Many questions about these ancient interactions remain, such as where and when did ancient populations connect, what social exchanges took place and what mechanisms provoked their eventual isolation.īeginning in Marine Isotope Stage 3 (approximately 57 ka), African populations underwent substantial social reorganization 9, 10, 11. Although ancient DNA is a powerful tool for acquiring information about biological exchange, it is unable to address the cultural context of ancient interactions. Research into these shifting connections is increasingly derived from DNA and ancient DNA analyses, which reveal that present-day African hunter–gatherer populations diverged into regional lineages sometime in the Pleistocene, including a deep division between southern and eastern groups approximately 350–70 ka 3, 4, 8. The metapopulation model suggests that anatomical modernity and behavioural complexity arose within a pan-African patchwork of populations who experienced pulses of connection and isolation 6, possibly in response to environmental circumstances 1, 7. Unresolved questions in human evolution concern the ancient distribution and diversification of our species ( Homo sapiens) across Africa 2, 5. Our study implies a later regional divergence than predicted by genetic analyses, identifies an approximately 3,000-kilometre stylistic connection and offers important new insights into the social dimension of ancient interactions. This suggests that climate exerted some influence in shaping human social contact.
The timing of this disconnection broadly corresponds with the southward shift of the Intertropical Convergence Zone, which caused periodic flooding of the Zambezi River catchment (an area that connects eastern and southern Africa). This connection breaks down approximately 33 ka, with populations remaining isolated until herders entered southern Africa after 2 ka.
We found that ostrich eggshell bead technology probably originated in eastern Africa and spread southward approximately 50–33 ka via a regional network. Here we compare ostrich eggshell bead variations between eastern and southern Africa to explore population dynamics over the past 50,000 years. Genetic analyses reveal that eastern and southern African lineages diverged sometime in the Pleistocene epoch, approximately 350–70 thousand years ago (ka) 3, 4 however, little is known about the exact timing of these interactions, the cultural context of these exchanges or the mechanisms that drove their separation. Humans evolved in a patchwork of semi-connected populations across Africa 1, 2 understanding when and how these groups connected is critical to interpreting our present-day biological and cultural diversity.
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