[LINK] "The first, second, and third nations"

[rfmcdonald]

GNXP's Razib Khan has a post up exploring a paper which takes a look at the genetic backgrounds of different indigenous populations in the Americas. The paper confirms the hypothesis of linguist Joseph Greenberg that the indigenous languages of the Americas fall into three broad families--Eskimo-Aleut (Inuit), Na-Dene (Navajo, Dene, Chipeweyan), and Amerind (everyone else). It goes into further detail.

The Eskimo-Aleut turn out to be a 50:50 mix between an Amerind group, what they term First Americans, and an Asian lineage related to Siberians. This is not totally surprising, but it is good to get solid grounding. Additionally, they report evidence of back-migration to eastern Siberia. Again, not too surprising, but it is a neat confirmation of the reality that the separation between the Old and New World was illusory in some deep ways. The Na-Dene population here, the Chipewyan, are a different case. They are ~90% First American, but also ~10% something else. That something else is also more Asian, but not quite the same as the non-First American component of Eskimo-Aleuts. This population X is quite possibly the Old World source for the Na-Dene. As the authors apologetically note they didn’t have many other Na-Dene samples to explore this question in detail. But, there is one aspect which they explore a great bit in the supplements: some models suggest that the Paleo-Eskimo Saqqaq sample exhibits a mix with First Americans at 15%, and 85% with this Asian population. With these sample sizes the statistical significant doesn’t seem rock solid, but it’s obviously suggestive. If you don’t remember, the Saqqaq sample comes from a man who died ~4,000 years ago. He seems to have resembled modern day Siberians more than Eskimo-Aleut, or indigenous peoples to the south. These data imply that the dominant component of the Saqqaq’s ancestry may indeed have been the minor component in the Na-Dene! A final twist is that the First American ancestry of the Saqqaq and Chipewyan is somewhat different than the First American ancestry of the Eskimo-Aleut. This is important in establishing a distinct ethnogenesis of the various groups, and their relationships to each other (I take their assertion that the First American of the Eskimo-Aleut being more “derived” a hint to likely later ethnogesis of this group via admixture than the Na-Dene).

To me the above implies that the closeness of the Saqqaq to the Siberian groups may be an artifact of the fact that the Eskimo-Aleut are synthetic populations, with ~50% First American, while the Saqqaq were only ~15% First American. Some have expressed curiosity as to how Na-Dene languages spread if the Chipewyan are only ~10% Na-Dene, using a grossly simplistic equivalency between language and ethnicity, but it strikes me that over time admixture could slowly reduce the genetic difference between the Na-Dene and their Amerind neighbors. By analogy, the Hui Muslims of China seem about ~90% Han Chinese genetically, but this can be easily explained by a very moderate amount of intermarriage over the past ~1,000 years, when you consider how small the Hui populations is in relation to the Han. One thing to note is that the Saqqaq may have been the first humans to settle much of the northern fringe of North America, and the Saqqaq man who was sequenced was alive during the very early centuries of this culture. One can easily imagine a rapidly expanding population pushing into uninhabited lands admixing very little with natives who did not exist. In contrast their Na-Dene cousins to the south were pushing into settled territory, and so experienced much greater admixture.

On a big picture note this puts the lie to the idea that before agriculture hunter-gatherer societies were subject purely to differentiation in situ. The Eskimo-Aleut and Na-Dene erupted into a settled landscape, and dispossessed the indigenous groups of their lands. How? The standard explanation for the Thule replacement of the Dorset is that the former were better adapted to northern climes. I know of no explanation for the Na-Dene expansion, but it probably had some rationale, social or technological. The fact relatively “pure” Saqqaq were later supplanted by a genomically hybrid populations also points to the complexity of these migratory narratives. The First Americans “struck back” in this case, shoving aside the pioneers of northern living who had likely originated more recently from the margins of eastern Asia. Of course, the Eskimo-Aleut and related peoples were not First Americans only, rather, it was the old (First American) and new (Asian) ganging up upon the not so old or new (Asian).