Orangutan’s use of a medicinal plant to treat wounds intrigues scientists

INDONESIA – In June 2022, a male Sumatran orangutan named Rakus suffered a facial wound below his right eye, apparently during a fight with another male orangutan at the Suaq Balimbing research site, a protected rainforest area in Indonesia. What Rakus did three days later really caught the attention of scientists.

On May 2, researchers described observing how Rakus appeared to treat the wound using a plant known for its pain-relieving properties and for promoting wound healing due to its antibacterial, anti-inflammatory, antifungal and antioxidant qualities.

The orangutan chewed the plant’s leaves to produce a liquid that Rakus repeatedly smeared over the wound and then applied the chewed plant material directly to the wound, much like a band-aid administered by doctors, according to primatologist and cognitive biologist Isabelle Laumer of the Max Planck Institute for Animal Behavior in Germany.

Rakus also ate the plant, an evergreen vine commonly called akar kuning (Fibraurea tinctoria), added Dr. Laumer, lead author of the study published in the journal Scientific Reports. Sumatran orangutans rarely eat this plant in this area of ​​peat swamp forest, home to about 150 critically endangered Sumatran orangutans.

“To our knowledge, this is the first documented case of active wound treatment with a plant species with medical properties by a wild animal,” said the study’s lead author, Caroline Schuppli, an evolutionary biologist at the institute.

Rakus, believed to have been born in 1989, is an eyelashed male, with large cheek pads on either side of the face, secondary male sexual characteristics. Rakus was one of the dominant males in the area.

The researchers said the orangutan’s self-treatment of the wound did not appear to be a fluke.

“His behavior appeared to be intentional. She selectively treated her facial wound on her right bridle with the juice from the plant and no other parts of her body. The behavior was repeated several times, not only plant juice but also more solid plant material was applied until the wound was completely covered. The entire process took a considerable amount of time,” Dr. Laumer said.

The wound never showed signs of infection and closed within five days, researchers said.

“The observation suggests that the cognitive abilities necessary for behavior (active wound treatment with plants) may be as old as the last common ancestor of orangutans and humans,” Dr. Schuppli said.

“However, what exactly these cognitive abilities are remains to be investigated. “While this observation shows that orangutans are capable of treating their wounds with plants, we don’t know to what extent they understand the process.”

The last common ancestor of orangutans and humans lived about 13 million years ago.

Orangutans are one of the world’s great apes (the closest living relatives of humans) along with chimpanzees, bonobos and gorillas. Orangutans are the least related to humans, but still share about 97 percent of human DNA.

“It is possible that treatment of wounds with Fibraurea tinctoria arises through accidental individual innovation. Individuals may accidentally touch their wounds while feeding. Fibraurea tinctoria and thus involuntarily applying the juice of the plant to their wounds,” Dr. Laumer said.

“But it may also be,” Dr. Laumer added, “that Rakus learned this behavior from other orangutans in his birth area.”

Widely distributed in China, Indonesia, Malaysia, Thailand, Vietnam and other parts of Southeast Asia, this plant is used in traditional medicine to treat diseases such as malaria.

Orangutan means “forest person” in the Indonesian and Malay languages, and these apes are the largest arboreal mammal in the world. Orangutans, adapted to living in trees, live more solitary lives than other great apes, sleeping and eating fruit in the forest canopy and swinging from branch to branch.

“Orangutans have high cognitive abilities, particularly in the area of ​​physical cognition,” Dr. Schuppli said. “They are known to be excellent problem solvers. Wild orangutans acquire their skills through observational social learning, and these skills are passed down from generation to generation. The population where this observation was made is known for its rich cultural repertoire, including the use of tools in different contexts.” REUTERS