Anthropologist Bruce Mannheim reports that a recent well-publicized study on the genetics of native Americans, which used genetic analysis to find “at least three streams of Asian gene flow,” is in fact a confirmation of a long-known fact. Mannheim writes:
This three-way distinction was known linguistically since the 1920s (for example, Sapir 1921). Basically, it’s a division among the Eskimo-Aleut languages, which straddle the Bering Straits even today, the Athabaskan languages (which were discovered to be related to a small Siberian language family only within the last few years, not by Greenberg as Wade suggested), and everything else.
This is not to say that the results from genetics are unimportant, but it’s good to see how it fits with other aspects of our understanding.
For what it’s worth, as Mannheim writes, languages and genes are transmitted by different mechanisms. The “well-known fact” is that the languages have three groups. The observation of three language groups in no way implies three waves of gene flow from Asia; it is of course also consistent with one initial colonization from Asia and then three groups splitting. The genetic evidence supports the former over the latter.
Sure, the three wave idea has been around for a long time — it’s the right idea, so it was pretty obvious to unbiased observers. Physical anthropologists, for example, noticed a long time ago that Na-Dene Amerindians look different from most Ameridinans, and they both look different from Eskimos, just like their languages suggest.
The problem was that cultural anthropologists became extremely displeased by the three wave theory for a variety of reasons: turf, anti-“reductionism,” delight in “ethnographic dazzle,” and politics: many Amerindian tribal activists claim their tribes were created on the territory they claim, so they don’t like scientific investigations of their pasts.