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 Scientists said on Wednesday a study of her genome indicated
there was just a single wave of migration into the Americas
across a land bridge, now submerged, that spanned the Bering
Strait and connected Siberia to Alaska during the Ice Age.
The infant -- named "sunrise girl-child" (Xach'itee'aanenh
T'eede Gaay) using the local indigenous language -- belonged to
a previously unknown Native American population that descended
from those intrepid migrants, the researchers added.
"The study provides the first direct genomic evidence that all
Native American ancestry can be traced back to the same source
population during the last Ice Age," University of Alaska
Fairbanks archaeologist Ben Potter said.
The remains of the infant -- part of a hunter-gatherer culture
that hunted bison, elk, hare, squirrels and birds and caught
salmon -- were unearthed in 2013 at a prehistoric encampment in
Alaska's Tanana River Valley about 50 miles (80 km) southeast of
Fairbanks.
Our species first arose in Africa roughly 300,000 years ago, and
later spread around the world. The researchers studied the
baby's genome and genetic data covering other populations to
unravel how and when the Americas were first populated.
A single ancestral Native American group split from East Asians
about 36,000 year ago and thousands of years later crossed the
land bridge, they said. This founding group diverged into two
lineages about 20,000 years ago.
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The first lineage trekked south of the huge ice caps that covered
much of North America between 20,000 and 15,000 years ago, spreading
throughout North and South America and becoming the ancestors of
today's Native Americans.
The second was the newly identified population called Ancient
Beringians who included the infant. They eventually disappeared,
perhaps absorbed into another population that later inhabited
Alaska.
Some scientists previously hypothesized about multiple migratory
waves over the land bridge as recent as 14,000 years ago.
The girl was found alongside remains of an even-younger female
infant, possibly a first cousin, whose genome the researchers could
not sequence. Both were covered in red ochre and surrounded by
decorated antler tools.
"Even the one that got sequenced was a huge challenge due to poor
DNA preservation," said Eske Willerslev, director of the University
of Copenhagen's Centre for GeoGenetics.
The research was published in the journal Nature.
(Reporting by Will Dunham; Editing by Sandra Maler)
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