...A new commentary paper published today in Trends in Ecology & Evolution is challenging the predominant view that our species, Homo sapiens, emerged from a single ancestral population and a single geographic region in Africa. By looking at some of the latest archaeological, fossil, genetic, and environmental evidence, a team of international experts led by Eleanor Scerri from Oxford’s School of Archaeology have presented an alternative story of human evolution, one showing that our species emerged from isolated populations scattered across Africa, who occasionally came together to interbreed. Gradually, this intermingling of genetic characteristics produced our species.
...“The idea that humans emerged from one population and progressed in a simple linear fashion to a modern physical appearance is attractive, but unfortunately no longer a very good fit with the available information,” said Scerri. “Instead it looks very much like humans emerged within a complex set of populations that were scattered across Africa.”
The reality, as suggested by this latest research, is that human ancestors were spread across Africa, segregated by diverse habitats and shifting environmental boundaries, such as forests and deserts. These prolonged periods of isolation gave rise to a surprising variety of human forms, and a diverse array of adaptive traits. When stratified groups interbred, they preserved the best characteristics that evolution had to offer. Consequently, the authors say that terms like “archaic humans” and “anatomically modern humans” are increasingly problematic given the evidence.
Scerri said occasional episodes of interbreeding between these different, semi-isolated populations created a diverse “meta-population” of humans within Africa, from which our species emerged over a very long time. Our species, Homo sapiens, emerged around 300,000 years ago, but certain characteristics, like a round brain case, pronounced chin, and a small face, didn’t appear together in a single individual until about 100,000 years ago, and possibly not until 40,000 years ago—a long time before genetics and other archaeological evidence tells us our species was already in existence. Isolated populations came together to exchange genes and culture—two interrelated processes that shaped our species, explained Scerri....