Native Americans arrived in at least three waves, finds DNA study
A genetic study of Native Americans from Greenland to Peru has found that the Western Hemisphere was populated by at least three distinct migrations from Asia.
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In the years since, genetic studies seemed to bolster the single-migration scenario, Ruiz-Linares said. But most of those studies examined very limited sets of genetic data, such as variations on the Y chromosome or in mitochondrial DNA, which contains only a dozen genes and passes virtually unchanged from mother to child.Skip to next paragraph
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The new study employed computers to scan the entire genomes of all the volunteers and look for small genetic variants known as single-nucleotide polymorphisms, or SNPs. This finer level of detail revealed more subtle differences among populations.
“This makes it possible to ask and answer questions we couldn’t even look at before,” said study co-author David Reich, a professor of genetics at the Harvard Medical School in Boston.
For instance, the analysis revealed that members of the separate migratory waves eventually mated with one another after arriving in the Americas.
Ripan Malhi, a molecular anthropologist at the University of Illinois at Urbana-Champaign who was not involved in the research, called the work “an important study” that marked “a big step forward” in using genomics to better understand the population history of Native Americans and other indigenous groups.
At the same time, he and others noted a key limitation in the research: The scientists had no samples from people living in the contiguous United States and only a few from Canada.
Deborah Bolnick, a genetic anthropologist at the University of Texas in Austin who also wasn’t involved in the research, said that more samples from North America might provide evidence for even more migratory waves. “It’s hard to tell if we’re looking at three or many more,” she said.
Ruiz-Linares, who was born in Colombia and began his population studies there in the 1990s, agreed that the samples included a disproportionate number from Central and South America because that’s where his collaborators happen to be located.
©2012 Los Angeles Times
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