Comments on: One founding for Native Americans

By: gcochran

gcochran — Tue, 25 Apr 2006 19:29:53 +0000

There’s more to it than that. Tribes often have _extremely_ limited HLA variation, contain only a small subset of the variation that you see in a wider set of Amerindians. Whereas in the old world, even little tiny groups with very low gene flow have lots of different HLA alleles. [Cavalli-Sforza 1994] You’d think that they’d lose those rare alleles by drift, but they don’t – has to be frequency-dependent selection, the same force that has kept alleles around for tens of millions of years. But in the Americas, it appears that those frequency-dependent forces simply did not exist. [Slatkin and Muirhead, 2000]
So, two things going on, which may or may not modify your conclusions. First, a bottleneck, probably: afterwards, a world in which HLA simply does not matter.

By: razib

razib — Tue, 25 Apr 2006 13:13:54 +0000

Or is that a separate issue, since neither of these groups penetrated to the
major Amerindian population centers?
that’s what i’m assuming.

By: Ethan

Ethan — Tue, 25 Apr 2006 09:09:02 +0000

Are you saying that the evidence does not support a late intrusion by the
ancestors of the Athabascans (including, e.g. the Navajho), and later the Inuit?
Or is that a separate issue, since neither of these groups penetrated to the
major Amerindian population centers?