Published online 10 February 2010 | Nature | doi:10.1038/news.2010.64

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DNA secrets of the ice hair

First ancient human genome sheds light on origins of Arctic people.

Artist's impression of ancient man.Artist's impression of original owner of tuft of hair.Nuka Godfredsen

A tuft of hair trapped in permafrost around 4,000 years ago has yielded DNA for the first sequence of an ancient human genome.

The sequencing of this Palaeo-Eskimo, reported today in Nature1, gives researchers unprecedented insight into the movements and make-up of early humans.

"It is extremely exciting," says Brian Kemp, a molecular anthropologist who probes ancient DNA at Washington State University in Pullman and was not involved in the work. "This serves as a benchmark to create maps of genetic variation at different times and places. You then can watch evolution occur."

An archaeological team from Denmark originally found the hair in 1986, at an archaeological site called Qeqertasussuk in Greenland, but it lay largely undisturbed inside a cabinet in the basement of the Natural History Museum of Denmark in Copenhagen for more than two decades.

In 2008, it was rediscovered by the University of Copenhagen's Eske Willerslev, who then led a team in extracting and sequencing DNA from the hair. Overall, 79% of the genome was sequenced 20 times over — twice the in-depth analysis given to the first modern human genome.

"They did it right," says Kemp. "The data make sense."

Saqqaq attack

The hair came from a male of the Saqqaq culture and analysis of the genome shows that the hair's owner was probably stocky and had dark skin and brown eyes. His genome also reveals a risk of baldness.

Willerslev, the founding director of the University of Copenhagen's Centre for GeoGenetics, told Nature he was examining the man's Y chromosome when he realized the high quality of the preserved DNA. "I knew the sample was really good then," he says, "And it was really important, because it was from one of the first people into the Arctic."

By comparing the genome with sequences from modern ethnic groups, the team found the Saqqaq's closest relatives to be the Chukchis of eastern Siberia.

This indicated that, about 5,500 years ago, the Saqqaq migrated across the Bering Strait and around the Arctic Circle, then settled along the shore of Disko Bay in western Greenland some 1,500 years later. The area was rich in game such as seals, reindeer and foxes, which is reflected in other specimens encased in the permafrost that held the Saqqaq hair.

Tools excavated at the site where the hair sample was excavated.Bjarne Gronnow

Interestingly, however, the Saqqaq are not ancestors of either Greenland's Inuits or the native peoples of North America, meaning that the Saqqaq's migration must have been independent of that of these groups' forefathers. This genetic detail offers a new understanding of migrations to North America.

"It is mind-blowing how much information they were able to get out of the Saqqaq DNA," says co-author and biological anthropologist Michael Crawford of the University of Kansas in Lawrence, who provided comparative DNA samples. "It is a truly significant piece of work."

Speed sequencing

With help from their colleagues in China, led by Jun Wang at the BGI (previously the Beijing Genomics Institute) in Shenzhen, Willerslev's team pushed ahead at breakneck speed, completing the sequencing in about two and a half months at a cost of around US$500,000. Wang, a deputy director of the BGI and co-senior author, was able to provide the Willerslev group with unparalleled access to sequencing capacity.

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One of the main surprises for Willerslev is that his group is the first to publish a sequence from an ancient human, because other researchers are close to publishing a Neanderthal genome.

"I thought we would be beaten," Willerslev confesses.

Now he is moving on to the next project: to try to sequence an ancient human specimen from a more temperate climate, where the DNA may have degraded more and be more difficult to capture. 

  • References

    1. Rasmussen, M. et al. Nature 463, 757-762 (2010). | Article
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