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There are some great questions
that have intrigued and haunted us

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since the dawn of humanity...

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The story of our search
to answer those questions

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is the story of science.

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Of all human endeavours,
science has had the greatest

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impact on our lives,

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on how we see the world
and how we see ourselves.

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Its ideas, its achievements,
its results are all around us.

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So, how did we arrive
at the modern world?

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Well, that is more surprising
and more human than you might think.

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The history of science is often told
as a series of eureka moments -

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the ultimate triumph
of the rational mind.

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The truth is that power and passion,

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rivalry and sheer blind chance have
played equally significant parts.

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In this series, I'll be
offering a different view

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of how science happens.
It has been shaped as much by

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what's outside the laboratory
as inside.

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Whoa!

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This is the story of how history
made science and science

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made history, and how the ideas that
were generated changed our world.

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It is a tale of...

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This time, the most personal
question we've asked...

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How did we get here?

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It's a question that provokes fierce
argument and huge controversy.

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And that's because it gets to
the heart of our human origins,

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our very significance. And yet,
until relatively recently,

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it was not a question that people
felt they had to keep asking.

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Most people believed
they already knew the answer,

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handed down in religious text
or in creation stories.

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We and everything else on earth

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had been put here by some kind of
supernatural power.

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What's special about this question

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is not how long it took to get
answered, but how long it took

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to get asked as a
scientific question.

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And it's a story that
begins over here.

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'The great voyages of discovery,

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of the 15th Century, heralded
the start of the modern age.

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Advances in navigation
and shipbuilding allowed

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European adventurers to explore
and exploit the rest of the globe.

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We're absolutely storming along now,
powered by the trade winds.

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And over there
is the Caribbean island of Jamaica.

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In 1494,
Christopher Columbus landed here.

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It was a completely
unknown part of the world,

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at least unknown to Europeans.
It is the Americas.

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The discovery of the Americas
sent shock waves through
European civilization.

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New peoples,
new plants, new animals.

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The early explorers arrived utterly
convinced that they were special,

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set apart from the rest of nature.
The pinnacle of God's creation.

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Yet what they found here
would begin to challenge that.

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And for me, the story begins
with a man called Hans Sloane.

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An Irish doctor who arrived in
Jamaica in 1687 to take up

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the lucrative post of personal
physician to the island's Governor.

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To be fair to Sloane, he was
more than simply an adventurer

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in search of a fast buck. He was
also a passionate botanist

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who loved to go exploring the island
on horseback with a guide.

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OK, Marlin, are you ready to go?
Yep. Lovely.

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HORSE BLUSTERS

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Elegantly done.

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Don't want to be left behind.

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My guide, Marlin Beale,
is a botanist.

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And together we're heading
for the Blue Mountains

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where Sloane would come face to
face with what he described as,

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"all that is extraordinary
in nature."

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I know that Sloane was a doctor
and he was particularly
interested in plants,

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which had any sort of
medicinal quality. Yes.

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So if you see any, do let me know.
Definitely, I will.

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'Since most 17th Century
medicines came from plants,

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'it's not surprising that
finding new species

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'was high on Sloane's agenda.'

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A-ha, here we go.

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Smell it. Very pretty.

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Yeah. Taste it, if you want.

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Which end do I taste?

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That end, the cut end.

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That's ginger, isn't it?

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It's wild ginger.

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Interesting, because Sloane wrote
quite a lot about wild ginger.

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He believed that ginger was
very good for the stomach.

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I don't know about that. It's
certainly good for sea sickness.

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If you were doing a two month
voyage across the Atlantic,
this would be useful.

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Sloane also claimed that wild ginger
was good for treating cancers.

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I'm not sure about that either.
Quite tasty though.

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Now, an interest in nature wasn't
confined to collectors like Sloane.

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Because in nature,
and particularly plants,

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lay the foundations
of European imperial power.

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Trading vessels criss-crossed
the globe, bringing home
all sorts of natural produce,

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from tobacco and spices
to tea and timber,

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the botanical booty was
practically limitless.

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Even the ships, which
carried the goods,

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were themselves made out of plants.

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There were trees for the framework,
hemp provided the sails and ropes,

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and they used pine resin
to produce pitch,

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which was used to
waterproof the ships.

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What distinguished Sloane from
most traders and plantation owners

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was an interest in all of nature.
Not just plants but also animals.

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This interest would open the world's
eyes to the beauty of God's creation

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and crucially to the puzzle
of its incredible diversity.

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There aren't very many big animals
here on Jamaica,

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but there are an awful lot of
lizards and what Marlin

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is about to do is make a little
noose I think, is that right?

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Yes. And hopefully we'll
capture a few lizards.

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Is this the sort of thing
that Sloane might have used?

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Possibly, because this would be
the most conventional method
at that time.

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Just tight.

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What we've got to do now is
persuade the lizard to stick its...

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It's head inside. So we've got
our noose. Very neat.

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A beautiful noose for catching
lizards in the style of Hans Sloane.

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Where are we likely
to find them, Marlin?

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Well, we can find some on
the ground or even on trees.

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So, both looking on the
ground and on trees is great.

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'It was this type of
hands on approach...'

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I think there's one over here.

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'..that enabled Sloane to collect
so many different specimens

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'of Jamaican wildlife.'
MICHAEL YELPS

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He jumped. I think he's gone.

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Michael. Have you seen something?

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Yes. This one right, right there,
do you see? Let's have a go.

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Brilliant. Is he safe to hold? Yeah.

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Maybe a bit feisty. So I'm
going to get the noose off of him.

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How many different species
of lizards are there?

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There are many different species,
over 20 different species.

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I think we've done very well. Yeah.

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This book has illustrations of
just some of the things that Sloane

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captured in Jamaica.
A snake there.

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There's our friends, the lizards.

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I think the one I helped capture,
is the one in the middle there.

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The book is just full of
beautiful drawings.

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Birds, fishes...

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The thing is that Hans Sloane
came to Jamaica not just to
revel in its beauty,

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but to record everything he saw,
which he did in enormous detail,
so that other people who

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couldn't come here could enjoy and
learn from what he had discovered.

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After 15 months on the island,
Sloane returned to England.

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He brought back with him
some 800 samples of flora and fauna,

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a fully grown crocodile and
a recipe for drinking chocolate.

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Unlike many explorers who returned
from the Americas with tall tales

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of giant sea serpents and men whose
heads grow beneath their shoulders,

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Sloane returned with real data
and real specimens.

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There was no reason as yet
to think that all this diversity
had anything to do with us.

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But it did unsettle traditional
ideas of God's creation of the
natural world.

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For people who believed that God
had created the world

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and everything in it,
permanent and perfect,

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this was also utterly bewildering.

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Why had God bothered to make
so many small and apparently
pointless variations on a theme?

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Why so many lizards?
Why so many beetles?

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The questions started to come
thick and fast.

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By the time Hans Sloane died
in 1753, he had put together

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the world's greatest collection
of natural objects.

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Most of which
are still with us today.

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In front of me we have
part of the Sloane Herbarium.

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There are many, many
thousands of objects

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about 14,000 of these
vegetable substances.

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Flowers, fruits, dried objects,
which we can't press.

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'And with that there are about
270 bound volumes

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'with many, many thousands
of specimens in.'

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So vast was Sloane's
hoard of wonders

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that it was moved to a new type
of institution

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beginning to appear across Europe.

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The national museum.

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Private collections, like Sloane's,

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could now be seen
by a much wider audience.

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Bringing nature out
of the wilderness and
into the every day world.

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This new curiosity about life
on earth

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would bring us closer to the
question - how did we get here?

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It was fuelled by
voyages of discovery and the
money to be made from nature,

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by obsessive collectors,
like Hans Sloane,

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who began to document
nature's diversity.

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And by museums, where ordinary
people could see it for themselves.

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And it now turned out that
all this life also had a history,
a rather rich one.

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Paris.
Just after the French Revolution.

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Where the belief that God's
creation was fixed and unchanging

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was about to be further undermined
by a brilliant anatomist

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and a taste for new buildings.

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Paris is a city
in love with its own beauty.

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Whatever events may have
been dominating the headlines -

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the fall of the Bastille,
the execution of the King,

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one thing has remained constant -

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the City's determination to build
on its rich architectural heritage.

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Buildings began to appear,
which were every bit as magnificent
as their predecessors.

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'While others were added to.'

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'For example, the Louvre.

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'In the years following
the Revolution, it grew

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'from a Bourbon palace into a
museum large enough to house

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'France's rapidly expanding
art collection.'

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But I'm less interested in what's
in there than what's out here.

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And in particular this stuff -
limestone.

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A rock which for centuries
had been the mainstay
of Parisian architecture.

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Now this limestone was hewn from
a quarry that is very near to
where I'm standing now.

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A hidden one,
one that is down there.

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Deep beneath Paris lies an
old network of stone quarries

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linked by hundreds
of kilometres of connecting tunnels.

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Together they form a mirror
image of the city above,
right down to the street names.

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People began quarrying away
underneath Paris in the middle ages.

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And they went on
digging for hundreds of years.

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There should be a sign
just over here.

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Yes, "3R."

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This is the old
revolutionary calendar

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and it means three years after
the start of the French Revolution.

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At that time,
houses being built over my head

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would have contained limestone
from quarries just like this one.

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Hello.

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00:17:03,800 --> 00:17:07,560
I'm Gilles. It's a pleasure to
meet you. And you.

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I guess actually quarrying down here
must have been pretty dangerous.

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It could be dangerous.

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It's the reason why quarrymen put
this hand made pillar

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to protect them from falling roof,
from collapse.

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00:17:21,320 --> 00:17:23,720
Who actually dug these areas?

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00:17:23,720 --> 00:17:26,880
It is specific to France when
you are owner of the surface,

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you are owner of the underground
until the centre of the earth.

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00:17:30,320 --> 00:17:32,200
To the centre of the earth
under French law?

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00:17:32,200 --> 00:17:34,800
Yeah, according to the French law.
How interesting.

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'As more and more quarries
were excavated,

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'people began to take a greater
interest in the mysterious objects

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00:17:48,840 --> 00:17:52,080
'they were finding
embedded in the rock.'

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Ah, it's magical, isn't it? You can
see there, a really clear shell.

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00:17:58,440 --> 00:18:01,920
It must have been very strange
for the workmen who first came

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down here when they realized they
were looking at something which
should be on the ocean floor.

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00:18:08,440 --> 00:18:12,520
What they were looking at,
of course, were fossils.

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00:18:18,360 --> 00:18:22,960
For a long time, people had no
idea what fossils really were.

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Some people claimed
they'd come from the moon.

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00:18:25,640 --> 00:18:30,720
Others that they were
mud's unsuccessful attempt
to turn into life.

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In fact, it wasn't until
the end of the 18th Century

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that people fully appreciated
they had once been living things.

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And this realization opened up
a whole new window into the past.

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A past that was both ancient
and unimaginably different.

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Here in France,
many of those fossils

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ended up in the hands of
a brilliant scientist.

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00:19:03,400 --> 00:19:06,640
A man obsessed by old bones.

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His name was Georges Cuvier

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and he was widely regarded as the
world's leading animal anatomist.

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There was barely
an animal in existence

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whose remains hadn't come his way.

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There's a story about Cuvier,
which I like, which I think
really sums up the man.

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00:19:37,520 --> 00:19:41,200
It's late at night
and Cuvier has gone to bed...

234
00:19:41,200 --> 00:19:45,360
when one of his students
dressed in a devil's costume bursts

235
00:19:45,360 --> 00:19:50,120
into his room and cries "Cuvier,
Cuvier, I've come to eat you!"

236
00:19:52,440 --> 00:19:57,920
Cuvier opened one eye, calmly looked
the student up and down and said,

237
00:19:57,920 --> 00:20:01,640
"All animals that have hooves
and horns are herbivores -

238
00:20:01,640 --> 00:20:03,160
"you cannot eat me."

239
00:20:05,560 --> 00:20:09,080
Now the point is that
Cuvier had realized

240
00:20:09,080 --> 00:20:10,960
that from a couple of features,

241
00:20:10,960 --> 00:20:14,480
you could work out the
essential nature of any animal.

242
00:20:16,000 --> 00:20:20,840
This insight would lead Cuvier to
propose a new, and to many minds,

243
00:20:20,840 --> 00:20:24,120
unthinkable story of life on earth.

244
00:20:25,920 --> 00:20:29,160
Now I'm no Cuvier, but I did
train as a medical doctor

245
00:20:29,160 --> 00:20:32,720
and so I've seen a lot of bones,
albeit human ones.

246
00:20:32,720 --> 00:20:37,520
In here I've got some fossil bones.
I'm going to try and see if I can
work out where they came from.

247
00:20:37,520 --> 00:20:41,840
Right. I think this is
the end bit of the finger.

248
00:20:41,840 --> 00:20:45,400
But in this case is has
a big claw attached.

249
00:20:45,400 --> 00:20:49,560
So I'm guessing this comes
from a carnivore. I'm going to go
and hunt carnivores.

250
00:20:52,120 --> 00:20:56,240
'By examining the form of any
body part, Cuvier claimed

251
00:20:56,240 --> 00:21:01,520
'you could discover everything there
was to know about its function.'

252
00:21:01,520 --> 00:21:07,440
It's a bit like a crocodile claw,
but not really close enough.

253
00:21:07,440 --> 00:21:10,960
'And from its function,
its likely source.'

254
00:21:10,960 --> 00:21:14,080
Bigger, but not bad. That's a dog.

255
00:21:16,160 --> 00:21:17,800
I think that's about right.

256
00:21:17,800 --> 00:21:22,560
I guess that this is from a hyena.

257
00:21:22,560 --> 00:21:25,040
Let's see if I'm right.

258
00:21:25,040 --> 00:21:29,880
No, close though,
it's from a wolf apparently. Wolf.

259
00:21:31,840 --> 00:21:35,920
Cuvier was clearly better at this
than me and this allowed him to

260
00:21:35,920 --> 00:21:40,680
identify many previously unknown
fossils coming out of the ground.

261
00:21:43,360 --> 00:21:49,040
But also some remains that would
have unsettling implications.

262
00:21:49,040 --> 00:21:53,240
One of the fossils that Cuvier
was sent, was this one.

263
00:21:53,240 --> 00:21:56,360
It is, believe it or not,
a giant tooth.

264
00:21:56,360 --> 00:21:58,720
You can tell that, because
this is the enamel

265
00:21:58,720 --> 00:22:00,320
or biting layer over here.

266
00:22:00,320 --> 00:22:02,320
Now, the people who found
this fossil

267
00:22:02,320 --> 00:22:04,600
were convinced
it came from an elephant.

268
00:22:04,600 --> 00:22:06,800
But Cuvier had other ideas.

269
00:22:09,120 --> 00:22:11,720
The fossil I've got here is
obviously much bigger

270
00:22:11,720 --> 00:22:13,880
than the elephant tooth
you've got there,

271
00:22:13,880 --> 00:22:16,600
what other features did Cuvier
notice were different?

272
00:22:16,600 --> 00:22:19,400
Well, you see the size of course,
you are right.

273
00:22:19,400 --> 00:22:22,640
But, in this African elephant tooth

274
00:22:22,640 --> 00:22:28,960
you can see that the enamel is very
different on the grinding surface.

275
00:22:28,960 --> 00:22:32,080
There are diamond enamel lamina.

276
00:22:32,080 --> 00:22:34,680
Here, there are parallel lamina

277
00:22:34,680 --> 00:22:38,640
and they are more numerous
than in the African elephant.

278
00:22:38,640 --> 00:22:41,480
So there is a
very important difference.

279
00:22:41,480 --> 00:22:44,800
We know that this tooth
was coming from Russia

280
00:22:44,800 --> 00:22:48,920
and this tooth was called by
Russians, the mammoth.

281
00:22:48,920 --> 00:22:51,120
Ah, it's a mammoth. A mammoth.

282
00:22:51,120 --> 00:22:54,840
So he was able to look at this
and go, "It's an elephant,

283
00:22:54,840 --> 00:22:56,480
"but a much bigger elephant,

284
00:22:56,480 --> 00:23:00,440
"and a very different, sort of
a third species of elephant."

285
00:23:03,960 --> 00:23:09,800
The revelation that the mammoth was
a species totally distinct

286
00:23:09,800 --> 00:23:15,520
from any living elephant was nothing
compared to Cuvier's next bombshell.

287
00:23:17,400 --> 00:23:19,880
Cuvier thought long and hard
about mammoths

288
00:23:19,880 --> 00:23:24,000
and he came to a surprising
and radical conclusion.

289
00:23:24,000 --> 00:23:29,280
Now clearly, mammoths are enormous
beasts yet no-one had ever seen one,

290
00:23:29,280 --> 00:23:32,000
which suggested that at
some point in the past

291
00:23:32,000 --> 00:23:36,320
mammoths, all of them,
must have gone extinct.

292
00:23:43,400 --> 00:23:47,000
And it wasn't just mammoths.

293
00:23:47,000 --> 00:23:51,000
Before long, hundreds of
other strange looking fossils

294
00:23:51,000 --> 00:23:55,880
began to be identified as creatures
that had mysteriously disappeared

295
00:23:55,880 --> 00:23:57,600
off the face of the earth.

296
00:24:02,040 --> 00:24:06,360
The claim that some animals that
had once lived had gone extinct

297
00:24:06,360 --> 00:24:08,680
raised uncomfortable questions.

298
00:24:08,680 --> 00:24:13,960
If every creature in God's fixed
universe had a place and a purpose,

299
00:24:13,960 --> 00:24:15,640
why had some died off?

300
00:24:19,280 --> 00:24:22,680
The suggestion
that most of the creatures

301
00:24:22,680 --> 00:24:29,160
who had ever lived were now extinct
was both baffling and disturbing.

302
00:24:31,960 --> 00:24:36,360
The only consolation was that
this was still a history of life,

303
00:24:36,360 --> 00:24:39,360
which we humans
were separate from.

304
00:24:43,400 --> 00:24:50,520
For now, the most pressing
question raised by extinction
was one of time.

305
00:24:50,520 --> 00:24:55,280
And whether this fossil record of
long lost species was evidence

306
00:24:55,280 --> 00:25:00,520
that the earth was older,
much older than previously believed.

307
00:25:12,200 --> 00:25:16,120
The 18th Century
was the age of the experiment.

308
00:25:16,120 --> 00:25:21,160
There were experiments on light,
liquids,

309
00:25:21,160 --> 00:25:23,560
gases,

310
00:25:23,560 --> 00:25:29,480
but also an experiment to establish
the precise age of the earth.

311
00:25:31,080 --> 00:25:34,720
The man behind the experiment
was Le Comte de Buffon.

312
00:25:34,720 --> 00:25:38,040
A fabulously wealthy
French aristocrat, Buffon

313
00:25:38,040 --> 00:25:41,920
was the first person to
seriously attempt to measure
the age of the earth,

314
00:25:41,920 --> 00:25:48,080
and he did so using some
metal balls, a pocket watch
and a blacksmith's forge.

315
00:25:54,120 --> 00:25:57,360
Good morning, Brian. Good morning.
Hi there, I'm Michael Mosley.

316
00:25:57,360 --> 00:25:59,200
Hello, Michael.
I have a present for you.

317
00:25:59,200 --> 00:26:02,240
Two metal balls. I think you
know what to do with them.

318
00:26:06,000 --> 00:26:10,440
You might imagine that back in
Buffon's day, most people believed

319
00:26:10,440 --> 00:26:15,720
that the world was created in
six days and was 6,000 years old.

320
00:26:15,720 --> 00:26:19,320
In fact, a lot of people,
including many clerics,

321
00:26:19,320 --> 00:26:22,160
did not take the Bible
that literally.

322
00:26:22,160 --> 00:26:27,240
Buffon was not unusual in suspecting
that the earth might be very old.

323
00:26:27,240 --> 00:26:34,800
Where he was unusual was he was
prepared to do an experiment
to find out just how old.

324
00:26:34,800 --> 00:26:36,720
Right, anything I can do?

325
00:26:36,720 --> 00:26:40,120
Give it a nice long stroke,
just slow, straight down.

326
00:26:40,120 --> 00:26:43,160
How long will it actually take
to heat up to red hot?

327
00:26:43,160 --> 00:26:46,840
Probably the best part of an hour
looking at the size of the ball.

328
00:26:49,160 --> 00:26:54,400
The experiment was actually based
on a suggestion by Sir Isaac Newton.

329
00:26:54,400 --> 00:26:59,960
He said imagine the world
had started off as a red,
hot piece of iron.

330
00:26:59,960 --> 00:27:02,080
If you could work out how long
it had taken to cool

331
00:27:02,080 --> 00:27:04,240
from that state to
the present state,

332
00:27:04,240 --> 00:27:08,920
then you could work out just
how old the earth really is.

333
00:27:11,360 --> 00:27:16,280
By timing how long it took for
different size balls to cool down,

334
00:27:16,280 --> 00:27:19,960
Buffon was confident he could
extrapolate his figures

335
00:27:19,960 --> 00:27:25,040
and establish how long it had taken
the earth to reach a similar state.

336
00:27:25,040 --> 00:27:27,200
Do you reckon they're
ready yet, Brian?

337
00:27:27,200 --> 00:27:29,320
Well, they're well
up to temperature, yes.

338
00:27:29,320 --> 00:27:31,080
It's hot, isn't it?

339
00:27:31,080 --> 00:27:35,120
I'm trying to
avoid dropping this on my toes.

340
00:27:35,120 --> 00:27:37,280
Take that down there.

341
00:27:39,520 --> 00:27:42,720
Brilliant.
I've got my pocket watch here now.

342
00:27:42,720 --> 00:27:45,720
So, how long do you think
before we can actually touch them?

343
00:27:45,720 --> 00:27:49,080
Looking at least 25 minutes or
even longer for the small one.

344
00:27:49,080 --> 00:27:53,320
The larger ones much more mass,
probably an hour.

345
00:28:01,400 --> 00:28:06,120
'A little later and I'm finally
ready to start to plot my graph,

346
00:28:06,120 --> 00:28:10,280
'extrapolating my timings
for the two balls,

347
00:28:10,280 --> 00:28:14,560
'to allow for the much
bigger diameter of the earth.'

348
00:28:14,560 --> 00:28:19,960
Right. Now for the age of the earth
using Buffon's method.

349
00:28:19,960 --> 00:28:25,480
I calculate the age of the earth at
92,000 years.

350
00:28:25,480 --> 00:28:29,480
And Buffon, well, he said it
was a suspiciously accurate

351
00:28:29,480 --> 00:28:35,840
74,832 years old.

352
00:28:35,840 --> 00:28:41,520
As we now know, both these
figures are in fact way out.

353
00:28:43,800 --> 00:28:47,160
Wildly inaccurate though Buffon's
method was,

354
00:28:47,160 --> 00:28:51,240
it would be churlish to
let that detract from his legacy.

355
00:28:54,320 --> 00:28:57,560
The important point is,
that by doing the experiments

356
00:28:57,560 --> 00:29:01,760
and by publishing the results,
Buffon sparked a debate.

357
00:29:01,760 --> 00:29:05,160
Not just about how old
the earth actually is,

358
00:29:05,160 --> 00:29:09,360
but how and why every creature
on earth came into being.

359
00:29:10,880 --> 00:29:14,200
A debate that would
now be intensified

360
00:29:14,200 --> 00:29:17,160
by a new way of looking
at the world.

361
00:29:25,280 --> 00:29:28,440
Standing between northern
and southern Europe

362
00:29:28,440 --> 00:29:32,080
is one of the world's
most formidable natural barriers -

363
00:29:32,080 --> 00:29:34,320
the Alps.

364
00:29:34,320 --> 00:29:36,800
Even as late as
the mid 18th Century,

365
00:29:36,800 --> 00:29:40,720
no-one had yet climbed
this region's highest peak -

366
00:29:40,720 --> 00:29:42,320
Mont Blanc.

367
00:29:53,720 --> 00:30:00,120
In 1760, a young Swiss aristocrat
called Horace Benedict de Saussure

368
00:30:00,120 --> 00:30:05,720
came to the small Alpine
village of Chamonix,
in the foothills of Mont Blanc.

369
00:30:05,720 --> 00:30:11,000
Now, he came originally to collect
plants. But he soon became
so enchanted by the mountain

370
00:30:11,000 --> 00:30:14,440
that he offered a reward to the
first person who could climb it.

371
00:30:20,400 --> 00:30:22,040
Despite many attempts,

372
00:30:22,040 --> 00:30:26,240
it was 26 years before anyone
managed to reach the summit.

373
00:30:29,480 --> 00:30:33,640
de Saussure himself got to
the top a year later.

374
00:30:35,320 --> 00:30:41,640
But de Saussure was much
more than a rich man
with a passion for extreme sports.

375
00:30:41,640 --> 00:30:45,640
For once he'd climbed Mont Blanc,
he proceeded to carry out a series

376
00:30:45,640 --> 00:30:50,520
of experiments to discover
much more about the mountain.

377
00:30:50,520 --> 00:30:55,240
Going to remote places and getting
your hands dirty was a new way

378
00:30:55,240 --> 00:30:59,000
of trying to understand the
processes which shaped the earth.

379
00:30:59,000 --> 00:31:01,080
And de Saussure gave it a name...

380
00:31:01,080 --> 00:31:02,960
geology.

381
00:31:04,480 --> 00:31:07,280
With its emphasis on
direct observation

382
00:31:07,280 --> 00:31:11,040
this new way of looking at the
earth would play a vital role

383
00:31:11,040 --> 00:31:13,840
in unravelling not just
the mysteries of the planet,

384
00:31:13,840 --> 00:31:20,160
but also the entire history
of life on earth including ours.

385
00:31:26,640 --> 00:31:30,720
All across Europe
practically dressed men

386
00:31:30,720 --> 00:31:34,040
armed with small hammers
headed off into the countryside

387
00:31:34,040 --> 00:31:37,720
in search of the earth's
hidden secrets.

388
00:31:39,560 --> 00:31:41,680
Driven by an intense curiosity

389
00:31:41,680 --> 00:31:45,000
that would have surprised their
predecessors,

390
00:31:45,000 --> 00:31:50,800
they began to notice a number of
strange anomalies in the landscape.

391
00:31:50,800 --> 00:31:53,200
I've come here to the
east coast of Scotland

392
00:31:53,200 --> 00:31:54,960
to a place called Siccar Point.

393
00:31:54,960 --> 00:31:58,520
It is wild,
windy and rather beautiful.

394
00:31:58,520 --> 00:32:02,960
And just down there
is something truly remarkable,
something which an early

395
00:32:02,960 --> 00:32:07,400
geologist who came here described as
like looking into the abyss of time.

396
00:32:24,720 --> 00:32:28,920
This is what I've come to see
and it is very strange indeed.

397
00:32:28,920 --> 00:32:31,720
It's called an unconformity.

398
00:32:31,720 --> 00:32:36,240
What you have down there is
layers of rock that appear
to be laid down vertically.

399
00:32:36,240 --> 00:32:43,120
And then just above them a layer of
red sandstone, which appears to
have been laid down horizontally.

400
00:32:48,200 --> 00:32:50,320
But as odd as this may seem,

401
00:32:50,320 --> 00:32:54,960
to some there appeared to be
a startling explanation.

402
00:32:57,440 --> 00:33:01,600
This layer of rock looks as
though it was laid down vertically.

403
00:33:01,600 --> 00:33:05,280
But at some point in the past
it must have been at the
bottom of the ocean

404
00:33:05,280 --> 00:33:09,960
and formed horizontally
by layer after layer of sediment.

405
00:33:09,960 --> 00:33:12,840
Then the whole thing rose
to the surface, was flipped

406
00:33:12,840 --> 00:33:16,920
through 90 degrees and sank
to the bottom of the seas again.

407
00:33:16,920 --> 00:33:19,320
There another layer formed,

408
00:33:19,320 --> 00:33:24,640
until finally the whole thing
rose to the surface once again.

409
00:33:28,960 --> 00:33:34,400
All these processes are
extremely slow and all this implied

410
00:33:34,400 --> 00:33:38,680
that the earth is incredibly old -
practically eternal.

411
00:33:42,760 --> 00:33:46,040
And it wasn't just Siccar Point.

412
00:33:46,040 --> 00:33:48,520
The evidence for slow change
was everywhere.

413
00:33:50,760 --> 00:33:54,560
Geologists looked at waterfalls
and saw how the constant

414
00:33:54,560 --> 00:33:58,440
flow of water had gradually eroded
the surrounding rock.

415
00:34:01,200 --> 00:34:06,560
They saw how rain had inexorably
worn away the tops of mountains.

416
00:34:08,320 --> 00:34:11,800
And how the slow movement
of glaciers

417
00:34:11,800 --> 00:34:14,880
had carved out entire valleys.

418
00:34:18,080 --> 00:34:22,400
They came to realize that
the single most important factor

419
00:34:22,400 --> 00:34:25,240
in why the world
looks the way it does

420
00:34:25,240 --> 00:34:29,040
was time and lots of it.

421
00:34:33,040 --> 00:34:37,080
The moment that people first began
to think in terms of deep time

422
00:34:37,080 --> 00:34:40,240
is one of the most significant
in the history of science.

423
00:34:40,240 --> 00:34:44,400
It would go on to profoundly affect
how people see themselves.

424
00:34:44,400 --> 00:34:49,200
But trying to grasp deep time
is extremely difficult, because
it is so different to human time.

425
00:34:49,200 --> 00:34:52,360
So you have to rely on analogies.

426
00:34:52,360 --> 00:34:59,640
One of my favourites is to imagine
the age of the earth as a length
from my shoulder to my finger tips.

427
00:34:59,640 --> 00:35:06,320
On that scale, the whole of human
history, everything we've achieved
in the last few thousand years

428
00:35:06,320 --> 00:35:11,080
would be wiped away
by the single swipe of a nail file.

429
00:35:13,320 --> 00:35:17,880
So, why did this concept of
deep time take root now?

430
00:35:19,400 --> 00:35:24,040
There was the expansion of
quarrying and mining
exposing more of the hidden earth.

431
00:35:25,640 --> 00:35:29,640
The fossils of extinct creatures
that were being uncovered.

432
00:35:31,640 --> 00:35:36,800
And the emergence of geology -
a new scientific view of the planet.

433
00:35:39,000 --> 00:35:45,440
Finally, the pieces were in place
to try and answer the question -
how did WE get here?

434
00:35:52,520 --> 00:35:58,600
The industrial revolution was a
time of rapid, dizzying change.

435
00:35:58,600 --> 00:36:03,560
Great industrial cities
spread across Victorian Britain,

436
00:36:03,560 --> 00:36:09,240
their factories drawing in
workers from far and wide.

437
00:36:09,240 --> 00:36:14,240
New railways snaked across the
landscape cutting journey times

438
00:36:14,240 --> 00:36:18,880
and bringing cheap
goods to the masses.

439
00:36:20,960 --> 00:36:25,040
'It was a whirlwind of new ideas,
new methods

440
00:36:25,040 --> 00:36:29,480
'and all of it in the
name of progress.'

441
00:36:31,680 --> 00:36:36,760
Belief in progress was one of
the defining characteristics
of the Victorian age.

442
00:36:36,760 --> 00:36:42,280
Factory owners from humble origins
had country houses,
even seats in Parliament.

443
00:36:42,280 --> 00:36:48,760
Britain was the leading industrial
country in the world thanks to
the ingenuity of her people.

444
00:36:57,080 --> 00:37:00,840
It was out of this belief in
progress that a radical theory

445
00:37:00,840 --> 00:37:04,280
of how WE got here
exploded onto the scene.

446
00:37:11,320 --> 00:37:15,600
The theory proposed that not only
were societies and nations

447
00:37:15,600 --> 00:37:19,880
capable of progressive change,
but also nature.

448
00:37:38,160 --> 00:37:42,640
In 1844, this slim, rather ordinary
looking book was first published

449
00:37:42,640 --> 00:37:46,080
and it swiftly became one of
THE most controversial books

450
00:37:46,080 --> 00:37:48,160
of the Victorian age.

451
00:37:48,160 --> 00:37:52,600
It was a literary sensation
selling tens of thousands of copies

452
00:37:52,600 --> 00:37:56,440
and it was read by everyone of
influence from the Queen downwards.

453
00:37:56,440 --> 00:38:00,840
Adding to its mystique was the
fact that its author made strenuous

454
00:38:00,840 --> 00:38:05,800
efforts throughout his lifetime
to remain strictly anonymous.

455
00:38:09,480 --> 00:38:12,680
The author was a Scotsman -

456
00:38:12,680 --> 00:38:14,200
Robert Chambers.

457
00:38:15,800 --> 00:38:20,240
Robert Chambers was born
with six fingers and six toes.

458
00:38:20,240 --> 00:38:23,640
When was young he had an operation
to get rid of the extra digits,

459
00:38:23,640 --> 00:38:25,480
which unfortunately went wrong.

460
00:38:25,480 --> 00:38:30,720
Self conscious, Robert now immersed
himself in the world of print.

461
00:38:34,920 --> 00:38:39,320
Few changes embodied the
Victorian ideal of progress

462
00:38:39,320 --> 00:38:43,720
as much as the 19th Century
transformation
of the print industry.

463
00:38:43,720 --> 00:38:49,360
The steam-powered printing press
ushered in a new age of cheap,

464
00:38:49,360 --> 00:38:53,880
mass-produced books creating
a hunger for knowledge right
across society.

465
00:38:58,080 --> 00:39:00,080
In response to this demand,

466
00:39:00,080 --> 00:39:05,400
Robert Chambers helped his brother
set up a successful publishing firm,

467
00:39:05,400 --> 00:39:09,200
while still leaving enough time
to devote to his first love -

468
00:39:09,200 --> 00:39:12,240
writing.

469
00:39:12,240 --> 00:39:17,200
Robert Chambers was not
a very original thinker
but he was well read.

470
00:39:17,200 --> 00:39:21,920
His writing was clear, vivid
and above all thought provoking.

471
00:39:21,920 --> 00:39:26,240
It was these qualities plus the fact
that he had an insider's knowledge

472
00:39:26,240 --> 00:39:31,320
of the publishing industry, which
ensured his book was a huge success.

473
00:39:31,320 --> 00:39:37,120
Chambers called it Vestiges Of
The Natural History Of Creation

474
00:39:37,120 --> 00:39:40,880
and in it he presented
a compelling case

475
00:39:40,880 --> 00:39:45,800
for the notion that species
are not fixed - they change.

476
00:39:48,360 --> 00:39:52,160
That everything
had developed from an earlier form.

477
00:39:53,680 --> 00:39:56,640
He called this concept
transmutation.

478
00:39:56,640 --> 00:40:00,080
We call it evolution.

479
00:40:04,760 --> 00:40:10,080
Evolution emerged out of a world of
progress, a conviction that

480
00:40:10,080 --> 00:40:14,600
all things are capable of change,
of improvement.

481
00:40:14,600 --> 00:40:20,080
A history of life that was as
diverse as it was baffling.

482
00:40:20,080 --> 00:40:24,760
And a realization that the
earth was almost immeasurably old.

483
00:40:26,840 --> 00:40:30,840
But the real significance of
evolution to this story is that

484
00:40:30,840 --> 00:40:34,400
it now forced people to confront
the uncomfortable question -

485
00:40:34,400 --> 00:40:36,440
how did we get here?

486
00:40:39,240 --> 00:40:42,720
Chambers was not the first
person to write about evolution,

487
00:40:42,720 --> 00:40:45,520
but he did take the argument
further than others had.

488
00:40:45,520 --> 00:40:48,560
Instead of being set apart
from the rest of creation,

489
00:40:48,560 --> 00:40:52,240
Chambers was saying
we were simply an extension of it.

490
00:40:52,240 --> 00:40:55,200
No wonder he wanted to remain
anonymous.

491
00:40:57,520 --> 00:40:58,760
SCREAMING

492
00:40:59,760 --> 00:41:03,240
For a society where people
fervently believed that

493
00:41:03,240 --> 00:41:06,640
humans had a special place
in God's creation,

494
00:41:06,640 --> 00:41:11,640
the claim we were descended
from animals was deeply shocking.

495
00:41:12,800 --> 00:41:15,440
And so the backlash began.

496
00:41:16,400 --> 00:41:19,360
There were attacks from
the scientific community

497
00:41:19,360 --> 00:41:22,440
on the book's accuracy.

498
00:41:22,440 --> 00:41:28,680
And from the clergy for undermining
moral and social order.

499
00:41:30,240 --> 00:41:33,720
One particularly scathing review
described it as,

500
00:41:33,720 --> 00:41:37,560
"not merely shallow and superficial,
but utterly false throughout."

501
00:41:37,560 --> 00:41:40,760
Harsh. But despite the controversy,

502
00:41:40,760 --> 00:41:42,880
or let's face it
probably because of it,

503
00:41:42,880 --> 00:41:46,280
the public simply couldn't
get enough of this book.

504
00:41:49,640 --> 00:41:53,680
For all its success,
what Chambers' book didn't do

505
00:41:53,680 --> 00:41:57,680
was come up with an explanation of
how evolution happens.

506
00:42:01,640 --> 00:42:06,520
The man who answered that question
was, of course, Charles Darwin.

507
00:42:10,160 --> 00:42:14,360
A keen geologist and an ardent
believer in the earth's antiquity,

508
00:42:14,360 --> 00:42:17,600
Darwin had been working on
his own theory of evolution

509
00:42:17,600 --> 00:42:20,600
for several years when
Vestiges first appeared.

510
00:42:23,760 --> 00:42:29,080
But, it would be a further 15 years,
by which time much of the fuss

511
00:42:29,080 --> 00:42:34,320
surrounding evolution had died down,
before Darwin felt ready to publish.

512
00:42:43,360 --> 00:42:47,480
His explanation for how
animals evolved had its roots in

513
00:42:47,480 --> 00:42:52,480
the same industrial landscape from
which Chambers' book had emerged.

514
00:43:04,280 --> 00:43:08,200
According to Darwin, life was
one long struggle for survival.

515
00:43:08,200 --> 00:43:10,360
And just as within
the cotton industry,

516
00:43:10,360 --> 00:43:13,200
there was competition
between manufacturers,

517
00:43:13,200 --> 00:43:17,320
so in nature there was competition
between and amongst species.

518
00:43:19,440 --> 00:43:24,400
Just as new technology might give
one factory an edge over another,

519
00:43:24,400 --> 00:43:27,120
so it was in nature.

520
00:43:29,840 --> 00:43:35,480
Any new trait that gave an organism
an edge over its rival would prevail

521
00:43:35,480 --> 00:43:39,680
and become more common
in later generations.

522
00:43:39,680 --> 00:43:45,800
Gradually giving rise to the
appearance of new species.

523
00:43:48,760 --> 00:43:54,080
A mechanism for change that
Darwin called Natural Selection.

524
00:43:57,880 --> 00:44:02,640
Darwin's followers must have hoped
that his theory of Natural Selection

525
00:44:02,640 --> 00:44:05,640
would help answer the question -
how did we get here?

526
00:44:05,640 --> 00:44:07,680
But there were holes in the theory.

527
00:44:07,680 --> 00:44:13,200
Although Darwin acknowledged
the critical importance of the
environment on driving evolution,

528
00:44:13,200 --> 00:44:16,200
he never fully grasped
the incredible extent

529
00:44:16,200 --> 00:44:20,480
to which life on earth is shaped
by changes in our violent planet.

530
00:44:20,480 --> 00:44:24,440
Something which has only
relatively recently come to light.

531
00:44:30,280 --> 00:44:34,600
While biology raced ahead
in the early 20th Century,

532
00:44:34,600 --> 00:44:38,520
geology had more or less
settled into a routine.

533
00:44:38,520 --> 00:44:40,720
Stones were dated,

534
00:44:40,720 --> 00:44:44,280
fossils examined,
collections expanded.

535
00:44:45,880 --> 00:44:48,800
But, as so often happens
in the story of science,

536
00:44:48,800 --> 00:44:53,480
it's the non-specialists, the
enthusiasts who shake things up.

537
00:44:54,480 --> 00:44:57,480
One such enthusiast
was Alfred Wegener.

538
00:44:57,480 --> 00:45:00,040
He was a German meteorologist,
a weather man,

539
00:45:00,040 --> 00:45:03,320
and with his brother, he held
a world record for ballooning.

540
00:45:03,320 --> 00:45:06,680
He was not, however,
a trained geologist.

541
00:45:06,680 --> 00:45:09,920
But that didn't put him
off proposing a radical

542
00:45:09,920 --> 00:45:14,040
and controversial new theory about
the forces that shaped the earth.

543
00:45:14,960 --> 00:45:19,760
Forces so powerful
as to have shaped even life itself.

544
00:45:22,520 --> 00:45:29,240
The story goes the Wegner was
looking at an atlas when he
noticed something rather peculiar.

545
00:45:29,240 --> 00:45:35,760
Take a map of the world, a pair
of scissors and cut your way
down through Greenland

546
00:45:35,760 --> 00:45:38,440
until you get
to the cost of South America.

547
00:45:38,440 --> 00:45:41,920
And then it requires a little
bit more finesse

548
00:45:41,920 --> 00:45:46,640
working away carefully
around Brazil.

549
00:45:46,640 --> 00:45:49,880
And then at the end,
just slash away again.

550
00:45:49,880 --> 00:45:52,800
If you move the coast of
South America over to the coast

551
00:45:52,800 --> 00:45:58,000
of Africa what you'll notice is
that they seem to match very
closely.

552
00:45:58,000 --> 00:46:00,280
It's almost as if
they were once joined.

553
00:46:02,960 --> 00:46:07,480
Wegner noticed this, but he did
nothing about it for around a year,

554
00:46:07,480 --> 00:46:11,160
until he came across
some fascinating fossil finds.

555
00:46:20,400 --> 00:46:22,320
Take a look at this.

556
00:46:22,320 --> 00:46:28,280
It's a fossilized leaf and it's
about 250 million years old.

557
00:46:28,280 --> 00:46:31,160
It came from a tree fern
that is now extinct.

558
00:46:31,160 --> 00:46:34,400
Now, the odd thing these tree
ferns grew in the tropics

559
00:46:34,400 --> 00:46:40,240
but these fossils have been found in
cold, remote places like this one.

560
00:46:40,240 --> 00:46:44,200
In fact, places even
colder than here in Iceland.

561
00:46:44,200 --> 00:46:47,240
So how was that possible?

562
00:46:49,520 --> 00:46:52,440
Then, there were reptiles.

563
00:46:52,440 --> 00:46:55,960
A particular species of reptile
found in South America

564
00:46:55,960 --> 00:47:02,720
but mysteriously matched by exactly
the same species in Africa
more than 7,000 kms away.

565
00:47:05,120 --> 00:47:12,360
In attempting to explain
these mysteries,
Wegner would transform geology.

566
00:47:12,360 --> 00:47:15,080
Science would have
to embrace a new

567
00:47:15,080 --> 00:47:19,040
and very different history
of life on earth.

568
00:47:22,440 --> 00:47:29,760
Wegner developed a theory
that was logical, but also, on
the surface, completely ludicrous.

569
00:47:29,760 --> 00:47:34,480
He suggested that all
the great seven continents
had once been clumped together

570
00:47:34,480 --> 00:47:39,080
into a single super continent
that he called Pangaea meaning,
"all lands".

571
00:47:39,080 --> 00:47:43,320
And then Pangaea
had simply split apart.

572
00:47:45,200 --> 00:47:48,760
A process that Wegner
attempted to illustrate.

573
00:47:56,400 --> 00:48:00,320
Wegner compared
the moving continents
to the huge floating icebergs

574
00:48:00,320 --> 00:48:04,600
he'd seen on
his many field trips to Greenland.

575
00:48:06,120 --> 00:48:09,600
But instead of blocks of ice
weighing a few thousand tons,

576
00:48:09,600 --> 00:48:16,160
he was talking about great slabs
of rock weighing trillions of tons.

577
00:48:16,160 --> 00:48:21,200
The problem for Wegner was
nobody was buying his big idea.

578
00:48:22,840 --> 00:48:27,320
To his eternal frustration,
Wegner had no way to explain

579
00:48:27,320 --> 00:48:33,200
how the slabs moved, no hard
evidence to convince the sceptics.

580
00:48:33,200 --> 00:48:39,000
One of Wegner's many critics
described his ideas
as "utter, damned rot."

581
00:48:39,000 --> 00:48:40,600
And you can see why.

582
00:48:40,600 --> 00:48:45,000
The idea that we are floating
around seems preposterous.

583
00:48:45,000 --> 00:48:48,720
And it didn't help that Wegner
was an amateur geologist,

584
00:48:48,720 --> 00:48:52,560
in many eyes,
a jumped-up weather forecaster.

585
00:48:54,080 --> 00:48:59,920
Wegner went back to meteorology
and his theory was shelved

586
00:48:59,920 --> 00:49:06,200
until a series
of unexpected discoveries made
during the height of the Cold War.

587
00:49:10,240 --> 00:49:15,800
In the 1950s, as the Cold War
intensified, the United States

588
00:49:15,800 --> 00:49:22,160
and the Soviet Union found
themselves engaged in a game of cat
and mouse deep beneath the ocean.

589
00:49:25,040 --> 00:49:30,680
A game that demanded
a much more accurate picture
of this underwater landscape.

590
00:49:33,800 --> 00:49:38,120
And so
the oceanographers set to work.

591
00:49:40,440 --> 00:49:44,520
They began taking thousands
of photographs of the ocean floor.

592
00:49:48,080 --> 00:49:54,160
Echo soundings plotted the rise
and fall of deep sea ridges...

593
00:49:56,520 --> 00:50:02,400
..while drill rods were sent down
to establish the composition
of the sea bed.

594
00:50:04,920 --> 00:50:11,120
But, in mapping the oceans,
the scientists discovered something
entirely unexpected.

595
00:50:13,840 --> 00:50:19,640
They found that the sea floor didn't
consists of one thick uniform crust,

596
00:50:19,640 --> 00:50:24,440
as used to be thought, but a
number of thin interlocking plates.

597
00:50:26,560 --> 00:50:31,320
And that the boundaries to those
plates featured mountain ranges...

598
00:50:34,720 --> 00:50:37,120
..deep rift valleys...

599
00:50:39,440 --> 00:50:41,840
..even volcanoes.

600
00:50:47,720 --> 00:50:55,000
And this entire landscape
was floating on a bed of molten rock
constantly on the move.

601
00:51:04,200 --> 00:51:09,080
And you can also see
evidence of this on dry land.

602
00:51:12,440 --> 00:51:16,800
I've come to
Thingvellir in Iceland,
one of the wonders of the world.

603
00:51:16,800 --> 00:51:19,040
It is one of the
few places on earth

604
00:51:19,040 --> 00:51:21,840
that you can actually see
with your own eyes

605
00:51:21,840 --> 00:51:24,200
the joins in our patchwork planet.

606
00:51:42,400 --> 00:51:48,240
This may look like an ordinary cliff
edge, but it's actually the start
of an enormous great slab of rock

607
00:51:48,240 --> 00:51:50,880
which extends all the way
from here in Iceland,

608
00:51:50,880 --> 00:51:55,240
across the Atlantic Ocean, across
North America to the Pacific Ocean.

609
00:51:55,240 --> 00:51:57,800
It is called the North American
Plate.

610
00:51:57,800 --> 00:52:03,120
And just over there,
well, that is the beginning
of another enormous plate.

611
00:52:03,120 --> 00:52:09,400
It is called the Eurasian Plate,
and it extends all the way
from here to Shanghai.

612
00:52:12,760 --> 00:52:18,160
Now, if I was to stand here long
enough, say, a few thousand years,

613
00:52:18,160 --> 00:52:25,080
I'd notice the gap between me
and Eurasia was getting wider.

614
00:52:25,080 --> 00:52:27,440
Scientists have measured
this movement.

615
00:52:27,440 --> 00:52:34,040
It ranges from a very gradual
seven millimetres a year
here at Thingvellir,

616
00:52:34,040 --> 00:52:38,240
to almost ten centimetres
a year elsewhere.

617
00:52:38,240 --> 00:52:40,320
Over hundreds of millions of years,

618
00:52:40,320 --> 00:52:46,120
this shifting of the earth's plates
has transformed the face
of our planet,

619
00:52:46,120 --> 00:52:51,280
a never-ending cycle of change that
Wegner had called continental drift.

620
00:52:54,640 --> 00:52:58,720
Sadly, Wegner didn't live long
enough to see his theory vindicated.

621
00:52:58,720 --> 00:53:02,040
In 1930, he went on an expedition
to Greenland.

622
00:53:02,040 --> 00:53:06,320
There, in temperatures of minus 60,
he died of cold and exhaustion.

623
00:53:06,320 --> 00:53:09,480
He was buried on the ice.

624
00:53:09,480 --> 00:53:15,120
Because of continental drift,
his body is now two metres
further away from home.

625
00:53:22,520 --> 00:53:28,600
But continental drift has done
much more than shape the earth.

626
00:53:28,600 --> 00:53:34,840
By showing how a fossilised tree
fern could travel all the way
from the tropics to the ice,

627
00:53:34,840 --> 00:53:42,080
or why it is that a single species
of reptile can be found on what are
now two widely separated continents.

628
00:53:42,080 --> 00:53:48,000
The theory also takes us closer
to solving the mystery
of how we got here.

629
00:53:53,600 --> 00:54:01,120
And that's because when the earth
moves in this way, the results
can also be incredibly violent.

630
00:54:01,120 --> 00:54:04,680
When the earth's plates collide...

631
00:54:06,160 --> 00:54:13,800
..they can trigger volcanic
eruptions so powerful as to block
out the sun for months on end.

632
00:54:18,080 --> 00:54:21,520
As those same plates
grind against each other,

633
00:54:21,520 --> 00:54:26,040
so they cause
devastating earthquakes...

634
00:54:28,600 --> 00:54:35,720
..which themselves can spawn
mega-tsunamis, that destroy
everything in their way.

635
00:54:39,920 --> 00:54:43,680
While it's easy to imagine
that all this violent upheaval

636
00:54:43,680 --> 00:54:49,400
brought with it nothing
but death and destruction,
the truth is very different.

637
00:54:49,400 --> 00:54:53,560
It's now clear that throughout our
four and half billion year history,

638
00:54:53,560 --> 00:54:59,560
the balance of our planet
has been absolutely central
to the creation of new life.

639
00:55:05,720 --> 00:55:11,360
Because, every time our planet
experiences violent change,

640
00:55:11,360 --> 00:55:14,560
a new opportunity for life
opens up...

641
00:55:16,080 --> 00:55:22,920
..making continental drift one
of the great drivers of evolution.

642
00:55:22,920 --> 00:55:27,720
And here are just a couple of ways
it has changed life on earth.

643
00:55:29,800 --> 00:55:31,960
Some 30 million years ago,

644
00:55:31,960 --> 00:55:37,880
the plate boundary separating Africa
from Arabia began to pull apart,

645
00:55:37,880 --> 00:55:41,160
causing the land in between
to fall away.

646
00:55:44,040 --> 00:55:46,960
A 5,000 km gash
in the earth's crust,

647
00:55:46,960 --> 00:55:50,360
that we know as
the East African Rift Valley.

648
00:55:55,560 --> 00:55:58,800
As a new landscape
of broken savannah formed,

649
00:55:58,800 --> 00:56:05,680
it allowed the ancestors
of many today's animals
to gain a foothold, and to flourish.

650
00:56:14,120 --> 00:56:19,680
And then there is climate change,
when continental drift
has also played a major role...

651
00:56:21,400 --> 00:56:25,280
..not least by accelerating
the onset of ice ages,

652
00:56:25,280 --> 00:56:30,880
by pushing land towards the poles,
and altering the flow
of ocean currents.

653
00:56:35,120 --> 00:56:40,400
Changes which have forced animals
to adapt in the most remarkable
of ways.

654
00:56:42,600 --> 00:56:48,520
And, just occasionally,
we're subjected to violence...

655
00:56:50,320 --> 00:56:53,760
..from beyond our planet,

656
00:56:53,760 --> 00:56:59,520
so extreme, that many species
are wiped out altogether...

657
00:57:01,480 --> 00:57:05,160
..only for others
to take their place.

658
00:57:11,160 --> 00:57:15,000
And so, what of us?

659
00:57:15,000 --> 00:57:17,440
How did we get here?

660
00:57:18,440 --> 00:57:24,600
Well, we are just the latest
in a long line of lucky survivors,

661
00:57:24,600 --> 00:57:29,600
born out of death, destruction,
and the immensity of deep time.

662
00:57:32,440 --> 00:57:37,080
And if this great experiment
that is life on earth

663
00:57:37,080 --> 00:57:38,880
were to be run again...

664
00:57:44,120 --> 00:57:46,560
..we might never even show up.

665
00:57:53,640 --> 00:57:58,040
It's now clear that the story of
life, and the story of our planet,

666
00:57:58,040 --> 00:58:01,880
which were once seen as separate,
are actually intrinsically linked.

667
00:58:01,880 --> 00:58:05,960
The evolution of new life
has been driven by climate change,

668
00:58:05,960 --> 00:58:11,920
by asteroid impacts, and by the
slow-motion collision of continents.

669
00:58:11,920 --> 00:58:16,360
It turns out that we
and every other living creature

670
00:58:16,360 --> 00:58:20,800
are marching to the drum beat
of our violent planet.

671
00:58:40,720 --> 00:58:45,440
Next time,
an ancient human ambition...

672
00:58:45,440 --> 00:58:48,360
the search for limitless power.

673
00:59:03,040 --> 00:59:06,080
Subtitles by Red Bee Media Ltd

674
00:59:06,080 --> 00:59:09,120
E-mail subtitling@bbc.co.uk