How We Got Here: DNA Points to a Single Migration From Africa
Modern humans evolved in Africa roughly 200,000 years ago. But how did our species go on to populate the rest of the globe?
The question, one of the biggest in studies of human evolution, has intrigued scientists for decades. In a series of extraordinary genetic analyses published on Wednesday, researchers believe they have found an answer.
In the journal Nature, three separate teams of geneticists survey DNA collected from cultures around the globe, many for the first time, and conclude that all non-Africans today trace their ancestry to a single population emerging from Africa between 50,000 and 80,000 years ago.
“I think all three studies are basically saying the same thing,” said Joshua M. Akey of the University of Washington, who wrote a commentaryaccompanying the new work. “We know there were multiple dispersals out of Africa, but we can trace our ancestry back to a single one.”
The three teams sequenced the genomes of 787 people, obtaining highly detailed scans of each. The genomes were drawn from people in hundreds of indigenous populations: Basques, African pygmies, Mayans, Bedouins, Sherpas and Cree Indians, to name just a few.
The DNA of indigenous populations is essential to understanding human history, many geneticists believe. Yet until now scientists have sequenced entire genomes from very few people outside population centers like Europe and China.
The new data already are altering scientific understanding of what human DNA looks like, experts said, adding rich variations to our map of the genome.
Each team of researchers tackled different questions about our origins, such as how people spread across Africa and how others populated Australia. But all aimed to settle the controversial question of human expansion from Africa.
In the 1980s, a group of paleoanthropologists and geneticists began championing a hypothesis that modern humans emerged only once from Africa, roughly 50,000 years ago. Skeletons and tools discovered at archaeological sites clearly indicated that modern humans lived after that time in Europe, Asia and Australia.
