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As a species, humans tend to have a bit of a fondness for mind altering substances. Is this true of other animals as well?

Hosted by: Hank Green

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Sources:
Dolphins
https://www.news.com.au/technology/science/dolphins-getting-high-on-puffer-fish-zoologist-rob-pilley-says/news-story/38d19452b6118e46a176ff6256950247
https://repositorio.uac.pt/bitstream/10400.3/2120/1/LMSpp125-127STEINER_N13A.pdf [PDF]
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4626696/
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2857368/
https://www.researchgate.net/publication/15871994_A_case_of_reversible_locked-in_syndrome_like_state_due_to_pufferfish_poisoning_author's_transl
https://onlinelibrary.wiley.com/doi/epdf/10.1002/jcla.1860040615
https://www.scientificamerican.com/article/how-do-whales-and-dolphin/
http://blogs.discovermagazine.com/science-sushi/2013/12/30/stoned-dolphins-give-puff-puff-pass-whole-new-meaning/#.XJpoCutKjOQ
https://www.researchgate.net/profile/Dara_Orbach/publication/266533868_Armed_Escorts_Dusky_Dolphin_Lagenorhynchus_obscurus_Interactions_with_Octopuses_Pinnoctopus_cordiformis_in_New_Zealand/links/5433e0e50cf2dc341dadf822.pdf [PDF]
https://onlinelibrary.wiley.com/doi/abs/10.1002/jcla.1860040615

Elephants
https://www.nationalgeographic.com/animals/2005/12/news-elephants-drunk-wild-myth/
https://pdfs.semanticscholar.org/acb1/518eafc552f90de76d3ac861fb575d444839.pdf [PDF]
https://www.researchgate.net/publication/232660578_The_Living_Elephants_Evolutionary_Ecology_Behavior_and_Conservation [PDF]

Cows
https://archive.org/details/bullbai112/page/n5
https://www.jstor.org/stable/3898731?casa_token=2gug3Ni9uQUAAAAA:lDf_-H1dB6woDtDwZLtx1dB1LKbsNhcVqzPbYHiCn0UTbDX7TcvsihbkDXPrzFfNhyPyd5BZ0Ob6dmT2j5MtKp42a2T-PlYJrH3cvC3tiePLTYOumJon&seq=3#metadata_info_tab_contents
https://www.researchgate.net/profile/Clement_Nzabanita/publication/328199133_Locoweed_Endophytes_A_Review/links/5bbe134a299bf10101768878/Locoweed-Endophytes-A-Review.pdf [PDF]
https://bioone.org/journals/Rangelands/volume-31/issue-1/1551-501X-31.1.16/Locoweed-Poisoning-in-Livestock/10.2111/1551-501X-31.1.16.short
https://books.google.ca/books?hl=en&lr=&id=5saa1x0y5iIC&oi=fnd&pg=PA285&dq=locoweed+cattle&ots=NkPHRyJEna&sig=F0VZ8gub94hpDXtAhVv11tP13X0#v=onepage&q=locoweed%20cattle&f=false
https://journals.uair.arizona.edu/index.php/jrm/article/view/8588
https://www.jstor.org/stable/4002819?seq=1#page_scan_tab_contents
https://www.cabdirect.org/cabdirect/abstract/19681404006
https://europepmc.org/abstract/med/10091127

Cats
https://www.gwern.net/docs/catnip/1963-todd.pdf
https://pdfs.semanticscholar.org/fb60/d7e7b5bc125dc511506e5fadc2b94601565f.pdf [PDF]
https://www.jstor.org/stable/pdf/4255068.pdf?refreqid=excelsior%3A2f55a75ad1d06b826a7493a96f9e8d23 [PDF]
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1480656/pdf/canvetj00079-0049.pdf [PDF]
https://www.gwern.net/docs/catnip/2017-espiniturbe.pdf [PDF]
https://www.tandfonline.com/doi/abs/10.3109/10826087309057482?journalCode=isum19

Image Sources:
https://commons.wikimedia.org/wiki/File:Steno_bredanensis_2.jpg
https://commons.wikimedia.org/wiki/File:Ecomare_-_strandgaper_(4792-mya-strandgaper-mok-ogb).jpg
https://commons.wikimedia.org/wiki/File:Gr%C3%B6nlandwal_6-1999.jpg


https://commons.wikimedia.org/wiki/File:Tetrodotoxin.svg
https://commons.wikimedia.org/wiki/File:Swainsonine_Formula_V.1.svg
https://commons.wikimedia.org/wiki/File:Tetrodotoxin-3D-balls.png
https://commons.wikimedia.org/wiki/File:Nepetalactone.svg
https://commons.wikimedia.org/wiki/File:Structural_formula_of_actinidine.svg
[♪ INTRO].

Although, of course, not every person likes to get drunk or high, there’s no doubt that, as a species, we do have a bit of a fondness for mind-altering substances. You find them in every human culture that has ever existed.

And it seems like our feathered and furry friends also partake from time to time. You might have read the news about wallabies getting high on poppy flowers, or perhaps you’ve watched the hilarious video of a New Zealand wood pigeon hanging upside down after eating too much fermented fruit. Stoned or tipsy animals - they are internet gold, but, as you might expect, most of these cases are anecdotal.

In fact, most examples of animals regularly seeking out intoxicants kind of fall apart when researchers look closer. Even some of the oldest and most well-known examples — like cats on catnip—don’t hold up to scientific scrutiny. So let’s take a look at four infamous cases and see what science says is really going on.

In 2013, the internet went berserk over a video showing dolphins apparently getting high by passing around an inflated puffer fish and “milking” out its toxins. After a few chews, the dolphins drifted motionless at the surface of the water like they were super stoned, or just “fascinated by their own reflection,” as one zoologist said. Observations of this weird behavior actually go back to 1995, when researchers described it in rough-toothed dolphins.

But there are a few reasons to think this drug-seeking story is a bit… fishy. Like, for example, the main toxin in the fish’s arsenal is tetrodotoxin or TTX, and TTX is perhaps the worst choice for a party drug ever. It works by binding to sodium channels in muscle and nerve cells and immobilizing them.

Anything more than a few micrograms of the stuff and mammals experience headaches, vomiting, muscle weakness, and paralysis. Too much leads to heart or lung failure. There have also been cases of people going into a deep coma where they’re still fully conscious but can’t move— which is not fun sounding… super terrifying.

I don’t like it! The same could be said for a whole bunch of recreational drugs— most have toxic effects if taken in high enough doses. But milligram for milligram, TTX is more than 2000 times as deadly as cocaine, so there isn’t a lot of room for error here.

Some animals, like garter snakes, soft-shell clams, and the pufferfish themselves have developed resistance to the compound. But it’s unlikely dolphins have, because no mammals appear to be immune to the stuff, and scientists know that dolphins can be killed by similar compounds. So a more likely scenario is that the dolphins were simply playing with the puffer.

A puffed pufferfish is basically an underwater beach ball, and dolphins have been known to be playful animals. There are other observations of dolphins toying with living things— like, there was a pod of dusky dolphins off the coast of New Zealand that passed around an octopus in the very same way. It’s fun for them - less fun for the octopus.

And that zoned-out chilling at the surface afterwards? It’s called logging, and it’s what dolphins and whales do to rest— like they might do if they were tuckered out after a bunch of playing with like an ocean beachball… that’s actually a living thing. Even if the logging was toxically-induced, there’s no guarantee the animals were enjoying the experience or desired to repeat it.

They might have been chilling at the surface because they were not, like, feeling good. So although it is possible dolphins are doing their own version of the puff, puff, pass, there is not any empirical evidence. And a lot of reasons to think that it’s not what’s happening.

Tales of drunken elephants go back to 1839 when a naturalist reported that Zulu guides told him they’d seen elephants get all weird and aggressive after eating fruit from the marula tree. The naturalist figured the fruit had spent too long on the ground and had fermented. And it was pretty clear to him that the elephants ate this alcoholic fruit because they, like us, enjoy getting tipsy—it just so happens they’re pretty mean drunks.

These stories are still told today. But it turns out they are just tall tales. It’s true that elephants have a pretty varied diet which includes leaves, grasses, tree bark, and fruit.

That fruit includes marula fruits, which will ferment if they fall and aren’t eaten. And these fruits can sometimes become an elephant’s favorite food. They’re a good source of carbohydrates, and there are lots of them around in the dormant season, when trees have shed their leaves and high-quality calorie sources are scarce.

But, there are a couple of reasons this whole drunken elephant story doesn’t hold up--and they were outlined in a 2006 paper in the journal Physiological and Biochemical Zoology. First of all, elephants usually go for the ripe fruit on a tree’s branches, not the fermenting, alcoholic fruit lying on the ground. But most importantly, the math does not add up.

Fermented fruits don’t contain a ton of alcohol. Assuming the fruit contained around 3 percent alcohol —which would be like a really weak beer-— an elephant would have to eat 4 times its maximum daily amount of fruit to get drunk. Being generous, we might try the calculations saying the fruits get up to 7% alcohol, because that’s the maximum percentage of alcohol captive elephants willingly drink.

Apparently we’ve done that study. But even then, there’s no way an elephant could eat enough fruit to get the 27 liters of giggle juice it would need to become tipsy. Elephants are very big!

So, I’m sorry, these giants are not using marula fruit as their night cap. And the overlap between their strange behavior and the fruiting season probably has a lot more of a straightforward answer. The elephants could be acting aggressively because they don’t want some lanky apes stealing their prized marula fruit.

If you’ve ever really watched cows—especially around here in Montana, or in several other western US states—you might have noticed they sometimes just look a little… out of it. Like, they just stare off into space, their head drooping, or they’re staggering around like they’re on something. Well, it’s possible they’ve been hitting the locoweed.

That’s the common name for the poisonous plants from the legume genuses Astragalus and Oxytropis that produce the chemical swainsonine. Swainsonine is a toxin that acts by inhibiting enzymes inside of cells which normally break down other molecules. When those enzymes are inhibited, the molecules build up, and that can have some pretty nasty effects.

The animals stop eating and waste away, become less fertile, miscarry or have babies that are malformed, or die of heart failure. And because cows and other livestock eat these plants despite all those negative effects, some have suggested they’ve become addicted. But scientists have figured out that idea is also loco.

For example, a study from 1987 published in the Journal of Range Management showed that cows born and raised on a paddock containing locoweed eat similar amounts of the plant as newly introduced cows. So experienced cows—ones that could possibly be addicted— don’t tend to eat any more than the cows that have never seen the stuff. And, in a 1991 study on sheep, ewes that were loco-ed in the past didn’t seek out the plant a year later when they were given an area with lots of room and different plants to graze on.

What’s probably happening instead is that these livestock animals are munching on locoweed when there are few other plants available. Locoweed species grow early in the spring before other plants and regrow in the fall, after many plants have died back. Some varieties of locoweed actually taste pretty gross to cows, but if there’s not much else to eat, they’re kind of forced to go for it.

And scientists think they may get used to the taste. Then, they can pass this habit on to others. In a 1994 study, cows that hadn’t seen locoweed before increased how much they ate of it after spending time around cows that had been trained to eat it.

So, in this case, it’s not a drug habit - it’s just a “eat whatever you can get your mouth on and also what everyone else is eating” habit. Which is the same thing I have. Now it’s no secret that cats go bonkers for catnip— hence the perpetual market for catnip toys, sprays and treats.

And way back in 1962, researchers at Harvard described what they called the catnip response: that characteristic 10-ish minute reaction where the cat goes from sniffing and licking to rubbing their face in the stuff and rolling around and looking cute and all whacked out. Later, some scientists went on to conclude that cats were experiencing hallucinations, like seeing butterflies, and even likened catnip’s effects to how people respond to LSD or marijuana. And from a chemical point of view, catnip could make sense as a feline party drug.

The active ingredients in catnip and other cat-attracting plants— molecules like nepetalactone or actinidine—might turn on some of the same brain pathways that many hallucinogens do. So it might seem like cats are a definitive case of drug-seeking behavior. But...

No one has actually shown that catnip makes cats hallucinate. That’s just how a few scientists interpreted some pretty standard pawing or rolling behavior. It’s not like they asked a cat to sit nicely in an MRI machine for a brain scan or gotten them to paint their weird trips.

And the reactions to catnip are all behaviors the animals naturally do in a sexual context. Like, all that rubbing and rolling over is how cats tell other cats that, like, they’re into them. In fact, scientists have gotten cats to perform the same behaviors by exposing them to extracts of male cat urine.

So it seems like those catnip compounds are chemically similar to feline social odors —enough so to fool cats’ noses, at least. And that would mean all that licking and rubbing is them reacting to what seems like the sudden, strong scent of another cat— with no visual dazzle or “high” feelings involved. If it is a case of olfactory overlap, that could explain why only two-thirds to three-quarters of cats seem to care much about catnip.

It’s long been thought that some cats are just immune to the stuff. But research in 2017 says that’s not true—it’s just that some cats don’t react as overtly. Instead, they just kind of chill out in a sphinx-like posture, which may be because they aren’t interested in the smell of a potential mate, or are too young for that kind of thing.

But, when you get right down to it, cats and catnip isn’t a great example of animal drug-seeking behavior because they don’t seek it. Researchers say it’s unlikely that wild cats self-administer the stuff. If they did, you might expect there to be more wild cats hanging around areas where catnip naturally grows.

Basically, if they really needed a hit, they wouldn’t mind traveling a bit to get it. But that’s not the case. There’s no correlation between where cat-attracting plants grow and where wild cats are found.

So, although most cats respond to catnip, their relationship to it isn’t the same as humans and mind-altering drugs. There are lots of other potential cases of animal drug use which could be explored. But so far, scientists haven’t really found any evidence that wild animals seek out chemical highs.

And that raises the question of why humans definitely do. But to answer that, we have to dig deeper into how our closest relatives and model organisms interact with mind-altering substances. And that is an episode for another day.

Thanks for watching! If you want to learn more about how other animals interact with drugs, let me recommend our episode breaking down what happened when scientists gave animals drugs in the lab. And if this episode has you hooked on SciShow, be sure to click on that subscribe button! [♪ OUTRO].