An orangutan named Rakus went through a tough time in the summer of 2022.
Researchers heard a fight between male orangutans in the treetops of a rainforest in Sumatra, Indonesia; a day later, they spotted Rakus sporting a pink wound under his right eyelid.
A piece of flesh the size and shape of a puzzle piece was missing. When Rakus, who is probably around 30 years old, made a long call, researchers noticed another wound inside his mouth.
Over the next few days, researchers followed Rakus remotely and saw something so surprising that they ended up reporting it in detail in the journal Scientific Reports.
According to their study, published Thursday, Rakus were observed repeatedly chewing the leaves of a particular vine over several days. The climbing vine is not a typical food for orangutans, but it is known to humans as a pain reliever.
On at least one occasion, Rakus made a paste from the chewed leaves and applied it to his face. This is the first time an animal has been seen applying medicine to a skin wound.
“This is the first documentation of external self-medication — the application of leaves, I would say, as a poultice, as humans do to treat wounds and pain,” said Michael Huffman, an associate professor at the Research Center on wildlife from Kyoto University in Kyoto. Japan, which was not involved in the new study.
Rakus’ wound never showed signs of infection and it closed within a week.
This discovery is new evidence that orangutans are capable of identifying and using pain-relieving plants. A growing body of research suggests that other animal species also self-medicate, with varying levels of sophistication.
The researchers behind the study believe that great apes’ ability to identify drugs and treat wounds may trace back to a common ancestor with humans.
New evidence that orangutans self-medicate
The discovery was only possible because Rakus spends his days in a protected area of rainforest called the Suaq Balimbing Research Area, in Indonesia’s Gunung Leuser National Park.
Researchers have been observing orangutans there since 1994. Today, around 150 of them live in the region. Rakus, which was first observed there in 2009, is either a resident or a frequent visitor.
Scientists often follow an orangutan in the area from early in the morning – when it leaves its night nest – until it builds a new night nest about 12 hours later.
“We don’t disturb the orangutans,” said the new study’s author, Isabelle Laumer, a primatologist and cognitive biologist at the Max Planck Institute of Animal Behavior in Germany. “They completely tolerate us following them.”
Laumer said researchers have never observed orangutans in the area self-medicating like Rakus did and it was unclear how he developed the behavior.
It’s possible that Rakus learned to treat his injury through “individual innovation,” Laumer said, after accidentally touching a finger to a wound with the pain-relieving leaf juice. Or it may have learned this behavior culturally from other orangutans very early in its life.
Orangutans learn socially and have been shown to be capable of using tools. They develop sophisticated knowledge about foods from their mothers.
“They learn a lot, like, about what types of fruits to eat, where to find them, when to find them, when they’re ripe, how to process them,” Laumer said. “Some orangutans feed on up to 400 different plants. … That’s some pretty in-depth knowledge that they really need to learn.”
Did humans learn medicinal plans from animals?
Evidence for animal self-medication has grown in recent decades.
In the 1960s, famous primatologist Jane Goodall noticed that chimpanzees in Tanzania were eating the entire leaves of a plant later identified as a type of Aspilia shrub. Decades later, Huffman wrote a paper describing how a different population of chimpanzees ate the bitter pith of a particular daisy, but only rarely and when other behaviors suggested they were sick.
Researchers believe chimpanzees evolved such behaviors to treat or prevent parasites.
In the 1990s and 2000s, extensive research identified new examples of self-medication.
A remarkable 2008 study of Bornean orangutans documented three females rubbing their bodies with a paste from the chewed Dracaena cantleyi plant, which local indigenous people use to relieve joint and bone pain.
Huffman said he believes all animal species self-medicate to some extent. Researchers have even documented this practice in insects.
“It shows us that animals are in control of their lives,” he said. “That they can behave in flexible ways, adapted to certain circumstances that depend on their very survival. »
He hypothesized that ancient humans derived the ability to identify medicinal plants and substances from close observations of animals.
“Many of the medicines that humans have used throughout our history as a species have come from our close connection to nature and our seeking advice from other animals and extrapolating what we we learned,” Huffman said. “I don’t know of any plant that an animal uses as medicine that isn’t also used by humans. And I think it was humans who learned from animals.
Laumer said his team’s findings — in a species 97 percent genetically similar to humans — could provide insight into how ancient primates developed their inclination to seek out medicines.
“It’s possible that our last common ancestor already showed similar behaviors,” she said.
Laumer added that the new findings also show how much can be learned from orangutans, which are considered critically endangered. The rainforests where Sumatran orangutans live are disappearing as land is converted to agriculture and climate change intensifies wildfires.
The latest estimates, from 2016, suggest there are fewer than 14,000 left.
This article was originally published on NBCNews.com
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