Who We Are and How We Got Here by David Reich

Author:David Reich
Language: eng
Format: epub
Publisher: Penguin Random House LLC
Published: 2018-03-27T04:00:00+00:00

Disputes over Bones

Ancient DNA studies of population history are mostly not as fraught as studies of present-day people. However, in 1990, the U.S. Congress passed the Native American Graves Protection and Repatriation Act (NAGPRA), which requires institutions that receive U.S. funding to contact Native American tribes and offer to return cultural artifacts, including bones that are from groups to which Native Americans can prove a biological or cultural connection. This has meant that Native American remains are being returned to Native American tribes and the opportunity to carry out ancient DNA analysis on many of the samples is disappearing. NAGPRA has had its greatest impact on archaeological remains dating to within the last thousand years, for which a relatively strong case can be made for cultural connections with living Native American tribes. The case for cultural connection is harder to make for very old remains, such as the approximately eighty-five-hundred-year-old Kennewick Man found on U.S. lands in Washington State in 1996.

Kennewick Man’s skeleton was initially slated for return to five Native American tribes that claimed him as an ancestor, but was made available for scientific study instead after courts found that there was no good scientific evidence that he was Native American under the rules of NAGPRA. To win their case, the scientists who challenged the tribal claims pointed to analyses of skeletal morphology that suggested that his skeleton was closer to Pacific Rim Asian and Pacific islander populations than to present-day Native Americans.18 In 2015, though, Eske Willerslev and his colleagues extracted and studied ancient DNA from Kennewick Man, which showed that these conclusions from the morphological studies were wrong.19 Kennewick Man is in fact derived from the same broad ancestral population as most other Native Americans.

Ancient DNA trumps morphological analysis whenever it is possible to compare the two types of data. The reason is simple. Morphological studies of skeletons can only examine a handful of traits that are variable among individuals, and thus can usually support only uncertain population assignment. In contrast, genetic analyses of tens of thousands of independent positions allow exact population assignment. Thus, the characterization of the ancestry of a single sample (like Kennewick Man) based on a small number of morphological traits cannot convincingly distinguish between Native American and Pacific Rim ancestry. Genetic data can.

While the ancient DNA study produced clear proof of the Native American ancestry of Kennewick Man, it was not so clear whether he bears a particularly strong relationship to the Washington State Native American populations that made claims on his remains. The paper reporting the Kennewick Man genome sampled DNA from the Colville tribe, one of the five tribes staking a claim of relationship to him, and argued that the data were consistent with a direct link. However, the Colville was the only tribe from the lower forty-eight states of the United States that the scientists analyzed, and a close look at the details of the paper provides no compelling case that Kennewick Man is more closely related to the Colville tribe than he is to Native Americans as far away as South America.

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