Scientists observed a wild male orangutan repeatedly rub the wounds on its face with chewed leaves of a medicinal plant in an Indonesian forest reserve.
This is the first known observation that wild animals use plants to treat wounds, and provides evidence that humans are not the only ones using plants for medicinal purposes.
Lacus, a male orangutan, lives in Sumatra's Gunung Leuser National Park and is believed to be about 35 years old. For years, researchers have followed orangutans like him as they travel through the forest, weaving their way through tree canopies in search of fruit to eat.
Scientists within the park's Suak Balimbin research area first noticed the scars on his face on June 25, 2022, when they saw him begin to self-medicate.
“I was very excited to hear about it,” said primatologist Isabel Romer of Germany's Max Planck Institute for Animal Behavior. One reason for this is that records of animals administering drugs themselves are rare, especially when it comes to treating injuries. . She and her colleagues detailed their findings in a study published Thursday in the journal Scientific Reports.
The plant Lacus used is known as Akal Kunin, or yellow root, and is used by people throughout Southeast Asia to treat malaria, diabetes, and other conditions. Research has shown that it has anti-inflammatory and antibacterial properties.
Orangutans rarely eat this plant. But in this case, Lacus ingested a small amount and even applied it to the wound multiple times. The wound closed within five days of noticing it, and within a month it was “healing with no signs of infection,” Dr. Romer said.
Michael Huffman, visiting professor at the Institute of Tropical Medicine at Nagasaki University in Japan, who was not involved in the study, said: Known biomedical properties in wound treatment. ”
Primates have been observed treating wounds in the past, but not plants. Simone Pica, an animal cognition expert at the University of Osnabrück in Germany who recorded the observation, said a group of more than 20 chimpanzees in Gabon, central Africa, had been bitten and a flying insect was applied to the wound. It is said that he was seen there.
It has been discovered that orangutans use medicinal plants in other ways. In 2017, scientists reported that six Borneo orangutans rubbed the chewed leaves of a shrub with anti-inflammatory and analgesic properties on their legs and arms, presumably to relieve muscle pain.
“The general application patterns are similar, which is good for understanding species predispositions to this kind of drug administration behavior,” Dr. Huffman said.
Examples of self-medication in primates remain rare and the behavior is incompletely understood. Chimpanzees, bonobos, gorillas, and white-handed gibbons are known to occasionally eat coarse leaves whole, presumably to expel parasites. Huffman and his colleagues also observed chimpanzees chewing the bitter pith of a plant called Vernonia amygdala to treat insect infections.
However, the behavior is not unique to primates. The Indian civet, a member of the feline family, also swallows leaves whole to get rid of insects. Various birds engage in a strange behavior called anting, in which they rub their bodies against ants to treat feather mites and other parasites. Hundreds of species of bees also collect flower extracts that prevent fungal and bacterial growth within their colonies, which can be considered a form of preventive self-medication or group medicine.
Dr. Raumer hopes Lacus' research will help create a greater appreciation for and desire to protect the endangered Sumatran orangutan. Even after 30 years of studying him in the park, researchers are still learning new things.
Just a few years ago, scientists showed that orangutans can solve complex puzzles, plan for the future, playfully tease each other, and laugh just like humans.
“There's still a lot we don't know about these great apes,” she says.