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 a part of your story.
The story of what makes you human.
Hidden deep under your skin
is a wonderful inner universe.
A place of raging currents,
electrical storms,
and triumph against the odds.
This is a fantastic voyage
through the most extraordinary organism on Earth.
Strange as it might seem,
this bazaar looking creature is you.
Or rather what you looked like
just three weeks after your conception.
This was when your brain was born.
It was the start of an astonishing transformation.
As you went from a small handful of brain cells
to the exquisite network of 100 billion brain cells
that you carry around inside our head.
We call this transformation childhood.
It's a remarkable time
that we'll share with three young girls,
each on the brink of momentous change.
Baby Phoebe is rapidly growing brain connections
as she discovers her senses.
11-year-old Wendy is learning to speak,
not one but 11 different languages.
And Stephanie's teenage brain
is pushing her to explore her wild side.
Together, they reveal the extraordinary story
of how you build your brain.
It all started before you were born.
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.
Big, big push.
Big push.
Don't scream, just push.
Get angry and push down into your bottom.
Come on.
Push.
What time is it?
It's a (mumbling).
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 Mom and Dad.
Oh, that was, that was pretty difficult.
I, yup.
And hot.
I think we gathered that.
Painful and there is a reason why it's labor.
Phoebe's brain is being flooded
with new sensations.
The chill of the room.
The smell of her dad.
And most puzzling of all,
the strange images that are pouring in through her eyes.
The lens that lye's in the center of the eye
can't focus on anything for long.
Even so, newborn's recognize their mom's face
after just a few hours.
At the back of the eye is the red plain
of your retina.
Here light from outside shines down,
casting images across the surface.
Underneath, these rays enter a dense forrest
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.
Phoebe's rod cells give her the ability
to see things that move quickly.
They also allow her to see in the dark.
And incredibility, they started working
when she was still in her mother's womb.
Your rods are so sensitive
they could detect the dim light that passed through
your mother's belly.
So they were training your brain to see
in black and white months before you were born.
But in daylight the amount of light around
can increase a million fold
and just like the moment of your birth
this totally bleaches out your night vision.
So a whole new set of sight cells spring into life,
your cones.
You have a richer experience of the world
than most other mammals
because your cones detect not two
but three different colors.
In one location, they begin to group together
causing the retina 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 colors.
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 your living in the dark for over an hour every day.
Your brain is so good at filling in the gaps
that 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 Mu Ko.
To survive, they've become expert underwater foragers.
Finding food underwater is difficult,
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 learned how to overrule
this automatic reflex
with an astonishing adaptation, seeing 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 Mu Ko 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.
But at three months old,
Phoebe's brain is still hopeless
at pretty much everything.
Hey!
It can tell her mouth to suck
but can't feed itself.
Can't maintain body temperature.
Can't even control when she goes to the loo.
I now an 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 micro arms
which connect with each other.
Each of Phoebe's 100 billion brain cells
will on average make 10,000 different connections.
And we can follow this on the outside.
At six months Phoebe thinks that when she can't see someone
they vanish from the world entirely.
I'm here, yay!
Watch Phoebe's face as Charlotte hides.
She immediately loses interest.
Where have I gone?
Where's Mommy gone?
When shall I come back?
But when her mother reappears,
her delight is obvious.
Yes I am!
Gonna come back, I'm here!
Where's Mommy gone?
Three months later and Phoebe's brain
has now learned that just because something
is hidden doesn't mean its disappeared.
Here I am!
Yay!
A childhood game of peak-a-boo
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 just can't resist
the urge to take its first big step
as you try to walk.
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 feet sooner than anywhere else.
This is Kawumba.
She is mother to a baby girl called Cassinee.
The 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 Cassinee 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.
Cassinee 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 Cassinee to try and stand up by herself.
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 Cassinee is placed on them.
It's uncomfortable and she soon wants to get off.
Giving her the gentle encouragement she needs
to use her legs.
These rituals seem to be accelerating the connections
that Cassinee is making between her brain
and her feet.
But before you can stand up for any length of time
there is a strange part of your body that your brain
must learn to understand.
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 semi-circular canals.
Inside each loop
there is a saddle topped fleshy mountain,
your crista.
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.
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 throw about
in the turbulent waters.
The pressure builds
until electricity flows
creating a powerful electrical current.
All this activity going on inside your semi-circular canals
creates your sixth sense,
your sense of balance.
To walk, your brain has to sense
when you are overbalancing to one side.
And then, instruct your body
to shift your weight back to the center.
All of this has to happen within a fraction
of a second.
To begin with it's a real struggle.
But Cassinee's half brother, Tizema
is already a master of bipedalism.
He is just 10 months old.
At his age, most children
are shuffling around on their bottoms.
From now on and for the rest of Tizema's life
walking will be automatic.
By the age on one
your brain has made over 500 trillion connections.
So many that your brain can cope
with almost anything that life throws its way.
Floating about.
Angelina is a rather remarkable one-year-old
because she was born with just half
a healthy brain.
She has a rare disease
which effects the blood vesicles on the right side
of her head.
She's a happy, active little girl
but every now and then.
Angelina?
Are you alright?
Okay?
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 is one's going on quite a bit isn't it.
Angelina?
Her parents, Lisa and Steven
have had to deal with her seizures
ever since she was born.
Angelina's brain scans show the cause.
Abnormal blood vesicles 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 of 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.
Pray to God she comes back to us at all
but what she does come back as we accept.
The surgeon who must navigate his way
through Angelina's tiny brain
is Mister William Hartless.
We've lifted the bone flaps.
So we made out trap door in the scull.
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.
That's the brain that does adapt
at this age of life.
We would expect most of the functions
to transfer to the other side of the brain.
It takes four hours of microsurgery
to find the bridge between the two sides
of Angelina's brain.
And this is what's called corpus collosum
which connects one side of the brain to the other.
Now he cut through it.
Angelina's health brain is finally free
from the disruption caused by the damaged right half.
Hopefully, if this child becomes seizure-free
I think that we'll have give her the best opportunity
for the future because of the type of epilepsy
that she had clearly is life threatening.
(mumbling) she's so sleepy.
You know I haven't given her a kiss yet.
Haven't you?
No, come here Angelina.
Come on (mumbling) darling.
Here sweetheart.
Here's a strong little girl hey.
Here's Daddy's strong little girl.
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.
While there's still room for plenty of development
there's less scope for fundamental change.
But as your young brain starts
to explore the world from its new lofty position
there is an immediate and rather wonderful consequence.
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 them.
A bit more than the average human.
From a young age,
street magician Dynamo has been fine-tuning
the control of his hands.
If I put 100 cards into your hand,
you'd just feel the edges of the card (mumbling).
Whereas I can actually feel how many cards
there is in my hand.
I build up a sense that allowed me to do it.
His hands are so nimble
your brain cannot keep up with them.
Just name any playing card.
Five of Clubs.
Five of Clubs, yeah?
Yeah.
Are you sure that's the one you want?
Yeah.
Yeah?
Definite?
Yeah.
Okay.
Cause, I thought I've got some cards in my pocket.
What I forgot to mention was that one
of the cards inside this deck is upside down.
Okay.
Yeah, look at this.
Just one card upside down there, yeah?
Yeah.
What card did you say?
Five of Clubs.
Turn that over.
No!
What?
What!
Your hands versatility springs
from a mixture of strength and sensitivity
and the tip of each finger is the densest collection
of nerve receptors found anywhere on your body.
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 hundredth of a millimeter across.
Yeah, just reach in and pull out any card.
Show it to Becs.
I'm going to put it about half way down
a few more, that's about half way right?
Yeah.
Just put your hands like this please.
Really focus on the card alright and watch.
Ooh!
That was incredible Dynamo, you are the man!
That was amazing, Dynamo I'm telling all my friends.
I'm telling all my friends.
Brilliant, group hug.
Thank you so much!
That was amazing.
Your hands allow your brain
to reach out and change the world.
As a result, our species is the only one
to have build a civilization.
Standing upright and walking releases
the potential of your wonderful hands.
And it's followed by another milestone.
An ability that is uniquely human.
The ability to talk.
When I was one I spoke Vietnamese only,
just like baby words.
When I was two I spoke English, Vietnamese,
Spanish, and Chinese.
So, four languages when I was two years old,
or at least I started learning them.
From an early age Wendy Voes brain
has been bursting with languages.
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 Vinita from India and I teach Wendy Hindi.
My name is Ashida and I teach Wendy
Arabic from Yemen.
And I teach Wendy Spanish.
She speaks Spanish a lot better
than some of the Spanish kids do.
At the Russian language she's very good.
Portuguese.
She's at the top because she can switch very
in a few seconds from one language to the other ones.
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.
From 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.
On the other side of the eardrum
these vibrations set a series of bone jiggling.
They end with the smallest bone in your entire body
called the stirrup.
It's smaller than a grain of rice.
These bones allow you to hear.
If a sound is too lound
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.
This seems (mumbling).
Finley tuned ears and a wonderfully versatile voice
have allowed humans to invent
over 7,000 different languages.
And each of us as we grow
pick up over 1,000 new words every year.
By your early teens, you have a working vocabulary
of over 10,000 words
as you head towards the brains next challenge,
puberty.
Stephanie Bean is 14 years old
and like all teenagers she's maturing physically.
We really don't talk about the puberty thing really.
I don't know, some girls think it's embarrassing.
Hi, come on in this is study hall.
Get rid of your gum.
Oh!
Like the rest of her teenage friends,
Stephanie's brain is maturing too.
And the way it does this is bazaar.
During her teenage years,
she will lose 40% of the connections
she's spent more than a decade building.
This extraordinary image is made
from hundreds of teenage brain scans.
It shows how as the brain matures
the areas which are packed with connections,
colored red and yellow, make way
for areas that contain far fewer, colored blue.
The brain is pruning away the connections
that it doesn't need.
Scientists believe that this leads
to more efficient and faster thinking.
But perhaps the most puzzling change
during puberty is your brain seems determined
to travel a dark road to risk-taking
and recklessness.
As well as being a cheerleader, Stephanie Bean
has another hobby.
She's also the world's youngest stock car racer.
I started racing stock cars
when I was 10 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, cause whenever you go around,
it's like you get all the speed in you
and it just 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 neurochemicals
that encourage risky behavior.
There will probably about 20 cars out there,
going like around 90 to 100 miles an hour.
Very close, like inches away from the wall.
Whenever she takes a risk,
the teen brain rewards her
with a much stronger natural high
than her grown up competitors.
Whenever a car is next to me,
it just makes me want to go even more faster.
If there's a gap and you know, take chances.
It's her brain's accelerator pedal,
pushing her to take risks.
Go Stephanie go!
But the scan of the developing brain,
reveals something else.
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 recognizes
that something is dangerous,
she will probably do it anyway.
But why are teenagers wired to take risks?
One theory is,
is to encourage you to try lots of new things,
before you settle down into adulthood.
Ever since that time long ago,
when you where just a tiny embryo,
you've been busy nurturing your brain cells.
You've assembled so many,
that their numbers now rival
the 100 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.
Until recently, scientists believed
this was pretty much the end of the brain's story.
That from then on,
it was just a slow, gentle decline into old age.
But we now know that your brain
retains that wonderful, childlike ability to learn,
throughout your life.
Adventurer, Eric Winemayer, is a striking example,
of how well a middle age brain
can respond to new challenges.
Eric 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 Eric, with his friend Greg Childs,
is going to attempt to scale Utah's
formidable Castleton Rock.
It's Eric'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 the brainport device.
This is the camera on these sunglasses here.
The camera picks up images,
and sends a feed to a computer on Eric's hip,
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 Eric'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 Eric'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'd lost his sight,
the visual part of Eric'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 was making sure you know,
that if I fall, I'm not gonna fall too far.
Okay.
Well sometimes I like to lead the rock face too.
That's really fun for me,
because I'm now the first person
going up the rock face.
I'm taking the risk.
Last pitch to the top.
Excellent.
Alright, I'm ready.
Eric is feeling so confident
with the brainport device,
that he decides to lead the final push.
But now, Greg's safety, for me, you know,
that's a real honor,
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 was a privilege.
I know.
Doing that with you.
This is totally beautiful.
Eric 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 spit 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 gonna come to Mommy?
Come to Mommy.
Good girl.
To hear her start to talk, start to walk,
it's just absolutely amazing, it really is.
Stone, 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.