1 00:00:03,300 --> 00:00:09,460 2 00:00:37,080 --> 00:00:38,990 North Africa. 3 00:00:56,840 --> 00:01:00,040 High in Morocco's Atlas Mountains, 4 00:01:00,360 --> 00:01:04,270 Barbary macaques shiver in the icy cedars. 5 00:01:05,480 --> 00:01:08,120 6 00:01:13,920 --> 00:01:17,880 The ancestors of these monkeys fled here from a disaster 7 00:01:17,960 --> 00:01:20,430 that overwhelmed their homeland. 8 00:01:22,600 --> 00:01:26,040 Now, trapped in this isolated corner of Africa, 9 00:01:26,480 --> 00:01:29,600 there's no going back to the land farther south. 10 00:01:32,840 --> 00:01:34,830 Even in this snowy refuge, 11 00:01:35,080 --> 00:01:37,910 there's a reminder of what drove them here. 12 00:01:43,880 --> 00:01:47,630 The unbridled power of the African sun. 13 00:01:55,320 --> 00:01:59,760 Under its intense gaze, the snow can't last for long. 14 00:02:06,400 --> 00:02:10,440 Meltwater should bring life to the lowlands. 15 00:02:13,360 --> 00:02:16,910 Hundreds of torrents cascade southwards. 16 00:02:19,040 --> 00:02:23,080 But each is flowing towards extinction. 17 00:02:27,720 --> 00:02:30,630 Just 200 miles south of the mountains, 18 00:02:30,720 --> 00:02:33,360 the rivers are vaporised. 19 00:02:39,840 --> 00:02:42,960 Life has been burnt off the land. 20 00:02:51,080 --> 00:02:55,550 This was the apocalypse from which the Barbary macaques fled, 21 00:02:57,200 --> 00:03:00,110 the sudden and unstoppable advance 22 00:03:00,280 --> 00:03:03,160 of the greatest desert on the planet. 23 00:03:05,020 --> 00:03:11,780 24 00:03:15,640 --> 00:03:18,600 The Sahara transformed North Africa. 25 00:03:20,480 --> 00:03:24,470 Today, it covers an area the size of the United States, 26 00:03:24,560 --> 00:03:27,870 one-third of the entire African continent. 27 00:03:33,600 --> 00:03:37,480 This is one of the hottest places on Earth. 28 00:03:45,400 --> 00:03:47,360 The merciless sun, 29 00:03:47,440 --> 00:03:50,990 a colossal 15-million-degree nuclear reactor, 30 00:03:51,720 --> 00:03:54,840 blasted life from the surface of the land. 31 00:03:58,600 --> 00:04:00,510 It still wreaks havoc. 32 00:04:00,840 --> 00:04:04,470 A faint breath of wind can be the beginning of disaster. 33 00:04:16,000 --> 00:04:18,430 34 00:04:50,320 --> 00:04:54,600 Nomads tell of entire villages being engulfed, 35 00:04:55,640 --> 00:04:57,630 camel trains disappearing, 36 00:04:58,000 --> 00:05:01,710 and people buried alive inside their tents. 37 00:05:09,320 --> 00:05:11,520 38 00:05:52,080 --> 00:05:56,200 A sandstorm can be a thousand miles across. 39 00:06:00,080 --> 00:06:04,710 It seems miraculous that anything can survive such devastation. 40 00:06:09,040 --> 00:06:13,030 The Saharan apocalypse wiped out many creatures, 41 00:06:13,720 --> 00:06:16,600 but today, some still cling on 42 00:06:16,680 --> 00:06:19,990 in the lands around the margins of the great desert. 43 00:06:24,200 --> 00:06:25,920 It's very dry here. 44 00:06:26,840 --> 00:06:29,910 Some years, the rains fail entirely. 45 00:06:39,360 --> 00:06:42,000 A lone Grevy's zebra. 46 00:06:44,680 --> 00:06:46,990 He weighs close to half a tonne, 47 00:06:47,320 --> 00:06:50,360 and can go for three days without drinking. 48 00:06:55,880 --> 00:07:01,030 Like the macaques, his forebears were refugees from the advancing Sahara. 49 00:07:03,480 --> 00:07:05,520 50 00:07:06,240 --> 00:07:08,960 The land is scrubby and dry. 51 00:07:10,040 --> 00:07:11,440 52 00:07:11,520 --> 00:07:12,790 53 00:07:14,000 --> 00:07:16,910 But this stallion has claimed it as his own. 54 00:07:19,480 --> 00:07:22,280 He's been waiting months for visitors. 55 00:07:23,200 --> 00:07:24,790 Female visitors. 56 00:07:33,440 --> 00:07:37,120 If they like his territory, they might stay a while. 57 00:07:42,160 --> 00:07:46,200 It's his first chance to mate for a very long time. 58 00:07:50,840 --> 00:07:52,910 59 00:07:59,840 --> 00:08:01,560 Hardly a success. 60 00:08:03,680 --> 00:08:07,590 Perhaps his visitors are looking for a more impressive partner. 61 00:08:10,400 --> 00:08:12,360 There's another setback. 62 00:08:14,240 --> 00:08:16,470 The females were being followed. 63 00:08:16,560 --> 00:08:20,470 A posse of young males - every one a rival. 64 00:08:26,760 --> 00:08:30,120 It's time to separate the men from the boys. 65 00:08:45,640 --> 00:08:47,310 66 00:08:55,440 --> 00:08:59,270 One by one, the stallion sees them off. 67 00:09:22,680 --> 00:09:25,430 The females had ringside seats. 68 00:09:27,520 --> 00:09:30,590 And his prowess has not gone un-noted. 69 00:09:37,720 --> 00:09:40,870 Machismo gives way to tenderness. 70 00:09:58,200 --> 00:10:01,480 Around here, you have to take every opportunity, 71 00:10:01,720 --> 00:10:05,190 be it for food, for water, or for mates. 72 00:10:16,080 --> 00:10:19,200 Female Grevy's are a fickle bunch. 73 00:10:19,280 --> 00:10:21,670 The herd have decided to move on. 74 00:10:23,360 --> 00:10:24,760 All of them. 75 00:10:26,720 --> 00:10:29,360 The stallion may never see them again. 76 00:10:29,800 --> 00:10:33,760 But there's a chance that one is now carrying his foal. 77 00:10:36,440 --> 00:10:40,480 In this harsh land, that must count as a triumph. 78 00:10:49,440 --> 00:10:53,670 The sun's power cannot, however, reach far underground. 79 00:10:55,960 --> 00:11:00,800 Below, in stark contrast, conditions are stable and tolerable. 80 00:11:03,480 --> 00:11:07,270 And home to one of the planet's strangest mammals. 81 00:11:11,200 --> 00:11:13,950 Meet the naked mole rats. 82 00:11:20,240 --> 00:11:25,520 These sabre-toothed sausages wouldn't last a day in the desert. 83 00:11:27,000 --> 00:11:29,230 Special filming tunnels allow us to see 84 00:11:29,320 --> 00:11:32,150 how well adapted they are to the subterranean life. 85 00:11:32,800 --> 00:11:35,270 They can run equally well in both directions, 86 00:11:35,360 --> 00:11:37,670 so tight space is no problem. 87 00:11:42,720 --> 00:11:44,710 They have lost their fur. 88 00:11:46,520 --> 00:11:50,200 And most bizarrely, they live in social colonies, 89 00:11:50,280 --> 00:11:52,710 much like termites or ants. 90 00:11:56,840 --> 00:12:00,880 After time spent digging, the workers come together to relax. 91 00:12:12,920 --> 00:12:16,670 But one here is very different from all the rest. 92 00:12:18,800 --> 00:12:20,200 Their queen, 93 00:12:21,680 --> 00:12:23,880 twice as heavy as her subjects, 94 00:12:24,320 --> 00:12:27,120 and not afraid to throw her weight around. 95 00:12:31,160 --> 00:12:34,360 She is the mother of every worker in the colony, 96 00:12:34,480 --> 00:12:37,950 and exists in a near-continuous state of pregnancy. 97 00:12:41,040 --> 00:12:45,830 Even now, two dozen babies are pulsating within her swollen belly. 98 00:12:51,840 --> 00:12:56,040 Just occasionally, one of her brood is raised differently, 99 00:12:57,680 --> 00:13:00,480 a daughter becomes a princess. 100 00:13:04,120 --> 00:13:08,480 Until now, this youngster's enjoyed a lazy, privileged life. 101 00:13:09,360 --> 00:13:11,320 But not for much longer. 102 00:13:16,640 --> 00:13:19,000 She has a destiny to fulfil. 103 00:13:26,840 --> 00:13:31,280 The surface is a place where no naked mole rat can survive for long. 104 00:13:39,040 --> 00:13:42,920 But a princess will risk everything to search for a partner. 105 00:13:52,360 --> 00:13:54,270 The quest is urgent. 106 00:14:02,200 --> 00:14:04,870 There's an enticing smell in the air. 107 00:14:14,040 --> 00:14:17,640 A seductive scent draws her downwards, to safety. 108 00:14:30,000 --> 00:14:32,230 She's sniffed out a partner. 109 00:14:35,600 --> 00:14:37,400 He too is alone, 110 00:14:37,480 --> 00:14:40,840 and eager to start a new colony in his lonely burrow. 111 00:14:44,720 --> 00:14:48,350 Two months later, the princess has become a queen. 112 00:14:48,480 --> 00:14:51,390 And a new tyranny begins. 113 00:14:59,160 --> 00:15:02,630 Tough though they are, such refugees 114 00:15:02,720 --> 00:15:05,000 living on the edges of North Africa 115 00:15:05,080 --> 00:15:08,710 cannot survive in the heart of the Sahara. 116 00:15:13,200 --> 00:15:15,790 And yet here, in southern Nigeria, 117 00:15:15,920 --> 00:15:17,910 there are creatures preparing to journey 118 00:15:18,000 --> 00:15:21,070 right across the centre of that great desert. 119 00:15:26,200 --> 00:15:27,790 Barn swallows. 120 00:15:32,960 --> 00:15:34,920 121 00:15:36,160 --> 00:15:40,120 They've spent the winter roosting in a forest of elephant grass. 122 00:15:42,400 --> 00:15:45,200 But now, it is time for them to leave. 123 00:15:50,480 --> 00:15:52,950 All two million of them. 124 00:16:15,840 --> 00:16:20,040 They're tiny, each weighing the same as a couple of one-pound coins, 125 00:16:21,480 --> 00:16:23,840 yet the journey to their breeding grounds in Europe 126 00:16:23,920 --> 00:16:26,430 is over 3,000 miles long. 127 00:16:29,040 --> 00:16:32,350 Ahead of them lies a vast death trap. 128 00:16:35,760 --> 00:16:38,400 The Sahara is too large to go around. 129 00:16:39,080 --> 00:16:43,310 The swallows have no choice but to meet it head-on. 130 00:16:54,800 --> 00:16:58,080 It will take one of nature's greatest feats of navigation 131 00:16:58,160 --> 00:17:00,830 to cross this lifeless wasteland. 132 00:17:02,920 --> 00:17:06,750 A wilderness that stretches not just to the horizon, 133 00:17:07,440 --> 00:17:10,030 but almost beyond imagination. 134 00:17:19,000 --> 00:17:22,680 It's an immense blank space on the map. 135 00:17:30,200 --> 00:17:32,760 In spite of the Sahara's reputation, 136 00:17:33,080 --> 00:17:35,510 less than one-fifth of it is sand. 137 00:17:38,520 --> 00:17:42,750 The rest is stone and wind-scoured rock. 138 00:17:52,640 --> 00:17:55,470 The sun not only bakes the land, 139 00:17:56,280 --> 00:17:58,750 it warps its appearance. 140 00:18:02,000 --> 00:18:05,790 The super-heated air, rising upward from the desert surface, 141 00:18:05,920 --> 00:18:07,990 distorts the distant scene. 142 00:18:12,320 --> 00:18:15,710 A reflection of the sky shimmers on the sands, 143 00:18:16,240 --> 00:18:17,510 a mirage. 144 00:18:23,560 --> 00:18:26,120 The sun is an illusionist. 145 00:18:30,280 --> 00:18:33,510 To thirsty travellers, a mirage can resemble a lake 146 00:18:33,600 --> 00:18:37,280 which agonisingly recedes as it's approached. 147 00:18:45,640 --> 00:18:48,550 And swaying camels coming to the rescue 148 00:18:48,640 --> 00:18:53,000 transform into dry, spiny acacia trees. 149 00:19:03,600 --> 00:19:07,040 To cross this confused, shimmering landscape, 150 00:19:07,200 --> 00:19:11,990 many swallows will need to find real water amongst the mirages. 151 00:19:19,160 --> 00:19:23,120 Even in the Sahara, rain does sometimes fall 152 00:19:23,560 --> 00:19:26,630 and that is sufficient for plants to survive, 153 00:19:26,720 --> 00:19:29,710 providing they have the right adaptations. 154 00:19:30,960 --> 00:19:35,270 Rising from the sand, a dried-out ball of twigs. 155 00:19:42,800 --> 00:19:45,790 In strong winds, it can travel. 156 00:20:02,800 --> 00:20:06,000 This plant may have been dead for 100 years. 157 00:20:09,960 --> 00:20:13,270 Yet its name suggests that all is not lost, 158 00:20:13,840 --> 00:20:16,720 for this is a resurrection plant. 159 00:20:24,320 --> 00:20:28,440 Around here, rain might only fall once or twice a year. 160 00:20:32,120 --> 00:20:36,110 But if you're searching for decades, that might be enough. 161 00:20:43,440 --> 00:20:48,470 Dead limbs absorb water and unfurl in a matter of minutes. 162 00:20:51,160 --> 00:20:54,760 But the resurrection plant needs one more miracle. 163 00:20:57,480 --> 00:20:59,630 164 00:21:02,120 --> 00:21:04,920 Rain must fall on its branches 165 00:21:05,000 --> 00:21:07,560 before they dry out and close up again. 166 00:22:05,800 --> 00:22:08,920 Within hours, shoots emerge. 167 00:22:24,880 --> 00:22:26,790 In just a few weeks, 168 00:22:26,880 --> 00:22:30,000 they flower and develop seeds of their own. 169 00:22:37,280 --> 00:22:40,000 Then, before they can grow any larger, 170 00:22:40,080 --> 00:22:42,590 the sun kills them. 171 00:22:47,840 --> 00:22:51,830 But their seeds live on, ready for when the rains return, 172 00:22:52,280 --> 00:22:55,320 even if that is a century from now. 173 00:22:59,520 --> 00:23:02,110 North Africa wasn't always so brutal. 174 00:23:02,920 --> 00:23:06,120 Scattered across the Sahara are glimpses of life 175 00:23:06,200 --> 00:23:09,030 before the apocalypse swept over the land. 176 00:23:13,160 --> 00:23:17,230 In the north, a petrified forest, trees turned to stone. 177 00:23:17,320 --> 00:23:20,520 Remains from a far distant, wetter past. 178 00:23:25,320 --> 00:23:29,710 White sediments in the heart of the Sahara are the dried-out remains 179 00:23:29,800 --> 00:23:33,000 of what was once the world's largest lake. 180 00:23:36,760 --> 00:23:40,670 In the east, ruined cities hark back to a time of plenty. 181 00:23:48,680 --> 00:23:53,310 And here, deep inside Libya, is Messak Settafet. 182 00:23:58,200 --> 00:24:01,560 Carved here are hundreds of images of animals, 183 00:24:02,480 --> 00:24:04,470 all drawn from life. 184 00:24:08,280 --> 00:24:11,190 Ghosts from a greener time. 185 00:24:16,280 --> 00:24:21,400 Remarkably, a remnant of this old North Africa survives. 186 00:24:25,880 --> 00:24:31,080 Bou-Hedma in Tunisia is sustained by mountain rains. 187 00:24:35,720 --> 00:24:39,510 It's a relic of the savannah that once carpeted North Africa. 188 00:24:51,920 --> 00:24:54,070 The vast grassland vanished 189 00:24:54,160 --> 00:24:58,070 when a shift in the Earth's orbit drove the rains south, 190 00:24:58,880 --> 00:25:01,440 and in perhaps only a matter of centuries, 191 00:25:01,520 --> 00:25:04,830 the Sahara Desert overwhelmed North Africa. 192 00:25:09,320 --> 00:25:13,550 The evidence suggests this took place around 6,000 years ago. 193 00:25:13,840 --> 00:25:16,800 In evolutionary terms, that's no time at all. 194 00:25:17,000 --> 00:25:20,990 And life has had little chance to adapt to this new world. 195 00:25:27,680 --> 00:25:30,270 Only a few tough specialists 196 00:25:30,360 --> 00:25:33,240 can cope with life amongst the dunes. 197 00:25:51,560 --> 00:25:55,110 Camels are sometimes called ships of the desert. 198 00:25:55,280 --> 00:25:58,960 But, like the swallows, they're really only visitors here. 199 00:26:00,440 --> 00:26:03,400 These ships can certainly cross the Sahara, 200 00:26:03,480 --> 00:26:07,630 but even they can't make their home in the harshest places. 201 00:26:12,680 --> 00:26:17,390 Left to wander the desert by themselves, camels would not survive. 202 00:26:18,080 --> 00:26:22,790 They depend on their human navigators to find oases and wells. 203 00:26:29,680 --> 00:26:33,310 Saharan folklore is full of tales of caravans 204 00:26:33,440 --> 00:26:37,480 that missed a well by a few hundred metres and disappeared. 205 00:26:52,360 --> 00:26:56,040 This is the White Desert, in Egypt. 206 00:27:01,240 --> 00:27:05,230 The landscape is littered with giant chalk pillars, 207 00:27:05,840 --> 00:27:09,120 carved by innumerable sandstorms. 208 00:27:13,440 --> 00:27:17,720 This glaring white oven is lethally hot. 209 00:27:20,440 --> 00:27:23,400 Food here is almost non-existent. 210 00:27:26,800 --> 00:27:29,790 But there's a rare gift from a passing camel. 211 00:27:30,160 --> 00:27:34,280 The smell has lured dung beetles from miles around. 212 00:27:36,200 --> 00:27:39,110 For them, this is manna from heaven. 213 00:27:46,200 --> 00:27:49,160 One dung ball could provide enough food 214 00:27:49,240 --> 00:27:52,360 to last this female beetle the rest of her life. 215 00:27:54,680 --> 00:27:56,350 But she has a problem. 216 00:27:57,400 --> 00:28:00,840 To keep it fresh, she must bury it in moist ground. 217 00:28:01,680 --> 00:28:03,830 And that's not easy to find. 218 00:28:12,560 --> 00:28:15,760 The temperature has already risen 10 degrees. 219 00:28:21,960 --> 00:28:24,760 This lizard avoids the roasting sand. 220 00:28:26,200 --> 00:28:30,720 Only 30 centimetres above the surface, it's significantly cooler. 221 00:28:39,280 --> 00:28:43,350 The reverse-pushing technique is certainly the fastest way 222 00:28:43,520 --> 00:28:45,510 to keep the ball rolling. 223 00:28:50,680 --> 00:28:53,190 But it does have one drawback. 224 00:29:01,840 --> 00:29:04,230 You can't see where you're going. 225 00:29:08,680 --> 00:29:10,000 Disaster! 226 00:29:11,440 --> 00:29:14,000 Stuck between two dunes. 227 00:29:22,600 --> 00:29:24,880 The dung ball is twice her weight, 228 00:29:24,960 --> 00:29:28,560 but the urge to keep pushing is inextinguishable. 229 00:30:12,920 --> 00:30:16,360 Now, it's 41 degrees Celsius. 230 00:30:16,760 --> 00:30:19,150 Soon, she'll be baked alive. 231 00:30:23,840 --> 00:30:29,680 Her survival instinct, in the end, overrides her love for dung. 232 00:30:29,920 --> 00:30:31,510 233 00:30:41,040 --> 00:30:43,600 Much of the Sahara is uninhabitable, 234 00:30:43,680 --> 00:30:47,880 but there are rare places where there is some possibility of survival. 235 00:30:47,960 --> 00:30:52,560 Places where, by strange chance, there is water. 236 00:30:56,960 --> 00:31:00,750 Waw an-Namus is an extinct volcano. 237 00:31:01,240 --> 00:31:06,470 From space, it's a remote, black scar on the Libyan Sahara. 238 00:31:13,680 --> 00:31:18,990 Yet there are other colours here, colours rarely seen on the desert floor. 239 00:31:21,400 --> 00:31:24,680 Blue and green. 240 00:31:37,400 --> 00:31:41,190 Rain fell thousands of years ago when the Sahara was green 241 00:31:41,440 --> 00:31:44,190 and percolated deep into the ground. 242 00:31:45,680 --> 00:31:51,550 And here water from this vast, ancient reservoir rises to the surface. 243 00:31:53,960 --> 00:31:58,510 These pools offer another glimpse of the Sahara's past. 244 00:32:05,000 --> 00:32:07,430 Wherever there's water in North Africa, 245 00:32:07,520 --> 00:32:11,830 living relics from this wetter time have a chance to cling on. 246 00:32:15,640 --> 00:32:20,160 This oasis is fed by a hot volcanic spring. 247 00:32:26,080 --> 00:32:28,720 Slightly away from the stream of near-boiling water, 248 00:32:28,800 --> 00:32:32,080 it's cooler and fish can live. 249 00:32:32,640 --> 00:32:34,630 These are Tilapia. 250 00:32:37,360 --> 00:32:40,000 Hatchlings stick close to their mother. 251 00:32:40,520 --> 00:32:43,990 There are other dangers here beside the scalding water. 252 00:32:49,240 --> 00:32:51,710 Particularly at night. 253 00:33:02,080 --> 00:33:05,040 The crocodiles are stealthy. 254 00:33:13,800 --> 00:33:18,560 And the Tilapia are almost blind in the darkness. 255 00:33:23,520 --> 00:33:27,310 In panic, they all leap to escape the hunter's approach. 256 00:33:34,560 --> 00:33:38,160 But this female can't abandon her brood. 257 00:33:46,120 --> 00:33:49,870 The crocodiles won't be thwarted. They, too, can leap. 258 00:34:34,640 --> 00:34:39,080 With first light, the crocodiles lose the element of surprise, 259 00:34:39,160 --> 00:34:41,520 and the battle is over for now. 260 00:34:43,520 --> 00:34:47,800 The mother fish has survived, but where are her young? 261 00:34:52,480 --> 00:34:54,600 All present and correct. 262 00:34:55,720 --> 00:34:59,190 They spent the whole night sheltering in her mouth. 263 00:35:00,720 --> 00:35:03,710 The contest will be repeated at sunset. 264 00:35:04,720 --> 00:35:06,870 There is nowhere else to go. 265 00:35:12,640 --> 00:35:15,950 Oases are always sought by desert travellers 266 00:35:16,040 --> 00:35:18,630 but not all are as they seem. 267 00:35:26,240 --> 00:35:30,470 This is the great Ubari Sand Sea, 268 00:35:30,560 --> 00:35:32,760 in the heart of the Sahara. 269 00:35:36,680 --> 00:35:42,600 These swallows have travelled 1,500 miles since they left Nigeria. 270 00:35:44,920 --> 00:35:49,230 Their superb powers of navigation will eventually guide them to Europe, 271 00:35:49,320 --> 00:35:51,960 but now they, and other thirsty migrants, 272 00:35:52,040 --> 00:35:56,910 need to find a speck of blue amidst this ocean of sand. 273 00:35:57,200 --> 00:35:58,840 274 00:36:01,760 --> 00:36:04,350 And here it is, 275 00:36:04,440 --> 00:36:06,190 Umm al-Maa. 276 00:36:14,800 --> 00:36:19,000 Here, too, ancient groundwater wells up to the surface. 277 00:36:33,320 --> 00:36:34,640 278 00:36:38,520 --> 00:36:40,830 But the birds need to be careful, 279 00:36:41,160 --> 00:36:44,520 for the sun has played a terrible trick. 280 00:36:52,200 --> 00:36:55,670 This oasis is poisonous. 281 00:36:58,080 --> 00:37:00,830 Intense evaporation over thousands of years 282 00:37:00,920 --> 00:37:04,230 has left the water saltier than the sea. 283 00:37:06,880 --> 00:37:08,630 As if to underline the horror, 284 00:37:08,720 --> 00:37:13,030 the place is infested by vast swarms of flies. 285 00:37:13,120 --> 00:37:14,710 286 00:37:17,600 --> 00:37:20,590 But this plague is the birds' salvation. 287 00:37:25,160 --> 00:37:30,000 The flies are filled with freshwater, filtered from the brine. 288 00:37:36,400 --> 00:37:40,190 So, like a desert wanderer squeezing a drink from a cactus, 289 00:37:40,320 --> 00:37:44,840 the birds get all the water they need from the flies' bodies. 290 00:37:52,680 --> 00:37:55,510 More and more migrants join in. 291 00:37:58,320 --> 00:37:59,470 Wagtails. 292 00:38:00,920 --> 00:38:02,560 293 00:38:15,160 --> 00:38:18,950 This is the birds' only stopover. 294 00:38:19,160 --> 00:38:25,000 It gives them enough fuel to escape from the Sahara and Africa. 295 00:38:28,440 --> 00:38:34,070 Away from an oasis, it seems remarkable that anything can live at all. 296 00:38:38,480 --> 00:38:42,920 The temperature of the sands can exceed 70 degrees Celsius. 297 00:38:44,960 --> 00:38:48,840 There's not the slightest trace of water left at the surface. 298 00:38:54,680 --> 00:38:59,280 And when that happens, the Sahara itself cries out. 299 00:39:01,800 --> 00:39:03,950 300 00:39:35,000 --> 00:39:38,360 Billions of sliding grains generate a hum 301 00:39:38,440 --> 00:39:41,350 that echoes across miles of empty desert. 302 00:39:42,920 --> 00:39:47,760 These are the Sahara's legendary singing dunes. 303 00:39:49,280 --> 00:39:50,600 304 00:40:13,440 --> 00:40:16,510 Over time, these avalanches add up. 305 00:40:20,680 --> 00:40:25,600 If you watch the dunes for long enough, something remarkable is revealed. 306 00:40:28,480 --> 00:40:32,310 One and a half years flash past in a matter of seconds. 307 00:40:41,760 --> 00:40:45,800 On this timescale, the dunes are like a stormy sea. 308 00:40:52,760 --> 00:40:56,590 An unstoppable tsunami of sand. 309 00:41:04,600 --> 00:41:07,350 In this immense, ever-shifting landscape, 310 00:41:07,440 --> 00:41:10,670 it's easy to see how a lost traveller could succumb 311 00:41:10,760 --> 00:41:14,960 to what's been called the Sahara's only endemic disease - 312 00:41:16,120 --> 00:41:17,600 madness. 313 00:41:35,800 --> 00:41:39,190 Can anything survive the North African desert 314 00:41:39,280 --> 00:41:42,080 when the sun is at its fiercest? 315 00:41:48,160 --> 00:41:50,750 It's approaching midday. 316 00:41:51,680 --> 00:41:54,560 A fringe-toed lizard is hungry. 317 00:41:55,800 --> 00:41:57,760 He's on a stakeout. 318 00:42:06,360 --> 00:42:10,590 Flashy scales reflect some of the sun's rays. 319 00:42:12,400 --> 00:42:15,950 Nevertheless, the heat is almost unbearable. 320 00:42:20,120 --> 00:42:23,670 His prey hasn't left home all day. 321 00:42:35,680 --> 00:42:40,520 The lizard is the last animal still out on the dunes. 322 00:42:44,480 --> 00:42:47,070 But even he can't take it any more. 323 00:42:48,760 --> 00:42:52,040 To survive longer, you'd need a spacesuit. 324 00:42:55,880 --> 00:42:59,950 And in a way, that's what these insects have. 325 00:43:03,160 --> 00:43:07,150 Silver ants' armoured skin reflects light. 326 00:43:07,440 --> 00:43:11,880 They can tolerate temperatures that would kill any other land animal. 327 00:43:14,000 --> 00:43:19,280 Even so, they can only survive for less than 10 minutes in the midday sun. 328 00:43:28,680 --> 00:43:30,030 Time is precious. 329 00:43:31,480 --> 00:43:35,840 The ants race to find food as soon as their predators go to ground. 330 00:43:44,760 --> 00:43:47,670 They can't afford to waste a second getting lost, 331 00:43:48,040 --> 00:43:51,350 so they spin to take a bearing from the sun. 332 00:43:52,400 --> 00:43:55,840 They log every change of direction, every footstep 333 00:43:55,920 --> 00:43:59,990 in order to know exactly where they are and where their nest lies. 334 00:44:06,280 --> 00:44:09,910 Only four minutes to spare and they've found a victim of heat stroke. 335 00:44:11,560 --> 00:44:12,750 A meal. 336 00:44:16,200 --> 00:44:19,480 But it's going to take a monumental effort to get it home. 337 00:44:34,040 --> 00:44:37,790 Three minutes to go and they're nearing their maximum temperature, 338 00:44:37,880 --> 00:44:41,080 an astounding 53 degrees Celsius. 339 00:44:49,680 --> 00:44:52,040 But there are already casualties. 340 00:45:03,240 --> 00:45:05,800 One minute left, and they're not going to make it. 341 00:45:05,880 --> 00:45:07,790 Something has to change. 342 00:45:55,320 --> 00:45:59,470 The silver ant is the hardiest of all desert inhabitants. 343 00:46:00,360 --> 00:46:04,400 Even so, it can only survive outside in the middle of the day 344 00:46:04,480 --> 00:46:05,880 for a matter of minutes. 345 00:46:11,240 --> 00:46:15,550 Now, the desert belongs to the sun alone. 346 00:46:18,640 --> 00:46:22,080 The sun has scorched life from the Sahara. 347 00:46:22,680 --> 00:46:29,030 And yet the vast desert it created is a source of life half a world away. 348 00:46:33,840 --> 00:46:39,200 The advancing Sahara vaporised the world's largest lake, 349 00:46:39,480 --> 00:46:45,110 leaving behind the silvery remains of countless microscopic algae. 350 00:46:47,760 --> 00:46:52,520 In winter, the wind carries away 700,000 tonnes 351 00:46:52,600 --> 00:46:56,280 of this mineral-rich dust every day. 352 00:46:58,360 --> 00:47:02,040 It blows from here all the way to South America, 353 00:47:02,160 --> 00:47:07,440 where, astonishingly, it fertilises the Amazon Rainforest. 354 00:47:13,880 --> 00:47:19,430 A striking demonstration of the reach of this mighty continent. 355 00:47:29,600 --> 00:47:31,110 Throughout its long history, 356 00:47:31,240 --> 00:47:34,360 Africa has influenced the entire planet. 357 00:47:35,120 --> 00:47:38,480 It was the cradle of a remarkable array of land animals 358 00:47:38,560 --> 00:47:40,280 that spread across the globe. 359 00:47:40,360 --> 00:47:44,040 And, of course, it was the ancestral home of all of us. 360 00:48:04,100 --> 00:48:08,780 361 00:48:14,720 --> 00:48:18,160 This is the tale of two of the Africa team's 362 00:48:18,240 --> 00:48:20,600 most challenging desert expeditions. 363 00:48:23,960 --> 00:48:24,950 364 00:48:25,960 --> 00:48:30,720 One focused on a minuscule creature with an incredible turn of speed. 365 00:48:32,920 --> 00:48:37,520 The other on a subject so slow, to film it in action would take years. 366 00:48:37,800 --> 00:48:38,790 367 00:48:39,640 --> 00:48:43,080 In both cases, the Sahara would push crews to the limit 368 00:48:43,160 --> 00:48:45,230 in pursuit of the perfect shot. 369 00:48:50,440 --> 00:48:54,880 In Tunisia, the mission is to capture footage of moving sand dunes, 370 00:48:54,960 --> 00:48:58,240 something that's never been tried like this before. 371 00:48:58,760 --> 00:49:01,070 The problem is that because the dunes move so slowly, 372 00:49:01,160 --> 00:49:03,310 we're going to have to leave cameras here for about 20 months, 373 00:49:03,400 --> 00:49:06,550 and that just means there's a huge potential for things to go wrong. 374 00:49:07,560 --> 00:49:10,200 And with filmmaking, if something can go wrong, 375 00:49:10,280 --> 00:49:11,710 it usually will. 376 00:49:13,440 --> 00:49:15,910 Two local shepherds, Amur and Nasser, 377 00:49:16,000 --> 00:49:18,960 have volunteered to tend the equipment full-time. 378 00:49:22,600 --> 00:49:26,880 The camera tower will be the tallest structure for as far as the eye can see. 379 00:49:31,080 --> 00:49:34,040 And there are three other cameras at lower angles. 380 00:49:36,160 --> 00:49:40,280 All this toil will yield surprisingly scant results. 381 00:49:41,280 --> 00:49:43,950 WRIGHT: They've programmed the cameras to take one photo every day, 382 00:49:45,120 --> 00:49:48,030 that's only 365 photographs a year. 383 00:49:48,960 --> 00:49:52,320 Which, when you run it at normal speed, just over 14 seconds. 384 00:49:52,600 --> 00:49:57,440 I think it's taken longer to explain what's going to happen 385 00:49:57,520 --> 00:49:59,030 than the end result will actually be. 386 00:50:00,120 --> 00:50:03,510 The cameras are left to the mercy of the sun, wind and sand. 387 00:50:05,960 --> 00:50:09,920 In the meantime, crews are shooting all across North Africa. 388 00:50:13,160 --> 00:50:16,070 In Egypt, the challenge is to get into the world 389 00:50:16,160 --> 00:50:18,520 of the most heat-tolerant desert animal - 390 00:50:18,600 --> 00:50:20,430 the silver ant. 391 00:50:20,520 --> 00:50:22,990 They're really small, they're really fast. 392 00:50:23,640 --> 00:50:26,230 Like, you're not too sure if you've seen an ant. 393 00:50:28,240 --> 00:50:31,760 The crew have three weeks to gather the footage they need. 394 00:50:33,480 --> 00:50:35,710 We're going to try a tracking shot on this ant nest. 395 00:50:35,840 --> 00:50:38,960 Moving forward towards it, 396 00:50:39,040 --> 00:50:41,600 as the ants pour out of the hole in their millions. 397 00:50:43,520 --> 00:50:45,750 Not only are these insects super-fast, 398 00:50:45,840 --> 00:50:48,430 they also keep antisocial hours. 399 00:50:49,200 --> 00:50:50,630 The thing is, we need to be out here 400 00:50:50,720 --> 00:50:53,310 in the middle of the day to film these ants. 401 00:50:53,400 --> 00:50:55,830 They don't do what they do when it's nice and cool 402 00:50:55,920 --> 00:50:57,960 at 7:00, 8:00 in the morning. 403 00:50:59,120 --> 00:51:01,510 I can't remember ever being in a place 404 00:51:01,600 --> 00:51:04,430 where the wind was so relentless and the temperatures were so high. 405 00:51:08,080 --> 00:51:11,790 The insufferable heat is not the only problem. 406 00:51:11,880 --> 00:51:13,920 Dangers are everywhere. 407 00:51:14,280 --> 00:51:15,950 408 00:51:16,040 --> 00:51:19,160 There's a really fat scorpion, it's really big! 409 00:51:19,840 --> 00:51:20,830 One, two, three... 410 00:51:23,160 --> 00:51:24,960 411 00:51:25,360 --> 00:51:26,870 This might kill. 412 00:51:26,960 --> 00:51:29,000 - Yeah? - Yeah. 413 00:51:29,120 --> 00:51:31,400 It's big and they have a lot of poison in his dart thing. 414 00:51:33,000 --> 00:51:34,640 What, that thing there? 415 00:51:34,720 --> 00:51:36,200 Oh, my god! 416 00:51:36,280 --> 00:51:37,550 Don't touch it! 417 00:51:37,880 --> 00:51:39,630 The scorpion will be released 418 00:51:39,720 --> 00:51:43,000 far, far away from the camp, in a shady spot. 419 00:51:44,600 --> 00:51:48,960 No such luck for the team. They're back to work in the midday sun. 420 00:51:49,880 --> 00:51:52,630 This is... This is too much. 421 00:51:52,720 --> 00:51:55,230 This is crazy! This is crazy! 422 00:51:55,880 --> 00:51:56,950 Indeed. 423 00:51:57,040 --> 00:52:01,000 The heat seems to have given Kat and Warwick a touch of Saharan madness. 424 00:52:02,880 --> 00:52:04,840 The plan is to do an experiment, 425 00:52:05,600 --> 00:52:09,830 to find out how fast these little ants can run. 426 00:52:10,520 --> 00:52:12,430 So we're going to lay this along the floor, 427 00:52:12,520 --> 00:52:16,120 and hopefully an ant will run alongside it, 428 00:52:16,200 --> 00:52:17,710 and we can film it at high speed. 429 00:52:18,080 --> 00:52:20,990 And from that, calculate their... their speed, 430 00:52:21,080 --> 00:52:24,680 and perhaps try and relate it to how fast that would be for a human. 431 00:52:25,440 --> 00:52:26,430 Like me. 432 00:52:27,720 --> 00:52:30,110 Silver ants are expert navigators, 433 00:52:30,200 --> 00:52:33,110 using the angle of the sun to calculate their position. 434 00:52:33,480 --> 00:52:38,030 But for our team, even basic mental tasks are becoming a challenge. 435 00:52:39,200 --> 00:52:40,190 Count a second. 436 00:52:40,280 --> 00:52:42,110 See one running and then count a second, see how far it gets. 437 00:52:42,200 --> 00:52:44,160 It's quite difficult to count a second, isn't it? 438 00:52:44,240 --> 00:52:45,310 No, it's "one". 439 00:52:48,120 --> 00:52:49,710 "One", yeah! 440 00:52:54,120 --> 00:52:55,110 There he goes. 441 00:52:57,880 --> 00:53:00,470 He's gone 10 centimetres in four seconds, 442 00:53:00,560 --> 00:53:03,950 but we're running at 500 frames a second, 443 00:53:04,040 --> 00:53:06,400 which is 20 times normal time. 444 00:53:06,680 --> 00:53:10,040 So, in fact, he's covered those 10 centimetres in... 445 00:53:13,960 --> 00:53:17,000 We know that he does half a metre in one second. 446 00:53:17,080 --> 00:53:18,510 Half a metre per second, yep. 447 00:53:20,040 --> 00:53:22,680 - 50 centimetres in one second, roughly. - Yeah, yeah. 448 00:53:23,400 --> 00:53:26,040 So, how many body lengths is that? 449 00:53:28,120 --> 00:53:30,480 He's maybe doing five body lengths a second 450 00:53:30,560 --> 00:53:31,790 if he's two metres tall, like I am. 451 00:53:31,880 --> 00:53:32,870 Are you? 452 00:53:32,960 --> 00:53:35,030 Yeah. That's how much more than a normal man I am. 453 00:53:41,320 --> 00:53:46,350 Eventually, the duo decide that if the silver ants were our size, 454 00:53:46,440 --> 00:53:50,320 they'd be doing 280 miles an hour. 455 00:53:53,280 --> 00:53:56,430 They're one of the fastest sprinters in the animal kingdom. 456 00:53:57,080 --> 00:53:58,910 No wonder we've been struggling to film them. 457 00:53:59,080 --> 00:54:01,040 It does explain a few things. 458 00:54:03,000 --> 00:54:04,510 Ant-letics! 459 00:54:08,960 --> 00:54:11,630 Knowing the exact speed of the ants is all well and good, 460 00:54:11,720 --> 00:54:15,110 but there's still a great deal of work to be done before the shoot finishes. 461 00:54:17,600 --> 00:54:21,390 However, in Tunisia, there's no shortage of time, 462 00:54:21,480 --> 00:54:26,680 and hopefully no news is good news as far as Amur and Nasser are concerned. 463 00:54:31,720 --> 00:54:36,920 The final week in Egypt, and the crew seem to be adapting to life in the oven. 464 00:54:40,800 --> 00:54:44,790 Practice is making perfect, and the sequence is coming together. 465 00:54:48,000 --> 00:54:49,800 I think we've got some lovely shots. 466 00:54:49,880 --> 00:54:52,000 Every single shot's been really hard-earned. 467 00:54:52,600 --> 00:54:54,640 But getting down in the ants' world 468 00:54:54,760 --> 00:54:56,830 is now taking its toll on the kit. 469 00:54:56,920 --> 00:54:58,270 It's running to stand still, 470 00:54:58,360 --> 00:55:00,350 the business of blowing dust off these things. 471 00:55:00,760 --> 00:55:01,750 472 00:55:03,200 --> 00:55:04,520 Oh, no! 473 00:55:04,760 --> 00:55:06,030 It's got dust in it! 474 00:55:06,720 --> 00:55:07,760 475 00:55:07,840 --> 00:55:08,880 Ooh, crunch. 476 00:55:11,880 --> 00:55:13,680 SLOSS: I think these ants are stunning-looking. 477 00:55:13,760 --> 00:55:16,720 Near-impossible to film, I think, because of the speed they had. 478 00:55:16,840 --> 00:55:20,520 But, you know, I've come to love them over the days and weeks. 479 00:55:22,800 --> 00:55:24,200 With the sequence in the bag, 480 00:55:24,280 --> 00:55:27,830 Warwick wants the final traditional sunset shot. 481 00:55:28,680 --> 00:55:32,310 It's the best time of day to film sunsets, in the evening. 482 00:55:34,440 --> 00:55:35,630 That's experience that tells me that, 483 00:55:35,720 --> 00:55:38,520 I've been doing this for years. You learn these things. 484 00:55:39,120 --> 00:55:43,320 Thanks to Warwick's experience, including sunsets, he and Kat 485 00:55:43,400 --> 00:55:48,030 have captured the extraordinary life of the speedy silver ant. 486 00:55:51,720 --> 00:55:53,360 Over a year later, in Tunisia, 487 00:55:53,720 --> 00:55:57,000 it's time to take down the sand dune cameras. 488 00:55:58,720 --> 00:56:00,390 Bonjour! 489 00:56:01,240 --> 00:56:03,280 - Nasser. - Amur. 490 00:56:03,360 --> 00:56:04,400 Hi. Hello again. 491 00:56:05,200 --> 00:56:06,470 So how's it been, has it been good? 492 00:56:06,560 --> 00:56:11,030 It's okay, but two days ago, we have a little bit, small problem. 493 00:56:12,040 --> 00:56:14,550 After surviving 600 days in the desert, 494 00:56:14,640 --> 00:56:19,030 the small problem is that the cameras have been vandalised. 495 00:56:21,720 --> 00:56:24,310 I'm really hot and bothered now, it's 40 degrees, 496 00:56:25,120 --> 00:56:27,920 and someone's smashed the cameras. 497 00:56:28,200 --> 00:56:30,400 Not been a good start to the day, to be honest. 498 00:56:31,720 --> 00:56:34,520 There's no doubt the dunes have moved. 499 00:56:34,600 --> 00:56:37,750 But the question is whether the equipment has survived. 500 00:56:41,720 --> 00:56:43,520 That is amazing. The camera's still here. 501 00:56:43,600 --> 00:56:47,150 I guess maybe it just took them so long to get through the toughened plastic, 502 00:56:47,240 --> 00:56:49,390 that they felt they had made so much noise 503 00:56:49,480 --> 00:56:50,830 that they were worried about the guards coming, 504 00:56:50,920 --> 00:56:53,230 because they only sleep a couple of hundred metres away. 505 00:56:54,440 --> 00:56:58,830 After almost two years of waiting, it's the moment of truth. 506 00:57:01,360 --> 00:57:04,640 We're going to find out, to find out whether or not 507 00:57:04,720 --> 00:57:06,920 the cameras have actually recorded anything. 508 00:57:07,000 --> 00:57:10,150 It's just hugely stressful because it's never been done before. 509 00:57:13,320 --> 00:57:17,150 The footage is a surreal window into a secret world, 510 00:57:17,240 --> 00:57:19,750 the private life of a sand dune. 511 00:57:21,880 --> 00:57:25,400 512 00:57:29,800 --> 00:57:32,390 The Africa team struggled under the burning sun 513 00:57:32,480 --> 00:57:36,310 and driving winds that are hallmarks of the Sahara. 514 00:57:42,360 --> 00:57:45,590 They went home with an enormous admiration for the creatures 515 00:57:45,680 --> 00:57:51,310 that spend their entire lives battling to survive in this brutal desert world.