SciShow Tangents - Parasites with Sally Le Page

Episode Date: December 25, 2018

This week, we’re joined by evolutionary biologist and science communicator Dr. Sally LePage to talk all about parasites! How did we deal with them before modern medicine? Are there any parasites bigger than their hosts? And is parasite-ception a thing!?Sources:[Fact Off]Fruit fly fungus:Frog flatworm:https://www.nationalgeographic.com/science/phenomena/2013/02/13/a-flurry-of-frog-legs/https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4330773/https://link.springer.com/article/10.1007%2Fs00436-011-2451-zhttps://www.nytimes.com/1996/10/13/us/many-reports-of-deformities-among-frogs-are-puzzling.htmlhttps://www.ncbi.nlm.nih.gov/pmc/articles/PMC4636111/[Ask the Science Couch]Cuckoos: https://www.audubon.org/news/the-brilliant-ways-parasitic-birds-terrorize-their-victimshttps://web.stanford.edu/group/stanfordbirds/text/essays/Brood_Parasitism.htmlPlants:http://ipm.ucanr.edu/PMG/PESTNOTES/pn7496.htmlhttps://csfs.colostate.edu/forest-management/common-forest-insects-diseases/dwarf-mistletoe/[Butt One More Thing] - pick the one that we end up using (probably Hank’s)Tick anus:https://www.medscape.com/viewarticle/717730_2Poop bean sprout:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3192079/ 

Hello and welcome to SciShow Tangents, the lightly competitive knowledge showcase starring some of the geniuses that make the YouTube series SciShow happen. And also this week, a special guest. We're going to do things a little bit differently. I've seated my spot on the science couch to our very special, very smart guest, evolutionary biologist and science YouTuber, Sally LePage. Hello, how are you? I'm all right, thanks. How are you? I'm good. What's your tagline?

My tagline this week is, Beelzebub has a devil put aside for me. Oh, very good. We're also, as usual, joined by Sari Riley, writer for Complexly and various things. And I also want to know what your tagline is. What even are sprinkles? And also Sam Schultz is here. Hello. Welcome to the dummy couch.

Yeah, it's great to be here. I feel so much less pressure. Yeah, do you really? Yeah, no, not really. What's your tagline? Jolly old elf. Oh, is it our Christmas episode? It might be.

Jingle, jingle. I'm Hank, and my tagline is shoes are for shoes. Oh, gosh. My mind's blown. That is deep. Yeah. Is it, though? What is a shoe shoe?

It's shoes for shoes. The sole of your shoes is the shoe of your shoe. Okay. That's a much better tagline than mine. All right. So every week here on SciShow Tangents, we get together, four friends,

to try and one-up, amaze, and delight each other with science facts. We're playing for glory, but we're also keeping score and awarding Hank bucks. We do everything we can

to stay on topic, but we do have a podcast called SciShow Tangents, so it's possible that we will go off topic. If the topic that we go off on is deemed not worthy,

you have to pay a hank buck. So make your tangent worthwhile. We're a pretty open-minded bunch. We don't really panelize people very frequently. It's true. So it doesn't matter how wide a tangent it is, as long as it's interesting. Correct.

And as always, we're going to introduce this week's topic with the traditional science poem this week from Sam. I slipped right in your fishy mouth. Tongue's in the way, so I cut it out. Now we swim the ocean blue, you attached to me and me attached to you. I tried to help you with my little arms to capture food and not do much harm. But I must admit, your blood is yummy and I can't help but nibble things going to your tummy. You're my best friend friend I'll never leave you but lately I've noticed

your skin's a pale hue so if someday we should have to part I'll find a new mouth but you'll always be in my heart is that that louse that replaces the tongue of other fish

yeah I can't say its name Simothoa exigua it's like a little yeah a little a little crustacean-y guy. It like chews off the tongue of a fish and it's like, I'm your tongue now. Yeah. You just open a fish's mouth and there's a smiley little face looking back at you. They are kind of cute. They got cute little faces, but they got very bad bodies.

Would you want your tongue to be an animal? I wouldn't want any part of my body to have its own consciousness. What if it was loyal to you, though, and it could, like, crawl away and come back with stuff? Ooh, like a familiar. Yeah, except it's your hand

or something. Right. No, absolutely. I would have that be my shoo-shoo. What's a shoe shoe? Remember earlier in the episode? It's a callback. From five minutes ago. My brain's got some holes. Yeah.

Like, it would be great if my shoes were sentient. Oh, yeah. Just your shoes. Wouldn't it feel really bad for your shoes?

No, they might like it. Like, the grass doesn't mind being walked on. So, it would be like that. It would be evolutionarily adapted

to be a shoe. So it would enjoy the process of being a shoe. In the Hitchhiker's Guide to the Galaxy number two where the pig's like, I love being eaten.

Why don't you take a chop from my thigh? And it's just bizarre. And that would be like that except shoes. And they would love having your stinky feet in them. And that would be like that, except shoes. And they would love having your stinky feet in them. And it would be like, oh, I like how moist it is. Would you have to feed them?

No, you just slough off foot skin cells. I like this. Sam likes it. There's an ant that has a parasite that is like a shoe parasite. What? It's a mite that eats its leg and then attaches itself to the ant's leg and just sucks a little bit of lymph from the ant as it walks around. But you get your leg and then all the mite's legs help them grip to surfaces. So it's a bonus.

Oh my God. Why didn't I hear about that? I mean, I thought about for my truth or fail when I read about this tongue replacement bug thing. You called it a, what did you call it? A louse? Louse. Is that what it is?

I think it is, basically. I think so. So it lives in the sea. It lives in the sea. So it's not an insect. Some kind of crustacean. So taxonomically, they're the same.

Yeah. And I think it has multiple pairs of legs. I think there's some kind of sea louse. Because fish are always being attacked by lice. I didn't know sea lice were a thing.

So I'm over here on the non-science counter. I'm feeling fine about it. Wait, now I have a question. So would that be a parasite or would that be like a symbiote with the ant leg? It's fuzzy. It is fuzzy. Parasitism is kind of fuzzy. But the general definition is that it is an organism

that is taking resources or doing harm to another organism. And so because it's a long lasting relationship, it stays the ant's leg for a while and it's sucking away lymph and nutrients from the ant constantly, probably parasitic. But like, I guess the idea is like, if the benefit that the ant gets from having this better shoe, which I can't believe you had an anecdote of an actual science parasite shoe, but here we are living in the actual world. Is the benefit worth the loss in lymph?

And if so, then it's a symbiotic relationship. But like, it's probably not. Oh, wait. Mutualism. Mutualism. Thanks. What did I say? Symbiosis.

So symbiosis is both benefit. Okay. Mutualism includes where neither benefits, but neither really loses out. But I feel like in that case, both would be benefiting because the louse is getting lymph or the mite is getting lymph and the ant is getting sticky feet and act and like great kicks and everybody's like those are very fashionable does it have velcro yeah it depends on if the fitness right you'd have to it's way out yeah you'd have to ask the ant probably how i felt about it my guess is the ant's like i don't like

having my foot be eaten by a tiny, tiny bug. Did we even say we were talking about... The topic is parasites. Okay. Go around to it eventually. And now, we're going to start out as always with... So this is the part where

I, this week, have prepared three science facts for everybody's education and enjoyment, but only one of those facts is true. The other panelists have to decide which one is the true one. And if you get that, you get a Hank Buck. If you get it wrong, then I get a Hank Buck because I tricked you. And I have three facts about parasites, but more particularly about how humans, before the advent of modern medicine, dealt with parasites.

Because parasites have obviously been around for a long time, and medicine has not been around for a long time. So we had a whole lot of life where we just lived with them and tried to get rid of them in various weird ways. So, friends, tell me which one of these things was a way that humans dealt with parasites before the advent of modern medicine. One, in Japan, where they eat plenty of raw fish, those raw fish also sometimes had parasites in them. So in order to

kill those parasites, instead of cooking the fish, which might seem like the obvious thing to do, they would rub a caustic root on them, which would cause them to either leave the fish or die. And the name of that root is wasabi. Two, in the 1700s, the bark of a tree which indigenous people in Peru used to help with shivering was given to people in Rome who had malaria, which is caused by a parasite, to help stop their shivering. Instead, it killed the parasite and saved millions of lives. The responsible compound ended up being called quinine. Or three, Pliny the Elder thought that ticks generated spontaneously from grasses, and he thought they were the, quote, foulest and nastiest creatures

that exist. But his main suggestion for preventing them was to cover a person in the leftover dregs from a pressing of olive oil mixed with wine, and then let the person sit in the sun all day, and that would make ticks less interested in them in the future. So we have wasabi was used to kill parasites. Two, accidental malaria cure. Or three, Pliny the Elder was wrong about stuff, which is, that's true. But particularly, he was wrong about leaving someone in the sun

while covered in olive pressings and wine. So this is a tricky one, because I know that quinine derives from a South American bark and is an anti-malarial, and that malaria was in the Mediterranean around the time of the Romans. It's whether all of those came together

to be a true thing. Whether there was trade between South America and ancient Rome is my biggest question in that fact. Well, not that ancient Rome. 1700s. Oh, not ancient at all. No, no.

Oh, okay. So that is likely, in my opinion. I agree. And this is why I don't like Hank's facts, because they're mostly true. And there's something that's wrong about it. But I do know that the story of quinine has something to do with,

I don't know when the dye came in and when we realized it was an antimalarial agent in relation to the dye, like the purple moving versus if we just tried sampling part of the tree and turned that into medicine. But I will say, as this is called tangents, that that is where gin and tonics came from. Yes. Because quinine is very bitter. And it's in tonic water. I hope it's not the last one because that one is more boring than the other two. Yeah.

But that makes me think it could be that one. And I feel like I've heard the dye part as part of the origin story for them finding out about it being anti-malarial. The last one sounds like Hank just made up a story to me. at being anti-malarial. The last one sounds like Hank just made up a story to me. Because like, Flanee the elder did whatever he wanted.

And I don't understand what the scientific benefit of rubbing olive oil and wine on someone would be. And I feel like even if he made things up and theorized randomly, he had a reason

behind all these things. If stones are falling from the sky and those are dinosaur teeth or whatever, he had a reason behind all these things. If stones are falling from the sky and those are dinosaur teeth or whatever. But he had a reason for that and had some story to tell around that. Wait, what?

There was definitely a thing where he thought that fossils fell like as a fossil rain. And he was like, that's where they come from. Or something like that. What a dummy.

Yeah, he had some stuff wrong. But hey, it was a different time. That's true. And then wasabi on fish. Mm-hmm. That could be the sleeper. Like, that could some stuff wrong. But hey, it was a different time. That's true. And then wasabi on fish. That could be the sleeper. Like, that could be the one.

I mean, it could be. Sounds cool. I just don't think that rubbing it would make a difference. There are communities in Southeast Asia where they eat so much seaweed that now they have the genes for digesting seaweed in their genome. Yeah, I think we recently talked about that on SciShow. They have mutated to be able to eat a food that you shouldn't be able to eat,

which is also the case with like me and milk, to be clear. It's a relatively recent mutation that allows us to digest lactose. Do we get it from another thing? We always have it at birth. So normally we lose the ability to produce it as we grow older because we only need it as a child to solidify the milk in our stomachs to make it easier to digest right but as humans we then lost the switching off process during adolescence oh because we like milk too much we like milk so much yeah just gotta just get it

from a different animal we got this big old thing. Just squeeze it. Yeah. Parts of that big old thing are very squeezable looking. I'm not saying it was a weird decision. The babies were squeezing it. They were like, let's do that with hands instead of mouths. Yeah, yeah, get out of here. Or let's start with mouths and then probably do the transition eventually.

Hopefully soon. All right, I'm going to make you guys guess. Sam, you want to go first? I think I'm going to go with the wasabi one. He's going to go with wasabi. He thinks it's the sleeper. I'm going to go for the anti-malarial. Quinine. I'm going to go for wasabi too. Oh, double wasabi. Oh, God. Sarah, you got to go with your instincts. It was quinine. Oh, no. So we're going to start from the top.

Wasabi does have antibacterial properties, and there is question about whether wasabi was first introduced to sushi, not because the meat was dirty, but because it was prepared by dirty knives and dirty hands. From what I could tell, this is something that people say, but something that's not necessarily true. I also saw lots of people saying that it was used to prevent parasites. That's definitely not true. I just don't think it would work. Parasites are burrowed inside of the fish flesh.

And for the most part, fish don't have parasites, especially the ones that are eaten in Japan, for obvious reasons. They figured that out over the years of eating fish. Second, yes, this is all just true. And it's a fascinating story of how this, it was a muscle relaxant, quinine, in addition to being bad for the malaria parasite. And so it was taken in South America as an anti-diarrheal drug so that it relaxes your colon and your small intestine to prevent it from squeezing out your poop too fast and uh that's the technical that's how diarrhea works yeah it's the opposite of how i would think well the pain is the spasming yeah okay and then it shoots out well it just doesn't it goes it goes through too quickly so your water doesn't get absorbed i understand okay and then like i've had diarrhea It goes through too quickly, so the water doesn't get absorbed. I understand. Okay.

And then, like— I've had diarrhea. And, yeah, and so, like, in that exchange, Europe got quinine, which prevented malaria, and the Americas got malaria. Oh, thanks. Yeah. Nice. That was a great tradeoff. But But yeah, so they started to give it

to people in Rome who were shivering during that portion of malaria where you like get really feverish and shivery. And then they just got better. And they were like, forever, they thought it was just really good at preventing the shivers, but it turned out it was actually preventing the disease. There was so much malaria in the Mediterranean that there is a natural resistance to it in the genetics. So the same way sickle cell anemia in Africa bears some resistance, there's beta thalassemias, which are other blood disorders,

have quite a high incidence in the Mediterranean because of the amount of historic malaria in the area. Which is now mostly gone. Yep. Which is wonderful. But could come back because, you know, global warming. Sure. Yay. Right. That's why we live in Montana, Sally.

And finally, Pliny the Elder was wrong about a bunch of stuff. And we're going to talk about one of the things he was wrong about in But One More Thing this episode, which, Sally, is the portion of the episode at the very end where we have a butt fact. That's the portion where we have the butt fact? We can have nowhere else. I mean, we have a lot of other ones. That one just where we have a butt fact. That's the portion where we have the butt fact? We can have that. We have a lot of other ones.

That one just has to be a butt fact. Right. But this was a sheep dip during ancient Roman times that was for making the sheep's wool better, preventing them from being scabby, and getting rid of their ticks, was to dip them in olive dregs and the dregs and like the leftover leavings from pressing wine.

But that was not from Pliny. That was from Marcus Portius Cato, who wrote the Roman farm management guide. Oh, yeah. Martius, love his work. Yeah. I read quite a bit of it. It sounds interesting.

He was really into how to prevent tics. And part of it was you had to leave it on them and let them sweat for two days. And then you had to have them run into the ocean. Was this a real thing that worked or not? I have no idea. Okay. They have better ways of preventing tics now. Sure.

So somehow I got two Hank bucks out of that. Sorry. Even though as soon as Sally opened her mouth, I was like, oh, dang it. I'm in trouble. I really thought I did hear the die thing at some point. I didn't come across that, but it's certainly possible. Before we get to the fact off with Sally versus Sari,

oh my gosh, this is going to be intense. We're going to have a little bit of an ad break. See y'all soon. And we're back. We've got some results. Sally, you have one Hank Buck. I have two Hank Bucks. Sam has one for his poem.

Oh, yeah. Well done on that. I almost forget that part. Thank you. Come one Hank Buck. I have two Hank Bucks. Sam has one for his poem. Oh, yeah. Well done on that. I almost forget that part. Thank you. Come in. Yeah. Last. There is last and has

no opportunity to come back. This is not really a game that's designed for it to be fair. And now it's time for the fact off. So get ready.

Two panelists have brought science facts to present to the others in an attempt to blow me and Sam's minds. So we each have a Hank Buck to award the fact we like the most. If we hate both of the facts, we can just throw the Hank Buck away. So who goes

first in our fact off? Did you know that the word parasite comes from the Greek word for a person who eats at another person's table? So the person who's going to go first is the person who most recently ate at someone else's table. I mean, yeah, I ate half an hour ago and all tables in the US are not my table. I don't eat at tables very often. This is true, you ate lots of desks. So I guess Sally goes first because you ate at my old dining room table.

So because it is about parasites, I thought I'd do this cool story. It's from 2015. And you may, it's so odd to say this, but you may know about the parasite cordyceps already, which is a fungus that infects ants and makes them climb up high. And then it's amazing that so many people

already know that they're like, oh yeah, I know about cordyceps. But this is a different thing. And firstly, it infects fruit flies. And I've just finished my PhD on fruit flies. That is one reason for choosing this. So it infects Drosophila melanogaster. And it's a fungus called Entomophthora musca.

Good. Which literally means destroyer of flies. And it's a fungus that similarly makes the flies climb up and then it eats all of the fatty tissue first, leaves all the vital organs. Then when it's done, it changes the cognition of the fly so that it climbs up to a high point, fuses its mouth parts with a leaf,

and then bursts out and it fires spores at 21 miles an hour. But that's not the fact. Okay. That was a pre-fact. The fact is this parasitic fungus is only parasitic when it is itself parasitized by a virus. So it's double parasitism. But when it doesn't have the virus, it's like,

cool, I'm just a regular fungus, no big, I don't want to eat a fly. They can only find them together. So at first, they try to sequence the fungus's RNA, which is like what genes are actually being switched on, and they found 20% viral genes. But that's no biggie. Whenever you get infected by a virus, there is a chance that some of it will enter your genome.

I've got virus genes. Yeah, exactly. But then they found out that this virus normally directly infects insects. And insects and fungi are in no way alike. Okay. And so they're like, what's going on? And so somehow there is a virus that normally infects insects

that now infects fungi in order to make them infect insects and then changes their brain. So they explode? The flies explode? So the flies explode. So they describe it as their wings lift up like car's doors in a sports car. And then, yeah, then the fungus bursts out of it and the fruiting bodies shoot the spores out.

Cool. All right, Sarah, hit us with your fact. So mine's a little bit older. In October 1996, the New York Times published an article about mysteriously deformed frogs across the U.S. and Canada. Some had stumps where their legs should have been, while others had way too many. So like four sprouting from the same point or legs all over their body. And this especially happened in Minnesota wetlands where researchers were having trouble

finding places without abnormal frogs. So like the majority of the wetlands had some sort of deformed frog. People were pretty weirded out, citizens too, and they set up state hotlines. And they were worried that pesticides or other toxic pollutants were messing with frog development and somehow that could affect humans too. But then within a couple years,

we figured out that a parasitic flatworm called Riberia was to blame. And it's because the larvae of larvae, the larvae of these flatworm burrow into tadpoles and create cysts by their limb buds, which is the point in the tadpole where their limbs develop from, and seem to release a bunch of a chemical called retinoic acid, which plays a key role in the cell biology of early development, among other things. This is because frogs with deformed legs are more likely to be eaten by hungry birds like herons, which is where the parasite wants to be to restart its whole life cycle. And its whole life cycle has a ridiculous number of parts. So step one, it sexually reproduces and

lays eggs within birds, which get spewed out in their poop and end up in water. Underwater, the eggs hatch, and then the first stage infects aquatic snails. They eat the internal organs of the snails to make them sterile and then reproduce asexually within the snails to produce a different larval form. Oh my God.

And then that larval form is what infects tadpoles, messes with their development, creates weird frogs, and then the cycle continues. Some people think there's intelligent design. It has two different forms

of sexual reproduction. Or there's asexual reproduction and sexual reproduction both yeah holy cow I feel so sorry for aquatic snails

they seem to be one of the hosts for so many different parasites they're very porous right pretty easy to get into

an aquatic snail when like all of your surface area is mucous membrane it's just like I'm in is that the parasite's hacker voice to an aquatic snail. Yeah, when all of your surface area is mucus membrane, it's just like, I'm in! Is that the parasite's hacker voice?

So they give them a bunch of legs so the birds are like, mmm, tasty. Yeah, you can't run away from a bird if you've got 18 legs. Or you can run 18 times faster. Or you can hit the super frog. I also love the idea of a state hotline. Like, there is a scourge of multi-necked frogs.

If you have seen them, please call this number now. There's a scary frog in my yard. Super freaking out. Because they put retinoic acid on newt limb buds. Because newts are really good at regenerating their limbs. And I seem to remember a lecture where they're like and it's all driven

by retinoic acid because if you chop off a newt's leg it can grow it back and if you put retinoic acid on it it will grow it back

faster I think that's interesting it makes its own it makes its own so even as an adult it's like the equivalent of chopping off your hand and growing back your hand

yeah right but can I get 17 hands? Do you want that? We could try. Well, I think that was a diminishing returns on hands. Where would you even put them all? I don't know.

Up your arm? Or would they be tiny little hands at the end of your finger so you would have fractal hands? Yeah, really what I want is an extra pair of fingerprints so I can do crimes. You can just use latex for that. You don't need a whole new hand. Oh, we should do a crime science episode. Teach people how to do the perfect crime.

I'm going to go ahead and spend a Hank buck on this because there's no way you guys are going to think this is worthwhile. One of my advisors in undergrad was trying to write a mystery novel in which one of the major plot points was that he got a bone marrow transplant,

like the criminal got a bone marrow transplant to change his blood type. And I was like, but DNA, man. And he was like, yeah, but they only test the blood type in the book. And I'm like, but why? It's like 2001, man. We got DNA now. Could he have said it at a time when they didn't just test the DNA? Yeah, maybe he should have done that. He should have done that.

Let's steal his book idea. But there'll be no records at all of this man undergoing a bone marrow transplant. Right. Yeah, he does it in an illicit bone marrow transplant, in an illicit bone marrow ward. But apparently you can, like, sometimes when you get a bone marrow transplant, your blood type changes.

That doesn't surprise me. Yeah, I mean, it makes sense. Like, if you have diseased bone marrow and like the reason you're getting a bone marrow transplant is to have healthy bone marrow and it's from a person who has a different blood type, then that's where it gets made. I'm mostly amazed that the body wouldn't reject it if it's producing a different blood type.

Apparently that's a different set of things. So like, obviously you can't give like one blood to another type of person, but like certain blood types, I think you can. Oh, I suppose if you're O negative, you could give it to anyone. Yeah. Something like that. So yes, we have to give points away.

That's right. Sarah, your fact was? Frog legs. They're deformed frogs. Yeah, that's better. And Sally, your fact was? A fungus that parasitizes flies is in itself parasitized by a virus. That one has two parasites on it. It's true, and that

parasite, the virus wants inside the bug, and so does the fungus, but the fungus might not even want to get inside the bug without the virus. I'm going with Sally, because I think a virus that affects a fungus that then affects the brain of a fly is too much. Too much. It's too much.

You can just give it to her. It's fine. It's very cool. No, I kind of like, like, you're just spooky. I do like the idea of a whole pond full of frogs

with the wrong number of legs. Yeah, like a whole state full of swamp full of frogs with the wrong number of legs. So I'm going to give it to Sari. All right. Did it get fixed?

I don't think so. I think it's still an ongoing problem. Okay. But it's good for the herons. It's good for the herons and it fluctuates in levels. I don't know if it's as bad as it once was, but now we have an explanation for it. And we found things like an increased biodiversity in the ponds helps negate the parasite because otherwise if like it's one species of frog, they're all getting taken over by the parasite. They're all getting eaten. They don't have a chance to bounce back. But if many different amphibians are getting infected, then the infection rate is much lower. Is it actually good for the herons? I mean, they get something to eat and the parasite doesn't really affect them. I'm sure it steals

some nutrients, but it just like comes out in their poop. It's worse for snails, worse for frogs. Grow better skin, guys. It's time for Ask the Science Couch, where we ask listener questions to our couch of finely honed scientific minds that this week I am not sitting on. Dylan at Physicinicism asks, are there any examples of parasites that are bigger than the animals they exploit? Ooh, good question, Dylan. This was a good question.

I bet there is. I was thinking about brood parasites because cuckoos, so when a cuckoo lays its egg in the nest of another bird, that is called a brood parasite. And I looked up the numbers. So a cuckoo can be about 130 grams. Don't ask me what that is in Imperial. And the birds that it parasitizes,

it's like the meadow pipit, can be 15 grams. So that is an eight times larger than... Than the mum? Than the mum. And the mum doesn't recognize. And it has a supernormal stimuli with a massive gape, the colour of the

inside of the bird's mouth. And so the mum's just like, I have to feed it. And you see these really sad images of this whopping great big bird in this tiny little nest. And the mum is obviously so much smaller. And she's still feeding it. She loves her giant son. oh yeah i know yeah just

because your baby's giant doesn't mean you don't love it so i mean there are so many interesting things about cuckoos the baby as breaks its egg really really quickly so it's still a kind of pink jelly bean size thing and pushes the first thing it does is pushes all the other eggs out of the nest when it's still a jelly bean when it's still a jelly bean you see this tiny I think it's still blind at this point

tiny little jelly bean and it's just using its shoulders to push out the other eggs and the eggs themselves so you get different kind of classes of cuckoo that specialise

on a different species so that their eggs will perfectly match the egg color. And there's so many amazing adaptations between cuckoos and the birds that they parasitize. I really thought that they just got so big that the other babies fell out of the nest. No, certainly with the Eurasian cuckoo, they push them out.

Oh, no. Oh, my God. I'm going to get that little jelly bean, knock it over the head and say, you need to learn some manners. But cuckoos, or certainly the European cuckoo, is red-listed at the moment. It's really not doing very well. Well, maybe I'll… Maybe.

It's such an emotional rollercoaster with cuckoos, you know. Because it's an evolutionary arms race, too, because the birds that they parasitize are trying to recognize different colored eggs or notice when a baby is different. Like a baby that hatches way too early and starts shoving eggs around and be like, maybe you're just food now.

They even create alarm calls so that the actual mother bird will fly off so that the cuckoo can swoop in and lay the egg when the mother's gone away. So they imitate the other bird's alarm. Yeah. If they think it was a hawk that swooped by, they won't check their eggs. Whereas if the mother bird sees a cuckoo around, they're much more likely to look at their

eggs and say, hang on a sec, that one's not quite right. Man, birds need to get smarter and be like, I had four eggs, now I have five. Yes. But then you don't know which one to peck. Yeah, because we can notice the difference, but the birds... If a human sees a nest with two different types of eggs, oftentimes we can see a color

that the birds won't be able to observe or things like that. But also the eggs just genuinely are very, very similar. If you see the correct cuckoo egg next to what it should be they are

so good at mimicking it is incredible like even the spots and the patterns on the egg it's amazing there is a bird

the superb fairy wren they teach their embryos a password inside the egg and so they're talking to their chicks. I don't know exactly how it happens,

but there's some sort of communication. Like they tap on the shell with their little baby beaks? It's not a password tapping. It's a password song called an incubation call. So the moms just, as soon as they lay their eggs, it sounds like they start calling to them and talking to them and singing to them. And when they hatch, I think they have to repeat back this very specific password.

And the cuckoo eggs or whatever brood parasite has laid eggs in their nest, those chicks don't have the ability to learn this call, so they don't remember it. They don't do it. And then the mama's like, I'm going to kick you out of the nest or possibly just not feed you or possibly just eat you. Yeah. All right.

Thank you to our science couch. That was wonderful. I feel so educated. If you want to ask a question to our science couch, you can tweet your question using the hashtag Ask SciShow. You can also follow us

at SciShow Tangents on Twitter. We're at SciShowTangents.org if you want to find us and share us and tell people about us. Thank you to Lena Garner and Tony Espinoza and everybody else who tweeted us your questions this week. Our final Hank book tally. Sarah, you have one Hank book. Sally, you have two Hank books. Hank, you only have one because you went on your weird bone marrow novel tangent and I didn't appreciate it. I took away one of my own Hank bucks. And Sam, you have one.

Sally, you're our winner. Yay! And Sally, where can we find more of what you do? Like shed science and sofa science and this thing that I'm about to do. You are about to do an interview on my channel. You can go to my YouTube channel, youtube.com slash sallylepage. S-A-L-L-Y-L-E-P-A-G-E. That is exactly right.

I did it. If you like this show and you want to help us out, you can do that, one, by leaving a review wherever you listen. Thank you to Yona L and LoveMyDog21 for doing that. It is super helpful and it helps us know what you like about the show. Second, tweet out your favorite moment from the episode so that we can look at it and laugh because like, yeah, you're right. That was funny. And finally, if you want to show your love for Tangents, you could just tell people about us. Thanks for joining. I have been Hank Green. I've been Sam Schultz. I've been Sari Reilly. And I've been Sajida Page. SciShow Tangents is a co-production between Complexly and WNYC Studios. It's produced by all of us and Caitlin

Hoffmeister. Our art is by Hiroka Matsushima and our sound design is by Joseph Tuna-Medish. Our social media organizer is Victoria Bongiorno, 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. Pliny the Elder also thought that ticks were in a class of animals that didn't have anuses. And so they just ate and ate and ate until they exploded and died.