by An orangutan named Rakus hit a rough patch in the summer of 2022.
Researchers have heard a fight between male orangutans in the treetops of the rainforest in Sumatra, Indonesia; The next day, they saw Rakus wearing a pink wound under his right eyelid.
A chunk of meat about the size and shape of a puzzle piece was missing. When Rakus, most likely in his 30s, made a long call, the researchers noticed another wound inside his mouth.
Over the next few days, the researchers followed Rakus from afar – and saw something so surprising that they ended up reporting it in detail in the journal Scientific Reports.
According to their study, published on Thursday, Rakus were observed repeatedly chewing on the leaves of a specific liana plant over several days. Climbing vine is not a common food for orangutans, but is known to humans as a pain reliever.
On at least one occasion, Rakus made a paste of the chewed leaves and applied it to his face. This is the first time an animal has been seen healing a skin wound.
“This is the first documentation of external self-medication – the use of leaves, I would argue, as poultices, as people do to treat wounds and pains,” said Michael Huffman, associate professor at the Wildlife Research Center at Kyoto University in Japan, who were not involved in the new study.
Rakus’ wound never showed signs of infection, and it closed within a week.
The discovery is new evidence that orangutans are able to recognize and use pain-relieving plants. A growing body of research suggests that other animal species also self-medicate, with varying degrees of sophistication.
The researchers behind the study think that the apes’ great ability to recognize medicines and treat wounds could be traced back to a shared ancestor with humans.
New evidence that orangutans self-medicate
The discovery was only possible because Rakus spends his days in a protected area of the rainforest called Suaq Balimbing research area, in Gunung Leuser National Park in Indonesia.
Researchers have been observing orangutans there since 1994. Today, about 150 call the area home. Rakus is a frequent resident or visitor, first observed there in 2009.
Scientists often follow an individual orangutan in the area from early morning – when it leaves its night nest – until it builds a new night nest about 12 hours later.
“We don’t interfere with the orangutan,” said the author of the new study, Isabelle Laumer, a primatologist and cognitive biologist at the Max Planck Institute for Animal Behavior in Germany. “They fully accept us following them.”
Laumer said that researchers had never observed orangutans in the area self-medicate as Rakus did and it was not clear how he developed the behavior.
Rakus may have learned to treat his wound through “individual innovation,” Laumer said, after he accidentally touched a finger to his wound with the pain-relieving leaf juice. Or he may have learned the behavior culturally, from other orangutans, early in life.
Orangutans learn socially and have been shown to be instrumental. They develop a sophisticated knowledge of foods from their mothers.
“They learn a lot about, for example, what kinds of fruit 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. … This is some serious knowledge that they really need to get.”
Did people learn about medical plans from animals?
Evidence of animal self-medication has increased in recent years.
In the 1960s, the famous primatologist Jane Goodall noticed that chimpanzees in Tanzania were eating whole leaves from a plant later identified as a type of Aspilia shrub. Years later, Huffman wrote a paper describing how a different population of chimpanzees ate the bitter pith of certain daisies, but only rarely and when other behaviors indicated they were ill.
Researchers think that chimps developed such behaviors to treat or prevent parasites.
In the 1990s and 2000s, a flood of research identified additional examples of self-medication.
A landmark 2008 study of Bornean orangutans documented three females rubbing their bodies with pastes of the chewing plant Dracaena cantleyi, which local indigenous people use to address bone and joint pain.
Huffman said he thinks all animal species are self-medicating to some extent. The practice in insects has even been documented by researchers.
“It shows us that animals are in control of their lives,” he said. “That they can behave in ways that are flexible, adapted to certain circumstances that come down to survival.”
He theorized that ancient people gained the ability to identify medicinal plants and substances from close observation of animals.
“A lot of medicine that people have used in our history as a species came from our close connection with nature and looking to other animals for advice and extrapolating from what we learned,” Huffman said. “I don’t know of any plant that has documented animal use as medicine that isn’t also used by humans. And I think it’s the people who learned from the animals.”
Laumer said her team’s findings – in a species that is 97% genetically similar to humans – could shed light on how ancient primates developed their propensity to pursue medicine.
“Our last common ancestor may have already demonstrated similar forms of ointment transport,” 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 increases wildfires.
The most recent estimates, from 2016, suggest that fewer than 14,000 remain.
This article was originally published on NBCNews.com
