"It's the most fundamental act of human life." "And though we may have come a long way from our early ancestors, one thing hasn't changed much." "Sex." "Yet, despite being widely practiced, sex has always been a bit of a mystery." "But science is starting to unlock its secrets literally getting under our skin to reveal a new, bizarre world." "Aworld where the truly unexpected can happen." "For the first time on television, we follow a woman under the influence of hormones, acquiring the body, the mind and facial hair of a man." "Understanding sex is the key to understanding how to build a human." "All humans are built in bits, far too small to be seen with the naked eye." "We're made up of cells." "And inside every cell is exactly the same mix of genes - our DNA." "Until recently, reproduction was regarded as pretty straightforward." "To build a new human you first take the genes that make up a woman, then the genes that make up a man, and then enthusiastically mix them up." "But things aren't quite that simple." "We might have been doing it since the dawn of time, but scientists know very little about the basic processes." "Reproductive physiologist Doctor Roy Levin, has struggled with the technical limitations of studying sex for decades." "We didn't really have the apparatus to allow us to do the measurements." "And there was a long period of time when you only guessed what was happening from the external appearances of men and women in coitus." "So that you couldn't really tell what was happening inside, because you just can't see." "Cur understanding of sex hasn't moved on much since Leonardo Da Vinci first started dissecting corpses and studying them over 500 years ago." "The Queen holds this drawing by Leonardo in her very own private collection." "Doctor Levin's life-Iong quest to reveal the secrets of sex is taking him to Germany." "What I've come for is a machine." "This is a machine that makes the body transparent." "You can look inside and see movements and the secrets really of coitus and how people get sexually aroused." "There are very few machines like this in the world, and one of them is here in a town called Krefeld, quite a few miles outside of Dusseldorf." "And the machine Doctor Levin's come to see is this FMRI scanner." "It's basically a camera which uses magnetic fields to penetrate human flesh." "Today, in the interests of science," "Michael DeGroot and his girlfriend Liz Leahy are going to attempt to have sex in its cramped confines." "Well, this is the machine as you can see inside, it's got, like, two doughnuts, those are the very magnets, and in between is the space that you'll lie down in and have coitus." "So it's been specially adapted, that means just a single board has been put down, and you'll lay in between the two magnets, and hopefully that will capture the images of what's going on during sexual intercourse." "The other thing that has to happen is," "Liz, is that you have to wear this girdle it won't do much for your figure, but it'll hopefully capture the images from what's happening inside your body." "So you have to put this sort of around you, in the pelvic area, and then you lay on top of that." "And so that's really basically all there is to it." "The other thing is though, Michael, that we'll help you to perform with this pharmaceutical support for it." "So hopefully, it'll help you to do this." "So let's go and get changed." "Ckay?" "Ckay." "Doctor Levin is well aware of the problems that need to be overcome if this experiment is to be successful." "It's not the easiest thing in the world to maintain an erection and have intercourse in terms of this particular set-up." "They're brave people that go into these machines." "We've seen the machine, and I'm interested to see how we're going to manoeuvre ourselves in there, because it looks like a pretty constricted space." "And I know they want us in one certain position." "So I hope" " I hope that that we're able to situate ourselves so that they get the images that they want." "I'm just -that's my main concern." "Michael has a personal interest in taking part in this study." "I have a small background in human sexuality, in the psychology aspect, because I'm a psychology under-graduate." "So with my background I just kind of got an interest, and hearing about these images that would be one of the first times that these would ever be recorded," "I just thought it would be really fun to be a part of this work." "Ckay, we're ready to go." "You can start now." "The scanner takes a picture every three seconds, and produces images of the body from top to bottom." "This is the first time that such images have been seen on British television." "You can sort of see the penis here." "That's outside of the body from about here." "And this is the root of the penis inside the body." "And this is inside the female's body." "That's her pubic symphysis, the bone, and here would be the pubic hair just around here." "That's, of course, her bottom." "And this is the vagina that the penis is in." "And at the top here is the glans." "And the thing that's obvious in this cross-section is the unusual shape of the penis during intercourse." "Well, it's like a boomerang." "That's what we've found out by this machines actually, that, in fact, the penis does look like a boomerang." "It isn't straight like they drew it in the early times." "In fact, it is bent, as you can see quite clearly." "It's actually incredible, because as far as when you have an erection you think it's, you know, hard and solid as a rock or wood or something, but when you look at those pictures it's unbelievable," "like, you have the 90 degree angle, and you can't even imagine that it would bend that way." "So..." "It's really fascinating to see what the body does." "Just incredible." "Yeah." "It's not something you really think about when you're actually in an act like that, and to actually have the pictures to see what's going on, it's just extremely interesting." "Nobody knows why the penis has to go through extraordinary contortions." "Cne theory is that it's a relic from our past, when sex was more commonly done on all fours and not face to face." "Doctor Levin is aware these experiments might be seen as prurient or trivial." "But he believes that understanding the mechanics has important practical applications." "Cne possibility is that when we get a bank of normal images of functional the normal reproduction and the movements that occur, and we have a whole range of images, because this is just one couple that we've done," "we can then possibly look at people who are abnormal, that they can't have children perhaps, and their -the dysfunctions that are there might be in the movements, might be in the motility that we can pick up," "and then we'll be able to look at that and possibly have treatments for it." "But that's really looking into the future." "We'rejust starting out really, the first step this is." "Understanding anatomy is important if you really want to understand what makes men and women tick." "But there's also much that can be learnt by studying their cells." "Down at this level, men and women are all very similar." "Each cell holds a nucleus which, in turn, contains DNA, the substance that builds us." "Each cell contains over two metres of DNA, divided and packaged neatly into chromosomes." "There are 46 of these." "The real difference between men and women is that women normally have two X sex chromosomes," "while men have an X and a Y." "But it's not always that straightforward." "Look at Jan Johnson." "She's an athletic, feminine 42 year old woman." "She's also six foot three inches tall, a distinct advantage when you're playing volley-ball." "The other thing that's different about Jan is that she's genetically male." "There's a huge stigma attached to my condition." "I think a lot of people don't want to talk about their personal conditions, and, you know, no one's perfect." "People - lots of people have problems, and itjust - it's a matter of facing your deepest, darkest secrets and bringing them out in the open." "She had no idea that there was anything strange about her when she was growing up." "The only thing that I remember is that I was just very active, and I just had a lot of energy." "In terms of, like, feeling different no, I didn't." "I just felt like a normal a normal little girl, and, you know," "I had girlfriends, and I had all my dolls and, you know, everything was just just normal." "It wasn't until she went to college to study anatomy that she realised something was wrong." "Quite simply, at the age of 19 she still hadn't gone through puberty." "I felt self-conscious because I wasn't developing like all my girlfriends were developing." "You know, it's painful to stand out and be different." "And I wanted to find out why I wasn't starting my period." "So I ended up going to the gynaecologist for the first time." "I came into class one day very upset, and - because I had gone to the doctor a few days before, and they had very simply just written XY on a piece of paper, and gave that to me." "And that was supposed to be the explanation of why I was the way I was." "So why did Jan become a woman when her genes were those of a man?" "The answer lies in understanding how the male sex chromosome the Y chromosome -works." "The most obvious thing about the Y is that it isn't very big." "The Y has around 60 genes and the eggs around 3,000." "The Y chromosome is the smallest chromosome, and when you look at it in detail only a very small part of it actually codes for anything." "So most of its a desert." "Peter Goodfellow knows the Y chromosome intimately." "He found the gene responsible for turning embryos into men." "It's on the Y chromosome, and it's called the SRY." "It's hugely influential in how men develop." "And this is it." "But being very important doesn't mean it's big." "Imagine that your dnawas a piece of string, so you could see it." "So we've magnified the DNA which is present in every cell in your body so it's visible." "And that piece of string now would stretch from here to Moscow." "Now, if we were to start ajourney from here to Moscow, on foot, the Y chromosome would represent the first 20 miles of thatjourney." "And the SRY gene would be the first step on thejourney to Moscow." "It takes 30,000 genes to build a human, butjust one gene -the SRY to build a man." "The SRY is a switch which clicks when the foetus is around six weeks old." "Until then, the baby could become either male or female." "When the SRY is switched on, it fires up the development of the male sex organs." "There's a tiny genetic difference, that genetic difference leads to one key difference, and that one key difference is men have testes and women have ovaries." "And it's what's produced by the testes and what's produced by the ovaries which is responsible for the differences you see between males and females." "But Jan Johnson has a copy of the SRY gene, so why isn't she a man?" "Well, the SRYtriggers development of the testes, and they produce a very versatile hormone called testosterone." "Testosterone is a steroid hormone, and one of the things that steroid hormones are excellent at is going in lots of different places in the body and instigating lots of different changes, and testosterone's a beautiful example of that." "Testosterone rampages through the male embryo building muscle and developing the cardio vascular system." "It's this hormone which makes men so very different from women." "To a remarkable extent, testosterone is responsible for the masculinisation of the human body." "It's really, in some ways, it's kind of surprising that this one agent seems to start this cascade that has so many different effects." "And it's testosterone that is the answer to the riddle of Jan Johnson's unusual genetic make up." "Jan has a condition called AIS Androgen Insensitivity Syndrome." "Her genes make testosterone, but her body can't respond to it." "If it can't react to testosterone the foetus assumes the default position, which is female." "And that's exactly what happened to Jan Johnson." "The discovery that she's genetically male was so traumatising that she couldn't even tell her then boyfriend and future husband, Peter." "I told him well, I'm unable to have children, and, you know, here's my situation, and I don't have my period." "But I never really got into the nuts and bolts of it with him." "Why?" "Because it was embarrassing for me." "I didn't want to talk about it." "And I didn't think anyone wanted to hear about it." "The only person she felt would listen and understand was her anatomy professor Kris Blodget." "And I said well, the first thing I want you to know is you're a normal girl, you're not a boy, you're definitely a girl, you're a very feminine girl." "This should not change your life." "It was devastating to know that I had XY chromosomes, and those are the same chromosomes a man would have." "Then I said, well, you can't respond to testosterone so, actually, you're more feminine than an actual than an XX female who can respond to testosterone, too." "So I said" " I said the people that have this develop as normal female, usually above-average in attractiveness, they're tall, they're very feminine." "Professor Blodget then got Jan to check her own genes." "So she could see there was nothing to be frightened of." "She was probably the strongest female person in my life back then." "My mum couldn't really offer any support, and you know, my siblings certainly couldn't offer support." "So I really didn't have anyone who could explain it to me the way she explained it to me." "And the pain and the hurt of the discovery that she was genetically male came flooding back when they met for the first time since Jan left college 25 years ago." "I was hoping that she's put it behind her, and was leading a normal life and not considering it a deep, dark secret, and realised that she was totally feminine and normal." "She really made me feel a lot better about myself." "So it was great to see her again." "Jan's unusual genetic make up means she can't have children, the thing she wants most." "She doesn't have a womb or ovaries." "And that's put an inevitable strain on her marriage." "We've been together for 23 years." "We've been married for 13 years." "And we've certainly had our ups and downs, and some of the - some of the deepest lows were over, you know, adoption." "And you know, and that's unfortunate." "I would" " I hoped back then that I would meet someone that would want to adopt children, and itjust - itjust didn't work out." "It was not the right time, and we didn't have the money or, you know, for some reason or another itjust never it never worked out." "Ironically, Jan Johnson works for a company which makes high-tech medical equipment." "But there's no technological solution to her inability to conceive," "Shejust doesn't have the right genes." "Instead of a Y, she'd need another X." "That's because the second X sends out instructions to make ovaries." "These produce the female hormone oestrogen which builds a womb and fallopian tubes." "The discovery that men are created from a female blueprint was certainly a big surprise and contradicts previously held notions about the relative importance of men and women." "Societies have decided the relative importance of men and women for thousands of years." "By and large, the men are regarded as more important than the women." "So when biology started to catch up, at first it looked to reinforce that;" "the idea was that the sperm contained the little person and the woman was just the sort of soil in which the man would grow, the baby would grow." "Gradually, as we've learnt more about it, we've realised that the mum is rather more important, and the woman's rather more important." "And the big shock came when it was realised that if you don't have a sex chromosome, or one of the sex chromosomes you don't come out as a boy, you come out as a girl." "So what that tells us is that the Bible was fundamentally the wrong way round." "Woman was not born of man's rib, it's the other way round." "Adam, if anything, came from Eve's rib." "So the male is an adapted form of the female." "Cne very obvious remnant of our female past can be found on every male chest." "Nipples." "The reason men have nipples is because they developed in the foetus before testosterone kicked in." "But if a hit of testosterone is all it takes to turn the female form into the male... what would happen if a genetic female were to be exposed to it?" "Max Toth, a software programmer, is physically and genetically a woman." "She wants to see if testosterone can turn her into a man." "I remembered having this distinct moment where I thought that God had made a mistake and that I should have been a boy, which I thought was interesting, because I grew up in an atheist household." "I didn't really have a good conception of what God was, or that there was an entity that could have made a mistake." "But I remembered having this very clear moment." "Science can't explain why she feels like this, but she knows she's not right the way she is." "She wants the body and looks of a man." "The idea that I could do this, that I could change something about the way that I was made up, that I can change the way that my body had been born was very exciting to me." "To masculinise her body," "Max is planning to take a course of testosterone." "I'm taking my life into my own hands in a lot of ways because there aren't a lot of studies about the long-term effects of testosterone." "But Max really wanted to do it and have it properly evaluated." "So we followed her testosterone treatment for six months to see what effect it would have, not only on her body, but also on her mind." "The body changes will be the most obvious." "Testosterone should build her muscles and make her more powerful, which should mean that she'll run faster." "To test this effect, we set up a round course ofjust over a mile in Pan Handle Park in the middle of San Francisco, and recorded her time." "11 minutes, exactly." "We'll come back and check that time as we monitor the progress of her testosterone treatment." "Apart from the rather obvious physical effects, testosterone might also change the way her brain works." "So we had her brain scanned by Doctor Ruben Gur, one of the world's leading scientists on the effects of hormones on the brain." "Doctor Gur also put Max through a battery of practical and psychological tests designed to see just how feminine Max currently is." "Max shows a fairly typical female profile cognitively, and I'd be curious to see whether there is a change in that." "At the moment, by any measure, Max is a woman." "But that's about to change." "I had a birthday party recently, and I thought as part of the festivities that I would allow people to express themselves artistically by drawing my future facial hair." "So I gave people this form, and this is some of the stuff they came up with." "Trucker Max." "Flaming Max." "Spit curls." "Bad Eighties rock star." "Funky shimmer boy." "My absolute favourite, the I'm secure in my masculinity Max." "Today's the day when Max receives her first shot of testosterone." "From now on, she wants to be referred to as 'he'." "So this is the big day, huh?" "Yep." "It's only a really small dose." "So it's a very small volume." "Right." "So it's not a problem." "I actually still have to go draw it up." "Ckay." "I just wanted to check what dose that we're starting you on." "Ckay." "Max will soon be exposed to the same level of testosterone as a young boy going through puberty." "Ckey-doke." "Here we go." "Ckay." "There you go." "Cn three - one, two, three..." "There you go, that's it." "A little blood and everything." "Ckay." "I'll just put a bandaid on there." "Ckay." "Cool." "Ckay?" "Thank you." "You're all set." "You're very welcome." "It was kind of exciting and it was kind of scary." "And my arm hurt." "I'm rolling the dice and seeing what it is that's gonna happen, and I have my own personal beliefs about kind of how much one's personality shifts aren't bio-chemical." "I'm kind of in the camp of I think that a lot of stuff is sociological." "And so - but - and I'm willing to stake my life on it, and the better part of my bio-chemistry." "So we're gonna see at the end of this, you know," "I don't want to wake up and be knuckle-dragging and chest-thumping and things like that." "So it does make me nervous." "But I don't think I will." "Women naturally have some testosterone in their bodies, but men have ten times as much." "And some men have more than others." "But does it really matter what your level is?" "Take a look at these athletes;" "they're all highly trained 100 metre specialists, and about the same age." "But if they raced, could you tell just by looking at them, who'd win?" "Well, this man, Doctor John Manning, says he can, just by measuring their fingers, and that's because testosterone levels and finger lengths are intimately linked." "We've known for a long time that there's a sex difference in the fingers." "It's quite a subtle difference and, in general, people don't talk about it and don't know about it even." "It starts in the womb." "Hormones rush through the developing embryo, building and shaping the body, including the fingers." "And the effects can be seen years later." "Compare the hand of the man on the left with that of the woman on the right." "The man's ring finger is longer than his index finger." "In the case of the woman, it's the opposite; the index finger is longer than the ring finger." "We think that the length of the ring-finger is a direct indicator of the amount of testosterone one's exposed to in utero, and the length of the index finger indicated the amount of oestrogen you've been exposed to in utero." "So it's the relative lengths of these two fingers that are important." "If you've got a longer ring finger than your index finger you have been exposed to high testosterone." "If you've got a longer index finger than ring finger you've been exposed to low testosterone and high oestrogen." "Doctor Manning is one of the world's leading experts on testosterone." "In the course of his investigations he's worked both with infertile men and with professional footballers." "He believes pre-natal testosterone plays a big part in determining future athletic performance." "But he's never put his considerable reputation on the line by trying to predict the result of a race between athletes he's never met or seen run." "This is a high risk business, I think." "You know, it would be nice to have ten races with ten different groups of athletes, and I think we would probably be able to predict sort of eight out of the ten winners of those ten races." "Cne race is highly chancy, but I'll give it a go." "So, why should it work?" "Well, testosterone helps develop the heart and lungs, the engine of any athlete." "Crudely speaking, the bigger the hit of testosterone in the womb the greater the physical potential of the foetus." "It's obviously impossible to say with any certainty how much testosterone these men were exposed to when in their mother's wombs." "Instead, Doctor Manning is using their fingers as a guide to the size of their in utero hit." "The runners and their coach aren't entirely convinced." "I don't think it's gonna work." "I'm not confident at all about it." "We're all probably a bit sceptical about it." "But I mean it's got undue possibilities if there's something in it." "I cannot see it, why your hand measurements would predict how fast you run." "I can't see any connection between the two." "While the lads get ready to run," "Doctor Manning finds a quiet corner to make his calculations." "So has he found a winner?" "These are five very, very fine young men." "I mean they're excellent athletes, and they've all had quite high testosterone levels before birth, as one would expect." "But there are clear differences between them." "As far as he's concerned, these are the winning fingers." "They belong to Tim Abeyu." "And you can see the difference between his ring finger and his index finger is quite marked." "Compare his hand to one of the other runners." "This is lan Deith's hand." "And the difference is obvious." "Tim's got a very low ratio, and I think has tremendous potential." "I think he's a very, very fast running." "So I'd go for Tim." "As they prepare to race, none of the athletes know Doctor Manning's selection." "So, the moment of truth." "They line up from the left, in lane 1, it's Lawrence Cbi." "In lane 2, it's Jonathan Regis." "3 is lan Deith. 4, James Ellington." "And in 5, Doctor Manning's selection Tim Abeyu." "And Abeyu's got an absolute flier." "He storms out of the blocks." "Doctor Manning looks like he's picked a winner here." "But Cbi in lane 1 is fighting back." "But the big man in lane 5 is pouring it on." "And Abeyu's got too much..." "and Abeyu wins." "So the prediction was spot on, which was a huge relief for Doctor Manning." "Well, I was very, very pleased to see Tim go across that line first." "And in great style as well." "Be interested to know if they have a race for elite athletes at the very top of their game, if the same principle applies." "Doctor Manning is conducting similar research with the British Ski Federation, helping to select potential downhill champions." "Men are engineered in such a way as to be able to compete physically against other men." "So the more testosterone a foetus has, a male foetus has, the more efficient his cardio vascular system is going to be after birth." "If you don't get exposure early and to high amounts of testosterone, then it will affect your competitive physical competitive abilities later in life." "In the light of such findings, parents might be tempted to add a touch of testosterone to their growing foetuses in the hope this will make them more athletic." "But building super athletes by manipulating testosterone would be dangerous." "And anyway, there's much more sophisticated technology available." "You can definitely create super athletes in the future, and there's a much easier way to do that than to muck muck around with the with the embryo itself." "The better way to do this is to create the cassette of genes that you want in the laboratory." "So even before you come near an embryo in your laboratory, you put together each of the genes that you want to put into your future child, you put them together, you make sure that they're working properly" "and you put them onto a brand new chromosome, and then you take this chromosome which has already vetted for perfection, you take this chromosome and put it into the embryo." "And that's a much more efficient way of changing a large number of genic characteristics at the same time." "If you think that sounds like science fiction you'd be wrong." "Artificial chromosomes are not just figments in the imagination of scientists, they've already been created in the laboratory, they've already been placed into mouse embryos and we already have mice born with these extra chromosomes." "And if you can do it in mice you can do it in humans." "But doing it in humans would be a big and disturbing advance." "The differences, on a genetic level, between us and our early ancestors like" "Australopithecus are tiny, less than 1%." "If it only took a few tiny changes in our DNA to go from Australopithecus to us, imagine where implanting an array of artificial chromosomes might lead to." "But perhaps it will never happen." "We've got to be aware that it's not easy to do." "Even if you achieve it, you've then got to say can I keep doing it?" "We've been to the moon once, but there's no hotels there." "So the ability to do it once is not the same as being able to do it on a wet Wednesday in Doncaster." "And I have great concerns aboutjust the complexity of these techniques and their applicability, even for severe diseases." "But even if you got it to the stage where you could make it work and you could cure some rare diseases or some serious diseases would you actually use that very precious, very expensive and challenging technology to do something" "as trivial as social modification of a person to make them bigger, smarter or whatever." "You know, which island full of mad scientists is actually doing to do that?" "I don't think they exist." "I don't think they would allow their precious reserves and resources to be used for that purpose." "But expensive and challenging technology is being used all the time for purposes its makers did not intend." "Testosterone wasn't synthesised to turn women into men." "Yet, it's being used for that." "It's six months since Max first started taking testosterone." "So, what are the changes?" "Well, he sings in a synagogue, and his voice is certainly different." "My voice is trying to get deeper." "It fluctuates where - kinda depending on where I am with the dose." "It can go farther down when I'm singing, but my speaking voice can be anywhere from exactly normal to slightly lower than normal." "And he's also getting much hairier." "I'm getting more body hair and traditionally male patterns." "Hair is coming in on the back of my calfs." "Hair is coming in on the edge of my hands in a way that never happened before." "I'm starting to get darker facial hair here, and a little bit more here, some on the sides." "But it's really subtle." "My whole body is changing slightly." "My weight's redistributing;" "my hips are getting smaller and my shoulders are starting to get more broad, and I am starting to get more shoulder muscles, which I haven't been working out a lot, so it's clearly not from what I've been doing." "And those physical changes are having an impact on his running." "He's a full minute faster than when he was a woman." "Exactly 10 minutes" "There's no doubt that testosterone can change the body." "But what effect does it have on the brain?" "Anyone who spends time with children is well aware that boys and girls tend to behave differently and play differently." "It's always been assumed that these differences are largely driven by cultural and social pressures." "But there's mounting evidence that this doesn't explain everything." "Scientists are only just beginning to understand the role biology plays in shaping children's behaviour." "There's no question that children themselves know from a very early age what separates the boys from the girls." "We don't like running, we like being gentle." "We can play rough all the time." "Girls put on make-up and boys don't." "My daddy always drives." "When boys do naughty things, then we will do naughty things." "Play behaviour fascinates scientists like Melissa Hines." "She's one of the leading figures in a unique long-term British study following children as they grow up." "The study is examining all aspects of developmental behaviour and has followed 14,000 mothers and their children for the last ten years." "And it's uncovered intriguing evidence about biological influences." "The early indications are that testosterone influences play behaviour." "Boys and girls play differently because their brains are sexed differently." "Just like the body, there are parts of the brain, not the whole brain, but certain parts of it, that have protectors or receiving units for hormones, including testosterone." "And in other species, including non-human primates like rhesus monkeys, hormones programme development of these brain regions." "If that's the case, what would testosterone do to a female brain?" "Can the apparently cultural phenomenon of the tomboys be explained by exposure to higher than average levels of testosterone in the womb?" "There's some evidence that high levels of testosterone in the womb are one factor that influences the development of play behaviour in human beings." "We know, for instance, that girls exposed to higher than normal levels of androgen the male hormone - pre-natally, on the average, show more male typical toy choices, like to play more often with boys," "and show male typical activity patterns." "If that's true, it will be fascinating to see what effect testosterone has on Max Toth." "Well, remember six months ago," "Max was tested and had his brain scanned by Doctor Ruben Gur." "Today, Max has come back to be re-tested, to see if there have been any changes in the way that he thinks." "He'll repeat the tests he did in the brain scanner to see if the testosterone he's been taking has produced any alterations in the structure and function of his brain." "The next test is called finger-tapping." "Alrighty?" "He'll also repeat the other tests he did when he was a woman, like finger-tapping." "Men tend to have better motor skills and can, on average, do more finger taps per minute than women." "Men are also stronger, and better at manipulating objects in three dimensions." "Women, however, tend to have better verbal skills and better visual memories." "These are standard scientific tests and will show if, mentally," "Max has become more like a man and less like a woman." "What I would expect to find is improved performance on functions that males on tasks where males do better, and worsening performance on tasks where women do better." "I know they've never really studied this before, and I'm interested to see if there is any difference because, you know, I've heard about the androgenising effects of testosterone on the brain, so I'm interested to see well, is anything changing." "But I'm fairly dubious that anything will." "The first test measures Max's emotional response to a series of faces." "The machine takes pictures of Max's brain activity as he looks at faces, which can then be compared with his emotional response when he performed the same test as a woman." "The results are startling." "What we are seeing really is a is a female brain turning into a male brain." "It was quite - quite amazing to see it in a single individual." "This is a scan of Max's brain when he was a woman." "The red areas show which parts of the brain are used when trying to read emotions." "And this is a scan of Max's brain doing the same task, but as a man." "The more red in the scan picture, the harder the brain is working." "As you can see, he found it much easier to read emotions when he was a woman than he does now." "Woman." "Man." "Woman." "Man." "In his case, the second time he had more difficulties with the task." "He had to put in more effort in order to perform that particular -that particular task." "So his - his brain responds more like a male brain to the task of trying to distinguish the emotions." "But how did Max do in the practical tests?" "All the changes are in the direction that we expected, in terms of becoming more masculine." "So remember the finger tapping?" "Uh-huh." "You managed to squeeze in another three taps per minute." "Whoo-oooh!" "Max is also much stronger." "You pushed another four kilos." "So that's -that's a significant..." "His spatial awareness has dramatically improved." "Last time you did 75 correct, this time you did 118 correct." "And that's pretty much the end of the good news." "Right." "Because with becoming a male you also lost a little bit." "Max's visual memory has deteriorated, and he's not as good with words." "I was actually surprised." "I didn't..." "I" " I was thinking maybe one or two tests will change, and this is, after all, a fairly brief period of time." "You would expect changes on those tests to take place over a longer period." "Max is still sceptical about the extent to which testosterone has changed his brain, but acknowledges that it has affected how he feels." "My body is changing, and it has been surprising to go through that." "It's been, you know, kind of exciting, and there were changes that I wasn't so, you know, that I didn't expect to go through." "There was a period of time where I really had trouble crying." "And it felt biological to me." "And by that I mean I've gone through different periods in my life where I had a harder time crying and had an easier time crying." "And this was the first time where I felt like I really wanted to cry and, like, there was something biochemical preventing me from doing it." "Like, it really felt like a big block." "And that was kind of a scary moment for me." "For Max there's now no going back." "As you can see from this time lapse sequence he's already undergone remarkable changes in just six months." "In another year he will look like this." "Further down the line," "Max might consider having surgery to enhance his masculinity." "But for now, he's happy with what testosterone alone has done." "I'm very excited." "Like, I didn't think I would be that excited about it." "But the way that my body is changing shape, the way that my fat's redistributing, that my shoulders are getting broader, the facial hair, it's really exciting for me." "Like, it's starting to feel much more comfortable for me to be in my body." "And even some of my friends have noticed, they're, like, wow, you're much more comfortable." "And I just present more comfortable and more confident because I feel better." "Manipulating sex hormones has allowed" "Max Toth to make a choice about his gender." "But science is only just beginning to explore what can be done to humans." "Manipulating DNAto build super athletes or even radically redesign humans may be a long way off, but the future has a way of arriving faster than we imagined." "The question for society in the 21st Century is no longer what can we do, but how far are we prepared to go." "Next week - ageing." "Thanks to recent advances in molecular biology, it's now possible to explain exactly why we age." "Scientists have now identified the rogue elements that cause ageing and have developed drugs that, for the first time, truly extend life."