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HOMO SAPIENS lived in Greece 210,000 years ago. The finding rewrites human prehistory, suggesting our ancestors migrated out of Africa 鈥� and reached Europe 鈥� earlier than we thought.

The evidence comes from Apidima cave in southern Greece. Two hominin skulls, both missing their lower jaws, were discovered in the cave in the 1970s. They were thought to be from Neanderthals, who lived in Europe long before modern humans arrived.

Katerina Harvati at the University of Tubingen in Germany and her colleagues have now taken a closer look. They CT-scanned the skulls and compared their shapes to other hominin specimens. As expected, one of the skulls was from a Neanderthal. But to their surprise, the other didn鈥檛 fit the Neanderthal mould, and was instead from a modern human.

The next step was to find out how old the skulls were. This was difficult, because they were found encased in a block of hardened mud and rocks stuck to the cave ceiling. 鈥淭his means that they did not come from the same context as any material excavated from the cave floor,鈥� says Harvati.

So Harvati鈥檚 team turned to uranium-thorium dating, which estimates the age of an object by tracking the decay of radioactive elements. This found the Neanderthal skull to be 170,000 years old. But the human skull was significantly older: 210,000 years old. 鈥淭his age makes it older than any other accepted Homo sapiens specimen outside of Africa,鈥� says Harvati

Nature, ).

In the early 2000s, most anthropologists agreed that Homo sapiens arose in Africa 200,000 years ago and that everyone of recent non-African descent came from a group that left Africa about 60,000 years ago, with Europe reached 45,000 years ago.

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However, this story is being revised. Fossils from modern humans found in Morocco date to 315,000 years ago, pushing back the age of our species. A jawbone found in an Israeli cave is 177,000 years old, meaning humans roamed beyond Africa earlier. There are also putative modern humans in China at similarly early times, but these are disputed.

Before these discoveries, the Apidima find would have been a shock, but 鈥渘othing surprises us any more鈥�, says Fred Spoor of London鈥檚 Natural History Museum.

Mathieu Duval at Griffith University in Nathan, Australia, points out that the uranium-thorium dating method gives the minimum age of the fossils, meaning the skulls could be even older.

Key findings must now be reconsidered, says Eleanor Scerri at the Max Planck Institute for the Science of Human History in Jena, Germany. For instance, 65,000-year-old cave art from Spain has been attributed to the Neanderthals, as modern humans were assumed to be absent from Europe. 鈥淭hose assumptions can鈥檛 be made now,鈥� she says.

The human skull at Apidima does make sense of a puzzle. Famously, humans and Neanderthals interbred about 50,000 years ago, leaving all people of recent non-African descent with a small amount of Neanderthal DNA in their cells. But it also seems they interbred over 200,000 years ago, giving Neanderthals human DNA. This made no sense if they lived on separate continents, but the Apidima skull suggests they overlapped and so could have met.

In separate research, Adam Siepel of Cold Spring Harbor Laboratory in New York and his colleagues have reanalysed modern human and Neanderthal DNA using a new technique. They found that the early interbreeding occurred between 300,000 and 200,000 years ago (, ). The two studies are 鈥渃onsistent in that respect鈥�, he says.

It remains clear that humans evolved in Africa, says Scerri. 鈥淭he oldest fossils are still in Africa and they鈥檙e 100,000 years older than these,鈥� she says.

However, Scerri says there may have been multiple dispersals out of Africa, perhaps enabled by a greening of the Sahara and Arabian deserts, which happens every 100,000 years.

Scerri and her colleagues promote African multiregionalism: the idea that there were many ancient human populations living in Africa, which were sometimes isolated and sometimes connected. It now seems this web of populations extended beyond Africa. 鈥淲e have this sort of human patchwork of very small populations,鈥� she says.