All language subtitles for 181765A941A2D7187BC7EB3A2F70BFAF_eng

Yes, this is home.

This is Earth.

Having trouble
finding a familiar continent?

The past is another planet.

Actually, many.

I'm standing on the great expanse of time
that has elapsed since the big bang.

In order to think about it,
we've compressed it all into a single year.

It's the early morning of December 23rd...

on this cosmic calendar of ours,
or about 350 million years ago...

when our world
was a mere four billion years old.

Earth looks so different...

you might not even know the place.

The stars wouldn't help you.

Even the constellations
would have been different back then.

The dinosaurs were still
more than 100 million years in the future.

There were no birds, no flowers.

And the air was different too.

The atmosphere had more oxygen than
at any other time in Earth's history...

before or since.

This allowed insects
to grow much larger than they do today.

How? Insects don't have lungs.

Life-giving oxygen
is taken in through openings...

in the outside of their bodies...

and transported
through a network of tubes.

If an insect were too large...

the outer reaches of these tubes
would absorb all the oxygen...

before it could ever get
to its internal organs.

But during the Carboniferous period...

the atmosphere
had almost twice the oxygen as today.

Insects could then grow much bigger and
still get enough oxygen in their bodies.

That's why the dragonflies here
are as big as eagles...

and the millipedes, the size of alligators.

So why was there so much oxygen
back then?

It was produced by a new kind of life.

What kind of life could've changed
the Earth's atmosphere so dramatically?

Plants that could reach for the sky:

Trees.

In their competition for sunlight,
trees evolved a way to defy gravity.

Before trees, the tallest vegetation
was only about waist-high.

And then something wonderful happened.

A plant molecule evolved
that was both strong and flexible...

a material that could support
a lot of weight...

yet bend in the wind without breaking.

Lignin made trees possible.

Now life could build upward.

And this opened a whole new territory...

a three-dimensional matrix
for communities far above the ground.

Earth became the planet of the trees.

But lignin had a downside.

It was hard to swallow.

When nature's demolition crew,
the fungi and bacteria...

tried to eat anything with lignin in it...

they got a really bad case
of indigestion.

And termites wouldn't evolve
for at least another 100 million years.

What to do with all those dead trees?

It took the fungi and bacteria
millions of years...

to evolve the biochemical means
to consume them.

Meanwhile, the trees just kept
springing up, dying, falling over...

and getting buried by the mud
that built up over eons.

Eventually, there were hundreds
of billions of trees...

entombed in the Earth,
buried forests all over the Earth.

What possible harm could come from that?

This cliff in Nova Scotia
is another kind of calendar.

It tells the story of that other world
that once flourished right here.

And this is the death mask
of that 300-million-year-old tree.

It was cast by minerals that
replaced the original wood, cell by cell.

In other words, a fossil.

The tree surrendered its organic molecules
to the environment long ago...

its carbon and water.

Only its shape remains.

When this tree was alive,
it took in carbon dioxide and water...

and used sunlight to turn them
into energy-rich organic matter.

The tree gave off oxygen
as a waste product.

That's what trees and
other plants still do.

When plants die, they decay.

And this reverses the transaction.

Their organic matter combines with oxygen
and decomposes...

putting carbon dioxide back into the air.

This balances the books...

for the chemistry of Earth's atmosphere.

But if the trees are buried
before they can decay, two things happen.

They take the carbon
and the stored solar energy with them...

and leave the oxygen behind...

to build up in the atmosphere.

That's what happened
around 300 million years ago.

There was an oxygen surplus.

That's how the bugs got so big.

And what became of all that buried carbon?

It lay there for eons
before dealing life on Earth...

its most devastating blow of all time.

There are places on this planet
where you can walk through time...

and read the history written in the rocks.

This beach in Nova Scotia is one of them.

Every layer is a page.

Each one tells the story of a flood...

one after another, over millions of years.

The layer cake of flood deposits
was slowly buried...

and turned into rock by heat and pressure.

The same forces that built mountains...

then tilted and uplifted them,
along with the entombed fossil forest.

The newer layers were always
deposited on top of the older ones.

All the pages are in the correct order...

bearing witness to what happened here...

over millions of years.

Back that way lies the more distant past.

And with every step I take...

I move about 1000 years
closer to the present...

and away from the world
of 300 million years ago.

Fifty million years later lies that way.

This was the beginning of the end
of the Permian world...

an event of unequalled carnage.

The Permian is the darkest corridor
in this memorial...

the Halls of Extinction.

Death has never come so close
to reigning supreme on this world...

in the quarter billion years since.

The eruptions, in what is now Siberia,
lasted for hundreds of thousands of years.

The lava flooded and buried
more than a million square miles.

This event dwarfs any volcanic eruption
in historical times.

Huge quantities of carbon dioxide
came pouring out of the volcanic fissures.

This greenhouse gas warmed the climate.

And this is where the long-buried forests
of the earlier Carboniferous period...

reenter the story.

During the intervening 50 million years...

those trees had turned
into immense deposits of coal.

And as it happened, one of the world's
largest accumulations of coal...

was buried right there in Siberia.

The heat from the lava baked the coal...

driving methane and sulfur-rich gases
out of the ground.

They were laden with toxic
and radioactive ash particles.

Coal smoke.

This witch's brew polluted the atmosphere
and radically destabilized Earth's climate.

A sulfuric acid haze blocked incoming
sunlight and darkened the planet.

Global temperatures plummeted
to subfreezing.

During lulls in the eruption,
the acid haze fell back to the surface.

But the carbon dioxide remained
and built up in the atmosphere...

to cause global warming.

Years of frigid cold alternating
with millennia of stifling heat...

battered a dwindling population
of plants and animals.

They had no chance to adapt
to the drastic swings in climate.

As the global warming continued...

the surface and the bottom waters
slowly mixed...

raising the temperature
of the once-frigid depths of the sea floor.

Methane-rich ices that had been frozen
in the sediments began to melt.

Newly liberated methane gas made its way
to the surface, and into the atmosphere.

Methane traps heat far more efficiently
than carbon dioxide...

so the climate got even hotter.

And the methane also destroyed
the ozone layer in the stratosphere.

The natural sunscreen
that protects life

from deadly ultraviolet
rays was eaten away.

The circulatory system
of the world ocean shut down.

These stagnant waters
became oxygen-starved...

killing almost all the fish in the sea.

But one kind of life flourished
in this brutal environment.

Bacteria that produced
deadly hydrogen sulfide gas...

as a waste product.

That was the last straw.

The poison gas killed almost all the
remaining plants and animals on the land.

This was the Great Dying...

the closest life on Earth
has ever come to annihilation.

Nine in ten of all species perished.

It took a long time
for life to bounce back.

For a few million years,
Earth could have been called...

the Planet of the Dead.

We are descended from one of the
few species that managed to squeak by.

You are human and alive
at this very moment...

because they managed to endure,
conveying their DNA...

through one of the most treacherous periods
in the history of life.

This mountain was made entirely by life.

The life that flourished
back in the glory days of the Permian...

before all hell broke loose.

This is part of the 400 mile-long
Guadalupe Mountain chain...

that runs through Texas and New Mexico.

It's the world's largest fossil reef.

All this was once a great inland sea.

The reef flourished and grew
for millions of years...

and was home to multitudes
of sponges, green algae...

and animals too small to see.

When these creatures died...

they sank to the bottom
and were buried in the silt.

Over millions of years...

their remains were converted
into oil and gas.

Eventually, the basin silted in
and the reef died.

This marine ghost town
was then buried a mile beneath the surface.

Later, tectonic forces lifted the
skeletal reef high above sea level...

where it was eroded and sculpted
over eons by wind and rain.

Just imagine what this place looked like
275 million years ago...

when it was a vibrant,
tropical inland sea...

dotted with islands, brimming with life.

Until about 220 million years ago...

New England and North Africa
were next-door neighbors.

There was no such thing
as the Atlantic Ocean.

Those thin blue fingers at the center,
they were lakes.

They were the first outward signs...

that the supercontinent
was splitting apart...

and that life on Earth
was due for another big shake-up.

A million years later,
the lakes became a long bay...

which would grow into the Atlantic Ocean.

These profound changes at the surface...

were merely symptoms of a drama
that was unfolding far beneath...

in the depths of the Earth.

By the time we got here...

the telltale traces of global upheaval were
buried at the bottom of the deep blue sea.

We were completely cut off from
the great story of Earth's violent past.

A species of amnesiacs trying
to find out who we were...

and what happened before we awakened.

In 1570, Abraham Ortelius created
the first modern world atlas...

reflecting the discoveries
of the previous 80 years:

the Golden Age of Exploration.

Before the ink was dry...

Ortelius stepped back
from his masterpiece...

mend became the first of many
to notice the striking puzzle-piece fit...

between the continents
on either side of the Atlantic.

He later wrote that the Americas
were torn away from Europe and Africa...

by earthquakes and floods.

But Ortelius observation
remained nothing more than a hunch...

for the next couple of centuries...

until an early 20th century
German astronomer and meteorologist...

amassed the evidence
to build the scientific case for it.

Alfred Wegener had been drafted
during the First World War...

but was wounded soon after.

As he recovered in a field hospital,
he scoured scientific literature...

for clues to the Earth's past.

Years before, Wegener had happened
upon an intriguing paper...

in the stacks of his university library.

It puzzled Wegener that fossils of the
same species of a now-extinct fern...

were reported to be found
on both sides of the Atlantic.

Even more curious...

were the discoveries of fossils
of the same dinosaurs on both continents.

In the early 20th century...

geologists explained
how life crossed the oceans...

by imagining that land bridges
had once existed between them.

It was thought that these bridges
gradually disintegrated...

and vanished
beneath the waves long ago.

But there was one piece of evidence
that convinced Wegener...

that the prevailing scientific view
must be wrong:

the Earth itself.

Why would a mountain range
cross the oceanic divide...

to continue on another continent?

And why would you find
the same unique pattern...

in the layers of rocks
in both Brazil and South Africa?

And another thing: Under what circumstances
could tropical plants have flourished...

in the frozen wastes of the Arctic?

Wegener concluded that there was
only one logical solution to this puzzle:

There had once been a single
supercontinent on Earth.

He named it Pangaea.

So Wegener becomes the toast
of the scientific world, right?

Not exactly.

Most geologists ridiculed
Wegener's hypothesis of continental drift.

They preferred
their imaginary natural land bridges...

to explain away Wegener's evidence.

How, they asked, could a continent plow
through the solid rock of the ocean floor?

Wegener had no convincing answer.

He became the laughingstock of the field,
a pariah at scientific conferences.

Despite this,
Wegener continued to fight for his ideas...

conducting daring research expeditions
to gather evidence.

On one of these, he learned that colleagues
were trapped on an ice cap without food.

On his way back from the mission,
he became lost in a blizzard.

A day or two after his 50th birthday,
he disappeared...

never knowing that, in time,
he would be vindicated...

and come to be viewed as one of
the greatest geologists in history.

Scientists are human.
We have our blind spots and prejudices.

Science is a mechanism
designed to ferret them out.

Problem is, we aren't always faithful
to the core values of science.

Few people knew this better
than Marie Tharp.

It's 1952, and Marie
is patiently enduring...

the slights of her fellow members
of the geology department.

Her degrees in geology and mathematics
count for little with them.

Bruce Heezen,
a graduate student from Iowa...

has just returned from a lengthy expedition
to map the ocean floor using sonar.

Unh. Will you do something with these?

Bruce, look. It's all come together.

There's this giant rift valley that runs
through the bottom of the Atlantic.

Ah, jeez, Marie, come on.
This is just more girl talk.

You're not in enough trouble
with everyone already?

This sounds too much like continental
drift. You wanna end up like Wegener?

But Marie would not be dissuaded.

Years later...

when Marie and Bruce placed a map
of oceanic earthquake epicenters...

on a light table over her seafloor map...

the earthquakes
fell right along the rift valley.

This was the smoking gun
for Wegener's moving continents.

Heezen now knew
that Marie had been right all along.

Together, they created
the first true map of the Earth...

including the ocean floor.

We were at last ready
to read the autobiography of the Earth.

Let's take the Ship of the Imagination...

to a part of the world that has
been off-limits to all but a few of us.

Two-thirds of the Earth lies beneath
more than 1000 feet of water.

It's a vast and largely
unexplored frontier.

Everybody knows the Alps and the Rockies...

but some of the world's most amazing
mountain ranges are hidden from view.

Below a thousand meters, we enter
a world where there is no sunlight.

Hidden in the darkness,
a world of wonders.

This is the longest submarine
mountain range in the world...

the Atlantic Mid-Ocean Ridge.

It wraps around our globe
like the seam on a baseball.

The past is another planet...

but most of us don't really know this one.

We don't see the mountains for the water.

This is the world that Marie Tharp
was the first to imagine.

The highest peaks of the ridge rise
over four kilometers above the ocean floor.

There are sprawling mountain ranges
and canyons too.

We've now entered the Marianas Trench,
the deepest canyon on Earth...

more than ten kilometers deep.

It formed when tectonic forces
pushed the seabed...

under the adjoining continental plate.

More people have walked on the moon
than have ever been down here.

The pressure here
is a crushing eight tons per square inch.

Being this deep in the ocean...

is like having 50 jumbo jets
stacked on top of you.

Yet even here, life has taken hold.

The fact that sunlight
can't penetrate the deep ocean...

doesn't mean there isn't light down here.

Many underwater species glow in the dark...

through a process called bioluminescence.

Our long history as land mammals,
denizens of the sunlit world...

hasn't prepared us
for the amazing variety of life...

that evolution has crafted
in the deep oceans.

Since there's no sunlight down here,
there's no photosynthesis.

That means there are
no plants to feed on...

and yet, even here,
in a world of permanent midnight...

there's a thriving food chain.

It begins with a process
called chemosynthesis.

These microscopic creatures have learned
to eat what's pouring out of that vent...

a noxious compound
called hydrogen sulfide.

That thick black smoke
provides the chemical energy...

that makes life possible here.

Tiny crustaceans eat the bacteria...

and the larger animals eat the crustaceans.

One day, on some future Earth...

these mountains could very well end up
above the water.

Tectonic forces continue
to shape our planet.

The future is also another planet.

It was a volcano like this one
that created the Hawaiian islands...

millions of years ago.

We live on the crust
of a seething cauldron.

At the center of our planet,
there's an iron core.

It's nested inside of a larger,
liquid iron shell.

Wrapped over this
is the part called the mantle.

It's rocky, but hot and viscous.

Like a pot of soup cooking on a stove,
the mantle is churning.

What keeps it moving?

Two things: the heat leftover
from Earth's formation...

and the decay of radioactive elements
in the core.

And this outer layer, the crust...

where you and me
and everyone we know lives...

it's only as thick as the skin on an apple.

The mantle drags
the solid overlying crust along with it.

The crust resists
because it's cool and rigid.

From time to time,
it reaches the breaking point.

When that happens, the Earth quakes.

It's not because somebody misbehaved
and is being punished.

It's due to random forces
that are governed by the laws of nature.

Our sense of the stability
of the Earth is an illusion...

due to the shortness of our lives.

If we could watch our planet
on its own timescale...

in which big changes
take millions of years to play out...

we would see it
as the dynamic organism it really is.

This is the world
of the late Triassic Period...

about 200 million years ago.

That little guy?

It's one of our distant ancestors.

He lived in Newark, New Jersey.

Wherever you walk on Earth...

lost worlds lie buried beneath your feet.

Fifty or a hundred million years ago...

even the most seemingly ordinary places
have been the scene of epic change.

These Palisades are a monument to the
breakup of the supercontinent Pangaea.

The sequence of volcanic
eruptions that made

these cliffs also led to
the next mass extinction.

The one that ended the Triassic world.

But a catastrophic extinction event
for one species...

is a golden opportunity for another.

The Triassic extinctions offered one group
that had been around for a while...

the chance to take center stage.

The dinosaurs had a good long run
for 170 million years.

Back then, India was an island.

It crept northward at the pace
of a few inches per year...

on its slow but inexorable rendezvous
with Asia.

Then, once again, the molten rock
beneath Earth's surface burst forth...

and flooded a huge area of western India.

The knockout punch
literally came out of the blue.

Few animals larger
than a hundred pounds...

survived the catastrophes
of the late Cretaceous.

The dust cloud brought night and cold
to the surface for months.

The dinosaurs froze and starved to death.

But there were small creatures
who took shelter in the Earth.

And when they emerged...

they found that the monsters who had hunted
and terrorized them were gone.

The Earth was becoming
the Planet of the Mammals.

And the Earth continued
its ceaseless changing.

This was once a desert
where nothing could grow.

It was a million square miles
of sand and salt...

far more hostile
than any environment on Earth today.

Daytime temperatures
were hot enough to bake bread.

And it was more than a mile below
sea level, so the atmospheric pressure...

was about 50 percent higher
than what we're used to.

It would be hard to think of a more
unpromising environment on this planet.

Yet this was the basin of the Mediterranean
five and a half million years ago...

before it became a sea.

The Earth never stops moving for long.

The natural dam at the western end
of the deep basin gave way...

probably due to earthquakes.

And the deluge began.

The torrential waters rushed in at a rate
40,000 times greater than Niagara Falls...

turning a vast desert into the
Mediterranean Sea in less than a year.

There were as yet no humans
to witness this enormous flood...

nor to admire the beauty it created.

Meanwhile, half a world away...

a broad channel
separated North and South America...

allowing ocean currents to flow
from the Atlantic into the Pacific Ocean.

Tectonic forces gradually brought
these two continents together...

closing the channel
and creating the Isthmus of Panama.

This reorganized the worldwide pattern
of ocean currents...

which, in turn, affected
the global climate.

In Africa, the lush green forest canopy
gave way to a sparser landscape.

Some species that were highly specialized
for life in the trees became extinct.

But the generalists, the ones
that could find a way to make a living...

no matter what life threw at them,
endured and evolved.

Our ancestors had once burrowed deep
in the ground...

to avoid predators who stalked the surface.

But when the dinosaurs perished,
they emerged into the daylight...

and over the eons, made new lives
in the branches of the trees.

They developed opposable thumbs and toes
for swinging from branch to branch...

across the broad canopy of treetops,
where all their needs were fulfilled.

They could also walk upright,
but only for short distances.

With so many trees around,
they didn't have to go very far.

But then it got colder,
and the trees thinned out.

Broad grasslands sprang up...

and our ancestors were forced
to traverse them in search of food.

You needed a totally different skill set
to make it on the savanna.

In the old days, you could sit perched
on your tree branch...

and watch the big cats
from a safe distance.

Now you were playing
on the same dangerous field.

The survivors were those
who evolved the ability...

to walk great distances on their hind legs
and to run when necessary.

This changed the way they looked
at the world.

Hands and arms
were no longer tied up with walking.

They were free to gather food
and pick up sticks and bones.

These could be used as weapons and tools.
Think of it.

A change in the topography
of a small piece of land...

half a world away reroutes ocean currents.

Africa grows colder and drier.

Most of the trees
can't withstand the new climate.

The primates who lived in them
have to seek other homes...

and before you know it,
they're using tools to remake the planet.

The Earth has shaped the course
of human destiny...

but so has the invisible pull
of distant worlds.

The planets have influenced our lives...

but not in the way you think.

The gravitational pull of Venus...

small but close...

and that of Jupiter, distant but massive...

tilted the Earth's axis
this way and that...

and ever so slightly
tweaked the shape of its orbit.

This periodically altered
the amount of sunlight

falling on the edge of
the northern ice cap.

Sometimes
it made the summers there colder...

and the glaciers advanced southward
from one year to the next...

grinding and scraping,
and crushing everything in their path.

That's what we call an Ice Age.

At other times,
changes in Earth's axis and orbit...

made the Arctic summers warmer.

And the melting glaciers began to retreat.

Imagine how resourceful
our ancestors had to be...

in order to survive
these radical changes in climate.

With each glacial period...

the ice sheets grow
at the expense of the oceans.

The world sea level falls
by more than 400 feet...

uncovering wide areas of land
along the edges of the continents.

Fifteen to 25,000 years ago,
there was a period when the ice receded...

exposing a temporary land bridge.

The gateway to the other half
of the planet swings open.

Bands of Wanderers crossed the land bridge
to North America and parts south.

About 10,000 years ago, the manic swings of
the climate and sea levels came to a stop.

A new and gentler climate age began.

It's the one we live in now.

When the great ice sheets melted,
the sea rose to its present height...

and the rivers carried silt
from the highlands...

to build great delta plains
where they met the sea.

On those fertile plains,
we learned a new way of life.

How to grow things,
to feed ourselves and more.

For most of us, this meant an end
to a million years of wandering.

The way the planets tug at each other,
the way the skin of the Earth moves...

the way those motions affect climate and
the evolution of life and intelligence...

they all combined to give us the means
to turn the mud of those river deltas...

into the first civilizations.

There's nothing like
an interglacial period,

one of those balmy
intermissions in an ice age.

And the great news
is that this one is due to last...

for another 50, 000 years.

What a break for our kind.

Just one problem.

We can't seem to stop
burning up all those buried trees...

from way back in the Carboniferous Age,
in the form of coal...

and the remains of ancient plankton,
in the form of oil and gas.

If we could, we d be
home free, climate-wise.

Instead, we are dumping carbon dioxide
into the atmosphere...

at a rate the Earth hasn't seen since
the great climate catastrophes of the past.

The ones that led to mass extinctions.

We just can't seem to break
our addiction to the kinds of fuel...

that'll bring back a climate
last seen by the dinosaurs.

A climate that will
drown our coastal

cities and wreak havoc
on the environment...

and our ability to feed ourselves.

All the while, the glorious sun pours
immaculate, free energy down upon us...

more than we will ever need.

Why can't we summon
the ingenuity and courage...

of the generations that came before us?

The dinosaurs never saw
that asteroid coming.

What's our excuse?

There's a corridor in
the Halls of Extinction

that is, right now,
empty and unmarked.

The autobiography of the Earth
is still being written.

There's a chance
that the end of our story lies in there.

Congratulations.

You're alive.

There's an unbroken thread that stretches
across more than three billion years...

that connects us to the first life
that ever touched this world.

Think of how tough,
resourceful and lucky all

of our countless
ancestors must have been...

to survive long enough to pass
on the message of life to the next...

and the next and the next generation...

hundreds of millions of times...

before it came to us.

There were so many rivers to cross,
so many hazards along the way.

Predators, starvation,
disease, miscalculation...

long winters, drought, flood and violence.

Not to mention the occasional upheavals
that erupted from within our planet...

and the apocalyptic bolts
that come from the blue.

No matter where we hail from
or who our parents were...

we are descended from the hearty survivors
of unimaginable catastrophes.

Each of us is a runner in the longest and
most dangerous relay race there ever was...

and at this moment,
we hold the baton in our hands.

The past is another planet.

And so is the future.

Some 250 million years from now...

many geologists think
that the lands of the Earth...

will be united once again.

All this beauty will have vanished
and the Earth of our moment in time...

will take its place among the lost worlds.

The great internal engine of
plate tectonics is indifferent to life...

as are the small changes
in the Earth's orbit and tilt...

and the occasional collisions
with little worlds on rogue orbits.

These processes have no notion
of what has been going on...

over billions of years
on our planet's surface.

They do not care.

Each of us is a tiny being...

riding on the outermost skin
of one of the smaller planets...

for a few dozen trips
around the local star.

The things that live
the longest on Earth...

endure for only about a millionth
of the age of our planet.

So, of course, the individual organisms
see nothing of the overall pattern.

Of changing continents...

climate...

evolution.

That we understand
even a little of our origins...

is one of the great triumphs
of human insight and courage.

Who we are and why we are here
can only be glimpsed...

b y piecing together something
of the full picture...

which must encompass eons of time...

millions of species...

and a multitude of worlds.

In this perspective, it's not surprising
that we're a mystery to ourselves...

and that despite our manifest pretension...

we are far from being masters
of our own little house.

This new corridor has no name above
the entrance to designate its epoch...

and we don't yet know which failed species
will be memorialized within its walls.

What happens here, in countless ways, both
large and small, is being written by us.

Right now.