Recently, an orangutan who successfully treated a wound by applying chewed leaves to it touched off a worldwide media event:

“It is the first study to scientifically demonstrate that an animal is using a plant with medicinal properties applicable to wounds, and putting those on the wounds and consistently treating over a period of time,” says Michael Huffman, who studies animal self-medication at the Institute for Tropical Medicine at Nagasaki University in Japan.

Vaidyanathan G. ‘Orangutan, heal thyself’: First wild animal seen using medicinal plant. Nature. 2024 May;629(8013):737. doi: 10.1038/d41586-024-01289-w. PMID: 38698232.

Stanford classics scholar Adrienne Mayor weighs in, begging to differ:

To me, the behavior of the orangutan sounded familiar. As a historian of ancient science who investigates what 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 antiquity. A remarkable body of accounts from ancient to medieval times describes self-medication by many different animals. The animals used plants to treat illness, repel parasites, neutralize poisons and heal wounds.

Adrienne Mayor, “People have observed animals self-medicate with plants for millennia,” UPI, May 24, 2024

Indeed, as she notes, thousands of years ago, writers reported many instances of animals seeking out plants to fix what ailed them. We may have noticed one of them ourselves: Dogs eat grass now and then, which may help them with digestion and deworming. (So do cats.)

She offers many examples, including

Pliny explained how the use of dittany, also known as wild oregano, to treat arrow wounds arose from watching wounded stags grazing on the herb. Aristotle and Dioscorides credited wild goats with the discovery. Vergil, Cicero, Plutarch, Solinus, Celsus and Galen claimed that dittany has the ability to expel an arrowhead and close the wound. Among dittany’s many known phytochemical properties are antiseptic, anti-inflammatory and coagulating effects.

Mayor, “For millennia,”

A troubling ambiguity

Mayor hastens to point out that “Of course, these premodern observations were folk knowledge, not formal science.” The troubling part is that she also wants us to recognize that “a large number of medicinal plants used in modern drugs were first discovered by Indigenous peoples and past cultures who observed animals employing plants and emulated them.”

Just what the distinction between folk knowledge and formal science is — or should be — here is unclear. Were the older observations correct or not? If that isn’t what matters, what does? For example, is a formal science study that turns out to be wrong of greater intrinsic value than perennial observations that turn out to be right? If so, we need clarification as to why, to say nothing of a chance for open discussion.

And a question

Mayor notes, “Mysteries remain. No one knows how animals sense which plants cure sickness, heal wounds, repel parasites or otherwise promote health. Are they intentionally responding to particular health crises? And how is their knowledge transmitted?”

Yes, how is their knowledge transmitted? We are told, “Even creatures with brains the size of pinheads somehow know to ingest certain plants or use them in unusual ways when they need them.” (Joel Shurkin, PNAS 2014) So it is not a matter of high intelligence. Genetics? Again, how exactly? Learning by imitation? That too could be studied.

We actually don’t know much more than the ancients did about animal self-medication — technically, zoopharmacognosy — a term coined in 1987. It is going to be interesting to see whether our current assumptions about animals (genetics plus environment explains everything) will shed light on it. Maybe this is a case of ecological design in nature.

You may also wish to read: The remarkable medicines wild animals find in nature. The “animals’ pharmacy” mainly aims at treating parasites and wounds using plants and insects. While intelligent animals like dolphins may sense cause and effect, we don’t know how butterflies and fruit flies pick out the plants that can help.