Chimpanzee mothers carry dead infants for weeks or months

An analysis of 83 cases involving chimpanzees and bonobos found that mothers often carry their dead infants for weeks, sometimes months. The duration of this behavior depends on the cause of death and the strength of the maternal bond, though it does not necessarily mean the great apes understand death.

A mother chimpanzee carried her dead infant for nearly two months

In 2003, in the deep forests of Bossou, Guinea, a chimpanzee mother carried the lifeless body of her one-year-old infant for approximately 68 days. Even as the infant mummified under her care, she gently swatted away flies, placed the body carefully on branches while she ate, and carried it against her body while moving through the canopy and on the ground.

Carrying a dead infant is physically and mentally demanding

Imagine having to go about your daily life, navigate difficult terrain, find food, and follow your group through a forest, all while carrying the weight of a lost child. This hinders movement and requires constant mental vigilance. Yet, despite this immense physical and psychological cost, chimpanzee and bonobo mothers often refuse to let go.

Researchers found this behavior is widespread among great apes

To understand why chimpanzee and bonobo mothers behave this way, researchers analyzed 83 cases in 15 chimpanzee and bonobo communities. They discovered that this behavior is remarkably widespread. It seems to be an integral part of how these great apes deal with the death of their infants.

The cause of death influences how long mothers carry the body

The clearest trend observed relates to the cause of death. Mothers carried infants who died of disease much longer than those killed by other chimpanzees. A fatal disease can create a slow transition between life and death. The infant reacts less and less, making it difficult to determine the exact moment when usual maternal care should cease.

Infant age and maternal bonding influence the duration of carrying

The age of the infant also seems to determine the mother's reaction. The bond between a primate mother and her newborn is based on a powerful cocktail of hormones and thousands of daily interactions. When a baby dies suddenly, the mother's brain and body do not sever this intense bond overnight.

Do these mothers understand death or just continue caring?

We are tempted to believe that carrying a corpse means the mother is disoriented or, conversely, that she fully grasps the finality of death. Our observations, however, suggest a more nuanced reality. Mothers do not treat their dead infant's body as they would a living baby. They may, for example, carry it carelessly by a single limb, or allow other group members to examine the body, which they would rarely allow with a living, vulnerable newborn.

Other animals also show complex reactions to death

Intense reactions to death are not exclusive to primates. Many highly social species also have difficulty separating from their dead. Elephants are known for returning to the bones of their relatives, gently touching them with their trunks, and they may even bury their dead young. In the ocean, dolphins have been seen pushing dead calves toward the surface.

Comparative thanatology explores how animals understand death

Together, these observations contribute to building the fascinating field of comparative thanatology, the scientific study of how different animals understand death and react to it. At the heart of this field lies an astonishingly difficult question. Some researchers believe that attributing to animals a concept of death similar to that of humans goes beyond what the data show.

Human mourning may have evolutionary roots in great ape behavior

However, because chimpanzees and bonobos are our closest living relatives, the differences in our ways of reacting to death are extremely revealing. The fact that the behavior of these great apes does not necessarily require a fully developed concept of death to be explained suggests something profound. The complex mental frameworks necessary to grasp the finality of death likely emerged in our own human lineage, after our separation from our common ancestor millions of years ago.