Originally posted by twhitehead
An interesting hypothesis, but they seem to be claiming to have proved it - with 2 samples. I am not impressed.
They haven't proved it, exactly, and it's not their hypopthesis, either. It's rather old. I recall an article by (IIRC) Asimov arguing that the native Americans were particularly susceptible to Eurasian diseases, while the opposite did not apply, for a very similar reason. After all, diseases often need vectors, which are usually limited by climate. Thus, people all over Eurasia could share, and develop a resistance to, one another's diseases, which therefore evolved to be more virulent. By contrast, diseases in America were limited to a smaller group of humans, and stayed relatively mild.
It's a pretty obvious hypothesis, if you look at a map. But "pretty obvious when you look at a map" proves nothing, of course. You need evidence other than reasoning. And that is what these people have provided - genetic evidence that backs up this existing theory. It doesn't prove
anything, and in fact the article never uses that word, but it does support the theory. More evidence may be desired, but this is support for, not against it.
678 markers investigated in 68 populations is rather more than "2 samples", by the way.