1 00:00:14,200 --> 00:00:17,600 Every year for just a few short months… 2 00:00:19,240 --> 00:00:23,160 …fresh water flows into the Okavango Delta… 3 00:00:27,680 --> 00:00:29,280 creating the perfect home… 4 00:00:31,360 --> 00:00:33,480 for a small family of elephants… 5 00:00:38,000 --> 00:00:42,280 and a playground for their two young calves… 6 00:00:44,520 --> 00:00:45,600 Bosigo… 7 00:00:47,680 --> 00:00:50,760 …and her baby cousin, Metsi. 8 00:00:59,440 --> 00:01:03,680 Bosigo and Metsi are only just beginning 9 00:01:03,760 --> 00:01:05,400 their love affair with water. 10 00:01:09,000 --> 00:01:10,320 But from now on, 11 00:01:11,200 --> 00:01:13,720 their lives will be defined by it. 12 00:01:15,960 --> 00:01:19,000 This one precious molecule… 13 00:01:21,400 --> 00:01:22,720 …delivered to Earth… 14 00:01:25,400 --> 00:01:29,640 …by the astonishing forces at work in our universe. 15 00:01:36,200 --> 00:01:38,560 It has transformed this planet… 16 00:01:41,760 --> 00:01:42,920 …into a haven… 17 00:01:48,600 --> 00:01:49,560 …for life. 18 00:02:26,200 --> 00:02:27,720 Summer has arrived. 19 00:02:30,360 --> 00:02:34,200 And what was paradise is no more. 20 00:02:37,360 --> 00:02:39,840 The fresh water that flooded the delta… 21 00:02:42,800 --> 00:02:44,760 only stays for a few months. 22 00:02:46,720 --> 00:02:48,800 And water holes are now vanishing. 23 00:02:50,520 --> 00:02:51,360 Fast. 24 00:02:58,520 --> 00:03:00,320 This means only one thing 25 00:03:00,400 --> 00:03:03,640 for the thousands of elephants who've been living here. 26 00:03:06,240 --> 00:03:08,080 It's time to move on. 27 00:03:21,960 --> 00:03:26,120 This has been the only home Metsi and Bosigo have ever known. 28 00:03:28,720 --> 00:03:32,200 But in a few weeks, all the water will be gone. 29 00:03:36,160 --> 00:03:40,000 So they must leave the delta with the rest of their family. 30 00:03:41,160 --> 00:03:43,120 A herd of females, 31 00:03:43,200 --> 00:03:46,200 sisters, aunts, and cousins, 32 00:03:48,080 --> 00:03:49,680 led by their grandmother, 33 00:03:50,760 --> 00:03:53,520 the great matriarch, Pula. 34 00:03:58,360 --> 00:04:02,440 They're embarking on a journey along with thousands of other families… 35 00:04:05,160 --> 00:04:06,400 out into the desert… 36 00:04:10,280 --> 00:04:11,600 in search of water. 37 00:04:18,840 --> 00:04:20,480 For the next eight months, 38 00:04:20,560 --> 00:04:24,840 they will migrate from water hole to water hole… 39 00:04:27,320 --> 00:04:30,160 and navigate ancient elephant trails… 40 00:04:31,200 --> 00:04:33,920 …using the matriarch Pula's knowledge, 41 00:04:35,320 --> 00:04:37,640 handed down to her through generations. 42 00:04:40,480 --> 00:04:43,040 The trek will put all their lives at risk. 43 00:04:45,080 --> 00:04:48,720 And they'll need every one of their exceptional senses… 44 00:04:48,800 --> 00:04:51,120 -…to endure the dangers. 45 00:04:55,640 --> 00:04:58,840 Making this journey is not a choice. 46 00:05:04,640 --> 00:05:07,080 Without water, they will die. 47 00:05:11,320 --> 00:05:13,880 Even on our blue planet, 48 00:05:13,960 --> 00:05:16,960 fresh liquid water is scarce. 49 00:05:20,160 --> 00:05:23,400 And if we search beyond the shores of our own planet… 50 00:05:25,480 --> 00:05:27,000 it's rarer still. 51 00:05:30,320 --> 00:05:32,880 Even the most arid desert on Earth 52 00:05:33,640 --> 00:05:38,240 is nothing compared to the rest of our solar system. 53 00:05:41,560 --> 00:05:44,080 In the cold outer reaches… 54 00:05:50,360 --> 00:05:52,720 …the only surface water is ice. 55 00:05:56,880 --> 00:05:59,320 Like Saturn's frozen moons… 56 00:06:01,640 --> 00:06:03,280 where fountains of ice 57 00:06:04,880 --> 00:06:07,400 shoot kilometers into space. 58 00:06:14,520 --> 00:06:17,800 Closer to the Sun on Mars, 59 00:06:18,720 --> 00:06:21,840 water is stripped away by savage solar winds. 60 00:06:32,640 --> 00:06:34,240 And on Venus, 61 00:06:34,320 --> 00:06:36,040 it simply boils away. 62 00:06:45,560 --> 00:06:48,320 There's only one world we know of 63 00:06:48,400 --> 00:06:51,800 that has the gift of liquid water on its surface. 64 00:06:57,120 --> 00:06:59,280 A pale blue dot. 65 00:07:00,920 --> 00:07:02,000 Our home… 66 00:07:08,160 --> 00:07:09,960 where right now, 67 00:07:10,800 --> 00:07:14,280 water is driving one particular family 68 00:07:14,800 --> 00:07:16,840 on a quest for survival. 69 00:07:24,600 --> 00:07:26,840 Just a month after leaving the delta, 70 00:07:27,920 --> 00:07:30,720 only a scattering of muddy pools remain. 71 00:07:34,840 --> 00:07:40,120 And they're getting fewer and farther apart each day. 72 00:07:43,840 --> 00:07:48,480 Pula is using her highly tuned memory to lead her family to a water hole. 73 00:07:55,040 --> 00:07:57,120 She can remember the exact route, 74 00:07:57,880 --> 00:07:59,480 even decades later. 75 00:08:03,680 --> 00:08:05,760 It's been a long day's march, 76 00:08:06,480 --> 00:08:09,640 and all of them are desperate for a drink. 77 00:08:13,800 --> 00:08:17,920 But so are the other 130,000 elephants 78 00:08:18,000 --> 00:08:19,600 that live in Botswana. 79 00:08:31,280 --> 00:08:34,800 The dry season has drawn herds from far and wide… 80 00:08:39,840 --> 00:08:42,000 …to this water hole. 81 00:08:52,160 --> 00:08:56,360 All competing for the same shrinking resource. 82 00:09:15,120 --> 00:09:19,240 The adults teach the young ones clever survival tricks, 83 00:09:20,000 --> 00:09:23,920 like how to skim a muddy pool to get the freshest water. 84 00:09:29,240 --> 00:09:34,000 And how to use some muddy water as refreshing sunscreen. 85 00:09:36,880 --> 00:09:40,800 Their wrinkly skin is perfect for trapping water and keeping cool. 86 00:09:49,480 --> 00:09:53,080 But Metsi and Bosigo are also learning… 87 00:09:56,120 --> 00:09:58,440 mud pools aren't just a place to drink. 88 00:10:00,080 --> 00:10:01,640 They're water parks too. 89 00:10:15,000 --> 00:10:16,960 With so many thirsty elephants, 90 00:10:17,480 --> 00:10:19,720 the water hole has been drained. 91 00:10:26,160 --> 00:10:28,000 Pula's family must press on… 92 00:10:31,840 --> 00:10:37,600 and try to make it to the next water hole before the blazing sun sucks it dry. 93 00:10:40,720 --> 00:10:44,080 This battle between sun and scorched earth 94 00:10:44,160 --> 00:10:47,280 has raged ever since our world was born… 95 00:10:52,040 --> 00:10:56,000 when our blue planet was anything but blue. 96 00:11:04,160 --> 00:11:06,840 Four and a half billion years ago… 97 00:11:12,600 --> 00:11:15,160 Earth was in its infancy. 98 00:11:16,640 --> 00:11:18,920 A fireball of molten rock… 99 00:11:23,440 --> 00:11:27,360 …destined to become a dry, barren world. 100 00:11:31,440 --> 00:11:34,560 But millions of kilometers out in the coldest reaches 101 00:11:34,640 --> 00:11:35,880 of the solar system… 102 00:11:41,040 --> 00:11:42,720 water crystals were forming 103 00:11:43,680 --> 00:11:46,760 on the surface of dust particles. 104 00:11:54,480 --> 00:11:59,760 Over time, these grains of dust clumped together into asteroids. 105 00:12:01,520 --> 00:12:03,920 Millions and millions of them. 106 00:12:06,080 --> 00:12:09,600 And these became the asteroid belt. 107 00:12:11,240 --> 00:12:14,440 A vast expanse of icy rocks. 108 00:12:17,640 --> 00:12:21,880 Yet they've laid tantalizingly out of Earth's reach. 109 00:12:25,840 --> 00:12:27,680 As luck would have it, however, 110 00:12:28,400 --> 00:12:30,160 a giant was on the move. 111 00:12:39,080 --> 00:12:40,160 Young Jupiter. 112 00:12:41,160 --> 00:12:43,120 A monster of a planet. 113 00:12:48,080 --> 00:12:50,920 Forces within the turbulent inner solar system 114 00:12:51,640 --> 00:12:55,520 were slowly pulling it in toward the Sun. 115 00:13:00,760 --> 00:13:03,880 A flight path that brought it into a collision course 116 00:13:04,760 --> 00:13:06,440 with the asteroid belt. 117 00:13:22,080 --> 00:13:24,560 As it thundered through the asteroids… 118 00:13:28,480 --> 00:13:30,800 …its massive gravitational force 119 00:13:31,800 --> 00:13:34,000 flung rocks in every direction. 120 00:13:41,880 --> 00:13:46,160 And yet, from all this chaos and destruction 121 00:13:46,240 --> 00:13:49,040 came the ultimate cosmic gift. 122 00:13:55,120 --> 00:14:00,760 Icy, water-rich rocks were hurled towards the Earth… 123 00:14:06,360 --> 00:14:11,360 …bringing the promise of life one step closer. 124 00:14:15,720 --> 00:14:17,280 Over billions of years, 125 00:14:17,360 --> 00:14:21,480 asteroids were woven into the fabric of Earth as it formed. 126 00:14:25,680 --> 00:14:29,240 Caught in the turmoil wrought by Jupiter… 127 00:14:30,920 --> 00:14:34,120 …driven deep into the Earth by asteroids, 128 00:14:35,800 --> 00:14:39,800 water molecules did not have an easy journey getting here. 129 00:14:42,760 --> 00:14:45,160 And they still had a long way to go, 130 00:14:46,320 --> 00:14:49,320 imprisoned for millions of years, 131 00:14:50,200 --> 00:14:52,640 locked within Earth's molten core… 132 00:14:55,640 --> 00:14:57,400 waiting for another miracle… 133 00:15:00,600 --> 00:15:01,960 to set them free. 134 00:15:12,040 --> 00:15:15,960 Today, much of Earth's water is still trapped underground. 135 00:15:23,880 --> 00:15:28,120 So elephants have evolved special skills 136 00:15:28,200 --> 00:15:29,240 to find it. 137 00:15:39,400 --> 00:15:41,960 Even the muddy pools are empty. 138 00:15:43,240 --> 00:15:46,120 This dry season has become a full-on drought. 139 00:15:49,560 --> 00:15:51,880 But Pula has a superpower. 140 00:15:54,200 --> 00:15:55,720 Her incredible trunk, 141 00:15:57,240 --> 00:15:59,880 packed with millions of sense receptors… 142 00:16:02,000 --> 00:16:04,440 can smell water from kilometers away… 143 00:16:09,040 --> 00:16:12,880 and pinpoint its sources deep underground. 144 00:16:23,720 --> 00:16:25,080 But you have to dig for it. 145 00:16:33,880 --> 00:16:35,640 Metsi isn't a big digger. 146 00:16:40,840 --> 00:16:43,080 But Bosigo is a natural. 147 00:16:51,520 --> 00:16:54,680 And Metsi is offered a seat at the bar. 148 00:17:00,360 --> 00:17:02,640 These few sips won't last them long. 149 00:17:07,280 --> 00:17:09,880 But if water had stayed trapped in the Earth, 150 00:17:11,520 --> 00:17:13,240 there would be none to drink. 151 00:17:17,800 --> 00:17:19,680 There would be no elephants. 152 00:17:23,200 --> 00:17:25,280 No life at all. 153 00:17:37,800 --> 00:17:41,160 After water was delivered here by asteroids 154 00:17:41,240 --> 00:17:43,480 and consumed by the Earth… 155 00:17:45,640 --> 00:17:48,280 it was locked into the rock as crystals 156 00:17:50,200 --> 00:17:51,800 deep inside the planet. 157 00:17:57,560 --> 00:18:00,160 It stayed buried for millions of years, 158 00:18:01,160 --> 00:18:04,360 beneath a vast sea of magma. 159 00:18:12,920 --> 00:18:17,880 Until slowly but surely, Earth cooled. 160 00:18:21,360 --> 00:18:25,880 And its surface hardened to a thick crust. 161 00:18:29,680 --> 00:18:34,240 Then, finally, the boiling interior broke through. 162 00:18:43,720 --> 00:18:45,600 Enormous volcanoes 163 00:18:47,080 --> 00:18:50,880 blasted gas and vapor kilometers into the sky. 164 00:18:58,720 --> 00:19:01,520 At last, water molecules… 165 00:19:03,000 --> 00:19:04,200 …were set free… 166 00:19:11,080 --> 00:19:13,800 …and formed the first clouds. 167 00:19:18,480 --> 00:19:21,080 Growing and building for millions of years, 168 00:19:21,600 --> 00:19:23,400 becoming laden with water… 169 00:19:28,320 --> 00:19:31,120 …until the temperature dropped just enough… 170 00:19:38,920 --> 00:19:41,480 …for the very first raindrop… 171 00:19:46,920 --> 00:19:50,560 …to form and fall. 172 00:20:08,800 --> 00:20:11,000 What followed was a deluge… 173 00:20:16,240 --> 00:20:18,640 that lasted thousands of years. 174 00:20:30,040 --> 00:20:32,080 Puddles turned into rivers. 175 00:20:41,520 --> 00:20:42,720 Lakes… 176 00:20:44,400 --> 00:20:45,760 …became seas. 177 00:20:53,480 --> 00:20:57,560 And great oceans flooded Earth's surface. 178 00:21:15,920 --> 00:21:20,120 And here, water gave rise to something magical. 179 00:21:25,320 --> 00:21:26,840 The first life. 180 00:21:31,080 --> 00:21:33,680 From these first cells 181 00:21:35,000 --> 00:21:38,040 sprang every living thing. 182 00:21:40,640 --> 00:21:43,960 Water is the fundamental ingredient 183 00:21:44,040 --> 00:21:48,000 of every cell of every creature on Earth. 184 00:21:57,360 --> 00:21:58,440 And today… 185 00:22:01,320 --> 00:22:06,400 the herd still carries this ancient water within them. 186 00:22:18,040 --> 00:22:20,240 It transports nutrients and oxygen. 187 00:22:30,200 --> 00:22:32,000 It powers every heartbeat. 188 00:22:38,920 --> 00:22:41,160 And drives every breath. 189 00:22:46,640 --> 00:22:49,240 Life evolved because of water, 190 00:22:51,000 --> 00:22:54,960 which is why no life can survive without it. 191 00:23:01,920 --> 00:23:05,480 In Botswana, the drought is only getting worse. 192 00:23:11,080 --> 00:23:13,880 The elephants' world is on fire. 193 00:23:22,600 --> 00:23:25,520 The herd manages to escape the burning forest… 194 00:23:29,040 --> 00:23:31,320 but walks straight into a new threat. 195 00:23:37,560 --> 00:23:40,360 In this drought, everyone is suffering… 196 00:23:43,680 --> 00:23:46,160 …from thirst and hunger. 197 00:23:52,600 --> 00:23:56,960 And for lions, baby elephants would satisfy both. 198 00:24:14,200 --> 00:24:17,320 The adults rally around Metsi and Bosigo. 199 00:24:24,720 --> 00:24:26,960 It's enough to keep the threat at bay. 200 00:24:30,680 --> 00:24:32,880 But lions are patient creatures. 201 00:24:36,880 --> 00:24:40,400 And the herd still has to cross an unforgiving wasteland… 202 00:24:42,600 --> 00:24:44,280 before the next water hole. 203 00:24:48,520 --> 00:24:50,680 They need a lifeline. 204 00:24:53,760 --> 00:24:56,040 And the Earth provides it 205 00:24:57,720 --> 00:25:00,120 in the most unexpected of places. 206 00:25:05,320 --> 00:25:08,000 The acacia tree is a beacon of hope. 207 00:25:13,880 --> 00:25:16,800 And a haven for creatures of all kinds. 208 00:25:24,880 --> 00:25:28,320 Its long roots reach much deeper underground 209 00:25:28,400 --> 00:25:30,400 than an elephant could ever dig… 210 00:25:41,240 --> 00:25:43,360 …drawing water up to its branches… 211 00:25:47,360 --> 00:25:48,520 and leaves. 212 00:26:01,000 --> 00:26:04,480 It's just enough water to keep them going. 213 00:26:08,280 --> 00:26:10,840 Especially vital for Metsi's mother, 214 00:26:12,720 --> 00:26:14,320 still nursing her baby. 215 00:26:18,320 --> 00:26:21,800 But this is so much more than just a local oasis. 216 00:26:25,360 --> 00:26:28,480 It's the vital link in water's eternal cycle. 217 00:26:32,720 --> 00:26:36,800 The acacia tree connects ground and sky… 218 00:26:43,600 --> 00:26:46,080 …breathing oxygen and vapor into the air. 219 00:26:55,000 --> 00:26:56,480 Feeding clouds 220 00:26:56,560 --> 00:26:59,320 and powering water's journey around the planet. 221 00:27:07,400 --> 00:27:08,880 Ever since rain 222 00:27:10,120 --> 00:27:12,400 fed the first green shoots… 223 00:27:16,320 --> 00:27:18,840 and gave life to the first tree… 224 00:27:24,120 --> 00:27:27,720 …plants have made our planet habitable… 225 00:27:35,280 --> 00:27:37,680 …bringing a once barren ball of rock 226 00:27:39,440 --> 00:27:40,280 to life. 227 00:27:45,880 --> 00:27:48,760 But the gifts our universe bestows 228 00:27:50,320 --> 00:27:52,760 can also be taken away. 229 00:28:01,280 --> 00:28:02,760 A long time ago, 230 00:28:04,080 --> 00:28:05,680 there was another planet 231 00:28:06,680 --> 00:28:09,480 whose surface was covered in liquid water. 232 00:28:18,080 --> 00:28:20,600 A water world just like ours. 233 00:28:25,720 --> 00:28:28,440 The same forces that delivered water to Earth 234 00:28:29,440 --> 00:28:32,000 also gave it to Mars. 235 00:28:35,200 --> 00:28:37,440 With an atmosphere in place, 236 00:28:37,520 --> 00:28:38,640 clouds formed, 237 00:28:40,480 --> 00:28:41,480 rain fell, 238 00:28:43,000 --> 00:28:44,440 rivers flowed. 239 00:28:48,800 --> 00:28:52,160 And an ocean surged across its surface. 240 00:28:57,240 --> 00:28:59,520 It was a world of possibility. 241 00:29:00,040 --> 00:29:02,320 It had the potential for life. 242 00:29:06,600 --> 00:29:08,080 But it didn't last. 243 00:29:13,720 --> 00:29:19,080 Because not far away was a raging nuclear inferno. 244 00:29:21,040 --> 00:29:22,040 Our Sun. 245 00:29:24,120 --> 00:29:27,520 It unleashes torrents of high-energy particles 246 00:29:27,600 --> 00:29:29,800 so powerful and deadly… 247 00:29:32,480 --> 00:29:34,480 …they can devastate planets. 248 00:29:43,960 --> 00:29:47,840 This solar wind streams through space… 249 00:29:52,320 --> 00:29:55,640 at 400 kilometers per second. 250 00:30:00,480 --> 00:30:03,160 And it ripped through the Martian atmosphere, 251 00:30:04,640 --> 00:30:06,800 tearing water molecules apart. 252 00:30:15,040 --> 00:30:16,520 Bit by bit, 253 00:30:16,600 --> 00:30:18,160 over millions of years, 254 00:30:19,600 --> 00:30:24,480 the planet's protective layer was stripped away by the Sun's fury… 255 00:30:29,680 --> 00:30:31,640 …until its ocean evaporated… 256 00:30:37,640 --> 00:30:41,040 and its water was lost to space. 257 00:30:48,600 --> 00:30:52,400 Mars became a desolate, frozen shadow 258 00:30:52,920 --> 00:30:54,280 of its former self. 259 00:31:03,360 --> 00:31:05,920 Consumed by dust storms. 260 00:31:12,520 --> 00:31:14,480 Any chance of complex life… 261 00:31:16,480 --> 00:31:18,280 gone forever. 262 00:31:27,560 --> 00:31:29,640 This could have been our story too. 263 00:31:44,360 --> 00:31:46,640 But somehow, on Earth, 264 00:31:47,560 --> 00:31:51,280 water and life have found a way to cling on. 265 00:32:06,320 --> 00:32:07,960 In Botswana, 266 00:32:08,040 --> 00:32:10,640 after 200 days in the burning sun… 267 00:32:12,840 --> 00:32:15,000 …there is no water to be found. 268 00:32:23,680 --> 00:32:26,040 Violent winds whip the scorched earth 269 00:32:26,120 --> 00:32:27,600 into a dust bowl. 270 00:32:45,320 --> 00:32:49,440 And the elephants' struggle hasn't gone unnoticed. 271 00:33:02,920 --> 00:33:06,800 In daylight, adults can usually protect their young. 272 00:33:18,240 --> 00:33:19,800 But when night falls… 273 00:33:25,480 --> 00:33:26,920 …it's a different story. 274 00:33:37,520 --> 00:33:40,400 Lions are masters of chaos and confusion. 275 00:33:53,440 --> 00:33:55,880 They pick the most vulnerable target… 276 00:34:00,800 --> 00:34:02,120 …working as a pack… 277 00:34:08,200 --> 00:34:10,280 …until there's nowhere left to run. 278 00:34:27,240 --> 00:34:29,600 Without the entire herd as protection, 279 00:34:30,960 --> 00:34:34,080 the lions overwhelm their prey. 280 00:34:36,880 --> 00:34:40,600 The drought and endless search for food and water 281 00:34:41,440 --> 00:34:44,880 have taken their ultimate toll on Bosigo. 282 00:34:55,040 --> 00:34:58,240 Elephants form deep emotional bonds. 283 00:35:09,920 --> 00:35:13,080 All the family mourn Bosigo's loss. 284 00:35:30,480 --> 00:35:32,840 The herd gathers to comfort Metsi, 285 00:35:34,680 --> 00:35:36,960 who feels it hardest of all. 286 00:35:48,480 --> 00:35:50,720 The never-ending fight to survive 287 00:35:50,800 --> 00:35:52,480 plays out every year, 288 00:35:54,280 --> 00:35:55,720 across the Okavango… 289 00:35:58,000 --> 00:35:59,280 across our planet… 290 00:36:01,960 --> 00:36:03,040 and beyond. 291 00:36:07,080 --> 00:36:09,560 But in this battle for survival, 292 00:36:10,440 --> 00:36:12,000 Earth got truly lucky… 293 00:36:14,000 --> 00:36:17,440 with a secret guardian that protects it. 294 00:36:24,360 --> 00:36:25,480 Deep within… 295 00:36:28,520 --> 00:36:32,280 …the planet's raging molten furnace burns 296 00:36:32,920 --> 00:36:33,920 and churns… 297 00:36:37,840 --> 00:36:40,240 …generating a powerful magnetic field 298 00:36:41,920 --> 00:36:44,360 that extends from the heart of the planet… 299 00:36:46,160 --> 00:36:50,680 …65,000 kilometers out towards the Sun. 300 00:36:52,600 --> 00:36:55,880 A vital force field defending Earth… 301 00:36:58,320 --> 00:37:01,040 …from the same savage solar winds 302 00:37:02,080 --> 00:37:04,040 that stripped water from Mars. 303 00:37:10,480 --> 00:37:13,920 Defeating them before they hit our atmosphere. 304 00:37:26,520 --> 00:37:28,760 Safeguarding our essential water. 305 00:37:30,520 --> 00:37:34,160 Hugging every drop close to our planet. 306 00:37:41,040 --> 00:37:43,960 This is what makes our pale blue dot 307 00:37:44,480 --> 00:37:46,160 unlike anywhere else. 308 00:37:49,520 --> 00:37:52,920 A place where life can thrive. 309 00:37:56,960 --> 00:37:59,080 Bringing relief to the elephants. 310 00:38:01,600 --> 00:38:04,880 Ensuring rains return each year without fail. 311 00:38:09,680 --> 00:38:14,000 In the distance, storm clouds are building. 312 00:38:29,200 --> 00:38:33,800 Elephants can detect the low-frequency rumble of thunder 313 00:38:33,880 --> 00:38:36,480 from 240 kilometers away. 314 00:38:43,400 --> 00:38:47,880 And it's telling them it's time to return to the Okavango. 315 00:38:56,600 --> 00:38:58,440 From the highlands of Angola, 316 00:39:00,200 --> 00:39:03,080 water is weaving its way through Botswana… 317 00:39:12,000 --> 00:39:14,280 …to rejuvenate the delta… 318 00:39:22,640 --> 00:39:24,720 with the kiss of life. 319 00:39:34,480 --> 00:39:37,480 Every step that brings the herd closer to home… 320 00:39:40,760 --> 00:39:45,280 is a continuation of a much larger cosmic odyssey. 321 00:39:51,640 --> 00:39:57,280 From tiny molecules hitching a ride on dust beyond Jupiter… 322 00:40:03,000 --> 00:40:05,800 to surviving the crushing heat of early Earth. 323 00:40:13,680 --> 00:40:16,160 Imprisoned in the planet's core… 324 00:40:18,200 --> 00:40:19,880 …then set free… 325 00:40:21,240 --> 00:40:23,080 …to sow the seeds of life… 326 00:40:27,360 --> 00:40:31,880 …every drop of water has an amazing tale to tell. 327 00:40:34,640 --> 00:40:36,000 Every molecule… 328 00:40:36,080 --> 00:40:39,120 -…a link in an unbroken chain… 329 00:40:40,440 --> 00:40:43,400 …cycling over tens of thousands of years… 330 00:40:46,480 --> 00:40:47,800 …through air… 331 00:40:50,840 --> 00:40:51,800 oceans… 332 00:40:55,680 --> 00:40:56,560 rocks… 333 00:41:04,800 --> 00:41:05,960 …and elephants. 334 00:41:11,680 --> 00:41:16,040 After eight months and hundreds of kilometers, 335 00:41:17,720 --> 00:41:21,520 Metsi and her family have finally reached 336 00:41:21,600 --> 00:41:24,960 the life-giving waters of the delta. 337 00:41:38,040 --> 00:41:41,640 It's well past time to drink… 338 00:41:43,880 --> 00:41:45,080 and play. 339 00:41:47,440 --> 00:41:50,160 And then, drink some more. 340 00:41:59,560 --> 00:42:02,040 And show the newest member of the family… 341 00:42:06,360 --> 00:42:09,200 …how they do things in the delta. 342 00:42:22,360 --> 00:42:25,360 Metsi and her new baby cousin 343 00:42:25,440 --> 00:42:28,240 are the latest in a long line 344 00:42:28,320 --> 00:42:31,560 to benefit from water's miraculous arrival 345 00:42:32,800 --> 00:42:33,720 on this planet. 346 00:42:44,480 --> 00:42:46,440 They will forever be connected 347 00:42:46,520 --> 00:42:47,880 to the universe 348 00:42:48,800 --> 00:42:52,280 that gave our planet this magic ingredient 349 00:42:54,040 --> 00:42:59,920 and gave us the ability to preserve and treasure it. 350 00:43:10,840 --> 00:43:15,120 Next, the story of our universe concludes… 351 00:43:16,280 --> 00:43:22,160 …with the force that brings everything we've seen so far together. 352 00:43:23,560 --> 00:43:26,320 The great sculptor of the cosmos, 353 00:43:26,960 --> 00:43:27,800 gravity. 354 00:43:29,160 --> 00:43:32,520 It's a force of attraction that built our planet. 355 00:43:35,560 --> 00:43:39,160 And we'll bring two penguins together at Earth's southern pole. 356 00:43:41,040 --> 00:43:44,120 But when did gravity start exerting its influence? 357 00:43:45,680 --> 00:43:50,080 How does it create both order and chaos? 358 00:43:52,920 --> 00:43:57,640 And why does it make ours the perfect planet for life… 359 00:43:59,920 --> 00:44:00,920 …and love?