1 00:00:17,160 --> 00:00:20,096 Across our natural world, 2 00:00:20,120 --> 00:00:23,440 life has taken on countless forms. 3 00:00:26,880 --> 00:00:30,480 Wondrous, strange... 4 00:00:31,560 --> 00:00:33,920 and endlessly diverse. 5 00:00:38,280 --> 00:00:41,256 It's easy to imagine that all of this is, like, 6 00:00:41,280 --> 00:00:43,160 somehow preordained... 7 00:00:45,440 --> 00:00:49,296 that it's been made, a world of balance and purpose, 8 00:00:49,320 --> 00:00:53,296 but the truth... The truth is much wilder. 9 00:00:53,320 --> 00:00:56,560 This is a world of survivors. 10 00:00:58,600 --> 00:01:01,416 From Earth's earliest moments, 11 00:01:01,440 --> 00:01:03,896 evolution has quietly, 12 00:01:03,920 --> 00:01:05,496 relentlessly, 13 00:01:05,520 --> 00:01:08,000 shaped the story of life. 14 00:01:09,440 --> 00:01:10,560 I can hear it... 15 00:01:11,920 --> 00:01:13,616 And in this series... 16 00:01:13,640 --> 00:01:15,696 It's quite emotional, if I'm honest with you! 17 00:01:15,720 --> 00:01:20,936 we'll trace the astonishing evolutionary journeys of five 18 00:01:20,960 --> 00:01:23,576 iconic modern animals. 19 00:01:23,600 --> 00:01:25,136 Look at this! 20 00:01:25,160 --> 00:01:27,216 Truly spectacular! 21 00:01:27,240 --> 00:01:31,296 We'll meet their oddball ancestors from the distant past 22 00:01:31,320 --> 00:01:35,496 and discover how generation, by generation... 23 00:01:35,520 --> 00:01:39,056 Absolutely amazing! 24 00:01:39,080 --> 00:01:42,600 they changed, to become the creatures we know today. 25 00:01:45,680 --> 00:01:50,176 From the smallest beginnings come the most extraordinary stories, 26 00:01:50,200 --> 00:01:54,256 stories of survival, of bizarre transformations, 27 00:01:54,280 --> 00:01:57,416 shaping life in the strangest of ways 28 00:01:57,440 --> 00:02:02,280 and, behind it all, the unstoppable force of evolution. 29 00:02:59,800 --> 00:03:05,416 Look at that! They used to say that animals couldn't experience joy. 30 00:03:05,440 --> 00:03:11,320 Come on! That looks like muddy, wet joy to me! 31 00:03:17,480 --> 00:03:18,760 CHRIS LAUGHS 32 00:03:21,800 --> 00:03:26,736 The African savannah elephant has to be one of evolution's most 33 00:03:26,760 --> 00:03:29,320 enchantingly strange creatures. 34 00:03:30,760 --> 00:03:32,040 I mean, look at the trunk. 35 00:03:33,440 --> 00:03:37,536 When they're adult, that measures nearly two metres in length, 36 00:03:37,560 --> 00:03:41,520 and it contains perhaps 90,000 miniature muscles. 37 00:03:43,800 --> 00:03:45,736 And then the tusks. 38 00:03:45,760 --> 00:03:48,600 Those are teeth that never stop growing. 39 00:03:49,920 --> 00:03:52,696 The ears! Look at the ears on this one, 40 00:03:52,720 --> 00:03:55,256 the size of a table cloth, 41 00:03:55,280 --> 00:03:56,720 flapping away. 42 00:03:59,840 --> 00:04:06,016 But their one most obvious defining feature, of course, is their size. 43 00:04:06,040 --> 00:04:07,400 Look at that! 44 00:04:10,160 --> 00:04:14,616 They can regularly reach five, six, seven tonnes. 45 00:04:14,640 --> 00:04:16,640 The very biggest, ten tonnes. 46 00:04:17,840 --> 00:04:19,560 They are colossal. 47 00:04:21,320 --> 00:04:23,256 So, here's a question for you. 48 00:04:23,280 --> 00:04:26,856 How did evolution come up with something as complex, 49 00:04:26,880 --> 00:04:30,480 as beautiful and as enormous as this? 50 00:04:31,640 --> 00:04:34,200 How did the elephant come to be? 51 00:04:38,960 --> 00:04:41,696 Well, to understand the elephant, 52 00:04:41,720 --> 00:04:44,280 the largest land animal alive today... 53 00:04:46,520 --> 00:04:49,440 you have to understand evolution itself. 54 00:04:51,640 --> 00:04:55,480 There was no blueprint, no grand design. 55 00:04:56,920 --> 00:05:03,120 Evolution is a process, shaped by powerful, invisible drivers. 56 00:05:06,600 --> 00:05:07,800 Like hunger... 57 00:05:08,800 --> 00:05:09,840 conflict... 58 00:05:10,960 --> 00:05:12,000 and even... 59 00:05:14,840 --> 00:05:16,240 catastrophe. 60 00:05:18,120 --> 00:05:20,920 So where does our story begin? 61 00:05:23,160 --> 00:05:27,760 The answer lies in what these giants are made of. 62 00:05:30,560 --> 00:05:35,776 They may be the world's largest land mammals, they may be beautiful, 63 00:05:35,800 --> 00:05:42,056 but brutally biologically speaking, this is just a giant mass of cells. 64 00:05:42,080 --> 00:05:44,736 Now, in case of the elephant, that's a lot of cells. 65 00:05:44,760 --> 00:05:46,616 It's a quadrillion. 66 00:05:46,640 --> 00:05:50,440 That's a one with 15 zeros after it. 67 00:05:57,360 --> 00:06:02,816 Cells are the fundamental building blocks, not just of elephants, 68 00:06:02,840 --> 00:06:06,920 but of all life today, be it animal... 69 00:06:07,920 --> 00:06:09,296 plant, 70 00:06:09,320 --> 00:06:10,440 fungi... 71 00:06:11,960 --> 00:06:13,120 or bacteria. 72 00:06:16,160 --> 00:06:18,560 So, where did those cells come from? 73 00:06:20,480 --> 00:06:25,176 Well, each one of this animal's cells has come from other 74 00:06:25,200 --> 00:06:29,296 cells, which have either divided or reproduced. 75 00:06:29,320 --> 00:06:32,136 OK, where did those cells come from? 76 00:06:32,160 --> 00:06:34,776 Well, they come from other cells that divided and reproduced. 77 00:06:34,800 --> 00:06:38,976 In fact, we can trace this chain back over unimaginable 78 00:06:39,000 --> 00:06:44,816 periods of time, through many long-lost extinct species, 79 00:06:44,840 --> 00:06:50,136 until remarkably it converges at a single point, 80 00:06:50,160 --> 00:06:54,936 a single-celled organism that's connected to every living thing, 81 00:06:54,960 --> 00:06:58,256 every branch on the tree of life, 82 00:06:58,280 --> 00:07:03,656 a common ancestor that lived billions of years ago, 83 00:07:03,680 --> 00:07:06,920 the cell that started everything. 84 00:07:09,320 --> 00:07:13,880 Now, when it comes to evolution, you need to take the long view. 85 00:07:14,880 --> 00:07:17,640 I mean the really long view. 86 00:07:19,160 --> 00:07:25,096 The elephant's improbable journey begins before mammals, before 87 00:07:25,120 --> 00:07:31,040 dinosaurs stomped about, before anything even had legs to stomp. 88 00:07:32,360 --> 00:07:35,520 It's a story that starts with a simple truth. 89 00:07:38,680 --> 00:07:42,760 If you want to evolve, you have to survive first. 90 00:07:50,920 --> 00:07:52,376 Violent, 91 00:07:52,400 --> 00:07:54,016 loud... 92 00:07:54,040 --> 00:07:56,976 Frankly, overdramatic. 93 00:07:57,000 --> 00:07:59,400 The young Earth is no paradise... 94 00:08:02,480 --> 00:08:07,360 but beneath the waves, life has already taken hold. 95 00:08:12,240 --> 00:08:16,640 Trillions of tiny, primitive cells battle the elements. 96 00:08:19,640 --> 00:08:22,240 Almost all will perish. 97 00:08:28,240 --> 00:08:31,600 But one cell is different. 98 00:08:32,920 --> 00:08:39,440 Within this tiny speck lies the future of all living things. 99 00:08:41,560 --> 00:08:43,480 It's a speck with a name. 100 00:08:44,880 --> 00:08:50,056 Meet LUCA, the ultimate survivor. 101 00:08:50,080 --> 00:08:55,456 The great-great-great times a billion grandparent of you, 102 00:08:55,480 --> 00:09:00,440 the elephant, and every other living thing on Earth. 103 00:09:20,400 --> 00:09:25,976 LUCA stands for Last Universal Common Ancestor. 104 00:09:26,000 --> 00:09:30,176 So, let's just think about this for a moment, because it was this 105 00:09:30,200 --> 00:09:34,256 single-celled organism, floating around in a world entirely 106 00:09:34,280 --> 00:09:40,776 alien to our own, which gave rise to every living thing on our planet. 107 00:09:40,800 --> 00:09:44,936 That's me, that's you, that's all the animals, all the plants, 108 00:09:44,960 --> 00:09:48,496 all the fungi, all the bacteria, everything! 109 00:09:48,520 --> 00:09:51,056 So, LUCA isn't just a clever acronym, 110 00:09:51,080 --> 00:09:53,416 something out of a biology class. 111 00:09:53,440 --> 00:09:59,056 LUCA defines the point where the story of life as we know it 112 00:09:59,080 --> 00:10:00,120 truly began. 113 00:10:06,080 --> 00:10:08,840 There are no fossils of LUCA... 114 00:10:11,000 --> 00:10:14,136 but because all living things have DNA 115 00:10:14,160 --> 00:10:19,400 and use the same genetic code, we know there must be a shared origin. 116 00:10:23,120 --> 00:10:24,576 Look at that. 117 00:10:24,600 --> 00:10:28,056 But why did LUCA and its descendants survive... 118 00:10:28,080 --> 00:10:32,216 Ooh! when trillions of others vanished? 119 00:10:32,240 --> 00:10:34,800 That's actually starting to burn my hand. 120 00:10:36,120 --> 00:10:40,600 Clues can be found in the Earth's most extreme places. 121 00:10:42,240 --> 00:10:45,440 I want to take my hand out of there. That's how hot it is. 122 00:10:49,920 --> 00:10:54,120 With alkaline water up to 86 degrees Centigrade... 123 00:10:57,320 --> 00:11:01,680 these are the sort of hostile conditions LUCA may have endured. 124 00:11:03,480 --> 00:11:05,056 But nevertheless, look. 125 00:11:05,080 --> 00:11:08,120 Life is tolerating it all round here. 126 00:11:14,040 --> 00:11:17,376 I know what you're thinking, this doesn't look like much, 127 00:11:17,400 --> 00:11:22,176 and certainly compared to us, this is pretty simple stuff. 128 00:11:22,200 --> 00:11:24,536 But I've got to tell you, it's not. 129 00:11:24,560 --> 00:11:27,456 The cells in here are amongst the most complex 130 00:11:27,480 --> 00:11:30,136 things in the known universe. 131 00:11:30,160 --> 00:11:33,776 Each one of these cells is generating energy, 132 00:11:33,800 --> 00:11:36,136 distributing that energy, dealing with waste. 133 00:11:36,160 --> 00:11:40,816 It's sensitive to its environment, it's reproducing. 134 00:11:40,840 --> 00:11:44,736 Every one of these cells is more complex than any machine 135 00:11:44,760 --> 00:11:46,880 ever made by any human. 136 00:11:49,040 --> 00:11:54,480 Just like these cells, LUCA was complex, robust, resilient... 137 00:11:55,880 --> 00:11:59,520 which may have helped it cling on against the odds. 138 00:12:01,080 --> 00:12:07,016 Now, we know that Luca wasn't the first cell and that it lived amongst 139 00:12:07,040 --> 00:12:11,456 other cells, but what made it special is that it didn't just live, 140 00:12:11,480 --> 00:12:14,496 it thrived, it survived. 141 00:12:14,520 --> 00:12:17,256 That little bubble of chemicals, 142 00:12:17,280 --> 00:12:20,240 formed in chaos billions of years ago. 143 00:12:26,720 --> 00:12:31,000 LUCA was the little cell that could. 144 00:12:35,840 --> 00:12:37,736 Plucky? Yes. 145 00:12:37,760 --> 00:12:40,600 Lucky? Almost certainly... 146 00:12:42,520 --> 00:12:46,840 but it also has life's greatest survival trick. 147 00:13:00,720 --> 00:13:03,640 LUCA can copy itself. 148 00:13:04,960 --> 00:13:07,440 Well enough to keep its genetic line going... 149 00:13:09,680 --> 00:13:13,640 but not so perfectly that every copy is identical. 150 00:13:16,600 --> 00:13:21,496 With every new generation, tiny errors, mutations, 151 00:13:21,520 --> 00:13:22,960 creep into its DNA. 152 00:13:25,720 --> 00:13:31,600 And yet these so-called mistakes fuel evolution. 153 00:13:34,000 --> 00:13:38,360 The story of our modern, living world has begun. 154 00:13:42,880 --> 00:13:45,480 Now it's time to hit fast forward. 155 00:13:48,360 --> 00:13:51,696 I mean, you can't cover four billion years of evolution without 156 00:13:51,720 --> 00:13:53,280 skipping some chapters. 157 00:13:55,960 --> 00:13:58,096 Generation after generation, 158 00:13:58,120 --> 00:14:02,240 little mistakes lead to entirely new life forms. 159 00:14:04,200 --> 00:14:09,760 Some cells begin to capture the sunlight - the ancestors of plants. 160 00:14:12,360 --> 00:14:17,360 Others would adapt to feed on decay - fungi. 161 00:14:22,600 --> 00:14:28,280 Many stay small and simple - the hidden world of microbes. 162 00:14:33,600 --> 00:14:36,256 But the cells that would give rise to the elephant 163 00:14:36,280 --> 00:14:37,960 take a very different path... 164 00:14:41,800 --> 00:14:45,360 three and a half billion years after LUCA... 165 00:14:48,000 --> 00:14:51,320 when the Earth is in a deep freeze. 166 00:15:04,600 --> 00:15:09,696 This is a period of intense global cooling. 167 00:15:09,720 --> 00:15:15,360 Ice grips the planet, and food webs are collapsing. 168 00:15:17,760 --> 00:15:21,216 But somewhere in the cold and dark, 169 00:15:21,240 --> 00:15:25,840 one hungry cell is about to change everything. 170 00:15:37,160 --> 00:15:41,736 The need to feed is one of the great driving forces of evolution. 171 00:15:41,760 --> 00:15:45,136 Any creature that can find its food more efficiently is more 172 00:15:45,160 --> 00:15:49,616 likely to survive and pass its genes into the next generation, 173 00:15:49,640 --> 00:15:54,816 as was the case over 600 million years ago 174 00:15:54,840 --> 00:15:59,016 when a single cell was on the verge of a breakthrough, 175 00:15:59,040 --> 00:16:01,936 a breakthrough that would lead to the incredible 176 00:16:01,960 --> 00:16:05,880 diversity of almost all animal life to come. 177 00:16:13,440 --> 00:16:16,560 Meet the ancient ancestor of the elephant... 178 00:16:17,560 --> 00:16:20,600 indeed of all animal kind. 179 00:16:28,720 --> 00:16:33,040 Urchoanozoan now has mitochondria for energy... 180 00:16:35,440 --> 00:16:37,360 a nucleus for control... 181 00:16:40,680 --> 00:16:43,400 and a tail-like flagellum to move. 182 00:16:46,560 --> 00:16:49,080 But one thing hasn't changed... 183 00:16:51,600 --> 00:16:54,280 this cell is still tiny... 184 00:16:56,600 --> 00:16:59,560 just 100th of a millimetre across. 185 00:17:04,720 --> 00:17:08,040 It's a small cell with a big problem. 186 00:17:10,280 --> 00:17:13,320 Food is brutally scarce. 187 00:17:16,560 --> 00:17:22,880 And that cell's ancient hunger may have set life on a new course. 188 00:17:24,960 --> 00:17:30,040 And you can see how, thanks to a remarkable creature alive today. 189 00:17:34,800 --> 00:17:36,216 {\an8}You might be wondering, what have 190 00:17:36,240 --> 00:17:39,376 a mass of insects like this got 191 00:17:39,400 --> 00:17:43,176 to do with an ancient single-celled organism? 192 00:17:43,200 --> 00:17:47,976 Well, the twist is that in the quest for food, 193 00:17:48,000 --> 00:17:51,320 they both came up with a similar solution... 194 00:17:52,840 --> 00:17:55,080 and it's down to numbers. 195 00:17:57,600 --> 00:18:01,016 You see, single ants are not very good 196 00:18:01,040 --> 00:18:05,776 when it comes to overwhelming prey. 197 00:18:05,800 --> 00:18:08,936 They're simply too small, they don't have the strength. 198 00:18:08,960 --> 00:18:14,000 So, what they've done is turn into a mass killing machine. 199 00:18:16,640 --> 00:18:21,056 Each one of the individuals has become a cog in that machine, 200 00:18:21,080 --> 00:18:24,016 and this means that they're far more efficient 201 00:18:24,040 --> 00:18:28,856 when it comes to handling whatever they're going to eat. 202 00:18:28,880 --> 00:18:31,040 Ow! It's all right. 203 00:18:33,560 --> 00:18:37,600 These ants act as one giant organism... 204 00:18:40,640 --> 00:18:44,760 overwhelming their meals with sheer force of numbers... 205 00:18:47,640 --> 00:18:51,960 and when they swarm, almost anything is on the menu. 206 00:18:54,040 --> 00:18:57,576 Crickets, caterpillars, or, if they're wounded, 207 00:18:57,600 --> 00:19:04,056 even chickens, goats and pigs and, by the feel of it, even a Packham! 208 00:19:04,080 --> 00:19:08,936 And there's the parallel with those ancient single-celled organisms, 209 00:19:08,960 --> 00:19:13,936 because they were about to adopt a similar technique which would 210 00:19:13,960 --> 00:19:15,400 change the world... 211 00:19:16,440 --> 00:19:17,976 forever. 212 00:19:18,000 --> 00:19:20,336 Oh, my goodness! 213 00:19:20,360 --> 00:19:23,976 My world's been changed forever, I think, to be quite honest with you. 214 00:19:24,000 --> 00:19:27,776 There are some of them in places that you won't be filming them. 215 00:19:27,800 --> 00:19:29,120 Get off! 216 00:19:33,280 --> 00:19:36,536 Over 600 million years ago, 217 00:19:36,560 --> 00:19:40,600 Urchoanozoan is about to do something revolutionary. 218 00:19:45,480 --> 00:19:49,400 Its surface is coated with sticky molecules... 219 00:19:53,200 --> 00:19:55,280 and when the time comes to divide... 220 00:19:57,200 --> 00:20:00,800 instead of floating off to live independent lives... 221 00:20:03,200 --> 00:20:06,080 the two remain stuck together. 222 00:20:09,560 --> 00:20:11,480 They continue to divide. 223 00:20:13,600 --> 00:20:16,280 More and more cells stick together... 224 00:20:18,280 --> 00:20:19,320 until... 225 00:20:20,640 --> 00:20:23,280 a vast alliance forms. 226 00:20:30,560 --> 00:20:32,720 Dubbed the Death Star... 227 00:20:34,960 --> 00:20:38,400 it's 100 larger than a single cell... 228 00:20:43,160 --> 00:20:46,840 and it has something of the dark side to it. 229 00:20:55,680 --> 00:20:58,096 When the all the flagella wiggle, 230 00:20:58,120 --> 00:21:00,400 they create stronger water currents... 231 00:21:04,360 --> 00:21:08,840 drawing in bacteria so the Death Star can feed. 232 00:21:12,720 --> 00:21:16,880 From cells sticking together came a new way of living. 233 00:21:18,440 --> 00:21:22,520 A multicellular organism is formed. 234 00:21:27,600 --> 00:21:31,376 Over the next 100 million years, 235 00:21:31,400 --> 00:21:34,640 the Death Star's descendants continue to grow... 236 00:21:36,960 --> 00:21:39,616 not just in size, 237 00:21:39,640 --> 00:21:41,160 but in complexity... 238 00:21:43,320 --> 00:21:46,800 as individual cells begin to specialise... 239 00:21:50,400 --> 00:21:54,640 until something truly revolutionary emerges... 240 00:21:57,600 --> 00:22:00,120 the first bodies on Earth. 241 00:22:11,320 --> 00:22:17,696 The oceans have now warmed and they're full of life forms. 242 00:22:17,720 --> 00:22:22,880 And lurking among them is the ancestor of the elephant. 243 00:22:33,840 --> 00:22:36,440 No trunk, no tusks... 244 00:22:38,120 --> 00:22:42,016 just a worm, three millimetres long, 245 00:22:42,040 --> 00:22:45,280 dragging itself across the seafloor. 246 00:22:48,000 --> 00:22:49,896 Evolution gave it a body, 247 00:22:49,920 --> 00:22:54,520 but one so small and simple you'd barely notice it. 248 00:23:01,920 --> 00:23:04,016 Building something bigger 249 00:23:04,040 --> 00:23:08,960 and more complex would require one vital ingredient... 250 00:23:10,120 --> 00:23:11,616 oxygen. 251 00:23:11,640 --> 00:23:16,376 Inside every cell in our body a slow, controlled burn is happening. 252 00:23:16,400 --> 00:23:19,016 Not with flames, of course, that would be concerning. 253 00:23:19,040 --> 00:23:23,280 But just like this fire, we need oxygen to release energy. 254 00:23:25,440 --> 00:23:29,040 Without it, we would simply sputter out and die. 255 00:23:32,520 --> 00:23:37,880 But for ancient animals, oxygen was largely out of reach. 256 00:23:42,760 --> 00:23:46,176 I've got some earthworms here, charming creatures, 257 00:23:46,200 --> 00:23:50,336 creatures of childhood, but not terribly sophisticated, 258 00:23:50,360 --> 00:23:52,456 particularly when it comes to breathing. 259 00:23:52,480 --> 00:23:54,656 You see, just like those early animals, 260 00:23:54,680 --> 00:23:56,600 they breathe through their skin. 261 00:23:57,680 --> 00:24:00,496 It's permeable, and as long as it's moist, 262 00:24:00,520 --> 00:24:03,376 they can extract oxygen from the air. 263 00:24:03,400 --> 00:24:07,936 But imagine you're living half a billion years ago. 264 00:24:07,960 --> 00:24:10,416 You're much smaller than this, and living at the bottom 265 00:24:10,440 --> 00:24:15,096 of an ocean where the oxygen supply is pitifully low. 266 00:24:15,120 --> 00:24:18,536 Life was small, life was slow, 267 00:24:18,560 --> 00:24:20,720 life was stuck. 268 00:24:25,400 --> 00:24:30,056 But this ancient worm has stumbled upon a new way to 269 00:24:30,080 --> 00:24:32,160 boost its oxygen supply. 270 00:24:36,640 --> 00:24:40,616 Tiny pores along its body, used to filter food, 271 00:24:40,640 --> 00:24:43,880 are now quietly adapting to a new role. 272 00:24:45,280 --> 00:24:49,480 They're able to draw in a fraction more oxygen... 273 00:24:51,480 --> 00:24:55,456 the beginning of a transformation that will allow creatures to 274 00:24:55,480 --> 00:24:57,960 grow bigger and stronger. 275 00:25:00,960 --> 00:25:04,720 And beating the competition is what it's all about. 276 00:25:11,120 --> 00:25:17,336 Generation by generation, tiny wrinkles inside the pores deepen, 277 00:25:17,360 --> 00:25:23,936 folding, twisting, meaning more surface area, 278 00:25:23,960 --> 00:25:25,360 more oxygen... 279 00:25:26,480 --> 00:25:31,080 until a whole new body part evolves. 280 00:25:39,200 --> 00:25:42,816 In tracing the evolution of the elephant or, for that matter, 281 00:25:42,840 --> 00:25:44,736 any other large land animal, 282 00:25:44,760 --> 00:25:49,376 the appearance of gills is hardly an obvious landmark moment. 283 00:25:49,400 --> 00:25:51,776 After all, elephants aren't famed for 284 00:25:51,800 --> 00:25:54,616 their deep-sea diving capabilities. 285 00:25:54,640 --> 00:26:00,056 But the emergence of gills was more than a minor upgrade. 286 00:26:00,080 --> 00:26:03,160 It was an evolutionary quantum leap. 287 00:26:07,200 --> 00:26:10,136 This is the fossil of Yunnanozoon. 288 00:26:10,160 --> 00:26:14,016 It lived in the Cambrian around 500 million years ago. 289 00:26:14,040 --> 00:26:19,576 What is it? Well, it wasn't a worm, wasn't yet a fish, 290 00:26:19,600 --> 00:26:22,776 but what makes it interesting is this... 291 00:26:22,800 --> 00:26:25,976 You can see these feathery structures 292 00:26:26,000 --> 00:26:28,456 running down here in rows. 293 00:26:28,480 --> 00:26:32,256 Some scientists believe that this is the first evidence 294 00:26:32,280 --> 00:26:35,000 that we've discovered of gills. 295 00:26:37,440 --> 00:26:40,496 Intricate folds like these can radically increase 296 00:26:40,520 --> 00:26:43,640 the surface area that's in contact with water... 297 00:26:44,960 --> 00:26:49,720 giving the animal the potential to access much more oxygen. 298 00:26:51,480 --> 00:26:55,296 And, of course, more oxygen means more energy. 299 00:26:55,320 --> 00:26:59,456 That can mean bigger bodies, faster movement. 300 00:26:59,480 --> 00:27:04,296 This innovation set the stage, not just for fish, 301 00:27:04,320 --> 00:27:07,760 or for elephants, but also for you and I. 302 00:27:09,600 --> 00:27:13,096 We tend to think of gills as a fish thing, 303 00:27:13,120 --> 00:27:16,800 but once they were pretty much everyone's thing. 304 00:27:18,320 --> 00:27:19,360 Every amphibian... 305 00:27:21,120 --> 00:27:23,856 reptile, bird, 306 00:27:23,880 --> 00:27:28,920 every mammal alive today descended from ancestors with gills. 307 00:27:31,200 --> 00:27:35,656 So, if gills were such a good idea, 308 00:27:35,680 --> 00:27:38,680 why did so many of us ditch them? 309 00:27:46,960 --> 00:27:52,120 Well, inside this fish is a clue to one of evolution's boldest leaps. 310 00:27:54,960 --> 00:27:58,240 Look at this extraordinary animal. 311 00:27:59,480 --> 00:28:06,536 This is protopterus aethiopicus and it's no ordinary fish. 312 00:28:06,560 --> 00:28:09,216 I mean, superficially it looks like an eel. 313 00:28:09,240 --> 00:28:13,056 It's got this long dorsal fin running all the way 314 00:28:13,080 --> 00:28:16,136 back down to this very spatulate tail here. 315 00:28:16,160 --> 00:28:19,376 Beautiful marbling, but look... 316 00:28:19,400 --> 00:28:21,936 Look at these wiggly limbs that are emerging. 317 00:28:21,960 --> 00:28:26,720 Two at the front here, and two more at the back. 318 00:28:31,680 --> 00:28:35,000 Frankly, what a weird-looking animal! 319 00:28:36,320 --> 00:28:38,616 But I'm dodging the big issue. 320 00:28:38,640 --> 00:28:43,896 What makes it special is that it can live in very stagnant water, 321 00:28:43,920 --> 00:28:46,576 water which is almost devoid of oxygen, 322 00:28:46,600 --> 00:28:50,696 and it can do that because it's a fish with a secret. 323 00:28:50,720 --> 00:28:53,656 Now, it is very, very slimy... 324 00:28:53,680 --> 00:28:55,736 If I can try and pick it up... 325 00:28:55,760 --> 00:28:59,216 I've got to watch my fingers, because it's well-armed 326 00:28:59,240 --> 00:29:01,856 with powerful, crushing teeth. 327 00:29:01,880 --> 00:29:04,736 Whoop! Come on. 328 00:29:04,760 --> 00:29:06,576 What a slippery customer. 329 00:29:06,600 --> 00:29:08,696 I just want you to be able to see its mouth, 330 00:29:08,720 --> 00:29:11,696 because it's through that mouth that it's able to draw 331 00:29:11,720 --> 00:29:17,296 in deliberately deep gulps of air, into a blood vessel lined sac 332 00:29:17,320 --> 00:29:20,536 where the oxygen can diffuse 333 00:29:20,560 --> 00:29:23,280 directly into its circulatory system. 334 00:29:25,880 --> 00:29:26,920 There! 335 00:29:29,560 --> 00:29:33,296 Protopterus aethiopicus, that's its scientific name, 336 00:29:33,320 --> 00:29:36,640 but that adaptation gives it its common name. 337 00:29:38,040 --> 00:29:44,720 This is not a fish out of water, so much as a lungfish on land. 338 00:29:50,680 --> 00:29:56,456 This air-gulping ability first evolved in fish 400 million 339 00:29:56,480 --> 00:30:02,216 years ago, as a simple backup plan for low oxygen water. 340 00:30:02,240 --> 00:30:07,440 But lungs would become key to one of evolution's giant leaps... 341 00:30:09,760 --> 00:30:11,960 the leap on to land. 342 00:30:15,720 --> 00:30:20,920 We're jumping through time again, a mere 300 million years. 343 00:30:24,240 --> 00:30:27,040 As animals ventured into new territories... 344 00:30:29,120 --> 00:30:33,080 limbs evolved, gills disappeared... 345 00:30:35,720 --> 00:30:37,680 bodies transformed. 346 00:30:40,560 --> 00:30:43,040 But we're picking up the elephant's story... 347 00:30:46,440 --> 00:30:48,920 {\an8}...at an evolutionary crossroads. 348 00:31:02,680 --> 00:31:04,896 In the age of the dinosaurs, 349 00:31:04,920 --> 00:31:08,040 life had gone truly XXL. 350 00:31:09,440 --> 00:31:12,680 The largest animals to ever walk the Earth. 351 00:31:19,640 --> 00:31:24,480 But the ancestor of the elephant has stayed stubbornly small. 352 00:31:30,040 --> 00:31:34,360 This tiny fuzzball is an early Afrotherian. 353 00:31:38,240 --> 00:31:42,416 It's got a long way to go before it can tower over the Savannah, 354 00:31:42,440 --> 00:31:46,200 but its small size is about to pay off. 355 00:31:49,960 --> 00:31:52,840 A rather large lump of rock is coming. 356 00:31:55,240 --> 00:31:58,640 Time's up for the giant dinosaurs. 357 00:32:00,120 --> 00:32:04,296 Mass extinction events don't go well for large animals. 358 00:32:04,320 --> 00:32:06,656 They need too much food when there's not much about, 359 00:32:06,680 --> 00:32:08,496 they're slow to reproduce, 360 00:32:08,520 --> 00:32:11,456 they simply can't bounce back quick enough. 361 00:32:11,480 --> 00:32:15,536 In order to survive, you need to be resourceful, adaptable, 362 00:32:15,560 --> 00:32:18,936 but above everything else, you need to be small. 363 00:32:18,960 --> 00:32:21,816 A bit like this little chap here. 364 00:32:21,840 --> 00:32:24,336 Where is he? Here he is. 365 00:32:24,360 --> 00:32:26,056 Look at that. 366 00:32:26,080 --> 00:32:29,776 That is a tree hyrax. 367 00:32:29,800 --> 00:32:31,896 It's about four or five months old. 368 00:32:31,920 --> 00:32:33,920 What a little beauty! 369 00:32:35,120 --> 00:32:38,856 This tree hyrax is a hand-reared orphan, 370 00:32:38,880 --> 00:32:42,896 allowing us to get an insight into what the elephant might have 371 00:32:42,920 --> 00:32:45,400 looked like before it bulked up... 372 00:32:46,720 --> 00:32:49,056 because, believe it or not, 373 00:32:49,080 --> 00:32:53,960 the hyrax is one of the elephant's closest living relatives. 374 00:32:55,640 --> 00:32:59,400 OK, he's coming, albeit slowly. Come on. 375 00:33:05,200 --> 00:33:06,776 What about that? 376 00:33:06,800 --> 00:33:10,576 I'm tempted to use the "c-word". I mean, he's undeniably cute. 377 00:33:10,600 --> 00:33:12,320 Look at the size of those eyes. 378 00:33:14,200 --> 00:33:16,656 After the asteroid impact, it would 379 00:33:16,680 --> 00:33:20,936 have been mammals of this size that were left roaming the Earth. 380 00:33:20,960 --> 00:33:24,696 All of the big species would have been wiped out completely. 381 00:33:24,720 --> 00:33:26,736 Hey, come on. 382 00:33:26,760 --> 00:33:28,120 Mind your footing. 383 00:33:32,920 --> 00:33:35,816 And you can see that it's retained some of the characteristics 384 00:33:35,840 --> 00:33:37,496 that helped them survive. 385 00:33:37,520 --> 00:33:40,456 It's nimble, it's cautious, undeniably, 386 00:33:40,480 --> 00:33:43,040 and it knows how to stay out of trouble. 387 00:33:44,040 --> 00:33:48,016 But, you know, that extinction event wasn't all about devastation. 388 00:33:48,040 --> 00:33:51,656 It also offered up a landscape of opportunity, 389 00:33:51,680 --> 00:33:55,440 a complete continent ripe for repopulation. 390 00:34:01,240 --> 00:34:03,760 With no giant dinosaurs for competition... 391 00:34:05,040 --> 00:34:10,560 Africa was an empty stage for evolution to run riot. 392 00:34:12,400 --> 00:34:15,600 The plants waste no time bouncing back. 393 00:34:18,280 --> 00:34:22,840 But the ancestor of the elephant remains small and furry. 394 00:34:24,000 --> 00:34:27,960 To get big, it needs food and lots of it. 395 00:34:29,440 --> 00:34:33,176 But the hard part isn't finding dinner. 396 00:34:33,200 --> 00:34:34,840 It's eating it. 397 00:34:43,440 --> 00:34:45,656 Plants must be easy to eat, right? 398 00:34:45,680 --> 00:34:48,056 After all, they can't run away, 399 00:34:48,080 --> 00:34:50,920 they can't fight back and they are everywhere. 400 00:34:52,080 --> 00:34:54,936 Well, not exactly, because obviously, 401 00:34:54,960 --> 00:34:57,096 plants don't want to be eaten. 402 00:34:57,120 --> 00:35:00,856 So, whilst they can't fight or claw their way out of trouble, 403 00:35:00,880 --> 00:35:04,776 they have come up with a formidable range of defences, which 404 00:35:04,800 --> 00:35:09,800 means that all of this greenery here is almost impossible to eat. 405 00:35:12,640 --> 00:35:18,056 For the ancestors of elephants, plants posed a serious challenge, 406 00:35:18,080 --> 00:35:22,840 not just because of thorns or toxins, but what they're made of. 407 00:35:23,840 --> 00:35:27,616 Even modern mammals struggle to digest them. 408 00:35:27,640 --> 00:35:29,040 Whose poo? 409 00:35:35,440 --> 00:35:40,416 Well, those of you with horses and ponies will probably get this. 410 00:35:40,440 --> 00:35:43,360 This is zebra poo. 411 00:35:44,760 --> 00:35:45,896 Look at that. 412 00:35:45,920 --> 00:35:48,336 We don't have too much time to admire it from the outside, 413 00:35:48,360 --> 00:35:50,816 let's delve in straight away. 414 00:35:50,840 --> 00:35:54,056 If I take this piece here, look at that! 415 00:35:54,080 --> 00:35:57,816 It looks like grass clippings. 416 00:35:57,840 --> 00:36:01,496 So, this has been nibbled, it's been munched, 417 00:36:01,520 --> 00:36:04,496 it's gone through the stomach, all the way through the gut of the 418 00:36:04,520 --> 00:36:09,496 zebra, and yet it's barely digested, and that's because the bulk 419 00:36:09,520 --> 00:36:13,016 of the material that you can see here is something called cellulose. 420 00:36:13,040 --> 00:36:17,336 It's the tough stuff that gives plants their strength and rigidity. 421 00:36:17,360 --> 00:36:18,856 But think about it. 422 00:36:18,880 --> 00:36:21,616 If a contemporary, complex, 423 00:36:21,640 --> 00:36:25,736 specialised herbivore like a zebra can't properly digest this 424 00:36:25,760 --> 00:36:30,400 stuff, what chance would those early mammals have? 425 00:36:41,240 --> 00:36:45,976 In truth, we are not certain whether the ancestors of the elephant 426 00:36:46,000 --> 00:36:51,280 made the leap to plant eating before or after the extinction event. 427 00:36:53,000 --> 00:36:54,600 The fossil record is patchy... 428 00:37:03,880 --> 00:37:06,616 but we do know the leap happened 429 00:37:06,640 --> 00:37:08,920 thanks to an unlikely alliance... 430 00:37:16,480 --> 00:37:18,400 Not with the bugs it was hunting. 431 00:37:19,560 --> 00:37:22,416 With something much smaller. 432 00:37:22,440 --> 00:37:25,856 You see, inside the elephant's ancestor, 433 00:37:25,880 --> 00:37:30,800 an invisible army of single-celled microbes is assembling. 434 00:37:32,600 --> 00:37:34,416 It's not an invasion, 435 00:37:34,440 --> 00:37:38,040 it's the start of a vital partnership. 436 00:37:40,840 --> 00:37:44,976 My goodness! Who says size is not important? 437 00:37:45,000 --> 00:37:48,176 This is not a termite mound, it's a termite monument! 438 00:37:48,200 --> 00:37:51,336 It's got to be five metres tall! 439 00:37:51,360 --> 00:37:55,616 Termites are famous for eating wood and other plant material, 440 00:37:55,640 --> 00:37:58,816 but in truth, that's not the whole story. 441 00:37:58,840 --> 00:38:02,840 They do the chewing, it's other organisms that do the digesting. 442 00:38:13,280 --> 00:38:18,520 Inside termite mounds, we find one of nature's strangest team-ups. 443 00:38:23,440 --> 00:38:26,256 Now, Chris Packham, a bloke who loves animals, 444 00:38:26,280 --> 00:38:29,496 why is he smashing up a termite mound? 445 00:38:29,520 --> 00:38:31,296 Well, I've thought long and hard about this. 446 00:38:31,320 --> 00:38:34,016 Firstly, they're extraordinarily resilient animals, 447 00:38:34,040 --> 00:38:36,816 they'll rebuild this really quickly. 448 00:38:36,840 --> 00:38:39,976 And the second thing is that every night, all over here, 449 00:38:40,000 --> 00:38:41,736 animals will be breaking into them. 450 00:38:41,760 --> 00:38:44,856 Just consider me the human aardvark. 451 00:38:44,880 --> 00:38:49,536 Besides, what I'm looking for is just under the surface. 452 00:38:49,560 --> 00:38:53,976 There are plenty of termites here, but I'm looking for something else. 453 00:38:54,000 --> 00:38:55,656 Ah! 454 00:38:55,680 --> 00:38:58,096 Another life-form lives here. 455 00:38:58,120 --> 00:38:59,336 I think this is it. 456 00:38:59,360 --> 00:39:01,656 Small, silent... 457 00:39:01,680 --> 00:39:02,976 Oh, yes, it is! 458 00:39:03,000 --> 00:39:04,816 and surprisingly useful. 459 00:39:04,840 --> 00:39:06,560 Look at that! 460 00:39:08,520 --> 00:39:12,136 That is termite fungal comb. 461 00:39:12,160 --> 00:39:15,416 {\an8}Now, the interesting thing about this fungus is that you can 462 00:39:15,440 --> 00:39:20,736 {\an8}only find it in termite mounds, nowhere else in the world. 463 00:39:20,760 --> 00:39:24,096 You see, the termites sort of farm it. 464 00:39:24,120 --> 00:39:27,056 They go out and they collect all that dead plant material, 465 00:39:27,080 --> 00:39:30,416 which they can't digest themselves, and then they come back 466 00:39:30,440 --> 00:39:32,696 and give it to the fungus. 467 00:39:32,720 --> 00:39:35,176 The fungus does digest the cellulose, 468 00:39:35,200 --> 00:39:39,776 and then turn it into substances which the termites can eat. 469 00:39:39,800 --> 00:39:41,080 What about that? 470 00:39:42,960 --> 00:39:46,600 And, of course, it's not just termites. 471 00:39:48,400 --> 00:39:53,056 Almost every plant-eater you can name has outsourced digestion 472 00:39:53,080 --> 00:39:54,320 to microbes. 473 00:39:57,120 --> 00:39:58,480 The only difference... 474 00:40:01,440 --> 00:40:07,440 most keep their microbial munchers safely tucked away inside their gut. 475 00:40:09,320 --> 00:40:13,856 Just as our bodies evolved, these sorts of partnerships evolved. 476 00:40:13,880 --> 00:40:16,576 It's difficult to know when, though, because we don't have any 477 00:40:16,600 --> 00:40:20,656 fossils of prehistoric animals with bacteria in their guts. 478 00:40:20,680 --> 00:40:24,216 But one thing we know for sure, and that is that over millions of years, 479 00:40:24,240 --> 00:40:28,416 many species have become dependent on these sorts of relationships. 480 00:40:28,440 --> 00:40:31,360 Without them, they would simply die. 481 00:40:39,680 --> 00:40:45,296 Sometimes, evolution's boldest moves aren't physical adaptations, 482 00:40:45,320 --> 00:40:47,240 they're partnerships. 483 00:40:48,440 --> 00:40:51,856 And now, thanks to its microbiome, 484 00:40:51,880 --> 00:40:54,640 it's a good time to sample the salad bar. 485 00:40:59,120 --> 00:41:01,896 Generation by generation, 486 00:41:01,920 --> 00:41:05,320 the gut balloons into a fermentation factory... 487 00:41:07,480 --> 00:41:10,456 filled with trillions upon trillions 488 00:41:10,480 --> 00:41:12,560 of plant-munching microbes. 489 00:41:19,680 --> 00:41:23,440 Just what you need for a plant-based diet. 490 00:41:30,320 --> 00:41:33,720 {\an8}And less than 20 million years later... 491 00:41:34,800 --> 00:41:40,000 we get this charming creature, an early proboscidean... 492 00:41:51,840 --> 00:41:55,880 now standing at a respectable one metre tall. 493 00:41:57,880 --> 00:42:01,560 But evolution has hit a problem of its own making. 494 00:42:03,280 --> 00:42:08,736 This proboscidean has elongated front teeth. 495 00:42:08,760 --> 00:42:10,880 Great for snagging vegetation... 496 00:42:17,040 --> 00:42:20,240 but big teeth can have drawbacks. 497 00:42:33,440 --> 00:42:36,280 This is the skull of an adult hyrax. 498 00:42:37,920 --> 00:42:43,296 It's got these massively oversized incisors there. 499 00:42:43,320 --> 00:42:45,216 What are those teeth for? 500 00:42:45,240 --> 00:42:48,816 Well, for seeing off predators, things like snakes and eagles, 501 00:42:48,840 --> 00:42:51,176 for displaying to other hyrax, and, if they cross the line, 502 00:42:51,200 --> 00:42:53,096 for seeing them off too. 503 00:42:53,120 --> 00:42:56,816 But we've got to remember that this is a herbivorous animal. 504 00:42:56,840 --> 00:43:00,360 How's it going to be nibbling leaves with these in the way? 505 00:43:02,240 --> 00:43:04,416 Well, it's going to struggle, and I can demonstrate 506 00:43:04,440 --> 00:43:10,576 that by adapting my own teeth with some elongated 507 00:43:10,600 --> 00:43:15,400 incisors of my own, and then try and tuck into a hyrax salad. 508 00:43:20,080 --> 00:43:23,216 Frankly, it's just not working. 509 00:43:23,240 --> 00:43:26,896 So, look, whilst big teeth can be impressive, and they certainly have 510 00:43:26,920 --> 00:43:30,856 their uses, if you're a herbivore, they can represent somewhat 511 00:43:30,880 --> 00:43:34,600 of an evolutionary challenge when it comes to grabbing your grub. 512 00:43:36,800 --> 00:43:40,216 Big front teeth come with trade-offs. 513 00:43:40,240 --> 00:43:44,520 For the hyrax, it means eating food through the side of the mouth. 514 00:43:47,600 --> 00:43:49,176 But with the proboscideans, 515 00:43:49,200 --> 00:43:51,680 evolution went down a different path. 516 00:43:57,600 --> 00:44:03,400 One individual was born with a slightly longer nose. 517 00:44:10,320 --> 00:44:13,840 It's the beginning of something special. 518 00:44:24,640 --> 00:44:26,896 There they are. There they are. 519 00:44:26,920 --> 00:44:29,976 To see what a flexible face can be capable of, 520 00:44:30,000 --> 00:44:33,040 we need a snout specialist. 521 00:44:34,720 --> 00:44:38,816 It's like being a lion, isn't it? Going out warthog hunting. 522 00:44:38,840 --> 00:44:41,656 Graceful? Not really. 523 00:44:41,680 --> 00:44:45,776 These are animals built for getting the job done. 524 00:44:45,800 --> 00:44:47,216 Warthogs... 525 00:44:47,240 --> 00:44:51,536 So ugly that they've crossed that line back into being beautiful. 526 00:44:51,560 --> 00:44:54,816 But we're not here for a beauty pageant, we're here for biology, 527 00:44:54,840 --> 00:44:59,760 so let's concentrate on their noses, a remarkable multi-tool. 528 00:45:02,600 --> 00:45:06,160 Warthog noses aren't just for sniffing snacks. 529 00:45:07,800 --> 00:45:11,800 They're for digging roots, and manoeuvring food into place. 530 00:45:15,440 --> 00:45:18,856 It's tough, it's not a delicate nose like ours. 531 00:45:18,880 --> 00:45:20,280 It's really robust. 532 00:45:21,920 --> 00:45:25,320 But even the best nose has its limits... 533 00:45:27,160 --> 00:45:32,656 especially when your food is on the ground, and your face isn't. 534 00:45:32,680 --> 00:45:34,896 The thing is, when you see them standing up, 535 00:45:34,920 --> 00:45:37,656 they've got quite long legs and short necks, 536 00:45:37,680 --> 00:45:41,496 so how do you get your nose down closer to the ground? 537 00:45:41,520 --> 00:45:44,936 Well, you do it like that - 538 00:45:44,960 --> 00:45:46,320 kneeling down. 539 00:45:50,840 --> 00:45:55,976 OK, so technically these are the creature's wrists, 540 00:45:56,000 --> 00:45:59,736 but either way, it's a brilliant example of evolution 541 00:45:59,760 --> 00:46:02,200 solving a problem of its own making. 542 00:46:04,840 --> 00:46:08,536 Certainly an effective solution, but it's not the only way 543 00:46:08,560 --> 00:46:12,176 of meeting that challenge of getting your nose closer to the ground. 544 00:46:12,200 --> 00:46:15,016 But there was a creature that lived millions of years ago that 545 00:46:15,040 --> 00:46:17,896 met the challenge in a completely different way 546 00:46:17,920 --> 00:46:21,456 and came up with something even more extraordinary. 547 00:46:21,480 --> 00:46:26,016 A tool, if you like, that it could use for eating, drinking, 548 00:46:26,040 --> 00:46:29,080 smelling and exploring the world. 549 00:46:34,200 --> 00:46:40,416 It would be the final flourish of an extraordinary evolutionary journey, 550 00:46:40,440 --> 00:46:45,976 a journey that started 4.2 billion years ago with 551 00:46:46,000 --> 00:46:49,560 a single cell that multiplied... 552 00:46:53,320 --> 00:46:55,360 and grew in complexity... 553 00:46:56,760 --> 00:46:58,000 gained a body... 554 00:46:59,640 --> 00:47:01,336 took a deep breath, 555 00:47:01,360 --> 00:47:03,120 and jumped onto land... 556 00:47:09,040 --> 00:47:14,800 before teaming up with microbes, giving it the guts to go vegan. 557 00:47:18,680 --> 00:47:22,480 And now, after countless generations... 558 00:47:23,920 --> 00:47:26,840 the nose gets longer... 559 00:47:29,600 --> 00:47:36,176 stretching down to the ground, giving better access to food, 560 00:47:36,200 --> 00:47:39,160 so the body continues to grow... 561 00:47:41,320 --> 00:47:46,016 until we get an animal of mindboggling complexity 562 00:47:46,040 --> 00:47:49,800 and size that you might just recognise. 563 00:47:58,000 --> 00:48:00,760 Meet Paleomastodon. 564 00:48:03,040 --> 00:48:06,376 {\an8}It's got the trunk, it's got the tusks. 565 00:48:06,400 --> 00:48:09,080 {\an8}Big ears? Still a work in progress... 566 00:48:11,320 --> 00:48:16,040 {\an8}...but it's a body shape we might finally call an elephant. 567 00:48:20,240 --> 00:48:22,760 And evolution didn't stop there. 568 00:48:26,520 --> 00:48:29,840 From creatures with bizarre jaw extensions... 569 00:48:34,400 --> 00:48:37,800 others with downward-curving tusks... 570 00:48:41,840 --> 00:48:47,560 and, of course, those icons of the Ice Age, the mammoths. 571 00:48:53,720 --> 00:48:57,320 Giant proboscideans once spanned the globe. 572 00:49:02,600 --> 00:49:08,016 Africa, Asia, Europe 573 00:49:08,040 --> 00:49:10,256 and South America. 574 00:49:10,280 --> 00:49:14,416 We have evidence of our relationship with proboscideans 575 00:49:14,440 --> 00:49:19,480 from all over the world, in the form of these carvings and paintings. 576 00:49:20,680 --> 00:49:24,616 These were not just creatures that were living in that landscape. 577 00:49:24,640 --> 00:49:27,736 We evolved alongside them. 578 00:49:27,760 --> 00:49:31,640 Our histories are uniquely intertwined. 579 00:49:35,880 --> 00:49:40,176 Some proboscideans were lost to natural climate change, 580 00:49:40,200 --> 00:49:45,320 but for others, it was the actions of our own ancestors. 581 00:49:50,200 --> 00:49:54,120 Today, just three species of proboscidean remain... 582 00:49:55,600 --> 00:50:00,296 each emerging within the last 10 million years - 583 00:50:00,320 --> 00:50:01,760 the Asian elephant... 584 00:50:05,280 --> 00:50:07,200 the African forest elephant... 585 00:50:10,760 --> 00:50:13,016 and, the biggest of them all, 586 00:50:13,040 --> 00:50:17,680 a grass-eating giant shaped on the open plains... 587 00:50:19,280 --> 00:50:21,760 the African savannah elephant. 588 00:50:27,080 --> 00:50:28,360 Remarkable! 589 00:50:30,000 --> 00:50:33,136 Aw, you're wonderful, aren't you? 590 00:50:33,160 --> 00:50:37,160 Let's take one last look at these incredible creatures. 591 00:50:40,480 --> 00:50:45,936 Made up of a million billion cells, powered by the largest lungs 592 00:50:45,960 --> 00:50:52,536 of any land animal, and in there, a gut coiled up, 20 metres long, 593 00:50:52,560 --> 00:50:57,776 packed full of microbes so it can digest all of this plant material. 594 00:50:57,800 --> 00:51:01,736 And then look at the front here, these tusks, and between them, 595 00:51:01,760 --> 00:51:05,936 this extraordinary, modified nose, its trunk, 596 00:51:05,960 --> 00:51:09,336 strong enough to pick up and carry a human, 597 00:51:09,360 --> 00:51:12,360 delicate enough to pick up a penny. 598 00:51:18,680 --> 00:51:22,856 The evolutionary journey that created the bizarre 599 00:51:22,880 --> 00:51:26,840 and beautiful elephant is just one story. 600 00:51:29,840 --> 00:51:34,016 Because, thanks to LUCA, that single-celled 601 00:51:34,040 --> 00:51:37,376 Last Universal Common Ancestor, 602 00:51:37,400 --> 00:51:41,760 we are all part of an ancient family. 603 00:51:42,920 --> 00:51:47,056 A family that may be bad at keeping in touch, 604 00:51:47,080 --> 00:51:50,576 and may be a little dysfunctional, 605 00:51:50,600 --> 00:51:55,000 but is always undeniably miraculous. 606 00:52:01,520 --> 00:52:02,816 Look at this! 607 00:52:02,840 --> 00:52:07,536 I'm literally leading a group of elephants through the forest. 608 00:52:07,560 --> 00:52:09,560 Who would have ever thought it? 609 00:52:12,200 --> 00:52:16,816 Every living thing, everything that's ever walked, 610 00:52:16,840 --> 00:52:24,296 swum or flown is all connected in that one tangled story, connected 611 00:52:24,320 --> 00:52:30,720 by that thread that runs through a four billion year tapestry of life. 612 00:52:34,720 --> 00:52:40,256 Evolution is messy, evolution's unpredictable and so grand, 613 00:52:40,280 --> 00:52:44,056 we're still really figuring out how it works, but there is one 614 00:52:44,080 --> 00:52:48,976 thing that we do know, and that is that given time and the resources, 615 00:52:49,000 --> 00:52:54,080 it comes up with creatures that are as remarkable as this. 616 00:52:56,800 --> 00:53:01,616 And we should cherish all life on Earth, not neglect it or 617 00:53:01,640 --> 00:53:06,896 destroy it, because evolution is wonderful, 618 00:53:06,920 --> 00:53:10,256 life is beautiful. 619 00:53:10,280 --> 00:53:12,536 ♪ You're such a 620 00:53:12,560 --> 00:53:15,080 ♪ Beautiful freak 621 00:53:16,360 --> 00:53:18,336 ♪ I wish there were 622 00:53:18,360 --> 00:53:20,960 ♪ More just like you... ♪ 623 00:53:32,080 --> 00:53:36,856 Next time - how the ostrich got the biggest egg on the planet... 624 00:53:36,880 --> 00:53:39,200 It's quite emotional, if I'm honest with you! 625 00:53:40,720 --> 00:53:43,400 a four billion year love story... 626 00:53:44,680 --> 00:53:46,160 from the first sex... 627 00:53:47,600 --> 00:53:49,480 to conquering the land. 628 00:53:53,160 --> 00:53:55,400 An incredible journey of flirting... 629 00:53:57,040 --> 00:53:58,456 feathers 630 00:53:58,480 --> 00:54:00,240 and fornication... 631 00:54:01,480 --> 00:54:02,896 giving rise... 632 00:54:02,920 --> 00:54:04,816 Look at this! 633 00:54:04,840 --> 00:54:07,520 to one of the most extraordinary birds. 634 00:54:17,280 --> 00:54:18,736 But first, 635 00:54:18,760 --> 00:54:23,960 how do we know that all life on Earth has a common ancestor? 636 00:54:26,840 --> 00:54:31,816 For centuries, fossils have provided a window into the past, 637 00:54:31,840 --> 00:54:35,240 helping scientists reconstruct the tree of life. 638 00:54:36,400 --> 00:54:41,616 In the past, our understanding for how a fossil fits in this 639 00:54:41,640 --> 00:54:45,856 larger system of life on Earth was comparative anatomy, 640 00:54:45,880 --> 00:54:48,536 and it worked for a long time, and it was a beautiful tool. 641 00:54:48,560 --> 00:54:51,256 Scientists would look at what animals or other organisms 642 00:54:51,280 --> 00:54:53,496 had in common, or didn't have in common, 643 00:54:53,520 --> 00:54:56,296 to try to recreate their evolutionary relationships. 644 00:54:56,320 --> 00:54:58,056 I think one thing we have to bear in mind is 645 00:54:58,080 --> 00:55:00,616 when we look at fossils, we're looking at just the remains, 646 00:55:00,640 --> 00:55:02,936 what is left behind, and it's not always complete. 647 00:55:02,960 --> 00:55:05,656 So, it's like trying to reconstruct a hand from a fingerprint. 648 00:55:05,680 --> 00:55:08,720 - And we made lots of mistakes. - LAUGHS 649 00:55:11,520 --> 00:55:13,736 {\an8}But in the middle of the last century, 650 00:55:13,760 --> 00:55:16,736 {\an8}a discovery changed everything. 651 00:55:16,760 --> 00:55:19,816 The appearance of DNA really was a game-changer. 652 00:55:19,840 --> 00:55:23,496 We couldn't study the tree of life with just comparative anatomy. 653 00:55:23,520 --> 00:55:24,640 You need DNA. 654 00:55:27,600 --> 00:55:31,656 We can compare genes to each other, compare those gene sequences 655 00:55:31,680 --> 00:55:34,776 to each other, look at the letters that those genes contain, 656 00:55:34,800 --> 00:55:38,056 and use that information to try to figure out how different 657 00:55:38,080 --> 00:55:39,960 organisms are related to each other. 658 00:55:42,920 --> 00:55:47,216 By analysing DNA, scientists have discovered that some 659 00:55:47,240 --> 00:55:49,136 creatures that look very different 660 00:55:49,160 --> 00:55:52,056 {\an8}are actually closely related, 661 00:55:52,080 --> 00:55:54,720 {\an8}like the Afrotherian mammals. 662 00:55:58,240 --> 00:56:03,816 And it's also allowed us to trace the tree of life back further 663 00:56:03,840 --> 00:56:08,720 than ever before, all the way to its root. 664 00:56:10,400 --> 00:56:13,256 - - LUCA. LAUGHS 665 00:56:13,280 --> 00:56:16,480 The Last Universal Common Ancestor to all life on Earth. 666 00:56:17,760 --> 00:56:21,616 It's the last organism that we can point back and say, "This is 667 00:56:21,640 --> 00:56:25,936 "a relative of not only us, but bacteria and elephants and bananas." 668 00:56:25,960 --> 00:56:29,136 I love thinking of LUCA as being not just my 669 00:56:29,160 --> 00:56:31,976 great-great-great-great-great-great- whatever grandparent, 670 00:56:32,000 --> 00:56:35,440 but everybody's great-great-great-great-great- whatever grandparent. 671 00:56:36,680 --> 00:56:39,896 In a landmark study, scientists analysed 672 00:56:39,920 --> 00:56:44,656 the DNA of 700 different microbial species, searching 673 00:56:44,680 --> 00:56:48,600 for patterns that would help them reconstruct LUCA's genetic code. 674 00:56:49,680 --> 00:56:53,616 Our ability to sequence DNA really has unlocked our ability to 675 00:56:53,640 --> 00:56:57,696 look deep in time to 4 billion years ago 676 00:56:57,720 --> 00:57:00,136 and come to a better understanding of what 677 00:57:00,160 --> 00:57:03,080 our Last Universal Common Ancestor may have looked like. 678 00:57:05,280 --> 00:57:08,896 The study revealed that LUCA was likely to have had 679 00:57:08,920 --> 00:57:14,560 over 2,600 genes, making it surprisingly complex. 680 00:57:17,520 --> 00:57:20,056 So, it wasn't necessarily the first form of life. 681 00:57:20,080 --> 00:57:23,376 It almost certainly wasn't, but it's the one that got by. 682 00:57:23,400 --> 00:57:28,456 From that one spark, we see the origin of all the life that we 683 00:57:28,480 --> 00:57:30,880 see today in its incredible diversity. 684 00:57:36,440 --> 00:57:38,896 Realising that we all came from LUCA, 685 00:57:38,920 --> 00:57:44,496 the same seed of the tree of life, is really humbling to me. 686 00:57:44,520 --> 00:57:47,016 It's a way of thinking about the world 687 00:57:47,040 --> 00:57:49,776 in a much more connected way. 688 00:57:49,800 --> 00:57:51,400 We all came from the same place. 689 00:57:53,280 --> 00:57:57,976 We've not only expanded our understanding of the tree life, but 690 00:57:58,000 --> 00:58:01,760 it's changed our understanding of where we fit into the tree of life. 691 00:58:05,720 --> 00:58:09,296 Do you want to know how an elephant is related to a clownfish? 692 00:58:09,320 --> 00:58:13,616 Discover more in a poster from the Open University on the tree of life. 693 00:58:13,640 --> 00:58:17,600 To get your free copy, scan the QR code on screen, or ring... 694 00:58:21,200 --> 00:58:22,520 or visit...