Sumatran orangutan heals himself after applying plant to his wound

In June 2022, a male Sumatran orangutan named Rakus was wounded below his right eye, apparently during a fight with another male orangutan at the Suaq Balimbing research site, a protected rainforest area in Indonesia. But what Rakus did three days later really caught the attention of scientists.

Researchers last week described observing how Rakus appeared to treat the wound, using a plant known for its pain-relieving properties and for supporting wound healing, due to its antibacterial*, anti-inflammatory*, antifungal* and antioxidant* qualities.

The orangutan chewed the plant’s leaves to produce a liquid that Rakus repeatedly smeared on the wound, then put the chewed-up plant material directly on the injury, much like a wound dressing administered by doctors, according to primatologist* and cognitive biologist* Dr Isabelle Laumer of the Max Planck Institute of Animal Behaviour in Germany.

Rakus also ate the plant, an evergreen vine commonly called Akar Kuning, added Dr Laumer, lead author of the study published in the journal Scientific Reports. This plant is rarely eaten by orangutans in this peat swamp forest area, home to about 150 critically endangered* Sumatran orangutans.

“To our knowledge, this is the first documented case of active wound treatment with a plant species with medical properties by a wild animal,” said study senior author Dr Caroline Schuppli, an evolutionary biologist* at the institute.

Rakus, believed to have been born in 1989, is a flanged* male, with large cheek pads on both sides of the face – secondary male sexual characteristics. Rakus was one of the area’s dominant* males.

The researchers said the orangutan’s wound self-treatment did not appear to be coincidental.

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

The wound never showed signs of infection and closed within five days, the researchers said.

“The observation suggests that the cognitive* capacities that are needed for the behaviour – active wound treatment with plants – may be as old as the last common ancestor* of orangutans and humans,” Dr Schuppli said. “However, what these cognitive capacities exactly are remains to be investigated. Whereas this observation shows that orangutans are capable of treating their wounds with plants, we don’t know to what extent they understand the process.”

The last common ancestor of orangutans and humans lived about 13 million years ago.

Orangutans are one of the world’s great apes – the closest living relatives of humans – alongside chimpanzees, bonobos* and gorillas. Orangutans are the least closely related to humans of them all but still share approximately 97 per cent of our DNA*.

“It is possible that wound treatment with (this particular plant Akar Kuning) emerges through accidental individual innovation*,” Dr Laumer said. “Individuals may accidentally touch their wounds while feeding on (Akar Kuning) and thus unintentionally apply the plant’s juice to their wounds. But it may also be that Rakus has learned this behaviour from other orangutans in his birth area.”

The plant, widely distributed across China, Indonesia, Malaysia, Thailand, Vietnam and other parts of Southeast Asia, is used in traditional medicine* to treat conditions such as malaria*.

Orangutan means “person of the forest” in the Indonesian and Malay languages, and these apes are the world’s biggest arboreal mammal*. Orangutans, adapted to living in trees, live more solitary lives than other great apes, sleeping and eating fruit in the forest canopy and swinging from branch to branch.

“Orangutans have high cognitive abilities, in particular in the area of physical cognition*,” Dr Schuppli said. “They are known to be excellent problem-solvers. Wild orangutans acquire their skill sets via observational social learning, and skills get passed on from generation to generation. The population where this observation was made is known for its rich cultural repertoire*, including tool use in different contexts.”

POLL

GLOSSARY

• antibacterial: directed or effective against bacteria, intended to kill or reduce the harmful effects of bacteria, especially when used on the skin
• anti-inflammatory: substance or treatment used to prevent or reduce swelling
• antifungal: medicines that kill or stop the growth of fungi (the plural of fungus) that cause infection
• antioxidant: natural or man-made substances that may stop or slow some types of cell damage
• primatologist: scientist who studies the behaviour, biology, evolution, and taxonomy of non-human primates
• cognitive biologist: scientist who studies the mental processes of animals as part of their life on Earth
• critically endangered: a species facing an extremely high risk of extinction in the wild
• evolutionary biologist: scientists specialising in understanding how species have evolved and changed over time
• flanged: refers to male orang-utans with big cheek pads on the sides of the face and a large pendulous throat sack under the chin
• dominant: has power and influence over others, controlling, more important or stronger than others
• cognitive: the mental process involved in knowing, learning, and understanding things
• ancestor: relative from an earlier time in history, sometimes from a very long time ago
• bonobos: small, intelligent African ape with black or brown fur, similar to a chimpanzee but slightly smaller
• DNA: the genetic information inside the cells of the body that helps make people who they are
• innovation: process of change, using new ideas, methods and tools
• traditional medicine: knowledge, skills and practices based on theories, beliefs and experiences indigenous to different cultures
• malaria: preventable, curable but potentially life-threatening tropical disease transmitted to humans by some types of mosquitoes
• arboreal mammal: animals that live in trees
• cognition: the mental process of thinking, learning, remembering, being aware of surroundings and using judgment
• repertoire: all the things of a particular kind that a person, animal or thing is capable of doing

EXTRA READING

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Taking selfies with endangered mountain gorillas

Great apes just got greater

Big Bobo meets mini-me

QUICK QUIZ

1. How did Rakus end up with the wound in the first place?
2. What is Suaq Balimbing and where is it?
3. What are the four qualities of the plant Rakus used that support wound healing?
4. Orangutans share was percentage of human DNA?
5. What does “orangutan” mean in Indonesian and Malay?

LISTEN TO THIS STORY

CLASSROOM ACTIVITIES
1. Akar Kuning plant
The Akar Kuning plant that Rakus the orangutan used to heal the wound on his face is known for its pain-relieving properties and for supporting wound healing, due to its antibacterial, anti-inflammatory, antifungal and antioxidant qualities.

What do you think humans today could use this plant for?

Do you think it’s used in modern day medicine?

What could you use this plant for at home?

How do you think Rakus the orangutan knew to use it on the sore below his eye?

Time: allow 20 minutes to complete this activity
Curriculum Links: English, Science, Personal and Social, Critical and Creative Thinking

2. Extension
Orangutans have high cognitive abilities and are excellent problem-solvers. What problem or task would you like to present to an orangutan to see if they can figure it out or solve it?

Time: allow 10 minutes to complete this activity
Curriculum Links: English, Science, Personal and Social, Critical and Creative Thinking

VCOP ACTIVITY
Imaginative dialogue
Imagine you were there during the event being discussed in the article.

Create a conversation between two characters from the article – you may need or want to include yourself as one of the characters. Don’t forget to try to use facts and details from the article to help make your dialogue as realistic as possible.

Go through your writing and highlight any punctuation you have used in green. Make sure you carefully check the punctuation used for the dialogue and ensure you have opened and closed the speaking in the correct places.