Orangutan treats wound with medicinal plant: A first for great apes

Traditionally, self-medication in animals has been limited to observations of them ingesting specific plant parts, often at low frequencies. While wound care behaviors have been documented in some animals, the deliberate use of plants with healing properties remained unseen – until now.

A new study published in Scientific Reports reveals the first instance of a wild Sumatran orangutan actively treating a facial wound with a medicinal climbing plant.

The research, led by cognitive and evolutionary biologists from the Max Planck Institute of Animal Behavior (Germany) and Universitas Nasional (Indonesia), took place at the Suaq Balimbing research site in Sumatra, Indonesia. Home to around 150 critically endangered orangutans, the site provided a unique opportunity to observe their behavior.

The study focused on a male orangutan named Rakus. Researchers noticed a facial wound, likely sustained during a fight with another male. Three days later, Rakus exhibited remarkable behavior. He selectively detached leaves from a climbing plant known locally as Akar Kuning (Fibraurea tinctoria).

After chewing the leaves, Rakus meticulously applied the resulting juice directly onto his wound for several minutes. He then covered the wound entirely with the chewed plant material.

Akar Kuning is traditionally used in Southeast Asian medicine for its anti-inflammatory and pain-relieving properties. Chemical analysis confirmed the presence of compounds known to have antibacterial, antifungal, and antioxidant properties beneficial for wound healing.

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“This behavior suggests an understanding of the plant’s medicinal properties,” says Isabelle Laumer (MPI-AB), lead author of the study. Notably, Rakus only treated the wounded area, further suggesting intentional application.

Interestingly, Rakus also exhibited increased resting behavior during the healing process, potentially linked to the body’s repair mechanisms during sleep.

While the specific cause of Rakus’ behavior remains unclear, the researchers propose two possibilities. The behavior could be an individual innovation – a novel behavior not previously observed in the Suaq orangutan population. Orangutans at Suaq rarely consume Akar Kuning, but accidental contact with the plant while feeding could have led Rakus to experience pain relief, prompting him to repeat the behavior with his wound.

Alternatively, the behavior might originate from Rakus’ natal population. Adult male orangutans disperse from their natal areas, and Rakus’ origin remains unknown. It’s possible that wound treatment with Akar Kuning is a more common practice in his original home range.

This study offers a groundbreaking perspective on self-medication in great apes. It suggests a potential shared evolutionary origin for wound treatment behavior in humans and orangutans. The earliest documented human wound treatment practices date back to 2200 BC, involving cleaning, bandaging, and application of specific wound care substances. The similarities between Rakus’ actions and these early practices raise intriguing questions.

“Our findings suggest a common underlying mechanism for recognizing and applying substances with medicinal properties to wounds,” says Caroline Schuppli, senior author of the study. The possibility that our last common ancestor with orangutans engaged in similar “ointment behavior” is a fascinating avenue for future research.

Further studies are needed to determine how widespread this behavior is among orangutans and other great apes. Additionally, investigating the knowledge transmission within orangutan populations could shed light on whether this behavior is learned or innovative.

This groundbreaking discovery paves the way for a deeper understanding of self-medication in our closest living relatives and the potential evolutionary roots of wound treatment practices across species.

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