May 03, 2015

Southern origins and recent admixture of Siberian populations

bioRxiv http://dx.doi.org/10.1101/018770

The complex admixture history and recent southern origins of Siberian populations

Irina Pugach , Rostislav Matveev , Viktor Spitsyn , Sergey Makarov , Innokentiy Novgorodov , Vladimir Osakovsky , Mark Stoneking , Brigitte Pakendorf

Although Siberia was inhabited by modern humans at an early stage, there is still debate over whether this area remained habitable during the extremely cold period of the Last Glacial Maximum or whether it was subsequently repopulated by peoples with a recent shared ancestry. Previous studies of the genetic history of Siberian populations were hampered by the extensive admixture that appears to have taken place among these populations, since commonly used methods assume a tree-like population history and at most single admixture events. We therefore developed a new method based on the covariance of ancestry components, which we validated with simulated data, in order to investigate this potentially complex admixture history and to distinguish the effects of shared ancestry from prehistoric migrations and contact. We furthermore adapted a previously devised method of admixture dating for use with multiple events of gene flow, and applied these methods to whole-genome genotype data from over 500 individuals belonging to 20 different Siberian ethnolinguistic groups. The results of these analyses indicate that there have indeed been multiple layers of admixture detectable in most of the Siberian populations, with considerable differences in the admixture histories of individual populations, and with the earliest events dated to not more than 4500 years ago. Furthermore, most of the populations of Siberia included here, even those settled far to the north, can be shown to have a southern origin. These results provide support for a recent population replacement in this region, with the northward expansions of different populations possibly being driven partly by the advent of pastoralism, especially reindeer domestication. These newly developed methods to analyse multiple admixture events should aid in the investigation of similarly complex population histories elsewhere.

Link

6 comments:

John Rudmin said...

"...there is still debate over whether this area remained habitable during the extremely cold period of the Last Glacial Maximum.."

I would think M'alta (did i put the ' in the right place?)would prove that...

terryt said...

But Mal'ta's (I'm pretty sure that's where the apostrophe goes) Y-DNA died out even though it is a branch of R evidently. I have not found any reliable information as to his mt-DNA. As a result we can fairly definitely say that although Siberia was habitable at 25,000 years ago there may have been a later period where the inhabitable region had shrunk greatly. I tend to think that there have been a series of pulses of human expansion into Central Eurasia followed by drastic reduction in geographical range, probably with isolated populations surviving in restricted regions only to expand once more as conditions ameliorated.

terryt said...

I've just checked and see MA-! is mt-DNA U but not narrowed down more than that.

terryt said...

"The results of these analyses indicate that there have indeed been multiple layers of admixture detectable in most of the Siberian populations"

Not only in Siberia apparently. Our evolution just got more complicated. Check this out:

http://linearpopulationmodel.blogspot.co.nz/2015/05/team-characterizing-dna-from-ancient.html

Quote:

"genetic patterns in the ancient human hint at the potential of admixture between modern humans and Neanderthals in Europe that may have persisted until not long before Neanderthals disappeared from the continent some 40,000 years ago".

And:

"comparisons between genetic variants in Oase 1 and those in present-day populations or previously sequenced ancient samples suggested that the ancient individual from Romania belonged to a population that was becoming somewhat European".

And finally:

""does not appear to have contributed much genetically to present-day human populations".

In other words the replacement of Neanderthals was no sudden process but went on for a very long time. However the first hybrids to form in Europe were eventually replaced by hybrid populations who had formed much earlier.

Gary Moore said...

Somewhat disappointed they did not discuss the Kets much or the Trans-Baikal Hiatus and the disappearance of the Kitoi Culture. Edward Vajda suggested that much of Siberia had been inhabited by populations with an affinity to Native Americans who were subsequenty replaced by Turkic and Tungusic-speaking herders.

terryt said...

Further to my comment:

"I tend to think that there have been a series of pulses of human expansion into Central Eurasia followed by drastic reduction in geographical range, probably with isolated populations surviving in restricted regions only to expand once more as conditions ameliorated".

Razib thinks the same way:

http://www.unz.com/gnxp/the-cro-magnons-have-no-descendants-in-europe-today/

Quote:

"With low population densities and a fragmented Pleistocene landscape it strikes me as plausible that Palearctic mammals in particular may be characterized by repeated resettlement of the frontier of the range from core source populations after local extinctions and retrenchments".

Of course humans are 'Palearctic mammals'.