A recent paper by Dr. Ross and Dr. Williams, who are close friends, examines Panama and Colombia as a test case. An ancestry estimation might suggest people from both countries would have similarly shaped skulls. But population affinity acknowledges that the trans-Atlantic slave trade and colonization by Spain resulted in new communities living in Panama that changed the makeup of the country’s population. “Because of those historical events, individuals from Panama are very, very different from those from Colombia,” said Dr. Ross, who is Panamanian.
Dr. Ross even designed her own software, 3D-ID, in place of Fordisc, the most commonly used forensic software that categorizes skulls into inconsistent terms: White. Black. Hispanic. Guatemalan. Japanese.
Other anthropologists say that, for all practical purposes, their own ancestry estimations have become affinity estimations. Kate Spradley, a forensic anthropologist at Texas State University, works with the unidentified remains of migrants found near the U.S.-Mexico border. “When we reference data that uses local population groups, that’s really affinity, not ancestry,” Dr. Spradley said.
In her work, Dr. Spradley uses missing persons’ databases from multiple countries that do not always share DNA data. The bones are often weathered, fragmenting the DNA. Estimating affinity can “help to provide a preponderance of evidence,” Dr. Spradley said.
Still, Dr. DiGangi said that switching to affinity may not address racial biases in law enforcement. Until she sees evidence that bias does not preclude people from becoming identified, she says, she does not want a “checkbox” that gets at ancestry or affinity.
As of mid-October, Dr. Ross is waiting for the American Academy of Forensic Sciences Standards Board to set a vote to determine whether ancestry estimation should be replaced with population affinity. But the larger debate — over how to bridge the gap between a person’s bones and identity in real life — is far from settled.
“In 10 or 20 years, we might find a better way to do it,” Dr. Williams said. “I hope that’s the case.”