Biologists from the Max Planck Institute of Animal Behavior, Konstanz, Germany and Universitas Nasional, Indonesia observed a large male orangutan self-medicating—using a paste of chewed up plants topically to heal a large wound on his cheek. It’s essentially a wild animal that appears to intentionally make his own medicinal salve.
A peer-reviewed study was Updated Thursday in Scientific Reports, demonstrating the first time scientists have observed this specific behavior from an orangutan. The biologists first saw the behavior in 2022 when the orangutan was badly wounded. Rakus is an orangutan that lives in Gunung Leuser National Park in Sumatra, and when he was wounded on his cheek with a gaping hole, he sprung into action, behaving in a way scientists have never seen before in a non-human.
Lead researcher Dr. Isabelle Laumer, a primatologist and behavioral biologist confirmed the findings to High Times. “We observed a male Sumatran orangutan (Pongo abelii) who sustained a facial wound,” researchers wrote. “Three days after the injury he selectively ripped off leaves of a liana with the common name Akar Kuning (Fibraurea tinctoria), chewed on them, and then repeatedly applied the resulting juice onto the facial wound. As a last step, he fully covered the wound with the chewed leaves.” Watch the orangutan here the first time he was observed behaving this way. (Laumer et al., 2024 Scientific Reports)
The researchers saw no indications of infection and the wound closed within five days. After a month, Rakus’s wound was fully healed.
Fibraurea tinctoria is a plant that demonstrates anti-inflammatory and antibacterial properties, and it can be used locally to treat malaria and diabetes. Humans have been using medicinal salves for thousands of years, but this behavior is rarely seen in wild animals.
“The treatment of human wounds was most likely first mentioned in a medical manuscript that dates back to 2200 BC, which included the cleaning, plastering, and bandaging of wounds with certain wound care substances,” Dr Caroline Schuppli, a senior author of the paper, told the Natural History Museum. “As African and Asian great apes have also been seen actively treating wounds, it is possible we share a common underlying mechanism for recognising and applying medical substances to wounds. This might have developed in a common ancestor, which may have already showed similar forms of ointment behaviour.” (Laumer et al., 2024 Scientific Reports)
CBS News reports that gorillas, chimpanzees, and bonobos swallow certain bitter-tasting leaves whole to get rid of stomach parasites. The rough texture of the leaves can scrape out their digestive systems. The apes appear to only eat those types of bitter leaves when they need help with their digestive tracts.
Researchers said we can learn about ourselves based on these findings. “They are our closest relatives and this again points towards the similarities we share with them. We are more similar than we are different,” biologist Dr Isabella Laumer at the Max Planck institute in Germany told BBC News.
Orangutan Intelligence
Orangutans demonstrate remarkable intelligence, and some researchers believe it may surpass the intelligence of chimps. Psychologist Robert Deaner of Grand Valley State University in Michigan, for instance, scoured hundreds of cognition studies and created “The Hierarchy of Primate Intelligence.” According to Deaner’s hierarchy, orangutans are smarter than chimpanzees, and they are the smartest primates after humans, and spider monkeys are the fourth smartest primates after orangutans and chimps, with gorillas being the fifth smartest.
Orangutans can perform several tasks that most apes cannot do. Researchers in Leipzig Zoo in Germany observed “calculated reciprocity”—meaning they “weigh the costs and benefits of gift exchanges.” They have also been observed creating a distraction in order to steal food from one another, essentially showing them pick-pocketing. They’ve also been seen using leaves to amplify calls, holding them to their mouth when they squeak, enabling them to deceive one another to sound like a larger ape. Scientists argue that these behaviors make them one of the most self-aware wild animals that have ever been observed.
Orangutans can learn up to 40 hand signs to communicate in sign language, and can do the same with their feet.
Medicinal Plants Used by Animals
The Natural History Museum reports that the use of medicinal plants by animals—known as zoopharmacognosy—is believed to be used by a variety of different species to treat their illnesses and injuries to some degree. But in most cases, it’s unclear if it’s prompted by instinct rather than learned behavior.
Blue-headed parrots, for instance, frequently lick clay which helps them absorb the toxins from unripe fruits they’ve eaten. Galápagos finches have been observed rubbing the leaves of the Galápagos guava tree on their feathers. These are rich in chemicals that repel mosquitoes and fly larvae.
Wild animals have been seen eating cannabis, but it’s unclear why they are attracted to it. In the wild, mice and rats eat germinated hemp seeds, while moles, rabbits, foxes, deer, and dogs have been seen eating hemp leaves and stalks. And this doesn’t include insect pests that regularly chow down on cannabis leaves.
Even insects eat different foods that have medicinal properties. Cordyceps and fungal infections are a nightmare (and the inspiration for The Last of Us video game and series) but ants have been observed eating normally unwanted foods that ward off fungal infections.
The new findings about orangutan behavior demonstrate how little we know about ape intelligence.
