The chimpanzee was sick. It had diarrhea and tapeworms — not unusual for a wild chimpanzee in the Budongo Forest of Uganda. What intrigued the watching research team was what the ape did about it.

Soon after its symptoms developed, the male traveled with two others away from the community’s home to a site in the forest with a particular type of tree. It collected some dead wood from the Alstonia boonei and chewed it. The plant has long been used in traditional medicine, and when the scientists tested it, they confirmed it had high antibacterial and anti-inflammatory properties. The chimp made a full recovery.