Hominin occupation of the Chinese Loess Plateau since about 2.1 million years ago

Earliest evidence of human occupations and technological complexity above the 45th North parallel in Western Europe. The site of Lunery-Rosieres la-Terre-des-Sablons (France, 1.1 Ma)

The site of LuneryRosieres la-Terre-des-Sablons (Lunery, Cher, France) comprises early evidence of human occupation in mid-latitudes in Western Europe. It demonstrates hominin presence in the Loire River Basin during the Early Pleistocene at the transition between an interglacial stage and the beginning of the following glacial stage. Three archaeological levels sandwiched and associated with two diamicton levels deposited on the downcutting river floor indicate repeated temporary occupations. Lithic material yields evidence of simple and more complex core technologies on local Jurassic siliceous rocks and Oligocene millstone. Hominins availed of natural stone morphologies to produce flakes with limited preparation. Some cores show centripetal management and a partially prepared striking platform. The mean ESR age of 1175 ka ± 98 ka obtained on fluvial sediments overlying the archaeological levels could correspond to the transition between marine isotopic stages (MIS) 37 and 36, during the normal Cobb Mountain subchron, and in particular at the beginning of MIS 36. The Lunery site shows that hominins were capable of adapting to early glacial environmental conditions and adopting appropriate strategies for settling in mid-latitude zones. These areas cannot be considered as inhospitable at that time as Lunery lies at some distance from the forming ice cap.

Orbital- and millennial-scale Asian winter monsoon variability across the Pliocene-Pleistocene glacial intensification

Intensification of northern hemisphere glaciation (iNHG), ~2.7 million years ago (Ma), led to establishment of the Pleistocene to present-day bipolar icehouse state. Here we document evolution of orbital- and millennial-scale Asian winter monsoon (AWM) variability across the iNHG using a palaeomagnetically dated centennial-resolution grain size record between 3.6 and 1.9 Ma from a previously undescribed loess-palaeosol/red clay section on the central Chinese Loess Plateau. We find that the late Pliocene-early Pleistocene AWM was characterized by combined 41-kyr and ~100-kyr cycles, in response to ice volume and atmospheric CO2 forcing. Northern hemisphere ice sheet expansion, which was accompanied by an atmospheric CO2 concentration decline, substantially increased glacial AWM intensity  and its orbitally oscillating amplitudes across the iNHG. Superposed on orbital variability, we find that millennial AWM intensity fluctuations persisted during both the warmer (higher-CO2) late Pliocene and colder (lower-CO2) early Pleistocene, in response to both external astronomical forcing and internal climate dynamics.

Hominin population bottleneck coincided with migration from Africa during the Early Pleistocene ice age transition

Two recently published analyses make cases for severe bottlenecking of human populations occurring in the late Early Pleistocene, one case at about 0.9 Mya based on a genomic analysis of modern human populations and the low number of hominin sites of this age in Africa and the other at about 1.1 Mya based on an age inventory of sites of hominin presence in Eurasia. Both models point to climate change as the bottleneck trigger, albeit manifested at very different times, and have implications for human migrations as a mechanism to elude extinction at bottlenecking. Here, we assess the climatic and chronologic components of these models and suggest that the several hundred-thousand-year difference is largely an artifact of biases in the chronostratigraphic record of Eurasian hominin sites. We suggest that the best available data are consistent with the Galerian hypothesis expanded from Europe to Eurasia as a major migration pulse of fauna including hominins in the late Early Pleistocene as a consequence of the opening of land routes from Africa facilitated by a large sea level drop associated with the first major ice age of the Pleistocene and concurrent with widespread aridity across Africa that occurred during marine isotope stage 22 at ~0.9 Mya. This timing agrees with the independently dated bottleneck from genomic analysis of modern human populations and allows speculations about the relative roles of climate forcing on the survival of hominins.

Earliest Prepared core technology in Eurasia from Nihewan (China): Implications for early human abilities and dispersals in East Asia

Organized flaking techniques to obtain predetermined stone tools have been traced back to the early Acheulean (also known as mode 2) in Africa and are seen as indicative of the emergence of advanced technical abilities and in-depth planning skills among early humans. Here, we report one of the earliest known examples of prepared core technology in the archaeological record, at the Cenjiawan (CJW) site in the Nihewan basin of China, dated 1.1 Mya. The operational schemes reconstructed from the CJW refit sets, together with shaping patterns observed in the retouched tools, suggest that Nihewan basin toolmakers had the technical abilities of mode 2 hominins, and developed different survival strategies to adapt to local raw materials and environments. This finding predates the previously earliest known prepared core technology from Eurasia by 0.3 My, and the earliest known mode 2 sites in East Asia by a similar amount of time, thus suggesting that hominins with advanced technologies may have migrated into high latitude East Asia as early as 1.1 Mya.

Using machine learning on new feature sets extracted from three-dimensional models of broken animal bones to classify fragments according to break agent

Distinguishing agents of bone modification at paleoanthropological sites is an important means of understanding early hominin evolution. Fracture pattern analysis is used to help determine site formation processes, including whether hominins were hunting or scavenging for animal food resources. Determination of how these behaviors manifested in ancient human sites has major implications for our biological and behavioral evolution, including social and cognitive abilities, dietary impacts of having access to in-bone nutrients like marrow, and cultural variation in butchering and food processing practices. Nevertheless, previous analyses remain inconclusive, often suffering from lack of replicability, misuse of mathematical methods, and/or failure to overcome equifinality. In this paper, we present a new approach aimed at distinguishing bone fragments resulting from hominin and carnivore breakage. Our analysis is founded on a large collection of scanned three-dimensional models of fragmentary bone broken by known agents, to which we apply state of the art machine learning algorithms. Our classification of fragments achieves an average mean accuracy of 77% across tests, thus demonstrating notable, but not overwhelming, success for distinguishing the agent of breakage. We note that, while previous research applying such algorithms has claimed higher success rates, fundamental errors in the application of machine learning protocols suggest that the reported accuracies are unjustified and unreliable. The systematic, fully documented, and proper application of machine learning algorithms leads to an inherent reproducibility of our study, and therefore our methods hold great potential for deciphering when and where hominins first began exploiting marrow and meat, and clarifying their importance and influence on human evolution.

Early Homo erectus lived at high altitudes and produced both Oldowan and Acheulean tools

In Africa, the scarcity of hominin remains found in direct association with stone tools has hindered attempts to link Homo habilis and Homo erectus with particular lithic industries. The infant mandible discovered in level E at Garba IV (Melka Kunture) on the highlands of Ethiopia is critical to this issue due to its direct association with an Oldowan lithic industry. Here, we use synchrotron imaging to examine the internal morphology of the unerupted permanent dentition and confirm its identification as Homo erectus. Additionally, we utilize new palaeomagnetic ages to show that (i) the mandible in level E is ca. 2 million-years-old, and represents one of the earliest Homo erectus fossils, and (ii) that overlying level D, ca. 1.95 million-years-old, contains the earliest known Acheulean assemblage.

Large mammals and trees in eastern monsoonal China: anthropogenic losses since the Late Pleistocene and restoration prospects in the Anthropocene

Massive human-induced declines of large-sized animals and trees (megabiota) from the Late Pleistocene to the Anthropocene have resulted in downsized ecosystems across the globe, in which components and functions have been greatly simplified. In response, active restoration projects of extant large-sized species or functional substitutes are needed at large scales to promote ecological processes that are important for ecosystem self-regulation and biodiversity maintenance. Despite the desired global scope of such projects, they have received little attention in East Asia. Here, we synthesise the biogeographical and ecological knowledge of megabiota in ancient and modern China, with relevant data mostly located in eastern monsoonal China (EMC), aiming to assess its potential for restoring functionally intact ecosystems modulated by megabiota. We found that during the Late Pleistocene, 12 mammalian megafaunal (carnivores ≥15 kg and herbivores ≥500 kg) species disappeared from EMC: one carnivore Crocuta ultima (East Asian spotted hyena) and 11 herbivores including six megaherbivores (≥1000 kg). The relative importance of climate change and humans in driving these losses remains debated, despite accumulating evidence in favour of the latter. Later massive depletion of megafauna and large-sized (45-500 kg) herbivores has been closely associated with agricultural expansion and societal development, especially during the late Holocene. While forests rich in large timber trees (33 taxa in written records) were common in the region 2000-3000 years ago, millennial-long logging has resulted in considerable range contractions and at least 39 threatened species. The wide distribution of C. ultima, which likely favoured open or semi-open habitats (like extant spotted hyenas), suggests the existence of mosaic open and closed vegetation in the Late Pleistocene across EMC, in line with a few pollen-based vegetation reconstructions and potentially, or at least partially, reflecting herbivory by herbivorous megafauna. The widespread loss of megaherbivores may have strongly compromised seed dispersal for both megafruit (fleshy fruits with widths ≥40 mm) and non-megafruit plant species in EMC, especially in terms of extra-long-distance (>10 km) dispersal, which is critical for plant species that rely on effective biotic agents to track rapid climate change. The former occurrence of large mammals and trees have translated into rich material and non-material heritages passed down across generations. Several reintroduction projects have been implemented or are under consideration, with the case of Elaphurus davidianus a notable success in recovering wild populations in the middle reaches of the Yangtze River, although trophic interactions with native carnivorous megafauna have not yet been restored. Lessons of dealing with human-wildlife conflicts are key to public support for maintaining landscapes shared with megafauna and large herbivores in the human-dominated Anthropocene. Meanwhile, potential human-wildlife conflicts, e.g. public health risks, need to be scientifically informed and effectively reduced. The Chinese government's strong commitment to improved policies of ecological protection and restoration (e.g. ecological redlines and national parks) provides a solid foundation for a scaling-up contribution to the global scope needed for solving the crisis of biotic downsizing and ecosystem degradation.

The estimation and evolution of hominin body mass

Body mass is a critical variable in many hominin evolutionary studies, with implications for reconstructing relative brain size, diet, locomotion, subsistence strategy, and social organization. We review methods that have been proposed for estimating body mass from true and trace fossils, consider their applicability in different contexts, and the appropriateness of different modern reference samples. Recently developed techniques based on a wider range of modern populations hold promise for providing more accurate estimates in earlier hominins, although uncertainties remain, particularly in non-Homo taxa. When these methods are applied to almost 300 Late Miocene through Late Pleistocene specimens, the resulting body mass estimates fall within a 25-60 kg range for early non-Homo taxa, increase in early Homo to about 50-90 kg, then remain constant until the Terminal Pleistocene, when they decline.

Human and African ape myosin heavy chain content and the evolution of hominin skeletal muscle

Humans are unique among terrestrial mammals in our manner of walking and running, reflecting 7 to 8 Ma of musculoskeletal evolution since diverging with the genus Pan. One component of this is a shift in our skeletal muscle biology towards a predominance of myosin heavy chain (MyHC) I isoforms (i.e. slow fibers) across our pelvis and lower limbs, which distinguishes us from chimpanzees. Here, new MyHC data from 35 pelvis and hind limb muscles of a Western gorilla (Gorilla gorilla) are presented. These data are combined with a similar chimpanzee dataset to assess the MyHC I content of humans in comparison to African apes (chimpanzees and gorillas) and other terrestrial mammals. The responsiveness of human skeletal muscle to behavioral interventions is also compared to the human-African ape differential. Humans are distinct from African apes and among a small group of terrestrial mammals whose pelvis and hind/lower limb muscle is slow fiber dominant, on average. Behavioral interventions, including immobilization, bed rest, spaceflight and exercise, can induce modest decreases and increases in human MyHC I content (i.e. -9.3% to 2.3%, n = 2033 subjects), but these shifts are much smaller than the mean human-African ape differential (i.e. 31%). Taken together, these results indicate muscle fiber content is likely an evolvable trait under selection in the hominin lineage. As such, we highlight potential targets of selection in the genome (e.g. regions that regulate MyHC content) that may play an important role in hominin skeletal muscle evolution.

Javanese Homo erectus on the move in SE Asia circa 1.8 Ma

The migration of Homo erectus in Southeast Asia during Early Pleistocene is cardinal to our comprehension of the evolution of the genus Homo. However, the limited consideration of the rapidly changing physical environment, together with controversial datings of hominin bearing sites, make it challenging to secure the robust timeline needed to unveil the behavior of early humans. Here, we reappraise the first appearance datum of Javanese H. erectus by adding the most reliable age constraints based on cosmogenic nuclides [Formula: see text]Be and [Formula: see text]Al produced in situ to a compilation of earlier estimates. We find that H. erectus reached Java and dwelled at Sangiran, Java, ca. 1.8 Ma. Using this age as a baseline, we develop a probabilistic approach to reconstruct their dispersal routes, coupling ecological movement simulations to landscape evolution models forced by reconstructed geodynamic and climatic histories. We demonstrate that the hospitable terra firma conditions of Sundaland facilitated the prior dispersal of hominins to the edge of Java, where they conversely could not settle until the Javanese archipelago emerged from the sea and connected to Sundaland. The dispersal of H. erectus across Sundaland occurred over at least tens to hundreds kyr, a time scale over which changes in their physical environment, whether climatic or physiographic, may have become primary forcings on their behavior. Our comprehensive reconstruction method to unravel the peopling timeline of SE Asia provides a novel framework to evaluate the evolution of early humans.

Paleolithic occupation of arid Central Asia in the Middle Pleistocene

Central Asia is positioned at a crossroads linking several zones important to hominin dispersal during the Middle Pleistocene. However, the scarcity of stratified and dated archaeological material and paleoclimate records makes it difficult to understand dispersal and occupation dynamics during this time period, especially in arid zones. Here we compile and analyze paleoclimatic and archaeological data from Pleistocene Central Asia, including examination of a new layer-counted speleothem-based multiproxy record of hydrological changes in southern Uzbekistan at the end of MIS 11. Our findings indicate that Lower Palaeolithic sites in the steppe, semi-arid, and desert zones of Central Asia may have served as key areas for the dispersal of hominins into Eurasia during the Middle Pleistocene. In agreement with previous studies, we find that bifaces occur across these zones at higher latitudes and in lower altitudes relative to the other Paleolithic assemblages. We argue that arid Central Asia would have been intermittently habitable during the Middle Pleistocene when long warm interglacial phases coincided with periods when the Caspian Sea was experiencing consistently high water levels, resulting in greater moisture availability and more temperate conditions in otherwise arid regions. During periodic intervals in the Middle Pleistocene, the local environment of arid Central Asia was likely a favorable habitat for paleolithic hominins and was frequented by Lower Paleolithic toolmakers producing bifaces.

Homo sapiens lithic technology and microlithization in the South Asian rainforest at Kitulgala Beli-lena (c. 45 - 8,000 years ago)

Recent archaeological investigations in Sri Lanka have reported evidence for the exploitation and settlement of tropical rainforests by Homo sapiens since c. 48,000 BP. Information on technological approaches used by human populations in rainforest habitats is restricted to two cave sites, Batadomba-lena and Fa-Hien Lena. Here, we provide detailed study of the lithic assemblages of Kitulgala Beli-lena, a recently excavated rockshelter preserving a sedimentary sequence from the Late Pleistocene to the Holocene. Our analysis indicates in situ lithic production and the recurrent use of the bipolar method for the production of microliths. Stone tool analyses demonstrate long-term technological stability from c. 45,000 to 8,000 years BP, a pattern documented in other rainforest locations. Foraging behaviour is characterised by the use of lithic bipolar by-products together with osseous projectile points for the consistent targeting of semi-arboreal/arboreal species, allowing for the widespread and recurrent settlement of the wet zone of Sri Lanka.

Life and death at Dmanisi, Georgia: Taphonomic signals from the fossil mammals

There are many hypotheses regarding influences on the early hominin biogeographic spread into Eurasia; among them is increased meat-eating. Dmanisi in Georgia is one of the rare Early Pleistocene sites in Eurasia, and here we present primary information and analysis of the medium and large mammal taphonomy, contributing information about site formation and the hominins' interaction with the fauna. Nearly 85% of the specimens come from the B1 stratum. Relative abundances of mammal families demonstrate some bias toward carnivores, especially Canis borjgali, and diverse Felidae species. Bones display little weathering. Post-depositional surface modifications and matrix obscure many bone surfaces, but carnivore tooth marking is the most common bone surface modification from the nutritive taphonomic phase. Tooth pits are large, in the size range of those made by modern Crocuta crocuta and Panthera leo. Breakage variables indicate most breaks occurred while the bones were still fresh, many by carnivore consumption. Fairly even limb bone representation of herbivores suggests carcasses were introduced to the site nearly whole. Hominin tool marks are present in low frequencies, but they suggest a variety of behaviors. These marks are found on Equus, Palaeotragus, Bison, large cervids, Pseudodama, Canis, and Mammuthus. Some were made by filleting proximal limb segments, and so are likely indicative of early access to carcasses, while other marks suggest scavenging. The Homo taphonomic variables resemble the rest of the taphonomic signatures from the site with little weathering, a slightly higher percentage of their bones are whole, but only a few have probable carnivore damage. The assemblage characteristics are compared to modern actualistic and experimental assemblages, and it is concluded that Dmanisi presents a palimpsest of hyena denning, felid activity, hominin meat-eating and likely natural deaths.

Oldowan Technology Amid Shifting Environments ∼2.03–1.83 Million Years Ago

The Oldowan represents the earliest recurrent evidence of human material culture and one of the longest-lasting forms of technology. Its appearance across the African continent amid the Plio-Pleistocene profound ecological transformations, and posterior dispersal throughout the Old World is at the foundation of hominin technological dependence. However, uncertainties exist concerning the degree to which the Oldowan constitutes an environment-driven behavioral adaptation. Moreover, it is necessary to understand how Oldowan technology varied through time in response to hominin ecological demands. In this study, we present the stone tool assemblage from Ewass Oldupa, a recently discovered archeological site that signals the earliest hominin occupation of Oldupai Gorge (formerly Olduvai) ∼2.03 Ma. At Ewass Oldupa, hominins underwent marked environmental shifts over the course of a ∼200 kyr period. In this article, we deployed an analysis that combines technological and typological descriptions with an innovative quantitative approach, the Volumetric Reconstruction Method. Our results indicate that hominins overcame major ecological challenges while relying on technological strategies that remained essentially unchanged. This highlights the Oldowan efficiency, as its basic set of technological traits was able to sustain hominins throughout multiple environments.

Agency and Identity in the Collective Self

Contemporary research on human sociality is heavily influenced by the social identity approach, positioning social categorization as the primary mechanism governing social life. Building on the distinction between agency and identity in the individual self ("I" vs. "Me"), we emphasize the analogous importance of distinguishing collective agency from collective identity ("We" vs. "Us"). While collective identity is anchored in the unique characteristics of group members, collective agency involves the adoption of a shared subjectivity that is directed toward some object of our attention, desire, emotion, belief, or action. These distinct components of the collective self are differentiated in terms of their mental representations, neurocognitive underpinnings, conditions of emergence, mechanisms of social convergence, and functional consequences. Overall, we show that collective agency provides a useful complement to the social categorization approach, with unique implications for multiple domains of human social life, including collective action, responsibility, dignity, violence, dominance, ritual, and morality.

New paleoecological inferences based on the Early Pleistocene amphibian and reptile assemblage from Dmanisi (Georgia, Lesser Caucasus)

Dmanisi (Georgia) is one of the oldest Early Paleolithic sites discovered out of Africa. In addition, it is the best site to understand the first Homo deme out of Africa and the first hominin occupation of Central to Western Eurasia. It has produced more than 40 hominin remains, including several very informative skulls, found in direct association with faunal remains and numerous lithic artifacts. To date, fossil amphibians and reptiles are one of the few proxies that have been used to propose quantitative climate reconstructions for the time where the hominins were living at Dmanisi. The aim of the present study is to review and amplify the previous paleoclimatic interpretation given by Blain et al. (2014), with an enhanced methodology using geographic information system and based on uncertain distribution area-occupied distribution area discrimination technique. This procedure permits to approach to a more precise common species distribution area and then using the WorldClim v. 2.1 climate database to propose for the first time monthly reconstructions for temperature and rainfall, in addition to annual parameters. The same technique is used to infer dominant ecoregions through the study area and potential tree coverage. Dmanisi climate is newly reconstructed as warm and semi-arid, similar to the present-day Mediterranean climate. New estimates however suggest warmer temperatures than previously reconstructed, together with a slightly higher but much more irregular amount of rainfall. The aridity indexes suggest a six months dry period, from May to October. Associated regional paleoenvironment is mainly characterized by Mediterranean forests, woodlands, and scrub, and the potential tree coverage is around 25%, that is, much less forested than today. New estimates agree with the 'Iberian' hominin ecological model, and with other proxies (large mammals, small mammals and archaeobotanical remains) that indicate a period of increased aridity contemporaneous with human occupations of the site.

Memory for medicinal plants remains in ancient and modern environments suggesting an evolved adaptedness

Adaptive memory is the propensity of human memory to easily store and retrieve important information to deal with challenges related to the Pleistocene. Recent evidence shows that humans have had a multiregional evolution across the African continent, including the rainforests and deciduous forests; however, there is little evidence regarding the implications of these origins and the relevant and recurring challenges of these environments on survival processing advantage in memory. In this study, we conducted an experiment with volunteers to analyze whether adaptive memory operates in the retrieval of important information to solve challenges of using medicinal plants to treat diseases in the ancestral environments of the savanna, rainforests, and deciduous forests compared to the modern environments of desert, tundra, coniferous forest, and urban areas. We used simulated survival environments and asked volunteers (30 per simulated scenario) to imagine themselves sick in one of these environments, and needing to find medicinal plants to treat their disease. The volunteers rated the relevance of 32 words to solve this challenge, followed by a surprise memory test. Our results showed no ancestral priority in recalling relevant information, as both ancestral and modern environments showed a similar recall of relevant information. This suggests that the evolved cognitive apparatus allows human beings to survive and can create survival strategies to face challenges imposed in various environments. We believe that this is only possible if the human mind operates through a flexible cognitive mechanism. This flexibility can reflect, for example, the different environments that the first hominids inhabited and the different dangerous situations that they faced.

Human Evolution in Asia: Taking Stock and Looking Forward

We review the state of paleoanthropology research in Asia. We survey the fossil record, articulate the current understanding, and delineate the points of contention. Although Asia received less attention than Europe and Africa did in the second half of the twentieth century, an increase in reliably dated fossil materials and the advances in genetics have fueled new research. The long and complex evolutionary history of humans in Asia throughout the Pleistocene can be explained by a balance of mechanisms, between gene flow among different populations and continuity of regional ancestry. This pattern is reflected in fossil morphology and paleogenomics. Critical understanding of the sociocultural forces that shaped the history of hominin fossil research in Asia is important in charting the way forward.

The unidirectional phylogeny of Homo sapiens anchors the origin of modern humans in Eurasia

BACKGROUND

The Out of Africa hypothesis, OOAH, was challenged recently in an extended mtDNA analysis, PPA (Progressive Phylogenetic Analysis), that identified the African human populations as paraphyletic, a finding that contradicted the common OOAH understanding that Hss had originated in Africa and invaded Eurasia from there. The results were consistent with the molecular Out of Eurasia hypothesis, OOEH, and Eurasian palaeontology, a subject that has been largely disregarded in the discussion of OOAH.

RESULTS

In the present study the mtDNA tree, a phylogeny based on maternal inheritance, was compared to the nuclear DNA tree of the paternally transmitted Y-chromosome haplotypes, Y-DNAs. The comparison showed full phylogenetic coherence between these two separate sets of data. The results were consistent with potentially four translocations of modern humans from Eurasia into Africa, the earliest taking place ≈ 250,000 years before present, YBP. The results were in accordance with the postulates behind OOEH at the same time as they lent no support to the OOAH.

CONCLUSIONS

The conformity between the mtDNA and Y-DNA phylogenies of Hss is consistent with the understanding that Eurasia was the donor and not the receiver in human evolution. The evolutionary problems related to OOAH became similarly exposed by the mtDNA introgression that took place from Hss into Neanderthals ≈ 500,000 YBP, a circumstance that demonstrated the early coexistence of the two lineages in Eurasia.

Origins and Evolution of the Primate Hepatitis B Virus

Recent interest in the origins and subsequent evolution of the hepatitis B virus (HBV) has strengthened with the discovery of ancient HBV sequences in fossilized remains of humans dating back to the Neolithic period around 7,000 years ago. Metagenomic analysis identified a number of African non-human primate HBV sequences in the oldest samples collected, indicating that human HBV may have at some stage, evolved in Africa following zoonotic transmissions from higher primates. Ancestral genotype A and D isolates were also discovered from the Bronze Age, not in Africa but rather Eurasia, implying a more complex evolutionary and migratory history for HBV than previously recognized. Most full-length ancient HBV sequences exhibited features of inter genotypic recombination, confirming the importance of recombination and the mutation rate of the error-prone viral replicase as drivers for successful HBV evolution. A model for the origin and evolution of HBV is proposed, which includes multiple cross-species transmissions and favors subsequent recombination events that result in a pathogen and can successfully transmit and cause persistent infection in the primate host.

The primitive brain of early Homo

The brains of modern humans differ from those of great apes in size, shape, and cortical organization, notably in frontal lobe areas involved in complex cognitive tasks, such as social cognition, tool use, and language. When these differences arose during human evolution is a question of ongoing debate. Here, we show that the brains of early Homo from Africa and Western Asia (Dmanisi) retained a primitive, great ape-like organization of the frontal lobe. By contrast, African Homo younger than 1.5 million years ago, as well as all Southeast Asian Homo erectus, exhibited a more derived, humanlike brain organization. Frontal lobe reorganization, once considered a hallmark of earliest Homo in Africa, thus evolved comparatively late, and long after Homo first dispersed from Africa.

Continuous presence of proto-cereals in Anatolia since 2.3 Ma, and their possible co-evolution with large herbivores and hominins

Cereals are a central resource for the human diet and are traditionally assumed to have evolved from wild grasses at the onset of the Neolithic under the pressure of agriculture. Here we demonstrate that cereals may have a significantly longer and more diverse lineage, based on the study of a 0-2.3 Ma, 601 m long sedimentary core from Lake Acıgöl (South-West Anatolia). Pollen characteristic of cereals is abundant throughout the sedimentary sequence. The presence of large lakes within this arid bioclimatic zone led to the concentration of large herbivore herds, as indicated by the continuous occurrence of coprophilous fungi spores in the record. Our hypothesis is that the effects of overgrazing on soils and herbaceous stratum, during this long period, led to genetic modifications of the Poaceae taxa and to the appearance of proto-cereals. The simultaneous presence of hominins is attested as early as about 1.4 Ma in the lake vicinity, and 1.8 Ma in Georgia and Levant. These ancient hominins probably benefited from the availability of these proto-cereals, rich in nutrients, as well as various other edible plants, opening the way, in this region of the Middle East, to a process of domestication, which reached its full development during the Neolithic.

Coping with arid environments: A critical threshold for human expansion in Europe at the Marine Isotope Stage 12/11 transition? The case of the Iberian Peninsula

Archaeological remains have highlighted the fact that the interglacial Marine Isotope Stage (MIS) 11 was a threshold from the perspective of hominin evolution in Europe. After the MIS 12 glaciation, considered one of the major climate-driven crises experienced by hominins, the archaeological records show an increasing number of occupations, evidence of new subsistence behaviors, and significant technical innovations. Here, we used statistical and geographic techniques to analyze the amphibian- and reptile-based paleoclimate and habitat reconstructions generated from a large data set of the Iberian Peninsula to (1) investigate if temperature, precipitation, and/or forest cover may have impacted the hominin occupation of the territory during the Early and Middle Pleistocene, (2) propose an 'Iberian' ecological model before and after the MIS 12/11 transition, and (3) evaluate, based on this model, the potential hominin occupation at a European scale. The results indicate the existence of climatic constraints on human settlement related to rainfall and environmental humidity. The Early Pleistocene and the first half of the Middle Pleistocene are dominated by the occupation of relatively humid wooded areas, whereas during the second part of the Middle Pleistocene, a broadening of the earlier ecological niche is clearly observed toward the occupation of more open arid areas. Based on the estimated occupational niche for hominins, a maximum potential distribution for early hominins is proposed in Europe before and after 426 ka. Results also indicate that parts of the Iberian Peninsula may not have been suitable for early hominin occupation. Our ecological model is consistent with the pattern of hominin occupation observed in northern and central Europe, where the earliest evidence reflects only pioneering populations merely extending their ranges in response to the expansion of their preferred habitats, as compared with a more sustained occupation by 400 ka.

Earliest Olduvai hominins exploited unstable environments ~ 2 million years ago

Rapid environmental change is a catalyst for human evolution, driving dietary innovations, habitat diversification, and dispersal. However, there is a dearth of information to assess hominin adaptions to changing physiography during key evolutionary stages such as the early Pleistocene. Here we report a multiproxy dataset from Ewass Oldupa, in the Western Plio-Pleistocene rift basin of Olduvai Gorge (now Oldupai), Tanzania, to address this lacuna and offer an ecological perspective on human adaptability two million years ago. Oldupai's earliest hominins sequentially inhabited the floodplains of sinuous channels, then river-influenced contexts, which now comprises the oldest palaeolake setting documented regionally. Early Oldowan tools reveal a homogenous technology to utilise diverse, rapidly changing environments that ranged from fern meadows to woodland mosaics, naturally burned landscapes, to lakeside woodland/palm groves as well as hyper-xeric steppes. Hominins periodically used emerging landscapes and disturbance biomes multiple times over 235,000 years, thus predating by more than 180,000 years the earliest known hominins and Oldowan industries from the Eastern side of the basin.

The reversal of human phylogeny: Homo left Africa as erectus, came back as sapiens sapiens

Background

The molecular out of Africa hypothesis, OOAH, has been considered as an established fact amid population geneticists for some 25–30 years despite the early concern with it among phylogeneticists with experience beyond that of Homo. The palaeontological support for the hypothesis is also questionable, a circumstance that in the light of expanding Eurasian palaeontological knowledge has become accentuated through the last decades.

Results

The direction of evolution in the phylogenetic tree of modern humans (Homo sapiens sapiens, Hss) was established inter alia by applying progressive phylogenetic analysis to an mtDNA sampling that included a Eurasian, Lund, and the African Mbuti, San and Yoruba. The examination identified the African populations as paraphyletic, thereby compromising the OOAH. The finding, which was consistent with the out of Eurasia hypothesis, OOEH, was corroborated by the mtDNA introgression from Hss into Hsnn (Neanderthals) that demonstrated the temporal and physical Eurasian coexistence of the two lineages. The results are consistent with the palaeontologically established presence of H. erectus in Eurasia, a Eurasian divergence between H. sapiens and H. antecessor ≈ 850,000 YBP, an Hs divergence between Hss and Hsn (Neanderthals + Denisovans) ≈ 800,000 YBP, an mtDNA introgression from Hss into Hsnn* ≈ 500,000 YBP and an Eurasian divergence among the ancestors of extant Hss ≈ 250,000 YBP at the exodus of Mbuti/San into Africa.

Conclusions

The present study showed that Eurasia was not the receiver but the donor in Hss evolution. The findings that Homo left Africa as erectus and returned as sapiens sapiens constitute a change in the understanding of Hs evolution to one that conforms to the extensive Eurasian record of Hs palaeontology and archaeology.

Olduvai's oldest Oldowan

Previously, Olduvai Bed I excavations revealed Oldowan assemblages <1.85 Ma, mainly in the eastern gorge. New western gorge excavations locate a much older ∼2.0 Ma assemblage between the Coarse Feldspar Crystal Tuff (∼2.015 Ma) and Tuff IA (∼1.98 Ma) of Lower Bed I, predating the oldest eastern gorge DK assemblage below Tuff IB by ∼150 kyr. We characterize this newly discovered fossil and artifact assemblage, adding information on landscape and hominin resource use during the ∼2.3-2.0 Ma period, scarce in Oldowan sites. Assemblage lithics and bones, lithofacies boundaries, and phytolith samples were surveyed and mapped. Sedimentological facies analysis, tephrostratigraphic and sequence stratigraphic principles were applied to reconstruct paleoenvironments and sedimentary processes of sandy claystone (lake), sandstone (fluvial), and sandy diamictite (debris flow) as principal lithofacies. Artifacts, sized, weighed, categorized, were examined for petrography, retouch, and flake scar size. Taxonomic classifications and taphonomic descriptions of faunal remains were made, and phytoliths were categorized based on reference collections. Lithics are dominantly quartzite, mainly debitage and less frequently simple cores, retouched pieces, and percussors. Well-rounded spheroids and retouched flakes are rare. Identifiable taxa, Ceratotherium cf. simum (white rhinoceros) and Equus cf. oldowayensis (extinct zebra), accord with nearby open savanna grasslands, inferred from C₃ grass, mixed and/or alternating with C₄ grass-dominated phytolith assemblages. Palms, sedges, and dicots were also identified from phytoliths. Diatoms and sponge spicules imply nearby freshwater. The assemblage accumulated at the toe of a Ngorongoro Volcano-sourced fan-delta apron of stacked debris flows, fluvials, and tuffs, preserving fossil tree stumps and wooded grassland phytoliths farther upfan. It formed after the climax of Ngorongoro volcanic activity during a Paleolake Olduvai lowstand and was then buried and preserved by lacustrine clays, marking the first of two lake transgressions, signifying wetter climates. Orbital precessional lake cycles were superposed upon multimillennial (∼4.9 kyr) lake fluctuations.

What kind of hominin first left Africa?

Recent discoveries of stone tools from Jordan (2.5 Ma) and China (2.1 Ma) document hominin presence in Asia at the beginning of the Pleistocene, well before the conventional Dmanisi datum at 1.8 Ma. Although no fossil hominins documenting this earliest Out of Africa phase have been found, on chronological grounds a pre-Homo erectus hominin must be considered the most likely maker of those artifacts. If so, this sheds new light on at least two disputed subjects in paleoanthropology, namely the remarkable variation among the five Dmanisi skulls, and the ancestry of Homo floresiensis.

The human life history is adapted to exploit the adaptive advantages of culture

Humans evolved from an ape ancestor that was highly intelligent, moderately social and moderately dependent on cultural adaptations for subsistence technology (tools). By the late Pleistocene, humans had become highly dependent on culture for subsistence and for rules to organize a complex social life. Adaptation by cultural traditions transformed our life history, leading to an extended juvenile period to learn subsistence and social skills, post-reproductive survival to help conserve and transmit skills, a dependence on social support for mothers of large-brained, very dependent and nutrient-demanding offspring, males devoting substantial effort to provisioning rather than mating, and the cultivation of large social networks to tap pools in information unavailable to less social species. One measure of the success of the exploitation of culture is that the minimum inter-birth interval of humans is nearly half that of our ape relatives. Another measure is the wide geographical distribution of humans compared with other apes, based on subsistence systems adapted to fine-scale spatial environmental variation. An important macro-evolutionary question is why our big-brained, culture-intensive life-history strategy evolved so recently and in only our lineage. We suggest that increasing spatial and temporal variation in the Pleistocene favoured cultural adaptations. This article is part of the theme issue 'Life history and learning: how childhood, caregiving and old age shape cognition and culture in humans and other animals'.

Innovation, life history and social networks in human evolution

There is a famous puzzle about the first 3 million years of archaeologically visible human technological history. The pace of change, of innovation and its uptake, is extraordinarily slow. In particular, the famous handaxes of the Acheulian technological tradition first appeared about 1.7 Ma, and persisted with little change until about 800 ka, perhaps even longer. In this paper, I will offer an explanation of that stasis based in the life history and network characteristics that we infer (on phylogenetic grounds) to have characterized earlier human species. The core ideas are that (i) especially in earlier periods of hominin evolution, we are likely to find archaeological traces only of widespread and persisting technologies and practices; (ii) the record is not a record of the rate of innovation, but the rate of innovations establishing in a landscape; (iii) innovations are extremely vulnerable to stochastic loss while confined to the communities in which they are made and established; (iv) the export of innovation from the local group is sharply constrained if there is a general pattern of hostility and suspicion between groups, or even if there is just little contact between adults of adjoining groups. That pattern is typical of great apes and likely, therefore, to have characterized at least early hominin social lives. Innovations are unlikely to spread by adult-to-adult interactions across community boundaries. (v) Chimpanzees and bonobos are characterized by male philopatry and subadult female dispersal; that is, therefore, the most likely early hominin pattern. If so, the only innovations at all likely to expand beyond the point of origin are those acquired by subadult females, and ones that can be expressed by those females, at high enough frequency and salience for them to spread, in the bands that the females join. These are very serious filters on the spread of innovation. This article is part of the theme issue 'Life history and learning: how childhood, caregiving and old age shape cognition and culture in humans and other animals'.

Macaques in China: Evolutionary dispersion and subsequent development

Depicting a taxonomic group's evolutionary trajectory as a function of changes in the geographical landscape and its historical distribution is critical for constructing informed conservation strategies. Based on fossil sites from the Pliocene to the Holocene, and historical records since 1175 AD, we established macaques’ dispersal pathways into and through China. These routes include internal pathways starting from the southeast corner of the Qinghai‐Tibet Plateau and Mts. Hengduan in western China, and the routes through the estuaries of the three major rivers (Yangtze, Yellow, and Pearl). Our results indicate that macaques used the three rivers and avoided the higher elevation of the plateaus to promote their radiation. They occupied the whole mainland and islands in the Pleistocene and experienced shrunken distribution in the Holocene due to climate changes and human‐induced activities. A prominent China‐wide reduction occurred between 1817 and 1917; and a remarkable retraction from central China happened between 1918 and 2018 following further eco‐social development and human expansion in central China, particularly since the second half of the last century. Starting in 1175 there was a restriction of range to higher altitudes, so that macaques have contracted their range to the west, and the Qinghai‐Tibet Plateau and Mts. Hengduan have become an important sanctuary. We predict that if the current climate and human‐induced changes are not reversed by decisive conservation actions, macaques in east and central China will likely be extinct in the near future.

Major waterways used by the primates to disperse and radiate in China

Primate evolution and dispersion in East Asia from the Pliocene to the Early Holocene

Historically shrunk macaque distribution in China

Contemporaneity of Australopithecus, Paranthropus, and early Homo erectus in South Africa

Understanding the extinction of Australopithecus and origins of Paranthropus and Homo in South Africa has been hampered by the perceived complex geological context of hominin fossils, poor chronological resolution, and a lack of well-preserved early Homo specimens. We describe, date, and contextualize the discovery of two hominin crania from Drimolen Main Quarry in South Africa. At ~2.04 million to 1.95 million years old, DNH 152 represents the earliest definitive occurrence of Paranthropus robustus, and DNH 134 represents the earliest occurrence of a cranium with clear affinities to Homo erectus These crania also show that Homo, Paranthropus, and Australopithecus were contemporaneous at ~2 million years ago. This high taxonomic diversity is also reflected in non-hominin species and provides evidence of endemic evolution and dispersal during a period of climatic variability.

Technological innovations at the onset of the Mid-Pleistocene Climate Transition in high-latitude East Asia

The interplay between Pleistocene climatic variability and hominin adaptations to diverse terrestrial ecosystems is a key topic in human evolutionary studies. Early and Middle Pleistocene environmental change and its relation to hominin behavioural responses has been a subject of great interest in Africa and Europe, though little information is available for other key regions of the Old World, particularly from Eastern Asia. Here we examine key Early Pleistocene sites of the Nihewan Basin, in high-latitude northern China, dating between ∼1.4 and 1.0 million years ago (Ma). We compare stone-tool assemblages from three Early Pleistocene sites in the Nihewan Basin, including detailed assessment of stone-tool refitting sequences at the ∼1.1-Ma-old site of Cenjiawan. Increased toolmaking skills and technological innovations are evident in the Nihewan Basin at the onset of the Mid-Pleistocene Climate Transition (MPT). Examination of the lithic technology of the Nihewan sites, together with an assessment of other key Palaeolithic sites of China, indicates that toolkits show increasing diversity at the outset of the MPT and in its aftermath. The overall evidence indicates the adaptive flexibility of early hominins to ecosystem changes since the MPT, though regional abandonments are also apparent in high latitudes, likely owing to cold and oscillating environmental conditions. The view presented here sharply contrasts with traditional arguments that stone-tool technologies of China are homogeneous and continuous over the course of the Early Pleistocene.

Hyena paleogenomes reveal a complex evolutionary history of cross-continental gene flow between spotted and cave hyena

The genus Crocuta (African spotted and Eurasian cave hyenas) includes several closely related extinct and extant lineages. The relationships among these lineages, however, are contentious. Through the generation of population-level paleogenomes from late Pleistocene Eurasian cave hyena and genomes from modern African spotted hyena, we reveal the cross-continental evolutionary relationships between these enigmatic hyena lineages. We find a deep divergence (~2.5 Ma) between African and Eurasian Crocuta populations, suggesting that ancestral Crocuta left Africa around the same time as early Homo. Moreover, we find discordance between nuclear and mitochondrial phylogenies and evidence for bidirectional gene flow between African and Eurasian Crocuta after the lineages split, which may have complicated prior taxonomic classifications. Last, we find a number of introgressed loci that attained high frequencies within the recipient lineage, suggesting some level of adaptive advantage from admixture.

Social evolution in Plio-Pleistocene hominins: Insights from hamadryas baboons and paleoecology

Reconstructions of hominin evolution have long benefited from comparisons with nonhuman primates, especially baboons and chimpanzees. The hamadryas baboon (Papio hamadryas) is arguably one of the best such models, as it exhibits both the male kin bonding and the cross-sex pair bonding thought to have been important in hominin evolution. Here we link processes of behavioral evolution in hamadryas baboons with those in a Plio-Pleistocene hominin, provisionally identified as Homo erectus (sensu lato) - a pivotal species in that its larger body and brain size and wider ranging patterns increased female costs of reproduction, increasing the importance of sociality. The combination of these higher costs of reproduction and shifts in diet and food acquisition have previously been argued to have been alleviated either via strengthening of male-female bonds (involving male provisioning and the evolution of monogamy) or via the assistance of older, post-reproductive females (leading to post-reproductive longevity in females, i.e., the grandmother hypothesis). We suggest that both arrangements could have been present in Plio-Pleistocene hominins if they lived in multilevel societies. Here we expand on our earlier scenario with two sets of recent data in support of it, (1) archaeological data from the 2 million year old Oldowan site of Kanjera South, Kenya and other sites that are suggestive of tool dependent foraging on nutrient dense resources (animal carcasses and plant underground storage organs), cooperation, and food sharing; and (2) a pattern of genetic variation in hamadryas baboons that suggests the operation of kin selection among both males and females at multiple levels of society. Taken together, these two sets of data strengthen our model and support the idea of a complex society linked by male-male, male-female, and female-female bonds at multiple levels of social organization in Plio-Pleistocene hominins.

Language, Memory, and Mental Time Travel: An Evolutionary Perspective

Language could not exist without memory, in all its forms: working memory for sequential production and understanding, implicit memory for grammatical rules, semantic memory for knowledge, and episodic memory for communicating personal experience. Episodic memory is part of a more general capacity for mental travel both forward and backward in time, and extending even into fantasy and stories. I argue that the generativity of mental time travel underlies the generativity of language itself, and could be the basis of what Chomsky calls I-language, or universal grammar (UG), a capacity for recursive thought independent of communicative language itself. Whereas Chomsky proposed that I-language evolved in a single step well after the emergence of Homo sapiens, I suggest that generative imagination, extended in space and time, has a long evolutionary history, and that it was the capacity to share internal thoughts, rather than the nature of the thoughts themselves, that more clearly distinguishes humans from other species.

Out of Africa by spontaneous migration waves

Hominin evolution is characterized by progressive regional differentiation, as well as migration waves, leading to anatomically modern humans that are assumed to have emerged in Africa and spread over the whole world. Why or whether Africa was the source region of modern humans and what caused their spread remains subject of ongoing debate. We present a spatially explicit, stochastic numerical model that includes ongoing mutations, demic diffusion, assortative mating and migration waves. Diffusion and assortative mating alone result in a structured population with relatively homogeneous regions bound by sharp clines. The addition of migration waves results in a power-law distribution of wave areas: for every large wave, many more small waves are expected to occur. This suggests that one or more out-of-Africa migrations would probably have been accompanied by numerous smaller migration waves across the world. The migration waves are considered "spontaneous", as the current model excludes environmental or other extrinsic factors. Large waves preferentially emanate from the central areas of large, compact inhabited areas. During the Pleistocene, Africa was the largest such area most of the time, making Africa the statistically most likely origin of anatomically modern humans, without a need to invoke additional environmental or ecological drivers.

Disentangling isolated dental remains of Asian Pleistocene hominins and pongines

Scholars have debated the taxonomic identity of isolated primate teeth from the Asian Pleistocene for over a century, which is complicated by morphological and metric convergence between orangutan (Pongo) and hominin (Homo) molariform teeth. Like Homo erectus, Pongo once showed considerable dental variation and a wide distribution throughout mainland and insular Asia. In order to clarify the utility of isolated dental remains to document the presence of hominins during Asian prehistory, we examined enamel thickness, enamel-dentine junction shape, and crown development in 33 molars from G. H. R. von Koenigswald's Chinese Apothecary collection (11 Sinanthropus officinalis [= Homo erectus], 21 "Hemanthropus peii," and 1 "Hemanthropus peii" or Pongo) and 7 molars from Sangiran dome (either Homo erectus or Pongo). All fossil teeth were imaged with non-destructive conventional and/or synchrotron micro-computed tomography. These were compared to H. erectus teeth from Zhoukoudian, Sangiran and Trinil, and a large comparative sample of fossil Pongo, recent Pongo, and recent human teeth. We find that Homo and Pongo molars overlap substantially in relative enamel thickness; molar enamel-dentine junction shape is more distinctive, with Pongo showing relatively shorter dentine horns and wider crowns than Homo. Long-period line periodicity values are significantly greater in Pongo than in H. erectus, leading to longer crown formation times in the former. Most of the sample originally assigned to S. officinalis and H. erectus shows greater affinity to Pongo than to the hominin comparative sample. Moreover, enamel thickness, enamel-dentine junction shape, and a long-period line periodicity value in the "Hemanthropus peii" sample are indistinguishable from fossil Pongo. These results underscore the need for additional recovery and study of associated dentitions prior to erecting new taxa from isolated teeth.