The remains of an ancient infant are shedding new light on the first humans to come to North America, scientists say, and may be able to confirm the dominant theory that all Native Americans are descended from a single ancestral group that migrated from Siberia long ago.
The skeleton, discovered in 2013 at the Upward Sun River archaeological site in Alaska, belonged to a girl who died at about six weeks of age. At 11,500 years old, they are “the oldest human remains ever found in Alaska,” according to Professor Eske Willerslev, whose team published their findings in the journal Nature.
She has been dubbed USR1 by researchers, though the local indigenous population has given her the more poetic name of Xach’itee’aanenh t’eede gay, or “Sunrise Girl.”
According to Willerslev, DNA testing of the girl shows that she is distantly related to modern Native Americans, but still genetically distinct. “So, you can say she comes from the earliest, or most original, Native American group—the first Native American group that diversified.”
Scientists believe that the ancestors of modern Native Americans began to genetically diverge from East Asians about 34,000 years ago, and completed the process by 25,000 years ago, either because they had already crossed the Bering Strait into North America or were at least isolated in Siberia.
About 20,000 years ago, however, the ancient Siberians-turned-Alaskans began to genetically diverge into two separate groups, as one segment (represented by Sunrise Girl) stayed in Alaska while others began to migrate to other parts of the continent. Eventually these formed the two genetic groups which became ancestors to all other Native Americans.
According to this theory, then, there was only one group which migrated from Siberia, which then branched off into the forebears of all indigenous peoples of North and South America.
Trying to find out more about this process has been difficult, according to Willershev, due to a lack of material to study; the Northeastern American soil is acidic and thus proves bad for preserving skeletons, and is especially hard on DNA. Generally researchers have had to compare ancient Siberian remains to the DNA of more recent Native Americans, which leaves a rather large gap.
Thanks to Sunrise Girl, however, they now have a genome that provides a link between the two. Researchers are hoping to find more such remains at some point in the future.
