Original subtitles

WILL SMITH: What do you need to win a game of chess?

Patience, clever tactics, loads of imagination.

You look nervous.

(laughs)

What makes us human

is the squishy triple-pounder inside our heads.

Check.

It lets us checkmate our friends,

build skyscrapers,

and lift a special few of us into space.

(roaring)

Eight astronauts with over 1,000 days in space between them

can tell us how being up there

helped them to truly understand what goes on down here.

JEFF HOFFMAN: From space you get the big picture.

You really see human civilization

spread out below you.

NICOLE STOTT: As far as we know,

there's nobody else like us out there in the universe.

JERRY LINENGER: The only reason I'm able to comprehend

the incredible complexity of the Earth

is because I have an incredibly complex brain inside my head.

LELAND MELVIN: We are the only species on this planet

that can construct realities in our mind

and then go actually build it.

SMITH: But for three billion years,

life didn't even have a brain.

MELVIN: The story of how our mind evolved

on this one strange rock

is one of chance, coincidence and impossible odds.

SMITH: I am going to tell you about the most incredible place.

The weird connections,

the dynamic forces that created us.

A species with a brain as complex as yours and mine.

(music)

(music)

(music)

(music)

The human brain is unique.

Not just because of its size, but also its ability.

It can meet challenges that are dangerous, demanding.

(laughs)

SMITH: And wonderfully absurd.

(applause)

(applause)

(applause)

(crowd chanting)

SMITH: In Spain, thousands come together every year

to build towers out of people.

SMITH: A ten-story human tower with the youngest kids on top.

Right.

Claudia and Marina, they're seven.

(crowd gasps)

(music)

(music)

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(crowd gasps)

(applause)

(music)

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(music)

(clapping)

(applause)

(music)

(cheering)

(cheering)

(cheering)

(cheering)

SMITH: Humans are like no other creature on Earth.

We do these things that might seem pointless,

not because we're stupid; because we're smart.

And we work as one.

It's that ability to link our minds together

that put those girls on top of that tower

and also put men and women up in space.

One of them is Leland Melvin.

Former NFL player, mechanical engineer, and astronaut.

Strong, smart, brave,

and pretty much unstoppable.

But Leland nearly didn't make it to space.

An accident in his training brought his dreams to a halt.

MELVIN: The only way to really simulate a spacewalk on Earth

is in a pool.

I remember getting in the suit, putting my gloves on, my boots.

MELVIN: As you're going down in the spacesuit,

you have to clear your ears.

MELVIN: Ten feet down,

I realized that the Styrofoam block,

you press your nose against it to clear your ears,

was missing in my helmet.

I tell the test director, turn the volume in the headset up.

I was straining to equalize the pressure.

And then, I immediately hear nothing but static.

They were pulling me out of the water.

And now I see the flight surgeon walking towards me.

He reaches up and touches my right ear.

He's moving his lips, but I don't hear anything he's saying.

And then I can feel the blood starting to trickle down

on the side of my face.

I'm like, 'Wow, something's really wrong.'

I was completely deaf.

Somehow the connection between my brain and my ears

had been severed,

along with my chances of going to space.

The accident gave me a profound appreciation

in what we take for granted.

The thing that makes us us: our brain.

The human brain sets us apart

from all other creatures on this planet.

It might look like a lump of Jell-O,

but it's the most complex thing in our universe.

Inside, there's a vast network with 100 trillion connections.

That's more than the number of stars in our own Milky Way.

It hosts our memories.

Our sensations.

Our dreams.

And all this depends on tiny cells firing electrical signals.

There's 86 billion of them.

We call them neurons.

SMITH: 86 billion.

Wow.

I'm just glad someone else was counting.

But here's the thing:

most of life on Earth does just fine without a brain.

I'm talking about some of Earth's oldest inhabitants.

Some brainless creatures are so successful,

you can even see them from space.

LINENGER: On a bright, sunny day,

I'm looking down, and for 1,000 miles,

I see an organized city of coral.

PEGGY WHITSON: They just glow.

It's just like the most beautiful art in the world.

MELVIN: This burst of color.

I'd never seen colors that vibrant before.

It's kind of amazing that corals are vast, motionless structures,

that thrive without a brain.

SMITH: In the country of the brainless,

the tiny-brained is king.

Meet this little guy.

He's got more in common with us than you might think.

Inside, he's got neurons, too, just not as many.

About 200.

Kind of a starter kit.

(music)

He's a baby sea squirt looking for a home.

His neurons do simple stuff,

like detect light and twitch his tail.

But here's the thing:

once he's found the right rock, his swimming days are over.

For the rest of his life, he stays put.

He dumps the tail and consumes the neurons that made it move.

Then, it grows into a big, old sea squirt.

Takes 'use it or lose it' to a whole new level.

MELVIN: It's kind of a freaky thought that, you know,

when neurons were developed, they weren't for thinking.

They were for simple motion or movement.

But one day, neurons like those, the ones inside our brains,

would help create things

like rocket ships going to space,

cities and music.

(music)

SMITH: Making a tail twitch to move a yard or two

requires just a few neurons.

However, the more advanced stuff,

that needs an awful lot more.

Life needs to sense its surroundings,

otherwise, it's just flailing around in the dark.

SMITH: There is nothing more complex than the human brain.

But the more complicated something is,

the more ways it can go wrong.

(bird shrieks)

MELVIN: After my training accident,

the doctors couldn't figure out what was wrong with me.

Everything looked physically intact,

but they couldn't fix me.

I was completely deaf.

My goal of getting to space seemed to be thwarted.

But all I could think about

was whether I'd ever hear music that I played again.

Music has been such a big part of my life.

(playing piano)

And so, when the music was silent...

That's when I just broke down and started crying.

SMITH: Leland's ears were fine.

That's not where the problem was.

Because you don't just hear with your ears,

you also hear with your brain.

It's the same for all the senses,

they link our brains to the outside world.

And over hundreds of generations they evolve to suit that world,

no matter how harsh it is.

SMITH: Hunters have lived here for thousands of years.

But to survive, they borrow the senses of a creature

that's been here even longer.

(music)

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(horse snorts)

(music)

(music)

(laughs)

(music)

SMITH: The eagle is like a weaponized telescope.

It can see a fox up to two miles away.

Out here, that's a crucial tool in the fight for survival.

(eagle chirps)

(yells)

(yelling)

(music)

(music)

(music)

(music)

(music)

(chirping)

(yelling)

(music)

(music)

SMITH: But to see like an eagle,

you need more than eagle eyes;

you need an eagle brain.

(squawking)

MELVIN: Eyes deliver masses of data about the world around us,

and all that lifesaving data

needed something powerful to make sense of it.

Simply put, if you're an animal with eyes,

you're gonna need a bigger brain than a sea squirt.

Eyes were a real game changer.

But it's not just the eyes.

Creatures had to develop an array of senses

that are each calibrated to deal

with the ever-changing environment of Planet Earth.

Not just barren desserts,

but these very dense jungles,

teeming ocean reefs,

and even icy Arctic waste.

The planet's varied landscapes played a significant role

in how animals sense.

SMITH: What goes for them, goes for us.

The planet shaped our senses, too.

It's something you might not notice

unless you leave the planet.

MIKE MASSIMINO: Our senses have evolved

to operate on Planet Earth.

MAE JEMISON: When you're up in space,

the inner ear isn't registering an up and down.

MELVIN: So, your sense of orientation

only comes from your eyes.

MASSIMINO: You know that weird feeling

in the pit of your stomach,

when you go over the top of a rollercoaster?

I was basically in that moment for an entire day.

STOTT: We're Earthlings.

That's just who we are.

MELVIN: The evolution of the senses in the primitive brain

have allowed living creatures to interact with our planet

in a way like never before.

But looking at our planet from space,

you can see it's not just varied, it's dynamic.

(thunder)

SMITH: Sometimes, the environment changes quickly,

and when that happens, you have to be just as fast to adapt.

Like when the sea level rises without warning,

and now, you're an island castaway.

(music)

(music)

Macaques are great with their hands.

They peel fruit, climb trees, and do each other's hair.

But on these islands, they do something no other macaques do.

(music)

(music)

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They use rocks as tools to shuck oysters.

Macaques don't normally eat them,

but when they were stranded by the rising sea,

they needed new ways to get a meal.

They weren't born with this skill;

a smart monkey had to work it out.

(music)

(music)

This is something only complex brains can do--

not just sense and react,

but learn,

adapt and problem solve.

But just because a macaque can learn to shuck oysters

doesn't mean it's gonna open a seafood restaurant.

Only a human would make that mental leap.

So, how come we're so different?

SMITH: Monkeys were the first primates in space,

but it wasn't exactly their idea.

In fact, they were probably against it.

So, how come we're the apes with the big ideas?

Well, it's a long story.

A story about something that may not exist

anywhere else in the solar system,

maybe the universe.

Fire.

(rooster crows)

(music)

(music)

SMITH: The Himba people have kept this same fire burning

for generations.

SMITH: As far as we know, this planet is the only one

with the right conditions for fire to burn.

But there's one thing that fire gives us above all else.

SMITH: But cooking food does something

that's way more important than just making it tasty.

MELVIN: Woo! We got fire, are we ready for food?

We as humans have these power-hungry brains.

A big chunk of our body's energy

has to be used to keep them running.

Turn, baby, turn.

By cooking, we're actually breaking down

the cell walls of the food

that releases so many more nutrients and calories,

to help fuel our big brains.

One of the key moments in the history of our species

was when our ancestors harnessed fire.

Alright, get your plates.

The theory goes, cooking let us get more energy

out of every bite of food.

So we spent less time feeding our brain

and more time using it.

SMITH: Try going a day that isn't touched by fire.

You couldn't imagine life without it.

But a brain that could harness fire

may not have evolved in the first place

if it wasn't for a force so powerful,

it made the highest mountains on Earth.

(monks chanting)

(monks chanting)

(music)

(music)

(music)

(music)

SMITH: The fossils tell us that these mountains,

once at the bottom of the sea, were forced high into the sky.

LINENGER: When you're in orbit,

as you come over the Himalaya Mountains,

you almost feel like you need to fire the thrusters a little bit.

You can tell where that subcontinent

just jammed into the Asian continent

and thrust those mountains up.

CHRIS HADFIELD: This collision between the smooth flatness

of India and these rugged, crumpled mountains,

it's like watching a super slow-motion train wreck.

MASSIMINO: The further you get away,

you can kind of see these overarching themes

to the way our planet is formed.

MELVIN: It was forces like these that would transform

one particular corner of our rock

into the cradle of humanity.

The Great Rift Valley in East Africa

was once a lush green forest, a paradise for apes.

(music)

(music)

But the Earth's crust shifted, mountains rose,

and the climate changed, making it a much tougher place to live.

(music)

It's hard to really know exactly how our ancestors adapted

over millions of years.

The changes may have pushed apes to do things

like innovate the tools.

Or walk on two legs.

And even harness fire.

Whatever it was, we came out the other side as early humans,

with bigger brains.

SMITH: We took off across the planet,

and there was one uniquely human skill we brought with us.

Here I am, talking to you,

and some of you are even listening.

What you're hearing is probably the most powerful tool

we've ever mastered.

So, how do you get a brain that can tell a damn good story?

(people speaking different languages)

SMITH: We speak.

(all talking)

SMITH: We link signs and sounds to thoughts and things,

in countless ways, creating almost infinite meanings.

That takes a lot of brain power.

(music)

JULIE MISAKI: Moving to Hong Kong has been amazing.

I'm originally from Japan,

but I've lived in Hong Kong for six years now.

But it has its challenges.

Even just buying dinner can get complicated.

A lot of us foreigners try to learn Chinese,

but it's not always easy.

One word can actually have many meanings,

depending on the tone you use.

For example, if I say xiao, it means burn,

or xiao, it means little,

or xiao, it means laugh.

Use the wrong tone, you could be in big trouble.

MELVIN: It's only us human beings

that have developed complex language.

Unlike many other languages,

Chinese uses the musical areas of the brain

to extract meaning from all those tones.

And that takes a lot of processing power.

But the really big question is

why we have any language at all.

It's partly due to the size of our big brains.

But there could be another factor at play.

One theory is that it was something really tiny.

There's a version of a gene, called FOXP2,

that only us humans have.

Take it away, and you'll struggle to talk.

No one knows how we've got this mutation.

(speaking Japanese)

But we do know...

(speaking Japanese)

...it gave us more precise control

over our mouth and our tongue muscles.

And that let us make more sophisticated sounds,

helping us turn thoughts into words.

SMITH: Small genetic twists turned us

from a bunch of folks who grunt

to a species that can tell xiao from xiao,

from xiao.

Sharing ideas, communicating them,

lets us do things that alone would be impossible.

Something pioneers know full well.

(roaring)

(music)

ROCKY ROBINSON: Okay, let's do it.

I'm getting all kinds-- I've wiped it off,

but I have all kinds of salt on me.

My shield got covered in salt.

MAN: Turn the water pump off.

ROBINSON: We're here in Bolivia

trying to break the motorcycle world land speed record.

We probably don't have a better opportunity

than we have right now to see just how fast this bike will go.

(music)

(music)

This is a huge team effort.

We communicate a lot, the team and I.

Communication is a huge advantage.

It takes so many people

to come up with a machine of this caliber.

(engine revving)

You have all these people doing all this stuff for you,

but once that canopy closes...

MAN: You ready?

ROBINSON: You're all alone.

MAN: 45, hit it, Rocky!

MAN ON RADIO: Full speed, 333.9.

MAN ON RADIO: Roger, six.

ROBINSON: Whoa, whoa, whoa!

There's something wrong with the motor.

MAN ON RADIO: He's coming to a...he's slowing down.

Everything okay down there?

MAN ON RADIO: Seems okay.

ROBINSON: It is going really strong,

and it's, whoa, whoa, whoa.

MAN: Main off?

ROBINSON: Yeah. MAN: Okay.

ROBINSON: Got up to right around 378 miles an hour,

and then the turbo coupler came off.

It's frustrating.

It's a huge team effort,

and, you know, we're all trying to reach our goal.

Probably 95% of the time there is something going wrong.

That's why records last so long.

Everything about land speed racing

is learning what's new and how to improve things.

We learn a lot, and I think we can put that to good use

in the future.

SMITH: I'm with Rocky on this.

You get knocked down, you get back up again.

Communicating helps you face failure without fear.

But our brains adapt.

So if we lose the ability to communicate,

our brain might find a work-around.

It's flexible.

Talk to Leland about it.

MELVIN: During the time of recovery

from my hearing accident,

there was a point when I could feel my brain rewiring itself

to hear again.

The brain over time can make adjustments

to compensate for losses or changes.

And I think that's what happened to me.

My hearing started coming back

about three weeks after my accident.

But it took two more years for me to recover properly.

Then finally, the chief medical officer for NASA

pulled out a piece of paper

that said, 'You are now cleared to fly in space.'

That was one of the most incredible days of my life.

I never took my brain for granted again.

(crowd cheering)

SMITH: With that flexible brain,

we learn, adapt, and problem solve.

Our brains give us language,

allowing us to share those lessons with others.

And writing lets us pass on that knowledge through time.

LINENGER: All that human brain power,

all that knowledge through written textbooks,

through calculations, through mathematics.

HOFFMAN: That just led to a huge explosion

in the development of civilization.

WHITSON: We can get a lot smarter,

because we can learn a lot more from the previous generations.

SMITH: Humanity is linked together by a network of minds

that spans time and space.

And that's helped us create things of dazzling complexity.

The most complex one we've ever made is floating above us.

MAN ON RADIO: Ignition sequence start.

Five, four, three, two, one.

MELVIN: You're lifting off of the planet.

Feeling 3 Gs on your chest

as you're being propelled to the cosmos.

It is one heck of a ride.

MELVIN: After losing the sense of hearing,

it took so many years for me to get to the launchpad,

but it just took a few minutes to get to orbit.

MAN ON RADIO: Good morning, Houston.

MELVIN: We got to space, I saw the planet.

It just blows your mind.

This burst of color.

I've never seen colors that vibrant before.

And I almost had to, like, smack myself to get back to work.

(music)

MAN ON RADIO: If you could get the other...

the expedition four crew, that we have them in sight.

MELVIN: And then I saw this little dot out on the horizon.

And we get closer and closer and closer.

(music)

The first time I saw the space station flying overhead,

I never knew how complex a vehicle it was.

(music)

You know, you could see the intricate design

in these modules, all these things

that were envisioned by the human brain.

(music)

(music)

WHITSON: So, you know, when you approach it,

it's just so beautiful.

It's an amazing, amazing engineering marvel.

HOFFMAN: There's no question that the space station

is the greatest international scientific project

that's ever been undertaken.

LINENGER: It's like, wow, this thing is awesome.

And I'm gonna get to live on that thing

for four or five months.

(music)

MAN ON RADIO: Coming in now and carrying the camera,

mission specialist Leland Melvin.

MAN: How you doing?

MAN: Bull in a china shop, man.

(laughs)

MELVIN: Climbing this hill to space

was one of the hardest things I've ever done.

I never imagined myself going deaf,

I never imagined coming back

and getting this opportunity after that accident.

(music)

And it's really a similar story for all of humankind.

Everything we've achieved as a species

is the product of a lucky chain of accidents.

SMITH: To get here, we needed a planet to congeal out of dust.

In the right place for life to form and mold our world,

allowing us to breathe and grow complex.

We needed to be shielded from our sun,

gifted with a moon,

and granted seasons.

We needed just enough bombardments

and near-annihilations

to let life meander

through its twists and turns

and evolve a species

with a brain as complex as yours and mine.

(baby cries)

(music)

(music)

MELVIN: When I was on the space station,

looking back at the planet,

it gave me a profound appreciation

in what we take for granted.

Humans are a wonderful, extraordinary oddity.

(music)

SMITH: Good job, man, great game.

With this blob of Jell-O,

these 86 billion neurons,

we've left the planet

and looked far, far out into the universe,

trying to unravel the mysteries of the cosmos.

But no matter how far out we look,

the most far-out thing we've ever found

is right between our ears.

(music)

(music)

Next time...

What does it feel like when you finally come back to Earth?

Is there really no place like home?