Today is world health day. Medicine is generally assumed to be a uniquely human activity. As we know it today, it is true that modern medical practice is no more than a century and a half old, with the leading figure of Sir William Osler . Although, from a broader point of view, the title of “father of medicine” is attributed to Hippocrates of Cos , a doctor of ancient Greece from the 5th century BCE and whose oath is recited today by all those who graduate in this discipline.
Still, we have records of the use of medicine before Hippocrates. The Egyptians had already written the Ebers papyrus around the year 1500 BCE . And before that, Ötzi , the man who froze to death in the Alps more than 5,000 years ago, already had medicinal plants with him that he took to his icy tomb.
But the oldest record of medical practice by humans does not even correspond to the species Homo sapiens . It is a Neanderthal mandible found in El Sidrón , Asturias, 40,000 years old, which showed remains of chamomile and yarrow, plants with little nutritional value and a bitter taste, which, however, have certain medicinal properties.
But although they belong to a different human species, Neanderthals are still human beings. Even taking Homo neanderthalensis into account, we could continue to maintain that medicine is human heritage. However, there are other animal species that self-medicate, either through acquired knowledge and deliberate consumption, or as a form of instinctive and innate behavior.
The most common examples in animal self-medication —or zoopharmacognosy— are those of carnivores that consume plants to “purge themselves”, or that of goats, sheep and deer that eat certain species of flowers when they have gastrointestinal discomfort. But there are others that are, if possible, much more fascinating.
Elephants that teach medicine
In Thailand, mahouts – or elephant keepers – treat their elephants with plant-based remedies. Many of them are based on myths and superstitions without a scientific basis, however, other plants do contain active ingredients and have real medicinal properties , if applied correctly.
The curious thing is that many wild elephants also use plants as a remedy . Elephant self-medication knowledge is estimated to include as many as 50 remedies, many of which coincide with those used by mahouts.
The use of plants as veterinary drugs in Thailand and their origin have recently been studied. The results were surprising: 20 of the species used by veterinarians were also used by elephants . But the most amazing thing is that three of them actually originated from the self-medicating behavior of elephants, and it was the mahouts who learned from them .
Macaws and geophagy
Geophagy is defined as the practice of eating soil or substances derived from soil. The consumption of clay and gravel among parrots and macaws is frequent.
The gravel helps the stomach of these birds to grind food more efficiently, releasing nutrients better and providing better digestion.
As for clay , it was believed that parrots ingested it as a dietary supplement. However, when analyzing their composition, it has been verified that, except for sodium, the rest of the components of these clays are common in the normal diet of macaws, and therefore they do not need them. And that, for that one exception, birds don’t typically actively seek out sodium-rich clays.
The researcher James D. Gilardi, during the development of his doctoral thesis, tested an alternative hypothesis for the consumption of clays: self-medication. The diet of macaws and parrots abounds in fruits with a high content of phenols, which are very toxic . Clay has the property of adsorbing toxins and retaining them, thus preventing them from entering the body. In the digestive system of parrots, the clay would act as a stomach protector that mitigates the toxic effects of phenols.
Lizards looking for the antidote
A Brazilian legend relates how lizards avoid being poisoned by snakebites by consuming teiú root ( Jatropha elliptica ), a plant that effectively contains antibothropic active ingredients —that is, it works by inhibiting the effect of certain poisons—. However, to date, there is no recorded empirical observation of such behavior in any lizard species from Brazil. Although that does not mean that there are no lizards that self-medicate.
There are indeed observations of the Calotes versicolor species, an agamid lizard widely spread throughout Asia that, when injured or sick, resorts to tender twigs of holy basil ( Ocimum sanctum ), a plant that contains active ingredients with anti-inflammatory, analgesic and anticonvulsant properties .
REFERENCES:
Gilardi, J. D. et al. 1999. Biochemical Functions of Geophagy in Parrots: Detoxification of Dietary Toxins and Cytoprotective Effects. Journal ofChemical Ecology, 25(4), 897-922. DOI: 10.1023/A:1020857120217Greene, A. M. et al. 2020. Asian elephant self-medication as a source of ethnoveterinary knowledge among Karen mahouts in northern Thailand. Journal of Ethnopharmacology, 259, 112823. DOI: 10.1016/j.jep.2020.112823Hardy, K. et al. 2012. Neanderthal medics? Evidence for food, cooking, and medicinal plants entrapped in dental calculus. Naturwissenschaften, 99(8), 617-626. DOI: 10.1007/s00114-012-0942-0Pandey, H. P. et al. 2017. A study on the role of holy basil (Ocimum sanctum) in auto-healing of Indian garden lizard (Calotes versicolor). InternationalJournal of Fauna and Biological Studies, 4(2), 97-100.
