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Mitochondrial Sequences From Indigenous Alaskans Offer Clues to Past Arctic Migrations

NEW YORK (GenomeWeb) – A study from a Northwestern University and University of Utah team suggests a population from Alaska's North Slope served as the source of Paleo-Eskimo and Neo-Eskimo populations that have populated Arctic over the last 4,500 years or so.

As they reported online recently in the American Journal of Physical Anthropology, the researchers did targeted mitochondrial gene sequencing on samples from more than 150 Iñupiat individuals living in eight present-day communities from the Alaska North Slope.

From these sequences, the team saw all of the mitochondrial haplotypes that have been described in existing Arctic populations in Canada, Greenland, Siberia, and the Aleutian Islands. But the Iñupiat also shared basal mitochondrial lineages with Paleo-Eskimo and Neo-Eskimo individuals sequenced in the past, consistent with the notion that the site served as a source of migrant populations stretching back thousands of years.

"This is the first evidence that genetically ties all of the Iñupiat and Inuit populations from Alaska, Canada and Greenland back to the Alaskan North Slope," senior author Geoffrey Hayes, an anthropology, endocrinology, and genetic medicine researcher at Northwestern University, said in a statement.

Past archeological studies suggest Paleo-Eskimo populations moved East from Beringia some 4,500 years ago, introducing terrestrial mammal hunting and other cultural traditions across Arctic Canada and Greenland. A few thousand years later, the Paleo-Eskimos appear to have been largely replaced by Neo-Eskimo whale-hunters who migrated quickly across the region roughly 800 years ago.

To look at how well these migration models fit with genetic patterns in present populations in the far North, researchers did targeted sequencing on mitochondrial hyper-variable regions I and II in 151 individuals from eight Iñupiat communities on Alaska's North Slope, using DNA from saliva samples collected between 2008 and 2010.

From these HVR I and HVR II sequences, the team determined that most of the North Slope participants — nearly 90 percent — fit into the mitochondrial haplogroup A. The remaining individuals belonged to haplogroup D or, rarely, to haplogroup C.

A closer look at the mitochondrial haplotypes pointed to subgroups that included those found in current Arctic populations descended from the Neo-Eskimo migrants, the researchers reported. But they also saw representation of a haplogroup called D2 that's only been described in the remains from more ancient Paleo-Eskimo populations in Canada.

"Our study suggests that the Alaskan North Slope serves as the homeland for both of those groups, during two different migrations," Hayes said. "We found DNA haplogroups of both ancient Paleo-Eskimos and Neo-Eskimos in Iñupiat people living in the North Slope today."

There are also clues that a subset of individuals from Inuit populations in Greenland may have migrated back to Alaska at some point, though more extensive genomic analyses are needed to confirm and flesh out such apparent population movements.