[LUM#14] Observing the mourning of chacma baboons
Grief does not stop at the threshold of human life. Numerous studies report the emotional and physiological manifestations caused by the death of a loved one in animals. An example of this can be seen in Namibia, where Montpellier primatologist Elise Huchard is exploring the grief of female baboons when their young die.
The expression "to mourn" could have been invented for them. In Tsaobis Nature Reserve, at the edge of the Namib Desert, female chacma baboons have been observed carrying the small corpse of their dead baby for several days. "Carrying the body is very difficult for them," explains Elise Huchard, a primatologist atthe Institute of Evolutionary Sciences in Montpellier (ISEM*). "A living baby will cling to its mother's belly or back on its own, but in this case, they have to carry it in their mouth or support it constantly with one arm, which makes it very difficult for them to move around."
A deep mourning
For these baboons, who are forced to travel long distances every day to find food, the cost of such behavior is significant. Yet females will sometimes carry the body for a week or even ten days. "They put it down briefly to go and eat, but as soon as another individual approaches, they rush back. Sometimes they lose it during a social conflict, for example. We have heard females emit real distress calls," says the ethologist.
Continued grooming is another manifestation of mourning, even when, under the effect of heat, the small body appears completely mummified or dislocated. Or even examining the wounds that caused death, most often inflicted by a male: "In the first hours after death, we often see females putting their fingers in the wound and licking it. We have seen them remove debris from the baby's mouth. " According to the researcher, these behaviors "most likely" demonstrate the strength of the social bond between a primate mother and her young. "When there is a sudden and unexpected break in this bond, mothers cannot cope emotionally. Staying in contact with their child's body can help them cope."
Researchers do not rule out the possibility that the death of adult individuals may also trigger mourning behavior, but this is more difficult to observe, particularly because the corpses are not found. However, another study of baboons, based on analysis of cortisol levels in feces, revealed an increase in stress levels among females who had recently lost a friend. "This is one of the few studies that quantifies a physiological stress response to the death of a loved one," says Elise Huchard. "These females will then have more grooming partners than usual, which helps them return to their normal stress hormone levels more quickly."
The field of mourning
The manifestations of grief in animals in general remain a relatively unexplored subject due to their very nature. Rare and unpredictable, death and the reactions it provokes are difficult to study in a specific project, as the behaviorist points out: "For a long time, we recorded these behaviors in the context of our routine projects. Then, in the 2010s, a field of research emerged on reactions to the death of animals, which has been particularly flourishing among primates."
A field that Elise Huchard and her colleagues at the Tsaobis baboon project wish to expand by making this study the starting point for a long-term project dedicated to observing mourning behavior in baboons. Their goal is to establish a protocol for quantifying all of these behaviors over several years. "We would like to know the impact that mourning can have on the lives of these females. Will they withdraw socially or, on the contrary, become more social? Will we observe consolation or social compensation behaviors on the part of other individuals in the group? Will they eat less? Does the intensity of the maternal relationship influence the duration of mourning...?"
With a heavy heart...
But are primates the only social mammals that react to death? For Elise Huchard, the answer is no. "Typically, in the case of primates, we see this obvious behavior of carrying, which is a consequence of the fact that they have hands. There is also a longer development period in these species , which explains the strength of the mother-child bond, but I think that many animals react to death with more or less obvious manifestations." She cites the case of whales andorcas that remain in contact with the carcass of their young for several days, andelephants that return for months to the place where a loved one died.
After these observations, one question inevitably springs to mind: should we see this as proof of an awareness of death in animals? It's not that simple, according to the specialist, for whom mourning "does not necessarily imply a high level of awareness of death, but this is partly the domain of philosophers, and their contribution to concepts as difficult to grasp as consciousness is extremely valuable to scientists like us." One thing is certain: these baboons are not just mimicking mourning.
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* Isem (University of Marseille – CNRS – IRD – EPHE)