Eggshell beads exchanged over 30,000 years ago

Lesotho is roughly at the center of a bullseye-shaped geologic formation called the Karoo Supergroup. The supergroup’s mountainous center is basalt, from relatively recent volcanic eruptions that formed the highlands of Lesotho. Encircling Lesotho are bands of much older sedimentary rocks. The outermost ring of the formation ranges between 325 and 1,000 kilometers away from the Lesotho sites.

I bet they were sharing genes too, not just egg shells.

I thought I’d comment on this thread.

An article on this paper Ostrich eggshell beads reveal 50,000-year-old social network in Africa | Nature came up in my news feed. It made me smile since ratites keep fascinating me as there are little quirks about them genetically or culturally that just don’t fit the evolutionary timeline as well as other aspects of science. This is not an exception. I searched the forum to remind myself of previous discussions and this post came up.

The expectation is that large cultural exchanges should result in significant gene sharing, right? But it isn’t the case (lineages diverged well before populations were isolated). The expectation is wrong or something is very wrong about the mainstream genetic timeline. I’m going with the latter. Or am I missing something?

Abstract:

Humans evolved in a patchwork of semi-connected populations across Africa1,2; understanding when and how these groups connected is critical to interpreting our present-day biological and cultural diversity. 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. Here we compare ostrich eggshell bead variations between eastern and southern Africa to explore population dynamics over the past 50,000 years. We found that ostrich eggshell bead technology probably originated in eastern Africa and spread southward approximately 50–33 ka via a regional network. This connection breaks down approximately 33 ka, with populations remaining isolated until herders entered southern Africa after 2 ka. 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 suggests that climate exerted some influence in shaping human social contact. 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.

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