In 2003, in the deep forests of Bossou in Guinea, a chimpanzee mother did something that reshaped how we view animal minds. Jire carried the the lifeless body of her one-year-old infant Jimato for some 68 days. Even as the infant mummified before her, she gently swatted flies away, carefully placed it on branches while she ate, and cradled it as she moved through the canopy and forest ground.
Authors
- Thomas A. Püschel
Associate professor, University of Oxford
- Reece Hammond
DPhil Student in Anthropology, University of Oxford
Carrying a deceased infant is an extraordinary physical commitment. Imagine trying to go about your everyday life, navigating difficult terrain, securing food, and keeping up with your family in a forest, while bearing the weight of a lost infant. It restricts how you move and demands constant mental vigilance.
Yet, despite this immense physical and psychological toll, chimpanzee and bonobo mothers frequently refuse to let go. Indeed, the example of Jire and Jimato is eclipsed by a case from the Mahale Mountains, Tanzania, where a mother carried her infant’s corpse for perhaps as long as 126 days.
To understand why chimpanzee and bonobo mothers do this, we analysed 83 cases across 15 chimpanzee and bonobo communities. We discovered that this behaviour is remarkably widespread. It seems to be a fundamental part of how these apes deal with the death of their young.
The strongest pattern we found concerned the cause of death. Mothers carried infants that had died from disease for much longer than
infants killed by other chimpanzees. A fatal illness can create a gradual fade between life and death. An infant slowly becomes less responsive, making the exact point at which normal maternal care should stop difficult to pinpoint. On the other hand, abandoning an infant after a violent attack might be a survival mechanism , allowing the mother to quickly escape a dangerous social situation.
The age of the infant also seems to dictate the mother’s response. The bond between a primate mother and her newborn is driven by a powerful cocktail of hormones and thousands of daily interactions. When a baby dies suddenly, the mother’s brain and body do not simply switch off that intense connection overnight. Comparative research across other primate species including great apes, Old World monkeys (Africa and Asia), and New World (central and south America) monkeys, shows that these deep biological attachments strongly influence how long a body is carried.
This raises a fascinating question: do these chimpanzee and bonobo mothers actually know their babies are dead?
It is tempting to assume that carrying a corpse means the mother is confused, or, conversely, that she fully grasps the finality of death. However, our observations suggest a more nuanced reality. Mothers treat the bodies of their deceased infants differently than they would a living baby. For instance, they might carry them casually by a single limb or allow other group members to investigate the body, behaviour they would rarely permit with a vulnerable, living newborn.
While these actions show the animals recognise something fundamental has changed, it does not automatically mean they grasp the complex human concept of death. In fact, a full understanding of death isn’t actually necessary to explain the patterns we observed. Instead, their actions are best explained by the powerful, lingering instinct to care for their young.
We found that the length of time a mother continues to carry her infant depends on how strong their bond was, her life experience, the physical risks of holding onto the body and how quickly it naturally breaks down.
This impulse towards dead infants is not restricted to mothers. At Gombe, Tanzania, almost a quarter of observed cases of chimpanzee infant-corpse carrying involved someone other than the infant’s mother . In Namibia, researchers even observed an unrelated male baboon carrying the corpse of a nine-week-old infant after its mother had died two days earlier. And among wild bonobos , other females have approached a mother’s dead infant to groom its body. Perhaps, then, these animals are experiencing an ancient biological pull towards the young one that does not simply disappear when life ends.
Intense responses to death are not restricted to primates. Many highly social species also struggle to part with their dead. Elephants are known to return to the bones of their relatives, touching them gently with their trunks and may even bury their deceased infants. In the ocean, dolphins have been seen pushing deceased calves to the surface, and in 2018, an orca named Tahlequah swam for 17 days carrying her dead calf across 1,000 miles of ocean and tragically, was later seen doing the same for a second calf .
Together, these observations are helping to build the fascinating field of comparative thanatology , – the scientific study of how different animals understand and react to death. At the heart of this field is a surprisingly difficult question. Some researchers argue that attributing a human-like concept of death to animals goes beyond the evidence. Others propose that animals’ understanding may exist on a spectrum .
When our early human ancestors lost a child, they would have experienced the same crushing hormonal and emotional withdrawal that we see in these chimpanzee and bonobo mothers today. Long before humans developed elaborate funerals, wakes and burials, this deep biological impulse to hold onto a deceased loved one laid the evolutionary basis for how we mourn.
However, because chimpanzees and bonobos are our closest living relatives , the differences in how we respond to death are incredibly revealing. The fact that these apes don’t necessarily need a fully developed concept of death to explain their behaviour suggests something profound. The complex mental frameworks required to grasp death’s finality probably emerged in our own human lineage after we diverged from our shared ancestor millions of years ago.
