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The story
of life on Earth...
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...has been marked by a series
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of catastrophic
extinction events.
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Natural disasters which
have threatened to wipe out
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many of the creatures
that call our planet home.
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But with each brush with death,
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life has come back
even stronger.
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One of the planet's
first great extinctions
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took place
444 million years ago.
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In the shallow seas, life had
established an exotic foothold.
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But then, suddenly,
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the climate cooled,
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sea levels plummeted,
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and 85% of all life died out.
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Eventually,
the seas rose again...
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...the survivors
rebuilt their world...
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...and some discovered
a whole new one.
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This is Earth,
444 million years ago.
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This is a world that will not
see the first dinosaur
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for another 200 million years.
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The continents are mostly
in the southern hemisphere,
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and all of them
are barren wildernesses,
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devoid of all
but microscopic life.
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No roars, no barking,
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not even a chirp sounds
across the empty landscape.
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Carbon dioxide is a staggering
14 times higher
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in the atmosphere
than it is today,
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and the days
are three hours shorter.
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It is a truly alien world,
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and yet, there is a place
where life is thriving.
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Hidden in the warm,
shallow sea,
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lives a magical world,
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Thousands of miles
of spectacular reefs.
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These dazzling corals
are home to newly-evolved
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complex creatures like starfish,
and horseshoe crabs.
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Bug-eyed trilobites
swim upside down,
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sifting the water for food.
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Yet one animal,
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whose descendants
will one day fill the seas,
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and a forerunner of every
bird, mammal,
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and reptile on Earth,
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is surprisingly hard to find.
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This guy, a fish.
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These are Sacabambaspis,
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one of the first animals
on Earth to evolve a backbone.
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These two young males
are here for lunch.
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The reefs are full
of things to eat,
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but most creatures here
have hard shells,
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and all these young fellas
can do is suck.
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Their search for food takes them
into a field of sea lilies.
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These graceful lilies
aren't actually plants,
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they're animals,
filter feeders,
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that open their arms to catch
plankton in the water.
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Finally, one of our
little guys finds a snack.
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He doesn't have jaws or teeth,
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so he has to get his head
right inside.
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And now, he's stuck.
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It is just not his day.
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His awkward jam
has caught the eye
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of some squid-like predators.
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They don't know what
this strange object is,
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just that it's worth
fighting over.
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Our hungry little Sacabambaspis
makes a break for it,
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and finds a place to hide.
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This cave should keep him safe.
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What he doesn't know
is that he has company.
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Hiding in the shadows
is the reef's top predator.
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444 million years ago,
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the land is empty,
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00:07:41,939 --> 00:07:46,466
but these shallow seas
are filled with coral reefs.
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It is the only place
on the whole planet
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that teems with complex life.
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Our little fish has taken
refuge in a cave,
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only to discover he's not alone.
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A giant sea scorpion.
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This reef's apex predator.
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But this scorpion
isn't hunting in this cave.
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She's here to molt.
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She can only get bigger
by shedding
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one armored skin
and growing another,
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but this makes her soft
and vulnerable
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for a few hours.
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Sometimes, even apex predators
have to hide.
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Looks like it's this guy's
lucky day.
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These endless
shallow seas have proved
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the perfect nursery
for early life,
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but something is happening
on land
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that is about to spoil
this prehistoric paradise.
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Across the empty landscapes,
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the absence of vegetation
means wind and water
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tear at its surface.
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Massive dust storms,
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and rivers laden with sediment
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are dumping vast quantities
of materials into the sea.
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This onslaught of minerals
is feeding marine algae
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on an explosive scale,
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generating enormous blooms
across the oceans.
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These algae blooms, in turn,
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absorb carbon dioxide
from the atmosphere,
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00:10:03,124 --> 00:10:05,300
and the levels
of this greenhouse gas
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are now plummeting.
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Earth has reached
a tipping point.
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It's cooling down fast.
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Even the warmest seas
will soon feel the change.
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Back at the reef, our little guy
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has returned
to the sea lily field.
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This time he is here
looking for something else.
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His bright red tail is a sign
he's ready to mate,
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and he's searching for
the right spot to build a nest,
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so he can attract a female.
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At last, a clearing
amongst the lilies.
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Except all these other guys
had the same idea.
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The competition is already
fighting over the best spots.
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A female.
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Her silvery stomach signaling
she's ready to lay her eggs.
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So now, it's showtime.
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The males start to dance.
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They're all trying to woo her,
to lay her eggs in their nest.
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She's chosen.
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Our little guy
is late to the party.
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To stand a chance,
he needs to find his own space.
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At last, an empty spot.
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Our little fish can only watch
as a larger male settles in.
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A predatory bristle worm.
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But it's bitten off
more than it can chew.
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No wonder that bit of sand
wasn't taken.
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These coastlines might
look tranquil.
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But twice a day,
beneath the water,
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it's a different story.
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The water is so shallow
that when the tides change,
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they produce massive
rip currents.
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The nesting males hunker down,
protected by the sea lilies.
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These early fish
are not strong swimmers.
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So they stick close
to the seafloor.
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The giant sea scorpion.
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Now that she's finished
her molting,
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she's bigger and hungrier
than ever.
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But she's after a bigger meal.
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The bristle worm.
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But in the chaos,
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our hapless little fish
is thrown up into the riptide.
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The current up here
is too strong.
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It drags him away over the reef.
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Soon, he is swept out to sea.
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By the time the tide
releases him,
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he is over a mile
from the reef.
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Exhausted and alone, it looks
like his luck has run out.
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Even worse, here be monsters.
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00:15:35,760 --> 00:15:37,501
For millions of years,
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00:15:37,719 --> 00:15:40,678
Earth has had high levels
of carbon dioxide,
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00:15:40,765 --> 00:15:44,639
which have heated the
atmosphere, and warmed the seas.
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These shallow waters
have been perfect
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for complex life to evolve.
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But now, they are cooling fast.
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This crisis has not reached
our young fish yet,
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but he is still in trouble.
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He has been dragged
off the reef by strong tides.
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Now, he is lost
in the open ocean,
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a long, long way from home.
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The waters here
are an unfamiliar deep green.
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He's on the edge
of a vast algae bloom,
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one of many that are drawing
carbon dioxide
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out of the atmosphere,
and cooling the planet.
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The consequences of this
climate shift are extreme.
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At this time,
most of the world's land masses
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sit over the South Pole,
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and as temperatures plummet,
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a giant ice cap is formed.
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All this ice is reflecting
the sunlight,
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making the planet
cool even faster.
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Even for the warmer seas
further north, change is coming.
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By sunset, our little fish
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still hasn't found his way
back to the reef.
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He will not last much longer.
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Then, in the middle of nowhere,
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he discovers something
he can rest on,
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and there's food on it.
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Things are looking up.
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Clustered with hundreds
of clam-like Brachiopods,
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it looks just like
part of a reef.
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A giant orthocone.
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At 30 feet long,
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this is the largest creature
on the planet,
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the ocean's top predator.
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It has 10 long tentacles that
feed a powerful beak-like mouth.
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Fortunately, our fish is too
small to be in any danger.
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Sometimes, it pays to be tiny.
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Orthocones are normally
solitary,
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but now is a time of gathering.
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Tonight, there is a supermoon.
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This long ago in prehistory,
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the moon is closer to the Earth,
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and larger in the sky.
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It has a huge influence on the
rhythms of life in the ocean.
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On this special night,
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the moon signals the start
of one of the sea's weirdest
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and most spectacular events,
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a mass mating.
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Our lost fish decides to take
a chance, and hitches a ride.
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Luck is with him again.
201
00:20:16,040 --> 00:20:19,740
The orthocones are heading
into shallower waters to mate.
202
00:20:23,961 --> 00:20:27,574
They're taking our little
adventurer back to the reef.
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00:20:34,929 --> 00:20:36,844
Under the light
of the supermoon,
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the reef is putting on
its biggest annual spectacle,
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as most of the animals
prepare to mate.
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00:20:46,854 --> 00:20:50,249
But is it all too late
for the little fish?
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00:21:00,563 --> 00:21:05,438
444 million years
before modern humans evolve,
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00:21:05,655 --> 00:21:09,529
most creatures on Earth
do not live by the seasons.
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00:21:12,401 --> 00:21:15,578
Instead, it is the moon
and tides
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that have the most profound
effect on the rhythms of life.
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00:21:24,587 --> 00:21:26,850
Tonight, there is a supermoon,
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00:21:27,808 --> 00:21:32,073
and it is a time of mating
for all creatures.
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00:21:41,604 --> 00:21:43,214
All along the reef,
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00:21:43,389 --> 00:21:47,958
every animal triggers a glowing
trail of phosphorescence
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00:21:48,176 --> 00:21:50,744
as their motion disturbs
algae in the water.
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00:22:02,016 --> 00:22:06,281
Our lucky little Sacabambaspis
is right back where he started.
217
00:22:07,630 --> 00:22:09,850
There's no place like home.
218
00:22:16,596 --> 00:22:18,162
It's mating time for many.
219
00:22:21,557 --> 00:22:24,212
The corals and sea lilies
are spawning.
220
00:22:39,662 --> 00:22:42,535
Generating clouds
of eggs and sperm
221
00:22:42,665 --> 00:22:44,841
that cloak the entire reef.
222
00:22:58,377 --> 00:23:01,554
Our eager youngster
heads back to his mating site.
223
00:23:04,339 --> 00:23:06,080
It looks like he's too late.
224
00:23:08,474 --> 00:23:12,565
But after all he's been through,
he isn't giving up yet.
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00:23:14,001 --> 00:23:16,699
He gets to work making a nest.
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00:23:22,575 --> 00:23:24,141
Just beyond the reef,
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00:23:24,359 --> 00:23:27,362
hundreds of orthocones
have now gathered.
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00:23:29,669 --> 00:23:32,498
Normally, these giants would
see another of their kind
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00:23:32,715 --> 00:23:34,935
as a threat, and attack.
230
00:23:36,589 --> 00:23:37,938
But not tonight.
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00:23:38,939 --> 00:23:41,507
The males must woo a mate,
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00:23:41,637 --> 00:23:44,814
and they do this
with a spectacular light show.
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He lights up with luminescent
patches on his skin.
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00:23:54,476 --> 00:23:57,827
Then he spreads
his tentacles wide,
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and begins a gentle,
mesmerizing dance.
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She accepts.
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Mating is brief.
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He doesn't want
to push his luck.
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00:24:56,103 --> 00:24:59,933
Our plucky Sacabambaspis
seems to have missed out.
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00:25:02,936 --> 00:25:06,026
Then, a solitary female appears.
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00:25:07,288 --> 00:25:11,205
This is his moment,
his last chance to dance.
242
00:25:37,057 --> 00:25:39,581
With no other challengers
to distract her,
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00:25:39,799 --> 00:25:41,583
she lays her eggs.
244
00:25:41,757 --> 00:25:45,413
And then our young male
fertilizes them.
245
00:25:47,197 --> 00:25:48,416
Mission accomplished.
246
00:25:55,641 --> 00:25:57,251
All across the reef,
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00:25:57,381 --> 00:26:00,733
millions of animals have begun
their next generation.
248
00:26:02,561 --> 00:26:05,607
But daybreak reveals
a sinister arrival.
249
00:26:07,870 --> 00:26:10,438
A warning from the frozen south.
250
00:26:13,615 --> 00:26:17,706
An iceberg has drifted all the
way up from the polar ice cap.
251
00:26:20,143 --> 00:26:25,105
Life on this reef
is about to change forever.
252
00:26:29,239 --> 00:26:32,286
As temperatures
drop across the planet,
253
00:26:32,503 --> 00:26:35,071
the oceans are cooling
down fast,
254
00:26:35,289 --> 00:26:37,987
and a huge ice cap is growing
over the south pole.
255
00:26:40,207 --> 00:26:42,122
Icebergs are breaking off,
256
00:26:42,252 --> 00:26:45,473
and one has made it
all the way to the tropics.
257
00:26:49,172 --> 00:26:52,088
Life here is living
on borrowed time.
258
00:26:56,179 --> 00:26:59,618
A female orthocone is looking
for somewhere to lay her eggs.
259
00:27:14,371 --> 00:27:16,504
She's not used
to these shallow waters,
260
00:27:17,070 --> 00:27:19,725
and is a little unsteady
on her tentacles.
261
00:27:24,991 --> 00:27:28,124
She's also being watched.
262
00:27:41,050 --> 00:27:43,879
A predatory sea scorpion
has picked up the scent
263
00:27:43,966 --> 00:27:45,315
of her new eggs.
264
00:27:53,193 --> 00:27:54,934
They'd make a tasty meal.
265
00:28:06,815 --> 00:28:08,121
But this...
266
00:28:09,557 --> 00:28:12,125
is the wrong mother
to mess with.
267
00:28:16,085 --> 00:28:19,001
Orthocones do not
abandon their eggs.
268
00:28:22,439 --> 00:28:24,877
Standing guard,
she will not eat
269
00:28:25,051 --> 00:28:28,315
or leave this spot
for six months.
270
00:28:29,751 --> 00:28:32,667
Which means,
by the time they hatch,
271
00:28:33,276 --> 00:28:34,800
she will have died.
272
00:28:40,240 --> 00:28:42,721
A mother's ultimate sacrifice.
273
00:28:50,380 --> 00:28:51,773
Back in the clearing,
274
00:28:51,947 --> 00:28:54,950
the Sacabambaspis adults
have all moved on.
275
00:28:58,824 --> 00:29:00,477
But under the sand,
276
00:29:01,130 --> 00:29:04,177
lie their abandoned,
translucent eggs.
277
00:29:14,274 --> 00:29:15,884
As the days pass,
278
00:29:16,102 --> 00:29:19,279
the iceberg that broke off
thousands of miles away
279
00:29:19,453 --> 00:29:21,760
floats ever closer to the reef.
280
00:29:23,979 --> 00:29:28,288
And the freezing cold fresh
water cascading down its sides
281
00:29:28,505 --> 00:29:30,594
pours directly
into the shallows.
282
00:29:36,339 --> 00:29:39,473
For these creatures
used to warm saltwater,
283
00:29:40,387 --> 00:29:41,910
it means death.
284
00:29:45,305 --> 00:29:47,916
Those that can move
try to escape,
285
00:29:48,090 --> 00:29:49,918
like these trilobites.
286
00:29:57,447 --> 00:30:01,974
Eventually, the cold water hits
the Sacabambaspis nesting site.
287
00:30:06,195 --> 00:30:09,024
They hatch at the worst moment.
288
00:30:09,895 --> 00:30:12,811
But at least these newborns
are mobile.
289
00:30:24,953 --> 00:30:28,478
The damage caused by this
iceberg is only local.
290
00:30:29,610 --> 00:30:33,179
The bigger threat is that
the entire planet is cooling.
291
00:30:36,399 --> 00:30:39,446
As the polar ice cap
in the south grows,
292
00:30:41,361 --> 00:30:43,798
it captures water as ice.
293
00:30:46,453 --> 00:30:50,587
Eventually, reaching eight times
the size of today's Antarctica,
294
00:30:51,458 --> 00:30:55,375
it locks away so much water
that global sea levels
295
00:30:55,462 --> 00:30:59,031
drop by 300 feet.
296
00:31:03,600 --> 00:31:06,821
Thousands of miles of vibrant
and colorful reefs
297
00:31:07,039 --> 00:31:08,736
are left high and dry,
298
00:31:11,391 --> 00:31:14,481
deprived of the one
and only habitat
299
00:31:14,568 --> 00:31:17,179
in which it has evolved
to thrive.
300
00:31:17,397 --> 00:31:20,313
85% percent of all
the life on Earth
301
00:31:20,530 --> 00:31:22,532
is driven to extinction.
302
00:31:41,595 --> 00:31:45,904
Ultimately, it is the Earth
itself that comes to life's aid.
303
00:31:48,471 --> 00:31:50,909
Over hundreds
of thousands of years,
304
00:31:53,128 --> 00:31:56,131
volcanic activity
from beneath the ice
305
00:31:56,218 --> 00:32:01,223
spews out carbon dioxide,
warming the atmosphere.
306
00:32:04,574 --> 00:32:06,489
The giant ice cap melts.
307
00:32:09,536 --> 00:32:13,453
and sea levels rise
as fast as they fell.
308
00:32:17,587 --> 00:32:19,589
From their scattered
sanctuaries,
309
00:32:22,592 --> 00:32:25,291
survivors begin to recolonize,
310
00:32:25,769 --> 00:32:29,730
and new versions of the old
animal groups return.
311
00:32:55,495 --> 00:32:57,801
15 million years later,
312
00:32:58,933 --> 00:33:00,979
life roars back.
313
00:33:02,981 --> 00:33:04,591
But there is a crucial
difference.
314
00:33:16,472 --> 00:33:17,952
For the first time,
315
00:33:18,779 --> 00:33:23,349
creatures are leaving the water
for the land.
316
00:33:32,184 --> 00:33:34,142
It is 15 million years
317
00:33:34,360 --> 00:33:37,015
since the oceans
suddenly cooled.
318
00:33:41,410 --> 00:33:45,240
Volcanic activity warmed
the planet and its oceans again,
319
00:33:46,241 --> 00:33:50,158
but the temperature shock caused
a catastrophic mass extinction.
320
00:33:54,075 --> 00:33:57,687
However, enough life
survived to recolonize,
321
00:33:58,384 --> 00:34:01,604
and now, at last,
the shallow seas
322
00:34:01,778 --> 00:34:04,390
are teeming with exotic
creatures again.
323
00:34:11,701 --> 00:34:14,008
Many remain unchanged.
324
00:34:15,923 --> 00:34:18,534
But one group
has been through a revolution,
325
00:34:19,796 --> 00:34:22,756
the descendant of our little
Sacabambaspis.
326
00:34:24,149 --> 00:34:25,237
Fish.
327
00:34:26,586 --> 00:34:29,415
There are now many,
many more of them.
328
00:34:39,555 --> 00:34:42,732
These new fish
have jaws and teeth.
329
00:34:42,950 --> 00:34:45,648
Unlike the timid Sacabambaspis,
330
00:34:45,779 --> 00:34:48,042
they are strong swimmers,
331
00:34:48,260 --> 00:34:51,045
and are the fastest
predators in the sea.
332
00:34:55,963 --> 00:34:58,574
The scorpion is now their prey.
333
00:35:03,144 --> 00:35:06,104
But these scorpions have
a trick up their sleeves,
334
00:35:07,061 --> 00:35:10,630
and there is still a place
where they can rule.
335
00:35:15,200 --> 00:35:19,465
Scorpions are among the first
complex lifeforms
336
00:35:19,639 --> 00:35:24,078
to leave the sea behind,
and crawl up onto land.
337
00:35:27,951 --> 00:35:30,084
Or at least,
the first predators.
338
00:35:36,134 --> 00:35:38,832
Up here, there's new prey
to hunt.
339
00:35:45,926 --> 00:35:50,409
An array of hard-shelled animals
have followed plants onto land.
340
00:35:51,758 --> 00:35:54,804
And animals aren't the only
ones thriving.
341
00:35:58,156 --> 00:36:00,723
Both plants and fungi
have started
342
00:36:00,854 --> 00:36:02,464
to break down the rock,
343
00:36:03,422 --> 00:36:04,510
creating soil,
344
00:36:15,129 --> 00:36:17,000
towering over it all.
345
00:36:21,091 --> 00:36:25,226
Giant fungi,
called Prototaxites,
346
00:36:25,444 --> 00:36:28,925
the largest living things
on the planet,
347
00:36:29,143 --> 00:36:32,320
forming Earth's first forests.
348
00:36:35,497 --> 00:36:38,544
Plant growth has raised oxygen
levels in the atmosphere.
349
00:36:43,201 --> 00:36:45,333
High enough to fuel fire.
350
00:36:51,209 --> 00:36:56,562
In fact, the first forest fire
is a sign of life's success.
351
00:37:00,479 --> 00:37:02,785
It is the start of a journey
352
00:37:03,003 --> 00:37:08,008
that will take living things
to every habitat on Earth.
353
00:37:20,716 --> 00:37:24,981
Today, one of the most
challenging habitats for life
354
00:37:25,155 --> 00:37:27,245
remains the coasts.
355
00:37:30,813 --> 00:37:33,947
Every day, they change
with the tides.
356
00:37:37,167 --> 00:37:40,780
Every year, they grow
or shrink from erosion.
357
00:37:44,262 --> 00:37:46,568
And on a much longer timescale,
358
00:37:46,786 --> 00:37:48,309
they are drowned,
359
00:37:48,483 --> 00:37:51,747
or left high and dry
by changing sea levels.
360
00:37:59,407 --> 00:38:01,104
Since the last ice age,
361
00:38:01,322 --> 00:38:03,977
sea levels have risen 300 feet.
362
00:38:09,156 --> 00:38:10,810
Around the world,
363
00:38:10,940 --> 00:38:14,988
low-lying coastal plains
were replaced by shallow seas.
364
00:38:16,685 --> 00:38:21,473
In Australia, this proved
an ideal habitat for coral.
365
00:38:26,260 --> 00:38:29,829
We now call it
the Great Barrier Reef.
366
00:38:35,530 --> 00:38:38,316
Life has evolved to cope
with changing sea levels.
367
00:38:46,367 --> 00:38:49,152
For humans, the story
is different.
368
00:38:52,417 --> 00:38:55,158
During the short period
of recorded history,
369
00:38:55,333 --> 00:38:57,204
sea levels
have been quite stable.
370
00:38:59,902 --> 00:39:02,470
Vast cities have spread
along our coasts,
371
00:39:05,255 --> 00:39:07,345
some even below sea level.
372
00:39:12,350 --> 00:39:16,354
But now, because of global
warming, that is changing.
373
00:39:18,965 --> 00:39:20,706
Sea levels are predicted to rise
374
00:39:20,923 --> 00:39:23,622
by around three feet
by the end of the century.
375
00:39:25,972 --> 00:39:28,496
We can build barriers
against storms.
376
00:39:32,326 --> 00:39:35,024
But we cannot protect all cities
377
00:39:35,155 --> 00:39:38,245
from the relentless power
of rising oceans.
378
00:39:42,249 --> 00:39:45,034
However, we are learning
from nature.
379
00:39:52,346 --> 00:39:54,087
In some coastal cities,
380
00:39:54,217 --> 00:39:56,002
rather than fighting the threat,
381
00:39:58,439 --> 00:40:01,921
they aim to let the water in,
and manage it.
382
00:40:05,315 --> 00:40:08,275
They are taking a strategic
approach to the future.
383
00:40:13,759 --> 00:40:16,414
Life has shown us the way.
384
00:40:18,154 --> 00:40:22,768
To survive, we must adapt.
385
00:40:29,339 --> 00:40:32,995
♪ I see trees of green ♪
386
00:40:33,213 --> 00:40:35,955
♪ Red roses too ♪
387
00:40:36,608 --> 00:40:41,787
♪ I watch them bloom
for me and you ♪
388
00:40:41,961 --> 00:40:44,920
♪ And I think to myself ♪
389
00:40:46,400 --> 00:40:51,318
♪ what a wonderful world ♪
390
00:40:53,276 --> 00:40:56,976
♪ Yes, I think to myself ♪
391
00:40:58,412 --> 00:41:02,590
♪ what a wonderful world ♪