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Yes, this is home.
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This is Earth.
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Having trouble finding
a familiar continent?
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The past is another planet.
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Actually, many.
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I'm standing on the great
expanse of time that has elapsed
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since the Big Bang.
In order to think about it,
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we've compressed it all
into a single year.
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It's the early morning
of December 23
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on this Cosmic Calendar of ours,
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or about 350 million years ago,
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when our world was
a mere four billion years old.
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Earth looks so different.
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You might not
even know the place.
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The stars wouldn't help you.
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Even the constellations would
have been different back then.
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The dinosaurs were still
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more than 100 million years
in the future.
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There were no birds,
no flowers.
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And the air was different, too.
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The atmosphere had more oxygen
than at any other time
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in Earth's history,
before or since.
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This allowed insects to grow
much larger than they do today.
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How?
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Insects don't have lungs.
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Life-giving oxygen is taken
in through openings
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in the outside of their bodies
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and transported
through a network of tubes.
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If an insect were too large,
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the outer reaches of these tubes
would absorb all the oxygen
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before it could ever get
to its internal organs.
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But during
the Carboniferous Period,
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the atmosphere had almost twice
the oxygen as today.
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Insects could then grow
much bigger
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and still get enough oxygen
in their bodies.
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That's why the dragonflies here
are as big as eagles
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and the millipedes
the size of alligators.
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So why was there
so much oxygen back then?
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It was produced
by a new kind of life.
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What kind of
life could've changed
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the Earth's atmosphere
so dramatically?
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Plants that could reach
for the sky--
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trees.
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In their competition
for sunlight,
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trees evolved a way
to defy gravity.
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Before trees,
the tallest vegetation was
47
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only about waist-high.
48
00:04:04,967 --> 00:04:08,303
And then something wonderful
happened.
49
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A plant molecule evolved that
was both strong and flexible,
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a material that could support
a lot of weight,
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00:04:18,314 --> 00:04:21,550
yet bend in the wind
without breaking.
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Lignin made trees possible.
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Now life could build upward.
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And this opened
a whole new territory,
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a three-dimensional matrix
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for communities
far above the ground.
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Earth became
the Planet of the Trees.
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But lignin had a downside:
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it was hard to swallow.
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When nature's demolition crew,
the fungi and bacteria,
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tried to eat anything
with lignin in it,
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they got a really bad case
of indigestion.
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And termites wouldn't evolve
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for at least
another 100 million years.
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What to do
with all those dead trees?
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It took the fungi and bacteria
millions of years
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to evolve the biochemical means
to consume them.
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Meanwhile, the trees just kept
springing up,
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dying, falling over
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and getting buried by the mud
that built up over eons.
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Eventually, there were
hundreds of billions of trees
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entombed in the Earth,
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buried forests
all over the Earth.
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What possible harm
could come from that?
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00:05:32,822 --> 00:05:37,292
This cliff in Nova Scotia
is another kind of calendar.
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It tells the story
of that other world
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that once flourished right here.
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And this is the death mask
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of that 300 million-year-old
tree.
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It was cast by minerals
that replaced the original wood
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cell by cell--
in other words, a fossil.
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The tree surrendered
its organic molecules
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to the environment long ago,
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its carbon and water.
Only its shape remains.
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When this tree was alive,
it took in carbon dioxide
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and water and used sunlight
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to turn them
into energy-rich organic matter.
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The tree gave off oxygen
as a waste product.
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That's what trees
and other plants still do.
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When plants die, they decay,
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00:06:21,604 --> 00:06:23,738
and this reverses
the transaction.
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Their organic matter combines
with oxygen
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and decomposes,
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putting carbon dioxide
back into the air.
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This balances the books
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for the chemistry
of Earth's atmosphere.
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But if the trees are buried
before they can decay,
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two things happen...
they take the carbon
99
00:06:40,590 --> 00:06:43,625
and stored solar energy
with them
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and leave the oxygen behind
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to build up in the atmosphere.
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That's what happened
around 300 million years ago.
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There was an oxygen surplus.
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That's how the bugs got so big.
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And what became
of all that buried carbon?
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It lay there for eons
before dealing life on Earth
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00:07:01,644 --> 00:07:06,581
its most devastating blow
of all time.
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There are places on this planet
where you can walk through time
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and read the history
written in the rocks.
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This beach in Nova Scotia
is one of them.
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Every layer is a page.
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Each one tells the story
of a flood,
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one after another,
over millions of years.
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The layer cake of flood
deposits was slowly buried
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and turned into rock
by heat and pressure.
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The same forces
that built mountains
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then tilted and uplifted them,
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along with the entombed
fossil forest.
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The newer layers were always
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deposited on top
of the older ones.
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All the pages are
in the correct order,
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bearing witness
to what happened here
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over millions of years.
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Back that way
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lies the more distant past.
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And with every step I take,
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I move about 1,000 years
closer to the present
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and away from the world
of 300 million years ago.
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50 million years later
lies that way.
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This was the beginning of
the end of the Permian world,
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an event of unequalled carnage.
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The Permian
is the darkest corridor
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in this memorial to the broken
branches on the Tree of Life--
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the Halls of Extinction.
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Death has never come so close
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to reigning supreme
on this world
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in the quarter billion years
since.
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The eruptions,
in what is now Siberia,
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lasted for hundreds
of thousands of years.
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The lava flooded and buried more
than a million square miles.
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This event dwarfs
any volcanic eruption
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in historical times.
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00:09:01,056 --> 00:09:04,987
_
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00:09:11,541 --> 00:09:15,010
Huge quantities
of carbon dioxide came pouring
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out of the volcanic fissures.
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This greenhouse gas
warmed the climate.
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And this is where
the long-buried forests
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of the earlier Carboniferous
Period reenter the story.
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During the intervening
50 million years,
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those trees had turned
into immense deposits of coal,
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and as it happened,
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one of the world's largest
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accumulations of coal
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was buried right there
in Siberia.
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The heat from the lava
baked the coal,
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driving methane and sulfur-rich
gases out of the ground.
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They were laden
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00:09:46,843 --> 00:09:50,245
with toxic
and radioactive ash particles--
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00:09:50,279 --> 00:09:52,714
coal smoke.
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00:09:52,748 --> 00:09:56,485
This witch's brew
polluted the atmosphere
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00:09:56,519 --> 00:09:58,753
and radically destabilized
Earth's climate.
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A sulfuric acid haze
blocked incoming sunlight
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and darkened the planet.
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Global temperatures plummeted
to subfreezing.
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During lulls in the eruptions,
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the acid haze fell back
to the surface.
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But the carbon dioxide remained
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and built up in the atmosphere
to cause global warming.
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Years of frigid cold
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00:10:22,512 --> 00:10:25,747
alternating with millennia
of stifling heat
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battered a dwindling population
of plants and animals.
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They had no chance
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00:10:29,952 --> 00:10:34,356
to adapt to the drastic swings
in climate.
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As the global warming
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continued, the surface
and the bottom waters
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slowly mixed,
raising the temperature
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00:10:44,033 --> 00:10:46,468
of the once-frigid depths
of the sea floor.
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00:10:46,502 --> 00:10:48,170
Methane-rich ices
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00:10:48,204 --> 00:10:52,140
that had been frozen in
the sediments began to melt.
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Newly liberated methane gas
made its way to the surface
181
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and into the atmosphere.
182
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Methane traps heat
far more efficiently
183
00:11:03,886 --> 00:11:06,321
than carbon dioxide,
so the climate
184
00:11:06,355 --> 00:11:08,390
got even hotter.
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00:11:08,424 --> 00:11:10,392
And the methane also destroyed
186
00:11:10,426 --> 00:11:12,527
the ozone layer
in the stratosphere.
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The natural sunscreen
that protects life
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from deadly ultraviolet rays
was eaten away.
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The circulatory system
of the world ocean shut down.
190
00:11:23,673 --> 00:11:27,142
These stagnant waters
became oxygen-starved,
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killing almost all
the fish in the sea.
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00:11:29,579 --> 00:11:32,881
But one kind of life flourished
in this brutal environment...
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00:11:32,915 --> 00:11:36,518
bacteria that produced
deadly hydrogen sulfide gas
194
00:11:36,552 --> 00:11:38,753
as a waste product.
195
00:11:38,788 --> 00:11:41,656
That was the last straw.
196
00:11:41,691 --> 00:11:45,093
The poison gas killed almost
all the remaining plants
197
00:11:45,127 --> 00:11:47,562
and animals on the land.
198
00:11:47,597 --> 00:11:50,732
This was the Great Dying.
199
00:11:50,766 --> 00:11:54,736
The closest life on Earth
has ever come to annihilation.
200
00:11:54,770 --> 00:11:58,440
Nine in ten
of all species perished.
201
00:11:58,474 --> 00:12:01,042
It took a long time
for life to bounce back.
202
00:12:01,077 --> 00:12:04,579
For a few million years,
Earth could have been called
203
00:12:04,614 --> 00:12:06,548
the Planet of the Dead.
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00:12:06,582 --> 00:12:10,185
We are descended
from one of the few species
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00:12:10,219 --> 00:12:12,087
that managed to squeak by.
206
00:12:14,757 --> 00:12:18,226
You are human and alive
at this very moment
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00:12:18,261 --> 00:12:20,896
because they managed
to endure, conveying
208
00:12:20,930 --> 00:12:24,032
their DNA through one of
the most treacherous periods
209
00:12:24,066 --> 00:12:26,234
in the history of life.
210
00:12:40,433 --> 00:12:44,035
This mountain
was made entirely by life.
211
00:12:44,070 --> 00:12:46,271
The life that flourished
back in the glory days
212
00:12:46,305 --> 00:12:49,707
of the Permian,
before all hell broke loose.
213
00:12:49,742 --> 00:12:51,676
This is part
of the 400 mile-long
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00:12:51,711 --> 00:12:53,778
Guadalupe Mountain chain
that runs through
215
00:12:53,813 --> 00:12:55,613
Texas and New Mexico.
216
00:12:55,648 --> 00:12:59,017
It's the world's
largest fossil reef.
217
00:12:59,051 --> 00:13:02,053
All this was once
a great inland sea.
218
00:13:02,088 --> 00:13:06,424
The reef flourished and grew
for millions of years,
219
00:13:06,459 --> 00:13:09,794
and was home to multitudes
of sponges, green algae,
220
00:13:09,829 --> 00:13:12,397
and animals too small to see.
221
00:13:12,431 --> 00:13:14,399
When these creatures died,
222
00:13:14,433 --> 00:13:17,535
they sank to the bottom
and were buried in the silt.
223
00:13:17,570 --> 00:13:19,738
Over millions of years,
224
00:13:19,772 --> 00:13:22,741
their remains were converted
into oil and gas.
225
00:13:22,775 --> 00:13:24,743
Eventually, the basin
226
00:13:24,777 --> 00:13:27,145
silted in and the reef died.
227
00:13:27,179 --> 00:13:29,914
This marine ghost town
was then buried
228
00:13:29,949 --> 00:13:31,649
a mile beneath the surface.
229
00:13:31,684 --> 00:13:34,719
Later, tectonic forces
lifted the skeletal reef
230
00:13:34,754 --> 00:13:37,889
high above sea level,
where it was eroded and sculpted
231
00:13:37,923 --> 00:13:40,091
over eons by wind and rain.
232
00:13:40,126 --> 00:13:42,394
Just imagine what
this place looked like
233
00:13:42,428 --> 00:13:44,896
275 million years ago,
234
00:13:44,930 --> 00:13:46,965
when it was a vibrant,
tropical inland sea,
235
00:13:46,999 --> 00:13:48,967
dotted with islands
236
00:13:49,001 --> 00:13:51,836
and brimming with life.
237
00:13:55,274 --> 00:13:57,842
Until about
220 million years ago,
238
00:13:57,877 --> 00:14:01,913
New England and North Africa
were next-door neighbors.
239
00:14:01,947 --> 00:14:03,948
There was no such thing
as the Atlantic Ocean.
240
00:14:03,983 --> 00:14:08,286
Those thin blue fingers
at the center-- they were lakes.
241
00:14:08,320 --> 00:14:11,256
They were the first outward
signs that the supercontinent
242
00:14:11,290 --> 00:14:12,824
was splitting apart and that
243
00:14:12,858 --> 00:14:16,027
life on Earth was due
for another big shake-up.
244
00:14:16,062 --> 00:14:19,330
A million years later,
the lakes became a long bay,
245
00:14:19,365 --> 00:14:22,267
which would grow
into the Atlantic Ocean.
246
00:14:22,301 --> 00:14:24,869
These profound changes
at the surface
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00:14:24,904 --> 00:14:29,007
were merely symptoms of a drama
that was unfolding far beneath,
248
00:14:29,041 --> 00:14:30,341
in the depths of the Earth.
249
00:14:32,745 --> 00:14:35,613
By the time we got here,
the telltale traces
250
00:14:35,648 --> 00:14:37,382
of global upheaval were buried
251
00:14:37,416 --> 00:14:39,617
at the bottom
of the deep blue sea.
252
00:14:39,652 --> 00:14:42,153
We were completely cut off
from the great story
253
00:14:42,188 --> 00:14:43,788
of Earth's violent past--
254
00:14:43,823 --> 00:14:47,559
a species of amnesiacs
trying to find out
255
00:14:47,593 --> 00:14:50,462
who we were and what happened
256
00:14:50,496 --> 00:14:52,530
before we awakened.
257
00:14:52,565 --> 00:14:56,334
In 1570, Abraham Ortelius
created the first
258
00:14:56,369 --> 00:14:59,838
modern world atlas,
reflecting on the discoveries
259
00:14:59,872 --> 00:15:01,639
of the previous 80 years--
260
00:15:01,674 --> 00:15:04,876
the Golden Age of Exploration.
261
00:15:04,910 --> 00:15:06,678
Before the ink was dry,
262
00:15:06,712 --> 00:15:09,147
Ortelius stepped back
from his masterpiece
263
00:15:09,181 --> 00:15:12,517
and became the first of many
to notice the striking
264
00:15:12,551 --> 00:15:14,819
puzzle-piece fit
between the continents
265
00:15:14,854 --> 00:15:17,222
on either side of the Atlantic.
266
00:15:17,256 --> 00:15:20,492
He later wrote that the
Americas were torn away
267
00:15:20,526 --> 00:15:23,561
from Europe and Africa
by earthquakes and floods.
268
00:15:23,596 --> 00:15:25,363
But Ortelius's observation
269
00:15:25,398 --> 00:15:27,198
remained nothing more
than a hunch
270
00:15:27,233 --> 00:15:29,200
for the next
couple of centuries...
271
00:15:30,603 --> 00:15:33,071
until an early 20th century
272
00:15:33,105 --> 00:15:35,073
German astronomer
and meteorologist
273
00:15:35,107 --> 00:15:36,608
amassed the evidence
274
00:15:36,642 --> 00:15:39,077
to build the
scientific case for it.
275
00:15:39,111 --> 00:15:42,247
Alfred Wegener had been drafted
during the First World War,
276
00:15:42,281 --> 00:15:44,716
but was wounded soon after.
277
00:15:44,750 --> 00:15:47,052
As he recovered
in a field hospital,
278
00:15:47,086 --> 00:15:49,187
he scoured scientific
literature
279
00:15:49,221 --> 00:15:51,923
for clues to the Earth's past.
280
00:15:51,957 --> 00:15:53,625
Years before,
281
00:15:53,659 --> 00:15:56,061
Wegener had happened upon
an intriguing paper
282
00:15:56,095 --> 00:15:57,629
in the stacks
of his university library.
283
00:15:57,663 --> 00:16:00,398
It puzzled Wegener
284
00:16:00,433 --> 00:16:03,868
that fossils of the same
species of a now-extinct fern
285
00:16:03,903 --> 00:16:08,540
were reported to be found
on both sides of the Atlantic.
286
00:16:08,574 --> 00:16:11,276
Even more curious were
the discoveries of fossils
287
00:16:11,310 --> 00:16:14,479
of the same dinosaurs
on both continents.
288
00:16:14,513 --> 00:16:16,414
In the early 20th century,
289
00:16:16,449 --> 00:16:18,983
geologists explained
how life crossed the oceans
290
00:16:19,018 --> 00:16:23,822
by imagining that land bridges
had once existed between them.
291
00:16:23,856 --> 00:16:27,292
It was thought that these land
bridges gradually disintegrated
292
00:16:27,326 --> 00:16:30,595
and vanished
beneath the waves long ago.
293
00:16:30,629 --> 00:16:33,131
But there was one piece of
evidence that convinced Wegener
294
00:16:33,165 --> 00:16:36,434
that the prevailing
scientific view must be wrong...
295
00:16:36,469 --> 00:16:39,070
the Earth itself.
296
00:16:39,105 --> 00:16:42,640
Why would a mountain range
cross the oceanic divide
297
00:16:42,675 --> 00:16:44,843
to continue
on another continent?
298
00:16:44,877 --> 00:16:46,978
And why would you find
the same unique pattern
299
00:16:47,012 --> 00:16:50,648
in the layers of rocks in both
Brazil and South Africa?
300
00:16:50,683 --> 00:16:52,650
And another thing...
301
00:16:52,685 --> 00:16:55,920
under what circumstances could
tropical plants have flourished
302
00:16:55,955 --> 00:16:59,324
in the frozen wastes
of the Arctic?
303
00:16:59,358 --> 00:17:01,459
Wegener concluded
that there was only
304
00:17:01,494 --> 00:17:04,195
one logical solution
to this puzzle...
305
00:17:04,230 --> 00:17:07,665
There had once been a single
supercontinent on Earth.
306
00:17:07,700 --> 00:17:11,102
He named it Pangaea.
307
00:17:11,137 --> 00:17:14,973
So Wegener becomes the toast
of the scientific world, right?
308
00:17:15,007 --> 00:17:16,941
Not exactly.
309
00:17:16,976 --> 00:17:19,344
Most geologists ridiculed
Wegener's hypothesis
310
00:17:19,378 --> 00:17:21,346
of continental drift.
311
00:17:21,380 --> 00:17:25,316
They preferred their
imaginary natural land bridges
312
00:17:25,351 --> 00:17:27,352
to explain away
Wegener's evidence.
313
00:17:29,255 --> 00:17:32,490
How, they asked, could
a continent plow through
314
00:17:32,525 --> 00:17:35,326
the solid rock
of the ocean floor?
315
00:17:35,361 --> 00:17:38,229
Wegener had no
convincing answer.
316
00:17:38,264 --> 00:17:40,365
He became the laughingstock
of the field;
317
00:17:40,399 --> 00:17:43,468
a pariah at scientific
conferences.
318
00:17:45,237 --> 00:17:47,972
Despite this, Wegener continued
to fight for his ideas,
319
00:17:48,007 --> 00:17:51,342
conducting daring research
expeditions to gather evidence.
320
00:17:51,377 --> 00:17:55,180
On one of these, he learned
that colleagues were
321
00:17:55,214 --> 00:17:58,049
trapped on an ice cap
without food.
322
00:17:58,084 --> 00:18:00,251
On his way back
from the mission,
323
00:18:00,286 --> 00:18:02,220
he became lost in a blizzard.
324
00:18:02,254 --> 00:18:05,056
A day or two after
his 50th birthday,
325
00:18:05,091 --> 00:18:06,391
he disappeared,
326
00:18:06,425 --> 00:18:08,560
never knowing that, in time,
327
00:18:08,594 --> 00:18:10,995
he would be vindicated
and come to be viewed
328
00:18:11,030 --> 00:18:14,599
as one of the greatest
geologists in history.
329
00:18:19,705 --> 00:18:21,906
Scientists are human.
330
00:18:21,941 --> 00:18:23,708
We have our blind spots
and prejudices.
331
00:18:23,743 --> 00:18:26,611
Science is a mechanism
332
00:18:26,645 --> 00:18:28,613
designed to ferret them out.
333
00:18:28,647 --> 00:18:31,016
Problem is, we aren't
always faithful
334
00:18:31,050 --> 00:18:32,851
to the core values of science.
335
00:18:32,885 --> 00:18:37,255
Few people knew this better
than Marie Tharp.
336
00:18:43,162 --> 00:18:47,198
It's 1952, and Marie is
patiently enduring the slights
337
00:18:47,233 --> 00:18:49,868
of her fellow members
of the geology department.
338
00:18:49,902 --> 00:18:52,037
Her degrees in geology
and mathematics
339
00:18:52,071 --> 00:18:53,738
count for little with them.
340
00:18:53,773 --> 00:18:56,908
Bruce Heezen, a graduate
student from Iowa,
341
00:18:56,942 --> 00:18:59,144
has just returned
from a lengthy expedition
342
00:18:59,178 --> 00:19:01,946
to map the ocean floor
using sonar.
343
00:19:04,850 --> 00:19:06,851
Will you do something
with these?
344
00:19:11,924 --> 00:19:14,626
Bruce, look.
345
00:19:14,660 --> 00:19:15,760
It's-- it's all come together.
346
00:19:15,795 --> 00:19:17,595
There's this giant rift valley
347
00:19:17,630 --> 00:19:19,631
that runs through
the bottom of the Atlantic.
348
00:19:19,665 --> 00:19:20,832
Aw, geez, Marie, come on.
349
00:19:20,866 --> 00:19:22,634
This is just more girl talk.
350
00:19:22,668 --> 00:19:25,303
You're not in enough trouble
with everyone here already?
351
00:19:25,338 --> 00:19:27,272
This sounds too much
like continental drift.
352
00:19:27,306 --> 00:19:29,274
You want to end up
like Wegener?
353
00:19:31,610 --> 00:19:35,513
But Marie
would not be dissuaded.
354
00:19:35,548 --> 00:19:39,417
Years later, when Marie and
Bruce placed a map of oceanic
355
00:19:39,452 --> 00:19:41,853
earthquake epicenters
on a light table
356
00:19:41,887 --> 00:19:43,355
over her seafloor map,
357
00:19:43,389 --> 00:19:45,190
the earthquakes
fell right along
358
00:19:45,224 --> 00:19:46,424
the rift valley.
359
00:19:46,459 --> 00:19:49,094
This was the smoking gun
360
00:19:49,128 --> 00:19:50,962
for Wegener's
moving continents.
361
00:19:50,996 --> 00:19:52,864
Heezen now knew
362
00:19:52,898 --> 00:19:56,167
that Marie had been
right all along.
363
00:19:56,202 --> 00:19:59,037
Together, they created the
first true map of the Earth,
364
00:19:59,071 --> 00:20:01,873
including the ocean floor.
365
00:20:04,910 --> 00:20:07,178
We were at last ready to read
366
00:20:07,213 --> 00:20:09,214
the autobiography of the Earth.
367
00:20:12,939 --> 00:20:16,575
Let's take
the Ship of the Imagination...
368
00:20:16,609 --> 00:20:19,311
to a part of the world
that has been off-limits
369
00:20:19,345 --> 00:20:21,446
to all but a few of us.
370
00:20:34,761 --> 00:20:36,261
Two-thirds of the Earth
371
00:20:36,295 --> 00:20:39,898
lies beneath more than
1,000 feet of water.
372
00:20:39,932 --> 00:20:43,235
It's a vast and largely
unexplored frontier.
373
00:20:43,269 --> 00:20:45,804
Everybody knows the Alps
and the Rockies,
374
00:20:45,838 --> 00:20:48,406
but some of the world's
most amazing mountain ranges
375
00:20:48,441 --> 00:20:50,008
are hidden from view.
376
00:20:52,311 --> 00:20:55,814
Below 1,000 meters,
we enter a world
377
00:20:55,848 --> 00:20:57,616
where there is no sunlight.
378
00:20:59,185 --> 00:21:02,854
Hidden in the darkness,
a world of wonders.
379
00:21:05,458 --> 00:21:08,760
This is the longest submarine
mountain range in the world,
380
00:21:08,795 --> 00:21:11,997
the Atlantic Mid-Ocean Ridge.
381
00:21:12,031 --> 00:21:16,034
It wraps around our globe
like the seam on a baseball.
382
00:21:19,238 --> 00:21:23,041
The past is another planet,
383
00:21:23,076 --> 00:21:26,311
but most of us
don't really know this one.
384
00:21:26,345 --> 00:21:29,981
We don't see the mountains
for the water.
385
00:21:30,016 --> 00:21:33,552
This is the world that Marie
Tharp was the first to imagine.
386
00:21:33,586 --> 00:21:35,554
The highest peaks of the ridge
387
00:21:35,588 --> 00:21:38,123
rise over four kilometers above
388
00:21:38,157 --> 00:21:39,958
the ocean floor.
389
00:21:39,992 --> 00:21:42,894
There are sprawling mountain
ranges and canyons, too.
390
00:21:42,929 --> 00:21:45,564
We've now entered
the Marianas Trench,
391
00:21:45,598 --> 00:21:47,332
the deepest canyon on Earth,
392
00:21:47,366 --> 00:21:50,235
more than ten kilometers deep.
393
00:21:50,269 --> 00:21:53,205
It formed when tectonic forces
pushed the seabed
394
00:21:53,239 --> 00:21:55,207
under the adjoining
continental plate.
395
00:21:55,241 --> 00:21:57,642
More people have walked
on the Moon
396
00:21:57,677 --> 00:22:00,245
than have ever been down here.
397
00:22:00,279 --> 00:22:04,516
The pressure here is a crushing
eight tons per square inch.
398
00:22:04,550 --> 00:22:06,718
Being this deep in the ocean
399
00:22:06,753 --> 00:22:10,422
is like having 50 jumbo jets
stacked on top of you.
400
00:22:10,456 --> 00:22:14,259
Yet even here,
life has taken hold.
401
00:22:16,929 --> 00:22:20,332
The fact that sunlight
can't penetrate the deep ocean
402
00:22:20,366 --> 00:22:22,934
doesn't mean
there isn't light down here.
403
00:22:22,969 --> 00:22:25,937
Many underwater species glow
in the dark,
404
00:22:25,972 --> 00:22:29,007
through a process
called bioluminescence.
405
00:22:29,041 --> 00:22:31,910
Our long history
as land mammals,
406
00:22:31,944 --> 00:22:35,080
denizens of the sunlit world,
hasn't prepared us
407
00:22:35,114 --> 00:22:37,849
for the amazing variety of life
that evolution
408
00:22:37,884 --> 00:22:40,452
has crafted in the deep oceans.
409
00:22:42,789 --> 00:22:45,123
Since there's no sunlight
down here,
410
00:22:45,158 --> 00:22:47,592
there's no photosynthesis.
411
00:22:47,627 --> 00:22:51,697
That means there are
no plants to feed on,
412
00:22:51,731 --> 00:22:55,100
and yet, even here, in a world
of permanent midnight,
413
00:22:55,134 --> 00:22:57,102
there's a thriving food chain.
414
00:22:57,136 --> 00:22:58,437
It begins
415
00:22:58,471 --> 00:23:00,906
with a process
called chemosynthesis.
416
00:23:00,940 --> 00:23:03,875
These microscopic creatures
have learned to eat
417
00:23:03,910 --> 00:23:07,579
what's pouring out
of that vent...
418
00:23:07,613 --> 00:23:10,649
a noxious compound
called hydrogen sulfide.
419
00:23:10,683 --> 00:23:12,084
That thick
420
00:23:12,118 --> 00:23:14,753
black smoke provides
the chemical energy
421
00:23:14,787 --> 00:23:16,922
that makes life possible here.
422
00:23:16,956 --> 00:23:19,925
Tiny crustaceans
eat the bacteria,
423
00:23:19,959 --> 00:23:23,361
and the larger animals
eat the crustaceans.
424
00:23:26,833 --> 00:23:29,301
One day, on some future Earth,
425
00:23:29,335 --> 00:23:30,902
these mountains could very well
426
00:23:30,937 --> 00:23:33,305
end up above the water.
427
00:23:33,339 --> 00:23:36,508
Tectonic forces continue
to shape our planet.
428
00:23:36,542 --> 00:23:40,479
The future
is also another planet.
429
00:23:40,513 --> 00:23:42,681
It was a volcano like this one
430
00:23:42,715 --> 00:23:47,319
that created the Hawaiian
islands millions of years ago.
431
00:24:06,973 --> 00:24:10,442
We live on the crust
of a seething cauldron.
432
00:24:10,476 --> 00:24:13,512
At the center of our planet,
there's an iron core.
433
00:24:13,546 --> 00:24:17,349
It's nested inside
of a larger, liquid iron shell.
434
00:24:17,383 --> 00:24:21,186
Wrapped over this is the part
called the mantle.
435
00:24:21,220 --> 00:24:24,122
It's rocky but hot and viscous.
436
00:24:24,157 --> 00:24:27,626
Like a pot of soup cooking
on a stove, the mantle
437
00:24:27,660 --> 00:24:28,860
is churning.
438
00:24:28,895 --> 00:24:30,896
What keeps it moving?
439
00:24:30,930 --> 00:24:34,800
Two things... the heat left over
from Earth's formation,
440
00:24:34,834 --> 00:24:38,470
and the decay of radioactive
elements in the core.
441
00:24:38,504 --> 00:24:41,073
And this outer layer--
the crust,
442
00:24:41,107 --> 00:24:44,142
where you and me
and everyone we know lives--
443
00:24:44,177 --> 00:24:46,545
is only as thick
as the skin on an apple.
444
00:24:46,579 --> 00:24:48,246
The mantle
445
00:24:48,281 --> 00:24:51,483
drags the solid overlying
crust along with it.
446
00:24:51,517 --> 00:24:54,853
The crust resists
because it's cool and rigid.
447
00:24:54,887 --> 00:24:58,657
From time to time,
it reaches the breaking point.
448
00:24:58,691 --> 00:25:01,993
When that happens,
the Earth quakes.
449
00:25:02,028 --> 00:25:04,596
It's not because
somebody misbehaved
450
00:25:04,630 --> 00:25:06,364
and is being punished.
451
00:25:06,399 --> 00:25:08,200
It's due to random forces
452
00:25:08,234 --> 00:25:10,669
that are governed
by the laws of nature.
453
00:25:10,703 --> 00:25:14,005
Our sense of the stability
of the Earth is an illusion
454
00:25:14,040 --> 00:25:16,208
due to the shortness
of our lives.
455
00:25:16,242 --> 00:25:20,112
If we could watch our planet
on its own timescale,
456
00:25:20,146 --> 00:25:24,750
in which big changes take
millions of years to play out,
457
00:25:24,784 --> 00:25:29,421
we would see it as the dynamic
organism it really is.
458
00:25:34,660 --> 00:25:38,130
This is the world
of the late Triassic period
459
00:25:38,164 --> 00:25:41,299
about 200 million years ago.
460
00:25:41,334 --> 00:25:43,435
That little guy?
461
00:25:43,469 --> 00:25:45,904
It's one of
our distant ancestors.
462
00:25:45,938 --> 00:25:48,840
He lived in Newark, New Jersey.
463
00:25:51,144 --> 00:25:55,313
Wherever you walk on Earth...
464
00:25:55,348 --> 00:25:58,316
lost worlds lie buried
beneath your feet.
465
00:25:58,351 --> 00:26:00,552
50 or 100 million years ago,
466
00:26:00,586 --> 00:26:03,054
even the most
seemingly ordinary places
467
00:26:03,089 --> 00:26:05,757
have been the scene
of epic change.
468
00:26:05,792 --> 00:26:08,160
These Palisades are a monument
469
00:26:08,194 --> 00:26:11,396
to the breakup of
the supercontinent Pangaea.
470
00:26:11,431 --> 00:26:13,565
The sequence
of volcanic eruptions
471
00:26:13,599 --> 00:26:17,936
that made these cliffs also led
to the next mass extinction--
472
00:26:17,970 --> 00:26:21,073
the one that ended
the Triassic world.
473
00:26:21,107 --> 00:26:22,407
But a catastrophic
474
00:26:22,442 --> 00:26:24,743
extinction event for one species
475
00:26:24,777 --> 00:26:26,812
is a golden opportunity
for another.
476
00:26:31,184 --> 00:26:33,585
The Triassic extinctions
offered one group
477
00:26:33,619 --> 00:26:35,520
that had been around
for a while
478
00:26:35,555 --> 00:26:37,322
the chance
to take center stage.
479
00:26:41,227 --> 00:26:43,495
The dinosaurs
had a good, long run
480
00:26:43,529 --> 00:26:46,631
for 170 million years.
481
00:26:46,666 --> 00:26:50,469
Back then, India was an island.
482
00:26:50,503 --> 00:26:54,172
It crept northward at the pace
of a few inches per year
483
00:26:54,207 --> 00:26:58,009
on its slow but inexorable
rendezvous with Asia.
484
00:26:58,044 --> 00:27:00,112
Then, once again,
485
00:27:00,146 --> 00:27:02,614
the molten rock beneath
Earth's surface
486
00:27:02,648 --> 00:27:06,685
burst forth and flooded
a huge area of western India.
487
00:27:13,226 --> 00:27:15,327
The knockout punch
488
00:27:15,361 --> 00:27:18,230
literally came out of the blue.
489
00:27:53,995 --> 00:27:55,796
Few animals
490
00:27:55,830 --> 00:27:57,331
larger than a hundred pounds
491
00:27:57,365 --> 00:28:00,400
survived the catastrophes
of the late Cretaceous.
492
00:28:00,435 --> 00:28:04,738
The dust cloud brought night and
cold to the surface for months.
493
00:28:04,772 --> 00:28:07,007
The dinosaurs froze
and starved to death.
494
00:28:07,041 --> 00:28:09,009
But there were small creatures
495
00:28:09,043 --> 00:28:11,011
who took shelter in the Earth.
496
00:28:11,045 --> 00:28:12,946
And when they emerged...
497
00:28:12,981 --> 00:28:14,982
they found that
the monsters who had hunted
498
00:28:15,016 --> 00:28:17,484
and terrorized them were gone.
499
00:28:17,518 --> 00:28:21,288
The Earth was becoming
the Planet of the Mammals.
500
00:28:21,322 --> 00:28:25,292
And the Earth continued
its ceaseless changing.
501
00:28:27,228 --> 00:28:30,364
This was once a desert
where nothing could grow.
502
00:28:30,398 --> 00:28:34,101
It was a million square miles
of sand and salt,
503
00:28:34,135 --> 00:28:37,471
far more hostile than
any environment on Earth today.
504
00:28:37,505 --> 00:28:41,041
Daytime temperatures were
hot enough to bake bread.
505
00:28:41,075 --> 00:28:43,710
And it was more than a mile
below sea level,
506
00:28:43,745 --> 00:28:45,512
so the atmospheric pressure
507
00:28:45,546 --> 00:28:48,115
was about 50% higher
than what we're used to.
508
00:28:48,149 --> 00:28:49,883
It would be hard to think
509
00:28:49,917 --> 00:28:52,686
of a more unpromising
environment on this planet.
510
00:28:52,720 --> 00:28:55,489
Yet this was the basin
of the Mediterranean
511
00:28:55,523 --> 00:28:57,991
five and a half
million years ago,
512
00:28:58,026 --> 00:29:00,193
before it became a sea.
513
00:29:00,228 --> 00:29:03,163
The Earth never
stops moving for long.
514
00:29:03,197 --> 00:29:05,666
The natural dam
at the western end
515
00:29:05,700 --> 00:29:07,301
of the deep basin
516
00:29:07,335 --> 00:29:09,970
gave way,
probably due to earthquakes.
517
00:29:10,004 --> 00:29:13,507
And the deluge began.
518
00:29:13,541 --> 00:29:17,244
The torrential waters rushed in
at a rate 40,000 times greater
519
00:29:17,278 --> 00:29:19,713
than Niagara Falls,
turning a vast desert
520
00:29:19,747 --> 00:29:22,115
into the Mediterranean Sea...
521
00:29:23,284 --> 00:29:26,153
in less than a year.
522
00:29:26,187 --> 00:29:28,322
There were as yet no humans
523
00:29:28,356 --> 00:29:30,557
to witness this enormous flood,
524
00:29:30,591 --> 00:29:33,360
nor to admire
the beauty it created.
525
00:29:33,394 --> 00:29:35,762
Meanwhile, half a world away,
526
00:29:35,797 --> 00:29:39,533
a broad channel separated
North and South America...
527
00:29:39,567 --> 00:29:41,735
allowing ocean currents to flow
528
00:29:41,769 --> 00:29:44,404
from the Atlantic
into the Pacific Ocean.
529
00:29:44,439 --> 00:29:46,607
Tectonic forces
gradually brought
530
00:29:46,641 --> 00:29:49,276
these two continents together,
closing the channel
531
00:29:49,310 --> 00:29:52,613
and creating
the Isthmus of Panama.
532
00:29:52,647 --> 00:29:55,882
This reorganized the worldwide
pattern of ocean currents,
533
00:29:55,917 --> 00:29:58,652
which, in turn, affected
the global climate.
534
00:30:01,422 --> 00:30:04,291
In Africa,
the lush green forest canopy
535
00:30:04,325 --> 00:30:06,693
gave way
to a sparser landscape.
536
00:30:06,728 --> 00:30:08,528
Some species
537
00:30:08,563 --> 00:30:11,231
that were highly specialized
for life in the trees
538
00:30:11,266 --> 00:30:13,100
became extinct.
539
00:30:13,134 --> 00:30:16,036
But the generalists, the ones
that could find a way
540
00:30:16,070 --> 00:30:18,372
to make a living no matter what
life threw at them,
541
00:30:18,406 --> 00:30:21,141
endured and evolved.
542
00:30:24,178 --> 00:30:27,748
Our ancestors had once
burrowed deep in the ground
543
00:30:27,782 --> 00:30:30,117
to avoid predators
who stalked the surface.
544
00:30:30,151 --> 00:30:32,419
But when
the dinosaurs perished,
545
00:30:32,453 --> 00:30:34,254
they emerged into the daylight,
546
00:30:34,289 --> 00:30:36,156
and over the eons,
made new lives
547
00:30:36,190 --> 00:30:38,225
in the branches of the trees.
548
00:30:38,259 --> 00:30:40,794
They developed
opposable thumbs and toes
549
00:30:40,828 --> 00:30:42,262
for swinging
from branch to branch,
550
00:30:42,297 --> 00:30:44,298
across the broad canopy
of treetops,
551
00:30:44,332 --> 00:30:46,566
where all their needs
were fulfilled.
552
00:30:46,601 --> 00:30:50,337
They could also walk upright,
but only for short distances.
553
00:30:50,371 --> 00:30:53,974
With so many trees around, they
didn't have to go very far.
554
00:30:54,008 --> 00:30:55,976
But then it got colder,
555
00:30:56,010 --> 00:30:57,778
and the trees thinned out,
556
00:30:57,812 --> 00:31:00,447
broad grasslands sprang up,
and our ancestors
557
00:31:00,481 --> 00:31:03,250
were forced to traverse them
in search of food.
558
00:31:03,284 --> 00:31:05,285
You needed
a totally different skill set
559
00:31:05,320 --> 00:31:07,120
to make it on the savanna.
560
00:31:07,155 --> 00:31:08,622
In the old days,
561
00:31:08,656 --> 00:31:10,624
you could sit
perched on your tree branch
562
00:31:10,658 --> 00:31:13,093
and watch the big cats
from a safe distance.
563
00:31:13,127 --> 00:31:16,697
Now you were playing
on the same dangerous field.
564
00:31:20,201 --> 00:31:22,836
The survivors were those
who evolved the ability
565
00:31:22,870 --> 00:31:25,472
to walk great distances
on their hind legs
566
00:31:25,506 --> 00:31:26,773
and to run when necessary.
567
00:31:27,909 --> 00:31:29,309
This changed the way
568
00:31:29,344 --> 00:31:31,044
they looked at the world.
569
00:31:31,079 --> 00:31:34,314
Hands and arms were no longer
tied up with walking.
570
00:31:34,316 --> 00:31:38,485
They were free to gather food
and pick up sticks and bones.
571
00:31:38,519 --> 00:31:41,054
These could be used
as weapons and tools.
572
00:31:41,089 --> 00:31:42,889
Think of it...
573
00:31:42,924 --> 00:31:46,493
A change in the topography
of a small piece of land
574
00:31:46,527 --> 00:31:49,796
half a world away
reroutes ocean currents.
575
00:31:49,831 --> 00:31:52,165
Africa grows colder and drier.
576
00:31:52,200 --> 00:31:55,068
Most of the trees can't
withstand the new climate.
577
00:31:55,103 --> 00:31:57,170
The primates who lived in them
578
00:31:57,205 --> 00:32:00,340
have to seek other homes,
and before you know it,
579
00:32:00,375 --> 00:32:03,377
they're using tools
to remake the planet.
580
00:32:03,411 --> 00:32:07,247
The Earth has shaped the course
of human destiny,
581
00:32:07,282 --> 00:32:12,052
but so has the invisible pull
of distant worlds.
582
00:32:36,824 --> 00:32:38,658
The planets have influenced
583
00:32:38,693 --> 00:32:41,995
our lives,
but not in the way you think.
584
00:32:42,029 --> 00:32:44,030
The gravitational pull
of Venus--
585
00:32:44,065 --> 00:32:46,566
small but close--
586
00:32:46,600 --> 00:32:50,203
and that of Jupiter--
distant but massive--
587
00:32:50,237 --> 00:32:54,708
tilted the Earth's axis
this way and that...
588
00:32:57,011 --> 00:33:00,413
and ever so slightly tweaked
the shape of its orbit.
589
00:33:03,017 --> 00:33:04,551
This periodically altered
590
00:33:04,585 --> 00:33:05,986
the amount of sunlight
591
00:33:06,020 --> 00:33:08,121
falling on the edge
of the northern ice cap.
592
00:33:11,425 --> 00:33:13,827
Sometimes it made
the summers there colder,
593
00:33:13,861 --> 00:33:15,595
and the glaciers
advanced southward
594
00:33:15,630 --> 00:33:17,397
from one year to the next,
595
00:33:17,431 --> 00:33:18,865
grinding and scraping,
596
00:33:18,899 --> 00:33:21,701
and crushing everything
in their path.
597
00:33:23,537 --> 00:33:25,672
That's what we call an ice age.
598
00:33:25,706 --> 00:33:28,908
At other times, changes
in Earth's axis and orbit
599
00:33:28,943 --> 00:33:30,810
made the Arctic summers warmer.
600
00:33:32,480 --> 00:33:35,081
And the melting glaciers
began to retreat.
601
00:33:36,484 --> 00:33:39,185
Imagine how resourceful
our ancestors had to be
602
00:33:39,220 --> 00:33:42,289
in order to survive these
radical changes in climate.
603
00:33:42,323 --> 00:33:44,224
With each glacial period,
604
00:33:44,258 --> 00:33:47,294
the ice sheets grow
at the expense of the oceans;
605
00:33:47,328 --> 00:33:50,697
the world sea level falls
by more than 400 feet,
606
00:33:50,731 --> 00:33:52,732
uncovering wide areas of land
607
00:33:52,767 --> 00:33:54,801
along the edges
of the continents.
608
00:33:54,835 --> 00:33:58,138
15 to 25,000 years ago,
609
00:33:58,172 --> 00:34:00,440
there was a period
when the ice receded,
610
00:34:00,474 --> 00:34:02,909
exposing a temporary
land bridge.
611
00:34:02,944 --> 00:34:06,313
The gateway to the other half
of the planet swings open.
612
00:34:06,347 --> 00:34:09,049
Bands of wanderers
crossed the land bridge
613
00:34:09,083 --> 00:34:11,785
to North America
and parts south.
614
00:34:11,819 --> 00:34:15,155
About 10,000 years ago,
the manic swings
615
00:34:15,189 --> 00:34:18,558
of the climate and sea levels
came to a stop.
616
00:34:18,593 --> 00:34:22,262
A new and gentler
climate age began.
617
00:34:22,296 --> 00:34:25,332
It's the one we live in now.
618
00:34:25,366 --> 00:34:27,233
When the great
ice sheets melted,
619
00:34:27,268 --> 00:34:29,402
the sea rose
to its present height
620
00:34:29,437 --> 00:34:32,806
and the rivers carried silt
from the highlands
621
00:34:32,840 --> 00:34:36,309
to build great delta plains
where they met the sea.
622
00:34:36,344 --> 00:34:40,146
On those fertile plains,
we learned a new way of life...
623
00:34:40,181 --> 00:34:44,184
how to grow things,
to feed ourselves and more.
624
00:34:44,218 --> 00:34:46,686
For most of us,
this meant an end
625
00:34:46,721 --> 00:34:49,055
to a million years
of wandering.
626
00:34:50,891 --> 00:34:52,993
The way the planets tug
at each other,
627
00:34:53,027 --> 00:34:55,262
the way the skin
of the Earth moves,
628
00:34:55,296 --> 00:34:57,631
the way those motions
affect climate
629
00:34:57,665 --> 00:35:00,467
and the evolution of life
and intelligence--
630
00:35:00,501 --> 00:35:03,203
they all combined
to give us the means
631
00:35:03,237 --> 00:35:05,472
to turn the mud
of those river deltas
632
00:35:05,506 --> 00:35:09,042
into the first civilizations.
633
00:35:09,076 --> 00:35:12,379
There's nothing like
an interglacial period,
634
00:35:12,413 --> 00:35:15,348
one of those balmy
intermissions in an ice age.
635
00:35:15,383 --> 00:35:18,818
And the great news is that
this one is due to last
636
00:35:18,853 --> 00:35:22,389
for another 50,000 years.
637
00:35:24,025 --> 00:35:27,227
What a break for our kind.
638
00:35:27,261 --> 00:35:29,729
Just one problem.
639
00:35:29,764 --> 00:35:31,698
We can't seem to stop
burning up all those
640
00:35:31,732 --> 00:35:35,235
buried trees from way back
in the Carboniferous Age,
641
00:35:35,269 --> 00:35:36,703
in the form of coal;
642
00:35:36,737 --> 00:35:39,172
and the remains
of ancient plankton,
643
00:35:39,206 --> 00:35:42,242
in the form of oil and gas.
644
00:35:44,011 --> 00:35:46,980
If we could, we'd be
home free, climate-wise.
645
00:35:47,014 --> 00:35:50,583
Instead, we're dumping carbon
dioxide into the atmosphere
646
00:35:50,618 --> 00:35:52,586
at a rate the Earth hasn't seen
647
00:35:52,620 --> 00:35:54,921
since the great climate
catastrophes of the past,
648
00:35:54,956 --> 00:35:58,658
the ones that led
to mass extinctions.
649
00:35:58,693 --> 00:36:02,262
We just can't seem to break our
addiction to the kinds of fuel
650
00:36:02,296 --> 00:36:05,999
that'll bring back a climate
last seen by the dinosaurs;
651
00:36:06,033 --> 00:36:09,369
a climate that will drown our
coastal cities and wreak havoc
652
00:36:09,403 --> 00:36:14,341
on the environment and our
ability to feed ourselves.
653
00:36:14,375 --> 00:36:17,244
All the while, the glorious sun
654
00:36:17,278 --> 00:36:20,280
pours immaculate,
free energy down upon us;
655
00:36:20,314 --> 00:36:23,116
more than we will ever need.
656
00:36:23,150 --> 00:36:25,885
Why can't we summon
the ingenuity and courage
657
00:36:25,920 --> 00:36:28,188
of the generations
that came before us?
658
00:36:28,222 --> 00:36:32,058
The dinosaurs never saw
that asteroid coming.
659
00:36:32,093 --> 00:36:34,427
What's our excuse?
660
00:36:44,338 --> 00:36:46,039
There's a corridor
661
00:36:46,073 --> 00:36:48,308
in the Halls of Extinction
that is, right now,
662
00:36:48,342 --> 00:36:50,577
empty and unmarked.
663
00:36:50,611 --> 00:36:55,315
The autobiography of the Earth
is still being written.
664
00:36:55,349 --> 00:36:59,953
There's a chance that the end
of our story lies in there.
665
00:37:06,299 --> 00:37:08,233
Congratulations.
666
00:37:08,235 --> 00:37:11,436
You're alive.
667
00:37:11,438 --> 00:37:14,239
There's an unbroken thread
that stretches across
668
00:37:14,241 --> 00:37:16,641
more than three billion years
669
00:37:16,643 --> 00:37:19,611
that connects us
to the first life
670
00:37:19,613 --> 00:37:22,814
that ever touched this world.
671
00:37:22,816 --> 00:37:26,217
Think of how tough,
resourceful and lucky
672
00:37:26,219 --> 00:37:28,486
all of our countless
ancestors must have been
673
00:37:28,488 --> 00:37:30,355
to survive long enough
674
00:37:30,357 --> 00:37:33,591
to pass on the message
of life to the next
675
00:37:33,593 --> 00:37:36,995
and the next...
676
00:37:36,997 --> 00:37:39,531
and the next generation,
677
00:37:39,533 --> 00:37:42,433
hundreds of millions
of times...
678
00:37:47,840 --> 00:37:49,507
before it came to us.
679
00:37:53,512 --> 00:37:55,847
There were so many
rivers to cross,
680
00:37:55,849 --> 00:37:57,448
so many hazards along the way.
681
00:37:57,450 --> 00:38:00,585
Predators, starvation, disease,
682
00:38:00,587 --> 00:38:03,754
miscalculation, long winters,
683
00:38:03,756 --> 00:38:06,157
drought, flood and violence.
684
00:38:06,159 --> 00:38:08,526
Not to mention
the occasional upheavals that
685
00:38:08,528 --> 00:38:11,696
erupted from within our planet
and the apocalyptic bolts
686
00:38:11,698 --> 00:38:14,899
that come from the blue.
No matter where we hail from
687
00:38:14,901 --> 00:38:18,035
or who our parents were,
we are descended
688
00:38:18,037 --> 00:38:21,205
from the hearty survivors
of unimaginable catastrophes.
689
00:38:21,207 --> 00:38:25,176
Each of us is a runner in
the longest and most dangerous
690
00:38:25,178 --> 00:38:27,612
relay race there ever was,
691
00:38:27,614 --> 00:38:31,482
and at this moment, we hold
the baton in our hands.
692
00:38:36,488 --> 00:38:40,825
The past is another planet.
693
00:38:40,827 --> 00:38:43,361
And so is the future.
694
00:38:43,363 --> 00:38:46,898
Some 250 million years from now,
695
00:38:46,900 --> 00:38:49,100
many geologists think
that the lands of the Earth
696
00:38:49,102 --> 00:38:51,803
will be united once again.
697
00:39:06,218 --> 00:39:08,352
All this beauty
will have vanished
698
00:39:08,354 --> 00:39:10,488
and the Earth
of our moment in time
699
00:39:10,490 --> 00:39:14,559
will take its place
among the lost worlds.
700
00:39:14,561 --> 00:39:17,228
The great internal engine
of plate tectonics
701
00:39:17,230 --> 00:39:19,263
is indifferent to life,
702
00:39:19,265 --> 00:39:22,200
as are the small changes
in the Earth's orbit and tilt
703
00:39:22,202 --> 00:39:24,101
and the occasional collisions
704
00:39:24,103 --> 00:39:27,238
with little worlds
on rogue orbits.
705
00:39:27,240 --> 00:39:30,208
These processes have no notion
of what has been going on
706
00:39:30,210 --> 00:39:32,743
over billions of years
on our planet's surface.
707
00:39:32,745 --> 00:39:35,780
They do not care.
708
00:39:35,782 --> 00:39:38,950
Each of us is a tiny being
709
00:39:38,952 --> 00:39:41,719
riding on the outermost skin
of one of the smaller planets
710
00:39:41,721 --> 00:39:44,956
for a few dozen trips
around the local star.
711
00:39:47,759 --> 00:39:50,394
The things that live
the longest on Earth
712
00:39:50,396 --> 00:39:52,196
endure for only
about a millionth
713
00:39:52,198 --> 00:39:54,465
of the age of our planet.
714
00:39:54,467 --> 00:39:56,534
So, of course,
the individual organisms
715
00:39:56,536 --> 00:39:59,070
see nothing of
the overall pattern.
716
00:39:59,072 --> 00:40:02,106
Of changing continents...
717
00:40:02,108 --> 00:40:04,609
climate...
718
00:40:04,611 --> 00:40:06,644
evolution.
719
00:40:06,646 --> 00:40:09,614
That we understand
even a little of our origins
720
00:40:09,616 --> 00:40:13,885
is one of the great triumphs
of human insight and courage.
721
00:40:13,887 --> 00:40:17,655
Who we are and why we are here
can only be glimpsed
722
00:40:17,657 --> 00:40:20,591
by piecing together
something of the full picture,
723
00:40:20,593 --> 00:40:24,595
which must encompass
eons of time...
724
00:40:24,597 --> 00:40:27,331
millions of species...
725
00:40:30,502 --> 00:40:33,070
and a multitude of worlds.
726
00:40:40,078 --> 00:40:42,980
In this perspective,
it's not surprising
727
00:40:42,982 --> 00:40:45,082
that we're a mystery
to ourselves and that,
728
00:40:45,084 --> 00:40:47,518
despite our
manifest pretension,
729
00:40:47,520 --> 00:40:50,588
we are far from being masters
of our own little house.
730
00:40:56,495 --> 00:40:59,464
This new corridor
has no name above the entrance
731
00:40:59,466 --> 00:41:02,400
to designate its epoch,
and we don't yet know
732
00:41:02,402 --> 00:41:06,771
which failed species will be
memorialized within its walls.
733
00:41:06,773 --> 00:41:11,476
What happens here, in countless
ways, both large and small,
734
00:41:11,478 --> 00:41:13,845
is being written by us.
735
00:41:13,847 --> 00:41:16,147
Right now.