Human movement out of Africa had a long pitstop

A region of modern-day Iran likely served as a hub of long-term human occupation for thousands of years, say a cross-disciplinary team studying migration patterns.

Using genetic, fossil and archaeological findings, a dozen researchers set out to learn why humans took so long to inhabit Eurasia after spreading out from Africa around 70,000 years ago.

While records suggest that ‘full spread’ into the northern parts of Asia and Europe had taken place by 45,000 years ago, it has remained unclear where these groups migrated from.

But connecting genetics from modern humans to those of Homo sapiens alive at the time has helped explain where our ancestors were living during this transition.

“We actually look at genetics, both ancient DNA and modern DNA, paleoecology, and archaeology,” says Michael Petraglia, Director of the Australian Research Centre for Human Evolution at Griffith University, and one of the co-authors of the study published in the journal Nature Communications.

“We argue that people first settled when they came out of Africa, in what we call the ‘hub’ location, or the Persian plateau.”

This population was the base from which subsequent waves of human migration occurred into Eurasia, from which the remainder of this region and Oceania were eventually populated.

This combination of genetic, archaeological and environmental data was used to construct a model that favours the Persian Plateau for the migration hub.

And while it’s not clear why humans remained for so long in the region after first leaving Africa, Petraglia suggests the conditions in the region were ideal for supporting a large population.

“It is a bit of a mystery as to what exactly happened,” he tells Cosmos. “And I don’t say that we solved it, but that’s what we’re addressing here, through a combination of evidence.

“We are arguing that this zone, the Persian Plateau, was an ideal setting to actually be living. We undertake environmental research as well, arguing that this region had a mosaic of environments, like savannas, grasslands, even forested zones.

“And the topography is really variable: you have lowlands and highlands, you have mountainous zones, so that hunter-gatherers would have found that a very ideal place to be living.”

Petraglia and his fellow authors suggest their findings gives a starting point for further archaeological investigation into the region that could help plug gaps in science’s understanding the history of human movement across Asia, Europe and Oceania. 

Buy cosmos print magazine

Please login to favourite this article.