Here I thought we were all descendants from multiple mutant generations of Australopithecus afarensis from Ethiopia and Kenya!
Caucasians seem to be leftovers from a few that survived the last ice age in caves in Anatolia and Spain. This
genetic bottleneck explains the high genetic similarity between most humans nowadays since in those periods, not the classical Darwinian natural selection but
genetic drift was the name of the game.
There have been several migration waves from East-Africa along the highway of the Nile along the Middle East and the Southern Asian shores, up till Australia. All these settlements except the ones of the last wave died out. One of the early waves remained in Australia (but their breadcrumbs going there were wiped out) as the aboriginals which are genetically quite different from current Asians.
Also don't forget the non-HSS (Homo Sapiens Sapiens) strains like the Neanderthals that coexisted with HSS in Europe till just 30,000 years ago. They were probably a leftover from a very early migration. HSS only migrated (the Out of Africa theory) to Europe/Asia a mere 150K years ago.
Western Africans also are genetically more different from the rest as they have been trapped under the Sahara and by the dense rain forest in Central Africa. Their only serious migration was the slave trade to the Americas.
The Asian eye folding may just be an amplification of a random mutation by genetic drift in a very small population. That drift stopped now since they are with 2.5 billion.
The skin albedo (melanin enrichment) is not really genetic but is steered by modulators of genes that can adapt 1000x more quickly than genes. It has been said any population migrating south will have a black skin within 15,000 years only (see the Tamils), and a white skin migrating north as skin albedo is a trade-off between death by skin cancer and death by lack of Vitamin D.
Boom diada boom diada, it's a wonderful world.
(back to work)
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