Rakus is a male Sumatran orangutan (Pongo abelii) who suffered a wound under one eye and to which a plant with known medicinal properties was applied, a behavior that is the first time it has been observed in a wild animal.
The orangutan living in the Suaq Balimbing research area, in Gunung Leuser National Park (Indonesia), ate and repeatedly applied sap from a climbing plant, Akar Kuning (Fibraurea tictoria), to the wound, which it also covered with chewed leaves, according to a study published today by Scientific Reports.
Akar Kuning is a species of liana known for its analgesic and antipyretic effects. In traditional medicine it is used to treat wounds and conditions such as dysentery, diabetes and malaria.
Rakus’ behavior was observed and followed, in June 2022, by researchers from the Max Planck Institute for Animal Behavior (Germany) and Universitas Nasional (Indonesia).
“Rakus’s behavior seemed to be intentional,” as he selectively treated only the facial wound with the plant’s juice, and it was repeated several times, said Isabelle Laumer, of the Max Planck Institute and one of the study’s signatories.
This suggests that medical treatment of wounds may have arisen in a common ancestor shared by humans and orangutans, the Max Planck Institute says in a statement.
Before this study, wild primate species had been observed swallowing, chewing or rubbing plants with medicinal properties, but not applying them to fresh wounds.
“During daily observations of the orangutans, we observed that a male named Rakus had sustained a wound on his face, probably during a fight with a neighboring male,” explained Isabelle Laumer.
Three days after the injury, Rakus selectively tore off Akar Kuning leaves, chewed them, and applied the resulting juice precisely for seven minutes on the wound. He then smeared the chewed leaves on the wound until it was completely covered and continued feeding on the plant for more than 30 minutes.
The chewed leaves may have helped reduce the pain and inflammation caused by the wound and promoted its healing, as it closed within five days and healed completely within a month.
Like all self-medication behavior in non-human animals, the case described raises questions about the intentionality of these behaviors and how they arise.
“It is possible that the treatment of wounds with Fibraurea tinctoria by Suaq orangutans arises from individual innovation,” says Caroline Schuppli, lead author of the study.
Local orangutans rarely eat the plant. However, they can accidentally touch their wounds while feeding and thus inadvertently apply the juice to the wounds. By having potent analgesic effects, they may feel an immediate release of pain, leading them to repeat the behavior several times, Schuppli suggested.
Since this behavior had not been observed before, it may be that wound treatment with Fibraurea tinctoria has been absent until now in the behavioral repertoire of the Suaq orangutan population, since like all adult males in the area, Rakus was not born there and its origin is unknown.
Therefore, “it is possible that the behavior is shown by more individuals from their natal population outside the Suaq research area,” he considered.
This possibly groundbreaking behavior presents the first report of active wound treatment with a biological substance in a great ape species and provides new insights into the existence of self-medication in our closest relatives and into the evolutionary origins of wound medication. more broadly.
