Twists in Out-of-Africa

Early modern human diversity suggests subdivided population structure and a complex out-of-Africa scenario:

The interpretation of genetic evidence regarding modern human origins depends, among other things, on assessments of the structure and the variation of ancient populations. Because we lack genetic data from the time when the first anatomically modern humans appeared, between 200,000 and 60,000 years ago, instead we exploit the phenotype of neurocranial geometry to compare the variation in early modern human fossils with that in other groups of fossil Homo and recent modern humans. Variation is assessed as the mean-squared Procrustes distance from the group average shape in a representation based on several hundred neurocranial landmarks and semilandmarks. We find that the early modern group has more shape variation than any other group in our sample, which covers 1.8 million years, and that they are morphologically similar to recent modern humans of diverse geographically dispersed populations but not to archaic groups. Of the currently competing models of modern human origins, some are inconsistent with these findings. Rather than a single out-of-Africa dispersal scenario, we suggest that early modern humans were already divided into different populations in Pleistocene Africa, after which there followed a complex migration pattern. Our conclusions bear implications for the inference of ancient human demography from genetic models and emphasize the importance of focusing research on those early modern humans, in particular, in Africa.

This sort of finding is not unheard of in genetics either. Possible Ancestral Structure in Human Populations. This is not to say that Multi-Regionalism is true, rather, the strong form Only-One-Band-Out-of-and-within-Africa once with total replacement of all other populations is not quite an absolute slam dunk.

Below is a 3-dimensional PC chart which illustrates the variation within their dataset compared to various populations. The two illustrations are simply two views of the same chart (i.e., front & back).

i-2b46743d65c403cec4761e012a62b03d-pcoutofafrica.png

More like this

"the phenotype of neurocranial geometry"

Can they tell if these early humans had sloping criminal foreheads? :^)

"Rather than a single out-of-Africa dispersal scenario, we suggest that early modern humans were already divided into different populations in Pleistocene Africa, after which there followed a complex migration pattern"

We already knew that - there's this from last year, which I might have found at GNXP come to think of it.

Still, it's nice to have further support for the hypothesis. Please tell me they have situated the skulls in specific millennia and places within the African continent; the spans we've gotten so far are too vague (between 150k-90kya in the article I linked; yikes!)

I'm also still waiting for the report as to whether humans left Africa before or after the Toba blast...