Inside The Human Body (2011) s01e03 Episode Script
Building Your Brain
MICHAEL MOSLEY: This man is blind.
Yet he can climb the world's most terrifying peaks.
These fishermen can see underwater better than almost anyone else on Earth.
And this delightful young girl is alive and well despite having just half a brain.
Their stories are part of YOUR story .
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the story of what makes YOU human.
Hidden deep under your skin is a wonderful inner universe .
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a place of raging torrents, electrical storms .
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and triumph against the odds.
This is a fantastic voyage through the most extraordinary organism on Earth.
You.
Strange as it might seem, this bizarre-looking creature is you.
Or rather, what you look like just three weeks after your conception.
This was when your brain was born.
It was the start of an astonishing transformation .
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as you went from a small handful of brain cells .
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to the exquisite network of a hundred billion brain cells that you carry around inside your head.
We call this transformation childhood BELL RINGS .
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and humans enjoy one of the longest childhoods of all.
This is New College Oxford.
I came here when I was 18 years old, and over the next three years I would become, in many ways, a completely different person.
On the outside, I had finally grown into a man.
Yet inside, my brain was anything but finished.
I first fell in love here, I had my heart broken here, I changed almost everything I believed in.
I want to show you why it took me, and you, so long to grow up.
It's a story of the biggest wiring job on the planet.
As your brain first plugs itself into your body .
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and then grows, fed by the stream of information that's rushing in through your senses.
It is so sophisticated that it takes nearly 20 years to mature.
20 years to go from the helpless baby to the proud possessor of the most sophisticated thing in the known universe.
In the womb you grew 8,000 new brain cells every second.
By the time you were ready to be born you had all the brain cells you'd ever need.
But this baby is about to experience the shock of her life.
Come on, big, big push.
Big push.
Push down.
SHE SCREAMS Don't scream, just push.
Get angry and push down into your bottom.
Come on.
Push.
It's got hair! What time is it? It's, er, about This is Phoebe.
As she emerges, her eyes are dazzled by light.
She's come from a gloomy, watery world into a bright, noisy room.
It's time for her to meet Mum and Dad.
Oh, that was that was pretty difficult.
Yeah.
And hot.
MIDWIFE: I think we gathered that.
And painful.
Andthere is a reason why it's "labour"! Phoebe's brain is being flooded with new sensations.
The chill of the room.
The smell of her dad.
Hello.
And, most puzzling of all, the strange images that are pouring in through her eyes.
The lens that lies in the centre of the eye can't focus on anything for long.
Even so, newborns recognise their mum's face after just a few hours.
At the back of the eye is the red plane of your retina.
Here, light from outside shines down, casting images across the surface.
Underneath, these rays enter a dense forest of 125 million light-sensitive cells.
These rod cells each detect just a tiny part of any image.
They send these fragments to your brain, which has to piece it all together.
BIRD CALLS It's your rods which enable you to see in the dark.
I think it's a strange thought that your rods were actually active when you were in your mother's womb, so when you were looking around in there, what you were seeing was a black and white world.
Your rods are so sensitive they could detect the dim light that passed through your mother's belly.
They were training your brain to see long before you were born.
I love that feeling in the morning when the sun's rising and the whole world is coming back to life.
Dawn lush, bird beautiful, you can feel your soul really sort of rising and singing along.
On a sunny morning, light levels rapidly increase a million-fold.
And like the moment of your birth, this bleaches out your night vision.
And a whole new set of cells are about to spring into life and they're going to inject colour into your world.
They are the cone cells.
You have a richer experience of the world than most other mammals because your cones detect not two but three different colours.
In one location, they begin to group together, causing the retina's surface to bulge.
Year after year, they continue to rise, creating a volcano-like structure.
It's not until you are four years old that the mound is finished.
This is your fovea.
It's the only part of your eye where your vision is crystal clear and, thanks to your cones, capable of sensing millions of different colours.
But the complexity and the beauty of the human eye is nothing without your brain.
You blink up to 20 times every minute.
Each blink lingers for less than half a second.
But add all those blinks of an eye up and you're living in the dark for over an hour every day.
Your brain is so good at filling in the gaps .
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you're not even aware of it.
Your eyes are an extension of your brain.
They are so adaptable that you can learn to see in places where human eyes normally struggle.
This is the remote Thai island of Koh Surin, home to a group of sea gypsies known as the Moken.
To survive, they've become expert underwater foragers.
Finding food underwater is difficult .
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particularly without goggles.
That's because our eyes have adapted to see clearly in air.
In water, the world becomes blurry.
As you descend, light levels drop quickly.
Your eye reacts by opening the iris, making the pupil larger and allowing more light in.
The image becomes brighter, but underwater, a larger pupil also makes the image more blurred.
But Goon has learnt how to overrule this automatic reflex with an astonishing adaptation seen clearly with the help of an infrared camera.
Instead of opening his pupils, he closes them as far as they will go.
This means Goon can see twice as well underwater as you or I.
Recent studies suggest that any child can quickly learn this trick.
The Moken show how well the human brain can adapt the body to suit its needs.
This adaptability has enabled our species to thrive on all seven of Earth's continents.
Hey! MAN: Rrrr! But at three months old, Phoebe's brain is still hopeless at pretty much everything.
Hey! Hey, Phoebe! It can tell her mouth to suck but can't feed itself .
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can't maintain body temperature .
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can't even control when she goes to the loo.
I now am utterly and totally responsible for another human being who has to take priority over my life in everything.
She has to come first, otherwise she can't survive.
Phoebe is so very helpless because her brain is still getting organised.
Bit by bit, her brain is creating her mind.
This remarkable time lapse shows living brain cells sending out tendril-like arms, which connect with each other.
Each of Phoebe's hundred billion brain cells will, on average, make 10,000 different connections .
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and we can follow this on the outside.
Oh, I've gone away! At six months, Phoebe thinks that when she can't see someone they vanish from the world entirely.
I'm here.
Ya-a-a-a-a-ay! Watch Phoebe's face as Charlotte hides.
Now you don't see me.
She immediately loses interest.
Where's Mummy gone? Where's Mummy gone? Shall I come back? But when her mother reappears I've come back! .
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her delight is obvious.
I'm here! Yes, I am! Going to come back, I'm here.
Where's Mummy gone? Three months later, and Phoebe's brain has now learnt that just because something is hidden doesn't mean it's disappeared.
Here I am! Yes! A childhood game of peekaboo has helped her build connections that will stay with her for the rest of her life.
And the longest connection Phoebe's brain will ever make is the one between her head and her toes.
Remarkably, the connection between your head and your toes won't be fully mature until you are three years old.
Long before that, your brain cannot resist the urge to take its first big step.
Standing up feels easy, natural, but learning how to do so was hard - really hard.
Today I want to try and recreate that challenge, that problem that we all had to face and overcome when we took our first steps.
Soahh! Young babies doing first steps.
Indeed.
I'm going to give you a little bit of a hand with this stick.
Excellent, good.
Right 'Like all beginners, I need a helping hand' Keep walking forwards.
It's going to get wobbly.
Andwhoa! That's it.
'.
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not from my mother, but tight-line walker Alana Jones.
' First steps, it was all right.
But that's only because I was holding onto you.
Keep going, keep walking.
Keep walking.
Keepwalking! Whoop! The thing about this is it's fantastically hard because you are using something like 54 different muscles in your leg but at the same time, you require at least 640 muscles of your body.
'And all of these muscles are being directed 'by a bizarre part of your inner ear.
' This cavern is buried deep inside your head.
It's part of a labyrinth of twisting tunnels completely submerged in fluid.
The tunnels are the three great loops of your semicircular canals.
Inside each loop there is a saddle-topped fleshy mountain, your crista.
LOW WHOOSHING OF LIQUID The mountain slopes are covered in a thick forest of tiny hair cells.
For the moment, they lie still.
But this inner sea never remains calm for long.
ROARING, THUNDERING GURGLING As you move your head, it generates a shock wave, which races through the tunnel and pummels the mountain.
On its flanks, the hair cells are thrown about in the turbulent waters.
The pressure builds .
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until electricity flows .
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creating a powerful electrical current.
All this activity going on inside your semicircular canals creates your sixth sense - your sense of balance.
Take your back leg off.
Off, off, off.
Oh Oh Good.
And again, off.
Good.
And again.
Whoo! Yes! INSECT CALLS AND BIRDSONG GOATS BLEA Learning to balance and coordinate your body is so complex that the area of your brain devoted to this one task involves as many cells as the whole of the rest of your brain put together.
Some people learn how to walk sooner than others.
But there is a place where people pull off this feat sooner than anywhere else.
LOW HUM OF CHATTER This is Kaumba.
She is mother to a baby girl called Kosini.
They live in Rhumsiki - a tiny village in the remote northern highlands of Cameroon.
Here, mothers are keen to get their babies off their backs and walking as soon as possible.
Ever since Kosini was a month old, her mother has repeated the process of "kitete" which means to make jump.
Every day, she takes hold under the arms and bounces her.
Kosini responds with a kind of stepping reflex.
You had this reflex, but it disappeared after a couple of months.
But here in Rhumsiki, this daily encouragement means that the reflex remains and gradually develops into mature walking.
Now she's seven months old, it's time for Kosini to try and stand up by herself.
WOMEN CHATTER So her mother sets about another ritual practice.
She washes her with a warm herbal liquid.
This seems to stimulate her legs, preparing them for walking.
The leftover warm leaves are laid on the ground and Kosini is placed on them.
It's uncomfortable and she soon wants to get off KOSINI GRIZZLES .
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giving her the gentle encouragement she needs to use her legs.
These rituals seem to be accelerating the connections that Kosini is making between her brain and her feet.
So by seven months old, she's ready for her first steps.
To walk, your brain has to sense when you are overbalancing to one side .
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and then instruct your body to shift your weight back to the centre.
All of this has to happen within a fraction of a second.
To begin with, it's a real struggle.
But Kosini's half-brother, Tisema, is already a master of bipedalism.
He is just ten months old.
At his age, my children were still shuffling around on their bottoms.
From now on, and for the rest of Tisema's life, walking will be automatic.
The first year of life is a critical period for your brain .
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because at this age it's an extraordinarily adaptable and efficient learning machine.
He's down at the bottom, isn't he? And each new skill you acquire is shaping the way it grows.
Right at the back here is an area called the visual cortex, that processes vision.
The left side of your brain is learning how to control the right side of your body.
That's it! So Henry's right hand here is being controlled by the left side of his brain and vice versa.
I think Tom's not entirely sure, but he's got lots of speech, lots of verbalisation, and that also Ah .
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tends to be on the left hemisphere.
Ah Ah! That's right! The different parts of your brain are becoming increasingly specialised.
Some of this development is pre-programmed by your genes.
But there's an awful lot that's also shaped by the everyday experiences that these little toddlers are going through at this moment.
The interplay between the genes you inherit and what you experience means that no two brains are ever identical.
It is the incredible flexibility of the human brain which gives it its power and enables the brain to respond to almost any challenge that the world throws at it.
That's a big one.
Is he coming round again? Uh Yeah, darling? Can you see the fishes? Look at these little ones.
Can you? Are they pretty? Yes, Mummy.
Angelina is a rather remarkable one-year-old because she was born with just half a healthy brain.
She has a rare disease which affects the blood vessels on the right side of her head.
She's a happy, active little girl, but every now and then Angelina? Angelina? SHE CLAPS Angelina? Angelina? SHE CLICKS HER TONGUE You all right? OK? HE CLICKS HIS FINGERS Angelina's having what we call a complex vocal seizure.
As you can see, she was very, very active and now she's gone very distant.
One indication is that her head lags.
She's slightly heavy in her breathing.
Angelina has a rare condition, Sturge-Weber syndrome.
This one is going on quite a bit, isn't it? Angelina? Angelina? Her parents, Lisa and Stephen, have had to deal with her seizures ever since she was born.
Angelina's brain scans show the cause - abnormal blood vessels, seen here in white on the right side of her brain.
But they also show that the left half of her brain is perfectly healthy.
There is a treatment for her condition, but it involves radical surgery - cutting off the damaged half of Angelina's brain.
We're in a position we don't know what we've got to face after this operation.
I pray to God she comes back to us at all, but what she does come back as, we accept.
MONITORS BEEP The surgeon who must navigate his way through Angelina's tiny brain is Mr William Harkness.
We've lifted the bone flaps so we've made our trap door in the skull.
And now we're beginning to see the brain.
It seems impossible that you can disconnect half of someone's brain and expect them to recover, yet that is exactly what the surgeons are hoping will happen.
Because the brain does adapt at this age of life, we would expect most of the functions to transfer to the other Other side of the brain.
It takes four hours of micro-surgery to find the bridge between the two sides of Angelina's brain.
And this is what's called the corpus callosum .
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which connects one side of the brain to the other.
Now, he cuts through it.
Angelina's healthy brain is finally free from the disruption caused by the damaged right half.
Hopefully, if this child becomes seizure-free, I think that we will have given her the best opportunity for the future because the type of epilepsy that she had clearly is life-threatening.
Angelina? She's so sleepy.
I haven't even given her a kiss yet.
Haven't you? No.
Come here, lovely.
Come on, my darling.
Hello, sweetheart.
Who's a strong little girl, eh? Who's Daddy's strong little girl? You have a nice dream.
All her parents can do is wait and hope.
It was essential for Angelina to have the operation at this age because after your first birthday your brain loses some of its flexibility.
EXCITED CHATTER AND WHOOPS While there's still room for plenty of development, there's less scope for fundamental change.
It becomes increasingly unlikely that you would make a full recovery from an operation as dramatic as Angelina's.
That's why the surgeons operated on her so young, they've given her the best chance she will ever have of being up and toddling around like any other one-year-old.
As your young brain starts to explore the world from its new, lofty position, there is an immediate and rather wonderful consequence.
# Girl, you got those hands # That heal # Help me get in touch with what I feel # Cos you understand # That's because walking releases two powerful natural tools - your hands.
I've kind of developed a skill with my hands that when I touch things, I get information from it.
A bit more than an average human.
From a young age, street magician Dynamo has been fine-tuning the control of his hands.
If I put a pack of cards into your hand, you'd just feel the edges of the cardboard, right? Whereas I can actually feel how many cards there is in the In my hand.
I've built up, you know, a sense that allows me to do it.
His hands are so nimble your brain cannot keep up with them.
HE CHUCKLES Just take a card out.
OK.
I'm going to turn around, just show it to the people.
HE MOUTHS Yep.
Got it? I'll take it back.
Yeah.
I'll do this slowly.
I'll put it about halfway down, yeah? Yeah.
It's fair, right? Yeah.
Put your hands like this.
Really concentrate on the card.
Look at me a second.
Watch.
HE LAUGHS One card jumps up.
HE LAUGHS That That was good! That was That was very good.
Can you do it again? Your hands' versatility springs from a mixture of strength and sensitivity.
At the tip of each finger is the densest collection of nerve receptors found anywhere on your body .
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feeding your brain with information about the temperature, pressure and vibrations of anything you touch.
They're so sensitive they can detect lumps and bumps less than a 100th of a millimetre across.
I've got some cards here, are they all different? Yeah, they look all different.
See that? Just hold your hand out.
Mm-hm.
What card is that? Five of hearts.
Five of hearts? Can you see that? Five of hearts.
Yeah? I'll place that on there, put your other hand on top so it don't blow away.
Yep.
Perfect.
So you've got the five of hearts.
I've got the five of hearts.
I'm going to take the Let's have a look.
Yeah, I'll take the next card, the queen of spades.
Yeah.
Yeah? Can you see that on camera? Yeah? Yeah.
Queen of spades, five of hearts.
Watch.
One, two, three, four.
HE CHUCKLES Very good.
I've got the five of hearts now.
Right, I've got the queen of spades.
That's clever.
Your hands allow your brain to reach out and change the world.
As a result, our species is the only one to have built a civilisation.
Standing upright and walking releases the potential of these wonderful flexible hands, and it's followed soon afterwards by another milestone, the development of an ability which is uniquely human.
One that I'm demonstrating right now.
It's the ability to talk.
From an early age, Wendy Vo's brain has been bursting with languages.
When I was one, I spoke Vietnamese only, like, it was just like baby words.
When I was two, I spoke English, Vietnamese, Spanish and Chinese, so four languages when I was two years old.
Well, I started learning them.
She hasn't stopped at just four languages.
Wendy spends an hour every week talking to a range of different people in their native tongues.
I am Winita from India, and I teach Wendy Hindi.
HINDI DIALOGUE My name is Rashida and I teach Wendy Arabic from Yemen.
ARABIC DIALOGUE And I teach Wendy Spanish.
She speaks Spanish a lot better than some Hispanic kids do.
WENDY SPEAKS SPANISH At the Russian languages, she is very good.
RUSSIAN DIALOGUE Portuguese PORTUGUESE DIALOGUE She is at the top because she can switch veryin few seconds, from one language to the other one.
FOREIGN DIALOGUE And she can think, speak, write.
It's unbelievable.
Vietnamese, English, Spanish, Chinese, French, Japanese, Hindi, Arabic, Russian, Cantonese and Portuguese.
Add them all up and Wendy has 11 different voices packed inside her head.
But speaking is only half the story.
ECHOING VOICE For meaning to fly from one person to another, the words have to travel deep into your body.
Inside your ear, sounds set off a complex chain of events.
They enter as pressure waves, which push and pull your eardrum, making it vibrate.
LOW RUMBLING On the other side of the eardrum, these vibrations set a series of bones jiggling.
RUSTLING They end with the smallest bone in your entire body, called the stirrup.
It is smaller than a grain of rice.
These bones allow you to hear.
If a sound is too loud ECHOING VOICE .
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a muscle pulls the stirrup away from the most sensitive parts.
Temporarily, at least, you go a bit deaf, but the rest of your ear is protected.
Beyond the stirrup is a fluid-filled cavern, your cochlea.
The incoming sound waves tickle clumps of tiny, hair-like sensors on the floor.
These begin to dance to the sounds of the world outside.
You have 30,000 sensors.
Each picks out a different part of the sound and sends it straight to your brain.
The cochlea is most sensitive to the sounds of another person's voice.
# Aha aha aha # CHILDREN CHATTER SPEAKS RUSSIAN RUSSIAN DIALOGUE # Da da da # Finely-tuned ears and a wonderfully versatile voice # Da da da # .
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have allowed humans to invent over 7,000 different languages.
# Da da da # SPEAKS IN FOREIGN LANGUAGE THEY GIGGLE Hello! Bonjour VARIOUS FOREIGN LANGUAGES And each of us, as we grow, pick up over a thousand new words every year.
SPEAKS IN FOREIGN LANGUAGE By your early teens, you have a working vocabulary of over 10,000 words, as you head towards the brain's next challenge - puberty.
I've got three kids at home.
There's Kate, who's 11, and she has yet to go through puberty so she's still a sort of cheerful girl.
I've got Jack, who's at the other end, and he's 18 and he's rapidly becoming an adult.
And then there's Daniel, in the middle, who's 16.
And Daniel is interesting because he has absolutely shot up recently.
He has changed a lot in himself.
They way he behaves.
Most obviously he hates going to bed.
Bedtime.
No, come on! Seriously, a couple of minutes.
And he's become much more fashion conscious.
What do you think about the buttons? Oh, yes.
THEY LAUGH Boring.
Living with puberty is all about living with change.
I think red's a lot better.
Red suits your skin colour a lot more.
And while hormones, those glandular bringers of pimples and sexual stirrings, can explain some of Dan's behaviour BOYS CHATTER .
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the true source of his transformation lies way north of his gonads.
Do you know what this is, what I'm looking at here? A brain? It is a brain indeed.
It's orientated this way so the eyes would be there, OK? And this is actually a scan, which is a mixture of about 1,000 brains.
OK.
And what they did is they filmed, um Wow! .
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kids from the age of three through to about 18.
This image allows us to see, for the first time, what really happens to the brain as it matures.
The colours represent how densely packed the particular part of the brain is.
Red and yellow means loads of active brain cells and connections.
Blue and green means far fewer.
So what would we expect to see? Um, more red over time, presumably? Yeah.
As new pathways are made.
Because, like, brains grow.
Brains grow.
OK.
Let's actually see what happens.
Here we go.
We're now up to about Kate's age.
Not a lot of activity happening, a little bit more blue.
And then we're hitting your age, Dan, what do you see? Wow.
A lot more blue, yeah.
That's quite cool.
That is not what I thought, it's really weird.
From Kate's age onwards, what we see is actually brain connections are dying off much more rapidly than they're growing.
So it's just downhill from Well, it's not downhill.
What's happening is, your brain is being re-sculpted, you know, a sculptor using a great big block of marble, what they're doing is, they're cutting stuff out, but by cutting stuff out, they're actually making it more beautiful.
This pruning process is already making Dan's brain faster and more powerful.
But it won't be completely finished until he's about 20 years old.
What modern brain imaging does is, it enables you to see inside a teenager's brain for the first time and I think when you do that, you see all those changes going on and it makes you forgive them for an awful lot of things, because when you see that stuff, you realise that an awful lot of their behaviour is not their fault.
It's actually just a natural product of what is going on inside their heads.
CLOCK TICKS SCHOOL BELL RINGS # I am human and I need to be loved # Just like everybody else does # Stephanie Bean is a 13-year-old all-American teen .
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and she's made it into the record books.
Stephanie is the world's youngest stock car racer.
I started racing stock cars when I was ten years old, so I've been racing them for four years.
She's competing on the Winchester Speedway, also known as the world's fastest half mile.
At 37 degrees, these are the steepest curves in American motor sport.
It's pretty awesome cos whenever you go round, you get all that speed in you and it builds up, and it's like, I want to go.
Stephanie is prepared to take risks that many of her adult competitors will not.
One reason is that part of her teenage brain is releasing neuro-chemicals that encourage risky behaviour.
There will probably be about 20 cars out there going, like, around 90 to 100 miles an hour, very close, like, inches away from the wall.
TYRES SCREECH Whenever she takes a risk, her teen brain rewards her with a much stronger natural high than her grown-up competitors.
Whenever a car's next to me, it just makes me want to go even more faster.
If there's a gap, then, you know, take chances.
It's her brain's accelerator pedal pushing her to take risks.
Go, Stephanie, go! But the scan of the teen brain reveals something else is also going on.
The last part of the brain to turn blue and mature is the bit at the front, which thinks through the consequences of taking a risk.
Stephanie's isn't fully mature, so even when she recognises that something is dangerous, she will probably do it anyway.
But why are teenagers wired to take risks? One theory is it's to encourage you to try lots of new things before you settle down into adulthood.
Ever since that time, long ago, when you were just a tiny embryo, you've been busy nurturing your brain cells.
You've assembled so many that their numbers now rival the hundred billion stars that populate our galaxy.
And this vast, beautiful network has been shaped by the kaleidoscope of sights, sounds and feelings that you've lived through.
Now, finally, after 20 years, it's done.
You are the proud possessor of an adult brain.
But that's not quite the end of the story.
When I was a medical student, we were taught that your brain goes on developing into adulthood, but after that it's pretty well downhill, as all the brain cells gradually die off.
As your brain ages, it does become more set in its ways.
But that can be good, because it allows you to hold onto life's lessons, locking in knowledge for the long-term.
Even so, change is still possible.
We now know that, in fact, your brain retains that wonderful child-like quality of being able to develop new cells and make new connections throughout your life.
Adventurer Erik Weihenmayer is a striking example of how well a middle-aged brain can respond to new challenges.
There's that step again, Erik.
Erik went blind when he was 13 years old.
Every week, you know, I would wake up with different levels of vision because my retinas were splitting away from my eyes.
Today, Erik, with his friend, Greg Childs, is going to attempt to scale Utah's formidable Castleton Rock.
It's Erik's first climb here.
To help him, he has brought along an impressive bit of new technology.
I don't know if you've seen this.
This is a brain port device.
This is the camera on these sunglasses here.
The camera picks up images and sends a feed to a computer on Erik's hip .
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which translates the images into a low-resolution picture of the world.
These blocky images are then sent to one of the most sensitive parts of Erik's body.
This is the tongue display.
On the surface are hundreds of tiny electrical stimulators.
If the camera sees a distinct outline, a corresponding line of stimulators buzz away, tickling Erik's tongue.
I can feel each dot, and together they create lines and shapes and, ultimately, images that my brain then reinterprets as the space around me.
Three decades after he lost his sight, the visual part of Erik's brain, his mind's eye, is back in action.
Except now, he's not seeing with his eyes.
He's seeing with his tongue.
Is that sight? Well, kind of, you know, because I think seeing is more in your brain than in your eyes.
In rock climbing, most of the risk is taken by the lead climber.
Greg led most of the tower.
He's making sure, you know, that if I fall, I'm not going to fall too far.
Ah! Oh.
OK! Well, sometimes I like to lead the rock face too.
And that's really fun for me, because I'm now the first person going up the rock face, and I'm taking the risk.
Last pitch to the top.
Excellent.
OK, are you ready? Erik is feeling so confident with the brain port device that he decides to lead the final push.
And now I'm Greg's safety, you know, for me, that's a real honour, being blind and still being able to be a real part of the team.
You pop over this lip and it's completely flat and the wind just gusts in your face.
And you're up there on this flat tower, 1,000 feet above the desert floor.
It's a privilege.
I know.
This is totally beautiful.
Erik is a great example of the brain's astonishing ability to remodel itself.
It's this that makes us so wonderfully adaptable.
And six months on from the operation to split her brain, it's this adaptability that is giving Angelina the chance to flourish.
It's just wonderful to see now that the development is just coming on in leaps and bounds.
Are you going to come to Mummy? Come to Mummy.
Good girl.
To hear her start to talk, start to walk, it's just absolutely amazing.
For you?! Say "hello".
Rock, paper, scissors, shoot.
Whatever your age, if you continue to stretch your brain, you can be sure it will rise to the challenge.
Stone, paper, scissors, shoot.
This is adventure, you know, this is total adventure.
Yet he can climb the world's most terrifying peaks.
These fishermen can see underwater better than almost anyone else on Earth.
And this delightful young girl is alive and well despite having just half a brain.
Their stories are part of YOUR story .
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the story of what makes YOU human.
Hidden deep under your skin is a wonderful inner universe .
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a place of raging torrents, electrical storms .
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and triumph against the odds.
This is a fantastic voyage through the most extraordinary organism on Earth.
You.
Strange as it might seem, this bizarre-looking creature is you.
Or rather, what you look like just three weeks after your conception.
This was when your brain was born.
It was the start of an astonishing transformation .
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as you went from a small handful of brain cells .
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to the exquisite network of a hundred billion brain cells that you carry around inside your head.
We call this transformation childhood BELL RINGS .
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and humans enjoy one of the longest childhoods of all.
This is New College Oxford.
I came here when I was 18 years old, and over the next three years I would become, in many ways, a completely different person.
On the outside, I had finally grown into a man.
Yet inside, my brain was anything but finished.
I first fell in love here, I had my heart broken here, I changed almost everything I believed in.
I want to show you why it took me, and you, so long to grow up.
It's a story of the biggest wiring job on the planet.
As your brain first plugs itself into your body .
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and then grows, fed by the stream of information that's rushing in through your senses.
It is so sophisticated that it takes nearly 20 years to mature.
20 years to go from the helpless baby to the proud possessor of the most sophisticated thing in the known universe.
In the womb you grew 8,000 new brain cells every second.
By the time you were ready to be born you had all the brain cells you'd ever need.
But this baby is about to experience the shock of her life.
Come on, big, big push.
Big push.
Push down.
SHE SCREAMS Don't scream, just push.
Get angry and push down into your bottom.
Come on.
Push.
It's got hair! What time is it? It's, er, about This is Phoebe.
As she emerges, her eyes are dazzled by light.
She's come from a gloomy, watery world into a bright, noisy room.
It's time for her to meet Mum and Dad.
Oh, that was that was pretty difficult.
Yeah.
And hot.
MIDWIFE: I think we gathered that.
And painful.
Andthere is a reason why it's "labour"! Phoebe's brain is being flooded with new sensations.
The chill of the room.
The smell of her dad.
Hello.
And, most puzzling of all, the strange images that are pouring in through her eyes.
The lens that lies in the centre of the eye can't focus on anything for long.
Even so, newborns recognise their mum's face after just a few hours.
At the back of the eye is the red plane of your retina.
Here, light from outside shines down, casting images across the surface.
Underneath, these rays enter a dense forest of 125 million light-sensitive cells.
These rod cells each detect just a tiny part of any image.
They send these fragments to your brain, which has to piece it all together.
BIRD CALLS It's your rods which enable you to see in the dark.
I think it's a strange thought that your rods were actually active when you were in your mother's womb, so when you were looking around in there, what you were seeing was a black and white world.
Your rods are so sensitive they could detect the dim light that passed through your mother's belly.
They were training your brain to see long before you were born.
I love that feeling in the morning when the sun's rising and the whole world is coming back to life.
Dawn lush, bird beautiful, you can feel your soul really sort of rising and singing along.
On a sunny morning, light levels rapidly increase a million-fold.
And like the moment of your birth, this bleaches out your night vision.
And a whole new set of cells are about to spring into life and they're going to inject colour into your world.
They are the cone cells.
You have a richer experience of the world than most other mammals because your cones detect not two but three different colours.
In one location, they begin to group together, causing the retina's surface to bulge.
Year after year, they continue to rise, creating a volcano-like structure.
It's not until you are four years old that the mound is finished.
This is your fovea.
It's the only part of your eye where your vision is crystal clear and, thanks to your cones, capable of sensing millions of different colours.
But the complexity and the beauty of the human eye is nothing without your brain.
You blink up to 20 times every minute.
Each blink lingers for less than half a second.
But add all those blinks of an eye up and you're living in the dark for over an hour every day.
Your brain is so good at filling in the gaps .
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you're not even aware of it.
Your eyes are an extension of your brain.
They are so adaptable that you can learn to see in places where human eyes normally struggle.
This is the remote Thai island of Koh Surin, home to a group of sea gypsies known as the Moken.
To survive, they've become expert underwater foragers.
Finding food underwater is difficult .
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particularly without goggles.
That's because our eyes have adapted to see clearly in air.
In water, the world becomes blurry.
As you descend, light levels drop quickly.
Your eye reacts by opening the iris, making the pupil larger and allowing more light in.
The image becomes brighter, but underwater, a larger pupil also makes the image more blurred.
But Goon has learnt how to overrule this automatic reflex with an astonishing adaptation seen clearly with the help of an infrared camera.
Instead of opening his pupils, he closes them as far as they will go.
This means Goon can see twice as well underwater as you or I.
Recent studies suggest that any child can quickly learn this trick.
The Moken show how well the human brain can adapt the body to suit its needs.
This adaptability has enabled our species to thrive on all seven of Earth's continents.
Hey! MAN: Rrrr! But at three months old, Phoebe's brain is still hopeless at pretty much everything.
Hey! Hey, Phoebe! It can tell her mouth to suck but can't feed itself .
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can't maintain body temperature .
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can't even control when she goes to the loo.
I now am utterly and totally responsible for another human being who has to take priority over my life in everything.
She has to come first, otherwise she can't survive.
Phoebe is so very helpless because her brain is still getting organised.
Bit by bit, her brain is creating her mind.
This remarkable time lapse shows living brain cells sending out tendril-like arms, which connect with each other.
Each of Phoebe's hundred billion brain cells will, on average, make 10,000 different connections .
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and we can follow this on the outside.
Oh, I've gone away! At six months, Phoebe thinks that when she can't see someone they vanish from the world entirely.
I'm here.
Ya-a-a-a-a-ay! Watch Phoebe's face as Charlotte hides.
Now you don't see me.
She immediately loses interest.
Where's Mummy gone? Where's Mummy gone? Shall I come back? But when her mother reappears I've come back! .
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her delight is obvious.
I'm here! Yes, I am! Going to come back, I'm here.
Where's Mummy gone? Three months later, and Phoebe's brain has now learnt that just because something is hidden doesn't mean it's disappeared.
Here I am! Yes! A childhood game of peekaboo has helped her build connections that will stay with her for the rest of her life.
And the longest connection Phoebe's brain will ever make is the one between her head and her toes.
Remarkably, the connection between your head and your toes won't be fully mature until you are three years old.
Long before that, your brain cannot resist the urge to take its first big step.
Standing up feels easy, natural, but learning how to do so was hard - really hard.
Today I want to try and recreate that challenge, that problem that we all had to face and overcome when we took our first steps.
Soahh! Young babies doing first steps.
Indeed.
I'm going to give you a little bit of a hand with this stick.
Excellent, good.
Right 'Like all beginners, I need a helping hand' Keep walking forwards.
It's going to get wobbly.
Andwhoa! That's it.
'.
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not from my mother, but tight-line walker Alana Jones.
' First steps, it was all right.
But that's only because I was holding onto you.
Keep going, keep walking.
Keep walking.
Keepwalking! Whoop! The thing about this is it's fantastically hard because you are using something like 54 different muscles in your leg but at the same time, you require at least 640 muscles of your body.
'And all of these muscles are being directed 'by a bizarre part of your inner ear.
' This cavern is buried deep inside your head.
It's part of a labyrinth of twisting tunnels completely submerged in fluid.
The tunnels are the three great loops of your semicircular canals.
Inside each loop there is a saddle-topped fleshy mountain, your crista.
LOW WHOOSHING OF LIQUID The mountain slopes are covered in a thick forest of tiny hair cells.
For the moment, they lie still.
But this inner sea never remains calm for long.
ROARING, THUNDERING GURGLING As you move your head, it generates a shock wave, which races through the tunnel and pummels the mountain.
On its flanks, the hair cells are thrown about in the turbulent waters.
The pressure builds .
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until electricity flows .
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creating a powerful electrical current.
All this activity going on inside your semicircular canals creates your sixth sense - your sense of balance.
Take your back leg off.
Off, off, off.
Oh Oh Good.
And again, off.
Good.
And again.
Whoo! Yes! INSECT CALLS AND BIRDSONG GOATS BLEA Learning to balance and coordinate your body is so complex that the area of your brain devoted to this one task involves as many cells as the whole of the rest of your brain put together.
Some people learn how to walk sooner than others.
But there is a place where people pull off this feat sooner than anywhere else.
LOW HUM OF CHATTER This is Kaumba.
She is mother to a baby girl called Kosini.
They live in Rhumsiki - a tiny village in the remote northern highlands of Cameroon.
Here, mothers are keen to get their babies off their backs and walking as soon as possible.
Ever since Kosini was a month old, her mother has repeated the process of "kitete" which means to make jump.
Every day, she takes hold under the arms and bounces her.
Kosini responds with a kind of stepping reflex.
You had this reflex, but it disappeared after a couple of months.
But here in Rhumsiki, this daily encouragement means that the reflex remains and gradually develops into mature walking.
Now she's seven months old, it's time for Kosini to try and stand up by herself.
WOMEN CHATTER So her mother sets about another ritual practice.
She washes her with a warm herbal liquid.
This seems to stimulate her legs, preparing them for walking.
The leftover warm leaves are laid on the ground and Kosini is placed on them.
It's uncomfortable and she soon wants to get off KOSINI GRIZZLES .
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giving her the gentle encouragement she needs to use her legs.
These rituals seem to be accelerating the connections that Kosini is making between her brain and her feet.
So by seven months old, she's ready for her first steps.
To walk, your brain has to sense when you are overbalancing to one side .
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and then instruct your body to shift your weight back to the centre.
All of this has to happen within a fraction of a second.
To begin with, it's a real struggle.
But Kosini's half-brother, Tisema, is already a master of bipedalism.
He is just ten months old.
At his age, my children were still shuffling around on their bottoms.
From now on, and for the rest of Tisema's life, walking will be automatic.
The first year of life is a critical period for your brain .
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because at this age it's an extraordinarily adaptable and efficient learning machine.
He's down at the bottom, isn't he? And each new skill you acquire is shaping the way it grows.
Right at the back here is an area called the visual cortex, that processes vision.
The left side of your brain is learning how to control the right side of your body.
That's it! So Henry's right hand here is being controlled by the left side of his brain and vice versa.
I think Tom's not entirely sure, but he's got lots of speech, lots of verbalisation, and that also Ah .
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tends to be on the left hemisphere.
Ah Ah! That's right! The different parts of your brain are becoming increasingly specialised.
Some of this development is pre-programmed by your genes.
But there's an awful lot that's also shaped by the everyday experiences that these little toddlers are going through at this moment.
The interplay between the genes you inherit and what you experience means that no two brains are ever identical.
It is the incredible flexibility of the human brain which gives it its power and enables the brain to respond to almost any challenge that the world throws at it.
That's a big one.
Is he coming round again? Uh Yeah, darling? Can you see the fishes? Look at these little ones.
Can you? Are they pretty? Yes, Mummy.
Angelina is a rather remarkable one-year-old because she was born with just half a healthy brain.
She has a rare disease which affects the blood vessels on the right side of her head.
She's a happy, active little girl, but every now and then Angelina? Angelina? SHE CLAPS Angelina? Angelina? SHE CLICKS HER TONGUE You all right? OK? HE CLICKS HIS FINGERS Angelina's having what we call a complex vocal seizure.
As you can see, she was very, very active and now she's gone very distant.
One indication is that her head lags.
She's slightly heavy in her breathing.
Angelina has a rare condition, Sturge-Weber syndrome.
This one is going on quite a bit, isn't it? Angelina? Angelina? Her parents, Lisa and Stephen, have had to deal with her seizures ever since she was born.
Angelina's brain scans show the cause - abnormal blood vessels, seen here in white on the right side of her brain.
But they also show that the left half of her brain is perfectly healthy.
There is a treatment for her condition, but it involves radical surgery - cutting off the damaged half of Angelina's brain.
We're in a position we don't know what we've got to face after this operation.
I pray to God she comes back to us at all, but what she does come back as, we accept.
MONITORS BEEP The surgeon who must navigate his way through Angelina's tiny brain is Mr William Harkness.
We've lifted the bone flaps so we've made our trap door in the skull.
And now we're beginning to see the brain.
It seems impossible that you can disconnect half of someone's brain and expect them to recover, yet that is exactly what the surgeons are hoping will happen.
Because the brain does adapt at this age of life, we would expect most of the functions to transfer to the other Other side of the brain.
It takes four hours of micro-surgery to find the bridge between the two sides of Angelina's brain.
And this is what's called the corpus callosum .
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which connects one side of the brain to the other.
Now, he cuts through it.
Angelina's healthy brain is finally free from the disruption caused by the damaged right half.
Hopefully, if this child becomes seizure-free, I think that we will have given her the best opportunity for the future because the type of epilepsy that she had clearly is life-threatening.
Angelina? She's so sleepy.
I haven't even given her a kiss yet.
Haven't you? No.
Come here, lovely.
Come on, my darling.
Hello, sweetheart.
Who's a strong little girl, eh? Who's Daddy's strong little girl? You have a nice dream.
All her parents can do is wait and hope.
It was essential for Angelina to have the operation at this age because after your first birthday your brain loses some of its flexibility.
EXCITED CHATTER AND WHOOPS While there's still room for plenty of development, there's less scope for fundamental change.
It becomes increasingly unlikely that you would make a full recovery from an operation as dramatic as Angelina's.
That's why the surgeons operated on her so young, they've given her the best chance she will ever have of being up and toddling around like any other one-year-old.
As your young brain starts to explore the world from its new, lofty position, there is an immediate and rather wonderful consequence.
# Girl, you got those hands # That heal # Help me get in touch with what I feel # Cos you understand # That's because walking releases two powerful natural tools - your hands.
I've kind of developed a skill with my hands that when I touch things, I get information from it.
A bit more than an average human.
From a young age, street magician Dynamo has been fine-tuning the control of his hands.
If I put a pack of cards into your hand, you'd just feel the edges of the cardboard, right? Whereas I can actually feel how many cards there is in the In my hand.
I've built up, you know, a sense that allows me to do it.
His hands are so nimble your brain cannot keep up with them.
HE CHUCKLES Just take a card out.
OK.
I'm going to turn around, just show it to the people.
HE MOUTHS Yep.
Got it? I'll take it back.
Yeah.
I'll do this slowly.
I'll put it about halfway down, yeah? Yeah.
It's fair, right? Yeah.
Put your hands like this.
Really concentrate on the card.
Look at me a second.
Watch.
HE LAUGHS One card jumps up.
HE LAUGHS That That was good! That was That was very good.
Can you do it again? Your hands' versatility springs from a mixture of strength and sensitivity.
At the tip of each finger is the densest collection of nerve receptors found anywhere on your body .
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feeding your brain with information about the temperature, pressure and vibrations of anything you touch.
They're so sensitive they can detect lumps and bumps less than a 100th of a millimetre across.
I've got some cards here, are they all different? Yeah, they look all different.
See that? Just hold your hand out.
Mm-hm.
What card is that? Five of hearts.
Five of hearts? Can you see that? Five of hearts.
Yeah? I'll place that on there, put your other hand on top so it don't blow away.
Yep.
Perfect.
So you've got the five of hearts.
I've got the five of hearts.
I'm going to take the Let's have a look.
Yeah, I'll take the next card, the queen of spades.
Yeah.
Yeah? Can you see that on camera? Yeah? Yeah.
Queen of spades, five of hearts.
Watch.
One, two, three, four.
HE CHUCKLES Very good.
I've got the five of hearts now.
Right, I've got the queen of spades.
That's clever.
Your hands allow your brain to reach out and change the world.
As a result, our species is the only one to have built a civilisation.
Standing upright and walking releases the potential of these wonderful flexible hands, and it's followed soon afterwards by another milestone, the development of an ability which is uniquely human.
One that I'm demonstrating right now.
It's the ability to talk.
From an early age, Wendy Vo's brain has been bursting with languages.
When I was one, I spoke Vietnamese only, like, it was just like baby words.
When I was two, I spoke English, Vietnamese, Spanish and Chinese, so four languages when I was two years old.
Well, I started learning them.
She hasn't stopped at just four languages.
Wendy spends an hour every week talking to a range of different people in their native tongues.
I am Winita from India, and I teach Wendy Hindi.
HINDI DIALOGUE My name is Rashida and I teach Wendy Arabic from Yemen.
ARABIC DIALOGUE And I teach Wendy Spanish.
She speaks Spanish a lot better than some Hispanic kids do.
WENDY SPEAKS SPANISH At the Russian languages, she is very good.
RUSSIAN DIALOGUE Portuguese PORTUGUESE DIALOGUE She is at the top because she can switch veryin few seconds, from one language to the other one.
FOREIGN DIALOGUE And she can think, speak, write.
It's unbelievable.
Vietnamese, English, Spanish, Chinese, French, Japanese, Hindi, Arabic, Russian, Cantonese and Portuguese.
Add them all up and Wendy has 11 different voices packed inside her head.
But speaking is only half the story.
ECHOING VOICE For meaning to fly from one person to another, the words have to travel deep into your body.
Inside your ear, sounds set off a complex chain of events.
They enter as pressure waves, which push and pull your eardrum, making it vibrate.
LOW RUMBLING On the other side of the eardrum, these vibrations set a series of bones jiggling.
RUSTLING They end with the smallest bone in your entire body, called the stirrup.
It is smaller than a grain of rice.
These bones allow you to hear.
If a sound is too loud ECHOING VOICE .
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a muscle pulls the stirrup away from the most sensitive parts.
Temporarily, at least, you go a bit deaf, but the rest of your ear is protected.
Beyond the stirrup is a fluid-filled cavern, your cochlea.
The incoming sound waves tickle clumps of tiny, hair-like sensors on the floor.
These begin to dance to the sounds of the world outside.
You have 30,000 sensors.
Each picks out a different part of the sound and sends it straight to your brain.
The cochlea is most sensitive to the sounds of another person's voice.
# Aha aha aha # CHILDREN CHATTER SPEAKS RUSSIAN RUSSIAN DIALOGUE # Da da da # Finely-tuned ears and a wonderfully versatile voice # Da da da # .
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have allowed humans to invent over 7,000 different languages.
# Da da da # SPEAKS IN FOREIGN LANGUAGE THEY GIGGLE Hello! Bonjour VARIOUS FOREIGN LANGUAGES And each of us, as we grow, pick up over a thousand new words every year.
SPEAKS IN FOREIGN LANGUAGE By your early teens, you have a working vocabulary of over 10,000 words, as you head towards the brain's next challenge - puberty.
I've got three kids at home.
There's Kate, who's 11, and she has yet to go through puberty so she's still a sort of cheerful girl.
I've got Jack, who's at the other end, and he's 18 and he's rapidly becoming an adult.
And then there's Daniel, in the middle, who's 16.
And Daniel is interesting because he has absolutely shot up recently.
He has changed a lot in himself.
They way he behaves.
Most obviously he hates going to bed.
Bedtime.
No, come on! Seriously, a couple of minutes.
And he's become much more fashion conscious.
What do you think about the buttons? Oh, yes.
THEY LAUGH Boring.
Living with puberty is all about living with change.
I think red's a lot better.
Red suits your skin colour a lot more.
And while hormones, those glandular bringers of pimples and sexual stirrings, can explain some of Dan's behaviour BOYS CHATTER .
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the true source of his transformation lies way north of his gonads.
Do you know what this is, what I'm looking at here? A brain? It is a brain indeed.
It's orientated this way so the eyes would be there, OK? And this is actually a scan, which is a mixture of about 1,000 brains.
OK.
And what they did is they filmed, um Wow! .
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kids from the age of three through to about 18.
This image allows us to see, for the first time, what really happens to the brain as it matures.
The colours represent how densely packed the particular part of the brain is.
Red and yellow means loads of active brain cells and connections.
Blue and green means far fewer.
So what would we expect to see? Um, more red over time, presumably? Yeah.
As new pathways are made.
Because, like, brains grow.
Brains grow.
OK.
Let's actually see what happens.
Here we go.
We're now up to about Kate's age.
Not a lot of activity happening, a little bit more blue.
And then we're hitting your age, Dan, what do you see? Wow.
A lot more blue, yeah.
That's quite cool.
That is not what I thought, it's really weird.
From Kate's age onwards, what we see is actually brain connections are dying off much more rapidly than they're growing.
So it's just downhill from Well, it's not downhill.
What's happening is, your brain is being re-sculpted, you know, a sculptor using a great big block of marble, what they're doing is, they're cutting stuff out, but by cutting stuff out, they're actually making it more beautiful.
This pruning process is already making Dan's brain faster and more powerful.
But it won't be completely finished until he's about 20 years old.
What modern brain imaging does is, it enables you to see inside a teenager's brain for the first time and I think when you do that, you see all those changes going on and it makes you forgive them for an awful lot of things, because when you see that stuff, you realise that an awful lot of their behaviour is not their fault.
It's actually just a natural product of what is going on inside their heads.
CLOCK TICKS SCHOOL BELL RINGS # I am human and I need to be loved # Just like everybody else does # Stephanie Bean is a 13-year-old all-American teen .
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and she's made it into the record books.
Stephanie is the world's youngest stock car racer.
I started racing stock cars when I was ten years old, so I've been racing them for four years.
She's competing on the Winchester Speedway, also known as the world's fastest half mile.
At 37 degrees, these are the steepest curves in American motor sport.
It's pretty awesome cos whenever you go round, you get all that speed in you and it builds up, and it's like, I want to go.
Stephanie is prepared to take risks that many of her adult competitors will not.
One reason is that part of her teenage brain is releasing neuro-chemicals that encourage risky behaviour.
There will probably be about 20 cars out there going, like, around 90 to 100 miles an hour, very close, like, inches away from the wall.
TYRES SCREECH Whenever she takes a risk, her teen brain rewards her with a much stronger natural high than her grown-up competitors.
Whenever a car's next to me, it just makes me want to go even more faster.
If there's a gap, then, you know, take chances.
It's her brain's accelerator pedal pushing her to take risks.
Go, Stephanie, go! But the scan of the teen brain reveals something else is also going on.
The last part of the brain to turn blue and mature is the bit at the front, which thinks through the consequences of taking a risk.
Stephanie's isn't fully mature, so even when she recognises that something is dangerous, she will probably do it anyway.
But why are teenagers wired to take risks? One theory is it's to encourage you to try lots of new things before you settle down into adulthood.
Ever since that time, long ago, when you were just a tiny embryo, you've been busy nurturing your brain cells.
You've assembled so many that their numbers now rival the hundred billion stars that populate our galaxy.
And this vast, beautiful network has been shaped by the kaleidoscope of sights, sounds and feelings that you've lived through.
Now, finally, after 20 years, it's done.
You are the proud possessor of an adult brain.
But that's not quite the end of the story.
When I was a medical student, we were taught that your brain goes on developing into adulthood, but after that it's pretty well downhill, as all the brain cells gradually die off.
As your brain ages, it does become more set in its ways.
But that can be good, because it allows you to hold onto life's lessons, locking in knowledge for the long-term.
Even so, change is still possible.
We now know that, in fact, your brain retains that wonderful child-like quality of being able to develop new cells and make new connections throughout your life.
Adventurer Erik Weihenmayer is a striking example of how well a middle-aged brain can respond to new challenges.
There's that step again, Erik.
Erik went blind when he was 13 years old.
Every week, you know, I would wake up with different levels of vision because my retinas were splitting away from my eyes.
Today, Erik, with his friend, Greg Childs, is going to attempt to scale Utah's formidable Castleton Rock.
It's Erik's first climb here.
To help him, he has brought along an impressive bit of new technology.
I don't know if you've seen this.
This is a brain port device.
This is the camera on these sunglasses here.
The camera picks up images and sends a feed to a computer on Erik's hip .
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which translates the images into a low-resolution picture of the world.
These blocky images are then sent to one of the most sensitive parts of Erik's body.
This is the tongue display.
On the surface are hundreds of tiny electrical stimulators.
If the camera sees a distinct outline, a corresponding line of stimulators buzz away, tickling Erik's tongue.
I can feel each dot, and together they create lines and shapes and, ultimately, images that my brain then reinterprets as the space around me.
Three decades after he lost his sight, the visual part of Erik's brain, his mind's eye, is back in action.
Except now, he's not seeing with his eyes.
He's seeing with his tongue.
Is that sight? Well, kind of, you know, because I think seeing is more in your brain than in your eyes.
In rock climbing, most of the risk is taken by the lead climber.
Greg led most of the tower.
He's making sure, you know, that if I fall, I'm not going to fall too far.
Ah! Oh.
OK! Well, sometimes I like to lead the rock face too.
And that's really fun for me, because I'm now the first person going up the rock face, and I'm taking the risk.
Last pitch to the top.
Excellent.
OK, are you ready? Erik is feeling so confident with the brain port device that he decides to lead the final push.
And now I'm Greg's safety, you know, for me, that's a real honour, being blind and still being able to be a real part of the team.
You pop over this lip and it's completely flat and the wind just gusts in your face.
And you're up there on this flat tower, 1,000 feet above the desert floor.
It's a privilege.
I know.
This is totally beautiful.
Erik is a great example of the brain's astonishing ability to remodel itself.
It's this that makes us so wonderfully adaptable.
And six months on from the operation to split her brain, it's this adaptability that is giving Angelina the chance to flourish.
It's just wonderful to see now that the development is just coming on in leaps and bounds.
Are you going to come to Mummy? Come to Mummy.
Good girl.
To hear her start to talk, start to walk, it's just absolutely amazing.
For you?! Say "hello".
Rock, paper, scissors, shoot.
Whatever your age, if you continue to stretch your brain, you can be sure it will rise to the challenge.
Stone, paper, scissors, shoot.
This is adventure, you know, this is total adventure.