for National Geographic News
Humans first moved out of Africa about 70,000 years ago, but 30,000 years later some of them moved back.
That's according to a new study based on DNA evidence from ancient human remains found in Africa.
The study shows that a small group of early humans returned to Africa after migrating to the Middle East.
In addition, the research suggests that the humans' return occurred around the same time that another group of humans left the Middle East and moved into Europe.
"We were rather surprised by the age of the migration back to Africa," said Antonio Torroni, a geneticist at the University of Pavia in Italy.
"We did not really expect that it was 40,000 to 45,000 years old."
"But the age and the fact that the migration had originated in the Levant [a geographical term referring to a large part of the Middle East] led us to link the migration to Africa to that occurring at the same time toward Europe from the same region," added Torroni, who led the research team.
The findings are reported in tomorrow's issue of the journal Science.
The new study builds on the theory, laid out in two separate studies published in Science last year, that humans migrated from Africa in a single dispersal about 70,000 years ago.
(Read Early Humans May Have Crossed Sea to Leave Africa" [May 13, 2005].)
That theory suggests that modern humans left East Africa by crossing the Red Sea, then journeyed south, following a coastal route along the Arabian Peninsula and on to India, Malaysia, and Australia (see a map of human migration).
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