North and South America were first populated by three waves of migrants from Siberia rather than just a single migration, say researchers who have studied the whole genomes of Native Americans in South America and Canada.I have an informed hunch that this will not be the last paper in the Reconstructing... series.
The supplementary material (pdf) is open access, and lists the data used, some of which has been taken from the literature and some of which is new. There is apparently also a new ADMIXTUREGRAPH software used in a paper which seems to parallel a little the functionality of TreeMix. I don't see a download option for this software yet; perhaps Joe Pickrell who co-authored TreeMix and is now in Harvard may chime in about the differences/applicability of the two pieces of code.
UPDATE: And here is the press release:
Two striking exceptions to this simple dispersal were also discovered. First, Central American Chibchan-speakers have ancestry from both North and South America, reflecting back-migration from South America and mixture of two widely separated strands of Native ancestry. Second, the Naukan and coastal Chukchi from north-eastern Siberia carry 'First American' DNA. Thus, Eskimo-Aleut speakers migrated back to Asia, bringing Native American genes.Interestingly, I have detected some of this "Native American" component in the Chukchi as part of my world9 calculator.
UPDATE II: Of course, if you look at the map of the sampled populations, you'll notice one big hole: the USA. Petty identity politics contra science? Data on Native groups outside the US have been studied for years, and I doubt that the sky will fall over the heads of the new Canadian and South American groups that participated in this particular study. Hopefully, one day the big hole will be filled, although I'm not holding my breath of that happening anytime soon.
Nature (2012) doi:10.1038/nature11258
Reconstructing Native American population history
David Reich et al.
The peopling of the Americas has been the subject of extensive genetic, archaeological and linguistic research; however, central questions remain unresolved1, 2, 3, 4, 5. One contentious issue is whether the settlement occurred by means of a single6, 7, 8 migration or multiple streams of migration from Siberia9, 10, 11, 12, 13, 14, 15. The pattern of dispersals within the Americas is also poorly understood. To address these questions at a higher resolution than was previously possible, we assembled data from 52 Native American and 17 Siberian groups genotyped at 364,470 single nucleotide polymorphisms. Here we show that Native Americans descend from at least three streams of Asian gene flow. Most descend entirely from a single ancestral population that we call ‘First American’. However, speakers of Eskimo–Aleut languages from the Arctic inherit almost half their ancestry from a second stream of Asian gene flow, and the Na-Dene-speaking Chipewyan from Canada inherit roughly one-tenth of their ancestry from a third stream. We show that the initial peopling followed a southward expansion facilitated by the coast, with sequential population splits and little gene flow after divergence, especially in South America. A major exception is in Chibchan speakers on both sides of the Panama isthmus, who have ancestry from both North and South America.