Why Chimpanzee Mothers Carry Their Dead Infants — An Oxford Study Sheds Light

It’s a sight that tugs at the heart: a chimpanzee mother gently cradling a tiny, lifeless body, refusing to let go for days, sometimes even months. Scientists have called the behaviour “infant corpse carrying” (ICC), but why it happens has long been a mystery.

Researchers at the University of Oxford have now taken a big step toward an answer. By pooling data from 83 documented ICC events across 15 different field sites, they uncovered patterns that tie the duration of the grieving grip to four main factors – the infant’s age, how it died, the mother’s investment in that offspring, and the ambient temperature.

First, the age of the baby matters a lot. Older infants, who have spent more time with mum, tended to be carried longer than newborns. It’s as if the longer the social bond had time to grow, the harder it is for the mother to let go, even when the child is already gone.

Second, the way the infant met its end influences the mourning period. When disease was the culprit, mothers clutched the bodies for a significantly longer stretch compared with infants killed by infanticide. The researchers think that a sudden, violent death is unmistakably final, while a slow, unseen illness leaves the mother with a vague sense that something might still be reversible.

Third, the study highlights “maternal investment” – essentially how much a mother has already poured into that particular child. Populations where females give birth less frequently, and therefore invest heavily in each youngster, showed lengthier ICC episodes. The more a mother has already given, the more reluctant she appears to be to abandon the corpse.

Finally, temperature sneaks in as a subtle but real player. Cooler periods corresponded with longer carrying bouts. One possible explanation is that cooler air slows decomposition, keeping the body’s shape intact longer and perhaps making it easier for the mother to hold on.

It’s tempting to read these findings as evidence that chimps understand death in the same way humans do. The Oxford team is careful not to over‑interpret. They point out that mothers have been observed carrying mummified infants – bodies that are unmistakably dead – yet the grip persists. This suggests the behaviour may stem from an innate maternal response that keeps going even after the infant’s biological signals have vanished.

“We don’t need to assume that chimp and bonobo mothers grasp the permanence of death to explain why they keep holding their babies,” says Thomas A. Püschel, an evolutionary anthropologist at Oxford. “The lasting bond, the circumstances of the death, and the environment together shape the behaviour.”

Why does this matter for us? Humans share a common ancestor with chimpanzees and bonobos roughly six to eight million years ago, so the way our close relatives deal with loss can hint at the evolutionary roots of grief. If recognising death as final isn’t a prerequisite for ICC, then the sophisticated, abstract concept of mortality might be a later development in the human line.

In short, the study paints a picture of grief that is both deeply emotional and profoundly practical – a mother’s love, the shock of loss, and even the weather combine to dictate how long she will linger with her departed infant.