Mankind may have arrived in Europe 150,000 years earlier than previously thought, researchers say, after reassessing an ancient skull found inside a cave in Greece.

The skull was found the cave in the 1970s, and initially identified as Neanderthal. But new techniques have allowed for further analysis of the skull, and scientists found to their astonishment that it is in fact a 210,000-year-old skull belonging to a Homo sapiens.

"It shows that the early dispersal of Homo sapiens out of Africa not only occurred earlier - before 200,000 years ago - but also reached further geographically, all the way to Europe," said Katerina Harvati, a palaeoanthropologist at the Eberhard Karls University of Tuebingen, in Germany.

"This is something that we did not suspect before, and which has implications for the population movements of these ancient groups."

The findings support the idea that Homo sapiens made several, sometimes unsuccessful, migrations from Africa over tens of thousands of years.