In June 2022, Rakus, an orangutan from the island of Sumatra, applies a plant poultice to his face to treat his wound. This is the first time it has been observed in great apes in the wild.
Almost human behavior. Wounded in the face, a Sumatran orangutan made a bandage from a medicinal plant, the journal Scientific Reports reported this Thursday, May 2. According to scientists, this is the first time such behavior has been observed in a great ape in the wild.
The primate, named Rakus, is being monitored by a team of scientists with some 130 conspecifics, all in the wild, in the Gunung Leuser National Park in the north of the island of Sumatra in Indonesia.
A traditional remedy
Aged around thirty, Rakus was injured in the face in June 2022 “probably during a fight with a male from the neighborhood”, according to Isabelle Laumer, primatologist at the German Max Planck Institute and first author of the study .
Three days after his injury, the monkey began to chew the leaves of a vine, locally called “Akar Kuning” (Fibraurea tinctoria). After extracting the juice, he coated his fingers with the preparation before applying it to his wound, extending from the right eye to the nostrils. Result: five days later the wound was closed and two weeks later, it left a barely visible scar.
The “remedy” used is not miraculous, it is part of the traditional pharmacopoeia in the region, from China to Southeast Asia. This vine and others like it “are used as traditional remedies for different ailments, such as malaria,” according to the cognitive biologist, cited by Max Planck. Thanks to antibacterial and anti-inflammatory properties, among others.
According to the study, this is the first “documented case of treatment of a wound with a plant species containing active biological substances by a wild animal.” If confirmed by further observations, it would complete a growing list of self-medicating behaviors by animals, particularly in primates.
“This is very special because until now, at least to our knowledge, no wild animal has been observed medically treating its wounds with a plant,” said Isabelle Laumer.
In the 1960s, famous primatologist Jane Goodall first observed chimpanzees ingesting medicinal leaves, the anti-parasitic role of which was later revealed. A behavior observed since in bonobos and gorillas, with a selection by the animal of the plants ingested, the knowledge of which would be transmitted by females.
An intentional gesture?
More recently, researchers observed Bornean orangutans, also in the wild, chewing the leaves of a medicinal plant before rubbing it only on their limbs. Coincidence? The plant in question, Dracenea cantleyi, is typically used by indigenous populations to treat sore muscles and joint pain.
“It’s always fascinating to discover behaviors that almost resemble those of humans,” Isabelle Laumer told the scientific journal Stat News.
“We are much more similar than different,” she added.
The study indeed believes that the behavior of Rakus, like that of its congeners from Borneo, was well intentional. With repeated and meticulous treatment of a very specific location, “which took a considerable amount of time”, according to Isabelle Laumer.
Co-author of the study, Dr. Caroline Schuppli does not rule out “individual innovation”, of accidental origin. Rakus could have unintentionally applied the juice of the plant to his wound, just after putting his fingers in his mouth. As the plant has an analgesic effect, the monkeys “can experience immediate relief, pushing them to repeat the operation several times”, according to this head of the Cognitive Development and Evolution Group at Max Planck.
This behavior has not been observed locally until now, the researcher does not exclude that it is present in the area of origin of Rakus, young male orangutans leaving their native region after puberty. The fact that primates, like humans, can actively treat an injury in this way suggests that “our last common ancestor already used similar forms of treatment using ointments”, according to Dr. Schuppli.
