Early Humans Left Africa Much Earlier Than Previously Thought

Hundreds of thousands of years ago, our species arose in Africa. Research on the DNA of living people has indicated that early Homo sapiens stayed on the continent for a long while, with a small group leaving just 50,000 years ago to populate the rest of the world.

But those findings have raised a puzzling question: Why did our species take so long to move beyond Africa?

Several new studies, including one published on Thursday, argue that the timeline was wrong. According to new data, several waves of modern humans began leaving the continent about 250,000 years ago.

“It wasn’t a single out-of-Africa migration,” said Sarah Tishkoff, a geneticist at the University of Pennsylvania. “There have been lots of migrations out of Africa at different time periods.”

Those earlier migrations went largely overlooked until now, Dr. Tishkoff said, because the people who moved did not leave a clear fossil record of their existence, nor did living people inherit their DNA.

But scientists are now discovering hints of those early waves in the DNA of Neanderthals.

The Neanderthal lineage most likely began in Africa about 600,000 years ago before moving into Europe and Asia. In 2010, Svante Paabo, a Swedish geneticist, and his colleagues at the Max Planck Institute for Evolutionary Anthropology in Leipzig, Germany, published the first draft of a Neanderthal genome, reconstructed from 40,000-year-old fossils found in Croatia.