Washington: A new, comprehensive review of humans’ anthropological and genetic records has provided the most up-to-date story of the “Out of Africa” expansion that occurred about 45,000 to 60,000 years ago.
This expansion, detailed by three Stanford geneticists, had a dramatic effect on human genetic diversity, which persists in present-day populations.
As a small group of modern humans migrated out of Africa into Eurasia and the Americas, their genetic diversity was substantially reduced.
In studying these migrations, genomic projects haven’t fully taken into account the rich archaeological and anthropological data available, and vice versa. This review integrates both sides of the story and provides a foundation that could lead to better understanding of ancient humans and, possibly, genomic and medical advances.
“People are doing amazing genome sequencing, but they don't always understand human demographic history” that can help inform an investigation, said review co-author Brenna Henn, a postdoctoral fellow in genetics at the Stanford School of Medicine who has a PhD in anthropology from Stanford.
“We wanted to write this as a primer on pre-human history for people who are not anthropologists,” Henn stated.
This model of the Out of Africa expansion provides the framework for testing other anthropological and genetic models, Henn said, and will allow researchers to constrain various parameters on computer simulations, which will ultimately improve their accuracy.
“The basic notion is that all of these disciplines have to be considered simultaneously when thinking about movements of ancient populations,” said Marcus Feldman, a professor of biology at Stanford and the senior author of the paper.
“What we're proposing is a story that has potential to explain any of the fossil record that subsequently becomes available, and to be able to tell what was the size of the population in that place at that time.” he noted.
The anthropological information can inform geneticists when they investigate certain genetic changes that emerge over time. For example, geneticists have found that genes for lactose intolerance and gluten sensitivity began to emerge in populations expanding into Europe around 10,000 years ago.
The study is published in the current edition of the Proceedings of the National Academy of Sciences.
First Published: Tuesday, October 23, 2012, 19:30