When a wild orangutan in Sumatra recently suffered facial injuries after a fight with another male, he did something that caught the attention of scientists observing him.
The animal chewed the leaves of an ivy vine, a plant that monkeys do not normally eat. Over the course of several days, the orangutan carefully applied the juice to his wound and then covered the wound with chewed vine paste. The wound healed with only a slight scar. The tropical herb he chose is known to have antibacterial and antioxidant properties and relieve pain, fever, bleeding, and inflammation.
The striking story was met with interest by the media around the world. In interviews and research articles, the scientists noted that this was “the first systematically documented case of active wound healing by a wild animal” with a biologically active plant. The discovery “will provide new insights into the origins of wound care in humans.”
The orangutan’s behavior seemed familiar to me. As a historian of ancient science researching what the Greeks and Romans knew about plants and animals, I was reminded of similar cases reported by . Aristotle, Pliny the Elder, Aelian and other naturalists from ancient times. A remarkable series of accounts dating from ancient times to the Middle Ages describe the self-medication of many different animals. Animals used plants to treat diseases, repel parasites, neutralize poisons, and heal wounds.
The term zoopharmacognosy – “knowledge of animal medicine” – was coined in 1987. But as Roman natural historian Pliny pointed out 2,000 years ago, many animals have made medical discoveries useful to humans. Indeed, many medicinal plants used in modern medicines were first discovered by indigenous peoples and past cultures who observed and imitated animals using the plants.
What can you learn from watching animals?
Some of the earliest written examples of animal self-medication date back to B.C. It is included in Aristotle’s “History of Animals”, dating from the 4th century; for example, the well-known habit of dogs of eating grass when sick, probably to cleanse and deworm.
Aristotle also noted that bears seek out wild garlic as their first food after hibernation. It is rich in vitamin C, iron and magnesium, which are healthy nutrients after a long winter sleep. Its Latin name reflects this folk belief: allium ursinum It means “bear lily” and its common name in many other languages refers to bears.
Pliny described how the use of dittany, also known as wild thyme, to treat arrow wounds originated from watching wounded deer grazing on the plant. Aristotle and Dioscorides attributed the discovery to wild goats. Vergil, Cicero, Plutarch, Solinus, Celsus, and Galen claimed that dittany had the ability to expel the arrowhead and close the wound. Dittany’s many known phytochemical properties include antiseptic, anti-inflammatory, and coagulant effects.
According to Pliny, deers also knew an antidote to poisonous plants: wild artichokes. Its leaves relieve nausea and stomach cramps and protect the liver. Pliny wrote that deer ate crabs washed ashore to recover from spider bites, and sick goats did the same. Especially crab shells contain chitosan, which strengthens the immune system.
Elephants accidentally ate olive leaves, a natural antibiotic to fight salmonella harbored by lizards, when they ingested chameleons hiding on green leaves. Pliny said that ravens ate chameleons, but then ate bay leaves to counteract the toxicity of the lizards. Antibacterial bay leaves relieve diarrhea and gastrointestinal distress. Pliny noted that blackbirds, partridges, jays, and pigeons also ate bay leaves for digestive problems.
Weasels are said to roll in the evergreen plant mother-of-pearl to ward off wounds and snake bites. Fresh rue is poisonous. Its medicinal value is uncertain, but the dried plant is included in many traditional folk medicines. Swallows collect celandine, another poisonous plant, to make poultice for their chicks’ eyes. Snakes coming out of hibernation rub their eyes on fennel. Fennel bulbs contain compounds that support tissue repair and immunity.
According to the naturalist Aelian, who lived in the 3rd century BC, the Egyptians based much of their medical knowledge on the wisdom of animals. Aelian explained that he treated elephants’ spear wounds with olive flowers and oil. He also explained that storks, partridges and doves crush thyme leaves and apply paste to the wounds.
Studies of animal treatments continued into the Middle Ages. An example from the Aberdeen Bestiary, a 12th-century compendium of English zoology, describes bears covering wounds with mullein. Folk medicine prescribes this flowering plant to relieve pain and heal burns and wounds, thanks to its anti-inflammatory chemicals.
Ibn al-Durayhim’s 14th-century manuscript “The Usefulness of Animals” reported that swallows healed the eyes of hatchlings with turmeric, another anti-inflammatory. He also noted that wild goats chew sphagnum moss and apply it to wounds, just as the Sumatran orangutan does with liana. Sphagnum moss dressings neutralize bacteria and fight infection.
nature’s pharmacopoeia
Of course, these pre-modern observations were folk knowledge, not official science. But the stories reveal long-term observations and imitations of various animal species self-medicating with bioactive plants. Just as traditional Indigenous ethnobotany has led to life-saving medicines today, scientific testing of ancient and medieval claims can lead to the discovery of new therapeutic plants.
Animal self-medication has become a rapidly growing scientific discipline. Observers report observations of animals ranging from birds to mice, from hedgehogs to chimpanzees, using a self-consciously impressive repertoire of medicinal substances. A surprising observation is that finches and sparrows collect cigarette butts. Nicotine kills mites in bird nests. Some veterinarians even allow sick dogs, horses, and other pets to choose their own prescriptions by sniffing various herbal compounds.
Mysteries remain. No one knows how animals perceive which plants cure diseases, heal wounds, ward off parasites, or otherwise improve health. Are they deliberately responding to specific health crises? So how is their knowledge conveyed? What we do know is that we humans have learned the secrets of healing by watching animals self-medicate for thousands of years.
This article is republished from The Conversation, an independent, nonprofit news organization providing facts and authoritative analysis to help you understand our complex world. Written by: Adrienne Mayor, Stanford University
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Adrienne Mayor does not work for, consult, own shares in, or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations other than academic appointments.