December 1, 2012
New Genetic Links Found Between Native Americans And Northern Europeans
April Flowers for redOrbit.com — Your Universe Online
Northern European populations - including British, Scandinavians, French and some Eastern Europeans - descend from a mixture of two very different ancestral populations a new study finds, and one of these populations is related to Native Americans. The results of this study, published in the November issue of the Genetics Society of America's journal GENETICS, help fill in the gaps in scientific understanding of both Native American and Northern European ancestry, while providing an explanation for some genetic similarities among what would otherwise seem to be very divergent groups.
Nick Patterson, of the Broad Institute, says, "There is a genetic link between the paleolithic population of Europe and modern Native Americans. The evidence is that the population that crossed the Bering Strait from Siberia into the Americas more than 15,000 years ago was likely related to the ancient population of Europe."
The Bering Strait is a current day channel of water linking the Arctic Ocean and the Bering Sea. This channel separates the continents of Asian and North America by a margin of only 53 miles at its narrowest point. Scientists believe that some 20,000 to 25,000 years ago - during the late Pleistocene - massive continental glaciers formed in the northern hemisphere, locking up so much water that the world's oceans were more than 300 feet lower than current day levels. This exposed an unglaciated tract known as the Bering Land Bridge, connecting Northeastern Siberia with Alaska, and allowing for migrations of animals and hominins from Asia to North America. Current theories hold that this land bridge was open until as recently as 11,000 years ago.
Patterson and his colleagues, including Harvard Medical School Professor of Genetics David Reich, studied DNA diversity, finding that one of these ancestral populations was the first farming population of Europe. The DNA of this group lives on today in relatively unmixed form in Sardinians and the people of the Basque Country. It is also present in at least the Druze population of the Middle East.
The second ancestral population is likely to have been the hunter-gathering population of Europe, which today appears to have its closest affinity to people in far Northeastern Siberia and Native Americans. When they met, these two populations were very different.
Patterson developed the statistical tools for analyzing population mixture, which were presented in a systematic way in the GENETICS paper. Patterson has used these tools in previous studies, which showed that Indian populations are mixed between two highly diverged ancestral populations and that Neanderthals contributed one to four percent of the ancestry of present-day Europeans.
The current study also releases a major dataset that characterizes genetic diversity in 934 samples from 53 diverse global populations.
"The human genome holds numerous secrets. Not only does it unlock important clues to cure human disease, it also reveal clues to our prehistoric past," said Mark Johnston, Editor-in-Chief of the journal GENETICS. "This relationship between humans separated by the Atlantic Ocean reveals surprising features of the migration patterns of our ancestors, and reinforces the truth that all humans are closely related."