1 00:00:01,835 --> 00:00:05,828 Imagine if you could halt the constant march of time. 2 00:00:11,544 --> 00:00:15,412 ...if you could slow it down... and speed it up. 3 00:00:17,450 --> 00:00:21,716 Imagine if you could stop time... or even reverse it. 4 00:00:23,690 --> 00:00:26,750 The world about us would look quite different. 5 00:00:31,031 --> 00:00:36,901 Imagine no longer... come with us as we go on a journey through time. 6 00:00:42,776 --> 00:00:45,768 Life is a race against the clock. 7 00:00:52,085 --> 00:00:54,451 For all of us, every second of every day 8 00:00:54,654 --> 00:00:57,680 the pressure is on to find food... 9 00:00:58,625 --> 00:01:01,253 ...meet a mate and have a family... 10 00:01:02,729 --> 00:01:04,890 ...all before our time is up. 11 00:01:12,305 --> 00:01:13,670 By speeding through days, 12 00:01:13,873 --> 00:01:15,238 months and years 13 00:01:15,442 --> 00:01:18,002 we're going to see how plants and animals 14 00:01:18,211 --> 00:01:22,113 manipulate time to stay in the running. 15 00:01:29,155 --> 00:01:32,488 Why is it that a mouse lives for two years... 16 00:01:35,361 --> 00:01:37,955 ...while a whale can live for 200? 17 00:01:41,267 --> 00:01:44,634 Why do these crabs have their own little alarm clocks 18 00:01:44,871 --> 00:01:47,499 that must be reset every day? 19 00:01:52,879 --> 00:01:54,506 What drives these caribou 20 00:01:54,714 --> 00:01:56,614 to run thousands of kilometres, 21 00:01:56,816 --> 00:01:59,785 through some of the harshest conditions on earth? 22 00:02:03,456 --> 00:02:08,985 And what has turned this hummingbird into the Pinocchio of the bird world? 23 00:02:12,765 --> 00:02:14,357 It's all down to time. 24 00:02:18,071 --> 00:02:20,596 By crushing centuries into seconds 25 00:02:20,807 --> 00:02:22,172 we'll see life change 26 00:02:22,375 --> 00:02:23,808 beyond recognition 27 00:02:24,010 --> 00:02:26,672 and meet some real time travellers. 28 00:02:39,092 --> 00:02:41,993 But can anything truly cheat time 29 00:02:42,328 --> 00:02:43,488 and live forever? 30 00:02:50,303 --> 00:02:52,965 Different animals have different life spans. 31 00:02:53,173 --> 00:02:54,970 Take a man and his dog. 32 00:02:55,308 --> 00:02:57,936 They both look like they could run and run... 33 00:02:58,278 --> 00:03:01,611 but one of them is already past his prime. 34 00:03:03,716 --> 00:03:05,513 The dog may look full of beans 35 00:03:05,718 --> 00:03:07,208 but it's six years old, 36 00:03:07,487 --> 00:03:11,218 and in dog-years that means well into middle age. 37 00:03:12,759 --> 00:03:14,351 Dogs live to about 12, 38 00:03:14,561 --> 00:03:17,894 whereas we humans now expect to reach 80. 39 00:03:18,164 --> 00:03:19,825 Why do we have these hugely 40 00:03:20,033 --> 00:03:21,864 different life spans? 41 00:03:24,671 --> 00:03:26,696 Even with these creature comforts, 42 00:03:26,906 --> 00:03:30,842 a house mouse will be lucky if it survives till it's two. 43 00:03:31,077 --> 00:03:33,671 Could life span be all down to size? 44 00:03:36,416 --> 00:03:39,385 Of course, a mouse only has to grow a tiny body... 45 00:03:41,788 --> 00:03:43,380 ...but that's not the whole story. 46 00:03:43,590 --> 00:03:46,081 Its short time on earth is also about 47 00:03:46,292 --> 00:03:48,852 staying one step ahead of danger. 48 00:04:01,040 --> 00:04:04,476 A mouse's life is so likely to come to a swift end 49 00:04:04,677 --> 00:04:06,304 that it pays to live life 50 00:04:06,512 --> 00:04:07,809 in the fast lane. 51 00:04:08,581 --> 00:04:11,812 A newborn mouse grows up at break-neck speed. 52 00:04:12,218 --> 00:04:15,847 Within a matter of days the first hair erupts... 53 00:04:16,889 --> 00:04:18,720 Next their body lengthens... 54 00:04:23,796 --> 00:04:24,854 The whiskers grow... 55 00:04:26,366 --> 00:04:28,129 ...and the ears pop out. 56 00:04:30,536 --> 00:04:32,265 A baby mouse turns into an adult 57 00:04:32,472 --> 00:04:34,099 in just FIVE weeks. 58 00:04:34,307 --> 00:04:37,572 Right away it can start having babies of its own. 59 00:04:44,517 --> 00:04:48,009 In its short lifetime, a mouse can have several litters 60 00:04:48,221 --> 00:04:51,088 with up to 12 babies each time. 61 00:04:51,291 --> 00:04:52,883 You don't have to do the sums to see 62 00:04:53,092 --> 00:04:56,255 how mice can quickly take over the place. 63 00:05:07,006 --> 00:05:08,997 Individuals may not live very long, 64 00:05:09,275 --> 00:05:12,267 but their fast and furious way of life 65 00:05:12,478 --> 00:05:13,445 is a winning one, 66 00:05:13,646 --> 00:05:16,137 if you're constantly dicing with death. 67 00:05:23,423 --> 00:05:26,324 A wild owl lives up to eight years. 68 00:05:28,428 --> 00:05:31,556 So what gives them the extra-Iong lease? 69 00:05:36,235 --> 00:05:38,362 It's not just that they're bigger than mice. 70 00:05:38,604 --> 00:05:41,630 It takes a lot longer to bring up their brood. 71 00:05:42,075 --> 00:05:44,100 What took the mice 5 weeks, 72 00:05:44,377 --> 00:05:46,675 takes the owls a whole year. 73 00:05:49,248 --> 00:05:50,840 By zooming through the months 74 00:05:51,050 --> 00:05:52,915 we can see that an infant owl has to 75 00:05:53,119 --> 00:05:57,556 develop some pretty complicated kit to become a successful hunter. 76 00:05:59,826 --> 00:06:02,989 It needs a beak that can rip into prey... 77 00:06:04,697 --> 00:06:06,221 Special wing feathers 78 00:06:06,432 --> 00:06:09,299 that will help it glide silently through the night... 79 00:06:11,170 --> 00:06:13,468 ...talons that can pincer a rodent... 80 00:06:14,907 --> 00:06:17,671 ...and discs of specialized feathers 81 00:06:18,144 --> 00:06:19,668 around each eye. 82 00:06:19,946 --> 00:06:21,208 Like satellite dishes 83 00:06:21,414 --> 00:06:23,348 these focus the tiniest rustlings 84 00:06:23,549 --> 00:06:26,746 directly to its pin-sharp ears. 85 00:06:28,955 --> 00:06:30,445 Even when it's fully fledged, 86 00:06:30,656 --> 00:06:32,988 our young owl still needs time to learn 87 00:06:33,192 --> 00:06:35,626 the tricks of its hunting trade. 88 00:06:41,934 --> 00:06:47,372 Only then can it hope to find a mate and have a family of its own. 89 00:06:52,044 --> 00:06:53,409 It's a more demanding way of life 90 00:06:53,613 --> 00:06:55,911 so they have to take things step by step. 91 00:06:56,416 --> 00:07:00,409 That's why barn owls live a lot longer than mice. 92 00:07:06,759 --> 00:07:12,698 But one animal has stretched its lifetime to an absolute extreme. 93 00:07:23,609 --> 00:07:25,736 Primitive harpoon heads have recently 94 00:07:25,945 --> 00:07:28,743 been found in a few bowhead whales - 95 00:07:28,948 --> 00:07:31,416 this proves that these whales can live 96 00:07:31,617 --> 00:07:35,109 for an incredible 200 years. 97 00:07:38,658 --> 00:07:39,750 Size matters, 98 00:07:40,560 --> 00:07:41,857 but living in the Arctic Ocean 99 00:07:42,061 --> 00:07:44,495 it might take decades to fatten up 100 00:07:44,697 --> 00:07:46,528 and reach breeding age. 101 00:07:52,939 --> 00:07:54,702 But that's not the only delay. 102 00:07:54,907 --> 00:07:56,704 Over these frozen wastes, 103 00:07:56,909 --> 00:08:00,367 it can take ages to even find a partner. 104 00:08:02,682 --> 00:08:05,116 There is no speed dating here. 105 00:08:05,351 --> 00:08:07,842 In these tough waters bowheads 106 00:08:08,054 --> 00:08:10,420 need very, very long lives 107 00:08:10,623 --> 00:08:13,888 to make sure there is a next generation. 108 00:08:17,697 --> 00:08:19,187 So what about us? 109 00:08:20,132 --> 00:08:21,156 Going by size, 110 00:08:21,400 --> 00:08:24,460 we humans should only live for 30 years. 111 00:08:24,670 --> 00:08:27,332 And in fact most people have found partners 112 00:08:27,540 --> 00:08:30,031 and had a family by their thirties. 113 00:08:32,011 --> 00:08:33,603 But our lives don't stop there. 114 00:08:33,846 --> 00:08:37,475 Even though we might have done our bit to prolong the human race, 115 00:08:37,783 --> 00:08:42,117 we then expect to live way past our child-rearing years. 116 00:08:45,358 --> 00:08:46,689 Sociable animals 117 00:08:46,893 --> 00:08:51,921 apes, dolphins and humans, get an extension on life. 118 00:08:52,131 --> 00:08:53,689 We've earned this extra time 119 00:08:53,900 --> 00:08:56,994 by becoming helpful in old age. 120 00:08:58,504 --> 00:08:59,937 Grandparents and other members 121 00:09:00,139 --> 00:09:04,508 of extended families offer wisdom, wealth and, of course, 122 00:09:04,710 --> 00:09:05,768 baby-sitting. 123 00:09:10,049 --> 00:09:13,280 Mouse, owl, whale or man - 124 00:09:13,686 --> 00:09:15,517 We've all got different life spans 125 00:09:15,721 --> 00:09:18,417 which best suit how and where we live. 126 00:09:18,658 --> 00:09:22,458 But no matter how long or short our time on earth, 127 00:09:22,695 --> 00:09:26,529 We're all under the thumb of one great clock. 128 00:09:49,555 --> 00:09:51,489 As dawn breaks over Hong Kong, 129 00:09:51,691 --> 00:09:54,717 millions of people begin their journey to work. 130 00:09:59,131 --> 00:10:03,625 This mad rush hour may seem as far removed from nature as you can get. 131 00:10:03,836 --> 00:10:06,066 But in fact we're not the only animal 132 00:10:06,272 --> 00:10:09,036 trapped in a nine to five routine. 133 00:10:13,412 --> 00:10:15,846 Off a remote island in the Pacific, 134 00:10:16,182 --> 00:10:19,276 golden jellyfish crowd a marine lake. 135 00:10:20,820 --> 00:10:22,151 By speeding up the clock 136 00:10:22,388 --> 00:10:25,516 we can see that they too have a rush hour. 137 00:10:29,795 --> 00:10:32,229 Every day they rise at the same time 138 00:10:32,431 --> 00:10:35,798 and set off on the same commute across the lake. 139 00:10:36,235 --> 00:10:38,760 So why have they joined the rat race? 140 00:10:44,176 --> 00:10:46,406 The clue lies in their golden glow, 141 00:10:46,612 --> 00:10:50,173 a colour caused by millions of tiny algae 142 00:10:50,383 --> 00:10:52,283 that live within the jellyfish. 143 00:10:55,321 --> 00:10:57,687 The algae produce sugars which they 144 00:10:57,890 --> 00:11:00,290 share with their jellyfish partners. 145 00:11:00,559 --> 00:11:02,220 But to keep their golden complexion 146 00:11:02,428 --> 00:11:05,522 the algae need a secret ingredient 147 00:11:06,732 --> 00:11:07,858 sunlight. 148 00:11:12,338 --> 00:11:15,239 That's where their mobile homes come in. 149 00:11:19,845 --> 00:11:24,578 The jellyfish transport the algae up towards the sun each morning. 150 00:11:31,223 --> 00:11:34,283 The water glistens as the jellies break the surface, 151 00:11:34,493 --> 00:11:36,552 but their job isn't over. 152 00:11:36,762 --> 00:11:39,162 All day they have to work the area of the lake - 153 00:11:39,365 --> 00:11:42,357 shifting position to follow the arc-ing sun. 154 00:11:43,736 --> 00:11:44,725 It's a long day, 155 00:11:44,937 --> 00:11:45,835 but it's the only way 156 00:11:46,038 --> 00:11:48,006 that both algae and jellies 157 00:11:48,307 --> 00:11:49,399 get enough to eat. 158 00:11:51,811 --> 00:11:56,111 The relationship is so successful that jellyfish numbers have boomed 159 00:11:56,949 --> 00:11:57,347 today 160 00:11:57,550 --> 00:11:59,814 there are over ten million of them. 161 00:12:03,656 --> 00:12:04,953 Unlike our jobs, 162 00:12:05,157 --> 00:12:06,681 there are no breaks. 163 00:12:06,892 --> 00:12:11,386 This is round the clock, day in, day out. 164 00:12:36,455 --> 00:12:39,356 The setting sun triggers a return commute - 165 00:12:39,592 --> 00:12:41,958 back down to the depths of the lake. 166 00:12:42,394 --> 00:12:43,520 Just as we need rest 167 00:12:43,729 --> 00:12:44,787 and recuperation 168 00:12:45,030 --> 00:12:48,989 the algae passengers must re-stock on vital nutrients 169 00:12:49,201 --> 00:12:50,759 that have sunk to the bottom. 170 00:12:51,170 --> 00:12:54,139 The algae get there on the jelly-train. 171 00:13:00,279 --> 00:13:02,213 Tomorrow the whole thing will start again. 172 00:13:06,852 --> 00:13:08,319 The sun is boss. 173 00:13:10,089 --> 00:13:11,989 We, and many other creatures, 174 00:13:12,191 --> 00:13:14,625 clock on while the sun floods the world 175 00:13:14,827 --> 00:13:16,419 with heat and light, 176 00:13:16,929 --> 00:13:19,454 and clock off when it sinks from view. 177 00:13:19,899 --> 00:13:23,494 Its daily rhythm is our daily grind. 178 00:13:33,579 --> 00:13:34,944 It may feel relentless, 179 00:13:35,181 --> 00:13:36,944 but the big clock in the sky 180 00:13:37,149 --> 00:13:41,176 sets the pace at which our bodies work best. 181 00:13:43,856 --> 00:13:48,259 But it's not the only timepiece controlling life on earth... 182 00:13:57,770 --> 00:14:01,467 Even though it is nearly 400,000 kilometres away, 183 00:14:01,774 --> 00:14:06,871 the moon also has a profound influence on many animals. 184 00:14:09,248 --> 00:14:10,772 As it spins around the earth 185 00:14:10,983 --> 00:14:15,283 it drags a great bulge of oceanic water in its wake 186 00:14:16,655 --> 00:14:17,883 the rising tide. 187 00:14:20,860 --> 00:14:22,885 It ebbs and flows twice a day 188 00:14:23,095 --> 00:14:24,153 but that's not all. 189 00:14:24,363 --> 00:14:27,389 Each day the timing of the new tide shifts forwards 190 00:14:27,600 --> 00:14:28,828 by nearly an hour. 191 00:14:31,136 --> 00:14:32,660 It's a highly complicated schedule 192 00:14:32,938 --> 00:14:35,498 so how can anything live by it? 193 00:14:41,347 --> 00:14:43,212 It's two in the afternoon 194 00:14:43,415 --> 00:14:47,613 and the incoming tide is driving waves towards the beach 195 00:14:47,820 --> 00:14:50,550 to a surfer's paradise in Australia. 196 00:14:57,930 --> 00:15:00,296 The best surf is at the turn of the tide, 197 00:15:00,633 --> 00:15:02,999 but predicting when this is requires 198 00:15:03,202 --> 00:15:06,296 some precise astronomical calculations. 199 00:15:07,439 --> 00:15:09,669 Luckily, someone else has done the maths. 200 00:15:14,446 --> 00:15:18,610 All surfers need to do is check out the tide timetable... 201 00:15:18,817 --> 00:15:20,375 and then just watch the clock. 202 00:15:29,528 --> 00:15:30,927 That's it - surf's up! 203 00:15:52,985 --> 00:15:54,885 Being able to calculate these moments, 204 00:15:55,087 --> 00:15:57,920 means you can make the most of moon-power. 205 00:15:58,190 --> 00:15:59,054 But for other creatures 206 00:15:59,258 --> 00:16:02,159 this complicated shift in the tide times 207 00:16:02,361 --> 00:16:04,727 could make life very risky indeed. 208 00:16:15,574 --> 00:16:17,633 The receding tide is like a cloth 209 00:16:17,843 --> 00:16:20,937 being pulled back from over a hidden feast. 210 00:16:21,246 --> 00:16:23,680 The tiny creatures aren't exactly on a plate, 211 00:16:23,882 --> 00:16:25,941 but they are there for the taking. 212 00:16:31,423 --> 00:16:33,983 While the tide's out it's dinnertime, 213 00:16:34,426 --> 00:16:36,587 not just for this one soldier crab, 214 00:16:36,829 --> 00:16:38,524 but a huge army of them. 215 00:16:53,379 --> 00:16:56,644 They're on a regimented march to the water's edge. 216 00:17:04,857 --> 00:17:06,848 With so many crabs to choose from, 217 00:17:07,159 --> 00:17:10,424 predators find it hard to single out their prey. 218 00:17:18,537 --> 00:17:22,337 Soldier crabs can only sieve out food along the shoreline 219 00:17:22,541 --> 00:17:23,974 while the sand is damp. 220 00:17:24,209 --> 00:17:25,608 So they haven't got long. 221 00:17:35,888 --> 00:17:37,617 Something extraordinary happens, 222 00:17:37,823 --> 00:17:39,848 just before the tide turns. 223 00:17:40,392 --> 00:17:45,329 It's as if a sergeant major has barked out the order to retreat. 224 00:17:45,531 --> 00:17:48,728 As one, the crabs scuttle back up the beach. 225 00:17:57,042 --> 00:17:57,906 Just as well. 226 00:17:58,110 --> 00:18:02,342 If they were to stay out a moment too long they would risk certain death. 227 00:18:05,818 --> 00:18:09,413 The incoming tide brings crab-hungry fish. 228 00:18:12,958 --> 00:18:15,893 Even though the tide times are constantly shifting, 229 00:18:16,228 --> 00:18:20,187 soldier crabs - amazingly - never get caught out. 230 00:18:23,202 --> 00:18:26,069 How do they get the timing right? 231 00:18:27,539 --> 00:18:30,007 Are they sensing movement under the sand? 232 00:18:32,845 --> 00:18:35,370 Is it down to remarkable eyesight? 233 00:18:38,383 --> 00:18:40,317 Or is something else going on? 234 00:18:46,291 --> 00:18:49,021 If we isolate crabs from the outside world 235 00:18:49,261 --> 00:18:52,492 we can reveal the secret of their precision timing. 236 00:18:55,901 --> 00:19:01,271 Just watch what happens to these crabs as the tide rises and falls. 237 00:19:04,977 --> 00:19:06,842 When it's outthey run around, 238 00:19:07,045 --> 00:19:08,478 as if it's time to feed. 239 00:19:10,549 --> 00:19:12,380 But when it re-floods, 240 00:19:12,918 --> 00:19:14,852 they mysteriously stop moving, 241 00:19:15,053 --> 00:19:17,078 as they would if they were in their burrows. 242 00:19:19,258 --> 00:19:22,750 It's all down to an internal alarm clock that's tied, 243 00:19:23,061 --> 00:19:24,050 not to the sun, 244 00:19:24,429 --> 00:19:25,453 but to the moon. 245 00:19:34,206 --> 00:19:37,403 What's more, it is incredibly sophisticated. 246 00:19:37,609 --> 00:19:38,769 It's self-adjusting. 247 00:19:39,044 --> 00:19:42,138 We wake up at more or less the same time each day. 248 00:19:42,481 --> 00:19:44,108 The crabs' wake-up call shifts 249 00:19:44,316 --> 00:19:45,977 by almost an hour 250 00:19:46,185 --> 00:19:47,652 with each tide. 251 00:19:54,693 --> 00:19:57,719 This is how the soldiers get their timing right. 252 00:20:09,708 --> 00:20:13,269 But it's not just animals that need to keep an eye on the clock. 253 00:20:16,648 --> 00:20:19,742 Many flowers open during daylight hours, 254 00:20:19,952 --> 00:20:22,420 but they don't all open at the same time. 255 00:20:26,225 --> 00:20:27,692 Take the morning glory. 256 00:20:28,026 --> 00:20:30,017 It opens soon after dawn, 257 00:20:30,229 --> 00:20:33,721 but the South African mesemb waits until noon. 258 00:20:35,067 --> 00:20:37,797 The evening primrose, as its name suggests, 259 00:20:38,003 --> 00:20:40,369 saves itself for the twilight hours. 260 00:20:43,475 --> 00:20:45,670 So what on earth is going on? 261 00:20:46,778 --> 00:20:48,939 Can plants really tell the time? 262 00:20:58,590 --> 00:21:00,353 When it comes to setting seed, 263 00:21:00,559 --> 00:21:02,857 flowers have a big problem. 264 00:21:03,128 --> 00:21:04,720 They must exchange pollen 265 00:21:04,930 --> 00:21:06,898 with each other a bit tricky 266 00:21:07,099 --> 00:21:08,623 when you're rooted to the spot. 267 00:21:13,672 --> 00:21:15,936 Flowers need go-betweens insects 268 00:21:16,141 --> 00:21:18,666 that can carry fertilizing pollen 269 00:21:18,877 --> 00:21:20,708 from one flower to another. 270 00:21:22,014 --> 00:21:24,482 To attract the attention of passing insects 271 00:21:24,683 --> 00:21:26,412 flowers have to flirt. 272 00:21:26,618 --> 00:21:30,054 And they do this with a dazzling array of colours 273 00:21:30,255 --> 00:21:31,313 and scents. 274 00:21:32,257 --> 00:21:37,820 But of course insects are being courted by every hot-blossomed flower in the bed. 275 00:21:38,096 --> 00:21:40,826 So some flowers have found a really cunning way 276 00:21:41,033 --> 00:21:43,194 of standing out in the crowd. 277 00:21:48,073 --> 00:21:50,303 And it's all down to timing. 278 00:21:51,677 --> 00:21:55,636 At sunrise the morning glory is already on the pull - 279 00:21:55,847 --> 00:21:58,782 opening its petals before any other flower. 280 00:22:00,285 --> 00:22:01,479 This might seem risky 281 00:22:01,687 --> 00:22:03,086 as few insects are up 282 00:22:03,288 --> 00:22:05,586 and about during these chilly hours. 283 00:22:06,058 --> 00:22:09,789 But the morning glory is counting on another early riser. 284 00:22:12,898 --> 00:22:14,593 Bumblebees are so big 285 00:22:14,800 --> 00:22:15,789 that they can warm up 286 00:22:16,001 --> 00:22:18,094 independently of the sun. 287 00:22:20,005 --> 00:22:21,666 They vibrate their wing muscles 288 00:22:21,873 --> 00:22:24,103 to generate their own internal heat - 289 00:22:24,309 --> 00:22:28,177 and can get airborne as early as five a.m. 290 00:22:30,148 --> 00:22:32,946 Morning glories are ready and waiting. 291 00:22:38,323 --> 00:22:39,984 In return for spreading pollen, 292 00:22:40,192 --> 00:22:43,457 the bees are rewarded with a drink of nectar. 293 00:22:50,035 --> 00:22:52,663 The Mexican poppy takes a different approach. 294 00:22:52,871 --> 00:22:55,533 It's less fussy about who it flirts with, 295 00:22:55,741 --> 00:22:57,709 so it waits 'til after breakfast 296 00:22:57,909 --> 00:22:59,740 before giving its all. 297 00:23:02,314 --> 00:23:03,747 Its bright orange outfit 298 00:23:03,949 --> 00:23:05,644 is critical to its future. 299 00:23:06,017 --> 00:23:07,917 If rain or wind threatens, 300 00:23:08,120 --> 00:23:10,179 the poppy folds its petals away. 301 00:23:17,362 --> 00:23:20,729 By late morning the flowerbed is a riot of colour - 302 00:23:20,932 --> 00:23:22,194 a scramble of flowers 303 00:23:22,401 --> 00:23:25,427 trying to win the attentions of winged helpers. 304 00:23:25,637 --> 00:23:29,004 But the South African Mesemb is only just opening. 305 00:23:29,341 --> 00:23:32,936 How can it afford this lazy start to the day? 306 00:23:35,414 --> 00:23:36,745 Its long lie-in matches 307 00:23:36,948 --> 00:23:39,041 that of its chosen pollen courier 308 00:23:39,251 --> 00:23:42,812 an insect that needs a little more time to get going. 309 00:23:44,589 --> 00:23:46,022 Monkey beetles cannot take off 310 00:23:46,224 --> 00:23:49,489 until their body temperature reaches 27 degrees. 311 00:23:49,761 --> 00:23:50,750 So they're only out 312 00:23:50,962 --> 00:23:54,159 and about during the very hottest part of the day. 313 00:23:55,667 --> 00:23:58,636 On cue, the eye-catching mesembs are ready. 314 00:24:22,194 --> 00:24:23,821 But time is limited. 315 00:24:24,029 --> 00:24:26,122 As soon as the temperature starts to drop, 316 00:24:26,331 --> 00:24:28,799 monkey beetles run out of steam. 317 00:24:29,000 --> 00:24:31,366 So the mesembs turn off the charm too. 318 00:24:38,176 --> 00:24:41,475 One flower saves itself until after sundown, 319 00:24:41,680 --> 00:24:43,739 when most others have gone to bed. 320 00:24:44,115 --> 00:24:46,675 Only then does the evening primrose waft 321 00:24:46,885 --> 00:24:49,376 its seductive scent over the garden. 322 00:24:49,621 --> 00:24:51,418 It lures in night-flyers, 323 00:24:51,623 --> 00:24:53,215 such as moths. 324 00:24:55,861 --> 00:24:56,919 By waiting this late, 325 00:24:57,128 --> 00:25:00,962 the evening primrose has the pick of the insect night shift. 326 00:25:06,705 --> 00:25:09,435 So it seems plants really can tell the time. 327 00:25:09,641 --> 00:25:10,801 Right through the day 328 00:25:11,009 --> 00:25:14,206 they keep appointments with their insect go-betweens. 329 00:25:18,149 --> 00:25:21,346 It's a highly efficient way of getting fertilized. 330 00:25:21,553 --> 00:25:24,249 So, importantly, it guarantees 331 00:25:24,456 --> 00:25:27,482 the next generation of floral timekeepers. 332 00:25:35,934 --> 00:25:38,664 Judging time over a day is one thing, 333 00:25:39,971 --> 00:25:42,235 but how about over months and years? 334 00:25:42,474 --> 00:25:44,271 Sometimes this is essential. 335 00:25:46,711 --> 00:25:47,803 Especially when it comes 336 00:25:48,013 --> 00:25:51,073 to keeping the whole family line on track. 337 00:25:55,787 --> 00:25:57,687 And for one North American animal 338 00:25:57,889 --> 00:26:02,155 it's turned into a truly desperate struggle against the clock. 339 00:26:05,597 --> 00:26:07,929 It's high summer in northern Quebec 340 00:26:08,133 --> 00:26:12,126 and a huge herd of caribou covers the tundra. 341 00:26:12,437 --> 00:26:15,270 This is the richest pasture around. 342 00:26:17,175 --> 00:26:20,338 It's a perfect place to raise their young. 343 00:26:20,812 --> 00:26:23,144 But these caribou can't stay here. 344 00:26:23,515 --> 00:26:25,949 They are about to be driven away. 345 00:26:29,554 --> 00:26:31,078 But what's giving them the push? 346 00:26:33,058 --> 00:26:34,753 They live so far north 347 00:26:34,960 --> 00:26:38,418 that their world flips between seasonal extremes. 348 00:26:40,865 --> 00:26:43,800 It's June, and these warm summer meadows 349 00:26:44,069 --> 00:26:46,594 are about to become howling snowscapes. 350 00:27:01,653 --> 00:27:03,917 As the autumn weather closes in, 351 00:27:04,122 --> 00:27:07,114 the caribou are forced to run south. 352 00:27:11,463 --> 00:27:14,159 It's the start of an incredible marathon. 353 00:27:14,466 --> 00:27:15,865 But there's a deadline. 354 00:27:16,167 --> 00:27:18,260 They need to get back to the summer meadows 355 00:27:18,470 --> 00:27:20,131 by June next year 356 00:27:20,338 --> 00:27:21,862 to give birth to their young. 357 00:27:24,509 --> 00:27:25,806 The further they go south, 358 00:27:26,011 --> 00:27:28,411 the more time it will take to get back. 359 00:27:28,680 --> 00:27:31,808 So they've got to keep one eye on the advancing weather 360 00:27:32,050 --> 00:27:33,540 and one on the clock. 361 00:27:38,323 --> 00:27:39,847 All the while their hormones 362 00:27:40,058 --> 00:27:41,616 are working to schedule. 363 00:27:41,960 --> 00:27:43,518 They flood through the males 364 00:27:43,728 --> 00:27:46,060 which kick-starts the rut. 365 00:27:50,902 --> 00:27:53,837 Antlers develop and harden in unison, 366 00:27:54,039 --> 00:27:57,202 allowing the males to battle for females. 367 00:28:11,856 --> 00:28:14,188 The shorter day-length has got female 368 00:28:14,392 --> 00:28:16,326 hormones racing too. 369 00:28:18,396 --> 00:28:19,055 It's no accident 370 00:28:19,264 --> 00:28:20,561 that males and females 371 00:28:20,765 --> 00:28:23,325 have their minds on the same thing. 372 00:28:23,768 --> 00:28:25,702 It's all part of the master plan 373 00:28:26,004 --> 00:28:27,665 to ensure that all the females 374 00:28:27,872 --> 00:28:30,067 get pregnant at the same time. 375 00:28:40,418 --> 00:28:41,112 Once that's done, 376 00:28:41,319 --> 00:28:43,412 they're desperate to head back north, 377 00:28:43,621 --> 00:28:44,918 back to their meadows. 378 00:28:45,190 --> 00:28:47,954 But now the bad weather is blocking their way. 379 00:29:00,338 --> 00:29:03,307 For now, they have to bide their time down here 380 00:29:03,508 --> 00:29:05,100 not a soft option. 381 00:29:05,577 --> 00:29:08,137 So they scratch a living from lichens 382 00:29:08,346 --> 00:29:09,711 under the snow. 383 00:29:14,719 --> 00:29:18,052 It's a relentless search for the right diet. 384 00:29:18,256 --> 00:29:19,621 Lichens aren't enough 385 00:29:19,824 --> 00:29:21,291 for expectant mothers. 386 00:29:27,232 --> 00:29:30,133 Sometimes time just runs out. 387 00:29:37,709 --> 00:29:40,507 The females are now living close to the wire. 388 00:29:40,712 --> 00:29:43,272 The June deadline is getting closer. 389 00:29:43,548 --> 00:29:44,446 They're heavily pregnant 390 00:29:44,649 --> 00:29:47,550 but they're still four thousand kilometers 391 00:29:47,752 --> 00:29:49,720 away from the rich summer meadows 392 00:29:49,921 --> 00:29:51,718 where they want to give birth. 393 00:29:57,262 --> 00:29:59,059 Even though the ground is still frozen, 394 00:29:59,264 --> 00:30:00,856 alarm bells are ringing, 395 00:30:01,466 --> 00:30:02,455 telling the females 396 00:30:02,700 --> 00:30:04,031 to head north again. 397 00:30:10,308 --> 00:30:12,208 They've been on their feet for months. 398 00:30:12,510 --> 00:30:15,377 They've clocked up nine thousand kilometres, 399 00:30:15,814 --> 00:30:19,614 all to make it back to the calving meadows in time. 400 00:30:39,704 --> 00:30:40,363 They arrive back, 401 00:30:40,572 --> 00:30:43,405 just as these rich meadows come to their peak. 402 00:30:44,709 --> 00:30:46,176 And that's the clever bit. 403 00:30:47,545 --> 00:30:51,447 Thousands of calves are born within days of each other 404 00:30:51,649 --> 00:30:54,015 and it's all been precision-timed. 405 00:30:54,219 --> 00:30:56,084 That's because there's just a short window 406 00:30:56,287 --> 00:30:57,777 when the grass is at its best 407 00:30:57,989 --> 00:31:00,287 and when the calves can grow up quickly 408 00:31:00,491 --> 00:31:02,425 on their mothers' fortified milk. 409 00:31:06,364 --> 00:31:07,626 They've met the deadline, 410 00:31:07,899 --> 00:31:10,333 but time doesn't stand still. 411 00:31:14,205 --> 00:31:15,433 Within an hour of birth a calf 412 00:31:15,640 --> 00:31:17,574 is able to keep up with its mother, 413 00:31:18,009 --> 00:31:20,671 and will soon be ready to join the caribou herd's 414 00:31:20,879 --> 00:31:23,279 annual marathon race against time. 415 00:31:30,421 --> 00:31:34,881 The natural rhythms of the earth hold animals in a vice-like grip. 416 00:31:35,293 --> 00:31:37,227 To survive, they've simply got to keep up. 417 00:31:37,795 --> 00:31:40,093 But some remarkable creatures have managed 418 00:31:40,298 --> 00:31:42,892 to step off this time-treadmill. 419 00:31:45,436 --> 00:31:47,597 They've set their own agenda. 420 00:32:00,585 --> 00:32:03,019 It's the summer of 2003 421 00:32:03,221 --> 00:32:06,349 and the town of Elkin, North Carolina, 422 00:32:06,557 --> 00:32:10,891 has been overwhelmed by a swarm of cicadas. 423 00:32:11,930 --> 00:32:13,898 Normally bird and mammal predators 424 00:32:14,098 --> 00:32:18,057 would be having a field day picking off these tasty morsels. 425 00:32:18,369 --> 00:32:20,701 But strangely enough, no-one's eating them. 426 00:32:20,939 --> 00:32:23,635 It's as if the cicadas aren't really there. 427 00:32:24,242 --> 00:32:25,231 What's going on? 428 00:32:27,078 --> 00:32:28,943 These are periodic cicadas, 429 00:32:29,147 --> 00:32:30,478 so called because they've come up 430 00:32:30,682 --> 00:32:33,617 with an ingenious strategy to outwit their enemies 431 00:32:34,585 --> 00:32:35,984 but to see it in action 432 00:32:36,187 --> 00:32:39,247 we have to go back in time half a century. 433 00:32:45,430 --> 00:32:47,091 It's 1952 and the town 434 00:32:47,298 --> 00:32:48,959 of Elkin looks very different. 435 00:32:49,200 --> 00:32:52,169 The only familiar things are the cicadas. 436 00:32:55,440 --> 00:32:58,671 The residents of Elkin might have time on their hands, 437 00:32:58,977 --> 00:33:02,071 but the adult cicadas have no time to lose. 438 00:33:02,413 --> 00:33:04,005 They only have three more weeks 439 00:33:04,215 --> 00:33:05,648 to complete their life cycle. 440 00:33:07,685 --> 00:33:09,175 First they must find a partner, 441 00:33:09,387 --> 00:33:12,447 which they do with their own chirpy little number. 442 00:33:31,876 --> 00:33:32,774 Once they've mated, 443 00:33:32,977 --> 00:33:37,141 the females lay all their eggs in the branches of trees. 444 00:33:42,453 --> 00:33:44,944 After they've hatched the larvae fall to the ground 445 00:33:45,323 --> 00:33:46,881 and bury themselves. 446 00:33:47,225 --> 00:33:50,217 This in itself isn't unusual. 447 00:33:50,528 --> 00:33:52,553 But what happens next is. 448 00:33:53,531 --> 00:33:54,293 If we whizz 449 00:33:54,499 --> 00:33:55,397 through to the same time 450 00:33:55,600 --> 00:33:57,727 the following year, 1953, 451 00:33:57,935 --> 00:33:59,596 the fashions have moved on, 452 00:33:59,804 --> 00:34:03,069 but the cicadas are nowhere to be seen. 453 00:34:10,048 --> 00:34:14,985 In fact, we have to fast forward seventeen years to 1969 454 00:34:15,286 --> 00:34:16,150 before there is any 455 00:34:16,354 --> 00:34:17,616 sign of them again. 456 00:34:25,963 --> 00:34:26,987 While Neil Armstrong 457 00:34:27,198 --> 00:34:29,063 takes his first steps on the moon, 458 00:34:30,068 --> 00:34:33,834 back on earth people are celebrating the summer of love. 459 00:34:52,023 --> 00:34:55,925 The cicadas have also emerged for their own summer loving. 460 00:35:09,006 --> 00:35:10,234 The world has moved on, 461 00:35:10,441 --> 00:35:13,706 but the cicadas go through the same old routine. 462 00:35:13,911 --> 00:35:16,141 Once again the nymphs bury themselves 463 00:35:16,347 --> 00:35:18,042 and disappear from view. 464 00:35:18,249 --> 00:35:20,740 But for how long will it be this time? 465 00:35:40,338 --> 00:35:44,138 In 1986, exactly 17 years later, 466 00:35:44,408 --> 00:35:45,466 they re-appear. 467 00:35:53,084 --> 00:35:54,847 How on earth can the next generation, 468 00:35:55,052 --> 00:35:56,644 buried deep underground, 469 00:35:56,854 --> 00:36:00,756 measure the passing of time so accurately? 470 00:36:02,493 --> 00:36:04,961 It's now thought that the cicadas pick up cues 471 00:36:05,163 --> 00:36:09,156 from the yearly rise and fall of sap in plant roots. 472 00:36:09,367 --> 00:36:11,961 Yep, these guys are actually counting. 473 00:36:28,119 --> 00:36:30,815 It's only when they've counted another 17 years 474 00:36:31,022 --> 00:36:34,150 that these little time travellers appear again. 475 00:36:34,358 --> 00:36:38,556 We're back to where we started, in 2003. 476 00:36:41,699 --> 00:36:45,135 But what's the reason for taking time out for so long? 477 00:36:47,038 --> 00:36:48,869 Well, since they show up so rarely, 478 00:36:49,073 --> 00:36:49,596 no animal 479 00:36:49,807 --> 00:36:51,968 can rely on them as a source of food. 480 00:36:52,176 --> 00:36:53,643 In fact most animals wouldn't even 481 00:36:53,844 --> 00:36:55,744 recognize them as food - 482 00:36:55,947 --> 00:36:57,039 they might have seen this sight 483 00:36:57,248 --> 00:36:59,113 only once in a lifetime. 484 00:37:06,691 --> 00:37:07,658 With little to threaten them, 485 00:37:07,858 --> 00:37:12,454 the nymphs move into position for the last stage of their development. 486 00:37:12,830 --> 00:37:14,229 Here they can time-travel 487 00:37:14,432 --> 00:37:18,095 and emerge into adulthood in peace. 488 00:37:40,424 --> 00:37:42,858 By morning the whole town of Elkin 489 00:37:43,060 --> 00:37:46,860 is littered with their discarded nymphal shells. 490 00:37:51,902 --> 00:37:54,462 As long as they can accurately count up to 17 491 00:37:54,672 --> 00:37:56,367 and emerge altogether, 492 00:37:56,641 --> 00:37:59,701 they will outwit any potential predators. 493 00:38:03,281 --> 00:38:05,306 It's not just mathematically brilliant, 494 00:38:05,516 --> 00:38:07,507 it's biologically clever. 495 00:38:07,718 --> 00:38:10,278 Periodic cicadas have, quite literally, 496 00:38:10,488 --> 00:38:12,115 calculated how to stay out 497 00:38:12,323 --> 00:38:13,915 of other creature's mouths 498 00:38:14,158 --> 00:38:16,752 and in the race against time. 499 00:38:20,431 --> 00:38:23,798 By time travelling through three generations of cicadas 500 00:38:24,001 --> 00:38:26,868 we've unlocked the secret of their success. 501 00:38:28,339 --> 00:38:29,101 But just imagine 502 00:38:29,307 --> 00:38:32,435 if we could travel back through thousands of generations. 503 00:38:32,710 --> 00:38:36,111 What stories would unfold in front of our eyes? 504 00:38:38,215 --> 00:38:42,242 Flying around with a beak this big is no joke. 505 00:38:43,888 --> 00:38:45,651 How did this poor hummingbird 506 00:38:45,856 --> 00:38:48,984 become the Pinocchio of the bird world? 507 00:38:53,898 --> 00:38:55,889 It's the humbling story of what happens 508 00:38:56,100 --> 00:38:58,227 when a bird is driven to drink. 509 00:39:01,005 --> 00:39:03,405 All hummingbirds' tipple of choice 510 00:39:03,607 --> 00:39:05,541 is sugar-rich nectar. 511 00:39:05,843 --> 00:39:07,708 But they have to work to get it - 512 00:39:08,212 --> 00:39:09,509 hovering in mid-air 513 00:39:09,780 --> 00:39:12,840 while shooting their long tongue down a flower. 514 00:39:14,385 --> 00:39:17,320 Just doing this uses up huge quantities of energy, 515 00:39:17,521 --> 00:39:20,046 so the more they drink, the more they need. 516 00:39:20,324 --> 00:39:21,951 They're addicted to the stuff. 517 00:39:23,627 --> 00:39:26,255 But it's the flowers that control the shots, 518 00:39:26,530 --> 00:39:29,988 because they need the birds to distribute their pollen. 519 00:39:31,569 --> 00:39:34,129 As the birds are given a good drink of nectar, 520 00:39:34,338 --> 00:39:36,966 pollen rubs off onto the bird's forehead. 521 00:39:40,177 --> 00:39:41,838 As time moved on certain 522 00:39:42,046 --> 00:39:45,709 flowers got increasingly picky about who came for a drink. 523 00:39:46,283 --> 00:39:47,750 Their flowers changed shape 524 00:39:48,252 --> 00:39:50,243 so that not all hummers could get in. 525 00:39:50,921 --> 00:39:53,913 It's like having a lock and key on the drinks cabinet. 526 00:39:54,325 --> 00:39:57,692 Only the birds with the right-shaped bill can get access. 527 00:40:03,834 --> 00:40:06,701 One bird tried to cheat the system. 528 00:40:09,640 --> 00:40:13,474 Thousands of years ago, swordbills with slightly longer beaks 529 00:40:13,677 --> 00:40:17,408 got an extra shot of nectar from the Datura flower. 530 00:40:17,915 --> 00:40:20,975 But their heads were no longer in contact with the pollen, 531 00:40:21,352 --> 00:40:23,980 so the flower grew longer in response. 532 00:40:30,294 --> 00:40:31,261 Over generations, 533 00:40:31,462 --> 00:40:34,829 flower and beak tried to outsmart each other. 534 00:40:35,266 --> 00:40:37,564 Both became longer and longer, 535 00:40:38,102 --> 00:40:40,366 increasingly dependent on each other. 536 00:40:43,474 --> 00:40:48,070 No other bird can reach the nectar from this outlandish flower 537 00:40:48,312 --> 00:40:51,042 and the swordbills are stuck in a rut too. 538 00:40:53,017 --> 00:40:55,986 And that could be their undoing. 539 00:40:56,487 --> 00:40:56,919 For them, 540 00:40:57,121 --> 00:40:59,715 the future is now a one-way street, 541 00:41:00,191 --> 00:41:02,352 one that's more likely to be a dead end. 542 00:41:10,434 --> 00:41:11,696 By speeding through days, 543 00:41:11,902 --> 00:41:13,199 months and years 544 00:41:13,404 --> 00:41:14,234 we've seen how life 545 00:41:14,438 --> 00:41:16,963 adapts to an ever-changing world, 546 00:41:17,441 --> 00:41:18,840 but is it possible for anything 547 00:41:19,043 --> 00:41:22,479 to truly cheat time and live forever? 548 00:41:38,195 --> 00:41:42,029 We humans have done our best to extend our lifetimes. 549 00:41:43,267 --> 00:41:44,291 With family support, 550 00:41:44,502 --> 00:41:45,161 and better health 551 00:41:45,369 --> 00:41:48,167 we've added decades to our life span. 552 00:41:53,010 --> 00:41:56,571 But there is something that's taken almost magical control 553 00:41:56,847 --> 00:41:58,474 of its time on earth. 554 00:41:59,250 --> 00:42:01,582 To discover the secrets of its eternal life 555 00:42:01,785 --> 00:42:04,777 we must remain in this English churchyard, 556 00:42:05,256 --> 00:42:09,215 but imagine travelling back one thousand, six hundred years... 557 00:42:14,832 --> 00:42:17,232 ...to a funeral in the Dark Ages. 558 00:42:18,736 --> 00:42:20,795 It was a simple ceremony 559 00:42:21,105 --> 00:42:22,470 but these early Christians were known 560 00:42:22,673 --> 00:42:26,939 to mark the grave by planting the sapling of a yew tree. 561 00:42:32,082 --> 00:42:34,482 Maybe our ancestors already had a hunch 562 00:42:34,685 --> 00:42:37,483 about the enduring nature of this tree. 563 00:42:45,329 --> 00:42:48,765 If we watch this yew sapling grow at speed, 564 00:42:49,133 --> 00:42:50,964 will its secrets be revealed? 565 00:42:53,737 --> 00:42:55,204 In its first two hundred years 566 00:42:55,406 --> 00:42:58,967 it witnesses the felling of most of the wildwood around. 567 00:43:00,110 --> 00:43:02,374 Perhaps because it marks a grave, 568 00:43:02,680 --> 00:43:05,114 our yew tree is spared. 569 00:43:06,884 --> 00:43:08,943 It's when it creeps into its third century 570 00:43:09,153 --> 00:43:11,781 that it starts to unveil mysterious powers. 571 00:43:11,989 --> 00:43:14,958 Only the flesh of its berries is safe to eat. 572 00:43:16,026 --> 00:43:18,893 The leaves and bark are highly poisonous 573 00:43:19,330 --> 00:43:20,957 and are left well alone. 574 00:43:26,303 --> 00:43:28,294 The needles are like a curse. 575 00:43:30,474 --> 00:43:32,339 As they fall their toxic juices 576 00:43:32,543 --> 00:43:34,238 leach out into the earth. 577 00:43:37,781 --> 00:43:38,805 It wipes out the competition 578 00:43:39,016 --> 00:43:40,244 so that the yew 579 00:43:40,451 --> 00:43:43,352 has all the goodness of the soil to itself. 580 00:43:44,755 --> 00:43:47,121 This is how it gives itself a head start. 581 00:43:54,732 --> 00:43:55,960 It might have stood out 582 00:43:56,166 --> 00:43:58,999 as monks were spreading the Christian faith across England, 583 00:43:59,303 --> 00:44:01,737 because our four hundred year old yew 584 00:44:01,939 --> 00:44:04,669 had become a favoured burial site. 585 00:44:08,646 --> 00:44:11,581 A church is built on this sacred ground. 586 00:44:17,588 --> 00:44:18,782 As the centuries pass 587 00:44:18,989 --> 00:44:21,423 the church increases in stature. 588 00:44:24,828 --> 00:44:25,453 Meanwhile 589 00:44:25,663 --> 00:44:28,291 the yew-tree seems master of its own destiny. 590 00:44:28,499 --> 00:44:29,932 It doesn't just grow slowly. 591 00:44:30,134 --> 00:44:33,570 It appears to be able to stop itself growing altogether. 592 00:44:40,144 --> 00:44:42,510 These are tricks which our tree will need, 593 00:44:42,713 --> 00:44:45,580 because as we roll into the Middle Ages 594 00:44:45,783 --> 00:44:47,250 there's trouble in store. 595 00:44:51,622 --> 00:44:53,385 The weather is at its worst. 596 00:44:53,657 --> 00:44:55,352 The winters are long and cold 597 00:44:55,592 --> 00:44:57,423 and it rains cats and dogs. 598 00:45:09,239 --> 00:45:12,470 Many of its neighbours are toppled by strong gales. 599 00:45:12,743 --> 00:45:14,574 But the yew stands firm. 600 00:45:15,946 --> 00:45:18,210 During its slow, slow growth 601 00:45:18,482 --> 00:45:19,710 it's laid down hard, 602 00:45:19,917 --> 00:45:21,214 close-grained wood. 603 00:45:21,585 --> 00:45:26,579 And that gives its trunk and branches immense strength and flexibility. 604 00:45:30,961 --> 00:45:32,451 It weathers the middle ages, 605 00:45:32,663 --> 00:45:34,392 but at twelve hundred years old 606 00:45:34,698 --> 00:45:36,359 disaster is about 607 00:45:36,567 --> 00:45:38,467 to strike big time. 608 00:45:45,943 --> 00:45:47,570 While Cavaliers and Roundheads 609 00:45:47,778 --> 00:45:49,405 are tearing the country apart 610 00:45:49,646 --> 00:45:52,342 the yew tree has its own battle to fight. 611 00:45:52,783 --> 00:45:54,944 The dense wood, which served it so well, 612 00:45:55,185 --> 00:45:58,154 has trapped pools of water between the branches. 613 00:45:59,256 --> 00:46:02,248 The very heart of the tree is beginning to rot. 614 00:46:03,293 --> 00:46:05,488 Surely this is the end? 615 00:46:09,433 --> 00:46:12,197 But at what seems like its final hour, 616 00:46:12,402 --> 00:46:15,769 it conjures up its most remarkable trick of all. 617 00:46:18,008 --> 00:46:20,909 The tree throws itself a lifeline. 618 00:46:23,480 --> 00:46:25,448 A young branch from the canopy does 619 00:46:25,649 --> 00:46:27,913 a U-turn and grows downwards... 620 00:46:28,685 --> 00:46:31,415 right down into the rotting wood. 621 00:46:34,992 --> 00:46:37,517 There it feeds off its own compost. 622 00:46:37,795 --> 00:46:40,593 It has turned itself into a new root. 623 00:46:46,069 --> 00:46:49,197 It digs down through the heartwood into the ground, 624 00:46:49,439 --> 00:46:51,134 replanting itself. 625 00:46:51,341 --> 00:46:53,935 This is a tree that has the power 626 00:46:54,144 --> 00:46:56,874 to be born again, and again. 627 00:47:00,617 --> 00:47:05,645 Rejuvenated, the tree marches steadily on... into the twenty-first century. 628 00:47:05,989 --> 00:47:08,253 It's now sixteen hundred years old 629 00:47:08,492 --> 00:47:10,460 and still going strong. 630 00:47:15,165 --> 00:47:18,225 These days it often stands over a wedding. 631 00:47:47,297 --> 00:47:51,825 This yew has already outlived 80 generations of people... 632 00:47:52,069 --> 00:47:55,527 but who knows how much further through time it might travel? 633 00:48:07,818 --> 00:48:09,786 This ancient tree seems to know 634 00:48:09,987 --> 00:48:12,785 nothing of old age or death. 635 00:48:13,323 --> 00:48:16,019 It appears to have found life's holy grail 636 00:48:16,360 --> 00:48:19,261 the ultimate time-busting strategy 637 00:48:19,696 --> 00:48:21,857 the ability to live forever. 638 00:48:32,175 --> 00:48:34,336 But the yew tree is not the only winner. 639 00:48:35,946 --> 00:48:38,642 Over time individuals may come and go, 640 00:48:38,982 --> 00:48:40,006 entire species 641 00:48:40,217 --> 00:48:42,208 may adapt or die. 642 00:48:42,486 --> 00:48:45,785 But life itself - in all its different forms - 643 00:48:46,023 --> 00:48:49,220 has been steadily marching through time - 644 00:48:49,626 --> 00:48:54,063 so far for an incredible three and a half billion years! 645 00:48:55,899 --> 00:48:57,764 That's staying power. 646 00:48:58,168 --> 00:48:59,157 And that's what matters 647 00:48:59,369 --> 00:49:02,702 most in life's race against time.