Some primates may grieve dead infants by carrying their corpses with them, sometimes for months, according to a study examining mothers’ responses to death among 50 primate species.
The study, published Wednesday in Proceedings of the Royal Society B: Biological Sciences, found “infant corpse carrying” behavior among many primate species, including gorillas, chimpanzees, macaques and baboons.
While nonhuman primates respond to death in a number of ways, infant corpse carrying is among the most frequently reported, according to the study.
Scientists have been unable to determine a clear explanation for the behavior, “especially considering that it is costly and provides no benefit for them,” according to study co-author Elisa Fernandez Fueyo’s website.
Researchers at University College London compiled a database of 509 cases across 50 primate species of mothers’ responses to infant deaths. About 80% of the species studied performed infant corpse carrying behavior.
The study found that three factors influenced whether the mother would carry her dead baby. Infant corpse carry was more common if the infant died from an illness or stillbirth than if it were traumatic (predator attack, accident). Mothers who have had younger babies are more likely to carry them for longer periods of time.
Younger mothers were also more likely to carry the dead baby, according to the study. According to the study, older primates may have learned to recognize when their baby is dead. This could indicate that they are more likely to carry the dead baby.
“While there is debate among scientists around whether primates are aware of death, this new study suggests that primate mothers may possess an awareness — or be able to learn about death over time,” according to a Wednesday statement from University College London.
“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,” study co-author Alecia Carter said in the statement. We don’t know if primates understand death as universal and that all animals, including ourselves, will eventually die. This is something we may never find out. “
The study adds to existing knowledge about how non-human primates process grief and shows “how strong and important maternal bonds are for primates,” Carter said.
Despite the findings, Fueyo said more research is needed to determine how much primate behaviors resembled human grief.
“We found that bonds, particularly the mother-infant bond, possibly drive primates’ responses to death,” Fueyo said. “Because of our shared evolutionary history, human social bonds are similar in many ways to those of non-human primates”