1 00:00:36,836 --> 00:00:38,360 It is the heart of Africa. 2 00:00:38,904 --> 00:00:40,098 A hidden world. 3 00:00:43,475 --> 00:00:45,033 It is a tangled jungle... 4 00:00:46,712 --> 00:00:48,873 ...haunt of flickering shadows. 5 00:00:54,687 --> 00:00:58,282 It is a place of immense challenges... yet full of life. 6 00:01:05,831 --> 00:01:09,323 The more we look, the more extraordinary variety we find. 7 00:01:14,840 --> 00:01:17,502 This is one of the great laboratories of evolution... 8 00:01:17,843 --> 00:01:20,607 a world we are only just beginning to understand. 9 00:01:22,748 --> 00:01:26,844 Africa's heart is not dark, but green and vibrant... 10 00:01:27,253 --> 00:01:30,051 it is the tropical rainforest. 11 00:01:42,234 --> 00:01:46,295 Sunrise over the Equator and the African rainforest wakes. 12 00:01:47,873 --> 00:01:51,104 From Uganda in the East, to Sierra Leone in the West, 13 00:01:51,410 --> 00:01:53,310 it is a great belt of green. 14 00:01:53,646 --> 00:01:57,548 It spans the continent for five and half thousand kilometres. 15 00:02:01,387 --> 00:02:05,118 More light, more heat, more water than anywhere in Africa 16 00:02:05,257 --> 00:02:08,784 perfect for plants and they've completely taken over. 17 00:02:13,832 --> 00:02:18,428 An endless sea of leaves worshipping the sun on a new African morning. 18 00:02:23,409 --> 00:02:26,936 On the forest floor, the sunlight barely filters through. 19 00:02:29,949 --> 00:02:33,976 The underworld: A land of trunks and buttresses. 20 00:02:35,020 --> 00:02:38,012 They hold up the forest roof and they are its plumbing... 21 00:02:38,290 --> 00:02:41,157 pumping nutrients and water to the leaves above. 22 00:02:45,297 --> 00:02:47,424 Here, it's wise to take care. 23 00:02:50,069 --> 00:02:52,230 Plants stud their trunks with spikes. 24 00:02:54,206 --> 00:02:58,142 They defend themselves with armies of vicious stinging ants. 25 00:03:01,180 --> 00:03:03,580 And they lace their flesh with poisons... 26 00:03:05,517 --> 00:03:07,678 ...all this to stop them being eaten. 27 00:03:13,392 --> 00:03:16,691 In such a hostile jungle, how can anything survive? 28 00:03:19,331 --> 00:03:23,859 But there are opportunities here for creatures who know how to grasp them. 29 00:03:40,552 --> 00:03:42,918 Giant fruit fall from the sky. 30 00:03:48,594 --> 00:03:50,858 The sound echoes through the forest. 31 00:03:54,633 --> 00:03:57,932 Elephants deep in the heart of the jungle. 32 00:04:02,608 --> 00:04:05,076 Drawn towards the sound of falling fruit. 33 00:04:19,825 --> 00:04:22,350 As big as melons and harder than coconuts 34 00:04:22,494 --> 00:04:25,224 the fruit of the Omphalocarpum tree are ripe. 35 00:04:37,409 --> 00:04:41,812 Two kilos of nutritious food for those who can break it open. 36 00:04:44,750 --> 00:04:47,878 The smell is irresistible too like garlic. 37 00:04:48,387 --> 00:04:49,945 It hangs in the jungle air. 38 00:05:08,807 --> 00:05:10,297 But this fruit is so hard, 39 00:05:10,442 --> 00:05:13,309 it seems not even an elephant can dent it. 40 00:05:15,514 --> 00:05:16,572 Or can it? 41 00:05:24,690 --> 00:05:27,420 The elephant uses its tusks as precision tools 42 00:05:27,559 --> 00:05:29,117 to prise open the fruit. 43 00:05:30,262 --> 00:05:33,425 This remarkable behaviour has only just come to light. 44 00:05:39,872 --> 00:05:43,000 Fruit is the forest elephant's staple and this manna 45 00:05:43,142 --> 00:05:45,838 from the heavens is full of energy. 46 00:05:49,848 --> 00:05:52,715 But its also a rare gift and it takes more than 47 00:05:52,851 --> 00:05:57,447 just one ripe Omphalocarpum tree to feed Africa's largest land mammal. 48 00:05:59,892 --> 00:06:03,760 So elephants have learned to make the most of opportunities just like this. 49 00:06:04,496 --> 00:06:07,488 There's not a fruiting tree an elephant doesn't know... 50 00:06:08,700 --> 00:06:12,534 ...each one, pinpointed on a mental map of the forest in their head. 51 00:06:13,972 --> 00:06:17,464 And as they travel, they follow a network of paths they've carved out 52 00:06:17,609 --> 00:06:21,409 across the forest to over a hundred species of fruiting tree... 53 00:06:24,316 --> 00:06:29,276 To survive in this hard world elephants have become the masters of opportunity. 54 00:06:40,199 --> 00:06:42,963 There are others who've learned to survive here. 55 00:06:45,404 --> 00:06:47,895 For generations, people have found a living here, 56 00:06:48,507 --> 00:06:52,170 like the elephants, constantly seeking out chances for food. 57 00:07:12,064 --> 00:07:14,999 Monkeys, foraging low down in the trees... 58 00:07:16,168 --> 00:07:17,760 ...just within crossbow range. 59 00:07:50,102 --> 00:07:53,902 In this tangled place, even the most skilled hunters can go hungry... 60 00:07:57,309 --> 00:08:00,972 ...escape is just a leap away into the forest canopy. 61 00:08:03,448 --> 00:08:05,939 Forty metres up, sunny, breezy. 62 00:08:06,251 --> 00:08:07,377 Another world. 63 00:08:12,791 --> 00:08:16,022 And here is the engine of all forest life. 64 00:08:17,262 --> 00:08:19,890 Leaves soak up the energy of the African sun 65 00:08:20,032 --> 00:08:22,398 and turn it into plant food. 66 00:08:35,580 --> 00:08:37,912 Monkeys, perfectly designed to leap 67 00:08:38,050 --> 00:08:41,884 from tree to tree they travel the rainforest canopy. 68 00:08:47,192 --> 00:08:51,925 This black and white colobus and this red, are specialist leaf eaters. 69 00:08:54,366 --> 00:08:56,800 For them, food up here is all around. 70 00:08:58,203 --> 00:09:01,036 ...and they spend their days contentedly munching. 71 00:09:05,344 --> 00:09:07,835 But these leaves are not as innocent as they look. 72 00:09:08,780 --> 00:09:12,079 They protect themselves with a lethal cocktail of poisons 73 00:09:12,217 --> 00:09:15,050 tannins, strychnine, cyanide. 74 00:09:20,158 --> 00:09:22,058 So how can colobus eat them? 75 00:09:22,861 --> 00:09:25,625 Over time they have evolved specialised stomachs filled 76 00:09:25,797 --> 00:09:29,028 with bacteria that neutralise these poisons. 77 00:09:31,203 --> 00:09:35,333 In one day they can eat enough to kill a man several times over. 78 00:09:45,984 --> 00:09:47,144 The crowned eagle. 79 00:09:47,819 --> 00:09:51,448 It can't eat leaves, but it can eat monkeys. 80 00:09:54,893 --> 00:09:57,521 The cover of trees is no protection. 81 00:10:25,424 --> 00:10:30,726 With powerful strokes of its 2 metre wings it airlifts the prey back to its eyrie. 82 00:10:35,133 --> 00:10:37,693 Here it feeds its chick in a penthouse suite 83 00:10:37,836 --> 00:10:41,636 with a view far and wide over the roof of the forest. 84 00:10:51,349 --> 00:10:57,151 The canopy world is a place of extremes, of hot sun and drying winds, 85 00:10:57,289 --> 00:10:59,519 fierce and drenching storms. 86 00:11:01,660 --> 00:11:06,324 From dry times to wet times the seasons here are more marked. 87 00:11:08,233 --> 00:11:10,793 The long hard rains are soon due and 88 00:11:10,902 --> 00:11:13,928 a transformation comes over the forest canopy. 89 00:11:17,175 --> 00:11:19,666 As far as the eye can see, the trees blush, 90 00:11:19,945 --> 00:11:22,140 not with old leaves, but with new... 91 00:11:25,450 --> 00:11:28,419 The growth of spring with the colours of autumn. 92 00:11:36,261 --> 00:11:39,697 New, tender leaves don't yet have the protection of poisons. 93 00:11:41,132 --> 00:11:44,226 So to ensure they survive trees produce a glut 94 00:11:44,369 --> 00:11:47,827 far more than even the hungriest monkeys can eat! 95 00:11:55,313 --> 00:11:58,373 Flowers too fall under the spell of the seasons. 96 00:11:59,651 --> 00:12:03,348 And the animals of the canopy have a sweet, nectary treat. 97 00:12:24,476 --> 00:12:26,341 The canopy is a place of treasure... 98 00:12:28,013 --> 00:12:30,140 but only for those who can reach it. 99 00:12:48,366 --> 00:12:50,027 Using just a knotted vine, 100 00:12:50,335 --> 00:12:53,930 a Bayaka pygmy climbs from one forest world to another. 101 00:12:58,610 --> 00:13:01,078 He's after the sweetest prize in the jungle. 102 00:13:02,247 --> 00:13:03,111 Honey. 103 00:13:23,034 --> 00:13:25,594 Mongonje is the best tree climber in the area 104 00:13:25,937 --> 00:13:27,598 but it's still dangerous work. 105 00:13:29,207 --> 00:13:33,803 One slip of his axe and he falls to the forest floor, thirty metres below. 106 00:13:35,046 --> 00:13:37,446 At least this is a hive of stingless bees. 107 00:13:39,851 --> 00:13:42,820 They're still distracting and that can be dangerous. 108 00:13:49,961 --> 00:13:51,690 This work takes great nerve. 109 00:13:53,598 --> 00:13:54,826 ...and it's worth it. 110 00:14:04,442 --> 00:14:07,775 For the Bayaka this is a precious seasonal treat. 111 00:14:17,255 --> 00:14:19,689 The sunblessed goodness of the canopy delivered 112 00:14:19,824 --> 00:14:22,349 to the forest floor in a basket... 113 00:14:44,482 --> 00:14:47,883 For the most part it's hard work finding food in the forest 114 00:14:48,920 --> 00:14:51,354 but there is a time, a time of plenty, 115 00:14:51,656 --> 00:14:56,286 when all who live here get a helping hand courtesy of plants. 116 00:15:00,031 --> 00:15:04,400 As the long wet season arrives, the forest gives its best. 117 00:15:08,807 --> 00:15:11,332 Fruit, pure temptation. 118 00:15:56,354 --> 00:15:58,549 Birds are always the first to arrive. 119 00:15:59,724 --> 00:16:00,952 A great blue turaco. 120 00:16:04,796 --> 00:16:05,888 Hornbills... 121 00:16:07,565 --> 00:16:09,032 ...the African grey parrot. 122 00:16:52,010 --> 00:16:53,671 Chimps love fruit too. 123 00:16:54,946 --> 00:16:57,244 Fussy about ripeness, they check each one. 124 00:17:02,921 --> 00:17:05,515 A fruiting fig like this is a major event. 125 00:17:12,797 --> 00:17:14,958 Over half a chimp's diet is fruit, 126 00:17:15,233 --> 00:17:19,101 so youngsters learn from an early age where to find trees like this. 127 00:17:23,208 --> 00:17:25,403 By the time they grow up the chimps know the trees 128 00:17:25,543 --> 00:17:28,774 so well that they can even predict when they are going to be ripe. 129 00:17:35,119 --> 00:17:37,587 When a fig tree fruits there's so much of it, 130 00:17:37,722 --> 00:17:40,213 even the forest floor gets a rare treat... 131 00:17:42,360 --> 00:17:44,351 ...the scraps from the banquet above. 132 00:17:50,401 --> 00:17:51,868 But figs are unusual. 133 00:17:52,136 --> 00:17:52,898 Unlike other trees, 134 00:17:53,037 --> 00:17:56,131 they can fruit in any season so they are especially useful 135 00:17:56,274 --> 00:17:58,538 for seeing animals through leaner times. 136 00:18:01,779 --> 00:18:03,838 Fruit is crucial for survival here. 137 00:18:04,449 --> 00:18:07,384 But as animals eat they also serve plants. 138 00:18:08,152 --> 00:18:10,177 As the chimps move off to find other fruits 139 00:18:10,321 --> 00:18:12,789 they carry with them the seeds of trees. 140 00:18:15,960 --> 00:18:18,087 Birds have an even bigger range 141 00:18:18,396 --> 00:18:20,296 the seeds they eat are energy rich, 142 00:18:20,431 --> 00:18:21,523 but lightweight, 143 00:18:21,933 --> 00:18:24,868 perfectly designed by plants to be airlifted. 144 00:18:27,405 --> 00:18:31,637 A quarter of all rainforest trees are dispersed by hornbills alone. 145 00:18:37,282 --> 00:18:40,945 And it's no coincidence that elephants love Omphalocarpum fruits. 146 00:18:41,819 --> 00:18:44,788 If a tree can tempt this animal into eating its fruit, 147 00:18:44,856 --> 00:18:47,188 it gets the best disperser there is. 148 00:18:52,263 --> 00:18:54,823 As they walk from tree to tree seeking fruit, 149 00:18:55,133 --> 00:18:57,795 elephants can range over hundreds of kilometres, 150 00:18:57,936 --> 00:19:01,463 sewing the seeds of new trees on their paths as they go... 151 00:19:02,340 --> 00:19:05,332 ...complete with a ready made pile of fertiliser. 152 00:19:22,894 --> 00:19:25,454 Over the millennia, animals have been a vital force 153 00:19:25,596 --> 00:19:30,431 in helping the African rainforest spread far and wide across the Equator. 154 00:19:42,513 --> 00:19:46,176 Now we are beginning to discover a new side to the forest. 155 00:19:48,619 --> 00:19:51,884 Africa's climate hasn't always been as it is today. 156 00:19:53,057 --> 00:19:57,460 Through the ages it has swung through repeated cycles of wet and dry. 157 00:20:00,098 --> 00:20:01,929 The forest has changed too, 158 00:20:02,066 --> 00:20:05,797 expanding with the wet years and shrinking back in the dry. 159 00:20:12,877 --> 00:20:15,710 Today's endless green sea is simply 160 00:20:15,847 --> 00:20:19,647 a snapshot of an ever changing, dynamic place. 161 00:20:20,918 --> 00:20:23,751 A pumping green heart at Africa's centre. 162 00:20:31,896 --> 00:20:34,262 Now is a wet time in Africa's history 163 00:20:34,399 --> 00:20:37,368 and the forest is near its maximum extent. 164 00:20:45,643 --> 00:20:48,271 It rains practically every day... 165 00:20:48,413 --> 00:20:51,814 in some place, an incredible 10 metres a year. 166 00:22:01,819 --> 00:22:05,516 To live here is to put up with a phenomenal amount of rain. 167 00:22:06,557 --> 00:22:08,582 But it's not necessarily bad news. 168 00:22:11,129 --> 00:22:12,426 The rain that has shaped the forest 169 00:22:12,563 --> 00:22:16,659 over millennia brings change on a small scale every day 170 00:22:17,468 --> 00:22:19,800 and with each change comes a new way for animals 171 00:22:19,937 --> 00:22:22,337 to survive in this land of plants. 172 00:22:24,275 --> 00:22:27,711 An elephant's footprint has filled with water from the downpour. 173 00:22:29,347 --> 00:22:31,542 Inside a minor miracle happens. 174 00:22:35,987 --> 00:22:38,455 Microscopic eggs hatch into fish. 175 00:22:55,773 --> 00:22:58,003 The transformation is complete. 176 00:22:58,643 --> 00:23:02,773 Multicoloured Killifish here in an elephant's footprint. 177 00:23:10,254 --> 00:23:14,156 In their temporary pool they are safe from the predators of bigger rivers. 178 00:23:15,092 --> 00:23:17,151 But even here there are villains. 179 00:23:24,202 --> 00:23:28,662 A Congo water scorpion has venom to dissolve the flesh of fish. 180 00:23:38,115 --> 00:23:40,208 Not much future in a footprint anyway. 181 00:23:41,085 --> 00:23:43,417 Now the killifish shows its true colours 182 00:23:44,055 --> 00:23:47,252 superbly designed to flip from stream to stream... 183 00:23:47,491 --> 00:23:49,220 in this temporary water world. 184 00:23:50,061 --> 00:23:53,030 He turns his nose into the current like a tiny salmon 185 00:23:53,164 --> 00:23:56,531 to take advantage of a newly running, rain-fed stream. 186 00:24:01,405 --> 00:24:02,997 And this is what the colours are for. 187 00:24:03,474 --> 00:24:04,839 A killifish female. 188 00:24:05,943 --> 00:24:10,073 In the dark light of the forest floor the display is irresistible. 189 00:24:28,599 --> 00:24:31,796 She is mesmerised by his kaleidoscopic advances... 190 00:24:33,471 --> 00:24:35,336 and a new generation is spawned. 191 00:24:37,041 --> 00:24:38,201 In these changing waters, 192 00:24:38,342 --> 00:24:41,106 killifish have found their niche in the rainforest. 193 00:24:42,580 --> 00:24:43,842 And when the rain subsides, 194 00:24:43,981 --> 00:24:45,915 the water level here may drop again, 195 00:24:46,050 --> 00:24:47,415 but her eggs will be safe, 196 00:24:47,551 --> 00:24:51,112 dormant in the river bed, just ready to add water. 197 00:24:56,327 --> 00:24:59,160 But for now the rainforest is overflowing. 198 00:25:01,132 --> 00:25:05,193 What water the trees don't suck up, the forest pours out. 199 00:25:06,103 --> 00:25:08,037 Streams flow into torrents... 200 00:25:08,239 --> 00:25:11,140 ...and torrents into giant foaming rivers. 201 00:25:53,184 --> 00:25:56,085 Rivers break up the monotony of the rainforest. 202 00:25:57,488 --> 00:25:59,581 Light streams down to the ground. 203 00:26:00,725 --> 00:26:03,592 Canopy world meets underworld. 204 00:26:06,964 --> 00:26:09,865 Black and white colobus like living beside rivers. 205 00:26:11,702 --> 00:26:14,535 Here, their plant food is more varied, more nutritious, 206 00:26:14,805 --> 00:26:17,205 so they don't need to spend so much time eating. 207 00:26:17,942 --> 00:26:20,843 There are better things to do, like grooming... 208 00:26:26,384 --> 00:26:29,353 ...or passing round the new-born, all white baby. 209 00:26:37,061 --> 00:26:38,050 ...or just playing. 210 00:26:49,173 --> 00:26:53,109 Over time, these huge rivers, snaking through the forest, 211 00:26:53,244 --> 00:26:56,111 have cut a great swathe through a carpet of green. 212 00:26:57,548 --> 00:26:59,140 The Niger, the, the mighty Congo. 213 00:26:59,283 --> 00:27:01,251 Some of the largest rivers on earth. 214 00:27:01,652 --> 00:27:02,744 With their relentless flow, 215 00:27:02,887 --> 00:27:04,946 they have broken the hold of the forest, 216 00:27:05,089 --> 00:27:08,616 at each twist and turn creating new chances for life. 217 00:27:10,361 --> 00:27:12,090 By travelling along the river's edge, 218 00:27:12,229 --> 00:27:16,996 animals like the black and white colobus have spread the forests of Africa... 219 00:27:19,670 --> 00:27:22,036 The rivers have brought others here, too. 220 00:27:31,816 --> 00:27:36,685 The Fang tribe of Equatorial Guinea depend for their survival on forest rivers, 221 00:27:36,821 --> 00:27:39,119 they've learned just how to exploit them. 222 00:27:48,732 --> 00:27:50,825 They collect the bark of the Olong tree... 223 00:28:03,013 --> 00:28:05,379 ...then they pound it by the side of the river. 224 00:28:38,249 --> 00:28:41,446 As they wash the bark, its juices flow downstream. 225 00:29:00,004 --> 00:29:01,471 They are poisonous juices. 226 00:29:01,839 --> 00:29:03,864 Designed to save a tree from being eaten, 227 00:29:04,008 --> 00:29:07,569 the poison is so strong that it stuns the fish of the river. 228 00:29:12,283 --> 00:29:14,080 If all fishing were so easy! 229 00:29:16,887 --> 00:29:20,220 And the effects of this natural poison are quite remarkable. 230 00:29:21,525 --> 00:29:23,755 Fish that are caught are safe to eat, 231 00:29:23,894 --> 00:29:26,761 whilst those that slip away quickly recover. 232 00:29:29,166 --> 00:29:32,033 Soon the river will be full of fish once more. 233 00:29:39,510 --> 00:29:40,943 In the depths of the Congo, 234 00:29:41,078 --> 00:29:44,878 rivers also provide food for some of our closest relatives. 235 00:29:50,688 --> 00:29:53,054 Bonobos or pygmy chimpanzees, 236 00:29:53,190 --> 00:29:55,886 fish for insect larvae in a forest stream. 237 00:30:03,934 --> 00:30:06,061 Bonobos are close cousins of chimps 238 00:30:06,203 --> 00:30:09,639 when it comes to water they are subtly different. 239 00:30:11,809 --> 00:30:14,334 Their legs are longer and their posture more upright 240 00:30:14,478 --> 00:30:16,503 so they're much more at home in water. 241 00:30:17,247 --> 00:30:22,116 ...often they wade, foraging in rivers and pools with their delicate fingers. 242 00:30:26,857 --> 00:30:29,018 An altogether more aquatic ape. 243 00:30:37,635 --> 00:30:41,196 As evening comes the Bonobos need to find a dryer place. 244 00:30:41,472 --> 00:30:43,667 And head for the shelter of the trees. 245 00:31:04,328 --> 00:31:06,694 Lacing branches together they make a bed. 246 00:31:40,197 --> 00:31:43,826 Long ago Bonobos were cut off from their chimpanzee cousins 247 00:31:43,901 --> 00:31:46,267 by the changing course of the Congo River. 248 00:31:47,705 --> 00:31:50,265 Separated by water and unable to swim, 249 00:31:50,407 --> 00:31:54,173 they evolved over time to become a completely different species. 250 00:31:59,650 --> 00:32:00,617 In the rainforest, 251 00:32:00,751 --> 00:32:04,551 rivers not only sustain life they help to create it. 252 00:32:15,399 --> 00:32:19,995 From space, the forest night is a display of a thousand tiny flashes 253 00:32:20,137 --> 00:32:23,300 each one a storm hundreds of miles across. 254 00:32:24,208 --> 00:32:27,006 The forces of change are relentless. 255 00:32:31,381 --> 00:32:36,114 As morning comes the rain has passed and the forest is smothered in heavy mist. 256 00:32:39,123 --> 00:32:41,523 All is quiet - primeval. 257 00:32:42,559 --> 00:32:45,357 Sometimes the forest feels very permanent. 258 00:32:51,869 --> 00:32:55,464 Trees of some form or other have existed on Africa's Equator 259 00:32:55,606 --> 00:32:57,597 since the age of the dinosaurs. 260 00:33:03,714 --> 00:33:07,810 At times it's easy to think that monsters are here still. 261 00:33:43,587 --> 00:33:45,578 With heavy burdens, shallow roots, 262 00:33:45,722 --> 00:33:49,351 thin soils - trees fall all the time in the rainforest, 263 00:33:49,493 --> 00:33:51,358 leaving a hole in its roof. 264 00:33:53,297 --> 00:33:56,357 And so a piece of Africa that has been centuries dark greets 265 00:33:56,500 --> 00:33:58,559 the stream of morning light. 266 00:34:03,173 --> 00:34:06,108 Immediately the whole intricate web of rainforest life 267 00:34:06,243 --> 00:34:08,234 jumps out to seize the day. 268 00:34:12,082 --> 00:34:14,448 The first to take the chance is the wild yam, 269 00:34:14,585 --> 00:34:16,519 sprinter of the plant world. 270 00:34:17,287 --> 00:34:20,313 It heads for the hole in the canopy and the precious sun. 271 00:34:21,024 --> 00:34:23,015 Underground is a secret weapon 272 00:34:23,160 --> 00:34:28,029 a giant tuber which pumps energy into the growing tip day and night. 273 00:34:34,838 --> 00:34:38,797 It grows an incredible one metre in just three days. 274 00:34:45,449 --> 00:34:46,416 And there's more. 275 00:34:46,550 --> 00:34:50,884 As it grows it produces tiny beads of sweet nectar on its shoots. 276 00:34:54,625 --> 00:34:55,819 Insects are drawn in. 277 00:34:57,027 --> 00:35:01,555 Butterflies, and most importantly, ants, 278 00:35:01,798 --> 00:35:05,825 who repay the favour by aggressively defending the yam from enemies. 279 00:35:08,038 --> 00:35:11,007 A place in the sun for the yam seems guaranteed. 280 00:35:13,210 --> 00:35:17,806 But in this infinitely complex world every defence is met with counter attack. 281 00:35:18,115 --> 00:35:20,310 Enter a very particular little beetle. 282 00:35:20,984 --> 00:35:24,044 Like the yam, it seizes what chances it may. 283 00:35:25,856 --> 00:35:28,416 It gets straight to the point and starts to mate. 284 00:35:28,825 --> 00:35:32,090 Before the ants are fully mobilised a tiny yellow larvae 285 00:35:32,229 --> 00:35:34,424 is already eating away at the yam. 286 00:35:35,432 --> 00:35:36,990 And here's the ingenious bit: 287 00:35:37,601 --> 00:35:40,832 As it eats, it absorbs poisons from the plant, 288 00:35:40,971 --> 00:35:42,495 taking the Yam's defences 289 00:35:42,639 --> 00:35:45,403 and spreading them on its back as a shield. 290 00:35:55,485 --> 00:35:57,885 To the ever watchful ant defence force, 291 00:35:58,021 --> 00:36:01,548 the beetle larvae now smells and tastes repellent. 292 00:36:02,392 --> 00:36:05,555 It's free to munch Yam flesh to its heart's content. 293 00:36:12,135 --> 00:36:14,626 One tiny larvae like this won't stop the yam 294 00:36:14,805 --> 00:36:16,534 on its journey to the sun 295 00:36:16,673 --> 00:36:19,938 but a chance for a yam is a chance for a beetle. 296 00:36:29,553 --> 00:36:33,216 As a host of forest life battles it out for a place in the sun, 297 00:36:33,357 --> 00:36:37,453 down below the fallen wood brings opportunity to others. 298 00:36:48,839 --> 00:36:51,603 The forest undertakers are staking their claims. 299 00:36:56,847 --> 00:37:00,010 Ants immediately get to work hollowing out the trunk. 300 00:37:17,100 --> 00:37:20,501 Fungi and slime moulds stretch out their morphing fingers 301 00:37:20,637 --> 00:37:22,764 to grab what nutrients they can. 302 00:37:27,477 --> 00:37:30,446 And termites digest the very fibre of the tree, 303 00:37:30,580 --> 00:37:32,946 passing nutrients back into the food chain. 304 00:37:51,368 --> 00:37:52,801 Chimpanzees love crisp, 305 00:37:52,869 --> 00:37:57,272 juicy and protein rich termites almost as much as they love fruits. 306 00:37:58,341 --> 00:38:01,970 And when it comes to winkling out dinner they have an advantage. 307 00:38:03,346 --> 00:38:06,338 Hands originally evolved to swing from trees are used 308 00:38:06,483 --> 00:38:10,442 with clever minds to fashion and manipulate tools. 309 00:38:25,936 --> 00:38:27,995 They learn by watching when they are young. 310 00:38:28,538 --> 00:38:31,336 Down the generations the skill is passed on. 311 00:38:35,645 --> 00:38:38,512 Though a short delicate twig is needed to tease out termites 312 00:38:38,648 --> 00:38:41,412 safari ants need a different technique 313 00:38:41,551 --> 00:38:45,282 a long stick and a good tolerance to vicious bites. 314 00:39:00,470 --> 00:39:03,371 Sometimes it helps to approach from off the ground. 315 00:39:29,933 --> 00:39:33,892 If you're smart, then life in the forest is that little bit easier. 316 00:39:45,815 --> 00:39:49,512 When it comes to making tools, we humans are the masters. 317 00:40:06,169 --> 00:40:12,301 This three metre stick is called an auger, specially designed to dig for yams. 318 00:40:16,179 --> 00:40:18,238 The yam tuber is deep underground. 319 00:40:19,216 --> 00:40:20,877 But not too deep for the auger. 320 00:40:24,721 --> 00:40:27,053 It's not all bad for the yam, however. 321 00:40:27,190 --> 00:40:30,956 The Bayaka leave the tip of the tuba in the ground to grow again. 322 00:40:31,595 --> 00:40:36,464 In a few years they'll come back to this very spot and harvest the reborn root. 323 00:40:45,609 --> 00:40:48,908 Back in the hunting camp the tubers are boiled and eaten. 324 00:40:52,282 --> 00:40:53,681 This is the only source of starch that 325 00:40:53,817 --> 00:40:56,581 the Bayaka people regularly get from the forest. 326 00:40:56,953 --> 00:40:58,511 So it's well worth the effort. 327 00:41:09,332 --> 00:41:12,790 The lives of these people are totally intertwined with the forest. 328 00:41:15,338 --> 00:41:18,000 They have developed technology to reach into the canopy, 329 00:41:18,141 --> 00:41:19,972 to dig far underground. 330 00:41:20,844 --> 00:41:24,507 They use the wood of the trees and even the chemistry of the forest... 331 00:41:30,387 --> 00:41:34,551 The sap from a vine called 'mbango' is squeezed in a special press, 332 00:41:34,691 --> 00:41:36,625 to tip the crossbow arrows. 333 00:41:38,094 --> 00:41:42,690 A scratch of this oily concentrate to the skin can cause a fatal heart attack. 334 00:41:53,877 --> 00:41:55,606 Over the years the Bakaya have discovered 335 00:41:55,745 --> 00:41:59,272 a whole range of complex compounds from plants 336 00:41:59,416 --> 00:42:02,214 science is only just beginning to catch up. 337 00:42:14,698 --> 00:42:17,633 And whilst one preparation may cause instant death, 338 00:42:17,834 --> 00:42:20,234 another is intentionally cut into the skin 339 00:42:20,370 --> 00:42:22,702 to cure headaches and diarrhoea 340 00:42:22,839 --> 00:42:25,808 the very poisons that plants use to defend themselves 341 00:42:25,909 --> 00:42:28,503 are the tools of a good forest pharmacist. 342 00:42:29,679 --> 00:42:31,647 His knowledge could even hold the future cures 343 00:42:31,848 --> 00:42:34,214 for our modern diseases. 344 00:42:43,226 --> 00:42:45,717 Though the Bakaya survive with great ingenuity, 345 00:42:45,862 --> 00:42:47,955 their impact on the forest is small. 346 00:42:48,998 --> 00:42:51,831 But there is one animal whose quest for survival here 347 00:42:51,968 --> 00:42:55,335 can alter the very nature of the forest itself. 348 00:42:59,609 --> 00:43:01,076 In a place called Dzanga Bai, 349 00:43:01,211 --> 00:43:05,875 in the Central African Republic it has carved out islands in a sea of green. 350 00:43:14,824 --> 00:43:16,792 Over the ages the padding of its feet 351 00:43:16,926 --> 00:43:19,588 through the undergrowth has changed the forest. 352 00:43:30,673 --> 00:43:34,074 There are a few rare places in the forest where precious salts 353 00:43:34,210 --> 00:43:36,542 and minerals are hidden in the ground. 354 00:43:38,181 --> 00:43:39,205 Every day, for generations, 355 00:43:39,349 --> 00:43:43,979 elephants have travelled to clearings like Dzanga Bai, to take the salts. 356 00:43:56,065 --> 00:43:57,828 No one quite knows what's here 357 00:43:57,901 --> 00:44:00,335 antidotes to plant toxins and minerals, 358 00:44:00,470 --> 00:44:02,961 essential for health, have both been discovered. 359 00:44:06,509 --> 00:44:08,170 But through studying these clearings, 360 00:44:08,311 --> 00:44:11,405 a bigger truth about elephants is being revealed. 361 00:44:15,652 --> 00:44:19,611 2800 individuals visit this one clearing. 362 00:44:21,157 --> 00:44:25,059 Half of Africa's elephants are now thought to live in the rainforest. 363 00:44:25,829 --> 00:44:28,798 They have a huge impact, not only spreading seeds, 364 00:44:28,932 --> 00:44:31,457 but opening up the forest for other animals. 365 00:44:33,303 --> 00:44:38,570 These places are oases of tranquillity havens for all manner of African beauty. 366 00:44:45,748 --> 00:44:46,715 Parrots. 367 00:44:52,255 --> 00:44:53,620 The rare Bongo. 368 00:44:56,893 --> 00:45:00,260 All around are animals breaking away from the protection of the trees 369 00:45:00,396 --> 00:45:02,523 to get a share of mineral goodness. 370 00:45:07,470 --> 00:45:10,769 In the dark forest it's difficult to even see another animal, 371 00:45:11,074 --> 00:45:12,200 let alone meet it. 372 00:45:13,009 --> 00:45:13,873 But in clearings, 373 00:45:14,010 --> 00:45:18,379 even the shyest can come out into the open for a chance to socialise. 374 00:45:23,253 --> 00:45:25,187 The Western Lowland gorilla. 375 00:45:27,223 --> 00:45:30,283 For years, less well known than its mountain cousins. 376 00:45:31,160 --> 00:45:32,821 Only through the discovery of clearings 377 00:45:32,962 --> 00:45:36,090 are we now finally getting to know this animal. 378 00:45:37,934 --> 00:45:41,802 There are over a hundred thousand hiding in these forests. 379 00:45:50,346 --> 00:45:52,906 They, too, visit clearings for their minerals, 380 00:45:53,049 --> 00:45:58,043 but in doing so they come together, to cement relationships, 381 00:45:58,187 --> 00:46:01,554 to dispute dominance - to play. 382 00:46:06,129 --> 00:46:09,565 And as these gorillas move out from the protection of the forest, 383 00:46:09,699 --> 00:46:12,793 they remind us of a much older migration. 384 00:46:14,871 --> 00:46:18,637 Six million years ago the African forest was retreating, 385 00:46:18,808 --> 00:46:22,904 overtaken by a brighter world of woods and grasslands. 386 00:46:25,648 --> 00:46:27,639 Many species emerged from the forest; 387 00:46:27,817 --> 00:46:30,012 to seek opportunities in this new world... 388 00:46:30,453 --> 00:46:34,787 among them a highly sophisticated ape our ancestors. 389 00:46:43,833 --> 00:46:49,396 Man began as a forest ape but became fully human in the new world beyond. 390 00:46:55,845 --> 00:46:59,440 Over time we humans returned to our ancestral home... 391 00:46:59,949 --> 00:47:01,280 like the Bayaka. 392 00:47:03,820 --> 00:47:08,553 'Etu' tells the story of how her people came to the forest to gather honey. 393 00:47:20,937 --> 00:47:23,906 The stories tell of a dream time when their ancestors 394 00:47:24,040 --> 00:47:27,407 evolved the skills to make a home in the forest. 395 00:47:32,815 --> 00:47:35,306 For animals and humans alike it is time 396 00:47:35,451 --> 00:47:38,249 that has given the best opportunities here. 397 00:47:50,233 --> 00:47:54,795 As the African rainforest has adapted to the climate, it has changed. 398 00:47:57,473 --> 00:48:01,967 An infinite number of trees has fallen, clearings have come and gone... 399 00:48:04,113 --> 00:48:06,138 ...rivers have snaked and moved 400 00:48:06,282 --> 00:48:09,649 and grasslands have been repeatedly swallowed and reborn. 401 00:48:12,488 --> 00:48:15,889 With every change there is a new chance for life 402 00:48:16,459 --> 00:48:20,190 here in the green heart of Africa.