Rare Bones and DNA of tiny children surprise scientists, support ideas about migration into the Americas 11,000 years ago
The small bodies of infants buried in an ancient campsite in the wilds of Alaska have given researchers a surprising and unprecedented look into the lives of prehistoric peoples and the ancient lineages of Native Americans. These rare bones are said to be the earliest human remains found in northern North America.
Archaeologists uncovered the skeletons of the two infants in 2013 at the Upper Sun River archaeological site in the Tanana River Basin of central Alaska, USA. It was found that one child (six- to 12-week-old baby) had died shortly after birth, and the other was a stillborn (preterm 30-week fetus). Most unexpected of all was the discovery this year that the two babies had different mothers and grandmothers. (Before their ages was determined it was believed the infants were twins). Radiocarbon dating showed the pair were buried approximately 11,500 years ago, reports the journal Science.
Not only are the remains the earliest in northern North America, they’re also the source of the first ancient DNA discovered in Beringia— the ancient region of the Bering Strait and Sea, when the Bering Land Bridge linked Asia and North America at various times during ice ages.
Beringia Migration and the Standstill Model
The study has been published in the journal Proceedings of the National Academy of Sciences (PNAS).
Archaeologists in Alaska found the remains of tiny prehistoric children, the earliest of northern North America. Credit: Ben Potter, University of Alaska at Fairbanks
Study co-author and doctoral candidate in anthropology at the University of Utah , Justin Tackney said that the genetic lines of the babies suggest to scientists that all Native Americans might trace their lineage to a single wave of migrants who crossed the Bering Strait, reports LiveScience.
This might support the “Beringian standstill model”, which theorizes that Native Americans are descendants of those early people who made their way from Siberia to Beringia via the massive land bridge approximately 25,000 to 30,000 years ago. They may have stayed and thrived in that northern location that was mostly tundra and shrubs for up to 10,000 years until a warming trend melted glaciers and raised sea levels, submerging their territory. Blocked by glaciers from going east, they moved quickly south into the Americas at least 15,000 years ago.
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The Beringia Land Bridge is thought to have been the route taken by the prehistoric ancestors of Native Americans. ( CC BY-SA 3.0 )
It is still not proven with certainty if this was done in multiple waves, or in one single migration. Many of the sites that were once ancient Beringia may hold the answers, but now remain submerged under water.
Artifacts from these ancient settlers, who have been named the Clovis culture after one of the archaeological sites in Clovis, New Mexico, have been found from Canada to the edges of North America. However, a number of discoveries in recent years have challenged the view that the Clovis were the first, and until now, no archaeological evidence of human settlements had ever been found in the Beringian land bridge.
In addition, some archaeologists and Native Americans take exception to the predominant theory that all people first came to the Americas via the land bridge.
Ancient DNA Reveals Surprising Genetic Diversity
According to The New York Times , scientists focused on recovering mitochondrial DNA from the bone samples. The results surprised researchers, as the DNA showed the infant and the fetus did not share a mother or even a maternal grandmother.
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The children came from genetically distinct population groups and were “the northernmost known kin to two lineages of Native Americans found farther south throughout North and South America,” notes Phys.org.
According to the study, one baby had a haplogroup of C1b, and the other had a B2 lineage. Both of these markers are found in modern Native Americans, however the B2 lineage has never been seen in modern northern Siberians or high-latitude Native North Americans. This led some researches to propose a secondary migration brought the B2 lineage. But the new findings are said to lay that theory to rest.
Connie Mulligan, genetics professor at the University of Florida told LiveScience that the new results in Alaska “really solidifies the argument for a single migration by showing that all major New World mitochondrial haplogroups can be found in ancient populations in the New World at the right time and in the right place.”