Death Practices of Baboons After Infants Die Discovered

Baboons have been observed carrying their dead infants around and cleaning their mouths in an apparent reaction to the loss, researchers have said. While studying Namibian chacma baboons for 13 years in the wild, a team documented the behavior following 12 infant deaths, finding specific practices relating to the death of an infant.

Primates like monkeys and chimpanzees are known to perform certain actions after the death of a group member. A study published last year reviewing evidence of primate thanatology—the study of death and associated practices—found apes and chimps appear to have awareness of death and grief-related rituals.

Now, researchers led by Alecia Carter, from the U.K.'s University College London (UCL), have extended our understanding of primate death practices. In their study, published in Royal Society Open Science, the team documented 12 infant deaths, including one miscarriage and two stillbirths.

The responses of the mothers and the group more generally were recorded in detail, charting—where possible—the age and status of the mother, the cause of death, how the corpse was handled afterwards and by who. Where another baboon handled the corpse, their interactions and relationship with the mother and infant were noted.

As with other primate species, the mothers were seen to carry the corpse for a period after death. This lasted between one hour and 10 days. They groomed the corpses frequently and in two cases the bereaved mothers cleaned out the mouth of the dead infant. This behavior had not been recorded in live individuals.

Carter told Newsweek the biggest surprise was that 10 days appeared to be the cut off for corpse carrying, which tends to be longer in Old World primates. "Male friends of the mothers also 'protect' the corpse, which seems to be very rare, even in species where the males are usually in the same groups as their infants," she said.

baboon infant corpse
An adult male baboon sits next to an infant's corpse. Researchers documented 12 infant deaths over 13 years among Namibian chacma baboons. A Carter/Royal Society Open Science

"Male baboons actually provide some care to infants, despite their promiscuous mating system. Females can form friendships with males, and these males often protect the infant from threats, or share their food patches with them. So, just as maternal behaviour seems to carry-over after her infant's death, it looks like some adult males also continue this protection after the infant's death."

Carter said there is no evidence to explain why the baboons would clean the dead infant's mouth: "I would suggest that the baboon mouth-grooming is not in itself significant. But I would argue that post-mortem corpse care, including any grooming, is significant."

Eventually, the infant's corpse would be abandoned, she said. Concluding, the researchers say their study adds to the "growing body of literature on primate thanatology," and shows how more cases can help give support or detract from current hypothesis. They call for more researchers to provide detailed accounts of how primates deal with death, so more specific behaviors can be identified.

Carter will continue to study thanatology among these species: "I really want to understand
why the primates carry their dead infants, and what this can tell us about the evolution of the primate mind," she said.

André Gonçalves, from Kyoto University's Primate Research Institute, Japan, who was not involved in the research, commented on the findings. "The question of whether non-human primates have a concept of death similar to humans is a thought-provoking one, but one which likely won't be answered without the help of well-designed experimental studies," he told Newsweek.

"Many questions still remain unanswered. Do baboons console other bereaved conspecifics like recently suggested in chimpanzees? Are baboon mothers just motivated to carry their dead infants in itself acting as a way to buffer their grief-like symptoms, not unlike handling a stillborn in some human cases? Do different causes of death impact the duration of the carryings, with violent ones permitting a faster recategorization from dead to live and slow acting ones such as illnesses precluding it? [This is] something to look for in future studies."

He said that in publishing this paper, the researchers have noted the need for long-term field studies so they can establish the factors that influence these behaviors. This, he said, can "also inform us about possible similarities, but also striking differences at both the species level but also at the level of different communities within the same species."