How Primates Respond to Their Dead Infants

When a young monkey or ape dies, its mother often keeps the body with her. This is the best-documented way that animals respond to death. This article describes what has been seen and what scientists think explains it.

What do primates do with the dead?

Several things. A 2019 review by Gonçalves and Carvalho says primates have been reported for two centuries to inspect, protect, retrieve, carry, or drag the bodies of their dead. Carrying a dead infant is the most commonly reported behavior. The review argues that, given primates’ thinking abilities, they are capable of an implicit awareness of death.

How long do mothers carry dead infants?

It varies a great deal. A 2022 chimpanzee study by Soldati and colleagues says chimpanzees typically carry a dead infant for up to three days. But a report from Bossou, Guinea, describes a mother who carried her dead infant for 27 days and groomed it regularly. The body dried out, or mummified, in the weeks after death. The authors of that report note that all three documented infant deaths at Bossou were followed by extended carrying. A bonobo report in Pan Africa News, citing earlier work, adds that a chimpanzee mother at Mahale, Tanzania, carried hers for at least 111 days.

Other species differ. Researchers observing geladas at Guassa, Ethiopia, over 3.75 years saw 14 females carry dead infants for anywhere from one hour to at least 48 days. A bonobo mother in that report carried her infant for about two hours. The same report notes that bonobo mothers have sometimes eaten the bodies of dead infants.

Why do they do it?

Nobody is certain, and the explanations are not mutually exclusive. Soldati and colleagues summarize six main hypotheses. Four of them are:

• The mother-infant bond. The stronger the bond, the longer the mother continues to care for the body.
• The climate. Dry, hot, or cold conditions slow decay and favor mummification, so a body stays recognizable and light enough to carry. The gelada researchers favor this idea for their cases.
• Hormones. The mother’s body is still in a post-birth state and keeps responding to her infant.
• Learning about death. Young or inexperienced mothers may carry corpses more often as a way to learn what death is.

Researchers have begun testing these. Elizabeth Lonsdorf and colleagues tested the hypotheses with 33 cases of chimpanzee corpse carrying at Gombe, Tanzania, the largest such dataset for chimpanzees. A preprint that has not been peer reviewed notes that carrying a body makes it harder to forage and move, which raises a mother’s risk from predators.

Do other primates comfort the dying?

Possibly chimpanzees only. The gelada researchers wrote that “compassionate” caretaking of dying group members may be unique to chimpanzees among non-human primates, though they note it is unknown whether it happens outside captivity.

Does this show grief?

That is the open question. The behavior is real and varied, but explanations like climate and hormones do not require grief. See Do Animals Understand Death? for the debate. For a human parallel, see Losing a Child.

Where can I learn more?

See Do Elephants Mourn Their Dead? and Orca Mothers Who Carry Their Dead Calves.