Native Americans Descend From Ancient Montana Boy

Source - http://news.sciencemag.org/archaeology/2014/02/native-americans-descend-ancient-montana-boy

Clovis cache. The child's skull was found in Montana with a host of Clovis tools. Samuel Stockton White

In 1968, when Sarah Anzick was 2 years old, a construction worker discovered more than 100 stone and bone tools on her family’s land near Wilsall, Montana. The artifacts were blanketed with red ochre, and with them, also covered with ochre, was the skull of a young child. In the years since, archaeologists concluded that the skull was about 12,700 years old—the oldest known burial in North America—and that the tools belonged to the Clovis culture, one of the first in the New World. Meanwhile, Sarah Anzick grew up, became a genome researcher at the National Institutes of Health (NIH), and dreamed of sequencing the rare bones.

This week, she is the second author on a paper in Nature that reports the complete sequence of the Anzick child’s nuclear genome. The sequencing effort, led by ancient DNA experts Eske Willerslev and Morten Rasmussen of the University of Copenhagen, comes to a dramatic conclusion: The 1- to 2-year-old Clovis child, now known to be a boy, is directly ancestral to today’s native peoples from Central and South America. “Their data are very convincing … that the Clovis Anzick child was part of the population that gave rise to North, Central, and Southern American groups,” says geneticist Connie Mulligan of the University of Florida in Gainesville.

If correct, the findings refute the Solutrean hypothesis, which postulates that ancient migrants from Western Europe founded the Clovis culture. The data also undermine contentions that today’s Native Americans descend from later migrants to the Americas, rather than from the earlier Paleoindians. And that could help tribes that want to claim and rebury ancient American skeletons such as that of the 9400-year-old Kennewick Man from Washington state. “This is proof that Kennewick Man was Native American,” says archaeologist Dennis Jenkins of the University of Oregon, Eugene. Sarah Anzick, whose family is in possession of the infant, says that it is likely to be reburied in May.

Researchers have long wanted to examine the DNA of the first Americans for clues to their origins. But even after scientists developed tools to get DNA from poorly preserved bones, they lacked the full cooperation of today’s Native Americans. The Anzick child remained available for study in part because it was found on private land, so the U.S. Native American Graves Protection and Repatriation Act (NAGPRA)—which gives native peoples the right to claim and rebury many human remains—does not apply.

Willerslev and colleagues extracted DNA from bone fragments taken from the child’s skull and one of its ribs, then sequenced the genome. They compared the genome with those of 143 modern non-African populations, including 52 Native American ones, in a database compiled over several decades by geneticist David Reich of Harvard Medical School and others. The database includes 45 DNA samples from Central and South America and seven from Canada and the Arctic, but none from the lower 48 states, in part because U.S.-based Native American groups have historically resisted providing DNA samples, and because Reich felt that true informed consent was lacking for some samples.

Despite the North American data gap, the team was able to determine that the Anzick genome was much more closely related to Native Americans than to any other group worldwide. The child’s DNA more closely resembles that of Central and South Americans than Native Americans from the far north, although the relationship is still very close, Willerslev says. Comparing the Anzick genome with that of a 24,000-year-old Siberian boy and a 4000-year-old Paleo-Eskimo from Greenland confirms that Native Americans originally come from Northeast Asia.

How to explain the north-south difference? The team concludes that the most likely scenario is that an ancestral population that lived several thousand years before the Clovis period split into two groups, one staying north and one going south. Just where and when this split happened cannot be determined from the genetic data, Willerslev and Rasmussen say. The northerners then likely mated with peoples who came in later from Asia, and so became slightly more genetically distant from Anzick.

The study “is a real technical and analytical achievement,” says anthropologist Theodore Schurr of the University of Pennsylvania, who was not a co-author. It “effectively puts the Solutrean hypothesis to rest,” he says. But advocates of that idea take umbrage at such a dismissal. “This is a single individual and can in no way represent all that was happening,” says archaeologist Bruce Bradley of the University of Exeter in the United Kingdom.

Schurr cautions that the lack of U.S.-based Native American genomes could have biased the analysis of how closely related the Anzick boy is to today’s native peoples. “The authors might want to be more cautious about making such definitive statements” about the Clovis culture’s ancestral status “without having … a much broader sampling of North American Indian populations,” he says.

Members of the team say they hope to get more U.S. data. “We hope the continued dialogue with local populations and studies like this will entice … Native peoples to participate in genetic studies,” Rasmussen says. Shane Doyle, a professor of Native American studies at Montana State University, Bozeman, and a member of the Crow tribe, shares that hope. Doyle is coordinating negotiations about reburying the child with the Anzick family, the researchers, and members of 11 local tribal groups, but he sees the value of such research for today’s Native Americans. “This is absolutely going to change the game about how we think about Paleoindians and their links to modern-day tribes,” Doyle says.

Both Doyle and Anzick (who notes that she is acting for her family, not NIH) say they are agonizing over how, and how soon, the child should be reburied. They worry that reburial will destroy data that might be retrieved years from now with better genetic techniques continue to improve. Schurr agrees: “This is why scientists are fighting against NAGPRA repatriations of Paleoamerican remains, as much can be learned from these ancient samples.”

But Doyle and Anzick insist that the child should be reburied out of respect for his Native American descendants. “The boy has given us an amazing gift,” Doyle says. “Now we must repay that by putting him back where he belongs.”