Original subtitles

[NBC chime]

NARRATOR: The story of life on Earth...

[roars]

...has been marked by a series

of catastrophic extinction events.

Natural disasters, which have threatened to wipe out

many of the creatures that call our planet home.

But after each brush with death,

life has come back even stronger.

[majestic music]

One such event occurred two and half million years ago,

in the Americas.

Up until then, North and South America had been separated

by ocean.

[trumpeting]

But then, the seabed rose up,

and a land bridge formed.

[snarling]

♪♪♪

For the first time,

animals and plants from these two completely different worlds

would face off.

[squawks]

Many were driven to extinction.

-[growling] -[screeching]

But for others, it was a whole new beginning.

-[trumpeting] -[screeching]

[growling]

[trumpeting]

[majestic music]

[low grunting]

It changed life in the Americas forever.

[theme music]

[wind gusts howl]

[reverent music]

NARRATOR: Long after the time of the dinosaurs,

and more than two million years

before modern humans walk the earth,

the world is becoming drier and cooler.

In Central America,

the climate shift is extreme.

A punishing drought has gripped these lands for six months.

♪♪♪

To survive here,

it takes a special kind of animal.

[snuffling]

Like these majestic Gomphotheres.

[low, rumbling grunts]

Descended from ancient elephant species

that originally migrated out of Africa,

these creatures have made North America their home.

[trumpeting]

Today, they are celebrating.

[trumpeting]

A little female calf, only hours old.

[trumpeting]

Her mom is the 40-year-old matriarch.

She is the leader of this herd.

[trumpeting]

[grunting]

She doesn‘t have the strength

to join the celebration.

♪♪♪

[trumpeting]

Exhausted after giving birth,

she looks for a place to be alone.

[screeching]

As matriarch, she is key

to the whole herd‘s survival,

so it is not surprising her behavior

is starting to make them anxious.

Something extremely rare has happened.

[high-pitched trumpeting]

[gentle music]

The matriarch has given birth to a twin.

♪♪♪

[trumpeting]

Brother and sister meet.

It is a moment of pure joy.

[high-pitched trumpeting]

The entire herd is elated with the arrival

of its newest members.

[herd trumpeting]

[tense music]

When night comes, the mood changes.

Despite an exhausting day,

it is the new mom who bravely stands guard

while the rest of the herd sleeps.

As an experienced matriarch,

one of her duties is to keep the others safe.

♪♪♪

And it‘s a good thing,

because tonight, there is danger,

lurking in the darkness.

[snarling growls]

Smilodon.

Ruthless sabretooth cats,

as big as jaguars.

♪♪♪

They’ve picked up the scent of the new calves.

♪♪♪

[tense music builds]

At three and a half tons,

these adult Gomphotheres are too big for Smilodon to take down.

[snarling]

But with a surprise attack...

they could separate one of the calves,

and go in for the kill.

[clattering]

[birds cawing]

[trumpeting]

[snarling]

Well, it‘s no longer a surprise.

[roars]

Changing tactics, they go straight for the herd.

[dramatic music]

-[trumpeting] -[snarling]

If they cause enough chaos,

one of the babies will be exposed.

[high-pitched trumpeting]

-[roaring] -[trumpeting]

Led by the matriarch, the adults hold the line...

for now.

But the sabretooths have got all night.

-[roaring] -[trumpeting]

It‘s rare for twin calves to both survive

their first year in this harsh land.

But can they even survive their first night?

[roaring]

[tense music]

NARRATOR: The moon sets over Central America,

two and a half million years ago.

♪♪♪

It is a land gripped by a severe drought.

[snarling]

During the night,

a herd of American elephants

have been targeted by sabretooth predators,

drawn by the smell of newborn twin calves.

[high-pitched trumpeting]

[trumpeting]

[snarling]

[gentle music]

NARRATOR: In the morning light,

the matriarch triumphantly reveals

all the members of her herd survived.

[gentle music]

Most importantly, her two babies.

♪♪♪

They didn‘t go unscathed.

Both the little male,

and his mother were injured.

But there‘s no time to rest.

The drought makes our matriarch‘s top priority

to find water for the herd.

[dramatic music]

She knows a place where her own mother

took her, decades ago.

It might seem dry, but if you know where to look,

there are underground springs.

[suspenseful music]

There’s barely a trickle.

[low grunting]

She is distressed.

Her home range has failed her,

and she has failed her herd.

She must find water.

[reverent music]

It is all down to the very land she is standing on.

Before now,

the continents of North and South America

were completely separate land masses.

♪♪♪

But continental drift has been pushing them

on a collision course over millions of years.

Now, they are almost touching.

♪♪♪

Ocean currents are rerouting,

and the climate in Central America

is getting steadily drier.

[wind gusts howl]

As the dry seasons get longer,

reliable water sources disappear,

and animals suffer.

These Gomphotheres can normally survive for days without water.

But with two calves to feed,

this new mother needs to find a solution, fast.

[high-pitched trumpeting]

Another mother in the herd has already

lost her calf to this drought.

[babies trumpeting]

Staying here, with no water,

would mean certain death for her two babies.

[trumpeting]

But then, our matriarch feels something

in the ground.

Through thick pads on her feet,

she can sense vibrations.

From experience, she knows what this is.

Distant thunderstorms.

[joyful music]

The promise of rain pushes her to take a huge risk.

[trumpeting]

[thud, echoes]

[low grunting]

[majestic music]

She decides to leave her ancestral lands,

and lead her herd south.

These American elephants can walk over 100 miles in a day,

but they are traveling into the unknown.

The lands to the south are even more inhospitable

than their home territory.

♪♪♪

Even the creatures they meet will be alien to them.

The gamble she‘s taking could be disastrous

for her new babies, and for the whole herd.

[high-pitched trumpeting]

[trumpeting]

[reverent music]

NARRATOR: The matriarch of a herd of Gomphotheres

has decided to migrate in search of water.

Desperate, she is leading her herd further south

than any American elephants have ever been.

And so far, it is only getting drier.

[suspenseful music]

When the matriarch‘s young son wanders away from the herd,

he encounters something he‘s never seen before.

-[grunting] -[trumpeting]

[braying]

An armored Glyptotherium.

Definitely not a creature from around here.

In fact, he‘s from another world...

the island continent of South America.

[trumpets]

[whimsical music]

Somehow, he‘s crossed into the north.

[grunting]

[braying]

He doesn‘t smell dangerous.

[trumpeting]

Maybe this odd-looking animal

could be a playmate.

[trumpeting]

[high-pitched trumpeting]

[screeching]

[low trumpeting]

The mother who lost her own baby

comes to the rescue.

[baby screeching]

[dramatic music]

[braying]

[low trumpeting]

It‘s nice to be part of a herd.

[trumpeting]

The little one is a bit bruised,

but his instincts were right.

The herd has nothing to fear from these strangers.

[whimsical music]

[braying]

Although, the Glyptotherium aren‘t used

to creatures powerful enough to turn them on their backs.

[braying]

For them, this new, dry world is proving tough.

[dramatic music]

The desperate herd is also struggling.

They haven‘t drunk now for days.

But our matriarch is sticking with her plan,

so she steps up the pace.

[bird screeching]

They persevere for days.

♪♪♪

Perhaps this was a mistake.

For the new calves, the pace is punishing,

but something even worse is happening.

[low grunting]

Their mother‘s wound is badly infected,

and she is growing weaker with every step.

♪♪♪

She made the decision to take them south,

but now, exhaustion and her infected wound

are making it impossible for this matriarch to lead.

She can barely walk.

[solemn music]

She knows her time has come.

[herd trumpeting]

Her herd try to help their leader back to her feet.

♪♪♪

But she’s reached the end of her journey.

[trumpeting]

And her death could mean the death of her twins.

[herd trumpeting]

♪♪♪

NARRATOR: The next morning, the herd has no leader.

But then, something remarkable happens.

The mother who lost her own calf still has milk.

[poignant music]

[grunting]

[high-pitched trumpeting]

She is now the new matriarch.

And following in the footsteps of her predecessor,

she starts to lead the herd south again.

♪♪♪

Finally, rolling clouds on the horizon.

It looks like our old matriarch was right.

Her legacy will be the herd‘s survival.

♪♪♪

There‘s the smell of water in the air.

But it’s not like any water they’ve smelled before.

[majestic music]

It’s the ocean.

This is where the Atlantic meets the Pacific.

For the last 50 million years,

this would have been the end of their journey.

Now, as the American continents collide,

there is the promise of a whole new land on the horizon.

[waves splashing]

But the journey there will test this herd to its limits.

[dramatic music]

NARRATOR: After an epic migration

the new matriarch has brought her herd

to the southern most tip of North America.

Before them lies South America

a continent that has been isolated

for the last 50 million years.

In between stretches miles of shallow sea,

crisscrossed with sand banks

and deep channels in all directions,

Here, they face an ocean for the first time.

[Gomphotheres grunting]

The new environment makes the herd nervous.

For the innocent calves, it’s a fun day at the beach.

[Gomphotheres squeaking and grunting]

Their new leader can tell the water isn’t drinkable.

[Gomphothere growling]

Then, she picks up the unmistakable scent

of lush vegetation floating on a southerly breeze.

Ahead, lies the island continent of South America.

Except, it’s no longer an island.

2.5 million years ago,

continental drift is pushing it so close to North America

that a series of new islands are forming a strip of land.

To find fresh water,

all the matriarch has to do is follow her nose.

So, she continues the journey south.

But she is unaware the land bridge they are on

only exists at low tide.

[dramatic music]

Now, the tide is coming in.

The herd is trapped, surrounded by water.

[Gomphotheres groaning]

Gomphotheres are naturally good swimmers,

but fighting tides and unpredictable currents

is much harder than crossing a river.

They all struggle to stay together.

The little female calf is pulled by the tide.

[calf crying]

The new matriarch can do nothing to help her.

[Gomphotheres crying]

[Gomphotheres groaning]

NARRATOR: Exhausted and disoriented,

they find themselves on a new continent:

South America.

But at what cost?

[Gomphothere trumpeting]

A miracle arrives on the high tide.

It‘s his sister!

In her young life she‘s overcome so much already.,

And now she‘s even managed to survive the rough sea.

[Gomphotheres trumpeting]

Finally, a new world.

This part of South America is less affected by the drought,

with plenty of fresh water and dense vegetation.

Yet, for the herd and their matriarch,

nothing is familiar here.

New scents hang in the air.

There are strange varieties of fruits.

Even the birdsongs are new to their ears.

Here, they are the aliens

and they have no idea who they‘ll encounter.

[animal growling]

This ancient land has been isolated for so long,

[bird squawking]

it has had plenty of time

to evolve its own terrifying predators.

NARRATOR: The herd of gomphotheres

have made the impossible journey across the tidal isthmus

that connects North and South America.

Everything is new to them.

These are the sights and sounds

of a completely unfamiliar world.

[birds trilling]

[animals growling]

Almost immediately, a strange call echoes around them.

It comes from an enormous creature.

Luckily, he‘s only interested in the fruit.

A Giant sloth.

One of the wonders of South America

two and a half million years ago.

Even bigger than the gomphotheres,

they evolved during the continent‘s

50 million years of isolation.

The matriarch leads them deeper into this new world.

Her role is to protect the herd

but she has no idea who‘ll they‘ll meet next.

For now, there is no sign of predators.

A herd of toxodons.

Thousands of these one-ton beasts graze these plains.

And with so much vegetation around,

they have no problem sharing.

So far, South America seems like paradise.

[bird trilling]

Suddenly, a piercing call sends the toxodons into a panic.

[birds squawking]

South America‘s Terror Bird.

These seven-foot super-predators

can run at over 25 miles an hour.

They start to flush out the weak.

[Gomphothere trumpeting]

Until, they spot unexpected visitors.

[bird squawking]

[Gomphothere groaning]

Our matriarch knows it‘s time for her to step up.

[Gomphothere trumpeting]

The birds assess these new creatures.

They have never seen an elephant of any kind before.

But, in this land, everything is prey to them.

[Gomphothere grunting]

[bird squawking]

They select their target.

[Gomphothere trumpeting]

[bird squawking]

[Gomphothere trumpeting louder]

[bird squawking]

[bird crying]

[bones snapping]

[bird squawking]

Not today.

Our new matriarch secured her place as leader of the herd.

And stamped her mark on this new continent.

They‘ve finally made it.

In a land where no predators can threaten the adults,

the gomphotheres’ future looks bright.

But this is only the beginning.

More species are moving south

and it is not just the herbivores

discovering this new continent.

Predators from the north have also made the crossing

and are about to change this land forever.

[growling]

NARRATOR: Over the course of hundreds

of thousands of years,

the movement of the continents

continue to push North and South America closer together.

A new permanent land bridge grows

at what will one day be Panama.

Thousands of species of plant and animal

move both north and south.

It is one of the largest rapid mixings of plant

and animal species in Earth‘s history.

And as these vastly different species collide,

they forge a new future for the Americas.

One million years later,

life in South America has gone through a seismic shift.

During the great Clash of Species,

many went extinct.

But out of the melting pot, new ones have evolved.

Now, at the top of the food chain,

sits the giant South American sabretooth.

Four times the weight of the sabretooths

that crossed over from the North,

this is one of the largest cats that ever lived.

The gomphotheres are also thriving.

Tens of thousands now roam these grassy plains.

And a large herd of gomphotheres is perfect

for a hungry sabretooth.

[sabretooth growling]

[Gomphothere trumpeting]

Unlike his Northern cousins,

this predator hunts alone

and is easily large enough to take down a gomphothere calf.

[Gomphothere trumpeting]

[frantic music]

[Gomphothere trumpeting]

[sabretooth growling]

[gomphothere grunting]

A bull gomphothere.

[gomphothere growling]

Pumped full of testosterone,

the little guy is part of a herd.

[animals growling]

And even apex predators know when to run from a fight.

[gomphothere trumpeting]

[gomphothere trumpeting]

From their origins in Africa,

the elephant family have now claimed a fifth continent

as their home.

A million years after the Americas unite,

there’s been an explosion in biodiversity.

The continent will go on

to support 32 different types of mammals

that weigh over a ton.

It‘s the greatest diversity of mega-mammals

in Earth‘s history.

The impact of the joining of the Americas

can still be seen today.

NARRATOR: But more recently, it is humans that have kickstarted

an even bigger clash of species.

After some 110 million years of separation,

the arrival of Columbus marked a new continental collision.

Living things from Africa and Eurasia

met with those of the Americas.

Everything from livestock and insects

to vegetables and viruses

moved both ways across the Atlantic.

The consequences of our re-connecting the continents

have been profound:

Some species’ populations are exploding,

while others’ go extinct.

Humans have impacted the environment

in countless ways,

but the way our activities are now mixing species

on a global scale

is perhaps our biggest legacy

to the future shape of life on Earth.