1 00:00:01,600 --> 00:00:04,920 In the natural world, 2 00:00:04,920 --> 00:00:08,200 you need to be smart... 3 00:00:08,200 --> 00:00:10,040 ..to stay alive. 4 00:00:11,840 --> 00:00:16,720 But we're only just discovering that some animals are brighter 5 00:00:16,720 --> 00:00:19,200 than we ever imagined. 6 00:00:19,200 --> 00:00:24,080 I've never failed to be impressed by nature's sheer ingenuity. 7 00:00:25,680 --> 00:00:29,600 Now, brand-new science using innovative techniques and the latest 8 00:00:29,600 --> 00:00:34,280 technology is revealing some surprising brainboxes. 9 00:00:34,280 --> 00:00:38,080 You can get bees to learn almost anything. 10 00:00:38,080 --> 00:00:41,120 Researchers across the globe... THEY LAUGH 11 00:00:41,120 --> 00:00:43,800 ..are uncovering the mind-blowing tricks... 12 00:00:45,240 --> 00:00:49,960 ..and clever strategies that give certain species the upper hand. 13 00:00:49,960 --> 00:00:54,880 It is an animal showcasing its intelligence in front of your eyes. 14 00:00:57,360 --> 00:00:59,920 As they build their homes... 15 00:01:01,040 --> 00:01:03,040 ..navigate their world... 16 00:01:04,280 --> 00:01:06,960 ..and raise their young. 17 00:01:06,960 --> 00:01:11,600 It's time to get inside the minds of nature's savviest species. 18 00:01:12,840 --> 00:01:16,040 But, I warn you, there's going to be a few surprises 19 00:01:16,040 --> 00:01:19,320 and some controversial candidates. 20 00:01:19,320 --> 00:01:23,480 But, most importantly, it's going to give us an opportunity to learn 21 00:01:23,480 --> 00:01:25,800 from these animal Einsteins 22 00:01:25,800 --> 00:01:27,840 and that's really exciting. 23 00:01:30,080 --> 00:01:33,920 In this programme, I'll be looking at the brilliant brains behind some 24 00:01:33,920 --> 00:01:37,200 of nature's best builders. 25 00:01:37,200 --> 00:01:42,320 We'll discover how beaver dams beat our engineering, 26 00:01:42,320 --> 00:01:47,560 how a spider constructs an underwater survival solution, 27 00:01:47,560 --> 00:01:51,600 and how the foundations of our own intelligence lie 28 00:01:51,600 --> 00:01:53,640 in apes building nests. 29 00:01:54,880 --> 00:02:00,840 So, just how good are Mother Nature's ingenious animal architects? 30 00:02:11,720 --> 00:02:16,360 This is the Meldon dam in Devon, an impressive structure 31 00:02:16,360 --> 00:02:20,200 that dominates the landscape here and holds back millions 32 00:02:20,200 --> 00:02:24,560 of gallons of one of our most precious resources, water. 33 00:02:25,760 --> 00:02:29,280 But when it comes to modifying the landscape to suit our needs, 34 00:02:29,280 --> 00:02:32,880 we're not the only ones doing it with dams. 35 00:02:32,880 --> 00:02:35,040 Ladies and gentlemen, and young people, 36 00:02:35,040 --> 00:02:37,320 I give you the beaver. 37 00:02:39,760 --> 00:02:44,040 These supersized semi-aquatic rodents are the only animals 38 00:02:44,040 --> 00:02:46,440 other than humans to build dams 39 00:02:46,440 --> 00:02:50,280 and they do it for exactly the same reason - 40 00:02:50,280 --> 00:02:52,320 to hold back water. 41 00:02:53,920 --> 00:02:58,000 Beavers skilfully block streams and rivers, creating vast ponds 42 00:02:58,000 --> 00:03:02,280 that help keep them safe from land predators and store food underwater 43 00:03:02,280 --> 00:03:05,680 to see them through harsh winters. 44 00:03:05,680 --> 00:03:09,400 They even sleep and raise young in these ponds, 45 00:03:09,400 --> 00:03:13,040 constructing ultra strong lodges that can only be accessed 46 00:03:13,040 --> 00:03:15,080 by underwater entrances. 47 00:03:15,080 --> 00:03:17,480 A fortress for the family. 48 00:03:19,000 --> 00:03:22,600 But it's their dams that are the most impressive structures, 49 00:03:22,600 --> 00:03:27,480 transforming the whole landscape, and they can be huge. 50 00:03:28,880 --> 00:03:31,960 I can tell you, for instance, that the longest beaver dam 51 00:03:31,960 --> 00:03:37,880 in the world, at over 850 metres, is four times longer than the dam 52 00:03:37,880 --> 00:03:43,560 I was standing on earlier - and so big it can be seen from space. 53 00:03:43,560 --> 00:03:46,240 That's an incredible feat of engineering 54 00:03:46,240 --> 00:03:49,240 and it's not only the size that's remarkable. 55 00:03:49,240 --> 00:03:53,080 To help evade predators, beavers are largely nocturnal, 56 00:03:53,080 --> 00:03:55,400 so they're building these structures 57 00:03:55,400 --> 00:03:58,760 in almost complete darkness, using natural materials 58 00:03:58,760 --> 00:04:01,240 with no plans and no training at all. 59 00:04:03,040 --> 00:04:04,240 Amazing. 60 00:04:06,960 --> 00:04:08,960 But we, too, build dams. 61 00:04:11,960 --> 00:04:14,400 And, with thousands of years of experience, 62 00:04:14,400 --> 00:04:16,640 we're getting quite good at it. 63 00:04:21,960 --> 00:04:26,600 Nevertheless, beavers have been building for millions of years 64 00:04:26,600 --> 00:04:29,680 and, over that time, they've picked up some pretty crafty 65 00:04:29,680 --> 00:04:32,280 construction techniques of their own. 66 00:04:36,920 --> 00:04:41,480 Recent research on beaver dams has shown that the upstream slope 67 00:04:41,480 --> 00:04:45,640 beneath the water is a lot shallower than the downstream slope, 68 00:04:45,640 --> 00:04:49,520 meaning that they can hold back considerably more water, 69 00:04:49,520 --> 00:04:55,240 something that I can demonstrate using this pair of doorstops. 70 00:04:55,240 --> 00:05:00,320 Now, if the beavers got it wrong and built their dam with a sheer face 71 00:05:00,320 --> 00:05:03,920 upstream, let's imagine that the door represents the weight 72 00:05:03,920 --> 00:05:05,600 of the water in the lake. 73 00:05:05,600 --> 00:05:09,480 If the mass of water is greater than the mass of the dam, 74 00:05:09,480 --> 00:05:13,680 then it's easily shifted by that water. 75 00:05:13,680 --> 00:05:15,760 However, the beavers don't do that, do they? 76 00:05:15,760 --> 00:05:18,600 They have the shallow slope on their dams. 77 00:05:18,600 --> 00:05:22,960 And this means that, when the weight of the water meets the dam, 78 00:05:22,960 --> 00:05:27,720 the vertical forces pressing down outweigh the horizontal forces 79 00:05:27,720 --> 00:05:32,000 of the water pressing downstream and the dam is immovable. 80 00:05:32,000 --> 00:05:34,040 In the real world of the beaver, 81 00:05:34,040 --> 00:05:37,040 as the horizontal forces of the water meet the dam, 82 00:05:37,040 --> 00:05:42,040 they become vertical and pin that dam to the base of the lake - 83 00:05:42,040 --> 00:05:45,800 and that's how it can hold back a lot more water. 84 00:05:50,120 --> 00:05:54,120 Whilst we haven't copied beaver dam building, human engineers 85 00:05:54,120 --> 00:05:56,920 have plumped for some of the same solutions. 86 00:05:58,240 --> 00:06:03,680 Just like the beavers, we also bow our dams upstream, a proven way 87 00:06:03,680 --> 00:06:06,320 of engineering these structures to be strong 88 00:06:06,320 --> 00:06:10,600 and incredibly long-lasting. 89 00:06:10,600 --> 00:06:14,160 So long-lasting, in fact, that beaver dams marked up on maps 90 00:06:14,160 --> 00:06:20,040 of North America from 1868 can still be found in use today. 91 00:06:21,680 --> 00:06:24,360 Using sticks, stones, rocks, and mud, 92 00:06:24,360 --> 00:06:28,240 these structures are clearly built to last. 93 00:06:28,240 --> 00:06:32,640 So just how do these master builders do it and what can we learn 94 00:06:32,640 --> 00:06:35,280 from beaver engineering expertise? 95 00:06:40,240 --> 00:06:41,840 Beavers really are the ones which, 96 00:06:41,840 --> 00:06:43,680 in our field of hydraulic engineering, 97 00:06:43,680 --> 00:06:46,480 provide by far the most interesting 98 00:06:46,480 --> 00:06:52,040 and the most far reaching solution to problems. 99 00:06:52,040 --> 00:06:55,560 Dr Gerald Muller is an engineer convinced that, when it comes 100 00:06:55,560 --> 00:06:58,480 to the dams of the future, taking a log out 101 00:06:58,480 --> 00:07:02,400 of the beaver construction manual is a very sensible approach. 102 00:07:02,400 --> 00:07:05,720 Beaver dams are very interesting from the point of view 103 00:07:05,720 --> 00:07:10,280 that, A, they are very strong and, B, you use natural material 104 00:07:10,280 --> 00:07:14,360 which is available everywhere, which is quite cheap. 105 00:07:14,360 --> 00:07:16,800 It also is a nature-based solution 106 00:07:16,800 --> 00:07:19,840 where we can re-use the material easily. 107 00:07:19,840 --> 00:07:22,320 If you would build a dam from reinforced concrete 108 00:07:22,320 --> 00:07:24,960 and you want to take it away, you need to get the jackhammer out 109 00:07:24,960 --> 00:07:30,560 and hammer it apart and you are left with some steel and a pile of rubble 110 00:07:30,560 --> 00:07:32,680 which cannot really be reused. 111 00:07:32,680 --> 00:07:36,160 And, from that point of view, a solution like this is really 112 00:07:36,160 --> 00:07:39,560 very near ideal, I must say. 113 00:07:39,560 --> 00:07:44,040 In short, the natural materials beavers use, like stones, wood, 114 00:07:44,040 --> 00:07:47,480 and mud, have an extremely small carbon pawprint. 115 00:07:48,760 --> 00:07:52,760 How good are they, though, at the job of retaining water? 116 00:07:54,440 --> 00:07:57,440 So, this is an experiment we designed to find out how strong 117 00:07:57,440 --> 00:07:59,840 beaver dams actually are. 118 00:07:59,840 --> 00:08:04,560 In the first experiment, Gerald sets up a dam using just rocks. 119 00:08:04,560 --> 00:08:08,200 By subjecting this structure to a simulated flood event, 120 00:08:08,200 --> 00:08:11,680 Gerald is able to measure the rock dam's strength. 121 00:08:16,440 --> 00:08:20,360 And I need to make a quick mark of the water level 122 00:08:20,360 --> 00:08:23,920 to make sure that we capture the maximum water level 123 00:08:23,920 --> 00:08:27,200 because, otherwise, it will, of course, drop and we don't have 124 00:08:27,200 --> 00:08:30,800 a record of the...of the maximum level. 125 00:08:30,800 --> 00:08:33,920 Whilst the height of the water gives an indication of the pressures 126 00:08:33,920 --> 00:08:37,680 the dam can withstand, the real measure of any dam 127 00:08:37,680 --> 00:08:39,480 is how long it stays up. 128 00:08:41,040 --> 00:08:44,560 Gerald's rock-only dam is soon undermined 129 00:08:44,560 --> 00:08:48,680 and, within just five minutes, it begins to collapse. 130 00:08:48,680 --> 00:08:52,120 So, now you can see what happened to our rubble-only dam 131 00:08:52,120 --> 00:08:54,520 after a while in the high flood. 132 00:08:54,520 --> 00:08:57,680 It has lost about two centimetres in height, 133 00:08:57,680 --> 00:09:00,720 but also about two thirds of its mass. 134 00:09:00,720 --> 00:09:04,760 It's just a pile of rubble, really, and the material gets washed away 135 00:09:04,760 --> 00:09:07,120 and deposited somewhere downstream. 136 00:09:08,720 --> 00:09:13,000 It turns out that simple piles of rocks are not very effective. 137 00:09:14,440 --> 00:09:19,200 Reassuringly, though, beaver builders are a little more creative. 138 00:09:19,200 --> 00:09:23,080 In the wild, they're often observed going to great lengths sourcing 139 00:09:23,080 --> 00:09:27,720 all sorts of materials to put into their dams, even digging canals 140 00:09:27,720 --> 00:09:31,160 to help them float larger logs straight to the site. 141 00:09:32,480 --> 00:09:34,960 But is all of that effort worth it? 142 00:09:38,880 --> 00:09:41,440 The beavers are building their dams with rock 143 00:09:41,440 --> 00:09:43,880 and with branches and wood, 144 00:09:43,880 --> 00:09:46,520 so that's what we're doing in this experiment. We're combining 145 00:09:46,520 --> 00:09:49,360 both materials and we put in the rocks first, 146 00:09:49,360 --> 00:09:52,200 and then a layer of branches. 147 00:09:53,320 --> 00:09:57,280 Could Gerald prove that, by choosing to combine materials, 148 00:09:57,280 --> 00:10:00,880 beavers were actually building stronger dams? 149 00:10:00,880 --> 00:10:02,920 Time for the next flood. 150 00:10:04,000 --> 00:10:06,000 How would the beavers' design compare 151 00:10:06,000 --> 00:10:08,920 to Gerald's first dam using just rocks? 152 00:10:11,520 --> 00:10:16,400 We have this difference in water level, so we've got more than twice 153 00:10:16,400 --> 00:10:20,360 the difference and that means more than three times the flow volume 154 00:10:20,360 --> 00:10:23,920 for the twig and rock dam. 155 00:10:23,920 --> 00:10:26,640 And you can see here the dam is stable. 156 00:10:26,640 --> 00:10:29,440 So, overall, I would say that it's a success. 157 00:10:29,440 --> 00:10:33,440 This dam is much stronger than the dam without reinforcement. 158 00:10:35,160 --> 00:10:38,240 Beaver dams might look chaotic, 159 00:10:38,240 --> 00:10:41,240 but the combination of materials they put together makes 160 00:10:41,240 --> 00:10:43,120 perfect structural sense. 161 00:10:44,880 --> 00:10:48,120 Adding branches to the rock dam means you add 162 00:10:48,120 --> 00:10:50,480 what we call tensile strength - 163 00:10:50,480 --> 00:10:54,000 that is the strength against pulling something apart to the structure - 164 00:10:54,000 --> 00:10:58,160 that increases the strength of the structure enormously. 165 00:10:58,160 --> 00:11:00,440 In engineering, this technique is actually known. 166 00:11:00,440 --> 00:11:03,200 There's a construction technique called reinforced earth, 167 00:11:03,200 --> 00:11:05,680 which uses the same principle but that was only discovered 168 00:11:05,680 --> 00:11:08,160 in the 1920s, I think, whereas the beavers have used it 169 00:11:08,160 --> 00:11:10,600 for millions of years. 170 00:11:10,600 --> 00:11:15,720 Brilliant engineers with an evolved understanding of material physics. 171 00:11:15,720 --> 00:11:19,120 Beavers can clearly teach us a lot when it comes to dam building. 172 00:11:23,680 --> 00:11:27,480 And they've also evolved the perfect tools for the job. 173 00:11:35,040 --> 00:11:36,600 Take a look at this. 174 00:11:36,600 --> 00:11:39,040 This is a beaver skull. 175 00:11:39,040 --> 00:11:41,480 It's absolutely fantastic. 176 00:11:41,480 --> 00:11:45,720 What I want to show you are its incisors here, its teeth. 177 00:11:45,720 --> 00:11:48,000 Firstly, look, they're bright orange, and that's 178 00:11:48,000 --> 00:11:51,840 because the enamel on the outside is filled full of iron oxide, 179 00:11:51,840 --> 00:11:54,080 a really tough compound. 180 00:11:54,080 --> 00:11:56,960 And they're self-sharpening, too. As they chew the word, 181 00:11:56,960 --> 00:11:59,560 the soft dentin at the back is worn away, 182 00:11:59,560 --> 00:12:04,040 leaving this cutting edge here very, very sharp. 183 00:12:04,040 --> 00:12:06,840 And there's a clear parallel between the way that they sharpen 184 00:12:06,840 --> 00:12:09,440 their teeth and we sharpen our chisels. 185 00:12:09,440 --> 00:12:12,520 When you think about it, we sharpen this edge here, 186 00:12:12,520 --> 00:12:15,560 leaving the cutting edge equally sharp. 187 00:12:15,560 --> 00:12:19,280 And when you look at it, the profile's exactly the same, too. 188 00:12:19,280 --> 00:12:21,960 It's easy to see why, given the teeth and the brain 189 00:12:21,960 --> 00:12:25,000 that we've got here, that we should be celebrating the beaver 190 00:12:25,000 --> 00:12:29,200 as one of the greatest builders in the natural world. 191 00:12:29,200 --> 00:12:33,080 But now, having said that, the beaver brings its tools 192 00:12:33,080 --> 00:12:34,680 to the construction. 193 00:12:34,680 --> 00:12:36,400 What about if you had an animal 194 00:12:36,400 --> 00:12:40,520 that also brought its own materials at the same time? 195 00:12:40,520 --> 00:12:43,040 Now, that really would be something. 196 00:12:46,880 --> 00:12:52,000 There's one animal that supplies a complete design-and-build package. 197 00:12:52,000 --> 00:12:55,640 Yes, if your spider sense is tingling, so is mine. 198 00:12:59,640 --> 00:13:03,960 There are more than 48,000 known species of spider found 199 00:13:03,960 --> 00:13:06,800 on every continent apart from Antarctica... 200 00:13:08,200 --> 00:13:13,600 ..and in many diverse habitats - from desert to jungle 201 00:13:13,600 --> 00:13:15,920 and even in our own homes. 202 00:13:17,360 --> 00:13:21,280 Almost all species are predators and they hunt using a wide range 203 00:13:21,280 --> 00:13:25,720 of strategies - from chasing their prey to lassoing it 204 00:13:25,720 --> 00:13:28,720 and, most familiar to us all, building webs 205 00:13:28,720 --> 00:13:31,040 to catch their food in flight. 206 00:13:31,040 --> 00:13:37,600 And although not all spiders build webs, every species produces silk. 207 00:13:37,600 --> 00:13:40,920 And should you choose to study one of the strongest and toughest 208 00:13:40,920 --> 00:13:43,400 natural materials on the planet, 209 00:13:43,400 --> 00:13:46,400 you'll need a hands-on approach with spiders. 210 00:13:48,120 --> 00:13:50,080 Right, so maybe I can invite you 211 00:13:50,080 --> 00:13:54,560 into our arachnarium, our spider room. 212 00:13:54,560 --> 00:13:58,280 I hope you're not arachnophobes - 213 00:13:58,280 --> 00:13:59,720 then you should stay outside. 214 00:13:59,720 --> 00:14:02,240 But, if you're not, please come in. 215 00:14:03,720 --> 00:14:06,160 Professor Fritz Vollrath is a scientist 216 00:14:06,160 --> 00:14:09,240 at the Oxford University Silk Group. 217 00:14:09,240 --> 00:14:12,200 These are the spiders that we study for the silk. 218 00:14:12,200 --> 00:14:14,960 These are big golden orb spiders, 219 00:14:14,960 --> 00:14:18,280 and this one has just been silked and I'm putting her back. 220 00:14:18,280 --> 00:14:20,120 She's doesn't want to let go. 221 00:14:20,120 --> 00:14:22,560 She loves me, look at that. 222 00:14:22,560 --> 00:14:26,640 The spider is the only animal really that makes something out of itself. 223 00:14:26,640 --> 00:14:29,600 So, the web is an extension of the body of the animal, 224 00:14:29,600 --> 00:14:32,920 but it's built out of apparently nothing, 225 00:14:32,920 --> 00:14:35,480 out of the silk that is inside the spider. 226 00:14:36,960 --> 00:14:39,840 The spiders were about the first animals on land, 227 00:14:39,840 --> 00:14:41,840 so about 400 million years ago, 228 00:14:41,840 --> 00:14:44,320 the insects came a little bit later, 229 00:14:44,320 --> 00:14:51,080 and they came on land already with a silk-like material. 230 00:14:51,080 --> 00:14:54,280 First they used the silk to wallpaper, as it were, 231 00:14:54,280 --> 00:14:58,320 actual burrows when there was a flooding. 232 00:14:58,320 --> 00:15:04,000 And then the silk evolved into a trap that could not only inform 233 00:15:04,000 --> 00:15:07,280 the spider about insects wandering about, 234 00:15:07,280 --> 00:15:11,240 but also hold these insects firm for a while. 235 00:15:11,240 --> 00:15:14,120 It's a highly evolved material 236 00:15:14,120 --> 00:15:16,040 and that, of course, is still evolving 237 00:15:16,040 --> 00:15:18,160 in this arms race with the insects. 238 00:15:19,880 --> 00:15:23,320 Yet here is the really clever bit. 239 00:15:23,320 --> 00:15:26,760 Where a silk worm can only produce one silk, 240 00:15:26,760 --> 00:15:30,720 spiders can make up to seven different types, 241 00:15:30,720 --> 00:15:33,680 each one crafted for a specific task. 242 00:15:35,880 --> 00:15:39,800 In building terms, it's like having the ability to produce bricks, 243 00:15:39,800 --> 00:15:42,600 concrete, rafters, and fixtures and fittings 244 00:15:42,600 --> 00:15:45,000 all out of your backside. 245 00:15:48,040 --> 00:15:51,120 It's an unmatched ability in the animal kingdom, 246 00:15:51,120 --> 00:15:54,600 but the real genius is that spiders know how to build 247 00:15:54,600 --> 00:15:57,680 with these materials effectively. 248 00:15:57,680 --> 00:16:01,080 Just take a look at how cleverly they combine silks 249 00:16:01,080 --> 00:16:03,280 when building an orb web. 250 00:16:03,280 --> 00:16:07,520 To start with, spiders always use their toughest silk 251 00:16:07,520 --> 00:16:10,280 on the spokes and radial strands. 252 00:16:10,280 --> 00:16:14,080 These will form the framework on which the structure will hang. 253 00:16:14,080 --> 00:16:17,320 A special silk then circles the centre. 254 00:16:17,320 --> 00:16:20,640 Onto this, a skeleton silk is added - 255 00:16:20,640 --> 00:16:25,240 effectively, scaffolding that holds the spokes in place - 256 00:16:25,240 --> 00:16:28,360 and it's removed when the web is completed. 257 00:16:28,360 --> 00:16:31,760 Only when this solid framework is firmly in place 258 00:16:31,760 --> 00:16:36,040 can the spider attach its key material - capture silk. 259 00:16:39,400 --> 00:16:43,520 It's these extra sticky strands with built-in shock absorbers 260 00:16:43,520 --> 00:16:47,400 that allow orb webs to both catch and hold their prey. 261 00:16:48,840 --> 00:16:53,120 You can imagine that this is an anti-weapon device, basically. 262 00:16:53,120 --> 00:16:55,720 Flying insects are, in effect, bullets. 263 00:16:55,720 --> 00:16:59,000 They come with a really huge amount of kinetic energy 264 00:16:59,000 --> 00:17:02,520 and they hit the web and the web must stop it, 265 00:17:02,520 --> 00:17:05,760 and not fling it back out - so it can't act as a trampoline. 266 00:17:07,320 --> 00:17:09,840 Or, to put it another way... 267 00:17:09,840 --> 00:17:14,320 Imagine you were a spider the size of a human 268 00:17:14,320 --> 00:17:17,760 and you were to make a web like the spider does - 269 00:17:17,760 --> 00:17:20,360 it would be the size of a cricket pitch. 270 00:17:20,360 --> 00:17:23,320 And, in terms of strength from the material, 271 00:17:23,320 --> 00:17:26,240 it would be able to catch small airplanes. 272 00:17:26,240 --> 00:17:31,120 So, that, if you just think about that, that's really interesting. 273 00:17:31,120 --> 00:17:35,120 You have to admit, Fritz certainly has a point. 274 00:17:35,120 --> 00:17:38,200 Spiders build a huge variety of structures, 275 00:17:38,200 --> 00:17:43,040 but it's the superlative skills of the 3,000 species of orb web spider 276 00:17:43,040 --> 00:17:46,560 that have really captured our imagination. 277 00:17:46,560 --> 00:17:50,320 With thousands to choose from, it's hard to pick a favourite, 278 00:17:50,320 --> 00:17:54,200 but there's one that I think deserves a special mention. 279 00:17:55,280 --> 00:17:58,520 Just look at this beautiful animal. 280 00:17:58,520 --> 00:18:02,880 This is one of the 11 species of Nephila spider. 281 00:18:02,880 --> 00:18:08,040 They're tropical animals and they make the most remarkable webs, 282 00:18:08,040 --> 00:18:12,200 but what they're really after is a range of quite large prey. 283 00:18:12,200 --> 00:18:17,200 They make huge webs, some sticky, some just acting as baffles 284 00:18:17,200 --> 00:18:19,840 to channel the prey into those sticky bits. 285 00:18:19,840 --> 00:18:24,880 And they can feed on small snakes and even small birds, too. 286 00:18:24,880 --> 00:18:28,560 They are remarkable animals and they do make remarkable webs. 287 00:18:28,560 --> 00:18:32,000 But, of course, they're making them on the surface. 288 00:18:32,000 --> 00:18:34,720 There is another species of spider which I think trumps them 289 00:18:34,720 --> 00:18:38,240 because it makes its web beneath the water. 290 00:18:38,240 --> 00:18:40,520 It's the diving bell spider. 291 00:18:42,400 --> 00:18:47,040 When life got too tough up top, this species built itself 292 00:18:47,040 --> 00:18:48,640 a brilliant solution. 293 00:18:53,760 --> 00:18:57,440 Diving bell spiders live almost completely underwater 294 00:18:57,440 --> 00:19:01,040 by weaving a special sac filled with trapped air. 295 00:19:04,000 --> 00:19:08,160 The thread frame they used to build this diving bell is then covered 296 00:19:08,160 --> 00:19:13,680 in gel-like sheets of silk, keeping air bubbles trapped, but also 297 00:19:13,680 --> 00:19:18,480 allowing oxygen and carbon dioxide to diffuse into the chamber, 298 00:19:18,480 --> 00:19:21,560 letting the spider breathe. 299 00:19:21,560 --> 00:19:23,440 It's genius. 300 00:19:23,440 --> 00:19:27,000 You could say this spider has built artificial gills, 301 00:19:27,000 --> 00:19:31,240 something no other animal has achieved, including us humans. 302 00:19:32,560 --> 00:19:36,040 Other animals, though, have taken a far simpler approach 303 00:19:36,040 --> 00:19:38,800 to keeping themselves out of harm's way. 304 00:19:38,800 --> 00:19:41,480 They don't dive - they dig. 305 00:19:51,240 --> 00:19:53,800 The world presents many threats to animals 306 00:19:53,800 --> 00:19:57,120 and, the more of these that can be mitigated, the more successful 307 00:19:57,120 --> 00:19:59,360 that animal will be. 308 00:19:59,360 --> 00:20:03,040 Digging a simple hole allows you to stay safe from predators. 309 00:20:03,040 --> 00:20:05,840 You can keep your young protected, store food, 310 00:20:05,840 --> 00:20:08,480 and protect yourself from the weather. 311 00:20:10,320 --> 00:20:15,240 To see a top digger in action, let's head to the vast grasslands 312 00:20:15,240 --> 00:20:18,440 of North America, home of the prairie dog. 313 00:20:23,440 --> 00:20:26,480 Out here, there's plenty for them to munch on - 314 00:20:26,480 --> 00:20:31,440 but they have to share this perfect pasture with a host of predators 315 00:20:31,440 --> 00:20:34,720 whose preferred source of protein... 316 00:20:34,720 --> 00:20:36,320 ..is prairie dog. 317 00:20:37,960 --> 00:20:41,200 With very little cover above ground to conceal them, 318 00:20:41,200 --> 00:20:45,880 the only way to get themselves out of a jam is to go underground, 319 00:20:45,880 --> 00:20:48,040 building themselves to safety. 320 00:20:50,560 --> 00:20:54,800 Down here, dozens of entrances and exits provide every chance 321 00:20:54,800 --> 00:21:01,080 of a getaway from dangers above and below the surface. 322 00:21:01,080 --> 00:21:03,960 Other holes are built as listening posts, 323 00:21:03,960 --> 00:21:08,240 vital early warning from any unseen dangers lurking above. 324 00:21:09,880 --> 00:21:14,720 Yes, self-preservation is clearly a priority for these guys... 325 00:21:15,960 --> 00:21:20,200 ..but prairie dogs have also been sensible enough to engineer in 326 00:21:20,200 --> 00:21:22,760 a few all-important creature comforts. 327 00:21:28,720 --> 00:21:29,960 Prairie dogs - 328 00:21:29,960 --> 00:21:34,000 what do they have in common with the designers of this building? 329 00:21:34,000 --> 00:21:37,440 Well, interestingly, it's chimneys. 330 00:21:37,440 --> 00:21:42,160 We want chimneys in our houses to vent the smoke from our fires. 331 00:21:42,160 --> 00:21:45,960 The prairie dogs, on the other hand, need a system of air conditioning 332 00:21:45,960 --> 00:21:48,600 to get fresh air into their tunnels. 333 00:21:48,600 --> 00:21:50,480 But how do they achieve it? 334 00:21:50,480 --> 00:21:52,920 Well, they use some physics. 335 00:21:52,920 --> 00:21:55,840 A fellow called Daniel Bernoulli published a book 336 00:21:55,840 --> 00:22:01,960 called Hydrodynamica in 1738, in which he outlined his principle. 337 00:22:01,960 --> 00:22:06,720 On this simple diagram, I can show you that air moves more slowly 338 00:22:06,720 --> 00:22:09,160 when it's close to the ground and faster 339 00:22:09,160 --> 00:22:11,600 when it's a few metres above the ground. 340 00:22:11,600 --> 00:22:16,640 Here, it generates a lower pressure over the entrance to any tube 341 00:22:16,640 --> 00:22:18,920 than the air at ground level, 342 00:22:18,920 --> 00:22:24,800 thus the difference in pressure draws air through the tube. 343 00:22:24,800 --> 00:22:27,400 But you do need a difference in height. 344 00:22:27,400 --> 00:22:31,520 So, if you're a prairie dog, you've got to build yourself a chimney. 345 00:22:31,520 --> 00:22:34,040 You've got to build yourself a mound. 346 00:22:34,040 --> 00:22:39,840 And that's exactly what they do to effect an enormously efficient 347 00:22:39,840 --> 00:22:43,480 system of air conditioning, which brings brilliant fresh air 348 00:22:43,480 --> 00:22:46,520 into their extensive prairie dog cities on the plains 349 00:22:46,520 --> 00:22:48,400 of North America. 350 00:22:48,400 --> 00:22:52,360 Now, I don't have a say in the matter, but, if I did, I'd give 351 00:22:52,360 --> 00:22:55,720 these prairie dogs the Nobel Prize for physics. 352 00:22:58,920 --> 00:23:03,200 Nobel Prize pending, prairie dogs' burrow building has certainly 353 00:23:03,200 --> 00:23:07,080 been key to their success as a species, providing ample 354 00:23:07,080 --> 00:23:10,720 opportunity for escape and a comfortable life underground. 355 00:23:10,720 --> 00:23:15,360 Colonies can number thousands of individuals. 356 00:23:15,360 --> 00:23:19,440 However, as successful as prairie dogs' holes have made them, 357 00:23:19,440 --> 00:23:23,320 they still have to risk returning to the surface for food. 358 00:23:25,040 --> 00:23:28,800 But over in East Africa lives the king of concealment - 359 00:23:28,800 --> 00:23:32,040 an expert tunneller who's perfected the art 360 00:23:32,040 --> 00:23:34,920 of staying out of harm's way. 361 00:23:34,920 --> 00:23:39,280 Ladies and gentlemen, one of the brightest builders on the block, 362 00:23:39,280 --> 00:23:41,960 the naked mole-rat. 363 00:23:45,760 --> 00:23:50,320 Naked mole-rats accrue in the hot, arid regions of East Africa, 364 00:23:50,320 --> 00:23:55,000 in countries like Kenya, Ethiopia, and Somalia. 365 00:23:55,000 --> 00:23:58,640 Above ground, these virtually-blind, hairless creatures 366 00:23:58,640 --> 00:24:03,320 wouldn't last five minutes, but the clever burrow systems they build 367 00:24:03,320 --> 00:24:06,760 has allowed them to live in a challenging environment 368 00:24:06,760 --> 00:24:09,400 where many other mammals struggle. 369 00:24:09,400 --> 00:24:12,960 Groups excavate miles of tunnels and connecting chambers 370 00:24:12,960 --> 00:24:16,720 within the burrow, each with a purpose - such as sleeping, 371 00:24:16,720 --> 00:24:18,680 breeding, and eating. 372 00:24:18,680 --> 00:24:21,200 They even designate a toilet room. 373 00:24:22,400 --> 00:24:27,880 In essence, they built a bunker, a refuge from predators and a shelter 374 00:24:27,880 --> 00:24:32,920 from harsh weather that's capable of sustaining not just small families, 375 00:24:32,920 --> 00:24:38,360 but huge colonies of hundreds of individuals all year round. 376 00:24:38,360 --> 00:24:42,920 Few mammals' survival is so completely entwined with its home, 377 00:24:42,920 --> 00:24:46,960 so looking after them in captivity can be quite a challenge. 378 00:24:46,960 --> 00:24:51,320 I've been caring for naked mole-rats for around three to four years now. 379 00:24:51,320 --> 00:24:55,560 Paige Bwye is the mole-rat keeper at Bristol Zoo. 380 00:24:55,560 --> 00:24:57,720 They're definitely different to all the other mammals 381 00:24:57,720 --> 00:24:59,360 that I look after here. 382 00:24:59,360 --> 00:25:01,240 Because they live completely underground, 383 00:25:01,240 --> 00:25:04,280 it makes how we care for them very different. 384 00:25:04,280 --> 00:25:08,320 To a naked mole-rat, excavating is everything. 385 00:25:09,560 --> 00:25:12,600 With a quarter of its muscle mass in its jaws, 386 00:25:12,600 --> 00:25:14,640 and teeth that protrude in front of its lips 387 00:25:14,640 --> 00:25:17,440 so dirt doesn't get in its mouth, 388 00:25:17,440 --> 00:25:20,680 they are perfectly evolved to shift soil. 389 00:25:22,320 --> 00:25:25,920 And, here at the zoo, they've found a clever way to keep these burrow 390 00:25:25,920 --> 00:25:29,040 builders doing just what they do best in the wild. 391 00:25:31,280 --> 00:25:33,120 We know they spend a lot of time digging, 392 00:25:33,120 --> 00:25:36,960 so one thing that we've created is an artificial sand hopper 393 00:25:36,960 --> 00:25:40,560 and what we do is we fill up these boxes here with sand, 394 00:25:40,560 --> 00:25:42,040 just like so... 395 00:25:43,440 --> 00:25:46,120 This sends out a signal to all the naked mole-rats. 396 00:25:46,120 --> 00:25:47,760 Wherever they are, they seem to realise 397 00:25:47,760 --> 00:25:49,320 what's going on straight away... 398 00:25:51,000 --> 00:25:55,280 ..that either a tunnel has collapsed or it's a new area that they haven't 399 00:25:55,280 --> 00:25:59,720 explored before, and it might have some novel scents on it. 400 00:25:59,720 --> 00:26:02,480 So, they'll come straight in and they'll start digging 401 00:26:02,480 --> 00:26:04,560 at this new area. 402 00:26:07,200 --> 00:26:08,720 To look at the naked mole-rats, 403 00:26:08,720 --> 00:26:11,080 they look like quite a vulnerable mammal, really - 404 00:26:11,080 --> 00:26:12,800 the fact that they have no hair, 405 00:26:12,800 --> 00:26:16,040 they've got quite poor eyesight, they're so small. 406 00:26:16,040 --> 00:26:18,400 But, actually, it makes them perfectly designed 407 00:26:18,400 --> 00:26:20,560 for living underground. 408 00:26:21,960 --> 00:26:25,320 Never having to leave its home means that mole-rats 409 00:26:25,320 --> 00:26:27,720 are one of the few species that have evolved 410 00:26:27,720 --> 00:26:32,080 to inhabit an environment they themselves have created. 411 00:26:32,080 --> 00:26:35,240 Biologically, they've become uniquely adapted 412 00:26:35,240 --> 00:26:37,280 to living underground. 413 00:26:37,280 --> 00:26:40,040 They don't actually require a lot of food at all from us. 414 00:26:40,040 --> 00:26:43,800 And we, in comparison, would feed another rodent group - 415 00:26:43,800 --> 00:26:46,280 so our mice or rats - four times the amount of food 416 00:26:46,280 --> 00:26:49,680 and that's because these guys have a really low metabolic rate. 417 00:26:49,680 --> 00:26:53,720 So, they don't need the same amount of energy as another type of rodent 418 00:26:53,720 --> 00:26:56,840 and that's because they actually dig their burrows in the perfect 419 00:26:56,840 --> 00:27:02,280 position from the sun to help regulate their body temperature. 420 00:27:02,280 --> 00:27:06,120 When it comes to tunnelling, naked mole-rats know pretty much every 421 00:27:06,120 --> 00:27:07,560 trick in the trade. 422 00:27:07,560 --> 00:27:10,920 The bunkers they build are truly brilliant. 423 00:27:10,920 --> 00:27:13,040 As a measure of their success, 424 00:27:13,040 --> 00:27:18,520 consider that, down here, these animals live for up to 30 years, 425 00:27:18,520 --> 00:27:23,200 decades longer than a rodent of similar size on the surface. 426 00:27:23,200 --> 00:27:26,840 For naked mole-rats, going underground might have been the best 427 00:27:26,840 --> 00:27:29,120 decision they ever made. 428 00:27:29,120 --> 00:27:33,400 These guys are super intelligent in terms of their social structures. 429 00:27:33,400 --> 00:27:36,360 Considering they're small mammals that live in a hole in the ground, 430 00:27:36,360 --> 00:27:38,320 they're incredibly complex. 431 00:27:47,800 --> 00:27:50,920 Digging holes underground is an intensely practical 432 00:27:50,920 --> 00:27:54,680 and successful way of building yourself out of trouble, 433 00:27:54,680 --> 00:27:57,040 but it's not very visually appealing, is it? 434 00:27:57,040 --> 00:28:00,760 You see, in the human world, architecture is all about artistic 435 00:28:00,760 --> 00:28:04,960 expression and aesthetic appeal as it is form and function. 436 00:28:04,960 --> 00:28:08,480 Just look at the roof on this building - that green roof, 437 00:28:08,480 --> 00:28:11,800 the way it melds into the environment here. 438 00:28:11,800 --> 00:28:13,360 Amazing. 439 00:28:13,360 --> 00:28:17,080 But there are other animals that are interested in aesthetics, too - 440 00:28:17,080 --> 00:28:20,160 particularly when it comes to finding a mate - 441 00:28:20,160 --> 00:28:23,720 then they have to craft things of exquisite beauty. 442 00:28:32,520 --> 00:28:37,120 Making a home with a partner is never a straightforward business... 443 00:28:39,560 --> 00:28:42,800 ..and, deep in the forest of New Guinea, one bird 444 00:28:42,800 --> 00:28:45,240 has really got his work cut out. 445 00:28:54,600 --> 00:28:59,480 This incredible structure is the creation of a Vogelkop bowerbird - 446 00:28:59,480 --> 00:29:03,120 a male one, to be precise - and it's not a house 447 00:29:03,120 --> 00:29:06,400 but one of very few structures in the animal kingdom built 448 00:29:06,400 --> 00:29:08,240 to attract females, 449 00:29:08,240 --> 00:29:12,480 a unique building designed entirely for mating purposes. 450 00:29:13,520 --> 00:29:18,360 Vogelkop bowerbirds build maypole bowers, elaborate structures 451 00:29:18,360 --> 00:29:22,440 up to two metres across that can take ten months to build 452 00:29:22,440 --> 00:29:23,880 and years to perfect. 453 00:29:25,280 --> 00:29:28,280 Once constructed, the birds decorate. 454 00:29:28,280 --> 00:29:33,000 Moss lines the floor and bowers are adorned with an array of sculptural 455 00:29:33,000 --> 00:29:34,760 and colourful ornaments. 456 00:29:37,880 --> 00:29:42,320 Vogelkops are one of around 20 bowerbird species that build 457 00:29:42,320 --> 00:29:45,480 a variety of architecturally elaborate structures 458 00:29:45,480 --> 00:29:47,600 to attract a mate, 459 00:29:47,600 --> 00:29:50,680 and the skill, and the attention to detail 460 00:29:50,680 --> 00:29:53,800 the birds display, is remarkable. 461 00:29:55,560 --> 00:29:59,400 But, when it comes to attracting certain female bowerbirds, 462 00:29:59,400 --> 00:30:02,640 a good-looking bower will only get you so far. 463 00:30:05,920 --> 00:30:08,160 Let's take a short hop over the water, 464 00:30:08,160 --> 00:30:10,400 from New Guinea to mainland Australia... 465 00:30:13,520 --> 00:30:17,280 ..where another bowerbird species is capable of building 466 00:30:17,280 --> 00:30:21,920 an optical illusion that tricks females into becoming their mates. 467 00:30:25,640 --> 00:30:27,240 I've been baking. 468 00:30:27,240 --> 00:30:29,840 If you believe that, you'll believe anything, 469 00:30:29,840 --> 00:30:30,920 but I do like cakes. 470 00:30:30,920 --> 00:30:34,120 Look at these two cupcakes that we've got here. 471 00:30:34,120 --> 00:30:37,600 Forced perspective is a type of optical illusion 472 00:30:37,600 --> 00:30:42,000 that can make objects seem bigger, smaller, closer or further away. 473 00:30:42,000 --> 00:30:45,920 It's a visual manipulation between scaled objects 474 00:30:45,920 --> 00:30:49,120 and the correlation of their position 475 00:30:49,120 --> 00:30:52,560 relative to the spectator, which sounds very, very complicated. 476 00:30:52,560 --> 00:30:58,720 What it means is that we can make small things, like this cupcake, 477 00:30:58,720 --> 00:31:01,920 look as large as large things, 478 00:31:01,920 --> 00:31:04,000 like this cupcake. 479 00:31:04,000 --> 00:31:05,240 Pretty clever. 480 00:31:05,240 --> 00:31:08,720 But then we are not the only species practising this trick, are we? 481 00:31:08,720 --> 00:31:12,240 It's exactly what these great bowerbirds are doing. 482 00:31:12,240 --> 00:31:16,400 When they create their bower, they make a courtyard outside, 483 00:31:16,400 --> 00:31:19,440 called the gesso, normally out of small, white stones, 484 00:31:19,440 --> 00:31:23,120 and they deliberately choose to put the smaller stones 485 00:31:23,120 --> 00:31:25,560 closer to the exit of the bower, 486 00:31:25,560 --> 00:31:28,200 and the larger stones further away, 487 00:31:28,200 --> 00:31:31,400 generating that form of forced perspective. 488 00:31:34,280 --> 00:31:36,480 They tempt the female into the bower. 489 00:31:36,480 --> 00:31:39,560 She stops at a very particular spot, 490 00:31:39,560 --> 00:31:42,920 and then the male dashes to one side and throws objects 491 00:31:42,920 --> 00:31:46,280 across this screen that he's made to titillate her - 492 00:31:46,280 --> 00:31:48,680 and it does. It visually stimulates her, 493 00:31:48,680 --> 00:31:53,080 and the longer she stays in that bower, the greater the chance 494 00:31:53,080 --> 00:31:55,840 he has of mating with her. 495 00:31:55,840 --> 00:31:57,000 What about that? 496 00:31:57,000 --> 00:32:01,280 If you thought we were being clever with these cupcakes, 497 00:32:01,280 --> 00:32:03,920 you've got to take your hat off to the bowerbird. 498 00:32:06,200 --> 00:32:08,720 By building a stage for his performance, 499 00:32:08,720 --> 00:32:14,400 the male great bowerbird effectively cons females into mating with him 500 00:32:14,400 --> 00:32:16,400 and, after falling for his trick, 501 00:32:16,400 --> 00:32:20,240 it's the female bowerbirds that end up building the nest. 502 00:32:25,840 --> 00:32:29,040 Birds' nests are probably one of the most recognised 503 00:32:29,040 --> 00:32:31,320 built animal structures on the planet 504 00:32:31,320 --> 00:32:34,800 and, when it comes to studying them, we're truly spoilt for choice. 505 00:32:37,360 --> 00:32:39,960 As one of the widest-ranging groups of animals, 506 00:32:39,960 --> 00:32:44,960 birds are also the most versatile and varied of builders. 507 00:32:44,960 --> 00:32:49,040 Birds build nests in virtually every habitat they occupy. 508 00:32:50,480 --> 00:32:53,080 When a new island arises from the sea, 509 00:32:53,080 --> 00:32:55,120 they're the first on the scene. 510 00:32:55,120 --> 00:32:59,560 In some places, they're the only animals to live and breed there. 511 00:33:00,840 --> 00:33:04,840 The sheer diversity of structures they build is astonishing 512 00:33:04,840 --> 00:33:07,280 and attention to detail staggering. 513 00:33:10,320 --> 00:33:13,800 Yes, when compared to treehouses we build, 514 00:33:13,800 --> 00:33:16,600 birds really do put us to shame. 515 00:33:18,880 --> 00:33:21,160 There's no doubt, I suppose, that the very best 516 00:33:21,160 --> 00:33:26,200 of the arboreal architects are birds and their nest. 517 00:33:26,200 --> 00:33:31,880 This beautiful little cup was woven by a goldfinch 518 00:33:31,880 --> 00:33:35,920 and you can see it's used twigs to make the initial part of that cup. 519 00:33:35,920 --> 00:33:38,080 It's then lined it with hair 520 00:33:38,080 --> 00:33:41,240 and finally sheep's wool, 521 00:33:41,240 --> 00:33:45,480 then it's covered the outside with moss to camouflage it. 522 00:33:45,480 --> 00:33:46,960 It's exquisite. 523 00:33:46,960 --> 00:33:51,200 But what can a beautiful bird's nest like this tell us 524 00:33:51,200 --> 00:33:54,200 about the intelligence of the animal that builds it? 525 00:34:00,480 --> 00:34:03,840 We're talking now about animals that have a bill and feet, 526 00:34:03,840 --> 00:34:09,040 and they are building structures that sometimes look 527 00:34:09,040 --> 00:34:12,520 remarkably like something a human might have made. 528 00:34:12,520 --> 00:34:14,960 Professor Sue Healy is convinced 529 00:34:14,960 --> 00:34:17,560 the bird brains behind these structures 530 00:34:17,560 --> 00:34:20,880 have to perform some quite complex decision-making. 531 00:34:22,160 --> 00:34:26,600 I think nest building poses a bunch of problems for the builder. 532 00:34:27,920 --> 00:34:32,520 The bird has to decide what is an appropriate place, 533 00:34:32,520 --> 00:34:35,880 and is that in a bush, in a tree, on the ground? 534 00:34:35,880 --> 00:34:39,920 Then it has to find appropriate materials. 535 00:34:39,920 --> 00:34:42,600 How does it know what materials are appropriate? 536 00:34:42,600 --> 00:34:45,000 Then it has to be able to transport those materials, 537 00:34:45,000 --> 00:34:47,440 so they can't be too heavy, for example. 538 00:34:50,280 --> 00:34:54,120 Then the animal has to put them together and end up with a structure 539 00:34:54,120 --> 00:34:57,400 into which either they, or their partner, can lay eggs 540 00:34:57,400 --> 00:34:58,600 and the eggs won't fall out. 541 00:35:00,640 --> 00:35:03,120 Incredibly, whatever the shape, 542 00:35:03,120 --> 00:35:08,000 material or location of the nest, each one is expertly designed 543 00:35:08,000 --> 00:35:10,800 and built to safely incubate eggs 544 00:35:10,800 --> 00:35:13,440 and eventually house chicks. 545 00:35:13,440 --> 00:35:16,520 So, is this all done simply by instinct, 546 00:35:16,520 --> 00:35:19,120 or do birds learn on the job? 547 00:35:20,360 --> 00:35:24,080 Working with zebra finches in experimental conditions, 548 00:35:24,080 --> 00:35:25,800 Sue had already established a link 549 00:35:25,800 --> 00:35:28,960 between the amount of building material used in a nest 550 00:35:28,960 --> 00:35:33,600 and the success the parents then had in raising chicks. 551 00:35:33,600 --> 00:35:37,400 Birds that had built a successful nest first time 552 00:35:37,400 --> 00:35:41,080 built the same nest when they built their second nest. 553 00:35:41,080 --> 00:35:45,760 Birds that had not been successful with their first nest 554 00:35:45,760 --> 00:35:49,440 put more material into their second nest. 555 00:35:49,440 --> 00:35:53,040 And that gives us an insight into the finch's brain. 556 00:35:54,880 --> 00:36:01,160 This is evidence that birds learn and remember their own experiences, 557 00:36:01,160 --> 00:36:05,000 and use that information to make then later decisions. 558 00:36:06,520 --> 00:36:11,600 Proving birds were learning to build better nests was a revelation. 559 00:36:13,760 --> 00:36:18,640 So Sue carried out a second test to find out if birds preferred 560 00:36:18,640 --> 00:36:21,320 to use one material over another. 561 00:36:21,320 --> 00:36:24,320 In the wild, birds build with everything, 562 00:36:24,320 --> 00:36:27,360 from mud, to sticks, to grass, 563 00:36:27,360 --> 00:36:29,880 and even their own spit, 564 00:36:29,880 --> 00:36:33,280 and often nests are superbly camouflaged, 565 00:36:33,280 --> 00:36:37,520 so Sue devised a clever experiment to see if birds could be flexible 566 00:36:37,520 --> 00:36:40,160 in their choice of building material. 567 00:36:40,160 --> 00:36:42,120 So we went to the lab, 568 00:36:42,120 --> 00:36:43,840 again, with zebra finches, 569 00:36:43,840 --> 00:36:47,520 and we asked zebra finches to build in their cages. 570 00:36:47,520 --> 00:36:52,400 Then we papered the wall of their cage and the box that they build in 571 00:36:52,400 --> 00:36:54,800 a particular colour 572 00:36:54,800 --> 00:36:58,680 and then we gave our zebra finches paper that was of the same colour 573 00:36:58,680 --> 00:37:01,080 as the wallpaper in their cage, 574 00:37:01,080 --> 00:37:04,560 and paper that was of a different colour. 575 00:37:05,640 --> 00:37:08,200 And the birds didn't disappoint. 576 00:37:08,200 --> 00:37:12,080 In almost every case, the birds decided to build their nests 577 00:37:12,080 --> 00:37:16,120 out of materials that matched the colour of the nest box. 578 00:37:16,120 --> 00:37:20,000 Sue had provided some of the very first experimental evidence 579 00:37:20,000 --> 00:37:22,640 that birds were building with materials 580 00:37:22,640 --> 00:37:25,600 specifically to match their surroundings 581 00:37:25,600 --> 00:37:28,920 and that nest building isn't simply hard-wired. 582 00:37:30,320 --> 00:37:35,200 So, although there will be a considerable genetic component 583 00:37:35,200 --> 00:37:37,240 to nest building in birds, 584 00:37:37,240 --> 00:37:39,880 increasingly we have evidence 585 00:37:39,880 --> 00:37:43,840 that almost all aspects of building 586 00:37:43,840 --> 00:37:45,560 comes from their own experience 587 00:37:45,560 --> 00:37:48,840 and nest building is heavily dependent 588 00:37:48,840 --> 00:37:51,080 on the bird's cognitive abilities. 589 00:37:53,720 --> 00:37:56,560 Sue's work is fascinating. 590 00:37:56,560 --> 00:37:58,600 Confirmation, if it were needed, 591 00:37:58,600 --> 00:38:02,640 that nests are deceptively complex structures, 592 00:38:02,640 --> 00:38:05,120 but also that the architects behind them 593 00:38:05,120 --> 00:38:09,080 are far from the bird brains we once took them for. 594 00:38:09,080 --> 00:38:11,800 Her findings certainly cast a new light 595 00:38:11,800 --> 00:38:13,480 on one of my favourites. 596 00:38:14,640 --> 00:38:20,120 This is the nest that belonged to a pair of long-tailed tits 597 00:38:20,120 --> 00:38:23,560 and, unbelievably, it's woven out of spider silk. 598 00:38:25,000 --> 00:38:29,080 You see, they will lay ten or more eggs inside the nest 599 00:38:29,080 --> 00:38:32,440 and, when their young are growing, they increase in volume, 600 00:38:32,440 --> 00:38:35,520 and this nest is flexible, it's pliable, 601 00:38:35,520 --> 00:38:40,160 so it expands to cope with all of those young birds inside, 602 00:38:40,160 --> 00:38:42,840 and, to keep those eggs warm, and the youngsters warm, 603 00:38:42,840 --> 00:38:48,320 it's also lined with sometimes more than a thousand feathers 604 00:38:48,320 --> 00:38:51,440 that these birds find in their environment. 605 00:38:51,440 --> 00:38:55,200 They cover the outside, using that sticky spider silk, 606 00:38:55,200 --> 00:38:59,440 with moss, and also lichen, so that, when the nest is pressed 607 00:38:59,440 --> 00:39:02,160 up against a tree, or hidden in a bush, 608 00:39:02,160 --> 00:39:06,000 it's almost completely camouflaged. 609 00:39:06,000 --> 00:39:09,640 What a remarkable thing that is. 610 00:39:09,640 --> 00:39:14,120 Remarkable, although you might say, in some ways, 611 00:39:14,120 --> 00:39:16,640 maybe a little bit tatty at the same time. 612 00:39:16,640 --> 00:39:20,600 But then there are other species of animals that produce their homes 613 00:39:20,600 --> 00:39:24,080 with architectural, even mathematical, precision. 614 00:39:28,760 --> 00:39:30,840 When you're constructing in the human world, 615 00:39:30,840 --> 00:39:33,520 precision is everything. 616 00:39:33,520 --> 00:39:36,080 Being out by a fraction of a centimetre, 617 00:39:36,080 --> 00:39:40,560 as any budding DIY enthusiast can testify, can be... 618 00:39:42,160 --> 00:39:43,800 ..disastrous. 619 00:39:47,640 --> 00:39:51,280 For bees, however, pinpoint precision comes naturally. 620 00:39:54,200 --> 00:39:58,120 You probably know that bees build using hexagonal cells 621 00:39:58,120 --> 00:40:00,240 to form honeycomb. 622 00:40:00,240 --> 00:40:04,920 The cells are mostly built horizontally, along the long axis. 623 00:40:04,920 --> 00:40:07,360 The top and bottom remain parallel. 624 00:40:07,360 --> 00:40:11,840 But what's really clever is that, to prevent honey spillage, 625 00:40:11,840 --> 00:40:18,120 the bees engineer the cells to pitch between nine and 14 degrees. 626 00:40:18,120 --> 00:40:20,520 As natural masters of geometry, 627 00:40:20,520 --> 00:40:22,600 bees can replicate this design 628 00:40:22,600 --> 00:40:25,440 to within half a millimetre of accuracy 629 00:40:25,440 --> 00:40:29,280 thousands and thousands and thousands of times. 630 00:40:31,320 --> 00:40:35,080 What's more, the wax the bees use to build these cells 631 00:40:35,080 --> 00:40:39,960 is antibacterial, antifungal and waterproof. 632 00:40:39,960 --> 00:40:41,920 As building materials go, 633 00:40:41,920 --> 00:40:44,560 beeswax is the bee's knees. 634 00:40:46,160 --> 00:40:49,320 Not only that, but the shape of the bees' cells 635 00:40:49,320 --> 00:40:50,960 measures up perfectly, too. 636 00:40:53,680 --> 00:40:57,520 As well as being spatially efficient, 637 00:40:57,520 --> 00:41:00,200 hexagonal honeycomb is also materially efficient. 638 00:41:00,200 --> 00:41:03,240 This is something that's known as "the honeycomb conjecture", 639 00:41:03,240 --> 00:41:06,160 a phenomena that's been recognised for thousands of years 640 00:41:06,160 --> 00:41:10,640 but was only proved mathematically as recently as 1999 - 641 00:41:10,640 --> 00:41:14,920 and it's all to do with spatial and material efficiency. 642 00:41:14,920 --> 00:41:16,360 Now, imagine you're a bee 643 00:41:16,360 --> 00:41:20,480 and you want to pack as many cells into your nest as you possibly can. 644 00:41:20,480 --> 00:41:23,920 Well, you wouldn't go down the circular route, would you? 645 00:41:23,920 --> 00:41:27,000 Look at all this dead space in-between them here. 646 00:41:27,000 --> 00:41:29,440 Basically, you're left with three choices. 647 00:41:29,440 --> 00:41:32,280 You can use squares, triangles, 648 00:41:32,280 --> 00:41:34,720 or, as the bees have done, 649 00:41:34,720 --> 00:41:38,160 you can go for those hexagons. 650 00:41:38,160 --> 00:41:40,800 Now, no good builder wants to waste money on materials 651 00:41:40,800 --> 00:41:42,200 they're not going to use 652 00:41:42,200 --> 00:41:46,480 and it turns out that bees have had it right all along. 653 00:41:46,480 --> 00:41:49,960 They can use the minimum amount of materials 654 00:41:49,960 --> 00:41:54,960 to create the maximum number of cells in any given volume 655 00:41:54,960 --> 00:41:59,480 using hexagons to store their honey. 656 00:41:59,480 --> 00:42:00,480 Remarkable. 657 00:42:05,000 --> 00:42:08,400 Discovering Mother Nature was building more efficiently 658 00:42:08,400 --> 00:42:11,560 has meant we've been quick to steal her best ideas 659 00:42:11,560 --> 00:42:13,400 and claim them as our own. 660 00:42:14,760 --> 00:42:17,400 This is the Eden Project in Cornwall. 661 00:42:17,400 --> 00:42:21,560 Here, designers have opted for the same hexagons as the bees, 662 00:42:21,560 --> 00:42:24,280 making this building not only beautiful 663 00:42:24,280 --> 00:42:26,720 but also materially efficient 664 00:42:26,720 --> 00:42:30,160 in that the air contained within it weighs about the same 665 00:42:30,160 --> 00:42:32,600 as the structure itself. 666 00:42:32,600 --> 00:42:34,200 Stealing ideas from nature 667 00:42:34,200 --> 00:42:37,600 and using them in buildings of our own is nothing new, 668 00:42:37,600 --> 00:42:39,720 we've been doing it for centuries, 669 00:42:39,720 --> 00:42:41,240 but it's only recently, 670 00:42:41,240 --> 00:42:44,400 where new technology has allowed us to look at nature 671 00:42:44,400 --> 00:42:47,040 in intricate detail, that we've realised 672 00:42:47,040 --> 00:42:50,640 just how ingenious animal builders are. 673 00:42:50,640 --> 00:42:52,840 So, rather than call it stealing, 674 00:42:52,840 --> 00:42:57,120 we prefer to call our copycat construction "biomimicry". 675 00:43:00,080 --> 00:43:02,920 Biomimicry is essentially a design inspired by nature, 676 00:43:02,920 --> 00:43:05,880 so it's looking at solutions in the natural world 677 00:43:05,880 --> 00:43:08,800 and learning from those to design better buildings, 678 00:43:08,800 --> 00:43:11,440 better cities, better products. 679 00:43:11,440 --> 00:43:14,840 Michael Pawlyn is one of the team that designed the Eden Project. 680 00:43:17,120 --> 00:43:21,120 For him, the natural world has plenty more ideas out there 681 00:43:21,120 --> 00:43:22,360 for us to plunder. 682 00:43:25,440 --> 00:43:28,000 You could look at nature as like a design source book, 683 00:43:28,000 --> 00:43:31,400 in which all the products have benefited from a 3.5-billion-year 684 00:43:31,400 --> 00:43:33,360 research and development period 685 00:43:33,360 --> 00:43:36,000 and, to make things even better, all the faulty products 686 00:43:36,000 --> 00:43:38,200 have been withdrawn from the marketplace. 687 00:43:38,200 --> 00:43:41,680 And, of course, what I'm referring to is this long and ruthless process 688 00:43:41,680 --> 00:43:45,960 of evolution that has resulted in some really amazing solutions 689 00:43:45,960 --> 00:43:49,800 amongst the plants and animals and other organisms that exist today. 690 00:43:51,640 --> 00:43:54,280 When you're designing a building, there are lots of functional 691 00:43:54,280 --> 00:43:56,120 challenges that you are trying to address. 692 00:43:56,120 --> 00:43:58,680 You're trying to make an efficient, beautiful structure, 693 00:43:58,680 --> 00:44:01,760 you're trying to use fewer material resources, 694 00:44:01,760 --> 00:44:03,400 you're trying to keep warm and cool, 695 00:44:03,400 --> 00:44:05,760 sometimes you're trying to harvest water, 696 00:44:05,760 --> 00:44:07,240 and, for all of those, 697 00:44:07,240 --> 00:44:11,520 you can find an amazing array of existing solutions in biology, 698 00:44:11,520 --> 00:44:15,400 and, often, you can learn from those to design better solutions 699 00:44:15,400 --> 00:44:17,960 that do that far better than we've ever done them before. 700 00:44:21,280 --> 00:44:24,520 With the environmental impact of building now at the forefront 701 00:44:24,520 --> 00:44:26,160 of many designers' minds, 702 00:44:26,160 --> 00:44:30,280 looking to nature for solutions has never been more important... 703 00:44:34,400 --> 00:44:37,720 ..and inspiration can come from pretty much anywhere. 704 00:44:45,240 --> 00:44:48,920 The world is literally an architect's oyster, 705 00:44:48,920 --> 00:44:51,480 or, in this case, abalone shell. 706 00:44:54,400 --> 00:44:57,640 We know, from the microstructure of abalone, 707 00:44:57,640 --> 00:45:01,120 that it's made out of very thin layers of tiles, 708 00:45:01,120 --> 00:45:04,320 essentially, that are built up, and, at a chemical level, 709 00:45:04,320 --> 00:45:07,600 that is almost identical to ordinary blackboard chalk. 710 00:45:07,600 --> 00:45:10,000 But, because of the microstructure, 711 00:45:10,000 --> 00:45:13,280 it achieves roughly 3,000 times the strength, 712 00:45:13,280 --> 00:45:16,560 and we've learned from that to design a house. 713 00:45:16,560 --> 00:45:20,600 So this is an early concept model of the abalone house 714 00:45:20,600 --> 00:45:22,040 that we're working on. 715 00:45:22,040 --> 00:45:26,440 We've learned from the curved forms of shells to make that a stiff form. 716 00:45:26,440 --> 00:45:29,960 So this is going to be built out of very thin layers of tiles, 717 00:45:29,960 --> 00:45:32,000 and, by doing that, we can design a house 718 00:45:32,000 --> 00:45:35,000 that uses about half the amount of materials of a conventional house. 719 00:45:42,560 --> 00:45:45,640 This is just one of my favourite examples. This is a glass sponge 720 00:45:45,640 --> 00:45:50,040 and this animal has evolved to make these wonderfully elegant structures 721 00:45:50,040 --> 00:45:52,040 out of glass fibre 722 00:45:52,040 --> 00:45:54,920 and, if you look at this under a magnifying glass, you can see 723 00:45:54,920 --> 00:45:57,160 that it's incredibly elegant, you know, 724 00:45:57,160 --> 00:46:00,840 these really, really thin fibres, and then cross-bracing. 725 00:46:00,840 --> 00:46:04,080 It's like the most elegant bit of engineering you've ever seen, 726 00:46:04,080 --> 00:46:07,720 and, as architects, you know, we could learn from examples 727 00:46:07,720 --> 00:46:11,400 like this to design buildings that are just far more lightweight, 728 00:46:11,400 --> 00:46:14,360 far more efficient, and, I think, far more beautiful. 729 00:46:16,640 --> 00:46:19,600 The Davies Alpine House, here at Kew Gardens, 730 00:46:19,600 --> 00:46:23,840 might look as futuristic as it gets for a greenhouse. 731 00:46:23,840 --> 00:46:27,400 Nonetheless, inspiration for its design actually came from 732 00:46:27,400 --> 00:46:29,480 ideas perfected in nature 733 00:46:29,480 --> 00:46:32,680 long before humans were even on the scene. 734 00:46:32,680 --> 00:46:35,640 So, here we are, in the Alpine House at Kew Gardens, 735 00:46:35,640 --> 00:46:38,600 and Alpine plants need a lot of light. 736 00:46:38,600 --> 00:46:40,400 They also need to be cool. 737 00:46:40,400 --> 00:46:43,240 Now, obviously, you could do that by just using loads of energy 738 00:46:43,240 --> 00:46:44,640 and air conditioning, 739 00:46:44,640 --> 00:46:46,920 but what I love about biomimicry is that it points to 740 00:46:46,920 --> 00:46:49,600 much more ingenious ways of solving those problems, 741 00:46:49,600 --> 00:46:53,600 and, here, the architects and engineers studied termites. 742 00:46:53,600 --> 00:46:56,000 Termites worked this out thousands of years ago. 743 00:46:56,000 --> 00:46:58,400 Their mounds extend down into the ground 744 00:46:58,400 --> 00:47:01,560 and they benefit from the steady temperature below the ground. 745 00:47:01,560 --> 00:47:03,160 That's exactly what's going on here. 746 00:47:03,160 --> 00:47:04,800 So, you can see these pipes. 747 00:47:04,800 --> 00:47:07,880 Those are drawing cool air up from the basement, 748 00:47:07,880 --> 00:47:09,680 which is like a labyrinth of walls, 749 00:47:09,680 --> 00:47:13,120 and that's what keeps the building cool. 750 00:47:13,120 --> 00:47:15,160 So it's controlling the temperature, 751 00:47:15,160 --> 00:47:18,400 but with an absolute fraction of the energy of conventional approaches. 752 00:47:23,480 --> 00:47:26,320 Yes, biomimicry has a lot to offer 753 00:47:26,320 --> 00:47:31,200 and termites alone are turning out to be a mine of inspiration. 754 00:47:33,440 --> 00:47:36,080 Up to 3,000 species of termites are found 755 00:47:36,080 --> 00:47:38,720 on all continents except Antarctica. 756 00:47:41,200 --> 00:47:44,200 Interestingly, not all of them build towers, 757 00:47:44,200 --> 00:47:48,680 but, in the hot savannahs of Africa, and prairies of Asia and Australia, 758 00:47:48,680 --> 00:47:52,400 these structures can be found in their millions. 759 00:47:52,400 --> 00:47:56,400 The relative scale of these constructions is jaw-dropping. 760 00:47:57,520 --> 00:47:59,040 In proportion to humans, 761 00:47:59,040 --> 00:48:03,320 these tiny animals are building structures that are over four times 762 00:48:03,320 --> 00:48:06,000 the height of our tallest ever skyscraper, 763 00:48:06,000 --> 00:48:08,840 the Burj Khalifa in Dubai, 764 00:48:08,840 --> 00:48:12,320 and, remember, they're doing this with no plans, 765 00:48:12,320 --> 00:48:15,040 using nothing other than mud and water. 766 00:48:18,240 --> 00:48:22,600 Termites build big and now there are some brand-new theories 767 00:48:22,600 --> 00:48:26,040 on the functions of these colossal towers, 768 00:48:26,040 --> 00:48:29,480 and, to help me explain one of them, I need a goat. 769 00:48:31,120 --> 00:48:32,760 Yep, I'm not kidding. 770 00:48:36,360 --> 00:48:39,440 Like most species of animals, termites breathe... 771 00:48:41,280 --> 00:48:44,200 ..utilising oxygen, and producing CO2, 772 00:48:44,200 --> 00:48:48,200 but, in the case of these insects living in a large colony, 773 00:48:48,200 --> 00:48:51,120 it's not just the individuals that are breathing, 774 00:48:51,120 --> 00:48:54,320 or that colony of insects, it's their food, too, 775 00:48:54,320 --> 00:48:57,680 because many species of termite farm fungus. 776 00:48:57,680 --> 00:49:00,360 They feed it grass and other organic material, 777 00:49:00,360 --> 00:49:03,800 and it respires, producing a huge quantity of CO2, 778 00:49:03,800 --> 00:49:06,880 enough to suffocate the entire colony, 779 00:49:06,880 --> 00:49:08,920 and what scientists have actually learned 780 00:49:08,920 --> 00:49:12,160 is that the average termite colony respires the same amount 781 00:49:12,160 --> 00:49:14,800 in every day as a goat. 782 00:49:14,800 --> 00:49:17,840 I know it's a pretty arbitrary measurement, 783 00:49:17,840 --> 00:49:20,080 but it's allegedly true. 784 00:49:20,080 --> 00:49:23,960 What's remarkable is that this inert body, the mound, 785 00:49:23,960 --> 00:49:29,240 can exchange that CO2 stale air, from the bottom of the colony, 786 00:49:29,240 --> 00:49:34,120 with nice, fresh, oxygen-rich air at the top. 787 00:49:34,120 --> 00:49:36,760 It's not only keeping those termites cool, 788 00:49:36,760 --> 00:49:39,120 it's acting as their lungs. 789 00:49:39,120 --> 00:49:42,840 It's actually breathing for them, which is fantastic. 790 00:49:46,960 --> 00:49:49,840 With air purification, temperature control, 791 00:49:49,840 --> 00:49:52,760 and no doubt many other built-in mound functions 792 00:49:52,760 --> 00:49:54,480 waiting to be discovered, 793 00:49:54,480 --> 00:49:56,280 termites are undoubtedly 794 00:49:56,280 --> 00:49:59,600 one of the most accomplished animal builders out there. 795 00:50:00,840 --> 00:50:03,520 As far as brilliant builders go, 796 00:50:03,520 --> 00:50:06,000 it's going to take a lot to top a termite. 797 00:50:08,880 --> 00:50:13,360 All of the animals we've featured so far are there on merit 798 00:50:13,360 --> 00:50:16,560 and, I have to say, I'm not surprised scientists, 799 00:50:16,560 --> 00:50:21,640 engineers and architects are now looking to nature for inspiration. 800 00:50:21,640 --> 00:50:25,520 But we mustn't overlook our own building prowess, 801 00:50:25,520 --> 00:50:30,680 and, unsurprisingly, our brains have given us a head start. 802 00:50:34,240 --> 00:50:37,880 There's a compelling argument to be made that humans are the most 803 00:50:37,880 --> 00:50:41,360 intelligent of all builders and, when you think about it, 804 00:50:41,360 --> 00:50:44,360 we put up the largest artificial structures, 805 00:50:44,360 --> 00:50:46,280 both on and off of our planet. 806 00:50:49,880 --> 00:50:52,920 And even the simplest buildings allowed us to move away 807 00:50:52,920 --> 00:50:55,440 from the plains of Africa, where we evolved, 808 00:50:55,440 --> 00:50:59,240 and dwell in the most inhospitable parts of the planet. 809 00:50:59,240 --> 00:51:03,480 So what gave us the increased intelligence to build better? 810 00:51:08,200 --> 00:51:11,160 Well, the key is sleep, 811 00:51:11,160 --> 00:51:12,800 or at least it will be, 812 00:51:12,800 --> 00:51:17,960 if I can get to grips with this particularly intelligent building. 813 00:51:17,960 --> 00:51:20,720 I've never been fond of hammocks, I've got to say. 814 00:51:20,720 --> 00:51:22,760 Oh! Oh, my goodness me. 815 00:51:22,760 --> 00:51:24,560 Oh! 816 00:51:24,560 --> 00:51:25,840 HE SIGHS 817 00:51:28,480 --> 00:51:33,560 For us, a good night's kip often boils down to the beds we sleep in 818 00:51:33,560 --> 00:51:39,120 and we are not the only animals building structures for a snooze. 819 00:51:39,120 --> 00:51:43,080 Well, one of the primary challenges of any organism on this planet 820 00:51:43,080 --> 00:51:47,000 is to be able to figure out how to sleep safely and comfortably, 821 00:51:47,000 --> 00:51:50,280 because sleep inherently is a very vulnerable activity. 822 00:51:50,280 --> 00:51:52,800 When you're asleep, you're vulnerable to predation, 823 00:51:52,800 --> 00:51:54,680 you're vulnerable to inclement weather, 824 00:51:54,680 --> 00:51:57,000 you're vulnerable to lots of different challenges 825 00:51:57,000 --> 00:51:58,920 in your environment. 826 00:51:58,920 --> 00:52:00,600 David Samson is a professor, 827 00:52:00,600 --> 00:52:03,200 studying the influence sleep has had 828 00:52:03,200 --> 00:52:05,960 on the evolution of human intelligence. 829 00:52:05,960 --> 00:52:07,680 He believes that sleeping platforms 830 00:52:07,680 --> 00:52:10,280 built by some of our closest living relatives 831 00:52:10,280 --> 00:52:12,160 might hold a vital clue 832 00:52:12,160 --> 00:52:16,400 to explaining our own advanced building ability. 833 00:52:16,400 --> 00:52:21,480 Great apes, bonobos, chimpanzees, gorillas and orangutans, 834 00:52:21,480 --> 00:52:23,720 they build what's called a nest - 835 00:52:23,720 --> 00:52:28,000 these are essentially tree beds - and no other primate does this. 836 00:52:28,000 --> 00:52:31,040 Even large-bodied monkeys or large-brained monkeys, 837 00:52:31,040 --> 00:52:33,120 they'll all sleep prostrate out on a tree. 838 00:52:33,120 --> 00:52:36,920 Great apes will climb up 12, 13 metres into the canopy 839 00:52:36,920 --> 00:52:40,120 and they will physically manipulate a sleeping environment 840 00:52:40,120 --> 00:52:43,080 by breaking a few frame-supporting branches together, 841 00:52:43,080 --> 00:52:46,200 interweaving them, in a way that allows for them 842 00:52:46,200 --> 00:52:48,480 to have safe, secure sleep up in the canopy. 843 00:52:50,000 --> 00:52:52,760 Though they're called nests, these structures 844 00:52:52,760 --> 00:52:56,360 are more like hammocks and constructing one strong enough 845 00:52:56,360 --> 00:53:00,040 to support 100kg of great ape is no mean feat... 846 00:53:01,080 --> 00:53:05,080 ..yet this is something most great apes will do every night. 847 00:53:08,000 --> 00:53:12,440 Building a bed to sleep in really is environmental problem solving 848 00:53:12,440 --> 00:53:13,960 of the highest order. 849 00:53:13,960 --> 00:53:18,720 Being up off the forest floor not only keeps apes safe from predators, 850 00:53:18,720 --> 00:53:23,440 but it's been proven to keep them warmer and even stave off insects. 851 00:53:24,640 --> 00:53:27,680 Their structures are almost as complex as a shelter 852 00:53:27,680 --> 00:53:29,760 a human might make. 853 00:53:29,760 --> 00:53:32,400 The apes know how the wood is going to break 854 00:53:32,400 --> 00:53:35,720 and they understand how strong the bed needs to be. 855 00:53:35,720 --> 00:53:39,040 Interestingly, they even have a preference for building 856 00:53:39,040 --> 00:53:41,880 with certain tree species. 857 00:53:41,880 --> 00:53:44,840 They are clearly intelligently built, 858 00:53:44,840 --> 00:53:47,440 but it's the brain-boosting capabilities 859 00:53:47,440 --> 00:53:51,160 of these sleeping platforms that really gets David excited. 860 00:53:52,480 --> 00:53:56,040 I would say that there is a baseline level of intelligence 861 00:53:56,040 --> 00:53:59,560 required to build the nest, but I think the more important question 862 00:53:59,560 --> 00:54:01,680 is - does it permit greater intelligence? 863 00:54:01,680 --> 00:54:04,200 And I think the answer to that is actually yes. 864 00:54:04,200 --> 00:54:08,120 These sleeping platforms allow the great apes to go in this deep, 865 00:54:08,120 --> 00:54:10,440 high-quality sleep that then primes them 866 00:54:10,440 --> 00:54:13,200 to face the ecological challenges of the next day, 867 00:54:13,200 --> 00:54:16,920 so I really do think it augments their intelligence 868 00:54:16,920 --> 00:54:19,440 in a way that is rather surprising. 869 00:54:22,000 --> 00:54:25,560 After years of studying these animals building in the wild, 870 00:54:25,560 --> 00:54:29,440 could David prove his theory that makeshift beds built 871 00:54:29,440 --> 00:54:33,840 by great apes were actually making them brainier? 872 00:54:33,840 --> 00:54:38,280 Orangutans are known to construct the most complex sleeping platforms, 873 00:54:38,280 --> 00:54:40,800 packed full of creature comforts, 874 00:54:40,800 --> 00:54:43,640 like pillows, blankets and even roofs. 875 00:54:43,640 --> 00:54:48,560 So David designed an experiment to test these simian sleep specialists 876 00:54:48,560 --> 00:54:50,240 under controlled conditions. 877 00:54:51,800 --> 00:54:54,640 What we did was we manipulated the sleeping environments 878 00:54:54,640 --> 00:54:56,480 that the orangutans were in 879 00:54:56,480 --> 00:54:59,960 and we introduced really high-quality sleeping materials, 880 00:54:59,960 --> 00:55:02,160 like memory foam mattresses 881 00:55:02,160 --> 00:55:05,200 and pillows and sheets and comforters. 882 00:55:05,200 --> 00:55:08,280 And when we gave them this high-quality material, 883 00:55:08,280 --> 00:55:10,280 we recorded their sleep physiology. 884 00:55:10,280 --> 00:55:12,920 We recorded the REM and non-REM and total sleep, 885 00:55:12,920 --> 00:55:15,360 and we found that their sleep was really high quality 886 00:55:15,360 --> 00:55:17,000 when they used these materials. 887 00:55:17,000 --> 00:55:19,160 But we wanted to take it one more step, 888 00:55:19,160 --> 00:55:23,680 so we gave them touch-screen cognitive tasks the very next day 889 00:55:23,680 --> 00:55:26,480 and we discovered that, in fact, the nights where they had the best 890 00:55:26,480 --> 00:55:28,760 access to the highest-quality materials, 891 00:55:28,760 --> 00:55:30,840 they scored the most accurate on these tests. 892 00:55:32,560 --> 00:55:36,120 David had confirmed that the sleeping platforms built 893 00:55:36,120 --> 00:55:40,360 by orangutans were boosting their brain power 894 00:55:40,360 --> 00:55:43,800 and this raised an interesting possibility. 895 00:55:43,800 --> 00:55:49,160 Could the act of building itself be the key to our success as a species, 896 00:55:49,160 --> 00:55:51,920 starting us on a path to become 897 00:55:51,920 --> 00:55:54,360 the best builders on the planet? 898 00:55:54,360 --> 00:55:56,480 For David, there's only one answer. 899 00:55:58,200 --> 00:56:01,040 And I think what we have here with early human evolution 900 00:56:01,040 --> 00:56:05,920 is where early proto-apes were building these sleeping platforms 901 00:56:05,920 --> 00:56:09,400 and, when they did that, they unleashed a watershed event 902 00:56:09,400 --> 00:56:11,480 where they were getting high-quality sleep, 903 00:56:11,480 --> 00:56:14,280 they were getting deeper sleep, they were getting more REM, 904 00:56:14,280 --> 00:56:17,840 and this enhanced their cognitive abilities for their very next day. 905 00:56:17,840 --> 00:56:20,800 They had basically primed their brains 906 00:56:20,800 --> 00:56:23,040 to be successful that following day 907 00:56:23,040 --> 00:56:25,240 and so that could have been a really critical moment 908 00:56:25,240 --> 00:56:26,640 in early human evolution. 909 00:56:28,480 --> 00:56:31,960 Evolution is littered with tipping points 910 00:56:31,960 --> 00:56:33,640 and, where discovering fire 911 00:56:33,640 --> 00:56:36,240 will always play an important role in ours, 912 00:56:36,240 --> 00:56:40,680 it's fascinating to consider that the act of building itself 913 00:56:40,680 --> 00:56:45,120 could be just as significant, setting us on a course 914 00:56:45,120 --> 00:56:48,200 from constructing rudimentary sleeping platforms 915 00:56:48,200 --> 00:56:52,920 to the International Space Station, all within a few million years. 916 00:56:58,360 --> 00:57:01,560 It's amazing to think, isn't it, that the simple nests built 917 00:57:01,560 --> 00:57:05,240 by our evolutionary ancestors may have allowed us to develop 918 00:57:05,240 --> 00:57:08,520 the intelligence to build? 919 00:57:08,520 --> 00:57:10,760 Although, when it comes to the hammock, 920 00:57:10,760 --> 00:57:13,480 I wish someone had put a bit more effort 921 00:57:13,480 --> 00:57:17,440 into a method of dismounting it elegantly. 922 00:57:21,160 --> 00:57:24,320 It's a problem great apes probably solved long ago, 923 00:57:24,320 --> 00:57:26,560 but, hey, nobody's perfect. 924 00:57:27,920 --> 00:57:30,840 Luckily, nature is packed full of inspiration 925 00:57:30,840 --> 00:57:33,280 for us to build better 926 00:57:33,280 --> 00:57:36,920 and, as we've seen, there's a lot we can learn from species 927 00:57:36,920 --> 00:57:40,400 as diverse as beavers, termites, 928 00:57:40,400 --> 00:57:43,240 bees and even prairie dogs. 929 00:57:44,480 --> 00:57:47,840 I wonder which animal will be next on that list. 930 00:57:49,320 --> 00:57:50,920 Maybe the snail. 931 00:57:50,920 --> 00:57:54,320 The snail builds its own home, 932 00:57:54,320 --> 00:57:56,440 doesn't need to pack it up to move. 933 00:57:56,440 --> 00:57:58,680 It avoids all of that stress. 934 00:57:58,680 --> 00:58:00,680 The snail, my money's on that. 935 00:58:05,000 --> 00:58:07,240 But they've got to fix the hammock first. 936 00:58:17,960 --> 00:58:21,520 In the next episode, I'll be exploring the ways that animals 937 00:58:21,520 --> 00:58:24,880 cleverly work together 938 00:58:24,880 --> 00:58:27,440 and how we can learn a thing or two 939 00:58:27,440 --> 00:58:29,800 from their intelligent social networks.