Scientists are one step closer to bringing the woolly mammoth back from extinction, after uncovering almost the entire genomes of two mammoths.

McMaster University researcher Hendrik Poinar has been working to sequence the woolly mammoth genome for a decade. (McMaster University)

A team of researchers from Sweden, the U.S. and Canada sequenced almost the complete library of DNA from well-preserved mammoths recently discovered in Russia after being frozen in permafrost for thousands of years, they reported today in the journal Current Biology. The study was led by Eleftheria Palkopoulou at the Swedish Museum of Natural History.

The genomes are already providing new information about mammoth evolution. They could soon help reveal what makes mammoths unique in the elephant family and why they went extinct.

Canadian researcher Hendrik Poinar said re-creating the mammoth using cloning technology is a "much more real possibility." Poinar, an evolutionary geneticist, is the director of the Ancient DNA Centre at McMaster University in Hamilton.

Woolly mammoths evolved just 500,000 years ago in the area between Russia and Canada, and went on to spread both east into North America and west into Asia. They went extinct from their last refuge, islands off Siberia and Alaska about 4,000 years ago.

"Egyptians were building pyramids while mammoths were still cavorting about," Poinar told CBC News.

]Among those mammoths was an adult male that lived around 4,300 years ago on Russia's Wrangel Island in the Arctic Ocean, one of the two whose DNA was used in the study.

The other was a baby male that lived 45,000 years ago in Siberia.

Poinar and his collaborators spent 10 years testing dozens of samples before finding some that were well-preserved enough to sequence. Only now is DNA sequencing technology advanced enough to make the project practical.

Mysterious near-extinction

Now, by looking at the mammoths' genomes, the researchers can see that the mammoths went through a mysterious near-extinction about 300,000 years ago.

That's surprising because it doesn't coincide with any major shifts in climate, Poinar said.

They recovered and regained their genetic diversity, but were severely inbred by the time the Wrangel Island mammoth was born, the study shows.

This is the trunk of a baby mammoth. One of the two mammoths whose DNA was used in the study was just a baby. (Love Dalén/Swedish Museum of Natural History.)

The findings suggest factors other than climate could wipe out large numbers of mammoths, and makes the cause of their extinction even more mysterious.

Scientists aren't sure what caused mammoths to go extinct, although climate change and humans are thought to have played roles.

Poinar hopes that closer examination of the genome will show what genes give mammoths the characteristics that set them apart from elephants, such as a woolly coat and extra fat to survive the cold of the Arctic during the Ice Age.

"It would be very nice to have a handful or bucketful of actual changes that make the mammoth the mammoth," he said.

Such genes would be of interest to both evolutionary biologists and those who aim to recreate the woolly mammoth, such as George Church at Harvard University.

Poinar said the new woolly mammoth genomes have been provided to Church's team, but the two teams aren't working together directly.

That said, he cautions, bringing back a mammoth is still years away.

"I have no question that it can be done. I have no question that it will be done at some point in the future, but I cannot tell you how quickly it will be done."

He noted the genome is only one component needed to achieve such a feat.

"You need to start with that, but that's step one of 20 steps and all of those are technically tremendously challenging," Poinar said.

When it comes to de-extinction, he said people need to consider why they're doing it and debate whether or not they should.