Original subtitles

[ Man Narrating] Pioneers on their way to California...

cross the American frontier...

and run headlong into a deadly roadblock.

A trap 200 million years in the making...

that for one infamous group...

will end in horror.

An epic tragedy with surprising roots in big history.

We think of history as a timeline...

a series of events stretching a few thousand years into the past.

It's time to think bigger.

Instead of a line, imagine a web of infinite connections...

interacting over billions of years...

linked together to create everything we've ever known-

our universe, our planet...

and us.

When we consider our most epic moments through the lens of science...

we unleash a revolutionary new idea-

the movement of atoms steer the movements of men...

civilizations, galaxies.

History as we know it is about to get big.

[ Narrator] America is growing.

“Yam!

Ana' in a great migration across the continent...

thousands brave an arduous trek west...

in search of land and prosperity.

Most will succeed...

but not all.

In just six months...

the 81 members of the Donner party cover 1,500 miles...

and climb their final obstacle- the High Sierras.

We imagine migrants and their wagon trains and so on...

heading off in that direction looking at what's coming.

This terrifying barrier.

[ Narrator] A 10-day blizzard traps the Donners...

in one of Earth's most extreme climates.

Half will perish.

Others resort to cannibalism to survive.

Traditional history tells us their horrible fate is a cautionary tale.

But big history reveals that the Donner story is pan' of a bigger pattern...

a surprising link between mankind...

and the ground beneath our feet.

Because of their thin air, freezing temperatures...

and perilous terrain...

mountains are nature's barriers.

A single range can stretch more than 4,000 miles.

And the highest peaks on Earth reach six miles into the sky.

Big history connects these barriers to the global migration of mankind.

This is the Earth as we know it-

seven separate continents...

dotted with dozens of different mountain ranges.

The Himalayas, the Alps...

the Andes, the Rockies.

But what most people don't realize...

is that these mountains aren't separate at all.

They're connected...

forming just two major mountain systems.

In the east is the Alpide Belt...

one gigantic system stretching across all of Europe and Asia.

It runs from the Apennines to the Alps to the Balkans through Turkey...

right on through to the great Himalayan range.

[ Narrator] Its origin 70 million years ago-

a monumental collision of the Earth's tectonic plates...

the south crashing into the north.

[ Markley ] Africa and India were moving from the south...

and gradually heading north and colliding with Eurasia.

This led to this great Alpide mountain range.

[ Narrator] The Alpide Belt may contain the highest peaks...

but there's another, larger mountain system on Earth.

It circles the Pacific Ocean...

stretching the length of the Americas in the west...

and Asia in the east...

to create the formidable Ring of Fire.

Together, the Alpide system and the Ring of Fire...

divide up the continents.

But big history shows us that for mankind...

it's how they divide us that matters.

As humans look for places to settle around the planet...

the prime spots sit within the east-west temperate zone...

where crops and animals thrive.

[ Markley] Human migration tends to run east-west.

The length of the days remains the same...

the temperature tends to remain about the same...

the rainfall tends to be pretty consistent.

That means that whatever you were growing in one place will probably transfer.

[ Narrator] In Europe and Asia, the Alpide Belt runs east-west...

so people here can migrate unobstructed alongside the mountains...

to reach new farmlands.

Not so on the other side of the world.

The amazing thing about the Ring of Fire is that it's a north-south system...

instead of an east-west system like the Alpide Belt.

[ Narrator] North-south mountains are a roadblock.

They cut people off from desirable land on the other side...

and make it harder for mankind to move around.

In North America, pioneers face a series of massive obstacles...

as they settle the West.

First, the Appalachians.

A thousand miles later, the Rockies.

And after that, the Sierras.

These ranges run north to south.

They block the way.

So for settlers like the Donner party...

Crossing them is dangerous but unavoidable.

And the mountains that divide the earth...

also separate us from each other...

and even bring us to war.

Big history connects forward to eastern Europe...

where the Balkan mountains divide people...

by ethnicity and religion.

[ Man ] There always has been a lot of conflict in the Balkans.

It's this place that's always boiling with tensions.

And it's even a word we have: to balkanize.

It means to separate into little pockets. You end up balkanized.

[ Narrator] This balkanization leads to the assassination...

of Austrian Archduke Franz Ferdinand in 1914...

[ Gunshots ]

Plunging Europe into the First World War.

It's a phenomenon that' we see wherever mountains divide us.

Like in the Appalachians...

where isolated mountain valleys are home to feuding clans...

like the Hatfields and McCoys.

[ Man ] The chain of Appalachians...

certainly set up very independent clans of families...

and they developed a number of blood feuds...

instead of allowing normal justice systems...

at some county courthouse miles away.

[ Narrator] Mountains divide us and steer our movements around the planet.

But they have another power that we're willing to kill and die for.

How do we know?

There are clues hidden in the oldest murder mystery on earth.

[ Narrator] Big history reveals how mountains steer the movements of man...

divide us into feuding clans...

even spark a world war.

But mountains have another secret that links them to the story of man.

Big history connects back to the Bronze Age...

and one of the oldest-known murders on earth.

High in the Alps, a young man takes his final steps...

brought down by an arrow in the back.

5,300 years later, in 1991...

his frozen body emerges from a melting glacier.

He is known as Ötzi the Iceman.

Ötzi the iceman died in the mountains, but he clearly didn't live in the mountains.

He was up there for a reason.

You have to figure he was looking for something.

[ Narrator] Scientists recover two intriguing clues...

his ax blade, made almost entirely of pure copper...

and arsenic residue in his hair.

[ Markley] The evidence of the copper ax and the arsenic residue...

leads us to believe this man was probably a metalworker of some kind...

and that was why he was in the mountains.

And the most likely thing he was looking for was metal.

[ Narrator] Mountains are a treasure trove...

[Anvil Clanging ]

Of the minerals and metals that people have always needed.

Flint for fire.

Copper and tin for Bronze Age swords.

Iron...

gold...

silver.

But metals are no more common in the mountains than anywhere else.

So why do Ötzi and millions like him...

have to trek into the mountains to get them?

Big history connects to geology.

Minerals are often miles deep...

buried under sediments that piled up over millions of years.

Early man has no way to dig that deep.

But mountains do.

Continents collide to create mountains that climb miles high.

Then erosion bulldozes the outer layers of earth...

and exposes the prize.

[Valle ] Mountains pretty much do excavation for us.

When you're walking along a cliff face and you see your rare mineral or coal...

or anything like that sticking out of it...

it's easy to grab a pickax and a shovel and start mining and follow the vein.

Try and do that in the middle of a flat plain.

You dig down. You may not even find anything.

[ Panting ]

[ Narrator] Bronze Age men like Ötzi...

will be among the first to die for these riches.

In modern times, mountains offer up another vital resource-

energy.

Obviously, the coal that comes out of the Appalachians...

helps drive the industrial revolution in North America.

Think of the role of that coal in driving the great machines, the great factories.

Without that coal, itself the product of mountain building...

we might not have had industrialization.

[ Narrator] But not all the riches raining down from mountains are set in stone.

Big history reveals how height and gravity work together...

to make mountains into water towers.

Mountains reach so far into the atmosphere that they create weather.

They force moist air passing over them to rise...

where it cools...

and its water vapor condenses and falls as rain.

Mountains are rainmakers.

All the wettest places on Earth...

are on the windward side of mountains.

In temperate zones, this moisture usually falls as snow.

[ Man ] In the growing season, that water is then slowly melted away...

where it feeds into the world's biggest river systems.

And so, very simply, without the role of mountains...

allowing the water to accumulate and then releasing it...

at a slow and steady rate in the summer...

we simply wouldn't have the major watersheds that we have in the world today.

[ Narrator] So if mountains are so vital...

what would the Earth be like without them?

There is a sign hidden in the place where mountains are born...

a place where few men have ever gone.

[ Narrator] Big history shows us how geology shapes our history...

how mountains act as giant bulldozers...

to raise up and carve out metals...

and as giant blenders that churn the atmosphere...

to water the planet.

But the mountains most essential to life on Earth-..

Are the ones we can't see.

Big history connects back...

to an unprecedented expedition in the mid-Atlantic.

[Tapping I

It's the age of the first transatlantic telegraph.

And a British ship surveys the ocean floor.

[ Markley] H.M.S. Challenger was looking for a good route...

to lay a cable across the Atlantic...

and they came across something quite unexpected...

a massive mountain range under the ocean...

the entire length of the Atlantic Ocean.

We call it now the Mid-Atlantic Ridge.

[ Narrator] This 10, 000-mile stretch of constant earthquakes...

volcanoes and spewing vents...

is not just a mountain range.

It's a mountain factory.

As the sea floor separates and builds these mid-ocean ridges...

continents are shoved apart...

creating mountains thousands of miles away.

[ Benjamin ] Here are the processes that drive plate tectonics.

These same mountain ranges are driving great parts of the crust of the Earth to move...

and to create eventually other mountain ranges.

[ Narrator] Without this factory constantly building new mountains...

our existing mountains would slowly erode away...

turning Earth into a nightmare planet.

If there were no mountains on Earth...

the entire planet would be radically different than what we know today.

Imagine no windbreaks...

so wind just continually speeds up.

Whirlwinds, gigantic tornadoes, cyclones.

It would be completely uninhabitable...

completely unlivable.

[ Narrator] Underwater...

the intense heat rising from the Earth's molten interior...

gushes out through black smokers...

creating a hellish soup of broiling chemicals...

that billions of years ago may have created life.

[ Benjamin ] Here's where early forms of bacteria appear...

feeding off the energy and heat that was coming out of these volcanic eruptions.

Here we think the first life on Earth appeared...

beside these great undersea mountain ranges.

[ Narrator] We've seen the power of mountains...

as barriers that separate us...

bulldozers that bring us riches...

sources of water...

and perhaps even life.

Mountains define the landscape...

carving the earth into a complex playing field...

with obstacles that dare us to challenge them.

They divide us, sustain us...

and shape who we are.

But the story of mountains is just the beginning.

There's a much bigger puzzle hidden in big history.

Each episode unlocks a clue.

Things like water...

meteors...

and the sun hold the key.

Watch them all and you'll see this grand mystery revealed.

The big history of time, of space.

The big history of us.