All language subtitles for BBC.Forces.of.Nature.with.Brian.Cox.3of4.The.Moth.and.the.Flame.720p.HDTV.x264.AAC.MVGroup.org.eng

This programme contains some scenes
which some viewers may find upsetting

The natural world is beautiful
but complex.

The skies dance with colour.

Yay! Yes!

Shapes form...

...and disappear.

But this seemingly infinite
complexity

is just a shadow
of something deeper -

the underlying laws of nature.

The world is beautiful to look at

but it's even more beautiful
to understand.

Watch out for the brambles.

It's a fact, and one of the great
mysteries about our universe,

that everything is made out of
a few simple building blocks

that interact with each other

according to a few simple laws
of nature.

And that applies to everything,

to stars and planets and galaxies
and rocks and oceans,

but also to living things.

And that raises an intriguing
possibility.

By looking carefully at nature,
by doing science,

we might be able to understand
what life is,

and, just perhaps, how it began.

The origin of life is one of the
great unsolved scientific mysteries.

Let's go by the tree.
There might be some over there.

Its origins seem to be lost
in the mists of time.

I've got a really pretty one here.

But in common
with many scientific mysteries,

there may be answers
if you ask simple questions.

Why do moths like flying into
the light so much?

Do they do it...

so they can spread out their wings
and get warm?

What's the deepest question
you can ask about a moth?

I think it's "how did it come
to exist in the first place?"

We can't go back to the origin
of life on Earth -

we don't have a time machine,

but we do have the moth and every
living thing on the planet today.

And these are like
little history books.

Their story, four billion years
of life on Earth,

is written into every
cell in its body.

So in order to discover the spark
of life, the origin of the flame,

we just have to learn
to read the book.

It's gone.

Living things are far too complex
to understand in one go...

...so we have to break the problem
down into simple questions.

What are the ingredients of life?

How does complex life form
from such simple ingredients?

And what was the driving force,

the energy source
that ignited the flame,

four billion years ago?

For the first 500 million years of
Earth's history, there was no life,

just the volcanic violence
of a restless, young planet

and the bombardment of countless
meteorites from space.

But somewhere, somehow,

the ingredients of the planet
were transformed.

Inanimate became animate

and, once ignited, that spark
has never been extinguished.

We are searching for our ancestor
from a time when there was no life.

If we are to understand
how life emerged

from the ingredients present
on the young Earth,

we must first explore
what those ingredients are -

what the Earth is made from.

There are very few places
on our planet

where the pure ingredients
of the Earth can be seen.

But here, beside a lake
of sulphuric acid,

one of the basic building blocks
of the planet boils to the surface.

This volcano delivers
a valuable, pure substance -

sulphur.

Emerging at over
200 degrees Celsius...

...it's an alien-looking cauldron
of chemistry.

Bagio and his father Budi go to
work on the volcano every day.

They labour to protect
the precious, pure sulphur.

This crater is
a working sulphur mine.

Sulphur's valuable

because it gets used in
the manufacture of many products,

from sugar to medicine.

But keeping the sulphur
pure is not easy,

because it readily catches fire
and transforms into sulphur dioxide,

a noxious gas.

Bagio and Budi are here
to fight the fires.

It's rare to find the elements
in their pure form,

because they tend to react
with other elements.

In the heat of the volcano, sulphur
reacts with oxygen in the air.

It burns.

Sulphur burns blue.

Working in the dark,

the firefighters can see
the flames clearly.

And it's their job to prevent
them from spreading.

Sulphur is an element
that is essential to life.

All living things need it.

But here, in such large quantities,
ignited by an active volcano,

it becomes toxic.

On contact with water
in the eyes and mouth,

the gaseous sulphur dioxide from the
flames turns into sulphuric acid.

Sulphur is one of the 92 naturally
occurring chemical elements.

There's no difference between the
sulphur in the wings of a moth...

...and the sulphur that
pours out of a volcano...

...or the sulphur in you and me.

We are made of the same stuff
as our planet

and there's no mystery in that.

It has to be so, because life
emerged from the planet.

Hydrogen atoms, carbon atoms,
oxygen and sulphur atoms.

These basic building blocks react
and combine to make everything.

A woodland is a complex place.

There are oak trees and grass
and mosses and ferns

and countless animals and plants

all living together
in a tangled ecosystem.

But there's a simpler level
of description.

Everything is made of atoms.

So an oak tree is really just
carbon, nitrogen,

oxygen and hydrogen, and a few
other bits mixed together.

So, when you look at it like that,

it's not really that
complicated at all.

The atoms that make up this woodland

have been on an extraordinary
journey to get here.

Think of a carbon atom
in this acorn.

It was assembled in the heart of
a star billions of years ago

out of protons that were built
just after the Big Bang.

It got thrown out into the
universe in a supernova explosion,

collapsed as part of a dust cloud
to form the Sun and then the Earth,

four and half billion years ago.

It will have spent a lot of time
in rocks.

It was probably part of some of
the first living things on Earth.

It would have got breathed out
as carbon dioxide by someone

that walked through this wood
400 years ago.

It will have got into some
ancient oak tree

through the action
of photosynthesis,

constructed into this acorn,
fallen down to the ground

and there it is. It's got a history
that goes back billions of years.

In fact, a history, in terms of
the building blocks of carbon,

the protons, that goes back right
to the origin of the universe.

And in billions of years' time,

when the Sun dies and the Earth
is vaporised,

it will be thrown back out
into space

and probably condensed
into a new world,

billions of years in the future.

So life is just a temporary home

for the immortal elements
that build up the universe.

The atoms are building blocks.

They combine to make molecules,

some of which are terrifically
intricate and complex.

The DNA molecules in the cells
in your body

are made up of billions of atoms
linked together,

carrying the genetic code
to make you.

Exactly how this complexity emerged
is still debated,

but everyone agrees on one thing.

There was a very special theatre
from which biology emerged.

A vital ingredient for life.

And these children know
where to find it.

The elements hydrogen and oxygen
combine to make water,

H2O.

Hidden deep in this forest...

...is a rare and magical sight...

...that only exists because
of a unique property of water.

A property that makes it
essential to life on Earth.

Biologist Tom Iliffe has brought
a specialist team here to find it.

This limestone is fantastic here.

The way it's pockmarked
and dissolved away

indicates that there is a lot
of water moving underneath.

We'll kill ourselves if we go down
that way. Yeah, it's slippery.

I'll slide on my ass.
We'll go that way, yeah.

Only a handful of divers
have the skill

to explore this network of caves.

So, you're going to need
those two and this one, yeah?

These caves are one of the last
true undiscovered, unexplored,

unknown frontiers
on the planet Earth.

Very few people, very few scientists
go out and do anything

any more dangerous than what we're
doing in cave diving.

This underground cave system exists
because water, the liquid we drink,

can eat through solid rock.

It makes easy work
of the soft limestone

and makes things
exceptionally fragile.

Worst thing is,
your tanks may wedge in

and literally stick you in a spot...

...where you can't move
forward or backward.

A little bit distracting when you're
trying to do something underwater

to have the cave
collapsing in on you.

Hey there! Welcome back.
Glad to see you!

Oh, man. That tight spot in there!

I could barely fit through!

Even worse is rocks
that get dislodged.

When they fall down,
it brings down a huge amount of...

I say we leave it 24 hours at least,
so it clears up. OK, OK.

Then come back, give it another go.

You will lose your own visibility
within seconds.

So there's not much time to stop
and hover and think.

The reason why we go through
these narrow slots,

why we push our bodies
to the limits,

is to find something majestic,

something beautiful
on the other side.

But unless you go there, unless you
look, you're never going to know.

Deeper into the cave system,
suddenly, the water changes.

Underneath the forest, miles from
the coast, they've found the ocean.

It's able to flow underground,

working through the pores
and fissures in the limestone

to end up here, where
the denser, salty sea water sinks

below the less dense freshwater,

creating a boundary, a beautiful
phenomenon known as a halocline.

Now we're in sea water.

We've reached the ocean, the
underground ocean in planet Earth.

We can see the movement of water,
freshwater going toward the ocean,

saltwater being sucked inland.

Water dissolves more substances
than any other liquid.

It does this
because it's a polar molecule.

It has positive and negatively
charged regions

and these can disrupt the forces
that bind other molecules together.

Bacteria that line the cave walls

feed on the nutrients
dissolved in the water.

You can see these stringy bacteria
hanging down

and they kind of wave in
the breeze as you fly by.

The bacteria in turn,
are food for other life.

Even in these dark, isolated
environments,

with no direct sunlight to power it,

a complex ecosystem
can be supported.

It's why, as far as we know,

where there's water on Earth,
there's life.

Our blue planet is an interconnected
matrix of rivers and oceans...

...transporting the dissolved
ingredients of the Earth

that are integral to life.

The salts and nutrients that are
carried around our planet...

...are also transported
through our bodies in water.

It's an intimate connection

that every living thing
shares with our blue planet.

Water delivers
the ingredients of life.

Water is a simple molecule,

a couple of hydrogen atoms and
an oxygen atom stuck together,

but its simplicity hides
a wealth of complex chemistry.

The chemistry
that makes life possible.

Hydrogen is the simplest
chemical element.

Its atoms consist of
a single proton -

it's called the atomic nucleus -

surrounded by a single electron.

Oxygen is a nucleus of eight protons
and eight neutrons,

surrounded by eight electrons.

Now, the nucleus is extremely small
compared to an atom.

If a nucleus were about that big,
let's say,

then the cloud of electrons would
stretch out way beyond that castle.

Atoms are almost
completely empty space.

Now, the way that the elements
combine is determined entirely

by the way that the electrons
arrange themselves

around the nucleus.

And that's just down to the basic
fundamental laws of nature

that describe the way our
universe is constructed.

It's very simple.

So, an oxygen nucleus has room
around it for ten electrons,

but it only has eight.

That means that two hydrogen atoms
can come floating in

and share their single electron
with the oxygen,

and that fills up
the oxygen's outer slots

and fills up the hydrogen slots
as well.

Oxygen. Hydrogen. H2O.

Everything is happy and you get
a molecule of water,

which has radically different
properties

to the elements on their own.

Oxygen's just a colourless,
odourless gas.

Hydrogen is a colourless,
odourless gas.

Stick them together to share those
electrons, and you get that stuff.

One of the most complex substances
in the known universe.

The theatre that allows life
to exist.

Water is the universal solvent.

It carries the ingredients of life.

Ingredients that are so important
that living things

will go to extraordinary lengths
to get hold of them.

It's the end of the Alpine winter.

This female ibex
has one thing in mind.

Kids.

She's leading her family
down from the snow line

in search of a life-giving
ingredient.

And it's a search that's not
without its risks.

Rada Bionda is a conservationist
who studies the ibex.

At first glance, the ibex
have everything they need.

They have food and water.

But the mother knows instinctively
not enough.

She's craving something else.

And she'll take risks to get it.

The rock that was used
to build this dam

contains essential minerals
that have been dissolved in water.

Minerals rich in the calcium that
these animals need to stay strong.

And they'll scale a dam to get them.

Without these salts and minerals,
their bones won't grow.

Their nervous systems and muscles
can't function.

Movement and co-ordination
can falter.

There's a strong bond
between mother and kid,

and the kid will follow her
wherever she goes.

The ibex eventually make it
to the prize.

Salt from the Earth
dissolved in water

continues on its journey
into their bodies...

...where it's used in
the nerves and muscles

that control dextrous,
pincer-like hooves.

Vital ingredients carried around
by a simple molecule

with remarkable properties.

If water is the theatre of life,

then the actors
are the atoms and molecules

that form the structures of
living things themselves.

There are only about 15 or so

that are vitally important
for living things.

There are the obvious ones like
carbon, nitrogen, oxygen,

but also some strange ones,
like rubidium,

or an element called molybdenum.

The reactions between
the elements are the same

in living and nonliving things,

but life fine-tunes and controls
the basic chemistry of the Earth

to do extraordinary things.

Moiswa and her family are preparing
for a once-in-a-lifetime ceremony...

...centred around
the chemistry of one element.

Iron.

It lies at the heart
of Maasai culture,

in their land and in their blood.

Tomorrow, Moiswa's son Ndika
will become an elder.

The family are almost ready
for their guests

but there's something they must
first collect from the land.

They are looking for red ochre,

a traditional pigment that has been
in use for over 100,000 years.

The rock's red colour
comes from iron,

which makes up a third
of our planet's mass,

most of it locked away
in the Earth's molten core.

The iron here is not
in its pure form.

It's combined with oxygen
to form iron oxide,

a red compound that, tomorrow, will
provide the colour of celebration.

This is the ceremony that will mark
Ndika's transition into elderhood.

A bull will be slaughtered...

...and he'll drink its blood.

Just like the red ochre from the
Earth, the blood is rich in iron.

Today, for Ndika, blood symbolises
power and strength.

Surrounded by his people,
decorated in ochre,

iron oxide.

It's a proud moment
for Ndika and his family.

Wherever there is
iron and oxygen, they can react,

whether it's in the veins of
the Earth or the arteries of life.

Whether it's in you and me
or the rocks of the Earth,

the fundamental chemistry
is the same.

But the way life uses chemistry
is exquisite.

Just think about the reaction
between iron and oxygen in blood...

...and rust.

Iron is an atom that really would
like to, if it could,

get rid of a few electrons.

Oxygen, on the other hand, is an
atom that would like, if it can,

to receive some electrons.

So if you put them together,

and they stick together,
that's what we call rust.

And the process that makes
our blood red is similar.

We're almost rusting,
but not quite.

One of the jobs of your blood is
to take oxygen from your lungs

and transport it around your body
to where it's needed.

So that means you need
some structure

that can bind oxygen to it,
but quite gently,

so that it can be carried
to where it's needed

and then released, easily.

Well, iron likes to stick to oxygen,

so in your blood you have iron atoms

but they are surrounded
by nitrogen atoms, four of them,

and that's surrounded by a big ring
of carbon and oxygen atoms.

That whole thing is called haem.

And then four of those
are stuck together,

and that thing is called
haemoglobin.

Its job is to carry oxygen around
and when the oxygen attaches,

your blood turns
a much brighter red.

And then the haemoglobin
can carry that oxygen around,

but because of that structure,
it's so delicately tuned

that when the oxygen gets
to where it's needed,

in your brain, for example,
it can be taken off.

Your blood gets less red
and goes back to your lungs

to get some more oxygen.

So, biology is really about using
the natural chemical reactions

of the elements, but tempering
them and fine-tuning them

with intricate
and complex structures

in order to do something useful,

which, in your case, is to live.

We are of the Earth...

...constructed from a ready supply
of chemical elements

forged in the stars.

Elements that react
on our oxygen-rich planet

and play their roles
in the theatre of life.

Water.

But there's one more
vital thing life needs -

energy.

The final clue we need to search
for the origin of life...

...can be found in the details of
how living things control energy.

Every year, between March and June,
an animal rises from the deep.

It harnesses the chemistry
inside its cells

to produce an almost
supernatural display.

For the locals, this alchemy
makes the creature a delicacy.

But for fishermen like Mr Urakami,
it makes them highly profitable.

Mr Urakami is banking on this

being the most lucrative
catch of the year.

And it's not fish he's after.

Away from the fishing boats, these
people are having a bit more luck.

Glowing lights signal the arrival
of the firefly squid.

Tiny organs called photophores
emit a deep blue light.

In the depths, this light
may be used to attract prey

but the greatest light show
is saved for the shallows

where they come up to spawn.

It's a one-way trip.

After they've spent
their last remaining energy,

their glow fades as they give
themselves up to the tide.

Out at sea, the squid
are also rising.

The squid are exploiting
something fundamental -

chemical reactions
can release energy.

Here the energy is released thanks
to the reactive nature of oxygen.

It wants to combine
with other elements

in a reaction known as oxidation.

In the squid, biological molecules
called luciferins,

built out of simple elements
like carbon, sulphur and nitrogen,

react with oxygen
to form oxyluciferin...

...and that process releases energy
as a blue light.

An exquisite display.

For Mr Urakami, this is the
spectacle he lives for.

It's a rare and beautiful sight
in nature...

...but the chemistry of oxidation
is fundamental to all animals.

There's a reason we breathe oxygen.

It fuels the chemical
reactions that power us.

They release the energy
to build and maintain

the complex structure of our bodies.

But it's the precise way life
controls this flow of energy

that's the difference
between a volcano and a squid...

...between raw chemistry and life...

...between a moth and a flame.

That one looks like an old man,
that one there.

That's nice!

Moths and flames always seem
to go together.

In fact, in a basic chemical sense
they are very similar,

and candle wax is essentially food.

It's a collection of long chain
carbon molecules.

And the candle, that food,

reacts with oxygen to produce
carbon dioxide, water

and release energy,
which is the flame.

And inside the moth,
exactly the same thing is happening.

Food is reacting with oxygen to
produce carbon dioxide and water

and release energy.
The energy that powers life.

That's called respiration.

It sounds quite simple.

We burn our food to release
the energy we need to live.

What do moths eat in the winter?

It's not that simple.

But simple questions lead
to the deepest answers.

In this case, to the origin of life.

The moth doesn't use the energy
released from food directly.

It does something
way more complicated.

It uses that energy to pump protons,

the building blocks of atomic
nuclei, across membranes.

Billions of them. And so do you.

And so does every living thing
on the planet.

In the time it's taken me to say
the sentence,

you have pumped more protons
across membranes

than there are stars
in the observable universe.

And then all those protons are
allowed to cascade back

down proton waterfalls,

and little nanomachines with little
water wheels stick in

to that waterfall, and spin around
and produce molecules called ATP,

which are the universal batteries
of life,

which are then, finally,
used to power your biology.

It is incredibly complicated,
and to be honest, a bit weird.

This complicated and weird chemistry

powers practically every
living thing on Earth...

...but it had to start somewhere...

...and it may have begun
before there was life.

There is a place where this strange
chemistry exists today,

but not in a living thing.

This may be the clue

to how you get from the Earth

to you and me.

This fjord in Iceland is one
of the few places on Earth

where you can see how life
could have emerged

from a restless, young planet.

My next-door neighbour
was this old lady

telling me stories about
the things she saw from the sea.

I have been diving there many times,
so I knew this place.

I didn't believe this old lady.

Curiosity drove diver
Erlendur Bogason

to an extraordinary discovery.

So I called my friend Artni,
the fisherman,

and asked him to
take me to this place.

Biologists knew of places
where the chemistry of life

emerges from the Earth,

but they're all thousands of metres
below the surface of the ocean.

These two men stumbled on a place
where you can literally touch it.

I was, like, stressed
because you're going alone

somewhere to dive, and you don't
know what you're going to find.

And when I did see this huge white
thing, it looked like a giant.

It was unbelievable sight.

Wow. It's beautiful.
Something incredible.

Erlendur had discovered
a hydrothermal vent,

but unlike those in the deep ocean,
you can swim right up to this one.

The vent is an outpouring
of fresh water

that's been heated by Iceland's
geothermal energy.

I took my glove off to put my arm
into the hot water.

It was like burning hot.

By studying vents like these,

scientists discovered that
the chemistry of life exists

in a nonliving thing,

in the Earth.

I called this scientist
and told him about this.

We went back for him
to take water samples.

To create a spark of life,
all you need is a battery,

with a flow of charged particles -
in this case, protons.

And to power the battery,

you need nothing more than water
from the vent and some sea water.

Thank you.

To show it works, you just need
to connect it all to a voltmeter.

And that is the spark of life.

Why would I say that?

Well, this water, taken from
the vents, is alkaline

and this sea water is relatively
more acidic.

That means that there is an excess
of protons

on this side of the battery
than this side.

And there's that waterfall,
that cascade of protons,

the same thing that's happening
in the cells in your body,

in the cells in the body
of the seagulls

and in fact the cells in the body
of every living thing on the planet.

Waterfalls of protons powering life.

And that's the clue.
That's the smoking gun.

The theory is that
the chemistry of life,

the beginnings of the assembly
of complex molecules,

all the way up to the first
living things to DNA

and everything we think
of as life today

was built, was constructed,
in conditions like this.

The waterfall, the cascade of
protons is the driver of complexity,

the spark of life.

It's the exquisite control
of the proton waterfalls

that separates life
from chemistry...

...the moth from a flame.

So just spare a thought for
what your body is doing now.

I mean, that sandwich you just ate
before watching this programme,

you're burning that in oxygen,
it's the oxygen that you breathe in.

But you're not using the energy
that gets released directly.

You're using it
to pump protons around.

You pump them across little
membranes, creating a voltage.

About 30 million volts per metre
in the cells in your body.

That's the voltage
of a lightning bolt.

That's the spark of life

and that's the clue that tells you
that the origin of you,

the most distant ancestor of you,
wasn't a living thing at all,

it was a geological thing.

It was most likely to be a vent like
the one we're floating over now,

in some ocean,
four billion years ago,

the very earliest life
of our planet.

From a sandwich to
a bolt of lightning,

you are a remarkable machine.

For me, this theory
of the origin of life

is the perfect example
of the power of science.

It's a grand, sweeping idea that
comes from exploring in detail

the way that living things
control their energy.

Look, it's slightly
vibrating its wings.

From asking questions like,

what's the difference between
a moth and a flame?

He's going for a walk.

But the answer is a wonderful story.

At this instant,
in the cells in your body,

you're recreating
the conditions that were present

in the oceans of
the primordial Earth.

You are just chemistry.

But what chemistry!

The Earth is your ancestor.

A restless planet is your creator.

Fire by Etta James

♪ Fire

♪ Fire

♪ Fire

♪ I'm on fire

♪ You make my body shiver, boy

♪ You make my head go bad

♪ You make my liver quiver, babe

♪ You make my eyes get red

♪ My knees get weak when I see you

♪ Your love is much too strong

♪ And when you take me in your arms

♪ You know tomorrow is my home

♪ Like I'm burning, yeah... ♪