1 00:00:38,767 --> 00:00:42,840 Leafcutter ants cleaning the refuse out of their nest. 2 00:00:43,727 --> 00:00:47,959 Every single one of these tiny creatures knows where it's going 3 00:00:48,047 --> 00:00:51,005 and what it's got to do when it gets there. 4 00:00:51,087 --> 00:00:54,363 And furthermore, there are about 10 million more of them 5 00:00:54,447 --> 00:00:57,723 in this huge underground nest beneath me. 6 00:00:58,487 --> 00:01:02,480 They're all members of one highly organised society. 7 00:01:02,847 --> 00:01:08,479 But they're not the blindly mechanical robotic slaves that we once thought they were. 8 00:01:09,247 --> 00:01:13,160 Indeed, we now know that every insect society 9 00:01:13,247 --> 00:01:18,446 is full of conflict, power struggles and mutinies. 10 00:01:23,607 --> 00:01:28,397 Social insects construct the tallest of all non-human buildings. 11 00:01:29,487 --> 00:01:33,162 Like these huge termite hills here in Australia. 12 00:01:34,687 --> 00:01:37,804 They protect their colonies with great ferocity. 13 00:01:38,847 --> 00:01:43,079 They increase the size of their societies at an alarming rate. 14 00:01:46,727 --> 00:01:52,120 And they're capable of mobilising huge armies to make wars on their neighbours. 15 00:01:54,047 --> 00:01:57,403 But how did these great communities develop? 16 00:01:57,487 --> 00:02:02,766 Most insects, like this little sand wasp here in the deserts of Arizona, 17 00:02:02,847 --> 00:02:04,963 live solitary lives. 18 00:02:05,807 --> 00:02:11,518 This one has just dug a hole in which she is going to lay her eggs. 19 00:02:12,367 --> 00:02:15,006 But then she does something else. 20 00:02:15,487 --> 00:02:20,322 She will cater for her as yet unhatched young 21 00:02:20,407 --> 00:02:25,800 by putting a caterpillar inside that hole on which they can feed. 22 00:02:25,887 --> 00:02:32,122 And that is a very important stage in the development of the social life. 23 00:02:34,207 --> 00:02:39,725 In fact, it's the very basis on which all the great insect societies are built. 24 00:02:41,327 --> 00:02:45,878 This species of wasp, however, is still at the stage of working alone. 25 00:02:48,727 --> 00:02:54,245 After stocking each nest with a caterpillar, she blocks the entrance to deter thieves. 26 00:02:56,687 --> 00:02:59,281 Her burrow may be several centimetres deep. 27 00:03:00,407 --> 00:03:03,080 At the bottom, lies the paralysed caterpillar. 28 00:03:03,167 --> 00:03:07,604 And on its back there is now a wasp grub feeding on it. 29 00:03:11,087 --> 00:03:14,682 The female wasp makes several of these nests a few feet apart 30 00:03:14,807 --> 00:03:18,277 and stocks each of them with living food for her young. 31 00:03:20,407 --> 00:03:23,160 Can there be a more hardworking mother? 32 00:03:24,567 --> 00:03:28,162 Despite all her attempts at parental care, 33 00:03:28,247 --> 00:03:31,762 the vast majority of her young will not survive. 34 00:03:32,167 --> 00:03:35,762 She's too busy hunting for more caterpillars 35 00:03:35,847 --> 00:03:38,600 to be able to guard all her nest sites. 36 00:03:41,887 --> 00:03:44,845 Back in the distant evolutionary past, 37 00:03:44,927 --> 00:03:49,045 other wasps started to build their nests alongside one another. 38 00:03:49,447 --> 00:03:53,486 And here on the coast of Panama, paper wasps still do so. 39 00:03:54,447 --> 00:03:56,403 Grouping their cells together 40 00:03:56,487 --> 00:03:59,763 means that even though you have to leave your eggs to collect food, 41 00:03:59,847 --> 00:04:02,839 there will always be someone around on guard. 42 00:04:04,767 --> 00:04:06,883 The wasps are all sisters. 43 00:04:06,967 --> 00:04:10,846 But, as often happens, one tends to dominate the rest. 44 00:04:11,407 --> 00:04:14,763 She starts to bite her sisters with great brutality. 45 00:04:14,847 --> 00:04:16,838 She is the boss, the queen. 46 00:04:16,927 --> 00:04:20,966 The others may build cells, but only she will lay eggs in them. 47 00:04:24,087 --> 00:04:28,046 Many of the genes in these eggs are the same as those carried by her sisters, 48 00:04:28,127 --> 00:04:31,756 and the sisters look after the eggs as if they were their own. 49 00:04:32,287 --> 00:04:36,917 And now, because the nest is so well-guarded, the family rears more young 50 00:04:37,047 --> 00:04:39,959 than if each female were to nest alone. 51 00:04:41,527 --> 00:04:45,839 So, as each egg is laid, the sisters take steps to protect it. 52 00:04:45,927 --> 00:04:48,680 To do that, they need building material. 53 00:04:51,807 --> 00:04:53,684 They chew wood into pulp 54 00:04:53,767 --> 00:04:58,158 and then use it to build a protective wall around each egg, a cell. 55 00:04:58,247 --> 00:05:01,284 So a colonial nest begins to grow. 56 00:05:03,207 --> 00:05:05,960 With more and more young females needing to be fed, 57 00:05:06,047 --> 00:05:08,117 the adults go hunting. 58 00:05:41,047 --> 00:05:45,598 Each returning wasp bringing prey is greeted by the other workers. 59 00:05:47,967 --> 00:05:52,085 They squabble over food. The queen takes the lion's share. 60 00:05:52,167 --> 00:05:55,603 Those of her sisters and daughters who are high up on the social scale 61 00:05:55,687 --> 00:06:00,078 also get big helpings because they bully the junior females. 62 00:06:08,887 --> 00:06:12,516 In fact, the food isn't eaten by the adult who wins it. 63 00:06:12,607 --> 00:06:15,917 She feeds it to her developing younger sisters. 64 00:06:28,087 --> 00:06:31,921 This grouping, an enormous single sex family, 65 00:06:32,007 --> 00:06:35,317 was the first step towards the development of insect societies 66 00:06:35,407 --> 00:06:40,162 containing millions of individuals, and it's still their basic structure. 67 00:06:43,687 --> 00:06:46,724 The forests in which the first wasps hunted 68 00:06:46,807 --> 00:06:50,243 were dominated by horsetails and conifers. 69 00:06:50,727 --> 00:06:54,322 They relied upon the wind to distribute their pollen. 70 00:06:54,407 --> 00:06:57,479 But then about 100 million years ago, 71 00:06:57,567 --> 00:07:01,924 a new kind of plant appeared which recruited insects to do the job. 72 00:07:02,207 --> 00:07:05,324 And they did it with nectar-loaded flowers. 73 00:07:08,327 --> 00:07:13,959 Some of these recruits then abandoned hunting and concentrated instead on this new food. 74 00:07:14,047 --> 00:07:15,685 They became bees. 75 00:07:18,807 --> 00:07:22,766 Today, there are about 20,000 different species of them. 76 00:07:28,247 --> 00:07:32,160 This queen bumblebee mated at the end of last summer 77 00:07:32,247 --> 00:07:34,283 before she hibernated. 78 00:07:34,367 --> 00:07:38,246 But now she's gone off to look for a new home 79 00:07:38,327 --> 00:07:41,797 because she's ready, at last, to lay those eggs. 80 00:07:44,847 --> 00:07:48,806 She may take some time to find just the right place. 81 00:07:54,087 --> 00:07:55,964 A deserted mouse hole. 82 00:07:56,407 --> 00:07:57,681 Ideal. 83 00:07:59,807 --> 00:08:05,518 First, she makes a little wax pot in which she lays a group of fertilised eggs. 84 00:08:05,607 --> 00:08:08,644 In due time, these hatch into young females. 85 00:08:08,727 --> 00:08:13,164 The queen now has her subjects. A colony has been established. 86 00:08:14,127 --> 00:08:17,119 From now on, she does little building herself. 87 00:08:17,207 --> 00:08:19,004 Her daughters take on that job 88 00:08:19,087 --> 00:08:22,045 and they use a material that no wasp ever had. 89 00:08:22,127 --> 00:08:24,846 It oozes from between their body segments. 90 00:08:24,927 --> 00:08:26,360 It's wax. 91 00:08:27,127 --> 00:08:31,325 The queen also produces a chemical substance that permeates the nest 92 00:08:31,407 --> 00:08:34,285 and keeps her daughters' sexuality in check. 93 00:08:34,847 --> 00:08:39,443 Their job is not to produce eggs, but to look after their younger sisters. 94 00:08:43,727 --> 00:08:47,766 More and more young workers are hauling themselves out of their cells. 95 00:08:57,167 --> 00:09:00,842 They don't have to travel far to find their first adult meal. 96 00:09:02,607 --> 00:09:07,442 In fact, to begin with, they stay inside the nest helping with nest duties, 97 00:09:07,527 --> 00:09:11,566 feeding the young, keeping the place clean, building more cells. 98 00:09:13,487 --> 00:09:18,880 After a few days, they begin to venture outside the nest to help in collecting food. 99 00:09:21,527 --> 00:09:26,760 If the colony is to be properly nourished, they must gather not only nectar, but pollen. 100 00:09:36,447 --> 00:09:39,280 Nectar, they transport in their crops 101 00:09:39,367 --> 00:09:45,124 but pollen is held in a tiny ball by a brush of stiff hairs on their two hind legs. 102 00:09:45,567 --> 00:09:49,003 A worker can carry a lump weighing half as much as she does herself. 103 00:09:51,207 --> 00:09:55,405 Each bundle is carefully unloaded into one of the storage cells. 104 00:10:10,127 --> 00:10:12,482 The pollen isn't eaten by workers. 105 00:10:12,847 --> 00:10:15,600 They unselfishly bring it back for the larvae, 106 00:10:15,727 --> 00:10:19,322 for it's rich in protein and essential food for their development. 107 00:10:27,007 --> 00:10:31,398 By the late summer, there may be more than 200 workers in the nest. 108 00:10:32,207 --> 00:10:35,563 Although the colony is now close to its maximum size, 109 00:10:35,647 --> 00:10:37,717 the queen is still laying. 110 00:10:38,287 --> 00:10:40,642 But these batches of eggs are different. 111 00:10:40,727 --> 00:10:43,366 She's now stopped producing the chemical substance 112 00:10:43,447 --> 00:10:46,405 that repressed the sexual development of her daughters, 113 00:10:46,487 --> 00:10:49,559 so these eggs will develop into new queens. 114 00:10:51,687 --> 00:10:57,000 The change affects not just her eggs but her existing daughters, the workers. 115 00:10:57,687 --> 00:11:00,679 No longer restrained by the queers chemical control, 116 00:11:00,767 --> 00:11:03,327 some workers have started laying their own eggs. 117 00:11:04,007 --> 00:11:07,044 This doesn't suit the queen and she destroys them. 118 00:11:13,727 --> 00:11:15,524 The workers haven't mated, 119 00:11:15,607 --> 00:11:19,236 but their eggs can develop nonetheless, and become males. 120 00:11:19,567 --> 00:11:22,286 The queen eats as many of these eggs as she can find 121 00:11:22,367 --> 00:11:26,155 because as well as queen eggs, she's also producing male eggs 122 00:11:26,247 --> 00:11:28,761 and can't tolerate the competition. 123 00:11:32,127 --> 00:11:34,118 She keeps such a close watch 124 00:11:34,207 --> 00:11:38,120 that she manages to destroy the workers' eggs almost as soon as they're laid. 125 00:11:40,527 --> 00:11:42,518 The end of summer approaches. 126 00:11:45,687 --> 00:11:49,999 There's now anarchy in the colony. The social order has collapsed. 127 00:11:50,087 --> 00:11:53,284 Many of the workers whose eggs are being destroyed by the queen 128 00:11:53,367 --> 00:11:55,198 start to attack her. 129 00:11:56,607 --> 00:11:59,963 The onslaught is brutal. No quarter is given. 130 00:12:22,367 --> 00:12:25,439 Eventually, they sting her to death. 131 00:12:27,327 --> 00:12:29,602 The end of the colony has come. 132 00:12:31,487 --> 00:12:34,081 None of the workers will survive the winter... 133 00:12:35,207 --> 00:12:39,120 but the young queens will have left the nest and found males. 134 00:12:39,727 --> 00:12:43,356 It's they who will establish new colonies next spring. 135 00:12:46,407 --> 00:12:48,875 Bumblebees have a particular problem. 136 00:12:49,327 --> 00:12:50,726 In any given area, 137 00:12:50,807 --> 00:12:54,925 there's only a limited number of holes that are suitable for nests. 138 00:12:55,007 --> 00:12:59,125 European honeybees, which in the wild, nest in holes in trees, 139 00:12:59,207 --> 00:13:01,198 have similar difficulty. 140 00:13:01,287 --> 00:13:04,802 But some bees have adopted a very radical solution. 141 00:13:05,167 --> 00:13:07,806 A very brave solution to that difficulty. 142 00:13:07,887 --> 00:13:12,438 They nest out in the open but at the top of tall trees. 143 00:13:12,887 --> 00:13:15,447 Sometimes very tall trees. 144 00:13:20,887 --> 00:13:25,563 These are the giant Asiatic bees, the biggest of all honeybees. 145 00:13:25,767 --> 00:13:29,965 They are found from the Himalayas all the way down to Southeast Asia. 146 00:13:30,367 --> 00:13:32,483 These colonies are in Malaysia. 147 00:13:34,087 --> 00:13:39,445 They defend themselves with stings. Very, very powerful stings, 148 00:13:39,527 --> 00:13:42,439 which is why I have to wear a bee suit. 149 00:13:43,807 --> 00:13:48,517 And it's not just against one bee that you have to guard yourself. 150 00:13:49,287 --> 00:13:53,200 Because if one bee attacks you, it releases a pheromone, 151 00:13:53,287 --> 00:13:58,077 a chemical signal, which is detected by the others in the comb, 152 00:13:58,167 --> 00:14:00,806 and within seconds there will be hundreds, 153 00:14:00,887 --> 00:14:03,879 indeed probably thousands, of them all around you 154 00:14:03,967 --> 00:14:07,084 launching a mass attack and stinging you. 155 00:14:07,727 --> 00:14:11,436 And some of those stings can actually go through a bee suit. 156 00:14:11,527 --> 00:14:14,325 So, something to be avoided. 157 00:14:43,007 --> 00:14:45,965 Stinging is a very expensive form of defence 158 00:14:46,047 --> 00:14:49,562 because when a bee loses its sting, it dies. 159 00:14:50,007 --> 00:14:55,240 So it's better for the colony to warn predators off before they have to fight them off. 160 00:14:55,847 --> 00:14:59,283 And they warn them with some dramatic displays. 161 00:15:00,287 --> 00:15:05,281 I've got a reproduction of a hornet, which is one of the main enemies of bees. 162 00:15:05,367 --> 00:15:07,119 I'll see if I can get them to do it. 163 00:15:07,807 --> 00:15:09,559 Just watch. There. 164 00:15:11,047 --> 00:15:15,120 See, there's a moving wave which passes over the surface of the colony. 165 00:15:15,887 --> 00:15:19,277 And that not only produces an impressive pattern, 166 00:15:19,367 --> 00:15:23,155 but it also makes it very difficult for any aggressor, 167 00:15:23,247 --> 00:15:26,205 like perhaps a hornet which eats bees, 168 00:15:26,287 --> 00:15:30,644 to actually land on that moving carpet of wings. 169 00:15:34,807 --> 00:15:39,437 The colony's great treasure, of course, is its huge store of honey. 170 00:15:43,567 --> 00:15:48,766 This is produced from nectar which the bees industriously collect from flowers. 171 00:15:49,127 --> 00:15:54,440 They systematically expose it to the air so that the water it contains evaporates 172 00:15:54,607 --> 00:15:57,280 and the nectar becomes sweeter and thicker. 173 00:15:57,687 --> 00:16:00,076 Eventually it turns into honey. 174 00:16:09,207 --> 00:16:13,519 The combs in which they store it are continuously guarded by the covering of bees. 175 00:16:13,607 --> 00:16:17,646 They cling so thickly that it might seem that nothing could get past them. 176 00:16:18,207 --> 00:16:22,359 But some thieves know how to do so, particularly at night. 177 00:16:28,887 --> 00:16:32,960 A death's-head hawk moth flies over the surface of the colony 178 00:16:33,047 --> 00:16:34,719 and goes so close to it 179 00:16:34,807 --> 00:16:38,038 that the bees are alarmed enough to wave their warning. 180 00:16:44,207 --> 00:16:47,324 But the moth is not put off. It wants honey. 181 00:16:55,407 --> 00:16:58,843 Amazingly, it manages to land on the carpet of bees 182 00:16:58,967 --> 00:17:01,162 and quickly pushes its way through them. 183 00:17:04,727 --> 00:17:07,605 A quick sip of honey and it's off. 184 00:17:08,767 --> 00:17:13,557 It succeeds because, although it looks nothing like a bee to our eyes, 185 00:17:13,647 --> 00:17:16,081 it has camouflaged itself with a smell, 186 00:17:16,167 --> 00:17:19,523 a pheromone that convinces the bees that it's one of them. 187 00:17:20,647 --> 00:17:22,478 But in spite of such raids, 188 00:17:22,567 --> 00:17:26,196 bees, thanks to their stings, retain their precious honey. 189 00:17:26,287 --> 00:17:31,236 Precious because it is that that enables them to survive a season without flowers. 190 00:17:34,647 --> 00:17:39,767 While some descendants of the wasps became flower-foraging bees, 191 00:17:39,847 --> 00:17:44,523 others remained hunters but went down to the ground to search for their prey. 192 00:17:44,607 --> 00:17:47,724 There, wings were more of a hindrance than a help 193 00:17:47,927 --> 00:17:51,602 and these insects lost their wings for most of their lives. 194 00:17:51,767 --> 00:17:53,439 They're the ants. 195 00:17:54,967 --> 00:17:57,003 These are wood ants 196 00:17:57,087 --> 00:18:00,602 and they build nests even bigger than those of the giant bees. 197 00:18:00,687 --> 00:18:03,485 This one is in the pine forests of the Alps. 198 00:18:08,167 --> 00:18:13,560 Hunting parties go out from the nest along well-established trails to search for prey. 199 00:18:17,807 --> 00:18:20,765 Anything their own size is quickly overpowered. 200 00:18:24,527 --> 00:18:26,006 But by working together, 201 00:18:26,087 --> 00:18:29,523 wood ants can tackle prey much bigger than themselves. 202 00:18:30,847 --> 00:18:36,160 Some caterpillars are covered with stinging hairs but the ants cut these off one by one. 203 00:18:37,127 --> 00:18:40,642 And they can slice right through a beetle's hard armour. 204 00:18:55,087 --> 00:18:58,318 Now they are attacking another hunter, a spider. 205 00:18:58,847 --> 00:19:01,566 Everything they catch is taken back to the colony 206 00:19:01,647 --> 00:19:05,481 to be shared by those workers that stayed at home, looking after the young. 207 00:19:17,807 --> 00:19:21,004 The disadvantage of building a huge nest like this 208 00:19:21,087 --> 00:19:23,237 is that you're very obvious to predators. 209 00:19:23,567 --> 00:19:28,436 But these ants have a very effective way of defending themselves. Watch. 210 00:19:40,847 --> 00:19:42,405 Hm! 211 00:19:42,487 --> 00:19:46,878 The unmistakable acrid smell of formic acid. 212 00:19:49,127 --> 00:19:52,483 Most ants, like their wasp ancestors, have stings. 213 00:19:52,567 --> 00:19:54,205 But not these wood ants. 214 00:19:54,287 --> 00:19:59,156 Instead of injecting poison, they squirt it, and very accurately, too. 215 00:20:08,527 --> 00:20:10,518 They don't eat just meat. 216 00:20:11,007 --> 00:20:14,283 They also visit aphids that sit in the branches above, 217 00:20:14,367 --> 00:20:16,278 drinking the pine tree's sap. 218 00:20:16,847 --> 00:20:22,524 This contains more sugar than the aphids need, so the ants drink the excess. 219 00:20:23,687 --> 00:20:27,316 And they collect it just as fast as the aphids excrete it. 220 00:20:30,567 --> 00:20:32,364 They carry it back to the nest 221 00:20:32,447 --> 00:20:35,803 but in this case they transport it inside their swollen stomachs. 222 00:20:35,967 --> 00:20:40,836 In fact, this liquid, honeydew, makes up more than two thirds of the colony's diet. 223 00:20:45,647 --> 00:20:50,038 All these wood ant nests are connected to one another by trails. 224 00:20:50,647 --> 00:20:54,322 And, indeed, they're also genetically related to one another. 225 00:20:54,567 --> 00:20:58,037 There are some 1,200 of them in this one patch of forest 226 00:20:58,647 --> 00:21:01,207 and that makes this what is thought to be 227 00:21:01,287 --> 00:21:04,996 the biggest supercolony of ants in the whole world. 228 00:21:07,407 --> 00:21:10,843 By mid June, the supercolony is ready to reproduce. 229 00:21:11,567 --> 00:21:15,162 Out of every nest, among the workers, come individuals with wings. 230 00:21:16,807 --> 00:21:19,685 Some nests produce only males. 231 00:21:20,287 --> 00:21:22,517 They take off in droves. 232 00:21:30,967 --> 00:21:33,959 Other nests produce only females. 233 00:21:35,967 --> 00:21:40,165 Both sexes, now that they are winged, look remarkably like wasps. 234 00:21:40,407 --> 00:21:42,398 A reminder of their ancestry. 235 00:21:47,167 --> 00:21:48,964 Unlike wasps, however, 236 00:21:49,047 --> 00:21:53,802 these flyers are not very confident about getting into the air. 237 00:22:12,407 --> 00:22:16,002 Males and females assemble in the nearby meadows. 238 00:22:16,287 --> 00:22:18,755 The queens lay down chemical trails 239 00:22:18,847 --> 00:22:22,635 so that the males may quickly discover exactly where they are. 240 00:22:22,727 --> 00:22:25,195 And the males are quick to take the hint. 241 00:22:38,647 --> 00:22:40,763 The males only live for a few days 242 00:22:40,847 --> 00:22:43,884 and they mate as quickly and as frequently as they can. 243 00:22:50,727 --> 00:22:54,197 A queen, on the other hand, may live for as long as 10 years 244 00:22:54,287 --> 00:22:59,441 and a single mating will provide her with enough sperm to last for her entire life. 245 00:23:00,887 --> 00:23:03,845 For a female, mating is often a bit of a battle. 246 00:23:04,487 --> 00:23:07,843 Sometimes she has to bite a male to make him release her. 247 00:23:07,927 --> 00:23:12,717 Sometimes she has to hang on to him because he's impatient and wants to move on. 248 00:23:18,567 --> 00:23:21,559 The newly-mated queens gather together in the undergrowth. 249 00:23:22,047 --> 00:23:24,197 Here, they shed their wings. 250 00:23:24,807 --> 00:23:28,402 They've found their males so their travelling is over. 251 00:23:34,887 --> 00:23:39,358 Now, each must find an existing nest in which to lay her eggs. 252 00:23:43,687 --> 00:23:46,360 This one encounters a column of workers. 253 00:23:46,767 --> 00:23:50,316 A wood ant nest may contain as many as 1,000 queens. 254 00:23:50,407 --> 00:23:53,205 But will these workers allow her to be one of them? 255 00:23:53,287 --> 00:23:55,926 If they don't, they will bite her to death. 256 00:23:58,927 --> 00:24:00,360 She's been accepted. 257 00:24:00,447 --> 00:24:03,598 The workers have detected chemical clues on her body 258 00:24:03,687 --> 00:24:07,566 that tells them that she is originally from one of the nests in their supercolony. 259 00:24:08,207 --> 00:24:11,836 She's large and fat. Walking is not easy for her. 260 00:24:12,167 --> 00:24:15,842 A single worker carries her along the trail back home. 261 00:24:16,287 --> 00:24:20,246 Perhaps even to the same nest in which she started life. 262 00:24:22,967 --> 00:24:24,923 Ants live almost everywhere. 263 00:24:26,687 --> 00:24:29,520 The water falling in this mangrove swamp in Australia 264 00:24:29,607 --> 00:24:32,997 exposes in the wet mud an ant's nest. 265 00:24:34,927 --> 00:24:36,918 Every time the tide recedes, 266 00:24:37,007 --> 00:24:40,920 the ants must repair any damage the water may have caused. 267 00:24:43,327 --> 00:24:47,798 Collapsed entrances must be reopened and blocked tunnels cleared. 268 00:24:58,287 --> 00:25:00,562 Now that the mud flats are exposed, 269 00:25:00,647 --> 00:25:04,037 the ants hurry to collect what food the tide might have delivered. 270 00:25:07,007 --> 00:25:10,124 But there are still some stretches of water to be crossed. 271 00:25:18,087 --> 00:25:22,763 The surface tension of the water supports them as they dance across it. 272 00:25:24,967 --> 00:25:27,322 Sometimes they actually swim. 273 00:25:44,647 --> 00:25:48,322 And there has indeed been a new delivery of food. 274 00:25:55,647 --> 00:25:58,207 But the tide has also created a problem. 275 00:25:58,287 --> 00:26:02,405 It has washed away the chemical trails that mark the frontiers of their territory, 276 00:26:02,527 --> 00:26:05,485 so there's now no clear boundary between them 277 00:26:05,567 --> 00:26:07,922 and ants belonging to a neighbouring colony. 278 00:26:10,447 --> 00:26:14,520 The interrogation of a stranger is complex and detailed. 279 00:26:15,807 --> 00:26:17,877 Who are you? Where do you come from? 280 00:26:21,047 --> 00:26:23,800 Answers are readily given and accepted. 281 00:26:34,487 --> 00:26:38,480 But every now and then, they have to fight to settle the question. 282 00:26:48,687 --> 00:26:53,556 They may have sorted out their disagreement but now there is a bigger threat to both of them. 283 00:26:54,327 --> 00:26:56,124 The tide is turning again. 284 00:26:56,207 --> 00:26:59,005 They must get back to the safety of their nests. 285 00:27:10,207 --> 00:27:11,765 While the tide has been out, 286 00:27:11,847 --> 00:27:14,315 larvae and pupae have been moved around the nest 287 00:27:14,407 --> 00:27:17,604 to keep them at the temperature needed for their proper development. 288 00:27:17,687 --> 00:27:22,044 Now, they must be moved again for the nest is not watertight. 289 00:27:22,127 --> 00:27:25,119 Many of the tunnels and chambers are flooded with every tide. 290 00:27:25,207 --> 00:27:27,437 There's no time to waste. 291 00:27:43,807 --> 00:27:47,117 But the water doesn't reach every part of the nest, 292 00:27:47,207 --> 00:27:50,199 for the ants have constructed bell-shaped chambers 293 00:27:50,287 --> 00:27:53,723 that trap pockets of air and so create refuges 294 00:27:53,807 --> 00:27:57,197 where the adults and the young can sit out the high tide. 295 00:28:13,967 --> 00:28:16,720 Here in Arizona, the problem for an ant 296 00:28:16,807 --> 00:28:19,719 is not too much water, but too little. 297 00:28:19,807 --> 00:28:21,604 The rainfall is so low 298 00:28:21,687 --> 00:28:24,918 that there's hardly any vegetation and very little to eat, 299 00:28:25,007 --> 00:28:29,080 so an ant has to be prepared to eat whatever it can find. 300 00:28:29,167 --> 00:28:32,637 There are seeds, but seeds are very tough 301 00:28:32,727 --> 00:28:35,480 and you need very powerful jaws to crack them. 302 00:28:35,767 --> 00:28:40,158 But then, that's exactly what these harvester ants have got. 303 00:28:46,127 --> 00:28:49,005 They make an intensive search of the sand. 304 00:28:49,087 --> 00:28:51,681 Almost any seed will be collected. 305 00:28:51,807 --> 00:28:55,561 Food around here is very scarce. They can't afford to be fussy. 306 00:29:08,047 --> 00:29:12,120 They carry their gleanings back to the nest to store it in larders, 307 00:29:12,207 --> 00:29:15,005 many of which are several metres below ground. 308 00:29:18,407 --> 00:29:21,683 But, like the mangrove ants, they must work fast. 309 00:29:22,327 --> 00:29:26,240 The desert warms quickly and before long the heat will be intolerable. 310 00:29:29,807 --> 00:29:33,686 By nightfall, the harvesters are back inside the nest. 311 00:29:33,927 --> 00:29:37,158 But there's still a lot going on out in the desert. 312 00:29:37,927 --> 00:29:40,725 There's another ant here, too. The night ant. 313 00:29:40,807 --> 00:29:43,719 This is one of their nests in front of me. 314 00:29:43,807 --> 00:29:47,436 They normally only come out after dark and they're generalists. 315 00:29:47,527 --> 00:29:49,518 They'll eat pretty well anything. 316 00:29:49,607 --> 00:29:52,440 But they have a particular taste for seeds. 317 00:29:53,207 --> 00:29:55,516 The trouble is that the harvester ants 318 00:29:55,607 --> 00:29:58,326 will have gathered all the seeds during the day 319 00:29:58,407 --> 00:30:01,444 unless the night ants can do something about it. 320 00:30:03,727 --> 00:30:05,240 Just after dark, 321 00:30:05,327 --> 00:30:10,276 the night ants start a major spoiling operation against their rivals. 322 00:30:13,207 --> 00:30:16,916 They start to shift stones and fragments of plants 323 00:30:17,007 --> 00:30:19,999 to block up some holes near their nest. 324 00:30:33,887 --> 00:30:36,799 By morning, it's clear what they've done. 325 00:30:36,887 --> 00:30:40,800 They've trapped the harvesters inside their own nests. 326 00:30:48,807 --> 00:30:51,162 The harvesters now have a lot of work to do 327 00:30:51,247 --> 00:30:53,966 before they can get out to collect more seeds. 328 00:30:54,047 --> 00:30:56,720 They clear away the rubble as quickly as they can. 329 00:31:08,047 --> 00:31:09,719 But this takes time. 330 00:31:09,807 --> 00:31:12,560 If they are seriously delayed, the day will be too hot 331 00:31:12,647 --> 00:31:14,842 for them to spend time out in the open. 332 00:31:14,927 --> 00:31:18,397 So today, they can't collect as much as they normally do. 333 00:31:22,807 --> 00:31:24,923 And that means that by nightfall, 334 00:31:25,007 --> 00:31:28,920 there will still be seeds on the ground for the night ants to collect. 335 00:31:35,767 --> 00:31:38,884 Not all ants live in permanent nests. 336 00:31:38,967 --> 00:31:41,800 In the tropical forests of Africa and South America, 337 00:31:41,887 --> 00:31:44,196 there are some that are nomads. 338 00:31:45,447 --> 00:31:48,564 These army ants in the rain forests of Central America 339 00:31:48,647 --> 00:31:50,683 are camped in the base of a tree. 340 00:31:50,767 --> 00:31:52,962 They've been there for three weeks. 341 00:31:53,047 --> 00:31:57,325 During this time the queen has been laying eggs, several thousand a day. 342 00:31:57,407 --> 00:32:01,320 The army has also been ransacking the surrounding forest for prey. 343 00:32:01,607 --> 00:32:04,997 But now it's time for them to find new hunting grounds. 344 00:32:05,087 --> 00:32:07,760 So once more, they start to march. 345 00:32:20,207 --> 00:32:22,357 The site for the new bivouac 346 00:32:22,447 --> 00:32:25,723 has not been picked by the queen, but by the workers. 347 00:32:26,087 --> 00:32:30,842 Scouts have been exploring the neighbourhood and they've decided on a new place. 348 00:32:31,287 --> 00:32:35,075 And now their chemical trails are leading the whole colony 349 00:32:35,167 --> 00:32:37,681 from the old bivouac to the new one. 350 00:32:40,727 --> 00:32:45,482 As in an army, the soldiers are prepared to risk their lives for the common good. 351 00:32:45,807 --> 00:32:49,163 A group of them interlock their bodies to form a safety barrier 352 00:32:49,247 --> 00:32:53,559 that will catch any of their companions that might slip off this sloping trunk. 353 00:32:54,767 --> 00:32:56,439 They take everything with them. 354 00:32:56,527 --> 00:33:01,237 Larvae, food, and in this case and very rarely seen, winged males. 355 00:33:15,727 --> 00:33:20,437 By the time daylight comes, the army has established a new bivouac. 356 00:33:20,647 --> 00:33:22,399 Its walls and tunnels 357 00:33:22,487 --> 00:33:27,003 are formed by the interlinked bodies of hundreds and thousands of individuals. 358 00:33:34,727 --> 00:33:37,195 But this is only a temporary camp. 359 00:33:37,287 --> 00:33:40,199 They still haven't reached fresh hunting grounds. 360 00:33:40,287 --> 00:33:44,121 Even so, they must eat and the workers set off to find food. 361 00:34:14,047 --> 00:34:17,676 There are probably a million individual ants in this one colony 362 00:34:17,767 --> 00:34:20,645 and together, they are collaborating and cooperating 363 00:34:20,727 --> 00:34:24,083 so that the colony has become one great superorganism. 364 00:34:24,167 --> 00:34:27,443 There's no central controlling intelligence as such. 365 00:34:27,527 --> 00:34:32,362 Instead, the behaviour of the superorganism is the cumulative result 366 00:34:32,447 --> 00:34:36,804 of thousands upon thousands of tiny mini-decisions by individual ants. 367 00:34:36,887 --> 00:34:41,438 A worker moves forward into new territory leaving a chemical trail behind it 368 00:34:41,527 --> 00:34:45,679 and then another, following in its trail, advances still a little further. 369 00:34:45,767 --> 00:34:48,361 So, the superorganism as a whole 370 00:34:48,447 --> 00:34:51,962 is moving through the forest, searching for food. 371 00:34:57,847 --> 00:35:02,443 These hunters can subdue almost any other creature in the undergrowth. 372 00:35:02,607 --> 00:35:05,644 Some predators may be armed with virulent poisons 373 00:35:05,727 --> 00:35:08,366 but their attackers are too small to sting. 374 00:35:11,047 --> 00:35:13,766 A lizard has no defence at all. 375 00:35:33,807 --> 00:35:38,085 A special caste of workers with particularly large jaws 376 00:35:38,167 --> 00:35:41,716 protect the smaller workers as they sting their prey and butcher it. 377 00:35:54,327 --> 00:35:58,002 The venom in their stings liquefies the tissues of their victims 378 00:35:58,087 --> 00:36:02,160 so that the bodies are more easily cut up into smaller pieces for transport. 379 00:36:21,487 --> 00:36:25,002 The chemical trails laid down by the first scouts 380 00:36:25,087 --> 00:36:29,877 have now been strengthened and broadened by the passage of many, many more workers. 381 00:36:30,247 --> 00:36:32,522 And now those trails are serving as highways 382 00:36:32,607 --> 00:36:37,965 along which booty is being brought back to the bivouac to feed the young brood. 383 00:36:58,247 --> 00:37:02,126 Remarkably, almost as soon as these workers return with food, 384 00:37:02,207 --> 00:37:05,517 scouts begin to search for a new bivouac site. 385 00:37:07,247 --> 00:37:11,684 The colony will move again tonight, and every night for the next few weeks 386 00:37:11,807 --> 00:37:14,401 until the queen is ready to lay more eggs. 387 00:37:17,687 --> 00:37:21,441 When it comes to creating a permanent home for the colony, 388 00:37:21,527 --> 00:37:26,043 the champions by far are these tiny creatures. 389 00:37:26,127 --> 00:37:27,401 Termites. 390 00:37:28,607 --> 00:37:31,405 Unlike ants, all termites are vegetarians. 391 00:37:31,487 --> 00:37:35,605 They are in fact descended not from wasps, but from cockroaches. 392 00:37:35,807 --> 00:37:39,322 And their huge nests act not only as their fortresses 393 00:37:39,407 --> 00:37:41,125 but their food stores. 394 00:37:42,447 --> 00:37:45,678 They build with nothing but mud and their own excrement 395 00:37:45,767 --> 00:37:47,837 yet their nests are gigantic. 396 00:37:47,927 --> 00:37:49,758 If termites were our size, 397 00:37:49,847 --> 00:37:54,125 some of their homes would be four times as tall as New York's skyscrapers 398 00:37:54,207 --> 00:37:57,404 and measure up to five miles across at their base. 399 00:37:57,487 --> 00:37:59,205 These are not quite so tall 400 00:37:59,287 --> 00:38:02,199 but they are particularly remarkable for another reason. 401 00:38:05,127 --> 00:38:09,245 Every one of these termite hills points in the same direction, 402 00:38:09,327 --> 00:38:11,238 north and south. 403 00:38:11,327 --> 00:38:14,922 It's as though they were needles in a compass. 404 00:38:15,007 --> 00:38:18,761 And, indeed, they're called magnetic termites. 405 00:38:18,847 --> 00:38:22,362 They in fact take their cue for building 406 00:38:22,447 --> 00:38:24,881 from the magnetism of the earth. 407 00:38:24,967 --> 00:38:28,960 But the benefit of doing so comes not from that, 408 00:38:29,047 --> 00:38:31,800 but from the daily movement of the sun. 409 00:38:43,447 --> 00:38:46,519 In the morning, the rays of the rising sun 410 00:38:46,607 --> 00:38:50,361 strike the eastern face of the mound foursquare. 411 00:38:50,447 --> 00:38:54,440 And the termites, after the cold of the night, need warming up 412 00:38:54,527 --> 00:38:57,758 and are gathered in galleries immediately below the surface. 413 00:38:58,287 --> 00:39:02,644 But as the day continues, it warms up, but the termites don't overheat 414 00:39:02,727 --> 00:39:06,686 because the rays of the sun only strike the surface glancingly. 415 00:39:06,767 --> 00:39:08,246 And by midday, 416 00:39:08,327 --> 00:39:12,161 the full force of the sun is felt only on the top edge. 417 00:39:21,847 --> 00:39:24,520 As the sun moves towards the west, 418 00:39:24,607 --> 00:39:27,917 so this face becomes roastingly hot. 419 00:39:28,447 --> 00:39:31,803 But the eastern face falls into shadow 420 00:39:31,887 --> 00:39:34,082 and remains relatively cool 421 00:39:34,167 --> 00:39:37,762 and the termites stay at the temperature that suits them best. 422 00:39:39,167 --> 00:39:41,442 Other termites escape the heat of the day 423 00:39:41,527 --> 00:39:44,963 by retreating to deep cellars below their mounds. 424 00:39:45,047 --> 00:39:50,167 But these magnetic termites colonise areas that flood during the rainy season 425 00:39:50,247 --> 00:39:53,398 and the ground beneath them is regularly waterlogged. 426 00:39:53,847 --> 00:39:55,758 So their compass-like mounds 427 00:39:55,847 --> 00:39:59,203 are a response not just to the movement of the sun, 428 00:39:59,287 --> 00:40:01,437 but to badly drained sites. 429 00:40:02,727 --> 00:40:06,276 Here in South Africa, it can also get very hot 430 00:40:06,367 --> 00:40:08,358 but there's no danger of flooding 431 00:40:08,447 --> 00:40:12,440 so termites can take refuge from the heat below ground 432 00:40:12,527 --> 00:40:15,837 where it's cool and relatively stable. 433 00:40:16,327 --> 00:40:19,160 But two million insects living below ground 434 00:40:19,247 --> 00:40:21,761 create a different kind of problem. 435 00:40:21,847 --> 00:40:24,486 The air around them gets stale. 436 00:40:24,567 --> 00:40:29,402 So termites need to have a way of linking the underground air 437 00:40:29,487 --> 00:40:32,320 with the fresh air above, a ventilation system. 438 00:40:32,607 --> 00:40:35,405 And they do that with this. 439 00:40:36,127 --> 00:40:40,518 And to see how it works, you've got to look inside. 440 00:40:43,287 --> 00:40:45,596 Using the latest scanning techniques, 441 00:40:45,687 --> 00:40:48,884 we can create a picture of the mound's interior. 442 00:40:49,647 --> 00:40:54,038 An intricate network of passages lead to a central chimney. 443 00:40:55,807 --> 00:40:59,277 Hot, stale air from the insect population below 444 00:40:59,367 --> 00:41:01,437 rises up through the chimney. 445 00:41:05,287 --> 00:41:08,563 But the top of the mound is sealed. 446 00:41:08,647 --> 00:41:11,286 So how does this stale air escape? 447 00:41:12,287 --> 00:41:16,439 The mound may look as though it has strong defensive walls like a fortress. 448 00:41:16,527 --> 00:41:19,041 But in fact these walls are porous. 449 00:41:19,127 --> 00:41:22,358 And their primary purpose is to harness the wind. 450 00:41:23,527 --> 00:41:26,041 Fresh air blowing against the side of the mound 451 00:41:26,127 --> 00:41:28,960 is forced through the tiny holes in these walls. 452 00:41:29,047 --> 00:41:32,164 From there, it travels through the smaller tunnels 453 00:41:32,247 --> 00:41:34,477 until it reaches the central chimney. 454 00:41:35,967 --> 00:41:40,438 Here, the cooler, fresh air mixes with the hot, stale air 455 00:41:40,527 --> 00:41:43,200 rising from the insect community below. 456 00:41:44,127 --> 00:41:48,200 Meanwhile, some air is blown around the side of the mound. 457 00:41:48,287 --> 00:41:53,042 This creates a suction that pulls the stale air out of the chimney 458 00:41:53,127 --> 00:41:55,038 and out through the outer walls. 459 00:41:55,167 --> 00:42:00,002 So an internal air current is created and the whole mound ventilated. 460 00:42:01,847 --> 00:42:06,557 The mound's inhabitants spend most of their time close to or below ground level. 461 00:42:08,487 --> 00:42:11,797 Beneath their living quarters, there are garden chambers 462 00:42:11,887 --> 00:42:17,120 where the termites cultivate a fungus that rots the wood and vegetation they collect 463 00:42:17,207 --> 00:42:19,118 and make it digestible. 464 00:42:20,327 --> 00:42:24,525 Farther down still, the queen lies in her own chamber. 465 00:42:26,767 --> 00:42:30,919 Her huge body is a gigantic egg-producing factory. 466 00:42:31,007 --> 00:42:34,841 She's so swollen that she can't look after herself. 467 00:42:34,927 --> 00:42:37,236 The workers must constantly clean her 468 00:42:37,327 --> 00:42:39,966 and feed her with food from their own crops. 469 00:42:41,327 --> 00:42:45,479 Her partner, with whom she founded the colony maybe 20 years ago, 470 00:42:45,567 --> 00:42:49,276 is still with her and mates with her throughout her life. 471 00:42:51,687 --> 00:42:54,679 She lays eggs at an extraordinary rate, 472 00:42:54,767 --> 00:42:57,406 as many as 30,000 a day. 473 00:42:59,127 --> 00:43:03,200 As she produces them, so workers remove them from the royal chamber 474 00:43:03,287 --> 00:43:05,323 and take them to nurseries. 475 00:43:05,407 --> 00:43:10,356 There they'll be fed on compost from the fungus gardens until they turn into adults. 476 00:43:16,527 --> 00:43:20,122 The superorganism that lives in this great castle 477 00:43:20,207 --> 00:43:25,725 crops the surrounding vegetation just about as severely as an antelope. 478 00:43:26,407 --> 00:43:30,525 The density of individual termites around here is extraordinary. 479 00:43:30,607 --> 00:43:33,758 Over 100,000 per square metre. 480 00:43:34,087 --> 00:43:38,956 And just as there are lions and leopard that hunt antelope, 481 00:43:39,047 --> 00:43:42,926 so in the undergrowth, there are insect hunters 482 00:43:43,007 --> 00:43:45,885 which prey on the tiny herbivores. 483 00:43:45,967 --> 00:43:49,118 The ants, the termites' ancient enemy. 484 00:43:51,007 --> 00:43:55,398 Matabele ants, specialist termite hunters. 485 00:44:01,247 --> 00:44:05,479 A scout has laid down a clear chemical trail 486 00:44:05,567 --> 00:44:10,402 and this battalion of workers have picked it up and are following it. 487 00:44:10,487 --> 00:44:12,796 There may be only a few hundred of them 488 00:44:12,887 --> 00:44:17,597 but they are going to severely test the defences of a termite colony. 489 00:44:25,007 --> 00:44:28,886 The mound has formidable guards, soldier termites. 490 00:44:41,047 --> 00:44:44,244 The ants have a special technique for dealing with these soldiers. 491 00:44:44,327 --> 00:44:46,158 They grab the termite's jaw 492 00:44:46,247 --> 00:44:49,796 and then sting it in the only vulnerable place on its head, 493 00:44:49,887 --> 00:44:51,957 in its mouth. 494 00:44:59,327 --> 00:45:02,000 The ants' front line breaks into the colony. 495 00:45:02,087 --> 00:45:05,443 Reinforcements for the termite soldiers arrive quickly. 496 00:45:05,527 --> 00:45:08,405 Already there are casualties on both sides. 497 00:45:12,247 --> 00:45:15,603 But the invaders overwhelm the defenders. 498 00:45:21,207 --> 00:45:25,200 It's not to the ants' advantage to kill an entire termite colony 499 00:45:25,287 --> 00:45:29,166 any more than it would be sensible for farmers to exterminate their cattle. 500 00:45:29,247 --> 00:45:33,525 Better to let most survive so that they can be regularly raided. 501 00:45:33,607 --> 00:45:36,758 So, although there are millions of termites in the colony, 502 00:45:36,847 --> 00:45:41,159 the Matabele ants rarely go deep into the nest to press home their victory. 503 00:45:59,727 --> 00:46:02,764 The raid lasts less than 15 minutes. 504 00:46:02,847 --> 00:46:05,566 Nonetheless, the spoils are impressive. 505 00:46:15,767 --> 00:46:20,522 Termite bodies are now being piled in dumps outside the nest. 506 00:46:29,727 --> 00:46:34,676 Many of the casualties are still alive but paralysed by the ants' stings. 507 00:46:34,927 --> 00:46:37,680 Now the raiders have the considerable task 508 00:46:37,767 --> 00:46:41,362 of carrying their victims back to their nest. 509 00:46:43,847 --> 00:46:46,407 They will have to take all their booty with them. 510 00:46:46,527 --> 00:46:51,157 If any termite bodies are left behind, they will be collected by scavengers. 511 00:46:55,287 --> 00:46:58,006 The termite soldiers certainly fought hard. 512 00:46:58,087 --> 00:47:02,126 One of their dead still grips a Matabele soldier in its jaws, 513 00:47:02,207 --> 00:47:05,165 which it killed before it was itself slaughtered. 514 00:47:13,647 --> 00:47:16,480 Well, it's been a successful raid. 515 00:47:16,567 --> 00:47:20,401 Many of the bigger ones have got mouthfuls of termites. 516 00:47:20,487 --> 00:47:24,366 How they manage to hold all of them in one mouthful, I don't know. 517 00:47:24,447 --> 00:47:28,486 But, obviously, they've got a little way to go now 518 00:47:28,607 --> 00:47:33,123 and soon the young ones back at the nest will be getting good food. 519 00:47:35,927 --> 00:47:39,886 The Matabele ants will use their plunder to raise more workers. 520 00:47:39,967 --> 00:47:43,676 Ironically, the raid will have the same effect on the termites. 521 00:47:43,767 --> 00:47:46,918 The queen will detect the loss of her soldiers and workers 522 00:47:47,047 --> 00:47:50,960 and will increase her output of eggs to repopulate the colony. 523 00:47:51,047 --> 00:47:55,598 So there will be just as much food for the Matabeles the next time they raid. 524 00:48:01,247 --> 00:48:03,886 The tiny creatures of the undergrowth 525 00:48:03,967 --> 00:48:07,880 were the first animals of any kind to colonise the land. 526 00:48:08,927 --> 00:48:13,318 They established the foundations of the land's ecosystems. 527 00:48:13,887 --> 00:48:16,765 Ultimately they were able to transcend 528 00:48:16,847 --> 00:48:19,486 any limitations of their small size 529 00:48:19,567 --> 00:48:22,764 by banding together in huge communities of millions 530 00:48:22,847 --> 00:48:25,361 and putting up buildings like this one. 531 00:48:25,847 --> 00:48:30,921 If we and the rest of the backboned animals were to disappear overnight, 532 00:48:31,007 --> 00:48:33,760 the rest of the world would get on pretty well. 533 00:48:34,567 --> 00:48:37,081 But if they were to disappear, 534 00:48:37,167 --> 00:48:40,398 the land's ecosystems would collapse. 535 00:48:40,487 --> 00:48:42,921 The soil would lose its fertility. 536 00:48:43,007 --> 00:48:46,124 Many of the plants would no longer be pollinated. 537 00:48:46,247 --> 00:48:50,035 Lots of animals, amphibians, reptiles, birds, mammals 538 00:48:50,127 --> 00:48:51,958 would have nothing to eat. 539 00:48:52,047 --> 00:48:56,677 And our fields and pastures would be covered with dung and carrion. 540 00:48:58,047 --> 00:49:02,040 These small creatures are within a few inches of our feet 541 00:49:02,127 --> 00:49:04,436 wherever we go on land 542 00:49:04,527 --> 00:49:06,916 but often, they're disregarded. 543 00:49:07,607 --> 00:49:10,804 We would do very well to remember them.