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.
MUSIC: Fire by Etta James
# 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... #