24-05-2025
Bug, MD: Meet the surgeons and doctors of the wild
Birds do it. Bees do it. Even hibernating bears do it.
They self-medicate, and they do it better than us.
Bears, for instance, eat willow bark after their long winter snooze. Rich in salicin, the bark helps cleanse the bear's system and ease the stiffness and aches that may have set in, during the still winter months.
Incidentally, salicylic acid drawn from salicin is used in our painkillers too; it's helped us make aspirin since 1899.
Now to more dramatic examples. Florida carpenter ants perform surgery on each other, to increase an injured buddy's chances of survival. A study published in the journal Current Biology last year detailed how an ant will bite off an injured colleague's infected upper leg to save its life, with a success rate of 90% for such amputations, against a survival rate of about 40% in cases where such an injury is left untreated.
Meanwhile, earlier this year, a study published in the journal Science reported that mice sometimes perform a kind of CPR on each other. In their experiment, researchers drugged a mouse and waited for it to fall unconscious. When it did, a fellow mouse aggressively opened its mouth and pulled out its tongue, helping open its airways quite effectively.
Such actions are not deliberate, in the way that we define deliberate, but they're not pure instinct either, says Jaap de Roode, a professor of biology at Atlanta's Emory University and author of the new book Doctors by Nature: How Ants, Apes, and other Animals Heal Themselves (Princeton University Press; March 2025).
The book compiles findings from scientists around the world, and details observational studies and experiments on this intriguing subject.
In modern science, the field is referred to as zoopharmacognosy (the study of animal self-medication). It is generally dated to the 1980s, when primatologist Michael Huffman and traditional healer Mohamedi Seifu Kalunde observed a mother chimpanzee in Tanzania ease a gut infection by swallowing the bitter leaves of the mjonso shrub, and then teach her infant to do the same.
'Back then, many Western scientists wouldn't believe it. They said there was no way animals could have the mental capacity to self-medicate, because they didn't have the intellect of humans,' de Roode says. 'With mounting scientific evidence, they started accepting it, but only because the chimpanzees are our distant cousins and have large brains.'
Over time, of course, humans learnt (and grew to accept) that several species have tools, cultures and customs. They may not evolve, as our cultures do. But they are passed down: the paths to healing, the use of basic tools, the best ways to raise young.
Winging it
The point of his book, de Roode says, is to shatter our human-centric perspective.
It drives much of what the 47-year-old does. His area of focus as a researcher, for instance, is the monarch butterfly. So, every year, at the St Marks Monarch Butterfly Festival in Florida, he holds specialised tours to explain why these orange-winged, polka-dotted creatures are 'expert doctors'.
'Insects are the most diverse group of animals on earth and they've been around for much longer — some 479 million years, against less than 200 million for mammals,' he tells them. Behind that ability to survive is a degree of adaptability to hurt — and a body of 'knowledge' about how to stay healthy.
Both wood ants and honeybees, for instance, collect and apply resins to their nests and hives to keep bacteria and fungi away and protect the health of the colony.
Woolly bear caterpillars eat as many as five plant species a day, to stock up on vital alkaloids. These nitrogen compounds are their primary line of defence when a tachinid fly lays eggs on them. As the larvae hatch, they chew on the little woolly bug. The alkaloids are toxic to the larvae, and this helps raise the caterpillar's odds of surviving (from 40% to 60%).
The really interesting bit: the alkaloids can be toxic to the little caterpillar too. It has to 'know' just how much to ingest.
Sage advice
Even plants have 'learnt' how to protect themselves.
Over time, as insects and animals evolved, plants began to encounter new threats, and developed the ability to produce toxins that work to stop these creatures from eating them. 'It is often these very compounds that act as medicines for animals — and for humans,' de Roode says.
Humans also gathered knowledge as they evolved, and passed it down, even though they couldn't explain why certain herbs heal or why others go into a salve. And so it is that we are now discovering antioxidants and anticarcinogens in the things our grandparents told us to eat.
'Many of the scientific discoveries of the last decades are in fact rediscoveries of traditional knowledge,' de Roode writes. There could still be cures in plain sight, he adds.
Researcher Cassandra Quave of Emory University is studying the sweet chestnut tree in her attempts to treat certain skin conditions, based on a tip she received from Italians and the Albanian Arbereshe community.
At the University of Kinshasa in the Congo, Ulrich Maloueki is studying which elements in primate diets contain antimalarial agents, in attempts to develop new drugs for humans.
We once ate food that doubled as medicine too. There are certain cultures (think of south India) that still largely adhere to seasonal eating habits, balance meals depending on time of day and time of year. In such cultures, as in the animal kingdom, food itself becomes the first line of defence against illness.
In a world of rapid extinctions, this is something to think about too.
'It is not just the animals we are losing,' as de Roode puts it. 'With every animal we lose, we lose another medical expert and another opportunity to discover new compounds that we may want to develop as medicines for ourselves.'
