africa, a region that has been key in debates about the relationship between climate and evolution. Preliminary biomarker work has shown promising abundances of leaf waxes, whose isotopic compositions of hydrogen and carbon are commonly used as proxies for paleoprecipitation and watershed vegetation composition, respectively. A complementary record of glycerol dialkyl glycerol tetraethers (GDGTs), which can serve as a proxy for temperature, soil input, and/or pH, will be presented alongside the leaf wax data to enhance the paleoenvironmental reconstruction of Lake Magadi. Present-day Lake Magadi is a saline pan, a descendant of a series of paleolakes that have occupied its drainage basin for approximately one million years. Hominid evolution milestones such as the mastering of fire as a tool, rapid encephalization, and the emergence of Homo sapiens all are thought to have occurred in the time frame encompassed by our record.

Symbiosis in cell evolution: Life and its environment on the early earth

NASA Technical Reports Server (NTRS)

Margulis, L.

1981-01-01

The book treats cell evolution from the viewpoint of the serial endosymbiosis theory of the origin of organelles. Following a brief outline of the symbiotic theory, which holds that eukaryotes evolved by the association of free-living bacteria with a host prokaryote, the diversity of life is considered, and five kingdoms of organisms are distinguished: the prokaryotic Monera and the eukaryotic Protoctista, Animalia, Fungi and Plantae. Symbiotic and traditional direct filiation theories of cell evolution are compared. Recent observations of cell structure and biochemistry are reviewed in relation to early cell evolution, with attention given to the geological context for the origin of eukaryotic cells, the origin of major bacterial anaerobic pathways, the relationship between aerobic metabolism and atmospheric oxygen, criteria for distinguishing symbiotic organelles from those that originated by differentiation, and the major classes of eukaryotic organelles: mitochondria, cilia, microtubules, the mitotic and meiotic apparatuses, and pastids. Cell evolution during the Phanerozoic is also discussed with emphasis on the effects of life on the biosphere

Neurocranium versus Face: A Morphometric Approach with Classical Anthropometric Variables for Characterizing Patterns of Cranial Integration in Extant Hominoids and Extinct Hominins

PubMed Central

Pérez-Claros, Juan Antonio; Jiménez-Arenas, Juan Manuel; Palmqvist, Paul

2015-01-01

The relative importance of the two main cranial complexes, the neurocranium and the splanchnocranium, has been examined in the five species of extant hominoids and in a huge sample of extinct hominins using six standard craniometric variables that measure the length, width and height of each cranial module. Factor analysis and two-block partial least squares were used for establishing the major patterns of developmental and evolutionary integration between both cranial modules. The results obtained show that all extant hominoids (including the anatomically modern humans) share a conserved pattern of developmental integration, a result that agrees with previous studies. The pattern of evolutionary integration between both cranial modules in australopiths runs in parallel to developmental integration. In contrast, the pattern of evolutionary and developmental integration of the species of the genus Homo is the opposite, which is probably the consequence of distinctive selective regimes for both hominin groups. PMID:26177535

Neurocranium versus Face: A Morphometric Approach with Classical Anthropometric Variables for Characterizing Patterns of Cranial Integration in Extant Hominoids and Extinct Hominins.

PubMed

Pérez-Claros, Juan Antonio; Jiménez-Arenas, Juan Manuel; Palmqvist, Paul

2015-01-01

The relative importance of the two main cranial complexes, the neurocranium and the splanchnocranium, has been examined in the five species of extant hominoids and in a huge sample of extinct hominins using six standard craniometric variables that measure the length, width and height of each cranial module. Factor analysis and two-block partial least squares were used for establishing the major patterns of developmental and evolutionary integration between both cranial modules. The results obtained show that all extant hominoids (including the anatomically modern humans) share a conserved pattern of developmental integration, a result that agrees with previous studies. The pattern of evolutionary integration between both cranial modules in australopiths runs in parallel to developmental integration. In contrast, the pattern of evolutionary and developmental integration of the species of the genus Homo is the opposite, which is probably the consequence of distinctive selective regimes for both hominin groups.

High adult mortality among Hiwi hunter-gatherers: implications for human evolution.

PubMed

Hill, Kim; Hurtado, A M; Walker, R S

2007-04-01

Extant apes experience early sexual maturity and short life spans relative to modern humans. Both of these traits and others are linked by life-history theory to mortality rates experienced at different ages by our hominin ancestors. However, currently there is a great deal of debate concerning hominin mortality profiles at different periods of evolutionary history. Observed rates and causes of mortality in modern hunter-gatherers may provide information about Upper Paleolithic mortality that can be compared to indirect evidence from the fossil record, yet little is published about causes and rates of mortality in foraging societies around the world. To our knowledge, interview-based life tables for recent hunter-gatherers are published for only four societies (Ache, Agta, Hadza, and Ju/'hoansi). Here, we present mortality data for a fifth group, the Hiwi hunter-gatherers of Venezuela. The results show comparatively high death rates among the Hiwi and highlight differences in mortality rates among hunter-gatherer societies. The high levels of conspecific violence and adult mortality in the Hiwi may better represent Paleolithic human demographics than do the lower, disease-based death rates reported in the most frequently cited forager studies.

Brief communication: Reaction to fire by savanna chimpanzees (Pan troglodytes verus) at Fongoli, Senegal: Conceptualization of "fire behavior" and the case for a chimpanzee model.

PubMed

Pruetz, Jill D; LaDuke, Thomas C

2010-04-01

The use and control of fire are uniquely human traits thought to have come about fairly late in the evolution of our lineage, and they are hypothesized to correlate with an increase in intellectual complexity. Given the relatively sophisticated cognitive abilities yet small brain size of living apes compared to humans and even early hominins, observations of wild chimpanzees' reactions to naturally occurring fire can help inform hypotheses about the likely responses of early hominins to fire. We use data on the behavior of savanna chimpanzees (Pan troglodytes verus) at Fongoli, Senegal during two encounters with wildfires to illuminate the similarities between great apes and humans regarding their reaction to fire. Chimpanzees' close relatedness to our lineage makes them phylogenetically relevant to the study of hominid evolution, and the open, hot and dry environment at Fongoli, similar to the savanna mosaic thought to characterize much of hominid evolution, makes these apes ecologically important as a living primate model as well. Chimpanzees at Fongoli calmly monitor wildfires and change their behavior in anticipation of the fire's movement. The ability to conceptualize the "behavior" of fire may be a synapomorphic trait characterizing the human-chimpanzee clade. If the cognitive underpinnings of fire conceptualization are a primitive hominid trait, hypotheses concerning the origins of the control and use of fire may need revision. We argue that our findings exemplify the importance of using living chimpanzees as models for better understanding human evolution despite recently published suggestions to the contrary. (c) 2009 Wiley-Liss, Inc.

Footprints reveal direct evidence of group behavior and locomotion in Homo erectus

PubMed Central

Hatala, Kevin G.; Roach, Neil T.; Ostrofsky, Kelly R.; Wunderlich, Roshna E.; Dingwall, Heather L.; Villmoare, Brian A.; Green, David J.; Harris, John W. K.; Braun, David R.; Richmond, Brian G.

2016-01-01

Bipedalism is a defining feature of the human lineage. Despite evidence that walking on two feet dates back 6–7 Ma, reconstructing hominin gait evolution is complicated by a sparse fossil record and challenges in inferring biomechanical patterns from isolated and fragmentary bones. Similarly, patterns of social behavior that distinguish modern humans from other living primates likely played significant roles in our evolution, but it is exceedingly difficult to understand the social behaviors of fossil hominins directly from fossil data. Footprints preserve direct records of gait biomechanics and behavior but they have been rare in the early human fossil record. Here we present analyses of an unprecedented discovery of 1.5-million-year-old footprint assemblages, produced by 20+ Homo erectus individuals. These footprints provide the oldest direct evidence for modern human-like weight transfer and confirm the presence of an energy-saving longitudinally arched foot in H. erectus. Further, print size analyses suggest that these H. erectus individuals lived and moved in cooperative multi-male groups, offering direct evidence consistent with human-like social behaviors in H. erectus. PMID:27403790

Evolution and ecology of retinal photoreception in early vertebrates.

PubMed

Collin, Shaun P

2010-01-01

Visual ecology or the relationship between the visual system of an animal and its environment has proven to be a crucial research field for establishing general concepts of adaptation, specialization and evolution. The visual neuroscientist is indeed confronted with a plethora of different visual characteristics, each seemingly optimised for each species' ecological niche, but often without a clear understanding of the evolutionary constraints at play. However, before we are able to fully understand the influence(s) of ecology and phylogeny on visual system design in vertebrates, it is first necessary to understand the basic bauplan of key representatives of each taxa. This review examines photoreception in hagfishes, lampreys, cartilaginous fishes and lungfishes with an eye to their ecology using a range of neurobiological methods including anatomy, microspectrophotometry and molecular genetics. These early vertebrates represent critical stages in evolution and surprisingly possess a level of visual complexity that is almost unrivalled in other vertebrates. 2010 S. Karger AG, Basel.

The early evolution of eukaryotes - A geological perspective

NASA Technical Reports Server (NTRS)

Knoll, Andrew H.

1992-01-01

This paper examines the goodness of fit between patterns of biological and environmental history implied by molecular phylogenies of eukaryotic organisms and the geological records of early eukaryote evolution. It was found that Precambrian geological records show evidence that episodic increases in biological diversity roughly coincided with episodic environmental changes and by sharp increases in atmospheric oxygen concentrations which significantly changed the earth surface environments. Although the goodness of fit among physical and biological changes is gratifyingly high, the records of these changes do not always coincide in time. The additional information in these fields that is needed for complete integration of geological and phylogenic records is suggested.

Tectonics and soil edaphics as controls on animal migrations and early human inhabitance in the Kenya Rift

NASA Astrophysics Data System (ADS)

Kübler, Simon; Rucina, Stephen; Reynolds, Sally; Fürgut, Felix; Bailey, Geoffrey; King, Geoffrey

2017-04-01

Animal movements in the tectonically active East African Rift Valley today are influenced by a combination of topography and soil nutrient distribution (soil edaphics). These patterns would have been the same in the past when hominins inhabited the area. Our study in the Kenya Rift shows that soil edaphics and active rift structures play a key role in present day animal movements as well as the for the location of early hominin sites. We carried out field analysis at Olorgesailie and Kariandusi, two key hominin sites in the southern and central Kenya Rift, respectiveley. Based on studying the relationship between the geology, tectonics and soil development we identified 'good' and 'bad' regions both in terms of edaphics and accessibility for grazing animals. We further sampled a large number of soils that developed on the volcanic bedrock and sediments of the region and interviewed the local Maasai shepherds to learn about present-day good and bad grazing sites. Ultimately, we created palaeoenvironmental and spatio-temporal reconstructions for interpreting human land use and exploitation of large mammals in the Kenya Rift for the relevant time frame of approximately 1 Ma BP. At Olorgesailie the hominin site is located in lacustrine sediments at the southern edge of a playa that extends north and northwest of Mt. Olorgesailie. The lakebeds are now tilted and eroded by motion on two north-south striking faults. The lake was trapped by volcanic flows and alluvial fans from Mt. Olorgesailie and was released by the fault motion leading to deep river incision and exposure of the site. To the west and the north steep fault scarps bound the playa forming a natural barrier for animals. Field observations and information from local shepherds suggest that the abundant trachytes at the valley floor produce poor soils whereas the soils developed on lacustrine and alluvial sediments close to the hominin site provide much more attractive grazing sites for present-day animals

Palaeoproteomics for human evolution studies

NASA Astrophysics Data System (ADS)

Welker, Frido

2018-06-01

The commonplace sequencing of Neanderthal, Denisovan and ancient modern human DNA continues to revolutionize our understanding of hominin phylogeny and interaction(s). The challenge with older fossils is that the progressive fragmentation of DNA even under optimal conditions, a function of time and temperature, results in ever shorter fragments of DNA. This process continues until no DNA can be sequenced or reliably aligned. Ancient proteins ultimately suffer a similar fate, but are a potential alternative source of biomolecular sequence data to investigate hominin phylogeny given their slower rate of fragmentation. In addition, ancient proteins have been proposed to potentially provide insights into in vivo biological processes and can be used to provide additional ecological information through large scale ZooMS (Zooarchaeology by Mass Spectrometry) screening of unidentifiable bone fragments. However, as initially with ancient DNA, most ancient protein research has focused on Late Pleistocene or Holocene samples from Europe. In addition, only a limited number of studies on hominin remains have been published. Here, an updated review on ancient protein analysis in human evolutionary contexts is given, including the identification of specific knowledge gaps and existing analytical limits, as well as potential avenues to overcome these.

Late stages of accumulation and early evolution of the planets

NASA Technical Reports Server (NTRS)

Vityazev, Andrey V.; Perchernikova, G. V.

1991-01-01

Recently developed solutions of problems are discussed that were traditionally considered fundamental in classical solar system cosmogony: determination of planetary orbit distribution patterns, values for mean eccentricity and orbital inclinations of the planets, and rotation periods and rotation axis inclinations of the planets. Two important cosmochemical aspects of accumulation are examined: the time scale for gas loss from the terrestrial planet zone, and the composition of the planets in terms of isotope data. It was concluded that the early beginning of planet differentiation is a function of the heating of protoplanets during collisions with large (thousands of kilometers) bodies. Energetics, heat mass transfer processes, and characteristic time scales of these processes at the early stages of planet evolution are considered.

The origin and early evolution of life on earth

NASA Technical Reports Server (NTRS)

Oro, J.; Miller, Stanley L.; Lazcano, Antonio

1990-01-01

Results of the studies that have provided insights into the cosmic and primitive earth environments are reviewed with emphasis on those environments in which life is thought to have originated. The evidence bearing on the antiquity of life on the earth and the prebiotic significance of organic compounds found in interstellar clouds and in primitive solar-system bodies such as comets, dark asteroids, and carbonaceous chondrites are assessed. The environmental models of the Hadean and early Archean earth are discussed, as well as the prebiotic formation of organic monomers and polymers essential to life. The processes that may have led to the appearance in the Archean of the first cells are considered, and possible effects of these processes on the early steps of biological evolution are analyzed. The significance of these results to the study of the distribution of life in the universe is evaluated.

A continued role for signaling functions in the early evolution of feathers.

PubMed

Ruxton, Graeme D; Persons Iv, W Scott; Currie, Philip J

2017-03-01

Persons and Currie (2015) argued against either flight, thermoregulation, or signaling as a functional benefit driving the earliest evolution of feathers; rather, they favored simple feathers having an initial tactile sensory function, which changed to a thermoregulatory function as density increased. Here, we explore the relative merits of early simple feathers that may have originated as tactile sensors progressing instead toward a signaling, rather than (or in addition to) a thermoregulatory function. We suggest that signaling could act in concert with a sensory function more naturally than could thermoregulation. As such, the dismissal of a possible signaling function and the presumption that an initial sensory function led directly to a thermoregulatory function (implicit in the title "bristles before down") are premature. © 2017 The Author(s). Evolution © 2017 The Society for the Study of Evolution.

Homo erectus and Middle Pleistocene hominins: brain size, skull form, and species recognition.

PubMed

Rightmire, G Philip

2013-09-01

Hominins that differ from Homo erectus, the Neanderthals, and recent humans are known from Middle Pleistocene localities across the Old World. The taxonomic status of these populations has been clouded by controversy. Perhaps the most critical problem has been an incomplete understanding of variation in skull form. Here, both H. erectus and later mid-Pleistocene hominins are the focus of an investigation aimed at clarifying the relationships among brain volume, basicranial dimensions, neurocranial shape, and certain facial characters. Brain size in H. erectus averages about 950 cm(3), while in a series of Middle Pleistocene crania from Africa and Europe, volume is about 1230 cm(3). If encephalization is the primary mechanism operating in the mid-Pleistocene, then diverse aspects of cranial form cannot all be treated as independent variables. Correlation is utilized to examine the associations among measurements for more than 30 H. erectus crania that are reasonably well preserved. A similar approach is used with the Middle Pleistocene sample. Patterns of covariation are compared in order to assess integration. Next, factor analysis is applied to the H. erectus specimens in an attempt to identify modules, tightly integrated traits that can evolve independently. Studies of the variation within H. erectus are followed by direct comparisons with the Middle Pleistocene population. Discriminant functions facilitate the description of intergroup differences. Traits that vary independently from brain volume include anterior frontal broadening, lateral expansion of the parietal vault, elevation of the lambda-inion chord, and rounding of the sagittal contour of the occipital. This finding helps to resolve the problem of species recognition. Neurocranial proportions as well as characters from the cranial base and face can be incorporated into a differential diagnosis for the mid-Pleistocene sample. Evidence presented here supports arguments for speciation in the Middle

Diet and environment 1.2 million years ago revealed through analysis of dental calculus from Europe's oldest hominin at Sima del Elefante, Spain

NASA Astrophysics Data System (ADS)

Hardy, Karen; Radini, Anita; Buckley, Stephen; Blasco, Ruth; Copeland, Les; Burjachs, Francesc; Girbal, Josep; Yll, Riker; Carbonell, Eudald; Bermúdez de Castro, Jose María

2017-02-01

Sima del Elefante, Atapuerca, Spain contains one of the earliest hominin fragments yet known in Europe, dating to 1.2 Ma. Dental calculus from a hominin molar was removed, degraded and analysed to recover entrapped remains. Evidence for plant use at this time is very limited and this study has revealed the earliest direct evidence for foods consumed in the genus Homo. This comprises starchy carbohydrates from two plants, including a species of grass from the Triticeae or Bromideae tribe, meat and plant fibres. All food was eaten raw, and there is no evidence for processing of the starch granules which are intact and undamaged. Additional biographical detail includes fragments of non-edible wood found adjacent to an interproximal groove suggesting oral hygiene activities, while plant fibres may be linked to raw material processing. Environmental evidence comprises spores, insect fragments and conifer pollen grains which are consistent with a forested environment.

THE EVOLUTION OF EARLY- AND LATE-TYPE GALAXIES IN THE COSMIC EVOLUTION SURVEY UP TO z {approx} 1.2

DOE Office of Scientific and Technical Information (OSTI.GOV)

Pannella, Maurilio; Gabasch, Armin; Drory, Niv

2009-08-10

The Cosmic Evolution Survey (COSMOS) allows for the first time a highly significant census of environments and structures up to redshift 1, as well as a full morphological description of the galaxy population. In this paper we present a study aimed to constrain the evolution, in the redshift range 0.2 < z < 1.2, of the mass content of different morphological types and its dependence on the environmental density. We use a deep multicolor catalog, covering an area of {approx}0.7 deg{sup 2} inside the COSMOS field, with accurate photometric redshifts (i {approx}< 26.5 and {delta}z/(z {sub spec} + 1) {approx}more » 0.035). We estimate galaxy stellar masses by fitting the multicolor photometry to a grid of composite stellar population models. We quantitatively describe the galaxy morphology by fitting point-spread function convolved Sersic profiles to the galaxy surface brightness distributions down to F814 = 24 mag for a sample of 41,300 objects. We confirm an evolution of the morphological mix with redshift: the higher the redshift the more disk-dominated galaxies become important. We find that the morphological mix is a function of the local comoving density: the morphology density relation extends up to the highest redshift explored. The stellar mass function of disk-dominated galaxies is consistent with being constant with redshift. Conversely, the stellar mass function of bulge-dominated systems shows a decline in normalization with redshift. Such different behaviors of late-types and early-types stellar mass functions naturally set the redshift evolution of the transition mass. We find a population of relatively massive, early-type galaxies, having high specific star formation rate (SSFR) and blue colors which live preferentially in low-density environments. The bulk of massive (>7 x 10{sup 10} M {sub sun}) early-type galaxies have similar characteristic ages, colors, and SSFRs independently of the environment they belong to, with those hosting the oldest stars

The early evolution of Jean Piaget's clinical method.

PubMed

Mayer, Susan Jean

2005-11-01

This article analyzes the early evolution of Jean Piaget's renowned "clinical method" in order to investigate the method's strikingly original and generative character. Throughout his 1st decade in the field, Piaget frequently discussed and justified the many different approaches to data collection he used. Analysis of his methodological progression during this period reveals that Piaget's determination to access the genuine convictions of children eventually led him to combine 3 distinct traditions in which he had been trained-naturalistic observation, psychometrics, and the psychiatric clinical examination. It was in this amalgam, first evident in his 4th text, that Piaget discovered the clinical dynamic that would drive the classic experiments for which he is most well known.

An Early Pleistocene high-resolution paleoclimate reconstruction from the West Turkana (Kenya) HSPDP drill site

NASA Astrophysics Data System (ADS)

Stockhecke, Mona; Beck, Catherine; Brown, Erik T.; Cohen, Andrew; Deocampo, Daniel M.; Feibel, Craig S.; Pelletier, Jon D.; Rabideaux, Nathane M.; Sier, Mark

2016-04-01

The Hominin Sites and Paleolakes Drilling Project (HSPDP), and the related Olorgesailie Drilling Project (ODP), recovered ~2 km of drill core since 2012. At the HSPDP West Turkana Kaitio (WTK) site a 216 m-long core that covers the Early Pleistocene time window (1.3 to 1.87 Ma) during which hominids first expanded out of Africa and marine records document reorganization of tropical climate and the development of the strong Walker circulation. WTK carries particular interest for paleoclimate and paleoenvironmental reconstructions as it is located only 2.5 km from the location of one of the most complete hominin skeletons ever recovered (Nariokotome Boy). XRF core scanning data provide a means of evaluating records of past environmental conditions continuously and at high resolution. However, the record contains complex lithologies reflecting repeated episodes of inundation and desiccation along a dynamic lake margin. Here we present a methodological approach to address the highly variable lithostratigraphy of the East African records to establish comprehensive paleoclimate timeseries. The power spectrum of the presented hydroclimate record peaks at Milankovitch cycles, qualifying HSPDP drill cores from the Turkana Basin to be used as high-resolution Early Pleistocene paleoclimate archive. Comparing these data with marine climate reconstructions sheds light into athmospheric processes and continental climate dynamics.

Recent Structural Evolution of Early-Type Galaxies: Size Growth from z = 1 to z = 0

NASA Astrophysics Data System (ADS)

van der Wel, Arjen; Holden, Bradford P.; Zirm, Andrew W.; Franx, Marijn; Rettura, Alessandro; Illingworth, Garth D.; Ford, Holland C.

2008-11-01

Strong size and internal density evolution of early-type galaxies between z ~ 2 and the present has been reported by several authors. Here we analyze samples of nearby and distant (z ~ 1) galaxies with dynamically measured masses in order to confirm the previous, model-dependent results and constrain the uncertainties that may play a role. Velocity dispersion (σ) measurements are taken from the literature for 50 morphologically selected 0.8 < z < 1.2 field and cluster early-type galaxies with typical masses Mdyn = 2 × 1011 M⊙. Sizes (Reff) are determined with Advanced Camera for Surveys imaging. We compare the distant sample with a large sample of nearby (0.04 < z < 0.08) early-type galaxies extracted from the Sloan Digital Sky Survey for which we determine sizes, masses, and densities in a consistent manner, using simulations to quantify systematic differences between the size measurements of nearby and distant galaxies. We find a highly significant difference between the σ - Reff distributions of the nearby and distant samples, regardless of sample selection effects. The implied evolution in Reff at fixed mass between z = 1 and the present is a factor of 1.97 +/- 0.15. This is in qualitative agreement with semianalytic models; however, the observed evolution is much faster than the predicted evolution. Our results reinforce and are quantitatively consistent with previous, photometric studies that found size evolution of up to a factor of 5 since z ~ 2. A combination of structural evolution of individual galaxies through the accretion of companions and the continuous formation of early-type galaxies through increasingly gas-poor mergers is one plausible explanation of the observations. Based on observations with the Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by AURA, Inc., under NASA contract NAS5-26555, and observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory

Clades reach highest morphological disparity early in their evolution

PubMed Central

Hughes, Martin; Gerber, Sylvain; Wills, Matthew Albion

2013-01-01

There are few putative macroevolutionary trends or rules that withstand scrutiny. Here, we test and verify the purported tendency for animal clades to reach their maximum morphological variety relatively early in their evolutionary histories (early high disparity). We present a meta-analysis of 98 metazoan clades radiating throughout the Phanerozoic. The disparity profiles of groups through time are summarized in terms of their center of gravity (CG), with values above and below 0.50 indicating top- and bottom-heaviness, respectively. Clades that terminate at one of the “big five” mass extinction events tend to have truncated trajectories, with a significantly top-heavy CG distribution overall. The remaining 63 clades show the opposite tendency, with a significantly bottom-heavy mean CG (relatively early high disparity). Resampling tests are used to identify groups with a CG significantly above or below 0.50; clades not terminating at a mass extinction are three times more likely to be significantly bottom-heavy than top-heavy. Overall, there is no clear temporal trend in disparity profile shapes from the Cambrian to the Recent, and early high disparity is the predominant pattern throughout the Phanerozoic. Our results do not allow us to distinguish between ecological and developmental explanations for this phenomenon. To the extent that ecology has a role, however, the paucity of bottom-heavy clades radiating in the immediate wake of mass extinctions suggests that early high disparity more probably results from the evolution of key apomorphies at the base of clades rather than from physical drivers or catastrophic ecospace clearing. PMID:23884651

The oldest known primate skeleton and early haplorhine evolution.

PubMed

Ni, Xijun; Gebo, Daniel L; Dagosto, Marian; Meng, Jin; Tafforeau, Paul; Flynn, John J; Beard, K Christopher

2013-06-06

Reconstructing the earliest phases of primate evolution has been impeded by gaps in the fossil record, so that disagreements persist regarding the palaeobiology and phylogenetic relationships of the earliest primates. Here we report the discovery of a nearly complete and partly articulated skeleton of a primitive haplorhine primate from the early Eocene of China, about 55 million years ago, the oldest fossil primate of this quality ever recovered. Coupled with detailed morphological examination using propagation phase contrast X-ray synchrotron microtomography, our phylogenetic analysis based on total available evidence indicates that this fossil is the most basal known member of the tarsiiform clade. In addition to providing further support for an early dichotomy between the strepsirrhine and haplorhine clades, this new primate further constrains the age of divergence between tarsiiforms and anthropoids. It also strengthens the hypothesis that the earliest primates were probably diurnal, arboreal and primarily insectivorous mammals the size of modern pygmy mouse lemurs.

The earliest long-distance obsidian transport: Evidence from the ∼200 ka Middle Stone Age Sibilo School Road Site, Baringo, Kenya.

PubMed

Blegen, Nick

2017-02-01

This study presents the earliest evidence of long-distance obsidian transport at the ∼200 ka Sibilo School Road Site (SSRS), an early Middle Stone Age site in the Kapthurin Formation, Kenya. The later Middle Pleistocene of East Africa (130-400 ka) spans significant and interrelated behavioral and biological changes in human evolution including the first appearance of Homo sapiens. Despite the importance of the later Middle Pleistocene, there are relatively few archaeological sites in well-dated contexts (n < 10) that document hominin behavior from this time period. In particular, geochemically informed evidence of long-distance obsidian transport, important for investigating expansion of intergroup interactions in hominin evolution, is rare from the Middle Pleistocene record of Africa. The SSRS offers a unique contribution to this small but growing dataset. Tephrostratigraphic analysis of tuffs encasing the SSRS provides a minimum age of ∼200 ka for the site. Levallois points and methods of core preparation demonstrate characteristic Middle Stone Age lithic technologies present at the SSRS. A significant portion (43%) of the lithic assemblage is obsidian. The SSRS obsidian comes from three different sources located at distances of 25 km, 140 km and 166 km from the site. The majority of obsidian derives from the farthest source, 166 km to the south of the site. The SSRS thus provides important new evidence that long-distance raw material transport, and the expansion of hominin intergroup interactions that this entails, was a significant feature of hominin behavior ∼200 ka, the time of the first appearance of H. sapiens, and ∼150,000 years before similar behaviors were previously documented in the region. Copyright © 2016 Elsevier Ltd. All rights reserved.

Human evolution: taxonomy and paleobiology

PubMed Central

WOOD, BERNARD; RICHMOND, BRIAN G.

2000-01-01

This review begins by setting out the context and the scope of human evolution. Several classes of evidence, morphological, molecular, and genetic, support a particularly close relationship between modern humans and the species within the genus Pan, the chimpanzee. Thus human evolution is the study of the lineage, or clade, comprising species more closely related to modern humans than to chimpanzees. Its stem species is the so-called ‘common hominin ancestor’, and its only extant member is Homo sapiens. This clade contains all the species more closely-related to modern humans than to any other living primate. Until recently, these species were all subsumed into a family, Hominidae, but this group is now more usually recognised as a tribe, the Hominini. The rest of the review sets out the formal nomenclature, history of discovery, and information about the characteristic morphology, and its behavioural implications, of the species presently included in the human clade. The taxa are considered within their assigned genera, beginning with the most primitive and finishing with Homo. Within genera, species are presented in order of geological age. The entries conclude with a list of the more important items of fossil evidence, and a summary of relevant taxonomic issues. PMID:10999270

Human evolution: taxonomy and paleobiology.

PubMed

Wood, B; Richmond, B G

2000-07-01

This review begins by setting out the context and the scope of human evolution. Several classes of evidence, morphological, molecular, and genetic, support a particularly close relationship between modern humans and the species within the genus Pan, the chimpanzee. Thus human evolution is the study of the lineage, or clade, comprising species more closely related to modern humans than to chimpanzees. Its stem species is the so-called 'common hominin ancestor', and its only extant member is Homo sapiens. This clade contains all the species more closely-related to modern humans than to any other living primate. Until recently, these species were all subsumed into a family, Hominidae, but this group is now more usually recognised as a tribe, the Hominini. The rest of the review sets out the formal nomenclature, history of discovery, and information about the characteristic morphology, and its behavioural implications, of the species presently included in the human clade. The taxa are considered within their assigned genera, beginning with the most primitive and finishing with Homo. Within genera, species are presented in order of geological age. The entries conclude with a list of the more important items of fossil evidence, and a summary of relevant taxonomic issues.

Microbes, Mineral Evolution, and the Rise of Microcontinents-Origin and Coevolution of Life with Early Earth.

PubMed

Grosch, Eugene G; Hazen, Robert M

2015-10-01

Earth is the most mineralogically diverse planet in our solar system, the direct consequence of a coevolving geosphere and biosphere. We consider the possibility that a microbial biosphere originated and thrived in the early Hadean-Archean Earth subseafloor environment, with fundamental consequences for the complex evolution and habitability of our planet. In this hypothesis paper, we explore possible venues for the origin of life and the direct consequences of microbially mediated, low-temperature hydrothermal alteration of the early oceanic lithosphere. We hypothesize that subsurface fluid-rock-microbe interactions resulted in more efficient hydration of the early oceanic crust, which in turn promoted bulk melting to produce the first evolved fragments of felsic crust. These evolved magmas most likely included sialic or tonalitic sheets, felsic volcaniclastics, and minor rhyolitic intrusions emplaced in an Iceland-type extensional setting as the earliest microcontinents. With the further development of proto-tectonic processes, these buoyant felsic crustal fragments formed the nucleus of intra-oceanic tonalite-trondhjemite-granitoid (TTG) island arcs. Thus microbes, by facilitating extensive hydrothermal alteration of the earliest oceanic crust through bioalteration, promoted mineral diversification and may have been early architects of surface environments and microcontinents on young Earth. We explore how the possible onset of subseafloor fluid-rock-microbe interactions on early Earth accelerated metavolcanic clay mineral formation, crustal melting, and subsequent metamorphic mineral evolution. We also consider environmental factors supporting this earliest step in geosphere-biosphere coevolution and the implications for habitability and mineral evolution on other rocky planets, such as Mars.

Sequential Bottlenecks Drive Viral Evolution in Early Acute Hepatitis C Virus Infection

PubMed Central

McElroy, Kerensa; Gaudieri, Silvana; Pham, Son T.; Chopra, Abha; Cameron, Barbara; Maher, Lisa; Dore, Gregory J.; White, Peter A.; Lloyd, Andrew R.

2011-01-01

Hepatitis C is a pandemic human RNA virus, which commonly causes chronic infection and liver disease. The characterization of viral populations that successfully initiate infection, and also those that drive progression to chronicity is instrumental for understanding pathogenesis and vaccine design. A comprehensive and longitudinal analysis of the viral population was conducted in four subjects followed from very early acute infection to resolution of disease outcome. By means of next generation sequencing (NGS) and standard cloning/Sanger sequencing, genetic diversity and viral variants were quantified over the course of the infection at frequencies as low as 0.1%. Phylogenetic analysis of reassembled viral variants revealed acute infection was dominated by two sequential bottleneck events, irrespective of subsequent chronicity or clearance. The first bottleneck was associated with transmission, with one to two viral variants successfully establishing infection. The second occurred approximately 100 days post-infection, and was characterized by a decline in viral diversity. In the two subjects who developed chronic infection, this second bottleneck was followed by the emergence of a new viral population, which evolved from the founder variants via a selective sweep with fixation in a small number of mutated sites. The diversity at sites with non-synonymous mutation was higher in predicted cytotoxic T cell epitopes, suggesting immune-driven evolution. These results provide the first detailed analysis of early within-host evolution of HCV, indicating strong selective forces limit viral evolution in the acute phase of infection. PMID:21912520

Diet and environment 1.2 million years ago revealed through analysis of dental calculus from Europe's oldest hominin at Sima del Elefante, Spain.

PubMed

Hardy, Karen; Radini, Anita; Buckley, Stephen; Blasco, Ruth; Copeland, Les; Burjachs, Francesc; Girbal, Josep; Yll, Riker; Carbonell, Eudald; Bermúdez de Castro, Jose María

2017-02-01

Sima del Elefante, Atapuerca, Spain contains one of the earliest hominin fragments yet known in Europe, dating to 1.2 Ma. Dental calculus from a hominin molar was removed, degraded and analysed to recover entrapped remains. Evidence for plant use at this time is very limited and this study has revealed the earliest direct evidence for foods consumed in the genus Homo. This comprises starchy carbohydrates from two plants, including a species of grass from the Triticeae or Bromideae tribe, meat and plant fibres. All food was eaten raw, and there is no evidence for processing of the starch granules which are intact and undamaged. Additional biographical detail includes fragments of non-edible wood found adjacent to an interproximal groove suggesting oral hygiene activities, while plant fibres may be linked to raw material processing. Environmental evidence comprises spores, insect fragments and conifer pollen grains which are consistent with a forested environment.

Temporal variations in early developmental decisions: an engine of forebrain evolution.

PubMed

Bielen, H; Pal, S; Tole, S; Houart, C

2017-02-01

Tight control of developmental timing is pivotal to many major processes in developmental biology, such as patterning, fate specification, cell cycle dynamics, cell migration and connectivity. Temporal change in these ontogenetic sequences is known as heterochrony, a major force in the evolution of body plans and organogenesis. In the last 5 years, studies in fish and rodents indicate that heterochrony in signaling during early development generates diversity in forebrain size and complexity. Here, we summarize these findings and propose that, additionally to spatio-temporal tuning of neurogenesis, temporal and quantitative modulation of signaling events drive pivotal changes in shape, size and complexity of the forebrain across evolution, participating to the generation of diversity in animal behavior and emergence of cognition. Copyright © 2017 Elsevier Ltd. All rights reserved.

The evolution of the diversity of cultures

PubMed Central

Foley, R. A.; Mirazón Lahr, M.

2011-01-01

The abundant evidence that Homo sapiens evolved in Africa within the past 200 000 years, and dispersed across the world only within the past 100 000 years, provides us with a strong framework in which to consider the evolution of human diversity. While there is evidence that the human capacity for culture has a deeper history, going beyond the origin of the hominin clade, the tendency for humans to form cultures as part of being distinct communities and populations changed markedly with the evolution of H. sapiens. In this paper, we investigate ‘cultures’ as opposed to ‘culture’, and the question of how and why, compared to biological diversity, human communities and populations are so culturally diverse. We consider the way in which the diversity of human cultures has developed since 100 000 years ago, and how its rate was subject to environmental factors. We argue that the causes of this diversity lie in the distribution of resources and the way in which human communities reproduce over several generations, leading to fissioning of kin groups. We discuss the consequences of boundary formation through culture in their broader ecological and evolutionary contexts. PMID:21357230

Root evolution at the base of the lycophyte clade: insights from an Early Devonian lycophyte

PubMed Central

Matsunaga, Kelly K. S.; Tomescu, Alexandru M. F.

2016-01-01

Background and Aims The evolution of complex rooting systems during the Devonian had significant impacts on global terrestrial ecosystems and the evolution of plant body plans. However, detailed understanding of the pathways of root evolution and the architecture of early rooting systems is currently lacking. We describe the architecture and resolve the structural homology of the rooting system of an Early Devonian basal lycophyte. Insights gained from these fossils are used to address lycophyte root evolution and homology. Methods Plant fossils are preserved as carbonaceous compressions at Cottonwood Canyon (Wyoming), in the Lochkovian–Pragian (∼411 Ma; Early Devonian) Beartooth Butte Formation. We analysed 177 rock specimens and documented morphology, cuticular anatomy and structural relationships, as well as stratigraphic position and taphonomic conditions. Key Results The rooting system of the Cottonwood Canyon lycophyte is composed of modified stems that bear fine, dichotomously branching lateral roots. These modified stems, referred to as root-bearing axes, are produced at branching points of the above-ground shoot system. Root-bearing axes preserved in growth position exhibit evidence of positive gravitropism, whereas the lateral roots extend horizontally. Consistent recurrence of these features in successive populations of the plant preserved in situ demonstrates that they represent constitutive structural traits and not opportunistic responses of a flexible developmental programme. Conclusions This is the oldest direct evidence for a rooting system preserved in growth position. These rooting systems, which can be traced to a parent plant, include some of the earliest roots known to date and demonstrate that substantial plant–substrate interactions were under way by Early Devonian time. The morphological relationships between stems, root-bearing axes and roots corroborate evidence that positive gravitropism and root identity were evolutionarily

Root evolution at the base of the lycophyte clade: insights from an Early Devonian lycophyte.

PubMed

Matsunaga, Kelly K S; Tomescu, Alexandru M F

2016-04-01

The evolution of complex rooting systems during the Devonian had significant impacts on global terrestrial ecosystems and the evolution of plant body plans. However, detailed understanding of the pathways of root evolution and the architecture of early rooting systems is currently lacking. We describe the architecture and resolve the structural homology of the rooting system of an Early Devonian basal lycophyte. Insights gained from these fossils are used to address lycophyte root evolution and homology. Plant fossils are preserved as carbonaceous compressions at Cottonwood Canyon (Wyoming), in the Lochkovian-Pragian (∼411 Ma; Early Devonian) Beartooth Butte Formation. We analysed 177 rock specimens and documented morphology, cuticular anatomy and structural relationships, as well as stratigraphic position and taphonomic conditions. The rooting system of the Cottonwood Canyon lycophyte is composed of modified stems that bear fine, dichotomously branching lateral roots. These modified stems, referred to as root-bearing axes, are produced at branching points of the above-ground shoot system. Root-bearing axes preserved in growth position exhibit evidence of positive gravitropism, whereas the lateral roots extend horizontally. Consistent recurrence of these features in successive populations of the plant preserved in situ demonstrates that they represent constitutive structural traits and not opportunistic responses of a flexible developmental programme. This is the oldest direct evidence for a rooting system preserved in growth position. These rooting systems, which can be traced to a parent plant, include some of the earliest roots known to date and demonstrate that substantial plant-substrate interactions were under way by Early Devonian time. The morphological relationships between stems, root-bearing axes and roots corroborate evidence that positive gravitropism and root identity were evolutionarily uncoupled in lycophytes, and challenge the hypothesis that

A Gradualist Scenario for Language Evolution: Precise Linguistic Reconstruction of Early Human (and Neandertal) Grammars

PubMed Central

Progovac, Ljiljana

2016-01-01

In making an argument for the antiquity of language, based on comparative evidence, Dediu and Levinson (2013) express hope that some combinations of structural features will prove so conservative that they will allow deep linguistic reconstruction. I propose that the earliest stages of syntax/grammar as reconstructed in Progovac (2015a), based on a theoretical and data-driven linguistic analysis, provide just such a conservative platform, which would have been commanded also by Neandertals and the common ancestor. I provide a fragment of this proto-grammar, which includes flat verb-noun compounds used for naming and insult (e.g., rattle-snake, cry-baby, scatter-brain), and paratactic (loose) combinations of such flat structures (e.g., Come one, come all; You seek, you find). This flat, binary, paratactic platform is found in all languages, and can be shown to serve as foundation for any further structure building. However, given the degree and nature of variation across languages in elaborating syntax beyond this proto-stage, I propose that hierarchical syntax did not emerge once and uniformly in all its complexity, but rather multiple times, either within Africa, or after dispersion from Africa. If so, then, under the uniregional hypothesis, our common ancestor with Neandertals, H. heidelbergensis, could not have commanded hierarchical syntax, but “only” the proto-grammar. Linguistic reconstructions of this kind are necessary for formulating precise and testable hypotheses regarding language evolution. In addition to the hominin timeline, this reconstruction can also engage, and negotiate between, the fields of neuroscience and genetics, as I illustrate with one specific scenario involving FOXP2 gene. PMID:27877146

Hydrogen, metals, bifurcating electrons, and proton gradients: the early evolution of biological energy conservation.

PubMed

Martin, William F

2012-03-09

Life is a persistent, self-specified set of far from equilibrium chemical reactions. In modern microbes, core carbon and energy metabolism are what keep cells alive. In very early chemical evolution, the forerunners of carbon and energy metabolism were the processes of generating reduced carbon compounds from CO(2) and the mechanisms of harnessing energy as compounds capable of doing some chemical work. The process of serpentinization at alkaline hydrothermal vents holds promise as a model for the origin of early reducing power, because Fe(2+) in the Earth's crust reduces water to H(2) and inorganic carbon to methane. The overall geochemical process of serpentinization is similar to the biochemical process of methanogenesis, and methanogenesis is similar to acetogenesis in that both physiologies allow energy conservation from the reduction of CO(2) with electrons from H(2). Electron bifurcation is a newly recognized cytosolic process that anaerobes use generate low potential electrons, it plays an important role in some forms of methanogenesis and, via speculation, possibly in acetogenesis. Electron bifurcation likely figures into the early evolution of biological energy conservation. Copyright © 2011. Published by Elsevier B.V.

The TIM Barrel Architecture Facilitated the Early Evolution of Protein-Mediated Metabolism.

PubMed

Goldman, Aaron David; Beatty, Joshua T; Landweber, Laura F

2016-01-01

The triosephosphate isomerase (TIM) barrel protein fold is a structurally repetitive architecture that is present in approximately 10% of all enzymes. It is generally assumed that this ubiquity in modern proteomes reflects an essential historical role in early protein-mediated metabolism. Here, we provide quantitative and comparative analyses to support several hypotheses about the early importance of the TIM barrel architecture. An information theoretical analysis of protein structures supports the hypothesis that the TIM barrel architecture could arise more easily by duplication and recombination compared to other mixed α/β structures. We show that TIM barrel enzymes corresponding to the most taxonomically broad superfamilies also have the broadest range of functions, often aided by metal and nucleotide-derived cofactors that are thought to reflect an earlier stage of metabolic evolution. By comparison to other putatively ancient protein architectures, we find that the functional diversity of TIM barrel proteins cannot be explained simply by their antiquity. Instead, the breadth of TIM barrel functions can be explained, in part, by the incorporation of a broad range of cofactors, a trend that does not appear to be shared by proteins in general. These results support the hypothesis that the simple and functionally general TIM barrel architecture may have arisen early in the evolution of protein biosynthesis and provided an ideal scaffold to facilitate the metabolic transition from ribozymes, peptides, and geochemical catalysts to modern protein enzymes.

The Atmospheres of the Terrestrial Planets:Clues to the Origins and Early Evolution of Venus, Earth, and Mars

NASA Technical Reports Server (NTRS)

Baines, Kevin H.; Atreya, Sushil K.; Bullock, Mark A.; Grinspoon, David H,; Mahaffy, Paul; Russell, Christopher T.; Schubert, Gerald; Zahnle, Kevin

2015-01-01

We review the current state of knowledge of the origin and early evolution of the three largest terrestrial planets - Venus, Earth, and Mars - setting the stage for the chapters on comparative climatological processes to follow. We summarize current models of planetary formation, as revealed by studies of solid materials from Earth and meteorites from Mars. For Venus, we emphasize the known differences and similarities in planetary bulk properties and composition with Earth and Mars, focusing on key properties indicative of planetary formation and early evolution, particularly of the atmospheres of all three planets. We review the need for future in situ measurements for improving our understanding of the origin and evolution of the atmospheres of our planetary neighbors and Earth, and suggest the accuracies required of such new in situ data. Finally, we discuss the role new measurements of Mars and Venus have in understanding the state and evolution of planets found in the habitable zones of other stars.

Crustal evolution of the early earth: The role of major impacts

NASA Technical Reports Server (NTRS)

Frey, H.

1979-01-01

The role of major impact basins (such as those which formed on the moon before 4 billion years ago) is examined to determine the effects of such impacts on the early crustal evolution of the earth. Specifically addressed is the fundamental problem of what is the origin of the earth's fundamental crustal dichotomy of low density continental and high density oceanic crust and its relationship to the superficially similar highlands/maria crustal dichotomies of the moon, Mercury and Mars.

Shedding light on the Early Pleistocene of TD6 (Gran Dolina, Atapuerca, Spain): The technological sequence and occupational inferences

PubMed Central

2018-01-01

This paper aims to update the information available on the lithic assemblage from the entire sequence of TD6 now that the most recent excavations have been completed, and to explore possible changes in both occupational patterns and technological strategies evidenced in the unit. This is the first study to analyse the entire TD6 sequence, including subunits TD6.3 and TD6.1, which have never been studied, along with the better-known TD6.2 Homo antecessor-bearing subunit. We also present an analysis of several lithic refits found in TD6, as well as certain technical features that may help characterise the hominin occupations. The archaeo-palaeontological record from TD6 consists of 9,452 faunal remains, 443 coprolites, 1,046 lithic pieces, 170 hominin remains and 91 Celtis seeds. The characteristics of this record seem to indicate two main stages of occupation. In the oldest subunit, TD6.3, the lithic assemblage points to the light and limited hominin occupation of the cave, which does, however, grow over the course of the level. In contrast, the lithic assemblages from TD6.2 and TD6.1 are rich and varied, which may reflect Gran Dolina cave’s establishment as a landmark in the region. Despite the occupational differences between the lowermost subunit and the rest of the deposit, technologically the TD6 lithic assemblage is extremely homogeneous throughout. In addition, the composition and spatial distribution of the 12 groups of lithic refits found in unit TD6, as well as the in situ nature of the assemblage demonstrate the high degree of preservation at the site. This may help clarify the nature of the Early Pleistocene hominin occupations of TD6, and raise reasonable doubt about the latest interpretations that support the ex situ character of the assemblage as a whole. PMID:29370188

Shedding light on the Early Pleistocene of TD6 (Gran Dolina, Atapuerca, Spain): The technological sequence and occupational inferences.

PubMed

Mosquera, Marina; Ollé, Andreu; Rodríguez-Álvarez, Xose Pedro; Carbonell, Eudald

2018-01-01

This paper aims to update the information available on the lithic assemblage from the entire sequence of TD6 now that the most recent excavations have been completed, and to explore possible changes in both occupational patterns and technological strategies evidenced in the unit. This is the first study to analyse the entire TD6 sequence, including subunits TD6.3 and TD6.1, which have never been studied, along with the better-known TD6.2 Homo antecessor-bearing subunit. We also present an analysis of several lithic refits found in TD6, as well as certain technical features that may help characterise the hominin occupations. The archaeo-palaeontological record from TD6 consists of 9,452 faunal remains, 443 coprolites, 1,046 lithic pieces, 170 hominin remains and 91 Celtis seeds. The characteristics of this record seem to indicate two main stages of occupation. In the oldest subunit, TD6.3, the lithic assemblage points to the light and limited hominin occupation of the cave, which does, however, grow over the course of the level. In contrast, the lithic assemblages from TD6.2 and TD6.1 are rich and varied, which may reflect Gran Dolina cave's establishment as a landmark in the region. Despite the occupational differences between the lowermost subunit and the rest of the deposit, technologically the TD6 lithic assemblage is extremely homogeneous throughout. In addition, the composition and spatial distribution of the 12 groups of lithic refits found in unit TD6, as well as the in situ nature of the assemblage demonstrate the high degree of preservation at the site. This may help clarify the nature of the Early Pleistocene hominin occupations of TD6, and raise reasonable doubt about the latest interpretations that support the ex situ character of the assemblage as a whole.

Endocranial morphology of Palaeocene Plesiadapis tricuspidens and evolution of the early primate brain.

PubMed

Orliac, Maeva J; Ladevèze, Sandrine; Gingerich, Philip D; Lebrun, Renaud; Smith, Thierry

2014-04-22

Expansion of the brain is a key feature of primate evolution. The fossil record, although incomplete, allows a partial reconstruction of changes in primate brain size and morphology through time. Palaeogene plesiadapoids, closest relatives of Euprimates (or crown-group primates), are crucial for understanding early evolution of the primate brain. However, brain morphology of this group remains poorly documented, and major questions remain regarding the initial phase of euprimate brain evolution. Micro-CT investigation of the endocranial morphology of Plesiadapis tricuspidens from the Late Palaeocene of Europe--the most complete plesiadapoid cranium known--shows that plesiadapoids retained a very small and simple brain. Plesiadapis has midbrain exposure, and minimal encephalization and neocorticalization, making it comparable with that of stem rodents and lagomorphs. However, Plesiadapis shares a domed neocortex and downwardly shifted olfactory-bulb axis with Euprimates. If accepted phylogenetic relationships are correct, then this implies that the euprimate brain underwent drastic reorganization during the Palaeocene, and some changes in brain structure preceded brain size increase and neocortex expansion during evolution of the primate brain.

Limb Bone Structural Proportions and Locomotor Behavior in A.L. 288-1 ("Lucy").

PubMed

Ruff, Christopher B; Burgess, M Loring; Ketcham, Richard A; Kappelman, John

2016-01-01

While there is broad agreement that early hominins practiced some form of terrestrial bipedality, there is also evidence that arboreal behavior remained a part of the locomotor repertoire in some taxa, and that bipedal locomotion may not have been identical to that of modern humans. It has been difficult to evaluate such evidence, however, because of the possibility that early hominins retained primitive traits (such as relatively long upper limbs) of little contemporaneous adaptive significance. Here we examine bone structural properties of the femur and humerus in the Australopithecus afarensis A.L. 288-1 ("Lucy", 3.2 Myr) that are known to be developmentally plastic, and compare them with other early hominins, modern humans, and modern chimpanzees. Cross-sectional images were obtained from micro-CT scans of the original specimens and used to derive section properties of the diaphyses, as well as superior and inferior cortical thicknesses of the femoral neck. A.L. 288-1 shows femoral/humeral diaphyseal strength proportions that are intermediate between those of modern humans and chimpanzees, indicating more mechanical loading of the forelimb than in modern humans, and by implication, a significant arboreal locomotor component. Several features of the proximal femur in A.L. 288-1 and other australopiths, including relative femoral head size, distribution of cortical bone in the femoral neck, and cross-sectional shape of the proximal shaft, support the inference of a bipedal gait pattern that differed slightly from that of modern humans, involving more lateral deviation of the body center of mass over the support limb, which would have entailed increased cost of terrestrial locomotion. There is also evidence consistent with increased muscular strength among australopiths in both the forelimb and hind limb, possibly reflecting metabolic trade-offs between muscle and brain development during hominin evolution. Together these findings imply significant differences in

Limb Bone Structural Proportions and Locomotor Behavior in A.L. 288-1 ("Lucy")

PubMed Central

Ruff, Christopher B.; Burgess, M. Loring; Ketcham, Richard A.; Kappelman, John

2016-01-01

While there is broad agreement that early hominins practiced some form of terrestrial bipedality, there is also evidence that arboreal behavior remained a part of the locomotor repertoire in some taxa, and that bipedal locomotion may not have been identical to that of modern humans. It has been difficult to evaluate such evidence, however, because of the possibility that early hominins retained primitive traits (such as relatively long upper limbs) of little contemporaneous adaptive significance. Here we examine bone structural properties of the femur and humerus in the Australopithecus afarensis A.L. 288–1 ("Lucy", 3.2 Myr) that are known to be developmentally plastic, and compare them with other early hominins, modern humans, and modern chimpanzees. Cross-sectional images were obtained from micro-CT scans of the original specimens and used to derive section properties of the diaphyses, as well as superior and inferior cortical thicknesses of the femoral neck. A.L. 288–1 shows femoral/humeral diaphyseal strength proportions that are intermediate between those of modern humans and chimpanzees, indicating more mechanical loading of the forelimb than in modern humans, and by implication, a significant arboreal locomotor component. Several features of the proximal femur in A.L. 288–1 and other australopiths, including relative femoral head size, distribution of cortical bone in the femoral neck, and cross-sectional shape of the proximal shaft, support the inference of a bipedal gait pattern that differed slightly from that of modern humans, involving more lateral deviation of the body center of mass over the support limb, which would have entailed increased cost of terrestrial locomotion. There is also evidence consistent with increased muscular strength among australopiths in both the forelimb and hind limb, possibly reflecting metabolic trade-offs between muscle and brain development during hominin evolution. Together these findings imply significant

Hominin Dispersal into the Nefud Desert and Middle Palaeolithic Settlement along the Jubbah Palaeolake, Northern Arabia

PubMed Central

Petraglia, Michael D.; Alsharekh, Abdullah; Breeze, Paul; Clarkson, Chris; Crassard, Rémy; Drake, Nick A.; Groucutt, Huw S.; Jennings, Richard; Parker, Adrian G.; Parton, Ash; Roberts, Richard G.; Shipton, Ceri; Matheson, Carney; al-Omari, Abdulaziz; Veall, Margaret-Ashley

2012-01-01

The Arabian Peninsula is a key region for understanding hominin dispersals and the effect of climate change on prehistoric demography, although little information on these topics is presently available owing to the poor preservation of archaeological sites in this desert environment. Here, we describe the discovery of three stratified and buried archaeological sites in the Nefud Desert, which includes the oldest dated occupation for the region. The stone tool assemblages are identified as a Middle Palaeolithic industry that includes Levallois manufacturing methods and the production of tools on flakes. Hominin occupations correspond with humid periods, particularly Marine Isotope Stages 7 and 5 of the Late Pleistocene. The Middle Palaeolithic occupations were situated along the Jubbah palaeolake-shores, in a grassland setting with some trees. Populations procured different raw materials across the lake region to manufacture stone tools, using the implements to process plants and animals. To reach the Jubbah palaeolake, Middle Palaeolithic populations travelled into the ameliorated Nefud Desert interior, possibly gaining access from multiple directions, either using routes from the north and west (the Levant and the Sinai), the north (the Mesopotamian plains and the Euphrates basin), or the east (the Persian Gulf). The Jubbah stone tool assemblages have their own suite of technological characters, but have types reminiscent of both African Middle Stone Age and Levantine Middle Palaeolithic industries. Comparative inter-regional analysis of core technology indicates morphological similarities with the Levantine Tabun C assemblage, associated with human fossils controversially identified as either Neanderthals or Homo sapiens. PMID:23185454

Early post-metamorphic, Carboniferous blastoid reveals the evolution and development of the digestive system in echinoderms.

PubMed

Rahman, Imran A; Waters, Johnny A; Sumrall, Colin D; Astolfo, Alberto

2015-10-01

Inferring the development of the earliest echinoderms is critical to uncovering the evolutionary assembly of the phylum-level body plan but has long proven problematic because early ontogenetic stages are rarely preserved as fossils. Here, we use synchrotron tomography to describe a new early post-metamorphic blastoid echinoderm from the Carboniferous (approx. 323 Ma) of China. The resulting three-dimensional reconstruction reveals a U-shaped tubular structure in the fossil interior, which is interpreted as the digestive tract. Comparisons with the developing gut of modern crinoids demonstrate that crinoids are an imperfect analogue for many extinct groups. Furthermore, consideration of our findings in a phylogenetic context allows us to reconstruct the evolution and development of the digestive system in echinoderms more broadly; there was a transition from a straight to a simple curved gut early in the phylum's evolution, but additional loops and coils of the digestive tract (as seen in crinoids) were not acquired until much later. © 2015 The Author(s).

The origin and early evolution of life on Earth.

PubMed

Oró, J; Miller, S L; Lazcano, A

1990-01-01

We do not have a detailed knowledge of the processes that led to the appearance of life on Earth. In this review we bring together some of the most important results that have provided insights into the cosmic and primitive Earth environments, particularly those environments in which life is thought to have originated. To do so, we first discuss the evidence bearing on the antiquity of life on our planet and the prebiotic significance of organic compounds found in interstellar clouds and in primitive solar system bodies such as comets, dark asteroids, and carbonaceous chondrites. This is followed by a discussion on the environmental models of the Hadean and early Archean Earth, as well as on the prebiotic formation of organic monomers and polymers essential to life. We then consider the processes that may have led to the appearance in the Archean of the first cells, and how these processes may have affected the early steps of biological evolution. Finally, the significance of these results to the study of the distribution of life in the Universe is discussed.

Large-Scale Impact Cratering and Early Earth Evolution

NASA Technical Reports Server (NTRS)

Grieve, R. A. F.; Cintala, M. J.

1997-01-01

The surface of the Moon attests to the importance of large-scale impact in its early crustal evolution. Previous models of the effects of a massive bombardment on terrestrial crustal evolution have relied on analogies with the Moon, with allowances for the presence of water and a thinner lithosphere. It is now apparent that strict lunar-terrestrial analogies are incorrect because of the "differential scaling" of crater dimensions and melt volumes with event size and planetary gravity. Impact melt volumes and "ancient cavity dimensions for specific impacts were modeled according to previous procedures. In the terrestrial case, the melt volume (V(sub m)) exceeds that of the transient cavity (V(sub tc)) at diameters > or = 400 km. This condition is reached on the Moon only with transient cavity diameters > or = 3000 km, equivalent to whole Moon melting. The melt volumes in these large impact events are minimum estimates, since, at these sizes, the higher temperature of the target rocks at depth will increase melt production. Using the modification-scaling relation of Croft, a transient cavity diameter of about 400 km in the terrestrial environment corresponds to an expected final impact "basin" diameter of about 900 km. Such a "basin" would be comparable in dimensions to the lunar basin Orientale. This 900-km "basin" on the early Earth, however, would not have had the appearance of Orientale. It would have been essentially a melt pool, and, morphologically, would have had more in common with the palimpsests structures on Callisto and Ganymede. With the terrestrial equivalents to the large multiring basins of the Moon being manifested as muted palimpsest-like structures filled with impact melt, it is unlikely they played a role in establishing the freeboard on the early Earth. The composition of the massive impact melt sheets (> 10 (exp 7) cu km) produced in "basin-forming" events on the early Earth would have most likely ranged from basaltic to more mafic for the

Body size and premolar evolution in the early-middle eocene euprimates of Wyoming.

PubMed

Jones, Katrina E; Rose, Kenneth D; Perry, Jonathan M G

2014-01-01

The earliest euprimates to arrive in North America were larger-bodied notharctids and smaller-bodied omomyids. Through the Eocene, notharctids generally continued to increase in body size, whereas omomyids generally radiated within small- and increasingly mid-sized niches in the middle Eocene. This study examines the influence of changing body size and diet on the evolution of the lower fourth premolar in Eocene euprimates. The P4 displays considerable morphological variability in these taxa. Despite the fact that most studies of primate dental morphology have focused on the molars, P4 can also provide important paleoecological insights. We analyzed the P4 from 177 euprimate specimens, representing 35 species (11 notharctids and 24 omomyids), in three time bins of approximately equal duration: early Wasatchian, late Wasatchian, and Bridgerian. Two-dimensional surface landmarks were collected from lingual photographs, capturing important variation in cusp position and tooth shape. Disparity metrics were calculated and compared for the three time bins. In the early Eocene, notharctids have a more molarized P4 than omomyids. During the Bridgerian, expanding body size range of omomyids was accompanied by a significant increase in P4 disparity and convergent evolution of the semimolariform condition in the largest omomyines. P4 morphology relates to diet in early euprimates, although patterns vary between families. Copyright © 2013 Wiley Periodicals, Inc.

Functional ecology and evolution of hominoid molar enamel thickness: Pan troglodytes schweinfurthii and Pongo pygmaeus wurmbii.

PubMed

Vogel, Erin R; van Woerden, Janneke T; Lucas, Peter W; Utami Atmoko, Sri S; van Schaik, Carel P; Dominy, Nathaniel J

2008-07-01

The divergent molar characteristics of Pan troglodytes and Pongo pygmaeus provide an instructive paradigm for examining the adaptive form-function relationship between molar enamel thickness and food hardness. Although both species exhibit a categorical preference for ripe fruit over other food objects, the thick enamel and crenulated occlusal surface of Pongo molar teeth predict a diet that is more resistant to deformation (hard) and fracture (tough) than the diet of Pan. We confirm these predictions with behavioral observations of Pan troglodytes schweinfurthii and Pongo pygmaeus wurmbii in the wild and describe the mechanical properties of foods utilized during periods when preferred foods are scarce. Such fallback foods may have exerted a selective pressure on tooth evolution, particularly molar enamel thinness, which is interpreted as a functional adaptation to seasonal folivory and a derived character trait within the hominoid clade. The thick enamel and crenulated occlusal surface of Pongo molars is interpreted as a functional adaptation to the routine consumption of relatively tough and hard foods. We discuss the implications of these interpretations for inferring the diet of hominin species, which possessed varying degrees of thick molar enamel. These data, which are among the first reported for hominoid primates, fill an important empirical void for evaluating the mechanical plausibility of putative hominin food objects.

Spatial and temporal variation of body size among early Homo.

PubMed

Will, Manuel; Stock, Jay T

2015-05-01

The estimation of body size among the earliest members of the genus Homo (2.4-1.5Myr [millions of years ago]) is central to interpretations of their biology. It is widely accepted that Homo ergaster possessed increased body size compared with Homo habilis and Homo rudolfensis, and that this may have been a factor involved with the dispersal of Homo out of Africa. The study of taxonomic differences in body size, however, is problematic. Postcranial remains are rarely associated with craniodental fossils, and taxonomic attributions frequently rest upon the size of skeletal elements. Previous body size estimates have been based upon well-preserved specimens with a more reliable species assessment. Since these samples are small (n < 5) and disparate in space and time, little is known about geographical and chronological variation in body size within early Homo. We investigate temporal and spatial variation in body size among fossils of early Homo using a 'taxon-free' approach, considering evidence for size variation from isolated and fragmentary postcranial remains (n = 39). To render the size of disparate fossil elements comparable, we derived new regression equations for common parameters of body size from a globally representative sample of hunter-gatherers and applied them to available postcranial measurements from the fossils. The results demonstrate chronological and spatial variation but no simple temporal or geographical trends for the evolution of body size among early Homo. Pronounced body size increases within Africa take place only after hominin populations were established at Dmanisi, suggesting that migrations into Eurasia were not contingent on larger body sizes. The primary evidence for these marked changes among early Homo is based upon material from Koobi Fora after 1.7Myr, indicating regional size variation. The significant body size differences between specimens from Koobi Fora and Olduvai support the cranial evidence for at least two co

Genomic Signatures of Selective Pressures and Introgression from Archaic Hominins at Human Innate Immunity Genes

PubMed Central

Deschamps, Matthieu; Laval, Guillaume; Fagny, Maud; Itan, Yuval; Abel, Laurent; Casanova, Jean-Laurent; Patin, Etienne; Quintana-Murci, Lluis

2016-01-01

Human genes governing innate immunity provide a valuable tool for the study of the selective pressure imposed by microorganisms on host genomes. A comprehensive, genome-wide study of how selective constraints and adaptations have driven the evolution of innate immunity genes is missing. Using full-genome sequence variation from the 1000 Genomes Project, we first show that innate immunity genes have globally evolved under stronger purifying selection than the remainder of protein-coding genes. We identify a gene set under the strongest selective constraints, mutations in which are likely to predispose individuals to life-threatening disease, as illustrated by STAT1 and TRAF3. We then evaluate the occurrence of local adaptation and detect 57 high-scoring signals of positive selection at innate immunity genes, variation in which has been associated with susceptibility to common infectious or autoimmune diseases. Furthermore, we show that most adaptations targeting coding variation have occurred in the last 6,000–13,000 years, the period at which populations shifted from hunting and gathering to farming. Finally, we show that innate immunity genes present higher Neandertal introgression than the remainder of the coding genome. Notably, among the genes presenting the highest Neandertal ancestry, we find the TLR6-TLR1-TLR10 cluster, which also contains functional adaptive variation in Europeans. This study identifies highly constrained genes that fulfill essential, non-redundant functions in host survival and reveals others that are more permissive to change—containing variation acquired from archaic hominins or adaptive variants in specific populations—improving our understanding of the relative biological importance of innate immunity pathways in natural conditions. PMID:26748513

Lithic Landscapes: Early Human Impact from Stone Tool Production on the Central Saharan Environment

PubMed Central

Foley, Robert A.; Lahr, Marta Mirazón

2015-01-01

Humans have had a major impact on the environment. This has been particularly intense in the last millennium but has been noticeable since the development of food production and the associated higher population densities in the last 10,000 years. The use of fire and over-exploitation of large mammals has also been recognized as having an effect on the world’s ecology, going back perhaps 100,000 years or more. Here we report on an earlier anthropogenic environmental change. The use of stone tools, which dates back over 2.5 million years, and the subsequent evolution of a technologically-dependent lineage required the exploitation of very large quantities of rock. However, measures of the impact of hominin stone exploitation are rare and inherently difficult. The Messak Settafet, a sandstone massif in the Central Sahara (Libya), is littered with Pleistocene stone tools on an unprecedented scale and is, in effect, a man-made landscape. Surveys showed that parts of the Messak Settafet have as much as 75 lithics per square metre and that this fractured debris is a dominant element of the environment. The type of stone tools—Acheulean and Middle Stone Age—indicates that extensive stone tool manufacture occurred over the last half million years or more. The lithic-strewn pavement created by this ancient stone tool manufacture possibly represents the earliest human environmental impact at a landscape scale and is an example of anthropogenic change. The nature of the lithics and inferred age may suggest that hominins other than modern humans were capable of unintentionally modifying their environment. The scale of debris also indicates the significance of stone as a critical resource for hominins and so provides insights into a novel evolutionary ecology. PMID:25760999

Gorilla and Orangutan Brains Conform to the Primate Cellular Scaling Rules: Implications for Human Evolution

PubMed Central

Herculano-Houzel, Suzana; Kaas, Jon H.

2011-01-01

Gorillas and orangutans are primates at least as large as humans, but their brains amount to about one third of the size of the human brain. This discrepancy has been used as evidence that the human brain is about 3 times larger than it should be for a primate species of its body size. In contrast to the view that the human brain is special in its size, we have suggested that it is the great apes that might have evolved bodies that are unusually large, on the basis of our recent finding that the cellular composition of the human brain matches that expected for a primate brain of its size, making the human brain a linearly scaled-up primate brain in its number of cells. To investigate whether the brain of great apes also conforms to the primate cellular scaling rules identified previously, we determine the numbers of neuronal and other cells that compose the orangutan and gorilla cerebella, use these numbers to calculate the size of the brain and of the cerebral cortex expected for these species, and show that these match the sizes described in the literature. Our results suggest that the brains of great apes also scale linearly in their numbers of neurons like other primate brains, including humans. The conformity of great apes and humans to the linear cellular scaling rules that apply to other primates that diverged earlier in primate evolution indicates that prehistoric Homo species as well as other hominins must have had brains that conformed to the same scaling rules, irrespective of their body size. We then used those scaling rules and published estimated brain volumes for various hominin species to predict the numbers of neurons that composed their brains. We predict that Homo heidelbergensis and Homo neanderthalensis had brains with approximately 80 billion neurons, within the range of variation found in modern Homo sapiens. We propose that while the cellular scaling rules that apply to the primate brain have remained stable in hominin evolution (since they

Gorilla and orangutan brains conform to the primate cellular scaling rules: implications for human evolution.

PubMed

Herculano-Houzel, Suzana; Kaas, Jon H

2011-01-01

Gorillas and orangutans are primates at least as large as humans, but their brains amount to about one third of the size of the human brain. This discrepancy has been used as evidence that the human brain is about 3 times larger than it should be for a primate species of its body size. In contrast to the view that the human brain is special in its size, we have suggested that it is the great apes that might have evolved bodies that are unusually large, on the basis of our recent finding that the cellular composition of the human brain matches that expected for a primate brain of its size, making the human brain a linearly scaled-up primate brain in its number of cells. To investigate whether the brain of great apes also conforms to the primate cellular scaling rules identified previously, we determine the numbers of neuronal and other cells that compose the orangutan and gorilla cerebella, use these numbers to calculate the size of the brain and of the cerebral cortex expected for these species, and show that these match the sizes described in the literature. Our results suggest that the brains of great apes also scale linearly in their numbers of neurons like other primate brains, including humans. The conformity of great apes and humans to the linear cellular scaling rules that apply to other primates that diverged earlier in primate evolution indicates that prehistoric Homo species as well as other hominins must have had brains that conformed to the same scaling rules, irrespective of their body size. We then used those scaling rules and published estimated brain volumes for various hominin species to predict the numbers of neurons that composed their brains. We predict that Homo heidelbergensis and Homo neanderthalensis had brains with approximately 80 billion neurons, within the range of variation found in modern Homo sapiens. We propose that while the cellular scaling rules that apply to the primate brain have remained stable in hominin evolution (since they

Young Binaries and Early Stellar Evolution

NASA Astrophysics Data System (ADS)

Brandner, Wolfgang

1996-07-01

Most main-sequence stars are members of binary or multiple systems. The same is true for pre-main-sequence (PMS) stars, as recent surveys have shown. Therefore studying star formation means to a large extent studying the formation of binary systems. Similarly, studying early stellar evolution primarily involves PMS binary systems. In this thesis I have studied the binary frequency among ROSAT selected T Tauri stars in the Chamaeleon T association and the Scorpius-Centaurus OB association, and the evolutionary status of Hα-selected PMS binaries in the T associations of Chamaeleon, Lupus, and ρ Ophiuchi. The direct imaging and spectroscopic observations in the optical have been carried out under subarcsec seeing conditions at the ESO New Technology Telescope (NTT) at La Silla. Furthermore, high-spatial resolution images of selected PMS stars in the near infrared were obtained with the ESO adaptive optics system COME-ON+/ADONIS. Among 195 T Tauri stars observed using direct imaging 31 binaries could be identified, 12 of them with subarcsec separation. Based on statistical arguments alone I conclude that almost all of them are indeed physical (i.e. gravitationally bound) binary or multiple systems. Using astrometric measurements of some binaries I showed that the components of these binaries are common proper motion pairs, very likely in a gravitationally bound orbit around each other. The overall binary frequency among T Tauri stars with a range of separations between 120 and 1800 AU is in agreement with the binary frequency observed among main-sequence stars in the solar neighbourhood. However, within individual regions the spatial distribution of binaries is non-uniform. In particular, in Upper Scorpius, weak-line T Tauri stars in the vicinity of early type stars seem to be almost devoid of multiple systems, whereas in another area in Upper Scorpius half of all weak-line T Tauri stars have a companion in a range of separation between 0.''7 and 3.''0. For a sample

Hypermagnetic helicity evolution in early universe: leptogenesis and hypermagnetic diffusion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Semikoz, V.B.; Smirnov, A.Yu.; Sokoloff, D.D., E-mail: semikoz@yandex.ru, E-mail: smirnoff.alexandr@gmail.com, E-mail: sokoloff.dd@gmail.com

2013-10-01

We study hypermagnetic helicity and lepton asymmetry evolution in plasma of the early Universe before the electroweak phase transition (EWPT) accounting for chirality flip processes via inverse Higgs decays and sphaleron transitions which violate the left lepton number and wash out the baryon asymmetry of the Universe (BAU). In the scenario where the right electron asymmetry supports the BAU alone through the conservation law B/3−L{sub eR} = const at temperatures T > T{sub RL} ≅ 10 TeV the following universe cooling leads to the production of a non-zero left lepton (electrons and neutrinos) asymmetry. This is due to the Higgsmore » decays becoming more faster when entering the equilibrium at T = T{sub RL} with the universe expansion, Γ{sub RL} ∼ T > H ∼ T{sup 2}, resulting in the parallel evolution of both the right and the left electron asymmetries at T < T{sub RL} through the corresponding Abelian anomalies in SM in the presence of a seed hypermagnetic field. The hypermagnetic helicity evolution proceeds in a self-consistent way with the lepton asymmetry growth. The role of sphaleron transitions decreasing the left lepton number turns out to be negligible in given scenario. The hypermagnetic helicity can be a supply for the magnetic one in Higgs phase assuming a strong seed hypermagnetic field in symmetric phase.« less

Early bursts of body size and shape evolution are rare in comparative data.

PubMed

Harmon, Luke J; Losos, Jonathan B; Jonathan Davies, T; Gillespie, Rosemary G; Gittleman, John L; Bryan Jennings, W; Kozak, Kenneth H; McPeek, Mark A; Moreno-Roark, Franck; Near, Thomas J; Purvis, Andy; Ricklefs, Robert E; Schluter, Dolph; Schulte Ii, James A; Seehausen, Ole; Sidlauskas, Brian L; Torres-Carvajal, Omar; Weir, Jason T; Mooers, Arne Ø

2010-08-01

George Gaylord Simpson famously postulated that much of life's diversity originated as adaptive radiations-more or less simultaneous divergences of numerous lines from a single ancestral adaptive type. However, identifying adaptive radiations has proven difficult due to a lack of broad-scale comparative datasets. Here, we use phylogenetic comparative data on body size and shape in a diversity of animal clades to test a key model of adaptive radiation, in which initially rapid morphological evolution is followed by relative stasis. We compared the fit of this model to both single selective peak and random walk models. We found little support for the early-burst model of adaptive radiation, whereas both other models, particularly that of selective peaks, were commonly supported. In addition, we found that the net rate of morphological evolution varied inversely with clade age. The youngest clades appear to evolve most rapidly because long-term change typically does not attain the amount of divergence predicted from rates measured over short time scales. Across our entire analysis, the dominant pattern was one of constraints shaping evolution continually through time rather than rapid evolution followed by stasis. We suggest that the classical model of adaptive radiation, where morphological evolution is initially rapid and slows through time, may be rare in comparative data.

Coupling of thermal evolution and despinning of early Iapetus

NASA Astrophysics Data System (ADS)

Robuchon, G.; Choblet, G.; Tobie, G.; Čadek, O.; Sotin, C.; Grasset, O.

2010-06-01

and 15 ppb, initial spin rates smaller than 8.5 h are required. For smaller values of [ 26Al], the body is too cold and viscous to acquire a significant flattening even if a rotation period close to the body disruption limit is considered. Even with a thin lithosphere during the early stage, our simulations show that Iapetus never reaches the equilibrium figure for a hydrostatic body due to the non-zero rigidity of the lithosphere. The 35 km value of the flattening is the result of the partial relaxation of an ancient larger flattening ranging between 45 and 80 km, depending on the evolution of the lithosphere thickness mainly controlled by the radiogenic content. A thin lithosphere is consistent with an early building of the equatorial ridge. The lithosphere thickening due to interior cooling can explain the preservation of the ridge throughout the remaining evolution of Iapetus.

Evolution and human sexuality.

PubMed

Gray, Peter B

2013-12-01

The aim of this review is to put core features of human sexuality in an evolutionary light. Toward that end, I address five topics concerning the evolution of human sexuality. First, I address theoretical foundations, including recent critiques and developments. While much traces back to Darwin and his view of sexual selection, more recent work helps refine the theoretical bases to sex differences and life history allocations to mating effort. Second, I consider central models attempting to specify the phylogenetic details regarding how hominin sexuality might have changed, with most of those models honing in on transitions from a possible chimpanzee-like ancestor to the slightly polygynous and long-term bonded sociosexual partnerships observed among most recently studied hunter-gatherers. Third, I address recent genetic and physiological data contributing to a refined understanding of human sexuality. As examples, the availability of rapidly increasing genomic information aids comparative approaches to discern signals of selection in sexuality-related phenotypes, and neuroendocrine studies of human responses to sexual stimuli provide insight into homologous and derived mechanisms. Fourth, I consider some of the most recent, large, and rigorous studies of human sexuality. These provide insights into sexual behavior across other national samples and on the Internet. Fifth, I discuss the relevance of a life course perspective to understanding the evolution of human sexuality. Most research on the evolution of human sexuality focuses on young adults. Yet humans are sexual beings from gestation to death, albeit in different ways across the life course, and in ways that can be theoretically couched within life history theory. Copyright © 2013 Wiley Periodicals, Inc.

Honey, Hadza, hunter-gatherers, and human evolution.

PubMed

Marlowe, Frank W; Berbesque, J Colette; Wood, Brian; Crittenden, Alyssa; Porter, Claire; Mabulla, Audax

2014-06-01

Honey is the most energy dense food in nature. It is therefore not surprising that, where it exists, honey is an important food for almost all hunter-gatherers. Here we describe and analyze widespread honey collecting among foragers and show that where it is absent, in arctic and subarctic habitats, honey bees are also rare to absent. Second, we focus on one hunter-gatherer society, the Hadza of Tanzania. Hadza men and women both rank honey as their favorite food. Hadza acquire seven types of honey. Hadza women usually acquire honey that is close to the ground while men often climb tall baobab trees to raid the largest bee hives with stinging bees. Honey accounts for a substantial proportion of the kilocalories in the Hadza diet, especially that of Hadza men. Cross-cultural forager data reveal that in most hunter-gatherers, men acquire more honey than women but often, as with the Hadza, women do acquire some. Virtually all warm-climate foragers consume honey. Our closest living relatives, the great apes, take honey when they can. We suggest that honey has been part of the diet of our ancestors dating back to at least the earliest hominins. The earliest hominins, however, would have surely been less capable of acquiring as much honey as more recent, fully modern human hunter-gatherers. We discuss reasons for thinking our early ancestors would have acquired less honey than foragers ethnographically described, yet still significantly more than our great ape relatives. Copyright © 2014 Elsevier Ltd. All rights reserved.

The early Miocene balaenid Morenocetus parvus from Patagonia (Argentina) and the evolution of right whales

PubMed Central

Cozzuol, Mario A.; Fitzgerald, Erich M.G.

2017-01-01

Balaenidae (right and bowhead whales) are a key group in understanding baleen whale evolution, because they are the oldest surviving lineage of crown Mysticeti, with a fossil record that dates back ∼20 million years. However, this record is mostly Pliocene and younger, with most of the Miocene history of the clade remaining practically unknown. The earliest recognized balaenid is the early Miocene Morenocetus parvus Cabrera, 1926 from Argentina. M. parvus was originally briefly described from two incomplete crania, a mandible and some cervical vertebrae collected from the lower Miocene Gaiman Formation of Patagonia. Since then it has not been revised, thus remaining a frequently cited yet enigmatic fossil cetacean with great potential for shedding light on the early history of crown Mysticeti. Here we provide a detailed morphological description of this taxon and revisit its phylogenetic position. The phylogenetic analysis recovered the middle Miocene Peripolocetus as the earliest diverging balaenid, and Morenocetus as the sister taxon of all other balaenids. The analysis of cranial and periotic morphology of Morenocetus suggest that some of the specialized morphological traits of modern balaenids were acquired by the early Miocene and have remained essentially unchanged up to the present. Throughout balaenid evolution, morphological changes in skull arching and ventral displacement of the orbits appear to be coupled and functionally linked to mitigating a reduction of the field of vision. The body length of Morenocetus and other extinct balaenids was estimated and the evolution of body size in Balaenidae was reconstructed. Optimization of body length on our phylogeny of Balaenidae suggests that the primitive condition was a relatively small body length represented by Morenocetus, and that gigantism has been acquired independently at least twice (in Balaena mysticetus and Eubalaena spp.), with the earliest occurrence of this trait in the late Miocene–early

Early cellular evolution.

NASA Technical Reports Server (NTRS)

Margulis, L.

1972-01-01

Study of the evolutionary developments that occurred subsequent to the origin of ancestral cells. Microbial physiology and ecology are potential sharp tools for shaping concepts of microbial evolution. Some popular unjustified assumptions are discussed. It is considered that certain principles derived mainly from the advances of molecular biology can be used to order the natural groups (genera) of extant prokaryotes and their patterns phylogenetically.

Origin and Evolution of The Early- Silurian Land Vascular Plants: Evidence From Biomarkers

NASA Astrophysics Data System (ADS)

Jin, R.

2016-12-01

Origin and early evolution of land vascular plants, is one of the most intriguing hotspots in the life science research. During the 1970s and 1980s,Pinnatiramosus qianensis was found in early-Silurian strata in guizhou of south China.43 years have passed. But so far, the biological characteristics and belonging of the age of this unique plant have been debated again and again, up in the air.Biomarkers have a good stability in the process of organic evolution, no more or less changed, so they have a special `function of mark'. While biomarkers can provide information about organic matter of hydrocarbon source rock (the source), the period of deposition and burial (diagenesis) environmental conditions, and many other aspects of information.This paper obtained the sedimentary environment, source of organic matter input and other relevant information, through extracting and analyzing biomarkers of the 26 samples in the late Ordovician to early Silurian strata in NorthGuizhou areas. According to the results, Pr/Ph of late Ordovician Meitan Fm-early Silurian Hanjiadian Fm is high.It manifests more pristane, characterized by reductive environment. At the bottom of the Hanjiadian Fm, Pr/Ph has a volatility.Some huge environmental changes may have taken place in the corresponding period. N-alkanes do not have parity advantage or has even carbon advantage slightly.The peak carbon is mainly in low carbon number.(C21 + C22)/(C28 + C29) is high.Aquatic organisms is a major source of organic matter during this period,C21-/C22+ is low.This may be caused by the relatively serious loss of light hydrocarbon during the separation of components. In the Hanjiadian Fm,information of C29/C27 sterane ratios and oleanane index showed a trend of rising at the same time, indicating that during this period, there was a gradual increase input in the number of higher plants.The stable carbon isotope of saturated hydrocarbon and aromatic hydrocarbon in the Hanjiadian Fm also gradually become

Early Evolution of Earth's Geochemical Cycle and Biosphere: Implications for Mars Exobiology

NASA Technical Reports Server (NTRS)

DesMarais, David J.; Chang, Sherwood (Technical Monitor)

1997-01-01

Carbon (C) has played multiple key roles for life and its environment. C has formed organics, greenhouse gases, aquatic pH buffers, redox buffers, and magmatic constituents affecting plutonism and volcanism. These roles interacted across a network of reservoirs and processes known as the biogeochemical C cycle. Changes in the cycle over geologic time were driven by increasing solar luminosity, declining planetary heat flow, and continental and biological evolution. The early Archean C cycle was dominated by hydrothermal alteration of crustal rocks and by thermal emanations of CO2 and reduced species (eg., H2, Fe(2+) and sulfides). Bioorganic synthesis was achieved by nonphotosynthetic CO2-fixing bacteria (chemoautotrophs) and, possibly, bacteria (organotrophs) utilizing any available nonbiological organic C. Responding both to abundant solar energy and to a longterm decline in thermal sources of chemical energy and reducing power, the blaspheme first developed anoxygenic photosynthesis, then, ultimately, oxygenic photosynthesis. O2-photosynthesis played a central role in transforming the ancient environment and blaspheme to the modem world. The geochemical C cycles of early Earth and Mars were quite similar. The principal differences between the modem C cycles of these planets arose during the later evolution of their heat flows, crusts, atmospheres and, perhaps, their blasphemes.

Chemical Evolution and the Formation of Dwarf Galaxies in the Early Universe

NASA Astrophysics Data System (ADS)

Cote, Benoit; JINA-CEE, NuGrid, ChETEC

2018-06-01

Stellar abundances in local dwarf galaxies offer a unique window into the nature and nucleosynthesis of the first stars. They also contain clues regarding how galaxies formed and assembled in the early stages of the universe. In this talk, I will present our effort to connect nuclear astrophysics with the field of galaxy formation in order to define what can be learned about galaxy evolution using stellar abundances. In particular, I will describe the current state of our numerical chemical evolution pipeline which accounts for the mass assembly history of galaxies, present how we use high-redshift cosmological hydrodynamic simulations to calibrate our models and to learn about the formation of dwarf galaxies, and address the challenge of identifying the dominant r-process site(s) using stellar abundances.

Paleoenvironmental Interpretation of drill core from Tugen Hills, Kenya through X-ray Diffraction

NASA Astrophysics Data System (ADS)

Minkara, K. E.; Rabideaux, N. M.; Deocampo, D.; Kingston, J.; Cohen, A. S.

2016-12-01

Paleoenvironmental reconstruction in regions of significant archeological and paleontological discoveries can be used to help better understand early hominin history in relation to environmental changes. Using X-ray diffraction (XRD) analysis of lacustrine sediments obtained from core material recovered during the Hominin Sites and Paleolakes Drilling Project (HSPDP) campaign at the Tugen Hills drilling site in central Kenya we can reconstruct a high-resolution record of paleoclimate and tectonics from the lake sediments during the Plio-Pleistocene. XRD analysis enables us to identify the mineralogical trends from the 227m core, which can be employed to understand the geochemical evolution of the basin. We want to test whether 23-kyr precessional cyclicity is the primary driver of environmental change at Lake Baringo, and how that change influenced vertebrate and hominin evolution. Our goals are to understand how the paleolake geochemically evolved over time and how the mineralogical characteristics are related to climate change. Preliminary results indicate discrete zones of carbonate and zeolite mineral occurrence, suggesting possible paleoclimate indicators of humidity versus aridity. Geochemical and sedimentological analysis will be required to distinguish primary lacustrine carbonate versus secondary or pedogenic carbonate, which does not carry a lacustrine signal. Quartz-rich intervals and diatomaceous sequences are distinct from zeolitic zones, suggesting variable salinities. Furthermore, hkl reflections of clay-rich bulk samples suggest varying relative abundances of kaolinite and smectite. As we extract clay fractions and analyze the clay mineralogy in further detail, this ratio may provide an indicator of paleoweathering intensity within the basin.

When should we expect early bursts of trait evolution in comparative data? Predictions from an evolutionary food web model.

PubMed

Ingram, T; Harmon, L J; Shurin, J B

2012-09-01

Conceptual models of adaptive radiation predict that competitive interactions among species will result in an early burst of speciation and trait evolution followed by a slowdown in diversification rates. Empirical studies often show early accumulation of lineages in phylogenetic trees, but usually fail to detect early bursts of phenotypic evolution. We use an evolutionary simulation model to assemble food webs through adaptive radiation, and examine patterns in the resulting phylogenetic trees and species' traits (body size and trophic position). We find that when foraging trade-offs result in food webs where all species occupy integer trophic levels, lineage diversity and trait disparity are concentrated early in the tree, consistent with the early burst model. In contrast, in food webs in which many omnivorous species feed at multiple trophic levels, high levels of turnover of species' identities and traits tend to eliminate the early burst signal. These results suggest testable predictions about how the niche structure of ecological communities may be reflected by macroevolutionary patterns. © 2012 The Authors. Journal of Evolutionary Biology © 2012 European Society For Evolutionary Biology.

A Burst of miRNA Innovation in the Early Evolution of Butterflies and Moths

PubMed Central

Quah, Shan; Hui, Jerome H.L.; Holland, Peter W.H.

2015-01-01

MicroRNAs (miRNAs) are involved in posttranscriptional regulation of gene expression. Because several miRNAs are known to affect the stability or translation of developmental regulatory genes, the origin of novel miRNAs may have contributed to the evolution of developmental processes and morphology. Lepidoptera (butterflies and moths) is a species-rich clade with a well-established phylogeny and abundant genomic resources, thereby representing an ideal system in which to study miRNA evolution. We sequenced small RNA libraries from developmental stages of two divergent lepidopterans, Cameraria ohridella (Horse chestnut Leafminer) and Pararge aegeria (Speckled Wood butterfly), discovering 90 and 81 conserved miRNAs, respectively, and many species-specific miRNA sequences. Mapping miRNAs onto the lepidopteran phylogeny reveals rapid miRNA turnover and an episode of miRNA fixation early in lepidopteran evolution, implying that miRNA acquisition accompanied the early radiation of the Lepidoptera. One lepidopteran-specific miRNA gene, miR-2768, is located within an intron of the homeobox gene invected, involved in insect segmental and wing patterning. We identified cubitus interruptus (ci) as a likely direct target of miR-2768, and validated this suppression using a luciferase assay system. We propose a model by which miR-2768 modulates expression of ci in the segmentation pathway and in patterning of lepidopteran wing primordia. PMID:25576364

Comparing the accuracy and precision of three techniques used for estimating missing landmarks when reconstructing fossil hominin crania.

PubMed

Neeser, Rudolph; Ackermann, Rebecca Rogers; Gain, James

2009-09-01

Various methodological approaches have been used for reconstructing fossil hominin remains in order to increase sample sizes and to better understand morphological variation. Among these, morphometric quantitative techniques for reconstruction are increasingly common. Here we compare the accuracy of three approaches--mean substitution, thin plate splines, and multiple linear regression--for estimating missing landmarks of damaged fossil specimens. Comparisons are made varying the number of missing landmarks, sample sizes, and the reference species of the population used to perform the estimation. The testing is performed on landmark data from individuals of Homo sapiens, Pan troglodytes and Gorilla gorilla, and nine hominin fossil specimens. Results suggest that when a small, same-species fossil reference sample is available to guide reconstructions, thin plate spline approaches perform best. However, if no such sample is available (or if the species of the damaged individual is uncertain), estimates of missing morphology based on a single individual (or even a small sample) of close taxonomic affinity are less accurate than those based on a large sample of individuals drawn from more distantly related extant populations using a technique (such as a regression method) able to leverage the information (e.g., variation/covariation patterning) contained in this large sample. Thin plate splines also show an unexpectedly large amount of error in estimating landmarks, especially over large areas. Recommendations are made for estimating missing landmarks under various scenarios. Copyright 2009 Wiley-Liss, Inc.

Comparative morphology of the hominin and African ape hyoid bone, a possible marker of the evolution of speech.

PubMed

Steele, James; Clegg, Margaret; Martelli, Sandra

2013-10-01

This study examines the morphology of the hyoid in three closely related species, Homo sapiens, Pan troglodytes, and Gorilla gorilla. Differences and similarities between the hyoids of these species are characterized and used to interpret the morphology and affi nities of the Dikika A. afarensis, Kebara 2 Neanderthal, and other fossil hominin hyoid bones. Humans and African apes are found to have distinct hyoid morphologies. In humans the maximum width across the distal tips of the articulated greater horns is usually slightly greater than the maximum length (distal greater horn tip to most anterior point of the hyoid body in the midline). A different pattern is usually found in the African ape hyoids, which have much greater maximum lengths. In humans, the hyoid body is also much more anteroposteriorly shallow in proportion to its height and width, and this is true for all age classes. The Dikika australopithecine hyoid body proportions are chimpanzeelike. A discriminant function analysis, using a larger subadult sample from the three extant species than that reported by Alemseged et al. (2006), confirms this finding. The Kebara hyoid dimensions (body alone, and articulated body and greater horns) are almost all within the observed range for human hyoids. Discriminant functions clearly distinguish human from African ape hyoids and classify the Kebara 2 hyoid as human (confirming the finding of Arensburg et al. 1989). Our virtual dissection of a chimpanzee air sac system shows its subhyoid extension into the dorsal hyoid body. Following Alemseged et al. (2006), the expanded bulla characteristic of the African ape and australopithecine hyoid body is therefore interpreted as refl ecting the presence of such a laryngeal air sac extension. Its absence in the human, Neanderthal, and H. heidelbergensis (Atapuerca SH) hyoids implicates the loss of the laryngeal air sacs as a derived Neanderthal and modern human trait, which evolved no later than the middle Pleistocene. If

Ancestral Ca2+ Signaling Machinery in Early Animal and Fungal Evolution

PubMed Central

Cai, Xinjiang; Clapham, David E.

2012-01-01

Animals and fungi diverged from a common unicellular ancestor of Opisthokonta, yet they exhibit significant differences in their components of Ca2+ signaling pathways. Many Ca2+ signaling molecules appear to be either animal-specific or fungal-specific, which is generally believed to result from lineage-specific adaptations to distinct physiological requirements. Here, by analyzing the genomic data from several close relatives of animals and fungi, we demonstrate that many components of animal and fungal Ca2+ signaling machineries are present in the apusozoan protist Thecamonas trahens, which belongs to the putative unicellular sister group to Opisthokonta. We also identify the conserved portion of Ca2+ signaling molecules in early evolution of animals and fungi following their divergence. Furthermore, our results reveal the lineage-specific expansion of Ca2+ channels and transporters in the unicellular ancestors of animals and in basal fungi. These findings provide novel insights into the evolution and regulation of Ca2+ signaling critical for animal and fungal biology. PMID:21680871

From action to language: comparative perspectives on primate tool use, gesture and the evolution of human language

PubMed Central

Steele, James; Ferrari, Pier Francesco; Fogassi, Leonardo

2012-01-01

The papers in this Special Issue examine tool use and manual gestures in primates as a window on the evolution of the human capacity for language. Neurophysiological research has supported the hypothesis of a close association between some aspects of human action organization and of language representation, in both phonology and semantics. Tool use provides an excellent experimental context to investigate analogies between action organization and linguistic syntax. Contributors report and contextualize experimental evidence from monkeys, great apes, humans and fossil hominins, and consider the nature and the extent of overlaps between the neural representations of tool use, manual gestures and linguistic processes. PMID:22106422

The minimal kinome of Giardia lamblia illuminates early kinase evolution and unique parasite biology

PubMed Central

2011-01-01

Background The major human intestinal pathogen Giardia lamblia is a very early branching eukaryote with a minimal genome of broad evolutionary and biological interest. Results To explore early kinase evolution and regulation of Giardia biology, we cataloged the kinomes of three sequenced strains. Comparison with published kinomes and those of the excavates Trichomonas vaginalis and Leishmania major shows that Giardia's 80 core kinases constitute the smallest known core kinome of any eukaryote that can be grown in pure culture, reflecting both its early origin and secondary gene loss. Kinase losses in DNA repair, mitochondrial function, transcription, splicing, and stress response reflect this reduced genome, while the presence of other kinases helps define the kinome of the last common eukaryotic ancestor. Immunofluorescence analysis shows abundant phospho-staining in trophozoites, with phosphotyrosine abundant in the nuclei and phosphothreonine and phosphoserine in distinct cytoskeletal organelles. The Nek kinase family has been massively expanded, accounting for 198 of the 278 protein kinases in Giardia. Most Neks are catalytically inactive, have very divergent sequences and undergo extensive duplication and loss between strains. Many Neks are highly induced during development. We localized four catalytically active Neks to distinct parts of the cytoskeleton and one inactive Nek to the cytoplasm. Conclusions The reduced kinome of Giardia sheds new light on early kinase evolution, and its highly divergent sequences add to the definition of individual kinase families as well as offering specific drug targets. Giardia's massive Nek expansion may reflect its distinctive lifestyle, biphasic life cycle and complex cytoskeleton. PMID:21787419

Carnivore activity in the Sima de los Huesos (Atapuerca, Spain) hominin sample

NASA Astrophysics Data System (ADS)

Sala, Nohemi; Arsuaga, Juan Luis; Martínez, Ignacio; Gracia-Téllez, Ana

2014-08-01

The Sima de los Huesos (SH) site is the largest accumulation of human remains from the Middle Pleistocene known to date. Studies in the last two decades have proposed different hypotheses to explain carnivore activity in the SH human sample. This study provides new data in order to test these different interpretations, and therefore to understand the role of the carnivores in site formation at SH. Carnivores are usually not the origin of large accumulations of hominin fossils in the Eurasian record. The results show that marks of carnivore activity in the SH sample appear very infrequently, which we interpret as indicating that carnivore activity was very sporadic at the site. This is in stark contrast with previous studies. The comparison of bone modification patterns at SH to actualistic carnivore data allows us to suggest that bears were likely to have been the carnivore responsible for the modification observed on both human and bear fossils.

Bar Evolution and Bar Properties from Disc Galaxies in the Early Universe

NASA Astrophysics Data System (ADS)

Hutchinson-Smith, Tenley; Simmons, Brooke

2017-01-01

Bars in disc galaxies indicate a large collection of stars in a specific configuration of orbits that give the galaxy center a rectangular looking feature. Astronomers have discovered that these bars affect the distribution of matter in galaxies, and are also related to galaxy stellar mass and star formation history. Little is known about the specifics of how bars evolve and drive the evolution of their host galaxies because only a handful of bars have been studied in detail so far. I have examined a sample of 8,221 barred galaxies from the early universe to identify and examine correlations with galaxy properties. The data comes from Galaxy Zoo, an online citizen science project that allows anyone to classify and measure detailed properties of galaxies. I present results including the fraction of galaxies in the sample that have bars, and the variation of galaxy properties with bar length, including galaxy color and stellar mass. I also compare these results to barred galaxies in the local universe. I will discuss the implications of these results in the context of galaxy evolution overall, including the effect of dark matter on bars and galaxy evolution.

Early-state damage detection, characterization, and evolution using high-resolution computed tomography

NASA Astrophysics Data System (ADS)

Grandin, Robert John

Safely using materials in high performance applications requires adequately understanding the mechanisms which control the nucleation and evolution of damage. Most of a material's operational life is spent in a state with noncritical damage, and, for example in metals only a small portion of its life falls within the classical Paris Law regime of crack growth. Developing proper structural health and prognosis models requires understanding the behavior of damage in these early stages within the material's life, and this early-stage damage occurs on length scales at which the material may be considered "granular'' in the sense that the discrete regions which comprise the whole are large enough to require special consideration. Material performance depends upon the characteristics of the granules themselves as well as the interfaces between granules. As a result, properly studying early-stage damage in complex, granular materials requires a means to characterize changes in the granules and interfaces. The granular-scale can range from tenths of microns in ceramics, to single microns in fiber-reinforced composites, to tens of millimeters in concrete. The difficulty of direct-study is often overcome by exhaustive testing of macro-scale damage caused by gross material loads and abuse. Such testing, for example optical or electron microscopy, destructive and further, is costly when used to study the evolution of damage within a material and often limits the study to a few snapshots. New developments in high-resolution computed tomography (HRCT) provide the necessary spatial resolution to directly image the granule length-scale of many materials. Successful application of HRCT with fiber-reinforced composites, however, requires extending the HRCT performance beyond current limits. This dissertation will discuss improvements made in the field of CT reconstruction which enable resolutions to be pushed to the point of being able to image the fiber-scale damage structures and

Elastic energy storage in the shoulder and the evolution of high-speed throwing in Homo

PubMed Central

Roach, Neil T.; Venkadesan, Madhusudhan; Rainbow, Michael J.; Lieberman, Daniel E.

2013-01-01

Although some primates, including chimpanzees, throw objects occasionally1,2, only humans regularly throw projectiles with high speed and great accuracy. Darwin noted that humans’ unique throwing abilities, made possible when bipedalism emancipated the arms, enabled foragers to effectively hunt using projectiles3. However, there has been little consideration of the evolution of throwing in the years since Darwin made his observations, in part because of a lack of evidence on when, how, and why hominins evolved the ability to generate high-speed throws4-8. Here, we show using experimental studies of throwers that human throwing capabilities largely result from several derived anatomical features that enable elastic energy storage and release at the shoulder. These features first appear together approximately two million years ago in the species Homo erectus. Given archaeological evidence that suggests hunting activity intensified around this time9, we conclude that selection for throwing in order to hunt likely played an important role in the evolution of the human genus. PMID:23803849

Phylogenetic ctDNA analysis depicts early stage lung cancer evolution

PubMed Central

Abbosh, Christopher; Birkbak, Nicolai J.; Wilson, Gareth A.; Jamal-Hanjani, Mariam; Constantin, Tudor; Salari, Raheleh; Le Quesne, John; Moore, David A; Veeriah, Selvaraju; Rosenthal, Rachel; Marafioti, Teresa; Kirkizlar, Eser; Watkins, Thomas B K; McGranahan, Nicholas; Ward, Sophia; Martinson, Luke; Riley, Joan; Fraioli, Francesco; Al Bakir, Maise; Grönroos, Eva; Zambrana, Francisco; Endozo, Raymondo; Bi, Wenya Linda; Fennessy, Fiona M.; Sponer, Nicole; Johnson, Diana; Laycock, Joanne; Shafi, Seema; Czyzewska-Khan, Justyna; Rowan, Andrew; Chambers, Tim; Matthews, Nik; Turajlic, Samra; Hiley, Crispin; Lee, Siow Ming; Forster, Martin D.; Ahmad, Tanya; Falzon, Mary; Borg, Elaine; Lawrence, David; Hayward, Martin; Kolvekar, Shyam; Panagiotopoulos, Nikolaos; Janes, Sam M; Thakrar, Ricky; Ahmed, Asia; Blackhall, Fiona; Summers, Yvonne; Hafez, Dina; Naik, Ashwini; Ganguly, Apratim; Kareht, Stephanie; Shah, Rajesh; Joseph, Leena; Quinn, Anne Marie; Crosbie, Phil; Naidu, Babu; Middleton, Gary; Langman, Gerald; Trotter, Simon; Nicolson, Marianne; Remmen, Hardy; Kerr, Keith; Chetty, Mahendran; Gomersall, Lesley; Fennell, Dean; Nakas, Apostolos; Rathinam, Sridhar; Anand, Girija; Khan, Sajid; Russell, Peter; Ezhil, Veni; Ismail, Babikir; Irvin-sellers, Melanie; Prakash, Vineet; Lester, Jason; Kornaszewska, Malgorzata; Attanoos, Richard; Adams, Haydn; Davies, Helen; Oukrif, Dahmane; Akarca, Ayse U; Hartley, John A; Lowe, Helen L; Lock, Sara; Iles, Natasha; Bell, Harriet; Ngai, Yenting; Elgar, Greg; Szallasi, Zoltan; Schwarz, Roland F; Herrero, Javier; Stewart, Aengus; Quezada, Sergio A; Peggs, Karl S.; Van Loo, Peter; Dive, Caroline; Lin, Jimmy; Rabinowitz, Matthew; Aerts, Hugo JWL; Hackshaw, Allan; Shaw, Jacqui A; Zimmermann, Bernhard G.; Swanton, Charles

2017-01-01

Summary The early detection of relapse following primary surgery for non-small cell lung cancer and the characterization of emerging subclones seeding metastatic sites might offer new therapeutic approaches to limit tumor recurrence. The potential to non-invasively track tumor evolutionary dynamics in ctDNA of early-stage lung cancer is not established. Here we conduct a tumour-specific phylogenetic approach to ctDNA profiling in the first 100 TRACERx (TRAcking non-small cell lung Cancer Evolution through therapy (Rx)) study participants, including one patient co-recruited to the PEACE (Posthumous Evaluation of Advanced Cancer Environment) post-mortem study. We identify independent predictors of ctDNA release and perform tumor volume limit of detection analyses. Through blinded profiling of post-operative plasma, we observe evidence of adjuvant chemotherapy resistance and identify patients destined to experience recurrence of their lung cancer. Finally, we show that phylogenetic ctDNA profiling tracks the subclonal nature of lung cancer relapse and metastases, providing a new approach for ctDNA driven therapeutic studies PMID:28445469

Phylogenetic ctDNA analysis depicts early-stage lung cancer evolution.

PubMed

Abbosh, Christopher; Birkbak, Nicolai J; Wilson, Gareth A; Jamal-Hanjani, Mariam; Constantin, Tudor; Salari, Raheleh; Le Quesne, John; Moore, David A; Veeriah, Selvaraju; Rosenthal, Rachel; Marafioti, Teresa; Kirkizlar, Eser; Watkins, Thomas B K; McGranahan, Nicholas; Ward, Sophia; Martinson, Luke; Riley, Joan; Fraioli, Francesco; Al Bakir, Maise; Grönroos, Eva; Zambrana, Francisco; Endozo, Raymondo; Bi, Wenya Linda; Fennessy, Fiona M; Sponer, Nicole; Johnson, Diana; Laycock, Joanne; Shafi, Seema; Czyzewska-Khan, Justyna; Rowan, Andrew; Chambers, Tim; Matthews, Nik; Turajlic, Samra; Hiley, Crispin; Lee, Siow Ming; Forster, Martin D; Ahmad, Tanya; Falzon, Mary; Borg, Elaine; Lawrence, David; Hayward, Martin; Kolvekar, Shyam; Panagiotopoulos, Nikolaos; Janes, Sam M; Thakrar, Ricky; Ahmed, Asia; Blackhall, Fiona; Summers, Yvonne; Hafez, Dina; Naik, Ashwini; Ganguly, Apratim; Kareht, Stephanie; Shah, Rajesh; Joseph, Leena; Marie Quinn, Anne; Crosbie, Phil A; Naidu, Babu; Middleton, Gary; Langman, Gerald; Trotter, Simon; Nicolson, Marianne; Remmen, Hardy; Kerr, Keith; Chetty, Mahendran; Gomersall, Lesley; Fennell, Dean A; Nakas, Apostolos; Rathinam, Sridhar; Anand, Girija; Khan, Sajid; Russell, Peter; Ezhil, Veni; Ismail, Babikir; Irvin-Sellers, Melanie; Prakash, Vineet; Lester, Jason F; Kornaszewska, Malgorzata; Attanoos, Richard; Adams, Haydn; Davies, Helen; Oukrif, Dahmane; Akarca, Ayse U; Hartley, John A; Lowe, Helen L; Lock, Sara; Iles, Natasha; Bell, Harriet; Ngai, Yenting; Elgar, Greg; Szallasi, Zoltan; Schwarz, Roland F; Herrero, Javier; Stewart, Aengus; Quezada, Sergio A; Peggs, Karl S; Van Loo, Peter; Dive, Caroline; Lin, C Jimmy; Rabinowitz, Matthew; Aerts, Hugo J W L; Hackshaw, Allan; Shaw, Jacqui A; Zimmermann, Bernhard G; Swanton, Charles

2017-04-26

The early detection of relapse following primary surgery for non-small-cell lung cancer and the characterization of emerging subclones, which seed metastatic sites, might offer new therapeutic approaches for limiting tumour recurrence. The ability to track the evolutionary dynamics of early-stage lung cancer non-invasively in circulating tumour DNA (ctDNA) has not yet been demonstrated. Here we use a tumour-specific phylogenetic approach to profile the ctDNA of the first 100 TRACERx (Tracking Non-Small-Cell Lung Cancer Evolution Through Therapy (Rx)) study participants, including one patient who was also recruited to the PEACE (Posthumous Evaluation of Advanced Cancer Environment) post-mortem study. We identify independent predictors of ctDNA release and analyse the tumour-volume detection limit. Through blinded profiling of postoperative plasma, we observe evidence of adjuvant chemotherapy resistance and identify patients who are very likely to experience recurrence of their lung cancer. Finally, we show that phylogenetic ctDNA profiling tracks the subclonal nature of lung cancer relapse and metastasis, providing a new approach for ctDNA-driven therapeutic studies.

Chloroplast Genome Evolution in Early Diverged Leptosporangiate Ferns

PubMed Central

Kim, Hyoung Tae; Chung, Myong Gi; Kim, Ki-Joong

2014-01-01

In this study, the chloroplast (cp) genome sequences from three early diverged leptosporangiate ferns were completed and analyzed in order to understand the evolution of the genome of the fern lineages. The complete cp genome sequence of Osmunda cinnamomea (Osmundales) was 142,812 base pairs (bp). The cp genome structure was similar to that of eusporangiate ferns. The gene/intron losses that frequently occurred in the cp genome of leptosporangiate ferns were not found in the cp genome of O. cinnamomea. In addition, putative RNA editing sites in the cp genome were rare in O. cinnamomea, even though the sites were frequently predicted to be present in leptosporangiate ferns. The complete cp genome sequence of Diplopterygium glaucum (Gleicheniales) was 151,007 bp and has a 9.7 kb inversion between the trnL-CAA and trnV-GCA genes when compared to O. cinnamomea. Several repeated sequences were detected around the inversion break points. The complete cp genome sequence of Lygodium japonicum (Schizaeales) was 157,142 bp and a deletion of the rpoC1 intron was detected. This intron loss was shared by all of the studied species of the genus Lygodium. The GC contents and the effective numbers of co-dons (ENCs) in ferns varied significantly when compared to seed plants. The ENC values of the early diverged leptosporangiate ferns showed intermediate levels between eusporangiate and core leptosporangiate ferns. However, our phylogenetic tree based on all of the cp gene sequences clearly indicated that the cp genome similarity between O. cinnamomea (Osmundales) and eusporangiate ferns are symplesiomorphies, rather than synapomorphies. Therefore, our data is in agreement with the view that Osmundales is a distinct early diverged lineage in the leptosporangiate ferns. PMID:24823358

Chloroplast genome evolution in early diverged leptosporangiate ferns.

PubMed

Kim, Hyoung Tae; Chung, Myong Gi; Kim, Ki-Joong

2014-05-01

In this study, the chloroplast (cp) genome sequences from three early diverged leptosporangiate ferns were completed and analyzed in order to understand the evolution of the genome of the fern lineages. The complete cp genome sequence of Osmunda cinnamomea (Osmundales) was 142,812 base pairs (bp). The cp genome structure was similar to that of eusporangiate ferns. The gene/intron losses that frequently occurred in the cp genome of leptosporangiate ferns were not found in the cp genome of O. cinnamomea. In addition, putative RNA editing sites in the cp genome were rare in O. cinnamomea, even though the sites were frequently predicted to be present in leptosporangiate ferns. The complete cp genome sequence of Diplopterygium glaucum (Gleicheniales) was 151,007 bp and has a 9.7 kb inversion between the trnL-CAA and trnVGCA genes when compared to O. cinnamomea. Several repeated sequences were detected around the inversion break points. The complete cp genome sequence of Lygodium japonicum (Schizaeales) was 157,142 bp and a deletion of the rpoC1 intron was detected. This intron loss was shared by all of the studied species of the genus Lygodium. The GC contents and the effective numbers of codons (ENCs) in ferns varied significantly when compared to seed plants. The ENC values of the early diverged leptosporangiate ferns showed intermediate levels between eusporangiate and core leptosporangiate ferns. However, our phylogenetic tree based on all of the cp gene sequences clearly indicated that the cp genome similarity between O. cinnamomea (Osmundales) and eusporangiate ferns are symplesiomorphies, rather than synapomorphies. Therefore, our data is in agreement with the view that Osmundales is a distinct early diverged lineage in the leptosporangiate ferns.

The emergence and early evolution of biological carbon-fixation.

PubMed

Braakman, Rogier; Smith, Eric

2012-01-01

The fixation of CO₂ into living matter sustains all life on Earth, and embeds the biosphere within geochemistry. The six known chemical pathways used by extant organisms for this function are recognized to have overlaps, but their evolution is incompletely understood. Here we reconstruct the complete early evolutionary history of biological carbon-fixation, relating all modern pathways to a single ancestral form. We find that innovations in carbon-fixation were the foundation for most major early divergences in the tree of life. These findings are based on a novel method that fully integrates metabolic and phylogenetic constraints. Comparing gene-profiles across the metabolic cores of deep-branching organisms and requiring that they are capable of synthesizing all their biomass components leads to the surprising conclusion that the most common form for deep-branching autotrophic carbon-fixation combines two disconnected sub-networks, each supplying carbon to distinct biomass components. One of these is a linear folate-based pathway of CO₂ reduction previously only recognized as a fixation route in the complete Wood-Ljungdahl pathway, but which more generally may exclude the final step of synthesizing acetyl-CoA. Using metabolic constraints we then reconstruct a "phylometabolic" tree with a high degree of parsimony that traces the evolution of complete carbon-fixation pathways, and has a clear structure down to the root. This tree requires few instances of lateral gene transfer or convergence, and instead suggests a simple evolutionary dynamic in which all divergences have primary environmental causes. Energy optimization and oxygen toxicity are the two strongest forces of selection. The root of this tree combines the reductive citric acid cycle and the Wood-Ljungdahl pathway into a single connected network. This linked network lacks the selective optimization of modern fixation pathways but its redundancy leads to a more robust topology, making it more

Knuckle-walking anteater: a convergence test of adaptation for purported knuckle-walking features of African Hominidae.

PubMed

Orr, Caley M

2005-11-01

Appeals to synapomorphic features of the wrist and hand in African apes, early hominins, and modern humans as evidence of knuckle-walking ancestry for the hominin lineage rely on accurate interpretations of those features as adaptations to knuckle-walking locomotion. Because Gorilla, Pan, and Homo share a relatively close common ancestor, the interpretation of such features is confounded somewhat by phylogeny. The study presented here examines the evolution of a similar locomotor regime in New World anteaters (order Xenarthra, family Myrmecophagidae) and uses the terrestrial giant anteater (Myrmecophaga tridactyla) as a convergence test of adaptation for purported knuckle-walking features of the Hominidae. During the stance phase of locomotion, Myrmecophaga transmits loads through flexed digits and a vertical manus, with hyperextension occurring at the metacarpophalangeal joints of the weight-bearing rays. This differs from the locomotion of smaller, arboreal anteaters of outgroup genera Tamandua and Cyclopes that employ extended wrist postures during above-branch quadrupedality. A number of features shared by Myrmecophaga and Pan and Gorilla facilitate load transmission or limit extension, thereby stabilizing the wrist and hand during knuckle-walking, and distinguish these taxa from their respective outgroups. These traits are a distally extended dorsal ridge of the distal radius, proximal expansion of the nonarticular surface of the dorsal capitate, a pronounced articular ridge on the dorsal aspects of the load-bearing metacarpal heads, and metacarpal heads that are wider dorsally than volarly. Only the proximal expansion of the nonarticular area of the dorsal capitate distinguishes knuckle-walkers from digitigrade cercopithecids, but features shared with digitigrade primates might be adaptive to the use of a vertical manus of some sort in the stance phase of terrestrial locomotion. The appearance of capitate nonarticular expansion and the dorsal ridge of the

Fossil scales illuminate the early evolution of lepidopterans and structural colors

PubMed Central

Zhang, Qingqing; Starkey, Timothy A.; McNamara, Maria E.; Jarzembowski, Edmund A.; Kelly, Richard; Ren, Xiaoyin; Chen, Jun; Zhang, Haichun

2018-01-01

Lepidopteran scales exhibit remarkably complex ultrastructures, many of which produce structural colors that are the basis for diverse communication strategies. Little is known, however, about the early evolution of lepidopteran scales and their photonic structures. We report scale architectures from Jurassic Lepidoptera from the United Kingdom, Germany, Kazakhstan, and China and from Tarachoptera (a stem group of Amphiesmenoptera) from mid-Cretaceous Burmese amber. The Jurassic lepidopterans exhibit a type 1 bilayer scale vestiture: an upper layer of large fused cover scales and a lower layer of small fused ground scales. This scale arrangement, plus preserved herringbone ornamentation on the cover scale surface, is almost identical to those of some extant Micropterigidae. Critically, the fossil scale ultrastructures have periodicities measuring from 140 to 2000 nm and are therefore capable of scattering visible light, providing the earliest evidence of structural colors in the insect fossil record. Optical modeling confirms that diffraction-related scattering mechanisms dominate the photonic properties of the fossil cover scales, which would have displayed broadband metallic hues as in numerous extant Micropterigidae. The fossil tarachopteran scales exhibit a unique suite of characteristics, including small size, elongate-spatulate shape, ridged ornamentation, and irregular arrangement, providing novel insight into the early evolution of lepidopteran scales. Combined, our results provide the earliest evidence for structural coloration in fossil lepidopterans and support the hypothesis that fused wing scales and the type 1 bilayer covering are groundplan features of the group. Wing scales likely had deep origins in earlier amphiesmenopteran lineages before the appearance of the Lepidoptera. PMID:29651455

Fossil scales illuminate the early evolution of lepidopterans and structural colors.

PubMed

Zhang, Qingqing; Mey, Wolfram; Ansorge, Jörg; Starkey, Timothy A; McDonald, Luke T; McNamara, Maria E; Jarzembowski, Edmund A; Wichard, Wilfried; Kelly, Richard; Ren, Xiaoyin; Chen, Jun; Zhang, Haichun; Wang, Bo

2018-04-01

Lepidopteran scales exhibit remarkably complex ultrastructures, many of which produce structural colors that are the basis for diverse communication strategies. Little is known, however, about the early evolution of lepidopteran scales and their photonic structures. We report scale architectures from Jurassic Lepidoptera from the United Kingdom, Germany, Kazakhstan, and China and from Tarachoptera (a stem group of Amphiesmenoptera) from mid-Cretaceous Burmese amber. The Jurassic lepidopterans exhibit a type 1 bilayer scale vestiture: an upper layer of large fused cover scales and a lower layer of small fused ground scales. This scale arrangement, plus preserved herringbone ornamentation on the cover scale surface, is almost identical to those of some extant Micropterigidae. Critically, the fossil scale ultrastructures have periodicities measuring from 140 to 2000 nm and are therefore capable of scattering visible light, providing the earliest evidence of structural colors in the insect fossil record. Optical modeling confirms that diffraction-related scattering mechanisms dominate the photonic properties of the fossil cover scales, which would have displayed broadband metallic hues as in numerous extant Micropterigidae. The fossil tarachopteran scales exhibit a unique suite of characteristics, including small size, elongate-spatulate shape, ridged ornamentation, and irregular arrangement, providing novel insight into the early evolution of lepidopteran scales. Combined, our results provide the earliest evidence for structural coloration in fossil lepidopterans and support the hypothesis that fused wing scales and the type 1 bilayer covering are groundplan features of the group. Wing scales likely had deep origins in earlier amphiesmenopteran lineages before the appearance of the Lepidoptera.

Early evolution of the venom system in lizards and snakes.

PubMed

Fry, Bryan G; Vidal, Nicolas; Norman, Janette A; Vonk, Freek J; Scheib, Holger; Ramjan, S F Ryan; Kuruppu, Sanjaya; Fung, Kim; Hedges, S Blair; Richardson, Michael K; Hodgson, Wayne C; Ignjatovic, Vera; Summerhayes, Robyn; Kochva, Elazar

2006-02-02

Among extant reptiles only two lineages are known to have evolved venom delivery systems, the advanced snakes and helodermatid lizards (Gila Monster and Beaded Lizard). Evolution of the venom system is thought to underlie the impressive radiation of the advanced snakes (2,500 of 3,000 snake species). In contrast, the lizard venom system is thought to be restricted to just two species and to have evolved independently from the snake venom system. Here we report the presence of venom toxins in two additional lizard lineages (Monitor Lizards and Iguania) and show that all lineages possessing toxin-secreting oral glands form a clade, demonstrating a single early origin of the venom system in lizards and snakes. Construction of gland complementary-DNA libraries and phylogenetic analysis of transcripts revealed that nine toxin types are shared between lizards and snakes. Toxinological analyses of venom components from the Lace Monitor Varanus varius showed potent effects on blood pressure and clotting ability, bioactivities associated with a rapid loss of consciousness and extensive bleeding in prey. The iguanian lizard Pogona barbata retains characteristics of the ancestral venom system, namely serial, lobular non-compound venom-secreting glands on both the upper and lower jaws, whereas the advanced snakes and anguimorph lizards (including Monitor Lizards, Gila Monster and Beaded Lizard) have more derived venom systems characterized by the loss of the mandibular (lower) or maxillary (upper) glands. Demonstration that the snakes, iguanians and anguimorphs form a single clade provides overwhelming support for a single, early origin of the venom system in lizards and snakes. These results provide new insights into the evolution of the venom system in squamate reptiles and open new avenues for biomedical research and drug design using hitherto unexplored venom proteins.

Craniomandibular form and body size variation of first generation mouse hybrids: A model for hominin hybridization.

PubMed

Warren, Kerryn A; Ritzman, Terrence B; Humphreys, Robyn A; Percival, Christopher J; Hallgrímsson, Benedikt; Ackermann, Rebecca Rogers

2018-03-01

Hybridization occurs in a number of mammalian lineages, including among primate taxa. Analyses of ancient genomes have shown that hybridization between our lineage and other archaic hominins in Eurasia occurred numerous times in the past. However, we still have limited empirical data on what a hybrid skeleton looks like, or how to spot patterns of hybridization among fossils for which there are no genetic data. Here we use experimental mouse models to supplement previous studies of primates. We characterize size and shape variation in the cranium and mandible of three wild-derived inbred mouse strains and their first generation (F 1 ) hybrids. The three parent taxa in our analysis represent lineages that diverged over approximately the same period as the human/Neanderthal/Denisovan lineages and their hybrids are variably successful in the wild. Comparisons of body size, as quantified by long bone measurements, are also presented to determine whether the identified phenotypic effects of hybridization are localized to the cranium or represent overall body size changes. The results indicate that hybrid cranial and mandibular sizes, as well as limb length, exceed that of the parent taxa in all cases. All three F 1 hybrid crosses display similar patterns of size and form variation. These results are generally consistent with earlier studies on primates and other mammals, suggesting that the effects of hybridization may be similar across very different scenarios of hybridization, including different levels of hybrid fitness. This paper serves to supplement previous studies aimed at identifying F 1 hybrids in the fossil record and to introduce further research that will explore hybrid morphologies using mice as a proxy for better understanding hybridization in the hominin fossil record. Copyright © 2017 Elsevier Ltd. All rights reserved.

The age of the hominin fossils from Jebel Irhoud, Morocco, and the origins of the Middle Stone Age.

PubMed

Richter, Daniel; Grün, Rainer; Joannes-Boyau, Renaud; Steele, Teresa E; Amani, Fethi; Rué, Mathieu; Fernandes, Paul; Raynal, Jean-Paul; Geraads, Denis; Ben-Ncer, Abdelouahed; Hublin, Jean-Jacques; McPherron, Shannon P

2017-06-07

The timing and location of the emergence of our species and of associated behavioural changes are crucial for our understanding of human evolution. The earliest fossil attributed to a modern form of Homo sapiens comes from eastern Africa and is approximately 195 thousand years old, therefore the emergence of modern human biology is commonly placed at around 200 thousand years ago. The earliest Middle Stone Age assemblages come from eastern and southern Africa but date much earlier. Here we report the ages, determined by thermoluminescence dating, of fire-heated flint artefacts obtained from new excavations at the Middle Stone Age site of Jebel Irhoud, Morocco, which are directly associated with newly discovered remains of H. sapiens. A weighted average age places these Middle Stone Age artefacts and fossils at 315 ± 34 thousand years ago. Support is obtained through the recalculated uranium series with electron spin resonance date of 286 ± 32 thousand years ago for a tooth from the Irhoud 3 hominin mandible. These ages are also consistent with the faunal and microfaunal assemblages and almost double the previous age estimates for the lower part of the deposits. The north African site of Jebel Irhoud contains one of the earliest directly dated Middle Stone Age assemblages, and its associated human remains are the oldest reported for H. sapiens. The emergence of our species and of the Middle Stone Age appear to be close in time, and these data suggest a larger scale, potentially pan-African, origin for both.

Evolution of domain walls in the early universe. Ph.D. Thesis - Chicago Univ.

NASA Technical Reports Server (NTRS)

Kawano, Lawrence

1989-01-01

The evolution of domain walls in the early universe is studied via 2-D computer simulation. The walls are initially configured on a triangular lattice and then released from the lattice, their evolution driven by wall curvature and by the universal expansion. The walls attain an average velocity of about 0.3c and their surface area per volume (as measured in comoving coordinates) goes down with a slope of -1 with respect to conformal time, regardless of whether the universe is matter or radiation dominated. The additional influence of vacuum pressure causes the energy density to fall away from this slope and steepen, thus allowing a situation in which domain walls can constitute a significant portion of the energy density of the universe without provoking an unacceptably large perturbation upon the microwave background.

Major transitions in the evolution of early land plants: a bryological perspective

PubMed Central

Ligrone, Roberto; Duckett, Jeffrey G.; Renzaglia, Karen S.

2012-01-01

Background Molecular phylogeny has resolved the liverworts as the earliest-divergent clade of land plants and mosses as the sister group to hornworts plus tracheophytes, with alternative topologies resolving the hornworts as sister to mosses plus tracheophytes less well supported. The tracheophytes plus fossil plants putatively lacking lignified vascular tissue form the polysporangiophyte clade. Scope This paper reviews phylogenetic, developmental, anatomical, genetic and paleontological data with the aim of reconstructing the succession of events that shaped major land plant lineages. Conclusions Fundamental land plant characters primarily evolved in the bryophyte grade, and hence the key to a better understanding of the early evolution of land plants is in bryophytes. The last common ancestor of land plants was probably a leafless axial gametophyte bearing simple unisporangiate sporophytes. Water-conducting tissue, if present, was restricted to the gametophyte and presumably consisted of perforate cells similar to those in the early-divergent bryophytes Haplomitrium and Takakia. Stomata were a sporophyte innovation with the possible ancestral functions of producing a transpiration-driven flow of water and solutes from the parental gametophyte and facilitating spore separation before release. Stomata in mosses, hornworts and polysporangiophytes are viewed as homologous, and hence these three lineages are collectively referred to as the ‘stomatophytes’. An indeterminate sporophyte body (the sporophyte shoot) developing from an apical meristem was the key innovation in polysporangiophytes. Poikilohydry is the ancestral condition in land plants; homoiohydry evolved in the sporophyte of polysporangiophytes. Fungal symbiotic associations ancestral to modern arbuscular mycorrhizas evolved in the gametophytic generation before the separation of major present-living lineages. Hydroids are imperforate water-conducting cells specific to advanced mosses. Xylem vascular

Leaf evolution in early-diverging ferns: insights from a new fern-like plant from the Late Devonian of China

PubMed Central

Wang, De-Ming; Xu, Hong-He; Xue, Jin-Zhuang; Wang, Qi; Liu, Le

2015-01-01

Background and Aims With the exception of angiosperms, the main euphyllophyte lineages (i.e. ferns sensu lato, progymnosperms and gymnosperms) had evolved laminate leaves by the Late Devonian. The evolution of laminate leaves, however, remains unclear for early-diverging ferns, largely represented by fern-like plants. This study presents a novel fern-like taxon with pinnules, which provides new insights into the early evolution of laminate leaves in early-diverging ferns. Methods Macrofossil specimens were collected from the Upper Devonian (Famennian) Wutong Formation of Anhui and Jiangsu Provinces, South China. A standard degagement technique was employed to uncover compressed plant portions within the rock matrix. Key Results A new fern-like taxon, Shougangia bella gen. et sp. nov., is described and represents an early-diverging fern with highly derived features. It has a partially creeping stem with adventitious roots only on one side, upright primary and secondary branches arranged in helices, tertiary branches borne alternately or (sub)oppositely, laminate and usually lobed leaves with divergent veins, and complex fertile organs terminating tertiary branches and possessing multiple divisions and numerous terminal sporangia. Conclusions Shougangia bella provides unequivocal fossil evidence for laminate leaves in early-diverging ferns. It suggests that fern-like plants, along with other euphyllophyte lineages, had independently evolved megaphylls by the Late Devonian, possibly in response to a significant decline in atmospheric CO2 concentration. Among fern-like plants, planate ultimate appendages are homologous with laminate pinnules, and in the evolution of megaphylls, fertile organs tend to become complex. PMID:25979918

Evolution of CO2 and H2O on Mars: A cold Early History?

NASA Technical Reports Server (NTRS)

Niles, P. B.; Michalski, J.

2011-01-01

The martian climate has long been thought to have evolved substantially through history from a warm and wet period to the current cold and dry conditions on the martian surface. This view has been challenged based primarily on evidence that the early Sun had a substantially reduced luminosity and that a greenhouse atmosphere would be difficult to sustain on Mars for long periods of time. In addition, the evidence for a warm, wet period of martian history is far from conclusive with many of the salient features capable of being explained by an early cold climate. An important test of the warm, wet early Mars hypothesis is the abundance of carbonates in the crust [1]. Recent high precision isotopic measurements of the martian atmosphere and discoveries of carbonates on the martian surface provide new constraints on the evolution of the martian atmosphere. This work seeks to apply these constraints to test the feasibility of the cold early scenario

Question 7: Comparative Genomics and Early Cell Evolution: A Cautionary Methodological Note

NASA Astrophysics Data System (ADS)

Islas, Sara; Hernández-Morales, Ricardo; Lazcano, Antonio

2007-10-01

Inventories of the gene content of the last common ancestor (LCA), i.e., the cenancestor, include sequences that may have undergone horizontal transfer events, as well as sequences that have originated in different pre-cenancestral epochs. However, the universal distribution of highly conserved genes involved in RNA metabolism provide insights into early stages of cell evolution during which RNA played a much more conspicuous biological role, and is consistent with the hypothesis that extant living systems were preceded by an RNA/protein world. Insights into the traits of primitive entities from which the LCA evolved may be derived from the analysis of paralogous gene families, including those formed by sequences that resulted from internal elongation events. Three major types of paralogous gene families can be recognized. The importance of this grouping for understanding the traits of early cells is discussed.

The Moon as a recorder of organic evolution in the early solar system: a lunar regolith analog study.

PubMed

Matthewman, Richard; Court, Richard W; Crawford, Ian A; Jones, Adrian P; Joy, Katherine H; Sephton, Mark A

2015-02-01

The organic record of Earth older than ∼3.8 Ga has been effectively erased. Some insight is provided to us by meteorites as well as remote and direct observations of asteroids and comets left over from the formation of the Solar System. These primitive objects provide a record of early chemical evolution and a sample of material that has been delivered to Earth's surface throughout the past 4.5 billion years. Yet an effective chronicle of organic evolution on all Solar System objects, including that on planetary surfaces, is more difficult to find. Fortunately, early Earth would not have been the only recipient of organic matter-containing objects in the early Solar System. For example, a recently proposed model suggests the possibility that volatiles, including organic material, remain archived in buried paleoregolith deposits intercalated with lava flows on the Moon. Where asteroids and comets allow the study of processes before planet formation, the lunar record could extend that chronicle to early biological evolution on the planets. In this study, we use selected free and polymeric organic materials to assess the hypothesis that organic matter can survive the effects of heating in the lunar regolith by overlying lava flows. Results indicate that the presence of lunar regolith simulant appears to promote polymerization and, therefore, preservation of organic matter. Once polymerized, the mineral-hosted newly formed organic network is relatively protected from further thermal degradation. Our findings reveal the thermal conditions under which preservation of organic matter on the Moon is viable.

Evidence of a chimpanzee-sized ancestor of humans but a gibbon-sized ancestor of apes.

PubMed

Grabowski, Mark; Jungers, William L

2017-10-12

Body mass directly affects how an animal relates to its environment and has a wide range of biological implications. However, little is known about the mass of the last common ancestor (LCA) of humans and chimpanzees, hominids (great apes and humans), or hominoids (all apes and humans), which is needed to evaluate numerous paleobiological hypotheses at and prior to the root of our lineage. Here we use phylogenetic comparative methods and data from primates including humans, fossil hominins, and a wide sample of fossil primates including Miocene apes from Africa, Europe, and Asia to test alternative hypotheses of body mass evolution. Our results suggest, contrary to previous suggestions, that the LCA of all hominoids lived in an environment that favored a gibbon-like size, but a series of selective regime shifts, possibly due to resource availability, led to a decrease and then increase in body mass in early hominins from a chimpanzee-sized LCA.The pattern of body size evolution in hominids can provide insight into historical human ecology. Here, Grabowski and Jungers use comparative phylogenetic analysis to reconstruct the likely size of the ancestor of humans and chimpanzees and the evolutionary history of selection on body size in primates.

Ecological variation in South American geophagine cichlids arose during an early burst of adaptive morphological and functional evolution

PubMed Central

Arbour, Jessica Hilary; López-Fernández, Hernán

2013-01-01

Diversity and disparity are unequally distributed both phylogenetically and geographically. This uneven distribution may be owing to differences in diversification rates between clades resulting from processes such as adaptive radiation. We examined the rate and distribution of evolution in feeding biomechanics in the extremely diverse and continentally distributed South American geophagine cichlids. Evolutionary patterns in multivariate functional morphospace were examined using a phylomorphospace approach, disparity-through-time analyses and by comparing Brownian motion (BM) and adaptive peak evolutionary models using maximum likelihood. The most species-rich and functionally disparate clade (CAS) expanded more efficiently in morphospace and evolved more rapidly compared with both BM expectations and its sister clade (GGD). Members of the CAS clade also exhibited an early burst in functional evolution that corresponds to the development of modern ecological roles and may have been related to the colonization of a novel adaptive peak characterized by fast oral jaw mechanics. Furthermore, reduced ecological opportunity following this early burst may have restricted functional evolution in the GGD clade, which is less species-rich and more ecologically specialized. Patterns of evolution in ecologically important functional traits are consistent with a pattern of adaptive radiation within the most diverse clade of Geophagini. PMID:23740780

A revision of hominin fossil teeth from Fontana Ranuccio (Middle Pleistocene, Anagni, Frosinone, Italy).

PubMed

Rubini, Mauro; Cerroni, Vittorio; Festa, Giulia; Sardella, Raffaele; Zaio, Paola

2014-12-01

The Fontana Ranuccio hominin teeth (FR, Latium, Italy) are dated to the Middle Pleistocene. In previous studies these teeth were classified as two lower (left and right) second molars, one lower left central incisor and a badly worn incisor crown, the exact position of which could not be determined. In 2012 these remains were acquired by the Anthropological Service of S.B.A.L. (Italian Ministry of Culture) and for this reason re-analysed. In a thorough revision we have reassessed them both morphologically and dimensionally as two lower (left and right) first molars, one lower left lateral incisor and a possible upper left canine. The comparison with penecontemporaneous and diachronic samples shows that the Fontana Ranuccio teeth are morphologically similar to Atapuerca-Sima de los Huesos, Arago XIII and Neanderthal samples. Copyright © 2014 Elsevier Ltd. All rights reserved.

Novel scenarios of early animal evolution--is it time to rewrite textbooks?

PubMed

Dohrmann, Martin; Wörheide, Gert

2013-09-01

Understanding how important phenotypic, developmental, and genomic features of animals originated and evolved is essential for many fields of biological research, but such understanding depends on robust hypotheses about the phylogenetic interrelationships of the higher taxa to which the studied species belong. Molecular approaches to phylogenetics have proven able to revolutionize our knowledge of organismal evolution. However, with respect to the deepest splits in the metazoan Tree of Life-the relationships between Bilateria and the four non-bilaterian phyla (Porifera, Placozoa, Ctenophora, and Cnidaria)-no consensus has been reached yet, since a number of different, often contradictory, hypotheses with sometimes spectacular implications have been proposed in recent years. Here, we review the recent literature on the topic and contrast it with more classical perceptions based on analyses of morphological characters. We conclude that the time is not yet ripe to rewrite zoological textbooks and advocate a conservative approach when it comes to developing scenarios of the early evolution of animals.

Origin and early evolution of photosynthetic eukaryotes in freshwater environments: reinterpreting proterozoic paleobiology and biogeochemical processes in light of trait evolution.

PubMed

Blank, Carrine E

2013-12-01

Phylogenetic analyses were performed on concatenated data sets of 31 genes and 11,789 unambiguously alignable characters from 37 cyanobacterial and 35 chloroplast genomes. The plastid lineage emerged somewhat early in the cyanobacterial tree, at a time when Cyanobacteria were likely unicellular and restricted to freshwater ecosystems. Using relaxed molecular clocks and 22 age constraints spanning cyanobacterial and eukaryote nodes, the common ancestor to the photosynthetic eukaryotes was predicted to have also inhabited freshwater environments around the time that oxygen appeared in the atmosphere (2.0-2.3 Ga). Early diversifications within each of the three major plastid clades were also inferred to have occurred in freshwater environments, through the late Paleoproterozoic and into the middle Mesoproterozoic. The colonization of marine environments by photosynthetic eukaryotes may not have occurred until after the middle Mesoproterozoic (1.2-1.5 Ga). The evolutionary hypotheses proposed here predict that early photosynthetic eukaryotes may have never experienced the widespread anoxia or euxinia suggested to have characterized marine environments in the Paleoproterozoic to early Mesoproterozoic. It also proposes that earliest acritarchs (1.5-1.7 Ga) may have been produced by freshwater taxa. This study highlights how the early evolution of habitat preference in photosynthetic eukaryotes, along with Cyanobacteria, could have contributed to changing biogeochemical conditions on the early Earth. © 2013 Phycological Society of America.

A reassessment of the early archaeological record at Leang Burung 2, a Late Pleistocene rock-shelter site on the Indonesian island of Sulawesi

PubMed Central

Hakim, Budianto; Ramli, Muhammad; Aubert, Maxime; van den Bergh, Gerrit D.; Li, Bo; Burhan, Basran; Saiful, Andi Muhammad; Siagian, Linda; Sardi, Ratno; Jusdi, Andi; Abdullah; Mubarak, Andi Pampang; Moore, Mark W.; Roberts, Richard G.; Zhao, Jian-xin; McGahan, David; Jones, Brian G.; Perston, Yinika; Szabó, Katherine; Mahmud, M. Irfan; Westaway, Kira; Jatmiko; Saptomo, E. Wahyu; van der Kaars, Sander; Grün, Rainer; Wood, Rachel; Dodson, John

2018-01-01

This paper presents a reassessment of the archaeological record at Leang Burung 2, a key early human occupation site in the Late Pleistocene of Southeast Asia. Excavated originally by Ian Glover in 1975, this limestone rock-shelter in the Maros karsts of Sulawesi, Indonesia, has long held significance in our understanding of early human dispersals into ‘Wallacea’, the vast zone of oceanic islands between continental Asia and Australia. We present new stratigraphic information and dating evidence from Leang Burung 2 collected during the course of our excavations at this site in 2007 and 2011–13. Our findings suggest that the classic Late Pleistocene modern human occupation sequence identified previously at Leang Burung 2, and proposed to span around 31,000 to 19,000 conventional 14C years BP (~35–24 ka cal BP), may actually represent an amalgam of reworked archaeological materials. Sources for cultural materials of mixed ages comprise breccias from the rear wall of the rock-shelter–remnants of older, eroded deposits dated to 35–23 ka cal BP–and cultural remains of early Holocene antiquity. Below the upper levels affected by the mass loss of Late Pleistocene deposits, our deep-trench excavations uncovered evidence for an earlier hominin presence at the site. These findings include fossils of now-extinct proboscideans and other ‘megafauna’ in stratified context, as well as a cobble-based stone artifact technology comparable to that produced by late Middle Pleistocene hominins elsewhere on Sulawesi. PMID:29641524

A reassessment of the early archaeological record at Leang Burung 2, a Late Pleistocene rock-shelter site on the Indonesian island of Sulawesi.

PubMed

Brumm, Adam; Hakim, Budianto; Ramli, Muhammad; Aubert, Maxime; van den Bergh, Gerrit D; Li, Bo; Burhan, Basran; Saiful, Andi Muhammad; Siagian, Linda; Sardi, Ratno; Jusdi, Andi; Abdullah; Mubarak, Andi Pampang; Moore, Mark W; Roberts, Richard G; Zhao, Jian-Xin; McGahan, David; Jones, Brian G; Perston, Yinika; Szabó, Katherine; Mahmud, M Irfan; Westaway, Kira; Jatmiko; Saptomo, E Wahyu; van der Kaars, Sander; Grün, Rainer; Wood, Rachel; Dodson, John; Morwood, Michael J

2018-01-01

This paper presents a reassessment of the archaeological record at Leang Burung 2, a key early human occupation site in the Late Pleistocene of Southeast Asia. Excavated originally by Ian Glover in 1975, this limestone rock-shelter in the Maros karsts of Sulawesi, Indonesia, has long held significance in our understanding of early human dispersals into 'Wallacea', the vast zone of oceanic islands between continental Asia and Australia. We present new stratigraphic information and dating evidence from Leang Burung 2 collected during the course of our excavations at this site in 2007 and 2011-13. Our findings suggest that the classic Late Pleistocene modern human occupation sequence identified previously at Leang Burung 2, and proposed to span around 31,000 to 19,000 conventional 14C years BP (~35-24 ka cal BP), may actually represent an amalgam of reworked archaeological materials. Sources for cultural materials of mixed ages comprise breccias from the rear wall of the rock-shelter-remnants of older, eroded deposits dated to 35-23 ka cal BP-and cultural remains of early Holocene antiquity. Below the upper levels affected by the mass loss of Late Pleistocene deposits, our deep-trench excavations uncovered evidence for an earlier hominin presence at the site. These findings include fossils of now-extinct proboscideans and other 'megafauna' in stratified context, as well as a cobble-based stone artifact technology comparable to that produced by late Middle Pleistocene hominins elsewhere on Sulawesi.

Leaf evolution in early-diverging ferns: insights from a new fern-like plant from the Late Devonian of China.

PubMed

Wang, De-Ming; Xu, Hong-He; Xue, Jin-Zhuang; Wang, Qi; Liu, Le

2015-06-01

With the exception of angiosperms, the main euphyllophyte lineages (i.e. ferns sensu lato, progymnosperms and gymnosperms) had evolved laminate leaves by the Late Devonian. The evolution of laminate leaves, however, remains unclear for early-diverging ferns, largely represented by fern-like plants. This study presents a novel fern-like taxon with pinnules, which provides new insights into the early evolution of laminate leaves in early-diverging ferns. Macrofossil specimens were collected from the Upper Devonian (Famennian) Wutong Formation of Anhui and Jiangsu Provinces, South China. A standard degagement technique was employed to uncover compressed plant portions within the rock matrix. A new fern-like taxon, SHOUGANGIA BELLA GEN ET SP NOV: , is described and represents an early-diverging fern with highly derived features. It has a partially creeping stem with adventitious roots only on one side, upright primary and secondary branches arranged in helices, tertiary branches borne alternately or (sub)oppositely, laminate and usually lobed leaves with divergent veins, and complex fertile organs terminating tertiary branches and possessing multiple divisions and numerous terminal sporangia. Shougangia bella provides unequivocal fossil evidence for laminate leaves in early-diverging ferns. It suggests that fern-like plants, along with other euphyllophyte lineages, had independently evolved megaphylls by the Late Devonian, possibly in response to a significant decline in atmospheric CO2 concentration. Among fern-like plants, planate ultimate appendages are homologous with laminate pinnules, and in the evolution of megaphylls, fertile organs tend to become complex. © The Author 2015. Published by Oxford University Press on behalf of the Annals of Botany Company. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Evolution of language: Lessons from the genome.

PubMed

Fisher, Simon E

2017-02-01

The post-genomic era is an exciting time for researchers interested in the biology of speech and language. Substantive advances in molecular methodologies have opened up entire vistas of investigation that were not previously possible, or in some cases even imagined. Speculations concerning the origins of human cognitive traits are being transformed into empirically addressable questions, generating specific hypotheses that can be explicitly tested using data collected from both the natural world and experimental settings. In this article, I discuss a number of promising lines of research in this area. For example, the field has begun to identify genes implicated in speech and language skills, including not just disorders but also the normal range of abilities. Such genes provide powerful entry points for gaining insights into neural bases and evolutionary origins, using sophisticated experimental tools from molecular neuroscience and developmental neurobiology. At the same time, sequencing of ancient hominin genomes is giving us an unprecedented view of the molecular genetic changes that have occurred during the evolution of our species. Synthesis of data from these complementary sources offers an opportunity to robustly evaluate alternative accounts of language evolution. Of course, this endeavour remains challenging on many fronts, as I also highlight in the article. Nonetheless, such an integrated approach holds great potential for untangling the complexities of the capacities that make us human.

Merger-driven evolution of the effective stellar initial mass function of massive early-type galaxies

NASA Astrophysics Data System (ADS)

Sonnenfeld, Alessandro; Nipoti, Carlo; Treu, Tommaso

2017-02-01

The stellar initial mass function (IMF) of early-type galaxies is the combination of the IMF of the stellar population formed in situ and that of accreted stellar populations. Using as an observable the effective IMF αIMF, defined as the ratio between the true stellar mass of a galaxy and the stellar mass inferred assuming a Salpeter IMF, we present a theoretical model for its evolution as a result of dry mergers. We use a simple dry-merger evolution model, based on cosmological N-body simulations, together with empirically motivated prescriptions for the IMF to make predictions on how the effective IMF of massive early-type galaxies changes from z = 2 to z = 0. We find that the IMF normalization of individual galaxies becomes lighter with time. At fixed velocity dispersion, αIMF is predicted to be constant with redshift. Current dynamical constraints on the evolution of the IMF are in slight tension with this prediction, even though systematic uncertainties, including the effect of radial gradients in the IMF, prevent a conclusive statement. The correlation of αIMF with stellar mass becomes shallower with time, while the correlation between αIMF and velocity dispersion is mostly preserved by dry mergers. We also find that dry mergers can mix the dependence of the IMF on stellar mass and velocity dispersion, making it challenging to infer, from z = 0 observations of global galactic properties, what is the quantity that is originally coupled with the IMF.

Lunge feeding in early marine reptiles and fast evolution of marine tetrapod feeding guilds.

PubMed

Motani, Ryosuke; Chen, Xiao-hong; Jiang, Da-yong; Cheng, Long; Tintori, Andrea; Rieppel, Olivier

2015-03-10

Traditional wisdom holds that biotic recovery from the end-Permian extinction was slow and gradual, and was not complete until the Middle Triassic. Here, we report that the evolution of marine predator feeding guilds, and their trophic structure, proceeded faster. Marine reptile lineages with unique feeding adaptations emerged during the Early Triassic (about 248 million years ago), including the enigmatic Hupehsuchus that possessed an unusually slender mandible. A new specimen of this genus reveals a well-preserved palate and mandible, which suggest that it was a rare lunge feeder as also occurs in rorqual whales and pelicans. The diversity of feeding strategies among Triassic marine tetrapods reached their peak in the Early Triassic, soon after their first appearance in the fossil record. The diet of these early marine tetrapods most likely included soft-bodied animals that are not preserved as fossils. Early marine tetrapods most likely introduced a new trophic mechanism to redistribute nutrients to the top 10 m of the sea, where the primary productivity is highest. Therefore, a simple recovery to a Permian-like trophic structure does not explain the biotic changes seen after the Early Triassic.

Lunge feeding in early marine reptiles and fast evolution of marine tetrapod feeding guilds

PubMed Central

Motani, Ryosuke; Chen, Xiao-hong; Jiang, Da-yong; Cheng, Long; Tintori, Andrea; Rieppel, Olivier

2015-01-01

Traditional wisdom holds that biotic recovery from the end-Permian extinction was slow and gradual, and was not complete until the Middle Triassic. Here, we report that the evolution of marine predator feeding guilds, and their trophic structure, proceeded faster. Marine reptile lineages with unique feeding adaptations emerged during the Early Triassic (about 248 million years ago), including the enigmatic Hupehsuchus that possessed an unusually slender mandible. A new specimen of this genus reveals a well-preserved palate and mandible, which suggest that it was a rare lunge feeder as also occurs in rorqual whales and pelicans. The diversity of feeding strategies among Triassic marine tetrapods reached their peak in the Early Triassic, soon after their first appearance in the fossil record. The diet of these early marine tetrapods most likely included soft-bodied animals that are not preserved as fossils. Early marine tetrapods most likely introduced a new trophic mechanism to redistribute nutrients to the top 10 m of the sea, where the primary productivity is highest. Therefore, a simple recovery to a Permian-like trophic structure does not explain the biotic changes seen after the Early Triassic. PMID:25754468

Climate and environment of the earliest West European hominins inferred from amphibian and squamate reptile assemblages: Sima del Elefante Lower Red Unit, Atapuerca, Spain

NASA Astrophysics Data System (ADS)

Blain, Hugues-Alexandre; Bailon, Salvador; Cuenca-Bescós, Gloria; Bennàsar, Maria; Rofes, Juan; López-García, Juan Manuel; Huguet, Rosa; Arsuaga, Juan Luis; Bermúdez de Castro, José Maria; Carbonell, Eudald

2010-11-01

The Sima del Elefante cave, in the Sierra de Atapuerca (Burgos, Spain), is famous for the fact that level TE9 of its Lower Red Unit recently delivered the oldest hominin remains of Western Europe, identified as Homo antecessor and dated by biostratigraphy and radiometric methods to ca 1.2 Ma. Given the importance of this discovery, every effort is being made to reconstruct the landscapes where these hominins once thrived. The amphibian and squamate reptile assemblage of the Sima del Elefante Lower Red Unit is here studied for the first time. The faunal list comprises at least 17 species (roughly 12,000 bone fossil remains): Salamandra salamandra, Triturus cf. marmoratus, Alytes obstetricans, Pelobates cultripes, Pelodytes punctatus, Bufo bufo, Bufo calamita, Hyla arborea, Rana sp., cf. Pelophylax sp., Lacerta s.l., small-sized indeterminate lacertids, Anguis fragilis, Natrix cf. natrix, Natrix cf. maura, Coronella cf. girondica and Vipera sp. As the amphibians and squamate reptiles do not differ at species level from the extant herpetofauna of the Iberian Peninsula, they can contribute to the reconstruction of the landscape and climate. In this paper, the mutual climatic range and habitat weighting methods are applied to the amphibian and squamate reptile assemblages in order to estimate quantitative data. The results from the squamate and amphibian study indicate that during the hominin presence the mean annual temperature (MAT = 10-13 °C) was always slightly warmer than at present and the mean annual precipitation (MAP = 800-1000 mm) was greater than today in the Burgos area. The landscape had open habitats in the vicinity of the Atapuerca caves throughout the sequence, with wet points in the surrounding area, and a predominance of humid meadows and open woodlands. These results mainly agree with those for large mammals, small mammals and the pollen analysis. The climate and landscape of TE-LRU are very similar to those reconstructed for the TD6 "Aurora Stratum

The Moon as a Recorder of Organic Evolution in the Early Solar System: A Lunar Regolith Analog Study

PubMed Central

Court, Richard W.; Crawford, Ian A.; Jones, Adrian P.; Joy, Katherine H.; Sephton, Mark A.

2015-01-01

Abstract The organic record of Earth older than ∼3.8 Ga has been effectively erased. Some insight is provided to us by meteorites as well as remote and direct observations of asteroids and comets left over from the formation of the Solar System. These primitive objects provide a record of early chemical evolution and a sample of material that has been delivered to Earth's surface throughout the past 4.5 billion years. Yet an effective chronicle of organic evolution on all Solar System objects, including that on planetary surfaces, is more difficult to find. Fortunately, early Earth would not have been the only recipient of organic matter–containing objects in the early Solar System. For example, a recently proposed model suggests the possibility that volatiles, including organic material, remain archived in buried paleoregolith deposits intercalated with lava flows on the Moon. Where asteroids and comets allow the study of processes before planet formation, the lunar record could extend that chronicle to early biological evolution on the planets. In this study, we use selected free and polymeric organic materials to assess the hypothesis that organic matter can survive the effects of heating in the lunar regolith by overlying lava flows. Results indicate that the presence of lunar regolith simulant appears to promote polymerization and, therefore, preservation of organic matter. Once polymerized, the mineral-hosted newly formed organic network is relatively protected from further thermal degradation. Our findings reveal the thermal conditions under which preservation of organic matter on the Moon is viable. Key Words: Moon—Regolith—Organic preservation—Biomarkers. Astrobiology 15, 154–168. PMID:25615648

Early chemo-dynamical evolution of dwarf galaxies deduced from enrichment of r-process elements

NASA Astrophysics Data System (ADS)

Hirai, Yutaka; Ishimaru, Yuhri; Saitoh, Takayuki R.; Fujii, Michiko S.; Hidaka, Jun; Kajino, Toshitaka

2017-04-01

The abundance of elements synthesized by the rapid neutron-capture process (r-process elements) of extremely metal-poor (EMP) stars in the Local Group galaxies gives us clues to clarify the early evolutionary history of the Milky Way halo. The Local Group dwarf galaxies would have similarly evolved with building blocks of the Milky Way halo. However, how the chemo-dynamical evolution of the building blocks affects the abundance of r-process elements is not yet clear. In this paper, we perform a series of simulations using dwarf galaxy models with various dynamical times and total mass, which determine star formation histories. We find that galaxies with dynamical times longer than 100 Myr have star formation rates less than 10-3 M⊙ yr-1 and slowly enrich metals in their early phase. These galaxies can explain the observed large scatters of r-process abundance in EMP stars in the Milky Way halo regardless of their total mass. On the other hand, the first neutron star merger appears at a higher metallicity in galaxies with a dynamical time shorter than typical neutron star merger times. The scatters of r-process elements mainly come from the inhomogeneity of the metals in the interstellar medium whereas the scatters of α-elements are mostly due to the difference in the yield of each supernova. Our results demonstrate that the future observations of r-process elements in EMP stars will be able to constrain the early chemo-dynamical evolution of the Local Group galaxies.

Early to Middle Jurassic tectonic evolution of the Bogda Mountains, Northwest China: Evidence from sedimentology and detrital zircon geochronology

NASA Astrophysics Data System (ADS)

Ji, Hongjie; Tao, Huifei; Wang, Qi; Qiu, Zhen; Ma, Dongxu; Qiu, Junli; Liao, Peng

2018-03-01

The Bogda Mountains, as an important intracontinental orogenic belt, are situated in the southern part of the Central Asian Orogenic Belt (CAOB), and are a key area for understanding the Mesozoic evolution of the CAOB. However, the tectonic evolution of the Bogda Mountains remains controversial during the Mesozoic Era, especially the Early to Middle Jurassic Periods. The successive Lower to Middle Jurassic strata are well preserved and exposed along the northern flank of the Western Bogda Mountains and record the uplift processes of the Bogda Mountains. In this study, we analysed sedimentary facies combined with detrital zircon U-Pb geochronology at five sections of Lower to Middle Jurassic strata to detect the tectonic evolution and changes of provenance in the Bogda area. During Early to Middle Jurassic times, the fluvial, deltaic and lacustrine environments dominated in the western section of the Bogda area. The existence of Early Triassic peak age indicates that the Bogda Mountains did not experience uplift during the period of early Badaowan Formation deposition. The Early Triassic to Late Permian granitoid plutons and Carboniferous volcanic rocks from the Barkol and Santanghu areas were the main provenances. The significant change in the U-Pb age spectrum implies that the Eastern Bogda Mountains initiated uplift in the period of late Badaowan Formation deposition, and the Eastern Junggar Basin and the Turpan-Hami Basin were partially partitioned. The Eastern Bogda Mountains gradually became the major provenance. From the period of early Sangonghe to early Toutunhe Formations deposition, the provenance of the sediments and basin-range frame were similar to that of late Badaowan. However, the Eastern Bogda Mountains suffered intermittent uplift three times, and successive denudation. The uplifts respectively happened in early Sangonghe, late Sangonghe to early Xishanyao, and late Xishanyao to early Toutunhe. During the deposition stage of Toutunhe Formation, a

Fuxianhuiid ventral nerve cord and early nervous system evolution in Panarthropoda.

PubMed

Yang, Jie; Ortega-Hernández, Javier; Butterfield, Nicholas J; Liu, Yu; Boyan, George S; Hou, Jin-Bo; Lan, Tian; Zhang, Xi-Guang

2016-03-15

Panarthropods are typified by disparate grades of neurological organization reflecting a complex evolutionary history. The fossil record offers a unique opportunity to reconstruct early character evolution of the nervous system via exceptional preservation in extinct representatives. Here we describe the neurological architecture of the ventral nerve cord (VNC) in the upper-stem group euarthropod Chengjiangocaris kunmingensis from the early Cambrian Xiaoshiba Lagerstätte (South China). The VNC of C. kunmingensis comprises a homonymous series of condensed ganglia that extend throughout the body, each associated with a pair of biramous limbs. Submillimetric preservation reveals numerous segmental and intersegmental nerve roots emerging from both sides of the VNC, which correspond topologically to the peripheral nerves of extant Priapulida and Onychophora. The fuxianhuiid VNC indicates that ancestral neurological features of Ecdysozoa persisted into derived members of stem-group Euarthropoda but were later lost in crown-group representatives. These findings illuminate the VNC ground pattern in Panarthropoda and suggest the independent secondary loss of cycloneuralian-like neurological characters in Tardigrada and Euarthropoda.

Fuxianhuiid ventral nerve cord and early nervous system evolution in Panarthropoda

PubMed Central

Yang, Jie; Ortega-Hernández, Javier; Butterfield, Nicholas J.; Liu, Yu; Boyan, George S.; Hou, Jin-bo; Lan, Tian; Zhang, Xi-guang

2016-01-01

Panarthropods are typified by disparate grades of neurological organization reflecting a complex evolutionary history. The fossil record offers a unique opportunity to reconstruct early character evolution of the nervous system via exceptional preservation in extinct representatives. Here we describe the neurological architecture of the ventral nerve cord (VNC) in the upper-stem group euarthropod Chengjiangocaris kunmingensis from the early Cambrian Xiaoshiba Lagerstätte (South China). The VNC of C. kunmingensis comprises a homonymous series of condensed ganglia that extend throughout the body, each associated with a pair of biramous limbs. Submillimetric preservation reveals numerous segmental and intersegmental nerve roots emerging from both sides of the VNC, which correspond topologically to the peripheral nerves of extant Priapulida and Onychophora. The fuxianhuiid VNC indicates that ancestral neurological features of Ecdysozoa persisted into derived members of stem-group Euarthropoda but were later lost in crown-group representatives. These findings illuminate the VNC ground pattern in Panarthropoda and suggest the independent secondary loss of cycloneuralian-like neurological characters in Tardigrada and Euarthropoda. PMID:26933218

Man the Fat Hunter: The Demise of Homo erectus and the Emergence of a New Hominin Lineage in the Middle Pleistocene (ca. 400 kyr) Levant

PubMed Central

Ben-Dor, Miki; Gopher, Avi; Hershkovitz, Israel; Barkai, Ran

2011-01-01

The worldwide association of H. erectus with elephants is well documented and so is the preference of humans for fat as a source of energy. We show that rather than a matter of preference, H. erectus in the Levant was dependent on both elephants and fat for his survival. The disappearance of elephants from the Levant some 400 kyr ago coincides with the appearance of a new and innovative local cultural complex – the Levantine Acheulo-Yabrudian and, as is evident from teeth recently found in the Acheulo-Yabrudian 400-200 kyr site of Qesem Cave, the replacement of H. erectus by a new hominin. We employ a bio-energetic model to present a hypothesis that the disappearance of the elephants, which created a need to hunt an increased number of smaller and faster animals while maintaining an adequate fat content in the diet, was the evolutionary drive behind the emergence of the lighter, more agile, and cognitively capable hominins. Qesem Cave thus provides a rare opportunity to study the mechanisms that underlie the emergence of our post-erectus ancestors, the fat hunters. PMID:22174868

A bizarre new toothed mysticete (Cetacea) from Australia and the early evolution of baleen whales.

PubMed

Fitzgerald, Erich M G

2006-12-07

Extant baleen whales (Cetacea, Mysticeti) are all large filter-feeding marine mammals that lack teeth as adults, instead possessing baleen, and feed on small marine animals in bulk. The early evolution of these superlative mammals, and their unique feeding method, has hitherto remained enigmatic. Here, I report a new toothed mysticete from the Late Oligocene of Australia that is more archaic than any previously described. Unlike all other mysticetes, this new whale was small, had enormous eyes and lacked derived adaptations for bulk filter-feeding. Several morphological features suggest that this mysticete was a macrophagous predator, being convergent on some Mesozoic marine reptiles and the extant leopard seal (Hydrurga leptonyx). It thus refutes the notions that all stem mysticetes were filter-feeders, and that the origins and initial radiation of mysticetes was linked to the evolution of filter-feeding. Mysticetes evidently radiated into a variety of disparate forms and feeding ecologies before the evolution of baleen or filter-feeding. The phylogenetic context of the new whale indicates that basal mysticetes were macrophagous predators that did not employ filter-feeding or echolocation, and that the evolution of characters associated with bulk filter-feeding was gradual.

A bizarre new toothed mysticete (Cetacea) from Australia and the early evolution of baleen whales

PubMed Central

Fitzgerald, Erich M.G

2006-01-01

Extant baleen whales (Cetacea, Mysticeti) are all large filter-feeding marine mammals that lack teeth as adults, instead possessing baleen, and feed on small marine animals in bulk. The early evolution of these superlative mammals, and their unique feeding method, has hitherto remained enigmatic. Here, I report a new toothed mysticete from the Late Oligocene of Australia that is more archaic than any previously described. Unlike all other mysticetes, this new whale was small, had enormous eyes and lacked derived adaptations for bulk filter-feeding. Several morphological features suggest that this mysticete was a macrophagous predator, being convergent on some Mesozoic marine reptiles and the extant leopard seal (Hydrurga leptonyx). It thus refutes the notions that all stem mysticetes were filter-feeders, and that the origins and initial radiation of mysticetes was linked to the evolution of filter-feeding. Mysticetes evidently radiated into a variety of disparate forms and feeding ecologies before the evolution of baleen or filter-feeding. The phylogenetic context of the new whale indicates that basal mysticetes were macrophagous predators that did not employ filter-feeding or echolocation, and that the evolution of characters associated with bulk filter-feeding was gradual. PMID:17015308

Natural history of Homo erectus.

PubMed