Central Kalimantan, Indonesia – New long-term research shows that orangutans in Borneo actively select plants with antimicrobial, anti-inflammatory, and wound-healing properties.

The findings are based on 20 years of observations of orangutans living in a peat-swamp forest, where scientists tracked their feeding behavior and plant choices.

Researchers found that the animals do not simply consume plants randomly. Instead, they appear to combine certain plant species in specific sequences, a pattern consistent with self-medicating behavior seen in other animals.

Some of the plants identified contain compounds linked to antimicrobial, anti-inflammatory, and wound-healing effects. Many of these plants are not major components of the orangutan diet, suggesting they may be eaten for specific benefits rather than everyday nutrition.

The study also noted that some plant combinations appeared far more frequently than would be expected by chance, indicating a deliberate pattern in their feeding behavior.

Scientists say it is not yet known how orangutans learn this behavior. It may be instinctive or passed down through generations of social learning.

“At this stage, we cannot say that orangutans are consciously ‘diagnosing’ themselves in the same way humans would,” said Georgia Allen, who led the study during her Master’s research at the University of Exeter.

“However, our findings suggest they selectively consume certain plants with medicinal properties in ways that go beyond simple nutrition,” she added.

Allen also noted that similar self-medicating behavior has been observed in chimpanzees, bonobos, gibbons, and gorillas, including the use of plants that help reduce internal parasite infections.

The research also highlights that some of the same plants are used by Indigenous communities for medicinal purposes, emphasizing the importance of preserving traditional knowledge alongside biodiversity conservation.

The study was conducted under supervision from researchers including Dr Kimberley Hockings and Dr Elodie Freymann, and was initiated by Dr Helen Morrogh-Bernard in collaboration with the Orangutan Behaviour Project and partner institutions.

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