1
00:00:06,006 --> 00:00:08,008
[wind howling]

2
00:00:12,595 --> 00:00:15,348
[Morgan Freeman] For 90%
of our planet's history,

3
00:00:16,516 --> 00:00:19,602
it has been too warm for ice to form.

4
00:00:23,732 --> 00:00:28,445
So when the Ice Age hit
two and a half million years ago,

5
00:00:29,279 --> 00:00:31,740
its impact was huge.

6
00:00:31,823 --> 00:00:33,825
[poignant music playing]

7
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[grunting]

8
00:00:45,086 --> 00:00:49,966
This is the story of a great freeze

9
00:00:51,176 --> 00:00:54,596
and the rise of a dynasty

10
00:00:54,679 --> 00:00:58,683
that would bring life
to the brink of extinction.

11
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[music intensifies]

12
00:01:02,645 --> 00:01:05,315
-[music ends]
-[echoing howls]

13
00:01:06,691 --> 00:01:08,693
[rousing music playing]

14
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[snarling]

15
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[trilling]

16
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[screeching]

17
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[rousing music continues]

18
00:01:49,818 --> 00:01:51,736
[growling]

19
00:01:51,820 --> 00:01:53,738
[wind howling]

20
00:01:55,824 --> 00:01:57,617
[rumbling]

21
00:01:59,619 --> 00:02:01,621
[rousing music intensifies]

22
00:02:01,704 --> 00:02:04,040
[music fades]

23
00:02:09,087 --> 00:02:11,089
[ambient music playing]

24
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[bird caws]

25
00:02:21,850 --> 00:02:23,852
[ethereal vocalizing]

26
00:02:27,397 --> 00:02:32,569
Yellowstone is one of the coldest places
in America.

27
00:02:39,492 --> 00:02:45,623
In winter, it still endures
some of the same freezing conditions

28
00:02:45,707 --> 00:02:47,709
that an ice age brings.

29
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[grunting]

30
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Temperatures can drop
below minus 50 degrees.

31
00:03:03,141 --> 00:03:06,936
Only those built for the cold can survive.

32
00:03:17,322 --> 00:03:20,700
A bison's thick coat
is such good insulation,

33
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they need little energy to keep warm…

34
00:03:29,083 --> 00:03:30,752
which is just as well,

35
00:03:30,835 --> 00:03:34,130
as grass is hard to find beneath the snow.

36
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[snorts]

37
00:03:38,343 --> 00:03:42,722
But bison aren't
the only hungry ones here.

38
00:03:44,140 --> 00:03:45,934
[high-pitched squawking]

39
00:03:46,017 --> 00:03:48,353
[howling]

40
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Wolves can also withstand
the coldest of winters…

41
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and have been hunting bison in America
for more than 100,000 years.

42
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[grunting]

43
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To split up the herd…

44
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[snorts]

45
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…the pack needs to get them moving.

46
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[bison grunting]

47
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Panic gives the wolves control.

48
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[tense music playing]

49
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The herd must stick together.

50
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One trip could prove fatal.

51
00:05:03,219 --> 00:05:05,305
But the bison can't run forever,

52
00:05:06,431 --> 00:05:08,641
especially in the deep snow.

53
00:05:08,725 --> 00:05:11,102
[grunting]

54
00:05:11,185 --> 00:05:13,479
[wolves whining, growling]

55
00:05:14,522 --> 00:05:15,523
[wolf growls]

56
00:05:15,606 --> 00:05:17,108
[grunting]

57
00:05:20,611 --> 00:05:25,825
Their only hope
is to turn and face their pursuers.

58
00:05:28,494 --> 00:05:30,496
[panting]

59
00:05:32,999 --> 00:05:35,001
[grunting]

60
00:05:37,003 --> 00:05:40,923
Only then does the pack finally relent.

61
00:05:42,592 --> 00:05:44,093
[bison grunting]

62
00:05:47,847 --> 00:05:50,475
But no matter where they go,

63
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the wolves will follow.

64
00:05:59,400 --> 00:06:04,989
Age-old enemies that have been
locked in battle for millennia.

65
00:06:09,827 --> 00:06:14,040
Yet these ancient adversaries are lucky…

66
00:06:16,542 --> 00:06:19,212
for they can look forward
to the end of winter

67
00:06:21,005 --> 00:06:22,673
and the relief of spring.

68
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[bison bellowing]

69
00:06:27,678 --> 00:06:30,723
But there was a time when winter

70
00:06:32,433 --> 00:06:34,477
never seemed to end.

71
00:06:41,859 --> 00:06:44,070
Two and a half million years ago,

72
00:06:45,196 --> 00:06:47,240
changes in the Earth's orbit,

73
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ocean currents, and carbon dioxide levels

74
00:06:51,744 --> 00:06:54,622
led to an abrupt cooling of the planet.

75
00:06:59,001 --> 00:07:01,796
The great Ice Age had begun…

76
00:07:01,879 --> 00:07:04,757
[ethereal music playing]

77
00:07:04,841 --> 00:07:09,011
…and it started
with the tiniest of things.

78
00:07:15,351 --> 00:07:21,983
On its own, a snowflake
is a fragile, frozen wonder.

79
00:07:23,234 --> 00:07:25,027
No two the same.

80
00:07:28,656 --> 00:07:33,119
But together,
snowflakes changed the world.

81
00:07:36,789 --> 00:07:39,584
Without warm summers to melt them,

82
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snow blanketed the north of the globe…

83
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[music ends]

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…and, over thousands of years, compacted

85
00:07:52,346 --> 00:07:56,601
to form permanent ice sheets
several kilometers thick.

86
00:08:07,445 --> 00:08:10,781
Here, in this silent realm,

87
00:08:11,532 --> 00:08:14,869
life was frozen out of existence.

88
00:08:19,332 --> 00:08:21,375
But south of the ice sheets,

89
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a new world was created
where life could thrive.

90
00:08:29,800 --> 00:08:33,304
Circling almost
the entire Northern Hemisphere,

91
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the tundra-steppe
became Earth's most extensive habitat.

92
00:08:51,072 --> 00:08:56,619
Mammals that adapted well to the cold
dominated these frigid lands…

93
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including the largest
and most iconic of them all…

94
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[creatures rumbling]

95
00:09:08,214 --> 00:09:10,049
…woolly mammoths.

96
00:09:12,260 --> 00:09:14,262
Their elephant-like ancestors

97
00:09:15,179 --> 00:09:18,432
left Africa millions of years earlier

98
00:09:18,516 --> 00:09:23,229
and evolved
into these highly specialized beasts.

99
00:09:23,312 --> 00:09:25,314
[rumbling]

100
00:09:26,857 --> 00:09:31,904
Long hair, smaller ears, and shorter tails

101
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help them conserve heat in the cold.

102
00:09:34,615 --> 00:09:36,617
[roaring]

103
00:09:39,912 --> 00:09:44,834
They are guided by an old female,
the matriarch,

104
00:09:44,917 --> 00:09:48,379
who passes her knowledge
down the generations.

105
00:09:49,672 --> 00:09:50,965
[roars]

106
00:09:52,508 --> 00:09:55,928
Generations she needs to keep safe.

107
00:09:56,012 --> 00:09:57,555
[roaring, snorting]

108
00:10:02,935 --> 00:10:04,937
[ominous music playing]

109
00:10:06,772 --> 00:10:08,566
[growling]

110
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[snarling]

111
00:10:12,945 --> 00:10:14,905
Bigger than lions today,

112
00:10:15,698 --> 00:10:19,952
cave lions can bring down
the very largest of prey.

113
00:10:25,207 --> 00:10:26,500
[mewling]

114
00:10:26,584 --> 00:10:29,170
But smaller is easier.

115
00:10:35,551 --> 00:10:40,056
With little cover,
the brazen cats don't even try to hide.

116
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Instead, they bide their time,

117
00:10:48,481 --> 00:10:51,108
waiting for the right moment.

118
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The calf must stay close
to its protectors…

119
00:11:05,790 --> 00:11:09,126
but the hunters have him in their sights.

120
00:11:11,045 --> 00:11:12,380
[grunting]

121
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[trumpeting]

122
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[roaring]

123
00:11:25,267 --> 00:11:27,436
-[snarling]
-[mammoths trumpeting]

124
00:11:28,229 --> 00:11:30,731
The mammoths form a wall of tusks…

125
00:11:31,399 --> 00:11:33,150
[snarling]

126
00:11:33,234 --> 00:11:36,904
…but the lions aren't going anywhere.

127
00:11:36,987 --> 00:11:38,989
[snarling]

128
00:11:40,908 --> 00:11:42,993
[snarling]

129
00:11:43,077 --> 00:11:44,578
[roaring]

130
00:11:44,662 --> 00:11:47,081
[trumpeting]

131
00:11:49,875 --> 00:11:51,168
[snarling]

132
00:11:51,252 --> 00:11:54,130
The matriarch has had enough…

133
00:11:54,213 --> 00:11:56,549
-[snarling]
-[trumpeting]

134
00:12:01,637 --> 00:12:05,182
…but one of the hunters
spots an opportunity.

135
00:12:08,227 --> 00:12:10,146
[tense music playing]

136
00:12:10,229 --> 00:12:11,313
[snarling]

137
00:12:14,108 --> 00:12:16,819
-[growls]
-[bellowing]

138
00:12:18,028 --> 00:12:21,699
The teenager will never stray
from the herd again.

139
00:12:21,782 --> 00:12:23,784
[snarling]

140
00:12:24,827 --> 00:12:26,203
[growling]

141
00:12:26,287 --> 00:12:27,997
[roaring]

142
00:12:31,917 --> 00:12:34,170
[snarling]

143
00:12:36,756 --> 00:12:40,718
Now it's the lions' turn to defend.

144
00:12:40,801 --> 00:12:42,803
-[roaring]
-[snarling]

145
00:12:46,599 --> 00:12:47,975
The calf's mother…

146
00:12:48,058 --> 00:12:50,019
[roaring]

147
00:12:50,102 --> 00:12:52,521
…knows it's a lost cause.

148
00:12:57,568 --> 00:13:00,404
They have no choice but to back down

149
00:13:01,155 --> 00:13:04,158
and protect the generations that remain.

150
00:13:07,036 --> 00:13:10,831
All they can do
is continue their migration

151
00:13:11,707 --> 00:13:14,710
across the cold tundra-steppe.

152
00:13:31,894 --> 00:13:35,648
While ice never completely
engulfed the planet,

153
00:13:37,775 --> 00:13:41,111
its impact was still felt
across the globe…

154
00:13:47,493 --> 00:13:51,997
sometimes in the most unexpected ways.

155
00:13:57,753 --> 00:14:00,965
With most of the world's water
locked up as ice,

156
00:14:02,007 --> 00:14:04,885
the land became increasingly dry.

157
00:14:06,804 --> 00:14:09,974
This is the flip side of an ice age.

158
00:14:14,061 --> 00:14:16,522
South of the tundra-steppe,

159
00:14:16,605 --> 00:14:19,942
the deserts almost doubled in size,

160
00:14:20,860 --> 00:14:23,737
devouring everything in their path.

161
00:14:26,240 --> 00:14:28,242
[unsettling music playing]

162
00:14:31,078 --> 00:14:33,080
[whispered vocalizing]

163
00:14:33,747 --> 00:14:40,129
Only desert specialists that had evolved
to withstand extreme heat

164
00:14:40,212 --> 00:14:42,965
could survive such hostile conditions.

165
00:14:48,012 --> 00:14:50,681
But the drying didn't stop there.

166
00:14:53,225 --> 00:14:58,063
Even further south,
Africa's tropical rainforests,

167
00:14:58,147 --> 00:15:02,276
stable sanctuaries for life
for over 50 million years,

168
00:15:02,943 --> 00:15:06,030
almost completely disappeared…

169
00:15:06,113 --> 00:15:08,115
[stirring music playing]

170
00:15:10,576 --> 00:15:12,578
[music ends abruptly]

171
00:15:13,621 --> 00:15:18,459
…replaced by a vast expanse
of dry forest and grassland.

172
00:15:22,713 --> 00:15:25,215
The impact on life was huge,

173
00:15:25,883 --> 00:15:29,136
not least on one group of animals…

174
00:15:31,013 --> 00:15:32,640
[honks, yaps]

175
00:15:32,723 --> 00:15:33,891
…the primates.

176
00:15:36,602 --> 00:15:41,357
Baboons share 94% of their DNA with us,

177
00:15:43,275 --> 00:15:47,279
as well as a crucial part of our story.

178
00:15:49,990 --> 00:15:54,870
The descent from the treetops
to a life on the forest floor.

179
00:16:04,588 --> 00:16:07,299
Down here, during the Ice Age,

180
00:16:07,883 --> 00:16:10,803
our cousins faced many new challenges.

181
00:16:17,977 --> 00:16:21,772
Life on the ground is more dangerous…

182
00:16:21,855 --> 00:16:23,857
[tense music playing]

183
00:16:27,987 --> 00:16:30,280
[baboon barking]

184
00:16:35,327 --> 00:16:37,454
…home to large predators.

185
00:16:47,297 --> 00:16:51,635
Fortunately, what primates lack
in strength and size,

186
00:16:53,554 --> 00:16:57,558
we make up for
with intelligence and large families.

187
00:16:58,559 --> 00:17:00,561
[gentle music playing]

188
00:17:06,066 --> 00:17:08,986
But finding enough food
to feed many mouths…

189
00:17:09,069 --> 00:17:10,320
[chirping]

190
00:17:10,404 --> 00:17:12,573
…is a constant challenge.

191
00:17:15,701 --> 00:17:18,746
[elephant growling]

192
00:17:22,499 --> 00:17:24,585
So when food is found,

193
00:17:26,003 --> 00:17:28,088
it attracts plenty of attention.

194
00:17:30,257 --> 00:17:31,300
[grunting]

195
00:17:39,099 --> 00:17:41,852
-And where there's a precious resource…
-[elephant snorts]

196
00:17:41,935 --> 00:17:43,395
[screeching]

197
00:17:43,479 --> 00:17:46,190
…conflict is inevitable…

198
00:17:46,273 --> 00:17:48,859
-[warthog squeals]
-[baboon grunts]

199
00:17:51,820 --> 00:17:55,282
…not least with your own kind.

200
00:17:55,365 --> 00:17:57,367
[tense, dramatic music playing]

201
00:17:58,202 --> 00:18:01,872
A rival troop
with no appetite for sharing.

202
00:18:03,457 --> 00:18:04,458
[barks]

203
00:18:12,466 --> 00:18:14,468
[clicking]

204
00:18:17,221 --> 00:18:19,056
[grunting]

205
00:18:21,809 --> 00:18:23,811
-[barking]
-[screeching]

206
00:18:30,234 --> 00:18:31,652
In the dry forest,

207
00:18:33,821 --> 00:18:36,657
every fruit is worth fighting for…

208
00:18:36,740 --> 00:18:37,908
[screeching]

209
00:18:37,991 --> 00:18:39,409
[barking]

210
00:18:42,412 --> 00:18:44,748
…and every fight counts.

211
00:18:44,832 --> 00:18:47,501
[energetic music playing]

212
00:18:47,584 --> 00:18:49,169
[screeching]

213
00:18:51,880 --> 00:18:53,882
[screeching]

214
00:19:02,683 --> 00:19:04,685
[screeching]

215
00:19:08,147 --> 00:19:09,231
[music slows]

216
00:19:09,314 --> 00:19:10,983
[screeching]

217
00:19:14,987 --> 00:19:17,739
The rival troop cut their losses.

218
00:19:18,365 --> 00:19:20,701
-[clicking]
-But they'll be back.

219
00:19:27,666 --> 00:19:31,170
To overcome the challenges
of a more hostile world,

220
00:19:31,795 --> 00:19:35,465
primates relied
on their social intelligence,

221
00:19:36,550 --> 00:19:39,052
a trait that, in time,

222
00:19:39,136 --> 00:19:45,184
would lead to one species of primate
achieving global domination.

223
00:19:46,018 --> 00:19:48,020
[ominous music playing]

224
00:19:49,897 --> 00:19:51,148
[music ends]

225
00:19:59,781 --> 00:20:04,912
The buildup of ice in the north
affected the climate across the planet.

226
00:20:08,916 --> 00:20:12,920
But just as life got used
to colder, drier conditions,

227
00:20:13,837 --> 00:20:15,839
everything changed.

228
00:20:21,511 --> 00:20:25,891
The ice began to melt
as Earth's orbit shifted once more

229
00:20:28,060 --> 00:20:31,730
and global temperatures began to rise.

230
00:20:31,813 --> 00:20:33,982
[somber music playing]

231
00:20:40,447 --> 00:20:44,034
What started as a series
of meltwater streams

232
00:20:44,117 --> 00:20:47,162
soon turned into a deluge.

233
00:20:47,246 --> 00:20:49,248
[somber music continues]

234
00:21:04,096 --> 00:21:09,142
In North America, the meltwater
formed an enormous glacial lake

235
00:21:09,768 --> 00:21:15,857
600 meters deep
and covering 10,000 square kilometers.

236
00:21:21,238 --> 00:21:25,534
The only thing stopping the water
from flooding the land to the west

237
00:21:26,326 --> 00:21:29,705
was a towering wall of ice.

238
00:21:35,127 --> 00:21:40,590
On the far side,
the wall was almost a kilometer high…

239
00:21:40,674 --> 00:21:43,427
[ominous music playing]

240
00:21:43,510 --> 00:21:46,430
…a seemingly unstoppable barrier…

241
00:21:49,599 --> 00:21:51,268
but not for much longer.

242
00:21:51,351 --> 00:21:53,353
[faint rumbling]

243
00:22:00,485 --> 00:22:05,699
As temperatures kept rising
and the meltwater lake kept growing,

244
00:22:06,533 --> 00:22:09,453
the pressure from behind increased.

245
00:22:09,536 --> 00:22:11,538
[creaking, rumbling]

246
00:22:18,128 --> 00:22:23,133
Before long, the walls started to crumble
from the inside out…

247
00:22:38,023 --> 00:22:41,818
until finally, catastrophic collapse.

248
00:23:01,880 --> 00:23:03,882
[dramatic music playing]

249
00:23:17,646 --> 00:23:23,276
In an instant, a lake the size
of the Irish Sea is unleashed.

250
00:23:41,169 --> 00:23:42,796
[music fades]

251
00:23:42,879 --> 00:23:44,881
[birds tweeting]

252
00:23:45,882 --> 00:23:47,676
Thirty kilometers south,

253
00:23:48,176 --> 00:23:51,680
and the first hint
of the coming apocalypse.

254
00:23:53,807 --> 00:23:55,475
[faint rumbling]

255
00:23:55,559 --> 00:23:56,768
Tremors.

256
00:23:58,854 --> 00:23:59,896
[chirping]

257
00:23:59,980 --> 00:24:01,565
They sense danger…

258
00:24:02,399 --> 00:24:04,526
[whinnying]

259
00:24:04,609 --> 00:24:06,445
…but there's nowhere to hide.

260
00:24:06,528 --> 00:24:08,530
[rumbling intensifies]

261
00:24:21,001 --> 00:24:22,752
[whinnying]

262
00:24:27,215 --> 00:24:31,428
The first they see is a wall of dust.

263
00:24:35,056 --> 00:24:36,808
A hundred meters high,

264
00:24:37,434 --> 00:24:40,353
it's the vanguard of a giant tsunami.

265
00:24:49,905 --> 00:24:52,616
[epic music playing]

266
00:25:16,598 --> 00:25:18,975
[music fades]

267
00:25:19,059 --> 00:25:21,311
In just ten hours,

268
00:25:21,394 --> 00:25:25,357
the megaflood smashes
an 800-kilometer-long path

269
00:25:25,982 --> 00:25:29,861
through the American continent,
all the way to the ocean.

270
00:25:30,904 --> 00:25:32,906
[mournful music playing]

271
00:25:40,497 --> 00:25:44,292
Natural wonders that might otherwise
take millennia to form

272
00:25:45,210 --> 00:25:47,963
are created in a matter of hours.

273
00:25:49,089 --> 00:25:51,091
[ethereal music playing]

274
00:26:01,059 --> 00:26:05,063
But these spectacles are short-lived.

275
00:26:12,320 --> 00:26:13,905
Just a few days later,

276
00:26:14,698 --> 00:26:16,741
all that remains

277
00:26:18,034 --> 00:26:19,786
is an eerie silence.

278
00:26:19,869 --> 00:26:22,122
[music fades to silence]

279
00:26:28,211 --> 00:26:34,884
The indelible scars of this megaflood
still mark the American landscape today…

280
00:26:38,138 --> 00:26:41,600
yet since the dawn of the Ice Age,

281
00:26:41,683 --> 00:26:46,688
there have been more than 50 cycles
of ice buildup and melt…

282
00:26:49,232 --> 00:26:53,153
each causing its own epic floods.

283
00:26:53,236 --> 00:26:55,238
[optimistic music playing]

284
00:26:59,784 --> 00:27:03,288
Once the turmoil
of the last great melt subsided,

285
00:27:04,289 --> 00:27:07,167
balance slowly returned across the land.

286
00:27:15,508 --> 00:27:17,677
Rainfall became more regular…

287
00:27:19,971 --> 00:27:22,390
allowing forests to bounce back.

288
00:27:22,474 --> 00:27:24,476
[chirping, tweeting]

289
00:27:27,520 --> 00:27:29,689
Deserts shrunk and greened

290
00:27:30,357 --> 00:27:33,360
as, once again, water flowed.

291
00:27:39,407 --> 00:27:41,409
And where water flows,

292
00:27:41,993 --> 00:27:44,746
life soon follows.

293
00:27:53,922 --> 00:27:55,882
Europe's Danube delta

294
00:27:55,965 --> 00:27:59,010
is one of the largest wetlands
in the world.

295
00:28:00,470 --> 00:28:03,056
It formed after the last great melt

296
00:28:03,682 --> 00:28:07,936
and quickly became home
to an incredible wealth of animal life.

297
00:28:14,484 --> 00:28:16,444
With so much food on offer,

298
00:28:16,528 --> 00:28:19,948
whiskered terns travel
thousands of kilometers

299
00:28:20,031 --> 00:28:21,866
to breed in these rich waters.

300
00:28:23,660 --> 00:28:26,371
It's the perfect place to raise a family…

301
00:28:27,872 --> 00:28:30,083
[chirping]

302
00:28:32,419 --> 00:28:36,047
…but it's a wasted journey

303
00:28:36,631 --> 00:28:40,510
if a male arrives too late
to find a female.

304
00:28:46,933 --> 00:28:52,480
All he can do
is watch the success of others.

305
00:28:52,564 --> 00:28:53,606
[chirping]

306
00:28:53,690 --> 00:28:55,692
[slow, playful music playing]

307
00:29:00,697 --> 00:29:02,365
With his rival gone…

308
00:29:02,449 --> 00:29:03,658
[chirping]

309
00:29:03,742 --> 00:29:05,285
…now is his chance.

310
00:29:13,918 --> 00:29:15,587
[chirping]

311
00:29:18,381 --> 00:29:20,175
Food makes an excellent gift…

312
00:29:20,842 --> 00:29:21,843
[chirping]

313
00:29:23,511 --> 00:29:25,930
…but she's not impressed.

314
00:29:27,140 --> 00:29:29,350
[chirping]

315
00:29:33,313 --> 00:29:36,649
He tries his luck nonetheless…

316
00:29:39,694 --> 00:29:40,820
but to no avail.

317
00:29:42,238 --> 00:29:43,531
[chirps]

318
00:29:46,409 --> 00:29:50,747
The spurned male must dine alone.

319
00:29:54,417 --> 00:29:59,798
Only when life is so bountiful
can females afford to be so choosy.

320
00:30:01,257 --> 00:30:03,259
[chirping]

321
00:30:08,807 --> 00:30:10,725
[chirping]

322
00:30:10,809 --> 00:30:15,271
The end of the Ice Age
ushered in not only a time of plenty…

323
00:30:18,525 --> 00:30:22,570
but also a time
of great climate stability…

324
00:30:25,073 --> 00:30:28,785
a time known as the Holocene.

325
00:30:44,175 --> 00:30:48,263
During this period,
warm, wet conditions prevailed…

326
00:30:48,346 --> 00:30:49,389
[trumpeting]

327
00:30:49,472 --> 00:30:51,432
…and average global temperatures

328
00:30:51,516 --> 00:30:55,228
fluctuated by
less than one degree Celsius,

329
00:30:56,771 --> 00:31:01,818
allowing life to flourish
in every corner of the world…

330
00:31:03,403 --> 00:31:05,363
[squawking]

331
00:31:08,616 --> 00:31:13,663
…each species boasting
an unbroken line of ancestry

332
00:31:13,746 --> 00:31:16,833
stretching back four billion years

333
00:31:16,916 --> 00:31:19,794
to the very origin of life on Earth.

334
00:31:20,461 --> 00:31:23,131
[gentle music playing]

335
00:31:33,892 --> 00:31:35,184
[trilling]

336
00:31:42,108 --> 00:31:44,110
[music fades]

337
00:31:45,278 --> 00:31:50,158
However, not everything thrived
during the Holocene.

338
00:31:53,786 --> 00:31:59,167
A strange and highly selective extinction
was underway.

339
00:32:01,252 --> 00:32:02,921
Across the planet,

340
00:32:03,004 --> 00:32:06,174
the largest land animals
were disappearing.

341
00:32:07,342 --> 00:32:12,805
Mammoths, cave lions,
and hundreds of other species vanished.

342
00:32:15,683 --> 00:32:18,186
North America was particularly hard-hit,

343
00:32:19,103 --> 00:32:22,649
losing over 70% of its giants…

344
00:32:25,777 --> 00:32:27,278
but not all.

345
00:32:29,697 --> 00:32:32,033
In the absence of competitors,

346
00:32:32,951 --> 00:32:36,079
bison took over the great plains…

347
00:32:36,162 --> 00:32:39,624
-[grunting]
-…roaming in huge numbers.

348
00:32:55,306 --> 00:32:57,392
-[grunting]
-But they weren't alone.

349
00:32:57,475 --> 00:32:59,602
[ominous music playing]

350
00:33:04,107 --> 00:33:06,985
With fewer big prey to choose from,

351
00:33:08,987 --> 00:33:12,490
bison became the focus
of another group of survivors.

352
00:33:16,285 --> 00:33:18,287
[grunting]

353
00:33:20,873 --> 00:33:23,459
Age-old enemies.

354
00:33:27,380 --> 00:33:31,426
Their best defense
is to keep an eye on the danger,

355
00:33:33,094 --> 00:33:36,431
stick together, and calmly move on.

356
00:33:40,935 --> 00:33:43,229
But these are no ordinary hunters…

357
00:33:45,565 --> 00:33:47,567
[grunting]

358
00:33:49,360 --> 00:33:53,698
…for the Ice Age saw the spread
of a new predator.

359
00:33:54,699 --> 00:33:56,701
[ominous music continues]

360
00:34:01,581 --> 00:34:02,707
Like wolves,

361
00:34:03,499 --> 00:34:05,334
we hunted in groups.

362
00:34:08,880 --> 00:34:11,299
And what we lacked in strength and speed…

363
00:34:13,634 --> 00:34:18,264
we made up for
with intelligence and cunning.

364
00:34:21,225 --> 00:34:25,188
The evolution of our large, complex brains

365
00:34:25,271 --> 00:34:28,066
had set us apart from other primates

366
00:34:29,484 --> 00:34:33,780
and enabled us to hunt
in increasingly sophisticated ways.

367
00:34:33,863 --> 00:34:36,908
[slow, majestic music playing]

368
00:34:39,285 --> 00:34:40,912
Mimicking wolves

369
00:34:42,038 --> 00:34:45,166
and using carefully placed stone stacks,

370
00:34:46,751 --> 00:34:50,797
hunters corralled the bison for miles,

371
00:34:52,173 --> 00:34:55,009
until they were exactly

372
00:34:55,968 --> 00:34:57,345
where they wanted them.

373
00:34:57,428 --> 00:34:58,554
[music fades]

374
00:35:04,018 --> 00:35:05,728
[bison grunting]

375
00:35:08,106 --> 00:35:12,068
Only then do they close in
behind the herd.

376
00:35:13,778 --> 00:35:16,322
[grunting]

377
00:35:21,285 --> 00:35:23,621
Reveal themselves too soon

378
00:35:25,498 --> 00:35:28,876
and days of effort will be wasted.

379
00:35:29,544 --> 00:35:31,546
[ominous music playing]

380
00:35:38,177 --> 00:35:41,013
Their ultimate prize
isn't the death of one,

381
00:35:42,682 --> 00:35:44,517
but the fall of many…

382
00:35:49,689 --> 00:35:53,067
to feed many over the winter months.

383
00:35:57,029 --> 00:35:58,865
[grunting]

384
00:36:02,326 --> 00:36:04,453
The trap is set.

385
00:36:09,876 --> 00:36:14,005
All they need is a little encouragement.

386
00:36:14,839 --> 00:36:16,632
[hunters shrieking]

387
00:36:17,508 --> 00:36:19,719
-[shrieking]
-[dramatic music playing]

388
00:36:20,845 --> 00:36:22,388
[grunting]

389
00:36:31,647 --> 00:36:32,899
[music ends]

390
00:36:32,982 --> 00:36:34,192
[grunting]

391
00:36:34,275 --> 00:36:36,277
[dramatic music resumes]

392
00:36:43,868 --> 00:36:45,411
[music ends]

393
00:36:45,494 --> 00:36:46,996
[rocks clattering]

394
00:36:49,248 --> 00:36:50,291
[dull thud]

395
00:37:00,468 --> 00:37:02,345
By the early Holocene,

396
00:37:02,970 --> 00:37:08,142
humans had spread out of Africa
to almost every continent on Earth

397
00:37:09,185 --> 00:37:13,022
and become
the world's most dangerous predator.

398
00:37:13,773 --> 00:37:15,775
[distant cries]

399
00:37:17,860 --> 00:37:19,737
While our rise contributed

400
00:37:19,820 --> 00:37:22,949
to the global extinction
of large land animals,

401
00:37:23,824 --> 00:37:26,869
our story could have been a short one

402
00:37:28,621 --> 00:37:31,207
had we not done something remarkable.

403
00:37:32,124 --> 00:37:34,126
[suspenseful music playing]

404
00:37:34,961 --> 00:37:40,299
We freed ourselves from the uncertainty
of a hunter-gatherer existence

405
00:37:41,008 --> 00:37:44,262
by forming alliances with nature.

406
00:37:47,223 --> 00:37:49,600
The stable climate of the Holocene

407
00:37:49,684 --> 00:37:53,604
enabled our ancestors
to develop a unique relationship

408
00:37:55,856 --> 00:37:57,066
with plants.

409
00:38:02,280 --> 00:38:04,699
They hand-selected certain species

410
00:38:05,449 --> 00:38:09,745
and sowed their seeds
where they were best able to grow.

411
00:38:09,829 --> 00:38:11,831
[gentle music playing]

412
00:38:16,294 --> 00:38:18,587
All this care and attention

413
00:38:18,671 --> 00:38:22,717
dramatically increased
the plants' chances of survival,

414
00:38:24,176 --> 00:38:29,098
and in return,
humans could reap the rewards.

415
00:38:33,978 --> 00:38:36,480
They learned how to produce more food

416
00:38:37,064 --> 00:38:40,234
and to make it last all year round.

417
00:38:44,363 --> 00:38:46,073
And where their plants grew,

418
00:38:47,992 --> 00:38:49,452
people prospered.

419
00:38:53,080 --> 00:38:58,544
Our ancestors discovered
how to ensure a stable food supply.

420
00:39:00,546 --> 00:39:03,966
And it wasn't just plants
they domesticated.

421
00:39:04,050 --> 00:39:05,384
[cattle lowing]

422
00:39:05,468 --> 00:39:06,802
Animals too.

423
00:39:08,512 --> 00:39:09,930
Across the world,

424
00:39:10,014 --> 00:39:14,769
many hunter-gatherers
gave up their nomadic lifestyles

425
00:39:17,021 --> 00:39:19,231
in favor of farming.

426
00:39:20,524 --> 00:39:25,946
Slowly but surely,
the wilderness was transformed,

427
00:39:27,198 --> 00:39:29,950
tamed by human hands.

428
00:39:32,370 --> 00:39:35,414
Freed from the constant battle
to find food,

429
00:39:36,207 --> 00:39:38,209
human populations grew,

430
00:39:39,794 --> 00:39:41,796
work diversified,

431
00:39:43,422 --> 00:39:46,092
society became more complex…

432
00:39:49,095 --> 00:39:52,014
and civilizations were born.

433
00:39:52,098 --> 00:39:54,100
[rousing music playing]

434
00:39:58,979 --> 00:40:04,026
We achieved something
no other species has ever done.

435
00:40:05,152 --> 00:40:10,032
We broke free of nature and rose above it.

436
00:40:11,575 --> 00:40:15,371
Agriculture changed everything…

437
00:40:17,748 --> 00:40:21,335
but another revolution was coming.

438
00:40:21,419 --> 00:40:23,421
[rousing music intensifies]

439
00:41:09,675 --> 00:41:11,677
[music fades]

440
00:41:13,762 --> 00:41:19,894
Our ingenuity has taken us further
than we could ever have imagined,

441
00:41:21,854 --> 00:41:26,942
and our story is now written
on the surface of the Earth.

442
00:41:30,488 --> 00:41:36,327
What was once wild has been tamed or lost.

443
00:41:40,831 --> 00:41:43,792
We're too successful for our own good

444
00:41:45,044 --> 00:41:46,921
and for that of the planet…

445
00:41:49,465 --> 00:41:54,303
and we are now causing
the next mass extinction.

446
00:41:54,386 --> 00:41:56,388
[solemn music playing]

447
00:42:00,142 --> 00:42:03,812
It's not just
that simply feeding ourselves

448
00:42:03,896 --> 00:42:06,982
takes up more than half
of all habitable land…

449
00:42:21,830 --> 00:42:26,168
and it's not just
that the carbon dioxide we are releasing

450
00:42:26,252 --> 00:42:28,337
is heating our planet faster

451
00:42:28,420 --> 00:42:32,925
than at any time
in the last 500 million years.

452
00:42:40,057 --> 00:42:45,396
Nor is it just that we are warming
and acidifying the oceans,

453
00:42:46,981 --> 00:42:49,483
destroying their natural balance

454
00:42:49,567 --> 00:42:53,571
and killing off
vast swathes of marine life.

455
00:42:57,116 --> 00:43:01,954
Nor is it just that we are causing
extreme weather events…

456
00:43:02,037 --> 00:43:03,414
[thunder crashing]

457
00:43:03,497 --> 00:43:04,790
…fire and drought

458
00:43:05,958 --> 00:43:09,920
that are returning the Earth
to its barren beginnings.

459
00:43:15,217 --> 00:43:18,679
And it's not just that we are doing
any one of these

460
00:43:19,847 --> 00:43:22,683
but that we are doing all of them,

461
00:43:23,475 --> 00:43:28,022
all at the same time.

462
00:43:29,982 --> 00:43:32,484
And to make matters worse,

463
00:43:33,444 --> 00:43:36,322
we are doing it at meteoric speed.

464
00:43:36,405 --> 00:43:39,116
[music quickens]

465
00:43:39,199 --> 00:43:41,201
[music ends abruptly]

466
00:43:46,707 --> 00:43:53,714
Although rare, mass extinctions change
the course of history like nothing else.

467
00:43:55,841 --> 00:44:01,680
So far, Earth has endured
five of these apocalyptic events,

468
00:44:02,931 --> 00:44:07,978
each one wiping out
more than three-quarters of all life.

469
00:44:11,440 --> 00:44:14,693
What's more, the dominant species going in

470
00:44:15,319 --> 00:44:19,573
are not the dominant species coming out.

471
00:44:23,786 --> 00:44:26,580
The impact of a mass extinction

472
00:44:26,664 --> 00:44:30,959
has not been felt for 66 million years.

473
00:44:32,378 --> 00:44:35,172
Now we're on track

474
00:44:36,548 --> 00:44:37,758
for the sixth.

475
00:44:45,516 --> 00:44:47,810
In the last 50 years alone,

476
00:44:48,686 --> 00:44:54,233
wildlife populations have fallen
by an average of almost 70%,

477
00:44:55,734 --> 00:45:01,657
and this time,
we are the ones responsible.

478
00:45:04,868 --> 00:45:08,288
And yet despite this grim forecast,

479
00:45:08,997 --> 00:45:12,584
there remains a glimmer of hope.

480
00:45:12,668 --> 00:45:15,254
[gentle, optimistic music playing]

481
00:45:16,213 --> 00:45:22,928
We are the first species
in the four-billion-year story of life

482
00:45:23,679 --> 00:45:27,891
to understand
what is happening to our world.

483
00:45:30,018 --> 00:45:32,688
We are also the first species

484
00:45:32,771 --> 00:45:36,525
to understand
what is needed to put it right.

485
00:45:36,608 --> 00:45:38,610
[ethereal vocalizing]

486
00:45:38,694 --> 00:45:43,031
Our intelligence has brought us this far,

487
00:45:44,742 --> 00:45:48,412
and it's the only thing that can save us.

488
00:45:55,002 --> 00:45:59,006
Our future, and that of the planet,

489
00:45:59,089 --> 00:46:00,924
is yet to be written.

490
00:46:02,885 --> 00:46:07,055
How we act now
will determine the next chapter…

491
00:46:07,139 --> 00:46:08,474
[baby gurgling]

492
00:46:08,557 --> 00:46:11,351
…in the story of life.

493
00:46:11,435 --> 00:46:13,353
-[echoing crash]
-[water dripping]

494
00:46:13,437 --> 00:46:15,939
-[music fades]
-[thunder rumbling]

495
00:46:20,319 --> 00:46:23,030
But whatever future awaits…

496
00:46:23,113 --> 00:46:25,574
[ominous music playing]

497
00:46:30,496 --> 00:46:33,373
…if there's one thing
we've learned from the past…

498
00:46:39,713 --> 00:46:45,803
it's that life has always found a way.

499
00:46:45,886 --> 00:46:47,846
[eerie music playing]

500
00:46:47,930 --> 00:46:49,848
[birds tweeting]

501
00:46:56,688 --> 00:46:58,690
[tweeting growing louder]

502
00:47:09,868 --> 00:47:12,371
[eerie music intensifies]

503
00:47:16,041 --> 00:47:18,377
[music fades]

504
00:47:20,087 --> 00:47:22,756
[rousing music playing]