If extraterrestrials came to Earth to observe human death rituals, they would have trouble seeing the point: Humans dress, embalm, and bejewel their dead, only to bury them deep in the ground, where their efforts are rendered meaningless. Is Homo sapiens’ sentimentality energetically wasteful? If so, new research on chimpanzees suggests we’re not unique in that regard: In a new study, scientists report that they’ve seen chimps going so far as to clean the teeth of their dead.

Publishing in the journal Scientific Reports, researchers from the University of St. Andrews report observing the strange behavior in a group of chimps in the Chimfunshi Wildlife Orphanage Trust in Zambia. In the paper, they describe seeing a mother chimp, Noel, perching by the dead body of her adopted son, Thomas, and searching around her for an appropriate blade of grass. When she finds the right stalk, she uses it as a tool to remove gunk from her dead son’s teeth, as a dental hygienist would to a patient. This is, as far as chimp death rites go, very involved, suggesting that these animals feel something akin to empathy for their peers.

“The report is important because it indicates once more that the human species is not the only one capable of compassion,” Edwin van Leeuwen, who led the study, told New Scientist. Is this definitive proof of a chimp death ritual?

Noel (right) practiced cadaver dentistry on her dead adopted son, Thomas.
Noel (right) practiced cadaver dentistry on her dead adopted son, Thomas.

While Noel’s tooth cleaning shows surprisingly intimate behavior between the living and the dead, chimp mortuary rites have been observed in the past. In 2011, researchers publishing in the American Journal of Primatology reported watching a female chimp carry around the body of her dead four-month-old baby well after the death occurred, hypothesizing that her behavior might constitute part of a grieving process. Other animals have been thought to “grieve” as well; scientists have reported elephants visiting the corpses of individuals they are not related to and dolphins swatting away predators from a newly deceased relative. Even crows are thought to hold funerals for their dead.

But while these behaviors may seem like concrete proof that animals grieve, we can’t conclusively say they are doing so. It’s totally valid to see these behaviors as forms of mourning, but there are other ways to interpret them. When a mother chimp picks at the teeth of her dead son, for example, it could very well be that she is simply puzzled that he is no longer responsive. Or, perhaps “grieving” animals are actually being selfish: Researchers have determined that crows that appear to congregate around a dead body do so in order to learn what killed it in the first place so they can avoid it in the future.

Still, there’s at least one thing definitely linking our behavior with that of our hairy cousins: The observations show that chimps are definitely intrigued by death. In the paper, the researchers write that their strange corpse dentistry may have “emerged from a motivation to learn about death, perhaps fuelled by a curiosity about the unique circumstances.” We may not pick at the teeth of our dead, but we certainly poke and prod at them in medical settings, hoping not only to understand what death means but how we might prevent it from happening altogether.

Photos via Scientific Reports/Edwin J. C. van Leeuwen et al.