1 00:00:02,000 --> 00:00:06,320 The natural world is full of extraordinary animals 2 00:00:06,320 --> 00:00:08,880 with amazing life histories. 3 00:00:08,880 --> 00:00:12,760 Yet certain stories are more intriguing than others. 4 00:00:14,680 --> 00:00:18,040 The mysteries of a butterfly's life cycle. 5 00:00:18,040 --> 00:00:20,840 Or the strange biology of the Emperor Penguin. 6 00:00:22,200 --> 00:00:25,000 Some of these creatures were surrounded by 7 00:00:25,000 --> 00:00:28,200 fantastic myths and misunderstandings. 8 00:00:29,520 --> 00:00:32,640 Others have only recently revealed their secrets. 9 00:00:34,160 --> 00:00:38,040 These are the creatures that stand out from the crowd, 10 00:00:38,040 --> 00:00:42,480 the curiosities that I find particularly fascinating. 11 00:00:49,080 --> 00:00:53,400 Pigeons are so common that we tend to take them for granted. 12 00:00:53,400 --> 00:00:56,360 But in fact, they are superb navigators 13 00:00:56,360 --> 00:01:00,040 and can find their way home from hundreds of miles away. 14 00:01:01,320 --> 00:01:05,680 And the dung beetle will roll a dung ball in a straight line 15 00:01:05,680 --> 00:01:08,720 even though it's head down and walking backwards. 16 00:01:09,880 --> 00:01:13,720 How on earth do these creatures manage to find their way? 17 00:01:21,640 --> 00:01:25,200 Pigeon fanciers know that if they take homing pigeons 18 00:01:25,200 --> 00:01:27,920 to somewhere where they've never been before, 19 00:01:27,920 --> 00:01:32,320 even if it's tens, even hundreds of miles away, and then release them, 20 00:01:32,320 --> 00:01:37,520 they will, after circling in the sky, head for home. 21 00:01:38,520 --> 00:01:41,360 These come from over there. 22 00:01:41,360 --> 00:01:43,120 Let's see what happens. 23 00:02:08,960 --> 00:02:12,840 Well, they certainly seem to be heading in the right direction. 24 00:02:12,840 --> 00:02:15,800 But how do pigeons find their way back home 25 00:02:15,800 --> 00:02:18,480 over totally unfamiliar territory? 26 00:02:18,480 --> 00:02:22,960 It seems the more mysterious to us because it's something we can't do 27 00:02:22,960 --> 00:02:26,080 unless we have all kinds of special equipment. 28 00:02:26,080 --> 00:02:29,800 But science is now beginning to find some of the answers. 29 00:02:31,440 --> 00:02:36,520 The homing pigeon is a domesticated descendant of the wild rock pigeon 30 00:02:36,520 --> 00:02:40,240 which lives on cliffs and ledges along our coasts. 31 00:02:40,240 --> 00:02:44,800 When humans started to domesticate them, they inevitably selected 32 00:02:44,800 --> 00:02:49,200 those birds that were particularly good at returning to their roosts. 33 00:02:52,960 --> 00:02:56,000 Pigeons are thought to be the very first birds 34 00:02:56,000 --> 00:03:00,800 to be domesticated by mankind, many thousands of years ago. 35 00:03:00,800 --> 00:03:04,560 Since then, they've been bred into many different varieties, 36 00:03:04,560 --> 00:03:06,440 including homing pigeons. 37 00:03:06,440 --> 00:03:09,960 And the varied appearance of this flock around me 38 00:03:09,960 --> 00:03:13,920 is evidence of that domesticated past. 39 00:03:13,920 --> 00:03:18,600 Since then, of course, they've come to live alongside us in our cities 40 00:03:18,600 --> 00:03:21,600 and giving many of us a lot of pleasure. 41 00:03:21,600 --> 00:03:22,960 Come on. 42 00:03:26,240 --> 00:03:29,240 It was not only their homing ability that made pigeons 43 00:03:29,240 --> 00:03:34,160 so popular with breeders, they are also superb flyers. 44 00:03:35,920 --> 00:03:40,080 Their powerful wing muscles make up nearly half their body weight 45 00:03:40,080 --> 00:03:43,360 and enable them to fly at speeds of 60mph. 46 00:03:44,760 --> 00:03:47,840 They're among the greatest long-distance athletes 47 00:03:47,840 --> 00:03:49,200 in the bird world. 48 00:03:54,600 --> 00:03:58,080 And pigeon fanciers have delighted in breeding them 49 00:03:58,080 --> 00:04:00,880 in order to race them competitively. 50 00:04:08,440 --> 00:04:13,960 Mankind has also used pigeons for a very practical purpose... 51 00:04:15,120 --> 00:04:16,560 ..as messengers. 52 00:04:19,520 --> 00:04:24,200 It was during the two World Wars that pigeons played a crucial role 53 00:04:24,200 --> 00:04:27,040 in carrying messages home from the front line. 54 00:04:28,080 --> 00:04:31,640 Nearly a quarter of a million birds served in the wars 55 00:04:31,640 --> 00:04:34,040 and helped save thousands of lives. 56 00:04:34,040 --> 00:04:37,920 One such bird was Cher Ami, 57 00:04:37,920 --> 00:04:41,640 a female donated by a British pigeon fancier 58 00:04:41,640 --> 00:04:45,760 for use by the United States Army during World War I. 59 00:04:47,160 --> 00:04:52,160 During one battle in France in 1918, more than 500 soldiers 60 00:04:52,160 --> 00:04:55,480 from the US infantry became trapped behind enemy lines. 61 00:04:57,160 --> 00:05:00,120 Worse, they were then fired upon by their own troops 62 00:05:00,120 --> 00:05:02,040 who didn't know they were there. 63 00:05:03,400 --> 00:05:07,480 Within 24 hours, more than half of them had been killed. 64 00:05:10,400 --> 00:05:13,840 With no other options, the commander, Major Whittlesey, 65 00:05:13,840 --> 00:05:17,400 desperately tried to send messages back by pigeon. 66 00:05:17,400 --> 00:05:21,120 The first two birds were shot down and only Cher Ami was left. 67 00:05:22,600 --> 00:05:26,480 For several moments, she flew with bullets zipping all around her, 68 00:05:26,480 --> 00:05:28,800 and eventually she was brought down. 69 00:05:28,800 --> 00:05:32,320 She'd been shot through the breast, blinded in one eye 70 00:05:32,320 --> 00:05:35,440 and her leg was left hanging by a tendon. 71 00:05:36,560 --> 00:05:40,240 Astonishingly, the injured bird managed to take flight again 72 00:05:40,240 --> 00:05:43,960 and arrived back at her loft at the division headquarters 73 00:05:43,960 --> 00:05:46,120 in just 25 minutes. 74 00:05:47,120 --> 00:05:52,640 Cher Ami's message helped save the lives of 194 soldiers. 75 00:05:53,840 --> 00:05:58,040 Her name in French, of course, means Dear Friend. 76 00:06:01,040 --> 00:06:04,160 When the Second World War broke out, 77 00:06:04,160 --> 00:06:06,520 Britain's pigeon fanciers once again 78 00:06:06,520 --> 00:06:09,440 gave their pigeons to the war effort 79 00:06:09,440 --> 00:06:13,040 to provide what was called the National Pigeon Service. 80 00:06:13,040 --> 00:06:18,560 This elite squad of birds was extremely valuable and successful. 81 00:06:18,560 --> 00:06:21,440 98% of their messages got through. 82 00:06:24,360 --> 00:06:28,040 The Germans, realising how important the pigeons had become, 83 00:06:28,040 --> 00:06:31,440 fought back with specially trained pigeon snipers. 84 00:06:37,560 --> 00:06:40,160 They also retaliated in another way, 85 00:06:40,160 --> 00:06:44,640 by using the pigeon's natural enemies - peregrine falcons. 86 00:06:50,040 --> 00:06:52,960 Pigeons played such a vital role in the war 87 00:06:52,960 --> 00:06:55,640 that many were celebrated as heroes. 88 00:06:55,640 --> 00:07:00,080 In 1943, this medal, the Dickin Medal, 89 00:07:00,080 --> 00:07:03,120 was founded to honour these animals. 90 00:07:03,120 --> 00:07:06,040 It was awarded to individuals that appeared, 91 00:07:06,040 --> 00:07:08,840 if you'll allow a little anthropomorphism, 92 00:07:08,840 --> 00:07:11,640 to have displayed particular bravery. 93 00:07:11,640 --> 00:07:16,880 And it's sometimes referred to as the Victoria Cross for animals. 94 00:07:16,880 --> 00:07:21,120 Of the 54 medals presented during World War II, 95 00:07:21,120 --> 00:07:23,600 32 were given to pigeons. 96 00:07:25,800 --> 00:07:28,000 We may have prized pigeons for centuries 97 00:07:28,000 --> 00:07:31,120 for their skills in finding their way through the skies, 98 00:07:31,120 --> 00:07:35,240 but for a long time we had no idea how the birds did it. 99 00:07:38,160 --> 00:07:40,720 Some suggested that pigeons used the sun. 100 00:07:40,720 --> 00:07:44,520 Others that they were guided by the Earth's magnetic field. 101 00:07:46,000 --> 00:07:49,840 But proving either was surprisingly difficult. 102 00:07:53,040 --> 00:07:55,840 A breakthrough came from an American scientist 103 00:07:55,840 --> 00:07:58,800 at Cornell University in the 1960s. 104 00:08:01,200 --> 00:08:04,960 William Keeton attached magnets to the backs of some pigeons, 105 00:08:04,960 --> 00:08:06,760 but not to others, 106 00:08:06,760 --> 00:08:08,880 and found that when the sun was out, 107 00:08:08,880 --> 00:08:12,360 both groups were able to make their way home. 108 00:08:13,880 --> 00:08:16,520 But when the sun was hidden behind clouds, 109 00:08:16,520 --> 00:08:18,960 the birds carrying magnets got lost. 110 00:08:20,360 --> 00:08:24,560 Keeton deduced that this was because the signals from their magnets 111 00:08:24,560 --> 00:08:27,800 swamped the much weaker ones coming from the Earth. 112 00:08:29,720 --> 00:08:33,760 So he established that pigeons can use either the sun 113 00:08:33,760 --> 00:08:37,160 or the Earth's magnetism to find their way around, 114 00:08:37,160 --> 00:08:38,920 according to conditions. 115 00:08:40,840 --> 00:08:45,000 But how do the birds detect the Earth's magnetism? 116 00:08:48,240 --> 00:08:51,360 This compass has a magnetised needle, 117 00:08:51,360 --> 00:08:54,720 which is sensitive to the Earth's magnetic field. 118 00:08:54,720 --> 00:08:56,840 It will always point north, 119 00:08:56,840 --> 00:08:59,920 allowing you to check the direction that you're travelling in. 120 00:08:59,920 --> 00:09:01,400 But what about pigeons? 121 00:09:01,400 --> 00:09:04,840 What could they be using to detect magnetic fields? 122 00:09:04,840 --> 00:09:08,000 Scientists were puzzled because they couldn't find 123 00:09:08,000 --> 00:09:11,800 any cells or organs in birds that were sensitive to magnetism. 124 00:09:14,920 --> 00:09:19,720 Then, in 2007, microscopic clusters of iron-rich cells 125 00:09:19,720 --> 00:09:23,360 were found in the beaks of homing pigeons, 126 00:09:23,360 --> 00:09:28,000 and it was thought that these might help them to detect magnetic forces. 127 00:09:29,560 --> 00:09:34,080 But only five years later, new research shattered that idea. 128 00:09:34,080 --> 00:09:37,840 It seems that the cells in fact are a defence against infection 129 00:09:37,840 --> 00:09:41,480 and have nothing whatsoever to do with magnetism. 130 00:09:41,480 --> 00:09:46,440 So the search for the pigeon's magnetic compass still continues. 131 00:09:46,440 --> 00:09:50,080 But we are now beginning to understand the other aspects 132 00:09:50,080 --> 00:09:52,120 of their navigational skills. 133 00:09:55,720 --> 00:09:59,760 A compass is just one of the tools we need for navigation. 134 00:09:59,760 --> 00:10:01,120 But it's not much help 135 00:10:01,120 --> 00:10:04,440 unless you know in which direction your destination lies. 136 00:10:04,440 --> 00:10:08,480 And to know that, you need a map of some kind. 137 00:10:10,160 --> 00:10:12,760 One way of creating a map in your mind 138 00:10:12,760 --> 00:10:15,880 is to memorise the prominent features of a landscape. 139 00:10:17,520 --> 00:10:22,160 Scientists at Oxford University are now using GPS technology 140 00:10:22,160 --> 00:10:24,520 to discover if pigeons do this. 141 00:10:27,560 --> 00:10:31,240 This bird has a GPS transmitting device strapped to its back 142 00:10:31,240 --> 00:10:33,720 in a specially designed backpack 143 00:10:33,720 --> 00:10:36,160 which causes it very little discomfort. 144 00:10:36,160 --> 00:10:41,320 And that will record the progress of the bird, second by second, 145 00:10:41,320 --> 00:10:43,200 once I let it go. 146 00:10:43,200 --> 00:10:48,280 It comes from a loft over there about six miles away in Oxford. 147 00:10:48,280 --> 00:10:51,560 Let's see whether or not she heads in that direction. 148 00:10:51,560 --> 00:10:53,360 Off you go. 149 00:10:56,280 --> 00:10:59,800 Birds, like this, that are released in a new place 150 00:10:59,800 --> 00:11:04,000 still ahead confidently in the direction of their home loft. 151 00:11:04,000 --> 00:11:05,560 How do they do it? 152 00:11:08,160 --> 00:11:09,720 Data from GPS trackers 153 00:11:09,720 --> 00:11:12,760 and cameras attached to the backs of pigeons 154 00:11:12,760 --> 00:11:15,320 have helped to answer that question. 155 00:11:16,720 --> 00:11:20,160 At first, a bird released in an unfamiliar place 156 00:11:20,160 --> 00:11:24,440 will use the sun or the Earth's magnetic field to get its bearings. 157 00:11:25,560 --> 00:11:28,080 But if you plot its movements on a map, 158 00:11:28,080 --> 00:11:32,640 you can see that at first it doesn't find the shortest route home. 159 00:11:34,040 --> 00:11:35,720 Then something changes. 160 00:11:37,160 --> 00:11:41,360 After repeated releases, the bird is able to use its experience 161 00:11:41,360 --> 00:11:43,680 to take a more direct way back. 162 00:11:48,160 --> 00:11:52,320 So it appears that pigeons learn to recognise features of the landscape 163 00:11:52,320 --> 00:11:56,520 such as hedgerows and trees, or even roads and buildings. 164 00:11:59,240 --> 00:12:03,800 They then memorise these to create a mental map of the area 165 00:12:03,800 --> 00:12:08,680 and by following familiar landmarks, they find their way back home. 166 00:12:11,800 --> 00:12:14,680 It seems that pigeons are creatures of habit. 167 00:12:14,680 --> 00:12:17,000 They like to stick to the routes they know well. 168 00:12:18,160 --> 00:12:22,800 Here are some tracks of a pigeon that lives in its home loft up here 169 00:12:22,800 --> 00:12:25,760 and was taken repeatedly to this point here. 170 00:12:26,760 --> 00:12:28,040 Watch what happens. 171 00:12:30,240 --> 00:12:33,560 It consistently makes a beeline for the major A road 172 00:12:33,560 --> 00:12:36,480 that conveniently runs past its home loft. 173 00:12:38,480 --> 00:12:41,440 And even when released some distance from this road, 174 00:12:41,440 --> 00:12:44,680 it will cut across to it and then follow it all the way home, 175 00:12:44,680 --> 00:12:46,440 as shown by the red lines. 176 00:12:53,360 --> 00:12:56,120 Some birds even fly around roundabouts 177 00:12:56,120 --> 00:12:59,120 before choosing the exit that will lead them back. 178 00:13:01,600 --> 00:13:04,960 So it seems that pigeons use methods of navigation 179 00:13:04,960 --> 00:13:08,080 more like ours than we might have imagined. 180 00:13:11,320 --> 00:13:13,040 We now know that pigeons have 181 00:13:13,040 --> 00:13:16,560 a whole range of navigational techniques at their disposal 182 00:13:16,560 --> 00:13:18,360 and can call on them as needed. 183 00:13:19,960 --> 00:13:22,600 It's a remarkably sophisticated system 184 00:13:22,600 --> 00:13:26,560 that enables them to find their way in nearly any situation. 185 00:13:31,280 --> 00:13:33,960 We've learned a lot about the pigeon's homing skills, 186 00:13:33,960 --> 00:13:36,160 but some mysteries still remain. 187 00:13:37,960 --> 00:13:42,480 In 1997, over 60,000 British birds were released 188 00:13:42,480 --> 00:13:44,800 during a pigeon race in southern France. 189 00:13:47,080 --> 00:13:50,560 Most of them didn't make it and were never seen again. 190 00:13:52,800 --> 00:13:58,000 In pigeon racing terms, the loss of so many birds was unheard of. 191 00:13:58,000 --> 00:13:59,520 A disaster. 192 00:13:59,520 --> 00:14:03,520 One bird might get lost, but tens of thousands? 193 00:14:07,280 --> 00:14:10,840 To get back to their lofts nearly 500 miles away, 194 00:14:10,840 --> 00:14:14,520 the pigeons had to cross the English Channel. 195 00:14:14,520 --> 00:14:17,400 It was not an unusually long or difficult journey 196 00:14:17,400 --> 00:14:21,120 for a racing pigeon, so why did the birds not make it? 197 00:14:22,120 --> 00:14:25,120 Well, there was a strange coincidence. 198 00:14:27,000 --> 00:14:30,840 At the very same time the racing pigeons were crossing the Channel, 199 00:14:30,840 --> 00:14:35,360 a Concorde supersonic airliner was flying along the Channel 200 00:14:35,360 --> 00:14:38,680 on its morning flight from Paris to New York. 201 00:14:41,000 --> 00:14:44,920 The Concorde generates a shock wave almost 100 miles wide. 202 00:14:46,080 --> 00:14:49,000 The pigeons flying below could not have escaped it. 203 00:14:49,000 --> 00:14:53,600 Could it be that this enormous wave of sound blotted out 204 00:14:53,600 --> 00:14:56,120 all other acoustic information? 205 00:14:58,480 --> 00:15:02,880 We know that pigeons can hear low-frequency infra-sounds 206 00:15:02,880 --> 00:15:05,440 such as those generated by ocean waves. 207 00:15:06,920 --> 00:15:12,120 And these might provide them with an acoustic map of their surroundings. 208 00:15:14,600 --> 00:15:17,760 The jury is still out as to whether pigeons really do use 209 00:15:17,760 --> 00:15:19,280 infra-sound to navigate 210 00:15:19,280 --> 00:15:23,200 and whether that explains the case of the disappearing pigeons. 211 00:15:24,360 --> 00:15:27,480 But it's an intriguing possibility. 212 00:15:30,960 --> 00:15:34,200 The familiar pigeon continues to surprise us. 213 00:15:34,200 --> 00:15:37,960 And even today, we're a long way off from understanding 214 00:15:37,960 --> 00:15:40,000 all its route-finding techniques. 215 00:15:42,840 --> 00:15:47,600 The small dung beetle has a brain no larger than a grain of rice. 216 00:15:47,600 --> 00:15:53,240 But, like the pigeon, it is capable of astonishing navigational feats. 217 00:15:57,200 --> 00:16:00,640 Moving large loads by walking head down and backwards 218 00:16:00,640 --> 00:16:03,280 must surely be one of the most bizarre ways 219 00:16:03,280 --> 00:16:04,960 of collecting your food. 220 00:16:07,240 --> 00:16:08,920 Dung beetles are well known 221 00:16:08,920 --> 00:16:11,600 for rolling their balls of dung in this way. 222 00:16:11,600 --> 00:16:13,720 But why do they do so? 223 00:16:13,720 --> 00:16:16,440 And how can they see where they are going? 224 00:16:19,240 --> 00:16:22,400 Ball rolling by dung beetles is probably 225 00:16:22,400 --> 00:16:26,280 one of the oldest recorded accounts of animal behaviour, 226 00:16:26,280 --> 00:16:29,000 dating back nearly 2,000 years. 227 00:16:29,000 --> 00:16:32,920 These insects were held sacred by the ancient Egyptians, 228 00:16:32,920 --> 00:16:37,000 and in the fifth century, an Egyptian scholar called Horapollo 229 00:16:37,000 --> 00:16:42,440 described the dung beetle as rolling its ball from east to west. 230 00:16:42,440 --> 00:16:45,760 It seems that he was suggesting that the beetles always 231 00:16:45,760 --> 00:16:48,760 moved their dung in a particular direction. 232 00:16:48,760 --> 00:16:50,760 But how true is that? 233 00:16:50,760 --> 00:16:55,200 In the following 2,000 years, little was done to examine the question. 234 00:16:57,360 --> 00:17:01,040 Dung beetles feed on what is, to the animals that produce it, 235 00:17:01,040 --> 00:17:04,280 a waste product - dung. 236 00:17:04,280 --> 00:17:08,320 But in fact, there's more than enough nourishment in one dropping 237 00:17:08,320 --> 00:17:10,880 to sustain a great number of beetles. 238 00:17:12,280 --> 00:17:16,520 They locate a newly dropped pile using their sense of smell. 239 00:17:17,600 --> 00:17:20,280 Their strong and powerful legs enable them 240 00:17:20,280 --> 00:17:21,840 to break up the dropping 241 00:17:21,840 --> 00:17:24,520 and their mouthparts are specially shaped 242 00:17:24,520 --> 00:17:27,920 to extract the nutrients and moisture that they need. 243 00:17:29,680 --> 00:17:33,400 They are, in fact, one of our planet's great recyclers. 244 00:17:38,680 --> 00:17:41,840 Dung beetles are found all over the world. 245 00:17:42,960 --> 00:17:47,520 There are over 6,000 species and they come in all shapes and colours. 246 00:17:49,200 --> 00:17:51,560 But they have one thing in common - 247 00:17:51,560 --> 00:17:54,480 they all feed on dung. 248 00:17:57,080 --> 00:17:59,840 Some of them, like this scarab beetle... 249 00:18:01,000 --> 00:18:04,360 ..have rows of projections on the head, 250 00:18:04,360 --> 00:18:07,600 which were likened by the ancient Egyptians 251 00:18:07,600 --> 00:18:10,400 to the rays of the rising sun. 252 00:18:10,400 --> 00:18:13,960 The broad front legs also carry spines. 253 00:18:13,960 --> 00:18:18,360 These are adaptations for digging and shaping dung balls, 254 00:18:18,360 --> 00:18:21,000 while the back legs are flattened 255 00:18:21,000 --> 00:18:24,400 and have tiny hairs for controlling the ball. 256 00:18:26,120 --> 00:18:30,000 But most dung beetles don't roll balls. 257 00:18:30,000 --> 00:18:32,400 They live either in the dung itself 258 00:18:32,400 --> 00:18:36,200 or tunnel directly into the soil beneath the dropping. 259 00:18:36,200 --> 00:18:39,960 Only 10% transport dung above ground. 260 00:18:39,960 --> 00:18:43,320 And they do so because competition near a pile of dung 261 00:18:43,320 --> 00:18:45,080 can be very fierce. 262 00:18:47,720 --> 00:18:51,280 The first ones at the scene are usually the rollers. 263 00:18:54,120 --> 00:18:59,000 They take a little lump, mould it into a ball and then start rolling. 264 00:19:04,840 --> 00:19:07,560 But that's easier said than done. 265 00:19:09,120 --> 00:19:11,760 Rivals are on the lookout for an easy meal 266 00:19:11,760 --> 00:19:15,480 and will only too quickly steal a ball if they can. 267 00:19:28,400 --> 00:19:32,480 With competition so intense, some species roll their ball away 268 00:19:32,480 --> 00:19:35,080 as quickly as possible and then bury it. 269 00:19:37,440 --> 00:19:39,040 They can then eat it later 270 00:19:39,040 --> 00:19:42,160 without the risk of another stealing their meal. 271 00:19:45,680 --> 00:19:50,640 Dung beetles appear to roll their balls of dung with great purpose. 272 00:19:50,640 --> 00:19:54,800 But it's only recently been discovered just how determined 273 00:19:54,800 --> 00:19:58,240 they can be to do so in one particular direction. 274 00:19:58,240 --> 00:20:02,080 Watch what happens if I put this dung beetle 275 00:20:02,080 --> 00:20:03,520 on this board here. 276 00:20:05,400 --> 00:20:09,080 And then put an obstacle in its way. 277 00:20:11,240 --> 00:20:13,080 And what does it do? 278 00:20:14,160 --> 00:20:16,080 It's going to go around. 279 00:20:16,080 --> 00:20:17,880 Excellent. 280 00:20:18,840 --> 00:20:22,000 And it resumes its previous direction. 281 00:20:24,240 --> 00:20:26,600 It's clear that the beetle knows exactly 282 00:20:26,600 --> 00:20:29,280 in which direction it wants to travel 283 00:20:29,280 --> 00:20:33,560 and will continue to do so even when it's deflected by obstacles. 284 00:20:35,480 --> 00:20:38,520 Now, let's make things even more difficult 285 00:20:38,520 --> 00:20:39,960 using this turntable. 286 00:20:41,040 --> 00:20:43,240 Let's see which direction 287 00:20:43,240 --> 00:20:44,560 he wants to go. 288 00:20:46,360 --> 00:20:48,680 He's going to come towards my hand. 289 00:20:48,680 --> 00:20:52,840 Now I'll turn the world through 90 degrees beneath his feet 290 00:20:52,840 --> 00:20:55,160 and yet he maintains 291 00:20:55,160 --> 00:20:57,000 the same direction. 292 00:20:57,000 --> 00:20:59,880 Why should it want to do that? 293 00:20:59,880 --> 00:21:02,360 It's quite extraordinary. 294 00:21:02,360 --> 00:21:05,680 He corrects his course instantaneously. 295 00:21:05,680 --> 00:21:07,880 How does he know how to do this, 296 00:21:07,880 --> 00:21:11,720 and why is he so determined to travel in a set direction? 297 00:21:15,280 --> 00:21:17,800 The answer is, in fact, quite simple. 298 00:21:18,880 --> 00:21:21,040 The fastest way to make a getaway 299 00:21:21,040 --> 00:21:23,880 is to roll your ball in a straight line. 300 00:21:26,200 --> 00:21:29,280 And that is exactly what the beetles try to do. 301 00:21:34,320 --> 00:21:36,600 Using only its front legs, 302 00:21:36,600 --> 00:21:40,800 a beetle can move a dung ball that is up to 60 times its own weight. 303 00:21:43,320 --> 00:21:48,080 But walking head down and backwards has its own problems. 304 00:21:48,080 --> 00:21:50,440 You can't see where you're going... 305 00:21:53,040 --> 00:21:55,240 ..or watch out for danger. 306 00:22:10,080 --> 00:22:13,560 With competition around the pile of dung so intense, 307 00:22:13,560 --> 00:22:17,920 it's obviously a good thing to get away from it as quickly as possible. 308 00:22:17,920 --> 00:22:21,440 But how do the beetles decide in which direction to go? 309 00:22:21,440 --> 00:22:25,480 Well, it seems it's all to do with a little dance that they perform 310 00:22:25,480 --> 00:22:27,040 on top of their dung balls. 311 00:22:27,040 --> 00:22:29,280 Let me see if I can persuade this one to do it. 312 00:22:32,960 --> 00:22:35,400 I'll try to get it to walk up this ramp 313 00:22:35,400 --> 00:22:37,280 until it falls off the end 314 00:22:37,280 --> 00:22:39,720 and is separated from its ball. 315 00:22:42,080 --> 00:22:44,200 Watch what it does then. 316 00:22:48,280 --> 00:22:50,080 This little dance was once 317 00:22:50,080 --> 00:22:52,640 regarded as being a sign of happiness, 318 00:22:52,640 --> 00:22:55,600 that the beetle was delighted to have found a dung ball. 319 00:22:55,600 --> 00:22:58,200 But actually, it's much more than that. 320 00:22:58,200 --> 00:23:02,440 It's a way of deciding which direction it should go. 321 00:23:02,440 --> 00:23:06,400 And what does it use as a cue to make that decision? 322 00:23:06,400 --> 00:23:10,840 Well, recent research is beginning to produce the answer. 323 00:23:13,800 --> 00:23:16,440 What appears to be a dance is actually 324 00:23:16,440 --> 00:23:19,400 a way of looking around to get its bearings. 325 00:23:22,960 --> 00:23:24,880 But what exactly is it looking for? 326 00:23:29,080 --> 00:23:32,480 We can test what the beetles are using for a cue 327 00:23:32,480 --> 00:23:34,520 by fitting them with caps. 328 00:23:34,520 --> 00:23:38,200 This cap allows the beetle to see the ground beneath, 329 00:23:38,200 --> 00:23:40,120 but not the sky above. 330 00:23:40,120 --> 00:23:43,960 Compare that with this one without a cap. 331 00:23:46,320 --> 00:23:47,760 Making up its mind. 332 00:23:47,760 --> 00:23:49,400 And away it goes. 333 00:23:50,400 --> 00:23:52,880 This one is still baffled. 334 00:23:55,000 --> 00:23:57,760 The beetle with the cap clearly can't decide 335 00:23:57,760 --> 00:23:59,360 in which direction to go. 336 00:24:05,320 --> 00:24:07,200 Such experiments show 337 00:24:07,200 --> 00:24:11,680 that dung beetles have to see the sky in order to orientate. 338 00:24:14,560 --> 00:24:19,440 Their eyes are split in two halves by shovel-like extensions 339 00:24:19,440 --> 00:24:21,280 on the sides of the head. 340 00:24:22,480 --> 00:24:25,080 So, as they roll their balls of dung, 341 00:24:25,080 --> 00:24:29,080 the upward-facing half can watch the sky above 342 00:24:29,080 --> 00:24:32,400 and use the sun as a celestial compass. 343 00:24:34,920 --> 00:24:38,920 But, contrary to what that ancient Egyptian scholar claimed, 344 00:24:38,920 --> 00:24:41,960 they don't always travel from east to west. 345 00:24:44,600 --> 00:24:47,360 Each beetle seems to choose a particular direction 346 00:24:47,360 --> 00:24:50,920 away from the dung heap and then keeps to that course. 347 00:24:56,840 --> 00:24:58,800 But why should anyone suppose 348 00:24:58,800 --> 00:25:02,760 that the dung beetle always rolls its dung from east to west? 349 00:25:02,760 --> 00:25:07,120 Well, the ancient Egyptians believed that their sun god, Khepri, 350 00:25:07,120 --> 00:25:11,600 was responsible for rolling the sun across the sky every day 351 00:25:11,600 --> 00:25:13,240 in just that direction. 352 00:25:14,880 --> 00:25:17,640 The scarab, the Egyptian dung beetle, 353 00:25:17,640 --> 00:25:21,000 similarly rolls its dung ball from dawn to dusk 354 00:25:21,000 --> 00:25:23,440 and came to symbolise the sun god. 355 00:25:26,000 --> 00:25:31,680 And so the god Khepri was often depicted with a scarab for a head. 356 00:25:34,280 --> 00:25:37,120 The Egyptians also saw the scarab 357 00:25:37,120 --> 00:25:40,160 as a symbol of life and resurrection. 358 00:25:40,160 --> 00:25:44,160 The adult beetle would disappear underground with the ball of dung, 359 00:25:44,160 --> 00:25:47,720 and when the eggs hatched, shiny, new scarab beetles 360 00:25:47,720 --> 00:25:50,880 would seem to appear magically out of nowhere. 361 00:25:50,880 --> 00:25:55,080 So the scarab came to symbolise creation, life 362 00:25:55,080 --> 00:25:57,000 and even rebirth. 363 00:25:59,240 --> 00:26:02,640 It's easy to see how the sun helps dung beetles 364 00:26:02,640 --> 00:26:04,760 to navigate during the day. 365 00:26:06,240 --> 00:26:08,880 But some beetles are nocturnal. 366 00:26:10,080 --> 00:26:12,680 How do they keep on a straight course? 367 00:26:19,160 --> 00:26:20,760 On a clear night, 368 00:26:20,760 --> 00:26:24,360 the moon and millions of stars illuminate the sky, 369 00:26:24,360 --> 00:26:27,640 just as they appear to do in this planetarium. 370 00:26:27,640 --> 00:26:31,080 This is a nocturnal scarab beetle. 371 00:26:31,080 --> 00:26:34,760 And scientists have recently discovered that it can use 372 00:26:34,760 --> 00:26:38,000 the light from the sky to navigate. 373 00:26:39,160 --> 00:26:41,080 But there is a puzzle. 374 00:26:41,080 --> 00:26:45,160 The scarab beetle has very, very small eyes. 375 00:26:45,160 --> 00:26:48,240 And whereas it can certainly see the moon, 376 00:26:48,240 --> 00:26:51,240 it can't distinguish individual stars. 377 00:26:51,240 --> 00:26:53,960 So how then does it navigate 378 00:26:53,960 --> 00:26:56,440 on a moonless night? 379 00:27:00,080 --> 00:27:02,600 The brightest light in the night sky 380 00:27:02,600 --> 00:27:06,600 comes from the great band of stars known as the Milky Way. 381 00:27:07,760 --> 00:27:11,000 And in the southern hemisphere, where these beetles live, 382 00:27:11,000 --> 00:27:14,160 the Milky Way is particularly vivid. 383 00:27:17,040 --> 00:27:20,600 Researchers have discovered that, as long as the Milky Way is in view, 384 00:27:20,600 --> 00:27:24,920 the beetle and its ball can roll along and stay on course. 385 00:27:26,400 --> 00:27:28,680 Without this bright band of light, 386 00:27:28,680 --> 00:27:32,320 the beetle has no reference point and is lost. 387 00:27:34,440 --> 00:27:38,720 The revelation that the beetles used starlight to navigate 388 00:27:38,720 --> 00:27:41,240 astonished the scientific world. 389 00:27:41,240 --> 00:27:44,960 How extraordinary that a tiny insect could use 390 00:27:44,960 --> 00:27:48,520 the edge of our galaxy to find its way around. 391 00:27:48,520 --> 00:27:52,480 Had the ancient Egyptians known that, surely they would have 392 00:27:52,480 --> 00:27:57,760 felt vindicated in giving the scarab the status of a god. 393 00:28:00,160 --> 00:28:05,160 So, the dung beetle and the pigeon are both ordinary creatures 394 00:28:05,160 --> 00:28:08,480 that have found extraordinary solutions 395 00:28:08,480 --> 00:28:11,440 to the problem that faces us all - 396 00:28:11,440 --> 00:28:14,000 how to find the way.