Rakus, a male Sumatran orangutan (Pongo abelii), who suffered an injury under one eye, treated himself with a plant with known medicinal properties – the first time such behavior has been observed in a wild animal.
This orangutan, living in the Suak Balimbing research area in Gunung Leuser National Park (Indonesia), ate and repeatedly applied the juice of the Akar Kuning climbing plant (Fibraurea tictoria) to a wound, which he also covered with chewed leaves. in a study published this Thursday in the journal Scientific Reports.
Akar Kuning is a type of vine known for its analgesic and antipyretic effects. In traditional medicine, it is used to treat wounds and diseases such as dysentery, diabetes and malaria.
In June 2022, Rakus’ behavior was observed and monitored by researchers from the Max Planck Institute for Animal Behavior (Germany) and the National University (Indonesia).
“Rakus’s behavior seemed deliberate” as he selectively applied the plant’s sap to only a wound on his face, and this was repeated several times, said Isabelle Laumer of the Max Planck Institute and one of the study’s authors.
This behavior suggests that wound healing may have originated from a common ancestor of humans and orangutans, the Max Planck Institute said in a statement.
Prior to this study, wild primate species were observed to ingest, chew or rub plants with medicinal properties, but did not apply them to fresh wounds.
“During our daily observations of the orangutans, we noticed that the male, named Rakus, had suffered a facial injury, probably during a fight with another male,” explained Isabelle Laumer.
Three days after being wounded, Rakus selectively plucked Akara Kuning leaves, chewed them, and applied the resulting juice to the wound for exactly seven minutes.
He then applied the chewed leaves to the wound until it was completely covered and continued to feed on the plant for more than 30 minutes.
The chewed leaves may have helped reduce the pain and inflammation caused by the wound and aided its healing, as it closed within five days and healed completely within a month.
As with all self-medication in non-human animals, this case raises questions about the intentionality of the behavior and how it occurs.
“It is possible that the treatment of Fibraurea tinctoria wounds in Suak orangutans is the result of individual innovation,” said Caroline Schuppli, lead author of the study.
Local orangutans rarely eat this plant. However, they may accidentally touch the wounds while feeding and thus accidentally apply juice to the wounds. Because they have a strong analgesic effect, they may experience immediate pain relief, which causes them to repeat the behavior multiple times, Schuppli suggested.
Since this behavior has not previously been observed, it is possible that wound healing with Fibraurea tinctoria has heretofore been absent from the behavioral repertoire of the Suak orangutan population since, like all adult males in the region, Rakus was not born there and has not been discovered. its origin is unknown.
“It is possible that more of their indigenous populations outside the Suak study area exhibit this behavior,” he said.
This potentially novel behavior represents the first report of active wound treatment with a biological agent in a great ape species and provides new insight into the existence of self-medication in close human relatives and the evolutionary origins of wound medications more broadly.