The frozen north and the first Eskimos

In this week's online edition of Science, a team of researchers from Greenland, Denmark, and other European laboratories report on the first (nearly) complete sequence of ancient mitochondrial DNA. Mitochondrial DNA (mtDNA) is found not in the cell nucleus but inside small cellular subunits called mitochondria--which supply energy to living cells. It is inherited only on the maternal line, and researchers use it to trace the worldwide migrational movements of prehistoric peoples over thousands of years.

The paper (abstract available here, full access requires an individual or institutional subscription) is particularly interesting, however, because the mtDNA was extracted from the hair of a so-called Paleo-Eskimo who lived on the west coast of Greenland roughly 4000 years ago. As I point out in an accompanying news article in Science (sorry, same restrictions apply, but you can read Nicholas Wades' account in the New York Times), the DNA sequence of this particular individual is unrelated to both Native Americans and today's Eskimos (such as the Inuit who live in Greenland now), and is also unrelated to the immediate ancestors of today's Eskimos, the so-called Neo-Eskimos, who moved across the Arctic Circle from Asia beginning about 1000 years ago (we have some partial mtDNA sequences from Neo-Eskimos taken from other excavations in the Arctic.)

If the findings can be confirmed from ancient DNA from other Paleo-Eskimos (and the research team, led by Eske Willerslev of the University of Copenhagen, is hoping to do just that) it would mean that the very first Eskimos did not derive from the Asian populations that gave rise to the first Americans more than 13,000 years ago, nor were they the ancestors of today's Eskimos. Rather, the DNA evidence suggests that they were an entirely separate group whose ancestors lived in the Bering Sea area. The researchers come to this conclusion because the mtDNA from the hair contains a genetic marker very similar to that found today in small groups that live in the Bering Sea area, such as the Aleuts and a group of Siberian Eskimos.

If that all sounds complicated, it is! But the new study might help to untangle some of the roots, as it were, of the first humans who ventured into the frozen north--even if they left no living descendants.

Photo: bigfoto.com

Update: National Public Radio's site has an interview with the paper's lead author, Tom Gilbert, that is well worth listening to.