A male Sumatran orangutan heals a facial ulcer by applying an anti-inflammatory ointment as a poultice, the first documentary evidence that animals may be able to deliberately treat their own wounds by using and modifying the resources that nature provides them.
Institute biologists Max Planck of Animal Behavior, Germanyand the National Universities, Indonesiahave obtained the first documentary evidence of a behavior that was already known, that animals are capable of use plants with healing properties for medical purposes.
He orangutan (Pongo abelii)called Rakusrepeatedly chewed and applied sap from a Southeast Asian climbing plant, Fibraurea tinctoriaalso known as Akar Kuning or yellow rootwith a high concentration of berberinea compound with anti-inflammatory and analgesic properties already known in the traditional medicine.
Rakus also covered the wound with a vegetable mesh that he made himself and stood as if it were a poultice.
Although self-medication in nature was not an unknown phenomenon, it is the first time that a wild animal has been seen and recorded applying a healing plant to itself that has properties to treat an injury.
The finding reinforces the hypothesis that medical treatment of wounds could have arisen from a common ancestor shared by humans and orangutans that lived millions of years agothe scientists conclude.
The study, published in Scientific Reportsof the group Nature, was made in Suaq Balimbingm, a protected area of tropical rainforest in Indonesia dedicated to the research of these primates supervised by Max Planck, where about 150 critically endangered Sumatran orangutans live. “During daily observations of the orangutans, we noticed that a male named Rakus had sustained a wound on his face, probably during a fight with a neighboring male,” he explains. Isabelle Laumer, from the Max Planck Institute for Animal Behavior.
Three days after the injury, Rakus selectively tore leaves from the liana, chewed them, and then repeatedly applied the resulting juice precisely to the facial wound for several minutes. As a last step, he completely covered the wound with the chewed leaves.
Observations over the next few days showed no signs of wound infection and after five days the wound was already closed.
Like all self-medication behavior in non-human animals, the case reported in this study raises questions about how intentional these behaviors are and how they arise. “Rakus’s behavior seemed to be intentional since selectively treated his facial wound on the right edge, and no other part of the body, with the juice of the plant. The behavior too was repeated several times, not only with the juice of the plant, but also later with more solid plant material, until the wound was completely covered. The whole process took a considerable amount of time,” says Laumer.
“As a curious fact,” he notes, “Rakus also rested more than usual when he was injured. Sleep positively affects wound healing, since during sleep they increase the release of wounds. growth hormoneprotein synthesis and cell division”.
“Although the self-medication In non-human animals it is often difficult to document systematically due to the difficulty of predicting its occurrence, there is widespread evidence of behaviors such as swallowing whole leaves, bitter chewing of the pith and rubbing of the fur in African great apes, orangutans, gibbons of white-handed monkeys and several other monkey species in Africa, Central and South America, and Madagascar,” the authors note in the study. “To our knowledge, there is only one report on active wound treatment in non-human animals, specifically in chimpanzees,” says Laumer.
Zoopharmacognosy, animal pharmacology
The idea that animals can self-medicate is not new, having been around at least since the 1960s. More formally known as zoopharmacognosyit is believed that a variety of different species could treat their illnesses and injuries to some extent, explains the London Natural History Museumwhich echoes the research.
To the Galapagos finchesFor example, they are sometimes seen rubbing their feathers on the leaves of the Galapagos guava tree, whose leaves contain chemicals that repel mosquitoes and fly larvae, suggesting that the birds could use them as natural pesticide. Other birds may even know how to treat the Stomach ache. The blue headed parrots They frequently lick clay, which is believed to help absorb toxins from the unripe fruits they have eaten. Meanwhile, some ants They appear to deliberately eat higher levels of harmful foods when they are at risk of contracting a fungal infection, or they forego eating these toxic foods when the fungus is not present, suggesting that it could help them fight it.
But they are theories, and if these behaviors are intentional (apprehended and not instinctive), it is difficult to prove. Much of the evidence that exists is anecdotal and we do not know if an animal is aware of the substances it uses. There is results of experimental studies that support these theoriesbut the tests are usually done in a laboratory, so it is difficult to say whether these behaviors also occur in wild animals.
The best evidence for self-medication generally comes from apes. “Long-term behavioral studies give scientists the opportunity to test their theories. Using decades of observations, researchers can show that apes are using plants or animals to treat ailments. “One of the most accepted self-medication behaviors is swallowing whole leaves.”
It is believed that apes swallow rough, bristly leaves to help them expel parasitic worms that live in their intestines, improving their health. While it was first seen in chimpanzees, it has since been seen in gorillas, bonobos and gibbons in Africa and Asia.
This suggests that this is likely to be more than just animal experimentation and could have a evolutionary origin. An even rarer type of self-medication is that of apes who apply substances directly on the wounds. Some chimpanzees place insects in wounds, for example, although the exact reasons are unknown. Rakus has given more confidence to researchers to delve into the thesis that their actions could have a genuine medical benefit.
He Akar Kuning is one of the lianas found in the tropical forests of Southeast Asia known for their analgesic, antipyretic and diuretic effects and are used in traditional medicine to treat various diseases, such as dysentery, diabetes and malaria.
“Previous analyzes of plant chemical compounds show the presence of furanoditerpenoids and protoberberine alkaloids, which are known to have antibacterial, anti-inflammatory, antifungal, antioxidant and other biological activities of relevance to wound healing,” explain the Max Planck researchers.
This possibly innovative behavior presents the first documented case of active wound treatment with a plant species known to contain biologically active substances by a wild animal, and provides new insights into the origins of the human wound care“.
Sci Rep 14, 8932 (2024). https://doi.org/10.1038/s41598-024-58988-7
DOI https://doi.org/10.1038/s41598-024-58988-7
