Analysis of his genome, reported in the current issue of Nature, has given researchers new insights into the extinct Saqqaq culture – the first known to inhabit Greenland – but the work also revealed a variety of Inuk's physical traits. He had brown eyes, brown skin, shovel-shaped front teeth and a problem with dry earwax. He might have been going bald, too, but not completely. In fact, Inuk managed to leave behind a very valuable clump of hair.
The lead scientists on the 53-person team, geneticists Eske Willerslev and Morten Rasmussen at the University of Copenhagen, found out about the hair, which had been excavated from permafrost in the 1980s, from an associate at the Natural History Museum in Denmark. One of the difficulties with analyzing ancient DNA is the risk of contamination from modern human DNA or damage inflicted by bacteria or fungi. But recent studies have shown that hair tends to protect DNA against the latter two threats.
Willerslev took special care to guard against contamination as his group analyzed the sample. Still, these were 4,000-year-old locks, so it wasn't perfect. "We were dealing with very, very short pieces of DNA," Willerslev says. "It was a massive puzzle of 3.5 billion pieces that you have to stick together in the right way."
That puzzle demanded help. Willerslev and his group did the initial analysis in Copenhagen, then shipped samples to labs in the United States, China, Great Britain and Australia; other scientists involved came from Estonia, France and Russia. "It was a huge amount of people involved in piecing all this together," he says.
The group analyzed more than 350,000 of the genome's single nucleotide polymorphisms, or SNPs. In modern people, scientists have been able to link these tiny variations in DNA to a number of characteristics, so Willerslev and his group scoured DNA databases for SNPs that Inuk shares with modern people.
The result was an unprecedented level of detail regarding the physical traits, metabolism and genetic predispositions of this ancient man. "I was actually quite surprised at the details we could get out of this," Willerslev says. "I think it's quite amazing that you could say that this guy had dry earwax."
Besides ear wax and skin color, the genetic detective work also allowed the scientists to determine how the Saqqaq relate to other ancient and modern people. They concluded that Inuk's ancestors migrated to the New World from Siberia more than 4,400 years ago. Previously, researchers contended that the Saqqaq people were ancestors of the Inuit and Native Americans of today, but the genetic analysis shows this is not the case. "It was very clear that he's not ancestral to modern people found in the New World," Willerslev notes. "His closest relatives are three Siberian groups."
Inspired by their success with Inuk, Willerslev and his team are now turning to a different continent. He plans to use similar techniques on 150 different ancient hair samples collected from all over South America, some of which date back 8,000 years. This next round of research will again address migration patterns, he says, but the scientists will also be exploring a phenomenon that could hold broader interest. "We're looking into the origin of clothes, and the clothes culture in the Americas."