
But what is most interesting, though not necessarily surprising, is that of those Argentines who claim four European grandparents (N = 22), the average proportion of European ancestry was 91 percent. The issue here is that an individual who claims four European grandparents should have close to 100 percent European ancestry. So what’s going on? First, I think the use of ancestrally informative markers is probably introducing noise; we can’t be sure that there won’t be residual “non-European” ancestry even in Europeans. Second, the respondents might be honest about what they know, but their grandparents may have not told them the whole truth about their backgrounds With a standard deviation of 9 percent I’m pretty sure that some of these 22 individuals do have substantial non-European ancestry. I don’t think ancestrally informative markers would be off that far.
For me the key fact to observe is that if you drew 22 random white (non-Hispanic) Americans you are almost certainly to get no more than a few percent non-European ancestry at most. If you selected Americans who claimed 4 European born grandparents there would be almost no non-European ancestry. Over the past year and a half I have done deeper analyses of friends who have received genotypes from 23andMe. These results align with what I’ve observed. White Americans generally look in vain for Native American ancestry. In contrast, white Latin Americans tend to have substantial non-European ancestry. And intriguingly it seems that many have unknown African ancestry. This highlights the difference between the settlement of Anglo-America, and Latin America. The demographic replacement of Amerindians in Anglo-America was radical and extreme. In contrast, even in self-consciously European settler regions such as South American’s southern cone a substantial proportion of Amerindian ancestry is present in contemporary populations. Because of the large number of Native Americans of mixed heritage it is likely that total Native American identified population is actually very similar to the amount of non-Hispanic Native American ancestry in the USA (i.e., numerous non-Native American identified whites and blacks with small quanta of ancestry will sum to be about the same absolute amount as the small number of Native Americans who are substantially indigenous). While 1.5 percent of Argentines identify as indigenous, 1 percent of Americans are Native American.

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