1 00:00:03,600 --> 00:00:07,759 Speaker 1: We are the most complex creature on this planet, a 2 00:00:07,799 --> 00:00:11,439 big brain, two legged mammal. We've risen from the raw 3 00:00:11,519 --> 00:00:14,960 materials of the Earth to dominate and shape it. 4 00:00:18,760 --> 00:00:20,640 Speaker 2: Wind the clock backwards, and. 5 00:00:20,640 --> 00:00:22,920 Speaker 1: The story of how we got to be us is 6 00:00:22,960 --> 00:00:27,679 a puzzle that defies all logic. Through nearly four billion 7 00:00:27,760 --> 00:00:35,679 years of evolutionary twists and turns, disasters, stripe predators threatened 8 00:00:35,679 --> 00:00:41,880 to wipe us out. From rodent to reptile, we face 9 00:00:41,960 --> 00:00:47,079 extinction at every turn, from the land into the water, 10 00:00:47,759 --> 00:00:55,600 fighting to survive every step of the way, from fish 11 00:00:55,640 --> 00:00:57,399 to worm, back to the. 12 00:00:57,439 --> 00:00:58,719 Speaker 2: Very first spark. 13 00:00:58,399 --> 00:01:07,400 Speaker 1: Of life, to a single simple self. And this is 14 00:01:07,439 --> 00:01:12,920 the most extraordinary, improbable story ever told, the story of 15 00:01:13,040 --> 00:01:29,040 mankind rising four billion years ago. A ball of rock 16 00:01:29,120 --> 00:01:38,840 and dust spins in the frozen vacuum of space. This 17 00:01:38,959 --> 00:01:40,079 isn't Mars. 18 00:01:42,079 --> 00:01:49,120 Speaker 2: Or Venus. This hell is Earth. 19 00:01:53,079 --> 00:01:56,760 Speaker 1: This seething, lifeless mass of molten lava will become home 20 00:01:56,799 --> 00:02:10,639 to nearly nine million living species. But generating life from 21 00:02:10,680 --> 00:02:13,639 this will take a chain of events that defies the 22 00:02:13,719 --> 00:02:16,719 laws of probability. 23 00:02:17,960 --> 00:02:19,080 Speaker 2: There are many theories. 24 00:02:19,800 --> 00:02:25,199 Speaker 1: Nobody knows exactly our where life began, but it couldn't 25 00:02:25,240 --> 00:02:36,639 happen without water. Experts believe asteroids or commets delivered it. Here, 26 00:02:43,319 --> 00:02:55,000 the water is churning with chemicals and organic compounds. Lightning 27 00:02:55,039 --> 00:02:59,000 strikes the chemical soup at the right place and the 28 00:02:59,120 --> 00:03:04,360 right time. Billions of volts of electricity trigger a chain 29 00:03:04,400 --> 00:03:10,199 of improbable coincidences. The chemicals atoms join up in a 30 00:03:10,240 --> 00:03:18,840 precise sequence, creating a bundle of genetic material. These fragile 31 00:03:18,840 --> 00:03:25,360 genes don't stand a chance in this extreme environment, but 32 00:03:25,520 --> 00:03:29,599 love strikes again. A blob of oily material engulfs a 33 00:03:29,639 --> 00:03:37,439 single chain to create the first ever cell. Now, the 34 00:03:37,520 --> 00:03:43,919 genes send out messages, chemical instructions, and three point five 35 00:03:44,000 --> 00:03:49,360 billion years ago, they do something extraordinary. They copy themselves 36 00:03:49,960 --> 00:03:55,840 and the cell to create a perfect clone. This is 37 00:03:55,879 --> 00:04:02,159 the very first living thing. Every human, every animal, every bug, 38 00:04:02,800 --> 00:04:06,680 every plant can trace its origins to this single cell. 39 00:04:09,439 --> 00:04:13,360 The genes tell each cell to reproduce, guaranteeing their survival 40 00:04:13,759 --> 00:04:17,639 as they pass from one generation to the next. For 41 00:04:17,720 --> 00:04:22,519 two billion years, the only living things are simple single cells. 42 00:04:23,279 --> 00:04:29,399 But a random accident changes everything. Two cells merge, their 43 00:04:29,480 --> 00:04:36,439 genes combine. The merge cell clones itself. Its offspring contains 44 00:04:36,480 --> 00:04:41,439 genes from not one, but two cells, two parents. We 45 00:04:41,560 --> 00:04:56,319 call this accident sex. Sex introduces variation. Occasionally things go 46 00:04:56,399 --> 00:05:02,160 wrong as the cells reproduce, genes get deleted, duplicated. These 47 00:05:02,199 --> 00:05:09,360 cells are mutants. Mutations pile up, differences increase until the 48 00:05:09,360 --> 00:05:14,120 cells become so different their separate species. The tree of 49 00:05:14,199 --> 00:05:18,319 life branches out into billions of species, but only one 50 00:05:18,399 --> 00:05:26,879 will lead to us. Mutating and diversifying, spreading out through 51 00:05:26,879 --> 00:05:32,920 the oceans, getting bigger, more complex, until our ancestor is 52 00:05:32,959 --> 00:05:40,600 a three inch long water worm. This is US five 53 00:05:40,720 --> 00:05:52,040 hundred and fifty million years ago. Mutations create distinct male 54 00:05:52,120 --> 00:05:57,439 and female sexes. We produce more offspring, passing on more 55 00:05:57,519 --> 00:06:04,439 genes Mars and venus. Boy meets girl. 56 00:06:05,399 --> 00:06:06,639 Speaker 2: It all starts. 57 00:06:06,279 --> 00:06:13,920 Speaker 1: Here, but finding a partner is almost impossible When every 58 00:06:13,959 --> 00:06:22,480 living thing is blind in this sea of darkness. The 59 00:06:22,560 --> 00:06:28,800 ability to see will give us a critical advantage. Nature's 60 00:06:28,839 --> 00:06:33,399 most perfect innovation begins to take shape. A handful of 61 00:06:33,439 --> 00:06:38,160 skin cells mutate. Now we can tell dark from light, 62 00:06:38,920 --> 00:06:44,560 find more prey, dodge more predators. We live longer and 63 00:06:44,680 --> 00:06:50,040 produce more offspring. Soon, creatures with light sensitive cells dominate 64 00:06:50,120 --> 00:06:56,079 the population over countless generations. More mutations refine the cells. 65 00:06:57,639 --> 00:07:01,759 This is natural selection in action, the process that allows 66 00:07:01,800 --> 00:07:04,920 every living thing to adapt to the world, and that 67 00:07:05,040 --> 00:07:25,600 gives our ancestor eyes. We can see, and everything we 68 00:07:25,680 --> 00:07:33,720 can see is descended from that first single cell. But 69 00:07:33,800 --> 00:07:38,759 we need to make sense of what we're seeing behind 70 00:07:38,800 --> 00:07:42,319 our eyes A tiny collection of nerve cells clustered together. 71 00:07:43,360 --> 00:07:47,639 They're no bigger than a pinhead. One day this will 72 00:07:47,680 --> 00:07:53,040 be nature's most complex and mysterious organ. Five hundred and 73 00:07:53,079 --> 00:07:56,879 twenty one million years ago, this is the very first brain. 74 00:07:59,279 --> 00:08:04,519 We are a fish like creature called Milo Conmingia. Our 75 00:08:04,560 --> 00:08:13,600 brain can make simple decisions, process basic information, but we 76 00:08:13,680 --> 00:08:23,360 can't outwith or outrun this anoma Lacarus, the great white 77 00:08:23,480 --> 00:08:28,879 of the ancient oceans. O odds of extinction are far 78 00:08:28,959 --> 00:08:41,320 higher than survival. Of all the species that have ever lived, 79 00:08:41,840 --> 00:08:52,200 ninety nine percent of them are extinct, But a lucky 80 00:08:52,279 --> 00:09:10,080 roll of the genetic dice helps Milo. Tough enough, your jaws, 81 00:09:11,000 --> 00:09:15,360 your teeth. They exist because over four hundred million years ago, 82 00:09:15,799 --> 00:09:20,080 we face the wrath of a primeval monster. Jaws and 83 00:09:20,120 --> 00:09:25,919 teeth mean more food and a bigger, stronger body. Until 84 00:09:25,960 --> 00:09:29,519 three hundred and seventy five million years ago, we're a 85 00:09:29,559 --> 00:09:45,879 foot long armored fish. 86 00:09:45,960 --> 00:09:58,000 Speaker 2: We look invincible, but we're not. Now. 87 00:09:58,440 --> 00:10:11,600 Speaker 1: The choice is simple, get out his way or die. 88 00:10:14,279 --> 00:10:19,159 We're safe in the shallow water, or are we. The 89 00:10:19,240 --> 00:10:25,879 water's stagnant, there's not enough oxygen. Starved of oxygen, cells 90 00:10:25,879 --> 00:10:31,519 shut down, Toxic carbon dioxide saturates the blood. We can't 91 00:10:31,559 --> 00:10:36,399 go back, we can't stay here. There's only one place 92 00:10:36,639 --> 00:10:37,080 left for. 93 00:10:37,159 --> 00:10:37,679 Speaker 2: Us to go. 94 00:10:48,679 --> 00:10:52,120 Speaker 1: It takes over three billion years for our ancestor to 95 00:10:52,200 --> 00:10:58,600 evolve from a single cell to a foot long armored fish. 96 00:10:58,919 --> 00:11:06,159 Now our future looks bleak, but natural selection throws us 97 00:11:06,159 --> 00:11:12,960 a lifeline. Over millions of years, thousands of generations, our 98 00:11:13,000 --> 00:11:16,279 body adapts until we do something no fish has done before. 99 00:11:17,200 --> 00:11:17,559 Speaker 2: Breathe. 100 00:11:17,559 --> 00:11:30,080 Speaker 1: There the air travels into a new organ, a lung. 101 00:11:32,440 --> 00:11:36,679 Take a breath, and remember it's because a monster fish 102 00:11:36,759 --> 00:11:40,600 chased our ancestor into the stagnant water, forcing them to 103 00:11:40,679 --> 00:11:49,519 breathe air. We're in ichthyostega. We can breathe air or water, 104 00:11:50,600 --> 00:11:55,399 closing off our windpipe to switch between lungs and gills. Today, 105 00:11:55,440 --> 00:12:00,000 our gills are gone, but the mechanism remains, and sometimes 106 00:12:00,000 --> 00:12:07,559 times at spasms, giving us the hiccups three hundred and 107 00:12:07,679 --> 00:12:12,519 sixty five million years ago. We stick our head out 108 00:12:12,519 --> 00:12:13,039 of the water. 109 00:12:17,600 --> 00:12:18,759 Speaker 2: There's a swamp. 110 00:12:18,399 --> 00:12:24,320 Speaker 1: Behind us, paradise ahead. The choice is simple, but the 111 00:12:24,360 --> 00:12:31,039 consequences are immense. We pull ourselves out of the water 112 00:12:32,200 --> 00:12:42,120 and change the course of history. This is the moment 113 00:12:42,200 --> 00:12:45,639 we leave the water for a new life on land. 114 00:12:47,919 --> 00:13:00,320 But all this food comes at a price. The fierce 115 00:13:00,399 --> 00:13:06,360 sun dries out our skin, the hard terrain tears at 116 00:13:06,360 --> 00:13:13,399 our soft feet. Ichthyostega is a fish out of water. 117 00:13:16,799 --> 00:13:21,120 We dodged extinction in a stagnant swamp, only to slam 118 00:13:21,159 --> 00:13:32,120 straight into another deadly environment. Countless creatures perish, but natural 119 00:13:32,159 --> 00:13:41,360 selection helps our ancestor adapt. Thicker skin protects us from 120 00:13:41,399 --> 00:13:48,720 the sun, and tough claws that will one day become 121 00:13:48,840 --> 00:13:54,879 our fingernails help us move across the rough terrain until 122 00:13:55,399 --> 00:14:01,440 we're cassanaria. We've adapted to life on life, but our 123 00:14:01,480 --> 00:14:05,120 eggs haven't. They need a tough shell to stop them 124 00:14:05,200 --> 00:14:11,320 drying out in the sun. The problem is males can't 125 00:14:11,320 --> 00:14:14,799 fertilize an egg through a tough shell, but they can 126 00:14:14,840 --> 00:14:19,279 fertilize it before the shell forms inside the female's body. 127 00:14:21,240 --> 00:14:27,720 Sex as we know it starts here. The result is 128 00:14:27,759 --> 00:14:32,039 a masterpiece of evolution, an egg in a tough shell 129 00:14:32,759 --> 00:14:42,240 with all the nutrients the embryo needs sealed inside. Sex 130 00:14:42,320 --> 00:14:45,279 is the best way to increase genetic variety and keep 131 00:14:45,320 --> 00:14:53,919 our species alive. Thanks to sex, three hundred and forty 132 00:14:53,960 --> 00:14:58,039 million years ago, Casinaria becomes the first of our ancestors 133 00:14:58,320 --> 00:15:06,519 to live entirely on land. It's a new world, different 134 00:15:06,559 --> 00:15:10,519 from anything we've experienced up to now. We breathe air, 135 00:15:11,559 --> 00:15:15,440 support our own weight, and wrestle with an onslaught of 136 00:15:15,519 --> 00:15:24,120 new smells, sounds, sights, bombarded with information, our brains evolve. 137 00:15:27,440 --> 00:15:31,720 We're smart, and we need to be. From that first 138 00:15:31,720 --> 00:15:37,399 creature to set foot on land, millions of species have evolved. 139 00:15:38,559 --> 00:15:50,639 More competitors mean less food to go round. A mutation 140 00:15:50,879 --> 00:15:55,720 gives us bigger, more powerful jaw muscles. It's a critical advantage. 141 00:15:56,200 --> 00:16:13,320 We can eat more food faster, and it shows we're Varnops, 142 00:16:13,919 --> 00:16:24,559 a slab of pure meat eating power. This little creature 143 00:16:25,039 --> 00:16:40,519 is a proterosaurus wants a competitor. Now he's prey with 144 00:16:40,720 --> 00:16:52,279 Varyonops for an ancestor. Our success seems certain, but our 145 00:16:52,360 --> 00:16:56,159 story is a rollercoaster ride, and there's a big dip coming. 146 00:17:11,359 --> 00:17:12,559 Speaker 2: Two hundred and fifty. 147 00:17:12,319 --> 00:17:16,680 Speaker 1: Million years ago, thousands of miles away in Siberia, the 148 00:17:16,720 --> 00:17:25,000 Earth tears itself apart. A giant plume of magma surges 149 00:17:25,079 --> 00:17:29,440 up from deep inside the planet. Molten rock oozes through 150 00:17:29,480 --> 00:17:32,839 cracks in the Earth's crust, covering an area the size 151 00:17:32,880 --> 00:17:36,200 of the United States under a layer one thousand feet deep, 152 00:17:38,240 --> 00:17:44,119 and it continues for half a million years. Trillions of 153 00:17:44,160 --> 00:17:48,119 tons of noxious carbon dioxide trapped the Sun's heat inside 154 00:17:48,119 --> 00:17:56,440 the atmosphere, Temperatures soar to over one hundred degrees. Plants, 155 00:17:56,839 --> 00:18:02,240 the plant eaters, and eventually the meat eaters perish. Ninety 156 00:18:02,279 --> 00:18:06,799 five percent of all species die, only a tiny handful 157 00:18:06,920 --> 00:18:15,559 hang off among them, us and another species that will 158 00:18:15,559 --> 00:18:22,400 one day become the dinosaurs. As the fight for survival 159 00:18:22,440 --> 00:18:34,680 winds down, the battle for supremacy begins. Thirty million years 160 00:18:34,720 --> 00:18:38,039 since volcanic eruptions wiped out ninety five percent of all 161 00:18:38,079 --> 00:18:48,319 living things. When the eruptions struck, we look like a 162 00:18:48,400 --> 00:18:54,319 large lizard. Now we're a catsized creature covered in fur 163 00:18:55,000 --> 00:19:03,319 called ectininion. Imagine you've survived the apocalypse, and today is 164 00:19:03,359 --> 00:19:06,240 the day it's finally safe to venture out of hiding, 165 00:19:08,759 --> 00:19:09,720 you discover. 166 00:19:09,400 --> 00:19:13,039 Speaker 2: You're not alone. 167 00:19:14,839 --> 00:19:18,279 Speaker 1: The last thing you want to see is a dinosaur, 168 00:19:23,920 --> 00:19:29,920 a five foot tall Herrerasaurus. She evolved from one of 169 00:19:29,920 --> 00:19:35,119 the small reptiles that survived the mass extinction. Her ancestors 170 00:19:35,119 --> 00:19:39,039 adapted faster than ours, putting the dinosaurs ahead in the 171 00:19:39,079 --> 00:19:47,480 game and leaving us playing ketchup. This one's fast, strong, 172 00:19:48,680 --> 00:20:19,839 and hungry. We're staring down the barrel of an evolutionary gun. 173 00:20:22,640 --> 00:20:32,079 Our only hope natural selection. Over millions of years, we 174 00:20:32,200 --> 00:20:33,319 get smaller. 175 00:20:33,839 --> 00:20:35,039 Speaker 2: So we're harder to catch. 176 00:20:36,279 --> 00:20:40,759 Speaker 1: We become nocturnal, making us harder to see. 177 00:20:41,400 --> 00:20:42,599 Speaker 2: We're cold and scared. 178 00:20:43,960 --> 00:20:47,920 Speaker 1: Tiny muscles around the base of each hair contract making 179 00:20:47,960 --> 00:20:52,599 our fur stand on end, trapping air as insulation. That's 180 00:20:52,599 --> 00:21:01,480 why today, when we're cold or startled, we get goosebumps. 181 00:21:05,160 --> 00:21:09,400 Our senses sharpened so we can see here and smell 182 00:21:09,440 --> 00:21:23,079 a dinosaur before a dinosaur sees us. Inside our brain, 183 00:21:23,240 --> 00:21:29,039 a new structure evolves, the neocortex, the home of complex 184 00:21:29,119 --> 00:21:34,079 thought that allows us to analyze the situation and respond. 185 00:21:34,799 --> 00:21:38,480 It will one day give us the power to imagine, create, 186 00:21:39,359 --> 00:21:47,000 and communicate. Sixty six million years ago. We're Batadom, a 187 00:21:47,039 --> 00:21:50,319 two inch long, shrewd like creature living on our wits 188 00:21:50,480 --> 00:21:55,599 in the ancient forests of Montana. Humanity's future depends on 189 00:21:55,640 --> 00:22:02,359 Badadan's sharp senses and supercharged brains. If these fail, we 190 00:22:02,400 --> 00:22:36,119 may never exist. The dinosaurs may be the best thing 191 00:22:36,160 --> 00:22:42,200 that ever happened to us. Thanks to them, we have 192 00:22:42,279 --> 00:22:48,680 powerful senses and brilliant brains. Without them, we could still 193 00:22:48,720 --> 00:22:56,920 be laying eggs to protect our offspring from hungry dinosaurs. 194 00:22:57,519 --> 00:23:04,480 We evolved to give birth to live young. Instead of 195 00:23:04,559 --> 00:23:09,160 leaving them to fend for themselves, we nurture them with milk. 196 00:23:11,400 --> 00:23:11,759 Speaker 2: Sweat. 197 00:23:11,759 --> 00:23:18,680 Speaker 1: Glens evolved to become mammary glands. It's a major milestone 198 00:23:18,799 --> 00:23:22,440 in our journey from cell to human, the birth of 199 00:23:22,480 --> 00:23:26,039 a new kind of animal, one that will branch out 200 00:23:26,119 --> 00:23:30,200 into more than four thousand species, from the smallest mouse 201 00:23:30,640 --> 00:23:36,519 to the largest whale. To us, the mammals have arrived. 202 00:23:40,440 --> 00:23:46,680 The dinosaurs help shape who we are, but we lost 203 00:23:46,680 --> 00:23:58,640 the battle for supremacy. The dinosaur's reign for over one 204 00:23:58,720 --> 00:24:03,079 hundred and sixty five million years. Nothing can stop. 205 00:24:02,880 --> 00:24:16,759 Speaker 3: Them, or so it seems. 206 00:24:19,440 --> 00:24:25,240 Speaker 1: Montana, sixty five million years ago, an asteroid strikes eighteen 207 00:24:25,319 --> 00:24:38,640 hundred miles away off Mexico's Yucatan Peninsula. A small rat 208 00:24:38,759 --> 00:24:41,319 like mammal is about to face the fight of his life. 209 00:24:42,319 --> 00:24:51,359 Lose and humans may never exist. Pulverized rock and dust 210 00:24:51,559 --> 00:25:18,359 engulfed the entire planet, the only way out is to dig. 211 00:25:29,799 --> 00:25:32,200 Smoke and ash from the fires block out the sun. 212 00:25:33,319 --> 00:25:43,559 Temperatures plummet, vegetation dies. The local disaster becomes a global catastrophe. 213 00:25:44,000 --> 00:25:49,200 For the dinosaurs, it's a disaster. They're big creatures with 214 00:25:49,319 --> 00:26:00,640 big appetites, and now that's a big problem. As the 215 00:26:00,720 --> 00:26:08,039 mighty fall, the small rise to the top. Bugs tough 216 00:26:08,160 --> 00:26:11,880 enough to survive the worst catastrophe, gorge on the dead 217 00:26:11,960 --> 00:26:20,279 and decaying, and they make the perfect snack. Next time 218 00:26:20,319 --> 00:26:23,480 you're about to squash a bug, remember that we wouldn't 219 00:26:23,519 --> 00:26:29,799 be here without them. Sixty four million years ago, our 220 00:26:29,839 --> 00:26:34,400 bug eating ancestor is purgatorious, just under six inches long. 221 00:26:35,000 --> 00:26:37,720 This little creature and the rest of his mammal family 222 00:26:37,880 --> 00:26:43,559 are the unlikely inheritors of the dinosaur's crown. Mammals become 223 00:26:43,599 --> 00:26:49,720 the dominant animals on land. They spread out across the 224 00:26:49,759 --> 00:26:59,240 newly formed continents. Our future rests on their tiny shoulders 225 00:27:02,759 --> 00:27:06,480 from the ashes of destruction. New life begins to sprout. 226 00:27:11,720 --> 00:27:20,279 Sixty million years ago, fruit ripens on the trees, packed 227 00:27:20,319 --> 00:27:24,240 full of nutrients. The more fruit we eat, the longer 228 00:27:24,240 --> 00:27:28,119 we live. We leave solid ground for a new life 229 00:27:28,200 --> 00:27:39,839 in the trees. A new world demands a new body. 230 00:27:42,000 --> 00:27:45,680 We've come a long way from that first single cell. Now, 231 00:27:45,920 --> 00:27:52,720 at last, we're beginning to glimpse of family resemblance. We're 232 00:27:52,799 --> 00:27:55,920 alti at Lassius, one of the first members of a 233 00:27:55,960 --> 00:27:58,839 new group of mammals, the primates. 234 00:28:08,599 --> 00:28:10,359 Speaker 2: By fifty six million years. 235 00:28:10,119 --> 00:28:25,000 Speaker 1: Ago, we've adapted to our world, but that world is 236 00:28:25,039 --> 00:28:35,759 about to change again. Over ten million years, extreme temperature 237 00:28:35,799 --> 00:28:45,559 shifts ravage the forests. Forests gets smaller, food gets harder 238 00:28:45,559 --> 00:28:57,039 to reach. Natural selection intervenes again. Our tail shrinks back 239 00:28:57,079 --> 00:29:00,599 to the base of the spine, where it stays as 240 00:29:00,640 --> 00:29:04,599 the coccix, a reminder of our days spent leaping through 241 00:29:04,640 --> 00:29:16,240 the trees. Instead of leaping, we stretch, our arms grow 242 00:29:16,319 --> 00:29:28,079 long and flexible. Changing temperatures changed our ancestors and us forever, 243 00:29:29,319 --> 00:29:35,839 but the planets not finished yet. Deep underground, the African 244 00:29:35,880 --> 00:29:40,200 and Arabian plates pull apart the land between them drops 245 00:29:40,240 --> 00:29:45,519 to form the East African Rift Valley. Along its edge, 246 00:29:45,720 --> 00:29:48,559 a three and a half thousand mile long mountain shape 247 00:29:48,759 --> 00:29:55,079 rises up rains from the Indian Ocean, once watered all 248 00:29:55,119 --> 00:30:03,480 of Africa. Now the mountains block their path, The trees 249 00:30:03,519 --> 00:30:11,680 get even further apart, the food harder to reach. We're starving, desperate. 250 00:30:13,599 --> 00:30:16,880 Four point four million years ago. The will to survive 251 00:30:17,559 --> 00:30:20,079 that's driven us from a single cell in the ocean 252 00:30:20,680 --> 00:30:24,400 to a complex primate in the forests of Africa is 253 00:30:24,440 --> 00:30:29,319 about to make us do something extraordinary, something no primate 254 00:30:29,440 --> 00:30:45,440 has ever done before. After three billion years of evolution, 255 00:30:46,559 --> 00:30:52,880 we hit an evolutionary dead end. We are Artipithecus ramidus, 256 00:30:54,079 --> 00:30:58,039 four feet tall at eighty pounds, with a brain the 257 00:30:58,119 --> 00:31:04,759 size of an orange. Our dense rainforest home has become 258 00:31:05,039 --> 00:31:16,400 patchy forest. We can stand on branches move along them, 259 00:31:16,440 --> 00:31:24,200 but to reach more food, we need to let go. 260 00:31:41,319 --> 00:31:45,559 Four point four million years ago, these are our first 261 00:31:45,680 --> 00:31:52,680 steps on two legs. Walking takes us to the food 262 00:31:52,759 --> 00:31:55,559 and leaves our hands free to pick it. 263 00:31:55,559 --> 00:31:57,680 Speaker 2: It catches on fast. 264 00:31:59,119 --> 00:32:03,960 Speaker 1: Artipithecus is smart enough to copy and learn. Walking gets 265 00:32:04,000 --> 00:32:08,200 past from parent to child. Over the next one point 266 00:32:08,279 --> 00:32:11,559 two million years Our body evolves so that we can 267 00:32:11,599 --> 00:32:22,200 walk further and faster. Finding shelter, a mate and food 268 00:32:22,839 --> 00:32:28,440 gets easier, but childbirth gets harder. With a narrower pelvis, 269 00:32:29,000 --> 00:32:36,119 giving birth to a fully developed infant becomes impossible. Babies 270 00:32:36,160 --> 00:32:39,200 have to come out early when their heads are smaller 271 00:32:39,240 --> 00:32:40,440 and they're barely developed. 272 00:32:41,480 --> 00:32:42,400 Speaker 2: That's why we are. 273 00:32:42,319 --> 00:32:44,759 Speaker 1: One of the few species to spend years caring for 274 00:32:44,799 --> 00:32:49,279 our offspring, protecting them, feeding them, and keeping them out 275 00:32:49,319 --> 00:32:57,880 of trouble. Three point two million years ago, we're an 276 00:32:57,880 --> 00:33:02,359 Australo pitheken. Our brain is the size of a grapefruit, 277 00:33:02,799 --> 00:33:36,839 and we walk on two legs all the time. We 278 00:33:36,920 --> 00:33:39,960 got lucky, the lion has already eaten. 279 00:33:41,279 --> 00:33:41,759 Speaker 2: This time. 280 00:33:44,000 --> 00:33:47,559 Speaker 1: We can't outrun our predators. The only way to survive 281 00:33:48,039 --> 00:33:51,480 is to outthink that the smarter we get, the. 282 00:33:51,480 --> 00:33:52,279 Speaker 2: Longer we live. 283 00:33:54,200 --> 00:33:57,440 Speaker 1: Natural selection promotes the mutations that improve. 284 00:33:57,160 --> 00:34:04,000 Speaker 2: Our brain power. Your jaw muscles released from the. 285 00:34:04,000 --> 00:34:05,799 Speaker 1: Muscle's vice like grip. 286 00:34:05,960 --> 00:34:07,359 Speaker 2: The brain is free to grow. 287 00:34:08,239 --> 00:34:19,159 Speaker 1: It doubles in size two point three million years ago. 288 00:34:19,639 --> 00:34:27,320 This is Homo habilis, also known as handyman. Walking on 289 00:34:27,400 --> 00:34:30,679 two legs with a big brain. We're the first of 290 00:34:30,719 --> 00:34:34,800 an entirely new type of creature. We're the first man. 291 00:34:36,559 --> 00:34:43,519 We're bigger, stronger, and hungry than ever before. There's food 292 00:34:43,559 --> 00:34:47,840 out there, but it's more likely to eat us before 293 00:34:47,880 --> 00:34:59,079 we can eat it. We're a scavenger working alone. We 294 00:34:59,119 --> 00:35:30,639 eat whatever we can find. The edge is razor sharp. 295 00:35:37,800 --> 00:35:44,840 We have just made the very first tool. Armed with this, 296 00:35:45,840 --> 00:35:46,880 we will change. 297 00:35:46,559 --> 00:35:47,400 Speaker 2: The world. 298 00:35:58,039 --> 00:36:03,000 Speaker 1: East Africa two point three million years ago, after over 299 00:36:03,079 --> 00:36:06,519 three billion years of evolution, we take our fate into 300 00:36:06,559 --> 00:36:10,360 our own hands. We are the first species to make 301 00:36:10,440 --> 00:36:15,719 tools in this hostile environment. We need every advantage we 302 00:36:15,760 --> 00:36:21,880 can get. We must fight off predators, starvation, and our 303 00:36:21,920 --> 00:36:51,559 own relatives. There's no meat left. It looks like we're 304 00:36:51,599 --> 00:36:59,599 going hungry again. But there's bone marrow locked inside packed 305 00:36:59,639 --> 00:37:03,800 within her. The tool is the key to a whole 306 00:37:03,840 --> 00:37:06,880 new way of life. We'll use it to grow crops, 307 00:37:07,599 --> 00:37:13,239 build cities, and travel into space. Our thumbs become stronger, 308 00:37:14,320 --> 00:37:18,280 puld a cup, pick up a pen. We can do 309 00:37:18,320 --> 00:37:21,960 this because two million years ago, tool use changed our 310 00:37:22,000 --> 00:37:26,639 bodies and the course of evolution. We've pieced together our 311 00:37:26,679 --> 00:37:31,599 ancestors story from their bones, but from the vastness of Africa. 312 00:37:32,320 --> 00:37:35,639 All the bones of our early human ancestors ever found, 313 00:37:36,239 --> 00:37:39,760 would fit into the back of a pick up. Less 314 00:37:39,800 --> 00:37:43,760 than one bone in a billion becomes a fossil factor 315 00:37:43,800 --> 00:37:46,559 in the chances of finding those bones across millions of 316 00:37:46,559 --> 00:37:51,440 square miles, and it's clear most of what has lived. 317 00:37:51,480 --> 00:37:52,280 Speaker 2: Has been lost. 318 00:37:53,360 --> 00:37:56,960 Speaker 1: Our family tree is a giant puzzle with most of 319 00:37:57,000 --> 00:38:03,360 the pieces missing. But one point eight million years ago, 320 00:38:03,880 --> 00:38:06,519 a piece falls into place and we find a new 321 00:38:06,519 --> 00:38:13,400 species on the scene, Homo erectus. Until this point we 322 00:38:13,400 --> 00:38:22,239 were scavengers, but now we're hunters, and we've learned how 323 00:38:22,239 --> 00:38:38,280 to work with other members of our species. The hunt 324 00:38:38,360 --> 00:38:44,320 is on. The impala can run fast, but we can 325 00:38:44,400 --> 00:38:50,719 run further. Low shoulders and long torsos stabilize us. Powerful 326 00:38:50,719 --> 00:39:02,599 buttock muscles contract, expand, and push us forwards. Sweat stops 327 00:39:02,679 --> 00:39:16,800 us from overheating. Covered in fur, the Impalla is exhausted. 328 00:39:34,480 --> 00:39:42,199 Fire it sparks an idea that will make our ancestors 329 00:39:43,320 --> 00:40:09,280 human warmth. Light, safety is within reach. Nature's power is 330 00:40:09,280 --> 00:40:27,719 in our hands. Protected from the terrors of the dark, 331 00:40:28,440 --> 00:40:34,079 our extended family gather round By working together, These earliest 332 00:40:34,119 --> 00:40:41,159 families get food more often, so we live longer. This 333 00:40:41,360 --> 00:40:44,880 is the advantage of family life, the reason most of 334 00:40:44,960 --> 00:40:59,559 us live as we do today. Meat is too precious 335 00:40:59,559 --> 00:41:13,239 to waste, and cooked meat is easier to chew. The 336 00:41:13,320 --> 00:41:17,119 powerful molars used to chew tough raw food retreat back 337 00:41:17,119 --> 00:41:20,880 into the gums, where they'll stay as our wisdom teeth. 338 00:41:21,719 --> 00:41:25,239 Thirty five percent of us never even grow them, a 339 00:41:25,280 --> 00:41:29,239 sign that they may be evolving out of existence. With 340 00:41:29,360 --> 00:41:33,320 less energy spent on chewing, our ancestors have energy to spare. 341 00:41:34,679 --> 00:41:38,360 The brain increases to the size of a softball, fifty 342 00:41:38,400 --> 00:41:43,559 percent larger than before the invention of cooking. Erectus is 343 00:41:43,599 --> 00:41:48,599 the cleverest, most cooperative ancestor to date, but with several 344 00:41:48,639 --> 00:41:56,159 adult males in an extended family, rivalries are inevitable, communicate 345 00:41:56,639 --> 00:42:09,199 and will live longer. A natural selection kicks in. Our tongue, 346 00:42:09,320 --> 00:42:13,079 changes shape and moves down our throat, carrying the larynx 347 00:42:13,119 --> 00:42:16,960 with it, allowing us to form different shapes in our mouths, 348 00:42:17,800 --> 00:42:25,440 making different sounds and ultimately words. Speech is our greatest tool. 349 00:42:26,480 --> 00:42:28,800 It's the last piece of the puzzle that turns our 350 00:42:28,840 --> 00:42:36,360 ancestors into us. Two hundred thousand years ago, after a 351 00:42:36,400 --> 00:42:40,400 three point three billion year battle for survival. We've arrived. 352 00:42:42,840 --> 00:42:48,880 We are Homo sapiens, meaning wise men. Pound for pound, 353 00:42:49,239 --> 00:42:51,840 we have the largest brain of any creature on Earth. 354 00:42:52,840 --> 00:42:55,000 Speaker 2: Armed with tools, speech, and. 355 00:42:55,000 --> 00:43:00,599 Speaker 1: Superior intelligence, we spread out across every continent, evolve and 356 00:43:00,679 --> 00:43:04,800 adapt to new environments, new challenges, until we become the 357 00:43:04,920 --> 00:43:06,840 undisputed masters of the world.