First Americans Arrived on 2 Separate Paths
THURSDAY Jan. 8, 2009 -- Genetic evidence suggests that two different waves of people migrated from what is now Siberia at about the same time to become the first settlers in the Americas, a new report says.
Approximately 15,000 to 17,000 years ago, one group of people came to North America via the Beringia landmass, which once connected northeast Siberia to Alaska, and moved down the Pacific coastline, according to findings published online in the Jan. 8 issue of Current Biology. About the same time, another group of people used the Beringia bridge and entered the eastern Rocky Mountain region after crossing an open land corridor between two ice sheets.
These conclusions come from Italian researchers at Universit#224; di Pavia who studied mitochondria DNA from two rare haplogroups, which are subgroups that share a common maternal ancestor. The study found that people with the D4h3 haplogroup spread from Beringia, down the Pacific coast and all the way to Tierra del Fuego in Argentina. The second group of migrants, the X2a haplogroup, came down the ice-free section of North America and stayed on the continent. The two groups combined to become the Paleo-Indians -- the first Americans, according to the researchers.
"Recent data based on archeological evidence and environmental records suggest that humans entered the Americas from Beringia as early as 15,000 years ago, and the dispersal occurred along the deglaciated Pacific coastline," researcher Antonio Torroni said in a news release issued by the journal's publisher. "Our study now reveals a novel alternative scenario."
If the first Americans came from more than one place, it could help explain the wide linguistic and cultural diversity of native Americans, the researchers said.
The U.S. National Library of Medicine has more about mitochondrial DNA.
Posted: January 2009