Primate mothers grieve by carrying their infants after death

A new study published in the journal Proceedings of the Royal Society B has revealed that some primate species express grief over the death of their infants by carrying the corpse with them, sometimes even for months. This study shows that primates may posses an awareness of the phenomenon of death, or at least be able to learn about death over time.

Researchers from University College London (UCL) compiled data from anecdotes about primate behavior from 126 publications. In one of the most extensive and rigorous quantitative analyses to date, they identified the behavior of “infant corpse carrying” in primate mothers in 409 cases across 50 species. 

“Our study indicates that primates may be able to learn about death in similar ways to humans,” explained study co-author Dr. Alecia Carter from the Anthropology department at UCL. “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. What we don’t know, and maybe will never know, is whether primates can understand that death is universal, that all animals – including themselves – will die.”

The scientists found that almost 80 percent of the species in the study performed corpse carrying behavior. Most of the great apes and Old World monkeys carried their infants’ corpses after death. Some primate species that evolutionarily diverged long ago, such as lemurs, did not carry the corpses. However, they were still found to express grief through other types of behavior, such as returning to the corpse or giving mother-infant contact calls.

This study can also shed more light on how non-human primates are processing grief. “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,” said Dr. Carter. “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.”

According to co-author Elisa Fernández Fueyo, mothers that were more strongly bonded to their infants carried their corpses for longer. “Because of our shared evolutionary history, human social bonds are similar in many ways to those of non-human primates. Therefore, it is likely that human mortuary practices and grief have their origins in social bonds,” she concluded.

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By Andrei Ionescu, Earth.com Staff Writer