Rakus I, an orangutan male from Sumatra (Pongo abelii), was observed to exhibit a unique behavior by applying a plant with medicinal properties to a wound under one of his eyes. This behavior, which had never been seen before in a wild animal, took place in the Suaq Balimbing research area of Gunung Leuser National Park in Indonesia. Rakus applied the sap of the climbing plant Akar Kuning (Fibraurea tinctoria) to the wound, covering it with chewed leaves.

Akar Kuning is known for its analgesic and antipyretic effects and is traditionally used to treat wounds, dysentery, diabetes, and malaria. Researchers from the Max Planck Institute for Animal Behavior in Germany and Universitas Nasional in Indonesia observed Rakus’ behavior in June 2022 and noted how he selectively treated his wound with the plant’s juice. This intentional behavior suggests that medical treatment of wounds may have originated from a shared common ancestor of humans and orangutans.

While wild primate species have been observed using plants with medicinal properties, it was the first time that a great ape species was seen applying them to fresh wounds. Rakus’ wound healed in five days and was completely cured within a month due to the application of the plant’s juices. This behavior raises questions about the intentionality of such actions in non-human animals and how they develop.

It is possible that Rakus’ innovative behavior of treating wounds with Fibraurea tinctoria may have been absent in the behavioral repertoire of the Suaq orangutan population until now. The potential evolutionary origins of this behavior shed light on the existence of self-medication in our closest relatives and provide insights into the broader concept of wound medication among great apes.