I've come here to Southwestern France to the Pyrenees and then
deep into a mountain, more than half a kilometre
through a labyrinth of damp and dark caves,
into this enormous and remarkable cavern.
But I've come here to show you something very special.
Look at this.
No less than eight bison...
..drawn on this cave wall.
Absolutely beautiful.
But it's not just these bison. Have a look at this panel over here!
Here, we don't just see bison - we see primitive horses, tarpan.
And look there, a Pyrenean ibex.
Absolutely sensational.
Now, I've stood in art galleries all over the world looking at art,
but this is the oldest I've seen by far.
And possibly the most beautiful and most moving.
The drawings of these animals are so fresh,
so accurate, so beautifully made.
For me, this is about being human.
This is about our history.
The cave paintings are the culmination of a story
that began long before the first humans set foot on Earth...
..deep within our planet's past...
LOUD EXPLOSION
..when the world of the dinosaurs...
..was destroyed...
..making way for the rise of the mammals.
It's a tale of turmoil and upheaval,
of millions of years of climate swings
from one extreme to another.
Until, out of the chaos,
our species was born.
A species capable of creating art
on a cave wall in Southern France.
Now, we think that these were drawn around 13,000 years ago.
And that's significant because it constitutes a turning point,
not just for our species, but for the planet,
because we were going on to be a significantly powerful force,
capable of transforming and reshaping the Earth.
In the time since the cave paintings were done,
we've radically altered life on the planet...
..in ways our ancient ancestors could never have imagined.
And so we've reached a unique point in our planet's
4.5 billion year history, when an intelligent species,
with a clear understanding of the Earth,
is transforming it at an incredible speed.
And that species is, of course, us.
66 million years ago,
one form of life dominated the surface of the Earth.
DEEP GROWLING
Dinosaurs.
These magnificent creatures, amongst the largest that have ever lived
on Earth, had reigned supreme for around 150 million years.
They had evolved into many hundreds of species,
spread across every continent on the planet.
But all that was about to change.
What a wonderful place, packed full of life.
I've just been looking up into the forest here.
Tanagers, aracari, orioles -
a mass of species.
Now, of course, all of them are individually beautiful.
But, for me, it's when they form that complex web,
when they knit together to form a dynamic, harmonious,
functional ecosystem that things become even more beautiful.
But I've got to say, of course,
that none of these species were predestined.
They weren't "meant to be".
In fact, they were only here because of a single, freak, chance event.
An event of unimaginable violence
and astonishing destruction.
I'm talking, of course, about that day 66 million years ago
when the asteroid struck the Earth.
You know the one -
the one that's said to have wiped out the dinosaurs.
Now, there has been lots of debate about exactly
what killed the dinosaurs.
Since the 1980s,
scientists have believed the main culprit was an asteroid...
..from the far reaches of the solar system,
the size of Mount Everest...
..and on a collision course with Earth.
An extraordinary claim requires some extraordinary evidence
and, let's be clear, claiming that a six mile wide asteroid
crashed into the planet, unleashing the power
of a billion nuclear weapons is an extraordinary claim.
So where is the evidence?
Where is the smoking gun?
Well, I'm sat in it.
This is called a cenote.
It's a word that comes from one of the Mayan languages.
It literally means hole in the ground filled with water.
Now, take a look at this map of this part of Mexico,
the Yucatan Peninsula.
When I superimpose the cenotes, you see there's an enormous
number of them, the landscape is completely freckled.
But then look again in more detail.
You see this here?
There's an arc of these geological features running across here.
And if we complete the arc, turning it into a circle,
it has a diameter of 110 miles, which corresponds perfectly
with the inner rim of the crater made
when the asteroid struck our planet.
Now, the cenotes weren't formed at the time.
Over millions of years, that impact seems to have weakened
the rock here.
Water has leached through it, forming cave systems,
which have collapsed in some places, giving us this ring of cenotes.
HIGH PITCHED BIRD CALL
A devastating remnant of the asteroid strike...
..that brought the reign of the dinosaurs to a crashing end.
SHARP, LOUD BLAST
DEEP SCREECHING
LOUD RUMBLING
THUNDERING BOOM
The blast annihilates everything within its reach.
Earthquakes and tsunami tear across the planet.
And then it begins to rain.
Not water...
..but scorching hot rock...
DINOSAUR ROARS
..made from the asteroid and the bedrock it had struck.
ANGUISHED ROARS
Truly one of THE worst days in Earth's history.
DINOSAUR ROARS
But was this cataclysm enough to kill the dinosaurs
all over the planet?
For a species to become fully extinct,
every member of that species has to die and not be replaced,
and not just in a small area or even over a continent,
but over the entire world.
That's what extinction's really about, that's what it entails.
And generally, it's not a dramatic process, it's a slow burner.
Have a look at this.
In my bag here, I've got the skull...
..of an ornithomimid dinosaur -
one of a group of dinosaurs.
These creatures looked rather like giant ostrich
and they could run really fast.
But the key thing is that these ornithomimids can be found all over
the world in the fossil record.
So how did they become extinct?
Well, those that were unlucky enough to be living within the blast radius
of the asteroid, the answer's simple -
they just vaporised instantaneously.
LOUD, DEEP BLAST
And those living a little further away,
say within thousands of miles,
well, it's likely they were killed by the aftermath effects
of that strike.
Things like earthquakes, tsunamis,
the glass rain and the forest fires.
But what about the ornithomimids that were living, say,
on the other side of the world, as far away as possible
from the immediate carnage that was caused by that asteroid?
How did THEY die?
Well, something else was needed to cause the worldwide mass extinction.
DEEP RUMBLING EXPLOSIONS
To seek answers to this puzzle,
scientists have drilled deep into the asteroid crater.
The samples they've retrieved reveal important clues.
Such as the fine-grain debris churned up by the powerful tsunami.
As well as rocks like granite, melted by the incredible temperature
and pressure created by the impact.
But, crucially, one type of rock that's known to exist in this area
is missing from the place where the asteroid hit.
This is anhydrite.
Now, I know what you're thinking.
You're thinking this is a rather boring, grey rock.
But what's important is that it contains large amounts of sulphur,
and this is the final piece of our extinction jigsaw
because, when the asteroid struck, it vaporised this rock,
releasing no less than 300 billion tonnes of sulphur
into the atmosphere.
Today, there's virtually no trace of anhydrite in the seabed
within the crater...
..because it was all blasted into the air...
..merging with ash and dust to form a vast, grey cloud...
..sweeping across the entire planet.
With the cloud blocking out most of the sunlight,
temperatures plummet by around 20 degrees.
But the extreme cold isn't the only killer.
In the dark, twilight conditions,
plants struggle to photosynthesise and wither away.
And with virtually no plants to eat, the food chain collapses.
Many dinosaurs starve to death.
When it came to the dinosaurs, only a handful hung on to evolve
into the 10,000 or so species of birds that we have today.
Three quarters of all animal and plant species simply disappear.
This was one of the worst extinction events our planet has ever seen.
And yet, for our world to emerge,
there needed to be some survivors.
And most importantly from that branch of life that we belong to...
..the mammals.
What a place.
It's not representative of humanity's greatest attributes,
is it? It's a mess.
An apocalyptic landfill,
screaming of waste and consumption.
I suppose the one thing we can say is,
"Look, nature's always fighting back, isn't it?"
Look at the plants here and, out there, a whole host of wildfowl.
But let's stick with the mammals
because 66 million years ago they didn't all become extinct
and this is actually quite a good place to find a modern creature
that shares some real characteristics
with those early mammals,
and I happen to have a very friendly one inside my jacket.
What do you reckon?
I'll show you.
Yes! The rat.
Now, I'm rather partial to rats, I've got to say.
Just look at those whiskers.
Those lovely bright eyes.
But you might not be quite so enamoured
when I tell you that our ancient ancestors shared significant
similarities with creatures like this rat.
So what was it that they had that the dinosaurs didn't?
Well, many of the dinosaurs were quite specialised.
The herbivores required very particular species of plants to eat,
the carnivores very particular species of dinosaurs.
But most of the early mammals, they were generalists
and, equally importantly, they were omnivores.
They could eat plant material and flesh.
In fact, they could eat rotting plant material
and rotting flesh, and that was a real asset
when all of that starvation was going on during the impact winter.
So, I have to tell you, that, all of those millions of years ago,
animals like this represented hope.
And the world that we know today was resting on the shoulders
of creatures just like this rat.
I like that.
Yes, down to you!
It's thought the extreme cold conditions
lasted for more than ten years.
But eventually the sky cleared,
the sun shone down
and life could begin to make a recovery.
For more than 150 million years,
the mammals had been living in the shadows of the dinosaurs.
But now a new chapter could begin.
The age of mammals.
And it would be Earth's geological forces,
rather than an asteroid, that would change the course of life.
Deep within the North Atlantic Ocean,
thousands of hydrothermal vents begin to release
vast quantities of greenhouse gases,
including methane,
a gas around 25 times more potent than carbon dioxide.
THUNDERCLAP
This methane escapes into the atmosphere,
sending temperatures rocketing and triggering rapid climate change.
Violent storms ravage the planet with flash floods...
..and protracted droughts.
This dramatic global warming has profound implications
for the ancient mammals.
BIRDS TWITTER
Look.
Millions of bats.
Millions of mammals.
I can smell them, I can see them,
I can hear them and I can feel them.
There are so many bats out there whirling around
that it's actually generated a breeze,
which is very pleasant given how sweaty I am.
And it's ironic, isn't it, that, just when the planet
was going to see the rise of mammals,
which would ultimately give rise to species like our own,
it was also going through what can only be described as
rapid climate change?
And I can show you that here with this graph.
Now, the Earth was already a few degrees warmer at this time,
but look at this spike.
What this tells us is that, within the space of just
a few thousand years, the global average temperature rose
by five degrees Centigrade.
Incredible but sobering,
because climate scientists today go back through the geological record
and they use this spike as an analogue
for what might be happening to our atmosphere today.
And what really concerns them is how this happened.
What's scary is that it was precipitated by a series of events,
each triggering the next, triggering the next, triggering the next,
until it pushed the Earth past some serious tipping points.
And that is our nightmare.
Scientists believe that 56 million years ago
the hot conditions on Earth led to a very different world.
In the Arctic, where temperatures averaged around 23 degrees,
alligators could be found swimming under palm trees.
But despite this havoc, this hothouse Earth
seems to have had a silver lining.
Because, thanks to the warmer conditions,
subtropical forest or jungle has moved away from the equator
and expanded across much of North America, Europe and Asia.
And this rich, lush habitat would prove to be crucial
to the emergence of new species of mammal.
Ones more like us.
Wow!
Just look at that.
What a landscape.
This is the Calakmul Biosphere Reserve in Mexico
and, with its 2,700 square miles of forest,
it's one of the largest forest reserves in Mexico
and Latin America.
And aside from these Mayan ruins on which I'm standing
and a few other pockets of development, there's very little
human activity here, which means it's packed full of wildlife.
More than 400 species of birds -
toucans, trogons, parrots and tanagers.
And it's not just birds.
Hiding in the forest here are all sorts of other natural wonders -
ocelot, puma, monkeys,
enormous numbers of bats,
not to mention a host of reptiles and amphibians.
So, the question is, why is this place such a biodiversity hot spot?
Now, it's partly due to the vast diversity of plants
that we have here.
We think that in this area alone there are more than 1,500 species.
But it's not just that.
It's also down to something that we very much take for granted.
Have a look at this fossil that I've got here,
and in particular this tiny star-shaped structure.
That is a fossilised flower.
And we know from where this rock came from, in Utah in North America,
that that means that this flower bloomed
around 51 million years ago.
That is incredible.
Flowering plants are one of the great drivers of biodiversity.
And 56 million years ago, Earth's flourishing forests
were full of them.
For insects, flowers offered food in the form of nectar
to tempt them in to spread the plant's pollen for fertilisation.
But for other creatures, there was an even juicier prize.
Something they can eat that helps disperse
the plant's fertilised seeds.
One of the plant kingdom's great gifts to life.
Fruit.
First eaten by birds many tens of millions of years earlier...
..the fruits of the forest were to play a key role in the
evolution of a new type of mammal revealed in the fossil record.
Fruit offered both a reward and a challenge for mammals.
Now, the reward is that this is a perfectly formed capsule
packed full of calories.
The challenge is you've got to find it
and then you've got to be able to get it, and in a forest environment
like this that's actually quite difficult.
To find it, you've got to be able to see it
and then identify that it's ripe.
And once you've done so, you've got to be able to reach it,
which means that you've got to be able to climb all the way up there,
20, 30 metres or more.
So what creature could have possibly evolved
that could take advantage of this fabulous resource?
Maybe something like that.
And that is a Geoffroy's spider monkey.
Quite a rare animal these days.
But the key thing is that this animal shares significant
characteristics with those first true primates that arose
56 million years ago.
Look at them, they're beautiful, if not a little weird.
They're highly specialised, but look at the head.
Their eyes are forward-facing, like ours,
good for stereoscopic vision, good for spotting fruit.
They've got a relatively big brain, so they can remember where
they previously found that fruit, but the key thing are the limbs.
Look - long and strong.
And if you look very carefully there,
you can see their hands are like hooks.
And their fifth limb, that prehensile tail,
it's so strong they can hang from it
when they're eating fruits like this.
There's no denying that creatures like this are perfectly adapted
for the high life up there at the top of the forest.
Now, we're not entirely sure where the world's first true primates,
our ancestors, appeared because as soon as they evolved
they started spreading rapidly around the world,
between North America and Asia and on into Europe and Africa.
These primates, they were having the time of their lives,
and very rapidly they'd occupied no less than four
of the world's continents.
They were making it look easy and at this point
it seemed as if the Earth was destined to become
a planet of the apes.
But it wasn't to be.
After more than 20 million years of a hothouse Earth...
..the planet's climate dramatically cooled.
Scientists aren't entirely sure why it happened,
but the result was devastating.
Across the northern continents,
the cooler, drier conditions decimated the jungle.
Destroying much of the habitat of our ancient ancestors.
Sadly, we've been conducting our own perverse experiment
into what happens if you deforest the planet.
This is just one of a multitude of sites all over the world
that have been destroyed.
Until recently, this would have been tropical forest -
lush, green, filled with masses of mammals,
monkeys, tapirs, jaguar.
But they're all gone.
You see, habitat destruction like this
is probably THE leading force when it comes to extinction today,
and it was no different 34 million years ago.
When the tropical forest disappeared from the northern climes,
there were severe consequences.
The primates disappeared from North America completely
and all but disappeared from Europe.
So, on the face of it, this looks like a massive tragedy,
a severe setback for our ancient ancestors.
Or was it?
Because, if the story that we're really telling is the story of us,
Homo sapiens, humans, then it's not that simple.
The path of evolution that would lead from those ancient ancestors
to a creature like us, an upright, bipedal, big-brained ape
with opposing thumbs, was never going to be straight-forward.
For evolution to come up with something like the human species,
it would require a very precise and complex series of events,
and it would need to occur in a very specific environment,
where evolution could be nudged, if you like, towards the human species.
And it would be down to the Earth to create that very special place.
Although primates had mostly disappeared from the cold,
dry, northerly continents...
..in East Africa, where the jungle still remained,
they had survived.
And here, the planet's forces began to shape a new environment.
From deep within Earth, hot magma started to rise up,
lifting the ground and forming large cracks on the surface
as, over millions of years, the continent pulls apart.
It forms the spectacular East African Rift Valley.
Running some 4,000 miles through what will become
Ethiopia, Kenya, Tanzania and Mozambique.
And crucially, with its patchwork of forests and savannah,
it presents the primates with a dilemma.
ENGINE PUTTERS
So what was the dilemma?
Well, the first thing you have to appreciate is that the
Rift Valley in East Africa was no longer a single, great,
vast tract of tropical forest.
It had become fragmented into smaller pockets of forest,
quite analogous to this rather beautiful park that I'm sat in.
So these represent those pockets of forest and the paths in-between
the grassland that had formed between them.
Now, I want you to imagine that you are a highly arboreal,
tree swinging, fruit eating primate
and you've had your breakfast here at point A,
but your lunch is over there at point B.
How do you get between the two?
Because in the old days you could simply swing from tree to tree.
This was the dilemma facing those early primates.
The forest had fragmented, so had their food supply,
and they had no efficient way of getting from A to B.
So, what was the solution?
What did evolution come up with?
Well, some of those early primates decided to stick it out in the
shrinking forest and they evolved into chimpanzees and gorillas.
But another group, our ancient ancestors,
started to do something that we take for granted
but we have to learn to do.
What do you reckon?
I'll tell you - they started walking on two feet.
But our early ancestors didn't just walk out of the forest
never to return. They still spent a lot of time there,
probably even sleeping in the trees.
But walking gave them freedom
and with that freedom came the ability to hunt,
so they started eating meat and then they evolved bigger brains.
And that's why the Rift Valley in East Africa
is known as the Cradle of Humanity.
Now, initially, there were quite a number of human species.
But the key thing is that that is where our species,
Homo sapiens, evolved.
Now, the origins of our species are still shrouded in mystery.
But the East African Rift Valley is where scientists
have discovered many of the most important fossils...
..that tell the incredible story of human evolution...
..and the emergence of Homo sapiens
around 300,000 years ago.
With hindsight, we simply have to marvel at that remarkable
set of factors that came together to produce that highly unlikely
chain of events.
The seemingly impossible had happened.
After the best part of 66 million years,
after continents tearing themselves apart,
mountain ranges forming, the Earth's climate fluxing
and throwing between hot and cold,
a new force was about to be unleashed upon the Earth.
Humans had arrived, and there was no turning back.
Yet whilst our species had been evolving in the warmth of Africa...
..Earth's climate had continued to cool.
Scientists think that part of the reason may be down to Earth's
new mountain ranges -
the Himalayas, Andes and Rockies.
They had formed over tens of millions of years
as the result of plate tectonics pushing up the Earth's crust.
And through the process of weathering,
the exposed rock was reacting with carbon dioxide,
removing it from the air and causing temperatures to drop.
It meant that, as humans migrated out of Africa into Europe,
Asia and Australia, the extreme cold, dry conditions
prevented them from crossing into North America.
Earth was in the midst of an Ice Age.
And yet, despite the extreme challenges
we faced from the climate, it was around this time that humans
began to create something that had never existed on Earth before.
Art.
The oldest that we know of is this painting of a pig in Indonesia,
and it's been dated to around 45,000 years ago.
And closer to home in Europe,
we find cave paintings from more recent periods.
Here we are, back in this spectacular cave
with its remarkable drawings.
They are so, so beautiful that it's worth taking a moment
to think about what's going on here.
Well, around 13,000 years ago,
humans of the same species, exactly the same species as us,
were standing or crouching here in the flickering light of their lamps,
making these beautiful, beautiful drawings.
But what's it about?
Well, art is always about communication.
And this isn't just communicating to me about their intelligence
or their creativity - there's something else going on.
And it's interesting to note that in cave paintings of this age
humans are very rarely depicted.
It's always about nature.
And at this time, all of these species were wild animals.
We were still hunter gatherers, we were in tune with,
connected to and, critically, part of nature.
But for us to go on to become the global force that we've become,
things would need to change.
Our population would have to grow massively
and to achieve that we would need to control nature.
The extreme cold and dry conditions of the Ice Age
were not destined to last.
Subtle changes in Earth's orbit altered the amount of sunlight
reaching the planet's surface.
And together with increasing levels of carbon dioxide,
this pushed up temperatures...
..melting the ice.
For the first time, humans spread across North and South America.
We were now living on every continent except Antarctica.
And it was around 11,000 years ago,
in this warmer and more humid climate,
that humans did something simple but revolutionary.
They began to farm,
first growing crops, then raising livestock.
Within a few thousand years,
nearly all human societies on the planet were farming.
And slowly but surely,
producing food became an industrialised process
with an ever greater impact on Earth's ecosystems.
This is a vast field of soya beans,
stretching all the way to the horizon where the forest remains.
And many people think of this as a natural environment,
but it couldn't be further from natural if it tried.
This is the antithesis of biodiversity.
Now, imagine biodiversity is a rainbow
and the spectrum represents the full breadth of beautiful life
and when we're looking at this
we're looking at a tiny slice of one colour.
All of these regimented rows here are just one species.
This is a monoculture.
And it's not just that because the conditions that this crop
require to grow weren't here naturally.
This has been flattened, it's been drained, it's been fertilised.
It's been smothered in pesticides to keep nature out.
Now, forgive me, because for just a moment
I'm going to take on the difficult role of devil's advocate.
Imagine that we could put all of those environmental issues
to one side and take a fresh look at this.
We might consider it to be remarkable
because it's highly efficient crop production like this
which is producing enough food to cater
for our ever increasing human population.
You might say that our ability to invent technologies
and come up with a food production system that can feed
around eight billion people and keep many of them
out of starvation and famine is an incredible achievement.
But I can't forget those environmental issues,
certainly when I tell you that 40%
of the world's land surface that isn't frozen
is now given over to agriculture like this -
bland monocultures devoid of life.
And also, I can tell you that, of all the mammals alive at this point
on planet Earth today,
only 4% of them are wild animals.
96% are humans, their pets
or domestic farm animals.
And that, from my perspective, is terrifying.
But our takeover of the natural world
goes far beyond industrial agriculture.
Humans now have a greater effect in shaping the Earth's surface
than many natural processes.
And human-made materials, like concrete and plastic,
outweigh the combined biomass of all life on the planet.
Behind all of this is the staggering increase in the human population.
From one billion just a couple of hundred years ago...
..to eight billion today.
Welcome to the human planet.
Now, it is awesome but for me it's not wondrous
because, hand on heart, this is not my sort of environment.
I mean, there is some nature here,
but most of it is entirely artificial.
Most of what I can see is made of brick, concrete, steel and glass.
This is Mexico City,
and together with the 59 districts that radiate out to the horizon
it occupies 3,000 square miles,
and it's home to more than 21 million people.
And, staggeringly, it's not unique.
There are more than 30 other megacities across the world
with more than ten million people living in them.
But standing here looking at all of this you've got to ask,
"How can it possibly work?"
One thing that we have to acknowledge
is that agricultural revolution,
our ability to produce food with brutal efficiency.
That's what feeds all of us living in these megacities.
But there's another far more important ingredient,
something that was formed by the Earth and life
hundreds of millions of years ago,
something that we've drilled for and mined for.
I'm talking about coal, oil and gas -
the fossil fuels.
That's what's powered the technology that's allowed us
to build these megacities.
But it comes at a terrible cost
because, as we continue to burn those fossil fuels,
we are pumping CO2 into this atmosphere
at a rate that's comparable with some of those volcanic eruptions
that occurred millions of years ago.
And critically...
..we've started to radically transform our climate.
For most of Earth's 4.5 billion year history,
the most dramatic changes in climate...
..have been driven by asteroids...
LOUD BLAST
LOUD RUMBLING
..the powerful tectonic movement of the continents...
..and the catastrophic eruptions of volcanoes.
BOOMING EXPLOSION
Of course, as we've seen,
there have been moments when life too has had a profound impact.
Like the bacteria that colonised the oceans 2.4 billion years ago...
..and gave us the oxygen we breathe.
Or the swamp forests that sent temperatures spiralling downwards
and created the coal we now burn.
But today, the climate is changing at a faster rate...
..than at any time in the last 66 million years.
Now, I've seen so much of the natural world that I cherish
destroyed that it's difficult not to be pessimistic.
But, ironically, when I go searching for hope,
I don't turn to those planetary forces.
I turn to the power of humanity
because, for all of our flaws, all of our foolishness,
we are a truly remarkable species.
Adaptable, resourceful,
inventive, intelligent, creative.
And you might argue that our most significant turning points
were perhaps standing up on two legs and beginning to walk
or drawing those animals on the cave walls or inventing farming,
or even landing on the moon.
But I need to argue that these were just our dress rehearsals,
because in the very near future our species will need to reach
the zenith of its achievements and that all humanity will have to learn
to put our Earth first.
That unique, fragile, beautiful Earth
that for more than four billion years has been forming this stage
on which we now stand,
and it's waiting for our finest performance.
And if we don't pull it off,
then of course life on this planet will continue to prosper.
But there will be no encore for humanity.
If the Earth could talk, what would it tell us?
Well, the Open University imagine how it might answer
some of our questions.
To experience this interactive presentation,
go to the website on the screen
and follow the links to the Open University.