1 00:00:15,500 --> 00:00:21,859 I'm on a fantastic journey to look for the origins of life. 2 00:00:21,860 --> 00:00:26,059 I shall be traveling not only around the world, but back in time, 3 00:00:26,060 --> 00:00:27,939 to try and build a picture 4 00:00:27,940 --> 00:00:31,540 of what life was like in that very early period. 5 00:00:33,060 --> 00:00:35,619 It will be a journey full of wonders. 6 00:00:35,620 --> 00:00:39,019 Parts of it were unknown until only a few years ago. 7 00:00:39,020 --> 00:00:44,219 In 50 years of programme-making, I've been lucky enough to explore 8 00:00:44,220 --> 00:00:47,260 the living world in all its splendor and complexity. 9 00:00:50,620 --> 00:00:56,380 The blue whale! The biggest creature that exists on the planet! 10 00:01:00,900 --> 00:01:04,659 Now, I'm off to explore the origins of all this. 11 00:01:04,660 --> 00:01:08,500 To look for the very first living creatures that appeared on the planet. 12 00:01:12,100 --> 00:01:17,019 In recent years, scientists have unearthed dramatic evidence of what those first creatures were like. 13 00:01:17,020 --> 00:01:21,380 We can also find clues in living animals. 14 00:01:23,620 --> 00:01:27,059 And this enchanting little creature 15 00:01:27,060 --> 00:01:28,619 is what we were looking for. 16 00:01:28,620 --> 00:01:33,939 Using the latest technology, it's possible to bring those first animals to life 17 00:01:33,940 --> 00:01:37,580 for the first time in half a billion years. 18 00:01:39,060 --> 00:01:41,299 From the moment they appeared 19 00:01:41,300 --> 00:01:45,059 to the time that they took their pioneering steps on land, 20 00:01:45,060 --> 00:01:48,819 we can deduce how animals acquired bodies that move, 21 00:01:48,820 --> 00:01:53,780 eyes that saw and mouths that ate. 22 00:01:57,140 --> 00:02:00,539 And we can understand how those first organisms 23 00:02:00,540 --> 00:02:05,100 laid the foundations for modern animals as we know them today. 24 00:02:06,380 --> 00:02:09,059 Hello, old boy. How are you? 25 00:02:09,060 --> 00:02:12,100 'Including you and me.' 26 00:02:21,740 --> 00:02:26,380 My 40,000 mile journey begins very close to home, in Britain. 27 00:02:28,260 --> 00:02:33,859 This is the Charnwood Forest in Leicestershire in the middle of England. 28 00:02:33,860 --> 00:02:37,259 As a schoolboy, I grew up near here. 29 00:02:37,260 --> 00:02:39,859 And in these rocks, a discovery was made 30 00:02:39,860 --> 00:02:42,739 that transformed our understanding 31 00:02:42,740 --> 00:02:46,660 of that mystery of mysteries, the origin of life. 32 00:02:51,860 --> 00:02:56,699 The history of life can be thought of as a many-branched tree, 33 00:02:56,700 --> 00:02:58,819 with all the species alive today 34 00:02:58,820 --> 00:03:02,220 related to common ancestors down near the base. 35 00:03:03,980 --> 00:03:10,059 The five kingdoms of life, the main branches, were established early on. 36 00:03:10,060 --> 00:03:12,539 Bacteria. 37 00:03:12,540 --> 00:03:16,180 Protists - amoeba-like creatures. 38 00:03:17,540 --> 00:03:20,220 Fungi. 39 00:03:21,180 --> 00:03:24,379 Plants. 40 00:03:24,380 --> 00:03:29,619 And animals. That for me is the most fascinating question of all. 41 00:03:29,620 --> 00:03:34,459 How and when did they first appear? 42 00:03:34,460 --> 00:03:38,099 The answers are only now beginning to emerge - 43 00:03:38,100 --> 00:03:42,420 and some of the first clues came from here in Charnwood Forest. 44 00:03:43,940 --> 00:03:47,339 I was a passionate fossil collector. 45 00:03:47,340 --> 00:03:51,579 But I never came to look for them in this part of Charnwood, 46 00:03:51,580 --> 00:03:55,339 because the rocks here are among the most ancient in the world. 47 00:03:55,340 --> 00:03:58,139 Around 600 million years old, in fact. 48 00:03:58,140 --> 00:04:03,219 And every geologist knew or at least was convinced that rocks of 49 00:04:03,220 --> 00:04:08,699 such extreme age couldn't possibly contain fossils of any kind. 50 00:04:08,700 --> 00:04:13,339 And then a boy from my very own school, just a few years after I left it, 51 00:04:13,340 --> 00:04:16,300 made an astounding discovery. 52 00:04:17,340 --> 00:04:20,739 Against all the predictions of scientific know-alls, 53 00:04:20,740 --> 00:04:25,939 he found a fossil in these ancient Leicestershire rocks. 54 00:04:25,940 --> 00:04:28,939 And this is it. 55 00:04:28,940 --> 00:04:33,419 It's called and is known around the world as Charnia, 56 00:04:33,420 --> 00:04:36,619 after the forest in which it was discovered. 57 00:04:36,620 --> 00:04:38,179 But what is it? 58 00:04:38,180 --> 00:04:40,819 Is it animal or plant? 59 00:04:40,820 --> 00:04:44,179 The fact is it comes from such a remote period 60 00:04:44,180 --> 00:04:48,379 that the distinction between those two forms of life was not yet clear. 61 00:04:48,380 --> 00:04:50,539 But one thing is certain. 62 00:04:50,540 --> 00:04:52,940 It clearly was alive. 63 00:04:55,260 --> 00:04:59,259 Charnia was a marine organism, part of an ancient community 64 00:04:59,260 --> 00:05:03,819 of living things that lived in darkness at the bottom of an ocean. 65 00:05:03,820 --> 00:05:06,659 That much we do know. 66 00:05:06,660 --> 00:05:10,099 But what was this strange creature? 67 00:05:10,100 --> 00:05:12,739 When did it first appear? 68 00:05:12,740 --> 00:05:15,619 And how is it related to modern animals? 69 00:05:15,620 --> 00:05:19,860 The answers to these questions are only now beginning to emerge. 70 00:05:22,300 --> 00:05:27,299 There were further finds in Charnwood forest, like this disk, 71 00:05:27,300 --> 00:05:29,659 which was probably the holdfast 72 00:05:29,660 --> 00:05:33,459 which secured the frond of Charnia to the sea floor. 73 00:05:33,460 --> 00:05:38,339 And then people began to look in rocks of this great age 74 00:05:38,340 --> 00:05:40,499 all around the world. 75 00:05:40,500 --> 00:05:44,819 And lo and behold they discovered a whole range of fossils 76 00:05:44,820 --> 00:05:50,219 that enable us now to put together in extraordinary detail 77 00:05:50,220 --> 00:05:53,139 the first chapters in the history of life. 78 00:05:53,140 --> 00:05:58,099 That all happened a very long time ago. 79 00:05:58,100 --> 00:06:02,220 Imagine traveling back through time. 80 00:06:10,940 --> 00:06:17,219 Humans have been around for two million years. 81 00:06:17,220 --> 00:06:22,580 The dinosaurs were wiped out 65 million years ago. 82 00:06:29,540 --> 00:06:34,019 Charnia is more than eight times older than the oldest dinosaur. 83 00:06:34,020 --> 00:06:38,100 It lived about 560 million years ago. 84 00:06:40,340 --> 00:06:45,779 But compared with the age of life itself, that's nothing. 85 00:06:45,780 --> 00:06:49,659 Before Charnia and other complex organisms existed, 86 00:06:49,660 --> 00:06:54,779 the only living things were microscopic single cells. 87 00:06:54,780 --> 00:06:58,739 They first appeared about three and a half billion years ago 88 00:06:58,740 --> 00:07:01,580 when the Earth was a very different place. 89 00:07:06,620 --> 00:07:09,180 The early continents were still forming. 90 00:07:11,940 --> 00:07:16,099 The days were a mere six hours long, because at that time 91 00:07:16,100 --> 00:07:21,060 the Earth was spinning much faster on its axis than it does today. 92 00:07:30,460 --> 00:07:34,899 The land was dominated by volcanoes - 93 00:07:34,900 --> 00:07:37,460 hostile and lifeless. 94 00:07:46,380 --> 00:07:52,019 But deep in the oceans, life had begun. 95 00:07:52,020 --> 00:07:57,219 The latest theory is that chemicals spewing from underwater volcanic vents 96 00:07:57,220 --> 00:08:00,659 solidified and created towers like these, 97 00:08:00,660 --> 00:08:04,820 and this produced the conditions needed for the first cells to form. 98 00:08:06,340 --> 00:08:13,340 Some of these began to harness the energy of sunlight, just as plants do today, and formed colonies. 99 00:08:14,940 --> 00:08:18,699 These rocky stromatolites in western Australia 100 00:08:18,700 --> 00:08:22,500 have been constructed by very similar photosynthesizing bacteria. 101 00:08:28,980 --> 00:08:32,699 Others managed to survive by extracting nourishment directly 102 00:08:32,700 --> 00:08:38,700 from the environment, like the fungi and animals that would later evolve. 103 00:08:44,060 --> 00:08:49,020 This state of affairs continued for a vast period of time. 104 00:08:52,660 --> 00:08:58,419 For some three billion years, simple microscopic organisms 105 00:08:58,420 --> 00:09:01,899 were the most advanced form of life on the planet. 106 00:09:01,900 --> 00:09:07,139 That's way over half the entire history of life on Earth. 107 00:09:07,140 --> 00:09:11,819 And then suddenly, within the space of a few million years, a mere 108 00:09:11,820 --> 00:09:16,939 blink of the eye in evolutionary terms, advanced organisms appeared. 109 00:09:16,940 --> 00:09:19,459 Why is a mystery, 110 00:09:19,460 --> 00:09:25,340 but we may find some clues to it on the coastline down here. 111 00:09:27,260 --> 00:09:31,619 On the Eastern coast of Canada, there is evidence of an event that 112 00:09:31,620 --> 00:09:35,660 may well have been the spark that started the evolution of animals. 113 00:09:38,220 --> 00:09:43,219 These rocks have been dated by radioactivity 114 00:09:43,220 --> 00:09:47,259 to just before the moment that life became very complex. 115 00:09:47,260 --> 00:09:52,299 So if we can understand the circumstances under which these rocks were formed, 116 00:09:52,300 --> 00:09:57,700 we may get a clue as to why it was that life suddenly became more complex. 117 00:09:59,900 --> 00:10:05,419 Fragments of red stone are embedded in the darker rock. 118 00:10:05,420 --> 00:10:07,779 They look out of place. 119 00:10:07,780 --> 00:10:09,780 And, in fact, they are. 120 00:10:11,300 --> 00:10:15,139 Geologists call them dropstones. 121 00:10:15,140 --> 00:10:19,539 They were transported here by glaciers. 122 00:10:19,540 --> 00:10:21,139 As the ice moved off the land, 123 00:10:21,140 --> 00:10:24,059 it floated out over the sea in a great shelf, 124 00:10:24,060 --> 00:10:27,739 carrying with it stones that it had gathered on the continents. 125 00:10:27,740 --> 00:10:30,219 And when the ice eventually melted, 126 00:10:30,220 --> 00:10:33,899 the stones fell into the sediments on the sea floor. 127 00:10:33,900 --> 00:10:37,139 This wasn't the only place covered by ice. 128 00:10:37,140 --> 00:10:41,540 Drop stones of the same age have been found in deposits all over the world. 129 00:10:43,220 --> 00:10:48,259 The evidence points to a global spread of glaciation. 130 00:10:48,260 --> 00:10:52,539 Just before complex life appeared, the world was in the grip 131 00:10:52,540 --> 00:10:55,660 of the biggest ice age in its entire history. 132 00:11:30,420 --> 00:11:34,740 It's been called Snowball Earth. 133 00:11:39,020 --> 00:11:42,219 The Earth was plunged into a deep freeze 134 00:11:42,220 --> 00:11:44,379 so severe it probably extended 135 00:11:44,380 --> 00:11:46,179 from pole to pole. 136 00:11:46,180 --> 00:11:49,179 The surface of the seas were frozen over. 137 00:11:49,180 --> 00:11:52,659 On the continents, ice caps and glaciers developed. 138 00:11:52,660 --> 00:11:57,219 In places, the ice was probably a kilometer or so thick. 139 00:11:57,220 --> 00:12:01,139 We still don't know enough about the details, but it's likely that 140 00:12:01,140 --> 00:12:04,700 those conditions lasted for millions of years. 141 00:12:08,900 --> 00:12:13,859 Stromatolites and similar bacterial colonies that dominated the Earth 142 00:12:13,860 --> 00:12:16,780 were crushed under the advancing glaciers. 143 00:12:21,620 --> 00:12:26,300 Life was nearly annihilated before it had truly begun. 144 00:12:31,060 --> 00:12:36,259 It's difficult to imagine how life managed to survive in those circumstances. 145 00:12:36,260 --> 00:12:38,700 But survive it did. 146 00:12:43,420 --> 00:12:45,979 Microbiologist Dr Hazel Barton 147 00:12:45,980 --> 00:12:50,500 believes that modern glaciers can tell us how it did so. 148 00:12:52,420 --> 00:12:56,499 She has come to the Columbia Icefield in the Rocky Mountains 149 00:12:56,500 --> 00:13:02,579 in search of organisms that are still able to endure such extremes today. 150 00:13:02,580 --> 00:13:04,139 The thing about being here 151 00:13:04,140 --> 00:13:06,899 is it looks like everything's been wiped clean, 152 00:13:06,900 --> 00:13:09,899 the glacier's come through and it's destroyed all life, 153 00:13:09,900 --> 00:13:11,299 there's nothing living. 154 00:13:11,300 --> 00:13:14,059 But to a microbiologist this looks a bit like a rainforest. 155 00:13:14,060 --> 00:13:17,379 From here you can see discoloration on the surface of the ice, 156 00:13:17,380 --> 00:13:19,699 but that's not dirt - 157 00:13:19,700 --> 00:13:23,339 that is photosynthetic bacteria that are surviving there 158 00:13:23,340 --> 00:13:26,219 and that creates an ecosystem where you have plants 159 00:13:26,220 --> 00:13:29,459 and you have predators come in and feed on those organisms. 160 00:13:29,460 --> 00:13:33,060 So even though it looks dead, it's actually wildly alive with life. 161 00:13:34,580 --> 00:13:39,059 The kind of life you can see here is pretty ancient. 162 00:13:39,060 --> 00:13:42,579 They've had to adapt to a lot of global catastrophes. 163 00:13:42,580 --> 00:13:45,980 They had to adapt to Snowball Earth. 164 00:13:46,860 --> 00:13:51,019 Microorganisms that live in these harsh environments we call extremophiles. 165 00:13:51,020 --> 00:13:56,859 They have an amazing amount of adaptability that's hardwired in their genomes. 166 00:13:56,860 --> 00:14:00,619 You can freeze them, you can bury them a mile down in ice 167 00:14:00,620 --> 00:14:04,100 and its not much of a hindrance because of their adaptable nature. 168 00:14:07,740 --> 00:14:13,539 We owe our existence to ice-dwelling extremophiles. 169 00:14:13,540 --> 00:14:16,939 Snowball Earth almost extinguished life, 170 00:14:16,940 --> 00:14:21,380 but tiny organisms like these hung on for millions of years. 171 00:14:23,940 --> 00:14:26,099 I think what you had is 172 00:14:26,100 --> 00:14:29,019 organisms that could withstand extreme environments 173 00:14:29,020 --> 00:14:32,139 conditioning themselves to this changing ecosystem. 174 00:14:32,140 --> 00:14:35,019 You had a skin of microbes on the surface of the planet, 175 00:14:35,020 --> 00:14:39,779 and you had these organisms living between where the, the glaciers contacted the rock, 176 00:14:39,780 --> 00:14:42,459 and that was enough life trickling over so that 177 00:14:42,460 --> 00:14:46,299 when those conditions retreated, and it became more favorable, 178 00:14:46,300 --> 00:14:49,380 then it was like, pff, and everything took off again. 179 00:14:57,660 --> 00:15:01,220 Finally, Snowball Earth began to warm. 180 00:15:06,580 --> 00:15:09,739 There is evidence that around this time, 181 00:15:09,740 --> 00:15:13,340 there was a global surge in volcanic activity. 182 00:15:17,460 --> 00:15:22,940 Eruptions punched through the ice, spewing carbon dioxide into the air. 183 00:15:27,020 --> 00:15:30,779 As it spread through the atmosphere, it produced a greenhouse effect, 184 00:15:30,780 --> 00:15:36,180 trapping heat so that the earth warmed and the ice melted. 185 00:15:56,300 --> 00:15:59,899 We still have a lot to discover about what happened next, 186 00:15:59,900 --> 00:16:04,339 but it seems likely that it was the melting of Snowball Earth 187 00:16:04,340 --> 00:16:08,060 that led to the next great development of life. 188 00:16:19,660 --> 00:16:22,299 As the glaciers retreated, 189 00:16:22,300 --> 00:16:27,500 so nutrient-rich meltwater flooded into the oceans. 190 00:16:42,540 --> 00:16:48,899 For the surviving cells, this flood of ground-up rock was a bonanza. 191 00:16:48,900 --> 00:16:52,819 For the microbes that could photosynthesize, 192 00:16:52,820 --> 00:16:55,899 the pulverized rock was a potent fertilizer. 193 00:16:55,900 --> 00:17:02,299 And their growth would have a direct influence on early animal cells. 194 00:17:02,300 --> 00:17:06,659 Cyanobacteria and other oxygen-producing microbes 195 00:17:06,660 --> 00:17:09,340 began to bloom across the globe. 196 00:17:13,020 --> 00:17:16,939 These flourished in colonies of plant-like microbes 197 00:17:16,940 --> 00:17:20,180 that pumped out enormous volumes of oxygen. 198 00:17:21,700 --> 00:17:23,979 And it was this increase in oxygen 199 00:17:23,980 --> 00:17:27,460 that was the key to the rise of the animal kingdom. 200 00:17:30,260 --> 00:17:32,779 Now, simple microscopic life 201 00:17:32,780 --> 00:17:37,660 had the fuel it needed to develop into something bigger. 202 00:17:41,940 --> 00:17:45,619 After billions of years of single-celled life, 203 00:17:45,620 --> 00:17:49,060 something amazing happened in the deep sea. 204 00:17:50,940 --> 00:17:55,699 Up to this moment, living cells that had been produced by division 205 00:17:55,700 --> 00:17:58,540 simply drifted away from one another. 206 00:18:02,940 --> 00:18:05,819 But now, with the aid of increased oxygen, 207 00:18:05,820 --> 00:18:08,340 some cells were sticking together. 208 00:18:10,540 --> 00:18:15,220 Some of these clumps ultimately evolved into animals. 209 00:18:16,740 --> 00:18:19,619 To find out how oxygen drove this process, 210 00:18:19,620 --> 00:18:22,419 I have come to Australia's Barrier Reef, 211 00:18:22,420 --> 00:18:26,219 to look at one of the most primitive of animals alive today - 212 00:18:26,220 --> 00:18:29,140 one that can truly be called a living fossil. 213 00:18:31,460 --> 00:18:35,539 It is one of the simplest multi-celled organisms that we know, 214 00:18:35,540 --> 00:18:38,939 but its basic body structure has nonetheless enabled it 215 00:18:38,940 --> 00:18:44,299 to survive virtually unchanged for around 600 million years. 216 00:18:44,300 --> 00:18:46,459 It's a sponge. 217 00:18:46,460 --> 00:18:51,779 Sponges are just collections of simple cells 218 00:18:51,780 --> 00:18:54,979 that have clumped together and got stuck together. 219 00:18:54,980 --> 00:18:58,739 They don't have a digestive system or a nervous system 220 00:18:58,740 --> 00:19:00,859 or a blood circulatory system, 221 00:19:00,860 --> 00:19:03,419 and they get their food and their oxygen 222 00:19:03,420 --> 00:19:08,819 by just pumping seawater through channels in the body. 223 00:19:08,820 --> 00:19:14,139 But they can give us an indication of how it was that cells 224 00:19:14,140 --> 00:19:18,380 first clumped together to form bodies of any real size. 225 00:19:20,620 --> 00:19:24,099 At the microscopic level, sponge cells are bound together 226 00:19:24,100 --> 00:19:29,580 by a tangle of hairy, stringy protein molecules called collagen. 227 00:19:31,140 --> 00:19:36,620 This collagen glue is found only animals, and nowhere else. 228 00:19:38,860 --> 00:19:45,019 Collagen is sometimes called the sticky tape of the animal world. 229 00:19:45,020 --> 00:19:47,819 It's the commonest protein in our body. 230 00:19:47,820 --> 00:19:50,699 It forms the framework of our skins. 231 00:19:50,700 --> 00:19:53,339 Plastic surgeons use it to pump up our lips. 232 00:19:53,340 --> 00:19:57,739 You need oxygen to manufacture collagen 233 00:19:57,740 --> 00:20:00,819 and with the rising amount of oxygen in the atmosphere 234 00:20:00,820 --> 00:20:06,060 at the end of Snowball Earth, cells were able to manufacture it. 235 00:20:08,540 --> 00:20:12,339 At the Research Station on Heron Island on the Great Barrier Reef, 236 00:20:12,340 --> 00:20:14,619 scientists are working to understand 237 00:20:14,620 --> 00:20:18,099 how it was that multi-celled organisms 238 00:20:18,100 --> 00:20:19,940 began to colonize the earth. 239 00:20:20,740 --> 00:20:25,219 To find the answer, marine biologist Professor Bernard Degnan 240 00:20:25,220 --> 00:20:28,419 is studying sponges. 241 00:20:28,420 --> 00:20:31,859 The things that connect sponges to the rest of the animal kingdom 242 00:20:31,860 --> 00:20:35,339 we can find at the level of the cell and the gene. 243 00:20:35,340 --> 00:20:39,419 When we look at its genes, it's clearly an animal. 244 00:20:39,420 --> 00:20:42,620 We look for the things that bind all animals together, 245 00:20:43,300 --> 00:20:46,819 so what does a human share not only with a chimpanzee 246 00:20:46,820 --> 00:20:50,300 and for that matter a tiger but what it shares with a sponge. 247 00:20:51,380 --> 00:20:53,459 If we can find any common threads, 248 00:20:53,460 --> 00:20:56,979 we're getting really to the heart of the matter of multicellularity 249 00:20:56,980 --> 00:20:59,420 in the animal kingdom, so that's the key. 250 00:21:03,420 --> 00:21:08,179 A classic experiment gives us some insight. 251 00:21:08,180 --> 00:21:12,460 First, a sponge is cut into small pieces. 252 00:21:18,500 --> 00:21:23,179 Then it is pushed through a sieve on the end of a syringe. 253 00:21:23,180 --> 00:21:26,500 This breaks the animal down into its individual cells. 254 00:21:30,580 --> 00:21:34,499 This may seem a brutal thing to do to a living organism, 255 00:21:34,500 --> 00:21:38,060 but to a sponge this is of no consequence. 256 00:21:41,060 --> 00:21:46,180 In response, it does something quite astonishing. 257 00:21:47,900 --> 00:21:51,979 The cells begin to move... 258 00:21:51,980 --> 00:21:54,380 and then they form clumps. 259 00:21:56,580 --> 00:22:00,179 Soon the clumps form bigger clumps, 260 00:22:00,180 --> 00:22:06,379 until three weeks later, a miniature sponge has formed. 261 00:22:06,380 --> 00:22:11,620 Sponges have this amazing capacity to regenerate themselves. 262 00:22:13,340 --> 00:22:16,379 And what we can do is actually rebuild a sponge 263 00:22:16,380 --> 00:22:18,580 from the cell level up. 264 00:22:25,460 --> 00:22:28,779 From this experiment, we can maybe infer a few things 265 00:22:28,780 --> 00:22:32,339 that happened 600 million years ago with the very first animals. 266 00:22:32,340 --> 00:22:37,299 We can infer that there were cells coming together, 267 00:22:37,300 --> 00:22:41,259 they could adhere to each other, they used extracellular proteins 268 00:22:41,260 --> 00:22:44,819 like collagen to glue themselves together. 269 00:22:44,820 --> 00:22:47,539 They had the ability to communicate with each other 270 00:22:47,540 --> 00:22:52,259 and a certain amount of flexibility that allowed them to interact 271 00:22:52,260 --> 00:22:55,579 to give rise to something that's bigger and greater, 272 00:22:55,580 --> 00:22:59,340 a large macroscopic multicellular animal. 273 00:23:01,180 --> 00:23:05,499 The advantages of being multi-celled were many. 274 00:23:05,500 --> 00:23:08,259 Colonies of cells could collect more food, 275 00:23:08,260 --> 00:23:10,979 control their internal environment 276 00:23:10,980 --> 00:23:14,060 and act efficiently by working as a team. 277 00:23:15,580 --> 00:23:17,620 It was just the beginning. 278 00:23:20,380 --> 00:23:23,219 In Canada, there is an extraordinary place 279 00:23:23,220 --> 00:23:25,420 that reveals what happened next. 280 00:23:26,980 --> 00:23:31,739 Here you can see how just a few million years after the melting of Snowball Earth, 281 00:23:31,740 --> 00:23:36,539 the earliest multi-celled organisms became much more sophisticated... 282 00:23:36,540 --> 00:23:38,900 and much bigger. 283 00:23:42,340 --> 00:23:45,979 This is Mistaken Point in Newfoundland. 284 00:23:45,980 --> 00:23:51,299 It got that name because in years gone by sailors coming up the eastern coast of North America 285 00:23:51,300 --> 00:23:54,219 but lost in the fogs that are so frequent here 286 00:23:54,220 --> 00:23:56,419 would head north for the open ocean 287 00:23:56,420 --> 00:23:59,020 but be wrecked on these savage rocks. 288 00:24:00,940 --> 00:24:07,259 But today Mistaken Point has a completely different reputation. 289 00:24:07,260 --> 00:24:09,259 Today it is recognized as one of 290 00:24:09,260 --> 00:24:14,419 the most important fossil-bearing sites in all the world. 291 00:24:14,420 --> 00:24:18,299 For here you can see fossils 292 00:24:18,300 --> 00:24:23,380 of the very first animals that evolved on this planet. 293 00:24:37,700 --> 00:24:42,660 The fossils in these rocks are both wonderful and bizarre. 294 00:24:46,660 --> 00:24:48,499 When the sun is low in the sky, 295 00:24:48,500 --> 00:24:52,460 the slanting light shows up their structure in great detail. 296 00:24:56,060 --> 00:24:58,259 Organisms were no longer 297 00:24:58,260 --> 00:25:02,299 just clumps of undifferentiated cells, like sponges. 298 00:25:02,300 --> 00:25:06,579 They were organized into defined shapes. 299 00:25:06,580 --> 00:25:10,819 And among them are some that look exactly like Charnia 300 00:25:10,820 --> 00:25:14,620 that had been first recognized in Charnwood Forest. 301 00:25:17,100 --> 00:25:20,819 Here, there are not only hundreds of examples of Charnia, 302 00:25:20,820 --> 00:25:24,099 but a whole community of other strange creatures. 303 00:25:24,100 --> 00:25:29,179 Everywhere you look there are complex markings and indentations 304 00:25:29,180 --> 00:25:30,699 of one kind or another - 305 00:25:30,700 --> 00:25:34,899 it's almost as though children have been playing in wet sand. 306 00:25:34,900 --> 00:25:39,139 It's like walking through a carpet of ancient creatures. 307 00:25:39,140 --> 00:25:44,099 It's difficult to imagine that 565 million years ago 308 00:25:44,100 --> 00:25:47,059 this was the bottom of the ocean 309 00:25:47,060 --> 00:25:51,220 and these were some of the first animals to live on this planet. 310 00:26:06,220 --> 00:26:08,739 Here at Mistaken Point, 311 00:26:08,740 --> 00:26:12,620 exceptional conditions have preserved these delicate life forms. 312 00:26:18,020 --> 00:26:21,019 Each one of these layers of rock 313 00:26:21,020 --> 00:26:25,380 was once mud lying at the bottom of an ocean. 314 00:26:27,260 --> 00:26:30,899 An ocean so deep it was very cold, 315 00:26:30,900 --> 00:26:32,979 and very poor in oxygen, 316 00:26:32,980 --> 00:26:38,019 so any organism that died here took a very long time to decay. 317 00:26:38,020 --> 00:26:41,419 But those that did have been preserved 318 00:26:41,420 --> 00:26:45,219 with an astonishing degree of perfection. 319 00:26:45,220 --> 00:26:47,940 What makes this place so different? 320 00:26:52,100 --> 00:26:56,459 There was a volcano rising from the sea floor close by, 321 00:26:56,460 --> 00:26:59,780 and it spewed out millions of tons of ash. 322 00:27:10,740 --> 00:27:12,779 The ash sank to the bottom, 323 00:27:12,780 --> 00:27:16,820 blanketing everything like a sub-marine Pompeii. 324 00:27:18,340 --> 00:27:23,859 Over millions of years, the ash itself was buried by muddy sediments 325 00:27:23,860 --> 00:27:26,619 and then all was turned into rock. 326 00:27:26,620 --> 00:27:29,819 And then, over hundreds of millions of years, 327 00:27:29,820 --> 00:27:33,299 mountain-building forces thrust the whole sea-floor upwards 328 00:27:33,300 --> 00:27:36,500 to its present position on the coast of Canada. 329 00:27:39,420 --> 00:27:44,260 Dr Guy Narbonne is a world expert on the fossils of Mistaken Point. 330 00:27:46,460 --> 00:27:49,819 What you can see on this surface 331 00:27:49,820 --> 00:27:54,099 is the Grey is the muddy sea bottom 332 00:27:54,100 --> 00:27:57,259 and this is where the creatures all lived. 333 00:27:57,260 --> 00:28:03,179 And they were knocked down and covered by a bed of volcanic ash. 334 00:28:03,180 --> 00:28:07,619 And you can see it here and all of this pink and white 335 00:28:07,620 --> 00:28:10,539 speckled stuff is volcanic ash. 336 00:28:10,540 --> 00:28:14,179 The volcanic ash cast every part of them, 337 00:28:14,180 --> 00:28:17,939 like putting plaster around your arm if you break it, 338 00:28:17,940 --> 00:28:22,259 and that led to a perfect preservation 339 00:28:22,260 --> 00:28:24,780 of every detail of the outside. 340 00:28:26,820 --> 00:28:30,379 Radioactivity in this light-colored ash layer 341 00:28:30,380 --> 00:28:34,419 allows Guy Narbonne to date precisely the eruptions, 342 00:28:34,420 --> 00:28:37,059 and therefore the fossils. 343 00:28:37,060 --> 00:28:41,659 Some are as old as 579 million years. 344 00:28:41,660 --> 00:28:46,019 Here we can see one of the best of the fossils on the surface. 345 00:28:46,020 --> 00:28:51,979 It consists of disks, and they all have these pustules 346 00:28:51,980 --> 00:28:56,379 on them and that's why we rather affectionately call them pizza disks. 347 00:28:56,380 --> 00:29:00,179 And they were very simple in form, 348 00:29:00,180 --> 00:29:05,100 but the first truly large creatures in Earth evolution. 349 00:29:07,460 --> 00:29:11,540 The pizza discs are only one of the species found here. 350 00:29:14,620 --> 00:29:19,940 Most are fern-like fronds, like this enormous species of Charnia. 351 00:29:22,660 --> 00:29:25,059 This is a two-meter-long frond. 352 00:29:25,060 --> 00:29:28,099 Astounding! And this is not the biggest. 353 00:29:28,100 --> 00:29:30,780 We have about 200 specimens of this here. 354 00:29:32,980 --> 00:29:37,060 The frond of Charnia found in Charnwood was isolated. 355 00:29:38,660 --> 00:29:45,059 But here at Mistaken Point, a whole community of organisms has been preserved together... 356 00:29:45,060 --> 00:29:49,459 and that could give us new information. 357 00:29:49,460 --> 00:29:54,099 You're calling this an animal but is it justified to call it an animal? 358 00:29:54,100 --> 00:29:55,979 Well... It's rather plant-like. 359 00:29:55,980 --> 00:29:59,259 Well, "What is it?" is a big question. 360 00:29:59,260 --> 00:30:01,859 We know for a fact it can't be a plant 361 00:30:01,860 --> 00:30:04,939 because we're in water thousands of meters deep, 362 00:30:04,940 --> 00:30:08,019 there wouldn't have been enough light to read a newspaper. 363 00:30:08,020 --> 00:30:12,299 We're several orders of magnitude too little light for photosynthesis. 364 00:30:12,300 --> 00:30:15,739 OK, so it's not photosynthesizing because it's too deep 365 00:30:15,740 --> 00:30:18,659 and therefore it's not a plant. What's it living on? 366 00:30:18,660 --> 00:30:25,179 What we believe they're living on is dissolved carbon and other nutrients in the deep oceans. 367 00:30:25,180 --> 00:30:30,779 So it's absorbing these nutrients through its entire body. 368 00:30:30,780 --> 00:30:36,179 Very thin. Probably not much thicker than your thumbnail. 369 00:30:36,180 --> 00:30:38,460 Very primitive. 370 00:30:40,700 --> 00:30:45,179 These organisms were very simple animals. 371 00:30:45,180 --> 00:30:50,739 Beyond the reach of light, they had to survive by absorbing chemical sustenance. 372 00:30:50,740 --> 00:30:55,619 But most animals we know today are able to move about. 373 00:30:55,620 --> 00:30:59,819 Even sponges and corals have swimming larvae. 374 00:30:59,820 --> 00:31:02,700 But there's no evidence of that here. 375 00:31:04,460 --> 00:31:08,139 The creatures were all immobile. 376 00:31:08,140 --> 00:31:09,979 Nothing could move. 377 00:31:09,980 --> 00:31:12,179 Nothing had a mouth, 378 00:31:12,180 --> 00:31:14,700 nothing had muscles. 379 00:31:16,220 --> 00:31:18,739 Probably none of them had color, 380 00:31:18,740 --> 00:31:22,820 probably an eerie whiteish color to everything. 381 00:31:24,860 --> 00:31:30,339 These are the oldest large multi-cellular creatures on Earth, 382 00:31:30,340 --> 00:31:33,980 the oldest things that might be called proto-animals. 383 00:31:35,500 --> 00:31:39,579 This is not like anything that exists on earth today. 384 00:31:39,580 --> 00:31:42,899 Even though they're not directly related to us, 385 00:31:42,900 --> 00:31:48,620 like some distant relative, they provide us with a view of our own beginnings. 386 00:31:52,220 --> 00:31:56,779 One of the most peculiar things about these wonderful proto-animals 387 00:31:56,780 --> 00:31:59,740 is the way they constructed their bodies. 388 00:32:01,660 --> 00:32:06,580 Unlike modern creatures, they had a very simple pattern of branching. 389 00:32:11,420 --> 00:32:15,579 Despite their size, these are still very simple animals. 390 00:32:15,580 --> 00:32:19,659 They can be put together with just six to eight genetic commands, 391 00:32:19,660 --> 00:32:26,819 as against some 25,000 such commands that were needed to construct a mammal like me. 392 00:32:26,820 --> 00:32:29,339 You can see this if you look at them in detail. 393 00:32:29,340 --> 00:32:33,139 You see that they are made up of a series of very small modules 394 00:32:33,140 --> 00:32:36,940 which are attached to one another in a number of different ways. 395 00:32:38,620 --> 00:32:45,060 Their modular or fractal way of building their bodies is one of Guy Narbonne's main areas of research. 396 00:32:47,380 --> 00:32:51,300 His study is centered on one particular species. 397 00:32:52,860 --> 00:32:54,379 This is Fractofusus. 398 00:32:54,380 --> 00:32:57,339 It's the most common fossil in the Mistaken Point assemblage. 399 00:32:57,340 --> 00:32:59,899 We have literally thousands of specimens. 400 00:32:59,900 --> 00:33:02,939 And it would have lain on the sea bottom like you see there. 401 00:33:02,940 --> 00:33:06,819 A spindle-shaped mass, very thin. 402 00:33:06,820 --> 00:33:09,939 It consists of these elements. 403 00:33:09,940 --> 00:33:12,019 And there are 20 of them on either side. 404 00:33:12,020 --> 00:33:14,739 And if you look at an individual element, 405 00:33:14,740 --> 00:33:17,059 it's remarkably finely-branched. 406 00:33:17,060 --> 00:33:19,940 It's a style we called fractal or self-similar. 407 00:33:21,460 --> 00:33:25,579 These fractal organisms grew by repetitive branching, 408 00:33:25,580 --> 00:33:29,139 with each branch exactly the same as its predecessor 409 00:33:29,140 --> 00:33:31,500 from the microscopic level upwards. 410 00:33:34,060 --> 00:33:38,740 It was a simple, yet extremely, effective way of building a body. 411 00:33:46,020 --> 00:33:51,619 Such finely-divided branches gave the organism a huge surface area, 412 00:33:51,620 --> 00:33:56,780 and this allowed them to absorb nutrients directly without mouths and without guts. 413 00:33:59,420 --> 00:34:03,460 This simple fractal body plan proved very successful. 414 00:34:04,980 --> 00:34:10,380 So animals using it grew large for the first time in the history of life on Earth. 415 00:34:14,460 --> 00:34:21,019 Fractal design was perfect for getting these earliest creatures off and running 416 00:34:21,020 --> 00:34:23,099 and its easy to see why. 417 00:34:23,100 --> 00:34:27,459 It takes a minimum of genetic programming in order to make one. 418 00:34:27,460 --> 00:34:30,619 You could probably do it with six or eight codes in your PC 419 00:34:30,620 --> 00:34:34,019 to make something that was fractally branching. 420 00:34:34,020 --> 00:34:38,819 And then combining them to make up larger elements is literally child's play, 421 00:34:38,820 --> 00:34:44,860 like a toddler might take Lego blocks and put them all together in order to make up a larger structure. 422 00:34:48,940 --> 00:34:56,219 The fossils of Mistaken Point provide a detailed record of fractal animals. 423 00:34:56,220 --> 00:35:01,340 But the absence of anything like them in more recent rocks is very significant. 424 00:35:03,860 --> 00:35:09,020 Just a few million years after they first evolved, they vanished. 425 00:35:10,540 --> 00:35:12,899 They have no living descendants. 426 00:35:12,900 --> 00:35:15,580 They were an evolutionary dead end. 427 00:35:17,100 --> 00:35:18,779 And the reason? 428 00:35:18,780 --> 00:35:22,580 The very simplicity of their fractal way of growing. 429 00:35:24,100 --> 00:35:31,419 They utterly dominate about the first 20 million years of the evolution of complex multi-cellular proto-animals. 430 00:35:31,420 --> 00:35:35,619 However, this fast start was also their demise. 431 00:35:35,620 --> 00:35:39,419 Because they were incapable of evolving things like 432 00:35:39,420 --> 00:35:44,420 guts and brains and muscles and teeth that later animals did. 433 00:35:47,220 --> 00:35:50,539 If animals were to acquire these things, 434 00:35:50,540 --> 00:35:54,939 they would have to build their bodies in a completely different way. 435 00:35:54,940 --> 00:35:59,740 And eventually, animals appeared that did exactly that. 436 00:36:01,900 --> 00:36:06,419 To see them, I'm traveling south from Newfoundland across the equator 437 00:36:06,420 --> 00:36:08,180 to South Australia. 438 00:36:14,020 --> 00:36:16,620 The Ediacara Hills. 439 00:36:18,860 --> 00:36:26,859 Here lie animals whose body plans are fundamentally the same as those of almost all animals alive today... 440 00:36:26,860 --> 00:36:28,540 including us. 441 00:36:31,100 --> 00:36:37,220 The creatures that are preserved here lived just after fractal animals began to die out. 442 00:36:43,020 --> 00:36:50,140 And about 550 million years ago, their differently-organized bodies gave them something quite new... 443 00:36:53,620 --> 00:36:55,140 ...mobility. 444 00:36:57,500 --> 00:37:02,619 But how and why did animals first begin to move? 445 00:37:02,620 --> 00:37:07,339 Scientists are beginning to find answers to those fascinating questions. 446 00:37:07,340 --> 00:37:12,340 And much of the detail comes from these extraordinary fossils behind me. 447 00:37:16,580 --> 00:37:21,899 A team of scientists, led by paleontologist Dr Jim Gehling 448 00:37:21,900 --> 00:37:24,580 is uncovering the evidence in great detail. 449 00:37:26,820 --> 00:37:29,179 When you have these beds covered in red clay 450 00:37:29,180 --> 00:37:33,179 you have a good chance of the beds having well-preserved fossils. 451 00:37:33,180 --> 00:37:36,100 This is the original sea floor. 452 00:37:38,180 --> 00:37:43,459 And this sea-floor was very different from that in the deep waters of Mistaken Point. 453 00:37:43,460 --> 00:37:45,659 This was once a shallow reef. 454 00:37:45,660 --> 00:37:48,420 It is 550 million years old. 455 00:37:50,260 --> 00:37:54,659 The surface of the ocean floor was covered with organic ooze. 456 00:37:54,660 --> 00:37:57,819 It may have even been green or orange. We don't know the color. 457 00:37:57,820 --> 00:38:04,859 But there was a lot of organic material made up by bacteria and all sorts of microorganisms. 458 00:38:04,860 --> 00:38:11,780 But sitting in and amongst that garden of slime, we would have seen these strange creatures. 459 00:38:14,860 --> 00:38:18,259 Jim Gehling's team is working to decipher the fossils. 460 00:38:18,260 --> 00:38:22,700 But it is not easy because these creatures still lacked any hard parts to their bodies. 461 00:38:26,780 --> 00:38:30,779 If I was working on dinosaurs, I'd go to a spot, 462 00:38:30,780 --> 00:38:36,059 find the bones and carefully dig them up, take them back into the lab, reconstruct the dinosaur. 463 00:38:36,060 --> 00:38:41,939 But I'm not dealing with bones. I'm dealing with soft-bodied creatures. 464 00:38:41,940 --> 00:38:47,580 All you've got are imprints of squishy things living flat on the seafloor. 465 00:38:49,100 --> 00:38:53,459 Despite the challenges, Jim has discovered compelling evidence here 466 00:38:53,460 --> 00:38:56,620 that these animals had begun to move. 467 00:38:59,500 --> 00:39:03,579 On this fossil bed, we find something very interesting. 468 00:39:03,580 --> 00:39:07,859 It's a series of faint, but very definite circles. 469 00:39:07,860 --> 00:39:12,459 They are almost identical in size and they overlap quite often. 470 00:39:12,460 --> 00:39:16,499 And then when you go to the end of the series of discs, 471 00:39:16,500 --> 00:39:22,859 you find a hollow with the imprint of a very distinct fossil, 472 00:39:22,860 --> 00:39:24,420 that of Dickinsonia. 473 00:39:26,380 --> 00:39:29,899 Dickinsonia was a cushion-like creature 474 00:39:29,900 --> 00:39:32,419 that lay flat on the seafloor. 475 00:39:32,420 --> 00:39:37,300 It ranged from the size of a penny to that of a bath mat. 476 00:39:40,660 --> 00:39:44,659 These imprints represent something very important. 477 00:39:44,660 --> 00:39:46,379 They are the first evidence 478 00:39:46,380 --> 00:39:49,900 of a kind of mobility of animals on the seafloor. 479 00:39:51,900 --> 00:39:57,899 The first animal movements were undoubtedly slow, but perhaps even too slow to notice. 480 00:39:57,900 --> 00:40:02,180 To see them in action, you have to speed them up. 481 00:40:05,820 --> 00:40:09,499 Dickinsonia crept from one feeding place to the next, 482 00:40:09,500 --> 00:40:14,459 absorbing the organic matter beneath it and then moving on once again. 483 00:40:14,460 --> 00:40:21,180 Perhaps it moved with the help of hundreds of tiny tubular feet, as starfish do today. 484 00:40:25,580 --> 00:40:33,579 The excavations at Ediacara reveal that Dickinsonia wasn't the only mobile creature around. 485 00:40:33,580 --> 00:40:38,859 Animals everywhere were on the move, actively seeking food. 486 00:40:38,860 --> 00:40:46,619 This shape here is a resting place of a slug-like animal called Kimberella. 487 00:40:46,620 --> 00:40:51,859 And these here, marks, are showing how it fed. 488 00:40:51,860 --> 00:40:53,459 It had a proboscis, a snout, 489 00:40:53,460 --> 00:41:00,739 and it fed by sifting through the mud, making these scratch marks. 490 00:41:00,740 --> 00:41:04,659 But it tells us more than how this animal fed. 491 00:41:04,660 --> 00:41:08,979 It also tells us how it moved because if you look back this way, 492 00:41:08,980 --> 00:41:10,779 this is where is started feeding 493 00:41:10,780 --> 00:41:15,099 and then it moved along here with more feeding marks and grooves, 494 00:41:15,100 --> 00:41:18,019 and then it settled down here 495 00:41:18,020 --> 00:41:20,539 into the mud where its final resting place was. 496 00:41:20,540 --> 00:41:24,499 So this shows that the animal not only fed like that, 497 00:41:24,500 --> 00:41:26,740 it actually moved like that. 498 00:41:28,500 --> 00:41:33,699 Kimberella was a very early ancestor of today's mollusks. 499 00:41:33,700 --> 00:41:36,259 It probably had a single muscular foot, 500 00:41:36,260 --> 00:41:38,739 just as snails and slugs have today 501 00:41:38,740 --> 00:41:42,579 with which it pulled itself along the sea bottom. 502 00:41:42,580 --> 00:41:46,299 Our speeded-up view of the Ediacaran seafloor 503 00:41:46,300 --> 00:41:50,180 gives an idea of what a busy place the oceans had now become. 504 00:42:02,340 --> 00:42:06,859 Whether that movement is by creeping or crawling over the seafloor, 505 00:42:06,860 --> 00:42:09,139 it doesn't matter because that animal 506 00:42:09,140 --> 00:42:13,899 has advantages over an animal that is fixed to the seafloor. 507 00:42:13,900 --> 00:42:16,019 It can move away from danger. 508 00:42:16,020 --> 00:42:19,539 It can move towards richer sources of food. 509 00:42:19,540 --> 00:42:25,059 It can move away from places which are over-colonized by its neighbors. 510 00:42:25,060 --> 00:42:29,420 That gives it an enormous advantage in the history of life. 511 00:42:39,300 --> 00:42:46,300 This new mobility was only made possible by a major change in the layout of animals' bodies. 512 00:42:47,820 --> 00:42:52,939 When we get to Ediacara, we still have some of those beautiful fractal-like forms 513 00:42:52,940 --> 00:43:00,819 that you see at Mistaken Point but in the Ediacara Hills we see something very different 514 00:43:00,820 --> 00:43:02,779 and that is, for the first time, 515 00:43:02,780 --> 00:43:09,660 you see a blueprint for all animals from then on, including ourselves. 516 00:43:11,180 --> 00:43:16,979 'The modern animal body plan is called bilateral symmetry.' 517 00:43:16,980 --> 00:43:19,140 What we see here is Spriggina. 518 00:43:22,980 --> 00:43:24,820 Let's make a cast of the fossil. 519 00:43:26,420 --> 00:43:31,579 Spriggina represents the first ever animal 520 00:43:31,580 --> 00:43:35,099 which had clear bilateral symmetry. 521 00:43:35,100 --> 00:43:39,579 It had a body with a head at one end, a tail at the other. 522 00:43:39,580 --> 00:43:43,780 And almost identical halves, if you split it down the middle. 523 00:43:46,700 --> 00:43:50,059 We see these together with other creatures 524 00:43:50,060 --> 00:43:53,659 which have this kind of body form. 525 00:43:53,660 --> 00:43:57,859 Spriggina is just one of countless kinds of fossils 526 00:43:57,860 --> 00:44:01,460 in the Ediacara Hills that had developed in this way. 527 00:44:02,980 --> 00:44:08,380 It had a head and a tail, and so it moved in a particular direction. 528 00:44:12,100 --> 00:44:17,499 It's quite likely that they had sensory organs concentrated in the head. 529 00:44:17,500 --> 00:44:21,779 Now why does my nose occur near my mouth? 530 00:44:21,780 --> 00:44:25,899 It's a very good reason. I want to smell the food before I ingest it. 531 00:44:25,900 --> 00:44:28,819 Why are my eyes above my mouth? 532 00:44:28,820 --> 00:44:30,579 So I can see what I'm eating. 533 00:44:30,580 --> 00:44:37,819 This head demonstrates that sensory capacity had evolved. 534 00:44:37,820 --> 00:44:42,859 It was able to sense where food was likely to be on the seafloor. 535 00:44:42,860 --> 00:44:48,580 And, therefore, clearly had a mechanism for actually moving towards that food. 536 00:44:50,660 --> 00:44:55,939 Bilateral animals like Spriggina had another advantage. 537 00:44:55,940 --> 00:44:59,980 Between the head and the tail, there are numerous segments. 538 00:45:02,100 --> 00:45:08,059 So these animals could increase in size by simply adding more segments. 539 00:45:08,060 --> 00:45:13,059 What is more, each segment could do a particular job. 540 00:45:13,060 --> 00:45:14,339 Once you start to move, 541 00:45:14,340 --> 00:45:17,339 you develop a front end and that becomes your head. 542 00:45:17,340 --> 00:45:20,459 And you also, by definition, have a back end. 543 00:45:20,460 --> 00:45:24,419 And in between, segments on which you can add appendages. 544 00:45:24,420 --> 00:45:27,979 On that basic pattern, you can add further features. 545 00:45:27,980 --> 00:45:32,259 On the front end, that's where you need sense organs, eyes, feelers. 546 00:45:32,260 --> 00:45:35,499 On the appendages, you can modify them to be hooks and claws 547 00:45:35,500 --> 00:45:37,419 that would help you to catch things. 548 00:45:37,420 --> 00:45:43,699 And at the back end, there will be a pore from which you excrete the waste products. 549 00:45:43,700 --> 00:45:49,740 And that is the basic body plan of almost all the animals that are alive on Earth today. 550 00:45:52,060 --> 00:45:58,659 It had taken 3,000 million years for multi-celled organisms to appear for the first time. 551 00:45:58,660 --> 00:46:04,539 But now, less than 100 million years later, an evolutionary blink of an eye, 552 00:46:04,540 --> 00:46:11,139 animals had appeared that had the same basic body plan as most that live today. 553 00:46:11,140 --> 00:46:14,339 They had heads and tails and segmented bodies. 554 00:46:14,340 --> 00:46:17,300 And they were able to move to find food. 555 00:46:18,820 --> 00:46:22,940 How was it that animals had suddenly become so complex? 556 00:46:25,340 --> 00:46:30,900 The Ediacara Hills may hold the evidence for an answer to that question. 557 00:46:35,780 --> 00:46:39,379 Living organisms don't live forever. 558 00:46:39,380 --> 00:46:47,380 If a species is to survive it has to reproduce and the first simple animals did that very simply, 559 00:46:47,420 --> 00:46:49,779 by straightforwardly dividing. 560 00:46:49,780 --> 00:46:57,539 But if a species is to survive it also has to have the ability to change with a changing environment. 561 00:46:57,540 --> 00:47:03,219 And to do that involves reproducing in a rather different way. 562 00:47:03,220 --> 00:47:10,340 Evidence of how that happened can also be seen is these very ancient Australian rocks. 563 00:47:21,940 --> 00:47:26,939 In 2007, paleontologist Dr Mary Droser 564 00:47:26,940 --> 00:47:31,339 discovered in these 550-million-year-old deposits 565 00:47:31,340 --> 00:47:35,660 evidence that animals had started to reproduce sexually. 566 00:47:38,260 --> 00:47:42,620 The animal concerned is called Funisia. 567 00:47:45,620 --> 00:47:50,179 If Droser's theory is right, this wormlike creature produced offspring 568 00:47:50,180 --> 00:47:54,739 by exchanging genetic material with other individuals. 569 00:47:54,740 --> 00:47:57,859 This gene-swapping, or sex, 570 00:47:57,860 --> 00:48:03,980 shuffles the genetic pack, greatly accelerating variation and therefore evolution. 571 00:48:08,580 --> 00:48:12,099 Sexual reproduction is absolutely one of the most fundamental steps 572 00:48:12,100 --> 00:48:13,419 in the history of life. 573 00:48:13,420 --> 00:48:15,899 It is why we have the diversity that we have. 574 00:48:15,900 --> 00:48:17,539 It's the birds and the bees. 575 00:48:17,540 --> 00:48:21,979 As far as we know, this is the first evidence of animals' sexual reproduction, 576 00:48:21,980 --> 00:48:25,619 and we're not catching the animal in the act of it, 577 00:48:25,620 --> 00:48:30,819 we're looking at the product of what we conclude was sexual reproduction. 578 00:48:30,820 --> 00:48:34,539 This fossil is key to Mary Droser's argument. 579 00:48:34,540 --> 00:48:38,540 The small circles show where the animals were anchored to the ground. 580 00:48:40,060 --> 00:48:44,739 You can see that these attachment structures are basically all the same size. 581 00:48:44,740 --> 00:48:48,019 They're all about a couple of millimeters in diameter. 582 00:48:48,020 --> 00:48:52,459 And you could go to another bed, and all the Funisia are half a centimeter in diameter. 583 00:48:52,460 --> 00:48:55,659 So the same size are all occurring together. 584 00:48:55,660 --> 00:49:01,259 This uniformity of size in a particular place is, Mary Droser believes, 585 00:49:01,260 --> 00:49:05,859 strong evidence that a new way of reproducing had arrived. 586 00:49:05,860 --> 00:49:08,059 We link this to sexual reproduction 587 00:49:08,060 --> 00:49:12,419 because if you look in modern environments, when you have this kind of size groupings, 588 00:49:12,420 --> 00:49:18,180 that is 99.9% of the time a product of sexual reproduction. 589 00:49:19,540 --> 00:49:26,300 To understand why, I'm traveling 2,000 miles northeast of Ediacara to the Great Barrier Reef. 590 00:49:30,420 --> 00:49:37,179 Here, there are modern creatures that reproduce in the way that Funisia is thought to have done. 591 00:49:37,180 --> 00:49:39,420 They're corals. 592 00:49:48,260 --> 00:49:52,899 Corals, like Funisia, are anchored to the seabed. 593 00:49:52,900 --> 00:49:57,500 They feed by filtering food from the water. 594 00:50:00,060 --> 00:50:05,700 And the way they breed creates one of nature's greatest annual spectacles. 595 00:50:08,100 --> 00:50:13,019 Once a year, there's an important event among the corals. 596 00:50:13,020 --> 00:50:15,099 We're not sure how it's coordinated. 597 00:50:15,100 --> 00:50:17,659 It probably has something to do with the moon. 598 00:50:17,660 --> 00:50:23,540 But it gives us a hint as to how sexual reproduction might have first appeared. 599 00:50:31,380 --> 00:50:34,579 At exactly the same time, 600 00:50:34,580 --> 00:50:40,220 the corals release countless millions of sperm and eggs all at once. 601 00:50:50,060 --> 00:50:54,059 The event is precisely timed to maximize the chances 602 00:50:54,060 --> 00:50:55,820 of fertilization. 603 00:50:57,340 --> 00:51:01,140 Millions of offspring are simultaneously conceived. 604 00:51:06,780 --> 00:51:10,979 So, as the coral grows, the individuals that make up 605 00:51:10,980 --> 00:51:16,459 the colonies are all of exactly the same age and size, 606 00:51:16,460 --> 00:51:18,660 just like Funisia. 607 00:51:23,340 --> 00:51:27,819 It's unlikely that Funisia was the first animal to reproduce sexually. 608 00:51:27,820 --> 00:51:34,939 But its discovery suggests that many other animals are also reproducing by mixing their genes. 609 00:51:34,940 --> 00:51:40,740 And that might explain how complex animals evolved so quickly. 610 00:51:45,420 --> 00:51:49,899 The arrival of sexual reproduction speeded evolution. 611 00:51:49,900 --> 00:51:54,819 Here was a mechanism that produced greater genetic variation more quickly. 612 00:51:54,820 --> 00:52:00,860 So, over many generations, species were able to adapt to their changing environments. 613 00:52:02,380 --> 00:52:08,900 550 million years ago, animal life was on the verge of a major advance. 614 00:52:10,460 --> 00:52:17,019 In an environment where animals were becoming more mobile, they would have to adapt fast. 615 00:52:17,020 --> 00:52:20,619 Movement requires a lot of energy. 616 00:52:20,620 --> 00:52:23,899 Simply absorbing nutrients through the surface of the body 617 00:52:23,900 --> 00:52:27,420 as Dickinsonia did was much too slow a process. 618 00:52:29,500 --> 00:52:33,659 Mobile animals would need to consume huge quantities of food. 619 00:52:33,660 --> 00:52:38,300 And they would do that by evolving the very first stomachs, mouths and teeth. 620 00:52:41,260 --> 00:52:45,420 You can see how they might have done so in Switzerland... 621 00:52:49,340 --> 00:52:54,660 ...where a new kind of technology provides a window into the past. 622 00:53:01,900 --> 00:53:07,700 This stadium-sized building houses one of the world's most powerful microscopes. 623 00:53:12,740 --> 00:53:15,780 It's called the synchrotron. 624 00:53:20,660 --> 00:53:26,380 Professor Philip Donoghue is preparing the tiniest of fossils for the synchrotron. 625 00:53:28,700 --> 00:53:34,379 These minuscule balls were excavated from a quarry in South China. 626 00:53:34,380 --> 00:53:39,980 Each and every one of them is the fossilized embryo of an ancient creature. 627 00:53:44,140 --> 00:53:46,699 If we really want to understand these fossils, 628 00:53:46,700 --> 00:53:49,379 what we need to do is not just to look at the surface 629 00:53:49,380 --> 00:53:51,659 which we can do with an electron microscope. 630 00:53:51,660 --> 00:53:52,819 We need to look inside. 631 00:53:52,820 --> 00:53:58,019 We have to use some form of X-ray tomography, a bit like CAT scanners in hospitals. 632 00:53:58,020 --> 00:54:04,459 But we have to use one that allows us to look at the very tiniest details down to a thousandth of a millimeter. 633 00:54:04,460 --> 00:54:07,579 The synchrotron is the only X-ray type machine that provides 634 00:54:07,580 --> 00:54:13,060 the kinds of resolution that we need to see all the tiny details within the fossilized embryos. 635 00:54:14,580 --> 00:54:17,100 KLAXON SOUNDS 636 00:54:18,500 --> 00:54:22,939 It was astonishing, I mean it was a real eureka moment 637 00:54:22,940 --> 00:54:27,339 that you could get to the very finest levels of fossilization, 638 00:54:27,340 --> 00:54:31,580 the very finest detail that the fossil record could ever give up using this technology. 639 00:54:40,220 --> 00:54:47,620 Powerful generators fire high-energy electrons around a circular tube at close to the speed of light. 640 00:54:51,500 --> 00:54:59,339 After one million orbits, the electrons emit X-rays so powerful, they can penetrate solid rock 641 00:54:59,340 --> 00:55:01,540 or these tiny fossils. 642 00:55:03,460 --> 00:55:06,459 Donoghue uses data from the synchrotron 643 00:55:06,460 --> 00:55:09,900 to build a three-dimensional picture of the fossils. 644 00:55:11,420 --> 00:55:16,899 We know it's a fossil embryo because it's surrounded by a preserved egg sac. 645 00:55:16,900 --> 00:55:21,500 And using tomography we can see inside to the developing animal. 646 00:55:26,780 --> 00:55:31,820 This fossil is the embryo of a tiny marine worm called Markuelia. 647 00:55:33,340 --> 00:55:37,980 It lived just twenty million years after the animals of Ediacara. 648 00:55:44,740 --> 00:55:49,659 Using his 3D model, Donoghue is able to see inside it 649 00:55:49,660 --> 00:55:53,180 and there he found evidence of something new. 650 00:55:55,060 --> 00:55:59,459 These fossils provide the first clear evidence for a gut within animals. 651 00:55:59,460 --> 00:56:04,659 We can clearly see that there's a mouth right at one end 652 00:56:04,660 --> 00:56:07,579 surrounded by rings of teeth that extend inside the mouth. 653 00:56:07,580 --> 00:56:12,140 And then there's a gut that extends all the way through to an anus at the other end. 654 00:56:13,660 --> 00:56:21,300 Internal digestion enabled Markuelia to extract energy from its food in a very efficient way. 655 00:56:24,580 --> 00:56:30,419 And the fact that it had teeth suggests that it had a new diet - 656 00:56:30,420 --> 00:56:32,260 other animals. 657 00:56:34,700 --> 00:56:39,539 The fact that it's got rings of teeth arranged by its mouth, that it would have averted out 658 00:56:39,540 --> 00:56:44,380 or it would have ejected out of its mouth to grasp prey items, tells us that this thing was a predator. 659 00:56:48,820 --> 00:56:52,139 For the first time, there were hunters in the oceans. 660 00:56:52,140 --> 00:56:57,100 And that had enormous evolutionary implications. 661 00:57:05,700 --> 00:57:12,700 There was about to be an explosion of life that would lay the foundations for modern animals. 662 00:57:18,020 --> 00:57:20,339 In another wave of evolution, 663 00:57:20,340 --> 00:57:24,819 the animal basic body plan became more and more elaborate. 664 00:57:24,820 --> 00:57:28,459 Fearsome predators appeared in the seas, 665 00:57:28,460 --> 00:57:35,020 great monsters on the land and animals became masters of the Earth. 666 00:57:37,580 --> 00:57:43,699 Next time I continue my journey in the Rocky Mountains of Canada, 667 00:57:43,700 --> 00:57:46,459 the deserts of North Africa 668 00:57:46,460 --> 00:57:51,179 and the tropical rainforests of Australia. 669 00:57:51,180 --> 00:57:57,899 I will discover how and why animals evolved skeletons and shells. 670 00:57:57,900 --> 00:58:01,220 How they developed true, picture-forming eyes. 671 00:58:02,340 --> 00:58:05,579 How others went to extraordinary lengths 672 00:58:05,580 --> 00:58:09,419 to protect themselves from attack. 673 00:58:09,420 --> 00:58:16,060 And I shall discover the first animals that moved out of the sea to conquer the land and the air.