All language subtitles for BBC - First Life (2010) - (E1 - Arrival) BD 1080p

I'm on a fantastic journey
to look for the origins of life.

I shall be traveling not only
around the world, but back in time,

to try and build a picture

of what life was like
in that very early period.

It will be a journey
full of wonders.

Parts of it were unknown
until only a few years ago.

In 50 years of programme-making,
I've been lucky enough to explore

the living world
in all its splendor and complexity.

The blue whale! The biggest creature
that exists on the planet!

Now, I'm off to explore
the origins of all this.

To look for the very first living
creatures that appeared on the planet.

In recent years, scientists have unearthed dramatic
evidence of what those first creatures were like.

We can also find clues
in living animals.

And this enchanting little creature

is what we were looking for.

Using the latest technology, it's possible
to bring those first animals to life

for the first time
in half a billion years.

From the moment they appeared

to the time that they took their
pioneering steps on land,

we can deduce how animals
acquired bodies that move,

eyes that saw and mouths that ate.

And we can understand
how those first organisms

laid the foundations for modern
animals as we know them today.

Hello, old boy. How are you?

'Including you and me.'

My 40,000 mile journey begins
very close to home, in Britain.

This is the Charnwood Forest in
Leicestershire in the middle of England.

As a schoolboy, I grew up near here.

And in these rocks,
a discovery was made

that transformed our understanding

of that mystery of mysteries,
the origin of life.

The history of life can be
thought of as a many-branched tree,

with all the species alive today

related to common ancestors
down near the base.

The five kingdoms of life, the main
branches, were established early on.

Bacteria.

Protists - amoeba-like creatures.

Fungi.

Plants.

And animals. That for me is the
most fascinating question of all.

How and when did they first appear?

The answers
are only now beginning to emerge -

and some of the first clues
came from here in Charnwood Forest.

I was a passionate fossil collector.

But I never came to look for them
in this part of Charnwood,

because the rocks here are
among the most ancient in the world.

Around 600 million years old,
in fact.

And every geologist knew or
at least was convinced that rocks of

such extreme age couldn't possibly
contain fossils of any kind.

And then a boy from my very own school,
just a few years after I left it,

made an astounding discovery.

Against all the predictions
of scientific know-alls,

he found a fossil in these
ancient Leicestershire rocks.

And this is it.

It's called and is known
around the world as Charnia,

after the forest
in which it was discovered.

But what is it?

Is it animal or plant?

The fact is
it comes from such a remote period

that the distinction between those
two forms of life was not yet clear.

But one thing is certain.

It clearly was alive.

Charnia was a marine organism,
part of an ancient community

of living things that lived in
darkness at the bottom of an ocean.

That much we do know.

But what was this strange creature?

When did it first appear?

And how is it related
to modern animals?

The answers to these questions
are only now beginning to emerge.

There were further finds
in Charnwood forest, like this disk,

which was probably the holdfast

which secured the frond of Charnia
to the sea floor.

And then people began to look in
rocks of this great age

all around the world.

And lo and behold they discovered
a whole range of fossils

that enable us now to put together
in extraordinary detail

the first chapters
in the history of life.

That all happened
a very long time ago.

Imagine traveling back
through time.

Humans have been around for
two million years.

The dinosaurs were wiped out
65 million years ago.

Charnia is more than eight times
older than the oldest dinosaur.

It lived
about 560 million years ago.

But compared with the age of
life itself, that's nothing.

Before Charnia
and other complex organisms existed,

the only living things
were microscopic single cells.

They first appeared about
three and a half billion years ago

when the Earth
was a very different place.

The early continents
were still forming.

The days were a mere six hours long,
because at that time

the Earth was spinning much faster
on its axis than it does today.

The land was
dominated by volcanoes -

hostile and lifeless.

But deep in the oceans,
life had begun.

The latest theory is that chemicals
spewing from underwater volcanic vents

solidified and created
towers like these,

and this produced the conditions
needed for the first cells to form.

Some of these began to harness the energy of sunlight,
just as plants do today, and formed colonies.

These rocky stromatolites
in western Australia

have been constructed by very
similar photosynthesizing bacteria.

Others managed to survive by
extracting nourishment directly

from the environment, like the fungi
and animals that would later evolve.

This state of affairs continued
for a vast period of time.

For some three billion years,
simple microscopic organisms

were the most advanced form of life
on the planet.

That's way over half
the entire history of life on Earth.

And then suddenly, within the space
of a few million years, a mere

blink of the eye in evolutionary
terms, advanced organisms appeared.

Why is a mystery,

but we may find some clues to it
on the coastline down here.

On the Eastern coast of Canada,
there is evidence of an event that

may well have been the spark that
started the evolution of animals.

These rocks
have been dated by radioactivity

to just before the moment
that life became very complex.

So if we can understand the circumstances
under which these rocks were formed,

we may get a clue as to why it was that
life suddenly became more complex.

Fragments of red stone
are embedded in the darker rock.

They look out of place.

And, in fact, they are.

Geologists call them dropstones.

They were transported here
by glaciers.

As the ice moved off the land,

it floated out over the sea
in a great shelf,

carrying with it stones that
it had gathered on the continents.

And when the ice eventually melted,

the stones fell into
the sediments on the sea floor.

This wasn't the only place
covered by ice.

Drop stones of the same age have been
found in deposits all over the world.

The evidence points to
a global spread of glaciation.

Just before complex life appeared,
the world was in the grip

of the biggest ice age
in its entire history.

It's been called Snowball Earth.

The Earth was plunged into
a deep freeze

so severe it probably extended

from pole to pole.

The surface of the seas
were frozen over.

On the continents, ice caps
and glaciers developed.

In places, the ice was probably
a kilometer or so thick.

We still don't know enough about
the details, but it's likely that

those conditions lasted
for millions of years.

Stromatolites and similar bacterial
colonies that dominated the Earth

were crushed under
the advancing glaciers.

Life was nearly annihilated
before it had truly begun.

It's difficult to imagine how life managed
to survive in those circumstances.

But survive it did.

Microbiologist Dr Hazel Barton

believes that modern glaciers
can tell us how it did so.

She has come to the Columbia
Icefield in the Rocky Mountains

in search of organisms that are still
able to endure such extremes today.

The thing about being here

is it looks like everything's been
wiped clean,

the glacier's come through
and it's destroyed all life,

there's nothing living.

But to a microbiologist this
looks a bit like a rainforest.

From here you can see discoloration
on the surface of the ice,

but that's not dirt -

that is photosynthetic bacteria
that are surviving there

and that creates an ecosystem
where you have plants

and you have predators come in
and feed on those organisms.

So even though it looks dead,
it's actually wildly alive with life.

The kind of life you can see here
is pretty ancient.

They've had to adapt to a lot of
global catastrophes.

They had to adapt to Snowball Earth.

Microorganisms that live in these harsh
environments we call extremophiles.

They have an amazing amount of adaptability
that's hardwired in their genomes.

You can freeze them, you can
bury them a mile down in ice

and its not much of a hindrance
because of their adaptable nature.

We owe our existence
to ice-dwelling extremophiles.

Snowball Earth
almost extinguished life,

but tiny organisms like these
hung on for millions of years.

I think what you had is

organisms that could
withstand extreme environments

conditioning themselves
to this changing ecosystem.

You had a skin of microbes
on the surface of the planet,

and you had these organisms living between
where the, the glaciers contacted the rock,

and that was enough life
trickling over so that

when those conditions retreated,
and it became more favorable,

then it was like, pff,
and everything took off again.

Finally,
Snowball Earth began to warm.

There is evidence that
around this time,

there was a global surge
in volcanic activity.

Eruptions punched through the ice,
spewing carbon dioxide into the air.

As it spread through the atmosphere,
it produced a greenhouse effect,

trapping heat so that
the earth warmed and the ice melted.

We still have a lot to discover
about what happened next,

but it seems likely that it was
the melting of Snowball Earth

that led to the next
great development of life.

As the glaciers retreated,

so nutrient-rich meltwater
flooded into the oceans.

For the surviving cells, this flood
of ground-up rock was a bonanza.

For the microbes
that could photosynthesize,

the pulverized rock
was a potent fertilizer.

And their growth would have a direct
influence on early animal cells.

Cyanobacteria
and other oxygen-producing microbes

began to bloom across the globe.

These flourished in colonies of
plant-like microbes

that pumped out
enormous volumes of oxygen.

And it was this increase in oxygen

that was the key to the rise
of the animal kingdom.

Now, simple microscopic life

had the fuel it needed
to develop into something bigger.

After billions of years of
single-celled life,

something amazing
happened in the deep sea.

Up to this moment, living cells
that had been produced by division

simply drifted away from
one another.

But now,
with the aid of increased oxygen,

some cells were sticking together.

Some of these clumps
ultimately evolved into animals.

To find out how oxygen
drove this process,

I have come to
Australia's Barrier Reef,

to look at one of the most primitive
of animals alive today -

one that can truly be called
a living fossil.

It is one of the simplest
multi-celled organisms that we know,

but its basic body structure
has nonetheless enabled it

to survive virtually unchanged for
around 600 million years.

It's a sponge.

Sponges are just
collections of simple cells

that have clumped together
and got stuck together.

They don't have a digestive system
or a nervous system

or a blood circulatory system,

and they get their food
and their oxygen

by just pumping seawater
through channels in the body.

But they can give us an indication
of how it was that cells

first clumped together
to form bodies of any real size.

At the microscopic level,
sponge cells are bound together

by a tangle of hairy, stringy
protein molecules called collagen.

This collagen glue is found
only animals, and nowhere else.

Collagen is sometimes called
the sticky tape of the animal world.

It's the commonest protein
in our body.

It forms the framework of our skins.

Plastic surgeons use it
to pump up our lips.

You need oxygen
to manufacture collagen

and with the rising amount
of oxygen in the atmosphere

at the end of Snowball Earth,
cells were able to manufacture it.

At the Research Station on Heron
Island on the Great Barrier Reef,

scientists are working
to understand

how it was that
multi-celled organisms

began to colonize the earth.

To find the answer, marine biologist
Professor Bernard Degnan

is studying sponges.

The things that connect sponges to
the rest of the animal kingdom

we can find at the level of
the cell and the gene.

When we look at its genes,
it's clearly an animal.

We look for the things that
bind all animals together,

so what does a human share
not only with a chimpanzee

and for that matter a tiger
but what it shares with a sponge.

If we can find any common threads,

we're getting really to the heart of
the matter of multicellularity

in the animal kingdom,
so that's the key.

A classic experiment
gives us some insight.

First, a sponge
is cut into small pieces.

Then it is pushed through a sieve
on the end of a syringe.

This breaks the animal down
into its individual cells.

This may seem a brutal thing
to do to a living organism,

but to a sponge
this is of no consequence.

In response,
it does something quite astonishing.

The cells begin to move...

and then they form clumps.

Soon the clumps form bigger clumps,

until three weeks later,
a miniature sponge has formed.

Sponges have this amazing capacity
to regenerate themselves.

And what we can do is
actually rebuild a sponge

from the cell level up.

From this experiment,
we can maybe infer a few things

that happened 600 million years ago
with the very first animals.

We can infer that there were
cells coming together,

they could adhere to each other,
they used extracellular proteins

like collagen
to glue themselves together.

They had the ability to
communicate with each other

and a certain amount of flexibility
that allowed them to interact

to give rise to something
that's bigger and greater,

a large macroscopic
multicellular animal.

The advantages of being
multi-celled were many.

Colonies of cells
could collect more food,

control their internal environment

and act efficiently
by working as a team.

It was just the beginning.

In Canada,
there is an extraordinary place

that reveals what happened next.

Here you can see how just a few million
years after the melting of Snowball Earth,

the earliest multi-celled organisms
became much more sophisticated...

and much bigger.

This is Mistaken Point
in Newfoundland.

It got that name because in years gone by sailors
coming up the eastern coast of North America

but lost in the fogs
that are so frequent here

would head north for the open ocean

but be wrecked
on these savage rocks.

But today Mistaken Point has
a completely different reputation.

Today it is recognized as one of

the most important fossil-bearing
sites in all the world.

For here you can see fossils

of the very first animals
that evolved on this planet.

The fossils in these rocks
are both wonderful and bizarre.

When the sun is low in the sky,

the slanting light shows up
their structure in great detail.

Organisms were no longer

just clumps of undifferentiated
cells, like sponges.

They were organized
into defined shapes.

And among them are some
that look exactly like Charnia

that had been first recognized
in Charnwood Forest.

Here, there are not only
hundreds of examples of Charnia,

but a whole community of other
strange creatures.

Everywhere you look there are
complex markings and indentations

of one kind or another -

it's almost as though children
have been playing in wet sand.

It's like walking through
a carpet of ancient creatures.

It's difficult to imagine that
565 million years ago

this was the bottom of the ocean

and these were some of the first
animals to live on this planet.

Here at Mistaken Point,

exceptional conditions have
preserved these delicate life forms.

Each one of these layers of rock

was once mud
lying at the bottom of an ocean.

An ocean so deep it was very cold,

and very poor in oxygen,

so any organism that died here
took a very long time to decay.

But those that did
have been preserved

with an astonishing degree
of perfection.

What makes this place so different?

There was a volcano rising from
the sea floor close by,

and it spewed out
millions of tons of ash.

The ash sank to the bottom,

blanketing everything
like a sub-marine Pompeii.

Over millions of years, the ash
itself was buried by muddy sediments

and then all was turned into rock.

And then, over hundreds of
millions of years,

mountain-building forces thrust
the whole sea-floor upwards

to its present position
on the coast of Canada.

Dr Guy Narbonne is a world expert
on the fossils of Mistaken Point.

What you can see on this surface

is the Grey is the muddy sea bottom

and this is where
the creatures all lived.

And they were knocked down and
covered by a bed of volcanic ash.

And you can see it here
and all of this pink and white

speckled stuff is volcanic ash.

The volcanic ash
cast every part of them,

like putting plaster around your arm
if you break it,

and that led to
a perfect preservation

of every detail of the outside.

Radioactivity in this
light-colored ash layer

allows Guy Narbonne
to date precisely the eruptions,

and therefore the fossils.

Some are as old as
579 million years.

Here we can see one of the best
of the fossils on the surface.

It consists of disks,
and they all have these pustules

on them and that's why we rather
affectionately call them pizza disks.

And they were very simple in form,

but the first truly large creatures
in Earth evolution.

The pizza discs are only one
of the species found here.

Most are fern-like fronds, like
this enormous species of Charnia.

This is a two-meter-long frond.

Astounding!
And this is not the biggest.

We have about
200 specimens of this here.

The frond of Charnia found
in Charnwood was isolated.

But here at Mistaken Point, a whole community
of organisms has been preserved together...

and that
could give us new information.

You're calling this an animal but is
it justified to call it an animal?

Well... It's rather plant-like.

Well, "What is it?"
is a big question.

We know for a fact
it can't be a plant

because we're in water thousands
of meters deep,

there wouldn't have been enough
light to read a newspaper.

We're several orders of magnitude
too little light for photosynthesis.

OK, so it's not photosynthesizing
because it's too deep

and therefore it's not a plant.
What's it living on?

What we believe they're living on is dissolved
carbon and other nutrients in the deep oceans.

So it's absorbing these nutrients
through its entire body.

Very thin. Probably
not much thicker than your thumbnail.

Very primitive.

These organisms were
very simple animals.

Beyond the reach of light, they had to
survive by absorbing chemical sustenance.

But most animals we know today
are able to move about.

Even sponges and corals
have swimming larvae.

But there's no evidence
of that here.

The creatures were all immobile.

Nothing could move.

Nothing had a mouth,

nothing had muscles.

Probably none of them had color,

probably an eerie whiteish color
to everything.

These are the oldest large
multi-cellular creatures on Earth,

the oldest things that
might be called proto-animals.

This is not like anything
that exists on earth today.

Even though they're not directly
related to us,

like some distant relative, they provide
us with a view of our own beginnings.

One of the most peculiar things
about these wonderful proto-animals

is the way they
constructed their bodies.

Unlike modern creatures, they had
a very simple pattern of branching.

Despite their size,
these are still very simple animals.

They can be put together with just
six to eight genetic commands,

as against some 25,000 such commands that
were needed to construct a mammal like me.

You can see this
if you look at them in detail.

You see that they are made up
of a series of very small modules

which are attached to one another
in a number of different ways.

Their modular or fractal way of building their bodies
is one of Guy Narbonne's main areas of research.

His study is centered on
one particular species.

This is Fractofusus.

It's the most common fossil in
the Mistaken Point assemblage.

We have literally
thousands of specimens.

And it would have lain on the
sea bottom like you see there.

A spindle-shaped mass, very thin.

It consists of these elements.

And there are 20 of
them on either side.

And if you look at
an individual element,

it's remarkably finely-branched.

It's a style we called
fractal or self-similar.

These fractal organisms
grew by repetitive branching,

with each branch
exactly the same as its predecessor

from the microscopic level upwards.

It was a simple, yet extremely,
effective way of building a body.

Such finely-divided branches gave
the organism a huge surface area,

and this allowed them to absorb nutrients
directly without mouths and without guts.

This simple fractal body plan
proved very successful.

So animals using it grew large for the first
time in the history of life on Earth.

Fractal design was perfect for getting
these earliest creatures off and running

and its easy to see why.

It takes a minimum of genetic
programming in order to make one.

You could probably do it with
six or eight codes in your PC

to make something that
was fractally branching.

And then combining them to make up larger
elements is literally child's play,

like a toddler might take Lego blocks and put them
all together in order to make up a larger structure.

The fossils of Mistaken Point provide
a detailed record of fractal animals.

But the absence of anything like them in
more recent rocks is very significant.

Just a few million years after
they first evolved, they vanished.

They have no living descendants.

They were an evolutionary dead end.

And the reason?

The very simplicity
of their fractal way of growing.

They utterly dominate about the first 20 million years of
the evolution of complex multi-cellular proto-animals.

However, this fast start
was also their demise.

Because they were incapable
of evolving things like

guts and brains and muscles and teeth
that later animals did.

If animals were to
acquire these things,

they would have to build their bodies
in a completely different way.

And eventually, animals appeared
that did exactly that.

To see them, I'm traveling south
from Newfoundland across the equator

to South Australia.

The Ediacara Hills.

Here lie animals whose body plans are fundamentally the
same as those of almost all animals alive today...

including us.

The creatures that are preserved here lived
just after fractal animals began to die out.

And about 550 million years ago, their differently-organized
bodies gave them something quite new...

...mobility.

But how and why
did animals first begin to move?

Scientists are beginning to find answers
to those fascinating questions.

And much of the detail comes from these
extraordinary fossils behind me.

A team of scientists, led by
paleontologist Dr Jim Gehling

is uncovering the
evidence in great detail.

When you have these
beds covered in red clay

you have a good chance of the beds
having well-preserved fossils.

This is the original sea floor.

And this sea-floor was very different from
that in the deep waters of Mistaken Point.

This was once a shallow reef.

It is 550 million years old.

The surface of the ocean floor
was covered with organic ooze.

It may have even been green or
orange. We don't know the color.

But there was a lot of organic material made up
by bacteria and all sorts of microorganisms.

But sitting in and amongst that garden of slime,
we would have seen these strange creatures.

Jim Gehling's team is working
to decipher the fossils.

But it is not easy because these creatures
still lacked any hard parts to their bodies.

If I was working on dinosaurs,
I'd go to a spot,

find the bones and carefully dig them up, take
them back into the lab, reconstruct the dinosaur.

But I'm not dealing with bones. I'm
dealing with soft-bodied creatures.

All you've got are imprints of squishy
things living flat on the seafloor.

Despite the challenges, Jim has
discovered compelling evidence here

that these animals
had begun to move.

On this fossil bed, we find
something very interesting.

It's a series of faint,
but very definite circles.

They are almost identical in size
and they overlap quite often.

And then when you go to the end
of the series of discs,

you find a hollow with the imprint
of a very distinct fossil,

that of Dickinsonia.

Dickinsonia was
a cushion-like creature

that lay flat on the seafloor.

It ranged from the size of a penny
to that of a bath mat.

These imprints represent
something very important.

They are the first evidence

of a kind of mobility
of animals on the seafloor.

The first animal movements were undoubtedly
slow, but perhaps even too slow to notice.

To see them in action,
you have to speed them up.

Dickinsonia crept from one
feeding place to the next,

absorbing the organic matter beneath
it and then moving on once again.

Perhaps it moved with the help of hundreds
of tiny tubular feet, as starfish do today.

The excavations at Ediacara reveal that Dickinsonia
wasn't the only mobile creature around.

Animals everywhere were on the move,
actively seeking food.

This shape here is a resting place of
a slug-like animal called Kimberella.

And these here, marks,
are showing how it fed.

It had a proboscis, a snout,

and it fed by sifting through the
mud, making these scratch marks.

But it tells us more
than how this animal fed.

It also tells us how it moved
because if you look back this way,

this is where is started feeding

and then it moved along here with
more feeding marks and grooves,

and then it settled down here

into the mud
where its final resting place was.

So this shows that the animal
not only fed like that,

it actually moved like that.

Kimberella was a very early
ancestor of today's mollusks.

It probably had
a single muscular foot,

just as snails and slugs have today

with which it pulled
itself along the sea bottom.

Our speeded-up view of
the Ediacaran seafloor

gives an idea of what a busy place
the oceans had now become.

Whether that movement is by creeping
or crawling over the seafloor,

it doesn't matter
because that animal

has advantages over an animal
that is fixed to the seafloor.

It can move away from danger.

It can move towards
richer sources of food.

It can move away from places which
are over-colonized by its neighbors.

That gives it an enormous
advantage in the history of life.

This new mobility was only made possible by a
major change in the layout of animals' bodies.

When we get to Ediacara, we still have
some of those beautiful fractal-like forms

that you see at Mistaken Point but in the
Ediacara Hills we see something very different

and that is, for the first time,

you see a blueprint for all animals
from then on, including ourselves.

'The modern animal body plan
is called bilateral symmetry.'

What we see here is Spriggina.

Let's make a cast of the fossil.

Spriggina represents
the first ever animal

which had
clear bilateral symmetry.

It had a body with a head at
one end, a tail at the other.

And almost identical halves,
if you split it down the middle.

We see these together
with other creatures

which have
this kind of body form.

Spriggina is just one
of countless kinds of fossils

in the Ediacara Hills
that had developed in this way.

It had a head and a tail, and so
it moved in a particular direction.

It's quite likely that they had sensory
organs concentrated in the head.

Now why does
my nose occur near my mouth?

It's a very good reason. I want to
smell the food before I ingest it.

Why are my eyes above my mouth?

So I can see what I'm eating.

This head demonstrates
that sensory capacity had evolved.

It was able to sense where food was
likely to be on the seafloor.

And, therefore, clearly had a mechanism
for actually moving towards that food.

Bilateral animals like Spriggina
had another advantage.

Between the head and the tail,
there are numerous segments.

So these animals could increase in
size by simply adding more segments.

What is more, each segment
could do a particular job.

Once you start to move,

you develop a front end
and that becomes your head.

And you also, by definition,
have a back end.

And in between, segments
on which you can add appendages.

On that basic pattern,
you can add further features.

On the front end, that's where you
need sense organs, eyes, feelers.

On the appendages, you can modify
them to be hooks and claws

that would help you
to catch things.

And at the back end, there will be a pore
from which you excrete the waste products.

And that is the basic body plan of almost all
the animals that are alive on Earth today.

It had taken 3,000 million years for multi-celled
organisms to appear for the first time.

But now, less than 100 million years
later, an evolutionary blink of an eye,

animals had appeared that had the same
basic body plan as most that live today.

They had heads and tails
and segmented bodies.

And they were able
to move to find food.

How was it that animals had
suddenly become so complex?

The Ediacara Hills may hold the evidence
for an answer to that question.

Living organisms don't live forever.

If a species is to survive it has to reproduce and
the first simple animals did that very simply,

by straightforwardly dividing.

But if a species is to survive it also has to have
the ability to change with a changing environment.

And to do that involves reproducing
in a rather different way.

Evidence of how that happened can also be
seen is these very ancient Australian rocks.

In 2007, paleontologist
Dr Mary Droser

discovered in these
550-million-year-old deposits

evidence that animals
had started to reproduce sexually.

The animal concerned
is called Funisia.

If Droser's theory is right, this
wormlike creature produced offspring

by exchanging genetic material
with other individuals.

This gene-swapping, or sex,

shuffles the genetic pack, greatly accelerating
variation and therefore evolution.

Sexual reproduction is absolutely
one of the most fundamental steps

in the history of life.

It is why we have the
diversity that we have.

It's the birds and the bees.

As far as we know, this is the first
evidence of animals' sexual reproduction,

and we're not catching the animal
in the act of it,

we're looking at the product of what
we conclude was sexual reproduction.

This fossil is key to
Mary Droser's argument.

The small circles show where the
animals were anchored to the ground.

You can see that these attachment
structures are basically all the same size.

They're all about a couple
of millimeters in diameter.

And you could go to another bed, and all the
Funisia are half a centimeter in diameter.

So the same size are
all occurring together.

This uniformity of size in a particular
place is, Mary Droser believes,

strong evidence that a new way
of reproducing had arrived.

We link this to sexual reproduction

because if you look in modern environments,
when you have this kind of size groupings,

that is 99.9% of the time
a product of sexual reproduction.

To understand why, I'm traveling 2,000 miles
northeast of Ediacara to the Great Barrier Reef.

Here, there are modern creatures that reproduce
in the way that Funisia is thought to have done.

They're corals.

Corals, like Funisia,
are anchored to the seabed.

They feed
by filtering food from the water.

And the way they breed creates one of
nature's greatest annual spectacles.

Once a year, there's an
important event among the corals.

We're not sure how it's coordinated.

It probably has something to do
with the moon.

But it gives us a hint as to how sexual
reproduction might have first appeared.

At exactly the same time,

the corals release countless millions
of sperm and eggs all at once.

The event is precisely timed
to maximize the chances

of fertilization.

Millions of offspring are
simultaneously conceived.

So, as the coral grows,
the individuals that make up

the colonies are all of
exactly the same age and size,

just like Funisia.

It's unlikely that Funisia was the
first animal to reproduce sexually.

But its discovery suggests that many other animals
are also reproducing by mixing their genes.

And that might explain how
complex animals evolved so quickly.

The arrival of sexual reproduction
speeded evolution.

Here was a mechanism that produced
greater genetic variation more quickly.

So, over many generations, species were able
to adapt to their changing environments.

550 million years ago, animal life
was on the verge of a major advance.

In an environment where animals were becoming
more mobile, they would have to adapt fast.

Movement requires a lot of energy.

Simply absorbing nutrients
through the surface of the body

as Dickinsonia did
was much too slow a process.

Mobile animals would need to consume
huge quantities of food.

And they would do that by evolving the
very first stomachs, mouths and teeth.

You can see how they might
have done so in Switzerland...

...where a new kind of technology
provides a window into the past.

This stadium-sized building houses one of
the world's most powerful microscopes.

It's called the synchrotron.

Professor Philip Donoghue is preparing the
tiniest of fossils for the synchrotron.

These minuscule balls were excavated
from a quarry in South China.

Each and every one of them is the
fossilized embryo of an ancient creature.

If we really want to understand
these fossils,

what we need to do is not
just to look at the surface

which we can do with
an electron microscope.

We need to look inside.

We have to use some form of X-ray tomography,
a bit like CAT scanners in hospitals.

But we have to use one that allows us to look at the very
tiniest details down to a thousandth of a millimeter.

The synchrotron is the only
X-ray type machine that provides

the kinds of resolution that we need to see all
the tiny details within the fossilized embryos.

KLAXON SOUNDS

It was astonishing, I mean
it was a real eureka moment

that you could get to the very finest
levels of fossilization,

the very finest detail that the fossil record
could ever give up using this technology.

Powerful generators fire high-energy electrons around
a circular tube at close to the speed of light.

After one million orbits, the electrons emit
X-rays so powerful, they can penetrate solid rock

or these tiny fossils.

Donoghue uses data
from the synchrotron

to build a three-dimensional
picture of the fossils.

We know it's a fossil embryo because
it's surrounded by a preserved egg sac.

And using tomography we can see
inside to the developing animal.

This fossil is the embryo of
a tiny marine worm called Markuelia.

It lived just twenty million
years after the animals of Ediacara.

Using his 3D model,
Donoghue is able to see inside it

and there he
found evidence of something new.

These fossils provide the first clear
evidence for a gut within animals.

We can clearly see that there's
a mouth right at one end

surrounded by rings of teeth
that extend inside the mouth.

And then there's a gut that extends all the
way through to an anus at the other end.

Internal digestion enabled Markuelia to extract
energy from its food in a very efficient way.

And the fact that it had teeth
suggests that it had a new diet -

other animals.

The fact that it's got rings of teeth arranged
by its mouth, that it would have averted out

or it would have ejected out of its mouth to grasp
prey items, tells us that this thing was a predator.

For the first time,
there were hunters in the oceans.

And that had enormous
evolutionary implications.

There was about to be an explosion of life that
would lay the foundations for modern animals.

In another wave of evolution,

the animal basic body plan
became more and more elaborate.

Fearsome predators
appeared in the seas,

great monsters on the land and
animals became masters of the Earth.

Next time I continue my journey
in the Rocky Mountains of Canada,

the deserts of North Africa

and the tropical rainforests
of Australia.

I will discover how and why animals
evolved skeletons and shells.

How they developed true,
picture-forming eyes.

How others
went to extraordinary lengths

to protect themselves from attack.

And I shall discover the first animals that moved
out of the sea to conquer the land and the air.