Orangutan Self-Medication: Wild Primate Treats Wound with Medicinal Plant

In a groundbreaking observation that bridges the gap between human and animal medicine, biologists have documented a wild Sumatran orangutan intentionally treating an open facial wound using a medicinal plant. This behavior marks the first scientific record of a wild animal precisely treating a wound with a plant species known to have biologically active properties.

The Discovery of Rakus and the Wound

The observation took place at the Suaq Balimbing research site within Indonesia’s Gunung Leuser National Park. Researchers from the Max Planck Institute of Animal Behavior and Universitas Nasional in Jakarta were monitoring a male Sumatran orangutan named Rakus.

In June 2022, observers noticed that Rakus had sustained a significant open wound on his right cheek below the eye. Biologists believe this injury likely resulted from a fight with a rival male, as loud “long calls” indicating dominance struggles were heard in the area shortly before the injury appeared.

Three days after the injury occurred, Rakus began exhibiting a behavior never before seen in this context. He began selectively feeding on the stem and leaves of a liana plant. However, rather than simply eating the plant for nutrition, Rakus began a systematic process of self-medication.

The Treatment Process

The researchers, led by primatologist Isabelle Laumer, watched as Rakus engaged in a deliberate, multi-step medical procedure that lasted roughly seven minutes.

• Extraction: Rakus chewed the leaves of the plant to produce a juice but did not swallow all of it.
• Application: He repeatedly used his fingers to apply the plant juice directly onto his open facial wound.
• Protection: After applying the liquid, Rakus took the chewed-up plant matter (the solid leaf mesh) and applied it over the wound. He effectively created a “poultice” or bandage, completely covering the injury.

This was not a one-time accidental brush with a leaf. Rakus repeated this behavior the following day, reinforcing the idea that the action was intentional and targeted toward healing the injury.

The Medicinal Plant: Akar Kuning

The plant Rakus selected is chemically significant. He utilized Fibraurea tinctoria, commonly known as Akar Kuning. This climbing liana is well-known in traditional medicine across Southeast Asia.

Analyses of Fibraurea tinctoria show that it contains furanoditerpenoids and protoberberine alkaloids. These chemical compounds provide powerful medicinal benefits:

• Antibacterial properties: Helps prevent infection in open wounds.
• Anti-inflammatory effects: Reduces swelling and redness.
• Analgesic qualities: Acts as a pain reliever.
• Antifungal: Prevents fungal growth on the skin.

Local human populations use this exact plant to treat various ailments, including dysentery, diabetes, and malaria. The fact that Rakus chose this specific plant—which is rarely eaten by orangutans in this area—suggests a high level of cognitive awareness regarding the plant’s soothing or healing effects.

Recovery and Results

The treatment appeared to be highly effective. Following the application of the plant paste, researchers continued to monitor the wound. There were no signs of infection, which is a common risk for wild animals living in humid, tropical environments.

Within five days of the treatment, the wound had closed. After one month, the injury was fully healed, leaving only a faint scar.

During the recovery period, researchers also noted that Rakus rested more than usual. This conservation of energy, combined with the medicinal application, likely accelerated the healing process. Sleep is a critical component of immune response in primates, and Rakus appeared to adopt a strategy of “bed rest” alongside his topical treatment.

Implications for Cognitive Evolution

This finding, published in Scientific Reports in May 2024, challenges our understanding of animal intelligence and the origins of medicine.

Prior to this, self-medication in animals (zoopharmacognosy) was largely observed as swallowing leaves to clear parasites or rubbing fur with insects. For example, chimpanzees have been seen applying crushed insects to wounds. However, the use of a plant with proven active chemical compounds to treat a specific external injury suggests a more advanced level of understanding.

There are two main theories on how Rakus acquired this knowledge:

1. Individual Innovation: Rakus may have discovered the pain-relieving effects accidentally while eating the plant and then intentionally applied it to the wound.
2. Social Learning: It is possible Rakus learned this behavior from watching other orangutans in his birth population before migrating to the Suaq Balimbing area.

Because this behavior has not been observed in other orangutans at this specific research site in 21 years of study, researchers suspect it might be a learned behavior or a rare innovation. This discovery suggests that the cognitive foundations for medicine might be much older than humanity itself, potentially shared by the last common ancestor of great apes and humans.

Frequently Asked Questions

What was the name of the plant the orangutan used? The orangutan used Fibraurea tinctoria, a climbing liana plant known locally as Akar Kuning. It is known to have antibacterial, anti-inflammatory, and pain-relieving properties.

Did the wound heal successfully? Yes. The wound showed no signs of infection and closed within five days. It was completely healed within one month of the treatment.

Is this the first time an animal has treated a wound? While other animals have been seen tending to wounds (such as licking them or applying insects), this is the first scientific documentation of a wild animal applying a plant with known medicinal properties specifically to treat an open wound.

Where did this observation take place? The observation occurred at the Suaq Balimbing research site in the Gunung Leuser National Park, located in South Aceh, Indonesia.

How did the orangutan know to do this? Scientists are unsure if this was individual innovation (trial and error) or social learning (mimicking others). Since Rakus is a flanged male who migrated to the area, he may have learned the behavior in his region of origin.