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00:00:07,006 --> 00:00:08,300
[narrator]
The story of life on Earth

2
00:00:08,341 --> 00:00:09,801
[baby dinosaur croaking]

3
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[dinosaur roaring]

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00:00:12,095 --> 00:00:13,638
has been marked

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00:00:13,679 --> 00:00:18,185
by a series of catastrophic
extinction events.

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00:00:18,226 --> 00:00:21,730
Natural disasters which have
threatened to wipe out

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00:00:21,771 --> 00:00:25,442
many of the creatures
that call our planet home.

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00:00:25,483 --> 00:00:27,402
But after every brush
with death

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00:00:27,443 --> 00:00:28,904
[roaring]

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00:00:28,945 --> 00:00:33,199
life has come back
even stronger.

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00:00:34,450 --> 00:00:36,161
One of the most recent disasters

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00:00:36,202 --> 00:00:38,705
happened just
12,000 years ago

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00:00:38,746 --> 00:00:41,541
in North America.

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A vast dam of ice
and rock collapsed,

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unleashing one of
the greatest floods

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the world has ever seen.

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[mammoths growling]

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00:00:56,806 --> 00:01:01,186
A catastrophe so enormous,

19
00:01:01,561 --> 00:01:06,316
it slammed the Northern
Hemisphere back into an ice age.

20
00:01:08,067 --> 00:01:10,403
-[bear growling]
-[wolf whining]

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00:01:11,154 --> 00:01:12,656
In this turmoil,

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even the mightiest
struggled to survive.

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-[wolves growling]
-[mammoths roaring]

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But out of the chaos

25
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rose the most dominant species
on Earth today

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[grunting]

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Humans.

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-[dramatic music]
-[birds trilling]

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Northern North America

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00:01:55,281 --> 00:01:57,283
at the end
of the last Ice age.

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A land of glaciers,
snow, and ice.

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00:02:05,541 --> 00:02:07,419
While the frozen landscapes

33
00:02:07,460 --> 00:02:10,338
and endless forests
may look familiar

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00:02:11,839 --> 00:02:14,801
the giant creatures that
live amongst them

35
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are anything but.

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[dire wolf howling]

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A dire wolf.

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A whole one third bigger than
the gray wolf we know today.

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He’s picked up the scent
of fresh blood.

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[dire wolf sniffing]

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♪

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His nose leads him
to an abandoned carcass.

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Something to fill his belly.

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[bear growling]

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-[dire wolf whimpering]
-[bear growling]

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A giant short-faced bear...

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[growling]

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...North America’s
largest bear ever.

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She is ferocious,

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especially now she’s defending
two new cubs.

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This Mama Bear needs
all the meat she can get

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to help them all survive
their long hibernation.

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00:04:15,421 --> 00:04:17,424
Three months later,

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00:04:17,465 --> 00:04:20,635
spring arrives
across North America.

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It’s coming earlier
with each passing year.

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The Ice Age that has gripped
the Earth

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00:04:27,641 --> 00:04:31,854
for tens of thousands of years
is losing its hold.

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As the snow and ice melt away,

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the wonderful creatures of
these dense forests

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begin to stir.

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[bird cawing]

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The lush new growth has drawn
in other animals...

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[mammoths groaning]

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...like these mammoths.

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Outside her den,

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Mama Bear prepares for
her first hunt of the spring.

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Her cubs want to tag along,

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but they are still too small
to leave the den.

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Before she hunts,

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she needs to do something

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she’s been
dreaming of all winter.

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[playful music]

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Oh yeah, that’s the spot.

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00:05:37,795 --> 00:05:41,758
Yet, this is much more
than back-scratching.

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She’s marking her territory
by spreading her unique scent,

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vital for warning
off other bears

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while her cubs are home alone.

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[bear growling]

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And now, onto the hunt.

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She picks up
the distinctive smell of prey.

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After months of hibernation,

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she’s lost a third
of her body weight

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and is ravenous.

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A shelter, which can mean
only one thing...

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humans.

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Only a handful
of humans roam these lands.

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And they’re smart enough not
to mess with a giant bear.

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[bear sniffling]

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[bear growling]

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[fast-paced music]

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[bear growling]

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[human grunting]

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This Mama Bear
is still too heavy

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to climb a tree,
even though she’s half starved.

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Our giant short-faced bear,
however,

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is dwarfed by
a much greater force.

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One that looms
over her territory.

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Only a few miles from her den,
the Laurentide Ice Sheet.

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Formed during an ice age that
gripped the Earth

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00:08:19,540 --> 00:08:22,085
for tens of
thousands of years,

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it covers millions of
square miles

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of the North American continent,

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north of the Great Lakes.

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It is one of the largest
expanses of ice

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00:08:32,886 --> 00:08:37,517
the world has seen in hundreds
of millions of years.

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00:08:37,850 --> 00:08:41,104
But now,
as temperatures rise,

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this massive ice sheet
is melting.

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Downstream, the meltwater
is swelling rivers.

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[bear grumbling]

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[stag-moose huffing]

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A stag-moose.

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Our Mama Bear knows
there’ll be easier prey.

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[stag-moose grunting]

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[stag-moose grunting]

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A stag-moose is a formidable
foe With six-foot antlers.

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But this one is old
and past his prime.

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And he is unaware
he’s being tracked

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[dire wolf growling]

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A dire wolf.

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Still, no threat
to this old boy.

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Except this wolf
brought friends.

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After a desperate winter,
they have formed a super pack.

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00:10:03,936 --> 00:10:07,357
Now, even the giant moose
is in trouble.

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[dire wolves barking]

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00:10:17,866 --> 00:10:23,247
It is the end of the last
Ice Age 12,000 years ago

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and still, most of
what will become Canada

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00:10:26,333 --> 00:10:29,170
is covered in
an ancient ice sheet.

128
00:10:31,130 --> 00:10:33,966
However, this is
beginning to melt,

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swelling all the local rivers.

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In a valley below,

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our older stag-moose has been
targeted by dire wolves.

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[dire wolf growling]

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They have formed a super pack

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and now, even powerful animals
like this stag-moose are prey.

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00:10:59,366 --> 00:11:02,370
[dire wolves barking]

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00:11:16,216 --> 00:11:20,471
Few animals can outrun a pack
of dire wolves for long.

137
00:11:25,642 --> 00:11:27,978
[dire wolves barking]

138
00:11:31,231 --> 00:11:35,986
Our stag-moose chooses deep
waters, over being eaten alive.

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00:11:39,782 --> 00:11:45,246
But this river is now swollen
by water from the melting ice.

140
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And the current
is too strong to fight.

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[stag-moose groaning]

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It was a brave attempt.

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The wolves watch

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00:12:11,355 --> 00:12:14,025
to see if
the stag’s body washes up

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at the bottom of the falls.

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Eventually, they give up.

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[stag-moose huffing]

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Miracles can happen

149
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and this old timer is proof.

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He has survived the falls.

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[stag-moose groaning]

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He’s lost an antler,

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00:13:01,738 --> 00:13:05,826
but it’s a small price to pay
for cheating death.

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[stag-moose roaring]

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00:13:12,124 --> 00:13:16,504
Months later,
spring gives way to summer.

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00:13:21,550 --> 00:13:24,136
Our Mama Bear is now well-fed

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and is taking her cubs
on field trips

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00:13:27,848 --> 00:13:30,518
further and further
from their den.

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00:13:35,898 --> 00:13:39,443
In the valley,
there are more mammoths now

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00:13:39,484 --> 00:13:42,363
And they’ve been joined
by a distant cousin...

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00:13:43,697 --> 00:13:45,533
a mastodon.

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Shorter than a modern elephant,
but more heavily built.

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Mammoth and mastodon have
roamed this continent together

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00:14:05,969 --> 00:14:08,222
for millions of years.

165
00:14:14,519 --> 00:14:18,607
Yet all these creatures
are living on borrowed time.

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00:14:22,235 --> 00:14:26,156
The giant ice sheet
is a ticking time bomb.

167
00:14:29,493 --> 00:14:31,203
As it continues to melt,

168
00:14:31,244 --> 00:14:34,290
it’s doing more
than just swelling rivers.

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00:14:35,916 --> 00:14:39,545
Vast quantities of water
are on the move.

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00:14:46,718 --> 00:14:51,932
Trickles feed streams
that turn into torrents.

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Entire rivers vanish down
deep holes in the ice.

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00:14:58,689 --> 00:15:02,610
But this glacial meltwater
doesn’t just disappear.

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00:15:09,658 --> 00:15:12,328
Along the edge of
the Laurentide Ice Sheet,

174
00:15:13,286 --> 00:15:16,206
a giant lake
has been building...

175
00:15:17,416 --> 00:15:20,002
year by year.

176
00:15:22,629 --> 00:15:24,006
Now, it covers an area

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00:15:24,047 --> 00:15:27,635
larger than all
the Great Lakes combined.

178
00:15:30,220 --> 00:15:33,724
23 hundred cubic miles
of meltwater,

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00:15:34,933 --> 00:15:38,437
held back by dams
of rock and ice.

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00:15:41,732 --> 00:15:43,275
And as the pressure builds,

181
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these dams are about to break.

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00:15:51,616 --> 00:15:54,704
The magnificent creatures in
the valleys

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00:15:54,745 --> 00:15:58,457
have no idea what’s on its way.

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[dramatic music]

185
00:16:05,839 --> 00:16:08,968
[rocks crumbling]

186
00:16:11,429 --> 00:16:15,558
The vast Laurentide Ice Sheet
that covers most of Canada

187
00:16:15,599 --> 00:16:22,106
is melting and along its edges,
enormous lakes have developed.

188
00:16:23,482 --> 00:16:27,778
So far, they have been
held back by ice dams,

189
00:16:29,279 --> 00:16:32,408
but they are about to reach
their breaking point.

190
00:16:37,829 --> 00:16:40,124
On the wooded slopes below,

191
00:16:40,165 --> 00:16:44,086
our Mama Bear has poached
a fresh carcass.

192
00:16:45,420 --> 00:16:48,215
But her cubs are not
where she left them.

193
00:16:51,551 --> 00:16:53,929
A mother’s work is never done.

194
00:16:53,970 --> 00:16:57,349
[bear growling]

195
00:17:01,937 --> 00:17:03,814
They are playing hooky,

196
00:17:03,855 --> 00:17:07,609
lured away by a fascinating,
prickly creature...

197
00:17:11,029 --> 00:17:12,781
a porcupine.

198
00:17:14,783 --> 00:17:18,412
With 30,000 barbed quills
covering his body,

199
00:17:18,453 --> 00:17:21,790
most in this forest
just leave him alone.

200
00:17:25,794 --> 00:17:30,340
Our naive cubs, however,
are new to the neighborhood.

201
00:17:30,590 --> 00:17:33,719
[cub sniffing and grunting]

202
00:17:36,972 --> 00:17:39,725
[cub groaning]

203
00:17:44,479 --> 00:17:47,357
-[cub crying]
-[bear sniffing]

204
00:17:50,569 --> 00:17:52,196
Rude.

205
00:17:55,615 --> 00:17:59,703
Our Mama Bear’s jaws may be
bone-crushingly powerful,

206
00:17:59,744 --> 00:18:03,624
but she can also use them
for delicate cub maintenance.

207
00:18:08,545 --> 00:18:12,007
This little one won’t be
messing with porcupines again.

208
00:18:12,048 --> 00:18:13,842
[cub whimpering]

209
00:18:20,599 --> 00:18:23,894
[bear growling]

210
00:18:23,935 --> 00:18:26,772
After months of
only their mother’s milk,

211
00:18:26,813 --> 00:18:29,775
this is the cubs’
first taste of meat.

212
00:18:32,360 --> 00:18:33,904
[bear grunting]

213
00:18:33,945 --> 00:18:37,783
But Mama Bear senses
something’s not right.

214
00:18:41,369 --> 00:18:43,872
[ice cracking]

215
00:18:47,000 --> 00:18:49,461
[mammoths growling]

216
00:18:54,799 --> 00:18:57,511
She leads her cubs back up
toward their den,

217
00:18:57,552 --> 00:18:59,429
high on the hillside.

218
00:19:08,230 --> 00:19:12,234
[ice creaking]

219
00:19:12,275 --> 00:19:16,488
[ice crumbling]

220
00:19:25,288 --> 00:19:30,127
[dramatic music]

221
00:19:30,168 --> 00:19:33,422
The giant wall of ice
finally breaks.

222
00:19:49,521 --> 00:19:51,565
[mammoths growling]

223
00:19:51,606 --> 00:19:55,652
♪

224
00:20:09,040 --> 00:20:12,503
Thousands of cubic miles
of glacial meltwater

225
00:20:12,544 --> 00:20:17,091
tear across North America
toward the Atlantic Ocean.

226
00:20:17,132 --> 00:20:23,639
♪

227
00:20:42,532 --> 00:20:45,911
This event, 12,000 years ago,

228
00:20:45,952 --> 00:20:49,123
is one of the greatest
flash floods

229
00:20:49,164 --> 00:20:51,041
in the history of the planet.

230
00:20:51,082 --> 00:20:56,546
♪

231
00:21:02,344 --> 00:21:05,472
[soft eerie music]

232
00:21:08,808 --> 00:21:12,062
Two months after
the catastrophic flood,

233
00:21:12,103 --> 00:21:16,817
a landscape decimated
by water and ice.

234
00:21:18,318 --> 00:21:24,700
Desolate, lifeless, except...

235
00:21:25,575 --> 00:21:28,495
our bears have survived.

236
00:21:28,536 --> 00:21:32,541
[bears growling]

237
00:21:34,334 --> 00:21:37,212
Mama bear’s instinct
saved her babies

238
00:21:37,253 --> 00:21:39,047
by heading up to the den.

239
00:21:42,550 --> 00:21:46,054
At this time of year,
they should be feasting.

240
00:21:48,056 --> 00:21:51,185
Instead, they are all starving.

241
00:21:51,226 --> 00:21:54,146
[snuffing]

242
00:21:55,730 --> 00:22:00,944
♪

243
00:22:00,985 --> 00:22:02,863
[sniffling]

244
00:22:02,904 --> 00:22:04,448
[sharp grunt]

245
00:22:04,489 --> 00:22:08,201
Another creature
that has survived the flood.

246
00:22:08,410 --> 00:22:11,788
A huge male short faced bear;

247
00:22:12,997 --> 00:22:15,500
but he’s not interested
in mating.

248
00:22:16,668 --> 00:22:18,920
He’s hunting the cubs.

249
00:22:19,838 --> 00:22:22,424
[light growl]

250
00:22:25,009 --> 00:22:27,763
[loud growl]

251
00:22:32,225 --> 00:22:34,936
[loud growling]

252
00:22:39,607 --> 00:22:41,652
[growling continues]

253
00:22:41,693 --> 00:22:44,113
There is no chance to run.

254
00:22:44,154 --> 00:22:49,159
Our giant Mama Bear
has met her match.

255
00:22:50,535 --> 00:22:53,789
[snarling]

256
00:22:59,586 --> 00:23:02,464
[narrator] A gigantic flood
containing thousands

257
00:23:02,505 --> 00:23:04,383
of cubic miles of meltwater

258
00:23:04,424 --> 00:23:06,635
has stripped
this landscape bare.

259
00:23:07,510 --> 00:23:10,013
And now the few animals left

260
00:23:10,054 --> 00:23:12,974
face a bleak
struggle for survival.

261
00:23:14,809 --> 00:23:16,854
For our mama bear and her cubs,

262
00:23:16,895 --> 00:23:20,190
their worst nightmare
has just tracked them down.

263
00:23:21,357 --> 00:23:23,151
A hungry male.

264
00:23:23,693 --> 00:23:25,988
[loud growling]

265
00:23:26,029 --> 00:23:28,907
[dramatic music]

266
00:23:31,159 --> 00:23:33,203
[growling]

267
00:23:36,080 --> 00:23:37,875
He is larger.

268
00:23:37,916 --> 00:23:40,544
But this mom
will fight to the death

269
00:23:40,585 --> 00:23:42,463
to defend her young.

270
00:23:42,504 --> 00:23:45,674
[growling]

271
00:23:47,842 --> 00:23:51,888
The winner of this battle
will decide the cub’s fate.

272
00:23:52,722 --> 00:23:55,809
[whimpering]

273
00:23:58,061 --> 00:24:01,773
[loud growling]

274
00:24:04,359 --> 00:24:06,820
[loud growling]

275
00:24:08,029 --> 00:24:09,614
[whimpering]

276
00:24:11,658 --> 00:24:16,621
[loud growling]

277
00:24:26,464 --> 00:24:29,843
[loud growling]

278
00:24:32,136 --> 00:24:36,099
A truce... for now.

279
00:24:40,770 --> 00:24:43,773
The male bear
has the cub’s scent.

280
00:24:45,441 --> 00:24:47,736
[snarling]

281
00:24:49,737 --> 00:24:52,032
This is not over.

282
00:24:52,073 --> 00:24:55,869
♪

283
00:25:02,292 --> 00:25:05,754
[light splashing]

284
00:25:07,797 --> 00:25:10,967
[tense music]

285
00:25:14,178 --> 00:25:17,724
[narrator]
Days later, tragedy.

286
00:25:19,017 --> 00:25:21,353
Our mama bear
did eventually lose

287
00:25:21,394 --> 00:25:23,689
one of her cubs to the male.

288
00:25:23,730 --> 00:25:26,942
[mama bear grunts]

289
00:25:26,983 --> 00:25:30,696
Her whole world has been turned
upside down since the flood.

290
00:25:30,737 --> 00:25:33,240
[mama bear grunts]

291
00:25:33,281 --> 00:25:36,868
But the devastation
is far wider.

292
00:25:41,873 --> 00:25:44,835
The deluge has swept
across the Great Lakes

293
00:25:44,876 --> 00:25:47,837
and followed
the St. Lawrence river,

294
00:25:48,129 --> 00:25:52,050
leaving a path
of destruction 500 miles long.

295
00:25:53,009 --> 00:25:55,929
And dumping 2,300 cubic miles

296
00:25:55,970 --> 00:25:59,141
of cold freshwater
into the Atlantic.

297
00:25:59,182 --> 00:26:03,687
♪

298
00:26:03,728 --> 00:26:05,856
The massive
outpouring of water

299
00:26:05,897 --> 00:26:08,024
changed the movement
of the ocean...

300
00:26:10,068 --> 00:26:13,822
leading to the collapse
of the North Atlantic current.

301
00:26:15,365 --> 00:26:19,369
Usually it transports as much
warm water northwards

302
00:26:19,410 --> 00:26:22,372
as 100 Amazon rivers.

303
00:26:22,789 --> 00:26:25,292
Now this vast source
of thermal energy

304
00:26:25,333 --> 00:26:28,545
has been interrupted
by the megaflood

305
00:26:29,253 --> 00:26:33,342
sending the northern hemisphere
back into the ice age.

306
00:26:33,383 --> 00:26:36,386
♪

307
00:26:39,389 --> 00:26:41,892
[dramatic music]

308
00:26:41,933 --> 00:26:45,478
Most animals here
are tough and resilient

309
00:26:45,853 --> 00:26:48,398
and have seen cold
periods come and go.

310
00:26:48,439 --> 00:26:54,196
♪

311
00:26:54,237 --> 00:26:57,991
Large animals like mammoths
are able to move away

312
00:26:58,032 --> 00:27:00,827
in a desperate search
for something to eat.

313
00:27:02,704 --> 00:27:05,832
But these bears don’t migrate.

314
00:27:07,250 --> 00:27:11,129
Our heartbroken mama bear
has found a new den

315
00:27:11,170 --> 00:27:14,424
to escape being discovered
by the male bear.

316
00:27:18,136 --> 00:27:22,265
In this cold weather,
they should start to hibernate.

317
00:27:27,645 --> 00:27:29,398
But she doesn’t
have enough milk

318
00:27:29,439 --> 00:27:32,400
to sustain her cub
to another winter.

319
00:27:34,986 --> 00:27:37,823
[mama bear groans]

320
00:27:37,864 --> 00:27:40,033
She must find more food.

321
00:27:41,117 --> 00:27:47,791
♪

322
00:28:01,637 --> 00:28:05,308
♪

323
00:28:06,934 --> 00:28:10,146
She’s alone
in this frozen wilderness.

324
00:28:16,819 --> 00:28:23,952
♪

325
00:28:26,621 --> 00:28:29,082
She smells something familiar.

326
00:28:37,381 --> 00:28:39,551
Humans.

327
00:28:40,843 --> 00:28:43,221
Several families
drawn together.

328
00:28:45,139 --> 00:28:47,058
In these extreme conditions,

329
00:28:47,099 --> 00:28:51,146
they stand a better
chance of survival as a group.

330
00:28:51,479 --> 00:28:55,191
And it’s paid off, hunting
caribou.

331
00:28:56,609 --> 00:28:58,319
They even have enough to share.

332
00:29:00,613 --> 00:29:03,450
♪

333
00:29:04,951 --> 00:29:08,204
[bear grunting]

334
00:29:11,707 --> 00:29:15,086
It’s dangerous approaching
this many humans.

335
00:29:17,380 --> 00:29:23,386
She is desperate, but this
is a fight she could lose.

336
00:29:23,427 --> 00:29:26,389
[roaring]

337
00:29:31,143 --> 00:29:35,106
[narrator] Following
the collapse of ocean currents,

338
00:29:35,147 --> 00:29:38,526
Ice Age rules
have returned to North America.

339
00:29:40,194 --> 00:29:43,281
The speed of this climate change
has been catastrophic

340
00:29:43,322 --> 00:29:45,992
for some of the animals here.

341
00:29:48,536 --> 00:29:52,123
Our Mama Bear has been unable
to prepare for hibernation

342
00:29:52,164 --> 00:29:55,669
and now has
to leave her cave and her cub

343
00:29:55,710 --> 00:29:58,046
in a desperate search for food.

344
00:29:59,463 --> 00:30:02,842
Her nose leads her
to a human encampment

345
00:30:03,551 --> 00:30:07,972
but stealing from humans
carries enormous danger.

346
00:30:09,640 --> 00:30:13,019
[humans yelling]

347
00:30:15,938 --> 00:30:19,108
[growling]

348
00:30:23,362 --> 00:30:28,493
She is huge but they are many,
and equally desperate.

349
00:30:29,410 --> 00:30:31,121
[loud snarling]

350
00:30:31,162 --> 00:30:34,666
[men yelling]

351
00:30:43,633 --> 00:30:45,593
She makes her escape

352
00:30:49,055 --> 00:30:52,350
[owl hooting]

353
00:30:58,689 --> 00:31:00,901
[light grunt]

354
00:31:00,942 --> 00:31:05,280
She retreats after scavenging
some of the humans’ caribou.

355
00:31:08,699 --> 00:31:10,160
It’s not much,

356
00:31:10,201 --> 00:31:12,704
but it should
sustain her cub for now.

357
00:31:13,829 --> 00:31:16,040
[groans]

358
00:31:19,543 --> 00:31:22,755
The price, however,
has been high.

359
00:31:25,383 --> 00:31:28,803
There is a spear
deep in her side.

360
00:31:30,596 --> 00:31:37,312
She risked it all for her cub,
but soon he will be all alone.

361
00:31:40,314 --> 00:31:44,527
The Mama Bear’s strength
and devotion was enormous

362
00:31:45,194 --> 00:31:48,323
but it was no match
for this climate shock.

363
00:31:48,364 --> 00:31:54,203
♪

364
00:31:55,579 --> 00:31:58,375
The disruption
of the North Atlantic Current

365
00:31:58,416 --> 00:32:00,877
and rapid
cooling in North America

366
00:32:00,918 --> 00:32:03,254
has far reaching implications.

367
00:32:04,672 --> 00:32:08,843
For 1,000 years, ice age
conditions return,

368
00:32:08,884 --> 00:32:10,595
with fleeting summers,

369
00:32:10,636 --> 00:32:15,016
and winters that are much
longer, and colder.

370
00:32:15,558 --> 00:32:19,604
For all the creatures here,
it’s a profound climate shock.

371
00:32:21,272 --> 00:32:23,483
But, in an ever changing world,

372
00:32:23,524 --> 00:32:27,612
eventually, the warm
Atlantic currents recover.

373
00:32:28,404 --> 00:32:30,323
And temperatures shoot back up,

374
00:32:30,364 --> 00:32:32,784
even more quickly
than they dropped.

375
00:32:33,868 --> 00:32:36,621
At one point,
average temperatures rise

376
00:32:36,662 --> 00:32:40,166
by 18 degrees
in just a few decades.

377
00:32:41,709 --> 00:32:44,421
The impact
of violent swings in climate

378
00:32:44,462 --> 00:32:47,090
are too much
for many larger animals...

379
00:32:47,298 --> 00:32:50,468
...like
the giant short-faced bears.

380
00:32:51,302 --> 00:32:53,513
And yet, it is the making

381
00:32:53,554 --> 00:32:56,599
of one particular
mammal species...

382
00:32:57,016 --> 00:32:59,310
...humans.

383
00:33:01,979 --> 00:33:05,858
[birds chirping]

384
00:33:09,236 --> 00:33:12,156
Life has rebounded...

385
00:33:13,324 --> 00:33:15,076
... but is still racing
to catch up

386
00:33:15,117 --> 00:33:17,328
with the increasing
temperatures.

387
00:33:20,873 --> 00:33:23,501
Some familiar
creatures are thriving...

388
00:33:24,877 --> 00:33:31,342
... including elk,
caribou and musk ox.

389
00:33:34,345 --> 00:33:37,682
But few
of the ice age giants remain.

390
00:33:39,725 --> 00:33:42,604
There were once tens
of thousands of mastodons

391
00:33:42,645 --> 00:33:44,564
in this part of North America.

392
00:33:46,315 --> 00:33:50,862
Now this tired old male
is the last of his kind...

393
00:33:52,488 --> 00:33:55,116
forever in search of a mate.

394
00:33:55,157 --> 00:33:58,453
[mastodon snarls]

395
00:33:59,703 --> 00:34:02,874
Today, at least,
he has found some company.

396
00:34:04,291 --> 00:34:07,712
A mother mammoth
with her seven-year-old calf.

397
00:34:08,921 --> 00:34:10,757
The iconic species

398
00:34:10,798 --> 00:34:13,384
is also teetering
on the edge of extinction.

399
00:34:13,884 --> 00:34:16,220
[snarling]

400
00:34:18,097 --> 00:34:20,391
But these majestic creatures

401
00:34:20,683 --> 00:34:23,436
face a more
immediate challenge...

402
00:34:30,025 --> 00:34:31,861
Hunters.

403
00:34:37,199 --> 00:34:39,994
[low grunting]

404
00:34:40,035 --> 00:34:41,954
[roars]

405
00:34:47,126 --> 00:34:51,589
Once, these powerful animals
had little to fear from people.

406
00:34:53,382 --> 00:34:55,927
Now, things have changed.

407
00:34:55,968 --> 00:34:58,471
[hunters yelping]

408
00:34:58,512 --> 00:35:00,974
While the mastodon may be old,

409
00:35:01,015 --> 00:35:03,851
he can still leave
the humans in the dust.

410
00:35:04,977 --> 00:35:08,564
But these hunters
aren’t trying to catching up...

411
00:35:08,939 --> 00:35:12,735
...they are herding them
straight into a trap.

412
00:35:14,862 --> 00:35:19,742
[mastodons grunting]

413
00:35:19,783 --> 00:35:20,576
[man grunts]

414
00:35:26,123 --> 00:35:29,418
[narrator] A thousand years
after the Great Flood...

415
00:35:30,502 --> 00:35:33,047
The imperious
giants of the ice age,

416
00:35:33,088 --> 00:35:34,966
like mastodon and mammoths,

417
00:35:35,007 --> 00:35:38,052
once had little
to fear from humans.

418
00:35:39,720 --> 00:35:42,724
Now, humans
have grouped together

419
00:35:42,765 --> 00:35:45,518
to become ruthless hunters.

420
00:35:46,518 --> 00:35:49,522
They have become
the apex predator.

421
00:35:52,566 --> 00:35:55,153
These giants
are being driven exactly

422
00:35:55,194 --> 00:35:57,446
to where the humans want them.

423
00:36:00,574 --> 00:36:02,994
The hunters have spears.

424
00:36:03,744 --> 00:36:07,624
These are heavy, and tipped
with razor-sharp flint,

425
00:36:07,665 --> 00:36:11,002
capable
of piercing thick hide.

426
00:36:11,043 --> 00:36:13,004
[loud yelling]

427
00:36:13,045 --> 00:36:15,756
[mammoth growling]

428
00:36:19,510 --> 00:36:21,429
[man grunts]

429
00:36:24,306 --> 00:36:25,516
[grunts]

430
00:36:25,557 --> 00:36:28,895
[mammoth growls in pain]

431
00:36:31,230 --> 00:36:33,733
[grunting]

432
00:36:38,237 --> 00:36:40,782
[narrator] The spear
has pierced a vital organ

433
00:36:40,823 --> 00:36:43,034
of this poor mother mammoth.

434
00:36:43,075 --> 00:36:46,078
[groans]

435
00:36:47,663 --> 00:36:50,791
[distant growling]

436
00:36:54,962 --> 00:37:00,426
♪

437
00:37:01,302 --> 00:37:04,096
[mammoth groans]

438
00:37:06,348 --> 00:37:10,144
By nightfall,
it’s all over.

439
00:37:13,897 --> 00:37:17,485
The old mastodon
has survived yet again.

440
00:37:17,943 --> 00:37:21,781
But he will remain
a tempting target for humans...

441
00:37:22,114 --> 00:37:25,451
... and will be lucky
to make it through the fall.

442
00:37:26,994 --> 00:37:32,792
♪

443
00:37:39,465 --> 00:37:44,595
For the humans, the killing
of a mammoth is a rare feat.

444
00:37:46,430 --> 00:37:49,183
So there is good
reason to celebrate.

445
00:37:55,189 --> 00:37:59,819
There are still only about
10,000 humans in North America,

446
00:38:02,029 --> 00:38:04,532
but they are skilled
hunters...

447
00:38:05,949 --> 00:38:10,997
...and, as a group, are able
to kill any animal they choose.

448
00:38:13,999 --> 00:38:19,005
This is what finishes off
the last of the Ice Age giants.

449
00:38:20,089 --> 00:38:23,884
It is the price
of human success.

450
00:38:29,681 --> 00:38:33,352
[light music]

451
00:38:33,685 --> 00:38:35,813
[narrator]
12,000 years have passed...

452
00:38:35,854 --> 00:38:38,399
since the great American flood

453
00:38:38,440 --> 00:38:41,694
led to the collapse
of the North Atlantic Current.

454
00:38:42,861 --> 00:38:47,033
Today, there are signs
it may happen again.

455
00:38:48,117 --> 00:38:50,536
Our warming planet
is now melting

456
00:38:50,577 --> 00:38:52,997
the Greenland Ice sheet
in the Arctic ...

457
00:38:53,038 --> 00:38:56,000
and vast amounts
of icy freshwater

458
00:38:56,041 --> 00:38:59,670
are pouring into
the North Atlantic every year.

459
00:39:01,630 --> 00:39:04,384
We now know
from the great ice age flood,

460
00:39:04,425 --> 00:39:08,220
the profound impact
on climate this could have.

461
00:39:09,888 --> 00:39:12,892
♪

462
00:39:12,933 --> 00:39:15,019
Extinction events
from Earth’s past

463
00:39:15,060 --> 00:39:18,689
can teach us a great deal
about our future...

464
00:39:22,901 --> 00:39:25,405
... Whether it’s toxic oceans...

465
00:39:25,446 --> 00:39:28,366
...rising carbon dioxide...

466
00:39:28,407 --> 00:39:31,243
...or falling asteroids...

467
00:39:33,078 --> 00:39:36,749
...our beautiful planet
can become a harsh home.

468
00:39:36,790 --> 00:39:41,629
♪

469
00:39:41,962 --> 00:39:46,259
But as we’ve seen,
life always adapts...

470
00:39:46,300 --> 00:39:49,178
and comes back stronger.

471
00:39:49,219 --> 00:39:55,851
♪

472
00:40:05,110 --> 00:40:10,116
♪

473
00:40:17,664 --> 00:40:21,878
Now, once again,
the Earth is changing.

474
00:40:21,919 --> 00:40:25,923
Unlike the catastrophes
of the past, however...

475
00:40:25,964 --> 00:40:28,968
there is one important
difference:

476
00:40:30,677 --> 00:40:34,432
This time,
one species has control

477
00:40:34,473 --> 00:40:36,892
over the causes of the change.

478
00:40:39,853 --> 00:40:42,523
♪ Trees of green ♪

479
00:40:42,564 --> 00:40:45,359
♪ Red roses, too ♪

480
00:40:45,400 --> 00:40:51,491
♪ I watched them bloom
for me and you ♪

481
00:40:51,532 --> 00:40:54,785
♪ And I think to myself ♪

482
00:40:55,869 --> 00:41:02,627
♪ What a wonderful world ♪

483
00:41:02,668 --> 00:41:07,047
♪ Yes,
I think to myself ♪

484
00:41:08,507 --> 00:41:12,970
♪ What a wonderful world ♪

485
00:41:13,011 --> 00:41:14,680
[NBC Universal chime]