The Inuit were not the first humans to inhabit the Arctic, a study suggests; that honor goes to "Paleo-Eskimos" from Siberia, with no genetic relation to today's Inuit or Native American people.
DNA studies have identified a single migration from Siberia leading to the region's "Paleo-Eskimo" cultures, which existed until around 700 years ago.
Later separate migration led to the rise of modern-day Inuit, the researchers say.
There has long been debate about the genetic lineages of various Arctic peoples, starting with the first arrivals through several distinct cultural groups to today's inhabitants of the region.
The Arctic regions of North America have been occupied by three broadly-grouped cultures: the Saqqaq up until 2,500 years ago, followed by a succession of Dorset cultures and then the Thule, ancestors of the Inuit, from about 1,000 years ago.
"All kinds of hypotheses have been proposed," Willerslev says. "Everything from complete continuity between the first people in the Arctic to present-day Inuits, [while] other researchers have argued that the Saqqaq and the Dorset and the Thule are distinct people."
DNA from ancient remains showed the Saqqaq and Dorset peoples, considered a single genetic line dubbed Paleo-Eskimos, originated in a single migration from Siberia across the Bering Strait into North America that started around 6,000 years ago.
Those Paleo-Eskimos spread from Alaska to as far as Greenland, but died out about 700 years ago.
DNA from those ancient people and modern day Inuit show no match.
The mystery is why they didn't intermix with the Inuit who had arrived in a second, distinct migration from Siberia; cultural remains have yielded no evidence of interaction, researchers say.
"Almost in all other cases where we look back in the past and we see people meeting each other, they might be fighting with each other but normally they actually have sex with each other as well," Willerslev says. "For some reason, this just didn't happen."
A fascinating aspect of the DNA study is that it corroborates what the Inuit have known -- and have been saying -- for centuries, he says.
Inuit oral tradition has always talked about the earlier peoples they encountered when they first arrived, that they were shy and would flee when approached.