During the terminal Pleistocene through Holocene, changes in dietary diversity signaled fundamental shifts in the way humans related to food resources in many parts of the globe. To understand local and regional dietary variation across the transition to food production in Kenya and Tanzania, we compare isotopic values of biological tissues (tooth enamel and bone collagen) from 111 ancient foragers and herders dated ~9,500-230 B.P., alongside isotopic data from contemporary eastern Africans, and contextualize these findings with ancient leaf wax and ceramic lipid residues. Fisher-foragers had remarkably diverse approaches to subsistence, and the earliest pastoralists in Kenya's Turkana Basin ~5,000 years ago retained dietary diversity amid major environmental and cultural changes. The shift to more specialized pastoralist diets did not occur until a millennium after the initial introduction of livestock.

During the course of human evolution, lithic technology became a critical element of hominin foraging ecology and a contributor to feedback loops selecting for increasingly sophisticated tool use, cognition, and language. Here we review the first million years of technology, from 3.3 million years ago (Ma) to 2.3 Ma. This time interval includes the two oldest archaeological industries (the Lomekwian and the early Oldowan) known exclusively from Africa, which collectively overlap with four genera of hominins (human relatives and ancestors). These Early Stone Age (ESA) industries focused on the production and use of sharp edges for cutting, as well as the use of larger, sometimes unworked stones for pounding. We review our current understanding of these technologies, where they were found, how they were made, what they were used for, and the hominins that could have produced them, and consider them in the context of nonhuman primate archaeology.

This study presents a comprehensive examination of the function of 26 percussive stone tools (PSTs) from Nyayanga, an Oldowan site located on the Homa Peninsula in southwestern Kenya. These artifacts, dating between 3.032 to 2.581 million years ago, were found together with hominin remains and animal fossils with stone tool butchery damage. To determine the function of the PSTs, we adopted a multiscale approach that combines qualitative use-wear analysis using microscopic techniques at low and high power approaches with quantitative analysis, employing 3D surface models generated with profilometry. These analyses indicate that Nyayanga hominins used PSTs to access both plant (e.g., USOs) and animal (bone marrow) nutrients. The inferred multifunctionality of these tools hints at diverse dietary strategies and contributes to our understanding of human technological evolution.

The adaptive shift that favored stone tool-assisted behavior in hominins began by 3.3 million years ago. However, evidence from early archaeological sites indicates relatively short-distance stone transport dynamics similar to behaviors observed in nonhuman primates. Here we report selective raw material transport over longer distances than expected at least 2.6 million years ago. Hominins at Nyayanga, Kenya, manufactured Oldowan tools primarily from diverse nonlocal stones, pushing back the date for expanded raw material transport by over half a million years. Nonlocal cobbles were transported up to 13 kilometers for on-site reduction, resulting in assemblage patterns inconsistent with accumulations formed by repeated short-distance transport events. These findings demonstrate that early toolmakers moved stones over substantial distances, possibly in anticipation of food processing needs, representing the earliest archaeologically visible signal for the incorporation of lithic technology into landscape-scale foraging repertoires.

The Homa Peninsula, in southwestern Kenya, continues to yield insights into Oldowan hominin landscape behaviors. The Late Pliocene locality of Nyayanga (-3 - 2.6 Ma) preserves some of the oldest Oldowan tools. At the Early Pleistocene locality of Kanjera South (-2 Ma) toolmakers procured a diversity of raw materials from over 10 km away and strategically reduced them in a grassland -dominated ecosystem. Here, we report findings from Sare-Abururu, a younger (-1.7 Ma) Oldowan locality approximately 12 km southeast of Kanjera South and 18 km east of Nyayanga. Sare-Abururu has yielded 1754 artifacts in relatively undisturbed low -energy silts and sands. Stable isotopic analysis of pedogenic carbonates suggests that hominin activities were carried out in a grassland -dominated setting with similar vegetation structure as documented at Kanjera South. The composition of a nearby paleo-conglomerate indicates that high -quality stone raw materials were locally abundant. Toolmakers at Sare-Abururu produced angular fragments from quartz pebbles, representing a considerable contrast to the strategies used to reduce high quality raw materials at Kanjera South. Although lithic reduction at SareAbururu was technologically simple, toolmakers proficiently produced cutting edges, made few mistakes and exhibited a mastery of platform management, demonstrating that expedient technical strategies do not necessarily indicate a lack of skill or suitable raw materials. Lithic procurement and reduction patterns on the Homa Peninsula appear to reflect variation in local resource contexts rather than large-scale evolutionary changes in mobility, energy budget, or toolmaker cognition.

The oldest Oldowan tool sites, from around 2.6 million years ago, have previously been confined to Ethiopia’s Afar Triangle. We describe sites at Nyayanga, Kenya, dated to 3.032 to 2.581 million years ago and expand this distribution by over 1300 kilometers. Furthermore, we found two hippopotamid butchery sites associated with mosaic vegetation and a C 4 grazer–dominated fauna. Tool flaking proficiency was comparable with that of younger Oldowan assemblages, but pounding activities were more common. Tool use-wear and bone damage indicate plant and animal tissue processing. Paranthropus sp. teeth, the first from southwestern Kenya, possessed carbon isotopic values indicative of a diet rich in C 4 foods. We argue that the earliest Oldowan was more widespread than previously known, used to process diverse foods including megafauna, and associated with Paranthropus from its onset.

The shift to increased meat consumption is one of the major adaptive changes in hominin dietary evolution. Although meat eating by Oldowan hominins is well evidenced at Pleistocene archaeological sites in eastern Africa by butchery marks on bones, the methods through which carcasses were acquired (i.e., hunting vs. scavenging) and extent of their completeness (fleshed vs. defleshed) is less certain. This study addresses these issues through a geographic information systems (GIS) comparative analysis of bone modification patterns created by hominins and carnivores observed in the ca. 2.0 Ma assemblage from Kanjera South, Kenya and those of several modern, experimentally modified bone assemblages. Comparison of GIS-generated models shows that the pattern of bone preservation at Kanjera South is similar to that found in experimental bone assemblages that were first butchered and hammerstone fractured by humans, and subsequently scavenged by carnivores. The distribution of bone modifications on the Kanjera fauna also suggests hominins had early access to small bovids. Butchery marks appear almost exclusively in 'hot zones'-areas where flesh does not typically survive lion consumption-further suggesting Kanjera hominins were not scavenging carnivore kills. Our findings support previous claims that the Kanjera assemblage offers the earliest clear evidence of repeated butchery of antelope carcasses by Early Stone Age (Oldowan) hominins and perhaps the earliest evidence for hunting. Kanjera carnivore damage frequencies are lower than those reported for the slightly younger site of FLK Zinj (Olduvai Gorge, Tanzania), suggesting differing competitive regimes at the two sites. (C) 2021 Elsevier Ltd. All rights reserved.

The Homa Peninsula has been known to science since 1911, and fossil specimens from the area comprise many type specimens for common African mammalian paleospecies. Here we discuss the fauna and the paleoenvironmental information from the Homa Peninsula. The Homa Peninsula is a 200 km2 area in Homa Bay County, situated on the southern margin of the Winam Gulf of Lake Victoria in Kenya (Figure 29.1). Lake Victoria is estimated to be the third largest lake in the world, with a surface area of 68,900 km2 and a maximum length of approximately 616 km. Although its catchment is extensive, it is relatively shallow compared to any other lake of similar size, with a maximum depth of 84 m. Lake Victoria is located in a depression formed by the western and eastern branches of the East African Rift System (EARS), and is at an average elevation of 1135 m a.s.l. (Database for Hydrological Time Series of Inland Waters, 2017).

The aspects of hominin behavior responsible for Oldowan stone tool variation are the focus of much debate. There is some consensus that this variation arises from a combination of ecological and cultural factors. The diversity of raw material types and technological strategies present at Kanjera South, Kenya, provide an opportunity to examine the interacting influences of ecology and culture on Oldowan stone tool variation. Here, we combine previous analyses of raw material properties, provenance, and technology with quantitative measures of core reduction intensity and tool utilization to examine the influence of both ecological and technocultural factors on stone tool variation at Kanjera South. The results of this analysis reflect a dynamic relationship between raw material properties, provenance, and hominin mobility. Exotic raw materials are generally more resistant to edge attrition compared with those available locally, which may have incentivized their transport over long distances and more extensive reduction. Cores produced on raw materials from distant sources also exhibit more complex core reduction strategies than locally acquired materials. While this pattern is partially due to the differences in the quality of knappable stone, bifacial centripetal and multifacial core reduction strategies also arise due to the continuous transport and use of exotic raw materials. Moreover, the variation in stone tool reduction is not consistent with neutral models of stone tool transport and discard. These results demonstrate that ecological factors such as raw material provenance and physical properties have strong impacts on reduction intensity and the technological strategies used by hominins.

Many geological contexts lack suitable material for commonly applied absolute dating methods. Even if some regions contain potentially datable materials, they may be inappropriate for dating by existing geochronological techniques. Paleoanthropological localities on the Homa Peninsula, southwestern Kenya, have yielded important paleoanthropological material. These localities are, however, poorly constrained in time, and few radioisotopic ages have been published, because sediments derived from the Homa Mountain carbonatite complex commonly do not contain zircons for U-Pb dating or feldspars for 40Ar/39Ar dating. Additionally, apatite grains that are present have failed to produce precise isotope dilution-thermal ionization mass spectrometer (ID-TIMS) results due to their high common lead content. Apatite (U-Th)/He dating using single-crystal laser fusion He determinations and the U-Th isotope dilution method was applied to three formations with well-constrained ages to test the suitability of this technique for dating sediments on the peninsula. Two of the three Kanam Formation samples provide dates close to the approximately 6 million year age (Ma) provided by 40Ar/39Ar dates. The Abundu Formation was dated to 2.39 +/- 0.29 Ma overlapping with the age of the Rawi Formation (C2An.1n Subchron, 3.05-2.59 Ma) to which it has been correlated. The age for the Kanjera South Member 1.54 +/- 0.85 Ma overlaps with the expected 2 Ma age, though it has a large uncertainty. The apatite raw (U-Th)/He ages are somewhat younger than the expected dates, but the technique shows promise.

Determining the provenance of archeological material is essential for documenting the movement of ancient resources and placing fossils and artifacts in the correct stratigraphic context. Non-destructive geochemical compositional analysis with Energy Dispersive X-ray Fluorescence (ED-XRF) spectrometry has the potential to provide a versatile approach to studying the provenance of archeological material. It is possible to build large regional XRF datasets that are useful for understanding the movements of toolmakers because this technique can be applied to a large number of samples non-destructively. However, incorporating new provenance data into existing datasets poses several potential challenges. Expanded provenance datasets often require the comparison of geochemical data across XRF instruments and settings. In particular the addition of different lithologies requires an understanding of diverse degrees of surface weathering and matrix heterogeneity.On the Homa Peninsula in Kenya, Oldowan tools from Kanjera South were previously linked to primary and secondary sources based on trace element geochemistry determined through ED-XRF. In this study, we established comparability across two ED-XRF instruments and incorporated samples from additional sources of quartzite and rhyolite into the existing raw material sourcing dataset. The new sources revealed regional differences in the geochemistry of rhyolite and quartzite that derive from drainages on and around the Homa Peninsula. This demonstrates the compatibility of quartzite and rhyolite materials with non-destructive ED-XRF sourcing and provides a methodological establishment of cross-study comparison in elemental values derived from non-uniform whole rock samples. This study highlights the importance of calibration using overlapping reference standards and linear regressions to determine offsets necessary for direct comparison.

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.

The archaeological record has documented Oldowan hominin occupation of habitats ranging from open grasslands to riparian forest by 2.0 Ma. Despite this we have a poor understanding of whether hominin foraging behavior varied in different environmental settings. We compared bovid mortality profiles from the two largest Oldowan zooarchaeological samples, one from a grassland (Excavation 1, Kanjera South, Kenya) and another from a woodland (FLK Zinj, Olduvai Gorge, Tanzania) with bovid mortality samples created by African carnivores in different habitats. Kanjera hominins frequently had early access, likely through hunting, to small (size 1 <= 23 kg and size 2 = 24-112 kg) juvenile bovids, creating a mortality pattern similar to that created by grassland dwelling carnivores. Kanjera hominins had more mixed access to large (size 3 = 113-340 kg), often juvenile, bovids and frequently scavenged heads. In contrast, previous work has shown that the few small bovids at FLK-Zinj were predominantly older individuals. Prime adults dominated the FLK-Zinj large bovid sample, leading to a mortality pattern similar to that created by carnivores occupying more closed habitats. Variation in bovid body size and mortality profiles between these archaeological assemblages may reflect the challenges of acquiring fauna in open versus closed habitats with a simple hunting toolkit. The heterogeneous woodland habitat of FLK-Zinj would have provided more opportunities to ambush prey, whereas on grasslands with more limited concealment opportunities Kanjera hominins focused their efforts on vulnerable juvenile prey, some likely acquired after short chases. (C) 2019 Elsevier Ltd. All rights reserved.

We investigate how oxygen isotopes in equid teeth can be used as a record of seasonality. First, we use in situ laser ablation and conventional microsampling techniques to understand time-averaging of environmental signals in intra-tooth isotope profiles in modern feral horse teeth (n = 5) from Mongolia, where there is a large seasonal gradient in the oxygen isotopic composition of precipitation. We demonstrate that laser ablation can be used to sample inner, middle, and outer enamel layers in large mammalian herbivore teeth. The inner enamel layer records less attenuated isotopic signals than other layers, as predicted by the mineralization patterns, but intra-tooth signal amplitude is similar for laser and conventional sampling methods. Second, we use modern zebra teeth (n = 21) collected in eastern Africa to evaluate how intra-tooth oxygen isotope variation relates to rainfall patterns in the tropics. We show that the intra-tooth isotopic range increases with intra-annual precipitation isotopic range, which in turn relates to aridity in the equatorial bimodal rainfall region but is influenced by other hydroclimate processes in the region as a whole. Finally, we address isotopic seasonality during the Early Pleistocene in eastern Africa using oxygen isotopes in fossil equid teeth from southwestern Kenya (n = 11) and northern Tanzania (n = 5). We find variable isotopic seasonality in the past, similar to present-day eastern Africa, consistent with the notion that hominins and other mammals were able to accommodate environmental variability on intra-annual scales in addition to well-documented orbital cycles. (C) 2019 Elsevier Ltd. All rights reserved.

This paper investigates Oldowan hominin behavioral ecology through use-wear analysis of artifacts from Kanjera South, Western Kenya. It extends development of our experimental use-wear reference collection and analysis of use-wear on the well preserved and unweathered Oldowan tools from this site to include rhyolite, a non-local material of similar durability to previously studied quartz and quartzite tools, and fenetized andesite, a local material with considerably less durability. Variability in rhyolite and fenetized andesite texture, inclusions, and matrix required enhancement of previous methods so we combine the use of stereoscopic, metallographic, and scanning electron microscopy in this study. This study allows us to begin exploration of the links between specific artifactual raw materials and the materials they were used to process. Data assembled so far suggest that tools fashioned from non-local and local stone were, with one possible exception, used to process similar materials. Additionally, experiments carried out with replicas of tools made of rhyolite and fenetized andesite confirm interpretation of reduction sequences that tools made of less durable local material had a shorter use-life and were used expediently compared to the more durable non-local quartz, quartzite, and rhyolite. These new data improve our understanding, of the functional needs, behavioral solutions, and cognitive capacities of Oldowan hominins. Finally, these data show how use-wear analysis, combined with lithic raw material and lithic technology, can be a powerful means for evaluating two key points for human evolution: long-term memory, and planning.

Oldowan sites in primary geologic context are rare in the archaeological record. Here we describe the depositional environment of Oldowan occurrences at Kanjera South, Kenya, based on field descriptions and granulometric analysis. Excavations there have recovered a large Oldowan artefact sample as well as the oldest substantial sample of archaeological fauna. The deposits at Kanjera South consist of 30 m of fluvial, colluvial, and lacustrine sediments. Magneto- and bio-stratigraphy indicate the Kanjera South Member of the Kanjera Formation was deposited between 2.3 and 1.92 million years ago (Ma), with 2.0 Ma being a likely age for the archaeological occurrences. Oldowan artefacts and associated fauna were deposited in the colluvial and alluvial silts and sands of Beds KS-1 to KS-3, in the margins of a lake basin. Field descriptions and granulometric analysis of the sediment fine fraction indicates sediments from within the main archaeological horizon were emplaced as a combination of tractional and hyperconcentrated flows with limited evidence of debris flow deposition. This style of deposition is unlikely to significantly erode or disturb the underlying surface and therefore promotes preservation of surface archaeological accumulations. Hominins were repeatedly attracted to the site locale, and rapid sedimentation, minimal bone weathering, and an absence of bone or artefact rounding further indicate that fossils and artefacts were quickly buried.

The current study describes a new method of mandibular ecological morphology (ecomorphology). Three-dimensional geometric morphometrics (3D GM) was used to quantify mandibular shape variation between extant bovids with different feeding preferences. Landmark data were subjected to generalized Procrustes analysis (GPA), principal components analysis (PCA), and discriminant function analysis (DFA). The PCA resulted in a continuum from grazers to browsers along PC1 and DFA classified 88% or more of the modern specimens to the correct feeding category. The protocol was reduced to a subset of landmarks on the mandibular corpus in order to make it applicable to incomplete fossils. The reduced landmark set resulted in greater overlap between feeding categories but maintained the same continuum as the complete landmark model. The DFA resubstitution and jackknife analyses resulted in classification success rates of 85% and 80%, respectively. The reduced landmark model was applied to fossil mandibles from the Upper Laetolil Beds (similar to 4.3-3.5 Ma) and Upper Ndolanya Beds (similar to 2.7-2.6 Ma) at Laetoli, Tanzania in order to assess antelope diet, and indirectly evaluate paleo-vegetation structure. The majority of the fossils were classified by the DFA as browsers or mixed feeders preferring browse. Our results indicate a continuous presence of wooded habitats and are congruent with recent environmental studies at Laetoli indicating a mosaic woodland-bushland-grassland savanna ecosystem. (C) 2017 Elsevier Ltd. All rights reserved.