Did Our Species Evolve in Subdivided Populations across Africa, and Why Does It Matter? (original) (raw)
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We challenge the view that our species, Homo sapiens, evolved within a single population and/or region of Africa. The chronology and physical diversity of Pleistocene human fossils suggest that morphologically varied populations pertaining to the H. sapiens clade lived throughout Africa. Similarly, the African archaeological record demonstrates the polycentric origin and persistence of regionally distinct Pleistocene material culture in a variety of paleoecological settings. Genetic studies also indicate that present-day population structure within Africa extends to deep times, paralleling a paleoenvironmental record of shifting and fractured habitable zones. We argue that these fields support an emerging view of a highly structured African prehistory that should be considered in human evolutionary inferences, prompting new interpretations, questions , and interdisciplinary research directions.
Human Origins, Dispersal And Associated Environments: An African Perspective
Encyclopedia of Life Support System, 2015
Africa’s position as the cradle of humanity is widely accepted, supported by rich fossil and archaeological discoveries from different parts of the continent. Drawing on the Out-of-Africa theory of human origins, this article provides a condensed narrative of the major milestones in human evolution and associated environmental settings. The underlying hypothesis is that changes in global climate played an important role in fueling early modern human origins and dispersals within and outside of Africa. As one will discover in this article, the history of humanity is a tale of small events that merged together into major milestones over a long span of time. There is an emerging consensus among scholars that the onset of variable global climate throughout the last 6 million years, particularly the repeated glacial and interglacial cycles in the last 2.5 million years, drove the evolution of the biological and behavioral traits that define the human lineage. As with our past, the futurity of humanity will likely hinge on future climate patterns.
Rethinking the dispersal of Homo sapiens out of Africa
Ash Parton, Matthew Meredith-Williams, Laura Lewis, James Blinkhorn, Geoff Bailey, Michael Petraglia, Huw Groucutt, Eleanor Scerri, Nicholas Drake, Paul S Breeze, Mark Thomas
Current fossil, genetic, and archeological data indicate that Homo sapiens originated in Africa in the late Middle Pleistocene. By the end of the Late Pleistocene, our species was distributed across every continent except Antarctica, setting the foundations for the subsequent demographic and cultural changes of the Holocene. The intervening processes remain intensely debated and a key theme in hominin evolutionary studies. We review archeological, fossil, environmental, and genetic data to evaluate the current state of knowledge on the dispersal of Homo sapiens out of Africa. The emerging picture of the dispersal process suggests dynamic behavioral variability, complex interactions between populations, and an intricate genetic and cultural legacy. This evolutionary and historical complexity challenges simple narratives and suggests that hybrid models and the testing of explicit hypotheses are required to understand the expansion of Homo sapiens into Eurasia.
Clarifying distinct models of modern human origins in Africa
Accumulating genomic, fossil and archaeological data from Africa have led to a renewed interest in models of modern human origins. However, such discussions are often discipline- specific, with limited integration of evidence across the different fields. Further, geneticists typically require explicit specification of parameters to test competing demographic models, but these have been poorly outlined for some scenarios. Here, we describe four possible models for the origins of Homo sapiens in Africa based on published literature from paleoanthropology and human genetics. We briefly outline expectations for data patterns under each model, with a special focus on genetic data. Additionally, we present schematics for each model, doing our best to qualitatively describe demographic histories for which genetic parameters can be specifically attached. Finally, it is our hope that this perspective provides context for discussions of human origins in other manuscripts presented in this special issue.
Human Evolution in Late Quaternary Eastern Africa
Eastern Africa (broadly Ethiopia, Somalia, South Sudan, Kenya, Uganda, and Tanzania) has yielded the earliest fossils of modern humans, the earliest evidence for Mode 3 technologies (Middle Stone Age), and is one of the areas in which modern humans may well have been endemic. This paper reviews the genetic, archaeological, and fossil evidence for the evolution of modern humans across MIS 6-2 in eastern Africa, and places this into the context of Middle Pleistocene human evolution, the development of the Middle Stone Age across the continent, and climatic change over the last two glacial cycles. We argue that while there is a paucity of well-dated sites that reduces the resolution of any interpretation, the available evidence indicates a major role for eastern Africa as an area of endemism, most probably related to the interaction of mosaic environments and refugia. We show that the evolution of modern humans has roots that extend well before MIS 6, and propose four overlapping stages, making this a much more prolonged process than has traditionally been described. There is a broad relationship between evolutionary history and major climatic oscillations; nevertheless , a closer examination reveals a more complex pattern. There are periods of synchrony and asynchrony in both contextual and evolutionary/behavioral changes, and these show variable links to both northern and southern Africa. Although eastern, northern and southern Africa (with central and western being largely unknown) show similarities and ultimately the same evolutionary and behavioral outcome, they also exhibit independent trajectories that require further research to throw light on the processes involved.
Quaternary Science Reviews
Understanding the structure and variation of Homo sapiens populations in Africa is critical for interpreting multiproxy evidence of their subsequent dispersals into Eurasia. However, there is no consensus on early Homo sapiens demographic structure, or its effects on intra-African dispersals. Here, we show how a patchwork of ecological corridors and bottlenecks triggered a successive budding of populations across the Sahara. Using a temporally and spatially explicit palaeoenvironmental model, we found that the Sahara was not uniformly ameliorated between ~130-75 thousand years ago (ka), as has been stated. Model integration with multivariate analyses of corresponding stone tools then revealed several spatially defined technological clusters which correlated with distinct palaeobiomes. Similarities between technological clusters were such that they decreased with distance except where connected by palaeohydrological networks. These results indicate that populations at the Eurasian gateway were strongly structured, which has implications for refining the demographic parameters of dispersals out of Africa.