for National Geographic News
Rapid climate change may have enabled early humans to venture out of Africa and colonize the rest of the world, according to a new study.
The research suggests that modern humans first moved out of Africa about 60,000 years ago, after some populations experienced major advances in culture and brainpower.
One likely trigger for these advances was rapid climate change, according to Paul Mellars, professor of prehistory and human evolution at the University of Cambridge in England.
Evidence indicates that modern humans originated in Africa between 150,000 and 200,000 years ago.
But it wasn't until some 100,000 years later that modern humans expanded into Europe and Asia, eventually replacing already established populations such as those of the Neandertals.
So why did it take them so long?
Writing in the June 12 issue of the Proceedings of the National Academy of Sciences, Mellars suggests that sudden fluctuations in rainfall may have spurred humans to spread from Africa.
The changes in rain patterns may have led humans to search for new food sources and also to develop new technologies to suit the changing environment, he says.
"If there's a big change in environment, then people have to change their behavior," Mellars explained.
"You would have to move on to new food supplies, and that would probably require new technology and strategies to exploit it." The bow and arrow, for example, might have been invented around this time, he said.
DNA and Archaeological Evidence
Mellars says clues to what stoked migration out of Africa lie in DNA studies of present-day African groups, as well as important recent archaeological discoveries.
SOURCES AND RELATED WEB SITES