On June 22, 2022, researchers at the Suaq Balimbing research station in Sumatra’s Gunung Leuser National Park heard a series of long calls from the canopy—the vocalizations male orangutans produce during dominance confrontations. The next day, they noticed that a flanged male orangutan named Rakus had a fresh wound on his right cheek, just below the eye, probably from a fight with a neighboring male. Three days later, they watched him do something no wild animal had ever been documented doing: he selected a specific plant—a climbing vine called Fibraurea tinctoria, known locally as Akar Kuning—ripped off its leaves, chewed them for 13 minutes, and then spent seven minutes applying the resulting juice directly to his wound with his fingers. He didn’t swallow the leaves during the application phase. When flies began landing on the wound, he covered it entirely with the chewed plant material, creating a poultice. The next day, he returned to the same plant and ate more leaves. Within five days, the wound closed. By July 19—roughly a month after the injury—only a faint scar remained. No infection developed.
The paper, published in Scientific Reports in May 2024 by Isabelle Laumer and Caroline Schuppli of the Max Planck Institute of Animal Behavior, called it “the first known case of active wound treatment in a wild animal with a medical plant.” The emphasis on “active” is deliberate. Animals have been observed swallowing plants with medicinal properties before—chimpanzees chew bitter pith, gorillas and bonobos swallow rough leaves whole to mechanically dislodge intestinal parasites, Bornean orangutans rub chewed plants on their limbs. But those behaviors involve ingestion or generalized application. What Rakus did was topical, targeted, and sequential: he applied the plant’s juice specifically to the wound, on no other body part, repeated the application multiple times, and then covered the wound with plant material. He treated his own injury the way a human would treat a cut—clean it, apply medicine, bandage it.
Why Akar Kuning matters
Fibraurea tinctoria is not a random plant. It’s a climbing liana found across Southeast Asia—Indonesia, Malaysia, Thailand, Vietnam—and it’s used extensively in traditional medicine to treat dysentery, diabetes, malaria, and infections. Chemical analysis of the plant has identified furanoditerpenoids and protoberberine alkaloids with documented antibacterial, anti-inflammatory, antifungal, antioxidant, and analgesic properties. The plant also contains jatrorrhizine, which has antimicrobial and anticancer properties, and palmatine, which has anti-inflammatory and antiviral effects. This isn’t a plant that happens to have healing properties. It’s a plant whose healing properties are well-characterized enough that humans have been using it medicinally for centuries.
Rakus’s population at Suaq Balimbing rarely eats it. In 21 years and roughly 390,000 feeding observations at the site, Fibraurea tinctoria appeared in only 0.3 percent of feeding scans. This wasn’t a plant the orangutan was already eating when he happened to touch his wound. He selected it specifically, used it in a way that doesn’t correspond to normal feeding behavior, and applied it exclusively to the injury. The researchers were careful to note that in 21 years and 28,000 observation hours, they had never previously seen an orangutan use leaves to treat a wound.
How deliberate was it?
This is the question the paper addresses directly and honestly. The behavior appeared intentional: Rakus selectively treated only his facial wound, not other body parts. He repeated the application multiple times. He used both the juice (liquid application) and the solid plant material (poultice). The entire process—feeding on the plant, applying the juice, covering the wound—took a considerable amount of time and was sustained across two consecutive days. The sequence is difficult to explain as accidental.
But the researchers offer two possible origin stories, and they’re transparent about not being able to distinguish between them. The first is “accidental individual innovation”—Rakus may have been feeding on the plant, accidentally touched his wound while chewing, felt immediate pain relief from the plant’s analgesic effects, and then repeated the behavior because it worked. Under this model, the behavior was discovered by accident and reinforced by its consequences, which is how a lot of animal tool use and self-medication originates. The second possibility is social learning—Rakus wasn’t born at Suaq Balimbing. Male orangutans disperse from their natal area during or after puberty, sometimes traveling long distances. Rakus may have observed the behavior in his birth population, carried the knowledge across dispersal, and applied it when the situation required. If so, the behavior represents a cultural tradition transmitted between individuals, not an individual invention.
The researchers can’t determine which explanation is correct because they don’t know where Rakus was born or what behaviors are practiced in that unknown population. This ambiguity is frustrating but honest—and it’s the central challenge of studying animal self-medication in the wild. You’re observing rare behaviors in long-lived animals across vast landscapes with limited coverage, and the most interesting questions (was it invented or learned?) require data from populations you may never have access to.
The broader landscape of animal self-medication
Rakus’s wound treatment is the most dramatic documented case, but self-medication in animals—zoopharmacognosy—is a recognized field with decades of evidence across multiple species and continents.
Chimpanzees at multiple African field sites chew the bitter pith of Vernonia amygdalina, a plant with antiparasitic compounds, when they’re suffering from intestinal infections. The behavior is targeted: chimps eat it when sick and avoid it when healthy, suggesting they’re responding to internal cues rather than eating it as a regular food. Gorillas, chimpanzees, and bonobos swallow rough, hairy leaves from Aspilia and other plants whole and without chewing—the leaves pass through the digestive tract intact and physically dislodge intestinal parasites, which researchers have confirmed by examining fecal samples and finding parasites wrapped in leaf material. This is mechanical self-medication: the plant’s physical properties, not its chemistry, provide the therapeutic effect.
Bornean orangutans have been observed rubbing chewed leaves of Dracaena cantleyi on their limbs, producing a lather that may have anti-inflammatory or antiparasitic properties. Capuchin monkeys rub citrus fruits and certain plants on their fur, potentially as insect repellent. Some moth species lay their eggs on alkaloid-rich plants when infected by parasitoid wasps, effectively medicating their offspring by ensuring the larvae consume antiparasitic compounds. Even fruit flies preferentially consume alcohol-containing food when infected by parasitoid wasps—the ethanol kills the wasp larvae developing inside them.
The pattern across these examples is consistent: animals with no understanding of chemistry, pharmacology, or infection select specific substances with specific biological activity in response to specific health conditions. The behavior isn’t random foraging. It’s condition-dependent, substance-specific, and in many cases targeted to the affected body region. The question isn’t whether animals self-medicate. They do. The question is what cognitive mechanism enables it.
What it means for the origins of medicine
The earliest known human medical manuscript, from Mesopotamia around 2200 BCE, describes wound treatment with plant-based remedies. But if a Sumatran orangutan—separated from the human lineage by roughly 14 million years of evolution—independently applies a biologically active plant to a wound and covers it with a poultice, the implication is that the cognitive capacity for wound treatment predates the human lineage entirely. Laumer and Schuppli suggest that “medical wound treatment may have arisen in a common ancestor shared by humans and orangutans,” and that the behavior observed in Rakus may reflect deep evolutionary roots rather than a recent invention.
The alternative—that Rakus and the Mesopotamian scribe independently arrived at the same solution—is possible but requires the same cognitive prerequisites: recognizing that a wound needs treatment, selecting a substance with appropriate properties, applying it specifically to the injury, and sustaining the behavior long enough for healing to occur. Whether the common ancestor had this capability or whether it evolved convergently in hominids and orangutans, the conclusion is the same: medicine didn’t start with humans. It started with primates who paid attention to what made them feel better and repeated it.
Traditional healers in Indonesian Borneo have reportedly learned plant-based remedies by observing orangutan behavior—the knowledge transmission running from ape to human rather than the reverse. If Rakus learned his wound treatment from his natal population, and if human populations learned similar treatments from watching orangutans, then the same medicinal knowledge has been transmitted across species boundaries in both directions. The forest pharmacy has always been open. The question is who figured out the inventory first.
We cover orangutan self-medication alongside baboon politics, ant collective intelligence, and the full landscape of animal cognition across our Animal Culture & Knowledge course—including why the first pharmacist may not have been a person. It may have been a primate with a cheek wound and the sense to reach for the right vine.