A little off the top
Reconstructing a polar people
The world of evolutionary biologists, paleo-Indian archaeologists, and DNA researchers is all abuzz with recent research reported by Eske Willerslev of Copenhagen, Denmark. With a tuft of human hair harvested from permafrost in Quqertasussuk, Greenland, Willerslev and his team were able to secure the first ancient-human genome. From that they coaxed detailed information about a people who made trans-Arctic journeys 5,500 years ago and about the man who belonged to the hair, who hunted in the area four millennia ago.
Willerslev is a professor in the biology department at the University of Copenhagen and director of the university’s Centre for GeoGenetics. He talks about his work in a pair of public events presented by Southwest Seminars: a lecture on Sunday, April 11, and a panel discussion on Monday, April 12.
The other panelists are Bruce Bradley, a paleo-Indian archaeologist from the University of Exeter, United Kingdom; Michael B. Collins, paleo-Indian archaeologist with the Gault School of Archaeological Research at Texas State University-San Marcos; and Jane Hill, a historical linguist and retired Regent’s Professor of Anthropology at the University of Arizona. The panel moderator is Eric Blinman, director of the Museum of New Mexico’s Office of Archaeological Studies.
Willerslev has a fondness for exploring the cold lands of the north, and the rigors of that work have nurtured in him the necessary stamina for his intensely persnickety research protocols. Such meticulousness is essential in preventing contamination of ancient artifacts with modern DNA.
In that regard, ancient hair is a safer bet than other DNA sources. “Hair has proven to be very good in the sense that all the contamination is on the surface only,” Willerslev said in a recent interview. “Bones are more porous, so microbes and other contamination can enter. Hair is like plastic and can be cleaned.”
The path to the currently famous tuft of hair — detailed in a story on the cover of Nature magazine in mid-February — was not a straight and easy one. In 2006, Willerslev shivered through six weeks of searching through ancient human camps in Greenland’s northern tundra and found nothing. Two years later, he found what he was looking for right in Copenhagen. “The tuft of hair was basically found in 1986 during an excavation of one of these sites, and people had forgotten about it,” he said. “It was just in a plastic bag in the basement of the Natural History Museum of Denmark.”
When they realized they had hair from a paleo-Eskimo man, Willerslev and his team set about examining and analyzing the hair. The technology used to read a genome — a complete set of chromosomes containing all of a species’ genetic information — is called “second-generation high-throughput sequencing.” The sequencing device chosen by Willerslev is a machine called the Illumina.
After preparation of the genome sample (which included tagging “the millions of fragments of extracted DNA with a barcode-like sequence to distinguish them from stray modern human DNA,” according to the story in Nature), it was sent to the Beijing Genomics Institute. “They have 120 of these machines in China,” Willerslev said. “It would have taken us a year to do it with the two Illumina machines we have in Copenhagen, but it took two-and-one-half months using 36 machines together in China. We wanted to finish this very quickly, because we were in competition with another group.”
The project yielded two groundbreaking results. “One is that you can use the genome to describe the individual, the physical, and phenotypical characteristics,” Willerslev said. “We can say this guy had brown eyes, darker skin, shovel-form front teeth, and a tendency to baldness, and that he was genetically adapted to cold temperatures. We can also see that this individual was quite inbred, similar to cousin marriages, which suggests that these guys were living in small family groups that were isolated from one another.
“Even though he was found in Greenland in the New World, his contemporary relatives actually live in northeastern Siberia. So it strongly suggests there was migration from the Old World to the New World about 5,500 years ago that didn’t leave any contemporary descendants in the New World — so migration independent of Native American ancestors and independent of Inuit ancestors.”
This flies in the face of a previous theory — that the earliest settlers in Greenland were Native American or Inuit. The Willerslev team compared the paleo-Indian DNA with that of modern humans and
Cold bearings: Eske Willerslev Opposite page: artist’s impression of a paleo-Eskimo man by Nuka Godfredsen; images courtesy Nature magazine