Substack cometh, and lo it is good. (Pricing)

Durc’s great-grandson

The_Clan_of_the_Cave_Bear_coverBy now you have heard of the recent ancient DNA finding dating from ~40,000 years ago in Southeastern Europe. The individual is a representative of one of the first anatomically modern groups to arrive in Europe…sort of. It exhibits robust characteristics, and may have had some admixture from Neandertals. Now, thanks to ancient DNA, that’s confirmed:

Qiaomei Fu, a palaeogenomicist at Harvard Medical School in Boston, Massachusetts, told the meeting how she and her colleagues had sequenced DNA from a 40,000-year-old jawbone that represents some of the earliest modern-human remains in Europe. They estimate that 5–11% of the bone’s genome is Neanderthal, including large chunks of several chromosomes. (The genetic analysis also shows that the individual was a man). By analysing how lengths of DNA inherited from any one ancestor shorten with each generation, the team estimated that the man had a Neanderthal ancestor in the previous 4–6 generations. (The researchers declined to comment on the work because it has not yet been published in a journal).

Two major points. First, the admixture fraction is way higher than any modern population. This isn’t a fluke. Second, they must be seeing ancestry tract lengths to make this inference. Basically the Neandertal ancestry blocks have been chopped up, but only a finite number of times. This really one-ups talk of “Cherokee great-grandmothers”, that’s for sure.

So what about the earlier results that most of the admixture must have happened in the Middle East? There have been revisions to this model, with many researchers now suggesting that a second pulse might have occurred in eastern Eurasia. But, another possibility is that very little of the ancestry of the first modern Europeans remains in modern Europeans. That is, the later Paleolithic populations of Europe may have replaced the first settlers, just as they in their turn were replaced or assimilated. The landscape of Mesolithic/Neolithic Europe seems demographically complex, so I see no reason not to suspect that the same was the case for the period before the Last Glacial Maximum. There may have been several admixture events with Neandertals, but the “outriders” may have been left no traces in the modern human lineages. It may be that the human “phylogenetic bush” has been extremely pruned many times over, so that most “fossil ancestors” are simply dead ends.

Addendum: As usual, great piece in Nature too.

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