Scientists observed Rakus pluck and chew up leaves of a medicinal plant used by people throughout Southeast Asia to treat pain and inflammation. The adult male orangutan then used his fingers to apply the plant juices to an injury on the right cheek. Afterward, he pressed the chewed plant to cover the open wound like a makeshift bandage, according to a new study published in Scientific Reports. Previous research has documented several species of great apes foraging for medicines in forests to heal themselves, but scientists hadn't yet seen an animal treat itself in this way. "This is the first time that we observed a wild great ape using a plant, a potent medical plant, in order to treat his wounds," says the report's lead author, Isabelle Laumer, a cognitive biologist at the Max Planck Institute of Animal Behaviour. The orangutan's intriguing behaviour was recorded in 2022 by Ulil Azhari, a co-author and field researcher at the Suaq Project in Medan, Indonesia. Photographs show the animal’s wound closed within two months without any problems. "Orangutan males, when they are in puberty or after puberty, they disperse over a wide distances to establish a new home range in another area. And we know that Rakus was not born in the area. So, it's possible that the behaviour is actually shown in his birth population, and he might have learned it from his mother or another orangutan," Laumer. "And we know that orangutans do social learning. So, they show peering, which is close distance observation of another, so that they sometimes come close 10 to 20 centimetres, watching another, for example, processing and opening a food, in order probably to learn the mechanism how to do it." Scientists have been observing orangutans in Indonesia’s Gunung Leuser National Park since 1994, but they hadn’t previously seen this behaviour. "This is a single observation. So, they saw one orangutan have this behaviour. So, on its own, if this was the only report on anything related to medication, you would say, well, we need more evidence. And I think we still do need more evidence," says Emory University biologist Jacobus de Roode, who was not involved in the study. "But I think there's a few key things here that really make me convinced that it is a form of animal self-medication. And one of them is this... the orangutan really specifically applied the mixture that it made to the wound, no other body parts. It's very direct what it was doing." Rakus was born and lived as a juvenile outside the study area. Researchers believe the orangutan got hurt in a fight with another animal. It's not known whether Rakus earlier treated other injuries. Scientists have previously recorded other primates using plants to treat themselves. Bornean orangutans rubbed themselves with juices from a medicinal plant, possibly to reduce body pains or chase away parasites. Chimpanzees in multiple locations have been observed chewing on the shoots of bitter-tasting plants to soothe their stomachs. Gorillas, chimpanzees, and bonobos swallow certain rough leaves whole to get rid of stomach parasites.