1 00:00:00,000 --> 00:00:04,964 (gentle guitar music) 2 00:00:08,593 --> 00:00:10,471 I spent most of my life trying to understand 3 00:00:10,471 --> 00:00:12,900 the forces that shaped our planet, 4 00:00:12,900 --> 00:00:15,058 and as a geologist, it always seemed to me 5 00:00:15,058 --> 00:00:17,848 that rocks were right at the heart of things. 6 00:00:17,848 --> 00:00:22,816 (gentle guitar music) 7 00:00:22,816 --> 00:00:26,028 But now, I'm discovering it's not only volcanoes 8 00:00:26,028 --> 00:00:27,863 and colliding continents 9 00:00:27,863 --> 00:00:30,740 that have driven the Earth's greatest changes, 10 00:00:31,742 --> 00:00:34,619 because at crucial moments in its history, 11 00:00:34,619 --> 00:00:38,081 another force has helped create the planet we live on. 12 00:00:39,708 --> 00:00:41,126 Plants. 13 00:00:41,827 --> 00:00:43,503 Just look at this seed. 14 00:00:43,503 --> 00:00:44,830 It's small, it's brown, 15 00:00:44,830 --> 00:00:46,673 it weighs hardly anything. 16 00:00:46,673 --> 00:00:48,091 Looks pretty ordinary. 17 00:00:48,091 --> 00:00:50,051 But actually, nothing could be further from the truth, 18 00:00:50,051 --> 00:00:51,678 because what it will become 19 00:00:51,678 --> 00:00:53,930 is truly extraordinary. 20 00:00:53,930 --> 00:00:58,930 (uptempo music) 21 00:01:02,647 --> 00:01:05,192 These are giant sequoias. 22 00:01:05,192 --> 00:01:08,486 Some are over 3,000 years old. 23 00:01:11,239 --> 00:01:14,992 And sequoias are the largest single life form on Earth. 24 00:01:16,494 --> 00:01:19,248 All from a tiny seed. 25 00:01:21,041 --> 00:01:23,168 Yet, even that pales into insignificance 26 00:01:23,168 --> 00:01:24,670 when compared to what the whole 27 00:01:24,670 --> 00:01:26,213 the plant kingdom's done 28 00:01:26,213 --> 00:01:28,172 throughout the history of our planet. 29 00:01:29,633 --> 00:01:32,594 It's a whole new story about our Earth, 30 00:01:34,637 --> 00:01:37,682 told through remarkable images, 31 00:01:37,682 --> 00:01:40,268 captured for the very first time, 32 00:01:42,061 --> 00:01:44,929 and the latest scientific discoveries. 33 00:01:46,274 --> 00:01:49,110 I love this. This is just fantastic. 34 00:01:49,110 --> 00:01:53,991 (uptempo music) 35 00:01:59,988 --> 00:02:03,375 This program is about just one type of plant, 36 00:02:03,375 --> 00:02:07,619 the most underrated but perhaps the most important of all. 37 00:02:08,797 --> 00:02:11,007 One that, by taking on and conquering 38 00:02:11,007 --> 00:02:12,759 the rest of the plant kingdom, 39 00:02:12,759 --> 00:02:15,053 shaped the face of the planet 40 00:02:15,053 --> 00:02:18,675 and went on to help create human civilization. 41 00:02:18,675 --> 00:02:21,978 This is the story of the rise of that underdog. 42 00:02:21,978 --> 00:02:26,556 (uptempo music) 43 00:02:33,196 --> 00:02:38,034 (gentle music) 44 00:02:38,831 --> 00:02:41,406 For hundreds of millions of years, 45 00:02:41,406 --> 00:02:43,373 throughout the time of the dinosaurs, 46 00:02:43,373 --> 00:02:45,416 forests ruled the land. 47 00:02:45,416 --> 00:02:49,630 (gentle music) 48 00:02:49,630 --> 00:02:53,800 It was so warm, trees extended over most of the Earth. 49 00:02:55,176 --> 00:02:58,888 Imagine the Arctic and Antarctic without ice, 50 00:02:58,888 --> 00:03:00,891 carpeted with forests. 51 00:03:00,891 --> 00:03:05,436 (gentle music) 52 00:03:05,436 --> 00:03:08,398 Welcome to the planet of the trees. 53 00:03:08,398 --> 00:03:13,398 (gentle music) 54 00:03:18,033 --> 00:03:20,534 Today, isolated remnants of those 55 00:03:20,534 --> 00:03:23,830 expansive forests still exist, 56 00:03:23,830 --> 00:03:27,876 and here in East Africa is one of the most impressive. 57 00:03:29,002 --> 00:03:31,164 The Kasagu cloud forest 58 00:03:31,164 --> 00:03:34,132 rises out of the dry plains of Kenya. 59 00:03:34,132 --> 00:03:39,132 (gentle music) 60 00:03:40,055 --> 00:03:44,267 Cloaked in moisture, it's much the same as it was then. 61 00:03:49,022 --> 00:03:51,149 Oh, at last. Look at that. 62 00:03:54,360 --> 00:03:55,854 But millions of years ago, 63 00:03:55,854 --> 00:03:58,155 a challenger to the old dominant trees 64 00:03:58,155 --> 00:03:59,950 came on to the scene. 65 00:04:02,995 --> 00:04:06,581 And the best way to find it is to climb right down, 66 00:04:06,581 --> 00:04:08,749 into the depths of the forest. 67 00:04:11,378 --> 00:04:13,755 There's never really elegantness. 68 00:04:13,755 --> 00:04:17,540 This is when the adrenaline thrill starts to come in. 69 00:04:18,683 --> 00:04:21,137 To be honest, I'm not quite sure after you get to, 70 00:04:21,137 --> 00:04:23,014 there's a little lip. 71 00:04:23,014 --> 00:04:25,016 Just seems to go straight down. 72 00:04:34,776 --> 00:04:38,227 This is the oldest forest in Africa up here. 73 00:04:39,155 --> 00:04:41,574 A relic, really, of the time when 74 00:04:41,574 --> 00:04:44,119 trees dominated the planet. 75 00:04:45,745 --> 00:04:48,915 So, this really has a feeling of descending 76 00:04:48,915 --> 00:04:51,375 into that ancient lost world. 77 00:04:52,836 --> 00:04:57,836 (slow tempo music) 78 00:05:19,854 --> 00:05:22,949 Back then, trees ruled 79 00:05:22,949 --> 00:05:26,036 because wood gave them the strength to grow ever taller 80 00:05:26,036 --> 00:05:29,153 and to gorge on the sunlight all plants need. 81 00:05:36,504 --> 00:05:38,965 As you descend, you get a real sense 82 00:05:38,965 --> 00:05:43,337 of how trees bully and overshadow everything below. 83 00:05:50,102 --> 00:05:53,187 We've come about 10 meters just into the canopy. 84 00:05:53,187 --> 00:05:55,845 And (chuckles) I've nicked the cameraman's light meter 85 00:05:55,845 --> 00:05:58,860 just to see what the light levels are doing. 86 00:05:58,860 --> 00:06:02,363 And already, we've dropped by about a third. 87 00:06:10,204 --> 00:06:12,416 Oh God, finally. 88 00:06:12,416 --> 00:06:13,583 Now, let's see. 89 00:06:13,583 --> 00:06:15,251 See how that light's doing. 90 00:06:17,545 --> 00:06:19,672 That's gone down by a half. 91 00:06:19,672 --> 00:06:22,800 These huge trees here have stolen half the light. 92 00:06:29,683 --> 00:06:32,976 Down here, the trees are intimidating. 93 00:06:37,523 --> 00:06:39,608 But it's not complete gloom. 94 00:06:41,861 --> 00:06:45,656 Patches of sunlight do break through to the forest floor. 95 00:06:49,077 --> 00:06:51,404 And those shafts of precious light 96 00:06:51,404 --> 00:06:53,831 offer the chance for a new type of plant, 97 00:06:53,831 --> 00:06:57,005 one that would come to take on the trees. 98 00:07:02,333 --> 00:07:04,010 So, how did scientists 99 00:07:04,010 --> 00:07:06,960 discover the identity of the challenger? 100 00:07:07,887 --> 00:07:11,807 It's all thanks to a rather enchanting piece of research 101 00:07:11,807 --> 00:07:15,061 involving what's inside this little box. 102 00:07:15,937 --> 00:07:17,971 You'll never guess what it is. 103 00:07:19,065 --> 00:07:23,444 This is a piece of fossilized dinosaur poo. 104 00:07:24,563 --> 00:07:26,197 It stinks. 105 00:07:27,324 --> 00:07:29,485 It's from a titanosaur sauropod 106 00:07:29,485 --> 00:07:32,120 which is kind of like a brontosaurus, 107 00:07:32,120 --> 00:07:34,696 my favorite dinosaur as a kid. 108 00:07:35,373 --> 00:07:37,875 It weighed about 100 tons which makes me think 109 00:07:37,875 --> 00:07:38,960 that this is just a fragment 110 00:07:38,960 --> 00:07:41,747 of something the size of, I don't know really. 111 00:07:41,747 --> 00:07:43,339 Something big anyway. 112 00:07:44,166 --> 00:07:47,551 Scientists love fossil poo, coprolites, we call it 113 00:07:47,551 --> 00:07:50,054 because they tell us about the diet of animals 114 00:07:50,054 --> 00:07:51,265 and particularly in this case, 115 00:07:51,265 --> 00:07:52,516 about the plants that were around 116 00:07:52,516 --> 00:07:54,518 when dinosaurs were here. 117 00:07:54,518 --> 00:07:57,229 And when scientists analyzed this one a few years ago, 118 00:07:57,229 --> 00:08:00,722 they found it contained something really strange. 119 00:08:04,068 --> 00:08:05,569 Under the microscope, 120 00:08:05,569 --> 00:08:08,437 the scientists saw a fragment of a plant. 121 00:08:09,449 --> 00:08:11,284 It had a distinctive pattern, 122 00:08:11,284 --> 00:08:13,411 these figure of eight nodules. 123 00:08:14,537 --> 00:08:16,998 They turned out to be the defining feature 124 00:08:16,998 --> 00:08:20,870 of a family of plants they were astonished to see. 125 00:08:20,870 --> 00:08:22,670 The grasses. 126 00:08:26,374 --> 00:08:29,219 It was from 66 million years ago, 127 00:08:29,219 --> 00:08:34,219 evidence for the earliest grass ever found called matleitis. 128 00:08:39,471 --> 00:08:40,856 From its humble birth, 129 00:08:40,856 --> 00:08:42,058 grass would eventually become 130 00:08:42,058 --> 00:08:44,776 one of the most dominant forces on our planet. 131 00:08:44,776 --> 00:08:49,776 (calm instrumental music) 132 00:08:55,787 --> 00:08:58,206 But its rise would be a David and Goliath 133 00:08:58,206 --> 00:09:00,409 battle with the trees. 134 00:09:10,252 --> 00:09:11,802 You can still find descendants 135 00:09:11,802 --> 00:09:14,221 of those early challengers today. 136 00:09:20,770 --> 00:09:22,397 Plants like this. 137 00:09:24,224 --> 00:09:26,025 And we think these are similar 138 00:09:26,025 --> 00:09:28,861 to what the first grasses must have looked like. 139 00:09:28,861 --> 00:09:30,188 You can just imagine them 140 00:09:30,188 --> 00:09:32,573 struggling away on the forest floor, 141 00:09:32,573 --> 00:09:34,992 just feeding off little scraps of light 142 00:09:34,992 --> 00:09:37,078 making it through the canopy. 143 00:09:38,872 --> 00:09:40,749 It's wonderful to think that dinosaurs 144 00:09:40,749 --> 00:09:44,168 the size of houses were trampling through forests like this, 145 00:09:44,168 --> 00:09:47,213 just grazing on little patches of grass. 146 00:09:53,962 --> 00:09:56,382 But the dinosaurs' days of grazing 147 00:09:56,382 --> 00:09:58,641 were about to end abruptly. 148 00:09:58,641 --> 00:10:03,479 (slow tempo music) 149 00:10:07,774 --> 00:10:10,027 65 million years ago, 150 00:10:10,027 --> 00:10:14,281 an asteroid 10 kilometers across killed them off. 151 00:10:23,875 --> 00:10:26,001 The grasses survived. 152 00:10:28,754 --> 00:10:32,668 But in turn, they would face their own crisis. 153 00:10:38,639 --> 00:10:40,183 What was coming had nothing to do 154 00:10:40,183 --> 00:10:43,060 with the plants and animals that lived on Earth. 155 00:10:43,060 --> 00:10:45,438 It was all to do with the atmosphere, 156 00:10:45,438 --> 00:10:49,066 and that was changing for the most surprising of reasons. 157 00:10:54,405 --> 00:10:57,618 Our air contains carbon dioxide. 158 00:10:57,618 --> 00:11:00,994 It's the gas that plants need to breathe to stay alive. 159 00:11:03,456 --> 00:11:06,292 But between 50 and 30 million years ago, 160 00:11:06,292 --> 00:11:08,628 this gas began to disappear, 161 00:11:11,047 --> 00:11:13,041 threatening all plants. 162 00:11:14,509 --> 00:11:19,509 (intense orchestral music) 163 00:11:22,100 --> 00:11:23,935 The crisis started with the creation 164 00:11:23,935 --> 00:11:27,563 of huge mountain ranges like the Himalayas. 165 00:11:27,563 --> 00:11:32,477 (rumbling) 166 00:11:36,147 --> 00:11:40,409 The biggest period of mountain building in Earth's history. 167 00:11:40,409 --> 00:11:45,406 (intense orchestral music) 168 00:11:49,704 --> 00:11:53,289 The freshly exposed rock was washed away. 169 00:11:53,289 --> 00:11:57,426 (rumbling) 170 00:11:57,426 --> 00:12:00,846 Some of the minerals ended up in the sea. 171 00:12:02,599 --> 00:12:05,894 (waves crashing) 172 00:12:07,937 --> 00:12:12,017 And here they sucked the carbon dioxide gas out of the air 173 00:12:12,017 --> 00:12:15,902 combining with it to form an entirely new type of rock. 174 00:12:15,902 --> 00:12:19,031 (rock breaking) 175 00:12:21,743 --> 00:12:23,358 Limestone. 176 00:12:26,288 --> 00:12:29,208 I can show you that limestone's got carbon dioxide in it 177 00:12:29,208 --> 00:12:33,087 because if i put a little bit of acid on it, 178 00:12:33,087 --> 00:12:35,080 it should fizz like mad. 179 00:12:36,007 --> 00:12:40,637 (acid fizzing) 180 00:12:40,637 --> 00:12:43,515 What this is doing is it's liberating carbon dioxide 181 00:12:43,515 --> 00:12:45,760 that had been in the ancient atmosphere 182 00:12:45,760 --> 00:12:48,977 and has now for the last few million years 183 00:12:48,977 --> 00:12:51,599 been locked away in this rock. 184 00:12:51,599 --> 00:12:56,568 (slow tempo music) 185 00:13:00,837 --> 00:13:03,076 By 30 million years ago, 186 00:13:03,076 --> 00:13:05,107 as the mountains had risen, 187 00:13:06,029 --> 00:13:09,039 the level of carbon dioxide fell. 188 00:13:10,541 --> 00:13:13,002 In fact, carbon dioxide levels dropped to a sixth 189 00:13:13,002 --> 00:13:14,838 of what they were beforehand, 190 00:13:14,838 --> 00:13:17,006 which is an enormous fall, 191 00:13:17,006 --> 00:13:20,467 and for the plant kingdom it meant crisis. 192 00:13:24,680 --> 00:13:27,558 Without enough vital carbon dioxide, 193 00:13:27,558 --> 00:13:30,103 many plants including the grasses 194 00:13:30,103 --> 00:13:32,272 were struggling to survive. 195 00:13:32,272 --> 00:13:36,943 (fizzing) 196 00:13:39,945 --> 00:13:44,945 (slow tempo guitar music) 197 00:13:53,118 --> 00:13:56,044 One way to reveal the impact this had on plants 198 00:13:56,044 --> 00:13:59,006 is to look at a clever bit of human machinery. 199 00:14:02,593 --> 00:14:04,219 The car engine. 200 00:14:08,796 --> 00:14:10,268 Because what's under the bonnet 201 00:14:10,268 --> 00:14:13,520 shares surprising similarities with plants. 202 00:14:13,520 --> 00:14:18,226 (slow tempo music) 203 00:14:20,772 --> 00:14:23,322 A car engine relies on two things to work. 204 00:14:23,322 --> 00:14:27,285 It needs petrol and it needs oxygen from the air. 205 00:14:27,285 --> 00:14:30,288 Inside the engine, these two are combined 206 00:14:30,288 --> 00:14:33,791 to release the energy to power the car. 207 00:14:33,791 --> 00:14:35,491 It's called combustion. 208 00:14:36,377 --> 00:14:41,377 (engine buzzing) 209 00:14:48,348 --> 00:14:50,307 Like the engine, plants also need 210 00:14:50,307 --> 00:14:52,177 a gas from the air to work, 211 00:14:52,177 --> 00:14:54,843 in their case, the carbon dioxide. 212 00:14:59,483 --> 00:15:00,526 So for plants, 213 00:15:00,526 --> 00:15:01,862 (engine buzzing) 214 00:15:01,862 --> 00:15:04,146 the collapse of carbon dioxide levels 215 00:15:04,146 --> 00:15:07,949 were similar to car engine starved of oxygen. 216 00:15:09,528 --> 00:15:11,663 If I block the air intake, 217 00:15:11,663 --> 00:15:14,540 you can feel the engine stuttering away 218 00:15:14,540 --> 00:15:17,210 because it's struggling to get the oxygen 219 00:15:17,210 --> 00:15:18,826 that it needs to work. 220 00:15:23,049 --> 00:15:25,884 With less carbon dioxide in the atmosphere, 221 00:15:25,884 --> 00:15:28,554 plants also began to stutter. 222 00:15:30,556 --> 00:15:32,592 But the grasses were evolving 223 00:15:32,592 --> 00:15:35,393 a new and ingenious invention. 224 00:15:36,729 --> 00:15:40,315 Again, the engine provides a parallel. 225 00:15:41,817 --> 00:15:43,610 But there's a piece of shiny machinery here 226 00:15:43,610 --> 00:15:45,989 that any petrol-head will recognize. 227 00:15:45,989 --> 00:15:47,898 What that does is the opposite of my hand. 228 00:15:47,898 --> 00:15:51,076 It forces more oxygen into the engine. 229 00:15:51,076 --> 00:15:52,994 It's called a turbocharger. 230 00:16:00,955 --> 00:16:02,296 More oxygen means that 231 00:16:02,296 --> 00:16:04,464 the petrol burns more fiercely 232 00:16:04,464 --> 00:16:06,925 and that means more power. 233 00:16:06,925 --> 00:16:08,719 Power enough to do this. 234 00:16:08,719 --> 00:16:12,758 (car buzzes) 235 00:16:12,758 --> 00:16:14,599 (laughs) 236 00:16:14,599 --> 00:16:16,560 (howls) 237 00:16:16,560 --> 00:16:21,560 (slow tempo music) 238 00:16:27,856 --> 00:16:31,994 Evolution often comes up with our cleverest solutions 239 00:16:31,994 --> 00:16:34,119 during desperate times. 240 00:16:37,873 --> 00:16:40,085 And one group of plants, the grasses, 241 00:16:40,085 --> 00:16:43,547 turned this crisis into an opportunity. 242 00:16:49,052 --> 00:16:51,720 Grasses like this, this is elephant grass 243 00:16:51,720 --> 00:16:54,925 which is one of the fastest-growing plants in the world. 244 00:16:54,925 --> 00:16:55,644 In three months, right, 245 00:16:55,644 --> 00:16:58,511 this stuff grows four meters. 246 00:16:58,511 --> 00:17:01,021 That's that much every day. 247 00:17:01,897 --> 00:17:03,693 This phenomenal growth rate was only possible 248 00:17:03,693 --> 00:17:08,195 because of a technology that evolved 30 millions years ago. 249 00:17:08,195 --> 00:17:12,115 A design so effective that if you're a mechanic, 250 00:17:12,115 --> 00:17:13,618 you'd be blown away. 251 00:17:20,708 --> 00:17:23,252 The new grasses came up with the equivalent 252 00:17:23,252 --> 00:17:26,745 of a turbocharger inside the leaves. 253 00:17:31,723 --> 00:17:33,762 It's in the cells of the leaves 254 00:17:33,762 --> 00:17:36,265 that photosynthesis occurs, 255 00:17:36,265 --> 00:17:38,184 where carbon dioxide is combined 256 00:17:38,184 --> 00:17:40,853 with water to make sugar. 257 00:17:44,357 --> 00:17:47,818 But the new grasses created an add-on, 258 00:17:47,818 --> 00:17:51,113 rings of specialist cells known as bundles. 259 00:17:54,033 --> 00:17:56,535 It all acts as a miniature pump, 260 00:17:56,535 --> 00:18:00,539 sucking in and concentrating vital carbon dioxide. 261 00:18:08,464 --> 00:18:12,301 So, although there was less carbon dioxide in the air, 262 00:18:12,301 --> 00:18:15,638 the grasses had the edge over other plants. 263 00:18:15,638 --> 00:18:20,638 (soothing piano music) 264 00:18:28,818 --> 00:18:30,236 You know, when you study the planet, 265 00:18:30,236 --> 00:18:33,114 you're so used to seeing the big events like 266 00:18:33,114 --> 00:18:36,825 I don't know, ice sheets melting and volcanoes erupting. 267 00:18:36,825 --> 00:18:40,530 But with the rise of turbocharge grasses 268 00:18:40,530 --> 00:18:43,123 you've got something that's the tinniest of events. 269 00:18:43,123 --> 00:18:45,619 It's something almost invisible 270 00:18:45,619 --> 00:18:49,630 tucked away inside the leaf of a plant. 271 00:18:49,630 --> 00:18:53,050 It's what makes the story of plants just so fascinating. 272 00:18:53,050 --> 00:18:58,050 (lively orchestral music) 273 00:18:59,766 --> 00:19:03,761 The grasses had found a way to survive the crisis. 274 00:19:03,761 --> 00:19:08,761 (lively orchestral music) 275 00:19:10,193 --> 00:19:12,736 But forests still ruled the world. 276 00:19:12,736 --> 00:19:17,449 (lively orchestral music) 277 00:19:17,449 --> 00:19:20,869 The huge trees had also survived. 278 00:19:25,083 --> 00:19:29,962 Then the underdog unleashed a devastating new weapon. 279 00:19:41,969 --> 00:19:44,601 Eight million years ago, 280 00:19:44,601 --> 00:19:47,648 by now the climate had altered. 281 00:19:47,648 --> 00:19:50,899 Much of the earth was dryer than ever before. 282 00:19:54,945 --> 00:19:58,407 It was the moment grasses had been waiting for. 283 00:20:04,246 --> 00:20:06,582 The grasses had evolved unique properties 284 00:20:06,582 --> 00:20:09,119 that made them especially flammable. 285 00:20:10,628 --> 00:20:14,881 When dry, they became like a tinderbox. 286 00:20:15,708 --> 00:20:18,968 All they needed was the spark. 287 00:20:18,968 --> 00:20:20,880 (thunder rumbling) 288 00:20:20,880 --> 00:20:25,880 (intense orchestral music) 289 00:20:28,729 --> 00:20:30,565 Today there's an ideal place to see 290 00:20:30,565 --> 00:20:33,024 what happened eight million years ago. 291 00:20:41,193 --> 00:20:43,952 Here in the national parks of South Africa, 292 00:20:43,952 --> 00:20:48,207 rangers deliberately start huge fires to manage the land. 293 00:20:53,670 --> 00:20:56,333 And for me, it's the perfect opportunity 294 00:20:56,333 --> 00:21:01,011 to see how back then grasses exploited fire. 295 00:21:01,721 --> 00:21:04,598 So, we're gonna get a chopper coming right down this lane 296 00:21:04,598 --> 00:21:07,471 dropping incendiaries all the way along here. 297 00:21:07,471 --> 00:21:09,477 (helicopter flying overhead) 298 00:21:09,477 --> 00:21:12,012 Chief fire starter is Chris Austin. 299 00:21:12,973 --> 00:21:14,018 Thanks for the treat. 300 00:21:14,018 --> 00:21:15,900 He coordinates the helicopter crew 301 00:21:15,900 --> 00:21:19,071 as they drop fire pellets onto the grass. 302 00:21:19,071 --> 00:21:21,449 Artificial lightning strikes. 303 00:21:24,409 --> 00:21:25,994 Now, what's gonna happen is they just sit there, 304 00:21:25,994 --> 00:21:27,913 they just open up, ignite 305 00:21:27,913 --> 00:21:29,658 and then you will just see them erupt. 306 00:21:29,658 --> 00:21:33,252 (helicopter flying overhead) 307 00:21:33,252 --> 00:21:34,545 Next 46 seconds which is 308 00:21:34,545 --> 00:21:35,831 quite a long time. 46 seconds. 309 00:21:35,831 --> 00:21:37,089 That's nice and precise. 310 00:21:37,089 --> 00:21:38,507 There we go, there's one. 311 00:21:38,507 --> 00:21:39,876 Come and have a look. 312 00:21:39,876 --> 00:21:41,300 Yeah, there's probably another one there but. 313 00:21:41,300 --> 00:21:42,697 13. 314 00:21:42,697 --> 00:21:44,054 This should ignite now. 315 00:21:44,054 --> 00:21:44,888 Behind this. It should go. 316 00:21:44,888 --> 00:21:45,764 It should go. 317 00:21:45,764 --> 00:21:47,099 There. 318 00:21:47,099 --> 00:21:50,811 And then over here, we got ourselves another one. 319 00:21:52,145 --> 00:21:54,064 So, this lane, this whole lane now 320 00:21:54,064 --> 00:21:56,316 is just gonna go up into a wall of flames, 321 00:21:56,316 --> 00:21:57,442 another one there. 322 00:21:57,442 --> 00:21:59,695 Is it safe now here? 323 00:21:59,695 --> 00:22:01,154 She's gonna go up slope, yeah? 324 00:22:01,154 --> 00:22:02,322 She's gonna go away from us? 325 00:22:02,322 --> 00:22:04,908 And of course, if the wind's pushing it it'll accelerate. 326 00:22:04,908 --> 00:22:08,029 You can see that's now being pulled by the slope. 327 00:22:08,029 --> 00:22:09,615 Oh, I can feel it. 328 00:22:09,615 --> 00:22:10,956 It's burning my face already. 329 00:22:10,956 --> 00:22:12,916 (fire crackling) 330 00:22:12,916 --> 00:22:15,448 Look at that. That's amazing. 331 00:22:16,502 --> 00:22:19,215 It's just a wall of smoke and flame. 332 00:22:19,215 --> 00:22:20,926 Unbelievable. 333 00:22:20,926 --> 00:22:25,926 (fire crackling) 334 00:22:28,341 --> 00:22:30,017 The most aggressive fire that I've seen 335 00:22:30,017 --> 00:22:32,185 moved at more than three meters a second which is-- 336 00:22:32,185 --> 00:22:33,645 Three meters a second, that's phenomenal. 337 00:22:33,645 --> 00:22:34,346 It's really quick. 338 00:22:34,346 --> 00:22:35,513 You can't outrun it. 339 00:22:35,513 --> 00:22:37,716 The fires that kill people are grassland fires 340 00:22:37,716 --> 00:22:39,693 because they're so fast-moving. 341 00:22:42,821 --> 00:22:44,447 And that's not all. 342 00:22:44,447 --> 00:22:47,034 Grass burns in a special way, 343 00:22:47,034 --> 00:22:50,236 a way that was devastating to its enemies. 344 00:22:53,623 --> 00:22:55,251 (giggles) 345 00:22:55,251 --> 00:22:56,908 I've kind of fallen into it. 346 00:22:58,712 --> 00:23:01,631 To discover more about its properties, 347 00:23:01,631 --> 00:23:05,677 I've volunteered to enter into the heart of the fire. 348 00:23:06,761 --> 00:23:08,486 This stuff that's going in now is not 349 00:23:08,486 --> 00:23:09,760 kind of medical monitoring, 350 00:23:09,760 --> 00:23:12,893 this is actually for monitoring the temperature of the fire. 351 00:23:12,893 --> 00:23:15,019 It's a thermocouple wire that's gonna go 352 00:23:15,019 --> 00:23:17,064 running down, in this case down my leg. 353 00:23:17,064 --> 00:23:17,933 I think this is probably the first time 354 00:23:17,933 --> 00:23:19,149 this has been done, really. 355 00:23:19,149 --> 00:23:20,818 First time I've ever done this with a guy. 356 00:23:20,818 --> 00:23:22,198 (laughs) 357 00:23:22,198 --> 00:23:24,862 First time you put your hand down a man's trousers. 358 00:23:24,862 --> 00:23:27,814 If you get stuck, that's us virtually married. 359 00:23:29,568 --> 00:23:30,994 Once in the flames, 360 00:23:30,994 --> 00:23:32,287 we hope to combine readings 361 00:23:32,287 --> 00:23:34,456 from the heat sensors on my suit 362 00:23:34,456 --> 00:23:36,333 with a thermal imaging camera 363 00:23:36,333 --> 00:23:39,252 to reveal the secrets of a grass fire. 364 00:23:39,252 --> 00:23:44,215 (fire crackling) 365 00:23:45,176 --> 00:23:47,420 The fire is picking up speed. 366 00:23:47,420 --> 00:23:49,470 (oxygen hissing) 367 00:23:49,470 --> 00:23:50,888 I can't believe I'm seeing this. 368 00:23:50,888 --> 00:23:53,349 It's starting to come towards us. 369 00:23:53,349 --> 00:23:56,980 This just seems like one of the daftest things I've done. 370 00:23:56,980 --> 00:24:01,980 (fire crackling) 371 00:24:06,946 --> 00:24:09,032 Look at the flames! 372 00:24:10,366 --> 00:24:14,371 Grass fires are very different from other fires. 373 00:24:14,371 --> 00:24:17,416 The readings show that the hottest area of the fire, 374 00:24:17,416 --> 00:24:19,335 the white parts on this image, 375 00:24:19,335 --> 00:24:22,786 is not in the burning grass but a meter above it. 376 00:24:25,340 --> 00:24:29,671 The temperature here is over 360 degrees. 377 00:24:29,671 --> 00:24:33,265 (fire crackling) 378 00:24:33,265 --> 00:24:35,683 Grass ignites more easily than other plants 379 00:24:35,683 --> 00:24:39,104 and it's transformed into a volatile gas. 380 00:24:42,690 --> 00:24:47,446 This gas rises and burns even hotter than the grass itself, 381 00:24:48,406 --> 00:24:49,906 making it one of the fiercest 382 00:24:49,906 --> 00:24:52,409 and fastest fires in nature. 383 00:24:52,409 --> 00:24:56,890 (oxygen hissing) 384 00:24:56,890 --> 00:25:01,890 (fire crackling) 385 00:25:07,549 --> 00:25:12,549 (oxygen hisses) 386 00:25:12,929 --> 00:25:16,183 Oh, I know this feels, sounds really strange but 387 00:25:16,183 --> 00:25:18,226 it was actually quite a privilege to be in there. 388 00:25:18,226 --> 00:25:21,021 You know, normally if you're stuck in one of them 389 00:25:21,021 --> 00:25:22,946 you just don't come out. 390 00:25:22,946 --> 00:25:25,488 It was great, at one point the flames comes up 391 00:25:25,488 --> 00:25:27,318 and I just looked down, 392 00:25:27,318 --> 00:25:29,946 and it was just lapping against the mask. 393 00:25:31,073 --> 00:25:33,200 You kind of feel sorry for the trees. 394 00:25:33,992 --> 00:25:38,992 (gentle piano music) 395 00:26:02,937 --> 00:26:06,858 The next day, the fire still smolders. 396 00:26:07,476 --> 00:26:09,017 It's so strange. 397 00:26:09,861 --> 00:26:11,613 Why did grasses evolve 398 00:26:11,613 --> 00:26:14,282 to encourage fires to take hold, 399 00:26:15,492 --> 00:26:19,193 ripping through the landscape and destroying plant life? 400 00:26:20,282 --> 00:26:22,749 It seems suicidal. 401 00:26:24,418 --> 00:26:27,211 Grasses don't just encourage fires to start, 402 00:26:27,211 --> 00:26:29,834 they're also designed to survive them. 403 00:26:29,834 --> 00:26:33,469 In fact, they're the most fire-resistant plant on earth 404 00:26:33,469 --> 00:26:36,305 and you can see here, this all looks scorched. 405 00:26:36,305 --> 00:26:37,764 Look at it, it's still... 406 00:26:38,349 --> 00:26:39,974 Look at the charcoal and smoke there. 407 00:26:39,974 --> 00:26:43,019 But the thing is, if you just peel this back, 408 00:26:43,019 --> 00:26:45,647 you quickly find that, look at that. 409 00:26:45,647 --> 00:26:48,274 There's a lot of that that's still alive. 410 00:26:48,274 --> 00:26:50,562 In fact, the trick really, 411 00:26:50,562 --> 00:26:53,655 the solution to why grasses can survive 412 00:26:53,655 --> 00:26:56,616 isn't on the surface, it's just below the surface. 413 00:26:57,701 --> 00:27:00,622 If you open up these stalks, 414 00:27:00,622 --> 00:27:03,323 you can see that right here there's a little bud. 415 00:27:03,323 --> 00:27:07,335 It's stuck under a kind of insulated thick coating. 416 00:27:07,335 --> 00:27:09,754 It's kind of tucked away in its underground bunker. 417 00:27:10,589 --> 00:27:12,247 It's still alive. 418 00:27:13,717 --> 00:27:14,885 So you look around here 419 00:27:14,885 --> 00:27:16,211 and you just think everything's dead, 420 00:27:16,211 --> 00:27:18,347 and that tree, that tree certainly is. 421 00:27:18,347 --> 00:27:22,100 But the grass, the grass is just biding its time. 422 00:27:22,100 --> 00:27:24,133 It's very much alive. 423 00:27:26,897 --> 00:27:29,441 You know this scene, this could easily be a scene 424 00:27:29,441 --> 00:27:31,528 from eight million years ago, 425 00:27:32,318 --> 00:27:34,946 where the grasses just really quickly 426 00:27:34,946 --> 00:27:37,032 recover and recolonize, 427 00:27:37,032 --> 00:27:41,662 and the sneaky bit is they do it much faster than trees. 428 00:27:42,745 --> 00:27:47,745 (gentle music) 429 00:28:00,137 --> 00:28:05,137 (helicopter flying overhead) 430 00:28:12,233 --> 00:28:14,445 In the wake of this onslaught, 431 00:28:14,445 --> 00:28:17,229 the forest started breaking up. 432 00:28:20,450 --> 00:28:23,489 The grasses were on a land grab, 433 00:28:23,489 --> 00:28:26,863 conquering the territory once held by the trees. 434 00:28:36,550 --> 00:28:38,385 The expanding grasses turned the Earth 435 00:28:38,385 --> 00:28:41,804 into a flammable planet, a fireball world. 436 00:28:41,804 --> 00:28:45,057 It must have seen about a million million trees burned 437 00:28:45,057 --> 00:28:46,727 and black ash filled the sky 438 00:28:46,727 --> 00:28:49,437 for hundreds of thousands of years. 439 00:28:49,437 --> 00:28:52,941 And for the trees, this was apocalypse. 440 00:29:02,784 --> 00:29:04,869 The world was ablaze. 441 00:29:06,614 --> 00:29:08,866 The challenger had sparked a revolution 442 00:29:08,866 --> 00:29:11,250 that was changing the face of the planet. 443 00:29:11,250 --> 00:29:16,250 (intense orchestral music) 444 00:29:23,930 --> 00:29:26,224 But the global rise of grasses 445 00:29:26,224 --> 00:29:29,304 wasn't just reshaping plant life. 446 00:29:29,304 --> 00:29:32,647 It was transforming the animal kingdom, too. 447 00:29:34,649 --> 00:29:37,193 So, how do we know this? 448 00:29:37,193 --> 00:29:41,990 (gentle instrumental music) 449 00:29:57,123 --> 00:29:58,966 The effects of the spreading grasses 450 00:29:58,966 --> 00:30:00,425 have been revealed by 451 00:30:00,425 --> 00:30:03,762 one of the most elegant pieces of forensic science. 452 00:30:03,762 --> 00:30:04,929 Part of the evidence had been discovered 453 00:30:04,929 --> 00:30:06,472 here in North America 454 00:30:06,472 --> 00:30:10,352 and it comes literally straight from the horse's mouth. 455 00:30:10,352 --> 00:30:11,728 Come on. 456 00:30:11,894 --> 00:30:13,605 (horse snorts) Whoa! 457 00:30:13,605 --> 00:30:18,527 (gentle instrumental music) 458 00:30:21,196 --> 00:30:23,115 When an animal eats a plant, 459 00:30:23,115 --> 00:30:27,284 the carbon of the plant is absorbed into its teeth. 460 00:30:28,286 --> 00:30:29,662 Studying the teeth tells you whether 461 00:30:29,662 --> 00:30:32,414 the herbivore has eaten the leaves of trees 462 00:30:32,414 --> 00:30:34,240 or the new grasses. 463 00:30:38,130 --> 00:30:41,424 And the fossil teeth from millions of years ago 464 00:30:41,424 --> 00:30:44,218 tell a remarkable story. 465 00:30:47,847 --> 00:30:50,102 This is the result of the scientific analysis 466 00:30:50,102 --> 00:30:54,021 of tooth enamel from herbivores in North America. 467 00:30:54,021 --> 00:30:55,272 You can see down here this is us 468 00:30:55,272 --> 00:30:57,983 going back in time in millions of years. 469 00:30:57,983 --> 00:30:59,685 Now, the thing is, up to about 470 00:30:59,685 --> 00:31:01,987 eight millions year to about here 471 00:31:01,987 --> 00:31:03,362 you could see that herbivores are largely 472 00:31:03,362 --> 00:31:04,950 eating shrubs and trees. 473 00:31:04,950 --> 00:31:07,025 But then there's a really dramatic change about 474 00:31:07,025 --> 00:31:09,528 between seven and six million years ago. 475 00:31:09,528 --> 00:31:12,413 And after that, they're eating grasses. 476 00:31:12,413 --> 00:31:14,582 And the thing is this sudden switchover 477 00:31:14,582 --> 00:31:16,125 isn't confined to North America. 478 00:31:16,125 --> 00:31:18,211 Here's a graph for South America 479 00:31:18,211 --> 00:31:22,090 and here's a graph for Africa and also for Asia. 480 00:31:22,090 --> 00:31:24,843 You put them together, look at that. 481 00:31:25,759 --> 00:31:28,089 What these graphs tell is the same story 482 00:31:28,089 --> 00:31:31,135 and that is in a period of about one million years, 483 00:31:31,135 --> 00:31:32,676 a geological instant, 484 00:31:32,676 --> 00:31:36,062 the world's herbivores dramatically change their diet 485 00:31:36,062 --> 00:31:38,398 so that they're eating the new grasses. 486 00:31:46,281 --> 00:31:50,299 This discovery proves that by six million years ago, 487 00:31:50,299 --> 00:31:52,986 grasses were dominating the land. 488 00:31:59,210 --> 00:32:00,878 It was a domination that would have 489 00:32:00,878 --> 00:32:04,131 striking consequences for many animals. 490 00:32:05,417 --> 00:32:10,354 (thunder rumbling) 491 00:32:18,856 --> 00:32:22,192 And it's involved another piece of clever engineering 492 00:32:22,192 --> 00:32:24,144 from the grasses. 493 00:32:31,151 --> 00:32:31,951 This is it. 494 00:32:31,951 --> 00:32:34,496 This is the stuff I've been looking for. 495 00:32:34,496 --> 00:32:37,874 This is the sharp stuff, I'm pretty sure of it. 496 00:32:37,874 --> 00:32:39,584 Let's have a little look. 497 00:32:42,545 --> 00:32:43,838 Ah, you... 498 00:32:45,465 --> 00:32:48,969 Oh, that's something we've all done in the past. 499 00:32:48,969 --> 00:32:51,588 Cut ourselves on a blade of grass. 500 00:32:51,588 --> 00:32:52,795 Look at that. 501 00:32:53,348 --> 00:32:54,807 I'm bleeding. 502 00:32:55,474 --> 00:32:58,604 But have you ever wondered why that happens? 503 00:32:58,604 --> 00:33:00,063 It's actually all to do with something 504 00:33:00,063 --> 00:33:02,023 that coats the edge of the leaf. 505 00:33:10,406 --> 00:33:14,577 Grass extracts a mineral called silica from the soil. 506 00:33:18,123 --> 00:33:20,541 This silica is built into row upon row 507 00:33:20,541 --> 00:33:23,044 of tiny daggers along the leaf. 508 00:33:26,632 --> 00:33:30,259 It's a defense to discourage animals from eating it. 509 00:33:34,464 --> 00:33:37,517 Although tiny, these weapons 510 00:33:37,517 --> 00:33:39,561 led to one of the biggest extinctions 511 00:33:39,561 --> 00:33:42,187 of mammals in Earth's history. 512 00:33:44,101 --> 00:33:45,691 The world had been full of many 513 00:33:45,691 --> 00:33:47,360 different plant eaters, 514 00:33:47,360 --> 00:33:50,197 including the vast Baluchitherium. 515 00:33:50,197 --> 00:33:53,157 (snorting and grunting) 516 00:33:53,157 --> 00:33:55,535 These 20-ton beasts were the largest 517 00:33:55,535 --> 00:33:57,611 mammals ever to exist. 518 00:33:59,072 --> 00:34:01,373 They fed off trees and shrubs 519 00:34:01,373 --> 00:34:03,578 but as their food source disappeared, 520 00:34:03,578 --> 00:34:05,544 these animals died out. 521 00:34:07,339 --> 00:34:10,751 (snorting) 522 00:34:14,930 --> 00:34:16,973 In North America alone, 523 00:34:16,973 --> 00:34:19,600 grasses led to the extinction of over half 524 00:34:19,600 --> 00:34:22,144 of all plant-eating mammals. 525 00:34:26,942 --> 00:34:29,819 But some herbivores thrived. 526 00:34:32,905 --> 00:34:34,907 It's all down to the teeth again. 527 00:34:34,907 --> 00:34:35,858 Who would have thought that 528 00:34:35,858 --> 00:34:38,745 gnashers could be so important? 529 00:34:38,745 --> 00:34:40,163 You could see how the survivors coped 530 00:34:40,163 --> 00:34:41,748 with this skull here. 531 00:34:41,748 --> 00:34:43,165 They developed harder teeth 532 00:34:43,165 --> 00:34:46,461 to bite through that silica-edged grass 533 00:34:46,461 --> 00:34:48,921 and also longer grinding teeth 534 00:34:48,921 --> 00:34:51,590 to that it didn't matter if they get worn down. 535 00:34:51,590 --> 00:34:54,260 The creatures adapted 536 00:34:54,260 --> 00:34:55,804 and this is one of the results. 537 00:34:55,804 --> 00:34:59,849 The jaw of a modern-day horse, like Tank here. 538 00:35:09,593 --> 00:35:11,269 By six million years ago, 539 00:35:11,269 --> 00:35:14,065 the triumph of grasses had caused the death 540 00:35:14,065 --> 00:35:16,442 of many types of animals, 541 00:35:16,442 --> 00:35:19,494 while creating vast herds of new ones, 542 00:35:20,620 --> 00:35:24,364 the more familiar plant eaters we know today. 543 00:35:24,364 --> 00:35:29,364 (intense orchestral music) 544 00:35:30,979 --> 00:35:33,841 But that's just the start 545 00:35:33,841 --> 00:35:35,177 because if you've got herbivores 546 00:35:35,177 --> 00:35:37,887 consuming silica-rich grasses, 547 00:35:37,887 --> 00:35:40,925 all that mineral has to go somewhere. 548 00:35:43,851 --> 00:35:45,353 As manure. 549 00:35:46,555 --> 00:35:48,527 The herds of herbivores were producing 550 00:35:48,527 --> 00:35:51,400 millions of tons of manure everyday. 551 00:35:55,863 --> 00:35:58,115 It's washed away into rivers 552 00:35:59,868 --> 00:36:02,328 until finally it reached the ocean. 553 00:36:04,873 --> 00:36:08,125 And within it was all that silica. 554 00:36:14,007 --> 00:36:15,509 It's out in the oceans that 555 00:36:15,509 --> 00:36:18,510 things really began to take off 556 00:36:18,510 --> 00:36:20,763 because it's out here that there's creatures 557 00:36:20,763 --> 00:36:23,432 that are addicted to this silica. 558 00:36:26,936 --> 00:36:29,397 These creatures are microscopic. 559 00:36:31,016 --> 00:36:33,818 A few hundredths of a millimeter across. 560 00:36:35,361 --> 00:36:39,073 They're diatoms, a type of green algae. 561 00:36:41,366 --> 00:36:44,405 Diatoms are wonderfully delicate, 562 00:36:44,405 --> 00:36:47,499 like some kind of alien architecture. 563 00:36:51,168 --> 00:36:52,836 But essentially for the construction 564 00:36:52,836 --> 00:36:55,996 of their tiny skeletons is silica. 565 00:37:00,106 --> 00:37:01,471 Five million years ago, 566 00:37:01,471 --> 00:37:03,473 they were feasting on huge amounts 567 00:37:03,473 --> 00:37:05,600 of silica from the grasses. 568 00:37:10,771 --> 00:37:13,273 For the diatoms, it was like Christmas. 569 00:37:13,273 --> 00:37:15,192 Their numbers exploded. 570 00:37:18,738 --> 00:37:23,575 (uptempo music) 571 00:37:23,575 --> 00:37:25,786 And diatoms are crucial because they form 572 00:37:25,786 --> 00:37:28,914 the foundation of the ocean's food chain. 573 00:37:30,123 --> 00:37:32,210 With more diatoms came huge shoals 574 00:37:32,210 --> 00:37:34,661 of anchovies and herring that eat them. 575 00:37:36,116 --> 00:37:39,880 This in turn attracts predators like seabirds and dolphins 576 00:37:39,880 --> 00:37:41,928 and even bigger hunters. 577 00:37:49,478 --> 00:37:52,897 But it's from space you really appreciate their importance. 578 00:37:53,731 --> 00:37:56,858 They appear as vast green blooms. 579 00:37:58,770 --> 00:38:01,812 When they bloom, they cover over a tenth of the oceans. 580 00:38:03,407 --> 00:38:05,369 They're green because like plants 581 00:38:05,369 --> 00:38:08,329 diatoms contain chlorophyll, 582 00:38:08,329 --> 00:38:12,083 and like plants, they all release oxygen. 583 00:38:13,209 --> 00:38:15,502 (squawking) 584 00:38:18,047 --> 00:38:20,425 Those photosynthesizing diatoms 585 00:38:20,425 --> 00:38:23,962 produce about a quarter of the oxygen in the atmosphere. 586 00:38:23,962 --> 00:38:27,890 So if you like, every fourth breath you take on average 587 00:38:27,890 --> 00:38:30,143 has been exhaled by the diatoms. 588 00:38:31,060 --> 00:38:33,896 They really are the lungs of the ocean. 589 00:38:38,317 --> 00:38:41,229 It's remarkable what the humble grasses had achieved 590 00:38:41,229 --> 00:38:43,448 by five million years ago. 591 00:38:46,533 --> 00:38:50,819 A once-forested planet was now dominated by open plains. 592 00:38:52,998 --> 00:38:57,962 (uptempo music) 593 00:38:58,675 --> 00:39:01,549 8,000 different species of grasses 594 00:39:01,549 --> 00:39:04,093 covering a quarter of all land. 595 00:39:06,553 --> 00:39:09,974 They'd selected which animals would live or die. 596 00:39:09,974 --> 00:39:14,974 (uptempo music) 597 00:39:15,354 --> 00:39:18,108 And they'd fundamentally altered the oceans 598 00:39:18,108 --> 00:39:19,275 playing a crucial role 599 00:39:19,275 --> 00:39:21,527 in the make-up of our atmosphere. 600 00:39:27,867 --> 00:39:29,952 Yet, perhaps the most important impact 601 00:39:29,952 --> 00:39:33,413 of this remarkable plant was still to come. 602 00:39:41,298 --> 00:39:43,842 The impact on our story. 603 00:39:43,842 --> 00:39:46,635 (vehicle buzzing) 604 00:39:46,635 --> 00:39:48,241 Human beings. 605 00:39:48,241 --> 00:39:53,241 (gentle music) 606 00:39:55,269 --> 00:39:58,731 And that's why I've come to the savanna of West Africa. 607 00:40:03,938 --> 00:40:06,906 I'm in Senegal to see a scientific first. 608 00:40:06,906 --> 00:40:09,992 It's a discovery that's got profound implications 609 00:40:09,992 --> 00:40:12,077 for our understanding of our own past, 610 00:40:12,077 --> 00:40:13,913 because it's here in Africa 611 00:40:13,913 --> 00:40:17,035 that our earliest ape ancestors emerged. 612 00:40:19,669 --> 00:40:21,496 Five million years ago, 613 00:40:21,496 --> 00:40:25,299 why did one group of apes leave the trees for the savanna 614 00:40:25,299 --> 00:40:29,261 and develop so differently eventually becoming human? 615 00:40:29,929 --> 00:40:33,975 Well, the chimpanzees here might provide some answers. 616 00:40:35,184 --> 00:40:37,812 Because unlike almost all other chimps in Africa, 617 00:40:37,812 --> 00:40:41,690 the ones here in Fongoli live on grasslands. 618 00:40:43,942 --> 00:40:44,627 Jill! 619 00:40:44,627 --> 00:40:45,236 Hey! 620 00:40:45,236 --> 00:40:46,195 Hey! 621 00:40:46,195 --> 00:40:46,946 Welcome. 622 00:40:46,946 --> 00:40:47,905 I'm Iain. 623 00:40:47,905 --> 00:40:49,532 It's what makes them so fascinating 624 00:40:49,532 --> 00:40:51,951 to anthropologist Jill Pruetz. 625 00:40:51,951 --> 00:40:53,619 This is HQ, chimp HQ. Yeah. 626 00:40:53,619 --> 00:40:54,745 This is home base. 627 00:40:54,745 --> 00:40:56,986 Everyday we take off wherever they're at. 628 00:41:02,245 --> 00:41:05,788 Jill has spent 10 years studying the Fongoli chimps 629 00:41:12,805 --> 00:41:14,766 She's most interested in parallels 630 00:41:14,766 --> 00:41:17,935 between the unusual behaviors of these chimps 631 00:41:17,935 --> 00:41:19,311 and what might have happened 632 00:41:19,311 --> 00:41:21,480 during the evolution of human beings. 633 00:41:21,480 --> 00:41:23,649 Settled around the waterhole like that. 634 00:41:23,649 --> 00:41:26,184 (chimps screeching) 635 00:41:32,450 --> 00:41:33,910 I wasn't expecting that. 636 00:41:33,910 --> 00:41:35,620 I guess I was expecting them kind of 637 00:41:35,620 --> 00:41:37,705 swinging through the trees, but look at them, 638 00:41:37,705 --> 00:41:40,041 they're just ambling along on all fours. 639 00:41:40,909 --> 00:41:42,668 Perfectly happy down here on the ground 640 00:41:42,668 --> 00:41:44,337 walking through the grass. 641 00:41:46,463 --> 00:41:47,672 And they look so human. 642 00:41:47,672 --> 00:41:50,092 I know, it's obvious, really obvious thing to say 643 00:41:50,092 --> 00:41:52,375 but they just look so human. 644 00:41:56,975 --> 00:41:59,675 The Fongoli chimps have other human attributes. 645 00:42:03,273 --> 00:42:05,399 They are proficient at using tools 646 00:42:05,399 --> 00:42:07,985 like sticks for collecting termites. 647 00:42:10,404 --> 00:42:13,658 Many chimps in Africa catch termites this way, 648 00:42:13,658 --> 00:42:16,660 although these chimps do it more than any others. 649 00:42:22,625 --> 00:42:25,078 But what makes them really special 650 00:42:25,078 --> 00:42:28,838 is a hunting technique, one that is unique. 651 00:42:31,626 --> 00:42:33,928 I think that probably the most exciting discovery made 652 00:42:33,928 --> 00:42:35,387 was that they hunt with tools, 653 00:42:35,387 --> 00:42:37,723 which before we had thought only humans did. 654 00:42:37,723 --> 00:42:38,926 How is that? 655 00:42:38,926 --> 00:42:42,186 They'll fashion branches into sort of like a spear 656 00:42:42,186 --> 00:42:45,056 and they'll use it to jab into these tree holes 657 00:42:45,056 --> 00:42:48,150 where you have another kind of primate, a bush baby. 658 00:42:48,150 --> 00:42:50,528 And then they jab it into the hole. 659 00:42:53,405 --> 00:42:56,159 Jill's filmed this remarkable behavior, 660 00:42:56,159 --> 00:42:58,953 the first time it's ever been recorded. 661 00:43:02,115 --> 00:43:05,000 It shows a chimp using a spear he's made 662 00:43:05,000 --> 00:43:08,087 to stab and kill a mammal, a bush baby. 663 00:43:14,677 --> 00:43:16,069 Yeah, that was something that 664 00:43:16,069 --> 00:43:18,389 again, we sort of had used that to define humans. 665 00:43:18,389 --> 00:43:19,098 Really? Yeah. 666 00:43:19,098 --> 00:43:20,641 So that's starting to blur the boundary. 667 00:43:20,641 --> 00:43:21,808 Yeah. 668 00:43:27,481 --> 00:43:32,481 (chimps screeching) 669 00:43:34,614 --> 00:43:36,657 The chimps of Fongoli are the only ones 670 00:43:36,657 --> 00:43:38,534 in the world that have been observed 671 00:43:38,534 --> 00:43:40,912 using spears to hunt mammals. 672 00:43:40,912 --> 00:43:44,373 (chimps screeching) 673 00:43:44,373 --> 00:43:46,912 Jill believes they've had to come up with this behavior 674 00:43:46,912 --> 00:43:49,920 to cope with the harsh and dry grasslands. 675 00:43:52,839 --> 00:43:55,635 It's a more hostile habitat than the forest 676 00:43:55,635 --> 00:43:58,763 so the chimps here have to be smarter. 677 00:44:03,517 --> 00:44:05,435 And Jill has discovered a final 678 00:44:05,435 --> 00:44:08,389 extraordinary behavior of these chimps. 679 00:44:15,153 --> 00:44:17,239 It also reveals more about how 680 00:44:17,239 --> 00:44:20,192 our ancient ancestors might have evolved 681 00:44:20,192 --> 00:44:22,578 as they moved out of the forests. 682 00:44:24,656 --> 00:44:27,709 This is a nice one I think from the wet season. 683 00:44:27,709 --> 00:44:29,794 So, this is a grassland. 684 00:44:29,794 --> 00:44:31,086 I can see a group of them in there. 685 00:44:31,086 --> 00:44:33,623 Yeah, about three, four of them. 686 00:44:33,623 --> 00:44:36,425 You can see them just above the grass but watch. 687 00:44:36,425 --> 00:44:38,969 Watch what they'll need to do here. 688 00:44:43,467 --> 00:44:46,351 (laughs) 689 00:44:46,351 --> 00:44:47,470 One of them just stood up. 690 00:44:47,470 --> 00:44:48,312 Yeah. 691 00:44:48,312 --> 00:44:51,273 I mean, he obviously has to do that to see over the grass. 692 00:44:51,273 --> 00:44:53,609 I want to see that again, yeah, let me see that. 693 00:44:53,609 --> 00:44:58,529 (gentle instrumental music) 694 00:45:05,371 --> 00:45:08,415 Many scientists think this is perhaps a mirror 695 00:45:08,415 --> 00:45:10,501 of what happened as our own forebears 696 00:45:10,501 --> 00:45:13,534 stood up on the grasslands for the first time. 697 00:45:15,547 --> 00:45:19,134 It allowed them to keep an eye out for predators and prey. 698 00:45:21,386 --> 00:45:24,681 And eventually to evolve walking. 699 00:45:26,345 --> 00:45:29,304 That's incredible to see chimps in the wild standing proud 700 00:45:29,304 --> 00:45:30,396 in the savanna grassland. Yeah, yeah. 701 00:45:30,396 --> 00:45:32,816 And looking incredibly comfortable as well. 702 00:45:32,816 --> 00:45:34,640 It's exciting to see it. 703 00:45:36,068 --> 00:45:37,652 It's the grasslands that's kind of 704 00:45:37,652 --> 00:45:38,905 driving and encouraging them 705 00:45:38,905 --> 00:45:40,240 to develop that way. Yeah, yeah. 706 00:45:40,240 --> 00:45:42,242 What, to be more resourceful, more resilient? 707 00:45:42,242 --> 00:45:43,117 I think so. 708 00:45:43,117 --> 00:45:45,327 They have to be creative and resilient. 709 00:45:46,245 --> 00:45:47,419 I've just got this weird feeling 710 00:45:47,419 --> 00:45:48,948 that I'm looking at a bit of video 711 00:45:48,948 --> 00:45:51,041 from four, five million years ago. 712 00:45:51,041 --> 00:45:52,000 Do you know what I mean? 713 00:45:52,000 --> 00:45:54,003 That could be the scene. Mm-hmm. 714 00:45:57,047 --> 00:45:59,299 Here at Fongoli you can actually see 715 00:45:59,299 --> 00:46:01,427 what scientists think happened when 716 00:46:01,427 --> 00:46:03,929 grasses shaped our ancient ancestors, 717 00:46:03,929 --> 00:46:05,972 and encouraged them to make those first 718 00:46:05,972 --> 00:46:09,310 upright steps onto the savanna. 719 00:46:09,310 --> 00:46:12,688 And it really brings home how our human journey 720 00:46:12,688 --> 00:46:14,856 began on the grasslands. 721 00:46:14,856 --> 00:46:19,856 (gentle instrumental music) 722 00:46:35,169 --> 00:46:37,630 Over the next five million years, 723 00:46:37,630 --> 00:46:41,050 these ape men continued to evolve in Africa. 724 00:46:44,095 --> 00:46:47,640 Until eventually they became homo sapiens. 725 00:46:49,266 --> 00:46:53,854 And then 100,000 years ago, these new people, 726 00:46:53,854 --> 00:46:57,232 for there really were people now, like you and me, 727 00:46:57,232 --> 00:47:00,403 began to migrate across the rest of the world. 728 00:47:03,781 --> 00:47:05,367 At this point in time, 729 00:47:05,367 --> 00:47:08,315 our ancestors were hunter-gatherers. 730 00:47:10,238 --> 00:47:13,499 They were living a tough life in small family groups, 731 00:47:13,499 --> 00:47:14,875 killing wild animals 732 00:47:14,875 --> 00:47:17,753 and collecting berries and roots to eat. 733 00:47:19,630 --> 00:47:22,257 But grasses hadn't finished with us 734 00:47:23,884 --> 00:47:26,595 because they trigger the greatest revolution 735 00:47:26,595 --> 00:47:28,972 in humankind's existence. 736 00:47:29,807 --> 00:47:34,807 (calm instrumental music) 737 00:47:45,488 --> 00:47:48,408 It's not in Africa but here in Southern Turkey 738 00:47:48,408 --> 00:47:50,035 that archaeologists believe 739 00:47:50,035 --> 00:47:53,455 they have discovered why that revolution happened. 740 00:47:56,542 --> 00:47:59,294 The place is called Gobekli Tepe. 741 00:48:03,049 --> 00:48:04,592 For me, this is one of the most 742 00:48:04,592 --> 00:48:07,920 exciting sites of modern archeology 743 00:48:07,920 --> 00:48:09,763 because here at Gobekli Tepe 744 00:48:09,763 --> 00:48:11,849 are some of the oldest buildings in the world. 745 00:48:11,849 --> 00:48:14,136 They date to nearly three times the age 746 00:48:14,136 --> 00:48:15,971 of the first Egyptian pyramids. 747 00:48:15,971 --> 00:48:18,396 And there's a real mystery here. 748 00:48:18,396 --> 00:48:20,399 Who built this place? 749 00:48:20,399 --> 00:48:24,195 And more importantly, how could they have done it? 750 00:48:24,195 --> 00:48:29,033 (slow tempo music) 751 00:48:40,503 --> 00:48:45,466 This astonishing structure is 12,000 years old. 752 00:48:46,251 --> 00:48:50,180 It lay buried and undiscovered until 1994. 753 00:48:53,390 --> 00:48:54,766 Hello. 754 00:48:54,766 --> 00:48:56,012 Hello Iain. 755 00:48:56,012 --> 00:48:57,936 The archaeologist who unearthed it 756 00:48:57,936 --> 00:48:59,432 is Klaus Schmidt. 757 00:48:59,432 --> 00:49:00,271 Well, it's great to be here. 758 00:49:00,271 --> 00:49:02,031 Hi. Welcome in enclosure C. 759 00:49:02,031 --> 00:49:03,816 (laughs) Enclosure C. 760 00:49:03,816 --> 00:49:06,195 What a place! It's spectacular, isn't it? 761 00:49:06,195 --> 00:49:08,196 I mean, these are great. 762 00:49:08,196 --> 00:49:10,073 Big question is who are they? 763 00:49:10,073 --> 00:49:11,491 One thing is very important. 764 00:49:11,491 --> 00:49:13,619 Never a face is depicted, 765 00:49:13,619 --> 00:49:15,411 they are always faceless. 766 00:49:15,411 --> 00:49:16,939 I saw you as you came down, 767 00:49:16,939 --> 00:49:18,582 you were working on a very sophisticated 768 00:49:18,582 --> 00:49:19,165 one here. Yeah, yeah. 769 00:49:19,165 --> 00:49:20,667 This looks amazing, what is it? 770 00:49:20,667 --> 00:49:22,295 It is a masterpiece of craftsmanship. 771 00:49:22,295 --> 00:49:24,754 It's one stone, it's one made from one stone. 772 00:49:24,754 --> 00:49:27,048 We have a flat relief of a boar 773 00:49:27,048 --> 00:49:29,670 and we have this high relief of a leopard. 774 00:49:29,670 --> 00:49:32,137 This is an extremely complex society. 775 00:49:32,137 --> 00:49:34,091 Yes, yes and this is a surprise. 776 00:49:34,091 --> 00:49:36,517 We didn't know this, we didn't expect this. 777 00:49:36,517 --> 00:49:37,601 What we are doing here, 778 00:49:37,601 --> 00:49:40,646 we're at a chapter in world history, 779 00:49:40,646 --> 00:49:44,692 a chapter which we didn't know it exist before. 780 00:49:47,645 --> 00:49:51,989 To construct Gobekli Tepe with its 50-ton megaliths 781 00:49:51,989 --> 00:49:53,492 would have needed a huge army 782 00:49:53,492 --> 00:49:55,910 of well-organized workers. 783 00:50:00,916 --> 00:50:04,703 Yet, 12,000 years ago was the Stone Age, 784 00:50:04,703 --> 00:50:06,338 a time when people were supposed to be 785 00:50:06,338 --> 00:50:09,674 hunter-gatherers living in small groups. 786 00:50:13,470 --> 00:50:15,181 How did they sustain the numbers 787 00:50:15,181 --> 00:50:18,474 essential to build such a vast temple? 788 00:50:27,402 --> 00:50:31,279 The answer lies a short distance away. 789 00:50:34,512 --> 00:50:39,512 (slow tempo music) 790 00:50:48,129 --> 00:50:50,341 Within sights of Gobekli Tepe 791 00:50:50,341 --> 00:50:53,260 are the Karacadag Mountains. 792 00:50:53,260 --> 00:50:55,219 Here something happened at this time 793 00:50:55,219 --> 00:50:57,712 that would change our world forever. 794 00:51:05,022 --> 00:51:08,816 It was all to do with one particular type of grass. 795 00:51:11,445 --> 00:51:13,488 It's an ancient type of wheat 796 00:51:13,488 --> 00:51:17,367 which grew totally wild, just as it does today. 797 00:51:17,367 --> 00:51:19,452 it's called einkorn wheat. 798 00:51:23,624 --> 00:51:28,336 12,000 years ago was a time before farming. 799 00:51:28,336 --> 00:51:29,713 The people here would have been desperate 800 00:51:29,713 --> 00:51:32,257 for whatever nutrition they could gather. 801 00:51:37,304 --> 00:51:40,433 Yet collecting it presented a huge problem. 802 00:51:40,433 --> 00:51:42,310 Let me show you why. 803 00:51:43,852 --> 00:51:45,137 When the head of the wheat is ripe 804 00:51:45,137 --> 00:51:49,275 then just the tinniest of touches and look what happens. 805 00:51:49,275 --> 00:51:51,276 It just scatters everywhere. 806 00:51:55,880 --> 00:51:57,407 And that's because the seed is 807 00:51:57,407 --> 00:52:00,660 attached to the plant so precariously. 808 00:52:00,660 --> 00:52:01,787 Imagine if you were trying to collect 809 00:52:01,787 --> 00:52:03,455 enough seed for a meal. 810 00:52:03,455 --> 00:52:06,583 I mean, I can hardly even see where they are. 811 00:52:06,583 --> 00:52:08,409 Here's one. Ah, dropped it. 812 00:52:09,245 --> 00:52:10,993 It would drive you mad. 813 00:52:18,837 --> 00:52:22,463 Frankly, it's hard to believe anyone would bother. 814 00:52:23,309 --> 00:52:25,686 But everything was about to change, 815 00:52:25,686 --> 00:52:28,313 triggered by a crucial event. 816 00:52:30,189 --> 00:52:33,394 A tiny alteration in the genetic makeup 817 00:52:33,394 --> 00:52:35,564 of a wild wheat plant. 818 00:52:35,564 --> 00:52:40,534 Just one gene in just one single plant. 819 00:52:46,707 --> 00:52:49,668 That mutation has been traced back to here, 820 00:52:49,668 --> 00:52:53,171 just 30 kilometers from Gobekli Tepe. 821 00:52:57,134 --> 00:52:59,637 If you look closely, you can see the difference 822 00:52:59,637 --> 00:53:01,805 between the two types of wheat. 823 00:53:06,518 --> 00:53:10,730 In the original wild wheat, a special ridge of cells 824 00:53:10,730 --> 00:53:12,559 between the stalk and the seed 825 00:53:12,559 --> 00:53:15,068 breaks down as the plant ripens, 826 00:53:15,861 --> 00:53:18,363 and this allows the seed to fall away. 827 00:53:21,700 --> 00:53:24,578 But in the wheat with the genetic mutation, 828 00:53:24,578 --> 00:53:27,330 these cells remain as a solid band. 829 00:53:31,627 --> 00:53:35,119 It means the new wheat never lets go of its seeds. 830 00:53:38,341 --> 00:53:40,136 Under normal circumstances in the wild 831 00:53:40,136 --> 00:53:41,637 that would doom the plant 832 00:53:41,637 --> 00:53:43,264 because it just couldn't scatter the seeds. 833 00:53:43,264 --> 00:53:46,307 Look, you bang it and nothing happens. 834 00:53:46,307 --> 00:53:49,061 But it turns out that for one animal species 835 00:53:49,061 --> 00:53:51,979 this trait was really beneficial. 836 00:53:52,772 --> 00:53:54,024 Us. 837 00:53:54,649 --> 00:53:59,649 (gentle music) 838 00:54:18,507 --> 00:54:22,094 Because the seed remained on the stalk after it ripened, 839 00:54:22,094 --> 00:54:24,638 it meant that not only could the people who lived here 840 00:54:24,638 --> 00:54:27,676 collect more grain, they could also begin to farm it. 841 00:54:27,676 --> 00:54:28,851 In other words, they can take 842 00:54:28,851 --> 00:54:31,268 some of the spare seeds at the end of a season, 843 00:54:31,268 --> 00:54:32,812 put it back in the ground 844 00:54:32,812 --> 00:54:36,024 and then harvest the new plants the following year. 845 00:54:36,024 --> 00:54:38,776 It was the dawn of domesticated wheat. 846 00:54:42,241 --> 00:54:46,235 (wheat rustling) 847 00:54:53,626 --> 00:54:56,961 And this wheat gave us bread. 848 00:54:58,705 --> 00:55:02,001 A fabulously concentrated form of energy. 849 00:55:02,001 --> 00:55:03,635 It could be carried, 850 00:55:03,635 --> 00:55:05,970 it could be divided up, it could be stored. 851 00:55:08,007 --> 00:55:12,060 And in turn, bread would lead to something even bigger. 852 00:55:12,060 --> 00:55:17,060 (slow tempo music) 853 00:55:19,735 --> 00:55:22,321 In order to build Gobekli Tepe, 854 00:55:22,321 --> 00:55:25,615 the Stone Age people turned their back on hunter-gathering. 855 00:55:29,578 --> 00:55:32,656 They became the first farmers. 856 00:55:36,710 --> 00:55:38,629 12,000 years ago, they began 857 00:55:38,629 --> 00:55:41,464 to sustain themselves with bread 858 00:55:43,091 --> 00:55:46,010 made from the grass we call wheat. 859 00:55:51,516 --> 00:55:53,645 Now they could feed the huge workforce 860 00:55:53,645 --> 00:55:56,063 required to construct such a vast 861 00:55:56,063 --> 00:55:58,430 and sophisticated temple. 862 00:56:01,479 --> 00:56:04,730 The mystery of Gobekli Tepe was solved. 863 00:56:05,447 --> 00:56:06,990 People had been hunter-gatherers 864 00:56:06,990 --> 00:56:10,258 and now this site marks the end of that time, 865 00:56:10,258 --> 00:56:13,538 the end of the period and the beginning of a new age. 866 00:56:16,123 --> 00:56:18,752 So Gobekli Tepe is part of that chain reaction? 867 00:56:18,752 --> 00:56:19,961 It's a cultural-- 868 00:56:19,961 --> 00:56:21,963 The people being in Gobekli Tepe 869 00:56:21,963 --> 00:56:25,468 are the first people having bread also in the villages, 870 00:56:25,468 --> 00:56:27,553 not only here but also in the villages. 871 00:56:27,553 --> 00:56:28,511 That's incredible, isn't it? 872 00:56:28,511 --> 00:56:29,763 To think that these were the first people 873 00:56:29,763 --> 00:56:31,181 that's gonna taste bread Yeah. 874 00:56:31,181 --> 00:56:32,182 And it was (mumbles). Yeah, for sure. 875 00:56:32,182 --> 00:56:34,593 And the idea then that it was bread 876 00:56:34,593 --> 00:56:36,603 that was the kind of energy source essentially, 877 00:56:36,603 --> 00:56:37,437 the sustenance. 878 00:56:37,437 --> 00:56:38,650 Exactly, exactly. 879 00:56:38,650 --> 00:56:41,389 It's a turning point in world history. 880 00:56:48,864 --> 00:56:53,864 (lighthearted piano music) 881 00:56:59,835 --> 00:57:02,118 There's one last thing that I find intriguing. 882 00:57:03,707 --> 00:57:05,339 Our ancestors must have felt 883 00:57:05,339 --> 00:57:07,758 that they were the masters of this new crop, 884 00:57:07,758 --> 00:57:09,677 in the same way that we still feel today. 885 00:57:09,677 --> 00:57:12,097 But in farming we are in control of the plants 886 00:57:12,097 --> 00:57:14,405 that we grow and harvest. 887 00:57:14,405 --> 00:57:17,436 But think of it for a minute from the wheat's point of view. 888 00:57:17,436 --> 00:57:20,271 I mean, here's a plant that's done something really clever. 889 00:57:20,271 --> 00:57:22,482 It's attracted an animal that's prepared 890 00:57:22,482 --> 00:57:24,734 to sow it, to nurture it, 891 00:57:24,734 --> 00:57:28,612 to protect it from competitors and scavengers. 892 00:57:28,612 --> 00:57:32,409 It's also prepared to disperse its seed by hand 893 00:57:32,409 --> 00:57:35,579 without the plant having to do a single thing. 894 00:57:37,073 --> 00:57:41,084 So, it begs the question, who's using who? 895 00:57:42,752 --> 00:57:47,752 (lighthearted music) 896 00:57:53,847 --> 00:57:56,183 Human beings had now invented 897 00:57:56,183 --> 00:57:59,477 a way of harnessing the power of plants, 898 00:57:59,477 --> 00:58:03,398 and once invented, it could never be reversed. 899 00:58:03,398 --> 00:58:05,357 Because farming allowed us to come together 900 00:58:05,357 --> 00:58:07,903 in bigger and bigger groups, 901 00:58:07,903 --> 00:58:12,699 to build villages, towns and eventually cities. 902 00:58:13,749 --> 00:58:18,749 (lighthearted music) 903 00:58:24,836 --> 00:58:28,714 A world once dominated by forests and dinosaurs 904 00:58:28,714 --> 00:58:31,384 had given way to a world of our own making. 905 00:58:31,384 --> 00:58:36,384 (lighthearted music) 906 00:58:41,227 --> 00:58:43,689 I've always been fascinated by how our planet 907 00:58:43,689 --> 00:58:45,856 changes over time, 908 00:58:45,856 --> 00:58:49,485 over the 4 1/2 billion years of Earth history. 909 00:58:49,485 --> 00:58:52,738 And what's astounding is how important plants have been 910 00:58:52,738 --> 00:58:56,325 in changing that original lifeless rock 911 00:58:56,325 --> 00:59:00,153 into this vital and vibrant world that we live in today. 912 00:59:01,039 --> 00:59:02,573 Our home. 913 00:59:04,960 --> 00:59:06,837 Over this series, we've seen how plants 914 00:59:06,837 --> 00:59:10,130 gave us the oxygen in the atmosphere. 915 00:59:12,418 --> 00:59:14,802 We've watched as the rise of flowers 916 00:59:14,802 --> 00:59:18,481 painted a drab world with brilliant color. 917 00:59:20,350 --> 00:59:22,227 And we've discovered how plants 918 00:59:22,227 --> 00:59:24,812 shape the animal kingdom. 919 00:59:30,818 --> 00:59:32,862 And for us, the humble grasses 920 00:59:32,862 --> 00:59:35,657 play the most important role of all. 921 00:59:35,657 --> 00:59:39,119 They drove the rise of our ape-like ancestors 922 00:59:39,119 --> 00:59:43,613 and ultimately, triggered the birth of civilization. 923 00:59:44,450 --> 00:59:47,669 Plants made us and the world we live in. 924 00:59:47,669 --> 00:59:52,669 (lighthearted music)