DNA tests on almost 1,000 people have shown all non-Africans are related to a single population that migrated from Africa between 80,000 and 50,000 years ago.

The research, published in the journal Nature, details how geneticists took DNA samples from people of different cultures in different parts of the world. They then traced back their genetic links through the millennia. All arrived at the same conclusion.

This animated video, produced by the University of Hawaii, shows the spread of the human race across the globe over a 125,000 year period.

Credit: Tobias Friedrich

The video shows small clusters of humans living on the Arabian Peninsula around 120,000 years ago. Archaeological findings support this theory. The researchers say that many of these early pioneers died out without passing on their genes to modern humans.

But around 80,000 years ago the exodus from Africa accelerated rapidly, with humans spreading out across the Middle East and southern Asia.

The distribution of humans 80,000 years ago
Image: Tobias Friedrich

The genetic similarities between a diverse range of modern humans and these pioneers points to a single mass exodus from Africa, according to David Reich from Harvard University. He and the other researchers also found evidence to show early Africans splitting into distinct groups around 200,000 years ago.

Joshua Akey from the University of Washington in Seattle says evidence of a single mass migration event is a major advance in our understanding of our earliest ancestors. “The more we understand about this particular event in human history, the more it provides a complete picture of our past," he says.

What made people move?

The research teams found that climate change and other environmental factors were the most likely reason for the mass migration out of Africa.

Luca Pagani and Mait Metspalu, from the Estonian Biocentre, explain that early migrants could only leave Africa when variations in the Earth’s rotation led to higher rainfall and cooler temperatures across areas which are now desert. These climate fluctuations created “green corridors” that were rich in vegetation and drinking water. These corridors allowed early humans to cross areas in the Arabian Peninsula and the Levant region that were previously too hostile to support human life.