1 00:01:05,465 --> 00:01:09,424 The planet on which we live is in a state of perpetual change. 2 00:01:10,737 --> 00:01:15,299 From cracks in its surface, molten rock is continually erupting. 3 00:01:33,760 --> 00:01:40,165 The forces that drive this lava to the surface als cause the continents to move round the globe, 4 00:01:40,333 --> 00:01:43,427 millimetre by millimetre, over thousands of years. 5 00:01:44,170 --> 00:01:50,973 When they collide, the buckling, contorted rocks are pushed up into great mountain ranges. 6 00:01:53,146 --> 00:02:00,109 Butjust as they rise, so are they cut down by the erosion of ice and snow and rushing water. 7 00:02:05,425 --> 00:02:11,261 At the poles, where the sun's rays strike the glob only obliquely, it's bitterly cold. 8 00:02:11,564 --> 00:02:18,299 Here glaciers grind their way across the land, gouge out deep valleys and flow into the sea. 9 00:02:46,299 --> 00:02:51,293 At the equator, where the sun strikes the earth four-square, the land is baked. 10 00:02:51,938 --> 00:02:55,305 Over centuries, the amount of rain falling on it has varied. 11 00:02:55,675 --> 00:03:01,170 As it diminishes, so the forests have dwindled and been replaced by grassland. 12 00:03:03,016 --> 00:03:07,214 And grassland, if it dries still further, turns to desert. 13 00:03:21,234 --> 00:03:24,601 Throughout all these changes, living creatures have evolved 14 00:03:24,771 --> 00:03:28,639 with a speed that has matched that of the changing landscape. 15 00:03:34,881 --> 00:03:39,375 In the hot deserts, animals have evolved ways of living in oven-like temperatures 16 00:03:39,552 --> 00:03:42,214 without drinking any liquid whatsoever. 17 00:04:02,875 --> 00:04:08,905 In the cold deserts around the poles, other creatures, who generate their own internal heat, 18 00:04:09,082 --> 00:04:14,952 have grown insulating coats of fur and fat so that they are not frozen to death. 19 00:04:50,790 --> 00:04:55,124 Human beings, one of the last species of large animal to appear on the planet, 20 00:04:55,295 --> 00:04:59,755 have spread with extraordinary speed to all corners of the globe. 21 00:05:00,333 --> 00:05:05,361 They've done so not so much because their bodies have changed to match extremes 22 00:05:05,538 --> 00:05:12,273 but because they've used skills and intelligence to exploit the adaptations of other living creatur 23 00:05:13,046 --> 00:05:16,504 The Eskimos survive in the Arctic by keeping themselves warm 24 00:05:16,683 --> 00:05:18,947 with the skins of polar bears and seals. 25 00:05:21,621 --> 00:05:27,025 In the jungles of the Amazon, the Indians have learned where to find and how to collect 26 00:05:27,193 --> 00:05:30,526 everything they need to sustain themselves. 27 00:06:00,026 --> 00:06:04,429 Even though today they may cook in metal pots traded from the outside world, 28 00:06:04,597 --> 00:06:07,691 they still know how to make pottery from the clay. 29 00:06:13,606 --> 00:06:19,704 In the hot deserts of southern Africa, the Bushmen survive droughts by tapping the stores of liquid 30 00:06:19,879 --> 00:06:24,248 held in the bodies of animals and the roots and the stems of plants. 31 00:06:36,996 --> 00:06:41,330 Immediately after the rains, however, they can collect water from natural hollows, 32 00:06:41,501 --> 00:06:43,935 but even that takes knowledge and skill. 33 00:06:50,143 --> 00:06:54,842 Human beings, for nearly all the half-million year of their existence as a species, 34 00:06:55,014 --> 00:06:59,212 have lived by gathering wild plants and hunting wild animals. 35 00:06:59,552 --> 00:07:05,491 10,000 years ago, people were doing so here in the Middle East, as they were everywhere else. 36 00:07:06,159 --> 00:07:08,184 In these forests, there's quite a lot to eat: 37 00:07:08,361 --> 00:07:13,094 Pistachio nuts and wild almonds and acorns and juniper berries. 38 00:07:13,366 --> 00:07:16,961 10,000 years ago there were quite a lot of wild animals: 39 00:07:17,270 --> 00:07:22,503 Wild goat, wild pig, wild horses, giant wild cattle and gazelle. 40 00:07:22,975 --> 00:07:28,436 Even so, there are hardships to be endured. There could be torrential rains. 41 00:07:28,714 --> 00:07:31,740 At night it can get crushingly cold and there could be snow. 42 00:07:31,951 --> 00:07:34,852 During the day it gets bakingly hot. 43 00:07:35,254 --> 00:07:40,487 But about 9,000 years ago, man took a crucial step. 44 00:07:40,927 --> 00:07:44,863 Until then, the environment through evolution had shaped his body, 45 00:07:45,031 --> 00:07:47,363 as it had shaped the bodies of all animals. 46 00:07:47,867 --> 00:07:51,234 But now, uniquely, man turned that around. 47 00:07:51,504 --> 00:07:55,998 He began to change the environment to suit himself, 48 00:07:56,175 --> 00:08:00,805 and one of the places where he first did so is in that valley down there. 49 00:08:03,249 --> 00:08:08,983 This is Beidha in Jordan, and here were found the remains of one of mankind's earliest villages. 50 00:08:10,590 --> 00:08:14,253 This was no temporary encampment, but a permanent settlement 51 00:08:14,427 --> 00:08:17,988 with alleys and houses of stone built adjoining one another. 52 00:08:20,132 --> 00:08:25,729 They were half-dug into the ground, the floor and walls covered with a plaster of mud and lime, 53 00:08:25,905 --> 00:08:30,365 and in the walls were posts which supported a roof of thatch 54 00:08:30,543 --> 00:08:35,139 which probably just cleared the top of the wall so light could get in. 55 00:08:35,414 --> 00:08:41,011 So the people had created a snug home, protected from the rain and the sun, 56 00:08:41,187 --> 00:08:45,783 a place where mothers could bear their children in safety. 57 00:08:49,996 --> 00:08:58,233 There are lots of grinding stones, querns, here, in which the people ground the seeds of grass, 58 00:08:58,404 --> 00:09:02,238 a kind of wild barley that grows abundantly hereabouts. 59 00:09:02,875 --> 00:09:08,006 They'd long since discovered that you could scatter grass seeds and produce a crop. 60 00:09:08,247 --> 00:09:13,981 They'd been doing that with the seeds of another wild grass, wheat, for many centuries. 61 00:09:14,253 --> 00:09:18,849 Now they were settled, it was inconvenient to scour the countryside 62 00:09:19,025 --> 00:09:22,017 to look for places where the grass happened to grow. 63 00:09:22,295 --> 00:09:28,427 Much better to throw it onto the ground near the village, where they could watch the crop, 64 00:09:28,601 --> 00:09:32,970 make sure animals didn't plunder it, and it was convenient to gather. 65 00:09:33,205 --> 00:09:35,969 So these people became farmers. 66 00:09:39,512 --> 00:09:44,973 The people were also meat-eaters, and in this one small chamber 67 00:09:45,151 --> 00:09:49,918 have been found great quantities of the bones of wild goat, like this. 68 00:09:50,289 --> 00:09:55,090 Domesticating animals must have been much more difficult than domesticating plants. 69 00:09:55,328 --> 00:09:59,958 But the first steps towards doing so were probably taken centuries earlier 70 00:10:00,132 --> 00:10:02,464 when the people were still nomads. 71 00:10:03,035 --> 00:10:07,563 A way in which that might have happened can be seen going on today 72 00:10:07,740 --> 00:10:10,709 amongst the Lapp peoples in Scandinavia. 73 00:10:14,580 --> 00:10:21,042 This is the most northerly living of all deer. It' found round the Arctic wherever there is land. 74 00:10:21,420 --> 00:10:25,948 In America, it's called the caribou, in Europe, reindeer. 75 00:10:31,697 --> 00:10:34,860 In North America the caribou are completely wild, 76 00:10:35,034 --> 00:10:40,597 but here in northern Scandinavia they are, to some degree at least, domesticated. 77 00:10:40,940 --> 00:10:46,708 Man has managed to achieve that by becoming a nomad himself. 78 00:10:53,719 --> 00:10:58,850 The reindeer during the winter have to keep on the move in search for something to eat, 79 00:10:59,025 --> 00:11:06,124 and the Lapps, to keep an eye on their herd and maintain possession, have to move with them. 80 00:11:09,802 --> 00:11:14,739 Traditionally, they do so on skis. Indeed, skis originated in this part of the world. 81 00:11:15,207 --> 00:11:19,667 But today the herdsmen are fully up to date with modern technology. 82 00:11:29,989 --> 00:11:35,552 The reindeer's winter food is a kind of lichen which they find growing beneath the snow. 83 00:11:37,763 --> 00:11:39,856 When the reindeer were completely wild, 84 00:11:40,032 --> 00:11:45,971 young stags would wander away from their group, taking a few young females with them. 85 00:11:46,505 --> 00:11:50,737 But the Lapps regarded the offspring of their herd as their property. 86 00:11:50,943 --> 00:11:54,936 To prevent them being lost, they castrated the young males. 87 00:11:55,381 --> 00:11:58,350 The few they left unmutilated in order to breed 88 00:11:58,517 --> 00:12:04,251 were those they thought most likely to remain unaggressive and disinclined to wander. 89 00:12:05,491 --> 00:12:10,986 So, consciously or unconsciously, the Lapps over centuries have changed the reindeer 90 00:12:11,163 --> 00:12:13,859 from a nervous creature living in family groups 91 00:12:14,033 --> 00:12:18,470 to one that is so docile it can be kept in herds thousands strong 92 00:12:18,637 --> 00:12:24,769 and can be moved from one slope to another by leading the way with a stag on a halter. 93 00:12:51,337 --> 00:12:58,004 It may well be that in some such way as this, the people who lived 9,000 years ago in Beidha 94 00:12:58,177 --> 00:13:04,343 gradually turned the wild goats of the surrounding mountains into tamed domesticated ones. 95 00:13:06,418 --> 00:13:11,219 The techniques of domestication and maybe the domesticated animals themselves 96 00:13:11,390 --> 00:13:14,325 slowly spread westwards across Europe. 97 00:13:15,661 --> 00:13:19,927 7,000 years ago, the people living in France had their own herds. 98 00:13:20,299 --> 00:13:25,669 And around 6,000 years ago, the techniques and even perhaps herdsmen with some stock 99 00:13:25,838 --> 00:13:28,636 crossed the channel into Britain. 100 00:13:50,963 --> 00:13:57,061 They must have landed somewhere in southern England, but the land didn't look like this. 101 00:13:57,336 --> 00:14:00,794 Like nearly all the rest of Britain, it was covered in trees. 102 00:14:01,106 --> 00:14:05,975 People were already living in the forests, gathering fruit and nuts 103 00:14:06,145 --> 00:14:09,205 and hunting the wild animals, deer and wild oxen. 104 00:14:09,481 --> 00:14:12,507 But they hadn't changed the woodlands of Britain 105 00:14:12,685 --> 00:14:16,917 any more than the Amazonian Indians have changed the jungle. 106 00:14:17,256 --> 00:14:25,163 But these new arrivals did. They began to clear the forests to make way for their farms. 107 00:14:26,065 --> 00:14:31,469 So this landscape of the South Downs is not natural. It's their creation. 108 00:14:34,740 --> 00:14:38,005 The people cut down the forests with stone axes. 109 00:14:38,310 --> 00:14:41,575 And then the teeth of their flocks kept the land open. 110 00:14:42,147 --> 00:14:45,605 Sheep still prevent the seedlings of trees from growing 111 00:14:45,784 --> 00:14:52,553 and keep the pastures clear for cowslips, clover, orchids, buttercups, pipits and skylarks. 112 00:14:53,158 --> 00:14:56,992 This was the beginning of a process that was to transform Britain. 113 00:14:57,329 --> 00:15:01,663 Much of our apparently wild landscape is in fact man-made. 114 00:15:03,402 --> 00:15:09,500 The Norfolk Broads, that wilderness of shallow lakes, reed beds and winding waterways, 115 00:15:09,742 --> 00:15:16,944 are not natural basins but vast pits, dug by men collecting peat some 600 years ago, 116 00:15:17,116 --> 00:15:18,640 that have subsequently flooded. 117 00:15:29,395 --> 00:15:32,660 Many upland moors of northern England and southern Scotland 118 00:15:32,831 --> 00:15:35,629 were cleared of forests thousands of years ago, 119 00:15:35,801 --> 00:15:39,498 but in the 19th century men encouraged heather to grow there 120 00:15:39,672 --> 00:15:42,539 by setting light to the moors regularly, 121 00:15:42,708 --> 00:15:45,074 for heather is the food of grouse, 122 00:15:45,244 --> 00:15:48,236 and men want flocks of grouse for their guns. 123 00:15:50,683 --> 00:15:54,881 Almost the only part of Britain that remains free of human influence 124 00:15:55,054 --> 00:16:00,788 is the land over 2,500 feet high that is of little practical use to people. 125 00:16:00,993 --> 00:16:05,430 It was scraped clean of soil by glaciers during the Ice Age 10,000 years ago 126 00:16:05,597 --> 00:16:08,088 and still remains stony and barren. 127 00:16:10,602 --> 00:16:17,098 As we transformed the landscape, so we also altered the community of animals that lived here. 128 00:16:17,409 --> 00:16:20,173 Those that didn't suit us, we got rid of. 129 00:16:21,647 --> 00:16:25,310 Brown bears were once common, but they were regarded as dangerous 130 00:16:25,484 --> 00:16:28,942 and they could give good sport if baited with dogs 131 00:16:29,254 --> 00:16:32,883 The last British bear was killed in the 10th century. 132 00:16:34,994 --> 00:16:39,863 Wolves preyed on domesticated flocks and herds and even threatened people. 133 00:16:40,299 --> 00:16:43,598 The last English wolf had been killed by the year 1500 134 00:16:43,769 --> 00:16:47,136 and the last Scottish one by the middle of the 18th century. 135 00:16:53,479 --> 00:16:57,142 Beavers were hunted not so much because of the damage they did 136 00:16:57,316 --> 00:16:59,546 but because their fur was highly valued. 137 00:16:59,952 --> 00:17:02,477 They had all gone by the 13th century. 138 00:17:08,794 --> 00:17:11,456 Wild boar were once common in British woods, 139 00:17:11,630 --> 00:17:15,566 grubbing up roots and bulbs, munching acorns and beech nuts. 140 00:17:16,502 --> 00:17:22,270 But boars could be aggressive and dangerous, and the sows made good eating. 141 00:17:22,574 --> 00:17:26,169 By the 17th century, there were none of these left either. 142 00:17:30,115 --> 00:17:33,516 The elk, known in America as the moose, once lived here too, 143 00:17:33,685 --> 00:17:37,951 but it had been hunted into extinction even before the Romans arrived. 144 00:17:40,526 --> 00:17:43,461 Men also introduced animals to Britain. 145 00:17:43,695 --> 00:17:48,632 The Normans brought fallow deer from Europe. And rabbits. 146 00:17:48,934 --> 00:17:54,463 At first they were guarded in enclosures, for they were valued for their fur and meat. 147 00:17:54,706 --> 00:17:58,733 They only became really common in the countryside during the 19th century. 148 00:18:04,149 --> 00:18:08,882 Pheasants are Asian birds, and were brought here soon after the Norman Conquest. 149 00:18:09,421 --> 00:18:14,188 Other introductions, however, were unintentional and much less welcome. 150 00:18:15,627 --> 00:18:21,497 The house mouse may have been the first animal of all to be brought to Britain by man, 151 00:18:21,667 --> 00:18:24,659 for the Romans found it living in British villages 152 00:18:25,237 --> 00:18:30,641 Other, bigger, animals were living around the settlements of those early British tribes. 153 00:18:31,176 --> 00:18:36,671 Aurochs, the giant cattle whose images were painted in French caves during prehistory, 154 00:18:36,849 --> 00:18:39,340 also roamed in British forests. 155 00:18:39,651 --> 00:18:42,620 By Roman times, some had already been domesticated, 156 00:18:42,788 --> 00:18:47,691 and one of the early strains derived from them still survives in the Cheviot Hills. 157 00:19:02,841 --> 00:19:07,471 This herd at Chillingham was penned in a great park during the 13th century, 158 00:19:07,646 --> 00:19:12,049 and has lived here ever since, with scarcely any interference from human beings. 159 00:19:13,085 --> 00:19:18,045 They may well be very similar to those that wandered around the farms in Roman times. 160 00:19:18,757 --> 00:19:22,784 They're formidable animals, very different from the gentle Friesian of today. 161 00:19:35,807 --> 00:19:39,573 One great bull rules the herd. He mates with all the cows 162 00:19:39,745 --> 00:19:42,714 and fights every young male who challenges him. 163 00:19:49,955 --> 00:19:51,855 Eventually, after two or three years, 164 00:19:52,024 --> 00:19:56,961 he will lose and surrender his place to a younger, more vigorous animal. 165 00:20:14,246 --> 00:20:18,478 Having changed a wild animal into a docile one by selective breeding, 166 00:20:18,650 --> 00:20:23,178 farmers now used the same techniques to modify the animal's body. 167 00:20:23,655 --> 00:20:27,989 They wanted meat, and soon they produced a very different-looking beast. 168 00:20:28,760 --> 00:20:32,218 These portraits, commissioned by breeders 100 years ago, 169 00:20:32,397 --> 00:20:38,597 show that the characteristics they valued in their cattle then are the same as those we prize today. 170 00:20:39,671 --> 00:20:44,768 Today's bulls have such stunted legs that they can't run fast to chase away a rival. 171 00:20:45,043 --> 00:20:48,479 Many don't even have horns with which to fight a courtship battle. 172 00:20:48,847 --> 00:20:52,010 These won't be permitted to mate with a cow. 173 00:20:52,351 --> 00:20:55,980 Their semen will be taken and injected into cows by syringe, 174 00:20:56,154 --> 00:20:58,884 so each one, without moving from his stall, 175 00:20:59,057 --> 00:21:02,993 may father thousands of offspring on the other side of the world. 176 00:21:04,896 --> 00:21:09,026 Under intensive feeding, such cattle can put on two pounds a day 177 00:21:09,201 --> 00:21:13,501 and grow so fast that they can be profitably slaughtered within a year. 178 00:21:15,173 --> 00:21:19,371 The new breeds of pig, descendants of the wild boars of the European forests, 179 00:21:19,544 --> 00:21:26,245 now grow five times faster than their wild cousins and are ready for slaughter within six months. 180 00:21:39,998 --> 00:21:43,559 Turkeys are descended from wild birds in Central America. 181 00:21:43,769 --> 00:21:48,638 They are produced by artificial insemination and have become creatures 182 00:21:48,807 --> 00:21:52,436 that will live not in small family groups but immense congregations. 183 00:21:57,349 --> 00:22:03,015 Chickens, birds of the Asian jungles, have been converted into egg-producing machines 184 00:22:03,188 --> 00:22:05,952 that can lay over 300 eggs a year. 185 00:22:08,827 --> 00:22:15,323 The same techniques produced our food plants, using species from all over the world. 186 00:22:15,567 --> 00:22:19,503 The potato came from the Andes, where it was grown by the Incas. 187 00:22:19,738 --> 00:22:25,301 The pea is a European plant first cultivated by the Italians in the 16th century. 188 00:22:25,577 --> 00:22:31,482 Beans came from Mexico, rhubarb from China, beetroot from Germany. 189 00:22:31,750 --> 00:22:36,346 This plant was first cultivated in the seventh century in Afghanistan, 190 00:22:36,521 --> 00:22:40,924 taken from there to North Africa, then brought by the Moors into Europe, 191 00:22:41,093 --> 00:22:47,225 where it was cultivated by the Dutch to produce... this, a carrot. 192 00:22:47,733 --> 00:22:52,727 But wild plants from the family that is the most important to man for food 193 00:22:52,904 --> 00:22:57,864 don't grow in this allotment because they would be regarded as weeds: The grasses. 194 00:23:03,949 --> 00:23:08,852 The grass we call rice was domesticated in Asia some 7,000 years ago, 195 00:23:09,020 --> 00:23:14,253 at about the same time that people were learning to cultivate wheat around the Mediterranean. 196 00:23:16,928 --> 00:23:23,663 The people of Asia have perfected the techniques of growing one kind of rice in flooded terraces. 197 00:23:24,069 --> 00:23:28,005 They do so with such skill that the rice will flower and ripen 198 00:23:28,173 --> 00:23:31,802 and produce heads of swollen seeds several times a year. 199 00:23:34,146 --> 00:23:40,949 As mankind's population grew, so more and more of the land had to be taken into cultivation. 200 00:23:51,863 --> 00:23:59,031 Today, 11% of all the arable land on earth is devoted to growing just this one species of grass. 201 00:23:59,638 --> 00:24:06,100 Now more than 2,000 million people depend on it, half the population of the world. 202 00:24:16,721 --> 00:24:22,557 In the western world, people still prefer the kind of grass they learned to eat during prehistory, 203 00:24:22,727 --> 00:24:24,991 but that too they have transformed. 204 00:24:26,898 --> 00:24:33,804 Today's wheat grows tall, uniform and dense, so it can be easily harvested by machines. 205 00:24:42,080 --> 00:24:45,413 Selective breeding has greatly increased its yield 206 00:24:45,817 --> 00:24:49,583 Even since the 1940s, its productivity has been doubled. 207 00:24:50,021 --> 00:24:53,684 Today it bears ten times the weight of seeds on each stem 208 00:24:53,859 --> 00:24:58,091 than does its wild ancestor that still grows in the parched lands of the Middle East. 209 00:25:03,235 --> 00:25:11,404 This change has a price. Wheat like this can't even reproduce itself now without man's aid. 210 00:25:11,743 --> 00:25:16,339 It's true that it is largely immune to pests like moulds and rusts, 211 00:25:16,515 --> 00:25:19,814 but moulds and rusts also evolve quickly, 212 00:25:19,985 --> 00:25:24,115 naturally, into forms which can attack the new strains. 213 00:25:24,356 --> 00:25:30,886 So farmers have to change the strain that they grow on average about every ten years. 214 00:25:31,196 --> 00:25:37,658 Today, in North America, over half the wheat comes from just four strains. 215 00:25:37,903 --> 00:25:42,966 Were plant breeders to fail to produce new varieties from wild species, 216 00:25:43,141 --> 00:25:48,272 then fields like this could be devastated and the western world would starve. 217 00:25:49,915 --> 00:25:54,409 To grow the vast quantity of grain needed by mankind's increasing population, 218 00:25:54,586 --> 00:25:59,649 huge areas of the most fertile lands on earth have been turned over to its cultivation. 219 00:26:00,458 --> 00:26:04,895 Gone are the rich communities of grasses and other small plants, 220 00:26:05,063 --> 00:26:08,590 together with hundreds of kinds of insects and small creatures. 221 00:26:09,067 --> 00:26:15,233 Now over thousands of square miles, all other plants and large animals, except human beings, 222 00:26:15,407 --> 00:26:17,375 are rigorously excluded. 223 00:26:17,642 --> 00:26:19,769 Intruders are poisoned or shot. 224 00:26:20,011 --> 00:26:25,039 So mankind has introduced to the earth a completely new type of environment, 225 00:26:25,216 --> 00:26:31,587 a monoculture, one which contains, to all intents and purposes, just one species. 226 00:26:35,260 --> 00:26:39,287 And this is another of mankind's virtual monocultures. 227 00:26:39,631 --> 00:26:43,226 The species that proliferates here and congregates of its own accord 228 00:26:43,401 --> 00:26:48,168 into dense swarms numbering millions is Homo sapiens himself. 229 00:26:48,740 --> 00:26:53,973 The tallest building he's constructed so far is in Chicago, the Sears Tower. 230 00:26:54,613 --> 00:26:58,777 It stands 1,454 feet high. 231 00:26:59,017 --> 00:27:05,581 12,000 people daily come to work in it, and they live in an artificial microclimate 232 00:27:05,757 --> 00:27:09,853 in which the temperature and humidity are controlled by computers. 233 00:27:10,128 --> 00:27:14,155 The whole structure is built of artificial man-made materials, 234 00:27:14,332 --> 00:27:18,962 a framework of steel, with black-skinned aluminium 235 00:27:19,137 --> 00:27:24,165 and bronze-faced glare-reducing glass forming a shell around it. 236 00:27:25,644 --> 00:27:32,447 In such an environment, you might suppose that animals and plants could have no place. 237 00:27:35,820 --> 00:27:37,310 But not so. 238 00:27:39,024 --> 00:27:45,259 Many human beings, it seems, don't wish to live totally out of contact with other living species. 239 00:27:49,134 --> 00:27:54,128 Once again, people have moulded their animals to match their particular whim and fancy, 240 00:27:54,339 --> 00:28:01,871 altering their size, their proportions, their fur. Even their smells. 241 00:28:09,954 --> 00:28:13,253 Dogs first associated with man when he was a nomadic hunter, 242 00:28:13,425 --> 00:28:18,590 accepting him as a leader, helping him to track and pull down his quarry, 243 00:28:18,830 --> 00:28:20,821 and taking a share in the spoils, 244 00:28:21,533 --> 00:28:26,163 but now that man no longer hunts, his dogs must play a very different role. 245 00:28:40,452 --> 00:28:43,853 Cats are not, in the wild, social animals like dog 246 00:28:44,022 --> 00:28:47,685 but solitary hunters with strong territorial instincts. 247 00:28:50,695 --> 00:28:55,826 They probably decided of their own accord to move into houses and hunt rats and mice, 248 00:28:56,000 --> 00:29:01,563 and people accepted them because of this useful service, and because they're endearing, 249 00:29:02,173 --> 00:29:06,667 but to this day they have remained independent operators, aloof and haughty, 250 00:29:06,845 --> 00:29:12,147 even when people have bred them to exaggerate the most cuddlesome of their characteristics. 251 00:29:23,795 --> 00:29:27,754 A few other living organisms have discovered that the city suits them. 252 00:29:28,099 --> 00:29:32,866 The well-drained sterility of a lava flow is not unlike that of a city street, 253 00:29:33,037 --> 00:29:39,203 and in the 18th century a botanist found a yellow ragwort growing on the slopes of Mount Etna. 254 00:29:41,012 --> 00:29:45,312 He took it back to Oxford, where it was cultivated in the botanic gardens. 255 00:29:48,419 --> 00:29:53,152 60 years later, the ragwort was noticed growing on the stones of college walls, 256 00:29:53,324 --> 00:29:55,849 but for quite a time it spread no further. 257 00:29:58,062 --> 00:30:02,465 Then, in the 19th century, railways were built across Britain. 258 00:30:03,334 --> 00:30:08,033 The stone rubble on which the tracks were laid was exactly what the ragwort liked. 259 00:30:08,306 --> 00:30:13,141 It spread along the railways to appear in all the cities along the main lines, 260 00:30:13,311 --> 00:30:15,108 where it still flourishes today. 261 00:30:21,352 --> 00:30:27,291 A few wild animals have found what they need in man's apparently hostile wildernesses. 262 00:30:27,659 --> 00:30:31,823 The sea otter swims happily in the waters of California's harbours. 263 00:30:33,798 --> 00:30:40,067 Prairie dogs, driven off the prairies by ranchers, find new homes in urban playgrounds. 264 00:30:41,172 --> 00:30:45,108 English foxes have discovered a rich source of food in city litter bins 265 00:30:45,276 --> 00:30:47,369 and doze on suburban roofs. 266 00:30:51,783 --> 00:30:57,187 And in the south-west of the United States, acorn woodpeckers store their acorns 267 00:30:57,355 --> 00:31:02,019 in the trunks of fir trees, even when they've been turned into telegraph poles. 268 00:31:11,970 --> 00:31:15,497 Ospreys habitually build their nests in the very tops of trees, 269 00:31:15,673 --> 00:31:20,007 and telegraph poles also give them the kind of isolation they need. 270 00:31:23,147 --> 00:31:27,880 Church towers, to kestrels, are just as good nesting sites as rocky crags. 271 00:31:36,060 --> 00:31:42,898 Kittiwakes apparently regard modern buildings as little more than particularly regular sea cliff 272 00:31:50,074 --> 00:31:54,773 Swallows learned to tolerate man for the sake of the nest sites beneath his eaves, 273 00:31:54,946 --> 00:31:57,073 and now few nest anywhere else. 274 00:31:58,016 --> 00:32:01,144 But not all people's urban companions are so welcome. 275 00:32:03,187 --> 00:32:09,786 There are still plenty of creatures, mammals and insects, that claim a share of mankind's food. 276 00:32:18,469 --> 00:32:23,031 Many insects eat cellulose, and find it in abundance in wood 277 00:32:23,207 --> 00:32:25,903 and in the paper with which people surround themselves. 278 00:32:34,252 --> 00:32:38,484 Grubs chew the sheep hair with which clothes are made. 279 00:32:39,924 --> 00:32:46,955 This whole community of insects is in turn preyed upon by other unwelcome creatures: Spiders. 280 00:32:50,134 --> 00:32:53,865 So we wage war on the animals that have come to live with us. 281 00:33:05,049 --> 00:33:10,578 Brown rats originated somewhere in Asia and spread to Europe some 300 years ago. 282 00:33:10,822 --> 00:33:14,383 Today, rats are found in every large city in the world. 283 00:33:14,726 --> 00:33:20,426 They will eat almost anything, tackling meat with as much relish as grain and vegetables. 284 00:33:25,937 --> 00:33:32,103 They gnaw electric cables, causing short circuits and even, in consequence, fires. 285 00:33:36,447 --> 00:33:42,511 They not only consume huge quantities of food, but contaminate much of what they leave, 286 00:33:42,887 --> 00:33:44,514 and they spread disease. 287 00:33:45,857 --> 00:33:50,294 So if we're not to be overrun, we have to pursue them wherever they go. 288 00:33:50,661 --> 00:33:56,361 We created the city, and if it's to function prope and be neither oppressively sterile 289 00:33:56,534 --> 00:34:01,904 nor infested with pests, we have to manage the living organisms that live in it, 290 00:34:02,073 --> 00:34:05,270 encouraging some, exterminating others. 291 00:34:05,643 --> 00:34:09,636 But our influence spreads far wider than we often choose to recognise. 292 00:34:09,814 --> 00:34:16,276 We're changing the whole of the globe, and we must accept our responsibilities of managing that, 293 00:34:16,454 --> 00:34:19,981 but so far we are making a very poorjob of it. 294 00:34:24,228 --> 00:34:28,289 We have to rid our cities of the vast quantity of rubbish we create. 295 00:34:31,302 --> 00:34:36,706 New York City produces 22,000 tons of refuse every single day. 296 00:34:37,809 --> 00:34:43,270 Half of that is taken by barge down the Hudson River and dumped on Staten Island. 297 00:34:57,829 --> 00:35:03,165 The rubbish is laid down in a layer several feet thick and 200 feet wide. 298 00:35:03,501 --> 00:35:10,373 Every day it advances 100 feet. When the land is covered, another layer is dumped on top. 299 00:35:18,516 --> 00:35:21,883 This is a very expensive way of getting rid of our rubbish. 300 00:35:22,286 --> 00:35:26,222 If there are cheaper ways of doing so, we take them, 301 00:35:26,457 --> 00:35:30,621 telling ourselves if it's out of sight, it doesn't matter what happens to it, 302 00:35:30,895 --> 00:35:33,830 assuming that somehow the world is so large 303 00:35:33,998 --> 00:35:37,798 that our poisons will simply be lost in its immensities. 304 00:35:39,637 --> 00:35:43,403 So we pour our waste chemicals and detergents into our rivers. 305 00:35:43,574 --> 00:35:46,941 Suds may or may not have been valuable in a sink. 306 00:35:47,178 --> 00:35:51,171 In a river they can be lethal, killing the plants and the fish. 307 00:35:57,955 --> 00:36:03,518 We spill oil into the sea, in spite of all the precautions, and set the waves aflame, 308 00:36:03,694 --> 00:36:08,722 and now there are patches of oil polluting even the remotest parts of the widest oceans. 309 00:36:20,778 --> 00:36:24,009 And we poison the very air we breathe. 310 00:36:25,449 --> 00:36:29,681 Fumes belched from our engines fill the atmosphere of the city. 311 00:36:39,463 --> 00:36:44,662 Steam rising from the cooling towers of power stations is relatively harmless, 312 00:36:44,835 --> 00:36:49,033 but the gases produced by burning coal and oil are certainly not. 313 00:36:49,507 --> 00:36:51,941 Our solution has been quite simple: 314 00:36:52,109 --> 00:36:57,809 To build chimneys even taller, so that the gases are blown farther away from our cities, 315 00:36:57,982 --> 00:36:59,609 but they don't disappear. 316 00:37:00,585 --> 00:37:05,022 They're carried by the prevailing winds to countries hundreds of miles away. 317 00:37:05,690 --> 00:37:10,627 The lakes of Scandinavia have, over the past few decades, become more and more acid 318 00:37:10,795 --> 00:37:14,663 until now fish and plants can no longer survive in many. 319 00:37:14,999 --> 00:37:21,563 In Norway alone, there are now 1,800 lakes without fish, and hundreds more that are dying, 320 00:37:21,872 --> 00:37:25,808 shameful monuments to our carelessness and lack of concern. 321 00:37:30,281 --> 00:37:33,944 In Germany, 10% of the forests are seriously damaged, 322 00:37:34,118 --> 00:37:37,884 almost certainly due to industrial pollution of the atmosphere 323 00:37:38,055 --> 00:37:41,115 and the collection of the poisons from it by rain. 324 00:37:44,962 --> 00:37:50,127 But we don't only despoil the natural world by accident. We do so quite deliberately. 325 00:37:51,802 --> 00:37:54,134 These islands, off the coast of Peru, 326 00:37:54,305 --> 00:38:00,676 may seem, on the face of it, to be the very picture of fertility and ecological succe 327 00:38:01,379 --> 00:38:06,009 They're the home of a great variety of seabirds: Cormorants and pelicans, 328 00:38:06,183 --> 00:38:09,277 boobies, terns and gulls. 329 00:38:20,698 --> 00:38:24,464 But 30 years ago, another bird was also living here: 330 00:38:24,802 --> 00:38:27,930 These, a kind of cormorant called the guanay. 331 00:38:28,239 --> 00:38:30,969 When these pictures were taken in the 1950s, 332 00:38:31,142 --> 00:38:35,806 five and a half million of them were nesting on just one of these islands. 333 00:38:36,147 --> 00:38:39,412 The guanay lives exclusively on anchovies and, oddly, 334 00:38:39,583 --> 00:38:44,987 excretes an unusually high proportion of the fish it eats as droppings or guano. 335 00:38:45,389 --> 00:38:50,656 No rain falls here, so the guano wasn't washed away but accumulated on the rocks. 336 00:38:50,961 --> 00:38:56,490 100 years ago the world realised that this was a fertiliser of unparalleled richnes 337 00:38:56,701 --> 00:39:01,968 It was collected and sold for such high prices that the guanay cormorant 338 00:39:02,139 --> 00:39:05,734 became known as the most valuable bird in the world. 339 00:39:06,844 --> 00:39:11,076 But then, in the 1950s, chemical fertilisers were developed in Europe, 340 00:39:11,248 --> 00:39:17,619 the price of guano began to drop and the people started to harvest not the guanay's droppings, 341 00:39:17,788 --> 00:39:20,552 but its food: Anchovies. 342 00:39:22,059 --> 00:39:26,655 In one year, 14 million tons of anchovies were taken out of these waters. 343 00:39:26,864 --> 00:39:31,358 They were sold not to feed people but cattle, chickens and pets. 344 00:39:31,702 --> 00:39:35,502 The fishing was so intense that the anchovies were almost wiped out. 345 00:39:35,740 --> 00:39:40,074 That in turn brought about the collapse of the guanay cormorants' population. 346 00:39:40,444 --> 00:39:45,507 And now for every 50 cormorants that used to live here, 347 00:39:45,683 --> 00:39:47,651 you're lucky if you find one. 348 00:39:47,985 --> 00:39:52,922 And these walls that would be filled with guano to the top inside two years, 349 00:39:53,090 --> 00:39:57,720 now seldom accumulate more than an inch or so. 350 00:39:58,429 --> 00:40:04,265 But the cormorants shed their guano not only on the land but in the sea. 351 00:40:04,502 --> 00:40:08,996 Indeed, for every drop they put on land, they shed 20 into the sea. 352 00:40:09,373 --> 00:40:13,309 There it fertilises water just as it fertilises the land, 353 00:40:13,477 --> 00:40:18,414 promoting the growth of floating plants, plankton, the food of the anchovy. 354 00:40:18,649 --> 00:40:22,779 So if you get less anchovies, you get less cormorants, 355 00:40:22,953 --> 00:40:25,979 and if you get less cormorants, you get less anchovies. 356 00:40:26,457 --> 00:40:31,986 Anchovies are food notjust for cormorants but for sea fish like tuna and sea bass. 357 00:40:32,296 --> 00:40:37,893 So, with that one rash act of overfishing 30 years ago, 358 00:40:38,068 --> 00:40:40,764 Peru has lost anchovies, 359 00:40:40,938 --> 00:40:46,308 cormorants, guano and sea fish. 360 00:40:47,111 --> 00:40:49,477 It's a major blow to the nation's economy. 361 00:40:50,981 --> 00:40:53,950 Nor do we seem to learn from our mistakes. 362 00:40:54,251 --> 00:40:57,584 We're making similar catastrophic misjudgements, 363 00:40:57,755 --> 00:41:02,522 and on an even greater scale, in the world's tropical rainforests. 364 00:41:03,093 --> 00:41:08,121 This, the richest of all living communities, has been of enormous value to us. 365 00:41:08,399 --> 00:41:12,802 It's provided industry with rubber, craftsmen with hardwoods, 366 00:41:12,970 --> 00:41:16,701 and our larders with bananas, nuts, chewing gum and chocolate. 367 00:41:17,007 --> 00:41:21,603 Many of our drugs are based on animals and plants that live here. 368 00:41:21,779 --> 00:41:28,548 And still we have only investigated in detail the biochemistry of less than 1% of the plants. 369 00:41:29,019 --> 00:41:35,549 And here, too, live some of the most beautiful and bizarre creatures to be found anywhere. 370 00:42:10,895 --> 00:42:15,389 These animals are the product of millions of years of evolution in these forests 371 00:42:15,766 --> 00:42:22,934 They can't live anywhere else. The numbers of each species in a given area remains stable, 372 00:42:23,107 --> 00:42:27,669 but over the past few centuries one species of animal outside the forest 373 00:42:27,845 --> 00:42:32,646 has suddenly started to increase in numbers in a way that is without parallel. 374 00:42:41,492 --> 00:42:46,862 In South-East Asia, as in South America and Africa, thousands of extra people every year 375 00:42:47,031 --> 00:42:50,626 are seeking land on which to grow food for themselves. 376 00:42:50,901 --> 00:42:54,701 They take it from the forest. The labour is huge. 377 00:42:54,872 --> 00:43:00,538 After the trees have been felled and burnt, the people sow their crops, in this case, hill ric 378 00:43:02,112 --> 00:43:08,711 After a month, it's as tall as this, and in only five months it will be ready to be harvested, 379 00:43:08,886 --> 00:43:14,483 and it will have been sustained by this, the ash from the burnt forest. 380 00:43:15,059 --> 00:43:19,052 But there are only enough nutrients in this to sustain one crop. 381 00:43:19,330 --> 00:43:26,498 So next year the people plant not rice but this, cassava or tapioca, as it's called here. 382 00:43:26,704 --> 00:43:31,539 This is a different crop, a root crop, which gets nutrients from deeper in the soil, 383 00:43:31,709 --> 00:43:35,270 but even this can only produce for one year. 384 00:43:35,512 --> 00:43:41,883 After that, the seeds from the wild forest will come in and new plants will grow, 385 00:43:42,052 --> 00:43:44,418 producing a landscape like that. 386 00:43:45,022 --> 00:43:50,722 But they will have to grow for eight to ten years before they are big enough 387 00:43:50,894 --> 00:43:56,093 to be felled and produce enough ash and nutrients to refertilise the soil 388 00:43:56,266 --> 00:43:58,564 and allow the people to take a second crop. 389 00:43:59,637 --> 00:44:06,372 And the true forest, with all its original richnes of animals and plants, will never be restored. 390 00:44:10,314 --> 00:44:13,408 It's not only the local people who cut down the forest. 391 00:44:13,684 --> 00:44:17,211 So, indirectly, do the people of the developed world. 392 00:44:35,105 --> 00:44:37,733 The huge trees are in perpetual demand 393 00:44:37,908 --> 00:44:41,810 to provide timber for furniture, for constructing buildings and crates 394 00:44:41,979 --> 00:44:47,007 and above all for the paper for which the world has an unquenchable appetite. 395 00:44:47,384 --> 00:44:53,653 So a tree that took 200 years to grow is now cut down by a chainsaw in five minutes. 396 00:45:00,497 --> 00:45:04,627 The gigantic trunks, which once could only be shifted by elephants 397 00:45:04,802 --> 00:45:08,363 and only be extracted from forests growing on flat country, 398 00:45:08,539 --> 00:45:12,566 are now handled with terrifying ease by modern machinery. 399 00:45:23,053 --> 00:45:27,752 Sometimes only the biggest trees are taken, leaving smaller ones standing, 400 00:45:27,925 --> 00:45:31,827 but the damage is such that the forest is largely beyond recovery. 401 00:45:32,262 --> 00:45:38,531 As the international price of timber increases, so more of the tropical forest is destroyed. 402 00:45:38,769 --> 00:45:43,331 In South-East Asia, it's been reduced to about a third of its original size, 403 00:45:43,507 --> 00:45:49,275 and, in the world at large, an area the size of Switzerland is being destroyed every year. 404 00:45:53,584 --> 00:45:55,643 But this may be a ray of hope. 405 00:45:56,220 --> 00:46:02,648 This is the fastest-growing tree in the world. It' called Albizia and comes from eastern Indonesia, 406 00:46:02,826 --> 00:46:07,263 and can be planted immediately after the felling of the jungle. 407 00:46:07,765 --> 00:46:12,862 In just one year it can grow to 10 or 11 metres tall, 35 feet. 408 00:46:13,070 --> 00:46:19,703 This one is some two years old and in only another six years it will be ready for logging. 409 00:46:21,445 --> 00:46:25,779 Albizia will grow well on the poor land that once supported rainforest, 410 00:46:25,949 --> 00:46:31,581 and many sawmills actually prefer small, easily handled logs of uniform size. 411 00:46:33,190 --> 00:46:39,186 So if it were possible to produce this kind of timber on a really large scale, 412 00:46:39,363 --> 00:46:42,264 it might no longer be necessary to continue 413 00:46:42,432 --> 00:46:49,929 the extremely expensive and appallingly destructive business of felling the wild trees. 414 00:46:50,307 --> 00:46:54,141 And were that to happen, then, in some parts of the world, 415 00:46:54,311 --> 00:46:58,805 away from the coasts and the rivers, in remote and mountainous country, 416 00:46:58,982 --> 00:47:02,474 the tropical rainforest might still survive. 417 00:47:11,595 --> 00:47:17,591 The great rivers of the world can also yield riche to mankind, not simply food but power. 418 00:47:36,153 --> 00:47:41,614 We've known for almost a century how to turn the force of water into electric power 419 00:47:42,125 --> 00:47:48,086 We've made mistakes. The dams have filled up with silt and become useless within decades, 420 00:47:48,265 --> 00:47:53,635 and fields downriver, robbed of their annual suppl of fertilising mud, have turned to desert. 421 00:47:56,473 --> 00:48:00,876 But we're getting better at it, and we're doing it on a greater scale. 422 00:48:01,245 --> 00:48:04,737 This dam, at Itaipu between Paraguay and Brazil, 423 00:48:05,048 --> 00:48:09,610 will harness the power of one of South America's greatest rivers, the Parana. 424 00:48:16,226 --> 00:48:19,992 I am walking across what was once the bed of that river. 425 00:48:20,364 --> 00:48:24,892 And above me rises the biggest dam ever built by man. 426 00:48:25,435 --> 00:48:31,840 It contains enough concrete to construct a whole city to house four million people. 427 00:48:32,209 --> 00:48:38,114 It will make a lake which will stretch upstream for 140 kilometres. 428 00:48:38,582 --> 00:48:43,918 And the power it will produce will be enough to supply the whole of Paraguay 429 00:48:44,087 --> 00:48:49,115 and the great cities of southern Brazil: Sao Paolo and Rio de Janeiro. 430 00:48:49,693 --> 00:48:56,098 And the astonishing thing is that it will have taken only seven years to build. 431 00:48:59,636 --> 00:49:02,469 There will, of course, be a heavy price to pay. 432 00:49:02,673 --> 00:49:08,009 44,000 people will have to be moved and their villages and fields submerged, 433 00:49:08,178 --> 00:49:11,807 fields that produce 200,000 tons of food a year, 434 00:49:11,982 --> 00:49:15,076 and that will create further demands on the rainforest. 435 00:49:21,325 --> 00:49:24,726 Even so, this major reshaping of the surface of the earth 436 00:49:24,895 --> 00:49:30,299 is likely to be one of the less damaging of those that mankind has inflicted on the planet. 437 00:49:30,934 --> 00:49:34,802 A million trees of 50 species will be planted around the lake 438 00:49:34,972 --> 00:49:37,338 to prevent silt from washing into it. 439 00:49:38,008 --> 00:49:41,739 The water will slowly clear and develop a population of fish. 440 00:49:42,279 --> 00:49:46,773 And the turbines will produce power without poisoning the atmosphere 441 00:49:46,950 --> 00:49:49,350 or leaving behind radioactive waste. 442 00:49:50,020 --> 00:49:54,047 They will not deplete the earth's irreplaceable reserves of fossil fuel, 443 00:49:54,224 --> 00:50:00,026 and the dam will continue to produce electricity, it's estimated, for the next 300 years. 444 00:50:05,102 --> 00:50:07,332 The scale of this immense construction 445 00:50:07,504 --> 00:50:11,463 is awe-inspiring evidence of the power we now have in our hands 446 00:50:11,641 --> 00:50:14,633 with which to transform the face of the earth. 447 00:50:19,116 --> 00:50:23,917 When, in prehistoric times, these stones were first put up to build this templ 448 00:50:24,087 --> 00:50:29,525 in the west of England at Avebury, they too must have been an astonishment to people, 449 00:50:29,693 --> 00:50:35,154 an amazing demonstration of how clever, how powerful, human beings had become. 450 00:50:35,399 --> 00:50:41,804 And yet that was less than 5,000 years ago, a mere moment in the history of life. 451 00:50:42,172 --> 00:50:48,771 And in the brief period since then, men have gone on to learn how to build dams like Itaipu, 452 00:50:48,945 --> 00:50:54,008 how to mould animals and plants to suit their needs or their fancies, 453 00:50:54,184 --> 00:50:56,982 how to transform whole landscapes. 454 00:50:57,454 --> 00:51:00,218 Immensely powerful though we are today, 455 00:51:00,390 --> 00:51:04,793 it's equally clear that we're going to be even more powerful tomorrow. 456 00:51:05,162 --> 00:51:09,121 And there will be greater compulsion to use our power 457 00:51:09,299 --> 00:51:13,167 as the number of human beings on earth increases still further. 458 00:51:13,537 --> 00:51:17,371 Clearly, we could devastate the world. 459 00:51:17,808 --> 00:51:20,470 If we're not to do so, we must have a plan. 460 00:51:20,877 --> 00:51:24,074 A plan has been formulated by environmental scientists. 461 00:51:24,247 --> 00:51:30,083 They called it the World Conservation Strategy and it rests on three simple propositions. 462 00:51:30,320 --> 00:51:35,986 One: That we shouldn't so exploit natural resources that we destroy them. 463 00:51:36,426 --> 00:51:41,363 Common sense, you might think. Yet look what we've done to the European herring, 464 00:51:41,531 --> 00:51:45,297 the South American anchovy, and are still doing to the whales. 465 00:51:45,969 --> 00:51:51,464 Two: We shouldn't interfere with the basic processes of the earth on which life depends, 466 00:51:51,641 --> 00:51:56,169 in the sky, on the green surface of the earth and in the sea. 467 00:51:56,413 --> 00:52:01,817 And yet we go on pouring poisons into the sky, cutting down the tropical rainforest, 468 00:52:01,985 --> 00:52:04,476 dumping our rubbish into the oceans. 469 00:52:04,855 --> 00:52:09,815 And third, that we should preserve the diversity of life. 470 00:52:10,293 --> 00:52:15,128 That's notjust because we depend upon it for our food, though we do, 471 00:52:15,298 --> 00:52:19,928 nor because we still know so little about it that we won't know what we are losing, 472 00:52:20,103 --> 00:52:25,234 though that is the case as well, but it is surely that we have no moral right 473 00:52:25,408 --> 00:52:29,868 to destroy other living organisms with which we share the earth. 474 00:52:30,780 --> 00:52:37,083 As far as we know, the earth is the only place in the universe where there is life. 475 00:52:38,088 --> 00:52:43,025 Its continued survival now rests in our hands.