But hair sample could have been from a wandering mercenary.
An early wave of migration into the New World and the Arctic has been identified by sequencing a genome from a frozen hair excavated in Greenland.
Archaeological evidence shows that there were two waves of migration to Greenland starting 4,500 years ago, first with the Saqqaq and then the Dorset groups, collectively known as the Paleo-Eskimos.
Later, around 1,000 years ago, came the Thule culture which led to the current native population. The relationship between these three groups has been uncertain.
Some theories hold that Paleo-Eskimos derived from the populations that also led to Native Americans, says Eske Willerslev, of the University of Copenhagen’s Centre for Ancient Genetics. Others argue that, like modern Neo-Eskimo populations, they came from Beringia, the land where the Bering Strait now exists.
All in the hair
Attempting to solve this question, Willerslev and his colleagues sequenced the mitochondrial genome of a Paleo-Eskimo using frozen hair recovered from permafrost at an early Saqqaq settlement at Disko Bay in western Greenland, believed to be between 3,400 and 4,500 years old.
The sample matched with neither Native Americans nor Neo-Eskimos, the team reports in Science1. Instead, it was a good match for a group of mitochondrial haplotypes called D2a1. These haplotypes, themselves groups of genetic variations called alleles, are used by researchers to trace the heritage of modern humans.
Different genetic codes are linked to different regions and groups. D2a1 is linked to Alaska's modern Aleutian Islanders and Siberian Yuit peoples, says Willerslev. “This means there has been migration into the New World that hadn’t been known before.”
It seems that the first migrations into what is now northern Canada and then on to Greenland may not have come from the Native Americans who were already in the Americas, nor from those who later became the Neo-Eskimos.
The whole picture
“What we can show by this data is that Paleo-Eskimos derive from a different group of people than other Native Americans. Toomas Kivisild , University of Cambridge”
The discovery “clarifies the issue about the peopling of Greenland and northern Canada", says fellow author Toomas Kivisild, of the Leverhulme Centre for Human Evolutionary Studies at the University of Cambridge, UK. “What we can show by this data is that Paleo-Eskimos derive from a different group of people than other Native Americans. This is a positive and conclusive result.”
The work does not shed light on the relationship between the Saqqaq and the Dorset cultures, however. Previously studied Dorset remains have only been identified as being in haplogroup D. Whether they are D3, like some of the Neo-Eskimo groups, or D2a1 is yet to be established, the researchers note.
As the work is based on only a single hair sample, it might not be a true representative of the Saqqaq people. The hair might have belonged to an Aleutian sword-for-hire who tagged along with the migration for money before meeting a chilly end.
Three further hair samples from the same site exist and the researchers hope these will yield more information.
“We are still far away from getting the whole picture,” says Willerslev. “This single sample does definitely suggest migration from the Aleutians into the New World.”
Gilbert, M. T. P. et al. Science advance online publication (29 May 2008).