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A case of inter-group violence among hunter-gatherers on the shores of Lake Turkana in Kenya 10,000 years ago. An early instance of human conflict Violence and warfare have shaped human societies for many thousands of years, but the origins of inter-group conflict in the archaeological record are controversial, dependent on how such conflicts are defined and recognized, as well as on the lottery of preservation. Marta Mirazón Lahr et al . report fossil finds from Nataruk in northern Kenya that point to a case of inter-group violence among hunter-gatherers in the early Holocene. Ten out of twelve skeletons, discovered near what was once a small lagoon, show evidence of having undergone violent deaths. There were no signs of deliberate burial, and several individuals have multiple major traumatic lesions — including an obsidian bladelet embedded in one of the skulls. The authors interpret this assemblage as the aftermath of a violent inter-group encounter that took place some 10,000 years ago on the fertile shores of Lake Turkana. The nature of inter-group relations among prehistoric hunter-gatherers remains disputed, with arguments in favour and against the existence of warfare before the development of sedentary societies 1 , 2 . Here we report on a case of inter-group violence towards a group of hunter-gatherers from Nataruk, west of Lake Turkana, which during the late Pleistocene/early Holocene period extended about 30 km beyond its present-day shore 3 . Ten of the twelve articulated skeletons found at Nataruk show evidence of having died violently at the edge of a lagoon, into which some of the bodies fell. The remains from Nataruk are unique, preserved by the particular conditions of the lagoon with no evidence of deliberate burial. They offer a rare glimpse into the life and death of past foraging people, and evidence that warfare was part of the repertoire of inter-group relations among prehistoric hunter-gatherers.

Carbon isotope studies of early hominins from southern Africa showed that their diets differed markedly from the diets of extant apes. Only recently, however, has a major influx of isotopic data from eastern Africa allowed for broad taxonomic, temporal, and regional comparisons among hominins. Before 4 Ma, hominins had diets that were dominated by C ₃ resources and were, in that sense, similar to extant chimpanzees. By about 3.5 Ma, multiple hominin taxa began incorporating ¹³C-enriched [C ₄ or crassulacean acid metabolism (CAM)] foods in their diets and had highly variable carbon isotope compositions which are atypical for African mammals. By about 2.5 Ma, Paranthropus in eastern Africa diverged toward C ₄/CAM specialization and occupied an isotopic niche unknown in catarrhine primates, except in the fossil relations of grass-eating geladas (Theropithecus gelada). At the same time, other taxa (e.g., Australopithecus africanus) continued to have highly mixed and varied C ₃/C ₄ diets. Overall, there is a trend toward greater consumption of ¹³C-enriched foods in early hominins over time, although this trend varies by region. Hominin carbon isotope ratios also increase with postcanine tooth area and mandibular cross-sectional area, which could indicate that these foods played a role in the evolution of australopith masticatory robusticity. The ¹³C-enriched resources that hominins ate remain unknown and must await additional integration of existing paleodietary proxy data and new research on the distribution, abundance, nutrition, and mechanical properties of C ₄ (and CAM) plants.

The past two million years of eastern African climate variability is currently poorly constrained, despite interest in understanding its assumed role in early human evolution 1 – 4 . Rare palaeoclimate records from northeastern Africa suggest progressively drier conditions 2 , 5 or a stable hydroclimate 6 . By contrast, records from Lake Malawi in tropical southeastern Africa reveal a trend of a progressively wetter climate over the past 1.3 million years 7 , 8 . The climatic forcings that controlled these past hydrological changes are also a matter of debate. Some studies suggest a dominant local insolation forcing on hydrological changes 9 – 11 , whereas others infer a potential influence of sea surface temperature changes in the Indian Ocean 8 , 12 , 13 . Here we show that the hydroclimate in southeastern Africa (20–25° S) is controlled by interplay between low-latitude insolation forcing (precession and eccentricity) and changes in ice volume at high latitudes. Our results are based on a multiple-proxy reconstruction of hydrological changes in the Limpopo River catchment, combined with a reconstruction of sea surface temperature in the southwestern Indian Ocean for the past 2.14 million years. We find a long-term aridification in the Limpopo catchment between around 1 and 0.6 million years ago, opposite to the hydroclimatic evolution suggested by records from Lake Malawi. Our results, together with evidence of wetting at Lake Malawi, imply that the rainbelt contracted toward the Equator in response to increased ice volume at high latitudes. By reducing the extent of woodland or wetlands in terrestrial ecosystems, the observed changes in the hydroclimate of southeastern Africa—both in terms of its long-term state and marked precessional variability—could have had a role in the evolution of early hominins, particularly in the extinction of Paranthropus robustus . A multiple-proxy reconstruction for the catchment of the Limpopo River and of sea surface temperatures in the Indian Ocean provides evidence for hydroclimatic changes that may have been important in hominin evolution.

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.

Considerable attention has been paid to dating the earliest appearance of hominins outside Africa. The earliest skeletal and artefactual evidence for the genus Homo in Asia currently comes from Dmanisi, Georgia, and is dated to approximately 1.77–1.85 million years ago (Ma) 1 . Two incisors that may belong to Homo erectus come from Yuanmou, south China, and are dated to 1.7 Ma 2 ; the next-oldest evidence is an H. erectus cranium from Lantian (Gongwangling)—which has recently been dated to 1.63 Ma 3 —and the earliest hominin fossils from the Sangiran dome in Java, which are dated to about 1.5–1.6 Ma 4 . Artefacts from Majuangou III 5 and Shangshazui 6 in the Nihewan basin, north China, have also been dated to 1.6–1.7 Ma. Here we report an Early Pleistocene and largely continuous artefact sequence from Shangchen, which is a newly discovered Palaeolithic locality of the southern Chinese Loess Plateau, near Gongwangling in Lantian county. The site contains 17 artefact layers that extend from palaeosol S15—dated to approximately 1.26 Ma—to loess L28, which we date to about 2.12 Ma. This discovery implies that hominins left Africa earlier than indicated by the evidence from Dmanisi. An Early Pleistocene artefact assemblage from the Chinese Loess Plateau indicates that hominins had left Africa by at least 2.1 million years ago, and occupied the Loess Plateau repeatedly for a long time.

Long paleoecological records are critical for understanding evolutionary responses to environmental forcing and unparalleled tools for elucidating the mechanisms that lead to the development of regions of high biodiversity. We use a 1.2-My record from Lake Malawi, a textbook example of biological diversification, to document how climate and tectonics have driven ecosystem and evolutionary dynamics. Before ∼800 ka, Lake Malawi was much shallower than today, with higher frequency but much lower amplitude waterlevel and oxygenation changes. Since ∼800 ka, the lake has experienced much larger environmental fluctuations, best explained by a punctuated, tectonically driven rise in its outlet location and level. Following the reorganization of the basin, a change in the pacing of hydroclimate variability associated with the Mid-Pleistocene Transition resulted in hydrologic change dominated by precession rather than the high-latitude teleconnections recorded elsewhere. During this time, extended, deep lake phases have abruptly alternated with times of extreme aridity and ecosystem variability. Repeated crossings of hydroclimatic thresholds within the lake system were critical for establishing the rhythm of diversification, hybridization, and extinction that dominate the modern system. The chronology of these changes closely matches both the timing and pattern of phylogenetic history inferred independently for the lake’s extraordinary array of cichlid fish species, suggesting a direct link between environmental and evolutionary dynamics.

The role of African savannahs in the evolution of early hominins has been debated for nearly a century. Resolution of this issue has been hindered by difficulty in quantifying the fraction of woody cover in the fossil record. Here we show that the fraction of woody cover in tropical ecosystems can be quantified using stable carbon isotopes in soils. Furthermore, we use fossil soils from hominin sites in the Awash and Omo-Turkana basins in eastern Africa to reconstruct the fraction of woody cover since the Late Miocene epoch (about 7 million years ago). 13 C/ 12 C ratio data from 1,300 palaeosols at or adjacent to hominin sites dating to at least 6 million years ago show that woody cover was predominantly less than ∼40% at most sites. These data point to the prevalence of open environments at the majority of hominin fossil sites in eastern Africa over the past 6 million years. To the woods: the landscape of human evolution It is widely recognized that the last common ancestor we share with modern chimpanzees inhabited wooded environments, and that hominin habitats became less wooded after this divergence some 5 million to 8 million years ago. What happened to our ancestors next is less clear, although it is speculated that bipedality and a change of diet may reflect a transition to open savannah grasslands. Thure Cerling and colleagues demonstrate that the fraction of woody cover can be quantified in modern tropical ecosystems and that the method can be extended into the geological past. Analysis of fossil soils from many localities associated with early hominins, such as Ardipithecus , shows a savannah-like environment with less than 40% tree cover, rather than the closed woodland commonly assumed. Moreover, woodland became more closed, rather than less, after hominins became more fully bipedal.

Adaptive radiations have been instrumental in generating a considerable amount of life’s diversity. Ecological opportunity is thought to be a prerequisite for adaptive radiation 1 , but little is known about the relative importance of species’ ecological versatility versus effects of arrival order in determining which lineage radiates 2 . Palaeontological records that could help answer this are scarce. In Lake Victoria, a large adaptive radiation of cichlid fishes evolved in an exceptionally short and recent time interval 3 . We present a rich continuous fossil record extracted from a series of long sediment cores along an onshore–offshore gradient. We reconstruct the temporal sequence of events in the assembly of the fish community from thousands of tooth fossils. We reveal arrival order, relative abundance and habitat occupation of all major fish lineages in the system. We show that all major taxa arrived simultaneously as soon as the modern lake began to form. There is no evidence of the radiating haplochromine cichlid lineage arriving before others, nor of their numerical dominance upon colonization; therefore, there is no support for ecological priority effects. However, although many taxa colonized the lake early and several became abundant, only cichlids persisted in the new deep and open-water habitats once these emerged. Because these habitat gradients are also known to have played a major role in speciation, our findings are consistent with the hypothesis that ecological versatility was key to adaptive radiation, not priority by arrival order nor initial numerical dominance. This study presents a continuous fossil record, extracted from a series of sediment cores, that shows how haplochromine cichlids came to dominate the fish fauna of Lake Victoria in Africa.

Reductions in hunter-gatherer mobility during the Late Pleistocene influenced settlement ecologies, altered human relations with animal communities, and played a pivotal role in domestication. The influence of variability in human mobility on selection dynamics and ecological interactions in human settlements has not been extensively explored, however. This study of mice in modern African villages and changing mice molar shapes in a 200,000-y-long sequence from the Levant demonstrates competitive advantages for commensal mice in long-term settlements. Mice from African pastoral households provide a referential model for habitat partitioning among mice taxa in settlements of varying durations. The data reveal the earliest known commensal niche for house mice in long-term forager settlements 15,000 y ago. Competitive dynamics and the presence and abundance of mice continued to fluctuate with human mobility through the terminal Pleistocene. At the Natufian site of Ain Mallaha, house mice displaced less commensal wild mice during periods of heavy occupational pressure but were outcompeted when mobility increased. Changing food webs and ecological dynamics in long-term settlements allowed house mice to establish durable commensal populations that expanded with human societies. This study demonstrates the changing magnitude of cultural niche construction with varying human mobility and the extent of environmental influence before the advent of farming.

The expansion of modern human populations in Africa 80,000 to 60,000 years ago and their initial exodus out of Africa have been tentatively linked to two phases of technological and behavioral innovation within the Middle Stone Age of southern Africa--the Still Bay and Howieson's Poort industries--that are associated with early evidence for symbols and personal ornaments. Establishing the correct sequence of events, however, has been hampered by inadequate chronologies. We report ages for nine sites from varied climatic and ecological zones across southern Africa that show that both industries were short-lived (5000 years or less), separated by about 7000 years, and coeval with genetic estimates of population expansion and exit times. Comparison with climatic records shows that these bursts of innovative behavior cannot be explained by environmental factors alone.