X & Y
TOBIN: Yes Kathy.
KATHY: You know what’s something we have in common?
TOBIN: That when we have insomnia, we buy things online.
KATHY: Oh my god, that’s so true. I just bought something. Ok but what I’m talking about is we both at some point in our lives worked at Radiolab here at WNYC.
TOBIN: Yes we did. You did a summer at Radiolab, I worked on the first season of Radiolab presents More Perfect.
KATHY: And suffice it to say, we are both huge fans of everyone there.
TOBIN: Yes We are! And that is why this week, while we’re taking a much needed Thanksgiving break, we are playing an episode of a Radiolab series called Gonads.
KATHY: Gonads is a 6-episode series about reproduction, hosted by Molly Webster. Amazing reporter. And we chose this episode specifically because it goes into the super fascinating nature of chromosomes, which sounds complicated, but trust me, it’s super interesting.
TOBIN: And If you like this episode, you’ll probably want to listen to the rest of the series, which you can find at radiolab.org/gonads.
KATHY: We’ll be back next week. Enjoy the episode.
TOBIN: Kathy, Tobin, out.
RADIOLAB INTRO: You’re listening to Radiolab, from WNYC.
MOLLY: Gonads. Episode three. I’m Molly Webster.
MOLLY: Hello, are you still there?
MARY: I’m still here
MOLLY: And this is my mother, Mary Webster.
MOLLY: But, yeah no. the bed bugs are such a freaking pain
MARY: Oh it sounds awful
MOLLY: You have to vacuum all of the baseboards, you have to vacuum the floors, you have to vacuum the door jambs because they crawl up the walls when they’re trying to get away
MARY: Oh Molly that sounds awful
MOLLY: And it just--
MOLLY: So, recently I called my mom for...I guest to catch up, but also
[MUSIC] “I’m calling from the other side”
MOLLY: I had a work question
[MUSIC] “have you ever stopped and wonder why”
MOLLY: That’s been bugging me...
[MUSIC] “a part of you was left behind”
MOLLY: ...Was on my mind.
MOLLY: So I asked her, mom.
MOLLY: I’ve been working on this story and it made me wonder what you would have named me if I was a boy.
MARY: You would have been named Daniel
MARY: Dad always like the name, and if we ever had a boy, Dad said he was gonna name him Daniel and I said, sure. If that’s what you want, go for it. You know, because he didn’t want a junior, he wanted a Daniel. He wanted a little Danny, hee hee
MOLLY: Instead, he got a Judy, Chrissy, Peggy, and Molly
JAD: Your poor father
MOLLY: My lucky father!
MARY: If you had come out boys, you would’ve been Daniel, yes
MOLLY: Wait, all of us?
MARY: No, we wanted Daniel for a boy, not for everybody.
MOLLY: You were just ready
MARY: Well we didn’t know when a boy came out if it was gonna be a Daniel, you know what I mean. That was it.
MUSIC - Daniel, Daniel, Daniel...
MOLLY: So this is just going to sound ridiculous, but I called my mom because all these stories that we’ve doing in this series, they do make you think about fate. Like even if you think about the first one where there are the primordial germ cells and they’re holding on to all sorts of possibilities and futures...and then
MUSIC - Chromosomes
MOLLY: Chromosomes step in. And peeuugh 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--
MOLLY: Maybe life isn’t so fateful
DAVID Z: [COUGHS]
MOLLY: Case in point - David Zarkower.
DAVID Z: Hello.
DAVID Z: I'm just going to say I don't like correcting people but I'll just correct you my name is pronounced Zar-Cove-Er.
DAVID Z: Zar-Cover-Er.
MOLLY: Because it is a W right? I'm not misspelling in my head?
DAVID Z: Is it a W, just for the sake of my parents, I pronounce it with like a V. It's essentially Polish.
MOLLY: That's good. And you work at the University of Minnesota?
DAVID Z: Yup that's right.
MOLLY: What do you do there.
DAVID Z: Genetics, cell biology and development.
MOLLY: That's that seems scary.
DAVID Z: It's broad
MOLLY: Anyways, the reason I called Zarkower was because I came across this series of experiments that he did that just like straight up… kicked me in the gonads.
DAVID Z: Okay so
MOLLY: To begin
DAVID Z: This was back in the early 1990s.
MOLLY: Zarkower was working in a lab, doing genetics stuff
DAVID Z: In worms and flies and mice and things. And
MOLLY: One day
DAVID Z: Presto, we got lucky
MOLLY: Bum bah dah dah - he and his team discovered a brand new gene
DAVID Z: Yep, that’s right
MOLLY: They saw it in mice and gave it a name
DAVID Z: I am unfortunately responsible for this. It’s DMRT1
DAVID Z: DMRT 1 - yep.
JAD: DMRT 1.
MOLLY: I keep trying to say D-R-M-T-blah blah blah
DAVID Z: Yeah. It's a nightmare. I'm very sorry for that.
MOLLY: And what was interesting, was that this gene was in mice.
DAVID Z: But also in humans.
MOLLY: And, in the male mouse, it was expressing itself in the, um, testis? I never know how to say it. Testis?
JAD: Testes. Testes
MOLLY: Testes. Testicles?
DAVID Z: Testis.
MOLLY: Is that a single?
DAVID Z: Yeah.
DAVID Z: So yeah we found this gene and humans had it in the testis. And the question we had was whether it was doing something or not
MOLLY: Like you’ve got genes in your eyes that’re making chemicals, that are making your eyes the color they are
DAVID Z: This gene, DMRT1.
MOLLY: What is it doing?
DAVID Z: We wanted to know if it's involved in maybe making sperm.
DAVID Z: Maybe it just hangs around, it doesn’t matter
MOLLY: Doesn’t do anything
DAVID Z: You know we don't know.
MOLLY: And so they’re like let’s mess around with it and see what happens. But you can’t do that experiment in humans
DAVID Z: No
MOLLY: So instead, they get some adult male mice
DAVID Z: Perfectly normal fertile males
MOLLY: That are making sperm
DAVID Z: And we use some fancy molecular genetic tricks.
MOLLY: And so basically
DAVID Z: It's kind of a mean trick but it's genetics.
MOLLY: They cut the gene out
DAVID Z: We did that, and then--
MOLLY: And then they take a slice of the testis, and they look at it under the microscope
DAVID Z: And it didn’t look like what we would have expected
MOLLY: 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
DAVID Z: long and skinny.
MOLLY: But suddenly
DAVID Z: They were different
MOLLY: With DMRT1 gone they had gotten smaller and rounder. And Zarkower was like
DAVID Z: This was not something that was supposed to happen.
MOLLY: What is going on here?
DAVID Z: What are these things?
MOLLY: Then he realized that the cells are making estrogen. And he was like--
DAVID Z: Oh. I think what is happening is that the cells in the testis
MOLLY: Turned into ovary cells
JAD: Wait, what
JAD: Wait this is a male mouse.
JAD: So you’re saying this male mouse now has ovary cells in its testicles?
DAVID Z: Yes, these are cells that are changing their sex
MOLLY: That’s insane. Can we just have like a, exclamatory moment. Like, were you like, whoa is that--that’s possible, that happened. What is--You know?
DAVID Z: What do you say? For us anyway, the greatest of all scientific exclamations is that's weird. So we had a that's weird moment.
MOLLY: 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
DAVID Z: Fancy molecular genetic tricks
MOLLY: Only this time they knocked out a female gene in the ovary. And when they went to look at it
DAVID Z: The ovary is trying to kind of reorganize itself into a testis.
JAD: You’re saying in both cases there’s one gene that’s flipping the sex from male to female or back
JAD: One gene?
MOLLY: One gene.
JAD: How many genes do we have in our body?
MOLLY: I don’t know… like tens of thousands?
JAD: Whoa, and just one is doing this!
MOLLY: Which is …
MOLLY: 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--
MOLLY: Is a girl and a boy so how could a gene step in and reverse that
JAD: Yeah because I thought chromosomes were lots of genes. They were these massive things. One gene is so tiny.
MOLLY: Genes are 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?
MOLLY: I think it’s helpful to see sort of like the history of how we understand sex in a slightly longer timeframe. So… let me bring in this guy
DAVID P: I’m David Page, biology professor at MIT
MOLLY: OK, where do we start?
DAVID P: Oh my gosh. Well we’re gonna go--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, um. Let’s go back to the 1890s
MOLLY: Yeah. That definitely is 1890s
DAVID P: So
MOLLY: So, genetics was in its infancy. Mendel, peas, all that was happening
DAVID P: And people had been pondering for millenia, where do boys and girls come from?
MOLLY: Now, when it came to how you looked, people thought, mom and dad clearly involved.
DAVID P: Because people had realized, you know, that children ended up growing up looking something like their mother and their father.
MOLLY: Like maybe you have a chin like your dad, a nose like your mom, and hair that’s a little bit of both
DAVID P: There was a kind of blending
MOLLY: Of mom and dad to make you, you
DAVID P: Right. But
MOLLY: When it came to why you were the sex you were
DAVID P: Mmmm
MOLLY: That was a mystery
DAVID P: Because
MOLLY: There was no blending
DAVID P: You ended up being like either your mother or your father
MOLLY: One or the other
DAVID P: Therefore, it must not have anything to do with heredity. It had to be imposed from the outside in some way.
MOLLY: So people came up with all kinds of ideas for what made you a boy or a girl
DAVID P: The phase of the moon at the moment of conception
MOLLY: Cold dark moon, definitely a girl
DAVID P: The state of the economy
MOLLY: Wouldn’t be surprised, down economy, girl
DAVID P: Yep
MOLLY: Everything that was bad was given to women. [laughs]
DAVID P: There was what the mother ate
MOLLY: Mom’s body heat, stress
DAVID P: All sorts of crazy things. And then
DAVID P: in 1923
MOLLY: We started looking elsewhere
CLIP: But how do we inherit our characteristics?
MOLLY: For an answer
DAVID P: Chromosomes
CLIP: Determine our physical appearance and our sex
MOLLY: In 1923 a scientist looking down the barrel of a microscope discovers two new chromosomes.
DAVID P: An X and a Y
CLIP: Called the sex chromosomes
MOLLY: But I just want to hit pause here
[MUSIC SLOW EFFECT]
MOLLY: I came to find out actually from David Page that X and Y chromosomes do not look like an X and Y
JAD: Wait, they don’t look like the letters?
DAVID P: Oh, no, no, no
MOLLY: No when they first discovered them
DAVID P: They were blobs
MOLLY: Under the microscope they just looked like these misshapen clumps
DAVID P: I’d say kidney bean-like
MOLLY: The X looked bigger, the Y looked smaller. But that’s it.
JAD: That’s so interesting. Like, I--because there’s something about the shape of the X and the shape of the Y which read as gendered letters.
MOLLY: That feels so--yeah
JAD: Because like the Y has a little stem on it which is sort of--
MOLLY: Penis-like. There’s like a duality of something in like the X which feels like, you know, ovaries and breasts or something. Like there is like--there is something about those letters, so I was
MOLLY: Totally shocked. When he was like,
DAVID P: There’s no real reason people gave them those letters, it was totally arbitrary.
MOLLY: Anyways. When they found these chromosomes
DAVID P: It was clear that if you had
DAVID P: Two X chromosomes, you would develop as a female
CLIP: A girl
DAVID P: Anatomic female. And if you had a Y chromosome
MOLLY: So you’re XY
DAVID P: You would develop as an anatomic male
CLIP: That’s right. A boy
DAVID P: That was the thinking
CLIP: So you see, Roger and Susan are boys--
MOLLY: But then that idea, it got more complicated
DAVID P: Yeah
MOLLY: Yeah, when did you intersect with this story?
DAVID P: Um, the summer of 1979
MOLLY: Page was at MIT
DAVID P: First year of medical school. And the DNA revolution
CLIP: So far tonight, we’ve been bringing you news of the world around us
DAVID P: Was just beginning
CLIP: Now we have news of the incredible world inside us
MOLLY: He was involved in what he describes as like the precursor
DAVID P: To
CLIP: The Human Genome Project
DAVID P: What would become the Human Genome Project. Working with a group of senior scientists who were envisioning maps of the Human Genome
CLIP: An encyclopedia of man. We’ll know the complete set of instructions, which make people
DAVID P: And we began to look back at some exceptional human individuals, who had not been understood previously
CLIP: That saliva test
DAVID P: Women
CLIP: Revealed that Maria had a set of X and Y chromosomes
DAVID P: Who had an X and a Y chromosome
CLIP: Like most men, women usually have a pair of X’s
MOLLY: And they’re also looking at men
DAVID P: Who had an altogether male anatomy
MOLLY: Penis, testes
DAVID P: But whose chromosomes appeared to be those typical of a female XX
MOLLY: 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
DAVID P: So we might actually be on the trail now of the secret
MOLLY: So scientists across the world started looking at these people’s chromosomes
DAVID P: And what we found was that a few XY females were actually missing a little bit of the Y chromosome.
MOLLY: With these XY women, a little bit of the Y wasn’t there
DAVID P: And the bit of the Y that the XY females were missing, was the same bit that was present in the XX males.
MOLLY: Meaning somehow a little bit of the Y chromosome had gotten onto one of the X’s of these XX males
DAVID P: And so it was becoming very clear that this must be the bit that matters
MOLLY: And around 1990
CLIP: Other news this day, scientists say they’ve made a major discovery
MOLLY: Scientists in Britain announced they’d found this one gene on the Y chromosome
CLIP: The genetic trigger on the Y chromosome that determines whether a baby will be a boy or a girl
MOLLY: What they found is that of the 200 some odd genes on the Y chromosome, there was this one single gene that acted as the switch.
CLIP: The master switch
DAVID P: The grand master switch
CLIP: Which determines the child’s sex
MOLLY: So it’s not X and Y as a whole, it’s one tiny piece.
MOLLY: So back in the first episode, there were those primordial germ cells and they had to go on this 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. They 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 whoooosh 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 these 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 egg, ovary, female. And the scientists gave this gene a name SRY.
MOLLY: Which is like sorry
MOLLY: You’re a man, sorry
JAD: [laughs] JAD: So it sounds like we’ve gone from crazy ideas about what makes a boy or a girl to chromosomes to now like this little gene
JAD: But the SRY gene that you just mentioned is different than the gene that I just heard about from--I’m forgetting his name
DAVID Z: Zarkower
DAVID Z: Zarkower, yeah
JAD: Zarkower, yes
MOLLY: It is I think--
JAD: Is that the same gene, or is it--
MOLLY: DMRT-1 is a different gene than SRY. But this, this is what’s so crazy about DMRT-1. Okay. Primordial germ cells, they’re in the embryo, they’re waiting to become something and then sorry shows up
DAVID Z: But it just comes on for about a day, and then it goes away
MOLLY: 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.
DAVID Z: And, as soon as the testis begins to develop
MOLLY: On turns the fourth gene
DAVID Z: DMRT-1
MOLLY: Zarkower’s gene
DAVID Z: And it clearly is important for finishing the job of making a testis
MOLLY: But the thing is, most of these other genes that make the testis turn off. But DMRT-1
DAVID Z: It doesn’t go away at that point. It stays active
MOLLY: 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, DMRT-1 is on. And if you take it away, like Zarkower did, the cell will actually change sex, which leads you to believe that DMRT-1 is actually preventing a cell from switching sexes.
BLANCHE: That’s right, so--
MOLLY: I called Blanche Capel, who is the geneticist from our first episode. And she explained that what all this means is that that other path, that 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.
MOLLY: Wait, I’m repressing the other pathway my whole life, like--
BLANCHE: I think--we think so, yeah
MOLLY: There’s like a parallel universe male Molly?
BLANCHE: [laughs] Yes, I think there is. There’s a parallel universe male Molly.
MOLLY: Wow. That’s just cool [laughs]
JAD: Wait, when you say this gene has been shushing the other Molly, what does that even mean?
MOLLY: Huh. OK 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 Zarkower says that what this gene does is it sort of--one of the things this gene does is it sort of patrols and it makes sure that Daniel genes don’t turn on.
DAVID Z: 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. [pooh pooh pooh] And it does this, maybe, every day. It’s like an election that’s always being kind of challenged. SRY cast the deciding vote and male happened, but there’s recount every now and then. And, uh, if DMRT-1’s not there to say nope, still male, then you can go the other way.
JAD: 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!
MOLLY: And it does go both ways. Like, you know, there’s SRY and there’s DMRT-1 but they have found these key genes in ovaries that you can turn on and off and have similar results.
JAD: Why would our--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 un-making the decision?
MOLLY: That is a good question. And I will answer that question after the break. But first, I’m gonna call my sisters. Ha!
[MUSIC] - You Daniel, you complete me, you Daniel...
TOBIN: And We’re back.
Kathy: Back to an episode of the Radiolab special series Gonads with reporter Molly Webster.
MOLLY: Everyone say say their name or hello
CHRISSY: Ok it’s Chrissy
JUDY: It’s Judy
MOLLY: Hi, how are you
PEGGY: I’m great
MOLLY: And these are my sisters, Judy, Chrissy and Peggy.
MOLLY: Ok so i’m going to tell you guys the thing. It’s not even that big a deal but it’s sort of just funny.
SISTERS: Oh my god, Oh no, Ok, What the fuck? You’re pregnant
MOLLY: 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
SISTER: ok. Mom had an affair?
MOLLY: Oh god. That would be--
SISTER: One of us doesn’t belong… It’s Chrissy….Yeah
MOLLY: This is ridiculous. Um the third episode is basically about how we all carry in us like the opposite self that we never became. So um So I called mom because I was like so what would male Molly have been like? Did you guys have like a name for male Molly? And they were like oh um we would have called you Daniel.
SISTER: No that was what they were supposed to call me! They were so desperate to use Daniel
MOLLY: And it turns out we were all supposed to be called Daniel
SISTER: That is the big reveal? There is an inner Daniel Webster?
SISTER: Jesus, Molly!
MOLLY: Oh man… are you surprised that your name would have been Daniel Webster? That you would have been a Daniel?
SISTERS: No….No...I think we all knew that right?
MOLLY: Peggy did you know that?
PEGGY: No I didn’t know that!
SISTER: I don’t feel like my inner Daniel Webster would have that much of a different life than I have so--
SISTER: 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 hopes that there was some Daniel lingering in me
SISTER: Isn’t Daniel Webster like a famous dude in history?
SISTER: Oh...I took a picture of a statue of him once and sent it to dad, because I was supposed to be Daniel.
SISTER: Who is Daniel Webster
SISTER: He’s a boring white dude
Molly: Well of course he is. We knew that part.
SISTER: He served as senator for Massachusetts and was the under-secretary of state under three presidents
SISTER: Well someone googled fast
SISTER: I think he was just like a regular old white lawyer dude
SISTER: yeah they were all racist or sexist or ageist or just a douchebag [LAUGHTER]
SISTER: Alright, well
SISTER: That was funny
MOLLY: Peggy got her giggles in, it’s all been worth it. Alright, that’s all I got.
SISTERS: Bye..We love you Molly
MOLLY: I love you guys, goodbye
SISTERS: Love you...Bye...Bye Molly you’re amazing.
MOLLY: OK bye
SISTER: I’m sorry about your bedbugs. Bye [LAUGHTER]
MOLLY: OK. So you catch everybody up, we have learned that we are all carrying around with us another path. We all have our own inner Daniel Websters, and we’re constantly shushing it--or them whatever. So my question for Zarkower was like why would I carry this path with me if I’m always turning, like if I’m just turning it off
DAVID Z: Ummmm
MOLLY: Do you have any answer to that?
DAVID Z: [LAUGHS] 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 DMRT-1 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 from a common ancestor with fish.
[BUBBLE MUSIC IN]
MOLLY: OK so this ancestor would be our great grandparent, 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 through millions of years of luck and chance and fate until finally getting to
[SPLASH SOUND IN]
MOLLY: You. And me. And
BOB: Can you hear me?
MOLLY: Yes. Can you hear me?
BOB: Yes I sure can.
BOB: My name is Bob Warner. I'm a research professor
MOLLY: Studies evolution and marine biology
BOB: At UC Santa Barbara.
MOLLY: What's your attraction to the ocean?
BOB: Uh well the whole idea that there is a different world under there
[SPLASH SOUND IN]
MOLLY: Well, I'm just going to Attenborough the [BLEEP] out of this.
MOLLY: So down in the waters around the Florida Keys there swims a remarkable fish
BOB: A bluehead wrasse.
MARSHALL: It is a very common coral reef fish
MOLLY: This is Marshall Phillips
MARSHALL: Graduate student at North Carolina State University.
MOLLY: She, like Bob, studies blueheads.
MOLLY: Anyways down in the Keys are some
MARSHALL: Primo spots.
MOLLY: Nice patches of reef
BOB: That might have a group of say a dozen -
MARSHALL: Blue heads
BOB: And in that group there will be a single large brightly colored male
MOLLY: Just one of them.
MOLLY: About the size of your hand
MARSHALL: With a blue head
MOLLY: And a shiny blue-green body
MARSHALL: And it has white and black stripes right behind its head.
MOLLY: That go black white black
MARSHALL: That we very technically call the Oreo.
MOLLY: And if he's got a big Oreo
MARSHALL: Well, that's a sexy male. [laughs]
MOLLY: And then the rest of the group is essentially a harem of lady fish
BOB: And the ladies in the group
MARSHALL: Are little and yellow
BOB: Very pretty.
MOLLY: They kind of swim a little bit slower, watching out for things
BOB: Where the male is
MARSHALL: Flashy, darting all around
BOB: Much more aggressive.
MOLLY: And so this one male and this harem of females will basically spend their entire lives on this one patch of reef
BOB: Where they mate every day.
MOLLY: Each female with that one male
MARSHALL: All it entails is the male and the female will dart up in the water column together
MOLLY: And then at the same time he’ll release his sperm, and she’ll release her eggs
MARSHALL: And then they dart right back down.
MOLLY: And then a different female, same male go up, eggs, sperm
MARSHALL: And dart back down
MOLLY: And then again, different female same male, they go up
MOLLY: And this is what they do every day.
MARSHALL: Over and over
MOLLY: Kind of sounds like a cult of the 1960s
MOLLY: But say something happens to this male
MARSHALL: Say a predator comes along. And he chomps that male.
MOLLY: So the alpha male
BOB: Is eaten up
MOLLY: Gone. Now the question is what happens to the ladies. You would think it would be chaos because their whole systems been thrown out of whack
MARSHALL: Within minutes to hours
MOLLY: Life finds a way
MOLLY: Somehow, the ladies pick who will be the next male
BOB: The ladies have it pretty well worked out who's the largest
MOLLY: Do they all start like eyeballing each other, like--
MARSHALL: They don’t line up or anything, like, am I bigger than you, no I-- But somehow they figure it out
MOLLY: And so once they establish who the largest female is she starts to change her behavior. She gets a little more friendly
BOB: Towards the other females
MOLLY: She’ll like swim up to them
MARSHALL: do this little wiggly dance.
MOLLY: Sort of waving her pectoral fin at the ladies
MARSHALL: Which isn’t really something they do as a female. Ever.
MOLLY: And then
MARSHALL: As time goes on
MOLLY: Her body starts to change
MARSHALL: She will get a little bit bigger
MOLLY: How do you just suddenly get bigger?
MOLLY: Her brain starts sending signals to produce tons of testosterone
MARSHALL: Testosterone is taking over.
MOLLY: And as she starts to grow
MARSHALL: A little bit of blue starts to appear right at her nose.
MOLLY: Her scales start to change color.
MARSHALL: Then sort of spread backwards right at her chin and spread outwards
MOLLY: Until her head is entirely blue, and then these dark stripes start to form
MARSHALL: Those will eventually become that black white black Oreo
MOLLY: And the other thing that starts to happen is her ovaries start to disintegrate.
BOB: These are the most valuable cells in the body and now suddenly they're being destroyed.
MOLLY: And then they start to rebuild themselves into testes that start producing
BOB: Sperm really rapidly.
MARSHALL: It’s nuts. It’s absolutely incredible.
MOLLY: And then
MOLLY: Sex cult is back.
BOB: There’s a new dominant male at the top of the heap
MARSHALL: But at first he’s not very good at being a male.
MOLLY: Like he doesn’t quite know when to dart up and when to spawn.
MARSHALL: It's just like a teenager who doesn't know how to talk to girls
MOLLY: But eventually, he gets the hang of it
MARSHALL: And can produce baby blueheads
MOLLY: [IN DAVID ATTENBOROUGH VOICE] And the cycle of life continues.
JAD: [laughs] That’s a good Attenborough
MOLLY: Thank you.
JAD: That is crazy that they just disintegrate their insides and then rebuild
MOLLY: But this is--the funny thing is if you ask Bob about this stuff
BOB: No, in fact--
MOLLY: About how these little lady fish completely transform he’s like, meh
BOB: Yeah I hate to admit that but, yeah.
MOLLY: It’s not that shocking
BOB: The shocking thing is how many
BOB: --fishes change sex.
MOLLY: it turns out it's a lot of fishes.
BOB: Nearly all the wrasses
MOLLY: Your blueheads, your ferries, your flashers
BOB: Uh, parrot fishes.
MOLLY: They actually look like parrots.
BOB: They change sex. Most of the big groupers
MOLLY: The tiny gobies
BOB: Damsel fishes. Everyone asks about clownfish
MOLLY: Finding Nemo.
BOB: Yes they change sex
MOLLY: But they do it a little differently.
BOB: They go from male to female
MOLLY: Up with the clownfish matriarchy.
MOLLY: Bob says we're dealing with like
MOLLY: A whole lot of sex changing fish
PAT WALTERS: Wow. Hundreds.
MOLLY: But here's the really crazy thing.
MOLLY: It’s not just fishes
BOB: Some shrimps. Worms
MOLLY: If you include all the animals in which their sex goes a different way than you would thinK
BLANCHE: Flies. Lobsters
MOLLY: It’s [BLEEP] bananas
BLANCHE: Lizards. Birds
MOLLY: Mussels snails slugs
MOLLY: Oh, eels
BLANCHE: Frogs. It's just amazing. And wait til we get to turtles.
MOLLY: It's a whole zoo in this conversation.
BLANCHE: [LAUGHS] I know.
MOLLY: So why would fish--why would why would any animal change sex?
DAVID P: Well I think sex change increases your fitness. You have more young, either eggs that you produce or eggs that your fertilized than you would as a--as a single sex
MOLLY: 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 there’s no-- your DNA goes nowhere. But if you 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.
JAD: OK so now let me ask you the next obvious question. You’ve told me that we come from the fish, that they’ve got this flexi-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?
MOLLY: Yeah it does make you think of that. Zarkower says that ever since he did those mouse experiments, he gets this question a lot.
DAVID Z: Yeah, you know, there’s some interest from the transgender community in whether this could be something that could be helpful. But, we can’t do it--we technically can’t alter--
MOLLY: Zarkower 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
DAVID Z: You might be able to produce your own natural sex hormones of the type that’s more aligned with your gender identity
MOLLY: 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
JAD: Well so then then this makes me confused, is this--to use Blanche’s word from a few episodes ago--is this bi-potentiality that still is there
JAD: latent, being supressed--is that a legacy thing, that’s just fading away or is it there for a reason? It’s there for a reason in the fish. Is it there for a reason in us?
MOLLY: Does it serve a purpose
JAD: and therefore will be with us --always
MOLLY: Always. Or maybe even get stronger. No I asked Blanche that.
BLANCHE: I don’t know, I don’t know. I don’t have a good answer for that. But it--
MOLLY: Do you think anyone does? Or is this like--
BLANCHE: 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
MOLLY: 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
BLANCHE: I think we like to bin 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 things like the level of testosterone you’re making or the level of estrogen you’re making or, um, the shape of your genitalia or, uh--many other features we bin 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
MOLLY: This episode was reported by me, Molly Webster, and produced by Matt Kielty. With additional production help by Rachael Cusick. Pat Walters was our editor. Scoring, mixing and original music by Alex Overington and Matt Kielty. 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 St Clair, Robin Lovell-Badge, and Sarah Richardson. Thank you to composer Erik Friedlander, for allowing us to use his work Frail As A Breeze Pt. 2, and musician Sam Prekop, whose work, A Geometric, from his album The Republic is out on Thrill Jockey. I think you should sign up for the Radiolab newsletter. You might think, eh, newsletter, what’s the big deal? Everyone’s got one. But in our newsletter you are going to get a bunch of staff picks telling you about super cool things we discovered while recording this series. Sign up at radiolab.org/newsletter or text “gonads” to 701-01. Radiolab Presents: Gonads is Rachel Cusick, Pat Walters, Jad Abumrad and me, Molly Webster. See you next time.
VOICEMAIL: Hi, it’s Annette Udal calling from Newcastle, California. Radiolab was created by Jad Abumrad 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 Bartolomeo, Becca Bressler, Rachael Cusick, David Gebel, Bethel Habte, Tracie Hunte, Matt Kielty, Robert Krulwich, Annie McEwen, Latif Nasser, Malissa O’Donnell, Arianne Wack, Pat Walters, and Molly Webster. With help from Shima Oliaee, Carter Hodge, and Liza Yeager. Our fact-checker is Michelle Harris. How’d I do guys?