Peopling the Planet
Not long ago, the story was simple. A vanguard of modern humans left their African birthplace 50,000â€“60,000 years ago and quickly conquered Asia. They turned left into Europe some 40,000 years ago, later crossing the Bering Strait and marching southward into the Americas. With their advance, Neanderthals and other earlier peoples dwindled and vanished.
But in the past five years, the picture has grown more complex â€” and more interesting. Few question the idea that modern humans are all emigrants from Africa. But when their journey began, when it ended and what they did along the way makes for a deepening mystery. Discoveries on the Arabian peninsula, for example, show that modern humans were camped on the doorstep of Asia more than 100,000 years ago, nearly twice as long ago as anyone thought. If they went farther at that early date, their presence would explain a smattering of ambiguous artefacts and fossils around Asia.