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Ancient babies boost Bering land bridge layover with DNA linking many Native Americans to infants in Alaskan grave.

By Lee Siegel

Long ago, in what is now central Alaska, a 6- to 12-week-old baby and 30-week fetus died and were buried together along with a cutting stone and some spear points made with antlers.

Now, 11,500 years later, U anthropologists and geneticists analyzed the infant’s maternal DNA and found they not only had different mothers, but belonged to two different Native American lineages, each of which has modern and ancient relatives farther south throughout North and South America.

The babies’ bones are the oldest human remains in far northern North America, and their genetic diversity lends support to what is known as the “Beringian standstill model.” That theory says Native Americans descended from people who migrated from Asia to Beringia – the vast Bering land bridge that once linked Siberia and Alaska – and then spent up to 10,000 years in Beringia before moving rapidly into the Americas beginning at least 15,000 years ago.

Finding two Native American lineages in the infants only a few thousand years after the migration south began indicates those lineages already were present before the migration started. That bolsters the notion that native ancestors spent enough time on the land bridge to diversify.

Justin Tackney and Dennis ORourke

Justin Tackney and Dennis O’Rourke

Discovery of the infants’ remains at the Upward Sun River excavation site southeast of Fairbanks was announced in 2014 in the journal Proceedings of the National Academy of Sciences by a team led by Ben Potter of University of Alaska Fairbanks. The new study, published in the same journal Oct. 26, 2015, was conducted by senior author and University of Utah anthropology professor Dennis O’Rourke, and first author and anthropology doctoral student Justin Tackney.

Other U researchers contributing to the study were senior lab specialists Michael Powers of the DNA sequencing core facility and W. Scott Watkins, in human genetics, and Derek Warner, sequencing facility director, as well as University of Kansas anthropologist Jennifer Raff, a former Utah postdoctoral fellow.

The two infants from Upward Sun River are among human remains at only eight sites in North America older than 8,000 years and from which researchers have obtained mitochondrial DNA – genetic information inherited only from mothers. The infants are the northernmost of all those remains and of the two lineages they represent.

In the eight sites, “we find all five of the major lineages of Native Americans,” Tackney says. “That indicates that all were present in the early population in Beringia that gave rise to all modern Native Americans.”

For more about the study, click here.


Lee Siegel is a senior science writer at University Marketing and Communications. If you have an interesting story idea, email him at