The Self-Medicating Animal

What can we learn from chimps and sheep and maybe even insects that practice medicine on themselves?

Comments: 43

  1. There is no real surprise here. Every dog owner knows that dogs will eat grass to settle an upset stomach. While most learning requires multiple trials before a given behavior is learned (e.g., classical conditioning), the gastrointestinal system seems to have been equipped through evolution with one-trial learning in which a single exposure to a toxin is enough for the animal to learn to avoid the particular substance eaten in all future encounters.

  2. Of course, dogs will eat all kinds of food that's bad for them too.

  3. To most dogs everything is food
    until proven otherwise.

  4. Warren is correct. Wild canids also specifically eat grasses, that pass through them nearly unchanged.

  5. It’s not only medication that animals seek instinctively, they also find essential nutrients in non food items, as elephants do in the clay of lake beds. Our condescending view of animals could use a long, hard, re-examination.

    In the late 1930's a pediatrician named Clara Davis did a series of studies on what came to be known as the"Wisdom of the body”. These experiments allowed infants to self select their diets according to innate tendencies. They were never concluded to clinical standards, but I’ve always wished that someone would take the idea up again and follow it to its conclusion. Are you busy at the moment, Marion Nestle?

  6. Given that some plants are quite toxic, animals (including humans) must employ something more than trial-and-error. Perhaps certain flavors are instinctively recognized as either toxic or helpful to a specific condition, or perhaps there is learning from other individuals, but pure trial-and-error is far too dangerous.

  7. MOISES VELASQUEZ-MANOFF, thank you for such a clear-eyed, fascinating and visually rendered look at biocultural diversity in action. As a health writer interested in ethnopharmacology, I'm aware of the many modern medical therapies that originated with extinct or currently threatened indigenous peoples. And many of our medicines are derived from animals. But what a revelation that we're sharing our planet with four-footed and winged pharmacists! Your observations put even more urgency around the tension between two agendas of the current political administration: health care reform and the loosening of environmental regulation and oversight. If we all viewed our place on the planet with more reverence for our fellow species, we'd take the long view and realize that conservation and "health insurance" are, in a sense, the same thing.

  8. Hours before the Tsunami of 2004 hit Indonesia, various types of animals including elephants left the lowland and headed to higher ground long before the 1st waves hit killing thousands of people. Scientists basically chalked this phenomenon up to the animals sixth sense. We should not underestimate the intelligence of any animal, big or small, domesticated or wild.

  9. This fascinating article omits consideration of an obvious pathway - shared by all the species discussed - by which self-medication might have evolved other than through intellectual or social steps: taste and smell, or more primitive versions of sensing and responding to chemicals and their electrical fields in the environment employed even by single cell creatures (and by our own T cells and other blood components in amazingly complex, sophisticated and seemingly intelligent ways). The illness - the symptom, or specific chemical traces associated with a particular parasite or germ - may alter our "taste," just as pregnancy does for many women - creating instinctive "cravings" for specific chemicals or chemical classes selected by evolution as suited to treat a specific condition. The social capacity to teach and the intellectual capacity to pursue scientific method likely sit on top of and magnify a more primitive evolved cellular process of response to chemical signals.

    And which is also likely why a salted fresh ripe tomato may be the best ever tasted after a hard morning's labor in hot muggy weather.

  10. While the self medication is rife in the animal world, and has shown that cattle grazing wildlands do much better than ones on feed lots actually says something about Humans as well. We have two very diverse populations of humans, ones who live entirely in the cities and dependent on stores for food, and those who live in the countryside and frequently grow their own foods.

    One of the offshots is that those in the country are not only much healthier, but tend towards being more observant of the environment and it's interactions and leaving the cityfolk more ignorant about where their foods come from and how much of the world operates around them that they are never subjected to. This drives huge misunderstandings between city dwellers and those out in the countryside when it comes to politics, ecology and economics.

  11. B. Honest, please be more honest, or at least cite your claims:

    "cattle grazing wildlands do much better than ones on feed lots", and
    "those in the country are not only much healthier", but
    "more observant of the environment and it's interactions".

    In any case, there are assuredly more than two populations of humans. I won't bother with accounts of ecological degradation caused, intentionally or otherwise, by farmers; or of well-informed urban dwellers passionately committed to protecting and restoring ecosystems at all scales. Agriculture itself simplifies ecosystems (otherwise, why bother), to divert more ecosystem productivity into human biomass and away from other species we don't eat.

    Indeed, the argument has been made that the invention of agriculture was the worst mistake humanity ever made. By allowing our populations to expand beyond their local ecological carrying capacities, it made our eventual global ecological saturation inevitable. By re-defining plant and animal species that compete with us for food as enemies, it drove our alienation from nature, and encouraged more population growth. By creating seasonal food surpluses that had to be defended from other expanding human communities, it led to "civilization" and all its problematic ramifications.

    Sorry, but from a long-term historical perspective today's farmers are owed neither more respect, nor less, than are people who purchase the farmers' produce while living in energy-efficient cities.

  12. This is a brilliant article. Along with the article on language and animals in this past NY Times Magazine, wherein prairie dogs were found to call out to others in their tribe with sounds particular not only the type of predator near, but the size and speed of the predator. Animals - They are us and we are them.

  13. This is an amazing article! It makes sense that evolution would cause animals to be able to know what kinds of food could make them feel better when they get ill. The question of whether the animals are using science or not is somewhat moot. Science is the rigorous testing of a hypothesis until there is little doubt about the outcome. The animals seems to try something once and, if they survive, continue to use the treatment. I wonder what the effects would be if they overdosed- of course the OD animal would probably get even sicker or die, but what about the animals around them? Would they never try that plant again? Or would they try to modulate the dose? What if several animals had different doses with non-treated animals watching them? Would the observing animals learn what the correct dose was? What about the animals given the drug- would they be able to recreate the dose within a margin of error when fed the plants as opposed to searching them out?

  14. "Consider those religious sects that refuse modern medicine altogether, favoring prayer instead, and whose believers sometimes die as a result. … the medicine that chimps practice derives from what they’ve learned through trial and error, not from untested explanations for how the world works."

    Religious explanations derive from made-up dogma, not from any studies of the physical world. Technology and science are studies of the physical world, but they differ.

    Technological knowledge derives from trial and error. Technology observes what works, but does not explain how something works. Science explains how the world works, but does so through testable explanations. Over the long-term, science provides a superior way of knowing the physical world because it carries explanatory power and predictive value. To learn that a plant is poisonous through the way of knowing of technology requires random trials that result in poisoning. To know that placing honey on wounds prevents infections is valuable technological knowledge, but it requires no explanation for how honey enacts healing properties. Knowing that bacterial pathogens exist and cause infections is scientific knowledge, which is more powerful because such knowledge explains honey's healing properties while offering many other ways to prevent or heal infections.

    Chimps have neither religion nor science, so it is difficult to understand why the author even invoked religion.

  15. Some varieties of intelligence might relate to each other in organizational ways that are "family like" in terms of an individual's development or in terms of evolution and the origins of new species. But the fundamentals of intelligence might also be organized in other basic ways: cellular, body systems, individual organisms, social groups, and even interspecially. Such a fancy evokes related notions of intelligence and even life as being integral to matter, energy (space and time)?

  16. Perhaps humans should trust science like some of these animals. If so, we would all believe in climate change and the benefits of vaccinations and better the world around us - both for ourselves and these delightful fauna that we share it with.

  17. Very interesting article!

    Liked the comparison to unproven treatments
    we humans sometimes rely on,
    (even prayer...).

  18. While I was living in Western Samoa (now Samoa) in the 1980s the US sent a group of scientists to look for pant medications in case we went to war in Afghanistan. Due to the rough terrain there they knew getting medicines to injured soldiers would be a big problem. Samoans used many different plants to mend themselves and they worked.

    Also we can learn from our pets. Ever since I was a small child I watched my dogs self medicate especially on certainly kids of grasses which either settled an upset stomach or worked as a emetic to make them vomit and feel better. I always wondered how they knew. Interesting to read about other animals doint similar things. We are learning recently that animals are much smarter than we thought for centuries.

  19. Most of us no longer can watch animals for hours at a time in the natural ecosystem. I placed myself in a position to do so, and realize that "secret life" of whatever species can reap insight into the incredible way every living thing interacts with its natural environment. It is both a battle and a ballet of interconnections that the current population of humans has largely been separated from. Of course anyone watching me just sees a lazy person watching horses or goats graze. That is partially true ;)

  20. "We are learning recently that animals are much smarter than we thought for centuries." The ancient Greeks had a word for the all too human tendency to think we are more "intelligent" than and superior to other creatures, including some of out fellow human beings: hubris, which is a defining core characteristic of our current President (sorry folks, couldn't help myself).

  21. There's a great book written in 2002 called "Wild Health" by biologist Cindy Engel on this exact subject that is fascinating. Reading that book made me relax and understand why my dogs ate grass and grazed on local salad berries, why my horses at a variety of plants, why my cows were eating "dirt" in what I called the clay pit.....all interesting behaviors and what many conventional vets would find alarming and race to treat the animals with wormer or something else. A variety of foods, generally plants, has been proven time and time again to be the best "medicine" and plants in their entirety the best of all. It's the human species that's turned to pharmaceutical, extrapolated or synthetic substances and away from whole plants and real foods (of nature) that is the "dumb" one! How did our species medicate in the past? Herbs....i.e. plants.

  22. I couldn't help but be profoundly amazed at the wide eyed innocence bordering at the level of ignorance with which some of the research takes place in this country. Knowledge of herbal medicines is a old as human civilization and it's a commonly held public knowledge at least in the countries like India, where this particular knowledge is recorded and studied for at least three thousand years, it's called as Ayurveda, the Knowledge of health. There is even a greater undocumented treasure of knowledge about medicinal use of different plant parts among the forest dwelling population in India named as the Adivasi people. They point to monkeys and other animals as their source of the knowledge about a particular plant. Domestic dogs and cats go searching for common grass to chew when their tummy aches. This is a very common observation of people all around. So, the phenomenon is known for thousands of years and I am sure, it's known world wide. The modern scientific explanations just seem so narrow and devoid of any imagination.

  23. Interesting stuff

    Color me biased. I worked for Big Pharm for a few years, preparing data submission to FDA; and also in Big Medicine, doing statistical research in cancer treatment.

    So here's my offer:

    We buy two flocks of sheep, mine gets veterinary medicine, yours forages

    And whose family starves, mine or yours.
    The article does note 'pre-western' self-medicat human experiential subjects, who know naturally occurring useful products, and we follow these people around, find the plants, extract the useful essence, then patent it after clinical trial (patent life 21 years , 7665 days, to recoup costs and generate surplus for the next cycle and throw something off for the investors)

    So why don't we ask them how they know

  24. Depends how large the range, overgrazing or insufficient range and number of plant species, how dry or wet the range is will effect the trial. As a long time large animal farmer, I have seen what "Dr. Grass" can do when supplied in the quality and quantities nature is supposed to offer to herd animals. I know vet bills go down with larger foraging acreage, animals are just healthier for many reasons , just one being self selection of food types.

  25. OK, you're biased. The proper hypothesis to be tested in all scientific experiments is the null hypothesis and any experiment must be designed to deny the null hypothesis in a statistically significant fashion while controlling for all possible biases. Your experiment asks the wrong question in the first place, i.e. which group would starve. Also you don't specify what veterinary medicine vs foraging is aimed to treat, not to mention how you would keep the medically treated animals from foraging. Healthy survival is the proper outcome question to be tested, not starvation.

    Also, Big Pharma spends far more on marketing than is spent on R&D, at least 2x by a conservative estimate and 19x by another. The actual disparity is likely in between but no one thinks more is spent on R&D than on marketing. Another problem with Big Pharma is that more than half of all 'new' drugs are copycats of drugs already on the market, not the product of "extract(ing) the useful essence" from naturally occurring plant compounds. Finally, FDA only requires that a drug be safe (enough) for humans and effective, i.e. work better than placebo or, with cancer drugs, as well or better than approved existing drugs. Statistical significance does not equate to clinical significance with any drug and with cancer drugs, 2-3 months of extra life may be statistically significant but not worth the exorbitant price.

  26. Where else would man have gotten ideas independent of language that language then communicates if not from animal pre-adaptations.

  27. So glad to see this article. Years ago, I planted a new garden containing echinacea (coneflowers) amongst other species. That year the coneflowers just couldn't get going. They were nibbled to the ground all the time. That same summer a cottontail rabbit with mange hung out nearby. The next year, no rabbit was spending time in the area of the garden and the coneflowers grew lush and plentiful. I thought, wow, that poor rabbit was trying to boost its immune system by gorging on echinacea. It had not occurred to me before that, of course, animals would select medicinal plants when they needed them. We keep discovering how "advanced" primitive cultures, animals and even plants are in their ability to interact with their worlds in successful ways. Time for us to learn some humility about our "uniqueness".

  28. I had a very similar experience with echinacea, where a groundhog would walk right past my vegetable patch (which he normally would ravage) and eat my echinacea down to the ground in spring. I attributed it to being debilitated from hibernation. Like a spring tonic!

  29. My dog eats plants when her stomach's upset---and she's picky about which ones she's eating as well.

  30. superb arcticle

  31. I always feel better myself when I self medicate. i recommend single malt Scotch.

  32. Isn't it something that "stupid" animals can treat themselves and thrive in conditions that would quickly kill the intelligent humans.
    The human race has become soft and technology dependant. That is what will be it's downfall.
    Don't get me started on the whole country boy "I will survive" thing. When their manufactured weapons fail and the supply of shells runs out they'll crumble.

  33. I read a book once in which the author was learning survival from a Native American elder. He asked how he could know which wild plants were okay to eat. The elder's response was to just go and ask the plant, the same way animals do--otherwise animals would die from eating a poisonous plant on the first bite. In other words, it isn't trial and error--it is insight through a form of communication. Science could argue what that communication might be--smell, electrical sensing, sixth sense, who knows? I just found that anecdote intriguing--the idea that we could humbly ask a plant what it could do for us and our senses could translate the answer. (Of course, I'd want to really practice at developing my sensing ability before I ever had to depend upon it!)

  34. I think we all self medicate in choosing the foods that are most appealing at any particular moment. At least, I know I do. I know some people who take this approach to exercise as well by selecting activities in the gym intuitively rather than following a preset plan. At what point these choices become a form of medical practice is open to discussion.

  35. I had a range bred horse for many years who was very picky about what grazing was on for that day. He ate the tips of willow on days when his arthritis acted up, the roots of certain plants that he would tug and pull up, then eat the soil covered roots and leave the green tops. He had access to a salt and mineral block so it did not have to be for salt.
    While riding in a mature woods, he stopped sudden, dropped his head and starting nuzzling and eating a band of greensand that was exposed when we made the trail. I returned with the front end loader and exposed the source for use in my gardens, which loved it as well. For thirty years I watched that cowpony select his food for his needs. I was lucky to give him the access to the broad acres needed to provide a wide selection of plants and soils for him to choose from.

  36. excellent

  37. Grazing animals in the wild or domestic animals grazing on large acreage will not eat where they defecate(eggs are in the feces) .They have bathroom areas and eating areas in any pastures. Animals keep their feed areas clean when given the chance and they will be tidy with their feces. They seem to know how to keep the parasite load small.
    Most parasites are killed by summer heat and so these same fields may be safely graze in the winter .Natures great system now ruined by how we manage livestock.
    Most grazing animals are now kept in feed lots or on small pastures which makes infestation intense and unavoidable. Currently at least in the US most parasites have become resistance to medications. It is a very serious problem.

  38. Bloodletting does have some logic to it. Bacteria require iron to multiply and many antibiotics work by disrupting the iron uptake process. Lowering the iron content of the blood through bloodletting - without killing the patient, I might add - can prevent an infection from spreading.

  39. There is a paragraph in this article I'd like to respond to:
    Moreover, it’s still unclear how an infant watching its mother learns to associate bitter-tasting plants with physical relief, given that the mother, not the infant, is the one experiencing it and that the effect may not be felt until a day or more after dosing. “That’s the puzzle,” the well-known primatologist and author Frans de Waal told me... “It doesn’t sound logical to me,” he said, “but it must have happened, because we see animals flock to certain resources when they’re sick.”
    As an evolutionary psychologist, I find there is a clear solution to this puzzle if one thinks in terms of evolved programs. One type of program that could account for this behavior is one that, when the body detected cues to pathogenic infection, increased the appetitiveness of bitter compounds. (Much like when we are hungry, motivations to seek sugars, and fats increase, our food selection psychology could be tailored to increase the desire for bitter plant foods.) Also, much like our food selection psychology in general, we learn what counts as edible from others, likely close kin and associates. This suggests there isn't a pure blank slate learning mechanism, which as Frans indicates would pose a huge learnability problem, but instead a program that evolved to take in particular kinds of information and deploy in a context sensitive manner: "when ill seek plant substances that you have observed others consuming." Mystery solved.

  40. A fascinating article but I'm not convinced about the final suggestion that animals learning from trial and error has anything much to do with evidence based medicine. Surely that necessarily involves the rejection of "personal experience" as the final authority where a statistical analysis of the experience of others indicates otherwise? "It seemed to work for me/my family so I believe it works" is the near opposite of evidence based science, yet presumably that and evolved instincts is all that animals have to go on (at least until we discover their yet unguessed at capacity to collect data from other animals and apply statistical methods).

  41. Sounds like what human's might call "hair of the dog," with all due respect to canines.

    Is there any science on whether animals become addicted to mood altering plants and if so, whether they have some type of natural re-had? This is a real question.