[ominous music playing]
[Morgan Freeman] Millions of years before the age of dinosaurs...
our planet was ruled by equally magnificent beasts.
[low grunting]
Two great dynasties had emerged
and were vying for domination.
[wailing]
This is the story of the battle to conquer land...
[growling]
...and how it changed everything for life on our planet.
[roaring]
[rousing music playing]
[snarling]
[trilling]
[screeching]
[rousing music continues]
[growling]
[wind howling]
[rumbling]
[rousing music intensifies]
[music fades]
[somber music playing]
For most of our planet's history,
land has been inhospitable to life.
A bleak and desolate realm...
more like the surface of the moon...
than like Earth today.
It's hard to imagine
how anything could ever make this hostile place its home.
But from beneath the waves,
where life had thrived for more than a billion years,
one curious life-form was among the first to rise to the challenge.
Lichen may not look remarkable,
but they are in fact completely unique.
A pioneering partnership.
[intriguing music playing]
Neither plant nor animal,
lichen are a strange combination of fungi and algae...
that only together had what it took
to overcome the extreme hostility of barren Earth.
[ethereal music playing]
But they were more than just pioneering.
They were groundbreaking.
As they spread...
[stirring music playing]
...their tiny filaments helped to break down rock
and produce the first ever soil...
paving the way for plants to take over.
Micro plants, like moss, were first to appear.
With leaves only one cell thick,
they couldn't grow upwards,
but could spread out.
Reproducing faster than lichen,
they soon carpeted the land,
which they ruled undisturbed for the next 40 million years.
[music intensifies]
[music fades]
But a green revolution was coming...
that would change the landscape forever.
Key was the evolution of a new compound,
lignin.
Lignin strengthened the plants' cell walls...
allowing them to grow bigger and stronger than ever before.
No longer confined to carpeting the land,
plants began to battle for the real estate above,
fighting for access to light.
[dramatic music playing]
[music fades]
Eventually, some plants grew so tall,
they towered above the world around them.
[majestic music playing]
Today's redwoods are nature's skyscrapers.
Reaching heights of more than a hundred meters,
they are the tallest living things to have ever existed.
But redwoods are just one of more than 400,000 species of plant,
the most visible signs of life on our planet.
[music fades]
Back in Earth's distant past, the arrival of plants
created new habitats for the next invaders from the sea.
[unsettling music playing]
The first animals to ever set foot on land were the arthropods.
Relatives of the trilobites,
their hard exoskeletons had served as useful armor underwater.
On land, that armor supported them
and prevented them from drying out.
They could also breathe through this tough exterior.
And with oxygen levels 60% higher than they are today,
some grew to be giants.
Arthropleura, the largest millipede to ever walk the Earth.
At over two and a half meters long and a half meter wide,
he has no natural enemies...
[peaceful music playing]
...so can focus all his energy on finding a mate.
But for Arthropleura, the pursuit of the perfect partner is
not straightforward.
- [soft thud] - [music stops]
For he's virtually blind...
[music resumes]
...and his world extends only as far as he can sense.
The fern forest is vast,
and a female could be anywhere.
But his search isn't as hopeless as it might seem.
Females ready to mate leave scent trails for males to follow.
A lifeline in the darkness.
[whooshing]
[pensive music playing]
And yet, sensing where she once was is not the same
as sensing where she is.
[whimsical music playing]
[peaceful music playing]
Finally, his chance to charm can begin.
[chirping]
By rubbing together parts of his shell, he creates his own unique love song.
- [music stops] - [chirping continues]
[peaceful music continues]
[soft chirping]
[music swells]
Mating on land can be an awkward affair.
Success requires the perfect alignment.
So it's important at this critical stage
not to put a foot wrong.
[music intensifies]
[music ends]
[birds tweeting]
345 million years later,
and in today's forests,
the arthropod art of seduction has come a long way.
Especially for some of the less armored members of the group.
[brooding music playing]
Unlike the ancient Arthropleura,
male jumping spiders have superb vision
and are no larger than a grain of rice.
[music becomes playful]
But what they lack in stature...
they make up for in style.
Each species has its own signature dance move
to attract female attention.
The peacock.
The side shuffle.
The disco dancer.
And the feather shake.
While the males evolved colorful costumes
and intricate dance moves...
females developed impeccable taste.
His side shuffle has caught her attention.
But has he got the moves she's looking for?
Only the very best will do.
[lively jazz music playing]
Waving her abdomen signals she's not impressed.
[dramatic music playing]
[music fades]
He needs to be careful,
for fussy females sometimes eat their suitors.
[tense music playing]
Still...
[lively jazz music resumes]
...it's worth one more try.
[music slows, fades]
Clearly, he's not getting the message.
[tense music playing]
He may be unlucky in love,
but his arthropod dynasty has had better luck.
They now make up over 80% of all animal species.
The secret to arthropod success
lies in their simple segmented body plan...
[sinister music playing]
...which has evolved in countless different directions.
[music intensifies]
Some have ears in their legs.
Others, eyes on stalks.
And armor plating for battle.
Variation after variation,
arthropods are evolution run wild.
Including the greatest runner of them all,
the tiger beetle.
Its design has been fine-tuned over millions of years.
The latest model is built for speed.
For its size, it is one of the fastest sprinters on Earth.
If scaled up to human proportions,
it would run
at over 1,000 kilometers per hour.
But there is one drawback to life in the fast lane.
His brain can't keep up.
He must frequently stop to get his bearings
while hunting down his next victim.
[tense music playing]
But his frantic search for food can lead him into dangerous territory...
because sometimes the hunter
can also be
the hunted.
[ominous music playing]
Fast and furious is not this trapdoor spider's style.
She prefers to wait for prey to come to her.
[suspenseful music playing]
[music intensifies]
[dramatic music playing]
[music fades]
In the battle of the arthropods,
flight would often make the difference between life and death.
[intriguing music playing]
[buzzing]
More than 300 million years ago,
one group of arthropods
were the first creatures to take to the skies.
[music intensifies]
And the evolution of wings
would eventually launch them to global success.
The insects.
[rousing music playing]
Today, for every human on the planet,
there are more than a billion insects.
They are the most abundant group of animals on Earth.
[music fades]
[creatures chirping, insect buzzing]
Despite their current success,
the ultimate flying insects first appeared back in the ancient swamps.
Dragonflies.
Their flight is as close to perfect as it gets.
Four flexible wings,
independently controlled,
give them unparalleled mobility.
They can fly in any direction,
pull off the tightest turns...
[intriguing music playing]
and accelerate faster than a fighter jet.
A winning design that has remained almost the same
for hundreds of millions of years.
[music fades]
And yet, living in the same prehistoric swamps,
another group of animals were undergoing their own radical change.
Beneath the surface,
vertebrates had continued to evolve...
and a new type of fish was thriving,
the lobe-finned fish.
Some grew to be monstrous predators.
[tense music playing]
In this fish-eat-fish world,
it pays to be big.
[music intensifies]
[music ends]
For the smaller ones, there's refuge in the shallows...
where their unique lobed fins are a distinct advantage.
Muscular and highly versatile,
they are different to those of other fish.
Not only do they help them swim...
but they're strong enough to support their body weight...
and help them crawl out of the water.
But these fish also have another game-changing adaptation...
the ability...
- [wheezes] - ...to breathe air.
Not through gills but through primitive lungs.
Together, these evolutionary advances
allowed vertebrates to leave the water and explore the land.
The race was on to colonize this new world.
But it was already too late
for these lobe-finned fish.
Others had made this transition before them.
[grunting]
[dramatic music playing]
Like the three-meter-long Anthracosaurus...
[low growling]
...that had already found its feet.
[grunts]
The evolution from fin to limb took millions of years.
[stirring music playing]
But once completed, life on land
would never be the same again.
The age of amphibians
had begun.
[ethereal music playing]
Today, there are more than 8,000 species of amphibian.
A peculiar but diverse group...
[long croak]
...of newts,
frogs,
salamanders,
and toads.
[music intensifies]
Not quite the giants they once were,
but still successful hunters...
[music fades]
...with their own killer style.
[birds tweeting]
Hundreds of millions of years after Anthracosaurus,
swamplands remain a stronghold for amphibians.
[tranquil music playing]
Here in Europe's Danube delta,
marsh frogs live in their thousands
and have become expert insect hunters...
with a particular taste
for dragonflies.
[tense music playing]
Thanks to their wraparound vision,
catching one isn't easy.
But marsh frogs have evolved some quirky adaptations of their own.
Webbed feet help them get airborne.
And a projectile tongue gives them extraordinary reach.
Even so, dragonflies in flight
can be just too hard to catch.
Waiting for the aerial acrobats to land might make things easier.
Time to take a different approach.
A female laying eggs in the water.
Half-submerged,
she should be an easier target.
[dramatic music playing]
The dragonflies are just too fast.
[suspenseful music playing]
And they can barrel-roll.
Missed again.
But frogs are nothing if not persistent.
[suspenseful music playing]
[music ends]
Despite the low hit rate,
amphibians have survived for over 350 million years.
And yet, they never conquered every environment the planet had to offer...
because there's something all amphibians need to raise their young.
Water.
This is the strawberry dart frog of Costa Rica.
[croaking]
Her tadpoles are in mortal danger.
Their tiny puddle, almost dry.
[croaking]
Their only means of escape
is on their mother's back.
The hard part is finding water.
Luckily...
[croaking]
...she knows exactly where to go.
[croaking]
Twenty meters above her,
a bromeliad collects rainwater.
The perfect pool for her precious tadpole.
But first, she must get there...
one hop at a time.
[invigorating music playing]
Barely the size of a human thumbnail,
this is her own personal Everest.
[ethereal vocalizing]
[croaking]
[music fades]
Safe at last.
[croaking]
No matter what great heights amphibians reached in their conquest of land...
they never escaped their tie to water...
a tie that would be their undoing when conditions on Earth...
radically changed.
[ominous music playing]
During the period known as the Carboniferous,
Earth's great land masses merged,
and the supercontinent of Pangaea was born.
As the land dried,
the vast swamps began to disappear.
Lacking water, most amphibians struggled.
[music fades]
But not all.
One evolved a revolutionary adaptation that enabled it to thrive.
Its egg developed a protective shell
that held the embryo in its own private pool of fluid.
Inside, the young could develop safely without drying out.
[serene music playing]
The tie to water was finally broken by the evolution
of this amniotic egg.
Known as the amniotes,
these creatures could colonize the drier land
in a way that amphibians could not.
[music intensifies]
And from this one common ancestor,
all mammals, reptiles, birds,
and dinosaurs would descend.
[sinister music playing]
[music fades]
Sixty million years after the evolution of the amniotic egg,
amniotes have spread across Pangaea...
[majestic music playing]
...producing two new dynasties and the start of an endless rivalry.
These sleeping armored beasts are a primitive type of reptile.
Scutosaurus, among the largest animals on land.
[distant bellowing]
[grunting]
Weighing over a ton,
they are the first giant plant-eaters to roam the planet.
Amniotic eggs allowed them to flourish in the drier conditions
and go where others could not.
[low growling]
But Pangaea didn't just belong to them.
Another new bloodline had emerged.
The ancestors of the mammals.
[mewls]
While a Lystrosaurus is no match for a Scutosaur...
- [growling] - [mewls]
...he has cousins here who are.
[ominous music playing]
[snarling]
A gorgonopsid.
A more impressive forerunner to the mammals.
At over three meters long and 300 kilos,
she rivals any big cat alive today.
[grunting]
With her powerful sense of smell,
tracking her prey is easy.
Getting past their heavy armor
will be her greatest challenge.
[grunting, wailing]
But she has a secret weapon.
[snarling]
Saber-like teeth.
Even so,
she'll need stealth to get close.
[grunting]
- [grunting] - [wind whistling]
[grunting]
[tense music playing]
She must choose her moment...
and her target
carefully.
[grunting]
Slowly
and silently...
does it.
[tense music continues]
[growling]
- [grunting] - [growls]
- [wailing]
[roars]
[roars, snarling]
[roars]
- [roaring] - [grunting]
[dramatic music playing]
- [music fades] - [wailing]
The rivalry between mammals and reptiles
has been a feature of life on Earth for hundreds of millions of years.
But their early rise was not to last,
because in the far north of Pangaea,
something catastrophic was happening.
[rumbling]
Lying dormant for years on end,
the colossal forces at work beneath Earth's surface
are easily forgotten.
But the molten underworld
is always stirring,
always probing for weakness.
[ominous ambient music playing]
[wind whistling]
Beneath Pangaea's crust,
a plume of superheated magma
was working its way to the surface.
Once these Permian eruptions started...
there was no stopping them.
[dramatic music playing]
What made them unique was their monumental scale.
[dramatic music continues]
They were among the largest,
most violent eruptions that life has ever witnessed.
And they raged for 100,000 years.
The devastation was unprecedented.
An area half the size of the United States
lost to lava.
[poignant music playing]
Millions of square kilometers,
once so full of life,
obliterated by the Earth itself.
[music fades]
And that was just the beginning.
The eruptions released something far more dangerous than lava.
A toxic concoction of noxious gases.
[hissing]
[dramatic music playing]
When these gases combined with water...
a potent cocktail of acid rain poured down.
Water, the giver of life,
was now its destroyer.
The toxic rain poisoned the ground...
killing off the plants.
Without their roots to bind the soil together...
entire ecosystems were washed away.
[dramatic music playing]
[rumbling]
[music fades]
And yet, there was something even more destructive in the air.
A silent killer.
Carbon dioxide.
The volcanoes released six times more CO2
than is in our atmosphere today...
triggering ten degrees of global warming...
[rumbling]
...and all the climate devastation
that comes with it.
[ominous music playing]
[thunder rumbles]
Hothouse Earth raged as the forces of nature ran wild.
[music intensifies]
There was nowhere to hide from the chaos.
And the oceans were worst affected.
As they warmed and acidified,
oxygen levels plummeted...
turning the seas, where life first took hold,
into a desolate graveyard.
This was the planet's third,
and most devastating, mass extinction.
[melancholy music playing]
Ninety percent of all species
lost forever.
Entire branches torn off the evolutionary tree.
But in the loss of many,
endured the few.
[rustling]
[breathing heavily]
All that remained of a bygone age.
Never had their survival been so important.
The future of all life
now hung by a thread.
[ethereal music playing]
[music continues]