Georgia Allen watched from the edge of a peat-swamp forest in Central Kalimantan as an orangutan peeled back the bark of a Melicope elleryana tree, carefully chewing its fibrous layers before moving to a nearby vine of Leea indica. This wasn’t random foraging—it was a pattern repeated over two decades of observation, one that suggests Bornean orangutans are quietly practicing a form of medicine all their own. Across 20 years of fieldwork, researchers have documented these great apes selectively consuming plants with known antimicrobial, anti-inflammatory, and wound-healing properties—often in precise sequences that go far beyond mere nutrition. The study, published in Scientific Reports, analyzed feeding behaviors of wild orangutans in Indonesian Borneo and found that certain plant combinations appeared together in their diets at rates far exceeding chance, signaling a potential instinctive or culturally transmitted knowledge of healing.

This kind of behavior, known as self-medication, has been observed in chimpanzees, who ingest specific leaves to combat parasites, and in gorillas and gibbons. But this is the first comprehensive evidence suggesting orangutans do the same. What makes the findings particularly compelling is that many of the plants consumed—such as Litsea elliptica and Dialium corbisieri—are not dietary staples. They appear only occasionally in the orangutans’ meals, often during times of visible illness or stress, reinforcing the idea that they’re being used for targeted health benefits. Some of these same plants are also used by Indigenous communities in Borneo for treating fevers, infections, and skin conditions, creating a powerful overlap between traditional human knowledge and animal behavior.

The research was led by Georgia Allen during her master’s degree in conservation and biodiversity at the University of Exeter. “At this stage, we cannot say that orangutans are consciously ‘diagnosing’ themselves in the same way humans would,” Allen said. “However, our findings suggest they selectively consume certain plants with medicinal properties in ways that go beyond simple nutrition.” The implications stretch beyond primate behavior—they underscore the value of preserving both rainforest ecosystems and the Indigenous knowledge systems that have long coexisted with them. As deforestation and palm oil expansion continue to threaten Central Kalimantan’s peat-swamp forests, the loss isn’t just of trees, but of living pharmacies used by both animals and people.

Understanding how orangutans interact with their botanical environment opens new doors for conservation and even medical research. If these apes can identify plant combinations that fight infection or reduce inflammation, studying their choices could reveal novel therapeutic pathways. More importantly, it challenges the human-centric view of medicine, reminding us that healing wisdom exists throughout the natural world. As the forest hums with life, the quiet choices of a single orangutan may hold lessons for global health—and a deeper respect for the intelligence embedded in the wild.