Take ribs, for example. George was standing near a donor, almost completely skeletonized, whose ribs were cracked. One could assume that these broken ribs were a clue to how the person had died. But he says the bones were broken in the compound, from a vulture sitting on them. She wouldn’t have believed it herself if she hadn’t caught it all on camera. Then he pointed to a body on the plateau at the far end of the compound. That donor, he said, broke his ribs when they died. The breaks looked totally different, the fractures more irregular. That’s because, George said, the breaks occurred in living bone, not after death, when the material is more brittle. On a third body, Passalacqua pointed to a small spike in the rib. This, he said, was also a rib fracture, but which had healed while the donor was alive.
Chronic diseases and some other diseases can manifest in the bones. Tuberculosis can spread there, causing lesions. Forensic anthropologists can estimate the age of a young dead person by understanding how the skeleton changes over time. Older adults may also have distinctive markers of age, such as bone loss. But this work is difficult, and there are still many scientists who do not know it. Donors like these help them learn more.
George and Passalacqua’s job is to teach the students, along with the law enforcement officers who train there from time to time, how to learn what they can from a body. Often the first step is to find out if a bone is human. Passalacqua regularly receives text messages from local law enforcement asking about the bones they’ve found: a partial skeleton of a bear paw looks strikingly like a person’s hand.
One of the most difficult things for forensic anthropologists to do is also one of the most essential: estimate the time since death. “There are so many variables that it’s really hard to take into account,” says Passalacqua. A reputable forensic anthropologist will rarely be able to say, for example, that a body has been dead for exactly three weeks. A range of, say, one week to two months is most likely. This is not so helpful for law enforcement officers trying to solve a crime.
When I arrived, donor X was already in advanced decay, but every day this donor will teach the living people something. When there is little left in the bone, students will carefully remove the body from the BOSC and take it to the lab. The bones will be cleaned by hand and perhaps simmered to remove the last bits of tissue. They will be presented and examined. And then they will be packed, the delicate pieces placed in cloth bags and stored in the university collection, labeled in identical cardboard boxes.
But for now, donor X stays in place, slowly turning into a unique microbiome. Dense trees filter the sunlight. The vultures aren’t there that morning, so as we walk and the students silently examine a donor’s bones, the only other sounds we hear are the cries of cicadas.