Archive for July 16th, 2012
Some fascinating information has been published in a new paper that details a comprehensive study on the genetic makeup of North American Native populations.
As Science Daly reports, an international team studying DNA sequences found that Native descendants came from not just one, but three migrations from foreign lands.
By studying variations in Native American DNA sequences, the international team found that while most of the Native American populations arose from the first migration, two subsequent migrations also made important genetic contributions. The paper is published in the journal Nature July 11.
“For years it has been contentious whether the settlement of the Americas occurred by means of a single or multiple migrations from Siberia,” said Professor Andres Ruiz-Linares (UCL Genetics, Evolution and Environment), who coordinated the study. “But our research settles this debate: Native Americans do not stem from a single migration. Our study also begins to cast light on patterns of human dispersal within the Americas.”
The Science Daly article calls this study the “most comprehensive survey of genetic diversity in Native Americans.”
“There are at least three deep lineages in Native American populations,” said co-author David Reich, Professor of genetics at Harvard Medical School. “The Asian lineage leading to First Americans is the most anciently diverged, whereas the Asian lineages that contributed some of the DNA to Eskimo-Aleut speakers and the Na-Dene-speaking Chipewyan from Canada are more closely related to present-day East Asian populations.”
The team also found that once in the Americas, people expanded southward along a route that hugged the coast with populations splitting off along the way. After divergence, there was little gene flow among Native American groups, especially in South America.
Two striking exceptions to this simple dispersal were also discovered. First, Central American Chibchan-speakers have ancestry from both North and South America, reflecting back-migration from South America and mixture of two widely separated strands of Native ancestry. Second, the Naukan and coastal Chukchi from north-eastern Siberia carry ‘First American’ DNA. Thus, Eskimo-Aleut speakers migrated back to Asia, bringing Native American genes.