AsianScientist (Aug. 01, 2025) – The ability to grieve for dying loved ones was long considered a distinctly human trait — an emotional complexity thought to separate us from animals. But new research from Japan is challenging that view.
In a study published in Primates, researchers from The University of Osaka have found that Japanese macaques display remarkably human-like responses to the deaths of their adult companions, offering fresh insights into the emotional lives of non-human primates.
Japanese macaques live in large and highly complex social groups, and their social behaviors have been studied for decades. Despite this, observations of the macaques’ responses to death have been rare, except for mothers of various non-human primate species, ranging from lemurs to apes, who carry their dead infants for a while, and respond toward their dead infant by sniffing, licking, touching, holding, grooming, and returning to the corpse.
The researchers encountered several rare opportunities to closely observe how individual free-ranging macaques responded to their dying and deceased companions. They found that some macaques stayed close to the bodies and even groomed them repeatedly, especially when the deceased had been a close social partner in life.
“It’s incredibly rare to document these kinds of behaviors in wild animals,” said Professor Masayuki Nakamichi, lead author of the study. “By tracking which individuals were near the deceased and recording their behaviors, we were able to show that their reactions to death were significantly influenced by social bonds.”
It was observed that obvious injury or infestation appeared to be a strong deterrent to physical contact, whereas more subtle signs of decline were less likely to affect social interactions. For instance, many macaques clearly avoided the presence of maggots in both dying and dead macaques, likely indicating an aversion to maggots.
However, the researchers recorded one case where social bonds triumphed over this aversion — one alpha female not only remained near her dying grooming partner, but also picked maggots off his back and ate them.
“The fact that some individuals remained near deceased companions they had close relationships with suggests that these macaques have emotional capacities that resemble human compassion,” says Kazunori Yamada, co-author of the study. “It shows that strong social bonds can affect the behavior of macaques, even after death.”
It remains uncertain whether social bonds affect the way to interact with dying and dead companions in other non-human primates.
“More observations of death-related events in more species will be needed to fully understand the emotional responses of non-human primates to the dead,” says Nakamichi.
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Source: The University of Osaka; Image: Freepik
The study can be found at: Responses to dying and dead adult companions in a free-ranging, provisioned group of Japanese macaques (Macaca fuscata)
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