Global Analysis of Human DNA Tracks Migration, Identity

By Steven Reinberg
HealthDay Reporter
Thursday, February 21, 2008; 3:00 PM

Copyright © 2008 ScoutNews, LLC. All rights reserved.

THURSDAY, Feb. 21 (HealthDay News) -- In the largest such examination of human genetic diversity yet conducted, an international team of geneticists has used clues in DNA to track differences and similarities between people around the globe.

Reporting in the Feb. 22 issue of Science, a team led by Richard Myers, of Stanford University, looked at more than 650,000 variants in individual genes, called single-nucleotide polymorphisms (SNPs) found in 938 unrelated volunteers in countries around the world.

Among other findings, the new data support the notion that "a small group of individuals migrated out of eastern Africa and their descendants subsequently expanded into most of today's populations," the researchers wrote.

That expansion occurred mainly over the past 100,000 years, the team says. Using high-tech DNA analysis of the SNPs, they were able to determine the distinct genetic identities of eight European groups of modern humans, as well as four in the Middle East. They also believe that shared genes found among Native Americans and certain groups in Russia "reflects shared ancestry before the predecessors of the Native Americans crossed the Bering Strait."

The report in Science follows on the heels of similar international efforts by other researchers, reported in two studies published in the Feb. 21 issue of Nature.

Noah Rosenberg, co-senior author of one of two Nature studies, explained that his group has "investigated genetic similarities of populations across a very large number of sites in the human genome. We found that it's possible, with a high degree of accuracy, [to tell] which continent, in which population, the individual comes from."

In addition, the primary determinant of genetic similarities and differences seems to be geographic location, said Rosenberg, who is an assistant professor of human genetics at the University of Michigan. "The closer populations are, the greater the degree of similarity between the populations," he noted.

Rosenberg's team also found that the number of distinct genetic variants declined as the distance from Africa increased. "This suggests that a genetic history reflects a history in which populations migrated out of Africa, and along the way only a portion of the genetic diversity available migrated to the next location," he said.