Newspaper article The Christian Science Monitor

What Do Ancient Babies Reveal about Travel by Ice-Age Americans?

Newspaper article The Christian Science Monitor

What Do Ancient Babies Reveal about Travel by Ice-Age Americans?

Article excerpt

Scientist have long debated how humans originally arrived in the Americas. The prominent idea has been that a sort of land bridge formed during the last ice age and people migrated from Asia.

But people may not have just waltzed over the land bridge and spread across the Americas. Instead, they may have settled in northern Alaska for a while first.

And the newest clues come from a surprising place: babies.

Scientists have sequenced the mitochondrial DNA from two infants found buried together at an Alaskan campsite some 11,500 years ago in a paper published Monday in the journal Proceedings of the National Academy of Sciences.

That ancient DNA revealed that the little ones did not share a mother. In fact, they are related to two different lineages of Native Americans found elsewhere in the Americas.

It's that genetic diversity that supports the "Beringian standstill model" that says humans may have spent as many as 10,000 years in the area around the Bering Strait known as Beringia before spreading south through the Americas.

"These infants are the earliest human remains in northern North America, and they carry distinctly Native American lineages," study senior author and University of Utah anthropology professor Dennis O'Rourke said in a news release.

"It supports the Beringian standstill theory in that if [the infants] represent a population that descended from the earlier Beringian population, it helps confirm the extent of genetic diversity in that source population," Professor O'Rourke said. "You don't see any of these lineages that are distinctly Native American in Asia, even Siberia, so there had to be a period of isolation for these distinctive Native American lineages to have evolved away from their Asian ancestors. We believe that was in Beringia."

Some 25,000 years ago the last ice age saw low sea levels. That revealed a sort of land bridge stretching from Siberia to Alaska where the Bering Strait is today.

People would have migrated across this newly revealed land into what is present-day Alaska. According to the Beringian standstill model, these people would have had to settle where they arrived, in what is called Beringia, because any other path was blocked by gigantic glaciers. …

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