Nothing could be more outstanding to a biologist than watch an animal – no, not humans – self-medicate whenever it succumbs to certain illnesses. Most importantly, this phenomenon was not just found in one species but across several species in the animal kingdom.
Such observations would raise a lot of questions, how did the animals know that such specific leaves would confer the resulting effect? When did they begin to utilize things from their environment for medicine? How do the animals know that they are sick or infected?
Since we have no way of communicating with these animals, these questions are yet to be answered and may remain so for a very long time.
How Did It All Begin?
Plant material, as we humans have realized millennials ago is made up of lots of compounds that may be of pharmaceutical importance. Before civilization and technological advancement, humans relied on crude forms of medicine.
The same questions could be asked about how humans came to know which plants would be of medicinal value. Could it be an accident or deliberate selection of such plants?
In the late 1900s, a scientist suggested that animals (herbivores specifically) may unknowingly benefit from the plants which already make up their regular diet. But as we go further, we’d see that some animals feed on plants or use some material that couldn’t have been a part of their diet at any point in time.
Michael Huffman, a scientist, proposed that the chimps were self-medicating in 1996. Huffman, an American who has spent years working at Kyoto University’s Primate Research Institute in Japan, first noticed a parasite-ridden, constipated chimp in Tanzania chewing on the leaves of a poisonous plant it would ordinarily avoid. The monkey had fully recovered by the next day.
Huffman developed generally accepted criteria for determining whether an animal is self-medicating.
- First and foremost, the plant consumed cannot be a normal component of the animal’s diet; it is utilized as a medication rather than food.
- Second, the plant should have minimal or no nutritional benefits for the animal.
- Third, the plant must be ingested at periods of the year when parasites are more prone to cause illnesses, such as during the rainy season.
- Fourth, the other animals in the group do not take part.
According to Huffman, if the action matches these criteria, it is safe to believe the animal is self-medicating. Researchers have seen the behavior in 25 distinct places involving 40 different plants.
Could This Habit be ingrained in the Genes?
After citing the Gorilla for his argument of active learning by organisms with regards to self-medication. Mr. Hunter, a Professor of Ecology and Environmental Biology, also suggested that such learned behavior could be passed down.
“It does not take a smart organism to develop an instinctive behavior.” – Mr Hunter.
There may be a genetic difference that causes the gorilla to taste a plant it does not ordinarily consume, and consuming the plant makes the gorilla healthier. The gorillas with such genetic backgrounds live longer and produce more offspring, with little attention given to it.
“That level of learning might operate with other kinds of organisms too,” he argues.
Another Scientist, Jacobus de Roode, assistant professor of biology at Emory University, argues along the line of Mr. Hunter. She makes her case with the monarch butterfly.
“All we have to do is look at a healthy monarch butterfly and a sick monarch butterfly,” says Jacobus de Roode.
“Now, a sick monarch butterfly is really affected by these parasites. The parasites bore little holes in the abdomen, and she will lose some of her bodily fluids and doesn’t feel good.”
She argues that the physiological changes that take place in the butterfly may alter how it responds to her environment. She further suggested that the butterfly may have a genetic predisposition that would cause her to opt for the therapeutic plant matter, which would ensure her survival.
According to add de Roode, The genetic propensity for healing plants implies her(the monarch butterfly) kids are more likely to have it as well and will have a greater survival rate, so it will be passed along to the next generation. The behavior is inherited.
The Unanswered Questions
Are animals more capable than we give them credit for? Scientists are investigating and observing these self-medicating practices of plants.
One could argue that the animals may be randomly selecting such self-medicating practices; scientific observations have debunked such a field of thought.
Some animals have been observed to engage in self-medicating behavior when they are ill from an injection, injury, or ingestion of the toxin. Answering the question “when did it begin?” would be difficult. In fact, it may carry the same weight as asking, “where did humans come from?”
Birds, bees, lizards, elephants, and chimps all have one thing in common: they self-medicate. These animals consume foods that help them feel better, prevent disease, remove parasites such as flatworms, germs, and viruses, or just aid in digestion.
Even creatures with brains the size of pinheads somehow know to ingest certain plants or use them in unusual ways when they need them.
Confirming the self-medicating habit and phenomenon of animals has led scientists to acknowledge this remarkable observation as one worthy of its own field of studies.
How Do Animals Combat Disease?
If you have animals around you, then you’ve witnessed that animals are capable of succumbing to illness just like humans. However, unlike Humans- animals don’t have multi-billion dollar companies that invest heavily in metabolites and complex pharmaceutical compounds.
So how do they cope with the disease? That’s an excellent question. If any animal that gets sick dies, then a lot of species would not be alive today, even humans. Therefore, animals must have a means by which to survive the cruelty of illness or face extinction.
Observations Made by Scientist on Self- medicating Bonobos in Congo
An example of self-medication among the great apes comes from the Congo Basin and features bonobos, often known as pygmy chimps. Barbara Fruth and her colleagues at Leipzig’s Max Plank Institute for Evolutionary Anthropology, including her husband Gottfried Hohman, have been researching bonobos since 1990.
Between October 2007 and June 2009, Fruth conducted fieldwork for several weeks. Her group is conducting research on a bonobo colony on the outside of Salonga National Park, some km from the nearby village.
Manniophyton fulvum, a shrub used by local humans to create animal traps, was one of the things Fruth observed the bonobos eating.
The bonobos would pile the leaves on their tongues, salivate, then fold the leaves back, making a ball while avoiding touch with their lips (contact with the skin causes irritation and blisters). Without chewing, the bonobos ultimately swallowed.
Fruth believes the leaves may potentially treat parasitic sores and have anti-inflammatory properties. She hasn’t figured out who the parasite is yet.
zoo-pharmacognosy is a word coined from three Greek words. “Zoo” means animal; “pharmaco” means “drug”, and “gnosy” means “knowing”.
Scientists proclaim that the self medicative habit of animals may be function by ;
1. Ingesting Plants with Phytochemical properties
Ingested material having therapeutic properties. For instance, when animals ingest medicinal plants to treat intestinal worm infections, the plant may possess chemicals that may decrease the ability of worms to hook unto the walls of the intestine.
2. Ingesting plants with consistent Physical property
The plant material may have a structure such that when ingested(usually wholly and not chewed), it serves as a sort of cleanser which brushes against the intestines. Parasites cling to the walls of the intestine by using hook-like structures. When the leaves brush against the walls of the intestines, it brushes the parasites off the mucosal lining of the intestine. Sometimes the sharp edges of the leaves cut parasites causing them to die or lose grip of the intestines.
3. Ingesting Plants that induce Diarrhea
Scientists have observed that some animals excrete undigested food materials after eating the medicinal plants suggesting that the medicinal plant was not eaten for nutritional purposes but to cause expulsion of intestinal contents. This may be a way of reducing Parasitic load, thereby obstructing the life cycle of the parasite.
How Do Animals Self Medicate?
If animals treat themselves, then it begs the question. How do they self-medicate? Do they inject chemicals into their bloodstream? Do they apply it like lotion? Or do they take their medications like we humans take prescription pills at certain intervals?
Animals have been observed to swallow whole leaves of medicinal plants. In this method, animals take the leaves like a human take capsule tablets. A typical example of animals that take their medicine like this would be the wild chimpanzees.
Chimpanzees would look for leaves of the Aspilia plant, but rather than chew it, they roll it up and swallow it whole. Scientists argue that the stomach of the chimpanzees easily digests the therapeutic chemicals of the leaves.
Hence would not have a lasting effect to counter this problem, the chimpanzees swallow the plant whole, consequently extending digestion time and giving the active ingredient in the plant to act longer on the infected body.
Aspilia leaves have been demonstrated to have chemical ingredients that are active against nematode parasites.
The chimpanzees swallow as much as 15 to 35 Aspilia leaves at a time and were observed to only enact this behavior during rainy seasons when the rate of parasitic infection is higher.
Many animals are known to eat substances that have been demonstrated to be of therapeutic benefits against parasitic infection.
3. Topical Application
Some animals may apply certain substances with medicinal properties to their skin. They have been observed to apply such substances as preventive or curative measures.
Geophagy refers to the eating of earth or clay by many animals. Kaolin is mostly composed of clay. There have been four ideas offered for monkeys linked to geophagy in reducing gastrointestinal diseases or disturbances.
How Did Animals Know What Plants Materials To Use?
The obvious issue is how the animals, some of which are not known for their intellect, learn to accomplish this. How did sparrows and finches learn to gather nicotine-rich cigarette butts in order to decrease mite infestations in their nests? How do honey bees and wood ants know to coat their nests with resin to protect themselves from bacteria?
Professor of ecology environmental biology at the University of Michigan, Mark Hunter, argues that Learning these habits might be inherent, behavioral, or a combination of the two. Apes, being clever creatures, undoubtedly pass on their wisdom to their offspring.
They are always monitoring each other and can communicate both verbally, and via gestures, so their children may observe how they treat themselves: active learning. However, there is also intrinsic learning.
You should never underestimate the power of natural selection,” – Professor Mark Hunter.
A simple explanation, says Mr. Hunter, is as follows: a couple of million years ago, some animal, say a gorilla, had stomach pain. For unexplained reasons, he or she picked up a leaf, chewed on it, or ingested it, and felt better.
When the stomach discomfort returned, the animal recalled the activity and returned to the same plant.
How Some Birds Self Medicate
- Many parrot species in the Americas, Africa, and Papua New Guinea eat kaolin or clay, which releases minerals while also absorbing harmful substances from the intestines.
- Great bustards consume blister insects of the genus Meloe to reduce parasite load in the digestive tract; cantharidin, a poisonous substance found in blister beetles, can kill a great bustard if consumed in large quantities.
- To heighten male sexual excitement, great bustards may consume deadly blister beetles of the genus Meloe.
- Anting is a behavior used by over 200 species of songbirds. Birds either seize ants in their bills and furiously wipe them down the spine of each feather to the base, or they roll in ant hills, twisting and turning, so the ants crawl down their feathers.
- Ants that spray formic acid are the most widely used by birds. This acid was found to be toxic to feather lice in laboratory experiments. Its vapors alone are capable of killing them.
- Some birds use antimicrobial-rich nesting material to defend themselves and their young from hazardous infestations or diseases.
- During a malaria outbreak, house sparrows (Passer domesticus) make their nests with neem tree (Azadirachta indica) materials but switch to quinine-rich leaves of the Krishnachua tree (Caesalpinia pulcherrima); quinine suppresses the symptoms of malaria.
- Some birds use antimicrobial-rich nesting material to defend themselves and their young from hazardous infestations or diseases.
How Some Invertebrates Self Medicate
The capability to seek means to protect oneself from infection and harm caused by the infectious organisms is not restricted to the higher animals. Invertebrates have also been observed to display a similar level of intelligence.
Tachinid flies can be deadly endoparasites of woolly bear caterpillars (Grammia incorrupta). The caterpillars consume plant poisons known as pyrrolizidine alkaloids, which boost their survival by providing resistance to flies.
Importantly, parasitized caterpillars are more prone than non-parasitized caterpillars to consume high amounts of pyrrolizidine alkaloids, and excessive consumption of these poisons affects non-parasitized caterpillar survival.
Ants infected with a certain fungus selectively eat hazardous compounds (reactive oxygen species, ROS) when exposed to a fungal disease but avoid them when not infected.
How Some Mammals Self Medicate
Great apes frequently ingest plants that have little nutritional value but have favorable effects on stomach acidity or battle parasite infection in the intestine.
Chimpanzees will sometimes munch on bitter plants. After chimps chew the leaves of the pith (Vernonia amygdalina), which have anti-parasitic action against Schistosoma, plasmodium, and Leishmania, parasite infection decreases considerably.
Chimpanzees occasionally consume the leaves of the herbaceous Desmodium gangeticum. Undigested, non-chewed leaves were found in 4% of wild chimp feces, while clusters of sharp-edged grass leaves were found in 2%.
The leaves have a rough surface or sharp edges, and the fact that they were not digested and excreted whole suggests that they were not consumed for nutritious purposes.
Aframomum angustifolium fruits are consumed by chimps, bonobos, and gorillas. The antimicrobial activity of homogenized fruit and seed extracts has been demonstrated in laboratory tests.
Apes have been recorded picking a specific section of a medical plant by pulling off leaves and breaking the stem to suck off the juice, demonstrating certain species’ medicinal expertise.
African elephants appear to self-medicate in order to induce labor by chewing on the leaves of a certain Boraginaceae tree; Kenyan women drink tea from this tree for the same reason.
Domestic cats and dogs frequently choose and consume plant stuff, ostensibly to cause vomiting.
The roots of pigweed, which humans utilize as an anthelmintic, are preferentially dug out and eaten by Indian wild boars. According to Mexican mythology, pigs consume pomegranate roots because they contain an alkaloid that is harmful to tapeworms.
Other Non-Therapeutic Self Medication
Humans were thought to be the only creatures that utilize recreational drugs. Our distant cousins are here to prove us wrong. Cats and other animals have been observed using some plants or materials the same way humans use narcotic drugs. Surprising right? I know.
Around 70% of domestic cats are drawn to and influenced by the herb commonly referred to as catnip. Wild cats, especially tigers, are also impacted, though the extent is uncertain.
Cats’ initial reaction is to sniff. Then they lick and occasionally chew the plant before rubbing against it with their cheeks and rolling over. When cats drink a concentrated extract of the plant, they soon exhibit over-excitement symptoms such as furious twitching, copious salivation, and sexual desire. In simpler terms, the cats are so “high” up in the sky.
The plant’s volatile terpenoids known as ‘nepetalactone’ produce the response. They are somewhat poisonous and repel insects from the plant, but their concentration is insufficient to harm cats.
It would seem more animals also partake in the habitual “highness” achieved by the use of certain materials. Dolphins, on the other hand, have a different source for their high.
Dolphins – Spy in the Pod, a BBC One program, revealed the sea animals chomping on pufferfish to get ‘high.’
How Humans Can Learn From Animals
Scientists studying zoopharmacognosy are persuaded that humans can learn from animals, particularly when it comes to developing novel treatments.
Much traditional medicine, particularly in the developing world, likely arose from medicine men observing animals self-medicate, and in the case of the herb used by bonobos, what they observed worked.
Professor Huffman has heard of doctors purposefully examining animals for ideas on how to heal human people.
Other plants are used by animals to battle schistosomiasis, plasmodium, and leishmania, all of which are dreadful human diseases, and some medications have been produced from them.
“If we can learn from creatures that have utilized medicinal herbs for millions of years, and then look at what they use it for,” de Roode adds, “we could learn intriguing things.”
Questions still Unanswered
The majority of modern medicine got its idea from the crude practice of human civilization from different cultures across the world. There are still numerous uncertainties concerning the relationship between genetics and the conditioned behavior to seek medicine.
How did these creatures know that such specific plant could be of medicinal benefit, let alone cure their specific illnesses? Is there more to it than meets the eye?
What are the odds that an animal would try hundreds if not thousands of plants with the aim of finding one with phytochemicals? Most importantly, where are these discovered cures a matter of trial and error? Was there any thought as to the effects of the plant material?
Birds picking up cigarettes as a deterrent of termites is another astonishing observation. Cigarettes have not existed for more than two centuries, yet these birds are already aware of the anti-termite capabilities of the cigarettes compounds. Was this also a result of trial and error?
It would take a tremendous amount of effort to observe, evaluate and investigate the mechanisms utilized by animals in finding cures or using tools from their environments to ensure their survival.
In another article, we discussed the discovery of Wallace’s king of the bees.