In a groundbreaking observation of animal behavior, researchers have documented a wild orangutan named Rakus treating his own injury with the leaves of a medicinal plant, marking a significant milestone in our understanding of nonhuman self-medication. This remarkable event took place in Gunung Leuser National Park in Indonesia, home to some 150 critically endangered Sumatran orangutans.
Rakus, a male orangutan believed to be around 32 years old, first caught the attention of scientists in June 2022 when he was observed sporting a serious facial wound. The injury was thought to have been sustained in a fight with a rival male. Researchers from the Max Planck Institute of Animal Behavior and Universitas Nasional in Indonesia were monitoring the orangutans when they witnessed Rakus engaging in a behavior not previously recorded in wild animals: applying plant juices to his wound.
Following his injury, Rakus chewed the leaves of a plant known locally as Fibraurea tinctoria, or akar kuning, which is renowned for its medicinal properties. This plant has been used by local people for centuries to alleviate various ailments, including pain and inflammation. Observers were astonished to see Rakus intentionally applying the extracts to his injury, effectively creating a makeshift poultice.
“This represents the first known instance of a wild animal actively treating its own wound with a medicinal plant,” said Isabelle Laumer, a cognitive biologist and co-author of the study. Researchers noted that Rakus’s method involved chewing up the leaves without swallowing them, then using his fingers to apply the juices directly to the wound, followed by placing the chewed leaves on top of it as a protective covering.
Some experts regard this behavior as a form of self-medication, an insightful example of how certain animal species might address their own health needs in the wild. Historically, many animals have been observed engaging in self-care behaviors, which scientists now classify as “self-medication.” However, Rakus's behavior transcends typical animal instincts in that it shows a complex understanding or at least an instinctive use of a specific plant recognized for its healing properties.
Laumer’s team closely monitored Rakus’s recovery over the following weeks. They documented that within approximately five days, the wound had closed significantly, and by July 19, roughly a month after the initial incident, the injury had healed completely, leaving behind only a faint scar. Interestingly, infections or other complications were not observed during this period, suggesting that the medicinal plant indeed played a role in promoting healing.
This incident provokes larger questions about the cognitive abilities of great apes and their potential to recognize the medicinal properties of plants in their environment. Previous studies have noted instances where various nonhuman animals, including chimpanzees and bonobos, have used plants to treat ailments or repel parasites, but direct applications for specific injuries were rare.
Jacobus de Roode, a biologist at Emory University not involved in the study, commented, “This is the first time that we’ve observed a wild animal applying a quite potent medicinal plant directly to a wound. It points to the possibility that self-medication may be more widespread among primates than we previously thought.”
Despite these remarkable findings, researchers note that Rakus's behavior was a singular observation, and further studies are necessary to understand whether this kind of self-treatment is common among other orangutans or in different populations. The potential for social learning plays a critical role in this inquiry, as male orangutans, like Rakus, often disperse from their natal areas and do not have opportunities to observe elder individuals.
Tara Stoinski, president and chief scientific officer of the Dian Fossey Gorilla Fund and not involved in the study, emphasized the significance of these findings, “If this behavior exists in some of our closest living relatives, what could that tell us about how medicine first evolved?”
Rakus was not previously known to frequently consume the akar kuning plant, which only featured in a minuscule fraction of his dietary choices—only 0.3% of all feeding scans recorded indicated its consumption. This raises questions: did Rakus stumble upon this healing method by chance, or did he learn it through interactions with other orangutans in different regions?
Throughout their extended study, Rakus and his community have been subjects of interest for years. Researchers have been monitoring orangutans within the Gunung Leuser National Park since 1994, providing a crucial body of observational data on their behavior and ecology.
Ultimately, Rakus's self-medication episode opens up a fascinating dialogue about animal behavior and cognition. This precedent-setting instance encourages an exploration into the depths of animal intelligence, self-care, and potentially even cultural transmission within species.
While this observation remains a landmark moment in animal behavior studies, it highlights the broader implications for conservation efforts. As habitat loss continues to threaten Sumatran orangutans and their ecosystems, understanding how these animals navigate their world can contribute to creating effective strategies to protect them.
