On July 5, President Donald Trump said he would give a million dollars to the favourite charity of Democratic US Senator Elizabeth Warren “if you take the test and it shows you’re an Indian”. Warren, a persistent Trump critic and potential presidential candidate in 2020, has long claimed she has Native American ancestry. The President has alleged she is lying, and repeatedly mocked her as “Pocahontas”, a possibly racist reference to the nickname of a teenage Native American girl who was abducted by English colonists in 1613, and died aged about 21. Warren on Monday released analysis of her DNA that suggested she had a Native American ancestor 6-10 generations back. Trump then denied having offered the $1 million bet, and said, “who cares?”
Political pointmaking aside, what do the results of such genetic testing really prove — or don’t? How does testing work? Does a genetic match automatically imply cultural kinship? Is a Native American ancestry of the kind Warren has, an unusual genetic attribute in America today?
The ancestry test
Warren provided her DNA to a private lab in Georgia in August, and the raw results data were analysed by the well regarded Stanford geneticist Carlos Bustamante, who concluded that she was between 1/1024th and 1/32nd Native American, reported The Boston Globe, which first saw the analysis.
Warren’s DNA was analysed by genotyping, which is a process of determining which genetic variants an individual possesses. (Genotyping is different from sequencing which determines the exact sequence of a certain length of DNA.) The human genome has over 3 billion base pairs, and Dr Bustamante was able to study 7,64,958 bases of Warren’s DNA. He compared her DNA to that of 148 individuals from the Americas, Europe, Africa and Asia, and was able to assign 95% to European ancestors. But five short pieces of DNA (the biggest of which was 4.7 million bases long) stood out as exceptions — they contained variants typically found in Native Americans. The small sizes of these segments indicated Warren’s Native American forebear was not a recent ancestor — rather, the ancestor lived 6-10 generations ago.
It is important to note that even the most accurate DNA ancestry test results have a range of error, and different ancestry companies that use different algorithms can produce somewhat different reports. “The approach taken by all of the commercial companies is to try to estimate the general geographic regions where your ancestors lived (and in a select small number of cases their ethnic identifiers) some indeterminate time in that past, probably something like a few hundred years ago,” a report in Vox quoted geneticist Joe Pickrell, CEO of Gencove, a firm that sells genotyping technology, as saying. And The Boston Globe report warned that “Detecting DNA for Native Americans is particularly tricky because there is an absence of Native American DNA available for comparison.”
Not about heritage
“DNA ancestry tests sort your DNA by the geographic regions you likely inherited it from — but not everything about our family histories is geographic,” said the Vox report. The tests don’t reveal the languages that the ancestors of an individual spoke, what traditions they followed, what they ate, or how they lived. A report in The New York Times said “the Senator’s genetic analysis was sound”, but whether she may “claim a cultural kinship with Native Americans is a very different question”. The report quoted University of Connecticut geneticist Deborah Bolnick as saying, “What determines tribal belonging is very much based on a person’s social connections and lived experiences. These are things not defined by the DNA in our bodies.” The Boston Globe report too, quoted scientists as cautioning that “indigenous identity and tribal membership are not determined by genetics but by longstanding cultural, familial, and historical ties to a Native American tribe.”
Not that rare either
A few years ago, geneticists at the California-based genomics and biotechnology company 23andMe studied the DNA of people who claimed European ancestry, and estimated that in as many as 5 million European-Americans, at least 1% of the genome was Native American. Dr Bustamante could not say from Warren’s DNA which tribe her ancestor belonged to; he was able only to compare her DNA to that of indigenous people in Peru and Mexico, as well as First Nations people in Canada, The NYT report said. Dr Bustamante did not study Native Americans in the US, and about their DNA relatively little is known.