What a long, strange evolutionary trip. The last of the woolly mammoths had North American, not Asian roots, new science suggests.

Many scientists thought the woolly mammoths -- relatives of the elephant -- represented one large population that spanned the Bering Land Bridge between present-day Alaska and Siberia.

Some of those mammoths crossed from Siberia into North America 200,000 years ago. Now, DNA analysis of woolly mammoth fossils shows that from 40,000 to 10,000 years ago, all of the beasts in Siberia showed North American genetic fingerprints, indicating that a cataclysmic event wiped out the species' Siberian predecessors. The findings, based on analysis of 160 remains from North America, Europe and Asia, are in today's Cell Biology.

"That we find such complete disappearance of the early Siberian groups is pretty remarkable," said Ross MacPhee, curator of vertebrate zoology at the American Museum of Natural History, who co-authored the paper. "It sounds like something really bad happened around 40,000 years ago that resulted in their collapse on that continent. It’s a strange and provocative finding."

Another author, Hendrik Poinar of McMaster University, said in a news release that the discovery suggests that woolly mammoths migrated across the Bering Land Bridge earlier than previously thought, then returned to Siberia to replace the older population.

Still unknown is how other species changed during the extinction of the Siberian woolly mammoth, MacPhee said.

"If we knew more about some of these other Ice Age species, we might know more about why these losses occurred in the first place," he said. "It's one of the biggest puzzles in extinction biology."

(Image courtesy of American Museum of Natural History/D. Finin)