Original subtitles

Across our natural world,

life has taken on countless forms.

Wondrous, strange...

and endlessly diverse.

It's easy to imagine that all of this is, like,

somehow preordained...

that it's been made, a world of balance and purpose,

but the truth... The truth is much wilder.

This is a world of survivors.

From Earth's earliest moments,

evolution has quietly,

relentlessly,

shaped the story of life.

I can hear it...

And in this series...

It's quite emotional, if I'm honest with you!

we'll trace the astonishing evolutionary journeys of five

iconic modern animals.

Look at this!

Truly spectacular!

We'll meet their oddball ancestors from the distant past

and discover how generation, by generation...

Absolutely amazing!

they changed, to become the creatures we know today.

From the smallest beginnings come the most extraordinary stories,

stories of survival, of bizarre transformations,

shaping life in the strangest of ways

and, behind it all, the unstoppable force of evolution.

Look at that! They used to say that animals couldn't experience joy.

Come on! That looks like muddy, wet joy to me!

CHRIS LAUGHS

The African savannah elephant has to be one of evolution's most

enchantingly strange creatures.

I mean, look at the trunk.

When they're adult, that measures nearly two metres in length,

and it contains perhaps 90,000 miniature muscles.

And then the tusks.

Those are teeth that never stop growing.

The ears! Look at the ears on this one,

the size of a table cloth,

flapping away.

But their one most obvious defining feature, of course, is their size.

Look at that!

They can regularly reach five, six, seven tonnes.

The very biggest, ten tonnes.

They are colossal.

So, here's a question for you.

How did evolution come up with something as complex,

as beautiful and as enormous as this?

How did the elephant come to be?

Well, to understand the elephant,

the largest land animal alive today...

you have to understand evolution itself.

There was no blueprint, no grand design.

Evolution is a process, shaped by powerful, invisible drivers.

Like hunger...

conflict...

and even...

catastrophe.

So where does our story begin?

The answer lies in what these giants are made of.

They may be the world's largest land mammals, they may be beautiful,

but brutally biologically speaking, this is just a giant mass of cells.

Now, in case of the elephant, that's a lot of cells.

It's a quadrillion.

That's a one with 15 zeros after it.

Cells are the fundamental building blocks, not just of elephants,

but of all life today, be it animal...

plant,

fungi...

or bacteria.

So, where did those cells come from?

Well, each one of this animal's cells has come from other

cells, which have either divided or reproduced.

OK, where did those cells come from?

Well, they come from other cells that divided and reproduced.

In fact, we can trace this chain back over unimaginable

periods of time, through many long-lost extinct species,

until remarkably it converges at a single point,

a single-celled organism that's connected to every living thing,

every branch on the tree of life,

a common ancestor that lived billions of years ago,

the cell that started everything.

Now, when it comes to evolution, you need to take the long view.

I mean the really long view.

The elephant's improbable journey begins before mammals, before

dinosaurs stomped about, before anything even had legs to stomp.

It's a story that starts with a simple truth.

If you want to evolve, you have to survive first.

Violent,

loud...

Frankly, overdramatic.

The young Earth is no paradise...

but beneath the waves, life has already taken hold.

Trillions of tiny, primitive cells battle the elements.

Almost all will perish.

But one cell is different.

Within this tiny speck lies the future of all living things.

It's a speck with a name.

Meet LUCA, the ultimate survivor.

The great-great-great times a billion grandparent of you,

the elephant, and every other living thing on Earth.

LUCA stands for Last Universal Common Ancestor.

So, let's just think about this for a moment, because it was this

single-celled organism, floating around in a world entirely

alien to our own, which gave rise to every living thing on our planet.

That's me, that's you, that's all the animals, all the plants,

all the fungi, all the bacteria, everything!

So, LUCA isn't just a clever acronym,

something out of a biology class.

LUCA defines the point where the story of life as we know it

truly began.

There are no fossils of LUCA...

but because all living things have DNA

and use the same genetic code, we know there must be a shared origin.

Look at that.

But why did LUCA and its descendants survive...

Ooh! when trillions of others vanished?

That's actually starting to burn my hand.

Clues can be found in the Earth's most extreme places.

I want to take my hand out of there. That's how hot it is.

With alkaline water up to 86 degrees Centigrade...

these are the sort of hostile conditions LUCA may have endured.

But nevertheless, look.

Life is tolerating it all round here.

I know what you're thinking, this doesn't look like much,

and certainly compared to us, this is pretty simple stuff.

But I've got to tell you, it's not.

The cells in here are amongst the most complex

things in the known universe.

Each one of these cells is generating energy,

distributing that energy, dealing with waste.

It's sensitive to its environment, it's reproducing.

Every one of these cells is more complex than any machine

ever made by any human.

Just like these cells, LUCA was complex, robust, resilient...

which may have helped it cling on against the odds.

Now, we know that Luca wasn't the first cell and that it lived amongst

other cells, but what made it special is that it didn't just live,

it thrived, it survived.

That little bubble of chemicals,

formed in chaos billions of years ago.

LUCA was the little cell that could.

Plucky? Yes.

Lucky? Almost certainly...

but it also has life's greatest survival trick.

LUCA can copy itself.

Well enough to keep its genetic line going...

but not so perfectly that every copy is identical.

With every new generation, tiny errors, mutations,

creep into its DNA.

And yet these so-called mistakes fuel evolution.

The story of our modern, living world has begun.

Now it's time to hit fast forward.

I mean, you can't cover four billion years of evolution without

skipping some chapters.

Generation after generation,

little mistakes lead to entirely new life forms.

Some cells begin to capture the sunlight - the ancestors of plants.

Others would adapt to feed on decay - fungi.

Many stay small and simple - the hidden world of microbes.

But the cells that would give rise to the elephant

take a very different path...

three and a half billion years after LUCA...

when the Earth is in a deep freeze.

This is a period of intense global cooling.

Ice grips the planet, and food webs are collapsing.

But somewhere in the cold and dark,

one hungry cell is about to change everything.

The need to feed is one of the great driving forces of evolution.

Any creature that can find its food more efficiently is more

likely to survive and pass its genes into the next generation,

as was the case over 600 million years ago

when a single cell was on the verge of a breakthrough,

a breakthrough that would lead to the incredible

diversity of almost all animal life to come.

Meet the ancient ancestor of the elephant...

indeed of all animal kind.

Urchoanozoan now has mitochondria for energy...

a nucleus for control...

and a tail-like flagellum to move.

But one thing hasn't changed...

this cell is still tiny...

just 100th of a millimetre across.

It's a small cell with a big problem.

Food is brutally scarce.

And that cell's ancient hunger may have set life on a new course.

And you can see how, thanks to a remarkable creature alive today.

You might be wondering, what have

a mass of insects like this got

to do with an ancient single-celled organism?

Well, the twist is that in the quest for food,

they both came up with a similar solution...

and it's down to numbers.

You see, single ants are not very good

when it comes to overwhelming prey.

They're simply too small, they don't have the strength.

So, what they've done is turn into a mass killing machine.

Each one of the individuals has become a cog in that machine,

and this means that they're far more efficient

when it comes to handling whatever they're going to eat.

Ow! It's all right.

These ants act as one giant organism...

overwhelming their meals with sheer force of numbers...

and when they swarm, almost anything is on the menu.

Crickets, caterpillars, or, if they're wounded,

even chickens, goats and pigs and, by the feel of it, even a Packham!

And there's the parallel with those ancient single-celled organisms,

because they were about to adopt a similar technique which would

change the world...

forever.

Oh, my goodness!

My world's been changed forever, I think, to be quite honest with you.

There are some of them in places that you won't be filming them.

Get off!

Over 600 million years ago,

Urchoanozoan is about to do something revolutionary.

Its surface is coated with sticky molecules...

and when the time comes to divide...

instead of floating off to live independent lives...

the two remain stuck together.

They continue to divide.

More and more cells stick together...

until...

a vast alliance forms.

Dubbed the Death Star...

it's 100 larger than a single cell...

and it has something of the dark side to it.

When the all the flagella wiggle,

they create stronger water currents...

drawing in bacteria so the Death Star can feed.

From cells sticking together came a new way of living.

A multicellular organism is formed.

Over the next 100 million years,

the Death Star's descendants continue to grow...

not just in size,

but in complexity...

as individual cells begin to specialise...

until something truly revolutionary emerges...

the first bodies on Earth.

The oceans have now warmed and they're full of life forms.

And lurking among them is the ancestor of the elephant.

No trunk, no tusks...

just a worm, three millimetres long,

dragging itself across the seafloor.

Evolution gave it a body,

but one so small and simple you'd barely notice it.

Building something bigger

and more complex would require one vital ingredient...

oxygen.

Inside every cell in our body a slow, controlled burn is happening.

Not with flames, of course, that would be concerning.

But just like this fire, we need oxygen to release energy.

Without it, we would simply sputter out and die.

But for ancient animals, oxygen was largely out of reach.

I've got some earthworms here, charming creatures,

creatures of childhood, but not terribly sophisticated,

particularly when it comes to breathing.

You see, just like those early animals,

they breathe through their skin.

It's permeable, and as long as it's moist,

they can extract oxygen from the air.

But imagine you're living half a billion years ago.

You're much smaller than this, and living at the bottom

of an ocean where the oxygen supply is pitifully low.

Life was small, life was slow,

life was stuck.

But this ancient worm has stumbled upon a new way to

boost its oxygen supply.

Tiny pores along its body, used to filter food,

are now quietly adapting to a new role.

They're able to draw in a fraction more oxygen...

the beginning of a transformation that will allow creatures to

grow bigger and stronger.

And beating the competition is what it's all about.

Generation by generation, tiny wrinkles inside the pores deepen,

folding, twisting, meaning more surface area,

more oxygen...

until a whole new body part evolves.

In tracing the evolution of the elephant or, for that matter,

any other large land animal,

the appearance of gills is hardly an obvious landmark moment.

After all, elephants aren't famed for

their deep-sea diving capabilities.

But the emergence of gills was more than a minor upgrade.

It was an evolutionary quantum leap.

This is the fossil of Yunnanozoon.

It lived in the Cambrian around 500 million years ago.

What is it? Well, it wasn't a worm, wasn't yet a fish,

but what makes it interesting is this...

You can see these feathery structures

running down here in rows.

Some scientists believe that this is the first evidence

that we've discovered of gills.

Intricate folds like these can radically increase

the surface area that's in contact with water...

giving the animal the potential to access much more oxygen.

And, of course, more oxygen means more energy.

That can mean bigger bodies, faster movement.

This innovation set the stage, not just for fish,

or for elephants, but also for you and I.

We tend to think of gills as a fish thing,

but once they were pretty much everyone's thing.

Every amphibian...

reptile, bird,

every mammal alive today descended from ancestors with gills.

So, if gills were such a good idea,

why did so many of us ditch them?

Well, inside this fish is a clue to one of evolution's boldest leaps.

Look at this extraordinary animal.

This is protopterus aethiopicus and it's no ordinary fish.

I mean, superficially it looks like an eel.

It's got this long dorsal fin running all the way

back down to this very spatulate tail here.

Beautiful marbling, but look...

Look at these wiggly limbs that are emerging.

Two at the front here, and two more at the back.

Frankly, what a weird-looking animal!

But I'm dodging the big issue.

What makes it special is that it can live in very stagnant water,

water which is almost devoid of oxygen,

and it can do that because it's a fish with a secret.

Now, it is very, very slimy...

If I can try and pick it up...

I've got to watch my fingers, because it's well-armed

with powerful, crushing teeth.

Whoop! Come on.

What a slippery customer.

I just want you to be able to see its mouth,

because it's through that mouth that it's able to draw

in deliberately deep gulps of air, into a blood vessel lined sac

where the oxygen can diffuse

directly into its circulatory system.

There!

Protopterus aethiopicus, that's its scientific name,

but that adaptation gives it its common name.

This is not a fish out of water, so much as a lungfish on land.

This air-gulping ability first evolved in fish 400 million

years ago, as a simple backup plan for low oxygen water.

But lungs would become key to one of evolution's giant leaps...

the leap on to land.

We're jumping through time again, a mere 300 million years.

As animals ventured into new territories...

limbs evolved, gills disappeared...

bodies transformed.

But we're picking up the elephant's story...

...at an evolutionary crossroads.

In the age of the dinosaurs,

life had gone truly XXL.

The largest animals to ever walk the Earth.

But the ancestor of the elephant has stayed stubbornly small.

This tiny fuzzball is an early Afrotherian.

It's got a long way to go before it can tower over the Savannah,

but its small size is about to pay off.

A rather large lump of rock is coming.

Time's up for the giant dinosaurs.

Mass extinction events don't go well for large animals.

They need too much food when there's not much about,

they're slow to reproduce,

they simply can't bounce back quick enough.

In order to survive, you need to be resourceful, adaptable,

but above everything else, you need to be small.

A bit like this little chap here.

Where is he? Here he is.

Look at that.

That is a tree hyrax.

It's about four or five months old.

What a little beauty!

This tree hyrax is a hand-reared orphan,

allowing us to get an insight into what the elephant might have

looked like before it bulked up...

because, believe it or not,

the hyrax is one of the elephant's closest living relatives.

OK, he's coming, albeit slowly. Come on.

What about that?

I'm tempted to use the "c-word". I mean, he's undeniably cute.

Look at the size of those eyes.

After the asteroid impact, it would

have been mammals of this size that were left roaming the Earth.

All of the big species would have been wiped out completely.

Hey, come on.

Mind your footing.

And you can see that it's retained some of the characteristics

that helped them survive.

It's nimble, it's cautious, undeniably,

and it knows how to stay out of trouble.

But, you know, that extinction event wasn't all about devastation.

It also offered up a landscape of opportunity,

a complete continent ripe for repopulation.

With no giant dinosaurs for competition...

Africa was an empty stage for evolution to run riot.

The plants waste no time bouncing back.

But the ancestor of the elephant remains small and furry.

To get big, it needs food and lots of it.

But the hard part isn't finding dinner.

It's eating it.

Plants must be easy to eat, right?

After all, they can't run away,

they can't fight back and they are everywhere.

Well, not exactly, because obviously,

plants don't want to be eaten.

So, whilst they can't fight or claw their way out of trouble,

they have come up with a formidable range of defences, which

means that all of this greenery here is almost impossible to eat.

For the ancestors of elephants, plants posed a serious challenge,

not just because of thorns or toxins, but what they're made of.

Even modern mammals struggle to digest them.

Whose poo?

Well, those of you with horses and ponies will probably get this.

This is zebra poo.

Look at that.

We don't have too much time to admire it from the outside,

let's delve in straight away.

If I take this piece here, look at that!

It looks like grass clippings.

So, this has been nibbled, it's been munched,

it's gone through the stomach, all the way through the gut of the

zebra, and yet it's barely digested, and that's because the bulk

of the material that you can see here is something called cellulose.

It's the tough stuff that gives plants their strength and rigidity.

But think about it.

If a contemporary, complex,

specialised herbivore like a zebra can't properly digest this

stuff, what chance would those early mammals have?

In truth, we are not certain whether the ancestors of the elephant

made the leap to plant eating before or after the extinction event.

The fossil record is patchy...

but we do know the leap happened

thanks to an unlikely alliance...

Not with the bugs it was hunting.

With something much smaller.

You see, inside the elephant's ancestor,

an invisible army of single-celled microbes is assembling.

It's not an invasion,

it's the start of a vital partnership.

My goodness! Who says size is not important?

This is not a termite mound, it's a termite monument!

It's got to be five metres tall!

Termites are famous for eating wood and other plant material,

but in truth, that's not the whole story.

They do the chewing, it's other organisms that do the digesting.

Inside termite mounds, we find one of nature's strangest team-ups.

Now, Chris Packham, a bloke who loves animals,

why is he smashing up a termite mound?

Well, I've thought long and hard about this.

Firstly, they're extraordinarily resilient animals,

they'll rebuild this really quickly.

And the second thing is that every night, all over here,

animals will be breaking into them.

Just consider me the human aardvark.

Besides, what I'm looking for is just under the surface.

There are plenty of termites here, but I'm looking for something else.

Ah!

Another life-form lives here.

I think this is it.

Small, silent...

Oh, yes, it is!

and surprisingly useful.

Look at that!

That is termite fungal comb.

Now, the interesting thing about this fungus is that you can

only find it in termite mounds, nowhere else in the world.

You see, the termites sort of farm it.

They go out and they collect all that dead plant material,

which they can't digest themselves, and then they come back

and give it to the fungus.

The fungus does digest the cellulose,

and then turn it into substances which the termites can eat.

What about that?

And, of course, it's not just termites.

Almost every plant-eater you can name has outsourced digestion

to microbes.

The only difference...

most keep their microbial munchers safely tucked away inside their gut.

Just as our bodies evolved, these sorts of partnerships evolved.

It's difficult to know when, though, because we don't have any

fossils of prehistoric animals with bacteria in their guts.

But one thing we know for sure, and that is that over millions of years,

many species have become dependent on these sorts of relationships.

Without them, they would simply die.

Sometimes, evolution's boldest moves aren't physical adaptations,

they're partnerships.

And now, thanks to its microbiome,

it's a good time to sample the salad bar.

Generation by generation,

the gut balloons into a fermentation factory...

filled with trillions upon trillions

of plant-munching microbes.

Just what you need for a plant-based diet.

And less than 20 million years later...

we get this charming creature, an early proboscidean...

now standing at a respectable one metre tall.

But evolution has hit a problem of its own making.

This proboscidean has elongated front teeth.

Great for snagging vegetation...

but big teeth can have drawbacks.

This is the skull of an adult hyrax.

It's got these massively oversized incisors there.

What are those teeth for?

Well, for seeing off predators, things like snakes and eagles,

for displaying to other hyrax, and, if they cross the line,

for seeing them off too.

But we've got to remember that this is a herbivorous animal.

How's it going to be nibbling leaves with these in the way?

Well, it's going to struggle, and I can demonstrate

that by adapting my own teeth with some elongated

incisors of my own, and then try and tuck into a hyrax salad.

Frankly, it's just not working.

So, look, whilst big teeth can be impressive, and they certainly have

their uses, if you're a herbivore, they can represent somewhat

of an evolutionary challenge when it comes to grabbing your grub.

Big front teeth come with trade-offs.

For the hyrax, it means eating food through the side of the mouth.

But with the proboscideans,

evolution went down a different path.

One individual was born with a slightly longer nose.

It's the beginning of something special.

There they are. There they are.

To see what a flexible face can be capable of,

we need a snout specialist.

It's like being a lion, isn't it? Going out warthog hunting.

Graceful? Not really.

These are animals built for getting the job done.

Warthogs...

So ugly that they've crossed that line back into being beautiful.

But we're not here for a beauty pageant, we're here for biology,

so let's concentrate on their noses, a remarkable multi-tool.

Warthog noses aren't just for sniffing snacks.

They're for digging roots, and manoeuvring food into place.

It's tough, it's not a delicate nose like ours.

It's really robust.

But even the best nose has its limits...

especially when your food is on the ground, and your face isn't.

The thing is, when you see them standing up,

they've got quite long legs and short necks,

so how do you get your nose down closer to the ground?

Well, you do it like that -

kneeling down.

OK, so technically these are the creature's wrists,

but either way, it's a brilliant example of evolution

solving a problem of its own making.

Certainly an effective solution, but it's not the only way

of meeting that challenge of getting your nose closer to the ground.

But there was a creature that lived millions of years ago that

met the challenge in a completely different way

and came up with something even more extraordinary.

A tool, if you like, that it could use for eating, drinking,

smelling and exploring the world.

It would be the final flourish of an extraordinary evolutionary journey,

a journey that started 4.2 billion years ago with

a single cell that multiplied...

and grew in complexity...

gained a body...

took a deep breath,

and jumped onto land...

before teaming up with microbes, giving it the guts to go vegan.

And now, after countless generations...

the nose gets longer...

stretching down to the ground, giving better access to food,

so the body continues to grow...

until we get an animal of mindboggling complexity

and size that you might just recognise.

Meet Paleomastodon.

It's got the trunk, it's got the tusks.

Big ears? Still a work in progress...

...but it's a body shape we might finally call an elephant.

And evolution didn't stop there.

From creatures with bizarre jaw extensions...

others with downward-curving tusks...

and, of course, those icons of the Ice Age, the mammoths.

Giant proboscideans once spanned the globe.

Africa, Asia, Europe

and South America.

We have evidence of our relationship with proboscideans

from all over the world, in the form of these carvings and paintings.

These were not just creatures that were living in that landscape.

We evolved alongside them.

Our histories are uniquely intertwined.

Some proboscideans were lost to natural climate change,

but for others, it was the actions of our own ancestors.

Today, just three species of proboscidean remain...

each emerging within the last 10 million years -

the Asian elephant...

the African forest elephant...

and, the biggest of them all,

a grass-eating giant shaped on the open plains...

the African savannah elephant.

Remarkable!

Aw, you're wonderful, aren't you?

Let's take one last look at these incredible creatures.

Made up of a million billion cells, powered by the largest lungs

of any land animal, and in there, a gut coiled up, 20 metres long,

packed full of microbes so it can digest all of this plant material.

And then look at the front here, these tusks, and between them,

this extraordinary, modified nose, its trunk,

strong enough to pick up and carry a human,

delicate enough to pick up a penny.

The evolutionary journey that created the bizarre

and beautiful elephant is just one story.

Because, thanks to LUCA, that single-celled

Last Universal Common Ancestor,

we are all part of an ancient family.

A family that may be bad at keeping in touch,

and may be a little dysfunctional,

but is always undeniably miraculous.

Look at this!

I'm literally leading a group of elephants through the forest.

Who would have ever thought it?

Every living thing, everything that's ever walked,

swum or flown is all connected in that one tangled story, connected

by that thread that runs through a four billion year tapestry of life.

Evolution is messy, evolution's unpredictable and so grand,

we're still really figuring out how it works, but there is one

thing that we do know, and that is that given time and the resources,

it comes up with creatures that are as remarkable as this.

And we should cherish all life on Earth, not neglect it or

destroy it, because evolution is wonderful,

life is beautiful.

♪ You're such a

♪ Beautiful freak

♪ I wish there were

♪ More just like you... ♪

Next time - how the ostrich got the biggest egg on the planet...

It's quite emotional, if I'm honest with you!

a four billion year love story...

from the first sex...

to conquering the land.

An incredible journey of flirting...

feathers

and fornication...

giving rise...

Look at this!

to one of the most extraordinary birds.

But first,

how do we know that all life on Earth has a common ancestor?

For centuries, fossils have provided a window into the past,

helping scientists reconstruct the tree of life.

In the past, our understanding for how a fossil fits in this

larger system of life on Earth was comparative anatomy,

and it worked for a long time, and it was a beautiful tool.

Scientists would look at what animals or other organisms

had in common, or didn't have in common,

to try to recreate their evolutionary relationships.

I think one thing we have to bear in mind is

when we look at fossils, we're looking at just the remains,

what is left behind, and it's not always complete.

So, it's like trying to reconstruct a hand from a fingerprint.

- And we made lots of mistakes. - LAUGHS

But in the middle of the last century,

a discovery changed everything.

The appearance of DNA really was a game-changer.

We couldn't study the tree of life with just comparative anatomy.

You need DNA.

We can compare genes to each other, compare those gene sequences

to each other, look at the letters that those genes contain,

and use that information to try to figure out how different

organisms are related to each other.

By analysing DNA, scientists have discovered that some

creatures that look very different

are actually closely related,

like the Afrotherian mammals.

And it's also allowed us to trace the tree of life back further

than ever before, all the way to its root.

- - LUCA. LAUGHS

The Last Universal Common Ancestor to all life on Earth.

It's the last organism that we can point back and say, "This is

"a relative of not only us, but bacteria and elephants and bananas."

I love thinking of LUCA as being not just my

great-great-great-great-great-great- whatever grandparent,

but everybody's great-great-great-great-great- whatever grandparent.

In a landmark study, scientists analysed

the DNA of 700 different microbial species, searching

for patterns that would help them reconstruct LUCA's genetic code.

Our ability to sequence DNA really has unlocked our ability to

look deep in time to 4 billion years ago

and come to a better understanding of what

our Last Universal Common Ancestor may have looked like.

The study revealed that LUCA was likely to have had

over 2,600 genes, making it surprisingly complex.

So, it wasn't necessarily the first form of life.

It almost certainly wasn't, but it's the one that got by.

From that one spark, we see the origin of all the life that we

see today in its incredible diversity.

Realising that we all came from LUCA,

the same seed of the tree of life, is really humbling to me.

It's a way of thinking about the world

in a much more connected way.

We all came from the same place.

We've not only expanded our understanding of the tree life, but

it's changed our understanding of where we fit into the tree of life.

Do you want to know how an elephant is related to a clownfish?

Discover more in a poster from the Open University on the tree of life.

To get your free copy, scan the QR code on screen, or ring...

or visit...