After sustaining a deep wound to his face during an assumed fight with another male, a wild Sumatran orangutan named Rakus did something that astounded researchers. 

First, he began feeding on a liana, a plant with potent medicinal qualities. After a time, he stopped swallowing, but continued chewing. Then for several minutes, he applied the fluid from the chewed vegetation to his wound before covering the open flesh with the plant mash. The observation was groundbreaking. 

“We were very excited because this is the first time that a wild animal was observed treating his or her own wound with a healing plant,” said Isabelle Laumer, the lead author of a recently published paper about the revelation. 

In the following Q&A with Bioneers, Laumer, a postdoctoral researcher at the Max Planck Institute of Animal Behavior in Germany, discusses the research team’s observations, the broader implications of Rakus’ behavior, and how the paper’s findings relate to her other research on animal cognition. The findings of the international research team, which includes researchers from the Max Planck Institute and the Universitas Nasional in Indonesia, were reported in a paper published in Scientific Reports. 

The following conversation has been edited for length and clarity. 

Bioneers: Could you start by sharing the significance of an orangutan being observed treating his wound with a medicinal plant? What signified to you and the other researchers that this was intentional behavior?

Isabelle Laumer: Since 1994, the team has observed wild Sumatran orangutans at the Suaq Balimbing research site and the protected rainforest area that consists mainly of peat swamp forest and is home to about 150 critically endangered Sumatran orangutans. They are wild, not sanctuary housed, and the observations were made by the team on-site. The team noticed that Rakus had sustained a facial wound. We think he got it during a fight with a neighboring male, as he was involved in several long call battles — calls used to repel rival males — before his injury. Three days after he had sustained the facial wound, he was observed feeding on a liana. The liana is called Fibraurea tinctoria, and this liana is rarely eaten. In just 0.3% of all the 390,000 feeding scans, the orangutans in this area are actually feeding from this plant. 

Then, after a while, he stopped swallowing but continued chewing. Then he put the plant fluid, that sort of chewed plant fluid, several times on his wound. The entire process lasted seven minutes. So for seven minutes, he was applying the fluid on top of his wound. And in the end, he even put the more solid plant matter on top of the wound. It was then fully covered with the green plant matter, like a wound plaster, basically. He was also observed feeding on the plant the next day. The wound healed very fast and there were no signs of wound infection. Within a short time, it was already fully closed. 

Bioneers: I saw the pictures. The wound looked really good after a while. 

Laumer: Yes, this process was quite fast, and then only a scar remained in the end. This plant is quite a potent healing plant. It’s used in ethnomedicine, and it’s pain-relieving and anti-inflammatory. He not only had a wound on his cheek, or his flange, but inside the mouth. We could see that because he was long calling; in the videos, you can actually see that there’s also a wound on the lip and inside the mouth. There are many studies actually that investigated the contents of this plant, and there are many other activities: it’s antibacterial, antifungal, antioxidant. It’s also used against malaria, diabetes and for wound treatment. Because of these pain-relieving substances, it could be that he felt immediate pain relief inside the mouth while chewing and feeding on it, then (made) the connection and put that on top of his wound. That’s one option. But it could also be that he accidentally touched with his finger the wound, so then felt, “Oh, yeah, this is pain-relieving,” and then he continued doing that. 

This was the first time that the team observed it, but it does not necessarily have to be the first time that Rakus showed this behavior. It may be the 10th time — we don’t know. What also is another possibility is that Rakus learned it socially from other orangutans. He was not born in Suaq; he was born outside the area. Males in puberty disperse over wide distances to establish a new home range in another area. That’s why we know that it’s actually from outside. It could be that his mother or another orangutan in his natal population shows this behavior, and he learned it socially when he was an infant or a teenager and then later applied the behavior himself when he was wounded. That is possible as well. 

We think that it’s intentional behavior because this was not just one time and that was it. It was applied for seven minutes, several times, and then in the end, he even put the more solid plant matter (on the wound). He only put it on top of his wound, and not on any other body part. This entire process took a considerable amount of time, so that’s why we think it’s an intentional behavior. 

Bioneers: What was the reaction from you and other members of the team when that behavior was reported to you? What are the broader implications? 

Laumer: We were very excited because this is the first time that a wild animal was observed treating his or her own wound with a healing plant. There are broader implications, in terms of evolution. There is also one chimpanzee group in Gabon that shows a form of wound treatment. They are catching little flies from the air, immobilizing them between their lips, and then putting them on their wounds. But the researchers, until this point, haven’t been able to identify the species of fly, therefore it’s unknown if this behavior is functional at all. So it could be a social behavior that this specific group shows, but it’s possible that these flies have certain medical activities in them. We don’t know, but hopefully, in the future, we will know. So we humans show wound care, chimpanzees also show some form of wound treatment, and now the Asian Great Apes, or the orangutans, also show it. Therefore, it’s possible that there exists a common underlying mechanism for the recognition and also for the application of substances with medical or functional properties to wounds. The broader implication is that it’s possible that our last common ancestor also showed similar forms of ointment behavior. 

Bioneers: That’s amazing. I also wanted to touch on some of your other research. You’ve investigated tool use and problem-solving in orangutans and cockatoos. How do you see the self-medication behavior relating to or tying into some of that research? Are there any connections or potential connections? 

Laumer: I think this observation, again, shows how similar we are to the great apes. There are four species of great apes: chimpanzees, orangutans, bonobos and gorillas. They are incredibly smart. For example, in my research, I was investigating whether orangutans can actually innovate a tool, a hook tool. There have been many studies conducted in the U.K. with children from different age classes, not just one study, but really a series of studies on this hook-bending problem. 

The children get a vertical tube with a basket at the bottom that is filled with a sticker. In the case of an orangutan, you put a food reward in order to get them motivated to get this basket out. The only thing that they get is a straight piece of wire and a string. But the string has no function; you cannot get the basket out with a string. But if you choose the wire and then bend it at one end into a hook and put the hook in the (basket) handle, then pull it all the way up until you can grab it, then you can basically solve the problem.

Human children are able to solve this multi-step problem. It’s actually quite complicated because there are several steps included, and all of them need to be applied in order to get the basket out. If you insert it the wrong way around, you can’t get it out. Human children are only able to solve the problem on their own at the age of eight, not earlier. Younger children can do it when you show it to them, but they don’t get the idea of how to do it before. This is because there is an area in the brain that matures later in life, at around eight years of age. This brain area is for multi-step problem-solving, multitasking, things like that. 

I was at (the University of Leipzig), and I think this was one of my first experiments with orangutans during my PhD. The keepers let (adult female orangutan) Padana in and she immediately solved it. I record every trial, and I’m sitting there thinking, “Okay, I hope that my cameras are really working,” because I wasn’t expecting this in this moment. I had two orangutans that, from their very first trial, were able to solve the task continuously.

I also did the same experiment with cockatoos before. Cockatoos are, in many ways, from cognitive aspects, comparable to great apes. Cockatoos are parrots, and parrots and corvids — ravens, for example — are very special in the bird world. Recent research shows that they have neural numbers similar to primates. They have such a small brain and there are lots of neurons. Imagine how fast the speed is. So a raven or a parrot is an incredibly smart animal, and the cockatoos were able to solve the task, but just two of them, and it took them a while. So when two of the orangutans immediately solved it, it was very impressive. This was my first study that I conducted with orangutans. That’s just one aspect of how incredibly smart they are. 

They also have emotions that are very similar to us humans. They can feel joy, they can feel fear, pain, sadness, and many other emotions. For example, during my first postdoc, I worked with researchers from the U.S. I studied humor in all four great ape species at the University of California in Los Angeles. What we found out is that — also research that was published this year — all four species of great apes show similar forms of playful teasing, as human children show.

Bioneers: What form does that take when they playfully tease? What are they doing physically?

Laumer: Playful teasing is a provocative, one-sided behavior. It’s playful, but it also can be annoying. It’s repetitive behavior, usually. But also they elaborate their behavior. For example, they would start by poking another, then they pull on their leg. They also sometimes show elements of surprise in their teasing. For example, they would suddenly jump on the back of the target, kind of surprising the other.

Bioneers: That does sound a lot like kids. 

Laumer: Yeah, it was interesting. Mostly, juveniles were showing teasing behavior. It was mostly directed towards adults in our small sample. We just analyzed one group of each species. That’s why we cannot say much about if this is really always between juveniles and adults. We had also a few adult-adult teasing events, but in our sample, it was mostly juveniles towards adults. Usually, the adults were reacting very calmly, ignoring it in the beginning, then after a while, they even moved away. We rarely observed aggression. In less than 5% of all of our teasing events, there was some element of aggression somewhere in this teasing bout, so aggression was very rare. That’s why we also think that it’s likely that apes are very good at reading others’ behavior and reacting properly to it, to not let it escalate into something serious. 

Bioneers: That’s interesting. Is there anything else that you want to add or highlight? 

Laumer: What is always important for me is to raise awareness of orangutans’ critically endangered status in the wild. They are close to extinction, and it would be extremely sad if such wonderful, intelligent animals — that are so close to us humans and so comparable in many ways — were to leave this world. It’s very important to support organizations that help directly where the apes live, that have sanctuaries. But it’s also very important to create more protected forest areas. Also it’s really important to have these long-term protected forest areas for research because if we were not able to do the research for a long time, no one would know that Rakus is showing this incredible behavior. And these protected forest areas are very important for species survival.