From the results of early DNA studies in the late 1980s and early ’90s, scientists argued that anatomically modern humans evolved in Africa, and then expanded into Asia, Oceania, and Europe, beginning about 60,000 years ago. The idea was that modern humans colonized the rest of the world in a succession of small founding groups–each one a tiny sampling of the total modern human gene pool. These small, isolated groups settled new territory and replaced the archaic humans that lived there. As a result, humans in different parts of the world today have their own distinctive DNA signature, consisting of the genetic quirks of their ancestors who first settled the area, as well as the genetic adaptations to the local environment that evolved later.
This view of human history, called the “serial founder effect model,” has big implications for our understanding of how we came to be who we are. Most importantly, under this model, genetic differences between geographically separated human populations reflect deep branchings in the human family tree, branches that go back tens of thousands of years. It also declares that people have evolutionary adaptations that are matched to their geographical area, such as lighter skin in Asians and Europeans or high altitude tolerance among Andeans and Tibetans. With a few exceptions, such as the genetic mixing after Europeans colonized the Americas, our geography reflects our deep ancestry.
Well, it’s time to scrap this picture of human history…
h/t Kevin B