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Tectonically driven physiographic evolution in early Miocene of eastern Africa significantly shaped landscapes, climates, and vegetation, resulting in habitat heterogeneity. Early hominoids inhabited these landscapes, and their evolutionary history was likely influenced by these heterogenous environments. In western Kenya, around the extinct Tinderet Volcano (ca. 19-21Ma), fossil-rich exposures offer crucial insights into this history with evidence of early hominoids. Here we use analyses of sedimentology, paleosol paleoclimate proxies, fossil leaves, and forestry metrics, to reconstruct the paleoclimate and paleoecological reconstruction of the Koru-16 fossil site. Sedimentological and stratigraphic analyses at Koru-16 reveal a landscape marked disturbance created by periodic volcanic eruptions and stable intervals marked by moderately to poorly developed paleosols. Paleoclimate reconstructions based on paleosol geochemistry indicates warm and wet conditions. Over 1000 fossil leaves were collected from the Koru-16 site, representing 17 morphotypes across two stratigraphic intervals. Mean annual precipitation estimates based on leaf size of shape indicate >2000mm/yr. Leaf lifespan reconstructions reveal predominantly evergreen taxa with a distribution leaf lifespan, similar to modern equatorial African rainforests. Fossil tree stump casts suggest an open forest, similar to contemporary tropical forests supporting large-bodied primates. Importantly, fossil leaves, the tree stump casts, a medium-sized pythonid, and multiple specimens of large-bodied primates occur in the same stratigraphic layer demonstrating their cooccurrence in the Koru-16 ecosystem. The multi-proxy paleoclimate and paleoecological reconstructions for Koru-16 converge on a very wet and warm climate supporting a closed, tropical seasonal forest to rainforest biome. This environment likely provided an ideal habitat for early hominoids, emphasizing the role of forested habitats in their early Miocene evolution. Additional work is ongoing on refining the paleosol paleoclimate estimates with a more recent model and δ13C analysis of soil organic matter will help to further refine these reconstructions. 

The first fossil apes published from Africa were discovered in the 1920s at the Tinderet site of Koru, Kenya. Since that time, the entire Tinderet fossil complex has produced thousands of fossil mammals, reptiles, and plants, including some of the most important early ape and stem catarrhine specimens. Here, we report results from geological, paleoecological, and paleontological surveys and samples conducted by our team between 2013-2023. A major part of our work has been to rediscover old but sometimes poorly documented fossil sites and to assess their potential for future research. One such site, Tonde Bridge, was thought to have no remaining fossil deposits but we report here the discovery of many new specimens. We have also discovered new fossil sites that may sample poorly known depositional and/or ecological settings. Our stratigraphic and geochronological results help to better ordinate major fossil outcrops with respect to each other. We have also specifically targeted the smallest microfauna as well as understudied taxonomic groups such as reptiles and amphibians. This work combined with other paleoecological analyses confirm closed habitats at many of the Tinderet sites. One site in particular has benefitted from extensive multi-proxy paleoecological reconstruction, allowing us to place some fossil apes within a dense forested environment. Finally, the discovery of important new primate specimens helps clarify some of the anatomical variation represented in historic collections but also extends the taxonomic variation from Tinderet. In particular, the discovery of a large-bodied nyanzapithecine from Koru suggests that size variation in this clade may have been similar to that found in proconsulids. 

Eastern African terrestrial ecosystems in the Early Miocene are characterized by habitat heterogeneity resulting from local rifting, climate variation, and biogeography. These dynamic landscapes profoundly influenced the evolutionary trajectories of hominoids and other mammals. In western Kenya, a collection of Early Miocene fossil-rich sites (ca. 20 Ma) proximate to the extinct Tinderet Volcano, offers a unique window into understanding habitat preferences and ecological drivers to the evolution of hominoids. Here, we present data from one of the sites, Koru 16, with evidence of remarkably preserved fossil fauna, fossil leaves, tree stump casts, and paleosols, to provide invaluable insights into the ancient ecological dynamics of the region. We use multiple proxies to reconstruct the paleoclimate and paleoecology of the Koru 16 site. The lithofacies of the Koru 16 area are characterized as interbedded ash and weakly developed paleosols indicating episodic landscape disturbance from eruptions of the volcano followed by intervals of stability. Paleosol features together with paleoclimate estimates using two models based on elemental weathering (RF-MAP and PPM) indicate warm and wet conditions. More than 1000 fossil leaves collected from two stratigraphic locations at Koru 16 yielded seventeen morphotypes which were identified across both localities and displaying different distributions of morphotypes between them. The average leaf size of morphotypes form both localities is mesophyll to megaphyll and mean annual precipitation estimates using multiple leaf physiognomic methods indicate >2000 mm/yr. Leaf lifespan estimates derived from the leaf mass per area (MA) proxy suggest that the site was predominantly characterized by evergreen taxa, with limited deciduous taxa. The distribution of MA is consistent with tropical rainforests and tropical seasonal forests in equatorial Africa, indicating similarities in leaf characteristics and ecological patterns. Tree stump casts corroborate this observation, as they indicate an open forest, with density similar to modern tropical forests that support large-bodied primates. The fauna includes a medium- sized pythonid, and at least two species of apes, along with other mammalian taxa typical for the early Miocene. Our comprehensive paleoclimate and paleoecological analyses suggest that the Koru 16 site was very warm and wet, which is a climate conducive for a tropical seasonal forest transitioning into a rainforest biome. This environmental reconstruction underscores the broad distribution of Early Miocene apes in a variety of habitats, and calls into question a recent hypothesis that apes only lived in environments with a significant open component. 

Hominoids exhibited high diversity in the early Neogene. The Early Miocene, in particular, is the inferred timing of the origin of the crown Hominoidea. Thus, understanding the paleoecology and paleoenvironments of the Early Miocene is critical for understanding the selective pressures that led to the evolution and diversification of hominoids. The Early Miocene fossil sites of Koru, Legetet, and Chamtwara occur on the southwestern flank of the now-extinct Tinderet volcano in western Kenya. While not as well- known as the Songhor site on the northwestern flank of the same volcano, the Chamtwara, Legetet, and Koru sites surrounding the village of Koru document surprising taxonomic diversity of Early Miocene hominoids; yet relatively little paleoenvironmental work has been conducted to contextualize this taxonomic diversity. Our recent geological, paleontological, and paleoenvironmental work has focused on reconstructing the paleoclimate and paleoecology of these fossil sites using a variety of proxies. Sedimentological analyses of the fossil sites indicate periodic disturbance of the landscape due to volcanic activity and that most of the fossiliferous strata are moderately to poorly developed paleosols and fluvial channels. Paleosol features are nearly identical across sites and demonstrate relatively wet and well-drained conditions with some evidence of seasonality and/or periodic water deficit. Paleosol based proxies for paleoclimate indicate wet conditions with mean annual precipitation greater than 175 cm/year. Paleobotanical proxies from fossil leaves and fossil tree stump casts indicate a warm and very wet climate indicating a tropical seasonal forest to tropical rainforest biome. Paleoclimate estimates based on habitats of extant relatives and vertebral ecomorphology of fossil snakes similarly indicate very warm and wet conditions consistent with tropical rainforests. Faunal analyses of the mammal community composition and dietary ecology also indicate forested environments. Taken together, our multi-proxy reconstructions of paleoclimate and paleoenvironment indicate that the Chamtwara, Legetet, and Koru sites were warm and very wet forested habitats connecting early hominoids to closed habitats. 

Tectonically driven physiographic evolution has profound effects on the climate and vegetation of Early Miocene terrestrial ecosystems across eastern Africa, creating habitat heterogeneity. Early hominoids were present on these dynamic landscapes, which likely influenced their evolutionary history. In western Kenya, a series of Early Miocene (ca.19-21Ma) fossiliferous exposures around the now-extinct Tinderet volcano document this history through preservation of hominoid fossils, fossil leaves, tree stump casts, and paleosols. Here, we use multiple proxies to reconstruct the paleoclimate and paleoecology of the fossil site Koru-16. Sedimentological and stratigraphic analysis indicate the landscape was disturbed by periodic eruptions of the volcano followed by intervals of stability, as shown by features of moderate to poorly developed paleosols. Paleoclimate estimates using the paleosol-paleoclimate model (PPM) indicate warm and wet climate conditions. Over 1000 fossil leaves were collected from two stratigraphic intervals. Seventeen morphotypes were identified across both sites, with an unequal distribution of morphotypes. Average leaf size estimate is mesophyll to megaphyll, with mean annual precipitation estimates using leaf physiognomic methods indicate >2000mm/yr. Leaf lifespan reconstructions based on leaf mass per area (MA) proxy indicate the site was predominately evergreen, with few deciduous taxa, with a MA distribution like modern tropical rainforests and tropical seasonal forests in equatorial Africa. Forest density estimates based on fossil tree stump casts indicate an open forest, with density similar to modern tropical forests that support large-bodied primates. Importantly, fossil leaves, tree stump casts, a medium-sized pythonid, a large-bodied hominoid and Proconsul africanus are all found within the same strata, indicating that these early apes lived within the reconstructed Koru-16 ecosystem. Our multi-proxy paleoclimate and paleoecological reconstructions indicate Koru-16 site sampled a very wet and warm climate that supported a tropical seasonal forest to rainforest biome. This likely provided an ideal habitat for hominoids and suggests that forested habitats played a role in the evolution of Early Miocene hominoids. 

INTRODUCTION Inherent in traditional views of ape origins is the idea that, like living apes, early large-bodied apes lived in tropical forests. In response to constraints related to locomoting in forest canopies, it has been proposed that early apes evolved their quintessential upright torsos and acrobatic climbing and suspensory abilities, enhancing their locomotor versatility, to distribute their weight among small supports and thus reach ripe fruit in the terminal branches. This feeding and locomotor transition from a quadruped with a horizontal torso is thought to have occurred in the Middle Miocene due to an increasingly seasonal climate and feeding competition from evolving monkeys. Although ecological and behavioral comparisons among living apes and monkeys provide evidence for versions of terminal branch forest frugivory hypotheses, corroboration from the early ape fossil record has been lacking, as have detailed reconstructions of the habitats where the first apes evolved. RATIONALE The Early Miocene fossil site of Moroto II in Uganda provides a unique opportunity to test the predictions of terminal branch forest frugivory hypotheses. Moroto II documents the oldest [21 million years ago (Ma)] well-established paleontological record of ape teeth and postcranial bones from a single locality and preserves paleoecological proxies to reconstruct the environment. The following lines of evidence from Moroto II were analyzed: (i) the functional anatomy of femora and a vertebra attributed to the ape Morotopithecus ; (ii) dental traits, including molar shape and isotopic profiles of Morotopithecus enamel; (iii) isotopic dietary paleoecology of associated fossil mammals; (iv) biogeochemical signals from paleosols (ancient soils) that reflect local relative proportions of C 3 (trees and shrubs) and C 4 (tropical grasses and sedges that can endure water stress) vegetation as well as rainfall; and (v) assemblages of phytoliths, microscopic plant-derived silica bodies that reflect past plant communities. RESULTS A short, strong femur biomechanically favorable to vertical climbing and a vertebra indicating a dorsostable lower back confirm that ape fossils from Moroto II shared locomotor traits with living apes. Both Morotopithecus and a smaller ape from the site have elongated molars with well-developed crests for shearing leaves. Carbon isotopic signatures of the enamel of these apes and of other fossil mammals indicate that some mammals consistently fed on water-stressed C 3  plants, and possibly also C 4  vegetation, in a woodland setting. Carbon isotope values of pedogenic carbonates, paleosol organic matter, and plant waxes all point to substantial C 4 grass biomass on the landscape. Analysis of paleosols also indicates subhumid, strongly seasonal rainfall, and phytolith assemblages include forms from both arid-adapted C 4 grasses and forest-indicator plants. CONCLUSION The ancient co-occurrence of dental specializations for leaf eating, rather than ripe fruit consumption, along with ape-like locomotor abilities counters the predictions of the terminal branch forest frugivory hypotheses. The combined paleoecological evidence situates Morotopithecus in a woodland with a broken canopy and substantial grass understory including C 4 species. These findings call for a new paradigm for the evolutionary origins of early apes. We propose that seasonal, wooded environments may have exerted previously unrecognized selective pressures in the evolution of arboreal apes. For example, some apes may have needed to access leaves in the higher canopy in times of low fruit availability and to be adept at ascending and descending from trees that lacked a continuous canopy. Hominoid habitat comparisons. Shown are reconstructions of a traditionally conceived hominoid habitat ( A ) and the 21 Ma Moroto II, Uganda, habitat ( B ). 

ABSTRACT ObjectivesIn subsistence populations, high physical activity is typically maintained throughout pregnancy. Market integration shifts activity patterns to resemble industrialized populations, with more time allocated to sedentary behavior. Daasanach semi‐nomadic pastoralists living in northern Kenya face lifestyle heterogeneity due to the emergence of a market center. We investigate how Daasanach women manage the energetic demands of pregnancy with subsistence labor tasks and how market integration relates to variation in energetic demands, physical activity, and coping strategies. MethodsWe conducted nine focus group discussions with 72 pregnant women. We also deployed wrist‐worn fitness trackers with 21 pregnant women in two community types: central or peripheral to the market center to capture variation in market integration. Data from focus group discussions were analyzed using thematic analysis. We used multiple linear regression to examine the relationship between gestational age and physical activity. ResultsWe identified themes of increased fatigue, diet restrictions, and assistance with labor tasks during pregnancy. Gestational age negatively predicted mean daily steps, with a decrease of 1160 ± 437 steps per day with each consecutive pregnancy month. Stratified by community type, gestational age only negatively predicted mean daily steps for peripheral communities, with a decrease of 1443 ± 629 steps per day with each consecutive pregnancy month. ConclusionsResults suggest that physical activity differs with market integration early, but not late, in pregnancy. Daasanach women cope with the energetic demands of pregnancy by reducing physical activity late in pregnancy and receiving assistance with labor tasks from family and neighbors. 

The assembly of Africa’s iconic C₄grassland ecosystems is central to evolutionary interpretations of many mammal lineages, including hominins. C₄grasses are thought to have become ecologically dominant in Africa only after 10 million years ago (Ma). However, paleobotanical records older than 10 Ma are sparse, limiting assessment of the timing and nature of C₄biomass expansion. This study uses a multiproxy design to document vegetation structure from nine Early Miocene mammal site complexes across eastern Africa. Results demonstrate that between ~21 and 16 Ma, C₄grasses were locally abundant, contributing to heterogeneous habitats ranging from forests to wooded grasslands. These data push back the oldest evidence of C₄grass–dominated habitats in Africa—and globally—by more than 10 million years, calling for revised paleoecological interpretations of mammalian evolution. 

This paper evaluates risk-oriented frameworks for explaining environmental, social, and economic changes faced by fishing and herding communities in the Turkana Basin during and after the African Humid Period (AHP, 15–5 ka). The orbitally-forced AHP created moist conditions, high lake levels, and unusual hydrological connections across much of northern and eastern Africa. As arid conditions set in and rainfall decreased between 5.3 and 3.9 ka in eastern Africa, Lake Turkana (NW Kenya) shrank dramatically. Shoreline retreat coincided with an expansion of open plains, creating new ecological conditions and potential opportunities for early herders in the basin. In this changing landscape, economies shifted from food procurement (fishing/hunting aquatic resources) to food production (herding), likely through both in-migration by pastoralists and adoption of herding by local fishers. Early pastoralists also built at least seven megalithic pillar sites that served as communal cemeteries during this time. Recent research has shown that local environmental dynamics – both during and after the AHP – were complex, demanding a more careful interrogation of the notion that post-AHP life entailed new and/or heightened risks. Risk-buffering strategies might include mobility, diversification, physical storage, and exchange. Archaeologists working around Lake Turkana have proposed that economic shifts from fishing to pastoralism entailed increased mobility as a risk-buffering strategy to deal with aridity and resource unpredictability, and that pillar sites – as fixed landmarks in an unstable landscape – provided settings for congregation and exchange amongst increasingly mobile herding communities. However, recent research has shown that local environmental dynamics in the Lake Turkana basin – both during and after the AHP – were more complex than previously thought, necessitating re-evaluation of the notion that post-AHP life entailed new and/or heightened risks. Here, we explore risk buffering strategies (e.g. mobility, diversification, physical storage and/or exchange) as only one category of potential explanation for the new social practices observed in the region at this time. Gauging their applicability requires us to (a) assess the spatial mobility of communities and individuals interred at pillar sites; (b) evaluate whether and how mobility strategies may have changed as pastoralism supplanted fishing; and (c) examine alternative explanations for social and economic changes.