SciShow Tangents - Hank's Favorite Things

Episode Date: December 1, 2020

Season 2 of SciShow Tangents is coming to a close, and to celebrate, we’re honoring each of our panelists with episodes about their favorite things! We’re starting, of course, with our fearless leader and professional liker-of-strange-and-amazing-things: Hank!  At the end of the month, we'll be naming the winner of this season and announcing the new name of the Tangents currency, so stay tuned!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: Stefan: @itsmestefanchin Ceri: @ceriley Sam: @slamschultz Hank: @hankgreenIf you want to learn more about any of our main topics, check out these links:[Truth or Fail]Pressure-sensitive Adhesiveshttps://en.wikipedia.org/wiki/Pressure-sensitive_adhesiveMalaria Detectorhttps://www.sciencedaily.com/releases/2018/10/181029102828.htmUrine-Powered Transmitterhttps://www.sciencedaily.com/releases/2015/12/151211130103.htmhttps://uwe-repository.worktribe.com/preview/844724/Wearable-MFC%2010-7-15_unedited.pdf[Fact Off]Cats eating grasshttps://www.sciencemag.org/news/2019/08/mystery-solved-why-cats-eat-grassMetal whiskershttp://thor.inemi.org/webdownload/newsroom/Presentations/SMTAI-04_tin_whiskers.pdfhttps://nepp.nasa.gov/whisker/background/index.htmhttps://phys.org/news/2012-12-doctoral-student-unravels-tin-whisker.htmlhttps://www.sciencedirect.com/science/article/abs/pii/S1359646218300319https://www.sharrettsplating.com/blog/alternatives-to-cadmium-for-plating-connectors/[Ask the Science Hank Couch]Wombat buttshttps://www.washingtonpost.com/news/speaking-of-science/wp/2016/10/06/wombats-have-buns-of-steel-and-they-might-literally-be-deadly/https://www.nationalgeographic.com/animals/2018/11/wombat-poop-cube-why-is-it-square-shaped/Caterpillar poophttps://www.sciencemag.org/news/2003/03/frass-fliesHydra butthttps://www.livescience.com/53980-terrifying-mouth-of-a-hydra.html[Butt One More Thing]Peru guanohttps://www.audubon.org/news/holy-crap-trip-worlds-largest-guano-producing-islandshttps://www.bbc.com/news/business-11153967

Hello and welcome to SciShow Tangents, the lightly competitive knowledge showcase starring some of the geniuses that make the YouTube series SciShow happen. starring some of the geniuses that make the YouTube series SciShow happen. Now, normally, I would say this week that, as always, I am joined by Stefan Shin. And this week, I am joined by Stefan Shin. But that won't always be true. After this month, Stefan is going to be saying goodbye to SciShow Tangents so he can do more of the things where he makes videos for the YouTube channel. So if Stefan's your favorite and he's the only reason you're listening, it was nice to have you be a part of the things where he makes videos for the YouTube channel. So if Stefan's your favorite and he's the only reason you're listening, it was nice to have you be a part of the podcast,

but I guess you can move on. Maybe Stefan will set up a live stream where you just watch him edit videos. Well, I'll still be hosting SciShow too, so that's right. Yeah, I'll still be around. But yeah, I don't know. Thanks for having me on the show for the last couple of years. It's been a lot of fun. I will be finishing out the season, which I'm very close to winning, so there's no way I was

going to leave until that. But yeah, I'm definitely sad to be moving on and I will miss goofing around with everyone every week. Stefan, who's your favorite co-host of SciShow Tangents? Ooh. You know, I'm going to say Sari, because I feel like Sari does a lot of behind-the-scenes work researching for the science couch question and did a lot of butt fact research, and Sari's just an unsung hero of SciShow Tangents. Okay. Thanks, Stefan.

I feel like if enough people say you're an unsung hero, which everybody says, then maybe you're kind of sung. Then eventually you just are sung. Well, here's the situation. In comparison to me, I get a great deal of positive feedback from the world at large. And so, like,

I don't need it. That, that we know. Okay. So it's either you or Sari. Okay. And someday you'll find out who my favorite co-host of SciShow Tangents is, but today is not that day.

Oh no. Stefan, what's your tagline? Hanging out the passenger side of my best friend's ride. We're also, of course, joined by Sam Schultz, who isn't going anywhere. Sam, are you a scrub? Yeah, I think I am, unfortunately.

What's a scrub? It's from the song that Stefan just referenced, which somebody could knock that off their bingo card now sari is confused by song what's your tagline gummy woim a gummy what woim what's a woim you know a gummy woim it just keeps getting better the more you say it. Sari, how do you stay warm living in Montana? What's your warmth strategies? Well, I think I am pretty cold resistant inside the house. Like I don't like wearing socks.

I find socks uncomfortable and constraining to my feet. I like wearing t-shirts. This is terrible news. You'll find out why in a moment. Oh, dear. What's your tagline? One long potato. And I'm Hank Green.

My tagline is the flash drive of Volcana. We must quest. Every week here on Tangents, we get together to try to one-up a maze and delight each other with science facts. We're playing for glory, but we're also awarding Sandbucks from week to week. And at the end of the year, whoever has the most Sandbucks gets to be the winner,

and we rename the bucks after you. We do everything we can to stay on topic here on SciShow Tangents, but judging by previous conversations, we aren't going to be great at that. So if the whole team deems your tangent unworthy, we'll force you to give up one of your sandbox. So tangent with care. It's almost the end of the year, which means that it is almost the end of season two of Tangents.

So first, that means that very soon we will find out who will be the buck title holder. That's very exciting. It won't be me. But also it means that this week we are celebrating science and friendship and the end of the season with episodes about each of our hosts. The topic of each episode in December will be one of us, and everyone else will be presenting facts about some of that person's

favorite things. And in the last episode of the year, we will announce the season's winner and the new name for the Tangent's currency. And so, as always, we introduce this week's topic with the traditional science poem, This Week from Me. Are you guys ready? Yeah. I think so. I'm a little scared, actually. Hello, my friends.

As you might well know, it's that day where we talk about me on this show. Usually it's whatever someone else wanted, but today, and I hope that you won't be affronted, it's all about me and the things that I love, like the rocky red planet that circles above, or butts being legs, or maybe just socks. Have I mentioned how much I love socks in these talks that we have on this show? Well, I'll do it today, because we're

launching a sock club for Charite! It's called the Awesome Socks Club, and it's ready to go. Awesomesocks.club slash tangent says the URL to know. A new pair of socks every month of the next year designed by a different, very talented peer. Every cent that we make profit in its totality goes to decrease maternal and child mortality. But it's only available for the next week. If you don't go right now, you will know true defeat.

Bring some joy to your ankles and be a trendsetter with some socks that will also make the world better. So pause the podcast right now. Do not delay. Awesomesocks.club slash tangents. Sign up today. It's very fitting because that's, I feel like this is also one of your favorite things.

Like, setting up a charity sock club subscription is such a Hank Green thing to do. Yeah. So everybody except for Sari should sign up for the sock club immediately. Sari hates socks because she doesn't like to be comfortable.

The sock club is only open until December 11th because we want to know exactly how many subscribers we have so that we don't create more socks than we need. So seriously, you should go sign up for it right now and you should use awesome socks dot club slash tangents so that we know that you came from this podcast. Actually do it today. It might close before December 11th. So, Sari, what is Hank? I'm going to look up the etymology of everyone's name. Hank, I went to William, which comes from Will Helmet, which are composed of

the two pieces, Will, which is what it sounds like, like a desire to do something, and Helm for protection. And Hank, which I looked up separately, is originally a short form of Hankin, which is a medieval diminutive of John, which is just so funny. Yeah. I only discovered that while I was doing a Vlogbrothers video on the origin of my name, and I was like, are you fucking kidding me? My mom named me my brother's name? But little teeny tiny version. Yeah. I'm like John, but cute, which actually works. That actually makes a lot of sense. Tracks. Well, I guess that means

that it is now time for True Tracks. One of our panelists has prepared three science facts for our education and enjoyment, but only one of those facts is real. The other panelists have to figure out either by deduction or wild guess which is the true fact. And if we get it right, we get a sandbox. If we

are tricked, then Stefan will get the sandbox. You can play along at twitter.com slash SciShow Tangents where we will have a Twitter poll. So you can vote for the fact that you think is most likely to be true. Stefan, what are your three facts? As we've learned so far, Hank loves unique socks. Which of these three very unique socks is real? Fact number one, waterproof gecko socks, which use pressure-sensitive adhesives to get stickier as you put your weight down on them, but then release naturally as you lift your foot.

While you wouldn't be able to climb up the side of the building with these, you could use them in the shower to gain traction or as footwear in work environments that require you to interact with wet or slippery surfaces. Number two, an inexpensive smart sock that can detect whether you are infected with malaria by detecting specific molecules in your foot odor. Progress has slowed in the global fight against malaria in recent years, and these socks could be especially helpful in identifying asymptomatic carriers. Or number three, a pair of socks with embedded microbial fuel cells that uses the power of your footsteps to continuously pump urine across the fuel cells so they can generate electricity. A potential application for this is as an emergency system for transmitting your coordinates if you had gotten lost on a hike. All right.

Okay, go ahead. We'll get there. Our three facts are waterproof gecko socks that you can use either in the shower or when you are working in a slippery environment that stick when you're pushing down but release when you are working in a slippery environment, that stick when you're pushing down, but release when you lift your foot. A smart sock that can detect whether you have malaria by detecting smells in your foot odor somehow,

or a pair of socks with embedded microbial fuel cells that use the power of your footsteps to pump urine through the system to generate electricity. Do I pee on my sock? Well, first of all, none of the awesome socks have any of these abilities. They're normal socks. They look cool.

They are designed to bring fun to you every month of 2021. And you can sign up now at awesomesocks.club slash tangents, but they don't do any of these things. Do not pee on the awesome socks. So I could not 100% confirm. I didn't read the whole paper, so I don't know.

I think there's a system of tubes within the socks that carry the urine through the fuel cells and then there might be a reservoir that you pee into to fill it up. They don't come preloaded. They don't have urine in them

when you buy them. Yeah, they don't come with urine.ed they don't urine in them when you buy them yeah they don't come with urine okay theoretically like urine would eventually lose its charge you need to have to pee again but like if you're lost in the woods no no big yeah you can keep peeing no one's gonna see you peeing in your shoes the the one that can detect malaria does it just like say you got malaria or does it like turn pink or something? What does it do? The word malaria appears on socks.

I had a cup from McDonald's when I was a kid. It was from the movie Willow. You remember, you know Willow? No, I do not. And when you poured your cool drink in it, Willow would appear. And like the Mad Mardigan and all of the characters from Willow would appear on the cup. And I was very enamored of it. So I imagine it's like that.

Probably Mad Mardigan appears. And it's like, you've got malaria. Rawr. Well, if you had said anything but Willow, I understood everything else of that. I've also owned cups that change color when you pour different liquids in them. Yeah. They probably had like Shrek on them though. I could also see you sending in the sock sort of like with Lyme disease.

You send in the tick to a lab. So maybe you just like walk around a little bit, get your sock real stinky, and then you send it to a lab and you're like, do I have malaria? Is it hard to test for malaria? Like would you be able to reach people with this sock test that you wouldn't be able to? You know, I have no idea. I imagine it's fairly easy to test people for malaria, but I do not know. Just based on my knowledge of things like allergy testing or whenever I've had to have a test,

like a blood test for iron levels or vitamin D levels, it's still something where I have to go to a place where people have specific test tubes and vials and stuff and they have to like extract something from me or do something to my skin. And this feels like a way you could make that more mobile and like send it to people. Yeah. Or just like have somebody come around and like pick up all the socks. Yeah. And is the gecko thing real or is that just from Mission Impossible 4?

gecko thing real or is that just from Mission Impossible 4? I weirdly just recorded a size show that talked about how geckos stickiness works. And based on that, this seems plausible to me. Okay. I think I'm going to go with the pea socks. I really, I think it's fun. I'm going to go with the malaria sock because I don't understand it, but it does seem like something that an epidemiologist would be like, that's a great idea. I was going to go with malaria socks too,

so I will stick with it. Oh no. That's right, isn't it? All right. It's time to go vote at twitter.com slash SciShow Tangents so that you can know if you got stumped by the inimitable Stefan Chin. Stefan, what is the correct fact? It's the pee-pee socks. Oh, no! No way! That's so dumb! There are so many better ways to get electricity than peeing in your socks! I don't really understand how this works, but apparently microbial fuel cells

can use any form of organic waste, and then they convert chemical energy into electrical energy through the action of the bacteria. And using urine to power these is not a new idea, but putting this whole thing into a sock is kind of the new thing here. Normally for these microbial fuel cells, you have a powered pump that is circulating the urine or whatever over these fuel cells. But they were not satisfied with that. They wanted a self-sufficient system that would be wearable tech and that could run only on human inputs. And so these socks are like, there's 24 flexible fuel cells that are

attached to the fabric of the socks, and then a bunch of soft tubing that carries the urine around. And the urine runs under the heels. So every time you take a step, it pumps a bunch of soft tubing that carries the urine around. The urine runs under the heels, so every time you take a step, it pumps a little bit through the system. There's also a built-in wireless transmitter, and so their sock was able to send a message to a computer that they had every two minutes. As far as applications, I mentioned transmitting coordinates if you're lost. They mentioned that the bonus there is that if you're getting a signal from that, then that means that the person is alive and well enough to be like peeing and walking around. So like it's a good sign if you're getting these coordinates from these pee pee socks.

So is there something to the malaria socks at least? Yeah. So there are socks involved, but it's actually they were training dogs to smell the socks, at least. Yeah, so there are socks involved, but it's actually they were training dogs to smell the socks for malaria. And so, like, they're asymptomatic carriers. There's, like, all these, you know, mutations in the protein, so the current tests maybe aren't picking it up. And so they need ways that are fast and non-invasive

to be able to diagnose it without having to test the whole community. And so this team is in the UK and they were training these dogs to be able to diagnose malaria by sniffing socks that had been worn. And so these were like socks that had been worn in Africa, were frozen and then transported back to the UK and then the dogs sniffed them and they had like a 70% success rate at identifying people who were infected. They had a 90% success rate at identifying uninfected people, but they thought that maybe the rates would be higher if they actually had the people or fresh socks, but this was

sort of a proof of concept that this could work. And I guess the malaria parasites do like people who have the parasite do generate some kind of distinct odor from their skin. And it changes based on what life stage the parasite is in, which is kind of weird. And then gecko socks. I just made up. I have no idea how geckos work.

There are pressure-sensitive adhesives, but they don't behave the way that I described. And there's like different types of them, but I don't think that's real. Yet. Who knows? It's up to you. Hank, did you like those facts?

I did. I did. And hey, if you want to pee on your awesome socks, that's up to you. Hank, did you like those facts? I did. I did. And hey, if you want to pee on your awesome socks, that's up to you. Next up, we're going to take a short break and then it'll be time for the Fact Off. Oh, welcome back, everybody. Sam Buck totals. Sari's coming in last so far with nothing. I have one for my poem. Sam has one for getting the fact right.

And Stefan has two. And that means it's time for the Fact Off. Two panelists this week, Sam and Sari, have brought science facts to present to the others in an attempt to blow our minds. The presentees each have a Sam book to award to the fact that we like the most, and to decide who's going to go first, I have a trivia question for you two. Unlike many planets, my second favorite planet is so well known to us humans that it does not have a date of discovery. It's portrayed on the ceiling in an Egyptian scholar's tomb.

The astronomical ceiling is the oldest known star map, and we can date it based on the position of the planets in the map. What year does this star map portray? No, I don't know when Egypt was. It was a while ago, Sam. Yeah. I'll give you that hint. I read and reread a book about mummies.

Like for some reason it was in my kindergarten classroom or first grade classroom. And whenever it was free reading time, I would go straight to the mummy book and then read it over and over again. So I think Egypt was like, I want to say 3000 BC

to whenever Alexander the Great came through. So in the hundreds BCE. Okay. I mean, Egypt is also still there. Yes, that's true. Ancient Egypt, at which time this star map would have been made, I'm guessing. Yeah. Boy, that's a long civilization. Not only was Egypt a long time ago, but it lasted a long time. That's way better than we're going to do. I'm going to guess 1,873 BCE. Whoa.

1,873 BCE. Okay. 1,800. So there's no reason for me to do anything except just one more or less than the number you just said. Yeah. So there's no reason for me to do anything except just one more or less than the number you just said. Unless you want to really make Hank and Stefan do some math to see which one was right. I'm going to say 3000 BCE.

Oh, wow. So you went as old as possible. Uh-huh. Well, that was strategically a poor choice. And also, in terms of reality, a poor choice because Sari was much closer. The actual year was 1534 BCE. So pretty close, Sari. Incredible. Is it Mars that is being talked about here?

Is that your second favorite planet? Yeah, sorry. We're talking about my second favorite planet, Mars. Is your first one Earth? Okay. Yeah. Everybody was like, my favorite planet is, I'm like, Earth. Yeah. You have to say Earth. it's by far the best one sam you go first oh great okay so hank lately has been at the center of a social media controversy for his inflammatory claim

that humans should not be eating grass and i didn't expect it to go here. Probably true. There are other animals out there eating grass that people aren't so sure should be eating grass. And one of those animals is house cats, which I assume Hank also likes because he has a house cat. And probably for as long as people have had cats, they've been seeing them eating grass and being worried that the cat was sick. One common explanation for cats eating grass is that they have an upset stomach

and they need to throw up, so eating the grass helps them throw up. But in 2019, a team of researchers wanted to put that belief to the test. So they took a survey of 1,000 people who had indoor-outdoor cats that they claimed to spend at least three hours a day observing. So these were people who were looking at their cats for three hours a day. It seems a little unlikely to me, but okay. The survey showed that cats eating grass was extremely common, with 61% of cats being seen eating grass at least 10 times in their lives.

But 91% of the people who said that they've seen cats eating grass have never noticed their cat being particularly sick before they eat the grass. And only 27% of them reported that their cat threw up after they ate the grass. So the team didn't think that the cats would be eating so much grass in order to throw up if that didn't really work that well and they were throwing up so infrequently. So the team took a look at wild carnivores commonly seen eating grass and other non-digestible plants to see what the heck was going on. So what they said was that basically all wild meat eaters are super full of parasites just from eating all their meat and stuff. Their digestive tracts are full of parasites.

And an occasional meal of plant matter would shoot their digestive tracts into high gear, which would basically help them poop out as many parasites as they could. So that's what they think cats are doing, except modern house cats aren't really carrying as many parasites as they could. So that's what they think cats are doing, except modern house cats aren't really carrying as many parasites as a wild animal because of like medicine and their diet is kibble and not nearly as much fresh meat. So most likely it's just an evolutionary impulse left over from their pre-domesticated ancestors. But if you think about it, they are also doing something that Hank thinks people should definitely be be doing which is getting a good dose of dietary fiber more of my favorite things they also said dogs eat way more than grass than cats do and they think it's maybe because

ancestor dogs are sniffing each other's butts so much that they were like huffing parasites out of each other's butts my cat goes and eats grass and then immediately pukes. 11% of cats puke very frequently after eating grass. But most cats don't puke after they eat grass. She's a special case. Sari, what do you got for us? Okay, I feel like I got to lay on the Hank's favorite things. But I chose this fact because Hank likes weird chemistry, science, mysteries, and space. So I

found a story that incorporates all three of those things. When you're working with metals, it's common to electroplate components to make a uniform thin surface of one metal on top. It can be used for decoration, like adding a thin layer of chromium on car parts to make them shiny, and for function, like how the same chrome car parts are usually more resistant to corrosion or easier to clean. And so electroplating for consistent surface function is also a really important part of making electrical hardware. And in the early 1940s, cadmium was really popular because it can make thin layers. It's super electrically conductive, and it doesn't corrode or wear very much, so it lasts a long time without maintenance.

conductive and it doesn't corrode or wear very much so it lasts a long time without maintenance except for one problem that was first formally written about in 1946 called cadmium whiskers so this is unintentionally vaguely cat related too but not because whiskers they're little metal hair-like structures that have a diameter of micrometers but a length of up to 10 millimeters or more so So basically much, much thinner than our hair, but pretty long for such a thin structure. And they are not useful at all. They are like pesky little stray cat hairs that gets everywhere and are a nuisance to the most important pieces of your electronics. Because cadmium whiskers act as bridges for electrons to hop between closely spaced electronic parts, which is especially risky in small

compact devices and causing short circuits and other failures. And after decades of research, we found tin whiskers and zinc whiskers too, but scientists can't really predict when or how badly these whiskers will form. There have been proposed mechanisms like that they're extruded to relieve stress on the metal. So like squeezing out a high pressure tube of toothpaste, but instead of tube of toothpaste, it's like a spike out of a metal surface. And it seems like scientists are sort of worried that this mysterious problem will continue to affect miniature electronics in the future because they are affecting modern ones. For example, metallic whiskers have led to short-circuiting

or failure of devices like pacemakers, maybe a pedal sensor in certain Toyota cars, or a space tech like at least three commercial satellites or an instrument on the Cassini space probe. All of these things needed to be electroplated because they aren't easily maintained or replaced, and so they wanted that like nice thin layer, but then whiskers happened and caused a crisis.

The extra danger of metallic whiskers in space because of the really low pressures is that they can vaporize into plasma and cause something called a metal vapor arc, which sounds really dramatic. I think it just destroys the electronics a little bit more because it's so high current, but I don't know. These little

metal whiskers, innocuous, can explode in space. And the only remediation NASA and other organizations really have is to stop using this electroplating made of pure tin, zinc, or cadmium and use alloys instead. But I just thought it was so weird that this thing that we discovered in the 1940s, which feels like a fairly simple material science problem to me like a non-material scientist that just like random spikes appear has still not been solved even after decades of research and it seems like a critical hurdle to overcome before we miniaturize electronics it seems like these are very fragile little structures and you should be able to just wipe them off. Yeah. Or zap them. And I just like blow off my little whiskers. Get some steel wool out, rub it down.

Well, you just like pull the pacemaker out of your chest, blow them off, and then stick it back in. Well, yeah, but before you put the pacemaker in, give it a little blow. Or does it continuously form? They continuously form. They like grow over time. That's not good.

So like that, I guess that is the part of the mystery that I did not tell so good in the story is that they grow over time. It's not like they form on a thing and then you send the satellite to space. It's like you send the satellite to space and then months later a failure happens and you're like, what happened?

I don't know, tin whiskers. So like they feel very innocuous, but you can't go fix them because your metal thing is in space or in a body or somewhere else in a nuclear power plant and can't easily be fixed. All right, Stefan, what do you think? You ready? You got some thoughts? Are you feeling cats' mighty grasses of an evolutionary holdover when it helped them expel parasites from their digestive tracts or mysterious metal whiskers that have stumped scientists for decades, forcing us to change how we make

electronic components. Yeah, I think I know. I think I know. Okay. Three, two, one. Sam. High score on episode for old scrub Sam. I just feel like I could eat grass one day if I need to, if I'm like, damn, I'm feeling a lot of parasites down below. You got a squirmy belly. Yeah. Stefan, if you're ever feeling like you have some parasites down below, you need to go and talk to your doctor. And that goes for everyone at home listening as well.

And now it's time to ask the science couch, where we've got a listener question for our couch of finally honed scientific minds except that this week it's just for me because it's me day and it's from at dan sexton riley who asks what is the most unique butt you can think of and what is so special about it i love this good hank question so i've got a favorite butt but i'm going to go through a couple interesting butts wombat butts are like uh really hard and like keratinous because they plug up their holes with their butts so they'll like get in their hole and then a predator will just attack their butt because if they like let the predator

in the hole it might be able to get its babies or something so the wombat just like sits in there and it's like you can't get through my butt that's really good there's a caterpillar and i can't remember what kind of caterpillar it is, that shoots its poop out really fast. So it's like I got a poop gun and that can scare away its predator or the predator sniffs out their poop. And so they have to get their poop far away from their bodies. But my favorite weirdest butt is the hydra. So hydra are like super tiny organisms, but multicellular organisms.

And hydra don't have mouths. And when it is time to put food inside of itself, it tears open its skin and then puts the food inside. And then it closes up its skin and it heals back together. Just like there was never, it just has like muscles on either side of its skin and it just like rips its own skin open, puts some food inside and then when it's time to poop

its butt is the same it just rips its body open with these muscles just like tears its skin apart and then poops out of its brand new gash that it has created in its own body does it always do it? I think I've asked this before but does it always do it in the same place? yeah, it has created in its own body. Does it always do it? I think I've asked this before, but does it always do it in the same place?

Yeah. It has like a location where its muscles can rip apart. Just get a sphincter, bro. Just grow a butthole, buddy. It's time. It's 2020. It's time to grow a sphincter.

If you want to ask the Science Couch your question, follow us on Twitter at SciShowTangents where we'll tweet out the topics for upcoming episodes every week. If you want to ask the Science Couch your question, follow us on Twitter, at SciShow Tangents, where we'll tweet out the topics for upcoming episodes every week. Thank you to at ScienceIsAnArt, at OneRoundPanda, and everybody else who tweeted us your questions for this episode. Final sandbox scores, Sam and Stefan lead with two,

Sari and Hank tie for last with one, which means that Stefan is maintaining his lead two points ahead of Sari, headed into our last month of the season and also Stefan's last month of tangents, which is just, when I say it, it makes my heart hurt a little bit, but it's okay, Stefan.

I will live on through my currency. It's possible, unless Sari comes and takes it from you. Uh-huh. Then your memory will be erased completely. Well, if there's anything I know it's that we'll all

eventually be forgotten. Thank you for listening to SciShow Tangents. If you like this show and you want to help us out it's real easy to do that. You can leave us a review wherever you listen.

That helps us know what you like about the show and also other people get to see what you like about the show too. You can tweet out your favorite moment from the episode and finally, if you want to show your love for SciShow Tangents, just tell people about us. You can also please go to awesomesocks.club

slash tangents to find out about the Awesome Socks Club. That's awesomesocks.club slash tangents. I wrote a poem for you. Check it out. Thank you for joining us. I've been Hank Green. I've been Sari Reilly. I've been Stefan Chin.

And I've been Sam Schultz. SciShow Tangents is created by all of us and produced by Caitlin Hoffmeister and Sam Schultz, who edit a lot of these episodes along with Hiroko Matsushima. Our social media organizer is Paola Garcia-Pietro. Our editorial assistant is Deboki Chakravarti. Our sound design is by Joseph Tunamedish.

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. So, Peru's islands are home to about 4 million birds, which includes birds such as the guanay cormorant, the Peruvian booby, and the Peruvian pelican. And all of those birds produce a crap ton of guano. Over a century ago,

that guano had amassed into deposits that were up to 200 feet deep. But because guano is so good for fertilizers and explosives, humans harvested most of it away to the point that these days the deposits are only a few feet deep. And they do all this harvesting by hand so that they don't scare the birds with any loud machinery. And these days, while they are harvesting at a more sustainable rate, Peru is still the world's largest producer of guano. We also have an episode about this on the SciShow YouTube channel, which I did the graphics for. Very synergistic episode. I tried to find a Pelican fact, but you've said all there is to be said about Pelicans, it seems like. My favorite Pelican fact is that they have a stomach just for bones.

They've got three stomachs and one of them is just for bones.