for National Geographic News
Innovation—not climate change—may have triggered early humans' migration out of Africa, a new study suggests.
For early Homo sapiens, periods of population movement coincided with social advances and tool-making innovation, the work found.
By contrast, human movements didn't match as closely with changes in Africa's climate, such as rainfall variation or other weather issues, as previous research had suggested.
The study authors caution, however, that their work doesn't suggest a specific cause-and-effect relationship.
"We see bursts of migration during a period with technological advances, so technology might have led to the migration," said Zenobia Jacobs, lead researcher from the University of Wollongong in Australia.
Alternatively, migration may have spread new ideas and skills throughout various populations.
"It's like the chicken-and-egg argument—did migration lead to innovation or did innovation stimulate migration?" Jacobs said.
The new study appears today in the journal Science.
Fueled by Fire
Archeologists believe that modern humans inhabited Africa about 200,000 to 150,000 years ago. Recent evidence suggests that human ancestors may have harnessed naturally lit fires as far back as 790,000 years ago.
Humans were making their own fire about 100,000 years ago, and by 60,000 years ago fire-making and tool-making skills as well as sophisticated communication were flourishing.
This coincides with the first human migrations out of Africa, genetic evidence suggests. (Related story: "Massive Genetic Study Supports "Out of Africa" Theory [February 21, 2008].)
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