Let's Talk About (Biological) Sex, Baby

Summary

Short Wave Podcast Summary: "Let's Talk About (Biological) Sex, Baby"

NPR's "Short Wave" delves into the intricate science of biological sex, challenging the simplistic binary view often portrayed in societal and legislative contexts. Hosted by Regina Barber and Hannah Chin, this episode explores the multifaceted nature of sex determination in humans, the prevalence and implications of intersex conditions, and the societal influences shaping our understanding of biological sex.

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1. Introduction

Regina Barber and Hannah Chin introduce the episode's focus on biological sex, distinguishing it from the broader and often conflated concept of gender. They highlight recent legislative efforts aimed at defining biological sex strictly, particularly in the context of college athletics, sparking debates and scientific discussions.

Hannah Chin [01:00]: "We're talking about sex here, not gender. That's a whole other can of worms."

2. Challenging the Binary: Chromosomal Determination

The hosts begin by examining the traditional chromosomal definitions of sex—XX for females and XY for males. However, they quickly acknowledge the complexities beyond this binary framework.

Genetic Insights:

Hannah Claire, a genetic counseling researcher, explains the prevalence and methodology of cell-free DNA testing in determining fetal sex.

Hannah Claire [05:37]: "As a pregnancy is growing, the placenta sheds DNA into the bloodstream of the pregnant person. And so what labs will do is take that blood, sort out that fetal fraction, and analyze that to look at the chromosomes."

Scientific Perspective:

Ann Fausto Sterling, a sexologist and emeritus professor at Brown University, debunks the notion of a strict binary in nature.

Ann Fausto Sterling [01:24]: "The answer to the question, are there always two sexes? Is no."

She further elaborates on the diversity of sexual systems in the animal kingdom, citing examples like white-throated sparrows and clam shrimp that possess more than two sexes or a single sex capable of producing both eggs and sperm.

3. Hormonal Influences: The Chemical Determination

Biological sex isn't solely dictated by chromosomes; hormones play a pivotal role in development. The episode explores the fluctuating nature of hormones throughout a human's lifecycle.

Hormonal Fluctuations:

Faisal Ahmed, a pediatric endocrinologist, discusses the cyclical activity of the testes and ovaries, emphasizing that hormone levels rise and fall at different life stages.

Faisal Ahmed [07:35]: "These glands are not making things all the time. They kind of go up and down. So very similar to ovaries."

Developmental Stages:

Hannah Chin describes the critical periods when hormones influence physical development, including "mini puberty" in infants and the significant hormonal surge during adolescent puberty that triggers secondary sexual characteristics.

Hannah Chin [07:52]: "That's really the second metric for determining sex—the chemicals."

4. Physical Manifestations: The Physical Determination

Physical characteristics, both primary and secondary, are commonly used to determine biological sex. However, these traits often exhibit significant variation, challenging the binary classification.

Diverse Physical Traits:

The hosts discuss how traits like genitalia, facial hair, voice pitch, height, and fat distribution are indicators of biological sex but do not conform strictly to male or female categories.

Hannah Chin [09:14]: "People's appearances can really vary."

5. The Spectrum of Intersex Conditions

A substantial portion of the episode is dedicated to intersex conditions, highlighting their prevalence and the medical community's historical and ongoing challenges in addressing them.

Defining Intersex:

Eileen Wong, an adult urologist, defines intersex as conditions where an individual's physical or genetic characteristics do not fit typical male or female classifications.

Eileen Wong [10:10]: "Intersex is an umbrella term for biological conditions where a child is born with physical or genetic characteristics that don't fall into our society's neat definitions of what is male or female."

Prevalence and Awareness:

Hannah Chin notes that intersex conditions affect about 1-2% of the population, making them more common than often perceived.

Hannah Chin [10:34]: "Intersex conditions overall affect one to two people in every 100."

Historical Medical Practices:

The discussion touches on the problematic history of medically unnecessary surgeries performed on intersex children to "normalize" their bodies, leading to long-term psychological and physical harm.

Eileen Wong [11:09]: "Doctors would operate on an intersex child and operate on them, usually without those children's full understanding or consent."

Faisal Ahmed emphasizes the importance of recognizing intersex not as a disorder but as a natural variation, advocating for informed and consensual medical practices.

Faisal Ahmed [12:17]: "Intersex is not a diagnosis, it's like saying somebody has short stature."

6. Societal Influences and the Complexity of Scientific Understanding

The episode underscores how societal norms and policies influence the scientific interpretation of biological sex, often oversimplifying complex biological realities to fit binary models.

Influence of Society:

Faisal Ahmed discusses how societal expectations can pressure the medical and scientific communities to conform to binary definitions, thereby marginalizing natural biological variations.

Faisal Ahmed [13:55]: "If society says that the only options we have is boy or girl, and anything other than boy, girl, is not normal, then doctors or scientists will go along with that."

Scientific Consensus:

Ann Fausto Sterling reiterates the absence of a non-overlapping binary model in nature, advocating for a more nuanced understanding of biological sex.

Ann Fausto Sterling [13:25]: "The fact is that that model doesn't exist in nature at all."

7. Conclusion: Embracing Complexity and Moving Forward

Regina Barber and Hannah Chin conclude by emphasizing the necessity of recognizing the complexity of biological sex in both scientific discourse and societal frameworks. They highlight the ongoing challenges posed by politicization and advocate for greater awareness and acceptance of biological diversity.

Hannah Chin [14:24]: "Biological sex is definitely not as simple as two separate categories. And we lose a lot of nuance and knowledge when we pretend that it is."

The episode calls for a departure from rigid binary classifications, urging listeners to appreciate the intricate biological variations that define human sex.

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Key Takeaways:

• Biological Complexity: Biological sex is determined by a combination of chromosomal, chemical, and physical factors, none of which are strictly binary.

• Intersex Awareness: Intersex conditions are relatively common and highlight the natural diversity of human biology, necessitating informed and respectful medical practices.

• Societal Impact: Societal norms and legislative actions often oversimplify biological sex, ignoring the underlying scientific complexities.

• Medical Community's Role: There is a pressing need for the medical community to bridge the information gap regarding intersex conditions and to move away from outdated, harmful practices.

NPR's "Short Wave" effectively dismantles the simplistic binary view of biological sex, presenting a comprehensive and scientifically grounded exploration that encourages deeper understanding and acceptance of human biological diversity.

Transcript

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[Hannah Chin]

Amazon One Medical, you're listening to Short Wave from npr.

[Regina Barber]

Hey, short wavers. Regina Barber here with producer Hannah Chin. Hey, Hannah.

[Hannah Chin]

Hey, Gina.

[Regina Barber]

So today you're bringing us a story about sex.

[Hannah Chin]

Yeah. Not like sex, drugs and rock and roll.

[Sponsor Message]

Oh.

[Regina Barber]

Oh, okay.

[Hannah Chin]

Okay. We're here with a deep dive on biological sex.

[Regina Barber]

Oh.

[Hannah Chin]

Which has been mentioned in the news a lot recently.

[Regina Barber]

In the House, lawmakers are set to.

[Hannah Chin]

Move forward with a bill defining biological sex.

[Sponsor Message]

Glims said the bill was about creating.

A definition for sex separate from gender.

[Hannah Chin]

T prohibits college athletes from competing on a team opposite to their biological sex. Their biological sex. Biological sex.

[Sponsor Message]

Biological sex.

[Hannah Chin]

And just to be clear here, Gina, we're talking about sex here, not gender. That's a whole nother can of worms. But I think a lot of times these conversations are missing something important because there's this sense that gender is socially defined and changing as opposed to sex, which is scientifically defined and has always been binary and clear.

[Regina Barber]

But it's not.

[Hannah Chin]

No, it's not. When you get down to the biological reality, sex is way more complicated than that.

[Ann Fausto Sterling]

The answer to the question, are there always two sexes? Is no.

[Hannah Chin]

This is Ann Fausto Sterling. She's a sexologist trained in developmental biology and emeritus professor of gender studies and biology at Brown University. And she says the animal kingdom, for example, has all kinds of sexes.

[Ann Fausto Sterling]

Different organisms have different sexual systems. And sometimes there's two, sometimes there's more than two.

[Hannah Chin]

If you're curious, Gina. White throated sparrows and clam shrimp are examples of animals with more than two sexes. And some kinds of snails and worms have just one sex. They can produce both eggs and sperm.

[Ann Fausto Sterling]

Sometimes the same individual animal changes sexes during the course of the life cycle. And this has been perfectly well understood by biologists for a long time.

[Regina Barber]

I think I remember, like, clownfish can change sexes over their lifetime.

[Hannah Chin]

Yeah, Ann told me that's really common with fish.

[Ann Fausto Sterling]

They'll live in a big school of fish with a dominant male and a group of females. And if the dominant male dies, one of the females literally transforms into a male. So technically, that's still two sexes, but the sexes aren't fixed for life.

[Hannah Chin]

Researchers have found more than 450 fish species that can and do change sex. So, yes, clownfish but also gobies and wrasse. It's a pretty long list.

[Regina Barber]

And there's also animals like the New Mexico whiptail lizard. Like, we've covered that on short wave. And that's a species that has, like, no males and the females just, like, lay egg that are, like, viable and they don't need fertilization at all.

[Hannah Chin]

Totally. But this doesn't necessarily translate to humans. Right? Like, lizards can do a lot of things that we can't, and vice versa. We're not fungi. We're not fish. We're different.

[Regina Barber]

So today on the show the Science of Biological Sex in Humans, what is it?

[Hannah Chin]

What's it determined by? And when policymakers refer to sex as this unchanging biological constant, is that reality?

[Regina Barber]

You're listening to Short Wave, the science podcast from npr.

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[Regina Barber]

Okay, Han, so we were just talking about biological sex and how there's, like, a lot of variation in other animals, but what about humans? Like, what's the determining factor for, like, sex in us?

[Hannah Chin]

So in humans, sex is determined based on a variety of factors. But for the purposes of this episode, we're gonna focus on three of the main chromosomal, chemical, and physical.

[Regina Barber]

Wait, I think we need to slow down and, like, break down each of them. Right. Like. So the first one you said is chromosomal. Right. And I remember learning about this in, like, high school bio. All the genetic information in our bodies are packaged in 46 chromosomes, and they're coupled up to make 23 pairs. The first 22 pairs tend to look similar, like in all humans, but the last one is usually either an XX or an XY pair, and XX is usually assigned to female XY is assigned to male.

[Hannah Chin]

Right. That's true for most humans, not all. I'll get to that later. But most. And Hannah Claire says that nowadays, when doctors predict fetal sex, usually they're looking at the chromosomes.

[Hannah Claire]

So when folks say that they know the sex sex of their pregnancy, sometimes they're referring to ultrasound, but more often, and especially after 2010, they're referring to this test called cell free DNA testing.

[Hannah Chin]

Hannah's a genetic counseling researcher with experience in OB GYN clinics. We're not using her full name here or noting her employer because she's concerned that speaking publicly could hurt her ability to fund her research. But she says this test is super common. Clinicians don't have to wait for the ultrasound to look at the fetus. They just do a little blood test.

[Hannah Claire]

As a pregnancy is growing, the placenta sheds DNA into the bloodstream of the pregnant person. And so what labs will do is take that blood, sort out that fetal fraction, and analyze that to look at the chromosomes.

[Regina Barber]

Well, that's really cool.

[Hannah Chin]

I know, right? So this test tells us the chromosomes that a baby has. But the Y chromosome isn't like an on off switch for sex. There are sex influencing genes present in the other 22 pairs of chromosomes too. And there's a lot of variation that's still possible within those genes. So for a number of reasons, after birth, the baby can develop in a way that's different from what the tests predicted. And that's where this second metric for determining sex comes in.

[Regina Barber]

Right, and you mentioned a second metric being chemical. Right. Like, what do chemicals tell us about sexual.

[Hannah Chin]

Yeah. So a big part of sex and how it develops has to do with hormones. And those chemical hormones, they fluctuate through your whole life. Like, as a little kid, you had a different hormone profile than when you went through puberty or than when you start going through menopause.

[Sponsor Message]

Wow.

[Regina Barber]

Yep. Yep. So when does this, like, first chemical change actually happen?

[Hannah Chin]

Puberty, way earlier. All humans have hormones like testosterone, estrogen, progesterone, et cetera. They just have them in different quantities and different cycles.

[Regina Barber]

Wow.

[Hannah Chin]

And those hormones really fluctuate through life. So a fetus gets the first hit of these hormones in the womb. That triggers things like genital growth and certain types of brain development. Then there's another hormone surge in babies after birth, within the first six months. It's one that endocrinologists call mini puberty.

[Regina Barber]

Wow. I did not know any of this. It's like baby puberty. Okay.

[Hannah Chin]

Heck, yeah. And after that, in early childhood, the hormones kind of. Take a break. One pediatrician I talked to said, and I quote, that the testes are fast asleep.

[Faisal Ahmed]

So the testes are active and inactive at specific periods during childhood and adolescence. I mean, these. These glands are not making things all the time. They kind of go up and down. So very similar to ovaries.

[Hannah Chin]

This is Faisal Ahmed. He's a pediatric endocrinologist at the University of Glasgow. And he says that once adolescent puberty hits, there's usually an increase in hormones. Yeah, Those chemicals can also be delayed or boosted, for example, during gender affirmative horm hormone therapy. And they're usually what trigger the development of a bunch of other characteristics that we use to determine sex. And this brings us to the last physical.

[Regina Barber]

Okay, and I'm guessing that's like genitals.

[Hannah Chin]

Well, yes. This can refer to internal genitalia, like ovaries, or external genitalia, like penis and testes. Or we could also look at secondary sexual characteristics, things that usually don't develop until puberty, like breasts or facial hair. Or even things that are determined in part by hormones and are often used to differentiate sex, like your voice or your height or the distribution of fat and muscle on your body.

[Regina Barber]

Wow, I didn't even think about those last things. Like, you're totally right.

[Hannah Chin]

Yeah. And those physical traits are really the main observable characteristics, the ones that don't require lab work. So usually when people who are not doctors or scientists are talking about biological sex, this is what they really mean. But these physical characteristics don't really fall on a strict binary. I mean, we have tall women and short men. We have women with flatter chests and men without facial hair. People's appearances can really vary. But I digress.

[Regina Barber]

Okay, so physical traits, hormones, chromosomes, we have all these different ways to determine sex. And I'm guessing, like, that most of the time they align, but not all the time.

[Hannah Chin]

Exactly. All of these things have the potential to differ from one another or to be ambiguous or unclear. Like, someone's chromosomes might be xy, but they don't have a penis. Or they do have a penis, but they also have internal ovaries. And these differences generally fall under the umbrella of something called intersex conditions.

[Eileen Wong]

Intersex is an umbrella term for biological conditions where a child is born with, like, physical characteristics or genetic characteristics that don't fall into our society's neat definitions of what is male or female.

[Hannah Chin]

This is Eileen Wong. She's a physician, specifically an adult urologist. And she says that although intersex conditions are rare, they're not as rare as you think.

[Regina Barber]

Wait, like, how common are they?

[Hannah Chin]

Well, estimates can vary, but the most common number that I've seen thrown around is that intersex conditions overall affect one to two people in every 100. So that would make it about as common as having red hair and even more common than being born an identical twin.

[Regina Barber]

So chances are, if you're listening to this episode and you're not intersex, you've probably at least encountered someone who is.

[Hannah Chin]

Exactly. And Eileen is really passionate about intersex awareness because she says her training, she went to med school at Yale. She did her residency at Stanford. It's still left her really unprepared to treat intersex patients.

[Eileen Wong]

Once you operate on an intersex body, that patient will need to deal with those complications for the rest of their life. You can't pick. You can't change them back to what nature made them as.

[Hannah Chin]

Eileen told me that in the past, there was this big push to normalize intersex patients bodies. Doctors would look at an intersex child and operate on them, usually without those children's full understanding or consent, so their bodies would conform to more typical sex assignments.

[Eileen Wong]

Kids were, quote, normalized. They were stigmatized. They were lied to. Their parents were told that they shouldn't tell their children because it would ruin them psychologically. They were subjected to surgeries, including literal clitoral amputations that caused dysparea, pain, chronic scarring, basically medical PTSD for hundreds and hundreds of people.

[Regina Barber]

That's really horrible.

[Hannah Chin]

Yeah. And in 2018, the American Academy of Family Physicians issued a statement opposing medically unnecessary surgeries on intersex children. Basically saying this is harmful and we shouldn't do it anymore. But Eileen says there's still a huge information gap when it comes to intersex bodies and medical treatment. Faisal specializes in this kind of treatment, and here he is again.

[Faisal Ahmed]

So sometimes people feel that, you know, intersex is a diagnosis, but it's not really. It's really like saying somebody has short stature.

[Hannah Chin]

Right.

[Regina Barber]

Because, like, height is one of those physical characteristics you mentioned earlier.

[Hannah Chin]

Yeah. Faisal says that if you're short, there could be a bunch of reasons why, like, it could be that your parents are short, or it could be a nutrition problem or a genetic condition. And depending on how short you are and the society that you live in, it might or might not pose a problem. Like, when I was talking to Faisal, he drew this comparison of urinal heights in Japan versus in Europe.

[Faisal Ahmed]

But if you go to Netherlands, they're much higher up. So society is creating this thing which makes people not fit in.

[Hannah Chin]

And that's the thing that's key. Gina, Even though a lot of these metrics for determining sex are based in science, the way we interpret them is rooted in society. All of the scientists that I talked to agreed. Biological sex is definitely not as simple as two separate categories. And we lose a lot of nuance and knowledge when we pretend that it is. Here's Anne Fausto Sterling again. She's the biologist that we heard from at the very beginning of the episode.

[Ann Fausto Sterling]

You can think of a model in which there is. There's only two, and they completely don't overlap. You always know which is which, no matter what measure you're using, whether you're looking at the genitals or the chromosomes or the gonads or the hormones. And the fact is that that model doesn't exist in nature at all.

[Hannah Chin]

Human biology and all its possible variations are overwhelmingly complex. One might even say too complex to fit into a 15 minute episode.

[Faisal Ahmed]

Now, if society says that the only options we have is boy or girl, and anything other than boy, girl, is, is not normal, then doctors or scientists will go along with that and they will say, okay, let's, let's try to make sure that everybody's male and female, okay? But I think the more you understand this area, you will realize there is more to humans than boy and girl or males and females.

[Hannah Chin]

So while biological sex is scientific, the way that medical experts and scientists determine it is more complicated than I thought. Although saying so has become increasingly politicized. We heard that at the start of the episode, right? And how much media coverage this topic has gotten recently, and I saw the effects of it in my reporting. I reached out to 11 experts for this story, Gina, and less than half of them agreed to talk to me. Some people who declined, they cited fear for their jobs or their institutions. It feels like a reminder that science doesn't happen in a vacuum.

[Regina Barber]

Thank you, Han, for bringing us this story.

[Hannah Chin]

Anytime, Gina.

[Regina Barber]

If you liked this episode, make sure you never miss a new one by following us on whatever podcasting platform you're listening from. And if you have a science question you'd like us to investigate, send us an [e-mail] news tape at the top.

[Hannah Chin]

Of the episode was from the following KSNT, KPAX, KCCI, WDAL and CBS News.

[Regina Barber]

This episode was produced by Burley McCoy and edited by our showrunner, Rebecca Ramirez. Tyler Jones checked the facts. Kwesi Lee was the Audio engineer Beth.

[Hannah Chin]

Donovan is our Senior Director and Colin Campbell is our Senior Vice President of Podcasting Strategy.

[Regina Barber]

Hi, I'm Regina Barber.

[Hannah Chin]

And I'm Hannah Chin.

[Regina Barber]

Thank you for listening to Short Wave from npr.

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