An orangutan named Rakus fell on hard times 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 with a pink wound below his right eyelid.
A piece of meat the size and shape of a puzzle piece was missing. When Rakus, who is probably in his 30s, let out a long call, researchers noticed another wound inside his mouth.
Over the next few days, researchers followed Rakus from a distance – and saw something so surprising that they ended up reporting it in detail in the journal Scientific Reports.
According to the study, published Thursday, Rakus was observed repeatedly chewing the leaves of a particular liana plant over several days. The 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.
“It’s 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, associate professor at Kyoto University’s Wildlife Research Center in Japan, which was not involved in the new study.
Rakus’ wound never showed signs of infection and closed within a week.
The discovery is new evidence that orangutans are able to identify and use 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 the great apes’ ability to identify medicines and treat wounds may date 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 tropical forest area called the Suaq Balimbing Research Area, in Gunung Leuser National Park, Indonesia.
Researchers have been observing orangutans there since 1994. Today, about 150 live in the area. Rakus, which was first observed there in 2009, is a resident or frequent visitor.
Scientists often follow an orangutan in the area from early morning – when it leaves its night nest – until it builds a new night nest around 12 hours later.
“We didn’t disturb the orangutan,” said one of the new study’s authors, Isabelle Laumer, a primatologist and cognitive biologist at the Max Planck Institute for Animal Behavior in Germany. “They completely tolerate us following them.”
Laumer said researchers had never observed orangutans in the area self-medicating like Rakus did and that it was unclear how he developed this behavior.
It’s possible that Rakus learned to treat his wound through “individual innovation,” Laumer said, after accidentally touching a finger to a wound with the pain-relieving leaf juice. Or he may have learned this behavior culturally, from other orangutans, early in life.
Orangutans learn socially and have been shown to be capable with tools. They develop sophisticated knowledge about their mothers’ foods.
“They learn a lot about, for example, what types of fruits to eat, where to find them, when to find them, when they are ripe, how to process them,” Laumer said. “Some orangutans feed on up to 400 different plants. … This is pretty intensive knowledge that they really need to acquire.”
Did humans learn about medicinal plans from animals?
Evidence of animal self-medication has increased in recent decades.
In the 1960s, famous primatologist Jane Goodall noticed that chimpanzees in Tanzania ate whole leaves from 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 part of a specific daisy, but only rarely and when other behaviors suggested they were sick.
Researchers believe that chimpanzees developed such behaviors to treat or prevent parasites.
In the 1990s and 2000s, a flurry of research identified additional examples of self-medication.
A notable 2008 study of Borneo orangutans documented three women rubbing their bodies with a chewed Dracaena cantleyi plant paste, which local indigenous people use to treat joint and bone pain.
Huffman said he believes all animal species self-medicate to some degree. Researchers have even documented the practice in insects.
“This shows us that animals have control over their lives,” he said. “That they can behave in ways that are flexible, that are adaptable to certain circumstances that come down to their own survival.”
He theorized that ancient humans obtained the ability to identify plants and medicinal substances from close observations of animals.
“Many of the medicines that humans have used in our history as a species have come from our close connection to nature and from seeking advice from other animals and extrapolating what we learn,” Huffman said. “I don’t know of any plant that an animal has used 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 that is 97% genetically similar to humans – could offer insight into how ancient primates developed their penchant for seeking out medicines.
“It is possible that our last common ancestor already exhibited similar forms of ointment behavior,” she said.
Laumer added that the new findings also show how much can be learned from critically endangered orangutans. 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 less than 14,000 remain.
This article was originally published in NBCNews. with
