Chimps self-medicate using bugs

For the first time, researchers in West Africa have observed chimpanzees putting insects on their wounds.

The research team first spotted this behaviour in November 2019, when they watched a chimpanzee called Suzee inspect a wound on her son, Sia. Suzee then caught an insect out of the air and placed it in her mouth to immobilise it before rubbing it over the surface of Sia’s wound.

“In the video, you can see that Suzee is first looking at the foot of her son, and then it’s as if she is thinking, ‘What could I do?’ and then she looks up, sees the insect, and catches it for her son,’” says Alessandra Mascaro, a volunteer at the Ozouga Chimpanzee Project in Gabon, West Africa.

This video shows a chimp named Suzee inspecting a wound on the foot of her adolescent son, Sia, then catching an insect out of the air, putting it in her mouth, pressing it between her lips, and applying it to the wound while her daughter, Sassandra, observes her. Credit: Alessandra Mascaro

While the Ozouga project had been studying this group of chimps in Loango National Park for seven years, it had never seen this behaviour before.

Now, in a new paper published in Current Biology, the team describes 76 cases of these wound-tending behaviours documented over 15 months, with chimps looking after both their own and others’ wounds. Sometimes insects were applied multiple times to the same wound.

Previous research has shown that bears, elephants, moths and bees also self-medicate, but not with insects.

Simone Pika, a cognitive biologist at Osnabrück University in Germany and co-author of the paper, argues that tending the wounds of others is an example of a prosocial behaviour – which in humans is linked to empathy.

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

She adds that the team isn’t quite sure exactly how insects could help a wound, or even which species of insects the chimps are using, though they appear to be winged flying insects.

“Humans use many species of insect as remedies against sickness – there have been studies showing that insects can have antibiotic, antiviral and anthelmintic functions,” says Pika.

Pika and team suggest that insects might perhaps provide pain relief.

The team now plans to identify the insects used by the chimps, and to continue to document which chimps apply insects to each other.

“Studying great apes in their natural environments is crucial to shed light on our own cognitive evolution,” says co-author Tobias Deschner from the Max Planck Institute for Evolutionary Anthropology in Germany.

“We need to still put much more effort into studying and protecting them and also protecting their natural habitats.”

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