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If living through puberty feels like a horror story, the villains of the piece are hormones. These tiny chemical messengers are beyond our control. Suddenly hordes of them start racing through our bloodstream, ordering our bodies to change. They tell us to switch on to sex, getting us ready to make babies. They tell our muscles and bones to get bigger and stronger. They make hair sprout in unusual places. Sometimes they really let us down. Amazing though it seems, hormones will affect our brains, too. They'll make us think about new things. We'll think about them in a new way. The result in the emerging adult is confusion and defiance. We followed a group of teenage boys in California, and we've done something unique. For a crucial eighteen months of her life, we've watched and listened as a British girl goes through the ups and downs of adolescence. Now, she's on the threshold of adulthood. But when we first met she looked and felt very different. My name's Beatrice. I'm twelve years old. My birthday's in November. My parents are divorced and I live with my mother and stepfather. Human beings are unique in the way they linger as children for an extraordinary long time. If Beatrice was any other animal, she'd have stopped being a kid a long time ago. It's a bit of a puzzle, because other animals mature very differently. Wherever you look in the world, all children have to learn the skills they need for survival. Not just the obvious ones, like making yourself understood, but the things we don't even think of as learning at all, like walking and controlling our bodies. As children, we can learn faster than we'll ever be able to again. Magnified ten thousand times, this is a single human brain cell. Your brain has a hundred billion of them. Every one is connected to thousands of others through their tiny branches. Each join adds a little bit more to the intricate picture of who we are. As children, the connections are still being made. Like a plant exploring its surroundings, brain cells like these are growing their branches, constantly reaching out to each other. Learn to ride a bike and you wire up a tiny part of the brain. Learn a new word or how to catch a ball, and you forge new links. And with difficult tasks, like writing, it's only by doing the same thing over and over again that the connections are made strong. In the end, they take root and stay with us for the rest of our lives. But though learning is so vitally important, there comes a time when our bodies have to move on, and the rollercoaster of puberty lurches into action. We don't know what exactly decides when that should be, but we do know that when it starts it's the brain that's in control. Peering deep inside the head, you can see where it all happens. For example, adrenalin makes you run faster just for a moment, but the hormones of puberty change your life forever. This system is so sensitive that even minute amounts of hormones make massive changes. If my taste buds were as sensitive, I'd be able to detect a pinch of salt in a swimming pool. You can't see hormones in the blood, but take them out of the body and they're suddenly revealed. Each one is a uniquely-shaped molecule which, like a key in a lock, can fit into specific receptors all over the body. They're subtle and they're in control... and at the start of puberty they come out at night. In the restless nights of early puberty, Beatrice's brain dispatches its chemical messages every ninety minutes... and her body listens to the signals carried in her blood. Not just to the amount of hormones, but to the patterns of their release. In a boy, it will be the testes that pick up the signals. In Beatrice, it's her ovaries. Circulating everywhere, from head to toe, these are the real heavyweights of puberty. They make the rollercoaster an unpredictable and emotional ride. Some days you feel like you're the bomb, like everything in your life is going great, you can't expect anything more. And then it feels like you're nothing, like you've made mistakes that it's over and stuff that you might as well give up and then it goes back up and then it goes back down. It's always up and down, up and down. It's never a straight line or inclining up, it's always bumpy. Beatrice, too, can't control the journey she's on. Biology has taken over, and the hormones inside her have reached critical levels. Her body is now being rebuilt around her. I don't like the physical side of it. I just wish it appeared one morning, but then that would be a bit awkward. Your upper body begins to... You get pubic hairs and that's a right bummer. And then you, I don't know, you get larger in different places and smaller and whatever. It's those hormones again, which arrive in very different combinations. Girls' bodies are flooded with estrogen and their chests respond. Across the world, there's a huge variety of size and shape, but every woman's breasts go through the same stages of development. First, the cells which will eventually make milk ducts start dividing. The dark area around the nipple begins to grow. Within months, the breasts start expanding. Fat is laid down as the adult shape forms. It'll be around four years before the skin around the nipples lies flat, forming the smooth contour of the adult breast. It's painful to run, let me tell you that. Because what happens up above, you have to start wearing a bra. Sorry, had to mention it. It gets really painful to run. Bras are really, really uncomfortable. It's just like having a strap put across your chest, permanently. But just getting breasts is not the end of the story. They will grow again during pregnancy and only after a woman gives birth will they be fully mature, when in most cases they start producing milk. While a girl's body begins to change shape, a less obvious, but more important transition is taking place deep inside her, in her ovaries. The size and shape of a walnut, these two off-white organs rest either side of the pelvis. Not only do they produce the hormones that drive puberty, but they contain the raw material of new life - a woman's eggs. More than a hundred thousand in each one. From puberty, once a month, one of these eggs will be set free. Carried inside the Fallopian tube, it takes the egg three days to make the 15 cm journey from ovary to womb. Meanwhile, the womb prepares for a possible pregnancy. Its lining thickens, ready to be home for a fertilized egg. This is it, ten thousand times larger than real life. A strange and dramatic landscape. They show the lining, unused, beginning to flow away. In her period which follows, the average woman will lose an eggcup-full of blood. I don't want to get periods. I'll tell you why, because people tend to get moody. One of my friends has got her periods and she gets really, really moody. And some people get pains and I don't know if I will. I hope not. I don't like the idea of getting my periods or whatever. Like it or not, once the rollercoaster starts, there's no stopping it. With hormones pulsing through her every day, Beatrice's body races ahead out of control. Yet it can all seem painfully slow. You know, I wish, I just really wish that it just appeared one morning that you went into a little cocoon and woke up and it was all there. And you were used to it. Not it happens over three years. Or four or five or whatever it is. One of the things I like, everyone used to be taller than me. Now, lots of my friends are still taller than me, but mostly adults are really short. I like the fact I'm taller than a lot of people, and being bulky and big, too. Boys' bodies too, are growing faster than at any time since they were toddlers. It's easier to develop your body, too, when you're in puberty. When you're little and you work out, it doesn't show up so much. It takes less. You start eating a lot, you eat a lot. Then you start getting bigger and you feel other things getting bigger, so you feel manly. All the changes they experience are driven by their own sex hormone, testosterone. And it's made in the testes. As puberty starts, the testes begin to grow. It's the first outward sign that anything is happening. The skin of the scrotum gets rougher and there's a wispy growth of pubic hair. Inside, the testes are a tangle of tiny tubes, miniature factories that will soon start to churn out sperm. And they'll do it on a massive scale. A thousand every second. Shortly after the testes start growing, the penis itself starts catching up. The skin gets darker, and in four years the machinery of reproduction is complete. With a special camera that shows heat as colour, we can see why the testicles are where they are. The red and yellow of the tummy show that it's hotter than the bits coloured green and blue. Sperm factories work best when slightly cooler than the bulk of a man's body. Hanging low keeps them cool. And it's now, of course, that the penis starts getting up to some new tricks. I had one first erection when I didn't know what it was. Then I had a first erection where I knew what it was. One that I didn't know what it was... That's the first one. The first one, you didn't know what it was? I'm sitting and I have to use the bathroom. I really had to piss, 'cause I didn't know what it was. Inside, the penis is made of a spongy tissue filled with thousands of tiny blood vessels. Normally, blood flows in and out at a constant rate. During an erection, blood flow increases dramatically. Blood vessels at the base of the penis are squeezed. Blood still flows in, but it can't get out. Pressure builds up. The thermal camera shows the heat produced by all that extra blood. And, to the horror of its owner, the penis seems to have a mind of its own. I don't like it when you get an erection in class. You're sitting like... So you try and hide it. I try and tuck it under my belt. Yeah? I fix it up and try to hold it down. These involuntary stirrings happen as the body learns to control its functions. But there's still one more surprise in store. It was in sixth grade, I was watching TV one night and I saw this foreign girl, and it was some movie where there was this really nice-looking girl, and I thought she looked good. I dreamed about her and I woke up in the middle of the night, and something was wet on my pants, on my boxers. I had Sex Ed a little before that so I knew then I was OK. I'm ready to be a man! Now I gotta clean it up. And change my boxers. That shit's sticky! Not on my bed, just my boxers. That's horrible! This is a view inside the sperm ducts. It's unlikely that the boys' first wet dreams contained any sperm at all. It takes time for the machinery of production to crank up. And the first few times, it's firing blanks. Even when the system kicks in, most of the fluid isn't sperm at all. It's a liquid which both protects sperm from the acid of a woman's vagina and gives them energy for their long swim ahead. But once the sperm factory is up and running, there's no going back. A man will go on producing sperm for the rest of his life. Quite apart from the physical transformation they bring, hormones trigger a much wider change. They influence teenagers' whole outlook on life. My mum says that I wear too much black. How can you wear too much black? I think the tie-dyed, try on the smallest one. For Beatrice and her friends, this means experimenting, learning to take charge of their lives, trying out attitudes and opinions to see if they fit. You might as well wear a couple of wires joined up. Might as well wear a bikini. It's basically see-through. I don't know why they have so much decoration. This might seem extremely sad, but I like that. Just as the body is test-driving its systems, the brain is beginning to explore its new world. She's become, since the summer, significantly more independent, but still likes to have us around, I think, in the background so we're there, but she's doing her own thing, so she's got some safety, I suppose. OK! What do you think? The top, not the skirt, the top, not the skirt? She was very proud of me because I caught the train by myself to Southampton. And it was a big achievement. She's quite testing in the sort of questions she asks and her opinions. She's got lots and lots of opinions about things that all come from outside or come from school, and that's all quite different. Teenagers, notoriously, want to break free from their parents. Their rebellion can cause pain all around. But now I have a lot of stuff to worry about in life and stuff - girls, parents, teachers, and school. So that's a lot of difference. When I was eleven, I had more people watching me and making choices for me or with me. Now it's more by me, with a little help. In future it'll be by me. Many of the changes in puberty are quite subtle. But one is blindingly obvious. We just grow much bigger. And how that happens is really rather surprising. To reveal the secret of how we grow, we need to look at my own bones. This scanner produces a magnetic field ten thousand times greater than the Earth's. Enough to see right through me. My hand and wrist are an intricate mesh of tightly-packed bones. If you could have seen them when I was a child, they would have been very different. This X-ray study is unique. And going backwards over twenty years reveals a remarkable thing. The hands of children are not all bone. There, for instance, no knuckles. And there, look at the gaps in the wrist. Instead of bone, there's cartilage, something the machine can't see. Only when cartilage turns into bone can the hand grow. And how does this happen? It's hormones again. Puberty pumps them out and joints get bigger and limbs get longer. By the end of our teens, there is no more cartilage and there can be no more growth. Boys and girls have two distinct periods of growth. When we are children, our bodies grow in a more or less constant way. Boys are generally no taller or stronger than girls. But at puberty all that changes. James and Annie are brother and sister, but James, a year and a half older than Annie, is a good ten centimetres shorter. A lot of my friends are shorter than me, but a lot are the same height. So, I'm not exceptionally tall, and he's not tall. He just doesn't grow. Shut up! You don't, you look freaky. You've been that height for about a year. What makes Annie taller at the moment is that girls get their growth spurt at the start of puberty, while boys get theirs at the end, which could be as much as three years later. The hip bones spread outwards and become flatter. But more important is what happens to the space in the middle. It opens, ending four centimetres wider than in men, just enough for a baby's head to squeeze through. The changes in a boy's body stem from his need, in times gone by, to be strong. The testosterone in his system has dramatic effects. His heart and lungs get bigger. With each breath, more air travels down his windpipe. Through a mass of tubes, it ends here, in the three hundred million air sacs that make up his lungs. Oxygen passes through the membranes and into his blood.
Puberty Raging Teens annotations
The more that gets to his muscles, the faster he can run. At the same time, the mechanical parts of his body are adding to his power. Here we can see the complex array of muscles and tendons that hold the knee together. Watching how they move reveals how impressive the human body is. The two bones don't actually touch. The soft tissue between them allows them to move in a smooth and precise way. This whole physical system gets better as muscles and tendons grow larger and stronger.
Puberty Raging Teens remarks
There's another change at puberty that you can hear easier than you can see. But I'm going to try and show you with this. Looking across the tongue and down the throat, these are vocal chords. The whiter bits in the middle make sound, vibrating furiously when air flows past. I can alter pitch just by changing the tension of the chords. Tight for high notes. Slack for low. In boys, the whole set-up grows. You can see it from outside. It just happens. With all those hormones wreaking havoc inside us, the body chooses now to confront us with one of life's trickiest challenges.
Puberty Raging Teens quotes
Sex! I want you to tell me the first thing you think of when you hear that word, sex. Just shout it out. Steve? Boys and girls. Love! Why is that the last thing some people think of, instead of the first thing? Good question. The answer seems to be that teenagers' physical development runs ahead of emotional maturity. The body has sexual urges that the mind can't deal with. And while it's catching up, there's plenty of scope for turmoil. Guys shouldn't be as nervous as some are towards girls, because girls in the long run want the same thing. And so they should be more outspoken, and should just come forward and say what they feel and say what they mean. I think first of all, it's physical. I think that's what you notice first. You don't look inside a girl and say, you'll look at her because you like what you see. I think after you go out with them for a couple of times, and you get to see what they're really thinking, that's when you decide that's the girl you want.
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