All language subtitles for A1CC866676C530A0271BBD63EF70AE75_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 4 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.

Now, insects don't have lungs.

Life-giving oxygen has 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 have 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, it got a
really bad case of indigestion.

And termites wouldn't evolve for at least
another hundred 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 millions
of trees that were 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, keer.

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.

With every step I take, I move about a
thousand years closer to the present and

away from the world of 300 million years
ago.

50 million years later lies that way.

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

An event of unequaled carnage.

The Permian is the
darkest corridor in this

memorial to the broken
branches on the tree of life.

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
sub-freezing.

During lulls and 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 coal 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 water slowly

mixed, raising the temperature of the once
frigid depths of the seafloor.

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 star,
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
shakeup.

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 tell-tale 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 and 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 Wagner 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, Wagner had
happened upon an intriguing

paper in the stacks
of his university library.

It puzzled Wagner that fossils of the same
species of the 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

Wagner 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?

Wagner 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, Wagner becomes the toast of the
scientific world, right?

Not exactly.

Geologists ridiculed Wagner's hypothesis
of continental drift.

They preferred their imaginary natural land
bridges to explain away Wagner's evidence.

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

Wagner had no convincing answer.

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

Despite this, Wagner
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.

The 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 Heason, a graduate student from
Iowa, has just returned from a lengthy

expedition to map the ocean floor using
sonar.

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, geez, Marie, come on.

This is just more girl talk.

You're not in enough trouble with everyone
here already?

This sounds too much like continental
drift.

You want to 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
sea floor map, the

earthquakes fell right
along the rift valley.

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

Heason 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 a thousand 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.

This is a world where there is no sun.

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
fifty 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.

And 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 left over 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
time scale, 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.

And that little guy is 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 Pangea.

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 100 pounds survived
the catastrophes of the late Cretaceous.

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%
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 savannah.

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.

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, falling on the
edge of the northern icecap.

Sometimes, it made the summers there
colder.

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, in

orbit 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's sea level falls by
more than 400 feet, uncovering

wide areas of land along
the edges of the continents.

15,000 to 25,000 years ago,
there was a period when the ice

reached a height receded,
exposing a temporary land bridge.

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

Bands of wanderers cross 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 river 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 is 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 3 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

hardy 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.

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, 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
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 by 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,

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.