The History of Medicine Starts in our Animal Lineage
How medicine emerged from the intersection of biology and class society.
A lone weary wanderer combs through the burning rainforests of Borneo, seeking rest and safety. Smog clouds his vision. Smoke fills his lungs. His arms and legs ache from exhaustion and burns. He has no bandages and medicines at his disposal to provide him relief. Luckily, rescuers arrive shortly and deliver much needed medical care.
As they checked his body for injuries, the rescuers were surprised to see pastes of pantung (Dyera constulata) applied on the burns. They knew that the wanderer used plants to self-medicate, but it was their first time to see the pantung plant used for burns. This begged the question: does D. constulata hold healing properties that medicine has yet to discover? Perhaps learning from the forest nomad’s example might help unlock more of nature’s secrets. But to do that, we probably need to learn a new way of speaking because the wanderer doesn’t communicate the way we do.
It may come as a surprise to many that orangutans self-medicate or have any knowledge of medicinal substances. Indeed, the idea of ant apothecaries and primate physicians may border the territories of science-fiction, but to outrightly dismiss the idea of other animals having their own healing habits deprives us of a richer view of the natural world. The gulf between us humans and other animals when it comes to healing is only a historical separation that doesn’t exist in biology, because firstly, we are — and will always be — animals. And secondly, it is in our animal lineage where the history of medicine begins.
Starting Small
All living organisms have, by varying degrees, the capacity to heal. We see this even in the most basic unit of life: the cell. Whenever a cell senses anomalies within itself, it enacts processes that repair and readjust itself back to its default conditions. It’s hard to see this in action with our naked eyes, try hard as we might. But under the microscope, the cellular world is magnified for our pleasure and scrutiny, revealing the secrets of their healing abilities. In a review of the literature, Marshall and Tang explain that cells have two significant self-repair mechanisms: resealing unwanted openings in their membranes and regenerating broken parts. The first is akin to wound healing, where dermal perforations are slowly patched over by new skin. A tear in the membrane can spell certain death for cells, as it provides an opportunity for water and essential nutrients to leak out of the cytoplasm. By a process that is yet to be fully understood, cells can detect lacerations in its membranes and immediately cover them before things get worse.
Other cells are able to create new parts of themselves to replace broken ones. Flagellated cells, those with tail-like appendages, can regenerate their flagella when impaired. The process involves a complex interplay within the cell machinery that first takes into account the extent of damage and then properly allocates resources for repair. “If only one flagellum is severed,” writes Marshall and Tang, “it will regenerate with similar kinetics to when both flagella are severed. While this happens, the other flagellum shortens until both flagella reach the same length, presumably due to competition for precursor proteins.”
Another important process that keeps cells in optimal condition is regulation.
Calcium ions trigger membrane repair response in cells. But too much of these ions can be fatal for the cell if not discharged immediately. To address this ion flooding, cells have evolved intricate structures that utilise physical forces to regulate the ionic content of their cytoplasms. Across the cell membrane are protein channels that act as security screens, permitting particles to move in and out of the cytoplasm. The metaphor is apt, as unlike normal passages, these channels discriminate and are selective, that is, they are specialised to only allow specific ions and particles to pass through them. This feature ensures that only excess molecules are displaced out of the cell, while essential ones are kept inside. Inversely, if certain particles are found lacking in the cytoplasm, the cell can selectively take them from the environment without allowing unnecessary and harmful agents inside.
Since the ability to self-repair and regulate is a fundamental feature of cells, it therefore makes perfect sense that animals, which are made up of cells (if we are to believe biologists [hint: we should]), will seek ways to maintain optimal health and relieve discomforts and diseases. Natural selection played an important role in this development. We will never know the exact details and right sequence, but we can infer using Darwinian logic that proto-cells incapable of self-fixing were eventually overrun by cells that were able to. From these ancestral cells emerged “endless forms, most beautiful”, whose living lineages still feel the tug of this ancient impulse to heal. From the earliest genesis of life, healing has always been the hallmark of a successful species.
Animals as Healers
Natural selection favours those able to solve life’s local and immediate problems, problems which are defined by the various environmental conditions all over the world. Every organism needs to consume nutrients to survive, but dietary concerns between a dromedary and a dolphin are vastly different, for example, despite both having a predisposition to bathe all the time: one in the sea and the other under the sun. This difference is the result of natural history, of organisms diverging into various species, with each befitting the environments they find themselves in. Along the same lines, problems of healing and keeping healthy vary from one species to another. This, in turn, explains the abundance of ways by which animals solve problems related to the maintenance of their well-being. The means by which animals stifle symptoms, regain relief, and mend maladies can thus be unique or shared, depending on what biology affords them and what the environment enforces upon them.
The non-human animal practice of self-medication is called zoopharmacognosy. If we dissect the word we get three main sections that are individually meaningful in Greek and a profound English compound: zoo (animal), pharmakeia (use of drugs), and gnosis (knowledge). Taken together, it simply means the cognitive ability of animals to use medicinal substances.
Let’s take a look at some examples.
When cats eat plant material they are not rebelling against carnivory. Rather, it is a feline form of zoopharmacognosy. The busy life of a cat involves a lot of sleeping and sporadic eating in between. When they miss an hour or two of their important daily 12–16 hours of sleep, they get lethargic. In this state of inertia, cats can even fall asleep as they eat. An upset stomach is almost unavoidable. So cats came up with a simple but effective solution: excess food that went in must go out immediately (similar to the regulation action of cells). To do this cats ingest grass or leaves to trigger a vomit reaction. Take from that what you will about their stance on vegan cat food.
Sometimes, animals don’t even self-medicate to relieve a bad feeling. Instead, their brand of zoopharmacognosy is all about feeling elevated. In short, getting high.
Birds are guilty of this. They have been convicted of indulging in formic acid. But wait a minute, how do they acquire the chemical when they don’t have laboratories? Simple. They agitate ants. Yes, ants. (Formic comes from the Latin word for ant, formica.) In a process aptly and creatively called anting, birds intentionally invite ants to have a go at them. The ants willingly reimburse this audacity by spraying formic acid which the avian assailants seem to enjoy rubbing on their feathers and skin.
Our close cousins, the great apes, are also practitioners of zoopharmacognosy. What was surprising in the above story about the burnt orangutan was his specific use of pantung, and not his general use of medicinal plants, as that was expected. Orangutans have recently been observed to use Dracaeny cantleyi leaves as a multi-purpose topical balm for various ailments. Researchers Morrogh-Bernard, Foitova, Zeen, et al. write in Nature that some orangutans in Borneo applied D. cantleyi “either directly to the skin or chewed and then rubbed into the fur for purposes including ectoparasite removal, insect repellent, treating fungal or bacterial skin infections, treating wounds, or for soothing, stimulating, or conditioning the skin or fur.”
Since orangutans are arboreal, that is to say, they are primarily tree dwelling, their existence has always been entangled in an intimate relationship with plants: they sleep and live on plants, after all. It is a relationship that stretches back millions of years ago, which is, by conventional counting, enough time to get to know each other’s innermost secrets. On the other side of the world, the African branch of the great ape family who spend most of their time on the ground, also boast an acute knowledge of medicinal plants. Bonobos were observed to directly swallow leaves of Manniophyton fulvum only at select instances even if this plant is in high-abundance in bonobo environments. This, researchers Fruth, Ikombe, Matshimba, et al. believe, is because M. fulvum leaves are only taken in for their purgative properties during episodes of parasite infections. This same mode of colonic cleansing was also inferred in chimpanzees from their similar use of Aspilia spp. leaves.
A connection is now made clear. What the ubiquity of self-medication in great apes tells us is that the propensity for healing and discovery is not exclusively human, for it is in fact common in our lineage. We’re not the only hominids that want to feel better and safe.
Primate Physicians
For primatologist Michael Huffman, this hominid healing heritage is of crucial importance in our eventual discovery of medicine. Not only did it give us the anatomy to maximise our environment and the ability to select what is helpful and useless, but it also gave us the promise of growth, of further development — the potential for medicine begins in our primate ancestry. “The strong similarities in plant selection criteria among the African great apes in response to parasite infection and gastrointestinal upset,” Huffman writes, “and the common use of some plants by chimpanzees and humans to treat such illnesses, are tantalizing evidence for the evolution of medicine.” Primate physicians do exist. We are proof of that. Indeed, even our ways of investigating possible curatives are patently primate. “It appears that the fundamentals of perceiving the medicinal properties of a plant by its taste, smell, and texture have their roots deep in our primate history.”
A unique turn in our existence as a species ultimately led us down the path of medical discovery. But medicine was just an ancillary creation down the road, as it was established only out of opportunity, and not from a preordained destiny to do so.
The final pangs of labour before the eventual birth of medicine happened some 23,000 years ago when our ancestors, out of the safety of African savannas, made the earliest attempts to cultivate plants. This initiative led to the discovery of agriculture, which radically altered human relationships by modifying the means and manifestations of power. Homo sapiens societies underwent a drastic transformation, where social order was now defined in terms of property: those who held more food lorded over those who held less; those who had arable land had more access to food, hence exercised more power than those who didn’t. Command began to emanate less from basic natural impulses, and more from the ownership of wealth. It was entirely novel in the animal world. An ambitious gorilla who hoarded food couldn’t simply usurp the alpha with the brute strength. Fresh fruit hardly counts as weapons anyway, despite what Monty Python might say. As soon as individuals started to get segregated into groups based on relative wealth, classes emerged as a fundamental category of human organisation. Slowly, the onus to heal eroded as a personal responsibility. It then fell piece by piece into the hands of a specialised cadre of healers who, by actual talent or designation, were tasked with the duty to collect herbs and administer cures.
It is these ancestral healers that became the midwives in class society’s successful delivery of medicine into the world.
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