Chimpanzees Appear to Use Insects to Treat Their Wounds

In a first, chimps in Gabon were seen applying insects to sores on themselves—and others, a possible show of empathy

The dark face of a chimpanzee against a green backdrop of leaves
Over the span of 15 months, scientists cataloged 76 instances of chimps using insects on their wounds and the wounds of others.  Marc Guitard via Getty Images

When humans get hurt, we usually reach for a bandage, but chimpanzees don’t have that luxury. Instead, it appears the great apes have invented their own first-aid system: applying insects to open wounds.

While some bears, elephants, insects, and lemurs have been known to use plants to self-medicate against parasites and illness, this is one of the first recorded instance of animals using other animal matter—smooshed insects—as a form of medication, Ashley Strickland reports for CNN. Because the chimps sometimes use bugs to treat their friends' wounds too, the behavior may be a sign of altruism in species, according to the study published Monday in Current Biology.

“When you’re going to school and you read in your biology books about the amazing things that animals can do,” study author Simone Pika, a biologist at Osnabrück University in Germany, told Agence France-Presse. “I think it could really be something like that, that will end up in those books.”

Led by Pika and Osnabrück University primatologist Tobias Deschner, scientists witnessed multiple instances of chimps catching and applying winged insects to themselves and others in a community of about 45 chimpanzees in Loango National Park in Gabon. The observation was made through the Ozouga Chimpanzee Project, which aims to better understand the chimps’ cognitive skills and social relationships.

"Our two closest living relatives, chimpanzees and bonobos, for instance, swallow leaves of plants with anthelmintic (antiparasitic) properties and chew bitter leaves that have chemical properties to kill intestinal parasites,” Pika says in a statement. "Chimpanzees eat insects but we did not know that they catch and use them to treat their wounds.

The novel discovery was made in 2019 by Alessandra Mascaro, who was a volunteer for the project at the time, reports the New Scientist’s Chen Ly. Mascaro watched as a female chimp named Suzee tended to her adolescent son, Sia, who had a wounded foot.

“I noticed that she appeared to have something between her lips that she then applied to the wound on Sia’s foot,” says Mascaro in a statement. “Later that evening, I re-watched my videos and saw that Suzee had first reached out to catch something which she put between her lips and then directly onto the open wound on Sia’s foot."

When Lara Southern, a primatology PhD student at Osnabrück University, witnessed an adult male chimp named Freddy exhibit a similar behavior the following week, the team hypothesized that the chimps were capturing tiny flying insects from the air. Over the next year, the researchers closely watched and filmed chimps that showed any signs of injury.

A year after Mascaro first saw Suzee apply crushed insects to her son’s foot, Southern noticed other adult chimps caring for each other's wounds.

“An adult male, Littlegrey, had a deep open wound on his shin and Carol, an adult female, who had been grooming him, suddenly reached out to catch an insect,” says Southern in a statement. “What struck me most was that she handed it to Littlegrey, he applied it to his wound and subsequently Carol and two other adult chimpanzees also touched the wound and moved the insect on it."

Over 15 months, the research team recorded 76 instances of chimps using insects on their injuries. The study authors suspect that the dark, flying insects might have anti-inflammatory or antiseptic properties, Natalia Mesa reports for The Scientist. Even if the insects don’t provide a medical benefit, the behavior may be an important part of the local chimpanzee social culture. 

What particularly surprised Pika was seeing chimps offer help to individuals that they weren’t genetically related to.

"This is, for me, especially breathtaking because so many people doubt prosocial abilities in other animals," Pika said. "Suddenly we have a species where we really see individuals caring for others."

Next, the researchers aim to recover any remaining insects the chimps use to parts to identify the species and its potential pharmaceutical properties.