Why some primate moms carry their babies after they die

Mothers of some species of non-human primates can express their grief over the loss of a baby by carrying their babies with them for months, according to a new study.

Researchers have been divided over whether primates and other animals are aware of death and are grieving. But these new findings suggest that primates are capable of having an awareness of death.

“The field of comparative thanatology, which specifically wants to answer these questions, is relatively new. However, scientists have been speculating for some time about the consciousness of primates and other animals of death, ”study co-author Alecia Carter, a lecturer in evolutionary anthropology in the Department of Education, told Treehugger. anthropology from University College London.

“There have been suggestive studies of grief in animals too, and new advancements in neurobiology that behavioral scientists are starting to catch up with now.”

Thanatology is the scientific study of death and the psychological mechanisms used to cope with it.

For their work, the researchers studied 409 cases of maternal responses to the death of their infants in 50 species of primates. They compiled data from 126 different studies of primate behavior to analyze a behavior known as “carrying infant corpses.”

The results were published in the journal Proceedings of the Royal Society B.

Carter says she first saw the behavior years ago and it impressed her.

“I was so shocked the first time I saw a baboon carrying a dead baby over ten years ago, but I was told it was common behavior, so at the time I didn’t did not pursue further, “she said.

His research gradually turned to cognition.

“In 2017, I watched people who weren’t the mother respond to a dead baby in baboons, and it made me even more curious about mothers’ motivations after reading the literature.”

Species and age matter

The researchers found that 80% of the species studied exhibited cadaver-carrying behavior. Although the behavior was well distributed, it was more common in great apes and Old World monkeys. These species carried their children after death longer than any other.

Some species of primates that diverged long ago, such as lemurs, did not bear their babies after they died. Instead, they showed their grief in other ways, such as visiting the body and calling the infant.

Other factors have also been found to impact the likelihood that they will carry their babies after death.

“Whether or not a mother carries her baby depends on how the baby died and the mother’s age,” says Carter. “[Mothers of] infants who die from traumatic causes, such as being killed by another member of the group or in an accident, are less likely to carry the infant cadaver. Older mothers are also less likely to wear it.

How long mothers carried their baby’s body depended on the strength of their bond, which was usually determined by the age at which they died. Mothers carried infants longer when they died at a very young age, while there was a significant drop when babies reached about half of weaning age.

Dealing with death and bereavement

The authors say their findings suggest primates might need to learn about and deal with death the same way humans do.

“It may take some experience to understand that death results in a long-lasting ‘cessation of function’, which is one of the concepts of death that humans have,” says Carter. do not know, and may never know, that is if primates can understand that death is universal, that all animals, including themselves, will die. “

Cater points out that human mothers who have a stillborn baby are less likely to experience severe depression if they are able to hold the baby and express their bond.

“Some primate mothers may also need the same time to cope with their loss, showing how strong and important maternal bonds are to primates and mammals in general.”

Researchers are trying to understand why primate mothers carry the corpses of their babies.

“At this point, with the evidence we have, I suspect that much of this is the strong mother-infant bond in mammals and the long-lasting addiction that infant primates (and some other mammals) have. have, ”Carter says.

“While it’s still speculative, it looks like porterage behavior can be compared to human grief, although we need more data to really find out. Talking about closure is difficult as it can vary from person to person. But I think some primate mothers need time to break the strong attachment they have for their babies.

The study could have important ramifications in many areas, researchers say

“These findings have implications for broader debates about animal cognition, the origins of grief and awareness of death, and by extension the ethical position of animals in society,” says Carter.

“Should we treat primates any differently if we know they mourn the loss of a closely related individual the same way we do?” In practice, if primates are to be kept in zoos, our results suggest that corpses should not be immediately removed if mothers are to “process” the loss. ”