Gemma Tarlach writes: The great thing about science is supposed to be that you come up with a hypothesis and then you and other researchers try to shoot it down and, if the hypothesis doesn’t hold up, you come up with a new one based on what you learned from destroying the old one. And the scientific method generally works, as long as everyone keeps their egos in check.

Unfortunately, many researchers clung to the idea of a single migration out of Africa, no earlier than 60,000 years ago, for too long. Finds such as a human presence in the Levant 100,000 years ago, for example, were dismissed as a single band of early humans that strayed too far from home and went extinct— in other words, an evolutionary dead end.

Today, however, writing in Science, researchers say that no one can ignore the preponderance of evidence. It’s time, at long last, to revise that tired old timeline of human migration.

The timeline they call for is one of multiple migrations out of Africa beginning perhaps 120,000 years ago. While some of these early explorations certainly failed and became evolutionary dead ends, others, say the authors, survived, not only spreading across Asia but interbreeding with Denisovans and Neanderthals.

Both the archaeological and genetic evidence support a large dispersal from Africa around 60,000 years ago, but it was by no means the first — or the last — to occur. [Continue reading…]