DNA analysis of ancient human hair from northwest Greenland has suggested that the first Eskimos in the New World came directly from Asia, and did not descend from Native Americans as was previously believed.
According to a report in National Geographic News, the analysis also suggests that these pioneer Eskimos later died out and did not give rise to the Inuit living in Greenland today.
The research is based on DNA analysis of a clump of frozen hair from a so-called Paleo-Eskimo, which was found preserved in permafrost soil in the Disco Bay area in the 1980s in Greenland.
The hair, which belonged to a male who lived some 4,000 years ago, has provided the first ever complete mitochondrial genome for an ancient human, according to a team led by Tom Gilbert of the Center for Ancient Genetics at the University of Copenhagen, Denmark.
Mitochondrial DNA is passed down from mother to child and thus gives a genetic marker to an individual's maternal ancestry.
In the ancient Greenland Eskimo's case, his hair revealed that his people came from Siberia, the study found.
"The Paleo-Eskimo's genetic relatives survive today only in small pockets in northeastern Siberia and the Aleutian Islands, which stretch across the Bering Sea from Alaska to Russia," said Gilbert.
Previously, there were two main theories to explain the ancestry of the first Eskimos in Alaska, Canada, and Greenland.
The theories held that they either descended from Native Americans who colonized North America at least 14,350 years ago, or they came from the same source area in Siberia that gave rise to modern Eskimos, such as those who have lived in Greenland for the past 1,000 years.
"Then there is a third idea that they were independent to both-and that's what it turns out to be," said Gilbert.
The new research suggests that the original Paleo-Eskimos of the New World were replaced by later colonizers, who spread eastward from Siberia.
"There would have been populations all the way from Alaska to Greenland, but then whole thing vanishes and another lot come in," said Gilbert. "A separate, new migration gave rise to the current Inuit," he added.
Gilbert and colleagues suggest that past ancient Eskimo populations succumbed to periods of climate cooling.
"Obviously, it's an extremely tough environment up there, and it may be that the environments got so harsh that the populations got smaller and smaller and collapsed," said Gilbert.