Of the hundreds of people who die trying to cross into the U.S. from Mexico each year, those with indigenous backgrounds are less likely to be identified than those with more European ancestry, a new analysis reveals.
The research, reported in the journal American Anthropologist, focused on DNA from individuals found dead in the Arizona desert and transported to the Pima County Office of the Medical Examiner in Tucson, where efforts are made to identify the individuals and return them to living relatives.
The researchers looked at highly variable regions of DNA, called short tandem repeats, that are traditionally used in forensics to identify individuals, "much like a fingerprint," said University of Illinois anthropology professor Cris Hughes, who led the new analysis.
"Forensic DNA analysis can help identify individuals by matching their genetic profiles with their family members', but my colleagues and I have shown in previous work that forensic genetic markers also can reveal information on a person's ancestral makeup," said Stanford University biology professor Bridget Albee-Hewitt, a co-author on the study.
Such DNA technologies have not always been available, but PCOME forensic anthropologists, including Bruce Anderson, a co-author on the new study, have kept samples of bones from unidentified bodies found on the border since the 1970s, making it possible for researchers to return to those cases while also working on newer ones.
The team used the DNA to analyze the ancestry of migrants who had died along the border, comparing those who had been identified with those who had not. That analysis revealed that people with more European ancestry were more likely to be identified than those with indigenous roots.
This is not the result of discrimination on the part of the investigators, Hughes said. The problem lay elsewhere - likely in the system by which authorities obtain the information they need to connect someone who died on the border with surviving family members, she said.
Once DNA is obtained from a body, matching it to a family requires that family to interact with authorities and offer up samples of their own DNA. This is where disparities begin to emerge between people from northern and southern Mexico, the researchers found.
"In Mexico, indigenous populations are concentrated in southern states, and poverty is more prevalent in the south," Hughes said. "There is a deep distrust between indigenous peoples in Mexico and their government, founded on a history of oppression by those in power.
"Interacting with U.S. and/or Mexican government institutions can be daunting for these families," Hughes said. "They may be undocumented themselves and uneasy about contact with any government agency. While most migrants experience these vulnerabilities, those with more indigenous ancestry seem even less inclined to come forward."
A possible solution to the problem involves nongovernmental organizations that can function as bridges between people searching for missing loved ones and authorities who are working to identify the dead, said University of Arizona anthropology professor Robin Reineke, a co-author on the study.
"The importance of community organizations, nongovernmental groups and intergovernmental efforts cannot be overestimated in the context of border disappearances," Reineke said. "Innovative projects, such as those done by the Colibrí Center for Human Rights or the Argentine Forensic Anthropology Team, take a humanitarian approach to the process of reporting and investigating these cases. Such efforts are critical during a time when so many families of the missing face the very same threats - poverty, racism, exclusion and violence - that caused their loved ones to migrate in the first place."
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Cris E. Hughes et al, Temporal Patterns of Mexican Migrant Genetic Ancestry: Implications for Identification, American Anthropologist (2017). DOI: 10.1111/aman.12845