for National Geographic News
Siberia's last woolly mammoths descended from North American—not exclusively Eurasian—stock, according to new research.
Scientists studying DNA from the remains of 160 of the animals found the ancient beasts migrated back and forth between Eurasia and Alaska several times over hundreds of thousands of years.
Cousins of present-day elephants (learn more), woolly mammoths are believed to have descended from African mammoths that traveled north through Eurasia and grew "woolly" long hair to survive the harsh climate of Siberia.
They went extinct after the last ice age ended 10,000 years ago.
(Related story: Climate Change, Then Humans, Drove Mammoths Extinct [April 1, 2008])
"The woolly mammoth is not exclusively a Eurasian beast," said lead study author Régis Debruyne of McMaster University in Canada.
"What happened to the mammoths in North America is part of the story and probably at the core of [woolly mammoth evolution]," he said.
Hendrik Poinar, who helped oversee the research, said people tend to think of migration between Siberia and North America going in one direction.
But the search for food drove the North American animals back to Eurasia, said Poinar, an evolutionary geneticist at McMaster University.
"The grass is greener on either side at some point," he said.
The study appears today in the current issue of Current Biology. However, critics argue the research team is jumping to conclusions based on limited data.
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