While previous attempts to date the exit of modern humans from Africa have relied heavily on evidence from genetics and archaeology, the researchers behind the new study said data on climate and environment could unlock new clues as to both how and why humans spread from the continent.
"The consensus view has been that modern humans left Africa around 60,000 years ago by a coastal route, skirting around some very arid places, and spread to Australia very quickly," said Michael Petraglia of the University of Oxford, co-author of the study published in the journal Quaternary International.
"We think that's wrong. We think people left Africa multiple times, probably a long time before, and we think it was terrestrial rather than coastal."
He acknowledged the idea goes against a well-established and widely held consensus, but said climate should be taken into account in any theory of movement out of Africa.
"We know that the climate has shifted a lot of times," he said. "We think that has acted like a pump out of Africa, pushing waves of people into South Asia."