Rampant inbreeding most probably caused the extinction of the Dorsets, a tribe of Eskimos that inexplicably disappeared 700 years ago.

A group of more than 50 international researchers studied why and how the Dorsets of the Arctic disappeared. The study and its findings were published in the journal Science on August 28.

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The Dorsets, who were ancient Paleo-Eskimos, lived in the Arctic, Greenland and parts of Canada for at least 4,000 years. They then disappeared quite suddenly.

Researchers studied 169 DNA samples from the Dorset people to learn more about their migratory habits.

Ancient Eskimos including the Dorsets were descendants of a group of people that migrated from Siberia. Modern Eskimos that currently live in the Arctic region are descendants of other groups of people.

The new study is the first complete genetic look at the people of the Arctic using DNA. In the past, cultural artifacts were the only basis for most research.

There have been theories and counter-theories about the Saqqaq, Dorset and Thule groups being distinct groups.

The new study suggests, however, that the Dorset group is descended from the Saqqaq people, the earliest settlers and migrants that reached the Arctic from Siberia more than 6,000 years ago.

The study also found the modern Inuit people were not descendants of the Dorset group, but of the Thule tribe.

Scientists came to the conclusion that the Saqqaq, Dorset and Thule tribes were in the region at the same time. For some reason, the Dorset tribe chose to isolate itself from other ancient Eskimos.

"This is surprising, because every time people meet each other we find evidence of sex between the people," said Eske Willerslev, an evolutionary biologist at the Center for GeoGenetics at the University of Copenhagen and an author of the study.

"But here we have a unique situation, where even though we know they must have been in touch with their neighbors, they chose to live in isolation,"

Rampant inbreeding among the Dorset tribe may have contributed to the weakening of their population, and ultimately their demise.