Two chimps, one grooming the other on the chin
One chimpanzee grooming another on its chin

Chimps Appear to Treat Others' Wounds Using Insects

The practice, which hasn’t been previously observed among nonhuman animals, may be a display of empathy. 

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Natalia Mesa

Natalia Mesa is an intern at The Scientist. She has a PhD in neuroscience from the University of Washington and a bachelor’s in biological sciences from Cornell University.

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Feb 7, 2022

ABOVE: Tobias Deschner

Researchers have spotted chimpanzees capturing insects, licking them, and applying them to other chimps’ wounds. The insects likely serve as a healing salve, the scientists speculate. And though other animals such as elephants and cats have been known to self-medicate, this is the first time nonhuman animals have been reported to apply medicines to others.

The behavior was first captured in 2019 by a volunteer who, while working at the Ozunga Chimpanzee Project in Loango National Park, West Africa, watched a female chimpanzee apply an insect to her son’s injured foot, according to Science Focus. Scientists working at the Ozouga Project documented 22 further instances of chimps applying insects to open wounds over the next 15 months and published their findings today (February 7) in Current Biology

Chimps use insects as medicine
Alessandra mascaro, ozouga chimpanzee project

The researchers don’t know what insects the chimpanzees are using or how they may help heal a wound, reports The New York Times, which adds that they are small, flying insects that are dark in colorAccording to Newsweek, researchers say that the insects may have some sort of anti-inflammatory or antiseptic properties. However, the researchers tell the outlet that it’s also possible that the insects have no medicinal benefits and that the behavior may be a part of chimpanzee culture. 

There’s no evidence that the chimps are eating the insects, according to the Times. Instead, they’re capturing them, squeezing them between their lips, and placing them inside the wound. 

Simone Pika, a cognitive biologist at the University of Osnabruck in Germany who is an author of the new study, tells Newsweek that to observe chimpanzees not only treat their own wounds but also the wounds of others was “particularly striking.” She says that specific social behavior is rarely seen in nonhuman species.

See “Chimp Groups Have Their Own Distinct ‘Handshakes’

Other animals cooperate with members of the same species in similar ways, Pika tells the Times, “But we don’t know of any other instances in mammals,” she says. “This may be a learned behavior that exists only in this group. We don’t know if our chimps are special in this regard.”

Aaron Sandel, an anthropologist at the University of Texas, Austin, who was not involved in the study, finds the work valuable but expresses doubts about the researchers’ explanation for the behavior. “They don’t offer an alternative explanation for the behavior, and they make no connection to what insect it might be,” he tells the Times. “The jump to a potential medical function? That’s a stretch at this point.”

In the animal kingdom, social behavior is typically mutually beneficial. But in the instances she observed, Pika tells the Times, the chimp capturing and placing the insect on another’s wound gets nothing tangible in return. To her, this may show that the apes are engaging in an act that increases “the welfare of another being.”

“With every field site we learn more about chimps,” Pika tells the Times. “They really surprise us.”