6 Natural Medicines (Maybe) Used by Animals | Zoopharmacognosy


SciShow is supported by Brilliant.org. [♪ Intro ] Some animals are way smarter
than we give them credit for. Crows can invent tools, some spiders customize
hunting techniques, animals have even been observed medicating themselves to treat illnesses. But animal behavior isn’t always what it
seems, and this self-medication is a great example of that. There’s actually a whole field about this
subject, called zoopharmocognosy, and it tends to pop up on the internet
from time to time. For example, you might have read how elephants
eat a certain tree to induce labor. Or that some primates eat specific plants
to get rid of parasites. But as cool as that sounds, and it sounds
pretty cool, some of those stories are a bit problematic,
at least scientifically. In some cases, the research isn’t nearly as
solidified as a lot of articles will make you believe. So here are six examples of zoopharmacognosy
and what the research really says. Although they are not the most famous examples,
the best-studied cases of zoopharmacognosy are actually in insects, like tiger moth caterpillars. These insects eat multiple species of plant,
but some of them are a bit unusual, because they contain harmful chemicals called pyrrolizidine alkaloids, or PAs. These chemicals reduce the caterpillars’ ability to grow, but there’s also a pretty big benefit to eating them: PAs protect the
caterpillars against parasitoids. And a small caterpillar is better than a dead
caterpillar any day. These caterpillars are parasitized by several
species of insect, including some flies that can make their lives
pretty horrible. The flies lay their eggs on the caterpillars,
and when they hatch, the young maggots burrow into the caterpillars and begin eating them alive. But if a caterpillar’s tissues are laced
with PAs, it has a chance to survive this horror, because the alkaloids are even more
toxic to the maggots than they are to the caterpillars. In a paper published in PLOS One in 2009,
researchers validated that idea in the lab, and they even found that parasitized insects
ate more alkaloid-laced food than their unaffected counterparts. Kind of like they were taking more medicine. It’s unclear exactly how much they know
why they’re doing what they’re doing, and the results were slightly different depending
on how many fly eggs a caterpillar had on it. But one way or another, it shows that they’ve
found a treatment to kill the flies that ail them. It’s not just caterpillars that do this,
either. Another insect that uses medicine to combat
body-snatching parasites is our old friend the fruit fly. If you’ve ever forgotten a peach in the
back of your pantry, you probably know that these flies are attracted to rotting fruit. They lay their eggs on it so that, when they
hatch, the little maggots have a sweet meal right in front of them. But sometimes, old fruit has yeast growing
on it. And as the yeast cells break down sugars in
the fruit, they make ethanol, a type of alcohol that gives those
baby flies a boozy meal. Ethanol isn’t good for developing baby anythings,
but fruit flies can tolerate some of it because they have an enzyme to break it down. Still, generally, female flies do prefer to
lay their eggs on fruit with low levels of ethanol, except when parasitoid wasps are
around. Kind of like with the caterpillars, tiny wasps
can lay their eggs in fruit fly maggots, and eventually, the wasp larvae
will devour them alive. But the wasps aren’t as tolerant of ethanol
as fruit flies. For them, it causes various organ defects,
and research published in 2012 showed that wasps were more than twice as likely to die if they parasitized flies that had been consuming ethanol. What’s especially cool is that another study,
published a year later, showed that female fruit flies decide whether or not to lay their eggs in boozy fruit based on the risk of parasitism. In the experiment, female flies that saw female
parasitoid wasps preferred to lay their eggs in high ethanol food sources. But flies who were shown male wasps, who don’t
lay eggs and so don’t pose a parasitism threat, preferred low-ethanol fruit. Like with the caterpillars, though, this doesn’t
necessarily mean the flies learned that ethanol was medicine. The researchers suggested that, instead, seeing
a female wasp might trigger changes in the fly’s brains that cause them to prefer it. Although these insect stories are great, the
whole idea of zoopharmacognosy really gained popularity based on work by primatologists. Over the years, they observed various monkeys and apes eating plants used by local humans to treat ailments, especially intestinal parasites. This led them to hypothesize that the animals
were also using plants as medicine, and their ideas trickled down into
pop culture from there. But the truth is, in a lot of these cases,
there just isn’t a ton of evidence, because these hypotheses are much harder to test in
primates compared to with insects. For example, it’s not really ethical, or
practical, to put a bunch of monkeys in lab, and then give some of them parasites and see what
they choose to eat. So scientists mostly have to rely on circumstantial evidence they gather by basically stalking primates in the wild. But those studies have been really interesting. One example was from a paper published in
2001, where researchers recorded an odd behavior in chimpanzees in Tanzania. First thing in the morning, on an empty stomach,
the chimps would fold up a leaf, often from an Aspilia plant, and then swallow it whole,
without chewing. Other researchers had seen similar things
before, but in this paper, the scientists took their work further. They recorded 14 instances of this behavior
and then followed the chimps closely to see, like, how everything came out. They were only able to observe pooping in
seven of the animals, but for those seven, they found that the leaves passed through
the chimps’ guts pretty much intact. More importantly, they noticed that there
were often adult nematode worms present in the poop, parasites that spend part of their
life cycle in the chimps’ intestinal walls. The researchers didn’t find evidence of
any nematode-killing chemical in the Aspilia leaves, though, like you might guess. Instead, they think the leaves may have more
of a mechanical action. They have rough, slightly bristly surfaces,
and the scientists think that allows them to physically scrape the worms off the chimps’
intestinal walls. Kind of like swallowing a scrub pad. As you can imagine, the leaves also irritate
the stomach, which makes it secret more gastric acid. Then, the acid passes through the intestine
as well and may further repel the worms. Of course, the sample size here is pretty
small, and the researchers couldn’t experimentally test whether the leaves actually dislodge any parasites. So before we say anything for sure, we’ve got to get some science way more up close and personal with those chimp intestines. All examples of zoopharmacognosy aren’t
about parasites, though. Some animals self-medicate for other reasons. For example, red colobus monkeys living on the island of Zanzibar may use charcoal to prevent upset tummies. Farmers in Zanzibar have planted two species
of non-native trees, mango and Indian almond, that have protein-rich, nutritious leaves
that also happen to be loaded with tannic acid. Tannic acid binds to proteins during digestion,
which makes food less nutritious and also causes symptoms like nausea and vomiting in
humans and, presumably, in monkeys. In high enough doses, it can also be toxic
to liver cells. So to eat the mango and almond leaves safely,
the colobus monkeys appear to take advantage of another resource that humans have inadvertently
provided, charcoal. Local farmers burn wood in outdoor kilns to
make charcoal for cooking fuel. And colobus monkeys visit these kilns when
they’re not in use to eat the bits of charcoal left behind. Charcoal doesn’t have any nutritional value,
but it is good at absorbing things. That’s why we use activated charcoal to
treat people who have ingested certain types of poison. In 1997, when researchers tested the samples
of charcoal the monkeys were eating, they found that they weren’t as good at absorbing
tannic acid as medical-grade activated charcoal, but they were surprisingly effective. That made them hypothesize that eating charcoal
allows the monkeys to safely eat the nutritious almond and mango leaves. This may even be a learned behavior, too. Colobus monkeys that don’t live near farms and don’t eat these leaves haven’t been observed eating charcoal. And when researchers left some out, the animals
had no interest in it. To get really convincing evidence that the
monkeys are using charcoal as medicine, though, you would have to do actual experiments, like
feeding the monkeys almond leaves without charcoal and seeing if they got sick. But that’s logistically pretty challenging,
and also just kind of mean. If you’ve tried doing the monkey bars on
the playground recently, you might have found that as you’ve gotten older you’re a little
less good at that and your arms got pretty sore. And you might have even later treated that
with a pain-killing rub like Icy Hot. If you did, you might not be alone. Based on some evidence, orangutans might do
something similar after a long day swinging through the trees. Starting back in 2003, scientists studying orangutans
in Borneo noticed some of the animals chewing up the leaves of the Dracaena plant, spitting them out, and massaging the spit-leaf mixture
on their arms and legs. The orangutans never swallow the Dracaena
leaves, and they don’t rub any other leaves on their body like this, so scientists got curious. They learned that local people used Dracaena to treat sore muscles, and after some chemical analyses, they found that there was good reason
for that: The plants contain chemicals called saponins, which can have anti-inflammatory properties. Specifically, they inhibit the production
of inflammatory cytokines, signaling chemicals that promote redness and swelling. Muscle soreness after hard exercise is caused
in part due to this inflammation. So it’s possible that the orangutans were using the chewed up Dracaena leaves as a pain-killing rub. What makes this more likely is that most of
the animals observed doing this were females who were hauling the extra weight of their
offspring around and might have had some extra sore arms. But so far, only ten orangutans have been
observed using Dracaena, and researchers can’t exactly ask them
how their arms feel. For all we know, the leaf-spit mixture just
makes their hair really soft and shiny. They’re instagram influencers. Finally, one example of zoopharmocognosy that
has gotten a lot of attention is the elephant and the red seringa tree. As the story goes, a researcher studying elephants
in Kenya observed one very pregnant elephant walk many kilometers out of its way to devour
this tree. They had never seen any of their elephants
eat this plant before, so it seemed odd that the pregnant one made such an effort to do it. Then, four days later, the elephant gave birth. When the researcher talked to local women
about this, they told her that sometimes they used a tea made from seringa leaves to induce uterine contractions and labor. So the researcher hypothesized that, maybe,
the elephant was using the plant the same way. But even though popular literature cites this
example a lot, it’s really not conclusive. For one, it’s not clear which chemical in
the seringa is responsible for inducing uterine contractions in humans. Or, if it has the same effect in elephants. Maybe that elephant would have given birth
in four days no matter what she ate. Generally speaking, we also don’t know how
often pregnant elephants eat this tree. At the moment there’s just this one recorded
observation and a cool hypothesis that needs more testing. All these examples go to show that zoopharmacognosy
is really a very cool field, and that, in some cases,
there is very strong evidence for it. But in other cases the jury is still out. There’s still a lot scientists need to learn,
and there are research methods they need to develop. But one way or another, this all raises interesting
questions about animal learning, and whether we can discover potential medicines for ourselves by watching how animals deal with their ailments. We just probably shouldn’t come to those
conclusions too fast. Which is true of anything. We have to apply appropriate methodology and
logic to any new discovery. And if you want to work out your analytical
thinking muscles, check out the Logic course on Brilliant.org. You’ll get to pretend you’re a 21st century
Sherlock Holmes when you learn ways to predict the outcome of a competition or unlock how to tell if a statement is true or false. And you’ll be learning multi-level thinking
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and right now, the first 200 people to go to sign up
at that link from here will get 20% off of an
annual premium subscription to Brilliant. Have fun and know that you’re supporting
SciShow too! Thanks! [ ♪ Outro ]

100 thoughts on “6 Natural Medicines (Maybe) Used by Animals | Zoopharmacognosy”

  1. If I recall correctly, the increased gastric acid would just be neutralized in the small intestine otherwise it would greatly damage it.

  2. We hold ourselves too far from our origin. To think the only reason a critter does something is because a switch is activated and assume that we don't have a similar response…try eating a low anything diet for a while (more than 30 days) and see what your body starts craving.

  3. Wild Health, by Cindy Engel, has an account of chimps swallowing Aspilia leaves starting on page 136. She also mentions the elephant on page 185.

  4. In the showdown of fruit fly vs. wasps, I gotta admit that I have a hard time picking which one I'd prefer to win.

  5. We do know dogs eat grass to induce vomiting when they have an upset tummy & cats eat grass to induce vomiting bc of all the fur in their stomachs. I'm surprised these weren't mentioned in the vid.

  6. You forgot cows actively eating new pine when they have low fibre (high carb) diets that make the rumen slightly acidic.

  7. Elephant are super smart, so you can assume they are prone to similar biases as humans. Maybe this one elephant saw a lot of pregnant human women fetch leaves from this tree and fell for the myth?

    I'm mainly joking but I mean, you shouldn't assume that if one elephant does it then they all know about it, they are very capable of learning about something as individuals without instinctively going for the treatment like the fruit fly would do for exemple.

    So you can assume they are also capable of being wrong about the treatment =p I really wonder how many animals take things that could be considered to be placebo.

  8. I remember a video i watched a while ago where Macaws in South America would eat clay. And they did this because the berries they eat are quite toxic when consumed in large quantities, and because they could eat clay and the berries, the berries became an easy food source for them since very few animal species could consume them.

  9. I just realized, SciShow doesn't cover events, they research stuff because they don't want to make false claims, even if false claims could increase popularity by causing people to ignorantly be sharing false information that sounds cooler than the hidden truth.

  10. Please learn how to pronounce "experiment." At 6:39 "ex speer iment." It is pronounced "ex spare ament."

  11. 1:46 Reminds me of a story my teacher told the class one day. He said that a boy who didn't wash his hands after going #2, had left a little bit of poop in his hair follicles when he scratched his head. This in turn attracted flies into his hair, laying their eggs into said follicles. The eggs would eventually hatch and the maggots would slowly but surely squirm downwards. They would arrive at your brain (somehow) and eat it.

  12. Hopefully these scientists refrain from hurting animals to study them. I observed an elephant in a zoo lean a stick up against a wall then push on it to break it. That seemed rather intelligent so learning about medicine doesn't seem that big of a stretch. Even in humans I'm sure there was a lot of trial and error discovering ancient medicine. As in… maybe I'll eat this and if it doesn't kill me maybe it'll help. Or maybe it's just a bunch of unconscious cravings. Like a bighorn sheep looking for a salt lick or even thirst in an animal. Your body draws you to ingest something even if you don't know why

  13. Some chimps eat mud to lessen the effects of poison in a fruit/food they like to eat.
    Ingenuity is incredible… I mean, who eats mud? Well, they do.

  14. Did you know that honeybees are medicating themselves with shrooms? Paul Stamets discovered this! There's a great video about it, somewhere here on YouTube.

    Here's one:
    https://youtu.be/Y_lqIUlON1s

  15. Hey! What's Saponin?
    Nothing much! What's happening with you?
    -Droopy, master-detective, circa 1998

  16. Not sure if you read these, but can you consider doing a video on Animals who use drugs?
    Bare with me on this…I have seen something about Dolphins using the puffer fish as a toy, an getting high from the toxins it gives off.
    And also I believe a species of monkey that does a similar thing with giant millipedes…
    I'm pretty sure these are real things, and would love to know of any evidence of it happening in other species!

  17. Even a caterpillar knows that it’s better to be alive than die From a disease they can prevent. But anti-VAXers don’t?

  18. Is no one going to comment on that awesome hair-flip by Hank? Watched it 5 times and kept laughing for 10 minutes.

  19. https://www.npr.org/sections/thesalt/2017/09/07/547981850/why-do-parrots-and-people-eat-clay

    I thought this would definitely have made the cut.

  20. 04:02 what is the difference between learning to do something and having changes in the brain that cause to do something?

  21. All lies. This is fake news just like climate change, vaccinations working, and the earth being round. The Bible is factual and science has no place in school. Vote for Trump and donate to your local church people. I say all this while being on my cellphone which is leagues beyond my comprehension while surfing the internet using WiFi. If anyone agreed with my opening statements please don't breed. If you found my opening statements to be unanimously ignorant please don't hesitate to educate others.

  22. I'd make a Canada joke since they showed a maple leaf in the chimp case, but it's the SAP that makes maple syrup, I think I heard maple leaves as they are might be toxic.

  23. Theres a belief i heard growing up that when you see cats or dogs eating grass, its because they are feeling something wrong or feeling ill perhaps and thats them trying to medicate themselves.

  24. very interesting. All critters with brains are clearly aware , the phenotype expressing the molecular code within the genotype. All critters respond to set , dna encoded, patterns of behaviour , all of us perceiving the world through our senses. If we consider this, how much of what we take to be our own personal impulses and drives are not simply part of the phenotype , as we presume of other geno/phenotypes.

  25. Why isn't man's best friend in this list?! Dogs eat grass when they are nauseous or have diarrhea and not just any grass either, they smell grass tufts intently and pick out certain ones they like… Why? I don't know but all dog-owners know of this behaviour… Sometimes it seems to be to induce vomiting, other times it might be to eat more fibrous material that they can't digest well…

  26. 4:07 Stop trying to make that distinction. You tread where countless generations of philosophers grazed already, wondering if a separation between consciousness and automaton-like decision-making is even possible to make and there is still and probably never will be a clear answer.
    If "seeing a female wasp might trigger changes in the flies' brains that cause them to" do something — that is the textbook example of stimulus-reaction interaction that describes our own thought process in psychological studies.

  27. Elephants eat a lot of clay too, to clean out parasites from their stomach. Nature knows natural medicines, as we once better did

  28. The DNA of fruit flies is very similar to that of humans. They have even been studied for understanding consumers in the business world

  29. Old timers in Alaska tell about bears that had been gut shot eating sedge grass and getting a thick covering on the wound of glacier silt or clay mud. I think they talk about it in " The Monarch of Admiralty Bay". It has been maaaaaaaaaaany years since I read that book so, don't bet anything you don't want to loose on that last piece of info.

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