As it turns out, chimpanzees make pretty good doctors. For decades, scientists have been studying what chimpanzees do when they fall ill. This search has led to the identification of medicinal behaviour, which often involves the ingestion of plants with chemical or physical properties that can help the animal’s recovery.

Previous studies have shown that wild chimpanzees appear to treat their wounds and maintain sexual hygiene using medicinal plants found in their environment. What’s more, they treat other group members, even ones who are unrelated to them....

We also headed into the field to collect eight months of our own behavioural data. The aim: to accumulate all the cases we could find of external healthcare behaviour and see if a pattern emerged.

What we found surprised us. The Budongo chimpanzees appear to have quite a diverse behavioural toolkit for tending to their own wounds and maintaining hygiene in the wild. This behaviour ranges from simple actions like wound licking, to more complicated behaviour such as applying plant material to an injury.

In some cases, chimpanzees dabbed their open wounds with leaves. In rarer cases, they chewed up plant material (like leaves or stem bark) and applied it directly to the affected area with their mouths. Similar behaviour was shown in Sumatran orangutans in 2024.