Wednesday, October 22, 2014
Ust'-Ishim belongs to K-M526
Not long ago I predicted that Ust'-Ishim belonged to a basal form of Y-chromosome haplogroup P (see here). As it turns out, the 45,000 year-old western Siberian genome belongs to K(xLT) or K-M526, which is actually pretty close to my guess. The Ust'-Ishim paper was published today and is behind a paywall here, but the extensive supp info is free.
Here's a map to help visualize the information, featuring Ust'-Ishim as well as Mal'ta boy, another North Eurasian Upper Paleolithic genome published recently.
The Ust'-Ishim genome was sequenced from the fossil of a femur bone found on the right bank of the Irtysh River. This area is very close to the Urals, and almost in the middle of the former Mammoth steppe that once stretched across North Eurasia from Iberia to Alaska. Interestingly, M526 is an ancestral mutation to the markers that define Y-chromosome haplogroups N, Q and R, which possibly dominated North Eurasia since the Upper Paleolithic (note that the 24,000 year-old Mal'ta boy belongs to a basal form of R).
Moreover, R1a and R1b are the most frequent haplogroups in Europe today. Thus, it would seem that most European males derive their paternal ancestry from North Eurasian hunter-gatherers whose ancestors spread out across Eurasia from the Middle East over 45,000 years ago.
I know that a lot of people have been arguing recently that K-M526 and the derived P-M45 originated and diversified in Southeast Asia, and then migrated north well within the last 45,000 years (for instance, see here). However, considering that K-M526 was already in reindeer country 45,000 years ago, as well as the Denisovan (ancient Siberian hominin) admixture among Southeast Asians, that might well turn out to be the equivalent of arguing that up is down and down is up.
By the way, Ust'-Ishim also belongs to pan-Eurasian mitochondrial (mtDNA) haplogroup R*, and in terms of genome-wide genetic structure appears roughly intermediate between West and East Eurasians. These outcomes fit very nicely with its Y-haplogroup.
However, it's slightly closer to Mesolithic Iberian genome La Brana-1, Upper Paleolithic Siberian MA-1 (or Mal'ta boy), and present-day East Asians, than to present-day West Eurasians, including Europeans. That's because it lacks "ancestry from a population that did not participate in the initial dispersals of modern humans into Europe and Asia". This is obviously the so called Basal Eurasian admixture discussed in Lazaridis et al. (see here), which is probably associated with early Neolithic farmers.
Also worth mentioning is that Ust'-Ishim harbors longer stretches of Neanderthal chromosomal segments than present-day Eurasians, which suggests that admixture between modern humans and Neanderthals took place in the Middle East not long before the ancestors of Ust-Ishim moved into Siberia (50-60,000 years ago). But this was already covered months ago, and you'll find lots of links on the topic on Google.
Qiaomei Fu et al., Genome sequence of a 45,000-year-old modern human from western Siberia, Nature 514, 445–449 (23 October 2014) doi:10.1038/nature13810