1 00:00:53,160 --> 00:00:56,440 The forests of the world, whether the jungles of Asia 2 00:00:56,440 --> 00:01:01,960 or the tropical rainforests of South America or woodlands in Europe, 3 00:01:01,960 --> 00:01:07,280 haven't really changed in their essentials for 50 million years. 4 00:01:07,280 --> 00:01:11,320 Then, as now, there were ferns and flowering plants 5 00:01:11,320 --> 00:01:15,560 and tall trees with broad leaves. Leaves, in fact, everywhere, 6 00:01:15,560 --> 00:01:20,120 sprouting and falling season after season, century after century. 7 00:01:20,120 --> 00:01:24,640 Dinosaurs had fed on leaves. Some of the biggest were plant-eaters. 8 00:01:24,640 --> 00:01:26,560 But when the dinosaurs disappeared, 9 00:01:26,560 --> 00:01:29,080 for reasons we still don't understand, 10 00:01:29,080 --> 00:01:32,160 these forests were left empty of any large creatures. 11 00:01:32,160 --> 00:01:34,520 There were just birds in the trees, 12 00:01:34,520 --> 00:01:38,200 insects and a few small reptiles and amphibians. 13 00:01:38,200 --> 00:01:43,040 And they stayed empty for several hundred thousand years. 14 00:01:43,040 --> 00:01:44,800 That may seem a very long time, 15 00:01:44,800 --> 00:01:48,240 but in geological time it's really quite short. 16 00:01:48,240 --> 00:01:51,280 And then, amongst those small creatures, 17 00:01:51,280 --> 00:01:52,840 there were some warm-blooded, 18 00:01:52,840 --> 00:01:56,360 inconspicuous little animals that fed on insects. 19 00:01:56,360 --> 00:01:58,360 They'd been around a long time. 20 00:01:58,360 --> 00:02:01,840 They had been in the forests with the dinosaurs, 21 00:02:01,840 --> 00:02:06,040 but with the dinosaurs gone, those creatures began to develop 22 00:02:06,040 --> 00:02:10,200 ways of raiding this untapped larder of leaves. 23 00:02:10,200 --> 00:02:12,840 And their descendants are still at it. 24 00:02:30,880 --> 00:02:34,720 One or two have become extraordinarily specialised. 25 00:02:34,720 --> 00:02:36,760 The three-toed sloth in South America 26 00:02:36,760 --> 00:02:39,040 eats only the leaves of the Cecropia tree. 27 00:02:39,040 --> 00:02:42,880 Hanging beneath the branches, no predators can reach it. 28 00:02:42,880 --> 00:02:47,080 And perhaps lulled by this security, it's fallen into a kind of torpor 29 00:02:47,080 --> 00:02:51,560 so that it's totally unable to move any faster than this. 30 00:02:52,720 --> 00:02:58,760 Others became nimble and agile acrobats - the monkeys. 31 00:02:58,760 --> 00:03:01,760 But the leaf-eaters didn't have everything their own way. 32 00:03:07,520 --> 00:03:10,800 There were also hunters in the forest, 33 00:03:10,800 --> 00:03:14,040 moving silently and stalking alone. 34 00:03:41,320 --> 00:03:45,040 These duels are also played out at night. 35 00:03:47,560 --> 00:03:50,760 From the beginnings of the mammals' history they'd been able, 36 00:03:50,760 --> 00:03:53,240 with the help of their warm bodies, to remain active 37 00:03:53,240 --> 00:03:56,080 even when the warming sun had gone down. 38 00:03:56,080 --> 00:03:58,960 A great proportion of them have never lost the habit 39 00:03:58,960 --> 00:04:02,320 and venture out only under the cover of darkness 40 00:04:02,320 --> 00:04:05,040 to nibble buds, bark and green shoots. 41 00:04:05,040 --> 00:04:07,280 This is a dormouse. 42 00:04:13,640 --> 00:04:17,480 On the woodland floor, a little hamster busily gathers food. 43 00:04:17,480 --> 00:04:21,040 It needs great quantities, for vegetation contains 44 00:04:21,040 --> 00:04:24,200 little nourishment in proportion to its bulk. 45 00:04:25,640 --> 00:04:29,480 But eating for hours on end out in the open can be dangerous, 46 00:04:29,480 --> 00:04:31,800 so the hamster stuffs all it can find 47 00:04:31,800 --> 00:04:34,800 into its cheek pouches as quickly as possible 48 00:04:34,800 --> 00:04:38,520 and then scampers back to the safety of its burrow. 49 00:04:41,120 --> 00:04:44,960 There it unloads its collection and eats it at leisure. 50 00:04:44,960 --> 00:04:49,240 Throughout the summer, it builds up immense stores down here, 51 00:04:49,240 --> 00:04:51,920 because soon another problem will face it, 52 00:04:51,920 --> 00:04:54,000 as it faces many other vegetarians. 53 00:05:06,240 --> 00:05:10,400 The frozen forests can no longer provide sufficient food 54 00:05:10,400 --> 00:05:12,560 to sustain the army of vegetarians 55 00:05:12,560 --> 00:05:15,840 that gnawed and nibbled here throughout the summer. 56 00:05:26,360 --> 00:05:30,200 The dormouse deals with the problem by hibernating. 57 00:05:30,200 --> 00:05:33,560 Its blood cools to only a few degrees above freezing, 58 00:05:33,560 --> 00:05:36,440 and the motors of its body slow down and idle, 59 00:05:36,440 --> 00:05:41,680 driven only by the fat accumulated during the leafy days of summer. 60 00:05:44,920 --> 00:05:49,000 The wood mouse, too, lives off its fat, though it doesn't hibernate 61 00:05:49,000 --> 00:05:53,240 and manages to keep going by finding seeds and gnawing bark. 62 00:06:00,480 --> 00:06:03,840 This is the time when the old and the weak die, 63 00:06:03,840 --> 00:06:06,720 and only the strongest survive. 64 00:06:13,000 --> 00:06:15,520 Bigger creatures too, like deer, 65 00:06:15,520 --> 00:06:20,400 are driven to search for nuts and to strip bark from trees. 66 00:06:21,760 --> 00:06:24,160 But after months of hardship, 67 00:06:24,160 --> 00:06:28,480 the year eventually turns and the world becomes green again. 68 00:06:28,480 --> 00:06:30,600 Among the leaves that sprouted 69 00:06:30,600 --> 00:06:33,840 during the springs of some 25 million years ago, 70 00:06:33,840 --> 00:06:38,640 there was a sudden increase in a particular kind - grass. 71 00:06:38,640 --> 00:06:41,280 The spread of grass was probably triggered 72 00:06:41,280 --> 00:06:42,960 by a drying of the climate. 73 00:06:42,960 --> 00:06:47,280 It may appear to be a simple kind of plant, little more than leaves, 74 00:06:47,280 --> 00:06:50,160 but in fact it's a complex and specialised one. 75 00:06:50,160 --> 00:06:54,000 It has tiny flowers that rely on the wind for pollination. 76 00:06:54,000 --> 00:06:57,640 Its leaves grow not from the tip, like most other plants, 77 00:06:57,640 --> 00:07:00,320 but from the bottom, close to the ground. 78 00:07:00,320 --> 00:07:04,640 So when a fire sweeps over the plains, the leaves may burn, 79 00:07:04,640 --> 00:07:09,440 but new ones will sprout from the root stocks almost immediately. 80 00:07:09,440 --> 00:07:12,000 Similarly, when animals nibble the top part, 81 00:07:12,000 --> 00:07:13,760 the bottom continues to grow, 82 00:07:13,760 --> 00:07:17,760 providing a never-ending supply of succulent food. 83 00:07:26,720 --> 00:07:30,360 Leaf-eaters from the forest soon moved out onto the plains 84 00:07:30,360 --> 00:07:35,000 to gather this new and bountiful supply of sustenance. 85 00:07:39,360 --> 00:07:42,720 Leaves are not, however, easy to digest. 86 00:07:42,720 --> 00:07:45,160 To extract their nourishment, 87 00:07:45,160 --> 00:07:48,600 they have to be worked on by the digestive juices for a long time. 88 00:07:48,600 --> 00:07:52,520 And rabbits make this happen in a most surprising way. 89 00:07:55,760 --> 00:07:58,920 Having nibbled a stomachful above ground, 90 00:07:58,920 --> 00:08:01,480 the rabbit retreats to its burrow. 91 00:08:02,480 --> 00:08:06,800 Here it excretes special mucus-covered pellets, 92 00:08:06,800 --> 00:08:09,200 but the grass in them is only half-digested. 93 00:08:09,200 --> 00:08:13,160 As each pellet emerges, the rabbit immediately swallows it, 94 00:08:13,160 --> 00:08:15,360 so that eventually all its food 95 00:08:15,360 --> 00:08:18,560 passes through its digestive system twice. 96 00:08:33,320 --> 00:08:38,120 These creatures also live entirely on plants. 97 00:08:38,120 --> 00:08:41,000 They're buffalo, and I'm in North America. 98 00:08:41,000 --> 00:08:44,000 Like all vegetarians, they have teeth 99 00:08:44,000 --> 00:08:47,240 that are specially modified for the job. 100 00:08:47,240 --> 00:08:50,280 Those at the front here are nippers, 101 00:08:50,280 --> 00:08:53,680 which shear off the grass or the browse. 102 00:08:53,680 --> 00:08:56,600 Then, at the back, there are these grinding molars, 103 00:08:56,600 --> 00:08:58,000 a great battery of them. 104 00:08:58,000 --> 00:09:02,800 They're open-rooted, so they keep on growing as the enamel wears down. 105 00:09:02,800 --> 00:09:04,120 They have these ridges, 106 00:09:04,120 --> 00:09:07,600 which help to break down the walls of the cellulose in the plant, 107 00:09:07,600 --> 00:09:11,320 and, also, the jaw can be moved from side to side 108 00:09:11,320 --> 00:09:13,960 to help in the grinding process. 109 00:09:21,520 --> 00:09:25,160 Gathering sufficient grass to sustain an animal this size 110 00:09:25,160 --> 00:09:28,480 takes a long time - up to nine hours a day. 111 00:09:28,480 --> 00:09:30,880 But even that battery of grinding teeth 112 00:09:30,880 --> 00:09:33,720 doesn't solve the problem of digesting grass. 113 00:09:33,720 --> 00:09:37,560 And the buffalo also has to give its meals a double treatment, 114 00:09:37,560 --> 00:09:41,400 though in a rather neater way than that used by the rabbit. 115 00:09:41,400 --> 00:09:45,240 The chewed grass goes down to a large chamber, the stomach, 116 00:09:45,240 --> 00:09:47,640 that serves as a fermentation vat 117 00:09:47,640 --> 00:09:51,480 and contains a particularly rich brew of bacteria 118 00:09:51,480 --> 00:09:53,880 and single-celled creatures. 119 00:09:53,880 --> 00:09:57,240 These actively swimming little organisms are so small 120 00:09:57,240 --> 00:10:00,600 that a thousand million of them could get into a teaspoon. 121 00:10:00,600 --> 00:10:03,960 The rectangular slabs are fragments of leaves. 122 00:10:03,960 --> 00:10:08,280 No mammal can digest the cellulose walls of plant cells, 123 00:10:08,280 --> 00:10:11,160 but these micro-organisms can. 124 00:10:11,160 --> 00:10:14,040 They produce a ferment which dissolves the cellulose, 125 00:10:14,040 --> 00:10:18,360 changing it into a substance that the buffalo can absorb. 126 00:10:18,360 --> 00:10:22,680 But the bodies of the microbes also contain valuable protein. 127 00:10:22,680 --> 00:10:24,600 This, too, will be digested, 128 00:10:24,600 --> 00:10:28,480 but not until the half-digested mash, or cud, 129 00:10:28,480 --> 00:10:31,200 is brought up a lump at a time... 130 00:10:34,000 --> 00:10:37,000 ..and given a second chewing. 131 00:10:42,680 --> 00:10:46,080 One mouthful goes down for a second time... 132 00:10:47,960 --> 00:10:51,160 ..and up comes another. 133 00:10:51,160 --> 00:10:53,600 Many grass-eaters chew the cud like this, 134 00:10:53,600 --> 00:10:56,160 and a very convenient technique it is, too. 135 00:10:56,160 --> 00:10:58,640 It can be done away from the open pasture, 136 00:10:58,640 --> 00:11:01,520 lying concealed and comfortable in the shade, 137 00:11:01,520 --> 00:11:06,000 or with the head held high if there is a need to keep watch for danger. 138 00:11:12,720 --> 00:11:17,360 So, many leaf-eaters from the forest found food on the plain, 139 00:11:17,360 --> 00:11:21,920 and out of the forest, too, in pursuit of them, came the hunters. 140 00:11:53,520 --> 00:11:57,280 The serval is considerably bigger than a domestic cat. 141 00:11:57,280 --> 00:11:58,920 It hunts rats and mice 142 00:11:58,920 --> 00:12:03,160 and must catch about a dozen each day in order to survive. 143 00:12:05,520 --> 00:12:08,880 Flesh-eaters need quite different teeth from vegetarians. 144 00:12:08,880 --> 00:12:11,360 Instead of grinders and pulpers 145 00:12:11,360 --> 00:12:15,080 they require the armoury of the butcher's shop. 146 00:12:15,080 --> 00:12:18,440 A lion has two pairs of fangs at the front, 147 00:12:18,440 --> 00:12:23,280 daggers to stab the prey and grip it unrelentingly as it struggles. 148 00:12:23,280 --> 00:12:28,080 At the front, nipping teeth to pick off strands of meat. 149 00:12:28,080 --> 00:12:30,000 At the back, the cutters, 150 00:12:30,000 --> 00:12:34,320 self-sharpening blades which mesh onto one another so accurately 151 00:12:34,320 --> 00:12:38,240 that they can shear through hide, tendons, even bones. 152 00:12:38,240 --> 00:12:43,040 These are why lions and cats chew with the sides of their mouths. 153 00:12:43,040 --> 00:12:46,200 With weapons like this around, it's hardly surprising 154 00:12:46,200 --> 00:12:49,560 one of the most pressing concerns of leaf-eaters on the plains 155 00:12:49,560 --> 00:12:52,440 is to keep out of the way. 156 00:12:52,440 --> 00:12:56,280 One of the ways to do that is to go underground. 157 00:12:56,280 --> 00:12:58,520 These are the waste tips of the mole rat, 158 00:12:58,520 --> 00:13:02,360 a creature that has foregone the lush leaves of the grass 159 00:13:02,360 --> 00:13:05,360 and specialised instead on eating the roots. 160 00:13:24,640 --> 00:13:28,440 It tunnels industriously a few inches below the surface, 161 00:13:28,440 --> 00:13:32,040 nipping off the grass roots from beneath. 162 00:13:32,040 --> 00:13:36,520 Eyes are no use underground, and the mole rat has become totally blind, 163 00:13:36,520 --> 00:13:38,080 the furry skin of its head 164 00:13:38,080 --> 00:13:41,320 having completely covered the vestiges of its eyes. 165 00:13:41,320 --> 00:13:43,720 It finds its way around by touch, 166 00:13:43,720 --> 00:13:47,560 using lines of bristles growing on either side of its head. 167 00:13:47,560 --> 00:13:50,360 It happily scuttles along its dark tunnels, 168 00:13:50,360 --> 00:13:53,320 not only forwards, but backwards, like a tram. 169 00:13:53,320 --> 00:13:57,880 For burrowing it uses predominantly its large and powerful gnawing teeth 170 00:13:57,880 --> 00:14:00,880 and its shovel-shaped snout. 171 00:14:02,320 --> 00:14:05,680 It excavates enormously long tunnels beneath the turf 172 00:14:05,680 --> 00:14:07,600 and guards them energetically 173 00:14:07,600 --> 00:14:11,520 to protect its supply of roots and bulbs growing down from the ceiling. 174 00:14:17,160 --> 00:14:20,520 If a mole rat meets a stranger in its tunnel, 175 00:14:20,520 --> 00:14:22,760 there is likely to be trouble. 176 00:14:34,920 --> 00:14:37,800 Having established by smell that they are rivals, 177 00:14:37,800 --> 00:14:41,520 their first reaction is to build a wall between the two territories. 178 00:14:51,400 --> 00:14:55,400 If they still run into one another, then they fight. 179 00:15:11,560 --> 00:15:16,240 In the spring, particularly large mounds appear above their runs, 180 00:15:16,240 --> 00:15:20,560 thrown up by the females as they excavate their breeding chambers. 181 00:15:20,560 --> 00:15:24,640 Each of these underground mansions has larders stocked with bulbs, 182 00:15:24,640 --> 00:15:28,960 special lavatories and passages to the tunnels where the males live. 183 00:15:28,960 --> 00:15:33,280 Here the young, blind like their parents, are born and reared. 184 00:15:33,280 --> 00:15:37,720 Mole rats are the most dedicated of underground dwellers. 185 00:15:37,720 --> 00:15:40,840 Other inhabitants of the plain, like these prairie dogs, 186 00:15:40,840 --> 00:15:43,840 are rather more confident about life. 187 00:15:50,400 --> 00:15:53,280 Prairie dogs are also burrowers, 188 00:15:53,280 --> 00:15:56,520 but they spend much of their time not below ground, but above it. 189 00:16:00,520 --> 00:16:03,520 They actively farm their fields. 190 00:16:03,520 --> 00:16:06,000 If a plant they don't like to eat, such as sage, 191 00:16:06,000 --> 00:16:08,680 takes root on their land, they will cut it down 192 00:16:08,680 --> 00:16:12,000 and so make room for more of the plants that they do like. 193 00:16:12,000 --> 00:16:14,960 If one patch of pasture gets overgrazed, 194 00:16:14,960 --> 00:16:17,400 they abandon it and let it lie fallow 195 00:16:17,400 --> 00:16:19,680 while they feed on another patch. 196 00:16:26,760 --> 00:16:30,120 They live in huge towns many thousands strong. 197 00:16:30,120 --> 00:16:34,600 These great communities are made up of groups of about 30 animals, 198 00:16:34,600 --> 00:16:36,800 which all know one another personally 199 00:16:36,800 --> 00:16:39,200 and have burrows that are often interconnected. 200 00:16:39,200 --> 00:16:43,760 When these neighbours meet, they kiss and groom one another. 201 00:16:46,520 --> 00:16:49,600 They exchange many kinds of signals. 202 00:16:49,600 --> 00:16:53,040 A citizen declares his ownership of a burrow like this. 203 00:16:53,040 --> 00:16:54,960 SCREECHING 204 00:17:05,240 --> 00:17:08,120 They also bark warnings when they spot danger, 205 00:17:08,120 --> 00:17:11,080 such as eagles or coyotes on the hunt. 206 00:17:11,080 --> 00:17:13,240 BARKING 207 00:17:14,560 --> 00:17:17,920 So, as the open plains spread through the world, 208 00:17:17,920 --> 00:17:20,600 the animals that came out of the forests to graze there 209 00:17:20,600 --> 00:17:23,200 developed different ways of digesting grass 210 00:17:23,200 --> 00:17:28,000 and of protecting themselves in this dangerously exposed environment. 211 00:17:28,000 --> 00:17:31,840 During this period, South America, where I am now, 212 00:17:31,840 --> 00:17:35,200 became isolated as a gigantic island. 213 00:17:35,200 --> 00:17:39,040 The land bridge of Panama sank beneath the sea. 214 00:17:39,040 --> 00:17:41,160 Cut off from the rest of the world, 215 00:17:41,160 --> 00:17:44,320 the inhabitants of these grasslands, the pampas, 216 00:17:44,320 --> 00:17:50,360 developed into forms that to our eyes seem very extraordinary indeed. 217 00:17:51,520 --> 00:17:54,880 One looked like a cross between a camel and an elephant. 218 00:17:54,880 --> 00:17:58,720 There were huge grazing beasts bigger than rhinos, 219 00:17:58,720 --> 00:18:01,120 and an armoured animal the size of a small car 220 00:18:01,120 --> 00:18:04,960 that trundled about beneath a great dome of bone. 221 00:18:04,960 --> 00:18:06,880 These vegetarians were preyed on 222 00:18:06,880 --> 00:18:10,240 by gigantic flightless birds with beaks like hatchets 223 00:18:10,240 --> 00:18:14,080 and hunters with sabre teeth that looked like tigers 224 00:18:14,080 --> 00:18:17,440 but bore their young in pouches, like kangaroos. 225 00:18:17,440 --> 00:18:19,480 But about five million years ago, 226 00:18:19,480 --> 00:18:22,720 the land link with North America was re-established 227 00:18:22,720 --> 00:18:25,600 and different creatures from the north moved south. 228 00:18:25,600 --> 00:18:28,000 As the populations mixed, 229 00:18:28,000 --> 00:18:31,840 northerners and southerners competed for the same food and territory. 230 00:18:31,840 --> 00:18:33,760 There were winners and losers, 231 00:18:33,760 --> 00:18:37,120 and most of the strange South Americans disappeared. 232 00:18:37,120 --> 00:18:39,320 But in this gigantic cave in Patagonia, 233 00:18:39,320 --> 00:18:41,440 on the southern tip of the continent, 234 00:18:41,440 --> 00:18:46,000 tantalising evidence has been found of a really dramatic survival. 235 00:18:46,000 --> 00:18:48,880 At the end of the 19th century a German came down here 236 00:18:48,880 --> 00:18:51,280 to settle and to ranch cattle and sheep. 237 00:18:51,280 --> 00:18:55,120 And this cave lay on his estancia. 238 00:18:55,120 --> 00:18:58,840 When he came to explore it, he found, at the back, 239 00:18:58,840 --> 00:19:01,240 behind that line of boulders, 240 00:19:01,240 --> 00:19:07,200 a pile of the most extraordinary bones, skin and dung. 241 00:19:07,200 --> 00:19:09,840 He hung a piece of the skin on one of the posts 242 00:19:09,840 --> 00:19:12,480 that marked the boundary of his property. 243 00:19:12,480 --> 00:19:17,760 And there, a few years later, a Swedish traveller noticed it. 244 00:19:17,760 --> 00:19:21,160 He sent it to the Natural History Museum in London, 245 00:19:21,160 --> 00:19:26,880 and there they identified it as belonging to a giant ground sloth. 246 00:19:29,040 --> 00:19:33,360 This animal had been known for some time from its fossilised bones. 247 00:19:33,360 --> 00:19:36,120 But the remains in the cave were not fossilised 248 00:19:36,120 --> 00:19:38,160 and seemed extraordinarily fresh. 249 00:19:38,160 --> 00:19:41,040 Could the animal still be alive somewhere? 250 00:19:41,040 --> 00:19:43,880 Why were there such huge piles of dung in the cave? 251 00:19:43,880 --> 00:19:46,680 Was it possible that the line of boulders 252 00:19:46,680 --> 00:19:49,160 was the remains of a wall built by men 253 00:19:49,160 --> 00:19:53,280 to pen the animals in the cave, like enormous cattle? 254 00:19:53,280 --> 00:19:57,600 For a long time, nobody knew the answers to those questions. 255 00:19:57,600 --> 00:20:01,440 But recent excavations have at least cleared up some of them. 256 00:20:01,440 --> 00:20:04,640 A few years ago, these bits of bone were dug up here. 257 00:20:04,640 --> 00:20:07,760 This is a bit of the jaw, and this of the hip. 258 00:20:07,760 --> 00:20:11,600 From tests on them and their position in the ground, we now know 259 00:20:11,600 --> 00:20:16,880 that the giant ground sloths were here up to about 5,000 years ago. 260 00:20:16,880 --> 00:20:21,200 The same excavations have also shown that the Indians were here 261 00:20:21,200 --> 00:20:23,640 between 8,000 and 10,000 years ago. 262 00:20:23,640 --> 00:20:29,480 So it is indeed possible that the Indians hunted those huge animals. 263 00:20:29,480 --> 00:20:31,880 But that line of boulders, I'm afraid, 264 00:20:31,880 --> 00:20:35,240 is no more than a natural fall of rock from the ceiling. 265 00:20:35,240 --> 00:20:38,120 And the piles of dung behind it are no mystery either. 266 00:20:38,120 --> 00:20:42,480 We now know that many animals habitually use the same dung hills, 267 00:20:42,480 --> 00:20:46,800 and maybe the sloths came in here during the winter to keep warm. 268 00:20:46,800 --> 00:20:50,280 But I'm afraid the animal is really now extinct. 269 00:20:50,280 --> 00:20:54,120 You can't hide a creature twice the size of a cow 270 00:20:54,120 --> 00:20:57,480 in the bleak emptinesses of Patagonia. 271 00:20:57,480 --> 00:21:00,840 So we've missed our chance of seeing it. 272 00:21:00,840 --> 00:21:05,160 But it was quite a close thing, in geological terms, at any rate. 273 00:21:06,760 --> 00:21:09,200 The South American giants may have gone, 274 00:21:09,200 --> 00:21:13,000 but some less conspicuous but equally bizarre creatures remain. 275 00:21:13,000 --> 00:21:15,400 There are many kinds of armadillos, 276 00:21:15,400 --> 00:21:18,280 trotting over the pampas and foraging in the forests, 277 00:21:18,280 --> 00:21:22,080 diminutive descendants of the huge extinct ones. 278 00:21:23,840 --> 00:21:26,520 There are some very odd rodents here, too. 279 00:21:26,520 --> 00:21:30,840 These are capybaras. They find safety in water. 280 00:21:30,840 --> 00:21:34,360 Like a hippopotamus, their eyes, ears and nostrils 281 00:21:34,360 --> 00:21:37,760 are all on the top of the head, and for the same reason - 282 00:21:37,760 --> 00:21:40,040 so that the capybara can lie in the water 283 00:21:40,040 --> 00:21:42,840 fully aware of what is going on around it, 284 00:21:42,840 --> 00:21:47,080 but with practically all its body hidden beneath the surface. 285 00:22:06,960 --> 00:22:11,280 Capybaras are the largest rodents to be found anywhere in the world. 286 00:22:11,280 --> 00:22:14,640 A male grows to be three feet long, a metre or so, 287 00:22:14,640 --> 00:22:19,440 and they're the descendants of an even bigger extinct ancestor. 288 00:22:21,080 --> 00:22:23,480 They move around in large family groups 289 00:22:23,480 --> 00:22:25,880 and are excellent swimmers right from an early age, 290 00:22:25,880 --> 00:22:31,080 though sometimes the young find even easier ways of getting around. 291 00:22:46,840 --> 00:22:50,480 They eat virtually nothing except leaves of one sort or another, 292 00:22:50,480 --> 00:22:54,880 either water plants or the grasses of the river bank. 293 00:23:00,480 --> 00:23:04,240 The viscacha is the South American equivalent of the prairie dog, 294 00:23:04,240 --> 00:23:08,400 though it's very much bigger, about the size of a badger. 295 00:23:12,240 --> 00:23:15,240 At dusk it comes up from its sleeping quarters 296 00:23:15,240 --> 00:23:19,920 and surveys the world before starting on its nightly labour 297 00:23:19,920 --> 00:23:22,680 of nibbling grass for hours on end. 298 00:23:29,800 --> 00:23:34,120 The mara, another South American rodent, has very long legs, 299 00:23:34,120 --> 00:23:38,000 for it finds safety not by burrowing underground, but by running. 300 00:23:38,000 --> 00:23:40,880 So when it browses, it's always on the alert, 301 00:23:40,880 --> 00:23:44,720 nervously watching for danger and so highly strung 302 00:23:44,720 --> 00:23:47,760 that it will race away at the crack of a twig 303 00:23:47,760 --> 00:23:50,680 or the faint whiff of a dangerous scent. 304 00:23:51,960 --> 00:23:53,840 This little leaf-eater 305 00:23:53,840 --> 00:23:58,000 appeared some 50 million years ago in North America. 306 00:23:58,000 --> 00:23:59,920 It was no bigger than a spaniel, 307 00:23:59,920 --> 00:24:03,640 and it had four toes on its front legs and three on the back. 308 00:24:03,640 --> 00:24:07,000 Like the mara, it sought safety in speed. 309 00:24:07,000 --> 00:24:10,160 The longer your legs, the longer strides you can take 310 00:24:10,160 --> 00:24:11,800 and the faster you can run. 311 00:24:11,800 --> 00:24:14,200 Over generations these creatures 312 00:24:14,200 --> 00:24:17,920 increased the length of their legs by rising up on their toes. 313 00:24:17,920 --> 00:24:20,280 After millions of years some developed 314 00:24:20,280 --> 00:24:24,200 which carried their main body weight on the middle toe alone, 315 00:24:24,200 --> 00:24:26,800 and the side toes barely touched the ground. 316 00:24:26,800 --> 00:24:30,240 Their continuously growing nail on the middle toe 317 00:24:30,240 --> 00:24:32,720 became thick to reduce wear - a hoof. 318 00:24:32,720 --> 00:24:35,960 Eventually the side toes disappeared altogether. 319 00:24:35,960 --> 00:24:37,800 These were the early horses, 320 00:24:37,800 --> 00:24:40,800 and they spread right across the northern hemisphere 321 00:24:40,800 --> 00:24:42,040 and down into Africa. 322 00:24:50,760 --> 00:24:54,600 Zebras, with their long legs jointed to a stiff backbone, 323 00:24:54,600 --> 00:24:59,840 can gallop at speeds of up to 40 miles, 65km an hour. 324 00:24:59,840 --> 00:25:02,720 They run in groups for the safety in numbers. 325 00:25:02,720 --> 00:25:05,200 It's more difficult to take an animal by surprise 326 00:25:05,200 --> 00:25:06,400 if it's in a group, 327 00:25:06,400 --> 00:25:10,760 and a swirling mass like this makes a very confusing target. 328 00:25:10,760 --> 00:25:13,400 Other grass-eaters on the plains 329 00:25:13,400 --> 00:25:17,280 find protection from hunters in different ways. 330 00:25:17,280 --> 00:25:21,600 The rhinoceros has a hide as tough as any mammal's, 331 00:25:21,600 --> 00:25:24,480 proof against the sharpest claws and teeth. 332 00:25:24,480 --> 00:25:27,160 Its sheer bulk makes it very formidable, too. 333 00:25:28,200 --> 00:25:32,040 But that also helps it with the universal problem for browsers - 334 00:25:32,040 --> 00:25:34,840 how to digest cellulose. 335 00:25:36,360 --> 00:25:39,240 The rhinoceros doesn't chew cud. 336 00:25:39,240 --> 00:25:44,240 Instead it keeps its food in its belly for a very long time indeed, 337 00:25:44,240 --> 00:25:47,600 so that the bacteria have plenty of time to work on it. 338 00:25:47,600 --> 00:25:51,920 To do that, you need a very large belly in which to store the food, 339 00:25:51,920 --> 00:25:55,640 and if you are to carry a large belly, you must be big. 340 00:25:56,720 --> 00:26:00,520 Only one creature on the plains is much bigger than the rhino. 341 00:26:09,240 --> 00:26:12,600 The elephant is the largest land animal alive, 342 00:26:12,600 --> 00:26:15,960 and its huge size makes it virtually invulnerable. 343 00:26:15,960 --> 00:26:19,560 No hunter is big enough or powerful enough 344 00:26:19,560 --> 00:26:22,680 to pull down a full-grown elephant. 345 00:26:22,680 --> 00:26:25,360 It's so big, it isn't shaded to any degree 346 00:26:25,360 --> 00:26:28,240 by any of the trees that occasionally stud the plains, 347 00:26:28,240 --> 00:26:32,560 and out in the baking sun it's in danger of getting overheated. 348 00:26:32,560 --> 00:26:36,400 Flapping its ears helps considerably in cooling the blood, 349 00:26:36,400 --> 00:26:39,720 as it passes through the veins of the ears. 350 00:26:44,480 --> 00:26:47,680 The elephant manages to live on what is probably 351 00:26:47,680 --> 00:26:49,800 the poorest diet of any mammal. 352 00:26:52,680 --> 00:26:55,360 Although it welcomes leaves when it can get them, 353 00:26:55,360 --> 00:27:00,640 it also eats the most fibrous browse of all - twigs, bark, even branches. 354 00:27:00,640 --> 00:27:02,880 But again its huge intestines allow it 355 00:27:02,880 --> 00:27:06,080 to give this roughage prolonged chemical treatment. 356 00:27:06,080 --> 00:27:09,560 Our food takes about a day to pass through our bodies. 357 00:27:09,560 --> 00:27:11,960 An elephant's takes two and a half days. 358 00:27:11,960 --> 00:27:14,000 For most of that time, the browse, 359 00:27:14,000 --> 00:27:16,760 having been mashed by the elephant's molars, 360 00:27:16,760 --> 00:27:19,560 is stewing in the digestive juices 361 00:27:19,560 --> 00:27:22,880 and bacterial broth of its gigantic gut. 362 00:27:28,040 --> 00:27:31,560 Forest antelopes also moved out into the open country, 363 00:27:31,560 --> 00:27:35,280 lured by so much readily available vegetation. 364 00:27:37,240 --> 00:27:39,040 The little dik-dik resembles 365 00:27:39,040 --> 00:27:42,040 the early forest-living antelopes in many ways. 366 00:27:42,040 --> 00:27:45,320 Like them, it's small, only a foot or so high, 367 00:27:45,320 --> 00:27:48,280 which is convenient for moving in thick vegetation. 368 00:27:48,280 --> 00:27:49,680 And it lives in pairs, 369 00:27:49,680 --> 00:27:53,560 for the shaded floor of the tropical forest is poor in leaves 370 00:27:53,560 --> 00:27:56,920 and can't sustain a dense population of leaf-eaters. 371 00:27:56,920 --> 00:27:58,960 So the antelopes living there 372 00:27:58,960 --> 00:28:03,200 mark and defend their precious pastures against rivals. 373 00:28:08,080 --> 00:28:12,640 The male deposits musk from a gland beneath his eye on twigs 374 00:28:12,640 --> 00:28:16,120 by poking the tips actually in the gland. 375 00:28:17,760 --> 00:28:19,280 The scent proclaims that 376 00:28:19,280 --> 00:28:21,600 the territory belongs to a particular pair, 377 00:28:21,600 --> 00:28:25,440 which will remain here together throughout their lives. 378 00:28:25,440 --> 00:28:28,600 Another male reads the signs. 379 00:28:28,600 --> 00:28:31,480 Smell is very important to the dik-dik. 380 00:28:31,480 --> 00:28:34,440 They have other scent glands between their hooves, 381 00:28:34,440 --> 00:28:36,840 which probably mark the trails. 382 00:28:36,840 --> 00:28:40,200 Since the pair never stray from this one patch of land, 383 00:28:40,200 --> 00:28:43,560 they know it intimately, and that's important in defence. 384 00:28:43,560 --> 00:28:45,960 When danger approaches, 385 00:28:45,960 --> 00:28:49,520 they know the best escape routes, the best corners in which to hide. 386 00:28:58,320 --> 00:29:01,440 Impala inhabit more open country. 387 00:29:01,440 --> 00:29:03,400 They no longer live in pairs, 388 00:29:03,400 --> 00:29:06,240 but have formed herds for safety's sake. 389 00:29:06,240 --> 00:29:09,560 It's very difficult to take them by surprise. 390 00:29:13,320 --> 00:29:14,840 When they are attacked, 391 00:29:14,840 --> 00:29:18,200 the herd works together to baffle their assailants. 392 00:29:23,400 --> 00:29:26,280 As the animals suddenly leap in all directions, 393 00:29:26,280 --> 00:29:29,360 a hunter may well hesitate in deciding which it should follow, 394 00:29:29,360 --> 00:29:33,920 and that may make the difference between a killing and an escape. 395 00:30:01,120 --> 00:30:05,920 Impala still prefer country containing bushes and trees, 396 00:30:05,920 --> 00:30:09,640 but some grazers spend all their lives exposed 397 00:30:09,640 --> 00:30:14,440 out on the open plain, where there is no cover of any kind. 398 00:30:25,000 --> 00:30:29,120 The wildebeest form some of the greatest herds of all. 399 00:30:29,120 --> 00:30:32,480 Tens of thousands of animals move across the plains, 400 00:30:32,480 --> 00:30:35,840 sometimes making huge journeys to follow the rains 401 00:30:35,840 --> 00:30:38,720 and find the newly springing grass. 402 00:30:38,720 --> 00:30:41,120 In vast assemblages like these, 403 00:30:41,120 --> 00:30:44,080 there are no pairs of males and females. 404 00:30:44,080 --> 00:30:45,480 During the rutting season 405 00:30:45,480 --> 00:30:48,400 the dominant bulls will set up small stamping grounds, 406 00:30:48,400 --> 00:30:51,280 which the females will visit one after the other. 407 00:30:51,280 --> 00:30:54,640 So a single bull will service many cows 408 00:30:54,640 --> 00:30:57,880 and then lose touch with them as individuals 409 00:30:57,880 --> 00:31:01,240 when they return to the anonymity of the herd. 410 00:31:01,240 --> 00:31:04,120 Not surprisingly, this immense concentration of animals, 411 00:31:04,120 --> 00:31:09,080 this vast reserve of meat, attracts the attention of hunters. 412 00:31:12,480 --> 00:31:16,320 The cheetah relies on speed in a straightforward chase. 413 00:31:16,320 --> 00:31:19,680 It's said to be the fastest runner in the world, 414 00:31:19,680 --> 00:31:22,920 capable of reaching 70 miles, 110km an hour. 415 00:31:22,920 --> 00:31:24,840 Its legs are not as long as an antelope's, 416 00:31:24,840 --> 00:31:27,120 but it increases their effective length 417 00:31:27,120 --> 00:31:29,640 by having a backbone that is extremely flexible, 418 00:31:29,640 --> 00:31:32,800 so that it can take huge strides. 419 00:31:33,960 --> 00:31:35,960 But it can't sprint like this for long. 420 00:31:35,960 --> 00:31:39,320 If it doesn't catch its prey within a quarter of a mile, 421 00:31:39,320 --> 00:31:41,800 it has to give up, exhausted. 422 00:31:46,040 --> 00:31:48,440 And this time, the gazelle has won. 423 00:31:54,240 --> 00:31:57,320 Young wildebeest are often taken by cheetah. 424 00:32:13,560 --> 00:32:16,440 This cheetah is one of a pair of males 425 00:32:16,440 --> 00:32:21,160 strolling through the herds, as if selecting their meal for the day. 426 00:32:43,040 --> 00:32:46,400 Oddly, perhaps, the wildebeest seem little concerned. 427 00:32:46,400 --> 00:32:49,760 Perhaps they know from the way the cheetahs are behaving 428 00:32:49,760 --> 00:32:52,840 that they're not about to attack yet. 429 00:33:04,680 --> 00:33:07,800 One male makes a tentative run. 430 00:33:07,800 --> 00:33:09,600 Bending his supple spine, 431 00:33:09,600 --> 00:33:13,080 he can cover an astonishing 23 feet, seven metres, 432 00:33:13,080 --> 00:33:15,400 in a single bound. 433 00:33:20,040 --> 00:33:23,520 It may be that by chivvying them in this way 434 00:33:23,520 --> 00:33:25,160 the cheetahs are trying to pick out 435 00:33:25,160 --> 00:33:27,840 the animal that is just a little slower than the others, 436 00:33:27,840 --> 00:33:30,320 just a little more vulnerable. 437 00:34:44,680 --> 00:34:47,400 His jaws are clenched on its windpipe, 438 00:34:47,400 --> 00:34:50,240 and the wildebeest dies throttled. 439 00:34:51,560 --> 00:34:55,360 The other male comes to share the catch. 440 00:35:19,960 --> 00:35:22,520 Cheetahs, like most hunting species, 441 00:35:22,520 --> 00:35:25,480 rarely tackle prey larger than themselves. 442 00:35:25,480 --> 00:35:30,280 But lions are not so restricted. They are social hunters. 443 00:35:30,280 --> 00:35:34,120 They're the biggest, the heaviest of all the hunters on the plains, 444 00:35:34,120 --> 00:35:37,840 and they live in groups, usually about 15 strong, 445 00:35:37,840 --> 00:35:41,000 though sometimes there may be over 30 in a pride. 446 00:35:49,280 --> 00:35:51,240 They're not as fast as the cheetah, 447 00:35:51,240 --> 00:35:53,600 about 35 miles an hour is their top speed, 448 00:35:53,600 --> 00:35:56,960 and out in the open they're no threat to the herds. 449 00:35:56,960 --> 00:35:59,360 The zebras can keep their distance. 450 00:35:59,360 --> 00:36:02,840 Provided they've got this amount of a start in a chase, 451 00:36:02,840 --> 00:36:05,000 the lions will never catch them. 452 00:36:09,440 --> 00:36:12,320 The lions' only chance is to get really close 453 00:36:12,320 --> 00:36:17,120 and then rely on their spectacular acceleration. 454 00:36:17,120 --> 00:36:20,000 Now one lioness begins to stalk, 455 00:36:20,000 --> 00:36:25,200 keeping low and almost invisible in the tawny, sun-withered grass. 456 00:36:32,960 --> 00:36:35,120 The zebra spot her. 457 00:36:44,480 --> 00:36:47,360 Ahead there are other members of the pride. 458 00:36:47,360 --> 00:36:50,200 In their panic, the zebra run towards them, 459 00:36:50,200 --> 00:36:52,160 and now they take up the hunt. 460 00:37:01,200 --> 00:37:05,520 But though she's got hold of it, she can't overpower it by herself. 461 00:37:05,520 --> 00:37:08,000 The others come to her aid. 462 00:37:18,640 --> 00:37:23,920 Now there is food, not just for one hunter, but for the whole pride. 463 00:37:23,920 --> 00:37:26,720 Lions, hunting in groups like this, 464 00:37:26,720 --> 00:37:30,280 kill on average once in every three attempts. 465 00:37:37,200 --> 00:37:39,960 But lions do not always work in groups. 466 00:37:39,960 --> 00:37:43,680 Sometimes a lioness will set out by herself. 467 00:38:20,040 --> 00:38:24,160 Only one in five of these solitary hunts is successful. 468 00:38:24,160 --> 00:38:27,520 Scavenging is a much easier way of getting meat. 469 00:38:27,520 --> 00:38:29,160 Hyenas killed this wildebeest, 470 00:38:29,160 --> 00:38:31,360 but a lioness, so much bigger than they are, 471 00:38:31,360 --> 00:38:34,920 can chase them off if there are only a few of them. 472 00:38:52,040 --> 00:38:54,000 Hyenas are small, 473 00:38:54,000 --> 00:38:56,840 and they can only run about half as fast as the cheetah, 474 00:38:56,840 --> 00:39:00,000 but they make up for that by hunting as a pack. 475 00:39:00,000 --> 00:39:01,720 They have enormous stamina 476 00:39:01,720 --> 00:39:04,320 and can keep up a good speed for a long time, 477 00:39:04,320 --> 00:39:07,640 harrying and wearing down their quarry. 478 00:39:12,960 --> 00:39:18,360 When a pack finally closes in on a wildebeest, there is no escape. 479 00:40:08,520 --> 00:40:12,840 Few creatures can defeat hyenas as long as they work as a team. 480 00:40:12,840 --> 00:40:17,480 A determined pack can even rob a lioness of her kill. 481 00:40:33,480 --> 00:40:37,360 She gives up. Perhaps she'd had enough anyway. 482 00:40:59,320 --> 00:41:03,560 So the pack and teamwork wins again. 483 00:41:08,000 --> 00:41:11,760 Sometimes, though, pack disputes with pack. 484 00:41:11,760 --> 00:41:14,680 This kill was made on the border between the hunting grounds 485 00:41:14,680 --> 00:41:16,080 of two neighbouring packs. 486 00:41:16,080 --> 00:41:18,480 The squabble surges this way and that, 487 00:41:18,480 --> 00:41:22,280 as each gains temporary control of the carcass. 488 00:41:41,840 --> 00:41:46,160 The females of the pack have their own dens where they raise the cubs. 489 00:41:46,160 --> 00:41:49,040 A pack may contain as many as 80 animals. 490 00:41:49,040 --> 00:41:52,960 They communicate with one another in the most comprehensive way, 491 00:41:52,960 --> 00:41:56,120 using sound, gesture and smell. 492 00:41:57,680 --> 00:42:00,080 The tail is particularly eloquent. 493 00:42:00,080 --> 00:42:02,480 Normally it's carried curved down. 494 00:42:02,480 --> 00:42:05,360 Erect like this, it's a sign of aggression. 495 00:42:05,360 --> 00:42:08,840 This female is unsure about her rival. 496 00:42:14,960 --> 00:42:17,800 Now she's happier. 497 00:42:20,720 --> 00:42:24,080 From a very early age, each hyena marks grass stems 498 00:42:24,080 --> 00:42:26,560 with scent from a gland beneath its tail. 499 00:42:35,600 --> 00:42:37,480 When members of the pack meet, 500 00:42:37,480 --> 00:42:41,240 they greet one another with extravagant smells and licks. 501 00:42:41,240 --> 00:42:44,120 Each animal knows its fellows individually, 502 00:42:44,120 --> 00:42:49,000 and each knows its place within the complex hierarchy of the pack. 503 00:42:54,640 --> 00:42:58,480 This elaborate social structure with leaders and followers 504 00:42:58,480 --> 00:43:00,120 and a highly effective system 505 00:43:00,120 --> 00:43:02,320 of communication, on which it's based, 506 00:43:02,320 --> 00:43:05,520 enables the pack to hunt most effectively as a team, 507 00:43:05,520 --> 00:43:08,400 so that the hyenas, small though they may be, 508 00:43:08,400 --> 00:43:11,760 are among the most effective killers on the plains. 509 00:43:11,760 --> 00:43:15,600 Indeed, in some parts it's the hyenas, hunting at night, 510 00:43:15,600 --> 00:43:19,240 that are responsible for the majority of the kills. 511 00:43:27,960 --> 00:43:31,800 Lion society also has a well-defined structure. 512 00:43:31,800 --> 00:43:34,680 The females are the basis of the pride. 513 00:43:34,680 --> 00:43:36,800 There may be a dozen or so of them, 514 00:43:36,800 --> 00:43:40,160 and they are probably all sisters or half-sisters. 515 00:43:47,600 --> 00:43:49,720 They cooperate with one another, 516 00:43:49,720 --> 00:43:52,880 even, on occasion, suckling one another's cubs. 517 00:44:17,760 --> 00:44:21,800 These lionesses will remain together throughout their lives. 518 00:44:21,800 --> 00:44:25,160 The males come from other groups elsewhere to join them. 519 00:44:25,160 --> 00:44:28,320 But once the males are accepted as members of the pride, 520 00:44:28,320 --> 00:44:30,520 they take over much of the responsibility 521 00:44:30,520 --> 00:44:32,160 for defending the territory, 522 00:44:32,160 --> 00:44:36,960 roaring their claims of possession and fighting off intruders. 523 00:44:36,960 --> 00:44:39,360 The females do most of the hunting, 524 00:44:39,360 --> 00:44:42,360 but that doesn't take up much of their time. 525 00:44:42,360 --> 00:44:44,760 Meat is much more nourishing than grass. 526 00:44:44,760 --> 00:44:48,120 A lion can eat as much as 20 kilos at a sitting, 527 00:44:48,120 --> 00:44:52,600 so a single meal will last it two days or even longer. 528 00:44:59,960 --> 00:45:02,840 For the rest of the time there's not much to do 529 00:45:02,840 --> 00:45:04,840 except watch the wildebeest herds 530 00:45:04,840 --> 00:45:07,400 gathering their great quantities of grass. 531 00:46:20,960 --> 00:46:24,800 Eventually the time comes when more meat is needed, 532 00:46:24,800 --> 00:46:27,360 and the pride must hunt again. 533 00:46:29,120 --> 00:46:31,520 The male is not to be disturbed. 534 00:46:31,520 --> 00:46:34,000 He'll follow later when all the work has been done, 535 00:46:34,000 --> 00:46:35,360 and probably just as well. 536 00:46:35,360 --> 00:46:39,360 With a great mane, he's much more conspicuous than they. 537 00:46:55,520 --> 00:46:57,720 The wildebeest have come down 538 00:46:57,720 --> 00:47:00,640 to feed on the lush grass beside a marsh. 539 00:47:07,320 --> 00:47:10,240 The lionesses spread out in line. 540 00:47:43,960 --> 00:47:47,800 The herd won't run into the marsh that lies beyond. 541 00:47:47,800 --> 00:47:50,400 It's a barrier against which they can be trapped. 542 00:47:59,320 --> 00:48:02,160 This lioness leaves the main group 543 00:48:02,160 --> 00:48:05,520 and walks off to the far flank of the herd. 544 00:48:07,880 --> 00:48:11,440 The others slowly advance on the wildebeest, 545 00:48:11,440 --> 00:48:13,760 which move nearer the marsh. 546 00:48:28,840 --> 00:48:32,760 Each lioness seems to keep a close watch on her companions 547 00:48:32,760 --> 00:48:36,840 as they advance together closer and closer. 548 00:48:50,040 --> 00:48:52,000 If the wildebeest get agitated, 549 00:48:52,000 --> 00:48:55,320 the lions simply sit and wait for them to settle again, 550 00:48:55,320 --> 00:48:58,560 which they do just a little nearer the marsh. 551 00:49:55,480 --> 00:49:58,200 Now the ambush is laid. 552 00:50:20,240 --> 00:50:23,800 Back and forth the wildebeest dash in panic and confusion, 553 00:50:23,800 --> 00:50:27,720 and the lionesses have time to select their prey. 554 00:51:19,280 --> 00:51:22,640 Once again jaws are clenched on a throat, 555 00:51:22,640 --> 00:51:26,000 and a wildebeest is throttled. 556 00:51:26,000 --> 00:51:30,800 By the time the others, including the male, arrive, it's dead. 557 00:52:03,880 --> 00:52:06,760 The hunt has produced two kills. 558 00:52:06,760 --> 00:52:10,880 That's more than enough meat for the whole pride. 559 00:52:35,800 --> 00:52:40,600 So the long duels between hunter and hunted fought out on the open plain 560 00:52:40,600 --> 00:52:44,920 led to a great development of teamwork and communication. 561 00:52:44,920 --> 00:52:48,000 One animal came out of the forest to hunt on the plains 562 00:52:48,000 --> 00:52:49,720 that I've not yet mentioned. 563 00:52:49,720 --> 00:52:52,640 That's a particularly interesting one to us, 564 00:52:52,640 --> 00:52:54,520 because it was our ancestor. 565 00:52:54,520 --> 00:52:58,480 To trace it from its origins, we'll have to go back into the forest, 566 00:52:58,480 --> 00:53:00,960 where its cousins still live.