SciShow Tangents - Fruit

Episode Date: June 22, 2021

The Tangents team tackles one of the greatest controversies in science history: are tomatoes fruits? Head to the link below to find out how you can help support SciShow Tangents, and see all the cool perks you’ll get in return, like bonus episodes and a monthly newsletter! https://www.patreon.com/SciShowTangentsA big thank you to Patreon subscriber Eclectic Bunny for helping to make the show possible!Follow us on Twitter @SciShowTangents, where we’ll tweet out topics for upcoming episodes and you can ask the science couch questions! While you're at it, check out the Tangents crew on Twitter: Ceri: @ceriley Sam: @slamschultz Hank: @hankgreen[Fact Off]Thumping watermelonshttps://www.ksre.k-state.edu/news/stories/2020/07/how-to-pick-a-ripe-melon.htmlhttps://www.almanac.com/how-tell-if-watermelon-ripehttps://www.bksv.com/en/knowledge/blog/perspectives/ripe-watermelonhttps://www.wsj.com/articles/the-science-of-a-ripe-watermelon-1498828907https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4325046/https://link.springer.com/article/10.1007/s00779-013-0706-7Animals eating moldy fruithttps://www.nature.com/articles/s41598-017-05643-z[Ask the Science Couch]Ripening fruit biochemistryhttps://kids.frontiersin.org/articles/10.3389/frym.2018.00016https://www.canr.msu.edu/news/all-fruit-and-vegetables-are-not-created-equal-when-it-comes-to-proper-storage-conditionshttps://academic.oup.com/jxb/article/63/13/4741/484722https://www.actahort.org/books/463/463_42.htm[Butt One More Thing]Medlar fruithttps://www.bbc.com/future/article/20210325-the-strange-medieval-fruit-the-world-forgothttps://www.atlasobscura.com/articles/medlar-fruit-forgotten-butt-shape

Hello and welcome to SciShow Tangents, the lightly competitive science knowledge showcase. I'm your host, Hank Green. And joining me this week, as always, is science expert, Sari Reilly. Hello. I'm ready to be a science expert again. Oh, good. I'm so glad. And we're also joined by resident everyman, Sam Schultz. What's up? It's me, your boy. I don't know about science. I know about Kermit the Frog. That's true. I know a lot about him. Do you want to tell people about your other? I have another podcast that I do with Matt Gato, so it also works for Complexly.

It's called Kermitment. And in it, me and Matt are watching literally every single still existent piece of Muppets media that we can get our hands on. We're like 11 episodes in and we're only to like 1971 or something. And so it's the rest of my life now. All right. But it's very fun. Well, there's a lot of it.

There's, you're never gonna, that's, that's what you want. You don't want your podcast to run out of content. No, you want to die. You want to die doing this podcast. Recently it was, it was released that Jeff Bezos will be on board Blue Origin's first flight to space or something. And I want to know what it would take to get you on that rocket ship with Jeff Bezos. Oh, my God. I think I would have to be paid $200,000.

Wow. That's so low. He's so rich. He's so rich, but he doesn't, I guess, like more would be good, but I don't think Jeff Bezos would be paying me. I don't think he'd want me there. Right? It's just like, it's your lowest price.

You don't have to tell Jeff your lowest price, but you have to tell me your lowest price. Yeah. Yes, if you paid me $200,000 and gave me a ticket to that rocket, I would ride and listen to Jeff Bezos talk about whatever Jeff Bezos talks about. They come back. They're coming back, right? Oh, yeah, yeah, yeah.

As long as everything goes according to plan. Okay. That's why my price is higher because I'm just not 100% confident that anybody's coming home. I'm not saying that there's a high chance of something going wrong, but a higher chance than going to the grocery store.

I guess I'm just thinking my price to go to Mars forever with Jeffff bezos not very very high couldn't be paid enough for that i don't know i think i'd be too scared actually i don't know if i would do it there's a price at which you can overcome your fear what about just some free podcast buzz marketing that would be great yeah if jeff bezos let me on the front page of amazon advertise my all my various podcasting projects then then sure actually i would do it for that that's true yeah actually i was gonna say that i wouldn't do it for any price but now that you've said like can i put sideshow tangents on the front page of amazon yes i would do it for that price absolutely

be so mad at me like hank no there's a lot like this is a lot it's a great time commitment and also you have a child That guy would be so mad at me. He's like, Hank, no. This is a lot. It's a great time commitment, and also you have a child. How long does it get there for? Well, you got to get there. You got to travel. I'm sure there's some days of prep time.

I don't know if there's training involved. It would kind of suck if you died in a rocket explosion with Jeff Bezos because you'd really be like a lot of paragraphs down. Yeah. You wouldn't make it into most of the articles about it. Also present, tangents. Every week here on SciShow Tangents, we get together to try to one-up a maze

and delight each other with science facts while trying to stay on topic. Our panelists are playing for glory, but also for Hank Bucks, which I will be awarding to them as we play. And at the end of the episode, one of them will be crowned the winner. Now, as always, we're going to introduce this week's topic with the traditional science poem this week from Sari. A fruit, although cute, is a very weird word whose meaning is dissected by a lot of nerds. And botanically, it's clear what's being conferred, but at the market, it's blurred and kind of absurd. Looking at anatomy, these are all egg parts. Acorns, peas, cucumber, check the charts.

But there are also less brain-bendy counterparts, like the berries or melon that you put in your carts. So I guess what I'm saying is that fruits spread seeds, but if they're savory, they're vegetables to suit our needs. Like socially or legally, as we're out here signing deeds, just use words as best you can. Don't get stuck in the weeds. I don't even know what to call those anymore. Are they songs? Are they poems? Are they raps?

I don't really know where the boundaries of poetry are. Yeah. The boundaries of poetry are wherever. This is the thing about poetry, they're wherever you want to put them and that was lovely and the amount of poetry talent

we have on this podcast is kind of astounding. You know, it's like, I basically threw you both in the water and we're like, you're poets now

and then you just hit it out of the park every time. Now I don't understand. Congratulations, Sarah, I'm very impressed by your poem and our topic for the day is fruit, which you have just said in your poem is easy to define despite the fact that we spend a whole lot of time arguing about what it is.

So botanically, it's easy to define. If you ask a botanist, what is a fruit? There is a sentence and it's like that. But the problem is, is that words are messy and we use words to describe the world around us. And then we've started layering on additional meanings of fruit and vegetable. Well, I'm going to guess that we had the word fruit before we had figured out the botanical definition of fruit. before we had figured out the botanical definition of fruit, like fruit was a, like was a word. And then we were like,

like most fruits were fruits. And so we started calling fruits, fruits, most fruits were these seed containing over things. And while there were also lots of things that were those seed containing over things, but weren't fruits. But we were like, well, they are mostly this. And so we put that word on that thing. And so the botanical definition is clear and scientific and nice. And it is what I like about definitions. And then the other thing is like, whatever it feels like.

Yes. Yeah. You look at something at a market and you're like, does this feel like a fruit to me? It's a little fruity. And then if so, then you're like, I would like to buy this fruit. What's a berry? A berry is our kind of fruit. There are subcategories of fruit depending on the structure. So fruit are the reproductive organs, the sexual organs of plants.

The ovary is what swells up around the seed, which is like the fertilized bit. Berries are defined as fruits where it's like fleshy with one or many seeds. So there's no core and it's like technically completely edible. So like you could eat a blueberry outside, for example. But then there are also peepos i think is how you say it which are berries with a hard skin like watermelons and there are droops which is just one seed surrounded by flesh so like a droop is like a cherry or a plum or a peach and then there are

aggregate fruits which are like a bunch of droops clustered together like raspberries or blackberries and strawberries are like kind of aggregate fruits but more like accessories because the seeds are on the outside instead of enclosed within it um so those are all like roughly lumped under fruits and there are many sub debates like strawberries aren't berries they're accessory aggregate fruits uh but i find that to be less interesting well i think there's yeah there's nothing that us non-science people like to argue about more like one of the top 10 things is what is and isn't a fruit so this has been very helpful they're all fruits basically right well and like there there are some things that aren't fruits and this is where like vegetable comes in and

everybody's like well the what's a vegetable it's just like a part of a plant you can eat so a fruit is also a vegetable kind of but there are vegetables that aren't fruits like carrots aren't fruits fruit is specifically referring to like the ovary of a plant vegetable can refer to like anything else so like if you look at a plant like even a cherry tree the cherry is the fruit and then everything else on the cherry tree is vegetative material. I heard this explained by Hallie Casey on the One to Grow On podcast and it's like stuck in my brain. She's so great. Where like the bark is vegetative material and the leaves are vegetative material, but we don't eat them so we wouldn't call them vegetables. But like that is the difference between fruit and vegetables. So in the way that Hank said, like spinach are leaves or carrots are roots or like potatoes are starches and tubers.

We like classify them all as vegetative material, a.k.a. a vegetable. And are they there to get eaten? Is that what they're there for? Why are they so tasty? They are there to get eaten. Oftentimes, the goal of the fruit, this isn't always the case, but the goal of the fruit is to get eaten so that then the seed will get pooped out somewhere else and the food will be distributed. So we're doing our work, eating those strawberries so we can poop out strawberry seeds and then grow lots of strawberry plants at the sewage treatment plant. You don't have your strawberry poop corner of your yard?

Is that just us? Yeah. One day of the year, we only eat strawberries, and then we poop there, and then it's just like, wow, look at those great strawberries that grew. So, that's how you got to do it. You have one day where you have devoted to each vegetable. That's how farming works. Farmers just have really, really strict diets where they're like, oh man, okay, kids, get into gear. Today is wheat day, and I know it's kind of boring, but we need wheat crops.

Yeah, we can't grind it up for a diet. You gotta eat it whole. And that's what a tractor is. It's just a portable toilet that drives you around. Yeah, correct. And it has a hole in the seat. Glad we worked it all out, you guys. This has been SciShow Tangents. Sari, where does the word

fruit come from? Well, it's kind of like you said, where it started out as any product that are useful to humans or animals that's grown from the earth. The fruits of your labor. But also, it came from Latin

fructus, which meant an enjoyment, a delight, a satisfaction. In addition to like produce. So that's why tomatoes aren't a fruit. Yeah, are you delighted by it when you eat it? I'm not really delighted by it. It's a fruit. And that means that it's time for our first game of the show.

Our quiz this week is a brainstorm. So with a brainstorm, I give Sam and Sari a question that has multiple answers and then you have to try and guess some of the answers going back and forth. And you get a point for every one you get. And if you get it wrong, then you don't get a point. But I'll let you keep going

for a while until it seems like until it seems like we're not getting any more. Basically. So in round number one of brainstorm, we got not getting any more, basically. So in round number one of BrainStorm, we got figs for bats versus birds. So because of the relationship between eating fruits and seed dispersal, which we just talked about, scientists have hypothesized that frugivores, the animals that eat fruits, have shaped the evolution of fruits. They call this hypothesis dispersal syndrome,

and the idea is that fruits evolved traits that correspond to the ways that animal species might see the world around them. The hypothesis is pretty neat, but it's also difficult to prove. One of the studies that has provided evidence for dispersal syndromes came about in 2010 when researchers compared figs eaten by birds versus figs eaten by bats at a research site in Papua New Guinea. By studying the fig species preferred by birds and bats, the researchers identified six fruit traits that were preferred by bats over birds and that could be connected to differences in their physiology and behavior. What are the traits of the fruits that they uncovered?

Can I go first? If you want to. Skin thickness. Is that the kind of thing we're looking for? That's the kind of thing we're looking for. I'm going to give it to you because one of them is hardness. So the hardness of the fruit, which does seem involved in the skin thickness. So we'll lump thickness in with hardness, and I'll give you that one. The aroma.

Aroma is correct. Bats ate smellier fruit than birds because birds have a worse sense of smell. What do bats like? They're my favorite animal. I should be more in touch with this. Bats like, I don't know, color. Yeah, color is one.

Oh, great. That's the only other one I can think of so yeah bats ate fruits that were lighter in color and were green or yellow and birds ate fruits that were more red and contrasted more from their background that's all backwards bats should be in the reddest fruits you have take that up with them okay sorry uh size size is one of them bats ate larger fruits than birds because bats can eat their food in pieces because they have teethies yes uh juiciness is that one juiciness is not damn it one fuzziness are figs fuzzy fuzzy is a great idea but no fuzziness did not make the list who knows we'll have to we'll have to investigate fuzziness? Are figs fuzzy? Fuzzy is a great idea, but no, fuzziness did not make the list. Who knows? We'll have to investigate fuzziness and juiciness further. I'll give you each one more crack at it.

Pass. Like age or ripeness of the fruit? That's a good thought, but no. The ones that you missed were where it grows on the tree. So bats ate fruit that grew out from the trunk further from foliage. Because they usually gather fruit in flight or by crawling to the fruit, while birds usually grab while perched on the tree. And also the peduncle length.

That's the stalk. Excuse me. The stalk that holds on to the fruit is called the peduncle. No. It couldn't be. And bats liked fruits with longer peduncles. Well, who can pull any more? So I don't know why you guys missed the peduncle length.

How could we? You know, me and Sam, the one thing that unites the science expert and the everyday man is the peduncle. Passion for peduncle. Passion for peduncle. Yeah. P for pee. P for pee. That's what they call it. Round number two is seed dispersal superlatives.

So animals are great at dispersing seeds, but not all equally good at it. If you don't eat a lot of fruit or you don't spread the seeds very far away in a way that protects them, you're not ultimately going to do a lot for the fruit. From 2015 to 2016, researchers observed animals eating the large fruit of the Platymytra macrocarpa in Khao Vi National Park in Thailand, and then they looked to see the fate of the seeds of the fruit. Based on their results, what were the top four animals when it came to dispersing seeds so you're gonna try and give me four frugivorous animals from thailand and it's a big it's a big fruit flying foxes like the the really big bats i love that for you no No. No, shoot. Oh. I'm so excited.

Some kind of deer, maybe. Is there some kind of deer? That's a points for Sam. Wow. Yes, deer is one of them. The Sambar deer ate a lot of fruit. They tended to spit out the seeds, leaving them more vulnerable to beetle infestation,

but they were one of the top four. All right. You scared? Yeah, I am, because I can't think of more animals. A bird? Is that too vague? I'm going to tell you it's not going to be a bird. These fruits are too big.

There are big birds. Okay. Like an ape? Yeah. A monkey? I'll give you that. A gibbon. The gibbon is one of the four.

They are on the smaller size in the list, but they both ate a lot of fruit and spread it well throughout the forest. So they're good seed scatterers. Thank you to the gibbons. All the ones that are left on the list are bigger than gibbons. Okay, okay. Are there elephants in Thailand? Elephants is correct!

Yes! Amazing, Sam. Wow, Sam, that's impressive. Elephants were the top seed dispersers. They did not visit the tree often, but when they did, they ate a lot of fruit and the seeds ended up in their dung where it was protected from infestation

and was more likely to become a seedling. They're good at eating, they're good at walking, and they're good at pooping. So that's all you need. Warthogs? Love it. Warthogs also sounds great, but it is not the final seed disperser which was bears

asiatic sun bears uh also didn't visit very often but the seeds ended up their dung and so were protected and the researchers weren't able to monitor seed survival in bear dung so we don't know how it compares to elephant dung and protecting the seeds but probably pretty well i don't know why they weren't able to monitor the seed survival in bear dung. Maybe because there were too many bears around. And finally, we've got round number three, your final round, our fruit-eating fish. We focused on animals that eat fruit by land or by air, but there are also fish that are happy to eat fruit that fall into the water.

And the fact that some species can hold the fruit in their guts for a really long time while swimming around makes them useful in dispersing seeds over long distances, though overfishing, damming, and deforestation threaten their ability to do so. Almost 300 species of frugivorous fishes have been identified, including piranha, catfish, and carp species, which have been reported throughout Africa, Southeast Asia, and South America. Fruit-eating fishes have also been reported in six European countries. What countries are they? Oh, I was cataloging all the fish I knew. I was too. I was like salmon, trout.

In Europe? Spain. Spain is the correct answer. France. France is the correct answer. Shoot. France is the correct answer. Shoot. Italy. Italy is not on the list.

Germany? No way. That's too far up there. All right. You only get one incorrect guess, so now you have to get it right or we're out. Okay. What do you got, Sam? Belgium.

No. No. I. No. I'm sorry. Portugal? Portugal, you would think since it's right there with Spain, but it's not on the list. We have Poland and the Netherlands and Greece and the United Kingdom, which we're putting in Europe geographically anyway. Congratulations, you two. I think you did remarkably well with that round.

Yeah, I felt good about that one. It was fun. It was stressful, but I think all good games are a little bit stressful. And don't really have rules that make sense. Sam came out one point ahead in our brainstorm portion

of the show. That doesn't happen much anymore. Five points to series four. Yeah. Yeah, Sam, you got a lot going for you. Is the rest of that sentence besides being really smart? Is that what you're implying?

No, no, that's not at all what I meant. You know a lot of things. You got a good brain on your shoulders. Next up, we're going to take a short break and then it'll be ready for the fact off. Our panelists have brought science facts to present in an attempt to blow my mind. After they have presented their facts, I will judge them and award Hank Bucks any way I see fit. Sam comes in with a little bit of a lead,

but that could easily be trounced by a very, very good fact from Sari. To decide who goes first, I have a trivia question. We have just discussed how a strawberry is not a berry. It's not even a fruit. It is an aggregate fruit, meaning it's several fruits growing from one flower what we think of as strawberry seeds are actually the fruits so the seeds a little encased little thing how many fruits are on an average strawberry oh my god so you're gonna do that thing where you like make a mental map of a strawberry and then you just like bend it apart until it's a Mercator projection.

And then you mentally weigh each section and then you can get the exact number. She's rotating 400 strawberries in her head. I did eat strawberries with lunch today. So I'm like trying to imagine one of those like the average strawberry. I'm going to say 100. Sam appears to have a pencil out. I was right. I was doing some math.

300. All right. So Sam has said 300. Sari has said 100, which presents a problem. I guess this is always mathematically possible. But I'm not sure how to move forward from here. The answer is 200, which means you're equally close. So since you both were equally distant from the answer,

earlier in the episode, I listed three types of frugivorous fishes that I did not spend a lot of time talking about. Can you tell me any one of them? Oh, I was completely checked out. I blocked it out once I finished the question. Koi? Is a koi one of them? No, it's close, though. You heard something. I did.

Carp. Okay, Sari. You decide who goes first. I'll go first, shamefully. One topic of conversation that inevitably comes up at summer picnics is the watermelon thump. So in my case, my mom would go through a market and hold up watermelons and tap them and listen to them and then say, Sari, see, this is what a ripe one sounds like. Or this one is no good. It's mushy.

Or they picked this one too early. Not ripe, not sweet and juicy. As a child, I was like, okay, mom, and didn't think more of it. But since we're doing fruit this week, I wanted to see if there was any scientific basis to the idea that you can hear if a watermelon is good without having to cut into it. And there is. So physically, when you tap an

object and it makes noise, it's because your tap pushes in the molecules, which makes them deform and spring back. And those wiggles create vibrations in the air, which then vibrates your eardrums. This isn't something you can easily see with like a wall when you tap it, but you kind of can with like a squishy couch cushion or a musical instrument. So some objects are made of multiple substances, like how a drum has a membrane and then an inner chamber of air, or how a watermelon has a hard rind and a fleshy inside. And in these cases, the sound you hear can kind of tell you

what the structure of the inside of an object, like a watermelon, is, if you tap a bunch of watermelons for comparison. So the first thing that a watermelon thump can tell you is if it feels like a note with a pitch, kind of like hitting a drum, or a dull thud. And the dull thud probably means that there are different textures throughout the inside or air gaps, and it's asymmetrical and probably mushy or overripe or bad for some reason. And the second thing is that a more ripe but not yet overripe watermelon has denser flesh than a not ripe one,

so the vibrations will be slower and the sound will be lower if you thump a ripe melon as opposed to an unripe melon. And to some extent, the sound varies depending on the size of the fruit, because bigger fruits mean lower sounds, but there is a gradual progression of sound changes based on ripeness. And if you don't have a parent to hit watermelons with you and train you on what a good one sounds like, what do you do? There may be an app for that, I think. I haven't actually checked if it's public, but scientists at least tested one. And it's for people who don't have a good ear for sound and in noisy places like markets and

or just to test if it's a thing. And multiple studies, at least one from August 2013 and one from February 2015, have measured sounds or vibrations from watermelons that had been thumped, and their acoustic-based methods are able to correctly classify ripe and unripe watermelons with an overall accuracy of 89% and 95% respectively. They didn't get into sweetness or juiciness or overripeness, so there are still melon secrets out there passed down through generations. But maybe someday there will be watermelon-thumping robots, or AI, helping us pick our fruit. A watermelon in particular feels like a remarkable achievement. That's a tremendous piece of food.

It does seem like something that was built not by nature in some weird way. It's too perfect and candy-like and delightful. Well, in some ways it is not. We worked together with nature to create it. We worked to help make it as big and juicy and beautiful as they are. So the thump is real. Yeah. I've always kind of doubted it,

but also bonded with other people whose parents did this. A lot of immigrant parents it's like a thing my mom's from malaysia and sylvia's dad is from spain and they both do it like thump the melons but yeah it's it's like a it's a real thing which i guess makes sense if enough people talk about well urban legends never mind enough people talk about something that doesn't make it real. No. All right, Sam, what you got? Picture this.

You're feeling a little peckish. Are you picturing it? You're hungry? I'm picturing it. So you take a peek in the old fruit bowl, and what do you see but a bunch of moldy, smelly fruit? Yucca, you say. And heck, no one could blame you for thinking that almost all other animals would say yucca to that fruit as well. And in fact, science seems to back up the conventional wisdom that an animal would rather eat something that hasn't been infested by a fungus.

There were a few pretty influential studies done mostly in the 70s that concluded that fungus rots a fruit in order to make it unappetizing to other organisms so that those organisms avoid those fruit and they can have it all to themselves. And that's basically been the final word on it until 2017 when a study was published that potentially changes everything. So citing the fact that many of those fungus fruit studies were performed with like pretty limited parameters, like almost all of them were about captive birds and berries, this team performed a new experiment. First, they found two orange groves in two different parts of the world, Brazil and Spain, where they knew a large variety of animals from birds to rabbits to wild boar hung out all the time eating fruit. So the team placed oranges under the trees of the orange grove. Some are infected with penicillium, which we make penicillin out of, I think,

which is a common orange infecting fungus. And some weren't. And they watched what the animals did. So the fungus infected oranges were like white and fuzzy and disgusting looking. What they found was that fruit eating vertebrates that came to this grove seemed to strongly prefer the fungus infected fruit to what the team called the intact fruit by a pretty huge margin. So in Brazil, the fruit-eating animals preferred the fungus-y fruit by two times, but in Spain, it seemed like they preferred the fungus-y fruit by almost 21 times. That's not how I feel. I almost always prefer the non-fungus-y fruit.

I might even say always. You're not a nasty old animal. Non-fungusy fruit. I might even say always. You're not a nasty old animal. So when certain fungus like penicillium rot fruit, they release volatile organic chemicals, a.k.a. smell chemicals, right? Is that what those are pretty much? And the fruit gets all soft and mushy. Those are like the two main things that happen. So researchers think that these two byproducts of rotting have developed

possibly to attract seed dispersing animals. So the smells make the fruit easier to find. And some of the specific smells like ethanol can signal to an animal that fruit is full of sugar and worth eating. And the mushiness makes it easier to eat. So they observed like little mice and small birds who otherwise couldn't puncture the orange's skin being able to rip it open and eat it. And they even suggested that it was possible that the animals were eating the penicillium infested fruit to medicate themselves. They didn't really follow up on that anymore, but it's possible. And it seems like penicillium and other microorganisms that make

the rotten fruit more desirable just live in the outer layers of the fruit and they don't actually spoil the pulp of the fruit. So pretty much they're making the packaging of the fruit more sweet smelling and desirable and leaving the good stuff inside super tasty. And this process ends up being beneficial to everybody. Pretty much the animals get to eat fruit, including fruit they might not have been able to eat normally. The plants get their seeds pooped out all over the place. And the fungus get to hitch a ride on the fur or inside of the animals and will hopefully be deposited near where the new trees will grow so they can keep doing their fungus thing. Okay. But is not bad for you to eat really moldy orange

i've kind of feel like i've been i've been sold this this version of reality where you definitely shouldn't eat moldy fruits but but these mice and deer are just like nah well they can also eat like raw meat and poop and stuff they eat a lot of things we don't eat. Somewhere along the way, we decided we weren't going to eat raw meat and poop anymore. So we made our choice. So now I must choose between your acoustic methods

for predicting a ripe watermelon 90 to 95% of the time or a study that found that animals prefer to eat the moldy fruits and that this is all part of the circle of life and it's advantageous apparently to everyone I think I have to go with Sam

I think I have to go with Sam because it's very counterintuitive and also but once explained makes perfect sense it's one of my

favorite types of fact which means Sam congratulations for being the winner of this episode of SciShow Tangents about time and now it's time

to ask the science couch where we've got some listener questions for our couch of finely honed scientific minds. The question comes from at Joseph J. Nathan, who asks, what the heck happens when a fruit ripens? Which is a great question because it's like, okay, so here's this fruit. It tastes bad.

And then like something occurs and it turns into mouth delight after it's been picked even it can happen yeah something's happening inside with no input from outside my banana turns from like a not very tasty thing into a perfect perfect a little delight so they're actually two different kinds of fruit divided into like two rough categories based on how they ripen and this is really interesting to me because I also have never thought about it. So there are climacteric fruits, which is where ripening leads to a burst of ethylene gas or ethylene hormones.

That is commonly used in the food industry, like the food storage industry, where they pick underripe bananas or apples or avocados. And then when they're ready to ripen them, they expose them to ethylene gas. It's also why when bananas are touching each other, they like get brown spots because like those fruits are continuing to produce ethylene

and that is a ripening hormone. And so the climacteric fruits use ethylene to ripen themselves, but also respond quite strongly to external ethylene. But then there are non-climacteric fruits where ethylene production doesn't go up during ripening. It needs to stay on the plant. So these are things like citruses or grapes or strawberries that you cannot really ripen by force. They ripen best and most on the vine, so you don't want to pick them

too prematurely. And we just don't know what they do. I was reading multiple papers on this, and it's just like ripening in non-climacteric fruits is not well understood. Like strawberries, they think it has something to do with hormones called auxin and abscisic acid. But then they're like, these are totally different than what we found in grapes. And so it seems like there's a bunch of different ways that non-climacteric fruits reach maturity. And what is actually happening inside of the thing? Like, is there, like, there's just a bunch of stuff

that turns from one compound into a different compound. And I imagine a lot of that is like starches turning into sugars because like, it's getting sweet now. Yeah, that's one big, there's like three main things that happen as a fruit ripens. And I imagine a lot of that is like starch is turning into sugars because like it's getting sweet now. Yeah, that's one big. There's like three main things that happen as a fruit ripens. So one is starch gets broken down into sugars, like you said. One is there is a decrease in acidity and bitter things. that keep it bitter and may act as like a pest defendant so that bugs don't eat the unripe fruit and they can stay nice and appealing for the animals that they want to eat them later, want in quotes.

And then the other thing that they do is they soften when they get riper. So enzymes dissolve sugars in the cell wall and the fluid pressure fluid pressure changes inside yeah so that it like gets more watery but like higher pressures to keep the fruit firm and juicy and then when it's done maturing or it's harvested then it loses water over time which causes a loss in that pressure again and that's why like like fruits get wrinkly over time because they like swell up to be juicy when they're most ripe and then that water just has nowhere to go besides out and what what a sort of like little ballet dance that has to happen right when the seed is ready to get dispersed like i'm ready come get me it's like they don't want to the plant doesn't want to produce any more

like sweetness or juiciness than it has to. So it has to all happen at exactly the right time. And then you get a cherry, and it was all worth it. I've tried before, but I've never eaten enough cherries to have diarrhea. How come? Am I just more powerful? Yeah, you're just good at absorbing all that water. Is that what it is, the water? It's probably the water and the sugar,

because eating a lot of candy makes your poops weird too. Not mine. Look, maybe you just have perfect poops, bud. Maybe I do. Have you ever gotten diarrhea in your lifetime? Oh, sure. Well, if you want to ask the Science Couch your question, you can follow us on Twitter

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SciShow Tangents is created by all of us and produced by Caitlin Hoffmeister and Sam Schultz, who also edits a lot of these episodes. Our social media organizer is Paola Garcia Prieto. Our editorial assistant is Deboki Chakravarti. Our sound design is by Joseph Tuna-Medish and we couldn't make any of this without our patrons on Patreon. Thank you and remember,

the mind is not a vessel to be filled, but a fire to be lighted. But one more thing. The medlar fruit has been known throughout history by names like the open arse, because it looks like a butthole. Their seeds have been found in the remains of a Roman toilet, and the fruit was likely popular in medieval times because they're harvested in December, which would make for a good source of sugar in winter. But if you eat them right away, you can get really sick. You have to let them ripen until they're practically rotten looking. You have to let them ripen until they're practically rotten-looking.

And while some say they taste delicious, one medieval writer said, quote, the medlar is not worth a turd until it's ripe, and then it tastes like shit. I love them. I love these boys. That's some good medieval writing right there. How does it make you sick? What are the symptoms? My guess is diarrhea.

Hey, it looked like they're already halfway to diarrhea. I got it. Yeah, that's the whole thing. You should try eating one, Sam, and see if you get diarrhea. Let's just test the limits of my body. It's our new YouTube show. Will this give Sam diarrhea?