Transcript: Biologist Carole Hooven on Conversations with Coleman Podcast

I went to Antioch College, which was great at the time. It was wonderful for me. And it has a co-op program. And as part of the co-op program, I did things like live on a kibbutz, travel around Egypt, work for the government in Washington, D.C., teach autistic kids, work with schizophrenic adults.

So I had a lot of travel experience and really interesting work experience that I could bring into the classroom. And these were small classes where we were encouraged to challenge everything. And that was a wonderful thing about Antioch, these small groups where there was just tons of debate and anything went. And it is not the case there anymore. They actually canceled me at the same time from giving a talk at the same time that Harvard was canceling, or whatever you want to call it, canceling me.

So Antioch was a really formative experience for me and I was turned on intellectually and I knew that I wanted to go to graduate school, but I also needed a lot of time to learn how to live on my own and earn money and be a competent adult. And I grew up with three older brothers. I was the only girl. I used to play Little League, which was very unusual in the 70s. I was kind of a rougher girl in some ways.

So I eventually, I read a lot of books during that time when I was trying to figure out what I wanted to do and just pursuing what I was interested in. And I write about this in my own book on testosterone, but it was “The Selfish Gene” by Richard Dawkins. I get chills when I talk about it because it was such a profound change in the way I viewed my existence and it got me really interested in science in a way I hadn’t been before.

COLEMAN HUGHES: Yeah. So one of my favorite books too. And I think still to this day, the best single book on evolution by natural selection you can read if you’re only going to read one.

The Path to Studying Chimpanzees

CAROLE HOOVEN: Yeah. And it helped me to make sense of all of the things that I had seen all over the world. I traveled extensively by myself and got into some situations which involved men and I was okay. Nothing happened. I was okay. But traveling around Egypt alone as a young, naive, single woman turned out to teach me a lot about cultures that were different from our own.

And I became really curious about why there were these cultural differences. And I had spent some time in East Africa, and this is before I went to Uganda later to study chimps. But my time particularly around these extremely different ecological and cultural conditions that were new to me as a young college student and then reading these books. So “The Selfish Gene” by Richard Dawkins, who I’m still a huge fan of, and Richard Wrangham’s book “Demonic Males.”

Because first I developed this interest in evolution and genetics and then I read this book by this guy, Richard Wrangham, who happened to teach at Harvard, a primatologist that explained how we could use evolutionary theory and an evolutionary framework to understand human origins. Where did we come from? What can we study to understand how we got to be who we are as humans, why we are the way we are? Why do we have so many similarities with non-human animals and with people in other cultures and so many differences.

And so I decided I wanted to go to graduate school at Harvard and work with Richard Wrangham to go study chimps. But I was extremely uncompetitive and I really had no relevant field experience. I hadn’t really done any serious data collection or have any field experience. So he ultimately offered me a job out in Uganda running his chimpanzee research project and learning how to do research on chimps.

So I went out there for what was supposed to be a year, but ended up being about eight months. Because in 1998 and 1999 when I was there, there was a huge amount of political upheaval in western Uganda where I was. And it was very disturbing. The Peace Corps was evacuated. There were some brutal murders of Westerners and rapes in the region, threats of beheadings of Westerners. So it was a scary situation.

Understanding Sex Differences Through Primates

And I was studying chimps and I was also hearing on the news about this horrific violence. And one profound difference in the behavior of the chimpanzees is that females are relatively peaceful and more concerned with their children. And they just do not engage in the extreme and sort of regular type of violence that the chimps engage in. Sorry, I should say that the chimp aggression is primarily by males.

Females can be very aggressive, but the male chimps are aggressive every day. They’re physically aggressive, competing for status. And then they also form these bonds with each other when they do things like protect their territory and go on border patrols where they get, the male chimps will get in a line essentially and patrol their borders looking for males to pick off from neighboring territories so that they can expand their territory.

And one of the things that Richard Wrangham essentially figured out was that the reason they do that is because larger territories benefit male reproductive success because it gives females more of the resources they need to essentially have more children, so that collectively the males benefit genetically when they cooperate.

So there were these very strong parallels obviously between sex differences in chimps in terms of sexuality and in terms of aggression. And I became very curious about the genetic or some other kind of aspect of their biology that could explain shared similarities in the way that the males and the females behaved. And I became interested in testosterone.

Our genes are very similar. But one thing we and most all other mammals and even across other taxa share is a big sex difference in testosterone with males having much more or androgen similar to testosterone. And there’s very similar patterns of effects in terms of explaining higher rates of male aggression and generally a higher libido and preference for sexual variety.

So I think that’s ultimately what got me interested in testosterone and sex differences in general. And then I had reapplied. I ended up getting evacuated after eight months because the threats of violence were becoming severe right where I was. So there were definitely parallels between what was going on in the world, right in my neighborhood out there in Uganda and what I was seeing also in the chimps. So it really hit me hard.

Graduate Studies at Harvard

And then I had reapplied and I got into the Harvard graduate program ultimately. And the plan was to work with Richard Wrangham. And I worked with him for a little while, but I decided I did not want to go back and study chimps. I wanted to do work and collect data at Harvard. So that’s what I did.

So I ended up getting my PhD at Harvard in cognitive neuropsychology. And my dissertation was based on sex differences in spatial ability. And I also collected saliva from men, mostly college students, and measured their testosterone levels and looked at something called mental rotation, which is the largest cognitive sex difference. So I was curious about whether testosterone helped to explain that sex difference and what the evolutionary basis might be for male superiority ultimately in spatial ability.

And then I stayed on at Harvard as a lecturer until I left in, technically I left in early 2023. That’s when my contract, that’s when I technically retired, but I really stopped teaching in 2022.

COLEMAN HUGHES: Okay, so can you talk a little bit about the circumstances of your departure and how your work in general has been treated over the past few years? I think listeners will be familiar with some of the cancellation story, but can you fill in what they might not remember?

A Thriving Career at Harvard

CAROLE HOOVEN: Sure. So I had a great time at Harvard. I felt incredibly lucky. So given my background especially, I felt incredibly lucky. And I have described my graduate school experience like I was like a pig in sh*t. I was so into it and I just really felt like I’d found my place, found my tribe.

And I had a great, my advisor, I was co-advised by Richard and another professor, Steve Kosslyn and a reproductive endocrinologist, Peter Ellison. And so I stayed on teaching in what the department that eventually became Human Evolutionary Biology. Originally it was Biological Anthropology and it stayed, retained its focus and faculty, but just sort of renamed to Human Evolutionary Biology.

So I stayed teaching in that department. My big course was Hormones and Behavior, and it was a very popular course. It was ordinarily the course in the department with the highest enrollment. I loved teaching it. It was a huge amount of work for me, but it’s incredibly satisfying. And I also taught in smaller courses, and I also advised students, served as their advisor for their senior theses, which are kind of like a mini dissertation. And I just developed close relationships with a lot of students.

And I was able to stay at Harvard in a non-tenure track position because I was hired into this administrative position, which ultimately was co-director of undergraduate studies, which means I kind of ran a lot of the aspects of the undergraduate program, oversaw undergraduate advising, did a lot of advising myself. And so, yeah, I was just deeply involved with the undergraduate program in terms of advising and teaching.

Publishing and Recognition

And then I wrote my book on testosterone, “The Story of Testosterone: The Hormone That Dominates and Divides Us.” It got great reviews overall. There were no criticisms really of the book. I was very proud of it. And after I wrote it through COVID, and it was actually published during COVID in the summer right before we went back to our offices in 2021, and I had literally a new corner office.

I’d just come out with this book I was really proud of. I’d won two teaching awards over COVID. I won teaching awards. I have, I don’t know, like 15 teaching awards or something. I worked really hard over COVID to create an experience for my students that would be meaningful in a remote teaching environment.

So even before I went back to my new office, I had given an interview to Fox and Friends because Bari Weiss at this time had a substack. I can’t even remember what…

COLEMAN HUGHES: I don’t think it was probably called Common Sense.

CAROLE HOOVEN: I don’t know if it was the Free Press substack or was there a Free Press?

COLEMAN HUGHES: It’s probably called Common Sense.

The Controversy Over Biological Sex

CAROLE HOOVEN: It might have been Common Sense. I think it was her Substack at the time. So Katie Herzog, who is a great journalist and co-hosts the Blocked and Reported podcast with Jesse Singal, had written an article in Bari Weiss’s Substack that looked into how medical school professors were backing away from using clear scientific terms, terms like male and female, and that they were getting pressure from the medical students not to use these words because they were offensive.

So I had contributed a quote to that article and so Fox and Friends had me on to talk about this. As I was talking about it, my main point was that nobody, no educator, especially not a science educator or somebody in charge of training our future doctors, should alter what they’re teaching because they’re scared of their students. You know, they’re the instructors. They have the authority. They should teach what the, use the words that make sense that people understand. Teach the scientific concepts that reflect the truth. You know, and this was just obvious to me.

So I didn’t really think twice about saying this on Fox and Friends. And in the process, I said, nobody should be afraid of saying that there are two sexes, male and female, and that sex in biology is defined by the kinds of gametes that organisms produce, you know, or are designed to produce. So that is what got me in trouble, is saying clearly that there are two sexes.

And I also said, but, you know, this doesn’t, I said something like, the facts of nature are over here, and then what we do with them is up to us. And we can use everybody’s preferred pronouns and respect gender identities, but we have to acknowledge the facts and be able to talk about them.

The Department’s Response

So in my department, we have, I think we still have it, a DEI committee. And this one is run, many of the internal departments in universities, many of the departments have their own DEI committees or groups or task forces. I think ours was a task force. The director of the task force happened to be a black woman. And that is important because it plays into what happened later.

So she went on Twitter and identified herself as the director of Harvard’s HEB Task Force, and in that capacity tweeted that she was appalled by, I don’t know why, I don’t remember the exact words. Appalled by my transphobic, definitely. She said, appalled by my transphobic remarks and described them as dangerous and harmful to undergrads.

COLEMAN HUGHES: And.

CAROLE HOOVEN: This, to me, you know, this went out in the world from someone representing herself, speaking on behalf of the department and Harvard and all my students and all the faculty know that the last thing I am is dangerous. If anything, I’m overly caring about my students. And I had taught in the department for, you know, at that point, I think 19 years. Ultimately, it was about 20 years.

So I retweeted her tweet because I kind of was shocked and wanted to take control of it and wrote, “Thank you for your input. I think, you know, I care about the students. How about a conversation?” Anyway, this whole thing went viral. It was picked up by, you know, online in newspapers all over the world. And my reputation on campus took a big, big hit, and the environment in the department changed very quickly.

Some other things happened on campus that involved a chair of another biology department sending out an email with a complaint about my supposed transphobia. You know, this went to hundreds of people, and I was isolated. I felt very isolated in my department. I don’t have my, I didn’t have my own lab. People stopped speaking to me.

The graduate student union took out a petition against me in the Harvard Crimson, saying that I had brought racist abuse and death threats against Laura, that I had caused this. So I became the bad actor.

COLEMAN HUGHES: And did they present any evidence for that part or was it just like out of whole cloth?

The Isolation and Departure

CAROLE HOOVEN: No, I looked on Twitter, there was none. I had seen an email where evidence was supposedly presented and there was none in terms of racist abuse or death threats that I saw. And so as a result, it seems that there was a, and when you teach a large lecture at Harvard or these other elite academic institutions, generally you have teaching fellows or teaching assistants. At Harvard, it’s teaching fellows. I cannot run the course without teaching fellows.

And I generally had two or three and they would run sections outside of the lecture and that’s a big part of the course. And they also grade the exams, et cetera, help to grade. Anyway, so I could not for the first time manage to get any teaching fellows for my course and could not teach it.

And while all this was happening, I was becoming increasingly distraught because I couldn’t believe that no one in a position of power in my department, departmental administration, the dean of science who I met with, Claudine Gay, who was the dean of faculty, they all knew exactly what was happening. It was all over the Crimson, people were talking about it. None of them would speak out on my behalf.

Jeff Flier, who was an ex-dean of Harvard Medical School who no longer had a position in power at Harvard, he offered to my department to publish this statement in defense of me and my work. They said no. I guess that never happened. My chair unfortunately co-signed a letter with the other chair who had sent out a letter saying that essentially that I was transphobic, eventually wrote a letter. I think they intended to apologize to hundreds of people which essentially only blamed me for what had happened and not taking enough care in the impact of my words.

So things just got worse and worse. Steve Pinker and Dan Gilbert, who’s a psychologist, Steve Pinker, also very well known psychologist, was helping me and was supporting me. And ultimately I retired. Definitely not what I wanted. But I was becoming miserable and I just could not stand to go into my department. It was just awful.

So I hired an attorney and negotiated a retirement and nobody begged me to stay. Nobody said we’re sorry. I mean, I suppose there was some kind of “I’m sorry,” but it wasn’t an apology. And I published some of this in the Free Press, a description of what happened, but that’s it. And that’s the story. I left and it was awful.

Understanding Average Differences

COLEMAN HUGHES: So it still is amazing how such a huge episode in your life can be touched off by such, what seems just like such a relatively benign, small comment and, well, a well-balanced comment. I mean, you probably could have even said it in a more barbed way than you did on Fox and Friends, but, and from someone with all the relevant credentials.

So I want to talk, you know, about gender differences and the role of hormones in biology and psychology. But one thing I want to caveat the whole conversation with is that in liberal and progressive circles especially, there’s something very strange that happens when you talk about this subject.

So, for instance, if I were to say the phrase “men are taller than women,” everyone would agree and understand that what I mean is that men are generally, on average, taller than women, even though we all know countless examples of taller women in our lives who are taller than men in our lives, right? No one would say, “Well, hold on a second, my friend Sally is taller than my friend Jim. So that’s not true,” right? No one has any problem holding these two truths in their head at the same time. That there can be an average difference with millions and millions of examples of individual pairs where the opposite is true.

But the moment you make any other claim about differences between men and women, no matter how well it’s supported by the literature, suddenly people lose the ability to see the distinction between an average difference and a categorical difference. And so I assume in this conversation we’re going to talk about many differences between men and women. And for, I mean, you’ll correct me if I’m wrong, but for literally all of them, it is true that you know many women in your life who are higher or lower on whatever trait we’re talking about than many men in your life for almost, if not all of the traits we might discuss or touch.

And so to me, that seems like it should be obvious, but it needs to be said up front. So with that said, let’s start with the effects of testosterone and estrogen. What actually do we know about the role of testosterone in human behavior? What does it actually do when you increase it? What happens as it decreases? What is the role of estrogen in human behavior? And what, if any, are some of the popular myths about what these hormones do?

The Biology of Sex

CAROLE HOOVEN: So, thank you. I just want to address your statement about average differences. So you’re right that every, I would say the only, I would say sex is binary. It’s a true binary. And that is because male and female animals, let’s just stick with animals, are defined by their function to produce one type of gamete or the other.

So that works across all sexually reproducing organisms in that males produce the smaller mobile gametes and females produce the larger immobile ones. I’m not making gametes anymore. However, I’m still female and little kids aren’t making gametes. Some people are born with disorders that mean that they can’t produce gametes, but it’s really, which path are you going down in early development and in mammals say that sex is determined by sex chromosomes.

I just want to clear this up because there’s a lot of confusion about this. So sex chromosomes do not define sex. I just told you what defines sex. It’s gametes. But not all animals even have sex chromosomes. So there’s temperature-dependent sex determination, say in crocodilians. And that means that the undifferentiated gonad in very early development will become ovaries or testes based on the temperature in the environment.

And that temperature will lead to the production of, say, a hormone enzyme called aromatase, which will lead to estrogen production. And in that case, ovaries will develop rather than testes. So that’s one way that sex is determined. So in crocodiles, you can’t identify sex by sex chromosomes.

So you can generally identify human sex by sex chromosomes because males have XY and females have XX. But not always. There are cases in which one male, a male, might have XXY, sorry, XXY, or even XYY, or a female might have XY. And there are interesting reasons for this. And this is because, I don’t know if you want me to go into how a female could have XY, I’m happy to, but the point is that the only, if there’s anything like an essence of sex, it’s about the gametes.

And those are necessary. All females will produce large immobile gametes or will have the theoretical capacity to produce those types of gametes. The reason this matters is because this difference is a very deep, ancient evolutionary difference that influences the way that males and females develop physically and behaviorally.

Because if you’re a small gamete producer, you’re going to have to go generally find and compete for the large gamete producers. And it helps to explain, on average, a lot of the behavioral and physical differences we see between the sexes. The fact that males produce small, mobile gametes and the females produce generally more expensive, calorically expensive, larger gametes. Okay?

So in humans, it is the chromosomes that determine whether the gonads are going to differentiate into ovaries that are capable of producing the large gametes or testes capable of producing the small gametes. That is not the definition of sex. Okay, does that make sense?

COLEMAN HUGHES: Yes.

Sex as a Spectrum vs. Binary

CAROLE HOOVEN: So I’m getting to, sorry, this is a long way of saying that you are correct, that all the other traits that are associated with sex, that are associated with the ability to produce sperm or eggs are on a spectrum that includes something as basic as sex chromosomes, genitalia, which are not always what you might predict for a male or female.

Generally, you know, almost always males will have XY sex chromosomes and a penis. But they don’t have to. Sometimes they don’t. Sometimes a male can have what appears to be a vagina, or a female could have what appears to be a penis. So you can start with these very basic reproductive characteristics. And those are not a clear, distinct binary.

Of course, when you get into things like hormone levels, body types, breasts, breast size, gender identity, however you want to define that, gender presentation, desire for rough and tumble play, parental investment, all those things are of course on a spectrum. So I just think that’s important to say and to clarify.

And what is happening now is that there is a conflation between sex itself and the traits associated with sex. So a book just came out by Augustin Fuentes, he’s a Princeton professor called “Sex is a Spectrum.” And in that book he, you said that most people can agree. I think you said that most people can agree that the sex is.

COLEMAN HUGHES: Men are taller than women.

The Biology of Sex Differences

CAROLE HOOVEN: Yeah. That men are taller than women. And then other set, you gave some other sensible examples. Sometimes people who defend the idea that sex is on a spectrum don’t agree. Somehow they do these tricks where they don’t agree with that or they kind of play with what average means.

So sex is just—I just want to be clear that sexual itself is binary and the sex associated traits are on a spectrum and differ on average.

Okay, so then you ask, what does testosterone do? So when you think about the capacity to—you think about sperm versus eggs. And the goal of natural selection is for organisms to get the highest proportion of their genes into the next generation as possible, generally. And it’s just about copying. It’s about copying DNA, one’s DNA.

And in the case of sexual reproduction, parents are combining their DNA to produce a new individual and they’re each providing half of their own DNA. Okay, so those organisms to reproduce as a male and reproduce as a female, on average, different strategies are needed.

So we can just talk about mammals because that makes it easier. And we can talk just about land mammals, say. So most mammals, in most mammals, males will have multiple female mates and compete for multiple female mates. In the book I talk about red deer.

Reproductive Strategies and Energy Investment

So a dominant red deer, the goal of the red deer is to create a large harem. And in order to acquire a large group of females that you, as the dominant male, would be able to inseminate, the goal is to attain high status so that you are able to—I’m just going to use the word—acquire a large group of females that you will then be motivated to mate with.

And you want to defeat other males in a status competition in order to do that. Those competitions are often physical and require weaponry and large body size and muscle mass and a psychological predisposition to fight during mating season with other males. That’s called mating competition.

And this is because males produce large gametes and they’re—in order to reproduce, they use their reproductive energy budget. All adult humans have reproductive energy budgets. So we put some energy, a lot of energy into growing and surviving. We put other energy into reproducing.

So in order for males, and just with the example of the red deer, to reproduce, they’re using a huge amount of energy to grow to a larger body size, to maintain a high amount of muscle mass, to grow antlers, to pursue females, to mate with them, to prevent other males from stealing—stealing, in quotes—the females.

So this takes a huge amount of energy, and people don’t appreciate that. Yes, female mammals gestate and lactate, and that requires an enormous amount of energy. But we do that with our bodies. It just once we are pregnant, it sort of happens without us having to do anything. We have to nurture our child. We have to let our child suck on our boob. And it’s pleasurable because of hormones like oxytocin.

But males have to go out and invest energy in their body and their behavior in order to reproduce. Okay. And that is because of the difference in parental investment. So the sperm are less calorically expensive to produce. They can make millions. Males can make millions and millions of them. Females make a limited number of more expensive eggs, which provide more of the nourishment for the developing embryo and fetus, obviously.

Okay, so given those differences in strategies, I just gave you an example where there’s an extreme difference, but in only 5% of mammals do males actually invest much, if anything, in parenting the offspring.

How Testosterone Works

So what testosterone does is, first of all, male humans have from like 10 to 30 times as much testosterone as females. And I want to make sure I talk about the critical periods where that has an effect. But overall, testosterone is a reproductive hormone that helps to allocate energy.

So you take energy in and convert it into offspring. That’s the goal. You want to survive. But then evolution shapes us to be motivated to get energy and to use it, especially once we completed growth, to then convert it into offspring. We have different strategies to do that because of the different ways we use our energy differently to do that.

So females have to have their bodies be homes for the fetus that they are growing. And then their breasts are used with the energy that they’re taking in to produce milk to grow the kid or kids once they’re on the outside. So that energy for females has to be used to store energy. So estrogen biases energy intake towards being used to produce body fat, right?

Testosterone biases energy intake to be used to produce muscle. Because these are the reproductive strategies that each sex needs. And we need hormones that direct the development of the physical and behavioral traits. And this is starting in utero that enable males to reproduce.

Critical Periods of Development

And for instance, in utero, males will have again very high testosterone during a critical period in utero which their testes are producing. And that testosterone directs the development not only of the internal and external genitalia, it also acts on the brain.

And we know this from very clear studies in non-human mammals, that testosterone is what is responsible, for instance, for higher rates of rough and tumble play in male animals. So that I should say there’s also a period in humans directly after birth where testosterone rises again in males that’s called mini puberty. It’s about three months after birth.

And that appears to be another time where testosterone is acting on the body specifically, interestingly, and they’re just sort of learning how this works. It has something to do with further penile development at that stage, but also potentially more actions on the brain to masculinize behavior.

So we know from some evidence in humans, but mostly in other mammals that you can regulate the expression of rough and tumble play, like tackling each other. I have a 16-year-old boy, he’s still doing this with his friends. And it makes me nervous because he’s 6’1″ and his best friend is 6’3″ now.

But this is what they did growing up. And they’re not like these tough, super athletic boys at all, but they’re one of their favorite ways to play and has been since they were little, is tackling each other and wrestling. Two girls playing as kids rarely play, you know, prefer to play that way.

And this is not something that is unique to humans. We see this in male mammals, particularly when as adults, physical competition is necessary for reproductive success. And it’s a skill that has to be learned. And aggression is reduced in adults when the as kids, boys learn how to play with each other aggressively and learn the signals, learn who’s dominant, and learn sort of when to submit, when not to submit.

COLEMAN HUGHES: How do we know that aggression is reduced in adults?

Evidence from Animal Studies

CAROLE HOOVEN: So we know this, this is—so the best studies we have are from non-human animals. And there’s a series of studies that if you prevent, you maintain a young male’s social environment, but you prevent him from playing with other males. Other males, I think. And those males as adults have higher rates of aggression than the young males who just play typically rough with their male friends, or whatever you want to call them, and other animals.

And the reason they’re less aggressive is because they learned how to regulate aggression. So play is the main thing that kids do. And the sex differences in play have something to do with reproductive behaviors. It’s practice for survival and reproductive behaviors that each sex needs in adulthood.

But what we do, I think, have better have good evidence for is that in non-human primates and in rodents, if you block male testosterone in utero or directly after birth, depending on when the critical period for masculinization is, you block rough and tumble play. So you can also add high male levels of testosterone to females in early development and you increase rough and tumble play.

And in humans, we know that in little girls who have excess testosterone in utero, they have higher rates of rough and tumble play. So the point is that it is this sex difference in testosterone that starts in utero and that sets each sex down on somewhat of a different path because they are developing sexually specific mating strategies, essentially, and they’re practicing them as kids.

Again, this is on average, there’s a lot of boys who don’t like rough and tumble play. And notably, boys who grow up to be gay show lower rates of rough and tumble play, which is interesting. But those boys who grew up to be gay show typical male sexual behavior, which is interesting because both of those things are mediated by testosterone in non-human animals. But that’s an aside.

So your question about increasing—okay, so that’s the first critical period. And the fact that when the kids are little, you know, say 4, 5, 6, 7, boys and girls don’t have differences in testosterone. That difference stopped a few months after birth. Like that was the end of the high testosterone. Girls never had much testosterone in utero. They have some and they have a little estrogen peak after birth, but they don’t require any specific sex hormones to show typical feminine behavior. It’s that if you don’t have that testosterone exposure, you are likely to show typical feminine.

COLEMAN HUGHES: So just to get this clear, if we’re looking at a group of 7-year-olds and we’re seeing that the boys are wrestling with each other and doing arm wrestling and the girls are by and large not doing that, that’s not because their 7-year-old levels of testosterone, if we measure them today, are any different. That’s just the long tail effect of being, having, being swamped in testosterone in the utero and in the early months of life.

Long-Term Effects of Early Hormone Exposure

CAROLE HOOVEN: That’s correct. Okay, so those are again, so in humans we can’t do the experiments to show exactly what is happening in the brain, but we do have a lot of evidence from non-human animals that testosterone is acting on specific parts of the brain, but that have to do primarily with sex and aggression.

And there’s some areas that have been identified, but it seems that testosterone is having more subtle effects on neuronal development, connectivity, death that affect overall behavior. I don’t think we still have great data on exactly what neural changes that testosterone leads to cause the different outcomes.

But we do know that you can manipulate these sex based behaviors that are more typical of one sex or the other by manipulating early exposure to testosterone. And so even if we didn’t have puberty as the next critical period, or we didn’t say we didn’t have sex differences in hormones or any sex hormones in puberty, you would still have these long term effects of the different behavioral patterns and social patterns that affect brain development that happened in childhood.

You know, if you’re doing a lot of rough play that’s going to shape the way your brain develops and the way you develop psychologically and socially. So just that large sex difference in behavior that is, I would say caused by a difference in testosterone exposure has long term effects on its own that don’t go away.

Nature Versus Nurture

COLEMAN HUGHES: Okay, so how do we know that the behavioral differences like rough and tumble play, for instance, are the product of hormones that are downstream of sex differences as opposed to how society tells boys they’re supposed to behave, how society tells girls they’re supposed to behave? What’s the best evidence or the best natural experiment that you would show to a skeptic who believes it’s all acculturation?

CAROLE HOOVEN: So first I would ask the skeptic, why every culture all over the world, why do we have no cultures where girls are doing this behavior and boys are playing house? Say, I mean, everyone uses their iPhones now but when kids are playing outside and have a lot of technology, like the way I grew up, why do we not have any? Why is culture everywhere across the world leading to the same outcome? Why is this the cultural norm?

COLEMAN HUGHES: Yeah, I mean, so I’m not a skeptic, but if I were to play devil’s advocate, I would say, well, you know, there’s a culture, a long standing culture of the patriarchy almost everywhere in the world for thousands of years where it just somehow it got locked in that men were to behave a certain way and women were to behave another way. And so, you know, it’s basically, it’s cultural on all four corners of the earth down through time.

The Biological Basis of Sex Differences

CAROLE HOOVEN: Yeah, I mean, I think that’s a very hard argument to make. But where I go is to say, first of all, let’s think about why this difference might exist. So I would point to evolution and reproductive strategies.

We have a theory that makes a whole lot of sense and clearly explains what we’re seeing in non-human animals. And we see the same thing in humans. So it’s predicted just based on evolutionary theory. And where we’re coming from our own evolutionary history, where we no longer have to use physical aggression to attain status in order to attain mates, we’ve been acculturated out of that—not everywhere, but in most western societies. And so you would predict that.

And then you do find that we also have a mechanism, and that is testosterone. And that mechanism of this specific hormone regulates a suite of behaviors that promote male, or have promoted male reproduction in human evolutionary history and currently in many non-human animals.

And we know this because when you manipulate testosterone in the different sexes or you manipulate the receptor or any number of other kinds of experiments, you can reverse the feminization or masculinization in terms of brain and behavior.

So then you could say, okay, well where’s the evidence in humans? Because we have this confound. We do have an extremely gendered society and there’s a lot of reinforcement of masculine norms. And that is a fact.

So here’s some evidence. Boys’ behavior is really very strict, often strictly policed to be, you know, especially by other boys who can be quite cruel if the behavior is not masculine enough. So there’s an incentive for boys to engage in rough play because they are often bullied and harassed if they’re seen as sissies.

But there are boys, especially these boys who are gender non-conforming as kids, they often will not engage in rough play because they don’t like it, no matter how much pressure they have from their dads or teachers. And so I think there are some counterexamples.

But then we have this evidence from girls who have congenital adrenal hyperplasia. And there’s a lot of pushback on the evidence because the people who want to support the argument that you just made hate that there is any evidence that shows that testosterone in utero increases rough and tumble play in girls.

At this point, there are probably over 100 studies, very well designed, clear studies that show—I think it’s over 100.

COLEMAN HUGHES: There’s a kind of—sorry to interrupt, but there’s just a kind of paradox which is interesting to me where, because people on the sort of postmodern “gender as a spectrum” side of this argument will often cite these examples of girls that behave in male typical ways and boys that behave in girl typical ways.

But then when you scratch beneath the surface, you find that those cases are cases of biology doing its work as well. And so beneath the surface, it actually ends up undermining their whole argument if all the girls that like rough and tumble play are girls with higher levels of testosterone, which then goes back and reinforces the idea that biology really is doing the lion’s share of the work to begin with. Is that right?

CAROLE HOOVEN: I wouldn’t—yeah, I don’t know. So, for instance, I don’t know that I had high prenatal testosterone. I had three older brothers, so maybe there was something about my environment.

But what we do know is that the girls who have congenital adrenal hyperplasia, who clearly have higher than average or sort of atypically high—not reaching the male range, that’s very difficult for a female to do—but atypically high testosterone, overwhelmingly are showing masculinized play. So that’s just a fact. And there are many, many studies showing that.

I don’t know if you can make the claim from play to higher testosterone, but it’s likely. And we don’t have terrific measurements of testosterone levels in the womb that fetuses are exposed to in general. But we know when there are these disorders that there is elevated testosterone.

And there’s also a masculinization of the clitoris. So there’s some physical effects of, say, congenital adrenal hyperplasia. So we have an index of how high the testosterone might have been based on clitoral size.

Where Sex Differences Matter Most

COLEMAN HUGHES: Right. So in everyday life, I’m talking about work, school, sports, et cetera. Where do these sex differences, these average sex differences matter the most and where do they matter the least?

CAROLE HOOVEN: Sex is the big one. So we have very clear evidence for testosterone. So here it gets interesting. So sex and aggression do seem to come apart a bit in terms of the effect.

So when what we should be thinking about, when we think about the effects of testosterone is really, and how to understand sex differences is really the fact that men have so much more than women, not sort of the differences among men or changes in male testosterone. Although male testosterone does change for some interesting social reasons, and I would like to come back to that.

But the meaningful difference is that males have so much more, many, many times more. The level—just say 20 times as much as females. So there’s some threshold and above that threshold you get male typical behavior.

So sexuality seems to be male typical. It’s not—you can have relatively low, but, you know, healthy range or relatively high. It predicts nothing about sexual behavior and so far as we know, it predicts nothing about aggression.

However, the fact that you have a male typical level predicts that you are going to have a much higher sex drive than most women. You are going to have a much stronger preference for a variety of sexual partners than most women. That just seems a male—if you have been exposed to typical levels of testosterone, you’re going to have a male typical sexuality.

You may or may not have male typical aggression. You know, that’s something we can’t measure in the lab because most people are not physically aggressive. But of the people who are extremely physically aggressive, they’re almost all male. You know, they’re 80—depending on the violent crime, you know, 80 to 99% male.

So, and if you look at the patterns of violent crime, it pretty well parallels the peak and then sort of plateau in male testosterone levels, which from an evolutionary point of view would have mirrored the height of male-male competition for mates.

There’s a bit of a delay after the peak in puberty and that is because—again, my son, sorry to use him, sorry, I won’t say his name—but he’s tall and thin right now and he’s 16. He’s got a lot of testosterone going on. But he had, you know, the teenagers are just entering the adult kind of mating market. They’re developing their musculature, they’re developing their dominant skills, they’re figuring out what they’re good at, how they can achieve social dominance.

It takes a few years for them to really enter that adult mating market and that’s when we see this peak in male violence. So sorry that was kind of getting off of your question.

But so we’ve got these two aspects of masculinity and I’m saying that the sexual, the masculinization of sexuality seems to just require some threshold. We have a huge amount of variation in aggression. It’s just that females on average are much, much less physically aggressive than males.

So in terms of where this plays out, competitiveness—a lot of women don’t like that. But there’s a different element. Females, of course, I’m not saying are not competitive. Many women are extremely competitive. But male-male competition takes on, in my view, a different nature here.

So the evidence for the testosterone involvement is best for sex and aggression, and that’s in humans and non-human animals in terms of the sex difference, particularly for sex.

Effects of Testosterone in Gender Transitions

So what’s interesting is that if you look at people who transition, making a gender transition and use hormones to do that, if they go from female levels of testosterone—so a woman transitioning to live in the male sex role, who takes male typical levels of testosterone—the most common and profound psychological effect that happens within a few months is they go through something like a male puberty and are generally shocked by the intensity of their sexual desire.

There’s variation here in the effects. But this is one thing where you’re going from a female typical on average type of sexuality to a male type which is more intense, more focused, more driven, and more objectifying of whatever the sex they’re attracted to.

So the same—there’s a similar need for ultimately love. But the high testosterone seems to lead people—and here I’m using what I have heard and there’s hints of this in the literature about objectification. I’ve heard this from a few people who have transitioned that they began to objectify body parts, think more and fantasize more and have more mental imagery about the body parts of the sex they’re attracted to while still having a longing for love and intimacy. There’s this other, you know, heightened drive and obsession with sex.

COLEMAN HUGHES: The other data point there is firsthand accounts, which there’s this guy, More Plates More Dates on YouTube who analyzes—he’s a former steroid user and bodybuilder that analyzes especially famous celebrity body transformations.

So you’ll have a celebrity, you know, like Kumail, whatever his name is, Kumail Nanjiani. I might be getting that slightly wrong, but he has a totally normal guy’s body and then six months later he’s in a Marvel movie looking like a God, which is, you know, as you know, not actually possible from—you could lift weights two hours, three hours a day. You can’t go from a normal scrawny guy to looking like, you know, Liam Hemsworth in six months. It’s just not possible. That takes many, many, many years. Unless you’re taking a whole bunch of testosterone, in which case you can actually do that in three, four months.

CAROLE HOOVEN: Yeah.

COLEMAN HUGHES: So he analyzes these bodies, these bodily transformations from the point of view of someone who has taken steroids. And steroids is just a suitcase term for different kinds of testosterone and other similar hormones. Often it’s just straight up testosterone.

But he analyzes these first person accounts that people will, you know, former steroid users will—I started taking testosterone and here’s what happened to my life in the next two years. And half of the stories are just people destroying their lives because they became so incredibly horny every single second of every day. Destroying their marriages, their relationships, getting into physical fights.

CAROLE HOOVEN: This is the anecdotes from—

COLEMAN HUGHES: These are anecdotes usually shared on Reddit or in essays. But this guy, More Plates More Dates on YouTube, he’ll read them because his whole channel is devoted to this genre of content.

CAROLE HOOVEN: Okay.

COLEMAN HUGHES: And so I have found those to be very entertaining and enlightening. So, you know, it’s not only women that want to transition to present as a man, it’s also men that double or triple their natural levels of testosterone in order to get jacked.

Supraphysiological Testosterone Levels

CAROLE HOOVEN: Okay, this is interesting because there is some very solid data showing that even when you raise male testosterone levels to supraphysiological levels, but maybe not to the levels that you’re talking about, sex drive tends not to change.

But these could also be guys who are in relationships or who are not so jacked that they’re getting a lot more attention from women. So here you have somewhat of a social potentially confound because once you change your body, it’s going to be easier to get sex. Generally if you’re a guy and you’re getting completely ripped.

So yeah, I haven’t seen the data that shows that effect in males. But possible. Yeah, but I can imagine it would happen.

COLEMAN HUGHES: It’s possible. These are people taking extreme amounts of Tren, Trenbolone and things like this. Not like the amount that a 50-year-old guy would go to his doctor to get, you know, testosterone therapy. These people are taking much more than that.

CAROLE HOOVEN: Yeah. So that’s interesting. Did they say anything about aggression?

COLEMAN HUGHES: Yeah, it’s, you know, people for the first time in their lives, getting in bar fights, this kind of thing, ending up, in some cases, ending up in prison. And, you know, looking back on the whole thing as, wow, why did I do all this to my life? Just to get jacked?

The Risks of Exogenous Testosterone

CAROLE HOOVEN: Yeah. No, I’m so glad you’re bringing this up, because people do not appreciate that once you start getting the benefits of high exogenous testosterone that you’re taking, that’s not produced naturally by your own body, when you take that testosterone, your brain senses that you have enough testosterone in your system and it stops sending signals to your testicles to produce testosterone.

So your testes kind of shrivel up because they’re not producing sperm or testosterone anymore. And it may take a long time for that function to come back online. And if you take enough of it for long enough, it’s not clear that your fertility will ever return. So in some cases, from what I understand, it could cause permanent infertility.

But suppose you have great erections, you’re getting super muscular, you’re getting a lot of attention, you feel great, and then you stop. Your testosterone won’t come online for months necessarily. I mean, it could be quite some time. So during that time, you’re not even going to be able to get an erection. You’re going to start losing muscle mass.

So this is why people become addicted, because coming off of it is so difficult. You know, you go from having tons of sex to essentially having none. So that’s something to really consider before you start taking it. That would be very difficult to come off of it.

Where Sex Differences Matter Least

COLEMAN HUGHES: Okay, so we never quite got to the second of my earlier question. Where are the sex differences in everyday life the least important?

CAROLE HOOVEN: Yeah, well, I guess I’m biased. It’s hard for me to think of any area where it’s not important because men and women are, and boys and girls are very different. Even intellectually, I think we’re different. Cognitively, we’re different.

I wrote an article for Quillette on sex differences in chess, and there are very large sex differences in chess, with males consistently, on average, dominating females. And it seems to be the case, I think the reason is that males have something called higher rates of obsessive drive, where they will focus intensely on one thing and becoming the best at that one thing and winning at that one thing and put their, more driven to put the time in.

I don’t see a clear relationship to testosterone in the literature. So we’re not, super important in terms of the role of the sexes in raising the kids. Sometimes it’s reversed, but in terms of large patterns and behavior.

COLEMAN HUGHES: It’s important everywhere.

CAROLE HOOVEN: I think it’s important everywhere, but it must be not very important in some places maybe. Can you think of something? I’ve never been asked this.

COLEMAN HUGHES: I love this. I mean I agree it’s important everywhere to a degree, but you know, that itself is a spectrum. So you’ve got sports on one end where we just have to segregate men and women to play sports essentially, unless you’re one of the few people who thinks we can get rid of that.

But we don’t have to segregate a journalism school. Right. Men and women can collaborate together on equal terms across various aspects of life and pretty much treat each other without regard to sex. And things work out in certain spaces and in other spaces men and women actually just straight up need to segregate.

CAROLE HOOVEN: I think you’re trying to talk more about practical implications.

COLEMAN HUGHES: Exactly.

CAROLE HOOVEN: Yeah, yeah. Then it doesn’t matter. Yeah. In the workplace, you know, it shouldn’t matter, but of course it does because there’s sexual harassment. There’s men doing each other favors and you know, women doing each other favors or women gossiping about men or you know, so officially, I mean, so I guess I think it matters in every social environment.

But like you’re in a relationship. What about your, do you think it matters in all aspects of your relationship or would?

COLEMAN HUGHES: With my fiance? Yeah, yeah, absolutely. Like, yeah, it would not make sense for her to treat me as if I were a woman and for me to treat her as I were a.

CAROLE HOOVEN: Man or just treat each other as human beings. Right. So that’s what I’m trying to think. Do we ever interact in a way that fails to account for or acknowledge or aware that our sex, meaning the effects of testosterone, say and or estrogen, different exposure over a lifetime is not part of that or an important part of that?

COLEMAN HUGHES: Well, I think in like a, it’s like a healthy, normal workplace environment, most of your actions will be indifferent to sex. That’s not to say there’ll be a sexual harassment situation or people will start dating and then it becomes very important. But in the run of the mill course of an average day, it really shouldn’t matter that much.

CAROLE HOOVEN: It shouldn’t and it doesn’t. Yeah, I think it shouldn’t, but I think it often does. Okay, so I didn’t give a good answer there.

COLEMAN HUGHES: No, that’s okay. You gave an honest answer and that’s what matters.

Long-Term Effects of Hormone Interventions

Okay, so what do we know about the long run effects of suppressing testosterone in the case of, say, puberty blockers in adolescents that have gender dysphoria? Or the long run effects of taking testosterone in the case of a natal female trying to transition to present as a man?

CAROLE HOOVEN: Okay, so this is a good way for me to piggyback on the last question because I can start out by talking about, so sex hormones are coordinated with the type of gametes we produce. So if you have like testosterone goes up in puberty because you’re making sperm, you’re becoming sexually a sexually viable mammal.

And you need to then develop the secondary sex characteristics and behaviors that will increase your chances of successful mating and et cetera. Right. So just starting with that in adults, especially in males, we do not see this in females with testosterone or estrogen in any of the studies that I have seen and I have looked very hard.

COLEMAN HUGHES: We.

Testosterone as a Dynamic Social Hormone

CAROLE HOOVEN: So females have changes in estrogen, of course, across their cycle that do. Those changes do appear to affect behavior in ways that are meaningful for reproduction. And men also have changes in testosterone that are relevant to their social situation, their status, their competitiveness, their risk taking.

Men get feedback based on their perception of what’s going on socially. That is translated often into alterations in testosterone level that are coupled with the environmental stimuli. So this is super important. And people don’t really understand that this happens.

And when you take exogenous testosterone, you are preventing these natural evolved, this whole system that has evolved to tune you into what’s happening socially and how you, Coleman Hughes, can increase your status or how you, should you compete or should you back off? Is this woman fertile or not? Do I have a chance competing? Not that you’re competing now, but do I have a chance competing against this other guy for this woman’s attention? Do I have a baby? Do I have a partner?

So when you entered into your mateship, you probably, when you’re committed to one female, you’d probably have a bit of a decline in testosterone. It’s just like when monogamous birds are setting up their territory and fighting off other males, they have an increase in testosterone, but when they pair up with one female, their testosterone goes down. It has to go down or else they will, when she has kids, the father will abandon the children if the testosterone is raised.

So suppressing testosterone in a relationship is adaptive. It’s not always good to have high testosterone and be out aggressing and trying to find new females. Okay, so that’s just a way of illustrating. And there’s much more to those social changes than I just said.

But the point is that there is a system in place where this is a dynamic hormone that influences and responds to social situations. So that when you have people who first of all go through, it’s not even a real, it’s not even, it’s a type of puberty will go through a, like if a male goes through an estrogenic puberty, he’s, that means he’s taking exogenous hormones.

Of course, that whole system that happens in females with monthly cyclic changes in hormones is not going to happen in a male, first of all. And similarly, when a female takes testosterone, actually, yeah. She will not experience those same kind of, that same kind of social feedback. So that’s one thing to think about.

COLEMAN HUGHES: The second thing, that’s a very interesting point. Can I linger on that before you go to the next point? So you’re saying the way testosterone works in a natal male is that maybe I get a burst of testosterone in response to specific events that my brain is telling me are good times to get a burst of testosterone. I don’t know what that means.

CAROLE HOOVEN: If you beat someone out in a.

COLEMAN HUGHES: Competition, my team wins in a competition. Right. Or if you take a risk and win.

CAROLE HOOVEN: If you win a chess game.

COLEMAN HUGHES: Right.

CAROLE HOOVEN: So there’s a lot of.

COLEMAN HUGHES: There’s feedback between when I get testosterone and how much I get and what’s actually happening in the real world. And that feedback allows me to navigate the world, encourages me to navigate the world towards higher status.

CAROLE HOOVEN: Or it’ll help you realize that, okay, you don’t have high status.

COLEMAN HUGHES: I’m not the alpha here.

CAROLE HOOVEN: Yes. Maybe you need a different strategy, like pair up with one female and be an amazing dad and you’ll have just as many kids as if you’re a higher status male with, you know, potentially higher testosterone out on the mating market all the time. You might come out even. But you’re using two different strategies. Okay.

COLEMAN HUGHES: Right. And you’re saying you’re making clear here that if you’re a natal female taking testosterone, that link between testosterone and navigating the world isn’t the same. You’re just getting a constant dose.

CAROLE HOOVEN: That’s correct.

COLEMAN HUGHES: Okay, so continue.

The Organizational-Activational Hypothesis and Cross-Sex Hormones

CAROLE HOOVEN: Not only are you getting a constant dose. Okay, here’s another really interesting, what I think is a very interesting overlooked factor in transitions. So I explained what happens in utero and there’s very good evidence in non-human animals that testosterone is having high testosterone in males, having different effects on the brain development than having no testosterone in utero. We know that there’s, that that really matters and influences some different outcomes.

So the idea is that this is called the organizational-activational hypothesis. And it’s not this simple, it is more complicated. But the idea is that in puberty, when testosterone goes up in males, it is acting on the masculinized brain. It’s acting on those masculinized neural structures to produce certain kinds of adult behavior.

So if you are a female who is taking high levels of testosterone, you’re not going to act exactly like a typical male because you have essentially something like, there’s not also just a female brain and a male brain, but there are brains that are more feminized and more masculinized. If you’re a female and you take testosterone, it has not been masculinized in utero. So it’s not the same act. It’s not going to be the same effect as pubertal testosterone in a typical male.

So now you take trans women who do have a masculinized brain, say who did go through male puberty, which is the second critical period which also has permanent testosterone, that high testosterone also has permanent effects on the brain and body, obviously in puberty. So if you take a trans woman who’s a male who transitions after puberty, that male has already had a double dose of testosterone on the brain and is now blocking it and taking estrogen.

You may have remnants of some very typically masculine behaviors, especially certain types of aggression seem to be still sexually differentiated, more masculine style of aggression, even in a male who is on estrogen. And part of the reason might be that it’s because of this early masculinization combined with the further effects of high levels of testosterone in puberty.

Effects of Cross-Sex Hormones in Puberty

Okay, but what you asked about is what are the effects of taking cross-sex hormones in puberty? Right? So one thing we know is, so the point of the high sex hormone or reproductive hormone levels in puberty is to masculine, sorry, to further develop, fully develop the reproductive system so that it’s capable of producing sperm in males and eggs in females, and then combining that reproductive system development with changes in the brain, like more risk taking, more sex drive, more nurturing, more socialization and status competition, pairing those traits with the availability of gametes.

So if you do not go through a natural puberty and you do not develop the testes and ovaries and genitalia so that they’re capable of producing gametes, and then in the male case, delivering gametes into the external world like a female’s genital tract or however you want to release your semen, if you don’t go through that development, so in the male there’s no capacity for erection anymore. The penis hasn’t developed, the sperm will not be made, the semen will not be produced.

So there will not be a typical male orgasmic capacity there. I don’t believe that there is evidence of orgasm. And here there’s definitely not going to be the capacity to produce sperm, so there’ll be permanent sterility and sexual function is definitely severely inhibited. And I don’t believe there’s evidence of orgasm in those males who go through an estrogenic puberty.

There is some anecdotal evidence of non-ejaculatory orgasms in men, but I’m not sure that it happens in this particular population. And so for females it’s a little bit different because the clitoris grows under testosterone. And I believe that there’s some orgasmic capacity for trans men.

But there’s again, it depends on what Tanner stage. I should qualify and say that if you let the ovaries and testes develop sufficiently, you might be able to harvest sperm or eggs or potentially resume capacity for their production. But generally when puberty blockers are started, say Tanner stage two, there’s not sufficient development of the ovaries and testes to allow for gamete production, so there would be no future fertility.

And of course we need more time to study this stuff and do more research. But so it does seem that fertility is permanent, infertility would be permanent in this population, and generally sexual function will be severely inhibited, particularly in males.

The Evidence Base for Youth Transition

COLEMAN HUGHES: So if you were to boil it down to the simplest possible terms to like a one minute answer, what is it that the trans activist community in general has wrong about the implications of cross-sex hormones and so forth for adolescents or even young adults?

CAROLE HOOVEN: Yeah, so I’m, my area is not really on how effective transitioning would be for alleviating gender dysphoria. I know about that literature, but a lot of people know more than I do. The idea is that the evidence base is just not there to support the claim that hormones and surgery, particularly in young people, alleviate their psychological problems, especially gender dysphoria.

So, you know, the recommendation is that young people under 18 not take puberty blockers because almost all of the people who start on puberty blockers progress to cross-sex hormones so they would interfere with their natural puberty. And there are studies that strongly suggest that going through natural puberty is what allows people to come to terms with their sexuality and experience some experience what it’s like to be a sexual human and have sexual activity and maybe some orgasms.

Because if you interfere with natural puberty, you’re not going to even experience any of that stuff before you decide to maybe never have it or never have kids. So the idea is just that the evidence base isn’t there for the benefits.

Segregating Sports by Hormone Levels

COLEMAN HUGHES: Okay, two more questions. Yeah, I heard someone online recently argue that sports should be segregated by hormone levels instead of by sex.

CAROLE HOOVEN: Almost Neil deGrasse Tyson.

COLEMAN HUGHES: It might have been, yeah, good idea or bad idea?

CAROLE HOOVEN: A terrible, terrible, terrible idea.

COLEMAN HUGHES: Why so?

CAROLE HOOVEN: It’s just ridiculous on its face because what we have makes sense. So there’s a reason we separate by sex. It’s because all those things, hormone levels, strength, limb length, bone density, speed, all those things are generally captured by sex.

It doesn’t mean that it’s fair. It’s not fair. Whoever said sports was fair? It’s not. Some people are just genetically blessed. Some people have more money and opportunity to practice. Some people put more energy into practicing. Some people don’t have kids and can practice. I mean, there’s a million reasons why some people are going to be better at sports than others, and it’s not fair.

But there’s no bigger divide. There’s no bigger single predictor of success than sex. If you’re, you know, especially if you’re at the elite level and everybody is similarly trained, there’s just no evidence that females could do, could match. So ridiculous, this claim and people are making it that women could match men if they just had the same opportunities in terms of training and support. There’s no evidence for that.

There was a, after Title Nine, there was a large increase in female performance relative to males, but this plateaued, I think in the, I can’t remember, I don’t want to say exactly one, but this plateaued many years ago, the sex difference. So it’s, women are still, you know, doing a little bit, making small improvements relative to men, but there’s no way that, there’s no evidence that the gap is closing.

It seems to have pretty much stabilized and depending on the sport, you know, like a 2% to 20% difference. It depends on the sport, but it’s such a monumental gap that there are thousands of high school kids. I think it’s thousands. Sorry, I don’t want to get the numbers wrong. There are a lot of high school boys who could beat the female Olympic champion in most track and field sports, for instance.

So, okay, so you could take hormone levels. Okay, so suppose you take hormone levels. Suppose you take, yeah. How would this even work? So you could take somebody like Lia Thomas, who blocked, who’s a male, who’s an adult male. Lia blocked, I’ll say her. But people should keep in mind this is an adult male blocked her testosterone.

So if you used hormone levels, that it would be completely fair for Lia Thomas to compete against Riley Gaines. Okay. Both of them, you know, exceeding, have all of the opportunities for training and are both working hard, as hard as they can. And but Lia Thomas has already gone through male puberty, already has increased bone density, already has height, already has masculinized heart and lungs, and all of these advantages that don’t go away.

And why should we just take hormone levels? Why should we mess with the categories that we have? It just doesn’t seem fair because it only hurts women. It is males.

Who’s Actually Asking for These Changes?

COLEMAN HUGHES: One of the strange things about this is like, I have never heard a professional female sports athlete ask for this. The people I’ve heard that want to sort of change sports are invariably not even athletes, right? Like, they’re not even people that play sports professionally for a living. They’re like professors at a university of some issue.

So if it were an organic demand coming from within the sports community, I mean, and of course, at some level, one has to discount the Lia Thomases of the world only because she, and to be polite, I’ll use her pronouns as well. But she is precisely the small sliver that stands to benefit from this thing being changed. She’s one stakeholder in a world where 99% of the stakeholders are not really going to benefit, most men are never going to transition anyway.

And no natal female stands to benefit from these categories being collapsed. So, and then you have examples where, like, the best women athletes in the world, like Serena Williams, you know, was very, was like, you know, you can go back and look at the actual interview. But she was like, why are people saying that the women could compete with the men? Like I, as the best woman tennis player in the world would not be able to compete with the men.

CAROLE HOOVEN: Right. I quoted her in my book from that interview.

COLEMAN HUGHES: And why do, I don’t need this to be the case. Like, I’m perfectly happy being the best female tennis player in the world. Right.

CAROLE HOOVEN: And she wants to compete against women.

COLEMAN HUGHES: Yeah. Which is the best?

CAROLE HOOVEN: Because she wants to be the best. And it’s not fair to have to compete against men. And you’re right. It’s people who have no skin in the game or men who are advocating for this. And it is very annoying as a woman to have males who identify as females say guilting women and gaslighting women and everyone else saying, you guys are bigots because males want to join your female category and you’re not letting them.

So you’re a bigot or you’re a transphobe and you’re not even allowed to have the conversation. That is ridiculous in my view. It doesn’t mean that there aren’t people who are frustrated, like trans women in particular or trans girls, frustrated about not being able to compete. But I don’t think they should be barging into the female category. It’s inconsiderate and wrong.

And also biologically, there’s just tons of evidence that if you block testosterone, yes, you’re going to lose some of your capacity, but you don’t get into the female category by picking out little pieces that matter and then saying, okay, maybe now you can have a chance. As long as you’re not, it just doesn’t make sense and it would never work. And Neil deGrasse Tyson is completely wrong on this.

COLEMAN HUGHES: Okay, last question. What is the most interesting unanswered question in the field of hormonal research?

Future Research on Testosterone and Hormones

CAROLE HOOVEN: Oh, wow. So this is a really good question. And I think the area where we need more work is on what I was talking about before and how, first of all, testosterone motivates exactly how it motivates particular male behaviors and the dynamic nature of testosterone and how it interacts with the nervous system. So this is the neuroendocrine system.

For instance, there’s some evidence that testosterone is having an effect on dopamine in reproductively relevant situations. And we have some clear evidence in non-human animals. And it would be great to understand more about how this works in humans.

And also, we really don’t have enough research on the role of estrogen in male and female behavior. And I think that would be super interesting because all estrogen comes from androgen precursors. So testosterone is converted in people who lift a lot of weights and are trying to get really big, know that the enzyme aromatase converts testosterone into estrogen because they try to block it. They take aromatase blockers.

So what we don’t know is if you—like, I take some testosterone as part of my HRT. I take estrogen, progesterone, and testosterone. What we don’t know is the extent to which in women, our testosterone is acting through estrogen and acting on estrogen receptors, or if it’s acting as testosterone on androgen receptors.

We don’t know a lot of that in men either, whether male testosterone, you know, when is it acting as testosterone via androgen receptors or after it’s been converted to estrogen in estrogen receptors.

There’s also some interesting research going on that is, look, it’s more clinical about the relationship between testosterone and obesity and diabetes and its potential for treatment in some metabolic disorders. Also, there’s mood. What is the relationship between low testosterone and depression?

And then in women, just what exactly is testosterone doing in terms of behavior? I think we really, the research that we do have shows it’s, as far as I can tell, it’s not doing the same thing as it’s doing in men. It doesn’t react in similar ways to competition, et cetera. So we need more work in women.

Where to Find Carole Hooven’s Work

COLEMAN HUGHES: All right, Carole Hooven, before I let you go, tell my audience where they can buy your book, what it’s called, and how they can follow you online. Oh, here it is.

CAROLE HOOVEN: All right, so my book, I just happen to have it right here, is called “T: The Story of Testosterone, the Hormone That Dominates and Divides Us.” And you can get it, you know, anywhere you get books. Amazon, and I am on Twitter at Hoovelet. H-O-O-V-L-E-T. I’m trying to do Instagram, so maybe I’m—I think I’m Carole Hooven on Instagram, but I still have to figure it out.

COLEMAN HUGHES: Awesome.

CAROLE HOOVEN: Thank you.

COLEMAN HUGHES: All right, thank you so much, Carole. Thanks for coming on my show.

CAROLE HOOVEN: It’s a pleasure. Thank you.

COLEMAN HUGHES: All right.

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