The Science of Testosterone || Carole Hooven

a very thoughtful and nuanced fashion. We have balanced discussions from multiple perspectives, including scientists, activists, and a leading feminism scholar. This series will hopefully expand your mind and help you make sense of the current heated debates surrounding the distinctions between sex and gender as well as transgender issues. The aim is to turn down the temperature on this very heated topic and increase understanding and integrate truth with love.

I hope you will listen to this entire series with an open mind, in an open heart, and as always we look forward to hearing your feedback and comments on our website and on the YouTube channel so that further ado I bring you this episode within the Making Sense of Sex and Gender series. Today, we welcome doctor Carol Hooven on the show. For the past six years, Doctor Hooven has served as a lecturer and co director of

undergraduate studies at Harvard's Department of Human Evolutionary Biology. She has received numerous teaching awards, and her popular Hormones and Behavior class was named one of the Harvard Crimson's Top ten Tried and True. Currently, doctor Hooven has moved to the Psychology Department, where she works as an associate at Stephen Pinker's lab. Her latest book is called t The Story of Testosterone, The Hormone that Dominates and Divides Us. In this episode, I talk to doctor Carol Hooven about

the science of testosterone. Why do males have higher rates of physical violence, take on more risk, and desire more sexual partners. Doctor Hooven's research points to testosterone as the answer. Although sex differences may stem from biology, she also points out that variations and behavior may be better explained by genetics interacting with culture. We also touch on the topics of evolutionary biology, gender dys for you, gender affirming care,

and academic freedom. So that further Ado, I bring you Doctor Carol Hooven. Doctor Carol Hooven, the Harvard evolutionary biologist. How you doing. I'm okay, it's a little stressful morning, but I'm gonna get into his zen mode, I think, and thank you for being so patient with me. Oh my pleasure. And once you start getting into your scientific passion, you'll get into the flow state. I'm sure, yes, you know you study testosterone, but you but more broadly evolutionary biology.

My gosh, can you explain to our audience a little bit about what that field is and how you got into it? Wow? Okay, that's a big question. So I think I can start with how I got into it, and it was I'd say organically. It's easier to understand. I think in retrospect, just thinking back on my own interests and how they developed. I think I've always been interested in people, and you know that's to me that

just sounds so obvious. Of course people are interesting, but like I'm married to someone, for instance, who really doesn't share my interest in human psychology and just kind of figuring out why people behave the way that they behave. You know, that's just always been natural for me. But really not everyone, as you I'm sure no shares that interest. A lot of people are more interested in things or numbers or something like that. So I just realized that

I've always been interested in how people work. And in college, I majored in psychology, and it wasn't until my senior year in college when I learned for the you know, I learned for the first time. I'll start crying at some point, Like talking about this always makes me tear up because it was so so exciting for me to learn about the brain and to learn about neurot transmitters. You know, it's so funny that I get emotional talking

about it, but I'll never forget that moment. And I wrote about that in my book, that moment and how transformative it was for me, because this was in my senior year. I had taken psychology. I had found it interesting, but I hadn't realized what I was missing until I learned about the brain. Until I learned about neurochemistry and like neurons and how they worked, and drugs that can affect behavior. And that is when I really became passionate

about learning more. You know, I was a senior, but I took a lot of classes and read a lot of books after I graduated. That's when I became passionate about really trying to understand the biological basis of human behavior, and sort of then I took I traveled, I read a lot of books, I took a lot of classes. And I hadn't taken molecular biology before, I hadn't taken genetics, so I took those classes and traveled all over the world.

So it was this combination of learning about evolution and genes and mutations and seeing so many different ecological and cultural environments across the globe that got me really curious about the commonalities between humans, what we all share, These like deep commonalities like sociality and trust and competition and aggression and sexuality. But then all these differences across cultures, like difference and religions and rights of women in different countries.

And that is what ultimately got me interested in sort of hooked on evolution and understanding how evolutionary pressures over time have shaped human nature in a sense, not just humans, but non human animals too, And I became really interested in that how evolution shapes these sort of common behaviors between humans and between humans and non human animals, and then also what accounts for the differences ultimately just quit my job and applied to Harvard to graduate school to

study something about the evolution of human behavior. And I got rejected, and I persisted, and I had no right to persist because I didn't really have the qualifications, and I eventually got offered a job to work in Uganda studying chimps and running this chimpanzee field research site in

western Uganda and in the jungle. Basically, that is what got me interested in sex differences and understand the biological basis of sex differences, because I was with the chimps that don't have human culture, and I was really struck at that point by you know, I had obviously noticed human sex differences, but to see very similar differences in chimps in the jungle with no human culture, that really got me more focused curiosity on what we share with

non human animals that can help explain male female differences. And that's what got me hooked on testosterone. So and that really, to me is what evolutionary biology is about. It's understanding how evolutionary processes can help to explain the phenotype, that is the physical and behavioral aspects of organisms. And in this case, you know, mammals and then humans in particular, and then just throw in human culture. That's a whole, big piece of the human environment that makes us really

fascinating and different from other animals in important ways. But it's a it's a framework that we can use to understand why we are the way we are, not just how we work. Like what's going on in the brain. Why do I like good and plenty, which no one seems to know what that is anymore anyway? Why do I like certain kinds? Why do I like candy? You know, because it tastes good? Right, There are receptors on my tongue that communicate with my brain and make me motivated

to get more. Right, So that's one kind of an explanation. But another kind of explanation is an ultimate explanation, is a evolutionary explanation. I am this way because it's been reproductively beneficial to my ancestors over human evolutionary history, and that's all answer. Yeah, that's evolutionary biology to me. Yeah, evolutionary biology. Yeah, either reproduction or survival sort of in

the ultimate explanation point of view. But you know, psychology is so interested in the proximal, and you probably jump back and forth between different levels of analysis. Oh yeah, and hormones, you know, really are about what's going on in your body right now. But when I'm really I'm interested in both. If I'm fascinated by how that stem works, but then why it works the way it does. There's a lot in what you just said. Let me go back to your dissertation work. Did you were you in

the Kabel Forest? Is that where you were in Uganda? Oh? Kibali? Yeah, so that the Kibali National Park. But I thought you were going to. The dissertation was actually with Steve Costlin, And I noticed that you have worked with you were supervised by Sternberg, Is that correct? Yes? And Jeremy Gray and you know you're not making that up. You're not making that up. And Jeremy Gray and the neuroscience of intelligence. Yeah, okay, So there's some overlap there because that my dissertation was

really about was mental rotation. Oh my mental rotation into Scots grown and evolution. So I was very interested in his work in terms of problems how we solve idea that for multiple Costlin was very good friends with Jeremy Gray. Yeah, multiple steps and discrete processes that are involved in solving any complex problem. And when you have when you give someone a test, you get one outcome. You're good at

this or you're bad at this. But what I really came to understand, partly due to your advisor's work, is that, well, no, you know what, if there's if there are a male female differences in test scores, that difference can derive from differences in any of the processes that are involved in complex problem solving. So we can't necessarily make a judgment that, you know, X group is better than why group unless we have unless we understand exactly what we're measuring. That's very,

very interesting. There's a little known fact about me, and that's that my first ever peer reviewed published paper, scientific paper I wrote like a review that I believe was published first, But I mean, my first ever scientific paper was in the journal Intelligence and it was on sex differences in mental rotation ability, which I did. Oh what, that's my whole master's thesis at the University of Cambridge in the biology. I was in the biology the Department

of Experimental Psychology at Cambridge University. Nicholas Macintosh was my advisor and he had studied this topic two thousand and six. Okay, I got my PhD in four which is which is probably why I didn't come across that. My whole master's thesis was accounting for this, yeah, three D mental rotation and trying to explain it through mediating variables, which I did. So can I just tell the audience what we're talking about? Yeah? Please do? I stumbled onto mental rotation. Initially I thought

I would do something with chimps. Somehow I stumbled onto mental rotation because it is the largest sex difference in human cognition. So that means in the way that people think and solve problems and navigate their world. And I didn't know what mental rotation was, and it sounded totally boring, and in a lot of ways it is totally boring because I think we don't and I'll just say what it is. This is my hairskin and nails vitamin, which

I have on my desk for some reason. But if I were to ask you to imagine what this looked like if I turned it upside down, why don't you go you people at home, go ahead and do that, those who are watching the YouTube video, what would these letters look like? Okay? If this bottle were upside down right. So in order to solve that problem, what's interesting is

in your brain. Instead of just regenerating the image at this like this right upside down, instead of just creating a new image, what you probably all did is go boo boo boo boo boo boo boo boo boo boo boop one hundred and eighty degrees. You rotated it in your head. And when you rotated it, you relied on the same neural architecture that you would use to reach out and do what I just did. Boo boo boo boo boo boo boop. So there's this relationship between physical

rotation of objects and mental rotation of objects. And you would take longer to answer a question about what this looked like at one hundred and eighty degrees than you would if I just ask you to imagine it like this right. And so the degrees that you have to rotate it predicts how long you would take to answer a question about what it would look like at a different angle. So this turns out to be a super important aspect of cognition, and we use it in all

kinds of other problem solving areas. So this would be opposed to something like verbal verbal cognition or other ways of solving problems. About Scott, you give me you're the intelligence guy and this has been so long for me. Yeah, give me some other kind of vocabulary? How would you explain? Of course, the you know a Nike you test is the Shmorgus sport of things include the vocabulary and now analogical thinking. You know, there's verbal things with verbal content,

things nonverbal content. There's like within the spatial demean there's different kinds of tasks. It seems like on average, the sex difference is largest in three D mental rotation, having to mentally rotate like a three dimensional cube that you're looking at, as opposed to a two dimensional mental rotation. That's then that's what I wanted to really understand in my dissertation was why what is so? Yes, I wanted a double click on the largest sex difference and really

understand what what's going on there? Now? Did you look at sex differences in your in your dissertation work? Oh yeah, yeah, that's what it was on entirely and and related to But we used the Shepherd and mets me too. Yeah. I used the shep okay, so I would I want to say to everybody, and I think this is super important that this test of the largest sex difference there is in the way we think, which is in imagining rotating three dimensional objects. And you have to say, in

this task, this cognitive task. You know people are always taking tests right with where you get one score, you're supposed to say, Okay, if I rotate two of these in different ways, can you imagine whether they're the same or different objects. I'm not doing a good job describing it, but you have to imagine rotating one object so that it would match another object, and then you have to

say whether it's the same or different. And these are paper, usually paper and pencil tasks that psychology departments all over mostly the country but also the world hand out to hundreds of people and consistently boys and men blow away girls and women. For the most part. This is to say nothing about the cause of this difference. It could be the large environmental or cultural contributions to this difference. So there's this is where we find this huge difference.

But if you give people any other kind of test, like the one where that's not just paper and a pencil test, but different tests of this aspect of cognition you typically get a lower sex different a smaller sex difference. Researchers want to get a big, interesting difference group difference so that they can publish their papers and they can say, look, we found that this. You know, we have replicated this large sex difference, and there's a big question about this.

So this is an effect where people keep using the same test, the Shepherd and Mesler paper and pencil test, because it yields I think partly because it yields this large sex difference, but we used a more complex computerized test where you get you get the slope in addition to the interception. You can analyze them separately. But anyway, the point is when you hear a report of a large sex difference, you have no idea what where the difference is located. It could be that in the encoding

of the objects, the sexes are different. Males might be better at encoding, males might be better in making a decision. And that's what I came to believe that it's that wasn't I didn't find evidence for the cognitive skill in terms of the actual rotation, but I did find evidence for men being faster and more accurate in terms of decide making a decision about difference, that they're more apt to say these two things are different. Women are more

apt to say these two things are the same. It doesn't mean that men aren't better at this, It's just that I didn't find it in my research, and I think there are interesting reasons why. On this particular test that everybody uses, which is the basis of this claim that men are so much better than women at this test, I think a lot of it has to do with the test itself, wow, rather than some basic inherent difference,

which there may very well be one. I think there probably is, but I don't think that this test is totally capturing the actual rotation difference and ability to rotate objects, which I'll just give an example in case people are still wondering why we're talking about this. If you go to pack your trunk and you have suitcases, and you know, square ones, rectangular ones, and you have to figure you have to look at the objects and figure out how

to move them. You imagine how you can pack them efficiently into your trunk, and you might not even know that you're doing that. You might not even know that you are looking at your luggage and imagining how to move it and turn things so that it most efficiently and neatly fits into your truck. That's mental rotation. And so these are skills that we use all the time

that we don't even recognize, but they help us survive. Ultimately, Yeah, you don't have to pack your truck to survive, but that's an example that people kind of relate to you. I do want to use this as a segue to talk about testosterone. Now. I do remember when I was I did my literature review back in two thousand and five for my master's thesis on this, I had a whole section on the role of testosterone, especially prenatal testosterone, on this three D mental ability. You know, you said, well,

you know, no one's saying anything about the cause. It could be environmental, but we do have data showing that there is a pretty strong contribution of even prenatal testosterone on this sex difference. Let's zoom out for a second now and just talk a little bit about what is testosterone. Well, it is testosterone in what ways? Does it matter? How far reaching is this are we talking here? We just talking three D mental rotation or are we talking other

things as well. I'm glad you actually brought up the idea that it might be related to cognition. So even though I did my dissertation on sex differences, testosterone and cognition, I left that out of my book, which is on testosterone and sex differences. The reason I left that out is because I don't think the evidence in that domain is as convincing as the evidence for testosterones effects on

sexual competitive and aggressive behavior. So if that's where I think the really strong evidence is for an impact of like you said, pre and directly postnatal testosterone and then pubertal and beyond, and how that explains some of the sex differences that we see many many of the sex differences that we see in human So and then we

can come back to that. But the part of the reason that the relationship to cognition I think is more tenuous, at least in the literature in the research that we have available, is because it's just not obvious how say testosterone, If testosterone increased mental rotation ability, what is the mechanism through which that would have provided a reproductive advantage for males.

So that's a little bit difficult. You can come up with a story, but I'm not convinced by really any of those stories in terms of direct and strong reproductive advantages like you have for male male aggression. So the reason this matters is because testosterone is a reproductive hormone. And I'm just gonna back up just so everyone has an idea what a hormone is. Okay, here I am

with my keembucha, which I love. There's some carbohydrates in that, and in order for my body to be able to process and use the glucose from the carbohydrates, I just drink so very soon the fact that I just ingested carbohydrates which will be converted into glucose, that glucose is going to signal my pancreas and tell it that there is now glucose coming into my blood and that will

need to be taken up by cells. So I don't have high blood sugar, which can cause problems, but also my cells might need some glucose to keep running, which they do. They run on glucose largely. So in response, my pancreas is going to secrete insulin. That is a hormone. It's a protein hormone, and Insulin will then go around to the cells that need glucose signal to those cells that glucose is available and should be taken up by

those cells. And it does that signaling by interacting with a receptor that is present in this case for protein hormones on the cell surface. So insulin's going to tell those cells that glucose is in my blood. It's going to open up a little portal, and then glucose can flow into cells to be stored or used for energy. So that is a hormone that helps us survive, It

helps us run our bodies, and it regulates energy availability. Essentially, Insulin is incredibly important hormone and it goes everywhere in the blood. Okay. So all hormones are broadcast from cells that produce them or glands that have lots of cells that produce them produce them, like the pancreas or the testes or the gonads or the adrenal gland or the thyroid. All the hormones go everywhere in the blood, but they only affect cells that have receptor for them, Okay. So

insulin is about energy regulation. It does all this stuff in the body, but it also goes into the brain, and it does something very different in the brain. It signals about what the energyergy situation is in the rest of the body. Why does it do that because you have to know how to behave when blood sugar is low. How does that work? You're hungry or you're irritable because you need sugar and you have that like sugar low.

And so the same hormone that controls some really important physiological processes also communicates to the brain to tell it what the energy situation is to affect behavior in ways that we don't really appreciate. But that's what Hunger is a response to hormonal signals. So that same hormone is coordinating physical energy with behaviors needed to also regulate energy like get more or go spend it by looking for

a mate or playing or whatever. Okay, So then we have hormones that are not about survival but are about reproduction, getting us to reproduce, and those are the steroid hormones, particularly estrogen and testosterone, made mostly from the ovaries and the testes, and their whole job is much sort of longer term. So like neurotransmitters and hormones like insulin work much more quickly, right, They have acts sort of on

off actions. Especially neurotransmitters are like that. Protein hormones are a little bit slower, but steroid hormones can coordinate puberty, you know, so they can have really long term actions on growth, on sperm and egg production, and like you mentioned, in utero, they have incredibly important functions in developing the reproductive system. Right, So the whole all of our reproductive

apparatus is set down essentially in utero. But at the same time, testosterone is active in the brain in the same kind of way that insulin affects the brain and body. Testosterone and estrogen, but estrogen not so much in utero.

It's mainly testosterone that affects the brain and body in boys in utero, coordinating the development of the brain with the development of a male reproductive system, which means sperm are going to be coming online in puberty, and organisms that produce sperm have to do different things to reproduce than organisms that produce eggs. And is testosterone that coordinates the physical end behavioral traits that enable male animals to reproduce,

and that happens in utero, and that's very important. Those in utero effects on the brain are permanent. They can shape various behaviors in adulthood, even if that animal doesn't go through mail puberty. But those animals are you know,

we can just talk about mammals for now. We'll go through a male puberty when testosterone rises again, and that's when testosterone further develops the reproductive system and acts on the brain to upregulate status, consciousness, competitiveness, aggression, eventually libido. That all comes online later and especially sperms start being made.

So that's what testosterone does. And in the same way, it acts on the body and you know secondary sex characteristics like a deep voice or larger body size, enhanced muscle mass. That's all because males over evolutionary history compared to females, benefit more from male from competition for mates because they produce sperm. And that's on average. Everything I say about sex differences is on average, meaning there's plenty of overlap in these grates. Wonderful. Thank you for that

wonderful primer. For people who miss biology classes, I think that that will be really helpful for them. Let's have a conversation, you know, more of like you know, back and forth because This is so fascinating to me. I have so many questions. It's so cool, and we should make clear as you said, uh, you know, we're talking about on average, and there's also other things that are important to recognize, Like these things can fluctually throughout the day,

within a there's within person variability as well. There's across the life span. You know, as as as people get older, testosterone levels tend to decrease, especially you know among male narcissists. Research I've shown that to be the case that it actually tracks reduced reductions and narcisism tracks reductions intotosterone is

male's age. I think that's really interesting. What's also super interesting about this is that there are other There are other hormones, there are other neurochemicals, and interactions are fascinating, right, So like you know, how does testosterone like interact with the cuddle hormone? Right? You know, the yeah, how do these things interact? Because you can have really like high t men and women who also are super compassionate, right and want to and uh and want to reduce the suffering.

We could fire firemen, you know, like you know, they're probably wild have jacked up on just austereroone, but they want to go in and save lives. So interactions between these various things are so interesting too, right, Yeah, no, I'm glad you mentioned that. So men do take more physical risks than women, but it's not all negative. It's not all risks like killing each other or you know,

behaving violently. Like you said, those risks are also to save the lives of others, So men are you know, I think it's I want to make clear that women also do this. Women also risk their lives to save the lives of others, but it's much more often their own family, their own children. Men are much more likely to die saving strangers. You know. There's an incredible amount

of heroism that physical heroism. And yes, women have babies and that is physically risky and dangerous, but I sort of it's not the same kind of physical risk taking that is sort of totally by choice in order to save someone else. So I just want to emphasize how important that is because testosterone gets a lot of press, partly because, as I do argue in my book, I do think it's it's largely responsible for the extremes that

are really problematic of male violence. Which you know, there's very low rates of that type of violence in women, but there's higher rates in men. That doesn't mean that most men are very violent. It means that most extreme violence is committed by men, and that needs to be addressed. So that is why that gets a lot of attention. What gets less attention are the positive aspects of what testosterone I think can do for men interacting of course

with our culture. This is all culture gene hormone interactions. That's incredibly important, and I'm just going to throw out that. You know, some cultures have very low rates of male violence relatively, and some have very high and that's because of culture, not because of differences in genes or testosterone level. You said, any sort of cultural differences are explained entirely based on culture, not on testosterone differences on average. Is

that is that one hundred percent true? Maybe one hundred percent true. It's not a hundred It has not it's not one hundred percent proven, because I think what you're getting at is the fact that different populations do have differences in both testosterone level, but more importantly, the activity of the testosterone receptor. So, like I was saying before, in order for a hormone to work, it has to interact with a receptor. The receptor is a protein, and

there is a gene for all hormone receptor. There's different genes that code for all of the hormone receptors. So the androgen receptor is coded for by the androgen receptor gene. And we can look across populations and it's very clear now these are basically racial slash ethnic differences in the

gene that codes for the androgen receptors. Are there differences, yes, so there are differences, wow, where so there are differences, But the cultural differences, in my view, cannot all the cultural differences cannot be a product of genetic differences, because you can have different laws and cultural norms and religions in very geographically closely related areas, and you see the cultural norms apparently having an effect on rates of male violence.

So if you have very strict rape laws in one country and very loose, say rape laws or norms in another, and those countries are geographically very closely related, where you would not expect there to be any you know, it's basically two Asian countries. Say, you will see differences in the degree of a sex difference, say in violence, because if a sex difference in violence is narrow, it's because males are doing less, it's not because females are doing more.

So all the variation, pretty much in the sex differences in aggression or anything else that has to do with physical that kind of physical risk taking is due to male variation, which is, as far as I can tell, a function of cultural norms for the most part. If you want to look in different continents, you know, I'm not sure you could make that same claim. But that's an area I don't even want really to venture into,

because you know, it's dangerous. Like I don't think the bang for the buck in terms of what we learn is worth it, right, And we obviously do not need to harp on this. It is a very very explosive topic. I mean, imagine the topic of the same the same discussion in terms of intelligence. Right. It seems like you're also saying there just doesn't even seem to be a lot of It's just like that scientific knowledge doesn't seem to be something that would be worth doing or conducting

or or well. No, I wouldn't say I don't I wouldn't say that what I am saying is that most of the variation in male violence, as far as I can tell, is best explained by cultural norms. Those cultural norms may be a product to some degree or related to those genetic differences. Those genetic differences, Yeah, that's possible. However, we have the power to change the cultural norms regardless

of the genetic contribution. I understand that that that's what you want to that's the point you want to highlight, and I think that's a very very important point. Yes, I do think that's a very very important point. And culture seems to be at pretty much everything because I don't think those differences are big enough to explain the

the huge differences we have in male violence across societies. So, yes, I hear everything you're saying, but it just stuff gets so tricky when we start talking about like should trans women be able to compete in certain sports men's sports.

So these are really tricky questions because in some ways you are saying, regardless of culture, like are holding culture constant, there are real effects of testosterone, especially if you're a natal male, right and you lived your whole life, you know, went through puberty naturally, and that there are real effects of testosterone that no matter what you do with cult, I'm kind playing Devil's advocate with you for a second if you see what I'm saying, because it's almost like

there's the issue of trans women in sports and the degree to which the physical advantages that natal males have over natal females translate into a cultural In this case, it's a you know, sports like, well, it's not entirely a cultural advantage, but would translate into some serious, physical, meaningful difference that plays out in culture in a formalized competition. Right, I'm just trying to make the link between the previous

conversation and this conversation. So there are real physical differences that matter. That's my questions. Are stronger and faster and larger than women, like, no question, and that is all due to testosterone. Like even if there weren't, even if men didn't you know, spend more time lifting weights in the gym, they would still be bigger, stronger, and faster.

I'm bigger, stronger, and faster than some males. So this is again, this is on average, and in elite sports that's where this really plays out because everybody is working out as hard as they can, even with say, in Cambridge, Massachusetts, where I live, most men are bigger and stronger than

most women. If the law in Cambridge we're so severe that you know, if there was if there were evidence of sexual assault, if the man is going to go to jail, you know, for twenty years, then you would very quickly see that that physical advantage would become much less meaningful. Right, So it's the interaction of the genes, the hormones, and the culture that is extremely important there.

So I would just argue that culture holds the key to leveling out those differences when they disadvantage people socially. But in sports, the whole point is to have an advantage over other people, and that is downed and that is encouraged. That's what everybody's trying to do. And that's where then we have to determine, well, what exactly is

the source of the advantage. Is there anything we can do about it to accommodate trans women in particular, source of the advantage I believe is clear or that's testosterone, But people argue about that. I don't know why. It's totally obvious if you look at the science. So the question then is what do you do about it culturally, So it's the same kind of question. Do you have an answer? Like, do you have do you do? What do you think is the most reasonable thing to do

as a society? Have you do you have a stance on it? I do, Okay, I'd love to hear yeah. I have a strong, strong stance, and I get very emotional about this. I'd love to hear it. The stance is, let sorry, I have like a personal situation. It puts some personal involvement in this situation because this is so controversial. My stance is, let people do the research they need to do, publish the relevant research, give people grants for the relevant research, stop stigmatizing people for trying to talk

about the evidence and weigh the evidence. Promote academic freedom and freedom of speech, and let people have the facts and let them discuss their points of view without shame or censor. That's my I almost don't and people will get mad at me for this. I don't really care that much about the actual outcome and sports. What I care about is that in a democracy, people have the right to weigh in on these policy decisions in a way that gives everybody a voice and access to the facts.

And we do not have that now. So it's hard to come up with a solution because people are afraid to speak, you know, people are afraid their careers are

going to be ruined, they'll be socially ostracized. So while I am firm and clear that trans women have an advantage over natal women on average because they went through male puberty, they are still bigger and stronger even after they block testosterone and start taking estrogen after one year, after two years, they still have significantly increased muscle mass. They still have increased body size, longer arms, they have,

the height, they have, the larger heart, larger lungs. Hemoglobin does go down and that makes a difference, and their performance will decline, you know, after blocking testosterone, but not enough to remove the advantages that they gained from going through mail puberty. What you do about that, I have no expertise there. I have the expertise in the fact

and the scientific facts. Some people think there should be an open category for there should be an open category where anyone can compete, So that would basically be the women's category. Sorry sorry, that would be what we had thought of as the men's category, and that the female category would be protected to include only natal females who had gone through their natal puberty, and that that would be the protected category, and then everyone else can compete

in an open category. It was like an all all gender category like bathrooms. Yeah. Yeah, however you identify whatever hormones, there's an open category. But then there's a protected category for natal females because they are a relative physical disadvantage relative to the other categories. But the point is people need to be able to have the conversations and be heard.

Everyone you know has different and I think very valid experiences and needs and perspectives, and we should respect people's perspectives and try to understand them and have a conversation, have conversations, and then everyone else can figure out what to do. But they need the fact, they need the facts. Yeah, and I love that you're taking a very scientific approach to this and trying to just at least have that

inform the discussion. I really do appreciate that. So, just so people are very clear, you have found very clearly that all other things being equal, people who have experienced male typical levels of testosteronen during puberty will have an athletic advantage over those who did not for much of their adult lives. I mean, that's a scientific fact, right, yeah.

And this is not my original research. This is research other people have done, like Emma Hilton, Tommy Lundberg, and there's a lot of people who are getting into this now. But that's the evidence we have. We just have no you know, and you can question that evidence, but we have no evidence showing that that initial advantage is lost. We have tons of evidence that shows exactly why men outperform women. What we need more of is evidence that

shows exactly what happens when you block testosterone. And that's what trans women would do. For those of those who want to transition with hormones, they would block testosterone and take estrogen, and you would expect that there'd be some decline in performance, and there is some decline, but we

need more research there, and we need some research. I think if people wanted to argue that trans women should compete in the female category, and they would argue that that should be fair in terms of physical ability, then we would need research that shows that the typical male advantage is lost, and that we don't have and we will never have. In my view, this stuff is even further complicated by the unknowns. There are a lot of unknowns I think admitting that you know, in science on

this topic, a lot more research needs to be done. Additionally, on the potential adverse side effects of taking testosterone blockers. Is it true that there could be some potential long term adverse consequences that people are not they're not thinking, They're only thinking about it from an athletic perspective, But then they realize some day they're they're sterile, right, or they realize some day aren't. Aren't there certain things that could it could lead to that would cause someone to

maybe regret making some of those decisions. So this is a really big issue, really important issue right now. So there are a lot of people, a lot of families, a lot of young people who have gender dysphoria, who are very uncomfortable in their sex to bodies, and there are good reasons for that. You know, we live in a very gendered culture and gender nonconformity, which is just behaving in a way sometimes since you were little, in a way that is not consistent with the expected norms

for your society, for your gender. This can be very uncomfortable for people who feel that they want that their behavior is more consistent with the opposite. So that can lead to something like gender dysphoria. And now what a lot is happening with increasing frequency, dramatically increasing frequency, is people are identifying as transgender people who have gender dysphoria instead of progressing through their natal puberty, which to many

of those people is a horrifying prospect. Like if you are male but you feel somehow that you identify more with females, if you start getting a deep voice and growing a beard, that can be really really distressing. Puberty blockers are a drug essentially that blocks the signal from the brain that stimulates hormone production from the testes and

ovaries and prevents puberty from commencing. So for more and more people with gender dysphoria, they're identifying as trans and they are being put on puberty blockers because the narrative here in this country, and this is changing now in Europe, especially like Sweden and Finland and the UK. It's a different situation there now they realize that puberty blockers have a lot of very serious and irreversible effects. And this is for children we're talking about, so before eighteen or

even before puberty has started. But here the narrative is that you can just go on puberty blockers and prevent this painful process that you anticipate, and that's going to

give you time to work out your gender identity. But the evidence shows that almost everybody who goes on to puberty, who goes on puberty blockers, and this would be at the start of puberty around eleven, twelve thirteen, almost everyone who goes on to puberty blockers, like almost one hundred percent, ninety five to one hundred percent of those people continue on to going to cross sex hormones, meaning if they're male, they will block testosterone and take estrogen and go through

an estrogenic puberty, and if they're female, they would take testosterone and develop male some male secondary sex characteristics. But doing that prevents the development of the reproductive system, so that the eggs and sper will never be produced and those people will be infertile for the rest of their forever. Wait, they're definitely going to be infertile. You take sperm, if you don't go through male puberty, you can't make eggs. If you don't go through female puberty, neither can you

have full sexual function. Many, if not most, are an orgasmic. That means they won't have orgasms, they won't have kids. But these people who are making the decision have never had an orgasm, don't you know, They're in pain, like they are making a decision out of feeling sometimes you know, extremely depressed and scared. But we also have evidence that shows that if people are allowed to progress through their

natal puberty, they most of them discover they're gay. And these are you know, if they've been gender atypical since childhood, most of those will discover that they're gay, and this may be a painful process, especially if they're in a region of the world or the country that's homophobic. Some parents actually would prefer to have to transition their kid

then have a gay kid. So this is really really complex and what needs to happen again, just like the trans women and sports thing, is that the evidence, like, we can't have conversations that are open and clear about this either, because the narrative is that if you don't affirm, it's even called gender affirming care, right, that's not really an evidence based way of thinking about this. They're kid's gender.

We don't even know what gender really is. Exactly, and people's sexuality and sense of their own gender changes over time and changes through puberty, so if you block that, you don't ever allow a child to have the change in their psychology. Also, that comes with discovering their sexual human being who might be attracted to their own sex. So it's extremely complicated. Parents are scared because the narrative is that your kid will commit suicide if you don't

affirm their gender. There isn't good evidence for that at all, and it's highly politicized unfortunately, like one view, you know, it's progressive, and one view is conservative, and that's too bad because what we need is an evidence based view. Yeah, well, evidence informed view. I definitely am on board with. I don't think it can one hundred percent make the decisions for individuals, but to be informed by that. I was under the impression that gender affirming care is a wide

range of services. It's like just like you go in and you're like, let's explore what's going on here, and let's figure out as a team what might be the best solution. It doesn't. It's not equivalent to you're going to take purerity blockers, right. It could be psychological aspects like even so, for instance, maybe just changing your pronoun might actually be very psychologically beneficial to some of these people.

Well it has been shown in their personal experience. Yes, no, and that's that's true, that these short term outcomes can be positive. But changing changing pronouns and identifying socially as the opposite sex and starting to wear the clothes of the opposite sex leads to purity blockers and transition. So because you sort of can't go back, it's difficult to go back on socially you've come out as I am

trans So what you're saying is pronouns are a gateway drug. Yeah, I mean, I wish we could live in a society where you have your own pronouns that reflect your sex, but that there are the you know in this who knows where we're going. But if I, for instance, could just wear a tie and a baseball cap or you know whatever and have a very male masculine social role, or that you could wear makeup and just do express your gender however you want. I wish that's where we're going.

And maybe we are going there because a lifetime of surgery and drugs and complications, which is what we have, you know, it's age people I don't think understand quite what they're signing up for. That doesn't mean it isn't right for some people. I think it definitely, you know, transitioning definitely is. I think that we need more caution. Some people argue we have the right amount of caution. Some people think that we have nowhere near enough. But again,

I think we need more research and discussion. We definitely need more research, and I appreciate you bringing in the research. I think we need less moral panics as well. I think that you see it on all sides though. You know, again, it's been my understanding with jenniferming Care from what I've understood so far is that there are actually a lot, a lot of hoops you have to jump through in order to actually go to the level of taking like

purity blockers or so. That's that's my impression. That's what I hear from trans people. It's very variables. I mean, there are really responsible clinics, and there are clinics where you can really yeah, and there's surgeries, you know, there's st ectomies that easily can be done even without parental consent. Yes, and it varies varies a lot, so the United States is now somewhat behind Europe in terms of the laws

around this and the evidence. That's the sort of there's much more caution around puberty blockers now in a lot of places in Europe because they have now been because they have more public healthcare system that are now more evidence based. We have a for profit healthcare you know, entirely for profit health care, largely for profit healthcare system. They are different standards for evidence, and I think that's important. Yeah, they're just more cautious, I would say, Okay, so that's

a good point too. So there's a huge variability and just how many hoops and how well thought through it is, how well as a team of medical doctors, parents, you know, everyone trying and the child at triangulating the decision. Yeah, I mean, I think the problem here is that medical professionals who disagree with the current treatment model are very hesitant to say so publicly that we vilified. Yeah, it's

they're really lammed and their careers can be ruined. So I don't think we have an environment that facilitates really the production and discussion of really high quality evidence around all this stuff. And we just don't have enough research that's interesting, the complementary perspectives between the evolutionary biology perspective

and the psychology perspective. It's almost like evolutionary biology is really important in explaining the sex binary, which I know is that's controversial too, is sex and the sex binary? Dare I say, am I allowed to say from an evolutionary point of view? Of course it has to be or else none of us would exist. That's very controversy. Yeah, yeah, I know, I know. And of course intersex intersex people

do exist, but they usually they can be classified. You know, it's either male or female, right, yeah, I mean intersex is it is a tough term. Some people don't like that term. They like disorder or difference of sexual development. That are you know, as a male condition or a female condition. Where there's so just to be clear, yeah,

there's male and female. But then everything else pretty much is on a spectrum, even you know, chromosomes and genitalia and behavior obviously, so something like gender, all the behaviors, but also even the physical traits are you know, can be on a spectrum. Those are important aspects of sex. Those are traits associated with sex, but that's different from sex male and female and that's all there is. So that's what I'm saying. From that, there's there are different

levels of analysis. So from from an evolution of biology perspective, that focus on sex is makes a lot of sense. And reproduction, I mean, obviously from an evolutionary point of view,

reproduction is important. But from the psychology perspective, and I'm really trying to understand gender, right like, I'm not an evolutionary biologist, you know, a psychologist trying to understand this fascinating cultural phenomenon of such a we're seeing an interesting flip There used to be mostly it was transgender men cross stressors, right like, and now trans women. I'm time getting confusing. Yeah, please help me over here. Okay, more men,

say for males who identified as trans than females. Now we have a huge flip rise in females who are not have not had evidence of any gender atypical behavior or feelings until they got close to puberty. That's the population we're really seeing now, which is escalating and asking for puberty blockers and hormones. Males are too, and most

of them are probably we're going to be gay. This is what's interesting is that there are multiple pathways to trans there's not a single unitary mechanism, and people don't know. I know, it gets very confusing. This is why when you lump it all together, you know, because you have like middle aged men, you know, like Caitlyn Jenner or not? Is that? Who was what Jener? Was it Caitlyn Jenner. You can have middle aged men decide just that they're

gonna they're gonna be changed their pronouns. But you can have pre pubescent children now who it seems to be mostly young girls. But so these all can't be explained by the same mechanism. Yes, can I just pause for one second because what you're saying is so so important because people have this idea that we just have to identify those kids who are trans and those are the

ones we have to give the treatment to. I don't think there is a trans one trans phenotype, and that it's not the case that then that kid is the one who has to be transitioned. It's about gender dysphoria. It's about that really complicated feeling of not like not wanting to be in your gendered body, not wanting it, not wanting to grow into a man or a woman, fearing you know, not wanting to be behave and the way that you think the social your social expectations are

for your gender, just feeling so uncomfortable. So that's not the same as trans. So I'm just really glad that you made that distinction. Most people do not. Yeah, why do most people like in this debate, they're like sometimes they talk past each other. I mean sometimes I look at and watch some of these debates on Twitter, and no one's listening to each other, like trans people who feel frustrated that their experience are not being listened to.

And then you also have those who are called turfs, those are labeled they're labeled turfs, But are there are their experiences being listened to by the trans people? No? I mean I think there are a lot of people who are listening to each other. I know some trans people who agree with the turfs, and I know some trans people who disagree with them, and they're able to have conversations. But then there's like this vocal minority on both sides who are dominating you know, these conversations in

kind of ugly ways. Is that because they're high in testosterone? I can help myself, But no, no no, no, no, you are there is something to that because this is controversial, but I believe that the prenatal exposure to testosterone, well I know one hundred percent that it does. It has lasting effects not just on the body but also on

the brain. And you can't you don't undo that. So yeah, there are some extremely outspoken trans women and trans men, but you don't really hear from the transmit it's it's I mean, you do, but it's really trans women. A small minority of trans women, mostly trans women, who are can be extremely enthusiastic. You know who Buck Angel is. Of course, Yes, he's going to be on my podcast soon with two other evolutions, two other scientists, and I'm going to have a coming on with Marco del Gus

who's a good friend of mine. Science studies, the science sex and Debra. So yeah, but he's a kind of a minority voice in that space. Yeah, I mean he is interesting because he says, I'm female, you know, he has no problem and he's a huge he's a huge, macho guy, like cigar smoking, tattooed, Harry, you know the works, which I think it's great that he is just able to not sort of require other people to endorse what

he says would be a fiction. You know that he is in fact a man, and I have no problem with that socially, Like, I think that's the right thing to do, is to for me, you know, use people's preferred pronouns. And I know a lot of trans people, and I know how heartbreaking it is for them when that doesn't happen. But Buck happens to be different. He's comfortable with that, and I think it's different for trans men. I think sometimes trans women have a greater need to

have people acknowledge their you know, womanhood. And I think as long as we can do that without anyone else paying a cost for that, I think we should. Yeah. I mean I'm all about letting listening to different people's lived experiences. I mean, that's that's Uh. It costs very little to say that you're going to listen to someone's lived experiences. That costs very little. It costs more to fight it and to be aggressive to human who when who's trying to tell you what it's like to be

who they are. I love it. I just said love what you're saying. I love. I love my spirit. That's my spirit costs very costs very little, and I'm like, you're getting teary eyed about it, but yeah, that's what we need to do. It's just you're right, it costs nothing. I love, I love putting it that way. I just wish we could all listen to each other more, and you know, with my yes en attitude listening each other's a live experiences more and be allowed to bring in

some objective objectivity. Are we allowed to do that at all? You know? And I know that you have probably sometimes been frustrated that you haven't really been able to bring in some facts that you have found. What's the climate like at Harvard these days? Is it? You know? Uh? You know, it wasn't EO. Wilson in your department. Okay, So I'm in Human evolutionary biology, and I should say that I'm on leave right now, so I don't know,

I haven't been there all semester. But EO. Wilson was in Organismic and Evolutionary Biology, which isn't like right across from my department, which is human evolutionary biology. But he yeah, he had water thrown on him for saying you know, he was usually controversialgu yeah, he was realified. Yeah, he was very controversial but of course everything he said was basically,

you know, basically right. But it's threatening to people to assert that there's a biological basis for behavior human behavior, because then people think that means that it's that we think it's right, or that we can't changeable and multi those. Yeah, yeah, absolutely. So what's your personal experience like being an evolutionary biologist in twenty twenty two. Is it different than being an evolutionary biologist in like two thousand and one? Maybe not,

maybe not. It's a human it's the human evolutionary biology piece, and particularly so I teach about the stuff we're talking about. And my undergrads are awesome. Do any of them? Do any of them like protest or no? They I've had like one person, one person a few years ago complained that I used the wrong pronouns to talk. I was talking about somebody with a disorder of sexual development who is female, and I called her she even though she had some she had body hair and looked male and

I called her she. And this person wrote a letter. But really, my undergrads, sorry, I love them. We have great discussions. We disagree all the time. They disagree with each other, they disagree with me. We always learn from each other. We we hear each other, and I have there that's been like incredible. Teaching undergrads at Harvard has

been incredible. However, I never changed anything I said or taught pretty much in any way to accommodate the people who I thought would try to attack me or call me names or transphobic or whatever. I never adopted you know, what they wanted me to say, or the language they wanted me to use, which is to say like sex isn't binary, it's on a spectrum, or I don't know what else I was expected to say, but it was uncomfortable. It became extremely uncomfortable in my department. There's an article

in the Harvard Crimson yesterday. You can just go look at that article on academic freedom, and it links to another Crimson article which described what happened to me when I went on TV and said there are two sexes. It was all very bad, and other bad things happened that made it very difficult for me to do my job. That's really unfortunate. I really wish that we could just be really clear in all these kinds of discussions that they're yes, we acknowledge the's are difference between sex and

gender identity. First of all, when people just say sex, they may think that's equivalent to gender, like in every case in the world, and gender identity is more of a psychological thing, you know, it's like there's we're still understanding exactly what it is, but it's certainly certainly people differ in what they identify with. That's undeniable. And it's so I wish just first of all, people to make

those differences. And I just I suppose maybe you say you've said things and then people do a lot of inference. They connect a lot of dots in terms of what you must think or what you must believe personally. Well, I don't even think that's the case. They just don't

want me to say that sex they've been clear. I mean, if it's clear that usual to say that sex is on a spectrum was not okay, or you know, I don't say this, But you can't change your sex, right, you can change a lot of other things, because I don't think people have to go around saying that, right, But that would be another thing that you're not allowed to say. So it's not connecting the dots, it's having someone in my position say something like that that seems

to undermine transgender rights. And to me, we've got to have the science and the facts and then talk about what are the implications for people's rights and policies, and we have to have compassionate and open discussions and listen to people. I so strongly agree with you. If we have all this division and this suppression of science, people aren't going to open their hearts and minds to people who are suffering who they think are opposing them, you know.

So it's all the science is getting all caught up in all this ideological stuff that is a disaster. The political, social, and ideological stuff has to grapple with the science, and we have to do it in is compassionate and open a way as possible with the facts. It's not just me, many people in my field are saying that they feel they cannot even publish the research that they want to do that they are doing. They can't get grants, they can't say what they want to say, they can't teach

what they want to teach. Do you think someday, like with crisper technologies, will be able to actually modify like our chromosomes, you know, like let's delete an next there. I mean, I don't know will you ever be able to get to a point do you think where we can actually go in at that level and change our sex. You'd have to change the chromosomes in every single cell to be So it's interesting because I think that it's really not the chromosome, it's what the chromosomes lead to,

which is testosterone versus estrogen. I think that's what really has the impact on everything related to sex. So we have good evidence for that in people who have complete androgen and sensitivity syndrome, who have xy sex chromosomes and all of their cells they even have internal testes that produce testosterone. However, they can't receive the testosterone. Their androgen

receptors don't work. And these people are extremely feminine typically, and research shows that they score lower in three dimensional rotation tasks. I summarize that in my master's thesis, and that's fascinating. So I would think if you can stop the production of testosterone in utero, it has to be from the get go, from the first few weeks, because that's what's changing, that changes the brain. And you also want to stop the physical development because even if you

didn't have testosterone. If you just had the body, you're gonna have changes in psychology because of social roles, so you might Yeah, I think maybe that could happen, but not via you know, necessarily manipulating the chromosomes. We just don't know how important the genetic differences are that you know, apart from the effects of testosterone, it appears not super but there's more research to be done there. Yeah, fair enough,

fair enough. Yeah, Look, I just really appreciate you coming to my podcast today and all the work that you do. I can say that testosterone is such a fascinating, fascinating hormone. Sometimes I wake up with the most loving feeling in the world and I want to just tweet out, may everyone cuddle today, and then I'll go to the gym and have a really great weightlifting session, and then all I want to do is dominate everyone that I see. So I know testosterol matters. I just got my book out.

This is the British this is the British cover, but it's the test Aser. I just want to give my book a place, very nice, very nice, thank you everyone by Carol Hooven's book. So for people who can't see the YouTube they're listening to it audio. The book is called Testostere. The book in the United States is called t The Story of Testosterone, the Hormone that Dominates and Divides Us, and you can get a link to it on Carolhoven dot com or Amazon and Carol has an

e on the end, which is a pain but great. Thanks. Thanks for being on my show today. I appreciate it. Thank you so much. I've really enjoyed this and I love your whole perspective on all of this. You're just so so compassionate and sensible, and I really appreciate it. Thank you. That means a lot. Thanks for listening to

this episode of The Psychology Podcast. If you'd like to react in some way to something you heard, I encourage you to join in the discussion at the Psychology podcast dot com or on our YouTube page the Psychology Podcast. We also put up some videos of some episodes on our YouTube page as well, so you'll want to check that out. Thanks for being such a great supporter of the show, and tune in next time for more mind, brain, behavior and creativity.