blog.rightreading.com

This map, from arstechnica, shows the distribution of genes of a protohuman species, Denisova hominins, among modern humans. The blue area in Europe, West Asia, and North Africa represent a low level of distribution of Denisovan genes, presumably because interbreeding in these areas was instead with Neanderthals. The Denisovan genes are most prevalent in New Zealand, but also in Australia, Southeast Asia, and southern China.

But what is striking about this map to me is something else: there is a strong distribution of Denisovan genes in northern South America. While there could be other explanations for this, this map seems pretty clearly to be indicating, in my opinion, that humans traveled directly across the Pacific to South America, and not across the Siberia-Alaska land bridge as used to be the conventional wisdom. It is possible that migration occurred that way too, but as far as this Denisovan-affected population is concerned, it sure looks like they just lit out straight across the Pacific.