Alaskan infant's DNA tells story of 'first Americans'

The 11,500-year-old remains of an infant girl from Alaska have shed new light on the peopling of the Americas. Genetic analysis of the child, allied to other data, indicates she belonged to a previously unknown, ancient group. Scientists say what they have learnt from her DNA strongly supports the idea that a single wave of migrants moved into the continent from Siberia just over 20,000 years ago.

Lower sea-levels back then would have created dry land in the Bering Strait. It would have submerged again only as northern ice sheets melted and retreated. The pioneering settlers became the ancestors of all today's Native Americans, say Prof Eske Willerslev and colleagues. His team has published its genetics assessment in the journal Nature. IllustrationImag  copyrightERIC.S.CARLSON ILLUSTRATIO Image caption. An illustration of how the Ancient Beringians at Upward Sun River might have lived. The skeleton of the six-week-old infant was unearthed at the Upward Sun River archaeological site in 2013. The local indigenous community have named her "Xach'itee'aanenh t'eede gay", or "sunrise girl-child". The science team refers to her simply as USR1. "These are the oldest human remains ever found in Alaska, but what is particularly interesting here is that this individual belonged to a population of humans that we have never seen before," explained Prof Willerslev, who is affiliated to the universities of Copenhagen and Cambridge. "It's a population that is most closely related to modern Native Americans but is still distantly related to them. So, you can say she comes from the earliest, or most original, Native American group - the first Native American group that diversified.

"And that means she can tell us about the ancestors of all Native Americans," he told BBC News.
Scientists study the history of ancient populations by analysing the mutations, or small errors, that accumulate in DNA down through the generations. These patterns, when combined with demographic modelling, make it possible to draw connections between different groups of people over time.

source; www.bbc.com