Law enforcement officials are trying to ascertain the owner of a jawbone that washed up on a beach in Aruba last November. They've ruled out missing Alabama teenager Natalee Holloway. Now they're considering Amy Bradley, who disappeared 12 years ago on a Caribbean cruise. The DNA is too damaged to be useful, but investigators say the bone likely belonged to a C aucasian woman. In the absence of DNA, can you really determine race from a jawbone?
Probably not. Forensic anthropologists try to infer the ancestry, gender, and age of human remains by measuring their dimensions and observing their features with the naked eye. The jawbone is one of the more useful bones in the body, as researchers have compiled a number of mandibular traits (PDF) that they think differ slightly between races. For example, if you place an Asian jawbone on a table, the bottom of it will likely maintain contact with the tabletop all the way around. African and Caucasian mandibles, in contrast, tend to undulate, or rise and fall along the lower border. The gonia—that's the area beneath your ears where the jawbone turns upward—generally curve more sharply in an Asian jaw. People of African descent often have slightly curled surfaces on the rear edges of their jaws, whereas European jaws are more likely to have a flatter edge. (Take a look at this picture.) But all of these traits are imprecise indicators. It's impossible to identify a person's ancestry definitively from a single bone.
