Native Americans actually came from Siberia
Dr Schurr's team checked Altai DNA samples for markers in mitochondrial DNA which is always passed on by mothers, and Y chromosome DNA which sons inherit from their fathers. Because of the large number of gene markers examined, the findings have a high degree of precision.
'At this level of resolution we can see the connections more clearly,' Schurr said. Looking at the Y chromosome DNA, the researchers found a unique mutation shared by Native Americans and southern Altaians in the lineage known as Q. Mitochondrial DNA is found in tiny rod-like 'powerplants' in cells that generate energy. Both kinds of DNA showed links between Altaians and Native Americans.
In the Y chromosome DNA, the researchers found a unique mutation shared by Native Americans and people from southern Altai.
The findings are published today in the American Journal of Human Genetics. Calculating how long the mutations they noted took to arise, Schurr's team estimated that the southern Altaian lineage diverged genetically from the Native American lineage 13,000 to 14,000 years ago, a timing scenario that aligns with the idea of people moving into the Americas from Siberia between 15,000 and 20,000 years ago.
Though it's possible, even likely, that more than one wave of people crossed the land bridge, Schurr said that other researchers have not yet been able to identify another similar geographic focal point from which Native Americans can trace their heritage. 'It may change with more data from other groups, but, so far, even with intensive work in Mongolia, they're not seeing the same things that we are,' he said.
In addition to elucidating the Asia-America connection, the study confirms that the modern cultural divide between southern and northern Altaians has ancient genetic roots.