the program, tonight the charlie rose brain series three, episode three gender identity. >> it's unfortunate that society often considers transsexuality to be a mental illness or an immoral choice. and because of this transgender people are still often denied basic human rights they're often subject to violence. and in many states, transgender people can still be fired just for being transgener. but as we heard as we've heard today on this program the brain has innate circuits that determine our gender identity and so being transgender is not a choice that i made. but it's how i was born. >> certainly in our culture we have lots of stereotypes that there are gender differences and abilities. people believe that boys and men are better at math and that girls and women are

better at verbal skills. and that boys are better at spatial performance. so those are the stereotypes. now what does the real data show. the most recent data show actually that girls are tied with boys now in mathematical performance. >> rose: episode three of the charlie rose brain series three underwritten by the shown foundation coming up. funding for charlie rose is provided by american express. additional funding provided by: >> and by bloomberg, a provider of multimedia news and information services worldwide. captioning sponsored by rose communications from our studios in new york city, this is charlie rose.

>> rose: tonight we continue our exploration of the magnificent human brain with a look at gender identity and the biology of the brain gender identity is a person's subjective experience of their own gender. it may or may not correspond to the sex assigned to them at birth. the term transgender describes someone without feels his or her body and gender do not match. it is estimated that about 700,000 transgender people live in the united states. one of them joins me today to share his experience. ben barres is professor at an chair of near biology at standford, he lived at barra barres until he changed his sex to male in 1997. also a remarkable group of scien cyst norman spack of boston children's hospital catherine dulac of boston university melissa hines of the university of cambridge and janet hyde at the university of wisconsin at madison. i'm pleased to have all of them here and to begin this

conversation with my colleague eric kandel. what are we going to talk about? >> we're going to speak about gender identity and the biology of the brain. this is a marvelous topic. and i like it in particular because it shows how brain science can be a liberating influence in our life. as we understand the biology of our own gender identity better, and become more comfortable with ourselves we become more empathic to somebody else's gender identity. and we can understand if all of a sudden at age eight nine or ten a person says i'm in the wrong body. we really can sympathize with them and understand what is going on. but this is to the only an interesting topic it's an unbelievably timely topic. when you and i first began talking about this six months ago it was not on the radar screen. we were ahead of our time. and but now but now you can't pick up an issue of "the new york times" or "vanity fair" without having

a discussion of gender identity. >> rose: and 17 million people watched the diane sawyer interview. >> an what we can bring it bear on the subject is not only a deep discussion on what the psychological and socio logical issues are but what the biological underinapproximatings are. when we begin to speak of the biological underpinnings we want to speak speak about what you already implied two topics anatomic sex and gender identity. anatomic sex is the body parted associated with reproduction gender is that one centers themselves as a male, female or something else. let's begin with the anatomical sex. an tomorrowical sex is determined the sur prisingly by our genes genes are arranged in chromosomes and we have 23 pairs of chromosomes, we get half from our father one pair from our father and one pair from our mother. 22 of these are called

odozomes and the difference between the father and mother's contributions are real but they're modest. but the sex chromosome, the difference is really quite profound. women are xx and men are xy. the chromosomes are really quite different than the odozosomes and they have a important function in determining sex. let's begin with the y chromosome and see how that determines the sex of the male. we are born with an undiffer yented gofad that can move in either direction either developing into t testes or ovaries. if there is a y chromosome there it has a region in it which is called the sex determining region of yferx. that contains a gene that activates the differentiation of the undifferentiated gofad into the testes. if that y gene is not there

you have an xx you have a female gonad develop. an each of those has profound consequences. let's look at the male differentiation first the male testes. the testes develops within the first seven weeks in utero. and if the testes matures as a result of the sex determining region of y the testes reaches a massive a amount of testosterone comparable to the level you have at puberty and the adult. and that is responsible for giving you the male body form, the brain characteristic of male functioning, as well as having actions and sort of every aspect of your being. if this sex determining region of y is not there if you have xx you have development of of-- ovary it in turn secretes estrogen and progesterone and gives you the female body form and gives you changes in the brain. so clearly these are extremely important changes.

and that's the easy part. this is the anatomical part. the more subtle the more elaborate part is the gender identity. and that's why we brought together this spectacular group of people to talk about that. as you pointed out, we have been with ben a long-term colleague, a major scientist in my field in brain science, also in catherine's field. and he is chairman as you pointed out at the department of standford member of the national academy of science and he's a transgender person. he made a decision in the 40s to actually undergo a bodily change. and he it tell us what it was like before when he felt he was in the wrong body and how he feels now. he not only can tell us how you feels but interestingly enough since people knew him as a scientist before he underwent this change they can describe what it was like interacting with him as a woman and now interacting with him as a man. we have norman spack with us. he is one of the pioneers in

the united states of pediatric endocrinology who can help people make a decision as to whether or not they should go on with their idea that they're in the wrong body and actually lead to transformation. and he has adopted a european strategy and really applied it in the united states of postponing puberty so people can think through what they actually want to do. and make the decision in an intelligent and thoughtful fashion. and the reason he wants to delay puberty is once puberty forms, it's a much more radical procedure than if you proceed before puberty. >> we have katharine kath ran dulac an old friend here last time. she is interested in how sex is represented in the brain. and she has found in mice amazingly in the male mouse this representation of the female. and in the female this recommendation of the male. this is not a completely novell idea freud not working with mice but working with people suggested we are all

bi sexual and we develop that way in one aspect of the sexuality matures but the other one remains and we certainly fell and we have heard about it in parenting, you pointed this out, there are men female components and there are women male components even in adult life. we have with us melissa hines who is interested in how kids differ boys and girls and the games they play and how they interact with each other. and she's interested in how hormoneal levels affect child play and the games they get involved with. and we have janet hyde janet hyde is interested in seeing what are the differences in cognitive capabilities between men and women. in computer science in mathematics and engineering. and her data pretty much suggests that there is very little difference between them. but as i've gotten to know janet a little bit better, i

think that that is incorrect. the more i speak to her she majored in matt matics. i have come to the conclusion that women are superior in mathematics and engineers and computer science. anyway i think we're in for a fantastic program. >> rose: let me begin with ben. tell me the experience that you went through share with us as much as you can about what lead up to your decision how you carried forward and the impact it has had on your life. >> sure. i think in many ways my experience is probably typical for other transgendered people. i was, i think only about four or five years old when i first started to have strong feels that i felt more like a boy. i was born as a girl, barbara. but i felt like a boy. i played with little boys. i preferred boys toys. i remember dreadfully wishing i could be in the cub scouts and boy scouts. every halloween i would dress up as an army man or football player. this all just seemed very normal to me. i felt like a boy. but as i got into middle

school, early teen years i did start to feel more and more uncomfortable with this. i didn't feel i should have breasts. i didn't feel comfortable at all wearing dresses makeup jewelry. and it became increasingly uncomfortable when i got into high school i started to be teased more by kids. you know i just had a lot of confusion about my gender. and i fell very ashamed of it. i never spoke with friends or family about it at all ever once. >> rose: no one. >> no. i just very very ashamed and very confused. don't forget this was in the days before the internet so there wasn't a lot of information about this sort of thing. so as i got into my 20s i you know i was doing well whale i wasn't doing good about pie gender i was doing medical training and i was increasingly uncomfortable and like many transgender people i started to think about suicide. i never attempted suicide

but i thought about it a lot. and this is actually a picture of me back when i was barbara. i think i was 30 at that point and i was a bradz made at my little sister's wedding and i can still remember vividly even though that was 30 years ago just theing aonee that i felt the discomfort putting on that dress wearing jewelry wearing makeup and in the years since, i still remember that. but anyway i did complete my training and begin a job at standford about 20 years ago when i was age 40. and about two years into that i actually developed breast cancer. and i was still very confused about my gender identity but i knew that i didn't like to have breasts. and so when the dock ter said he needed to do a mastectomy to remove the cancer which very fortunately was picked up early and i was cured of. i said while you are there, lease take off the other breast. and he was quite horrified by this perhaps he was the first one i shared my feelings about gender identity.

but since this cancer runs in my family he did agree to remove the other breast. and i just can't tell you how therapeutic that was. i felt so relieved to have those breasts removed. and i recognized that that was a very different response than my mom had when she had her mastectomy. she saw this as a huge blow to her femininity. after the surgery the doctor started talking to me about reconstructing the breasts and i was absolutely horrified. there is no way you are putting those things back on me. so this was sort of a maybe a increasingly occurred to me that there was something a little different about pie gend are. and it was only about a year later i was reading the san francisco chronicle one day when i read a several page article about the life of james green, an openly female to male transgender person in the bay area. and i realized for the first time in my life that there were other people that had experienced the same sorts of gender confusion, that there were other people like me and that i might be transgender. and so i went to see don lab a sex change pioneer at

standford and he ran a gender clinic. and indeed after they valuated me they told me that they thought i was transgend are and they offered me the possibility of changing my sex. which was immediately irresistable to me and very quickly, within weeks i decided to change sex. i already had the upper surgery the mastectomy. i did not want lower surgery but so all that was needed was to take some testosterone and you can see the affects that it's had on me. it is powerful stuff. and one of the most surprising things will the testosterone was that i actually to my great surprise became much harder for me to cry. and male to female report that it now becomes much easier for them to cry. so that was perhaps surprising experience. but i think the main experience that i had is i just felt after i changed sex just i can't it's hard to describe the intense relief that i felt just like this weightlifted off of my back. and i've been so much

happier since. i have never had another suicidal thought. and i have to say that at the time i decided to do this i was i had been a scientist at standford for several years. i was very worried that changing sex would alter might harm my career. this was 20 years ago. but i have to say that everybody, all my colleagues an friends and family were immediately supportive. and i have been very fortunate to have just my career continue. and to have lots of wonderful students and so forth. i guess the other thing that i would like to say is that i think the other surprise after changing my sex is that i found that living as a man has dramatically changed the way that people react to me. and i can tell you a story about an experience that happened to me shortly after i changed sex a couple of years later. i was invited to give a seminar about my research at mit. an one of my friends told me that after i gave the seminar one of his colleagues was talking to

him about the seminar. and he said gee, that benn barres his work is so much better than his sister's barbara. i think that that experience sort of points out something that all of us transpeople whether female to male or male to female we have lived life as both genders. and we all share an intense anger at the different way that society treats men and women simply based on their gender. and i think in general, i think we would all say that in general society with a man sort of assumes that they are competent until proven otherwise and with women they are considered incompetent until proven otherwise. so this creates terribly unfair barriers for talented women in science. so i now devote some part of my time to trying to help women in their careers. >> rose: let me turn to norman. solis ening to that story, i assume this is a story that may be typical in terms of both someone who is

questioning and to go from questioning to looking for solutions and the experience of the reaction after you have changed. what does it is a about gender identity? >> well i wish we knew more charlie. we certainly know it when we see it. i want to show you a very powerful example of sue of identity twins who in this case one of the male twins and we have proven that these twins are indeed absolutely identical and born male. but one of them at age three started to say everything about being a girl. and in fact, if there was any issue that came up she turned it into an issue of gender. and she did some of those things that we consider hallmarks like wearing -- preferring to wear female underwear and female pajamas

and et cetera. and by the age of seven, the family decided with the help of a counselor to change her name to a female name and to have the child assume a female role. so here is twin sister with twin brother, at the sage of just about nine to ten years of age. >> rose: fourth grade. >> so they were fourth grade. and what i want to point out is that if i switched all the attachments to them the earrings, the clothing, the hair style, the shoes you could basically switch one for the other. the fact of the matter is that kids with their clothes on are virtually interchangeable prepuberty. and actually their hormoneal levels are virtually at that particular point

interchangeable. so everything happens really at puberty. here they are at age 14. now because it is so difficult to live in a gender different from your biologic sex, when you have the toxic faekts of your genetically hormone driven puberty, which would basically make twin sister look exactly like begin brother. and you can see that she looks still almost like a nine or ten-year-old and there's a good reason for it. she has had her puberty suppressed. the next slide shows the level of sex hormones across the human life span. look at the blue line which is the male level of testosterone, the hormone that benn was receiving and that some of us make but that during fetal life especially in the mid

trimester, the level of testosterone in a fetus rises to a level close to the full adult rang. and then it-- range, and then it falls and then there is another blip-up right after birth a kind of second puberty. and then things go completely dorman-- dorm anti. in fact f they didn't go dormant we would have a whole bunch of pubertial looking fifth graders running around because everything is suppressed. >> when we're thinking about possible causes for transgender, and ben and i spoke about this before wouldn't it be possible that there is some aberration in testosterone he is connection, for example or estrogen secretion during interuterine development or shortly thereafter, might be one of the contributing factors. >> it is certainly possible. it's certainly possible. it is a very dynamic stage. we still don't know what that second bump is right after birth or what role it plays or whether boys who are born without testes but

are otherwise normal show any differences as a result of that. the problem, the problem is that when we want to look at a hormone we have to be able to measure it we have to get it out and measure it. well you can't get it out of the brain. the other problem is sometimes it isn't the hormone level that is important but the affinity of the receptor for the hormone. and it's very very difficult to measure such things. >> this is really fascinating, to see what the biological underpinning of transgender identity. >> exactly. >> because as you point out it's so important because kids who are in the wrong sex, you know their incident of suicide attempt is very serious. >> it's one of the highest risks of any. >> so this is really something we need to understand. >> and the pubertial process

this whole system reawakens again, the system that had been awakened in utero suddenly comes back in which hypothalmic hormones hitting the pituitary cause the release of other hormones that strike the ovary or the testes and cause the release of what we call the sex steroid hormones which are testosterone and estrogen mainly. and those things produce the differences between the body of a male and the female associated with puberty. so we have been able to probably since the 1980s we have been able to block the releases of the hormone from the hypothalamus to the pituitary and once you do that so far upstream everything downstream guess down to zero. and we have a record of this medication being completely successful in shutting them down until the appropriate time, and also the fact that it's completely reversible.

look how revealing this is. because the twin sister affirms a female identity and the puberty is blocked for two years. two years to get more time for counselling without the pressure of body change. that's very important. because if we're going to give her estrogen that's going to have permanent affects. so take a look what would happen to her if she hadn't been given this blockade. she would look exactly like twin brother. and he is in early pub ert for a 14-year-old. but so would she have been. because they're identical. now here are the twins at age 17. and age 14 just after that picture was taken she began estrogen. while at the same time having her male hormones blocked. with that our patients don't need breast surgery when they fem inize. because it is so effective.

and she is now in that picture entering junior high school as is her brother. and she's absolutely fabulous. this past october the dutch who taught us this. >> right. >> reported that first followup of the patient the 55 of whom whose puberty was blocked and for whom sex steroids were later switched in the manner of our twin sister, the dutch group all had surgery at 18 at which point their gender disphoria their total uncomfortableness with their gender disappeared. and the dutch found that the kids treated this way psycho socially functioning as well or better than the control group of nontransgender kids they're being compared to. >> that say horrible argument for surgery. >> it's a powerful argument for available surgery at the right time for the right people. >> but also i think one of the nice things about the dutch approach is that it delays puberty.

once puberty sets in you have as just pointed out physical changes that make it much more difficult to reverse, so you prevent those physical changes of the other sex occurring. moreover, in addition to the biological changes that it delays it allows the child to think through whether this is the course they want to be on. because some people say i'm in the wrong body. i want to be a man when they're a woman but change their mind after a few months. think this is the wrong course. that occasionally happens. this delay allows not only the physiological process to be handled in a more satisfactory way but the psychological evaluation to see whether this is the way the kid actually feels which is only a temporary decision in their mind. >> so the dutch gave me their protocol in 20-- 2006 and we started using it in boston children's hospital at which time we were the only major medical center to

do so. but we're not that many years since 2006 and over 40 programs now are doing it. >> so it's to you becoming the standard of care. >> okay, now let me turn to catherine and talk about whether this is wired. >> so as we have just horde from ben and from norm arne, humans have a very early and very strong sense of their gender identity. and this is really a critical component of our individual identity as humans. now in animals as in humans males and females display clear differences in behaviors, mostly but not exincludesively related to sexual and social behaviour. so for example males and females have very distinct sexual and aggressive displace and we've seen in the previous episode that mothers of females are usually maternal and males in millionals are usually attacking the pups. so how are these differences

established and how are they maintained. well, the basic mechanism by which the brain control gender specific behavior cannot be study spermentsally in humans. so instead my laboratory is using the mouse as a model system. mice display clear differences, gender specific behaviors. and the mechanism by which the brain control gender specific behavior in the mouse can be studied using all the modern tools and the powerful tools of modern neuroscience molecular neuroscience and genetics, so sex typical behaviors particularly sexual, aggressive and also parental behavior are extremely maintained across different animal species. and so that suggests that the brain control of those behaviors is also very maintained across animals. now in contrast the signals that trigger these behaviors are usually extremly

specific of a given species. so for example, in the species of birds call the american flicker these only one side that matters to trigger gender specific behavior. and that is the black house dash on the face of the male. and so if you remove the black mustache from the face of the male you just mask it. then the other males will attempt to copulate with that male without a mustache-- muss stash because they will assume this is a female. and similarly if you paint a muss stash on the face of the female, then the other males will attack that with the muss stash because they will assume it's a male. i have a mustache it's a male i don't have a mustache i'm a female. mine in contrast use olfactory cues called ferromoans and humans are particularly sensitive to

visual and audit other krews a fact that has been-- by the pornography industry. so once we know what are the signals that trigger gender specific behavior, now we can look into the brain. how is the brain processing these signals and establishing this ginder specific behaviors. as we have erd from norm spack, in young males they are very important releases -- release of hormones testosterone and this release of testosterone has been shown to be absolutely essential to masculineize the brain. and in contrast females do not have release of test toses rone so in male the simpleest intermtions is that testosterone is essential to establish and maintain a very specific set of circuit underlying male

specific behavior and females organize their brain in a different way, in order to control female specific behavior. now in our lab we have performed a number of genetic experiments that show that the situation is a little bit more complex. the experiment we did is actually very simple. we looked at mut ants for pheromone detection which is indicated by this little cross here on the structure of the brain called the ol fact ory so this is simply insensitive to sex specific pheromonal cueses and when we look at their behavior we saw something extremely surpassing. so here in gray is the female mut ant and in black is male. and as you can see this female is mounting the male which is a very male specific behavioural display it is a male specific sexual display. so these females, in other

words, is displaying a male typical behaviour. if we now look at the mute ant males a male unable to detect pheromon ercks this male strangely instead of attacking is now retrieving an infant an bringing it to a test that this male has built right before him. so here again this male is displaying a female-specific parental behavior. so what do we learn out of this. well what we learn is that the brain of both males and females contain the presentation of male and female behaviour. so in females in normal animals, the male behavior is repressed by the pheromonale system and in males similarly the female specific circuit is normally repressed. but in the mut ant that we

observed what is happening is that the repression of the opposite brain opposite sex behavior-- does does no longer skis and therefore the female now is able to display both male specific behavior and female specific behavior. similarly, the male is able to display both female specific behavior and male specific behavior. >> i think this is so beautiful. not only because this is something that-- is struggling with, but it really i think provides a way we can begin thinking and exploring a transgender identity, if in fact we have the circuits for both kinds of behaviors, you can see how slight tilts for one reason or another could contribute to wanting to be another gender. i think this is very profound. >> yes so i think that exactly as eric mentioned what this shows is that the brain of males and females are largely similar. and that a specific hormoneal and genetic regulation leads to the

predominant but not exclusive display of the behavior of a given sex. and these are extremely important because animals occasionally need to display the behavior of the other sex. we have seen in a private episode that males are occasionally able to display parental behavior and similarly n many species females are displaying mounting behavior as a sign of dominance. and so the brain has actually been shown to be by sexual in fish many years ago, in reptiles more recently, now in mice. and we think that this ability to have both the remtions of the male and female brain could also be totally irrelevant to the primal gender identity in humans. >> let me turn to melissa and talk more about defining gender identity and sexual orientation and gender role behavior. >> i have studied the role

of testosterone in human gender development. and we have studied genetic conditions that cause people to have either higher or lower levels of test torses rone testosterone during prenationalality development than would otherwise be the case and evidence from those people suggest that testosterone in humans also influences gender development including gender identity. and to start it is useful to put this in context to expand our understanding of the dimensions of gender related behavior. we've talked about an no-- anatomical sex and gender identity which is our sense of self as male, female or something else. but also people have sexual orientation. and there is separate to gender identity it refers to our erotic interests in males, females both or in some people neither. and finally there is a third class of behavior called gender role behaviors. and these are all the other characteristics that differ

on the average for males and females. an among these some are bigger than other . some of the biggest ones are seen in childhood toy and activity preferences. the next image showsed sex difference in height and we're all familiar with this males tend to be taller than females. but there's some overlap. so the males are the blue distribution and the females are the orange distribution. and the people where the overlap is would be people you wouldn't know their gender from knowing their height. and the next images show that these gender differences in play play with toys like vehicles or boys toys, play with toys like dolls or girl's toys are similar in size to the sex difference in height. and finally we see the gender difference in identifying with the male gender and we is see that this gender difference is even bigger and there's almost no overlap between males and females. but there are some people who are in the other

distribution. and these include the people who want to change their gender. how does this come to be? we've talked about these sex differences in testosterone some of which occur very early in life. and this corresponds to a period of very rapid brain development. and so it provides an opportunity for hormones to program the brain in ways that might have enduring influences across the life span including for instance on gender identification. so the next image shows data about women who had very high levels of testosterone before birth and about two percent of women who have very high levels of testosterone before birth in adulthood decide to live as men. and you might says that's not very many, only two percent but it's hundreds of times more than would otherwise do so. so this is increased many times over by being exposed to high testosterone

prenatally. and the next image shows men. in this case xy individuals who are actually xy females because their cells can't respond to testosterone. so they have testes they are producing male typical levels of testosterone including prenatally but because their cells can't respond, they look like girls at birth and they are raised as girls and in adulthood almost 100% of them, 99.9% want to live as women. >> such profound findings because although we don't really know in the vast majority of cases what causes a desire to change sex, here we find one concrete biological explanation for a causative mechanism it makes one realize this is not a social fact it is clearly a biological factor and probably with time you will be able to identity a significant number of other ones. i think having one is very powerful. >> yes, yes. and also going back to the

toys children like to play with when i began this work people thought that these different interests in girls and boys were completely socially determined. but it turns out these are altered too by prenationalal testosterone exposure. so the next slide shows the toy choices of girls and boys in general versus those of girls exposed to testosterone before birth and boys then most of their time playing with toys like vehicles. shown by the blue and girls spend most of their time playing with toys like dolls shown by the orange. and the girls exposed to testosterone prenatally are in between. so they spend about half their time playing with toys that boys normally choose and about 30% of their time a reduced amount of time playing with the toys that girls normally choose. these are different dimensions of behavior. and the influence on gender identity is less powerful it appears than the influence of testosterone or

childhood play. so that leaves a lot of unidentified factors, perhaps genetic factors or social factors that contribute to gender identity outcomes. but finally this is not just testosterone acting on the brain before birth but also hirn who have had high levels of testosterone engage in different behaviors. and this has a feedback affect on their brain development. so this becomes an increasing mechanism where their behavior is increasingly masculineized as they go through life. >> thank you, janet talk about cognitive performance and ability. >> right well certainly in our culture we have lots of ster why types that there are gender differences and abilities. people believe that boys and men are better at math and girls and women are better at verbal skills and boys are better at spatial performance. those are the stereotypes.

what does the real data show once again we're looking at distributions for male and female performance blue for males and orange for females. what you see is that the most recent data show actually that girls are tied with boys now in mathemattal performance. many people find this surprising but i have data from millions of people showing this. in regard to verbal performance you can see that there is a female advantage but it's teeny tinny, you can hardly see it on that graph. so these are very subtle slight differences. for spatial performance the difference is a little larger favouring males. and i'm showing you one particular kind of spaition performance which involves the ability to rotate three dimensional objects in your mind and think how they might look. other kinds of spatial performance don't show this quite as large a gender difference. you need this kind of spatial ability if you want to be an engineer or an architect, or if you want to

use a map to navigate around new york city. so it is important for some things but not everything. but i have to say that we get this gender difference in spatial performance in the absence of a spatial curriculum in the schools. that is we teach kids lots of verbal skills and lots of mathematical skills. we don't teach them spatial skills. these are completely trainable. in some school districts are to you getting the message and starting to institute these programs so if we want to do something to foster bim getting into areas like engineering where they are very underrepresented instituting a spatial curriculum might really do a lot to hem. i also want to emphasize the importance of cultural context in shaping these gender differences. this is the percentage of ph.ds awarded to the women in the u.s. by decade beginning in the 1890s. now it turns out i didn't

know this i don't know if you knew this, it turns out that even in the 1890s 11% of the ph.ds in math were going to women in the 1890sment you can see it inches up a little bit there into the 1930s. and then the percentage plummets in the 1950s. so that only 5% of the ph.ds are going to women. then it's been inching up ever since so that actually today 31% of the ph.ds in mathematics are going to women. why did it plummet in the '50s. those were the 1950s right. the men came home from the war. the women were delighted to see them. they moved to the suburbs and had lots of babies so there is not some single biological force that causes women to be good enough to get a ph.d in math it has much more to do with cultural context. well it's findings like these that i've shown you for verbal and math performance and so on that lead me to propose what i call the principal of gender similarities which is that males and females are

actually quite similar on most not all but most psychological variables. you saw it for math and verbal performance which are widely stereotyped to show gender differences. and of course this has implications for women in science, technology engineering and math careers. so this graph shows essentially what the genlder similarities hypothesis is. again, we have the overlapping distributions normal distributions for males and females. females shown in orange and males in bluement and you can see there's just huge overlap, areas where males and females are quite similar. let me turn now to looking at psychological disorders. because for some psychological disorders we do get very lopsided gender ratios. so on the left part of this graph, you can see two disorders where many more men than women are affected. those are alcoholism and autism. you see the blue bar is the preponderance of male. that's not to say that we

don't have women alcoholics or girls with autism. but it's a preponderance of males. if we look at the right we can see for depression, and the eating disorder of anorexia here we have the a preponderance of women shown in the orange bars. so we do have these lopsided gender ratios. we wonder why those are. i'm most familiar my research has been on gender differences in depression. we can see that the gender difference in depression is not present in childhood but it begins to emerge between 13 and 15 years of age, as you can see the orange bar is going up there. and then it widened between 15 and 18 years of age. so gender differences in depression emerge in adolescence. and if we're going to crack it's a 2 to 1 ratio twice as men women as men depressed, if we're going to crack this question we need to understand why the gend ever difference emerges in adolescence.

many factors are doubtedless involved. it may have something to do with genes. we have a few genes that have been identified that have to do with depression it may have to do with pubertyal hormones because the condition emerges just as puberty is coming on it may have to do with other factors such as the media's emphasis on hyperskinny models and girls as they go through puberty. the bodies get farther away from the skinny models. boys have the advantage because they are adding muscle and that is the way the models look. so that may be a factor. we also know that there is plenty of pure sexual har wasment in the schools and that also may contribute to this gender difference. >> rose: thank you. >> ben let me go back to this idea of how society is responding. because we know from the cover of "vanity fair" the new york sometimes story. we know from "time" magazine did a cover story which i'm told was the secretary biggest selling "time" magazine cover story that

year with one exception of the pope. transgend certificate right behind the pope. >> i think it's unfortunate that society often considers transsexuality to be a mental illness or an immoral choice. and because of this transgenter people are still often denied bake human rights they're often subject to violence. and in many states transgender people can still be fired just for going transgender. but as we've heard today on this program, the brain has innate circuits that determine our gender identity. and so being transgender is not a choice that i made. but it's how i was born. and i should mention something we haven't really brought out yet, that there is a broad spectrum of transgender people. some of them prefer not to change sex or even to be identified as male or female. but for some of us there is

a compelling innate need to change sex and denied that possibility 40% of us attempt suicide. and that's why i think that by helping transgender teens to avoid thising aonee dr. spack and the dutch pioneers are such great heroes. >> you are advising at standford, what role do you play? what is it that you can provide. >> it is interesting catherine, just in recent years i've really been amazed at how many young lgbt lesbian gay bisexual transgender students, trainees, young scientists are reaching out to me. these days almost every time i visit another university to give a talk, i often get e-mails in advance from young kids, often still in the closet and very concerned about whether coming out will harm their careers. and they often want to meet with me and talk about this.

and i always advise them to be open and to live openly as who they are. people are very very accepting today. sure, there's always going to be a few bullie's. a few people that are ignorant. but never let other people define who you are. >> so what should parents do? >> i think the first thing that parents ought to do as with most things is sit down and take a deep breath okay. and realize that the prepubertial child is in a state of exploration. it is no accident that both boys and girls go to the boy toys and the girl toys in kinder gart ebb. >> rose: right. >> this is not gender identity expression by and large. this is almost always a gender role play which is

normal for children. now of children who are fairly persist ent in their cross gender play but are prepubertyal only about 20% will go on to be transgender. 80% are not going to be transgender. what i would say to parents is that if your child is getting close to puberty or worse is already in and is showing this kind of behavior particularly underwear wearing and saying i'm the wrong gender and binning breasts, et cetera then you need to get help for that child fast. and that may be calling your pediatrician and ask for a gender specialist to meet with your child. because a child who is according to the dutch and us and others a child who

holds on to the belief that they are in the wrong body at the onset of puberty feels like pin octoberia becoming a donkey and may well take their life. so these are the kids who are the real deal. >> rose: over the series of three years eric you and i have found a range of things that we traced to the brain and understood. and some levels in some cases the what we understood about what was taking place within the brain, was large in some cases small. where do you put this? in terms of understanding what is going on? >> i think we're at the very early stages in understanding what is going on. and i think the wonderful thing about this discussion t points out number one there really is a buy only. it's a challenging problem. it's extremely fundamental but our understanding is just very very modest. we talked about this before. many times people have asked charlie and me, how long do you think it will take

before we'll have a really satz fact other understanding of the brain. and our position has been a century. we have made a lot of progress, in the last three years in the brain series alone. >> yeah. >> but we are a long way to really understanding the brain systemically. >> gender identity is so essential to who we are and our ability to be happy. i think we have a duty to be able to provide some type of explanation. but there is something really important to which is to understand that it's not all black and white. >> i think it's important to remember that differences are not disorders. >> absolutely. >> and i'm proud to be transgender. i think that the different brains drive innovation and different perspectives. and so i think the real question is why is society persists in insisting that male brains are better brains, which as we've heard tonight is definitely not the case. >> that's right. >> i think one thing that will be interesting to see

is as you function in a way that you are comfortable with it has freed you up it is impossible on the single case to answer this has it increased your creativity? >> well, i think that it released a lot of mental energy that was devoted to confusion and feelings suicidal so i would say yes i felt so much happier and productive as a person. >> that's wonderful. what percent of people also undergo anatomical change? >> the issue we're now in a state of flux about the an operation that may cost $25,000 dollars which is a female a male to female genitalplasty. and the reason i say that is because insurance companies are waking up to the idea that this is a medical condition. that it is entitled to be billable for surgical and medical aspects of their

care can be covered by insurance. and so it's going to change everything. because up until now people had to save all of that up to have the surgery. and it starts from the top down. first you have to not make it a mental illness. you have to define it as a physical problem. >> which it is but hiding it as being gay was prior to 1973, what freed up people starting to see gay people as not having a psychiatric illness t was having it removed from the diagnosis and statistical manual of mental illness. >> so that's happening now. and we will just see. the colleges are doing it. if they are self-insured maybe even the college you went to charlie is paying for people's everything. because i'm going over to some of them and seeing it done. >> thank you each of you very much for coming. it is, i think it's-- there is enormous interest as you can see in the publications

devoting attention to it. and also the conversations that is taking place. even i once this subject was introduced in terms of a television program i remember someone came up to me and identified themselves as transgender. you know and said but they -- they said that the fact that is is getting so much attention made all the difference in their life you know. and so they felt not so isolated. and not so different. i mean they felt like -- >> wonderful. >> that there had been identified as something so that they could have an appreciation of where they stood and what their options were. so what are we doing next time sm. >> we're going to continue to discuss child dome which we discussed earlier. what are the consequences of growing up under very difficult circumstances. how does it affect the cognitive development of children. and is this passed on from generation to generation. so we're going to learn a

lot more about child development next time. >> thank you thank all of you. and thank you. we'll see you next time. >> for more about this program and earlier episodes visit us on-line at pbs.org and charlie rose.com.

>> funding for charlie rose is provided by american express. additional funding provided by:. and by bloomberg, a provider of multimedia news and information services worldwide.

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