An astonishing report appeared in the December 2012 issue of ‘Biology Letters’. Researchers at the National Autonomous University of Mexico found sparrows and finches in the campus would pick up used cigarette butts and place them in their nests. Wondering about this act, the researchers studied the matter in some detail, and found that the birds used the cigarette butts to reduce the parasite infection affecting the eggs and baby birds in the nests! They found that ‘control’ nests with no butts had more parasite count then the ones which did. It also appears that the butt-usage is perhaps an urban manifestation — an innovation — of what sparrows do in the wild, where they collect some green plant material to line the nests to repel parasites.
We have known for some time that chimpanzees and bonobos hunt around for specific plants and leaves to use them as therapy against some diseases. They even swallow whole leaves of some plants and defecate them in order to “flush” out intestinal parasites. Dr. Michael Huffman of Kyoto University has a comprehensive review of such instances of animal self- medication (Proc Nutr Soc. 62; 371, 2003). Well before man came on earth, animals seem to have practiced such herbal remedies. Indeed he argues that the origin of herbal medicine has its roots deep within the animal kingdom.
In the country Gabon in Africa, local tribesmen watched how gorillas, bush pigs and porcupines go into wild frenzies after digging up and eating the roots of certain plants, and learnt about the intoxicants in the plant (and used it themselves). It was on similar observations on goats eating the coffee plant that we learnt coffee to be a stimulant. The roots of the plant “chota – chand” in Nepal were found to be antidote for snake-bite, a fact learnt after watching mongooses feeding on the plant before fighting cobras. Man may not after all be the only sapient animal.
It goes further back in time and evolution. Even backbone-less species (invertebrates) practise herbal medicine. Drs. Singer, Mace and Bernays write in the March 2009 issue of the journal PLoSOne that caterpillars self-medicate themselves to rid of parasites. They preferentially chew on some plants (which are have since found to contain molecules called pyrrolizidine alkaloids or PA) in order to survive longer and produce healthier eggs. However PA is a toxic substance, reducing the growth rate of the caterpillar.
Why would they ingest PA then? The scientist trio did control experiments with field collected caterpillars (both infected with parasites and uninfected), fed them on plates containing PA or sugar and observed. Three things became clear. Caterpillars with no parasite infection (healthier ones) survived better on sugar, while parasite-infected (ill ones) survived better on PA- coated food. PA is thus toxic to the parasite. Next, among the infected ones, those that ate PA survived and grew better. Thirdly, in another set of experiments they found that infection induces self-medication. Infected animals ate more food (with added sugar or added PA, did not matter) than the unparasitised ones. The sick ones “knew” what to do — you do not need big brains or backbones to practise medicine! (Pardon me doctors, I mean no offence).
Dr Huffman asks: “why should any of this information really be a surprise? After all, from an evolutionary standpoint, preservation of health is a basic principle of survival and all species living today can be expected to have evolved a variety of ways of protecting themselves from predators and parasites, large and small, in their environment”. He takes us back to the plant kingdom where the plant produces toxic substances as self-defence.
And in cases where plants and animals co-evolved, each of them utilised the other for mutual benefit. And medication need not be only therapeutic; it can also be prophylactic (to ward off illness). Fruit flies are known to lay their eggs on food with high ethanol, to ward off infection by parasites, wood ants layer their anthills with antimicrobial plant resins to prevent microbial growth. (An excellent summary of such self medication in animals is published by Dr de Roode and others in the 12 April 2013 issue of Science).
It would thus appear that the practice of natural medicine, indeed Ayurveda, has its origin from the plant and animal kingdom. The Panchatantra tales need to be read and understood in this context. Man, living with animals and plants observed what they do, how they keep healthy and fight sickness, and learnt from them. The origins of herbal medicine go all the way to bugs and beasts, and molecular medicine its child. As Drs de Roode, Lefevre and Hunter point out in their perspective note in Science, studies of animal medication may lead the way in discovering new drugs to relieve human suffering.