Science

Last woolly mammoths had North American roots: study

The last of the woolly mammoths to roam the Earth had North American ancestry, according to a study released Thursday by researchers at McMaster University in Hamilton.

The last of the woolly mammoths to roam the Earth had North American ancestry, according to a study released Thursday by researchers at McMaster University in Hamilton.

The study, based on DNA of woolly mammoth specimens, is expected to cause some controversy among paleontologists, because it suggests that North American mammoths replaced their Eurasian counterparts. The study appears in the September issue of Current Biology.

Hendrik Poinar, associate professor in the departments of anthropology, and pathology and molecular medicine at McMaster University, said the results of the study are surprising.

"Scientists have always thought that because mammoths roamed such a huge territory, from western Europe to central North America, that North American woolly mammoths were a sideshow of no particular significance to the evolution of the species," he said.

"However, it now appears that mammoths established themselves in North America much earlier than presumed, then migrated back to Siberia, and eventually replaced all pre-existing haplotypes of mammoths."

Poinar said migrations over Beringia, the land bridge that once spanned the Bering Strait, were rare. "It served as a filter to keep eastern and western groups or populations of woollies apart," he said.

DNA evidence reveals ancestry

But the study shows that a migration of North American mammoths did occur. Woolly mammoths lived between 40,000 and 4,000 years ago.

Poinar and Regis Debruyne, a post-doctoral research fellow in Poinar's lab, spent three years collecting and sampling mammoths from much of their former range in Siberia and North America. They extracted DNA and pieced together the samples, comparing and studying hundreds of mammoth specimens using a database of ancient DNA.

Debruyne said the study shows that North American mammoths were more important in evolutionary terms than previously considered by scientists.

"Like paleontologists, molecular biologists have long been operating under a geographic bias," he said.

"For more than a century, any discussion on the woolly mammoth has primarily focused on the well-studied Eurasian mammoths. Little attention was dedicated to the North American samples, and it was generally assumed their contribution to the evolutionary history of the species was negligible. This study certainly proves otherwise."

Ross MacPhee, curator of mammalogy at the American Museum of Natural History and one of the researchers on the study, said the ancient DNA is proof that the last of the woolly mammoths had North American roots.

"Small-scale population replacements, as we call them, are not a rare phenomenon within species, but ones occurring on a continental scale certainly are," he said. "We never expected that there might have been a complete overturn in woolly mammoths, but this is the sort of discoveries that are being made using ancient DNA. Bones and teeth are not always sensitive guides."

Funding for this study was provided in part by the Natural Science and Engineering Research Council, the Human Frontiers Science Program, the Social Sciences and Humanities Research Council, the Canadian Research Chairs program, and the Discovery Channel.

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