Not three thousand years.

Not thirteen thousand years.

Thirty-one thousand years before the present day, at a time when most of northern Europe was buried under kilometers of glacial ice, when the English Channel did not exist, when most of what is now the United States was still being sculpted by glaciers, when anatomically modern humans had only recently spread through Europe and were still in the process of replacing or absorbing the last Neanderthals — at that extraordinarily distant moment in time, two children were alive above the Arctic Circle in Siberia.

They were part of a community.

They played, presumably.

They shed their milk teeth.

And when researchers extracted DNA from those tiny preserved teeth in 2019, the genetic code inside them revealed something that nobody expected.

These children belonged to a population that had never been identified before.

A group of humans so distinct, so genetically different from any other ancient population that scientists had studied, that they represented an entirely new branch of the human family tree from this period.

The team who sequenced their genomes named them the Ancient North Siberians.

And then the story got stranger still.

Because the Ancient North Siberians — these people who lived and died in the deep frozen far north of the Pleistocene world — turned out to be part of the story of how the Americas were first settled.

Their genetic signature appears in the ancestry of the populations that would eventually cross into the New World and give rise to the Indigenous peoples of North and South America.

Two milk teeth from Ice Age children in one of the most forbidding places on Earth.