Wild orangutan treats his facial wound with a healing plant 

Biologists from the Max Planck Institute of Animal Behavior (MPI-AB) in Germany and the National University in Indonesia have discovered a male Sumatran orangutan using natural remedies to treat a facial wound. 

This finding marks the first recorded instance of an animal applying healing plants to wounds, suggesting that such medical behaviors might have originated from a common ancestor shared by humans and orangutans.

The researchers noted that while self-medication through ingestion is common in various animal species, the application of biologically active substances to wounds has not been previously documented outside of human practices. 

Orangutan treats his own wound 

The experts, who led the study at the Suaq Balimbing research site in Indonesia – a protected rainforest home to about 150 critically endangered Sumatran orangutans – witnessed the orangutan, named Rakus, engage in this unique behavior.

“During daily observations of the orangutans, we noticed that a male named Rakus had sustained a facial wound, most likely during a fight with a neighboring male,” reported lead author Isabelle Laumer, a primatologist at MPI-AB.

Medicinal plant leaves 

Rakus was observed selecting leaves from a liana known as Akar Kuning (Fibraurea tinctoria), chewing them, and applying the sap directly to his wound. He then covered the wound with the masticated leaves. 

This plant is recognized in traditional medicine for its anti-inflammatory and pain-relieving properties and contains compounds such as furanoditerpenoids and protoberberine alkaloids, known for their antibacterial and antioxidant activities.

“This and related liana species that can be found in tropical forests of Southeast Asia are known for their analgesic and antipyretic effects and are used in traditional medicine to treat various diseases, such as malaria,” Laumer explained.

Successful wound treatment 

The subsequent observations revealed no infection, and the wound had closed within five days. 

“Interestingly, Rakus also rested more than usual when being wounded. Sleep positively affects wound healing as growth hormone release, protein synthesis, and cell division are increased during sleep.”

Innovation within the orangutan population 

The researchers examined the intentionality and emergence of such behavior, emphasizing its potential innovation within the orangutan population at Suaq. 

“The behavior of Rakus appeared to be intentional as he selectively treated his facial wound on his right flange, and no other body parts, with the plant juice. The behavior was also repeated several times, not only with the plant juice but also later with more solid plant material until the wound was fully covered. The entire process took a considerable amount of time,” Laumer said.

According to senior author Caroline Schuppli, an expert in cognitive evolution and animal behavior at MPI-AB, while the orangutans at Suaq rarely consume this plant, incidental contact during feeding might have introduced its therapeutic effects. 

“It is possible that wound treatment with Fibraurea tinctoria by the orangutans at Suaq emerges through individual innovation,” she explained.

Evolutionary roots of wound treatment 

The study not only provides the first evidence of great apes managing wounds with medicinal plants but also invites further exploration into the evolutionary roots of such behavior, hinting at a shared ancestral trait between humans and apes in recognizing and utilizing natural substances for medical purposes.

“As forms of active wound treatment are not just human, but can also be found in both African and Asian great apes, it is possible that there exists a common underlying mechanism for the recognition and application of substances with medical or functional properties to wounds and that our last common ancestor already showed similar forms of ointment behavior,” Schuppli concluded.

More about Sumatran orangutans

Sumatran orangutans are a critically endangered species of great ape native to the island of Sumatra in Indonesia. Known scientifically as Pongo abelii, they are one of the three species of orangutans. Sumatran orangutans are distinguished by their lighter color and slightly smaller size compared to their Bornean counterparts. 

Lifestyle and reproduction 

These apes are predominantly arboreal, spending most of their lives in the trees of tropical rainforests. Their diet is primarily frugivorous, consisting largely of fruits, but also includes leaves, bark, and insects.

These orangutans have a slow reproductive rate, which contributes to their vulnerability. Females give birth to a single offspring only once every eight years or so, making population recovery a slow process. 

Primary threats 

The primary threats to their survival include habitat loss due to deforestation for palm oil plantations, logging, and agriculture. Illegal wildlife trade and conflict with humans, when orangutans venture into farmlands, also pose significant risks.

Conservation 

Conservation efforts are in place to protect the Sumatran orangutan, involving habitat preservation, anti-poaching patrols, and rehabilitation centers that rescue and return orangutans to the wild. International and local organizations collaborate to raise awareness and funds to support these initiatives, aiming to secure a future for the species in their natural habitat. 

Despite these efforts, the Sumatran orangutan remains one of the world’s most endangered primates, with an estimated population of just over 14,000 individuals.

The study is published in the journal Nature Scientific Reports.

Image Credit: Armas / Suaq Project

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