Original subtitles

PROFESSOR BRIAN COX: 7fhis creature is a wonder of life.

A voracious predator,

this male has lived under water for nearly five months,

feeding, growing,

preparing for this moment.

He is about to undertake one of the most remarkable transformations

in the natural world.

From ağuatic predator

to master of the air.

(BUZZING)

The brief adult life of a dragonfly

is amongst the most energetic in nature.

Dragonflies are the most remarkable animals.

You can see their

incredible agility

in flight just watching them skim across the surface of this pond.

They can pull two and a half G in a turn

and they can fly at 15 miles an hour which is fast for something that big.

They've been around on Farth since before the time of the dinosaurs.

And in that time they have been fine-tuned by natural selection

to do what they do,

which is to catch their prey on the wing.

So, dragonflies are beautiful pieces of engineering.

They're intricate, complex machines.

But is that all they are?

Because once their brief lives are over, their vitality will be goöne.

And this raises deep guestions.

What is it that makes something alive?

And how did life begin in the first place?

So, what is the difference between the living and the dead?

What is life?

(MYSTICAL MUSIC PLAYING)

I've come to one of the most isolated regions of the Philippines,

to visit the remote hilltop town of Sagada.

İt's a two-day drive from the capital Manila,

over some of the country's roughest roads

that wind their way 1,500 metres up into the hills.

This is a place where the traditional belief

is that mountain spirits give us life

and that our souls return to the mountain when we dlle.

And where the people who live here still imagine

that the spirits of the dead Walk among the living.

(OVERLAPPING CHATTER)

(CHILD LAUGHING)

Tonight is November the first

and here in Sagada, in fact, across the Philippines,

that means that it's the Day of the Dead.

That's a day when people come to this graveyard on a hillside

and, well, celebrate the lives of their relatives.

The people light fires to honour and warm the departed,

inviting their souls to commune with them.

No matter how unscientific it sounds, this...

this idea that there's some kind of soul or spirit or...

animating force that makes

us what we are, and that persists after our death, is common.

Virtually every culture, every religion,

has that deeply-held belief.

And there is a reason for that. Because it feels right.

I mean, just think aboutit.

İt's hard to accept that when you die, you will just stop existing.

And that you are, your life, the essence of you,

is just really something that emerges from an inanimate bag of stuff.

(SPEAKING TAGALOG)

Don't get too close. Hooray!

You can see that these people feel

not only that they can celebrate the lives of their relatives,

but they're coming, in some sense, to communicate with their relatives,

even though their physical bodies have died,

they are still, in some sense, here.

And when you think about it, that's not so easy to dismiss.

I mean, if we are to state that science can explain everything

about us, then it's incumbent on science to answer the guestion -

what is it that animates living things?

What is the difference between, er...

a piece of rock that's carved into a gravestone and me?

From millennia, some form of spirituality has been evoked

to explain what it means to be alive

and how life began.

İt's only recently that science has begun to answer

these deepest of guestions.

In February, 1943,

the physicist Erwin Schrodinger gave a series of lectures in Dublin.

Now, Schrodinger is almost certainly

most famous for being one of the founders of guantum theory,

but, in these lectures, which he wrote up in this little book,

he asked a very different guestion.

"What is life?"

And right up front on page one,

he says precisely what it isn't.

"It isn't something mystical," says Schrodinger.

There isn't some mağgical spark that animates life.

Life is a process.

It is the interaction between matter and energy described

by the laws of physics and chemistıy.

The same laws that describe the falling of the rain

or the shining of the stars.

So, the guestion İs,

how is it that this magnificent complexity that we call life

could have assembled itself on the surface of the planet

which itself formed

from nothing more than a collapsing cloud of gas and dust?

To Schrodinger, the answer had to lie in the way living things process

öne of the universe's most elusive properties.

Energy.

Energy is a concept that's central to physics

but, because it's a word that we use every day,

its meaning has got a bit woolly.

I mean, it's easy to say whatit is, in a sense.

I mean, obviously this river has got energy

because, over the decades and centuries,

it's cut this valley through solid rock.

But while this description sounds simple,

in reality things are a little more complicated.

For me, the best definition is that

it's the length of a space-time core vector in the time direction.

But that's not very enlightening, I'll grant you that.

Över the years, the nature of energy

has proved notoriously difficult to pin down.

Not least because it has the seemingly magğical property

that it never runs out.

It only ever changes from one form to another.

So, take the water in that waterfall. At the top of the waterfall,

it's got something called gravitational potential energy,

which is the energy it possesses due to its height above the EFarth's surface.

See, ifl...

scoop some water out of the river into this beaker,

then I'd have to do work to carry it up to the top of the waterfall.

I'd have to expend energy to get it up there.

So, it would have that energy as gravitational potential.

I can even do the sums for you.

Half a litre of water has a mass of half a kilogram

multiplied by the height. So, that's about five metres

and acceleration due to gravity is about 10 metres per second sguared.

So, that's half times five times 10 is, uh, 25 joules.

So, I'd have to put in 25 joules

to carry this water to the top of the waterfall.

Then, if I emptied it

over the top of the waterfall, then all that gravitational potential energy

will be transformed into other types of energy.

İt's sound, which is pressure waves in the air.

There's the energy of the waves in the river

and there's heat.

So, it will be a bit hotter down there

because the water İs cascading into the pool at the foot of the waterfall.

But the key thing is

energy is conserved. İt's not created or destroyed.

So, because energy is conserved

if I were to add up all the energy in the water waves,

all the energy in the sound waves,

all the heat energy at the bottom of the pool,

then I would find that it would be precisely egual

to the gravitational potential energy at the top of the falls.

What's true for the waterfali

is true for everything in the universe.

It's a fundamental law of nature

known as the first law of thermodynamics.

And the fact that energy is neither created nor destroyed

has a profound implication.

İt means energy is eternal.

The energy that's here now has always been here.

And the story of the evolution of the universe

is just the story of the transformation of energy from one form to another,

from the origin of the first galaxies to the ignition of the first stars

and the formation of the first planets.

Every single joule of energy in the universe today

Was present at the Big Bang 13.7 billion years ago.

Potential energy held in primordial clouds of gas and dust

Was transformed into kinetic energy,

as they collapsed to form stars

and planetary systems Jjust like our own solar system.

In the sun, heat from the collapse initiated fusion reactions at its core.

Hydrogen became helium.

Nuclear binding energy was released, heating the surface of the sun,

producing the light that began to bathe the young Farth.

And at some point in that story, around four billion years ago,

that transformation of energy led to the origin of life on Earth.

Around 350 kilometres south of Sagada, this is lake Taal.

Despite its sleepy languid appearance,

this landscape has been violentiy transformed by energy.

When I think of a volcano, I usually think

of a pointy, fiery mountain with a little crater in the top.

Probably a bit like that one.

But, actually, this entire lake is the flooded crater of a giant volcano.

It began erupting only about 140,000 years ago.

And in that time, it's blown 120 billion

cubic metres of ash and rock into the Earth's atmosphere.

This crater is 30 kilometres across

and, in places, 150 metres deep.

I mean, that's a cube of rock

five kilometres by five kilometres

by five kilometres just blown away.

İt's a big volcano.

Taal lake is testament to the immense power

locked within the Earth at the time of its formation.

Since the lake was createdi, a serles of further eruptions

formed the island in the centre.

And at its heart is a place where you can glimpse the turmorl

of the inner Farth,

where energy from the core still bubbles up to the surface,

producing conditions similar

to those that may have provided the very first spark of life.

Now, the water in this lake is different from drinking water

in a very interesting way.

See, if I test this bottle of water

with this, which is called universal indicator paper,

then you see immediately that it goes green.

And that means that it's completely neutral.

İt's called pH 7 in the jargon.

Then, look what happens when I test the water from the lake.

Now the indicator paper stays orange,

in fact, it might have gone a bit more orange.

So, that means that this is acid. İt's about pH 3.

At the most basic level,

the energy trapped inside the Earth is melting rocks.

And when you melt rock like this, you produce gases.

A lot of carbon dioxide.

And, in the case of this volcano, a lot of sulphur dioxide.

Now, sulphur dioxide dissolves in water

and you get H2SO4, sulphuric acid.

Now, what do I mean when I say that the water is acidic?

Well, water is H20, hydrogen and oxygen bonded together,

but actually when it's liguid, it's a bit more complicated than that.

İt's actually a sea of ions.

So, H plus ions. That's just single protons.

And OH minus ions. That's oxygen and hydrogen bonded together.

ALI floating around.

Now when something is neutral, when the pH is 7,

then that means that the concentrations of those ions are perfectly balanced.

When you make water acidic,

then you change the concentration of those ions,

and, to be specific, you increase the concentration

of the H plus ions, of the protons.

So, this process of acidification has stored

the energy of the volcano as chemical potential eneragy.

The volcano transforms heat from the inner Earth

into chemical energy and stores it as a reservolrr of protons in the lake.

And this is the same way energy is stored in a simple battery

or fuel cell.

These bottles contain a weak acid,

and are connected by a semi-permeable membrane.

Passing an electric current through them has a similar effect

to the volcano's energy bubbling up into the lake.

İt causes protons to builld up in one of the bottles.

You can think ofit, I suppose, like a waterfall

where the protons are up here waiting to Tlow down.

And all you have to do to release that energy

and do something useful with it is complete the circuit.

Which I can do

by just connecting a motor to İt.

There you go. Look at that.

That's the protons cascading down the waterfall,

and driving the motor around.

(CHUCKLES) It actually works.

GOuite remarkable, actually.

Now, the fuel cell produces and exploits its proton gradient artificially.

But there are places on EFarth

where that gradient occurs completely naturally.

Here, for example.

So, we've got the proton reservoir over there, the acidic volcanic lake.

If you look that way, there's another lake

and the reaction of the water with the rocks on the shore

make that lake slightly alkaline, which is to say that there's a deficit

of protons down there.

So, here's the waterfall.

Reservoir of protons up there, the deficit down there.

If you could just connect them,

then you'd have a naturally occurring geological fuel cell.

And it's thought

that the first life on our planet may have exploited the energy

released in those natural proton waterfalls.

(CHİLDREN SHOUTING, LAUGHING)

What do you think? It's good, isn't it?

These are pictures from deep below the surface of the Atlantic Ocean,

somewhere between Bermuda and the Canarles.

And it's a place known as the Lost City.

You can see why. Look at these.

Huge towers of rocks, some of them 50, 60 metres high,

reaching up from the floor of the Atlantic and into the ocean.

İt's what's known as a hydrothermal vent system.

So these things are formed by hot water and minerals and gases

rising up from deep within the Earth.

The reason it's thought that life on Earth may have begun

in such structures is because these are a very unigue kind

of hydrothermal vent called an alkaline vent.

And about four billion years ago, when life on Earth began,

sea water would have been mildly acidic.

So, here is that proton gradient, that source of energy for life.

You've got a reservoir of protons in the acidic sea water

and a deficit of protons around the vents.

And the vents don't just provide an energy source.

They're also rich in the raw materials life needs.

Hydrogen gas, carbon dioxide

and minerals containing iron, nickel and sulphur.

But there's more than that. These vents are porous.

There are little chambers inside them

and they can act to concentrate the organic molecules.

You've got everything inside these vents.

You've got concentrated building blocks of life trapped inside the rock.

And you've got that proton gradient.

You've got that waterfall that provides the energy for life.

So this could be where your distant ancestors come from.

Places like these could be the places where life on Earth began.

The first living things might have started out

as part of the rock that created them.

Simple organisms

that exploited energy from the naturally occurring proton gradients in the venits.

And we think this because living things still get their energy

using proton gradients today.

Deep within ourselves,

the chemistry the first life exploited in the vents

is wrapped up in structures called mitochondria.

Microscopic batteries

that power the processes of life.

This is a picture

of the mitochondria from a little brown bat.

This is the picture of mitochondria from a plant.

İt's actually a member of the mustard family.

This, a picture of mitochondria in bread mould.

And this, mitochondria inside a malaria parasite.

So, the fascinating thing

is that all these animals and plants

and, in fact, virtually every living thing on the planet

uses proton gradients to produce energy tolive.

Why?

Well, the answer is probably

because all these radically different forms of life

share a common ancestor.

And that common ancestor was something that lived

in those ancient undersea vents four billion years ago,

where naturally-occurring proton gradients provided the energy

for the first life.

So, if you are looking for a universal spark of life,

then this is it.

The spark of life is proton gradients.

In those four billion years, that spark has grown

into a flame.

And a few simple organisms

clustered around a hydrothermal vent

have evolved to produce all the magnificent diversity

that covers the Farth today.

(RUMBLING)

Today, life on Earth is so diverse.

İt covers so much of the planet, that you can find places like this lake.

I mean, it's effectively its own sealed ecosystem.

İt's salt water. It's connected to the sea.

But it's only connected through small channels through the rock.

So that means that the marine life in the area is effectively isolated.

(BIRDS CHIRPING)

This is the golden jellyfish,

a unigğue subspecies only found in this öone lake on this öone island

in the tiny Micronesian Republic of Palav.

They used to live like most jellyfish.

Cruising the open ocean, catching tiny creatures,

zooplarıkton, in their long tentacles.

But today, their tentacles have all but disappeared.

Because the golden jellyfish have evolved to do something

that very few other animals can do.

İt really is incredible.

There are... I want to say, millions of jellyfish

as far as you can see, all the way down

till the... till the light vanishes, there are jellyfish.

And you can see them congregating in the sun. If you go over there

to where the lake's in shade, there are just none.

And then, in this pool of light

beneath the sun, there are millions of them.

Beautifully elegant things just floating around.

(CHUCKLES)

I'm not being unduly hyperbolic. İt's gulite remarkable.

(MUFFLED MUMBLING)

This lake is home to over 20 million jellyfish,

whose success comes down to a remarkable adaptation.

Their bodies play host to thousands of other organisms.

Photosynthetic algae that harvest energy directly from sunliğht.

The jellyfish engulf the algae as juveniles.

And, by adulthood, algal cells make up around 1096 of their biomass.

Grouped into clusters of up to 200 individuals,

they live inside the jellyfish's own celis.

The gölden jellyfish uses algae to get most of its energy from photosynthesis.

The ones at the surface are gentiy...

Wow! There's one there. They're gently turning.

The reason they do that is to give all their algae

an eğual dose of sunlight.

So they are guite democratic creatures, just making sure

they get as much food as they can.

And they just come up to you

jellying around,

photosynthesising.

They tell me they don't sting.

But I'm sure I've got a tingling finger.

And it's not just their anatomy that's adapted to harvest solar energy.

Every morning, as the sun rises,

the jellyfish begin to swim towards the east.

And as the sun tracks across the sky, they move back again

towards the west where they spend their night.

So, the jellyfish have this...

beautiful, intimate and complex relationship

with the position of the sun in the sky.

As sunliğht is captured by their algae,

it's converted into chemical energy.

Enerogy they use to combine simple molecules,

Water and carbon dioxide,

to produce a far more complex one -

glucose.

Önce absorbed by the jellyfish, glucose and other molecules

not only power their daily voyage across the lake,

they provide the basic building blocks the jellyfish use to grow

the elegant and complex structures of their bodies.

So the jellyfish, through their symbiotic algae,

absorb the light, the energy from the sun, and they use İt to...

to live, to power their processes oflife.

And that's true, directly or indirectly,

for every form of life on the surface of our planet.

But things are a little bit more interesting than that,

because energy is neither created nor destroyed.

So life doesn't eat it somehow.

İt doesn't use İit up. It doesn't remove it from the universe.

So what does it do?

To understand how energy sustains life,

you have to understand exactiy what happens to it

as the cosmos evolves.

In the first instance after the Big Bang,

there was nothing in the universe but energy.

(RUMBLING)

As it changed from one form to another,

galaxies, stars and planets were born.

But while the total amount of energy in the universe stays constant,

With every single transformation,

something does change.

(CRACKLING)

The energy itself becomes less and less useful.

It becomes ever more disordered.

And you can see this process in action

as energy from the sun hits the surface of the Farth.

Think about this sand on the beach. It's been under the glare of the sun all day.

İt's been absorbing its light, which has been heating it up.

And now that the sun is dipping below the horizon,

then the sand is still hot to the touch.

Because it's reradiating all the energy that it absorbed as heat

back into the universe.

And the keyword there is "all". AILL the eneragy.

See, ifit didn't do that, then it would just gradually heat up

day after day after day and eventually, I suppose, the whole beach would melt.

So, what's changed?

Well, it's the guality of the energy, if you like.

I mean, think about it.

If as much energy was coming back off this sand now

as İit absorbed from the sun, then it should be giving me a suntan.

Right? I should need sun creamif I sit looking at this beach all night

and obviously I don't.

The difference is that this energy is of a lower guality.

It can do less.

İt's heat, which is a very low guality of energy indeed.

So what the sand's done

is take highly-ordered, high-guality energy from the sun

and convert it to an egual amount of low-guality, disordered eneragy.

(WAVES CRASHING)

Ihis descent into disorder is happening across the entire universe.

(EXPLODING)

As time passes, every single joule of energy

is converted into heat.

The universe gradually cools towards absolute zero

until with no öordered energy left,

the cosmos grinds to a hallt...

and every structure in it decays away.

Yet whilst the universe is dying,

everywhere you look, life goes on.

İt's a deep paradox that Schrodinger was well aware of

when he wrote his book in 1943.

"How can it be," writes Schrodinger,

"that the living organism avoids decay?" In other words,

how can it be that life seems to continue to build

increasingly complex structures

when the rest of the universe is falling to bits, is decaying away?

Now, that's a paradox

because the universe is falling to bits.

İt is tending towards disorder.

That is enshrined in a law of physics called the second law of thermodynamics.

And I think most physicists believe

that it's the one law of physics that will never be broken.

The key to understanding how life obeys the laws of thermodynamics

is to look at both the energy it takes in

and the energy it gives out.

This is a thermal camera, so hot things show up as red

-and cold things show up as blue. -(COCK CROWING)

So what you're seeing here

is that the chicken is hotter than its surroundings.

Now heat is a highly-disordered form of eneragy.

So the chicken is radiating disorder

out into the wider universe.

By converting chemical energy into heat,

life transforms energy from an öordered to a disordered form

in exactiy the same way as every other process in the universe.

(COCK CROWING)

In fact, every single human being generates

6, 000 times more heat per kilogram than the sun.

And it's by converting so much energy from one form to another

that life is able to hang on

to a tiny amount of order for itself.

Just enougğh to resist the inevitable decay of the universe.

So it's no accident that living things are hot

and export heat to their surroundings,

because it's an essential part of being alive.

The living things borrow order from the wider universe

and then they export it again as disorder.

But it's not precisely in balance. They have to export more disorder

than the amount of order they import.

That is the content of the second law of thermodynamics.

Living things have to obey the second law

because they're physical structures.

They obey the laws of physics.

Just by being alive

we too are part of the process of energy transformation

that drives the evolution of the universe.

(RUMBLING)

We take sunliğht that has its origins at the very start of time

and transform it into heat

that will last for eternity.

So far from being a paradox,

living things can be explained by the laws of physics.

The very same laws that describe the falling of the rain

and the shining of the stars.

The dragonfly draws its energy from proton gradients,

the fundamental chemistry that powers life.

But the real miracles are the structures

they build with that energy.

Borrowing order to generate cells,

arranging those cells into tissues

and those tissues into the intricate architecture of their bodies.

So we've developed a guite detailed understanding

of the underlying machinery that powers these dragonflies

and, indeed, all life on Earth.

And, whilst we don't have all the answers,

it is certainly safe to say that there's no mysticism reduired.

You don't need some kind of magical flame

to animate these little machines.

They operate according to the laws of physics.

And I think they are no less magical for that.

Yet the dragonfly will only maintain this delicate balancing act for so long.

Because all living things share the same fate.

Fach individual will die.

But life itself endures.

This is because there's something that separates life

from every other process in the universe.

(BIRDS CHIRPING)

(ELEPHANT TRUMPETIİNG)

This is the Malaysian state of Sabah

on the northern tip of the island of Borneo.

It's öone of the most biodiverse places on the planet.

Home to 15,000 plant species,

3,000 species of tree,

420 species of bird

and 222 species of mammals,

-including those. -(TRUMPETS)

(ELEPHANT ROARS)

Borneo's rainforests contain trees

that are thought to live for more than a thousand years.

But the forest itself has existed for tens of millions of years.

The reason it persists is because each generation of animal and plant

passes the information to recreate itself

on to the next generation.

And that's possible

because of a molecule found in every cell of every living thing.

A molecule called DNA.

Now, all I need to isolate my DNA is some washing-up liguid...

a bit of salt...

and the chemist's best friend...

vodka.

Now, to get a sample of DNA,

İ can just use myself. If I just swirl my tongue around

on the edge of my cheek,

I'll dislodge some cheek cells into my saliva.

(CHUCKLES) I missed the test tube.

There we are. İt's a physicist doing an experiment.

(CHUCKLING)

Then... I add a bit of washing-up liguid.

Now, what this will do...

is it will break open those cheek cells

and it will also degrade the membrane that surrounds the cell nucleus

that contains the DNA.

Salt will encourage the molecules to clump together.

DNA is insoluble in alcohol.

So you should get a layer...

of alcohol...

with the DNA molecules precipitated out.

Yeah.

There, can you see?

Those strands of white.

And so, in that cloudy, almost innocuous-looking solid,

are all the instructions needed

to build a human being.

So that is what makes life unigue.

Only living things have the ability to encode

and transmit information in this way.

And the conseguences of that profoundly affect our understanding

of what it is to be alive.

This rainforest is part of the Sepilok Forest Reserve.

And in here somewhere are some of our closest genetic relatives.

COX: Shh. Shh.

Oh, yeah. There. Can you see?

Orang-utans are highly specialised for a life lived in the forest canopy.

Their arms are twice as long as their legs.

And all four limbs are incredibiy flexible,

each öone ending in a hand

whose curved bones are perfectliy adapted for gripping branches.

These adaptations are encoded in information passed down in their DNA.

(CHUCKLES) He's got a hat on.

He has actually just put a hat on.

(CHUCKLES)

This is the orang-utans' genetic code.

It was published in 2011.

And there are over three billion letters in İt.

And if I flick through it...

Look at that.

Now, it's composed of only four letters - A, C, T and G,

which are known as bases.

They're chemical compounds. They're molecules.

And the way it works is beautifully simple.

They are grouped into threes called codons.

And some of them just tell the code reader, if you like,

how to start or where to start and where...

-(LEAVES RUSTLING) -...and when it's gonna stop.

(COX CHUCKLES)

He's fast. (CHUCKLES)

So you would have a start and a stop

in between each group of three codes for a particular amino acid.

Now amino acids are the building blocks of proteins

which are the building blocks of all living things.

So you would just read along. You would find a start-stop.

And then you would go along in threes. Build amino acid, build amino acid,

build amino acid, build amino acid.

Stitch those together into a protein. And if you keep doing that,

eventually, you will come out with one of those.

İ mean, it's not that simple, of course.

But the basics are there.

This code written in there...

are the instructions to make him.

To faithfully reproduce those instructions,

for generation after generation,

the orang-utans, and indeed all life on Farth,

rely on a remarkable property of DNA.

Its incredible stability and resistance to change.

Every time a cell divides, its DNA must be copied.

And the genetic code is highly resistant to copying errors.

The little enzymes, the chemical machines that do the copying,

on average make only one mistake in a billion letters.

I mean, that's like copying out the Bible about 280 times

and making just one mistake.

That fidelity means adaptations are faithfully transmitted

from parent to offspring.

And so while we think of evolution aS a process of constant change,

in fact, the vast majority of the code is preserved.

So even though we are separated from the orang-utans

by nearly 14 million years of evolution,

what's really striking is Just how similar we are.

And those similarities are far more than skin-deep.

Orang-utans are surely one of the most human of animals.

And they share many of the behavioural traits that you would define

as being uniguely human.

They nurture their young for eight years

before they let them go on their own into the forest.

In that time, the infants learn which roots are safe to eat

and which are poisonous,

which branches will hold their weight and which won't.

And they can do all that because they have memory.

They can remember things that happened to them in their life.

They can learn from them and they can pass them on

from generation to generation.

And that deep connection extends far beyond our closest relatives

because our DNA contains the fingerprint

of almost four billion years of evolution.

(BIRDS CHIRPING)

If I draw a tree of life for the primates,

then we share a common ancestor with the chimps and bonobos.

About four to six million years ago.

And if you compare our genetic seguences,

you find that our genes are 9996 the same.

We go back to the split

with gorillas, about six to eight million years ago,

and, again, iİf you compare our genes

then you find that they are 98.496 the same.

Back in time again.

Common ancestor with our friends over there, the orang-utans,

then our genes are 97.496 the same.

And you could carry on all the way back in time.

You can look for our common ancestor with a chicken

and you'd find that our codes are about 6096 the same.

And, in fact, if you look for any animal like him. A little fly or a bacteria,

something that seems superficially completely unrelated to us,

then you will still find seguences in the genetic code

which are identical to seguences in my cells.

So this tells us that all life on Earth is related. It's all connected

through our genetic code.

DNA is the blueprint for life.

But its extraordinary fidelity means it also contains a story.

And what a story it is.

The entire history of evolution

from the present day, all the way back to the very first spark of life.

And it telis us that we're connected.

Not only to every planet and animal alive today,

but to every single thing that has ever lived.

The guestion "What is life?" is surely one of the grandest of guüestions.

And we've learnt that life isn't really a thing at all.

İt's a collection of chemical processes

that can harness a flow of energy to create local islands of order,

like me and this forest,

by borrowing order from the wider universe.

And then transmitting it from generation to generation

through the elegant chemistry of DNA.

And the origins of that chemistry can be traced back four billion years,

most likely to vents in a primordial ocean.

And, most wonderfully of all, the echoes of that history

stretching back for a third of the age of the universe

can be seen in every cell of every living thing on Earth.

And that leads to what I think is the most exciting idea of all.

Because far from being some chance event ignited by a mystical spark,

the emergence of life on Earth

might have been an inevitable conseduence of the laws of physics.

And, if that's true,

then a living cosmos might be the only way our cosmos can be.

(GALAXY DNA SONG PLAYING)