One founding for Native Americans

Earlier this week I hinted that I had a priori genetic reasons for being skeptical of a "two wave" theory for the peopling of the New World. Well, I was going to do some literature searches and slap something together that was meaty, but I don't have time, so I'll just offer up an attenuated but sufficient outline of what my issue is. First, look at this map and note the "Amerindians" and other populations. Now, look at this table and note the level of heterozygosity of Amerindians vs. other populations. In short, Amerindians are notoriously genetically homogenous on the MHC loci compared to other human populations. This is a key point, the MHC loci and the HLA variants associated with them are extremely polymorphic, and either overdominance or frequency dependent selection maintains alleles which should be extinct. Some of the alleles predate the human species, that is, there are ...