1 00:00:25,560 --> 00:00:30,000 The Earth, home to millions of species. 2 00:00:34,640 --> 00:00:37,880 But what might live... beyond? 3 00:00:45,160 --> 00:00:48,480 There are countless planets throughout the universe. 4 00:00:53,920 --> 00:00:57,360 If life exists on only a fraction of them, 5 00:00:58,520 --> 00:01:03,200 then the universe must be... alive. 6 00:01:12,960 --> 00:01:16,640 All living things have the same needs. 7 00:01:19,440 --> 00:01:20,640 To feed... 8 00:01:27,320 --> 00:01:28,600 reproduce... 9 00:01:33,280 --> 00:01:34,280 and evolve. 10 00:01:38,120 --> 00:01:40,760 By applying the laws of life on Earth 11 00:01:41,320 --> 00:01:43,080 to the rest of the universe... 12 00:01:45,120 --> 00:01:46,920 it's possible to imagine 13 00:01:47,400 --> 00:01:48,880 what could live... 14 00:01:50,320 --> 00:01:52,480 on alien worlds. 15 00:02:15,720 --> 00:02:19,040 All life forms need a planet to live on. 16 00:02:20,640 --> 00:02:23,760 But how many planets are there in the universe? 17 00:02:28,920 --> 00:02:30,480 Think about our star, 18 00:02:31,440 --> 00:02:32,440 the Sun, 19 00:02:33,360 --> 00:02:36,760 with Earth, Mars, Jupiter orbiting it. 20 00:02:41,520 --> 00:02:42,880 For centuries, 21 00:02:42,960 --> 00:02:46,040 people have asked themselves, "What about the other stars? 22 00:02:46,120 --> 00:02:48,200 Uh, do they have planets as well?" 23 00:02:52,120 --> 00:02:53,760 And 24 years ago, 24 00:02:54,600 --> 00:02:55,920 I found one! 25 00:03:02,880 --> 00:03:06,440 Didier Queloz is a superstar astrophysicist. 26 00:03:09,120 --> 00:03:12,840 He has won the Nobel Prize for discovering the first planet 27 00:03:12,920 --> 00:03:14,880 beyond our solar system. 28 00:03:18,520 --> 00:03:21,480 I was 28 years old when I found the planet. 29 00:03:22,240 --> 00:03:24,560 I was about to finish my PhD, 30 00:03:24,640 --> 00:03:28,080 and my PhD adviser gave me the key of the equipment. 31 00:03:28,680 --> 00:03:32,400 And after observing a couple of times, the star 51 Peg, 32 00:03:32,480 --> 00:03:35,080 I realized that something was going on on that star. 33 00:03:36,720 --> 00:03:39,120 And frankly, I just panicked at that time. 34 00:03:40,120 --> 00:03:42,840 I thought something was really wrong with my equipment. 35 00:03:44,120 --> 00:03:48,120 And the more I wanted to understand this, the less it made sense. 36 00:03:49,640 --> 00:03:53,040 Until the point I got convinced it must be a planet. 37 00:03:58,480 --> 00:04:00,240 That's likely to be a planet over there. 38 00:04:02,440 --> 00:04:03,920 Could be Jupiter over there. 39 00:04:04,480 --> 00:04:05,720 It's pretty cool. 40 00:04:12,040 --> 00:04:15,280 Distant planets are invisible to telescopes 41 00:04:15,920 --> 00:04:17,960 because they don't emit any light. 42 00:04:21,120 --> 00:04:23,800 But if a planet passes in front of a star, 43 00:04:24,760 --> 00:04:26,880 it casts a tiny shadow, 44 00:04:27,520 --> 00:04:30,680 and there's a minuscule dimming of the star's brightness. 45 00:04:32,920 --> 00:04:35,960 When astronomers detect this dip in light level, 46 00:04:36,040 --> 00:04:38,400 they have found a new planet. 47 00:04:41,920 --> 00:04:43,040 Hello, guys. 48 00:04:43,960 --> 00:04:46,200 Uh... Oh, hey. Here is what the telescope is looking at. 49 00:04:46,280 --> 00:04:48,200 This is a picture of the telescope right now. 50 00:04:49,240 --> 00:04:52,640 Uh, in the middle, you have the... the target we're observing. 51 00:04:52,720 --> 00:04:56,680 So, you analyze this whole field, you process the data, 52 00:04:56,760 --> 00:05:00,480 and, um, if you're lucky enough, you detect this. 53 00:05:00,560 --> 00:05:03,200 There's a little bit of a decrease of the flux, 54 00:05:03,280 --> 00:05:06,560 and this tells me that there is a planet orbiting that star. 55 00:05:10,960 --> 00:05:14,560 We know there are a huge number of planets in the universe. 56 00:05:17,720 --> 00:05:21,400 There must be a zillion kinds of different life. 57 00:05:22,240 --> 00:05:25,400 Let's imagine that this is the Earth, here... 58 00:05:27,080 --> 00:05:28,080 Right? 59 00:05:28,120 --> 00:05:33,760 So, imagine that one meter is 20 light-years. 60 00:05:33,840 --> 00:05:37,040 So, I've made two meters as 40 light-years. 61 00:05:37,120 --> 00:05:42,200 This is where you have 51 Peg, where the first planet was detected. 62 00:05:44,000 --> 00:05:46,920 Each of these tiny lights represents a star 63 00:05:47,000 --> 00:05:48,840 where a planet has been found. 64 00:05:51,320 --> 00:05:53,000 Over the next few years, 65 00:05:53,440 --> 00:05:55,680 planets were turning up everywhere. 66 00:05:57,400 --> 00:05:59,640 ♪ Planets, planets everywhere ♪ 67 00:06:03,360 --> 00:06:05,760 It looks pretty cool right now. 68 00:06:06,240 --> 00:06:08,480 A horizon of stars and planets... 69 00:06:09,320 --> 00:06:11,000 all around. 70 00:06:16,920 --> 00:06:21,560 Planets beyond our solar system are called exoplanets. 71 00:06:26,520 --> 00:06:29,920 Astronomers have found over 4,000 of them. 72 00:06:31,120 --> 00:06:32,880 And they keep finding more. 73 00:06:41,280 --> 00:06:46,480 They now believe there's at least one planet for every star in the universe. 74 00:06:48,920 --> 00:06:55,280 That means over a million, billion, trillion exoplanets. 75 00:07:00,040 --> 00:07:03,600 More than all the grains of sand on Earth. 76 00:07:05,840 --> 00:07:10,440 A vast canvas for the evolution of life. 77 00:07:18,160 --> 00:07:20,760 The distances are mind-boggling. 78 00:07:22,720 --> 00:07:26,560 The nearest exoplanets are trillions of miles from us. 79 00:07:29,720 --> 00:07:34,640 But they're all subject to the same force that holds the Earth in place. 80 00:07:37,200 --> 00:07:38,200 Gravity. 81 00:07:46,160 --> 00:07:49,520 Imagine a world double the size of Earth, 82 00:07:50,440 --> 00:07:52,280 with twice as much gravity. 83 00:07:56,040 --> 00:07:58,360 This is Atlas. 84 00:08:03,160 --> 00:08:06,360 How would life adapt on such a world? 85 00:08:17,920 --> 00:08:21,520 Gravity pulls vegetation to the planet's surface. 86 00:08:24,120 --> 00:08:27,520 And yet, seeds can float in the sky. 87 00:08:29,520 --> 00:08:32,600 That's because gravity here is so strong. 88 00:08:33,120 --> 00:08:36,080 Air molecules are densely packed together... 89 00:08:38,280 --> 00:08:42,840 creating a thick, buoyant atmosphere for seeds to drift through. 90 00:08:53,520 --> 00:08:55,080 And where there are seeds... 91 00:08:56,160 --> 00:08:57,680 there are sky grazers. 92 00:09:03,120 --> 00:09:06,280 Giant herbivores with six wings 93 00:09:07,040 --> 00:09:09,600 to ride on the dense pillow of air. 94 00:09:21,200 --> 00:09:22,800 Because of the extra gravity, 95 00:09:23,440 --> 00:09:26,240 they weigh twice as much as they would on Earth. 96 00:09:29,520 --> 00:09:31,640 But they don't fall from the sky. 97 00:09:32,320 --> 00:09:36,480 The atmosphere is thick enough to keep them airborne. 98 00:09:43,720 --> 00:09:46,000 Whether on Atlas or on Earth, 99 00:09:46,680 --> 00:09:50,800 flying is always a battle to overcome gravity. 100 00:09:59,320 --> 00:10:02,920 You might say I have a pretty complicated relationship with gravity. 101 00:10:04,640 --> 00:10:07,280 And you can really feel that gravity is a force pulling you down 102 00:10:07,360 --> 00:10:08,800 as you struggle your way up. 103 00:10:11,920 --> 00:10:15,280 But ultimately, my dream has always been to be able to fly. 104 00:10:18,560 --> 00:10:21,520 Whoo-hoo-hoo! 105 00:10:23,480 --> 00:10:27,960 The thing I love most about paragliding is that it's so simple and intuitive. 106 00:10:28,040 --> 00:10:29,800 It's just you and the air. 107 00:10:32,040 --> 00:10:34,640 Like the sky grazers on Atlas, 108 00:10:35,120 --> 00:10:38,400 paragliders use their wings to generate lift. 109 00:10:42,120 --> 00:10:44,680 But the atmosphere is less dense on Earth... 110 00:10:46,640 --> 00:10:49,680 so it takes more effort to stay airborne. 111 00:10:54,120 --> 00:10:56,480 Most people don't see air as a substance. 112 00:10:58,520 --> 00:11:00,120 But for me, when I'm flying, 113 00:11:00,200 --> 00:11:04,160 I really see it as a fluid that's moving up and down the valleys 114 00:11:04,240 --> 00:11:05,600 and along the ridges. 115 00:11:08,720 --> 00:11:12,040 It would be really weird to fly in a very dense atmosphere. 116 00:11:13,040 --> 00:11:16,680 You could just be gliding around the whole time, effortlessly. 117 00:11:20,120 --> 00:11:24,160 The best way to gain altitude is to find an updraft, 118 00:11:25,120 --> 00:11:26,880 known as a "thermal." 119 00:11:29,120 --> 00:11:31,216 When you hit the thermal, it's very similar 120 00:11:31,240 --> 00:11:33,440 to when you're in an elevator and it starts. 121 00:11:36,520 --> 00:11:38,080 You feel a push upwards. 122 00:11:38,160 --> 00:11:39,600 Yeah, there we go! 123 00:11:43,720 --> 00:11:45,880 Just the power of nature to pull me up. 124 00:11:50,040 --> 00:11:52,840 When I'm flying and I see a bird circling up, 125 00:11:52,920 --> 00:11:54,880 it means there must be a thermal there. 126 00:11:55,680 --> 00:11:57,840 So we're always constantly looking at them. 127 00:12:02,400 --> 00:12:06,000 You can really feel the balance between the gravity pulling you down 128 00:12:06,080 --> 00:12:07,640 and the air lifting you up. 129 00:12:08,320 --> 00:12:11,760 You can then use your bodyweight to gain speed, 130 00:12:11,840 --> 00:12:13,840 and use that speed to generate more energy 131 00:12:14,440 --> 00:12:16,240 and feel that you're moving through the air. 132 00:12:34,680 --> 00:12:38,320 Gravity may be weaker on Earth than on Atlas... 133 00:12:39,120 --> 00:12:42,680 but the thinner atmosphere means there's less buoyancy. 134 00:12:45,240 --> 00:12:48,400 So, eventually, everything falls. 135 00:13:10,720 --> 00:13:14,520 On Atlas, the sky grazers never need to land. 136 00:13:18,720 --> 00:13:22,280 Their front and back wings are for direction and thrust. 137 00:13:25,520 --> 00:13:28,280 Their long middle wings are for catching thermals. 138 00:13:32,080 --> 00:13:33,720 Despite their weight, 139 00:13:34,360 --> 00:13:38,320 the air is thick enough for them to live a life 140 00:13:38,800 --> 00:13:40,080 in the sky. 141 00:13:45,120 --> 00:13:48,080 But it's not always a peaceful life. 142 00:13:50,640 --> 00:13:54,760 As on Earth, grazers attract predators. 143 00:13:57,400 --> 00:14:02,000 Using hydrogen-producing bacteria to inflate their air sacs, 144 00:14:02,440 --> 00:14:04,560 they take to the skies. 145 00:14:15,080 --> 00:14:17,840 Alone, they're no match for their prey... 146 00:14:20,440 --> 00:14:22,320 so they hunt in a pack... 147 00:14:24,400 --> 00:14:27,800 waiting for a sky grazer to stray from the group. 148 00:14:38,480 --> 00:14:41,920 Target sighted, they expel their gas... 149 00:14:44,440 --> 00:14:46,240 and attack from above. 150 00:14:56,840 --> 00:14:59,080 The fastest predator on Earth 151 00:14:59,160 --> 00:15:01,320 uses the same tactic. 152 00:15:04,640 --> 00:15:06,600 My interest in flying falcons is... 153 00:15:07,160 --> 00:15:11,240 their predatory instinct coupled with the speed factor... 154 00:15:16,320 --> 00:15:18,360 and how they use that speed to their advantage. 155 00:15:24,040 --> 00:15:27,240 But just watching a top predator do its thing... 156 00:15:31,520 --> 00:15:33,280 is perfection. 157 00:15:43,720 --> 00:15:46,600 I probably have 30-some birds at this moment. 158 00:15:47,440 --> 00:15:49,320 Each bird is a different personality. 159 00:15:50,720 --> 00:15:52,240 What I love about falcons 160 00:15:52,320 --> 00:15:55,440 is how evolution has made the most perfect specimen. 161 00:16:05,440 --> 00:16:07,720 I do have a relationship with these guys. 162 00:16:07,800 --> 00:16:09,840 Certainly from my end, I do. 163 00:16:09,920 --> 00:16:11,880 I don't think the falcons see it that way, 164 00:16:11,960 --> 00:16:14,160 but they certainly see me as part of the team. 165 00:16:16,560 --> 00:16:21,960 Vahe Alaverdian trains captive-bred falcons how to hunt. 166 00:16:27,240 --> 00:16:29,240 These birds are genetically programmed 167 00:16:29,320 --> 00:16:31,600 to be the top-notch avian predators that they are. 168 00:16:34,440 --> 00:16:35,840 What we do as falconers 169 00:16:35,920 --> 00:16:38,600 is try to awaken that predatorial nature in the bird. 170 00:16:47,240 --> 00:16:49,240 Lure training is the very first step. 171 00:16:49,320 --> 00:16:51,360 Come on, buddy! Hup, hup, hup, hup, hup! 172 00:16:54,640 --> 00:16:57,000 I want to put that lure in front of the bird, 173 00:16:57,560 --> 00:16:59,920 and get the falcon to coordinate eye to foot... 174 00:17:00,000 --> 00:17:00,920 Hup, hup! 175 00:17:00,921 --> 00:17:03,041 ...and throw its feet out as if it's gonna grab it. 176 00:17:03,920 --> 00:17:06,920 As that happens, I try to pull that away from the falcon 177 00:17:07,400 --> 00:17:10,360 to get it to shoot up in the air and repeat this process again. 178 00:17:11,320 --> 00:17:14,800 I wanna see that bird drop down as vertical as it can. 179 00:17:18,520 --> 00:17:22,120 That's something that they later on will apply to hunting game. 180 00:17:30,440 --> 00:17:35,000 When the falcons are ready, Vahe introduces a prey target... 181 00:17:36,600 --> 00:17:37,840 a racing pigeon. 182 00:17:41,240 --> 00:17:44,200 The falcon can't keep up with the pigeon in a chase, 183 00:17:45,440 --> 00:17:47,560 so its best bet is to drop on it... 184 00:17:48,480 --> 00:17:49,600 using gravity. 185 00:17:55,840 --> 00:17:58,720 When the bird thinks that he's got the advantage, 186 00:17:59,560 --> 00:18:01,680 that's when the wings will get tucked in. 187 00:18:04,640 --> 00:18:07,400 They stoop into a little teardrop shape... 188 00:18:09,040 --> 00:18:10,360 coming down from the heavens. 189 00:18:12,440 --> 00:18:14,880 The kinetic energy of a falcon hitting a pigeon 190 00:18:16,120 --> 00:18:19,560 would be as if you were hit by a cannonball. 191 00:18:27,440 --> 00:18:30,480 In training, the pigeon invariably gets away, 192 00:18:31,560 --> 00:18:35,120 because the falcon is made to stoop from less than a thousand feet. 193 00:18:38,440 --> 00:18:39,880 When hunting for real, 194 00:18:40,520 --> 00:18:42,520 it'll drop from a greater height... 195 00:18:44,280 --> 00:18:45,600 to lethal effect. 196 00:19:06,440 --> 00:19:08,680 The predators make their move. 197 00:19:23,840 --> 00:19:25,600 They deploy their wings 198 00:19:25,680 --> 00:19:27,040 to create drag... 199 00:19:28,960 --> 00:19:31,200 destabilizing the sky grazer 200 00:19:31,280 --> 00:19:33,680 to devour it on the ground. 201 00:19:42,720 --> 00:19:46,600 But this pack is too small to take down such a large beast. 202 00:19:53,640 --> 00:19:55,480 Today, they'll go hungry. 203 00:20:07,920 --> 00:20:10,880 The sky grazer climbs to a safe height... 204 00:20:12,520 --> 00:20:13,680 to recuperate. 205 00:20:19,440 --> 00:20:21,200 But as a fertile female, 206 00:20:21,920 --> 00:20:23,240 she has company. 207 00:20:25,680 --> 00:20:29,360 Male grazers, competing to be chosen as a mate. 208 00:20:36,640 --> 00:20:39,680 Their oversized tails are a handicap, 209 00:20:40,720 --> 00:20:42,200 making it harder to fly. 210 00:20:43,640 --> 00:20:47,440 But to the female, they're a sign of vitality. 211 00:20:51,600 --> 00:20:53,880 The first to reach her gets to mate 212 00:20:54,720 --> 00:20:57,000 and pass on his genes. 213 00:21:04,720 --> 00:21:07,560 The same principle applies on Earth, 214 00:21:08,760 --> 00:21:10,560 whether up in the sky 215 00:21:11,280 --> 00:21:12,800 or down in the dirt. 216 00:21:15,920 --> 00:21:18,600 Males compete for the right to mate. 217 00:21:20,600 --> 00:21:22,760 And running, set... 218 00:21:24,160 --> 00:21:27,600 I think when people sit at home watching insects on television, 219 00:21:27,680 --> 00:21:30,200 they imagine the cameraman sitting in the jungle, 220 00:21:30,760 --> 00:21:32,480 in a river or in a hedge, 221 00:21:33,120 --> 00:21:35,880 waiting for this beetle to come across 222 00:21:35,960 --> 00:21:39,440 and reproduce or have a fight in front of the camera. 223 00:21:42,120 --> 00:21:43,440 It doesn't work that way. 224 00:21:48,880 --> 00:21:53,200 This is a ramshackle old shed which is attached to my parents' place, 225 00:21:53,320 --> 00:21:54,520 which is just there. 226 00:21:55,640 --> 00:21:58,680 Huge advantages to having a place attached to your mum and dad's. 227 00:21:58,760 --> 00:22:02,880 You get good dinners in the evening and, uh, teas arriving during the day. 228 00:22:03,920 --> 00:22:05,720 - Have a look and see what we're doing. - Oh! 229 00:22:06,360 --> 00:22:07,600 Oh, gosh. 230 00:22:08,560 --> 00:22:10,240 Oh! What on Earth are they? 231 00:22:10,320 --> 00:22:12,400 They are rhinoceros beetles. 232 00:22:13,720 --> 00:22:15,280 The male's got these big horns. 233 00:22:15,360 --> 00:22:18,600 The female doesn't. It's a form of sexual selection, 234 00:22:18,680 --> 00:22:22,720 because the females like males with big horns. 235 00:22:24,320 --> 00:22:25,600 So every time they mate, 236 00:22:25,680 --> 00:22:28,960 they'll mate with a beetle that has a slightly bigger horn 237 00:22:29,040 --> 00:22:30,816 - than the one they've last seen before. - Oh! 238 00:22:30,840 --> 00:22:33,600 And, therefore, that male passes its genes on. 239 00:22:34,320 --> 00:22:37,400 So, over generations, the horns will get bigger. 240 00:22:39,280 --> 00:22:41,536 - Anywhere particular? - Um, just on the... 241 00:22:41,560 --> 00:22:43,520 on the log facing the other male. 242 00:22:44,400 --> 00:22:46,360 Here they go. They're going straight away. 243 00:22:49,920 --> 00:22:52,160 The horns of a male rhinoceros beetle 244 00:22:52,240 --> 00:22:54,800 are like the tail of a male sky grazer. 245 00:22:57,840 --> 00:23:00,280 They've evolved for sexual competition. 246 00:23:20,640 --> 00:23:22,840 - Ha-ha! - That dominant one's done it again. 247 00:23:28,360 --> 00:23:30,240 That's a good shot. The shot we wanted. 248 00:23:30,280 --> 00:23:32,160 - Yeah. - Going into her, yeah. 249 00:23:35,640 --> 00:23:36,760 One, two, three. 250 00:23:37,960 --> 00:23:39,120 - That right? - Yeah. 251 00:23:39,760 --> 00:23:41,120 - Yep. - That's it. 252 00:23:41,200 --> 00:23:42,680 - Can I... Yes. - You putting that in? 253 00:23:48,000 --> 00:23:51,760 Male insects don't always fight to snare a mate. 254 00:23:53,240 --> 00:23:57,320 Sometimes it's enough just to show off their physical prowess. 255 00:24:00,160 --> 00:24:02,520 Right, I'm gonna bring the male in front of you. 256 00:24:02,600 --> 00:24:03,840 He's coming in from your right. 257 00:24:06,480 --> 00:24:08,080 Now, uh... He's flown off. 258 00:24:09,200 --> 00:24:11,560 These are stalk-eyed flies. 259 00:24:14,760 --> 00:24:17,440 Stalk-eyed fly is an amazing little thing. 260 00:24:17,520 --> 00:24:21,280 It looks a little bit like an ant with massive eyes on the ends of stalks. 261 00:24:22,680 --> 00:24:26,600 Both the male and the female have eyes on the end of stalks, 262 00:24:26,680 --> 00:24:29,360 but the male has much longer eye stalks than the female. 263 00:24:32,040 --> 00:24:36,200 The males with the long stalks will come up to one another, 264 00:24:36,280 --> 00:24:38,480 and they will, kind of, have a little dance. 265 00:24:44,640 --> 00:24:46,000 And they will try and judge 266 00:24:46,080 --> 00:24:48,920 which of the two of them has the bigger stalks. 267 00:24:51,080 --> 00:24:53,000 There they are. That's the standoff! 268 00:24:57,560 --> 00:25:01,280 The winner of that will remain where they are and the loser will then toddle off. 269 00:25:03,280 --> 00:25:05,960 That winner then will gain access to the female, 270 00:25:06,040 --> 00:25:08,200 and be able to reproduce with her, 271 00:25:08,280 --> 00:25:11,000 and that way can pass on the genetics that he has, 272 00:25:11,080 --> 00:25:14,080 which will include that of a longer eye stalk. 273 00:25:15,600 --> 00:25:17,760 - Yes! Got it. - Are... are you on it? 274 00:25:18,200 --> 00:25:19,400 Oh, It's fantastic. 275 00:25:25,160 --> 00:25:28,280 Normally, it's a second and they're gone. This is fantastic. 276 00:25:34,920 --> 00:25:36,960 Why would the male stalk-eyed fly go to the effort 277 00:25:37,040 --> 00:25:38,880 of having these enormous eye stalks? 278 00:25:39,440 --> 00:25:43,000 Well, the idea is that you are conspicuously signaling to the female 279 00:25:43,080 --> 00:25:48,000 that you can have this incredible investment of energy into this resource 280 00:25:48,080 --> 00:25:49,520 that is completely needless. 281 00:25:51,720 --> 00:25:53,440 And if you can still survive, 282 00:25:53,520 --> 00:25:57,080 if you can carry on flying and living and not getting predated upon, 283 00:25:57,160 --> 00:26:01,840 and still have this... wasteful extravagance coming out of your head, 284 00:26:01,920 --> 00:26:04,880 then you're gonna be a pretty good bet to reproduce with. 285 00:26:19,040 --> 00:26:20,280 On Atlas, 286 00:26:20,360 --> 00:26:26,080 the long tail of the male sky grazer shows he's an ideal choice... 287 00:26:28,200 --> 00:26:30,880 to father the next generation. 288 00:26:37,720 --> 00:26:41,040 But the mother can't lay her eggs in the sky. 289 00:26:46,960 --> 00:26:48,800 So she's come down to land. 290 00:26:53,120 --> 00:26:58,280 Because of the gravity, she's too heavy to launch herself back into the sky. 291 00:27:04,200 --> 00:27:08,080 To create new life, she must surrender her own. 292 00:27:22,120 --> 00:27:25,760 The babies grow up close to where their mothers die. 293 00:27:29,320 --> 00:27:33,080 Now they need to get off the ground and into the air. 294 00:27:41,560 --> 00:27:44,160 But scavengers lie in wait. 295 00:27:45,760 --> 00:27:47,360 Boneless creatures 296 00:27:47,480 --> 00:27:50,360 with no skeleton to give them form. 297 00:27:55,920 --> 00:28:00,200 They kill by enveloping and dissolving their prey. 298 00:28:10,920 --> 00:28:17,240 The sky grazers have only just hatched, but already they're in grave danger. 299 00:28:20,840 --> 00:28:24,000 And now, there's no going back. 300 00:28:48,200 --> 00:28:49,640 Every day on Earth, 301 00:28:49,720 --> 00:28:53,000 young animals have to overcome terrible odds, 302 00:28:53,560 --> 00:28:55,000 if they're to survive. 303 00:28:59,200 --> 00:29:03,760 Sixty percent of meerkats don't make it to their first birthday. 304 00:29:06,320 --> 00:29:08,920 For a young meerkat, in their early life, 305 00:29:09,400 --> 00:29:11,840 there's a lot of danger here. 306 00:29:12,680 --> 00:29:16,680 They're vulnerable for many months after they're born... 307 00:29:19,840 --> 00:29:23,640 but particularly in the first month or two after they emerge from the burrow. 308 00:29:25,920 --> 00:29:29,520 Predators are everywhere, and a constant danger. 309 00:29:34,920 --> 00:29:36,360 There are snakes in this area 310 00:29:37,720 --> 00:29:40,000 that will eat a young meerkat. 311 00:30:03,400 --> 00:30:06,280 A young meerkat is safe within a group, 312 00:30:07,240 --> 00:30:10,400 but if it lags behind, it's vulnerable. 313 00:30:15,840 --> 00:30:18,720 Scorpions are a constant threat. 314 00:30:24,560 --> 00:30:27,400 The young are really completely incompetent, 315 00:30:27,880 --> 00:30:31,120 and totally ignorant when it comes to dealing with scorpions, initially. 316 00:30:34,240 --> 00:30:36,720 But they can't avoid this danger forever. 317 00:30:38,640 --> 00:30:42,040 They're going to eventually have to learn how to neutralize the threat. 318 00:30:49,520 --> 00:30:52,960 The first time that a young meerkat faces a scorpion 319 00:30:53,040 --> 00:30:54,920 and it has to deal with it itself 320 00:30:56,640 --> 00:30:59,000 is probably a terrifying encounter. 321 00:31:00,720 --> 00:31:03,440 This is a real moment of truth. 322 00:31:28,120 --> 00:31:32,280 It's a real rite of passage, because once they've managed to do that themselves, 323 00:31:33,280 --> 00:31:36,320 then they really are at a stage where they can start to forage by themselves 324 00:31:36,400 --> 00:31:39,280 and become independent and be a useful group member. 325 00:31:41,040 --> 00:31:44,840 So, they've really managed to escape the vulnerability of being a pup 326 00:31:44,920 --> 00:31:48,400 and made that transition into being an adult. 327 00:31:57,600 --> 00:32:00,960 It's one step on the road to adulthood, 328 00:32:01,040 --> 00:32:03,720 but it's by no means plain sailing after that. 329 00:32:05,160 --> 00:32:07,680 There are a lot of threats out there, 330 00:32:07,760 --> 00:32:11,080 and it will have to continue to learn in order to reach adulthood. 331 00:32:23,240 --> 00:32:25,880 If the young sky grazers are to grow up, 332 00:32:27,320 --> 00:32:28,920 they have no choice. 333 00:32:31,320 --> 00:32:33,040 It's time to fly. 334 00:33:03,440 --> 00:33:06,000 Even in the air, they're still not safe. 335 00:33:14,160 --> 00:33:18,400 On Atlas, survival is a game of chance. 336 00:33:27,040 --> 00:33:31,080 Life goes on from one generation to the next. 337 00:33:34,640 --> 00:33:36,400 At least for now. 338 00:33:41,640 --> 00:33:46,720 The strong gravity of Atlas pulls asteroids onto a collision course. 339 00:33:55,120 --> 00:33:57,440 Most burn up in the atmosphere. 340 00:33:59,320 --> 00:34:02,840 But there's a constant threat something big will get through... 341 00:34:05,160 --> 00:34:08,320 and reset the course of life on the planet. 342 00:34:18,520 --> 00:34:21,760 Because gravity is weaker on Earth than Atlas, 343 00:34:21,840 --> 00:34:24,320 asteroid strikes are less frequent. 344 00:34:27,320 --> 00:34:31,240 But when they do occur, they can be catastrophic. 345 00:34:36,440 --> 00:34:38,640 This is the Yucatán Peninsula. 346 00:34:42,480 --> 00:34:46,200 27,000 square miles of tropical jungle. 347 00:34:49,120 --> 00:34:54,600 But hidden within the jungle are numerous sinkholes called cenotes. 348 00:35:08,040 --> 00:35:12,280 These are entrances to vast underground cave systems. 349 00:35:15,040 --> 00:35:18,360 There's no surface rivers or streams in the peninsula, 350 00:35:19,320 --> 00:35:23,040 so the only source of water is underground in caves. 351 00:35:30,080 --> 00:35:34,000 But the really interesting thing is the location of these cenotes. 352 00:35:34,400 --> 00:35:39,440 Although there's probably 10,000 or more cenotes across the peninsula, 353 00:35:39,880 --> 00:35:42,000 in the northwest corner... 354 00:35:45,360 --> 00:35:50,080 they occur in a very well-defined semicircle. 355 00:35:50,160 --> 00:35:54,440 If we follow that semicircle out into the Gulf of Mexico... 356 00:35:57,880 --> 00:36:02,800 we now have a complete circle that marks what one would expect 357 00:36:02,880 --> 00:36:06,000 from the edge of an asteroid impact crater. 358 00:36:07,800 --> 00:36:10,000 65 million years ago, 359 00:36:10,080 --> 00:36:13,760 gravity pulled an asteroid into our solar system. 360 00:36:16,560 --> 00:36:18,520 It smashed into our planet, 361 00:36:18,840 --> 00:36:22,720 causing the extinction of 75 percent of life on Earth. 362 00:36:33,920 --> 00:36:37,320 The asteroid strike generated enough debris 363 00:36:38,200 --> 00:36:41,080 to block out sunlight for two years. 364 00:36:44,520 --> 00:36:47,480 A world plunged into darkness. 365 00:36:48,680 --> 00:36:50,000 Nothing could grow. 366 00:36:54,320 --> 00:36:56,000 This would happen on Atlas 367 00:36:56,680 --> 00:36:59,280 if a big enough asteroid hit the planet. 368 00:37:01,160 --> 00:37:04,480 Cenotes are difficult places to survive... 369 00:37:06,320 --> 00:37:10,000 just like the Earth was 65 million years ago. 370 00:37:12,240 --> 00:37:17,000 What are the characteristics that a species needs to survive an extinction? 371 00:37:27,720 --> 00:37:29,080 Somebody's in here. 372 00:37:39,640 --> 00:37:42,400 So, crocodiles are very resilient animals. 373 00:37:44,720 --> 00:37:48,000 They live both in the water and on land. 374 00:37:50,320 --> 00:37:54,600 They're generalists. They don't require a specific diet. 375 00:37:56,400 --> 00:37:58,360 They'll eat almost anything. 376 00:38:00,400 --> 00:38:02,800 Whatever is available is good enough, 377 00:38:03,440 --> 00:38:04,560 they'll take it. 378 00:38:09,720 --> 00:38:11,280 Here in this cenote, 379 00:38:12,240 --> 00:38:15,600 one's fallen in, gotten trapped, no way out... 380 00:38:17,040 --> 00:38:18,560 Somehow, some way... 381 00:38:19,840 --> 00:38:21,160 he's succeeded. 382 00:38:22,400 --> 00:38:23,840 They're survivors. 383 00:38:26,920 --> 00:38:30,960 In a changing world, it pays to be a generalist, 384 00:38:31,040 --> 00:38:32,400 not a specialist. 385 00:38:46,400 --> 00:38:49,080 If a big enough asteroid hits Atlas, 386 00:38:49,640 --> 00:38:52,680 the sky grazers and predators would be doomed. 387 00:38:59,360 --> 00:39:02,640 They're too specialized to cope with change. 388 00:39:08,040 --> 00:39:11,600 The generalists are the boneless scavengers. 389 00:39:13,000 --> 00:39:16,240 Like crocodiles, they eat anything... 390 00:39:17,440 --> 00:39:19,200 and live anywhere. 391 00:39:23,640 --> 00:39:26,200 On this imagined high-gravity world, 392 00:39:26,920 --> 00:39:30,120 they could be the great survivors. 393 00:39:43,440 --> 00:39:45,160 How might life adapt 394 00:39:45,240 --> 00:39:47,040 on a different world, 395 00:39:48,320 --> 00:39:49,920 where creatures are trapped 396 00:39:50,560 --> 00:39:52,160 between a searing desert 397 00:39:53,760 --> 00:39:55,680 and a frozen shadowland? 398 00:39:57,720 --> 00:40:00,600 A world of extremes.