Documented for the first time

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"Rakus" treated his wound himself - with the sap of a liana and plenty of sleep.(Bild: APA/AFP/SUAQ Foundation)

For the first time, researchers have systematically documented that a wild animal uses a plant to treat injuries. Evolutionary biologists from the Max Planck Institute of Animal Behavior in Konstanz report in the journal "Scientific Reports" that a Sumatran orangutan actively treated a wound on its face with a medicinal plant.

A few days after suffering an injury in a fight with a conspecific, the male "Rakus" tore off leaves from a liana, chewed on them and repeatedly applied the sap to the facial wound for several minutes. "The last step was to cover the wound completely with the chewed leaves," says first author Isabelle Laumer.

Liana is used by humans to treat malaria
She observed the behavior at the Suaq Balimbing research site, a protected rainforest area on Sumatra, which is home to around 150 endangered Sumatran orangutans (Pongo abelii). The liana used for healing (Fibraurea tinctoria) is known for its analgesic and antipyretic effects and is used in traditional medicine to treat various diseases such as malaria.

"Rakus" (pictured) treated his wound himself - with the sap of a liana and plenty of sleep.(Bild: APA/AFP/SUAQ Foundation)

The authors also report that the orangutan did not develop an infection in the days that followed. The wound closed within five days and healed completely within a month. "Interestingly, 'Rakus' also rested more than usual when he was injured. Sleep has a positive effect on wound healing, as the release of growth hormone, protein synthesis and cell division are increased during sleep," explains Laumer.

The orangutan without the nasty wound on his face.(Bild: APA/AFP/SUAQ Foundation)

"The process took a long time"
The behavior of "Rakus" therefore appeared to be intentional, as it selectively treated only the facial wound and no other parts of the body with the plant sap. "The behavior was also repeated several times, not only with the plant sap, but later also with more solid plant material, until the wound was completely covered. The whole process took a long time," says Laumer.

According to the study, it was previously only known that great apes ingested certain plants to treat parasite infections and rubbed plant material on their skin to treat sore muscles. Recently, a group of chimpanzees in Gabon were also observed applying insects to wounds.