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00:00:07,400 --> 00:00:09,800
I've spent most of my life
trying to understand


2
00:00:09,800 --> 00:00:12,240
the forces that shaped our planet,


3
00:00:12,240 --> 00:00:14,440
and as a geologist,
it always seemed to me


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00:00:14,440 --> 00:00:17,160
that rocks were right
at the heart of things.


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00:00:21,880 --> 00:00:26,360
But now, I'm discovering it's not
only volcanoes and colliding
continents


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that have driven
the Earth's greatest changes,


7
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because at crucial moments
in its history,


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another force has helped create
the planet we live on...


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00:00:37,240 --> 00:00:39,600
...plants.


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Just look at this seed.


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It's small, it's brown,
it weighs hardly anything.
Looks pretty ordinary.


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But, actually, nothing
could be further from the truth,


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because what it will become
is truly extraordinary.


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These are giant sequoias.


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Some are over 3,000 years old.


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And sequoias are the largest
single life form on Earth.


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All from a tiny seed.


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Yet, even that pales into
insignificance


19
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when compared to what the whole
of the plant kingdom's done


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throughout the history
of our planet.


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It's a whole new story about
our Earth...


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...told through remarkable images,
captured for the very first time,


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and the latest scientific
discoveries.


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I love this. This is just fantastic.


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This programme is about
just one type of plant,


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the most underrated but perhaps
the most important of all.


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One that, by taking on and
conquering the rest of
the plant kingdom,


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shaped the face of the planet
and went on to help create
human civilisation.


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This is the story
of the rise of that underdog.


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For hundreds of millions of years,
throughout the time of
the dinosaurs,


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forests ruled the land.


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It was so warm, trees extended
over most of the Earth.


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Imagine the Arctic and Antarctic
without ice, carpeted with forests.


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Welcome to the planet of the trees.


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Today, isolated remnants of those
expansive forests still exist


36
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and here in East Africa
is one of the most impressive.


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The Katago Cloud Forest rises
out of the dry plains of Kenya.


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Cloaked in moisture,
it's much the same as it was then.


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Ah! Oh, at last!


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Look at that.


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But millions of years ago,


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a challenger to the old dominant
trees came onto the scene.


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And the best way to find it is
to climb right down


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into the depths of the forest.


45
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It's never really elegant, this.


46
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This is when the adrenaline thrill
starts to come in.


47
00:04:08,160 --> 00:04:11,320
To be honest, I'm not quite sure
after you get to...


48
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There's a little lip,
just seems to go straight down.


49
00:04:23,280 --> 00:04:26,720
This is the oldest forest
in Africa up here.


50
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A relic, really, of the time
when trees dominated the planet.


51
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So, this really has a...
a feeling of descending into
that ancient lost world.


52
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Back then, trees ruled


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because wood gave them
the strength to grow ever taller


54
00:05:12,640 --> 00:05:15,960
and to gorge on the sunlight
all plants need.


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As you descend,


56
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you get a real sense of
how trees bully and overshadow
everything below.


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We've come about ten metres
just into the canopy.


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(CHUCKLES) And I've nicked
the cameraman's light metre,


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just to see
what the light levels are doing.


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And already, they've dropped
by about a third.


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(WHISPERS) Oh, God, finally.


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Now, let's see...
see how that light's doing.


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That's gone down by a half.


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These huge trees here
have stolen half the light.


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Down here, the trees
are intimidating.


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But it's not complete gloom.


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Patches of sunlight do break through
to the forest floor.


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And those shafts of precious light
offer the chance


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for a new type of plant,


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one that would come to take on
the trees.


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00:06:45,040 --> 00:06:49,120
So, how did scientists discover
the identity of the challenger?


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It's all thanks to a rather
enchanting piece of research


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involving what's inside
this little box.


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You'll never guess what it is.


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This is a piece
of fossilised dinosaur poo.


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It stinks.


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Phew.


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It's from a titanosaur sauropod,


79
00:07:10,720 --> 00:07:13,920
which is kind of like
a brontosaurus,


80
00:07:13,920 --> 00:07:16,680
my favourite dinosaur as a kid.


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00:07:16,680 --> 00:07:18,200
It weighed about 100 tonnes,


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which makes me think that this is
just a fragment of something the
size of...


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I don't know, really.
Something big, anyway.


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00:07:25,160 --> 00:07:28,040
Scientists love fossil poo.
Coprolites, we call it.


85
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They tell us about the diet of
animals, and particularly,


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about the plants that were around
when dinosaurs were here.


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And when scientists analysed
this one a few years ago,


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they found it contained
something really strange.


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00:07:43,840 --> 00:07:49,320
Under the microscope, the scientists
saw a fragment of a plant.


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It had a distinctive pattern,
these figure-of-eight nodules.


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They turned out to be
the defining feature


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00:07:56,400 --> 00:08:00,360
of a family of plants
they were astonished to see.


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The grasses.


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00:08:04,520 --> 00:08:07,760
It was from 66 million years ago,


95
00:08:07,760 --> 00:08:13,520
evidence for the earliest grass
ever found, called matleitis.


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00:08:18,160 --> 00:08:19,520
From its humble birth,


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00:08:19,520 --> 00:08:23,360
grass would eventually become one
of the most dominant forces
on our planet.


98
00:08:33,600 --> 00:08:37,680
But its rise would be a
David-and-Goliath battle
with the trees.


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BIRD SONG


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You can still find descendants
of those early challengers today.


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Plants like this.


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And we think these are similar to
what the first grasses must have
looked like.


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00:09:05,560 --> 00:09:09,000
You can just imagine 'em
struggling away on the forest floor,


104
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just feeding off little scraps of
light making it through the canopy.


105
00:09:14,840 --> 00:09:17,680
It's wonderful to think
that dinosaurs the size of houses


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were trampling through forests like
this, just grazing on little patches
of grass.


107
00:09:29,240 --> 00:09:34,440
But the dinosaurs' days of grazing
were about to end abruptly.


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65 million years ago,
an asteroid ten kilometres across
killed them off.


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The grasses survived.


110
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But in turn,
they would face their own crisis.


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What was coming had nothing to do


112
00:10:13,840 --> 00:10:16,640
with the plants and animals
that lived on Earth.


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It was all to do with the
atmosphere,


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and that was changing
for the most surprising of reasons.


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Our air contains carbon dioxide.


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It's the gas that plants
need to breathe to stay alive.


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But between 50 and 30 million years
ago, this gas began to disappear...


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...threatening all plants.


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The crisis started with the creation
of huge mountain ranges like
the Himalayas...


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...the biggest period of mountain
building in Earth's history.


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The freshly exposed rock was
washed away.


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Some of the minerals ended up
in the sea.


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And here they sucked the carbon
dioxide gas out of the air,


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combining with it to form
an entirely new type of rock.


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Limestone.


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I can show you that limestone's got
carbon dioxide in it,


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because if I put
a little bit of acid on it,


128
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it should fizz like mad.


129
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What this is doing is
it's liberating carbon dioxide


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that had been in the ancient
atmosphere


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and has now for the last few million
years been locked away in this rock.


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By 30 million years ago,
as the mountains had risen,


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the level of carbon dioxide fell.


134
00:12:37,840 --> 00:12:42,240
In fact, carbon dioxide levels
dropped to a sixth of what they were
beforehand,


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which is an enormous fall,


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and for the plant kingdom
it meant crisis.


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Without enough vital carbon dioxide,


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many plants, including the grasses,
were struggling to survive.


139
00:13:18,240 --> 00:13:21,720
One way to reveal
the impact this had on plants


140
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is to look at a clever bit
of human machinery.


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00:13:28,000 --> 00:13:30,040
The car engine.


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Because what's under the bonnet
shares surprising similarities with
plants.


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The car engine relies
on two things to work.


144
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It needs petrol
and it needs oxygen from the air.


145
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Inside the engine, these two
are combined to release the energy


146
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to power the car.


147
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It's called combustion.


148
00:14:00,160 --> 00:14:02,400
ENGINE STARTS


149
00:14:10,960 --> 00:14:15,600
Like the engine, plants also need
a gas from the air to work,


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00:14:15,600 --> 00:14:18,640
in their case the carbon dioxide.


151
00:14:22,640 --> 00:14:24,800
So, for plants...
ENGINE STARTS


152
00:14:24,800 --> 00:14:26,920
...the collapse of
carbon dioxide levels


153
00:14:26,920 --> 00:14:30,920
were similar to a car engine
starved of oxygen.


154
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If I block the air intake, you can
feel the engine stuttering away,


155
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because it's struggling to get
the oxygen that it needs to work.


156
00:14:44,960 --> 00:14:47,480
With less carbon dioxide
in the atmosphere,


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plants also began to stutter.


158
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But the grasses were evolving
a new and ingenious invention.


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ENGINE RUNNING
Again, the engine provides
a parallel.


160
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There's a piece of shiny machinery
here that any petrol-head
will recognise.


161
00:15:06,600 --> 00:15:09,680
What that does is the opposite
of my hand.


162
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It forces more oxygen
into the engine.


163
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It's called a turbocharger.


164
00:15:21,360 --> 00:15:24,840
More oxygen means
that the petrol burns more fiercely


165
00:15:24,840 --> 00:15:28,800
and that means more power,
power enough to do this.


166
00:15:31,840 --> 00:15:34,440
(LAUGHS)


167
00:15:34,440 --> 00:15:36,640
Whoo-hoo!


168
00:15:47,160 --> 00:15:51,200
Evolution often comes up
with our cleverest solutions


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during desperate times.


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And one group of plants,
the grasses, turned this crisis


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into an opportunity.


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00:16:07,120 --> 00:16:08,440
Grasses like this.


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This is elephant grass,
which is one of the fastest-growing
plants in the world.


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00:16:12,640 --> 00:16:16,760
In three months, right,
this stuff grows four metres.


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That's that much every day.


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This phenomenal growth rate
was only possible


177
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because of a technology
that evolved 30 million years ago,


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00:16:26,000 --> 00:16:31,600
a design so effective that,
if you were a mechanic,
you'd be blown away.


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00:16:38,000 --> 00:16:41,440
The new grasses came up with the
equivalent of a turbocharger


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00:16:41,440 --> 00:16:44,200
inside the leaves.


181
00:16:48,240 --> 00:16:53,000
It's in the cells of the leaves
that photosynthesis occurs,


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00:16:53,000 --> 00:16:57,120
where carbon dioxide is combined
with water to make sugar.


183
00:17:00,680 --> 00:17:03,880
But the new grasses created
an add-on,


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00:17:03,880 --> 00:17:07,000
rings of specialist cells
known as bundles.


185
00:17:09,800 --> 00:17:12,440
It all acts as a miniature pump,


186
00:17:12,440 --> 00:17:16,200
sucking in and concentrating
vital carbon dioxide.


187
00:17:23,840 --> 00:17:26,960
So, although there was
less carbon dioxide in the air,


188
00:17:26,960 --> 00:17:30,800
the grasses had the edge
over other plants.


189
00:17:41,800 --> 00:17:43,680
Hm.


190
00:17:43,680 --> 00:17:47,720
You know, when you study the planet,
you're so used to seeing the big
events,


191
00:17:47,720 --> 00:17:50,960
like, I don't know, ice sheets
melting and volcanoes erupting.


192
00:17:50,960 --> 00:17:54,360
But with the rise of
turbocharge grasses


193
00:17:54,360 --> 00:17:56,960
you've got something
that's the tiniest of events.


194
00:17:56,960 --> 00:18:00,360
It's something almost invisible
tucked away


195
00:18:00,360 --> 00:18:03,040
inside the leaf of a plant.


196
00:18:03,040 --> 00:18:07,000
It's what makes the story of plants
just so fascinating.


197
00:18:12,400 --> 00:18:16,600
The grasses had found a way
to survive the crisis.


198
00:18:22,480 --> 00:18:25,480
But forests still ruled the world.


199
00:18:29,920 --> 00:18:32,760
The huge trees had also survived.


200
00:18:36,640 --> 00:18:42,000
Then the underdog unleashed
a devastating new weapon.


201
00:18:53,560 --> 00:18:57,960
Eight million years ago,
by now the climate had altered.


202
00:18:58,960 --> 00:19:01,800
Much of the earth
was dryer than ever before.


203
00:19:04,920 --> 00:19:09,160
It was the moment
grasses had been waiting for.


204
00:19:14,720 --> 00:19:19,000
The grasses had evolved unique
properties that made them especially
flammable.


205
00:19:20,920 --> 00:19:24,360
When dry, they became like
a tinderbox.


206
00:19:25,360 --> 00:19:28,760
All they needed was the spark.


207
00:19:37,280 --> 00:19:42,400
Today there's an ideal place
to see what happened
eight million years ago.


208
00:19:49,160 --> 00:19:52,240
Here in the national parks
of South Africa,


209
00:19:52,240 --> 00:19:57,360
rangers deliberately start huge
fires to manage the land.


210
00:20:02,520 --> 00:20:08,920
And for me it's the perfect
opportunity to see how back then
grasses exploited fire.


211
00:20:09,920 --> 00:20:12,600
So, we've got a chopper
coming right down this line


212
00:20:12,600 --> 00:20:15,120
dropping incendiaries
all the way along here.


213
00:20:17,600 --> 00:20:20,560
Chief fire-starter is Chris Austin.


214
00:20:21,800 --> 00:20:25,760
He coordinates the helicopter crew
as they drop pellets onto the grass.


215
00:20:25,760 --> 00:20:28,440
Artificial lightning strikes.


216
00:20:31,520 --> 00:20:35,080
What'll happen is that they just sit
there, they just open up, ignite,


217
00:20:35,080 --> 00:20:36,880
and then you just see them erupt.


218
00:20:39,120 --> 00:20:43,600
Next 46 seconds,
which is quite a long time.
46 seconds? That's nice and precise.


219
00:20:43,600 --> 00:20:46,560
There we go. There's one.
There we go. Come and have a look.


220
00:20:46,560 --> 00:20:49,640
Yeah, there's probably another one
there. There it is.


221
00:20:49,640 --> 00:20:51,240
It should ignite now.


222
00:20:51,240 --> 00:20:53,960
There she goes. There.


223
00:20:53,960 --> 00:20:58,560
And then over here
we've got ourselves another one.


224
00:20:58,560 --> 00:21:02,160
So, this line, this whole line now,
is just gonna go up into a wall of
flames.


225
00:21:02,160 --> 00:21:03,200
Another one there.


226
00:21:03,200 --> 00:21:04,960
Is it safe now here?


227
00:21:04,960 --> 00:21:08,520
She's gonna go up slope, yeah?
She's gonna go away from us?


228
00:21:08,520 --> 00:21:11,400
Of course, if the wind's
pushing it, it'll accelerate.


229
00:21:11,400 --> 00:21:13,440
You can see it's
being pulled by the slope.


230
00:21:13,440 --> 00:21:16,280
Oh, I can feel it burning my face
already.


231
00:21:18,000 --> 00:21:20,640
Look at that. That's amazing.


232
00:21:21,880 --> 00:21:24,720
It's just a wall of smoke and flame.


233
00:21:24,720 --> 00:21:26,480
Unbelievable.


234
00:21:31,560 --> 00:21:36,400
The most aggressive fire
that I've seen moved at more than
three metres a second, which is...


235
00:21:36,400 --> 00:21:39,800
That's phenomenal. It's really
quick. You can't outrun it.


236
00:21:39,800 --> 00:21:43,840
The fires that kill people are
grassland fires, because they're
so fast-moving.


237
00:21:46,760 --> 00:21:48,520
And that's not all.


238
00:21:48,520 --> 00:21:53,240
Grass burns in a special way,
a way that was devastating to its
enemies.


239
00:21:57,240 --> 00:21:58,480
(GIGGLES)


240
00:21:58,480 --> 00:22:00,960
I've kind of fallen into it.


241
00:22:02,200 --> 00:22:05,360
To discover more about
its properties,


242
00:22:05,360 --> 00:22:08,600
I've volunteered to enter
into the heart of the fire.


243
00:22:09,880 --> 00:22:12,680
This stuff that's going in now
is not kind of medical monitoring.


244
00:22:12,680 --> 00:22:15,160
This is actually for monitoring
the temperatures of the fire.


245
00:22:15,160 --> 00:22:19,680
It's a thermocouple wire. It's gonna
go running down...in this case down
my leg.


246
00:22:19,680 --> 00:22:23,520
It's probably the first time
this has been done. First time
I've ever done this with a guy!


247
00:22:23,520 --> 00:22:25,280
(LAUGHS) First time you've put
your...


248
00:22:25,280 --> 00:22:28,000
First time you've put your hand
down a man's trousers.


249
00:22:28,000 --> 00:22:30,280
If you get stuck,
that's us virtually married.


250
00:22:30,280 --> 00:22:35,560
Once in the flames, we hope to
combine readings from the heat
sensors on my suit,


251
00:22:35,560 --> 00:22:37,720
with a thermal-imaging camera


252
00:22:37,720 --> 00:22:41,280
to reveal the secrets
of a grass fire.


253
00:22:46,200 --> 00:22:48,640
OXYGEN HISSES
The fire is picking up speed.


254
00:22:49,760 --> 00:22:54,560
I can't believe I'm seeing this.
It's starting to come towards us.


255
00:22:54,560 --> 00:22:58,120
This just seems like
one of the daftest things I've done.


256
00:23:07,640 --> 00:23:09,560
Look at the flames!


257
00:23:10,920 --> 00:23:13,840
Grass fires are very different
from other fires.


258
00:23:13,840 --> 00:23:17,480
The readings show
that the hottest area of the fire,


259
00:23:17,480 --> 00:23:19,120
the white parts on this image,


260
00:23:19,120 --> 00:23:22,880
is not in the burning grass
but a metre above it.


261
00:23:25,000 --> 00:23:29,400
The temperature here
is over 360 degrees.


262
00:23:30,680 --> 00:23:32,760
OXYGEN HISSING


263
00:23:32,760 --> 00:23:35,120
Grass ignites more easily
than other plants


264
00:23:35,120 --> 00:23:38,880
and it's transformed into
a volatile gas.


265
00:23:41,960 --> 00:23:46,520
This grass rises and burns
even hotter than the grass itself,


266
00:23:46,520 --> 00:23:50,880
making it one of the fiercest
and fastest fires in nature.


267
00:23:50,880 --> 00:23:53,000
OXYGEN HISSING


268
00:24:02,000 --> 00:24:04,400
SIGHS AND SNORTS


269
00:24:05,720 --> 00:24:08,240
OXYGEN HISSES
Ah.


270
00:24:10,560 --> 00:24:13,000
Oh, I know this feels...
It sounds really strange,


271
00:24:13,000 --> 00:24:16,040
but it was actually
quite a privilege to be in there.


272
00:24:16,040 --> 00:24:18,640
You know, normally
if you're stuck in one of them,


273
00:24:18,640 --> 00:24:20,400
you just don't come out.


274
00:24:20,400 --> 00:24:24,560
It's great, at one point, the flames
came up, and I just looked down,


275
00:24:24,560 --> 00:24:27,600
and it was just lapping against the
mask.


276
00:24:27,600 --> 00:24:30,440
SNORTS
You kind of feel sorry
for the trees.


277
00:24:58,800 --> 00:25:02,840
The next day, the fire still
smoulders.


278
00:25:02,840 --> 00:25:05,520
It's so strange.


279
00:25:05,520 --> 00:25:09,480
Why did grasses evolve
to encourage fires to take hold...


280
00:25:10,880 --> 00:25:14,200
...ripping through the landscape
and destroying plant life?


281
00:25:15,240 --> 00:25:18,480
It seems suicidal.


282
00:25:19,520 --> 00:25:22,440
Grasses don't just
encourage fires to start.


283
00:25:22,440 --> 00:25:24,560
They're also designed
to survive them.


284
00:25:24,560 --> 00:25:28,200
In fact, they're the most
fire-resistant plant on earth


285
00:25:28,200 --> 00:25:30,920
and you can see here,
this all looks scorched.


286
00:25:30,920 --> 00:25:34,360
How can it still... Look at the
charcoal and smoke there.


287
00:25:34,360 --> 00:25:38,480
But the thing is, if you just peel
this back, you quickly find that...


288
00:25:38,480 --> 00:25:41,200
Look at that.
A lot of that's still alive.


289
00:25:42,160 --> 00:25:44,880
In fact the trick, really,


290
00:25:44,880 --> 00:25:48,200
the solution to why grasses can
survive isn't on the surface.


291
00:25:48,200 --> 00:25:50,000
It's just below the surface.


292
00:25:50,000 --> 00:25:56,880
Cos if you open up these stalks,
you can see that right here
is a little bud.


293
00:25:56,880 --> 00:26:00,640
It's stuck under a...
a kind of insulated thick coating.


294
00:26:00,640 --> 00:26:03,640
It's kind of tucked away
in its underground bunker.


295
00:26:03,640 --> 00:26:06,080
It's still alive.


296
00:26:06,080 --> 00:26:09,080
So, you look around here and you
just think everything's dead.


297
00:26:09,080 --> 00:26:11,560
And that tree...
that tree certainly is.


298
00:26:11,560 --> 00:26:16,440
But the grass...the grass
is just biding its time.
It's very much alive.


299
00:26:19,280 --> 00:26:24,600
You know, this scene...
this could easily be a scene
from eight million years ago


300
00:26:24,600 --> 00:26:29,080
where the grasses just really
quickly recover and recolonise.


301
00:26:29,080 --> 00:26:33,520
And the sneaky bit is they do it
much faster than trees.


302
00:27:02,600 --> 00:27:06,880
In the wake of this onslaught,
the forest started breaking up.


303
00:27:10,440 --> 00:27:13,720
The grasses were on a land grab,


304
00:27:13,720 --> 00:27:17,360
conquering the territory
once held by the trees.


305
00:27:25,960 --> 00:27:29,360
The expanding grasses turned the
earth into a flammable planet,


306
00:27:29,360 --> 00:27:31,160
a...a fireball world.


307
00:27:31,160 --> 00:27:34,360
It must have seen
about a million trees burned


308
00:27:34,360 --> 00:27:38,440
and black ash filled the sky
for hundreds of thousands of years.


309
00:27:38,440 --> 00:27:41,760
And for the trees,
this was apocalypse.


310
00:27:51,320 --> 00:27:53,640
The world was ablaze.


311
00:27:54,920 --> 00:27:59,480
The challenger had sparked a
revolution that was changing
the face of the planet.


312
00:28:10,920 --> 00:28:16,200
But the global rise of grasses
wasn't just reshaping plant life.


313
00:28:16,200 --> 00:28:19,880
It was transforming
the animal kingdom too.


314
00:28:20,880 --> 00:28:24,520
So, how do we know this?


315
00:28:43,480 --> 00:28:46,480
The effects of the spreading grasses
have been revealed by...


316
00:28:46,480 --> 00:28:49,480
not one of the most elegant pieces
of forensic science.


317
00:28:49,480 --> 00:28:52,760
Part of the evidence had been
discovered here in North America


318
00:28:52,760 --> 00:28:55,600
and it comes literally straight
from the horse's mouth.


319
00:28:55,600 --> 00:28:57,320
Come on.


320
00:28:57,320 --> 00:28:58,840
HORSE SNORTS
Whoa!


321
00:29:03,120 --> 00:29:04,840
IAIN GRUNTS


322
00:29:06,960 --> 00:29:08,920
When an animal eats a plant,


323
00:29:08,920 --> 00:29:12,640
the carbon of the plant
is absorbed into its teeth.


324
00:29:12,640 --> 00:29:17,320
Studying the teeth tells you
whether the herbivore has eaten
the leaves of trees...


325
00:29:17,320 --> 00:29:18,960
or the new grasses.


326
00:29:18,960 --> 00:29:20,960
Yeah.


327
00:29:20,960 --> 00:29:22,520
All right?


328
00:29:22,520 --> 00:29:28,080
And the fossil teeth
from millions of years ago
tell a remarkable story.


329
00:29:31,560 --> 00:29:35,560
This is the result of the scientific
analysis of tooth enamel


330
00:29:35,560 --> 00:29:38,040
from herbivores in North America.


331
00:29:38,040 --> 00:29:41,880
You can see down here this is us
going back in time in millions
of years.


332
00:29:41,880 --> 00:29:45,000
Now, the thing is, up to about eight
million years to about here


333
00:29:45,000 --> 00:29:48,400
you can see that herbivores
are largely eating shrubs and trees.


334
00:29:48,400 --> 00:29:50,440
But then there's
a really dramatic change


335
00:29:50,440 --> 00:29:52,760
between seven
and six million years ago.


336
00:29:52,760 --> 00:29:55,120
And, after that,
they're eating grasses.


337
00:29:55,120 --> 00:29:58,800
And the thing is, this sudden
switchover isn't confined
to North America.


338
00:29:58,800 --> 00:30:01,200
Here's a graph for South America.


339
00:30:01,200 --> 00:30:04,880
And here's a graph for Africa
and also for Asia.


340
00:30:04,880 --> 00:30:07,200
You put them together. Look at that.


341
00:30:08,440 --> 00:30:10,640
What these graphs tell
is the same story


342
00:30:10,640 --> 00:30:15,040
and that is in a period of about
one million years,
a geological instant,


343
00:30:15,040 --> 00:30:18,400
the world's herbivores
dramatically change their diet,


344
00:30:18,400 --> 00:30:20,640
so that they're eating
the new grasses.


345
00:30:28,080 --> 00:30:32,200
This discovery proves that,
by six million years ago,


346
00:30:32,200 --> 00:30:34,520
grasses were dominating the land.


347
00:30:40,600 --> 00:30:44,840
It was a domination that would have
striking consequences for many
animals...


348
00:30:50,280 --> 00:30:52,120
INSECT BUZZES


349
00:30:59,120 --> 00:31:04,520
...and it involved another piece
of clever engineering
from the grasses.


350
00:31:09,920 --> 00:31:13,640
Ah, this is it. This is the stuff
that I've been looking for.


351
00:31:13,640 --> 00:31:17,400
This is the sharp stuff.
I'm pretty sure of it.


352
00:31:17,400 --> 00:31:19,160
Let's have a little look.


353
00:31:21,480 --> 00:31:23,960
Ah, you...


354
00:31:23,960 --> 00:31:25,600
Ooh. Oh.


355
00:31:25,600 --> 00:31:28,200
That's something
we've all done in the past.


356
00:31:28,200 --> 00:31:30,680
Cut ourselves on a blade of grass.


357
00:31:30,680 --> 00:31:32,440
Look at that.


358
00:31:32,440 --> 00:31:34,120
I'm bleeding.


359
00:31:34,120 --> 00:31:36,640
But have you ever wondered
why that happens?


360
00:31:36,640 --> 00:31:39,320
It's actually all to do
with something that coats


361
00:31:39,320 --> 00:31:40,480
the edge of the leaf.


362
00:31:48,800 --> 00:31:52,840
Grass extracts a mineral
called silica from the soil.


363
00:31:56,200 --> 00:32:01,000
The silica is built into row upon
row of tiny daggers along the leaf.


364
00:32:04,320 --> 00:32:07,680
It's a defence to discourage
animals from eating it.


365
00:32:11,600 --> 00:32:13,520
Although tiny,


366
00:32:13,520 --> 00:32:19,120
these weapons led to one of the
biggest extinctions of mammals
in Earth's history.


367
00:32:21,120 --> 00:32:24,120
The world had been full
of many different plant eaters


368
00:32:24,120 --> 00:32:26,800
including the vast balachetherium.


369
00:32:26,800 --> 00:32:28,800
SNORTING AND GROWLING


370
00:32:30,200 --> 00:32:34,080
These 20-tonne beasts were the
largest mammals ever to exist.


371
00:32:35,120 --> 00:32:37,880
They fed off trees and shrubs.


372
00:32:37,880 --> 00:32:41,680
But, as their food source
disappeared, these animals died out.


373
00:32:43,440 --> 00:32:46,520
SNORTING AND GROWLING


374
00:32:50,720 --> 00:32:52,720
In North America alone,


375
00:32:52,720 --> 00:32:57,600
grasses led to the extinction
of over half of all plant-eating
mammals.


376
00:33:02,240 --> 00:33:04,400
But some herbivores thrived.


377
00:33:07,120 --> 00:33:09,680
It's all down to the teeth again.


378
00:33:09,680 --> 00:33:12,840
Who would have thought
that gnashers could be so important?


379
00:33:12,840 --> 00:33:16,280
You can see how the survivors coped,
with this skull here.


380
00:33:16,280 --> 00:33:21,040
They developed harder teeth to bite
through that silica-edged grass.


381
00:33:21,040 --> 00:33:26,040
And also longer grinding teeth so
that it didn't matter if they got
worn down.


382
00:33:26,040 --> 00:33:28,440
The creatures adapted.


383
00:33:28,440 --> 00:33:33,360
And this is one of the results,
the jaw of a modern-day horse,
like Tank here.


384
00:33:43,080 --> 00:33:44,760
By six million years ago,


385
00:33:44,760 --> 00:33:49,040
the triumph of grasses had caused
the death of many types of animals,


386
00:33:49,040 --> 00:33:52,960
while creating vast herds
of new ones,


387
00:33:52,960 --> 00:33:56,760
the more familiar plant eaters
we know today.


388
00:34:02,480 --> 00:34:06,200
ELEPHANTS TRUMPETING
But that's just the start.


389
00:34:06,200 --> 00:34:09,840
Because if you've got herbivores
consuming silica-rich grasses,


390
00:34:09,840 --> 00:34:13,400
all that mineral
has to go somewhere...


391
00:34:15,840 --> 00:34:17,840
...as manure.


392
00:34:17,840 --> 00:34:23,720
The herds of herbivores were
producing millions of tonnes of
manure every day.


393
00:34:27,400 --> 00:34:29,640
It's washed away into rivers...


394
00:34:31,040 --> 00:34:33,840
...until finally it reached
the ocean.


395
00:34:35,360 --> 00:34:38,920
And within it was all that silica.


396
00:34:44,240 --> 00:34:49,000
It's out in the oceans that things
really began to take off.


397
00:34:49,000 --> 00:34:51,760
Because it's out here
that there's creatures


398
00:34:51,760 --> 00:34:54,680
that are addicted to this silica.


399
00:34:57,320 --> 00:35:00,000
These creatures are microscopic...


400
00:35:01,200 --> 00:35:03,760
...a few hundredths
of a millimetre across.


401
00:35:05,400 --> 00:35:09,360
They're diatoms,
a type of green algae.


402
00:35:11,240 --> 00:35:16,760
Diatoms are wonderfully delicate,
like some kind of alien
architecture.


403
00:35:20,560 --> 00:35:25,160
But essential for the construction
of their tiny skeletons is silica.


404
00:35:29,160 --> 00:35:30,600
Five million years ago,


405
00:35:30,600 --> 00:35:34,800
they were feasting on huge amounts
of silica from the grasses.


406
00:35:38,760 --> 00:35:41,600
For the diatoms,
it was like Christmas.


407
00:35:41,600 --> 00:35:43,640
Their numbers exploded.


408
00:35:51,760 --> 00:35:56,040
And diatoms are crucial because they
form the foundation of the ocean's
food chain.


409
00:35:57,560 --> 00:36:02,920
With more diatoms came huge shoals
of anchovies and herring
that eat them.


410
00:36:02,920 --> 00:36:07,440
This in turn attracts predators
like seabirds and dolphins


411
00:36:07,440 --> 00:36:09,480
and even bigger hunters.


412
00:36:16,520 --> 00:36:20,680
But it's from space you really
appreciate their importance.


413
00:36:20,680 --> 00:36:23,280
They appear as vast green blooms.


414
00:36:25,360 --> 00:36:28,720
When they bloom, they cover
over a tenth of the oceans.


415
00:36:29,800 --> 00:36:34,320
They're green because like plants
diatoms contain chlorophyll


416
00:36:34,320 --> 00:36:38,280
and like plants
they all release oxygen.


417
00:36:38,280 --> 00:36:40,720
SQUAWKING


418
00:36:43,720 --> 00:36:46,160
Those photosynthesising diatoms


419
00:36:46,160 --> 00:36:49,120
produce about a quarter
of the oxygen in the atmosphere.


420
00:36:49,120 --> 00:36:53,280
So, if you like, every fourth breath
you take on average


421
00:36:53,280 --> 00:36:55,440
has been exhaled by the diatoms.


422
00:36:56,400 --> 00:36:59,400
They really are the lungs of
the ocean.


423
00:37:02,800 --> 00:37:08,040
It's remarkable what the humble
grasses had achieved by
five million years ago.


424
00:37:11,200 --> 00:37:15,320
A once-forested planet
was now dominated by open plains.


425
00:37:22,720 --> 00:37:27,960
8,000 different species of grasses
covering a quarter of all land.


426
00:37:29,000 --> 00:37:30,960
ELEPHANTS TRUMPET


427
00:37:30,960 --> 00:37:34,280
They'd selected
which animals would live or die.


428
00:37:38,400 --> 00:37:42,320
And they'd fundamentally
altered the oceans


429
00:37:42,320 --> 00:37:45,160
playing a crucial role
in the make-up of our atmosphere.


430
00:37:50,800 --> 00:37:56,080
Yet perhaps the most important
impact of this remarkable plant
was still to come.


431
00:38:02,920 --> 00:38:05,600
The impact on our story.


432
00:38:08,320 --> 00:38:10,480
Human beings.


433
00:38:17,120 --> 00:38:21,080
And that's why I've come to
the savanna of West Africa.


434
00:38:24,400 --> 00:38:28,280
I'm in Senegal to see
a scientific first.


435
00:38:28,280 --> 00:38:30,800
It's a discovery that's got
profound implications


436
00:38:30,800 --> 00:38:33,280
for our understanding
of our own past,


437
00:38:33,280 --> 00:38:37,800
because it's here in Africa that
our earliest ape ancestors emerged.


438
00:38:40,560 --> 00:38:42,240
Five million years ago,


439
00:38:42,240 --> 00:38:45,880
why did one group of apes
leave the trees for the savanna


440
00:38:45,880 --> 00:38:49,880
and develop so differently,
eventually becoming human?


441
00:38:49,880 --> 00:38:54,960
Well, the chimpanzees here
might provide some answers.


442
00:38:54,960 --> 00:38:57,920
Because unlike almost all
other chimps in Africa,


443
00:38:57,920 --> 00:39:01,520
the ones here in Fongoli
live on grasslands.


444
00:39:03,760 --> 00:39:06,240
Jill! Heh-hey! Hey! Welcome.


445
00:39:06,240 --> 00:39:07,320
I'm Iain.


446
00:39:07,320 --> 00:39:11,520
It's what makes them so fascinating
to anthropologist Jill Pruetz.


447
00:39:11,520 --> 00:39:14,040
All this is HQ, chimp HQ?
Yeah, this is home base.


448
00:39:14,040 --> 00:39:16,920
Every day we take off
wherever they're at.


449
00:39:21,040 --> 00:39:24,640
Jill has spent ten years
studying the Fongoli chimps.


450
00:39:30,960 --> 00:39:35,600
She's most interested in parallels
between the unusual behaviours of
these chimps


451
00:39:35,600 --> 00:39:38,840
and what might have happened
during the evolution of human
beings.


452
00:39:38,840 --> 00:39:41,440
Settled round the waterhole
like that.


453
00:39:41,440 --> 00:39:43,640
CHIMPS SCREECHING


454
00:39:50,320 --> 00:39:51,600
I wasn't expecting that.


455
00:39:51,600 --> 00:39:54,760
I guess I was expecting them
kind of swinging through the trees.


456
00:39:54,760 --> 00:39:57,560
But look at them. They're just
ambling along on all fours.


457
00:39:57,560 --> 00:40:03,320
Perfectly happy down here on the
ground walking through the grass.


458
00:40:03,320 --> 00:40:06,880
And they look so human.
I know, it's obvious.
Really obvious thing to say.


459
00:40:06,880 --> 00:40:09,480
But they just look so human.


460
00:40:13,720 --> 00:40:17,120
The Fongoli chimps
have other human attributes.


461
00:40:19,880 --> 00:40:24,200
They are proficient at using tools
like sticks for collecting termites.


462
00:40:26,480 --> 00:40:28,920
Many chimps in Africa
catch termites this way,


463
00:40:28,920 --> 00:40:33,240
although these chimps do it
more than any others.


464
00:40:38,240 --> 00:40:44,200
But what makes them really special
is a hunting technique,
one that is unique.


465
00:40:45,760 --> 00:40:48,840
I think that probably
the most exciting discovery made


466
00:40:48,840 --> 00:40:52,760
was that they hunt with tools, which
before we thought only humans did.


467
00:40:52,760 --> 00:40:54,040
How is that?


468
00:40:54,040 --> 00:40:57,280
They'll fashion branches
into sort of like a spear


469
00:40:57,280 --> 00:40:59,920
and they'll use it to jab
into these tree holes,


470
00:40:59,920 --> 00:41:03,080
where you have another kind
of primate, a bush baby.


471
00:41:03,080 --> 00:41:06,520
And then they jab it into the hole.


472
00:41:07,560 --> 00:41:09,960
Jill's filmed
this remarkable behaviour,


473
00:41:09,960 --> 00:41:12,920
the first time
it's ever been recorded.


474
00:41:15,960 --> 00:41:21,240
It shows a chimp using a spear he's
made to stab and kill a mammal,


475
00:41:21,240 --> 00:41:23,040
a bush baby.


476
00:41:27,880 --> 00:41:31,280
Yeah, that was something that...
again, we used to define humans.


477
00:41:31,280 --> 00:41:34,880
Really? Yeah. See, that's starting
to blur the boundaries. Yeah.


478
00:41:39,920 --> 00:41:41,680
CHIMPS SCREECHING


479
00:41:47,080 --> 00:41:49,760
The chimps of Fongoli
are the only ones in the world


480
00:41:49,760 --> 00:41:53,240
that have been observed
using spears to hunt mammals.


481
00:41:53,240 --> 00:41:55,240
CHIMPS SCREECHING


482
00:41:56,480 --> 00:41:59,280
Jill believes they've had to
come up with this behaviour


483
00:41:59,280 --> 00:42:02,120
to cope with the harsh and dry
grasslands.


484
00:42:04,320 --> 00:42:07,880
It's a more hostile habitat
than the forest


485
00:42:07,880 --> 00:42:10,480
so the chimps here
have to be smarter.


486
00:42:15,120 --> 00:42:20,040
And Jill has discovered a final
extraordinary behaviour of
these chimps.


487
00:42:20,040 --> 00:42:22,880
BIRDSONG


488
00:42:25,480 --> 00:42:31,120
It also reveals more about how our
ancient ancestors might have evolved


489
00:42:31,120 --> 00:42:32,880
as they moved out of the forests.


490
00:42:35,440 --> 00:42:38,800
This is a nice one, I think,
from the wet season.


491
00:42:38,800 --> 00:42:42,160
So, this is a grassland. I can see
a group of them in there.


492
00:42:42,160 --> 00:42:45,920
There are three, four of them. You
can see 'em just above the grass.


493
00:42:45,920 --> 00:42:49,280
But watch...
watch what they'll need to do here.


494
00:42:53,240 --> 00:42:58,080
(LAUGHS) One of them just stood up!


495
00:42:58,080 --> 00:43:01,000
I mean, he obviously has to do that
to see over the grass.


496
00:43:01,000 --> 00:43:04,080
I want to see that again.
Yeah, let me see that.


497
00:43:14,320 --> 00:43:18,000
Many scientists think this is
perhaps a mirror of what happened


498
00:43:18,000 --> 00:43:22,240
as our own forebears stood up on the
grasslands for the first time.


499
00:43:24,160 --> 00:43:28,040
It allowed them to keep an eye out
for predators and prey...


500
00:43:29,920 --> 00:43:33,080
...and eventually to evolve walking.


501
00:43:33,080 --> 00:43:37,520
That's incredible to see chimps in
the wild standing proud in
the savanna grassland.


502
00:43:37,520 --> 00:43:40,560
Yeah, yeah. And looking
incredibly comfortable as well.


503
00:43:40,560 --> 00:43:42,440
It's exciting to see it.


504
00:43:43,800 --> 00:43:47,840
It's the grasslands that's driving
and encouraging them to...
develop that way.


505
00:43:47,840 --> 00:43:52,920
What, to be more resourceful,
more resilient? I think so. They
have to be creative and resilient.


506
00:43:52,920 --> 00:43:58,160
I've just got this weird feeling
that I'm looking at a bit of video
from four, five million years ago.


507
00:43:58,160 --> 00:44:01,400
Do you know what I mean?
That could be the scene. Mm-hm.


508
00:44:03,400 --> 00:44:07,960
Here at Fongoli you can actually see
what scientists think happened


509
00:44:07,960 --> 00:44:10,640
when grasses shaped
our ancient ancestors


510
00:44:10,640 --> 00:44:15,360
and encouraged them to make those
first upright steps onto
the savanna.


511
00:44:15,360 --> 00:44:19,160
And it really brings home how
our human journey


512
00:44:19,160 --> 00:44:21,280
began on the grasslands.


513
00:44:40,640 --> 00:44:46,360
Over the next five million years,
these ape men continued to evolve
in Africa...


514
00:44:48,760 --> 00:44:52,400
...until eventually
they became homo sapiens.


515
00:44:54,160 --> 00:44:58,560
And then 100,000 years ago,
these new people,


516
00:44:58,560 --> 00:45:02,120
for they really were people now,
like you and me,


517
00:45:02,120 --> 00:45:04,760
began to migrate
across the rest of the world.


518
00:45:07,280 --> 00:45:12,080
At this point in time,
our ancestors were hunter-gatherers.


519
00:45:14,160 --> 00:45:17,600
They were living a tough life
in small family groups,


520
00:45:17,600 --> 00:45:21,600
killing wild animals and collecting
berries and roots to eat.


521
00:45:23,120 --> 00:45:25,600
But grasses hadn't finished
with us...


522
00:45:26,680 --> 00:45:32,760
...because they'd trigger the
greatest revolution in humankind's
existence.


523
00:45:40,360 --> 00:45:42,800
SCRAPES EARTH


524
00:45:47,200 --> 00:45:50,480
It's not in Africa
but here in southern Turkey


525
00:45:50,480 --> 00:45:55,400
that archaeologists believe they've
discovered why that revolution
happened.


526
00:45:58,080 --> 00:46:01,160
The place is called Gobekli Tepe.


527
00:46:04,920 --> 00:46:09,720
For me, this is one of the most
exciting sites of modern
archaeology,


528
00:46:09,720 --> 00:46:13,320
because here at Gobekli Tepe are
some of the oldest buildings
in the world.


529
00:46:13,320 --> 00:46:17,120
They date to nearly three times the
age of the first Egyptian pyramids.


530
00:46:17,120 --> 00:46:19,600
And there's a real...
there's a real mystery here.


531
00:46:19,600 --> 00:46:21,400
Who built this place?


532
00:46:21,400 --> 00:46:25,040
And more importantly,
how could they have done it?


533
00:46:40,800 --> 00:46:45,360
This astonishing structure
is 12,000 years old.


534
00:46:46,320 --> 00:46:50,000
It lay buried and undiscovered
until 1994.


535
00:46:52,400 --> 00:46:54,520
Hello.


536
00:46:54,520 --> 00:46:55,960
Hello again.


537
00:46:55,960 --> 00:46:58,760
The archaeologist who
unearthed it is Klaus Schmidt.


538
00:46:58,760 --> 00:47:03,120
It's great to be here.
Welcome in enclosure C. Enclosure C!


539
00:47:03,120 --> 00:47:08,120
What a place! It's spectacular,
isn't it? I mean, these are great.


540
00:47:08,120 --> 00:47:09,800
Big question is, "who were they"?


541
00:47:09,800 --> 00:47:14,520
One thing is very important.
Never a face is depicted.
They are always faceless.


542
00:47:14,520 --> 00:47:18,040
I saw you working on a very
sophisticated one here. Yeah.


543
00:47:18,040 --> 00:47:19,640
This looks amazing. What is it?


544
00:47:19,640 --> 00:47:23,520
It's a masterpiece of craftsmanship.
It's made from one stone.


545
00:47:23,520 --> 00:47:25,280
And we have a flat relief of a boar,


546
00:47:25,280 --> 00:47:27,880
and we have this high relief
of a leopard.


547
00:47:27,880 --> 00:47:30,440
This is an extremely complex
society.


548
00:47:30,440 --> 00:47:33,600
Yes, and this is a surprise.
We didn't expect this.


549
00:47:33,600 --> 00:47:38,480
What we are doing here, we are at
a chapter in world history,


550
00:47:38,480 --> 00:47:41,200
a chapter which we didn't know
existed before.


551
00:47:41,200 --> 00:47:42,240
Yeah.


552
00:47:45,240 --> 00:47:49,400
To construct Gobekli Tepe
with its 50-tonne megaliths


553
00:47:49,400 --> 00:47:53,240
would have needed a huge army
of well-organised workers.


554
00:47:57,680 --> 00:48:01,480
Yet 12,000 years ago
was the Stone Age,


555
00:48:01,480 --> 00:48:04,360
a time when people were supposed
to be hunter-gatherers


556
00:48:04,360 --> 00:48:06,680
living in small groups.


557
00:48:09,360 --> 00:48:15,320
How did they sustain the numbers
essential to build such
a vast temple?


558
00:48:23,320 --> 00:48:26,680
The answer lies
a short distance away.


559
00:48:43,200 --> 00:48:48,160
Within sight of Gobekli Tepe
are the Karacadag Mountains.


560
00:48:48,160 --> 00:48:52,800
Here something happened at this time
that would change our world forever.


561
00:48:59,360 --> 00:49:03,280
It was all to do with
one particular type of grass.


562
00:49:05,400 --> 00:49:10,520
It's an ancient type of wheat
which grew totally wild,
just as it does today.


563
00:49:10,520 --> 00:49:12,760
It's called einkorn wheat.


564
00:49:16,760 --> 00:49:21,360
12,000 years ago
was a time before farming.


565
00:49:21,360 --> 00:49:25,640
The people here would have been
desperate for whatever nutrition
they could gather.


566
00:49:30,400 --> 00:49:33,400
Yet collecting it
presented a huge problem.


567
00:49:33,400 --> 00:49:35,640
Let me show you why.


568
00:49:36,640 --> 00:49:40,120
When the head of the wheat's ripe,
then just the tiniest of touches,


569
00:49:40,120 --> 00:49:41,880
and look what happens.


570
00:49:41,880 --> 00:49:44,280
It just scatters everywhere.


571
00:49:48,080 --> 00:49:52,280
And that's because the seed is
attached to the plant so
precariously.


572
00:49:52,280 --> 00:49:55,600
Imagine if you were trying to
collect enough seed for a meal.


573
00:49:55,600 --> 00:49:57,800
I mean, I can hardly even see
where they are.


574
00:49:57,800 --> 00:50:00,480
There's one. Ah, don't...


575
00:50:00,480 --> 00:50:02,240
It would drive you mad.


576
00:50:10,280 --> 00:50:13,880
Frankly, it's hard to believe
anyone would bother.


577
00:50:13,880 --> 00:50:19,080
But everything was about to change,
triggered by a crucial event.


578
00:50:21,040 --> 00:50:25,400
A tiny alteration in the genetic
makeup of a wild wheat plant.


579
00:50:26,400 --> 00:50:28,200
Just one gene.


580
00:50:28,200 --> 00:50:31,200
In just one single plant.


581
00:50:31,200 --> 00:50:33,520
CHILDREN CHATTER


582
00:50:36,560 --> 00:50:40,240
That mutation
has been traced back to here,


583
00:50:40,240 --> 00:50:42,360
just 30 kilometres
from Gobekli Tepe.


584
00:50:47,000 --> 00:50:48,040
If you look closely


585
00:50:48,040 --> 00:50:51,800
you can see the difference
between the two types of wheat.


586
00:50:55,840 --> 00:50:57,960
In the original wild wheat,


587
00:50:57,960 --> 00:51:02,360
a special ridge of cells between
the stalk and the seed breaks down


588
00:51:02,360 --> 00:51:04,840
as the plant ripens


589
00:51:04,840 --> 00:51:07,480
and this allows the seed
to fall away.


590
00:51:10,480 --> 00:51:15,720
But in the wheat with the genetic
mutation these cells remain
as a solid band.


591
00:51:20,000 --> 00:51:23,440
It means the new wheat
never lets go of its seeds.


592
00:51:25,720 --> 00:51:29,080
Under normal circumstances in the
wild that would doom the plant,


593
00:51:29,080 --> 00:51:31,400
because it just couldn't
scatter the seeds.


594
00:51:31,400 --> 00:51:33,840
Look, you bang it
and nothing happens.


595
00:51:33,840 --> 00:51:39,880
But it turns out that for one animal
species this trait
was really beneficial.


596
00:51:39,880 --> 00:51:40,960
Us.


597
00:51:56,280 --> 00:51:58,600
LOW CHATTER


598
00:52:05,080 --> 00:52:08,400
Because the seed remained on the
stalk after it had ripened,


599
00:52:08,400 --> 00:52:12,200
it meant that not only could the
people who lived here collect
more grain,


600
00:52:12,200 --> 00:52:13,920
they could also begin to farm it.


601
00:52:13,920 --> 00:52:17,680
In other words they could take
some of the spare seeds
at the end of a season,


602
00:52:17,680 --> 00:52:21,800
put it back in the ground
and then harvest the new plants
the following year.


603
00:52:21,800 --> 00:52:24,720
It was the dawn of
domesticated wheat.


604
00:52:38,960 --> 00:52:41,920
And this wheat gave us bread.


605
00:52:43,400 --> 00:52:46,160
A fabulously concentrated form
of energy.


606
00:52:46,160 --> 00:52:50,120
It could be carried, it could be
divided up, it could be stored.


607
00:52:52,200 --> 00:52:56,000
And in turn, bread would lead
to something even bigger.


608
00:53:03,680 --> 00:53:06,120
In order to build Gobekli Tepe,


609
00:53:06,120 --> 00:53:10,200
the Stone Age people turned their
back on hunter-gathering.


610
00:53:13,120 --> 00:53:15,920
They became the first farmers.


611
00:53:20,000 --> 00:53:24,160
12,000 years ago, they began
to sustain themselves with bread...


612
00:53:25,400 --> 00:53:28,760
...made from the grass we call
wheat.


613
00:53:34,200 --> 00:53:36,320
Now they could feed
the huge workforce


614
00:53:36,320 --> 00:53:40,640
required to construct such a vast
and sophisticated temple.


615
00:53:43,160 --> 00:53:46,600
The mystery of Gobekli Tepe
was solved.


616
00:53:47,760 --> 00:53:52,240
People had been hunter-gatherers,
and now this site marks the end
of that time,


617
00:53:52,240 --> 00:53:54,960
the end of that period
and the beginning of a new age.


618
00:53:57,880 --> 00:54:01,480
So Gobekli Tepe is part of that
chain reaction? It's a cultural...


619
00:54:01,480 --> 00:54:03,400
The people in Gobekli Tepe...
Yeah.


620
00:54:03,400 --> 00:54:06,640
...are the first people having bread
also in their villages,


621
00:54:06,640 --> 00:54:08,840
not only here but also
in the villages.


622
00:54:08,840 --> 00:54:12,880
That's incredible to think
that these were the first people
to taste bread. Yeah.


623
00:54:12,880 --> 00:54:18,040
And the idea, then, that it was
bread that was the kind of energy
source, essentially, the sustenance.


624
00:54:18,040 --> 00:54:21,640
Exactly, exactly. It's a turning
point in world history.


625
00:54:39,560 --> 00:54:41,880
There's one last thing
that I find intriguing.


626
00:54:43,040 --> 00:54:46,840
Our ancestors must have felt
that they were the masters
of this new crop,


627
00:54:46,840 --> 00:54:49,560
in the same way that we still
feel today about farming.


628
00:54:49,560 --> 00:54:52,760
You know, we are in control of the
plants that we grow and harvest.


629
00:54:52,760 --> 00:54:56,520
But think of it for a minute
from the wheat's point of view.


630
00:54:56,520 --> 00:54:59,440
I mean, here's a plant
that's done something really clever.


631
00:54:59,440 --> 00:55:03,600
It's attracted an animal that's
prepared to sow it, to nurture it,


632
00:55:03,600 --> 00:55:07,280
to protect it from competitors
and scavengers.


633
00:55:07,280 --> 00:55:10,960
It's also prepared to disperse
its seed by hand


634
00:55:10,960 --> 00:55:13,400
without the plant
having to do a single thing.


635
00:55:15,320 --> 00:55:18,960
So, it begs the question,
who's using who?


636
00:55:31,520 --> 00:55:36,520
Human beings had now invented a way
of harnessing the power of plants


637
00:55:36,520 --> 00:55:40,600
and once invented
it could never be reversed


638
00:55:40,600 --> 00:55:45,000
because farming allowed us to come
together in bigger
and bigger groups,


639
00:55:45,000 --> 00:55:49,440
to build villages, towns,
and eventually cities.


640
00:56:01,560 --> 00:56:04,720
A world once dominated
by forests and dinosaurs


641
00:56:04,720 --> 00:56:07,000
had given way to a world
of our own making.


642
00:56:16,960 --> 00:56:21,440
I've always been fascinated
by how our planet changes over time,


643
00:56:21,440 --> 00:56:24,680
over the four and a half billion
years of Earth history.


644
00:56:24,680 --> 00:56:27,760
And what's astounding
is how important plants have been


645
00:56:27,760 --> 00:56:31,920
in changing that original
lifeless rock


646
00:56:31,920 --> 00:56:35,960
into this vital and vibrant world
that we live in today.


647
00:56:35,960 --> 00:56:37,240
Our home.


648
00:56:39,680 --> 00:56:44,200
Over this series we've seen how
plants gave us the oxygen
and the atmosphere.


649
00:56:47,440 --> 00:56:51,040
We've watched as the rise of flowers
painted a drab world


650
00:56:51,040 --> 00:56:52,840
with brilliant colour.


651
00:56:54,360 --> 00:56:57,960
And we've discovered how plants
shape the animal kingdom.


652
00:57:04,440 --> 00:57:09,120
And, for us, the humble grasses
play the most important role of all.


653
00:57:09,120 --> 00:57:12,520
They drove the rise
of our apelike ancestors


654
00:57:12,520 --> 00:57:17,200
and ultimately triggered
the birth of civilisation.


655
00:57:17,200 --> 00:57:21,040
Plants made us
and the world we live in.


656
00:57:33,040 --> 00:57:38,200
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