1 00:00:17,480 --> 00:00:20,340 Across our natural world, 2 00:00:20,340 --> 00:00:23,660 life has taken on countless forms. 3 00:00:27,100 --> 00:00:30,700 Wondrous, strange... 4 00:00:31,780 --> 00:00:34,140 ..and endlessly diverse. 5 00:00:38,500 --> 00:00:41,500 It's easy to imagine that all of this is, like, 6 00:00:41,500 --> 00:00:43,380 somehow preordained... 7 00:00:45,660 --> 00:00:49,540 ..that it's been made, a world of balance and purpose, 8 00:00:49,540 --> 00:00:53,820 but the truth... The truth is much wilder. 9 00:00:53,820 --> 00:00:56,780 This is a world of survivors. 10 00:00:58,820 --> 00:01:01,660 From Earth's earliest moments, 11 00:01:01,660 --> 00:01:04,140 evolution has quietly, 12 00:01:04,140 --> 00:01:05,740 relentlessly, 13 00:01:05,740 --> 00:01:08,220 shaped the story of life. 14 00:01:09,660 --> 00:01:10,780 I can hear it... 15 00:01:12,140 --> 00:01:13,860 And in this series... 16 00:01:13,860 --> 00:01:15,940 It's quite emotional, if I'm honest with you! 17 00:01:15,940 --> 00:01:21,180 ...we'll trace the astonishing evolutionary journeys of five 18 00:01:21,180 --> 00:01:23,820 iconic modern animals. 19 00:01:23,820 --> 00:01:25,380 Look at this! 20 00:01:25,380 --> 00:01:27,460 Truly spectacular! 21 00:01:27,460 --> 00:01:31,540 We'll meet their oddball ancestors from the distant past 22 00:01:31,540 --> 00:01:35,740 and discover how generation, by generation... 23 00:01:35,740 --> 00:01:39,300 Absolutely amazing! 24 00:01:39,300 --> 00:01:42,820 ..they changed, to become the creatures we know today. 25 00:01:45,900 --> 00:01:50,420 From the smallest beginnings come the most extraordinary stories, 26 00:01:50,420 --> 00:01:54,500 stories of survival, of bizarre transformations, 27 00:01:54,500 --> 00:01:57,660 shaping life in the strangest of ways 28 00:01:57,660 --> 00:02:02,500 and, behind it all, the unstoppable force of evolution. 29 00:03:00,020 --> 00:03:05,660 Look at that! They used to say that animals couldn't experience joy. 30 00:03:05,660 --> 00:03:11,540 Come on! That looks like muddy, wet joy to me! 31 00:03:17,700 --> 00:03:18,980 CHRIS LAUGHS 32 00:03:22,020 --> 00:03:26,980 The African savannah elephant has to be one of evolution's most 33 00:03:26,980 --> 00:03:29,540 enchantingly strange creatures. 34 00:03:30,980 --> 00:03:32,260 I mean, look at the trunk. 35 00:03:33,660 --> 00:03:37,780 When they're adult, that measures nearly two metres in length, 36 00:03:37,780 --> 00:03:41,740 and it contains perhaps 90,000 miniature muscles. 37 00:03:44,020 --> 00:03:45,980 And then the tusks. 38 00:03:45,980 --> 00:03:48,820 Those are teeth that never stop growing. 39 00:03:50,140 --> 00:03:52,940 The ears! Look at the ears on this one, 40 00:03:52,940 --> 00:03:55,500 the size of a table cloth, 41 00:03:55,500 --> 00:03:56,940 flapping away. 42 00:04:00,060 --> 00:04:06,260 But their one most obvious defining feature, of course, is their size. 43 00:04:06,260 --> 00:04:07,620 Look at that! 44 00:04:10,380 --> 00:04:14,860 They can regularly reach five, six, seven tonnes. 45 00:04:14,860 --> 00:04:16,860 The very biggest, ten tonnes. 46 00:04:18,060 --> 00:04:19,780 They are colossal. 47 00:04:21,540 --> 00:04:23,500 So, here's a question for you. 48 00:04:23,500 --> 00:04:27,100 How did evolution come up with something as complex, 49 00:04:27,100 --> 00:04:30,700 as beautiful and as enormous as this? 50 00:04:31,860 --> 00:04:34,420 How did the elephant come to be? 51 00:04:39,180 --> 00:04:41,940 Well, to understand the elephant, 52 00:04:41,940 --> 00:04:44,500 the largest land animal alive today... 53 00:04:46,740 --> 00:04:49,660 ..you have to understand evolution itself. 54 00:04:51,860 --> 00:04:55,700 There was no blueprint, no grand design. 55 00:04:57,140 --> 00:05:03,340 Evolution is a process, shaped by powerful, invisible drivers. 56 00:05:06,820 --> 00:05:08,020 Like hunger... 57 00:05:09,020 --> 00:05:10,060 ..conflict... 58 00:05:11,180 --> 00:05:12,220 ..and even... 59 00:05:15,060 --> 00:05:16,460 ..catastrophe. 60 00:05:18,340 --> 00:05:21,140 So where does our story begin? 61 00:05:23,380 --> 00:05:27,980 The answer lies in what these giants are made of. 62 00:05:30,780 --> 00:05:36,020 They may be the world's largest land mammals, they may be beautiful, 63 00:05:36,020 --> 00:05:42,300 but brutally biologically speaking, this is just a giant mass of cells. 64 00:05:42,300 --> 00:05:44,980 Now, in case of the elephant, that's a lot of cells. 65 00:05:44,980 --> 00:05:46,860 It's a quadrillion. 66 00:05:46,860 --> 00:05:50,660 That's a one with 15 zeros after it. 67 00:05:57,580 --> 00:06:03,060 Cells are the fundamental building blocks, not just of elephants, 68 00:06:03,060 --> 00:06:07,140 but of all life today, be it animal... 69 00:06:08,140 --> 00:06:09,540 ..plant, 70 00:06:09,540 --> 00:06:10,660 fungi... 71 00:06:12,180 --> 00:06:13,340 ..or bacteria. 72 00:06:16,380 --> 00:06:18,780 So, where did those cells come from? 73 00:06:20,700 --> 00:06:25,420 Well, each one of this animal's cells has come from other 74 00:06:25,420 --> 00:06:29,540 cells, which have either divided or reproduced. 75 00:06:29,540 --> 00:06:32,380 OK, where did those cells come from? 76 00:06:32,380 --> 00:06:35,020 Well, they come from other cells that divided and reproduced. 77 00:06:35,020 --> 00:06:39,220 In fact, we can trace this chain back over unimaginable 78 00:06:39,220 --> 00:06:45,060 periods of time, through many long-lost extinct species, 79 00:06:45,060 --> 00:06:50,380 until remarkably it converges at a single point, 80 00:06:50,380 --> 00:06:55,180 a single-celled organism that's connected to every living thing, 81 00:06:55,180 --> 00:06:58,500 every branch on the tree of life, 82 00:06:58,500 --> 00:07:03,900 a common ancestor that lived billions of years ago, 83 00:07:03,900 --> 00:07:07,140 the cell that started everything. 84 00:07:09,540 --> 00:07:14,100 Now, when it comes to evolution, you need to take the long view. 85 00:07:15,100 --> 00:07:17,860 I mean the really long view. 86 00:07:19,380 --> 00:07:25,340 The elephant's improbable journey begins before mammals, before 87 00:07:25,340 --> 00:07:31,260 dinosaurs stomped about, before anything even had legs to stomp. 88 00:07:32,580 --> 00:07:35,740 It's a story that starts with a simple truth. 89 00:07:38,900 --> 00:07:42,980 If you want to evolve, you have to survive first. 90 00:07:51,140 --> 00:07:52,620 Violent, 91 00:07:52,620 --> 00:07:54,260 loud... 92 00:07:54,260 --> 00:07:57,220 Frankly, overdramatic. 93 00:07:57,220 --> 00:07:59,620 The young Earth is no paradise... 94 00:08:02,700 --> 00:08:07,580 ..but beneath the waves, life has already taken hold. 95 00:08:12,460 --> 00:08:16,860 Trillions of tiny, primitive cells battle the elements. 96 00:08:19,860 --> 00:08:22,460 Almost all will perish. 97 00:08:28,460 --> 00:08:31,820 But one cell is different. 98 00:08:33,140 --> 00:08:39,660 Within this tiny speck lies the future of all living things. 99 00:08:41,780 --> 00:08:43,700 It's a speck with a name. 100 00:08:45,100 --> 00:08:50,300 Meet LUCA, the ultimate survivor. 101 00:08:50,300 --> 00:08:55,700 The great-great-great times a billion grandparent of you, 102 00:08:55,700 --> 00:09:00,660 the elephant, and every other living thing on Earth. 103 00:09:20,620 --> 00:09:26,220 LUCA stands for Last Universal Common Ancestor. 104 00:09:26,220 --> 00:09:30,420 So, let's just think about this for a moment, because it was this 105 00:09:30,420 --> 00:09:34,500 single-celled organism, floating around in a world entirely 106 00:09:34,500 --> 00:09:41,020 alien to our own, which gave rise to every living thing on our planet. 107 00:09:41,020 --> 00:09:45,180 That's me, that's you, that's all the animals, all the plants, 108 00:09:45,180 --> 00:09:48,740 all the fungi, all the bacteria, everything! 109 00:09:48,740 --> 00:09:51,300 So, LUCA isn't just a clever acronym, 110 00:09:51,300 --> 00:09:53,660 something out of a biology class. 111 00:09:53,660 --> 00:09:59,300 LUCA defines the point where the story of life as we know it 112 00:09:59,300 --> 00:10:00,340 truly began. 113 00:10:06,300 --> 00:10:09,060 There are no fossils of LUCA... 114 00:10:11,220 --> 00:10:14,380 ..but because all living things have DNA 115 00:10:14,380 --> 00:10:19,620 and use the same genetic code, we know there must be a shared origin. 116 00:10:23,340 --> 00:10:24,820 Look at that. 117 00:10:24,820 --> 00:10:28,300 But why did LUCA and its descendants survive... 118 00:10:28,300 --> 00:10:32,460 Ooh! ..when trillions of others vanished? 119 00:10:32,460 --> 00:10:35,020 That's actually starting to burn my hand. 120 00:10:36,340 --> 00:10:40,820 Clues can be found in the Earth's most extreme places. 121 00:10:42,460 --> 00:10:45,660 I want to take my hand out of there. That's how hot it is. 122 00:10:50,140 --> 00:10:54,340 With alkaline water up to 86 degrees Centigrade... 123 00:10:57,540 --> 00:11:01,900 ..these are the sort of hostile conditions LUCA may have endured. 124 00:11:03,700 --> 00:11:05,300 But nevertheless, look. 125 00:11:05,300 --> 00:11:08,340 Life is tolerating it all round here. 126 00:11:14,260 --> 00:11:17,620 I know what you're thinking, this doesn't look like much, 127 00:11:17,620 --> 00:11:22,420 and certainly compared to us, this is pretty simple stuff. 128 00:11:22,420 --> 00:11:24,780 But I've got to tell you, it's not. 129 00:11:24,780 --> 00:11:27,700 The cells in here are amongst the most complex 130 00:11:27,700 --> 00:11:30,380 things in the known universe. 131 00:11:30,380 --> 00:11:34,020 Each one of these cells is generating energy, 132 00:11:34,020 --> 00:11:36,380 distributing that energy, dealing with waste. 133 00:11:36,380 --> 00:11:41,060 It's sensitive to its environment, it's reproducing. 134 00:11:41,060 --> 00:11:44,980 Every one of these cells is more complex than any machine 135 00:11:44,980 --> 00:11:47,100 ever made by any human. 136 00:11:49,260 --> 00:11:54,700 Just like these cells, LUCA was complex, robust, resilient... 137 00:11:56,100 --> 00:11:59,740 ..which may have helped it cling on against the odds. 138 00:12:01,300 --> 00:12:07,260 Now, we know that Luca wasn't the first cell and that it lived amongst 139 00:12:07,260 --> 00:12:11,700 other cells, but what made it special is that it didn't just live, 140 00:12:11,700 --> 00:12:14,740 it thrived, it survived. 141 00:12:14,740 --> 00:12:17,500 That little bubble of chemicals, 142 00:12:17,500 --> 00:12:20,460 formed in chaos billions of years ago. 143 00:12:26,940 --> 00:12:31,220 LUCA was the little cell that could. 144 00:12:36,060 --> 00:12:37,980 Plucky? Yes. 145 00:12:37,980 --> 00:12:40,820 Lucky? Almost certainly... 146 00:12:42,740 --> 00:12:47,060 ..but it also has life's greatest survival trick. 147 00:13:00,940 --> 00:13:03,860 LUCA can copy itself. 148 00:13:05,180 --> 00:13:07,660 Well enough to keep its genetic line going... 149 00:13:09,900 --> 00:13:13,860 ..but not so perfectly that every copy is identical. 150 00:13:16,820 --> 00:13:21,740 With every new generation, tiny errors, mutations, 151 00:13:21,740 --> 00:13:23,180 creep into its DNA. 152 00:13:25,940 --> 00:13:31,820 And yet these so-called mistakes fuel evolution. 153 00:13:34,220 --> 00:13:38,580 The story of our modern, living world has begun. 154 00:13:43,100 --> 00:13:45,700 Now it's time to hit fast forward. 155 00:13:48,580 --> 00:13:51,940 I mean, you can't cover four billion years of evolution without 156 00:13:51,940 --> 00:13:53,500 skipping some chapters. 157 00:13:56,180 --> 00:13:58,340 Generation after generation, 158 00:13:58,340 --> 00:14:02,460 little mistakes lead to entirely new life forms. 159 00:14:04,420 --> 00:14:09,980 Some cells begin to capture the sunlight - the ancestors of plants. 160 00:14:12,580 --> 00:14:17,580 Others would adapt to feed on decay - fungi. 161 00:14:22,820 --> 00:14:28,500 Many stay small and simple - the hidden world of microbes. 162 00:14:33,820 --> 00:14:36,500 But the cells that would give rise to the elephant 163 00:14:36,500 --> 00:14:38,180 take a very different path... 164 00:14:42,020 --> 00:14:45,580 ..three and a half billion years after LUCA... 165 00:14:48,220 --> 00:14:51,540 ..when the Earth is in a deep freeze. 166 00:15:04,820 --> 00:15:09,940 This is a period of intense global cooling. 167 00:15:09,940 --> 00:15:15,580 Ice grips the planet, and food webs are collapsing. 168 00:15:17,980 --> 00:15:21,460 But somewhere in the cold and dark, 169 00:15:21,460 --> 00:15:26,060 one hungry cell is about to change everything. 170 00:15:37,380 --> 00:15:41,980 The need to feed is one of the great driving forces of evolution. 171 00:15:41,980 --> 00:15:45,380 Any creature that can find its food more efficiently is more 172 00:15:45,380 --> 00:15:49,860 likely to survive and pass its genes into the next generation, 173 00:15:49,860 --> 00:15:55,060 as was the case over 600 million years ago 174 00:15:55,060 --> 00:15:59,260 when a single cell was on the verge of a breakthrough, 175 00:15:59,260 --> 00:16:02,180 a breakthrough that would lead to the incredible 176 00:16:02,180 --> 00:16:06,100 diversity of almost all animal life to come. 177 00:16:13,660 --> 00:16:16,780 Meet the ancient ancestor of the elephant... 178 00:16:17,780 --> 00:16:20,820 ..indeed of all animal kind. 179 00:16:28,940 --> 00:16:33,260 Urchoanozoan now has mitochondria for energy... 180 00:16:35,660 --> 00:16:37,580 ..a nucleus for control... 181 00:16:40,900 --> 00:16:43,620 ..and a tail-like flagellum to move. 182 00:16:46,780 --> 00:16:49,300 But one thing hasn't changed... 183 00:16:51,820 --> 00:16:54,500 ..this cell is still tiny... 184 00:16:56,820 --> 00:16:59,780 ..just 100th of a millimetre across. 185 00:17:04,940 --> 00:17:08,260 It's a small cell with a big problem. 186 00:17:10,500 --> 00:17:13,540 Food is brutally scarce. 187 00:17:16,780 --> 00:17:23,100 And that cell's ancient hunger may have set life on a new course. 188 00:17:25,180 --> 00:17:30,260 And you can see how, thanks to a remarkable creature alive today. 189 00:17:35,020 --> 00:17:36,460 You might be wondering, what have 190 00:17:36,460 --> 00:17:39,620 a mass of insects like this got 191 00:17:39,620 --> 00:17:43,420 to do with an ancient single-celled organism? 192 00:17:43,420 --> 00:17:48,220 Well, the twist is that in the quest for food, 193 00:17:48,220 --> 00:17:51,540 they both came up with a similar solution... 194 00:17:53,060 --> 00:17:55,300 ..and it's down to numbers. 195 00:17:57,820 --> 00:18:01,260 You see, single ants are not very good 196 00:18:01,260 --> 00:18:06,020 when it comes to overwhelming prey. 197 00:18:06,020 --> 00:18:09,180 They're simply too small, they don't have the strength. 198 00:18:09,180 --> 00:18:14,220 So, what they've done is turn into a mass killing machine. 199 00:18:16,860 --> 00:18:21,300 Each one of the individuals has become a cog in that machine, 200 00:18:21,300 --> 00:18:24,260 and this means that they're far more efficient 201 00:18:24,260 --> 00:18:29,100 when it comes to handling whatever they're going to eat. 202 00:18:29,100 --> 00:18:31,260 Ow! It's all right. 203 00:18:33,780 --> 00:18:37,820 These ants act as one giant organism... 204 00:18:40,860 --> 00:18:44,980 ..overwhelming their meals with sheer force of numbers... 205 00:18:47,860 --> 00:18:52,180 ..and when they swarm, almost anything is on the menu. 206 00:18:54,260 --> 00:18:57,820 Crickets, caterpillars, or, if they're wounded, 207 00:18:57,820 --> 00:19:04,300 even chickens, goats and pigs and, by the feel of it, even a Packham! 208 00:19:04,300 --> 00:19:09,180 And there's the parallel with those ancient single-celled organisms, 209 00:19:09,180 --> 00:19:14,180 because they were about to adopt a similar technique which would 210 00:19:14,180 --> 00:19:15,620 change the world... 211 00:19:16,660 --> 00:19:18,220 ..forever. 212 00:19:18,220 --> 00:19:20,580 Oh, my goodness! 213 00:19:20,580 --> 00:19:24,220 My world's been changed forever, I think, to be quite honest with you. 214 00:19:24,220 --> 00:19:28,020 There are some of them in places that you won't be filming them. 215 00:19:28,020 --> 00:19:29,340 Get off! 216 00:19:33,500 --> 00:19:36,780 Over 600 million years ago, 217 00:19:36,780 --> 00:19:40,820 Urchoanozoan is about to do something revolutionary. 218 00:19:45,700 --> 00:19:49,620 Its surface is coated with sticky molecules... 219 00:19:53,420 --> 00:19:55,500 ..and when the time comes to divide... 220 00:19:57,420 --> 00:20:01,020 ..instead of floating off to live independent lives... 221 00:20:03,420 --> 00:20:06,300 ..the two remain stuck together. 222 00:20:09,780 --> 00:20:11,700 They continue to divide. 223 00:20:13,820 --> 00:20:16,500 More and more cells stick together... 224 00:20:18,500 --> 00:20:19,540 ...until... 225 00:20:20,860 --> 00:20:23,500 ..a vast alliance forms. 226 00:20:30,780 --> 00:20:32,940 Dubbed the Death Star... 227 00:20:35,180 --> 00:20:38,620 ..it's 100 larger than a single cell... 228 00:20:43,380 --> 00:20:47,060 ..and it has something of the dark side to it. 229 00:20:55,900 --> 00:20:58,340 When the all the flagella wiggle, 230 00:20:58,340 --> 00:21:00,620 they create stronger water currents... 231 00:21:04,580 --> 00:21:09,060 ..drawing in bacteria so the Death Star can feed. 232 00:21:12,940 --> 00:21:17,100 From cells sticking together came a new way of living. 233 00:21:18,660 --> 00:21:22,740 A multicellular organism is formed. 234 00:21:27,820 --> 00:21:31,620 Over the next 100 million years, 235 00:21:31,620 --> 00:21:34,860 the Death Star's descendants continue to grow... 236 00:21:37,180 --> 00:21:39,860 ..not just in size, 237 00:21:39,860 --> 00:21:41,380 but in complexity... 238 00:21:43,540 --> 00:21:47,020 ..as individual cells begin to specialise... 239 00:21:50,620 --> 00:21:54,860 ..until something truly revolutionary emerges... 240 00:21:57,820 --> 00:22:00,340 ..the first bodies on Earth. 241 00:22:11,540 --> 00:22:17,940 The oceans have now warmed and they're full of life forms. 242 00:22:17,940 --> 00:22:23,100 And lurking among them is the ancestor of the elephant. 243 00:22:34,060 --> 00:22:36,660 No trunk, no tusks... 244 00:22:38,340 --> 00:22:42,260 ..just a worm, three millimetres long, 245 00:22:42,260 --> 00:22:45,500 dragging itself across the seafloor. 246 00:22:48,220 --> 00:22:50,140 Evolution gave it a body, 247 00:22:50,140 --> 00:22:54,740 but one so small and simple you'd barely notice it. 248 00:23:02,140 --> 00:23:04,260 Building something bigger 249 00:23:04,260 --> 00:23:09,180 and more complex would require one vital ingredient... 250 00:23:10,340 --> 00:23:11,860 ..oxygen. 251 00:23:11,860 --> 00:23:16,620 Inside every cell in our body a slow, controlled burn is happening. 252 00:23:16,620 --> 00:23:19,260 Not with flames, of course, that would be concerning. 253 00:23:19,260 --> 00:23:23,500 But just like this fire, we need oxygen to release energy. 254 00:23:25,660 --> 00:23:29,260 Without it, we would simply sputter out and die. 255 00:23:32,740 --> 00:23:38,100 But for ancient animals, oxygen was largely out of reach. 256 00:23:42,980 --> 00:23:46,420 I've got some earthworms here, charming creatures, 257 00:23:46,420 --> 00:23:50,580 creatures of childhood, but not terribly sophisticated, 258 00:23:50,580 --> 00:23:52,700 particularly when it comes to breathing. 259 00:23:52,700 --> 00:23:54,900 You see, just like those early animals, 260 00:23:54,900 --> 00:23:56,820 they breathe through their skin. 261 00:23:57,900 --> 00:24:00,740 It's permeable, and as long as it's moist, 262 00:24:00,740 --> 00:24:03,620 they can extract oxygen from the air. 263 00:24:03,620 --> 00:24:08,180 But imagine you're living half a billion years ago. 264 00:24:08,180 --> 00:24:10,660 You're much smaller than this, and living at the bottom 265 00:24:10,660 --> 00:24:15,340 of an ocean where the oxygen supply is pitifully low. 266 00:24:15,340 --> 00:24:18,780 Life was small, life was slow, 267 00:24:18,780 --> 00:24:20,940 life was stuck. 268 00:24:25,620 --> 00:24:30,300 But this ancient worm has stumbled upon a new way to 269 00:24:30,300 --> 00:24:32,380 boost its oxygen supply. 270 00:24:36,860 --> 00:24:40,860 Tiny pores along its body, used to filter food, 271 00:24:40,860 --> 00:24:44,100 are now quietly adapting to a new role. 272 00:24:45,500 --> 00:24:49,700 They're able to draw in a fraction more oxygen... 273 00:24:51,700 --> 00:24:55,700 ..the beginning of a transformation that will allow creatures to 274 00:24:55,700 --> 00:24:58,180 grow bigger and stronger. 275 00:25:01,180 --> 00:25:04,940 And beating the competition is what it's all about. 276 00:25:11,340 --> 00:25:17,580 Generation by generation, tiny wrinkles inside the pores deepen, 277 00:25:17,580 --> 00:25:24,180 folding, twisting, meaning more surface area, 278 00:25:24,180 --> 00:25:25,580 more oxygen... 279 00:25:26,700 --> 00:25:31,300 ..until a whole new body part evolves. 280 00:25:39,420 --> 00:25:43,060 In tracing the evolution of the elephant or, for that matter, 281 00:25:43,060 --> 00:25:44,980 any other large land animal, 282 00:25:44,980 --> 00:25:49,620 the appearance of gills is hardly an obvious landmark moment. 283 00:25:49,620 --> 00:25:52,020 After all, elephants aren't famed for 284 00:25:52,020 --> 00:25:54,860 their deep-sea diving capabilities. 285 00:25:54,860 --> 00:26:00,300 But the emergence of gills was more than a minor upgrade. 286 00:26:00,300 --> 00:26:03,380 It was an evolutionary quantum leap. 287 00:26:07,420 --> 00:26:10,380 This is the fossil of Yunnanozoon. 288 00:26:10,380 --> 00:26:14,260 It lived in the Cambrian around 500 million years ago. 289 00:26:14,260 --> 00:26:19,820 What is it? Well, it wasn't a worm, wasn't yet a fish, 290 00:26:19,820 --> 00:26:23,020 but what makes it interesting is this... 291 00:26:23,020 --> 00:26:26,220 You can see these feathery structures 292 00:26:26,220 --> 00:26:28,700 running down here in rows. 293 00:26:28,700 --> 00:26:32,500 Some scientists believe that this is the first evidence 294 00:26:32,500 --> 00:26:35,220 that we've discovered of gills. 295 00:26:37,660 --> 00:26:40,740 Intricate folds like these can radically increase 296 00:26:40,740 --> 00:26:43,860 the surface area that's in contact with water... 297 00:26:45,180 --> 00:26:49,940 ..giving the animal the potential to access much more oxygen. 298 00:26:51,700 --> 00:26:55,540 And, of course, more oxygen means more energy. 299 00:26:55,540 --> 00:26:59,700 That can mean bigger bodies, faster movement. 300 00:26:59,700 --> 00:27:04,540 This innovation set the stage, not just for fish, 301 00:27:04,540 --> 00:27:07,980 or for elephants, but also for you and I. 302 00:27:09,820 --> 00:27:13,340 We tend to think of gills as a fish thing, 303 00:27:13,340 --> 00:27:17,020 but once they were pretty much everyone's thing. 304 00:27:18,540 --> 00:27:19,580 Every amphibian... 305 00:27:21,340 --> 00:27:24,100 ..reptile, bird, 306 00:27:24,100 --> 00:27:29,140 every mammal alive today descended from ancestors with gills. 307 00:27:31,420 --> 00:27:35,900 So, if gills were such a good idea, 308 00:27:35,900 --> 00:27:38,900 why did so many of us ditch them? 309 00:27:47,180 --> 00:27:52,340 Well, inside this fish is a clue to one of evolution's boldest leaps. 310 00:27:55,180 --> 00:27:58,460 Look at this extraordinary animal. 311 00:27:59,700 --> 00:28:06,780 This is protopterus aethiopicus and it's no ordinary fish. 312 00:28:06,780 --> 00:28:09,460 I mean, superficially it looks like an eel. 313 00:28:09,460 --> 00:28:13,300 It's got this long dorsal fin running all the way 314 00:28:13,300 --> 00:28:16,380 back down to this very spatulate tail here. 315 00:28:16,380 --> 00:28:19,620 Beautiful marbling, but look... 316 00:28:19,620 --> 00:28:22,180 Look at these wiggly limbs that are emerging. 317 00:28:22,180 --> 00:28:26,940 Two at the front here, and two more at the back. 318 00:28:31,900 --> 00:28:35,220 Frankly, what a weird-looking animal! 319 00:28:36,540 --> 00:28:38,860 But I'm dodging the big issue. 320 00:28:38,860 --> 00:28:44,140 What makes it special is that it can live in very stagnant water, 321 00:28:44,140 --> 00:28:46,820 water which is almost devoid of oxygen, 322 00:28:46,820 --> 00:28:50,940 and it can do that because it's a fish with a secret. 323 00:28:50,940 --> 00:28:53,900 Now, it is very, very slimy... 324 00:28:53,900 --> 00:28:55,980 If I can try and pick it up... 325 00:28:55,980 --> 00:28:59,460 I've got to watch my fingers, because it's well-armed 326 00:28:59,460 --> 00:29:02,100 with powerful, crushing teeth. 327 00:29:02,100 --> 00:29:04,980 Whoop! Come on. 328 00:29:04,980 --> 00:29:06,820 What a slippery customer. 329 00:29:06,820 --> 00:29:08,940 I just want you to be able to see its mouth, 330 00:29:08,940 --> 00:29:11,940 because it's through that mouth that it's able to draw 331 00:29:11,940 --> 00:29:17,540 in deliberately deep gulps of air, into a blood vessel lined sac 332 00:29:17,540 --> 00:29:20,780 where the oxygen can diffuse 333 00:29:20,780 --> 00:29:23,500 directly into its circulatory system. 334 00:29:26,100 --> 00:29:27,140 There! 335 00:29:29,780 --> 00:29:33,540 Protopterus aethiopicus, that's its scientific name, 336 00:29:33,540 --> 00:29:36,860 but that adaptation gives it its common name. 337 00:29:38,260 --> 00:29:44,940 This is not a fish out of water, so much as a lungfish on land. 338 00:29:50,900 --> 00:29:56,700 This air-gulping ability first evolved in fish 400 million 339 00:29:56,700 --> 00:30:02,460 years ago, as a simple backup plan for low oxygen water. 340 00:30:02,460 --> 00:30:07,660 But lungs would become key to one of evolution's giant leaps... 341 00:30:09,980 --> 00:30:12,180 ..the leap on to land. 342 00:30:15,940 --> 00:30:21,140 We're jumping through time again, a mere 300 million years. 343 00:30:24,460 --> 00:30:27,260 As animals ventured into new territories... 344 00:30:29,340 --> 00:30:33,300 ..limbs evolved, gills disappeared... 345 00:30:35,940 --> 00:30:37,900 ..bodies transformed. 346 00:30:40,780 --> 00:30:43,260 But we're picking up the elephant's story... 347 00:30:46,660 --> 00:30:49,140 ..at an evolutionary crossroads. 348 00:31:02,900 --> 00:31:05,140 In the age of the dinosaurs, 349 00:31:05,140 --> 00:31:08,260 life had gone truly XXL. 350 00:31:09,660 --> 00:31:12,900 The largest animals to ever walk the Earth. 351 00:31:19,860 --> 00:31:24,700 But the ancestor of the elephant has stayed stubbornly small. 352 00:31:30,260 --> 00:31:34,580 This tiny fuzzball is an early Afrotherian. 353 00:31:38,460 --> 00:31:42,660 It's got a long way to go before it can tower over the Savannah, 354 00:31:42,660 --> 00:31:46,420 but its small size is about to pay off. 355 00:31:50,180 --> 00:31:53,060 A rather large lump of rock is coming. 356 00:31:55,460 --> 00:31:58,860 Time's up for the giant dinosaurs. 357 00:32:00,340 --> 00:32:04,540 Mass extinction events don't go well for large animals. 358 00:32:04,540 --> 00:32:06,900 They need too much food when there's not much about, 359 00:32:06,900 --> 00:32:08,740 they're slow to reproduce, 360 00:32:08,740 --> 00:32:11,700 they simply can't bounce back quick enough. 361 00:32:11,700 --> 00:32:15,780 In order to survive, you need to be resourceful, adaptable, 362 00:32:15,780 --> 00:32:19,180 but above everything else, you need to be small. 363 00:32:19,180 --> 00:32:22,060 A bit like this little chap here. 364 00:32:22,060 --> 00:32:24,580 Where is he? Here he is. 365 00:32:24,580 --> 00:32:26,300 Look at that. 366 00:32:26,300 --> 00:32:30,020 That is a tree hyrax. 367 00:32:30,020 --> 00:32:32,140 It's about four or five months old. 368 00:32:32,140 --> 00:32:34,140 What a little beauty! 369 00:32:35,340 --> 00:32:39,100 This tree hyrax is a hand-reared orphan, 370 00:32:39,100 --> 00:32:43,140 allowing us to get an insight into what the elephant might have 371 00:32:43,140 --> 00:32:45,620 looked like before it bulked up... 372 00:32:46,940 --> 00:32:49,300 ..because, believe it or not, 373 00:32:49,300 --> 00:32:54,180 the hyrax is one of the elephant's closest living relatives. 374 00:32:55,860 --> 00:32:59,620 OK, he's coming, albeit slowly. Come on. 375 00:33:05,420 --> 00:33:07,020 What about that? 376 00:33:07,020 --> 00:33:10,820 I'm tempted to use the "c-word". I mean, he's undeniably cute. 377 00:33:10,820 --> 00:33:12,540 Look at the size of those eyes. 378 00:33:14,420 --> 00:33:16,900 After the asteroid impact, it would 379 00:33:16,900 --> 00:33:21,180 have been mammals of this size that were left roaming the Earth. 380 00:33:21,180 --> 00:33:24,940 All of the big species would have been wiped out completely. 381 00:33:24,940 --> 00:33:26,980 Hey, come on. 382 00:33:26,980 --> 00:33:28,340 Mind your footing. 383 00:33:33,140 --> 00:33:36,060 And you can see that it's retained some of the characteristics 384 00:33:36,060 --> 00:33:37,740 that helped them survive. 385 00:33:37,740 --> 00:33:40,700 It's nimble, it's cautious, undeniably, 386 00:33:40,700 --> 00:33:43,260 and it knows how to stay out of trouble. 387 00:33:44,260 --> 00:33:48,260 But, you know, that extinction event wasn't all about devastation. 388 00:33:48,260 --> 00:33:51,900 It also offered up a landscape of opportunity, 389 00:33:51,900 --> 00:33:55,660 a complete continent ripe for repopulation. 390 00:34:01,460 --> 00:34:03,980 With no giant dinosaurs for competition... 391 00:34:05,260 --> 00:34:10,780 ..Africa was an empty stage for evolution to run riot. 392 00:34:12,620 --> 00:34:15,820 The plants waste no time bouncing back. 393 00:34:18,500 --> 00:34:23,060 But the ancestor of the elephant remains small and furry. 394 00:34:24,220 --> 00:34:28,180 To get big, it needs food and lots of it. 395 00:34:29,660 --> 00:34:33,420 But the hard part isn't finding dinner. 396 00:34:33,420 --> 00:34:35,060 It's eating it. 397 00:34:43,660 --> 00:34:45,900 Plants must be easy to eat, right? 398 00:34:45,900 --> 00:34:48,300 After all, they can't run away, 399 00:34:48,300 --> 00:34:51,140 they can't fight back and they are everywhere. 400 00:34:52,300 --> 00:34:55,180 Well, not exactly, because obviously, 401 00:34:55,180 --> 00:34:57,340 plants don't want to be eaten. 402 00:34:57,340 --> 00:35:01,100 So, whilst they can't fight or claw their way out of trouble, 403 00:35:01,100 --> 00:35:05,020 they have come up with a formidable range of defences, which 404 00:35:05,020 --> 00:35:10,020 means that all of this greenery here is almost impossible to eat. 405 00:35:12,860 --> 00:35:18,300 For the ancestors of elephants, plants posed a serious challenge, 406 00:35:18,300 --> 00:35:23,060 not just because of thorns or toxins, but what they're made of. 407 00:35:24,060 --> 00:35:27,860 Even modern mammals struggle to digest them. 408 00:35:27,860 --> 00:35:29,260 Whose poo? 409 00:35:35,660 --> 00:35:40,660 Well, those of you with horses and ponies will probably get this. 410 00:35:40,660 --> 00:35:43,580 This is zebra poo. 411 00:35:44,980 --> 00:35:46,140 Look at that. 412 00:35:46,140 --> 00:35:48,580 We don't have too much time to admire it from the outside, 413 00:35:48,580 --> 00:35:51,060 let's delve in straight away. 414 00:35:51,060 --> 00:35:54,300 If I take this piece here, look at that! 415 00:35:54,300 --> 00:35:58,060 It looks like grass clippings. 416 00:35:58,060 --> 00:36:01,740 So, this has been nibbled, it's been munched, 417 00:36:01,740 --> 00:36:04,740 it's gone through the stomach, all the way through the gut of the 418 00:36:04,740 --> 00:36:09,740 zebra, and yet it's barely digested, and that's because the bulk 419 00:36:09,740 --> 00:36:13,260 of the material that you can see here is something called cellulose. 420 00:36:13,260 --> 00:36:17,580 It's the tough stuff that gives plants their strength and rigidity. 421 00:36:17,580 --> 00:36:19,100 But think about it. 422 00:36:19,100 --> 00:36:21,860 If a contemporary, complex, 423 00:36:21,860 --> 00:36:25,980 specialised herbivore like a zebra can't properly digest this 424 00:36:25,980 --> 00:36:30,620 stuff, what chance would those early mammals have? 425 00:36:41,460 --> 00:36:46,220 In truth, we are not certain whether the ancestors of the elephant 426 00:36:46,220 --> 00:36:51,500 made the leap to plant eating before or after the extinction event. 427 00:36:53,220 --> 00:36:54,820 The fossil record is patchy... 428 00:37:04,100 --> 00:37:06,860 ..but we do know the leap happened 429 00:37:06,860 --> 00:37:09,140 thanks to an unlikely alliance... 430 00:37:16,700 --> 00:37:18,620 Not with the bugs it was hunting. 431 00:37:19,780 --> 00:37:22,660 With something much smaller. 432 00:37:22,660 --> 00:37:26,100 You see, inside the elephant's ancestor, 433 00:37:26,100 --> 00:37:31,020 an invisible army of single-celled microbes is assembling. 434 00:37:32,820 --> 00:37:34,660 It's not an invasion, 435 00:37:34,660 --> 00:37:38,260 it's the start of a vital partnership. 436 00:37:41,060 --> 00:37:45,220 My goodness! Who says size is not important? 437 00:37:45,220 --> 00:37:48,420 This is not a termite mound, it's a termite monument! 438 00:37:48,420 --> 00:37:51,580 It's got to be five metres tall! 439 00:37:51,580 --> 00:37:55,860 Termites are famous for eating wood and other plant material, 440 00:37:55,860 --> 00:37:59,060 but in truth, that's not the whole story. 441 00:37:59,060 --> 00:38:03,060 They do the chewing, it's other organisms that do the digesting. 442 00:38:13,500 --> 00:38:18,740 Inside termite mounds, we find one of nature's strangest team-ups. 443 00:38:23,660 --> 00:38:26,500 Now, Chris Packham, a bloke who loves animals, 444 00:38:26,500 --> 00:38:29,740 why is he smashing up a termite mound? 445 00:38:29,740 --> 00:38:31,540 Well, I've thought long and hard about this. 446 00:38:31,540 --> 00:38:34,260 Firstly, they're extraordinarily resilient animals, 447 00:38:34,260 --> 00:38:37,060 they'll rebuild this really quickly. 448 00:38:37,060 --> 00:38:40,220 And the second thing is that every night, all over here, 449 00:38:40,220 --> 00:38:41,980 animals will be breaking into them. 450 00:38:41,980 --> 00:38:45,100 Just consider me the human aardvark. 451 00:38:45,100 --> 00:38:49,780 Besides, what I'm looking for is just under the surface. 452 00:38:49,780 --> 00:38:54,220 There are plenty of termites here, but I'm looking for something else. 453 00:38:54,220 --> 00:38:55,900 Ah! 454 00:38:55,900 --> 00:38:58,340 VOICEOVER: Another life-form lives here. 455 00:38:58,340 --> 00:38:59,580 I think this is it. 456 00:38:59,580 --> 00:39:01,900 VOICEOVER: Small, silent... 457 00:39:01,900 --> 00:39:03,220 Oh, yes, it is! 458 00:39:03,220 --> 00:39:05,060 ..and surprisingly useful. 459 00:39:05,060 --> 00:39:06,780 Look at that! 460 00:39:08,740 --> 00:39:12,380 That is termite fungal comb. 461 00:39:12,380 --> 00:39:15,660 Now, the interesting thing about this fungus is that you can 462 00:39:15,660 --> 00:39:20,980 only find it in termite mounds, nowhere else in the world. 463 00:39:20,980 --> 00:39:24,340 You see, the termites sort of farm it. 464 00:39:24,340 --> 00:39:27,300 They go out and they collect all that dead plant material, 465 00:39:27,300 --> 00:39:30,660 which they can't digest themselves, and then they come back 466 00:39:30,660 --> 00:39:32,940 and give it to the fungus. 467 00:39:32,940 --> 00:39:35,420 The fungus does digest the cellulose, 468 00:39:35,420 --> 00:39:40,020 and then turn it into substances which the termites can eat. 469 00:39:40,020 --> 00:39:41,300 What about that? 470 00:39:43,180 --> 00:39:46,820 And, of course, it's not just termites. 471 00:39:48,620 --> 00:39:53,300 Almost every plant-eater you can name has outsourced digestion 472 00:39:53,300 --> 00:39:54,540 to microbes. 473 00:39:57,340 --> 00:39:58,700 The only difference... 474 00:40:01,660 --> 00:40:07,660 ..most keep their microbial munchers safely tucked away inside their gut. 475 00:40:09,540 --> 00:40:14,100 Just as our bodies evolved, these sorts of partnerships evolved. 476 00:40:14,100 --> 00:40:16,820 It's difficult to know when, though, because we don't have any 477 00:40:16,820 --> 00:40:20,900 fossils of prehistoric animals with bacteria in their guts. 478 00:40:20,900 --> 00:40:24,460 But one thing we know for sure, and that is that over millions of years, 479 00:40:24,460 --> 00:40:28,660 many species have become dependent on these sorts of relationships. 480 00:40:28,660 --> 00:40:31,580 Without them, they would simply die. 481 00:40:39,900 --> 00:40:45,540 Sometimes, evolution's boldest moves aren't physical adaptations, 482 00:40:45,540 --> 00:40:47,460 they're partnerships. 483 00:40:48,660 --> 00:40:52,100 And now, thanks to its microbiome, 484 00:40:52,100 --> 00:40:54,860 it's a good time to sample the salad bar. 485 00:40:59,340 --> 00:41:02,140 Generation by generation, 486 00:41:02,140 --> 00:41:05,540 the gut balloons into a fermentation factory... 487 00:41:07,700 --> 00:41:10,700 ..filled with trillions upon trillions 488 00:41:10,700 --> 00:41:12,780 of plant-munching microbes. 489 00:41:19,900 --> 00:41:23,660 Just what you need for a plant-based diet. 490 00:41:30,540 --> 00:41:33,940 And less than 20 million years later... 491 00:41:35,020 --> 00:41:40,220 ..we get this charming creature, an early proboscidean... 492 00:41:52,060 --> 00:41:56,100 ..now standing at a respectable one metre tall. 493 00:41:58,100 --> 00:42:01,780 But evolution has hit a problem of its own making. 494 00:42:03,500 --> 00:42:08,980 This proboscidean has elongated front teeth. 495 00:42:08,980 --> 00:42:11,100 Great for snagging vegetation... 496 00:42:17,260 --> 00:42:20,460 ..but big teeth can have drawbacks. 497 00:42:33,660 --> 00:42:36,500 This is the skull of an adult hyrax. 498 00:42:38,140 --> 00:42:43,540 It's got these massively oversized incisors there. 499 00:42:43,540 --> 00:42:45,460 What are those teeth for? 500 00:42:45,460 --> 00:42:49,060 Well, for seeing off predators, things like snakes and eagles, 501 00:42:49,060 --> 00:42:51,420 for displaying to other hyrax, and, if they cross the line, 502 00:42:51,420 --> 00:42:53,340 for seeing them off too. 503 00:42:53,340 --> 00:42:57,060 But we've got to remember that this is a herbivorous animal. 504 00:42:57,060 --> 00:43:00,580 How's it going to be nibbling leaves with these in the way? 505 00:43:02,460 --> 00:43:04,660 Well, it's going to struggle, and I can demonstrate 506 00:43:04,660 --> 00:43:10,820 that by adapting my own teeth with some elongated 507 00:43:10,820 --> 00:43:15,620 incisors of my own, and then try and tuck into a hyrax salad. 508 00:43:20,300 --> 00:43:23,460 Frankly, it's just not working. 509 00:43:23,460 --> 00:43:27,140 So, look, whilst big teeth can be impressive, and they certainly have 510 00:43:27,140 --> 00:43:31,100 their uses, if you're a herbivore, they can represent somewhat 511 00:43:31,100 --> 00:43:34,820 of an evolutionary challenge when it comes to grabbing your grub. 512 00:43:37,020 --> 00:43:40,460 Big front teeth come with trade-offs. 513 00:43:40,460 --> 00:43:44,740 For the hyrax, it means eating food through the side of the mouth. 514 00:43:47,820 --> 00:43:49,420 But with the proboscideans, 515 00:43:49,420 --> 00:43:51,900 evolution went down a different path. 516 00:43:57,820 --> 00:44:03,620 One individual was born with a slightly longer nose. 517 00:44:10,540 --> 00:44:14,060 It's the beginning of something special. 518 00:44:24,860 --> 00:44:27,140 WHISPERS: There they are. There they are. 519 00:44:27,140 --> 00:44:30,220 To see what a flexible face can be capable of, 520 00:44:30,220 --> 00:44:33,260 we need a snout specialist. 521 00:44:34,940 --> 00:44:39,060 It's like being a lion, isn't it? Going out warthog hunting. 522 00:44:39,060 --> 00:44:41,900 Graceful? Not really. 523 00:44:41,900 --> 00:44:46,020 These are animals built for getting the job done. 524 00:44:46,020 --> 00:44:47,460 Warthogs... 525 00:44:47,460 --> 00:44:51,780 So ugly that they've crossed that line back into being beautiful. 526 00:44:51,780 --> 00:44:55,060 But we're not here for a beauty pageant, we're here for biology, 527 00:44:55,060 --> 00:44:59,980 so let's concentrate on their noses, a remarkable multi-tool. 528 00:45:02,820 --> 00:45:06,380 Warthog noses aren't just for sniffing snacks. 529 00:45:08,020 --> 00:45:12,020 They're for digging roots, and manoeuvring food into place. 530 00:45:15,660 --> 00:45:19,100 It's tough, it's not a delicate nose like ours. 531 00:45:19,100 --> 00:45:20,500 It's really robust. 532 00:45:22,140 --> 00:45:25,540 But even the best nose has its limits... 533 00:45:27,380 --> 00:45:32,900 ..especially when your food is on the ground, and your face isn't. 534 00:45:32,900 --> 00:45:35,140 The thing is, when you see them standing up, 535 00:45:35,140 --> 00:45:37,900 they've got quite long legs and short necks, 536 00:45:37,900 --> 00:45:41,740 so how do you get your nose down closer to the ground? 537 00:45:41,740 --> 00:45:45,180 Well, you do it like that - 538 00:45:45,180 --> 00:45:46,540 kneeling down. 539 00:45:51,060 --> 00:45:56,220 OK, so technically these are the creature's wrists, 540 00:45:56,220 --> 00:45:59,980 but either way, it's a brilliant example of evolution 541 00:45:59,980 --> 00:46:02,420 solving a problem of its own making. 542 00:46:05,060 --> 00:46:08,780 Certainly an effective solution, but it's not the only way 543 00:46:08,780 --> 00:46:12,420 of meeting that challenge of getting your nose closer to the ground. 544 00:46:12,420 --> 00:46:15,260 But there was a creature that lived millions of years ago that 545 00:46:15,260 --> 00:46:18,140 met the challenge in a completely different way 546 00:46:18,140 --> 00:46:21,700 and came up with something even more extraordinary. 547 00:46:21,700 --> 00:46:26,260 A tool, if you like, that it could use for eating, drinking, 548 00:46:26,260 --> 00:46:29,300 smelling and exploring the world. 549 00:46:34,420 --> 00:46:40,660 It would be the final flourish of an extraordinary evolutionary journey, 550 00:46:40,660 --> 00:46:46,220 a journey that started 4.2 billion years ago with 551 00:46:46,220 --> 00:46:49,780 a single cell that multiplied... 552 00:46:53,540 --> 00:46:55,580 ..and grew in complexity... 553 00:46:56,980 --> 00:46:58,220 ..gained a body... 554 00:46:59,860 --> 00:47:01,580 ..took a deep breath, 555 00:47:01,580 --> 00:47:03,340 and jumped onto land... 556 00:47:09,260 --> 00:47:15,020 ..before teaming up with microbes, giving it the guts to go vegan. 557 00:47:18,900 --> 00:47:22,700 And now, after countless generations... 558 00:47:24,140 --> 00:47:27,060 ..the nose gets longer... 559 00:47:29,820 --> 00:47:36,420 ..stretching down to the ground, giving better access to food, 560 00:47:36,420 --> 00:47:39,380 so the body continues to grow... 561 00:47:41,540 --> 00:47:46,260 ..until we get an animal of mindboggling complexity 562 00:47:46,260 --> 00:47:50,020 and size that you might just recognise. 563 00:47:58,220 --> 00:48:00,980 Meet Paleomastodon. 564 00:48:03,260 --> 00:48:06,620 It's got the trunk, it's got the tusks. 565 00:48:06,620 --> 00:48:09,300 Big ears? Still a work in progress... 566 00:48:11,540 --> 00:48:16,260 ..but it's a body shape we might finally call an elephant. 567 00:48:20,460 --> 00:48:22,980 And evolution didn't stop there. 568 00:48:26,740 --> 00:48:30,060 From creatures with bizarre jaw extensions... 569 00:48:34,620 --> 00:48:38,020 ..others with downward-curving tusks... 570 00:48:42,060 --> 00:48:47,780 ..and, of course, those icons of the Ice Age, the mammoths. 571 00:48:53,940 --> 00:48:57,540 Giant proboscideans once spanned the globe. 572 00:49:02,820 --> 00:49:08,260 Africa, Asia, Europe 573 00:49:08,260 --> 00:49:10,500 and South America. 574 00:49:10,500 --> 00:49:14,660 We have evidence of our relationship with proboscideans 575 00:49:14,660 --> 00:49:19,700 from all over the world, in the form of these carvings and paintings. 576 00:49:20,900 --> 00:49:24,860 These were not just creatures that were living in that landscape. 577 00:49:24,860 --> 00:49:27,980 We evolved alongside them. 578 00:49:27,980 --> 00:49:31,860 Our histories are uniquely intertwined. 579 00:49:36,100 --> 00:49:40,420 Some proboscideans were lost to natural climate change, 580 00:49:40,420 --> 00:49:45,540 but for others, it was the actions of our own ancestors. 581 00:49:50,420 --> 00:49:54,340 Today, just three species of proboscidean remain... 582 00:49:55,820 --> 00:50:00,540 ..each emerging within the last 10 million years - 583 00:50:00,540 --> 00:50:01,980 the Asian elephant... 584 00:50:05,500 --> 00:50:07,420 ..the African forest elephant... 585 00:50:10,980 --> 00:50:13,260 ..and, the biggest of them all, 586 00:50:13,260 --> 00:50:17,900 a grass-eating giant shaped on the open plains... 587 00:50:19,500 --> 00:50:21,980 ..the African savannah elephant. 588 00:50:27,300 --> 00:50:28,580 Remarkable! 589 00:50:30,220 --> 00:50:33,380 Aw, you're wonderful, aren't you? 590 00:50:33,380 --> 00:50:37,380 Let's take one last look at these incredible creatures. 591 00:50:40,700 --> 00:50:46,180 Made up of a million billion cells, powered by the largest lungs 592 00:50:46,180 --> 00:50:52,780 of any land animal, and in there, a gut coiled up, 20 metres long, 593 00:50:52,780 --> 00:50:58,020 packed full of microbes so it can digest all of this plant material. 594 00:50:58,020 --> 00:51:01,980 And then look at the front here, these tusks, and between them, 595 00:51:01,980 --> 00:51:06,180 this extraordinary, modified nose, its trunk, 596 00:51:06,180 --> 00:51:09,580 strong enough to pick up and carry a human, 597 00:51:09,580 --> 00:51:12,580 delicate enough to pick up a penny. 598 00:51:18,900 --> 00:51:23,100 The evolutionary journey that created the bizarre 599 00:51:23,100 --> 00:51:27,060 and beautiful elephant is just one story. 600 00:51:30,060 --> 00:51:34,260 Because, thanks to LUCA, that single-celled 601 00:51:34,260 --> 00:51:37,620 Last Universal Common Ancestor, 602 00:51:37,620 --> 00:51:41,980 we are all part of an ancient family. 603 00:51:43,140 --> 00:51:47,300 A family that may be bad at keeping in touch, 604 00:51:47,300 --> 00:51:50,820 and may be a little dysfunctional, 605 00:51:50,820 --> 00:51:55,220 but is always undeniably miraculous. 606 00:52:01,740 --> 00:52:03,060 Look at this! 607 00:52:03,060 --> 00:52:07,780 I'm literally leading a group of elephants through the forest. 608 00:52:07,780 --> 00:52:09,780 Who would have ever thought it? 609 00:52:12,420 --> 00:52:17,060 Every living thing, everything that's ever walked, 610 00:52:17,060 --> 00:52:24,540 swum or flown is all connected in that one tangled story, connected 611 00:52:24,540 --> 00:52:30,940 by that thread that runs through a four billion year tapestry of life. 612 00:52:34,940 --> 00:52:40,500 Evolution is messy, evolution's unpredictable and so grand, 613 00:52:40,500 --> 00:52:44,300 we're still really figuring out how it works, but there is one 614 00:52:44,300 --> 00:52:49,220 thing that we do know, and that is that given time and the resources, 615 00:52:49,220 --> 00:52:54,300 it comes up with creatures that are as remarkable as this. 616 00:52:57,020 --> 00:53:01,860 And we should cherish all life on Earth, not neglect it or 617 00:53:01,860 --> 00:53:07,140 destroy it, because evolution is wonderful, 618 00:53:07,140 --> 00:53:10,500 life is beautiful. 619 00:53:10,500 --> 00:53:12,780 # You're such a 620 00:53:12,780 --> 00:53:15,300 # Beautiful freak 621 00:53:16,580 --> 00:53:18,580 # I wish there were 622 00:53:18,580 --> 00:53:21,180 # More just like you... # 623 00:53:32,300 --> 00:53:37,100 Next time - how the ostrich got the biggest egg on the planet... 624 00:53:37,100 --> 00:53:39,420 It's quite emotional, if I'm honest with you! 625 00:53:40,940 --> 00:53:43,620 ..a four billion year love story... 626 00:53:44,900 --> 00:53:46,380 ..from the first sex... 627 00:53:47,820 --> 00:53:49,700 ..to conquering the land. 628 00:53:53,380 --> 00:53:55,620 An incredible journey of flirting... 629 00:53:57,260 --> 00:53:58,700 ..feathers 630 00:53:58,700 --> 00:54:00,460 and fornication... 631 00:54:01,700 --> 00:54:03,140 ..giving rise... 632 00:54:03,140 --> 00:54:05,060 Look at this! 633 00:54:05,060 --> 00:54:07,740 ..to one of the most extraordinary birds. 634 00:54:17,500 --> 00:54:18,980 But first, 635 00:54:18,980 --> 00:54:24,180 how do we know that all life on Earth has a common ancestor? 636 00:54:27,060 --> 00:54:32,060 For centuries, fossils have provided a window into the past, 637 00:54:32,060 --> 00:54:35,460 helping scientists reconstruct the tree of life. 638 00:54:36,620 --> 00:54:41,860 - In the past, our understanding for how a fossil fits in this 639 00:54:41,860 --> 00:54:46,100 larger system of life on Earth was comparative anatomy, 640 00:54:46,100 --> 00:54:48,780 and it worked for a long time, and it was a beautiful tool. 641 00:54:48,780 --> 00:54:51,500 - Scientists would look at what animals or other organisms 642 00:54:51,500 --> 00:54:53,740 had in common, or didn't have in common, 643 00:54:53,740 --> 00:54:56,540 to try to recreate their evolutionary relationships. 644 00:54:56,540 --> 00:54:58,300 - I think one thing we have to bear in mind is 645 00:54:58,300 --> 00:55:00,860 when we look at fossils, we're looking at just the remains, 646 00:55:00,860 --> 00:55:03,180 what is left behind, and it's not always complete. 647 00:55:03,180 --> 00:55:05,900 So, it's like trying to reconstruct a hand from a fingerprint. 648 00:55:05,900 --> 00:55:08,940 - And we made lots of mistakes. - LAUGHS 649 00:55:11,740 --> 00:55:13,980 But in the middle of the last century, 650 00:55:13,980 --> 00:55:16,980 a discovery changed everything. 651 00:55:16,980 --> 00:55:20,060 - The appearance of DNA really was a game-changer. 652 00:55:20,060 --> 00:55:23,740 - We couldn't study the tree of life with just comparative anatomy. 653 00:55:23,740 --> 00:55:24,860 You need DNA. 654 00:55:27,820 --> 00:55:31,900 - We can compare genes to each other, compare those gene sequences 655 00:55:31,900 --> 00:55:35,020 to each other, look at the letters that those genes contain, 656 00:55:35,020 --> 00:55:38,300 and use that information to try to figure out how different 657 00:55:38,300 --> 00:55:40,180 organisms are related to each other. 658 00:55:43,140 --> 00:55:47,460 - By analysing DNA, scientists have discovered that some 659 00:55:47,460 --> 00:55:49,380 creatures that look very different 660 00:55:49,380 --> 00:55:52,300 are actually closely related, 661 00:55:52,300 --> 00:55:54,940 like the Afrotherian mammals. 662 00:55:58,460 --> 00:56:04,060 And it's also allowed us to trace the tree of life back further 663 00:56:04,060 --> 00:56:08,940 than ever before, all the way to its root. 664 00:56:10,620 --> 00:56:13,500 - LAUGHS ALL: - LUCA. 665 00:56:13,500 --> 00:56:16,700 - The Last Universal Common Ancestor to all life on Earth. 666 00:56:17,980 --> 00:56:21,860 - It's the last organism that we can point back and say, "This is 667 00:56:21,860 --> 00:56:26,180 "a relative of not only us, but bacteria and elephants and bananas." 668 00:56:26,180 --> 00:56:29,380 - I love thinking of LUCA as being not just my 669 00:56:29,380 --> 00:56:32,220 great-great-great-great-great-great- whatever grandparent, 670 00:56:32,220 --> 00:56:35,660 but everybody's great-great-great-great-great- whatever grandparent. 671 00:56:36,900 --> 00:56:40,140 - In a landmark study, scientists analysed 672 00:56:40,140 --> 00:56:44,900 the DNA of 700 different microbial species, searching 673 00:56:44,900 --> 00:56:48,820 for patterns that would help them reconstruct LUCA's genetic code. 674 00:56:49,900 --> 00:56:53,860 - Our ability to sequence DNA really has unlocked our ability to 675 00:56:53,860 --> 00:56:57,940 look deep in time to 4 billion years ago 676 00:56:57,940 --> 00:57:00,380 and come to a better understanding of what 677 00:57:00,380 --> 00:57:03,300 our Last Universal Common Ancestor may have looked like. 678 00:57:05,500 --> 00:57:09,140 - The study revealed that LUCA was likely to have had 679 00:57:09,140 --> 00:57:14,780 over 2,600 genes, making it surprisingly complex. 680 00:57:17,740 --> 00:57:20,300 - So, it wasn't necessarily the first form of life. 681 00:57:20,300 --> 00:57:23,620 It almost certainly wasn't, but it's the one that got by. 682 00:57:23,620 --> 00:57:28,700 - From that one spark, we see the origin of all the life that we 683 00:57:28,700 --> 00:57:31,100 see today in its incredible diversity. 684 00:57:36,660 --> 00:57:39,140 - Realising that we all came from LUCA, 685 00:57:39,140 --> 00:57:44,740 the same seed of the tree of life, is really humbling to me. 686 00:57:44,740 --> 00:57:47,260 It's a way of thinking about the world 687 00:57:47,260 --> 00:57:50,020 in a much more connected way. 688 00:57:50,020 --> 00:57:51,620 We all came from the same place. 689 00:57:53,500 --> 00:57:58,220 - We've not only expanded our understanding of the tree life, but 690 00:57:58,220 --> 00:58:01,980 it's changed our understanding of where we fit into the tree of life. 691 00:58:05,940 --> 00:58:09,540 - Do you want to know how an elephant is related to a clownfish? 692 00:58:09,540 --> 00:58:13,860 Discover more in a poster from the Open University on the tree of life. 693 00:58:13,860 --> 00:58:17,820 To get your free copy, scan the QR code on screen, or ring... 694 00:58:21,420 --> 00:58:22,740 ..or visit...