Radiolab - Gonads: X & Y

Episode Date: June 30, 2018

A lot of us understand biological sex with a pretty fateful underpinning: if you’re born with XX chromosomes, you’re female; if you’re born with XY chromosomes, you’re male. But it turns out, our relationship to the opposite sex is more complicated than we think. And if you caught this show on-air, and would like to listen to the full version of our Sex Ed Live Show, you can check it out here.  This episode was reported by Molly Webster, and produced by Matt Kielty. With scoring, original composition and mixing by Matt Kielty and Alex Overington. Additional production by Rachael Cusick, and editing by Pat Walters. The “Ballad of Daniel Webster” and “Gonads” was written, performed and produced by Majel Connery and Alex Overington. Special thanks to Erica Todd, Andrew Sinclair, Robin Lovell-Badge, and Sarah S. Richardson. Plus, a big thank you to the musicians who gave us permission to use their work in this episode—composer Erik Friedlander, for "Frail as a Breeze, Part II," and musician Sam Prekop, whose work "A Geometric," from his album The Republic, is out on Thrill Jockey. Radiolab is supported in part by Science Sandbox, a Simons Foundation initiative dedicated to engaging everyone with the process of science. And the Alfred P. Sloan Foundation, enhancing public understanding of science and technology in the modern world. More information about Sloan at www.sloan.org.  

Wait, you're listening. Okay. All right. You're listening to Radio Lab. Radio Lab. From W. N. Y. C. See?

Yeah. GONADS, episode three. I'm Molly Webster. Hello? Hello? Are you still there? I'm still here. And this is my mother, Mary Webster.

Yeah. But, but, yeah, no, the bedbugs are such a freaking pain. Oh, it sounds awful. You have to vacuum all of the baseboards. You have to vacuum the floors. You have to vacuum the door jams because they crawl up the walls when they're trying to get away. Oh, Molly, that sounds awful. So I recently called my mom for, I guess, to catch up.

But also, I had a work question. That's been bugging me. It was on my mind. Yeah. So I asked her, mom. I've been working on this story, and it made me wonder what you would have named me if I was a boy. You would have been named Daniel. Dad always liked the name.

And if we ever had a boy, dad said he was going to name him Daniel. And I said, if that's what you want, go for it. You know, because he didn't want a junior. He wanted a little Danny. Instead, he got a Judy, Chrissy, Peggy, and Molly. Your poor father. My glucky father. If you had come out, boy, you would have been Daniel.

Yes. Wait, all of us? No, well, you see, no, we went Daniel for a boy, not for everybody. You were just ready. Yeah, well, we didn't know. When a boy came out, it was going to be a Daniel. You know what I mean? That was it.

So this is just going to sound ridiculous, but I called my mom because all these stories that we've been doing in the series, they do make you think about fate. Like even if you think about the first one where they're the primordial germ cells and they're holding on to all sorts of possibilities and futures and then chromosomes step in and no more infinity. You're just like shunted onto a path. I guess I

I guess asking my mom about Daniel was just like a clumsy way of getting back to what feels like a really pristine moment, like a moment where no decision had been made, where you exist totally unblemished by life and choice and fate, unless maybe life isn't so fateful. Case in point, David's our cower. Hello. Hi. Actually, I'm just going to make, I don't like correcting people, but I'll just correct you.

My name is pronounced Zarkover. Zarkover? Zarkover, yep. Because it is a W, right? I'm not miss spelling it in my head. For the sake of my parents, I pronounce it with like a V. It's essentially Polish. That's good.

And you work at the University of Minnesota? Yep, that's right. What do you do there? Genetics, cell biology, and development. That seems scary. It's broad. Anyways, the reason I called Zarcover was because I came across a series of experiments that he did that just straight up

kicked me in the gonads. Okay, so... To begin. This was back in the early 1990s. Zarkover was working in a lab doing genetic stuff. In worms and flies and mice and things. And...

One day? Presto, we got lucky. He and his team discovered a brand new gene. Yep, that's right. They saw it in mice and gave it a name. I unfortunately am responsible for this. It's DMRT1. DMRT1.

DMRT1, yep. Dmerth one. I keep trying to... say DRM-T. Yeah, it's a nightmare. I'm very sorry for that. And what was interesting was that this gene was in mice, but also in humans. And in the male mouse, it was expressing itself in the testis.

I never know how to say it. Testes, testes. Testicles? Testicles. Is that a single? Yeah. Okay. So, yes, we found this gene and humans had it in the testes. and the question we had was whether it was doing something or not. Like you've got genes in your eyes that are making chemicals

that are making your eyes the color they are. This gene, DMRT1... What is it doing? We wanted to know if it's involved in maybe making sperm. Or... Maybe it just hangs around. It doesn't matter. It doesn't do anything. You know, we don't know.

And so they're like, let's mess around with it and see what happens. But you can't do that experiment in humans. No. So instead, they get some... adult male mice. Perfectly normal, fertile males that are making sperm. And we use some fancy molecular genetic tricks. And so basically...

It's kind of a mean trick, but it's genetics. They cut the gene out. We did that. And then they take a slice of the testis, and they look at it under the microscope. And it didn't look like what we would have expected. And what they expect to see is that these are the cells that help make sperm in the testis. and normally they're kind of tall and lean. Long and skinny.

But suddenly, they were different. With DMRT1 gone, they had gotten smaller, rounder. And Zarkova was like... This was not something that was supposed to happen. What is going on here? What are these things? Then he realized that the cells are making estrogen. And he was like, oh, I think what is happening is that the cells in the testis turned into ovary cells.

Wait, what? Wait, this is a male mouse. Yes. So you're saying this male mouse now has ovary cells in its testicles? Yes, these are cells that are changing their sex. That's insane. Can we just have like an exclamatory moment? Like, were you like, whoa, is that possible?

That happened? What is, you know? What do you say? For us anyway, the greatest of all scientific exclamations is that's weird. So we had a VAT's weird moment. And just to take this weirdness, like, one step further, a group of scientists did a similar experiment in adult female mice, where they did, like, the same fancy molecular genetic tricks.

Only this time they knocked out a female gene in the ovary. And when they went to look at it, the ovary is trying to kind of reorganize itself into the testes. Wait. Mm-hmm. You're saying in both cases there's one gene that's flipping the sex from male to female in the back. Yes. One gene.

One gene. How many genes do we have in our body? I don't know. Like tens of thousands. Whoa. And just one is doing this. Which is a weird concept to think of because we typically connect like sex or gonads to chromosomes. At least I do like an X and a Y is a girl and a boy.

So how could a gene step in and reverse that? Yeah, because I thought chromosomes were lots of genes. There are these, like, massive things. One gene is so tiny. Gene to tiny chromosomes are much bigger. And I think the answer to that is that when you get down to sex, like what makes us one sex or the other, it's not, it doesn't work exactly like we thought. Like take, for example, the X and Y idea.

This like chromosomal narrative we have of biological sex, it's a specific way of thinking about things from a certain moment in history. that we are potentially starting to rethink? I think it's helpful to see sort of the history of how we understand sex in a longer time frame. So let me bring in this guy. I'm David Page, biology professor at MIT. Okay, where do we start?

Oh, my gosh. Well, we're going to go, so let's see, we could go off the rails in any number of directions here, all of which would be quite productive, but let's see. So let's go back to the 1890s. Yeah, that definitely is 1890s. So genetics was in its infancy, Mendel, peas, all that was happening. And people had been pondering for millennia.

Where do boys and girls come from? Now, when it came to how you look, people thought mom and dad clearly involved. Because people had realized, you know, that children ended up growing up looking something like their mother and their father. Like maybe you have a chin like your dad and nose like your mom and a hair that's a little bit of both. There was a kind of blending of mom and dad to make you

you. Right. But when it came to why you were the sex you were that was a mystery. Because there was no blending. You ended up being like either your mother or your father. One or

the other. Therefore, it must not have anything to do with heredity. It had to be imposed from the outside in some way. So people came up with all kinds of ideas for what made you a boy or a girl. The phase of the moon, at the moment of conception. Cold, dark moon, definitely a girl. The state of the economy. Wouldn't be surprised, down economy, girl.

Yeah. Everything that was bad was given to women. There was what the mother ate, mom's body heat, stress. All sorts of crazy things. And then, um, in 1923... We started looking elsewhere. But how do we inherit our characteristics? For an answer.

Chromosomes. Chromosomes. Chromosomes. Determine our physical appearance and our sex. In 1923, a scientist looking down the barrel of a microscope discovers two new chromosomes. An X and a Y. Called the sex chromosomes. But I just want to hit pause here.

Okay. I came to find out actually from David Page that the X and Y chromosomes do not look like an X and Y. Wait, they don't look like the letters? Oh, no, no, no. No, when they first discovered them. They were blobs. Under the microscope, they just look like these misshapen clumps. I'd say kidney bean like.

The X looked bigger, the Y looks smaller, but that's it. That's so interesting, because there's something about the shape of the X and the shape of the Y, which read as gendered letters. That feels so, yeah. Yeah, because like the Y has a little. stem on it, which is sort of penis-like. There's like a duality or something in the X, which feels like, you know, ovaries and breasts or something. Like, there is like a, there is something about those letters.

So I was totally shocked when he was like, there's no real reason they got those letters. It was totally arbitrary. Anyways, when they found these chromosomes. It was clear that if you had X, X, X, X, chromosomes, you would develop as a female, anatomic female. And if you had a Y chromosome. So your X, Y. You would develop as an anatomic male.

That's right. A boy. That was the thinking. So you see, Roger and Susan are born and home. But then, that idea got more complicated. Yeah. Yeah, when did you intersect with this story? The summer of 1979. Page was at MIT.

First year of medical school. And the DNA revolution. So far tonight, we've been bringing you news of the world around us. was just beginning. Now we have news of the incredible world inside us. He was involved in what he describes as like the precursor. To the human genome project. What would become the human genome project,

working with a group of senior scientists who were envisioning maps of the human genome. An encyclopedia of man. We'll know the complete set of instructions, which made people. And we began to look back at some exceptional human individuals who had not been understood previously. That saliva test.

Women revealed that Maria had a set of X and Y chromosomes. Who had an X and a Y chromosome. Like most men, women usually have a pair of X's. And they were also looking at men. Who had an altogether male anatomy. Penis, testes. But whose chromosomes appeared to be those typical of a female. XX.

And for Page and other scientists, they were like, oh, there must be something more happening here than, just like the chromosome. There must be something deeper going on here. So we might actually be on the trail now of the secret. So scientists across the world started looking at these people's chromosomes. And what we found was that a few X, Y, females, were actually missing a little bit of the Y chromosome. With these X, Y women, a little bit of the Y wasn't there. And the bit of the Y that the X, Y, females were missing was the same bit that was present in the XX males.

Meaning somehow a little bit of the Y chromosome had gotten onto one of the X's of these XX males. And so it was becoming very clear that this must be the bit that matters. And around 1990... Other news this day, scientists say they've made... a major discovery. Scientists in Britain announced they'd found this one gene on the Y chromosome. The genetic trigger on the Y chromosome that determines whether a baby will be a boy or a girl. What they found is that of the 200 odd genes on the Y chromosome, there was this one single gene that acted as the switch. The master switch. The grand master switch. Which determines the child's sex.

So it's not X and Y as a whole. whole, it's one tiny piece. So back in the first episode, there were those primordial germ cells and they had to go on that super long journey to get to the GONAD Cathedral. And on the journey, when they got to the cathedral, they were full of potential, right? They could be anything. It could be male. They could be female. They could be whatever your version of anything is. And then when they get there, there's a moment where, like we said, fate stepped in and just, like, swept all their possibility away and said, you are one thing. And this is the thing you will be. This gene is fate.

This gene the scientists discovered, if it shows up, then you shoot off down the path that is sperm, testis, male. And if it doesn't show up, you shoot down the path of, of egg, ovary, female. And the scientists gave this gene a name S-R-Y, which is like, sorry. And it's like, you're a man, sorry. So it sounds like we've gone from like crazy ideas about what makes a boy or a girl to chromosomes

to now like this little gene. Yeah. But the sorry gene that you just mentioned is different than the gene that I just heard. about from, I'm forgetting his name. Zarcover. Zarcover. Zarkover, yeah.

Zarkover. Zarkover, yes. It is, I think. Is that the same gene or is it? DMRT1 is a different gene than SRI. But this, this is what's so crazy about DMRT1. Okay, primordial germ cells, they're in the embryo. They're waiting to become something.

And then Sari shows up. But it just comes on for about a day and then it goes away. But once it turns on, it then starts this like cascade of gene after gene after gene that all sort of say, you're male, you're male, you're male. And what all of these genes do is they create chemicals that send out signals that start forming and shaping the testis. And as soon as the testis begins to develop... On turns the fourth gene.

DMRT1. Zarkover's gene. And it clearly is important for finishing the job of making a testis. But the thing is most of these other genes that make the testis turn off, but DMRT1... It doesn't go away at that point. It stays active. Forever. In the womb, when the testis is just growing, and then when you're born and through, you know, childhood, your teenage years, adulthood, like until you die, DMRT1 is on.

And if you take it away, like Zarkover did, the cell will actually change sex. Which leads you to believe that DMRT1 is actually preventing a cell from switching sexes. That's right. So I called Blanche Capel, who's the geneticist from our first episode. And she explained that what all this means is that that other path, the path that you did not take in the GONAD Cathedral, it never went away. It's actually still there. You carry it with you always.

it's just that that gene has been shushing it. Yeah. Wait, I'm repressing the other pathway my whole life. I think we think so. Yeah. Really? Yeah. There's like a parallel universe male mollie?

Yes, I think there is. There's a parallel universe male molly. Wow. That's just cool. Wait, when you say this gene has been shushing the other molly, what does that even mean? Huh. Okay, so you can think of it like this. The code for that other molly.

who I'll call Daniel, that code is still in my cells. And Zarkover says that what this gene does is it's sort of, one of the things this gene does is sort of patrols and it makes sure that Daniel genes don't turn on. Basically what this gene's been doing, it turns out, is playing whack-a-mole. Basically just going around and being like, Daniel, no, off, Daniel, no, off. And it does this maybe every day. It's like an election that's always being kind of challenged. S-R-Y cast the deciding vote and mail happened, but there's a really. recount every now and then. And if DMRT1's not there to say, nope, still male, then you can go

the other way. So now I understand why you're so obsessed with Daniel because it's not just an idea. He's like trying to get out. And it does go both ways. Like, you know, there's SRY and there's DMRT1, but they have found these key genes in ovaries that you can turn on and off and have similar results. Why would our bodies be set up this way? Like you think once the decision gets made, that you just make that decision and be done with it? Why would there always be the possibility of unmaking the decision? That is a good question. And I will answer that after break. But first, I'm going to call my sisters. This is Kayla Cobble calling from Sunny Austin, Texas. Radio Lab presents

GONADS. GONADS is supported in part by Science Sandbox, a Simons Foundation initiative dedicated to engaging everyone with the process of science. Additional support for Radio Lab is provided by the Alfred P. Sloan Foundation. All right, back to GONADS. I'm Molly Webster.

Everyone say their name or hello. Okay, it's Chrissy. Dude. Peggy? Yeah. Hi, how are you? I'm great And these are my sisters

Judy, Chrissy, and Peggy Okay, so I'll tell you guys the thing It's not even that big of a deal But it's just sort of funny Oh no, okay Oh my God What the fuck?

You're pregnant I'm not pregnant I'm not No no I just want to tell you About some reporting That I've been doing And then a funny thing

That mom and dad told me That's all it is Okay Mom had an affair No Oh God That would be One of us doesn't belong

It's Chrissy Yeah This is ridiculous. The third episode is basically about how we all carry in us like the opposite self that we never became. So I called mom because I was like, what would male Molly have been like? Did you guys have like a name for male Molly? And they were like, oh, we would have called you Daniel. No, that was what they were supposed to call me.

They were so desperate to use Daniel. It turns out that we were all supposed to be called Daniel. That's the big reveal. It's not a reveal. Did I have an inner Daniel Webster? Yes. Jesus, Molly. Oh, man.

Are you surprised that your name would have been Daniel Webster, that you would have been a Daniel? No. No. No. I think we all knew that, right? Peggy, did you know that? I didn't know that. I don't feel like my inner Daniel Webster would have that much of a different life

I have. But I think you guys, honestly, not to railroad this conversation, but I think you guys lucked out because I was the one that was raised with the hoax that there was like some Daniel lingering in me. Isn't Daniel Webster like a famous dude in history? Yes.

I took a picture of a statue of him once and sent it to Dad because I was supposed to be Daniel. Who is Daniel Webster? He's a boring white dude. Well, of course he is. We knew that part. He served as senator from Massachusetts and was the Undersecretary of State under three presidents. Well, someone Googled fast.

I think he's just a regular, like, old white lawyer dude. Yeah, they're all racist or sexist or agist or just a douchebag. All right, well, great. That was funny. Peggy got her giggles in. It's all been worth it. All right, that's all I got. We love you, Molly.

I love you guys. Goodbye. Love you. Bye. Bye. Bye, Molly. You're amazing. Okay, bye.

Sorry about your bed bugs. Bye. Okay, so to catch everybody up, we have learned that we are all carrying around with us another path. We all have our own inner Daniel Webster's, and we're constantly shushing it. Or them, whatever. So my question for Zarakover was like, why would I carry this path with me if I'm always turn, like if I'm just turning it off? Do you have any answer to that?

I wish I had the answer. So we don't really have an answer. It could be as boring as, well, it doesn't really matter because normally no molecular geneticist comes in and hacks out DMRT1 or turns on Fox L2 or whatever. So why solve a problem that you haven't created? That's quite possible but boring. The more interesting answer is that this is an evolutionary holdover from a common ancestor with fish. Okay, so this ancestor would be our great-grandparents, 16 million times removed, which means 400 million years ago, a fish, swam out of the depths of the ocean, crawled onto land, and took like squelching steps forward and forward and forward and board and

forward through millions of years of luck and chance and fate until finally getting to you and me. Hello. Hello. Can you hear me? Yes, can you hear me? Yes, I sure can. Bob. My name is Bob Warner.

I'm a research professor. Studies evolution and marine biology. At UC Santa Barbara. What's your attraction to the ocean? Well, the whole idea that there is a different world under there. Well, I'm just going to add and bro the shit out of this. So down in the waters around the Florida Keys, there swims a remarkable fish. The bluehead rass.

It is a very common coral reef fish. This is Marshall Phillips. Graduate student at North Carolina State University. She, like Bob, studies blueheads. Yes. Anyways, down in the Keys are some... Primo spots. Nice patches of reef.

that might have a group of, say, a dozen. Blueheads. And in that group, there will be a single, large, brightly colored male. Just one of them. Yeah. About the size of your hand. With a blue head. And a shiny blue-green body.

It has white and black stripes right behind its head. That go black-white black. That we very technically call the Oreo. And if he's got a big Oreo. Well, that's a sexy male. And then the rest of the group. is essentially a harem of ladyfish. And the ladies in the group are little and yellow.

Very pretty. They kind of swim a little slower, watching out for things. Where the male is... Flashy, darting all around. Much more aggressive. And so this one male and this harem of females will basically spend their entire lives on this one patch of reef. Where they mate every day.

Each female with that one male. All it entails is the male and the female will dart up in the watercolon. them together. And then at the same time, he'll release his sperm and she'll release her eggs. And then they dart right back down. And then a different female, same male, go up, egg sperm. And dart back down. And then again, different females, same male, they go up. Down. And this is what they do every day. Over and over. Kind of sounds like a cult of the 1960s. But say something happens to this male. Well, say a predator comes along and he chops that male, So the alpha male is eaten up.

Dead. Yep. Gone. Now the question is, what happens to the ladies? You'd think it would be chaos because their whole system's been thrown out of whack. But within minutes to hours, life finds a way. Somehow, the ladies pick who will be the next male. The ladies have it pretty well worked out who's the largest. Do they all start, like, eyeballing each other?

They don't line up or anything. Am I bigger than you? But somehow they figure it out. And so once they establish who the largest female is, she starts to change her behavior. She gets a little more friendly. Towards the other females. She'll swim up to them.

Do this little wiggly dance. Sort of waving her pectoral fin at the ladies, which isn't really something they do as a female ever. And then as time goes on, her body starts to change. will get a little bit bigger. How do you just suddenly get bigger? Testosterone.

Her brain starts sending signals to produce tons of testosterone. Testosterone is taking over. And as she starts to grow, a little bit of blue starts to appear right at her nose. Her scales start to change color. Then sort of spread backwards, right at her chin and spread outwards.

Until her head is entirely blue, and then these dark stripes start to form. Those will eventually become that, black, white, black Oreo. And the other thing that starts to happen is her ovaries start to disintegrate. These are the most valuable cells in the body, and now suddenly they're being destroyed.

And then they start to rebuild themselves into testes that start producing... Sperm really rapidly. Wow. It's nuts. It's absolutely incredible. And then... Sex cult is back. There's a new dominant male at the top of the heap.

But at first, he's not very good at being a male. Like, he doesn't quite know when to dart up and when to spawn. It's just like a teenager who doesn't know how to talk to girls. But eventually, he gets the hang of it. And can produce baby blueheads. And the cycle of life continues. That's a good adenbroe. Thank you.

That is crazy that they just disintegrate. their insights and then rebuild. But the funny thing is, if you ask Bob about this stuff, about how these little ladyfish completely transform, he's like, eh. Yeah, I hate to admit that, but yeah. It's not that shocking. The shocking thing is how many fishes change sex.

It turns out it's a lot of fishes. Nearly all the rasses. Your blue heads, your fairies, your flashers. Parrot fishes. They actually look like parrots. They change sex. Most of the big groupers. The tiny gobies.

Damsel fishes. Everyone asks about clownfish. Finding Nemo. Yes, they change sex. But they do it a little differently. They go from male to female. Up with the clownfish matriarchy. Bob says we're dealing with like...

Hundreds. A whole lot of sex-changing fish. Easily. Wow. Hundreds. Yep. But... Here's a really crazy thing. It's not just fishes.

Some shrimps, worms. Alligators. If you include all of the... animals in which their sex goes a different way than you would think? Lies. Lobsters. It's f***. Bannas.

Lizards. Birds. Muscle, snails. Chickens. Oh, eels. Frogs. It's just amazing. And wait until we get to turtles.

It's a whole zoo in this conversation. I know. So why would fish, like, why would any animal change sex? Well, I think sex change increases your fitness. You have more young, either eggs you produce or eggs that you've fertilized. than you would as a single sex. In other words, it just ensures that you can pass on your genetic material. Like if you're the fishes on the reef and the male disappears, you're stuck and your DNA goes nowhere.

But if you can become a male, you can make sure that your DNA goes somewhere and then like all the other fishes in your little kingdom go somewhere. Okay, so now let me ask you the next obvious question. You've told me that we come from the fish. Yes. That they've got this flexy, sexy thing. And that we have it to some degree. Daniel lurks within you and is being actively suppressed every single day. So can we be like the fish?

Yeah, it does make you think of that. Zarkover says that ever since he did those mouse experiments, he gets this question a lot. Yeah, yeah. There's some interest from a transgender community and whether this could be something that would be helpful. But we can't do it. We technically can't. Zarkover says it's unethical and at this point probably even technically impossible to take that gene away. And even if we could, removing a gene just won't physically reorganize us in the way the fish do.

He says at most... You might be able to produce your own natural sex hormones of the type that's more aligned with your gender identity. Oh, pretty crazy you could even get the body to do that. But the reason we can't actually do the full-on switch, is because humans, male and female humans, have developed internal reproductive plumbing that is so different from each other. It would be impossible at the drop of a hat to switch. Well, so then this makes me confused. Well.

Is this, to use Blanche's word from a few episodes ago, is this bipotentiality that still is there latent, being suppressed? Is that a legacy thing that is just feeling? fading away or is there, is it there for a reason? It's there for a reason in the fish. Is it there for a reason in us? Does it serve a purpose? And therefore we'll be with us. Always. Or maybe even get stronger. Yeah. No, I asked Blanche that. I don't know. I don't know. I don't have a good answer for that. But it... Do you think anyone does? Or is this like a... No, I don't think anyone does. I think we're all trying to figure out why it would be the case. And most people ask the same question you ask,

why would this be true? And I don't know why it would be true. Even if we don't know why, just knowing that that other path is there just below the surface, you know, almost like wanting to express itself, does make you think a different way about how rigidly we define ourselves. I think we like to bend people as male or female,

and we've always put people in two piles. But I think there's a tremendous amount of middle ground. Even when you're just talking about, you know, things like the level of testosterone you're making or the level of estrogen you're making or the shape of your genitalia or many other features that we've been as male or female, I think there is a lot of variation between the two piles.

And maybe we just haven't appreciated the variation that exists naturally in our population. This episode is reported by me, Molly Webster, and produced by Matt Kilty, with additional production help by Rachel Cusick. Pat Walters was our editor. Scoring, mixing, and original music by Alex Overington and Matt Kilty, the GONADS theme and The Ballad of Daniel Webster were written, performed, and produced by Majel Connery and Alex Overington. Special thanks for this episode.

Go to Erica Todd, Andrew Sinclair, Robin Lovell badge, and Sarah Richardson. Thank you to composer Eric Friedlander for allowing us to use his work, Freel is A Breeze Part 2, and musician Sam Precock, whose work, A Geometric from his album, The Republic, is out on thrill jockey. I think you should sign it for the Radio Lab newsletter. You might think, yeah, newsletter, what's the big deal? Everyone's got one. but in our newsletter, you're going to get a bunch of staff picks telling you about super cool things we discovered while reporting this series.

Sign up at RadioLab.org slash newsletter or text GONADS to 701-01. Radio Lab presents GONADC is Rachel Cusick, Pat Walters, Jad Abumrod, and me, Molly Webster. See you next time. Hi, it's Annette Udall calling from Newcastle, California. Radio Lab was created by Jad Abramrod and is produced by Soren Wheeler. Dylan Keefe is our director of sound design. Maria Matasar Padilla is our managing director. Our staff includes Simon Adler, Maggie Bartala Mayo, Becca Bressler, Rachel Cusick, David Gebel, Bethel Hapty,

Tracy Hunt, Matt Kilty, Robert Krollwich, Annie McEwan, Matif Nassar, Melissa O'Donnell, Arian Wack, Pat Walters, and Molly Webster. With help from Shima O'le, Carter Hodge, and Lisa Yeager. Our fact checker is Michelle Harris. How many do, guys.