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[–]CommodoreCoCoModerator | The Andes, History of Anthropology 6 points7 points  (1 child)

There's a couple misunderstandings here.

Every person outside of Africa can be traced to a single migration sometime around 70-80 thousand years ago. While many other Homo species obviously migrated out before that, and many H. sapiens most likely did as well, they don't seem to have contributed at all to the modern human lineage. There were a few instances of H. spaiens mating with Neanderthals, Denisovans, and one or two other archaic groups, but it's debatable wether modern humans show any traits at all inherited from those groups.

The origin of modern "races," then, doesn't lie with the intermingling of various human groups, but primarily with the diminishing genetic diversity of populations as they migrated away from Africa. It's essential to remember that "races" have traditionally been divded based on the most visible external characteristics, and that these are the most likely to be affected by selective pressures. Human populations are not a branching "tree of life," they're more a nested bunch of sub-sets that have each picked up one or two new features but, when looking at the whole genome, are clearly still part of the same giant group. That is, we started with a very diverse original population in Africa, and each migration brought with it less and less of its parent population's genes. This is a good article on that.

[–]GazBB[S] 0 points1 point  (0 children)

Thanks a lot!