DNA traces woolly mammoth extinction

LONDON, June 11 (UPI) -- British scientists used ancient-DNA to determine the cause of the disappearance of woolly mammoths, one of the most iconic of all ice age giants.

DNA from mammoth fossils revealed a genetic signature of a range expansion after the last interglacial period.

"In combination with the results on other species, a picture is emerging of extinction not as a sudden event at the end of the last ice age but as a piecemeal process over tens of thousands of years involving progressive loss of genetic diversity," said Ian Barnes of the University of London. "For the mammoth, this seems much more likely to have been driven by environmental, rather than human, causes, even if humans might have been responsible for killing off the small, terminal populations that were left."

Barnes and Adrian Lister of University College London said they found two distinct genetic groups, implying mammoths diverged in isolation for some time before merging back into a single population.

The DNA further suggested that, no later than 40,000 years ago, one group died out, leaving only the second alive at the time of the mammoth's total extinction.

The study appears in the journal Current Biology.