There’s a new report out in Nature, on the DNA results from a 45,000 AMH skeleton found in Western Siberia. It’s the oldest radiocarbon-dated modern human outside Africa and the Middle East.
The Neanderthal admixture is there, about the same amount as today, but in larger blocks than in people today. Less shuffled, so we now have a better estimate on the admixture date: 50-60,000 years ago. The skeleton confirms the new lower estimate of the human mutation rate, about 1.2 x 10-8 per generation. He’s equally related to Andaman islanders, Amerindians, Han Chinese, that Mal’ta Siberian ANE boy, and Old European hunter-gatherers (La Brana), but somewhat more distant from modern Europeans (French and Sardinians), because of this basal Eurasian component from the Middle East (found in the EEF, the original farmers of Europe). These Basal Eurasians would have had to split from the AMH population that did the main expansion out of Africa before they left, so the split must have been well over 60,000 years ago. That doesn’t tell us exactly when the Basal Eurasians left Africa, however. Could have been as long ago as the Shkul and Qafzeh skulls, roughly 100,000 years ago, could actually have been far more recent.
We know that there was an expansion of modern humans into the Middle East ~100,000 years ago – so the simplest explanation is that the Basal Eurasians are descended from that early expansion. Otherwise we have to posit three different expansions of modern humans out of Africa, one of which failed after a while. If they left that early, looks as if the Basal Eurasians didn’t sufficient moxie to displace archaic humans over most of Eurasia (while the later dispersal did) . On the other hand, they do seem to have invented agriculture.
Finding a decent-quality ancient sample that is a good representative of those Basal Eurasians, as the Mal’ta boy is of the ancient Siberians, would sure help clarify things.
Chris Stringer is quoted as saying that the study offers compelling evidence that living non-Africans descend from a group that left Africa about 60,000 years ago – but in fact it strengthens the case that there were in actuality at least two different successful expansions of anatomically modern humans out of Africa.