DNA from two babies that were buried at an Alaskan campsite 11,500 years ago revealed them to be the northernmost relatives to two lineages of modern Native Americans in North and South America.
The new findings support the "Beringian standstill model," which suggests Native Americans descended from people who migrated from Asia to Beringia (the land bridge that once linked Siberia and Alaska) and spent about 1,000 years there before moving down the Americas about 15,000 years ago, the University of Utah reported.
"These infants are the earliest human remains in northern North America, and they carry distinctly Native American lineages," said University of Utah anthropology professor Dennis O'Rourke, senior author of the paper set for online publication the week of Oct. 26 in the journal Proceedings of the National Academy of Sciences. "We see diversity that is not present in modern Native American populations of the north and we see it at a fairly early date. This is evidence there was substantial genetic variation in the Beringian population before any of them moved south."
Some theories have suggested the two Native Americans lineages evolved when the people moves south, and not while they were still living in Beringia. The evidence from these newly discovered infants from a period only a few thousand years after the migration suggests the lineages already existed before the migration began.
"It supports the Beringian standstill theory in that if they [the infants] represent a population that descended from the earlier Beringian population, it helps confirm the extent of genetic diversity in that source population," 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."
Across the eight sites looked at in the study, the researchers found all five of the major lineages of Native Americans. This means these lineages existed were present in the early population in Beringia that led to the birth of all modern-day Native Americans.
