New Study Reveals Why Primates Continue to Carry Offspring After Death

Humans have long been fascinated by the way animals act in the wild. There are countless shows and films documenting their behaviors for everything from mealtime to caring for their young.

In primates, which include not only humans themselves but some of the closest relatives to humans in the animal kingdom, there are often notable similarities between us and them. Though there is one ritual that scientists have been keeping an eye on for decades.

In what has been observed now hundreds of times since 1915, many species of primates—though particularly common among large apes and Old-World monkeys—have been found to not only interact with but sometimes even carry their young for days on end after they have died, according to Live Science.

A recent study published in the Proceedings of the Royal Society B: Biological Sciences on September 15 looked at over 400 cases of mothers interacting with their infants after death creating the most extensive study of its kind to date.

Family of Baboons
A new study looked at a range of primates who showed various responses to death, some including infant corpse carrying. Here, a family of Chacma baboons, is photographed in Kruger National Park, South Africa. EcoPic/Getty Images

According to Live Science, the study, which was led by a team out of University College London, analyzed reports dating from 1915 to 2020 of monkeys, apes, bushbabies and lemurs that tended to their young after they had died. From that analysis, they found that roughly 80 percent of the species they reviewed performed "corpse-carrying behavior."

"Our study indicates that primates may be able to learn about death in similar ways to humans: it might take experience to understand that death results in a long-lasting 'cessation of function,' which is one of the concepts of death that humans have," said co-author Alecia Carter in an article from UCL.

"Our study also has implications for what we know about how grief is processed among non-human primates," Carter continued in the statement. "It's known that human mothers who experience a stillbirth and are able to hold their baby are less likely to experience severe depression, as they have an opportunity to express their bond. Some primate mothers may also need the same time to deal with their loss, showing how strong and important maternal bonds are for primates, and mammals more generally."

The study found that in those mothers that did carry their young after death, the length of time they hung on depended on the time of death and how strong the bond between mother and child was. Another factor was how the infant died, if it was less traumatic, like an illness, the behavior was more common.

"Because of our shared evolutionary history, human social bonds are similar in many ways to those of non-human primates," said Elisa Fernández Fueyo, another co-author of the study in an article from UCL. "Therefore, it is likely that human mortuary practices and grief have their origins in social bonds."