Favorite Things Redux: Beringian DNA

Map of gene-flow in and out of Beringia, from 25,000 years ago to present

Scientists have long believed that the first humans made it to the Americas by crossing from now-Russia to now-Alaska. When and how they did it–by boat or by foot–remain matters of contentious debate. Did people move quickly through Alaska and into the rest of North America, or did they hover–as the “Bering standstill” hypothesis suggests–in Beringia (or the Aleutian Islands) for thousands of years?

Archaeologists working at the Upward Sun River site (approximately in the middle of Alaska) recently uncovered the burials of three children: a cremated three year old, and beneath it, a 6-12 week old infant and a 30 week, possibly premature or stillborn fetus. The three year old has been dubbed “Upward Sun River Mouth Child,” and the 6 week old “Sun-Rise Girl Child.” Since these aren’t really names, I’m going to dub them Sunny (3 yrs old), Rosy (6 weeks), and Hope (fetus).

They died around 11,500 years ago, making them the oldest burials so far from northern North America. Rosy and Hope were probably girls; cremation rendered Sunny’s gender a mystery. Rosy and Hope were covered in red ocher and buried together, accompanied by four decorated antler rods, two dart points and two stone axes. (Here’s an illustration of their burial.) The site where the children were buried was abandoned soon after Sunny’s death–perhaps their parents were too sad to stay, or perhaps the location was just too harsh.

Rosy and Hope were well enough preserved to yield DNA.

Surprisingly, they weren’t sisters. Rosy’s mother’s mtDNA hailed from haplogroup C1b, which is found only in the Americas (though its ancestral clade, haplogroup C, is found throughout Siberia.) Hope’s mtDNA is from haplogroup B2, which is also only found in the Americas. Oddly, B2’s parent clade, (B), isn’t common in Siberia–it’s much more common in places like Vietnam, Laos, the Philippines, and Saipan. It’s not entirely absent from Siberia, but it got to Alaska without leaving a larger trail remains a mystery.

Since they are found in the Americans but not Asia, we know these lineages most likely evolved over here; the main questions are when and where. If the Bering Standstill hypothesis is correct and the Indians spent 10-20,000 years stranded in Beringia, they would have had plenty of time to evolve new lineages while still in Alaska. By contrast, if they crossed relatively quickly and then dispersed, these new lineages would have had much less time to emerge, and we would expect them to show up as people moved south.

Source: Ancient Beringians: A Discovery Changing Early Native American Hisotry

Or there could have been multiple migration waves, with different haplogroups arriving in different waves. (There were multiple migration waves, but the others occurred well after Sunny and the others were buried.)

In fact, there are five mtDNA lineages found only in the Americas (A2, B2, C1, D1, and X2a.) With Hope and Rosy, we have now identified all five mtDNA lineages in North American burials over 8,000 years old, lending support to the Beringian Standstill hypothesis.

But were the Upward Sun River children’s families ancestral to today’s Native Americans? Not quite.

It looks like Sunny’s tribe split off from the rest of the Beringians (or perhaps the others split off from them) around 22-18,000 years ago. Most of the others headed south, while Sunny’s people stayed in Alaska and disappeared (perhaps because all of their children died.) So Sunny’s tribe was less “grandparent” to today’s Indians and more “great aunt and uncle,” but they still hailed from the same, even older ancestors who first set out from Siberia.

I have previously favored the Aleutian or at least a much more rapid Beringian route, but it looks like I was wrong. I find the idea of the Bering Standstill difficult to believe, but that may just be my own biases. Perhaps people really did get stuck there for thousands of years, waiting for the ice to clear. What amazing people they must have been to survive for so long in so harsh an environment.