All language subtitles for A Star Is Born - 5

af Afrikaans
ak Akan
sq Albanian
am Amharic
ar Arabic
hy Armenian
az Azerbaijani
eu Basque
be Belarusian
bem Bemba
bn Bengali
bh Bihari
bs Bosnian
br Breton
bg Bulgarian
km Cambodian
ca Catalan
ceb Cebuano
chr Cherokee
ny Chichewa
zh-CN Chinese (Simplified)
zh-TW Chinese (Traditional)
co Corsican
hr Croatian
cs Czech
da Danish
nl Dutch
en English
eo Esperanto
et Estonian
ee Ewe
fo Faroese
tl Filipino
fi Finnish
fr French
fy Frisian
gaa Ga
gl Galician
ka Georgian
de German
el Greek
gn Guarani
gu Gujarati
ht Haitian Creole
ha Hausa
haw Hawaiian
iw Hebrew
hi Hindi
hmn Hmong
hu Hungarian
is Icelandic
ig Igbo
id Indonesian
ia Interlingua
ga Irish
it Italian
ja Japanese
jw Javanese
kn Kannada
kk Kazakh
rw Kinyarwanda
rn Kirundi
kg Kongo
ko Korean
kri Krio (Sierra Leone)
ku Kurdish
ckb Kurdish (Soranî)
ky Kyrgyz
lo Laothian
la Latin
lv Latvian
ln Lingala
lt Lithuanian
loz Lozi
lg Luganda
ach Luo
lb Luxembourgish
mk Macedonian
mg Malagasy
ms Malay
ml Malayalam
mt Maltese
mi Maori
mr Marathi
mfe Mauritian Creole
mo Moldavian
mn Mongolian
my Myanmar (Burmese)
sr-ME Montenegrin
ne Nepali
pcm Nigerian Pidgin
nso Northern Sotho
no Norwegian
nn Norwegian (Nynorsk)
oc Occitan
or Oriya
om Oromo
ps Pashto
fa Persian
pl Polish
pt-BR Portuguese (Brazil)
pt Portuguese (Portugal) Download
pa Punjabi
qu Quechua
ro Romanian
rm Romansh
nyn Runyakitara
ru Russian
sm Samoan
gd Scots Gaelic
sr Serbian
sh Serbo-Croatian
st Sesotho
tn Setswana
crs Seychellois Creole
sn Shona
sd Sindhi
si Sinhalese
sk Slovak
sl Slovenian
so Somali
es Spanish
es-419 Spanish (Latin American)
su Sundanese
sw Swahili
sv Swedish
tg Tajik
ta Tamil
tt Tatar
te Telugu
th Thai
ti Tigrinya
to Tonga
lua Tshiluba
tum Tumbuka
tr Turkish
tk Turkmen
tw Twi
ug Uighur
uk Ukrainian
ur Urdu
uz Uzbek
vi Vietnamese
cy Welsh
wo Wolof
xh Xhosa
yi Yiddish
yo Yoruba
zu Zulu
Would you like to inspect the original subtitles? These are the user uploaded subtitles that are being translated: 1 00:00:03,120 --> 00:00:06,920 The natural world is full of extraordinary animals with 2 00:00:06,920 --> 00:00:09,840 amazing life histories. 3 00:00:09,840 --> 00:00:13,760 Yet certain stories are more intriguing than most. 4 00:00:16,080 --> 00:00:19,720 The mysteries of a butterfly's life cycle, 5 00:00:19,720 --> 00:00:23,680 or the strange biology of the emperor penguin. 6 00:00:23,680 --> 00:00:26,480 Some of these creatures were surrounded by myth 7 00:00:26,480 --> 00:00:29,400 and misunderstandings for a very long time. 8 00:00:30,600 --> 00:00:33,920 And some have only recently revealed their secrets. 9 00:00:35,080 --> 00:00:38,920 These are the animals that stand out from the crowd, 10 00:00:38,920 --> 00:00:42,960 the curiosities I find most fascinating of all. 11 00:00:51,680 --> 00:00:54,880 Some of our most familiar animals puzzled scientific 12 00:00:54,880 --> 00:00:58,160 minds for a surprisingly long time. 13 00:00:58,160 --> 00:00:59,760 The mysterious comings 14 00:00:59,760 --> 00:01:03,520 and goings of barn swallows led to some far-fetched ideas. 15 00:01:05,480 --> 00:01:09,720 While the life cycle of the painted lady butterfly took centuries 16 00:01:09,720 --> 00:01:10,960 to unravel. 17 00:01:12,600 --> 00:01:14,760 But the abilities of some plants 18 00:01:14,760 --> 00:01:19,880 and animals are so remarkable that they seem to be almost supernatural. 19 00:01:19,880 --> 00:01:24,360 In this programme, I investigate the shocking power of a fish that 20 00:01:24,360 --> 00:01:27,680 advanced our understanding of electricity, 21 00:01:27,680 --> 00:01:31,560 and plants with senses that are surprising modern science. 22 00:01:33,520 --> 00:01:37,040 How do these extraordinary powers help the organisms that 23 00:01:37,040 --> 00:01:38,840 produced them? 24 00:01:45,960 --> 00:01:49,760 The freshwater eel is surrounded by legends. 25 00:01:49,760 --> 00:01:53,600 The first Europeans to explore the New World heard amazing 26 00:01:53,600 --> 00:01:55,400 stories about it. 27 00:01:55,400 --> 00:01:58,920 And when, in the 18th century, specimens of this strange fish 28 00:01:58,920 --> 00:02:01,760 reached Europe, they created a sensation. 29 00:02:03,320 --> 00:02:07,160 In 1776, Captain George Baker, 30 00:02:07,160 --> 00:02:09,560 an American mariner and whaler, 31 00:02:09,560 --> 00:02:12,720 made the long and difficult journey from South America across a 32 00:02:12,720 --> 00:02:18,160 raging Atlantic Ocean to bring five live electric eels to London. 33 00:02:18,160 --> 00:02:21,240 These are two of his actual eels. 34 00:02:22,520 --> 00:02:26,320 Captain Baker and his five electric eels, or gymnotas as they were known, 35 00:02:26,320 --> 00:02:30,080 set up shop in the Haymarket and offered two shillings 36 00:02:30,080 --> 00:02:34,160 and sixpence for a shock, or five shillings for a spark. 37 00:02:36,600 --> 00:02:39,160 Baker's eels had come all the way from the lower 38 00:02:39,160 --> 00:02:42,040 reaches of the Amazon and Orinoco rivers, 39 00:02:42,040 --> 00:02:47,280 where he had heard tales from the locals about their astonishing powers. 40 00:02:47,280 --> 00:02:51,400 They called these fish "trembladores". 41 00:02:51,400 --> 00:02:55,480 Humboldt, the famous naturalist and explorer, had described how he 42 00:02:55,480 --> 00:02:59,720 had witnessed horses being killed by the repeated shocks from these fish. 43 00:03:01,080 --> 00:03:03,520 And he himself accidentally stepped on one 44 00:03:03,520 --> 00:03:05,520 and vividly described the effect. 45 00:03:06,840 --> 00:03:10,920 "With each stroke, you feel an internal vibration that lasts 46 00:03:10,920 --> 00:03:14,720 "two or three seconds, followed by a painful numbness. 47 00:03:14,720 --> 00:03:18,840 "All day I felt strong pain in my knees and in all my joints." 48 00:03:21,600 --> 00:03:25,280 I encountered this remarkable fish in its natural environment 49 00:03:25,280 --> 00:03:29,400 when I filmed at the same rivers that Humboldt explored. 50 00:03:29,400 --> 00:03:31,600 There was talk of me swimming with the eel, 51 00:03:31,600 --> 00:03:35,200 but thankfully we had some technical difficulties with the diving 52 00:03:35,200 --> 00:03:37,600 equipment that I was supposed to wear, 53 00:03:37,600 --> 00:03:41,240 and so I stayed safely in a canoe and was able to demonstrate 54 00:03:41,240 --> 00:03:44,960 another subtler, but equally remarkable, side to this fish. 55 00:03:47,480 --> 00:03:52,040 The eels were constantly producing electric discharges. 56 00:03:52,040 --> 00:03:56,280 Somehow they were generating a small, nonstop flowing current. 57 00:03:56,280 --> 00:03:58,880 ELECTRIC DRONE 58 00:03:58,880 --> 00:04:01,680 They were also able to sense electricity and were 59 00:04:01,680 --> 00:04:06,280 attracted to electrical pulses emitted from my underwater detector, 60 00:04:06,280 --> 00:04:11,000 suggesting that electricity plays a key role in their lives. 61 00:04:12,720 --> 00:04:14,760 But at the time of their discovery, 62 00:04:14,760 --> 00:04:18,520 no-one knew the full functions of their extraordinary abilities. 63 00:04:20,840 --> 00:04:24,560 We now know that the shock was caused by electricity, 64 00:04:24,560 --> 00:04:29,480 and I can demonstrate it by touching the animal with an electrode. 65 00:04:29,480 --> 00:04:31,000 Watch. 66 00:04:31,000 --> 00:04:33,920 There. You see? 67 00:04:33,920 --> 00:04:36,520 The scope and the lights are flashing up and down. 68 00:04:36,520 --> 00:04:38,040 Extraordinary. 69 00:04:38,040 --> 00:04:42,080 But this is only a small indication of the real power of this fish. 70 00:04:42,080 --> 00:04:44,440 If I were to try and pick it up, I could get 71 00:04:44,440 --> 00:04:49,160 a jolt of an astonishing 600 volts, which is quite enough to kill me. 72 00:04:57,320 --> 00:05:01,680 This 1960s educational film illustrated the shock, 73 00:05:01,680 --> 00:05:04,160 even though the equipment used prevented 74 00:05:04,160 --> 00:05:07,240 the volunteers from getting its full power. 75 00:05:07,240 --> 00:05:10,880 They were to join hands and then connected to a live eel. 76 00:05:12,120 --> 00:05:15,280 WOMAN SCREAMS 77 00:05:16,360 --> 00:05:20,400 Firm believers in electric eels. Thank you very much. 78 00:05:21,640 --> 00:05:24,640 You can imagine how startling Baker's electric eels 79 00:05:24,640 --> 00:05:26,600 were 200 years ago. 80 00:05:29,320 --> 00:05:30,800 In the 18th century, 81 00:05:30,800 --> 00:05:33,720 electricity was becoming one of the most fashionable areas 82 00:05:33,720 --> 00:05:38,080 of scientific investigation, but it was still very poorly understood. 83 00:05:38,080 --> 00:05:41,920 Very few advances had been made since its discovery 150 years 84 00:05:41,920 --> 00:05:45,960 earlier by Elizabeth I's personal physician, William Gilbert. 85 00:05:45,960 --> 00:05:50,120 Gilbert repeated a trick that had been known about since Greek times. 86 00:05:50,120 --> 00:05:54,120 Rubbing a piece of amber with cat fur, that allowed the amber 87 00:05:54,120 --> 00:05:58,040 to attract a small object like a feather. Let's give it a try. 88 00:05:58,040 --> 00:05:59,920 Here is a bit of amber. 89 00:06:03,280 --> 00:06:04,680 There. 90 00:06:04,680 --> 00:06:07,760 It had always been assumed that this amber effect was caused 91 00:06:07,760 --> 00:06:11,520 by magnetism but Gilbert showed that it was something different. 92 00:06:11,520 --> 00:06:15,760 He named this new force after the Greek word for amber, 93 00:06:15,760 --> 00:06:20,200 electron, and so electricity was born. 94 00:06:21,520 --> 00:06:26,520 Londoners of the time developed a fascination for this magical force. 95 00:06:26,520 --> 00:06:31,720 Showmen staged bizarre spectacles to demonstrate its properties. 96 00:06:31,720 --> 00:06:35,040 In one, a young boy attached to a friction generator 97 00:06:35,040 --> 00:06:37,960 attracted small pieces of paper to his hands. 98 00:06:37,960 --> 00:06:42,040 In another, a gentleman kissed a lady and was repulsed 99 00:06:42,040 --> 00:06:45,360 by the charge carried through her whalebone corset. 100 00:06:46,760 --> 00:06:49,520 No-one knew what to do with electricity 101 00:06:49,520 --> 00:06:53,200 but a better understanding of its nature was slowly emerging. 102 00:06:54,200 --> 00:06:56,760 More and more ingenious ways were developed 103 00:06:56,760 --> 00:07:00,520 to create what we now call static electricity. 104 00:07:00,520 --> 00:07:04,040 And soon it became something more than just a quirk of rubbing amber, 105 00:07:04,040 --> 00:07:06,440 it became visible as a spark. 106 00:07:11,040 --> 00:07:14,520 The ability to produce this characteristic blue spark 107 00:07:14,520 --> 00:07:17,760 along with its invigorating smell became the signature 108 00:07:17,760 --> 00:07:21,520 of this new force and it prompted scientists to make 109 00:07:21,520 --> 00:07:24,800 obvious comparisons with other natural phenomena. 110 00:07:24,800 --> 00:07:26,840 THUNDER 111 00:07:28,760 --> 00:07:32,040 In the American colonies, Benjamin Franklin bravely, 112 00:07:32,040 --> 00:07:36,760 or perhaps foolishly, flew kites into thunderstorms and proved that 113 00:07:36,760 --> 00:07:40,160 lightning and the electric spark were one and the same. 114 00:07:41,160 --> 00:07:45,160 But there's another common property of lightning and static electricity. 115 00:07:45,160 --> 00:07:47,520 That is the ability to shock. 116 00:07:47,520 --> 00:07:51,280 It wasn't long before a comparison was made between the shock from 117 00:07:51,280 --> 00:07:55,200 the early generators and the shock that could be delivered by a fish. 118 00:07:58,040 --> 00:08:00,760 The electric eel wasn't the only kind of fish 119 00:08:00,760 --> 00:08:03,400 known to give humans a powerful jolt. 120 00:08:03,400 --> 00:08:07,280 The ancient Egyptians knew that the electric catfish could also 121 00:08:07,280 --> 00:08:11,040 give shocks and they called it the "Thunderer of the Nile". 122 00:08:12,320 --> 00:08:17,040 And in the nearby Mediterranean lives the torpedo ray. 123 00:08:17,040 --> 00:08:19,760 Its muscle batteries make it so bulky 124 00:08:19,760 --> 00:08:22,760 it can't undulate its body like other rays 125 00:08:22,760 --> 00:08:26,040 but has to propel itself by waving its tail. 126 00:08:26,040 --> 00:08:28,040 Like the electric eel, 127 00:08:28,040 --> 00:08:32,520 it uses its discharge to stun the other fish on which it prays. 128 00:08:34,560 --> 00:08:38,520 Sadly, the pressure of celebrity and having to produce shocks 129 00:08:38,520 --> 00:08:42,520 and sparks to order exhausted Baker's long-suffering eels 130 00:08:42,520 --> 00:08:44,760 and they didn't last the winter. 131 00:08:44,760 --> 00:08:49,040 But two were preserved and expertly dissected by John Hunter, 132 00:08:49,040 --> 00:08:52,040 a very distinguished Scottish surgeon of the time 133 00:08:52,040 --> 00:08:56,520 and he found a great number of striped muscular layers 134 00:08:56,520 --> 00:08:59,640 that proved to be where the electricity was generated. 135 00:08:59,640 --> 00:09:03,680 They are now referred to as Hunter's organs. 136 00:09:04,680 --> 00:09:08,680 He found these muscles along the tail and sides of the eels 137 00:09:08,680 --> 00:09:10,520 arranged in stacks. 138 00:09:12,040 --> 00:09:15,280 One scientist called Galvani believed that animals 139 00:09:15,280 --> 00:09:20,280 had their own natural electricity even without these electric organs 140 00:09:20,280 --> 00:09:25,040 and he tried to prove this by connecting wires to frogs' legs 141 00:09:25,040 --> 00:09:27,040 and making them twitch. 142 00:09:27,040 --> 00:09:31,040 He called this phenomenon animal electricity. 143 00:09:32,760 --> 00:09:36,760 But another scientist called Volta had other ideas. 144 00:09:36,760 --> 00:09:40,760 He proved that the frog was merely a conductor for electricity 145 00:09:40,760 --> 00:09:42,760 with a simple experiment. 146 00:09:43,760 --> 00:09:48,040 Volta replaced Galvani's frog with discs of cloth 147 00:09:48,040 --> 00:09:50,280 soaked in saltwater or acid 148 00:09:50,280 --> 00:09:53,280 and sandwiched them between two different metals. 149 00:09:53,280 --> 00:09:56,040 I can do the same thing with filter paper, 150 00:09:56,040 --> 00:10:01,040 copper two pence pieces and these simple galvanised zinc washers. 151 00:10:01,040 --> 00:10:02,320 Watch. 152 00:10:04,320 --> 00:10:06,040 Tuppenny piece. 153 00:10:07,040 --> 00:10:08,760 Filter. 154 00:10:08,760 --> 00:10:10,560 And washer. 155 00:10:14,040 --> 00:10:16,520 There, nearly 0.6 of a volt. 156 00:10:17,520 --> 00:10:21,280 But the amount of electricity generated was tiny. 157 00:10:21,280 --> 00:10:25,040 Certainly not enough to make the sparks seen from eels. 158 00:10:25,040 --> 00:10:28,520 Unlike Galvani, Volta saw no distinction 159 00:10:28,520 --> 00:10:32,760 between animal electricity and his new electricity from metals 160 00:10:32,760 --> 00:10:37,760 so he now looked at animals to see how he might amplify his new device. 161 00:10:40,520 --> 00:10:43,040 Was it significant that the muscles 162 00:10:43,040 --> 00:10:47,280 producing the electric power in the eels were arranged in stacks? 163 00:10:49,040 --> 00:10:54,040 Volta decided to add more stacks to his electric pile. 164 00:10:54,040 --> 00:10:57,280 We call this way of connecting electric cells together 165 00:10:57,280 --> 00:11:01,280 "in series", and we now know that it increases the voltage. 166 00:11:01,280 --> 00:11:04,520 But Volta was about to find this out for the first time. 167 00:11:04,520 --> 00:11:07,280 He piled up his tiny cells like the bands of muscle 168 00:11:07,280 --> 00:11:08,800 in an electric fish. 169 00:11:08,800 --> 00:11:11,000 Here I've got ten pairs. 170 00:11:11,000 --> 00:11:12,600 And just watch. 171 00:11:15,040 --> 00:11:16,800 Nearly six volts. 172 00:11:16,800 --> 00:11:18,040 Wonderful. 173 00:11:18,040 --> 00:11:22,280 Volta could now produce heat, shocks and even sparks 174 00:11:22,280 --> 00:11:27,360 from electricity in a continuous never-ending stream. 175 00:11:28,760 --> 00:11:33,440 He had made the first battery, partly inspired by the electric eel. 176 00:11:34,440 --> 00:11:38,040 The pieces of the puzzle had come together and the eel's example 177 00:11:38,040 --> 00:11:41,760 had helped to advance our understanding of electricity. 178 00:11:42,760 --> 00:11:45,760 Eels, in fact, contain natural batteries. 179 00:11:45,760 --> 00:11:48,040 Stacks of special muscles. 180 00:11:49,640 --> 00:11:52,520 It's amazing to think when electricity is so much 181 00:11:52,520 --> 00:11:55,760 a part of our lives today that before Volta 182 00:11:55,760 --> 00:11:59,040 the only source of electricity was lightning, 183 00:11:59,040 --> 00:12:01,280 a few static generators 184 00:12:01,280 --> 00:12:04,760 and fish like this incredible electric eel. 185 00:12:09,040 --> 00:12:13,520 Understanding how electric eels managed to find their way around 186 00:12:13,520 --> 00:12:16,760 revealed a hitherto unknown animal sense. 187 00:12:18,360 --> 00:12:21,440 But it's not just animals that have surprised us. 188 00:12:22,440 --> 00:12:25,280 We're now discovering that plants too 189 00:12:25,280 --> 00:12:29,040 have intriguing abilities that are still mysterious. 190 00:12:32,040 --> 00:12:35,760 We think of plants as passive, still and silent. 191 00:12:35,760 --> 00:12:39,920 But they may have more in common with animals than you might think. 192 00:12:44,760 --> 00:12:48,520 New research suggests that they have surprising abilities. 193 00:12:48,520 --> 00:12:51,360 It depends on how you look at them. 194 00:12:53,800 --> 00:12:57,240 I first started seeing plants in a different light 195 00:12:57,240 --> 00:13:00,760 when making a series called The Private Life of Plants. 196 00:13:01,760 --> 00:13:06,040 We used time-lapse photography to reveal the way they move. 197 00:13:07,040 --> 00:13:10,520 The bramble spreads aggressively - seemingly unstoppable. 198 00:13:11,520 --> 00:13:15,280 Other plants pulsed to the rhythms of day and night. 199 00:13:15,280 --> 00:13:18,800 And flower buds explode like fireworks. 200 00:13:21,560 --> 00:13:25,240 So, with speeded up film, we had been able to translate 201 00:13:25,240 --> 00:13:27,040 their time into ours 202 00:13:27,040 --> 00:13:30,520 and to realise that they're constantly on the move. 203 00:13:37,280 --> 00:13:41,520 200 years ago, one plant that moved very quickly indeed 204 00:13:41,520 --> 00:13:45,480 attracted the attention of a great scientific mind. 205 00:13:45,480 --> 00:13:48,040 It appeared to behave like an animal 206 00:13:48,040 --> 00:13:51,920 and could move fast enough to catch its own food. 207 00:13:52,920 --> 00:13:56,600 Charles Darwin was fascinated by the Venus flytrap. 208 00:13:56,600 --> 00:14:00,680 He called it one of the most wonderful plants in the world. 209 00:14:00,680 --> 00:14:04,280 He recognised that it could move in a very different way 210 00:14:04,280 --> 00:14:06,560 to that of plant growth. 211 00:14:06,560 --> 00:14:10,080 This movement was not only fast but also repeatable. 212 00:14:10,080 --> 00:14:12,520 Darwin experimented and found that the traps 213 00:14:12,520 --> 00:14:14,280 are not triggered by raindrops 214 00:14:14,280 --> 00:14:18,280 but only by a very particular stimulation of the leaf hairs, 215 00:14:18,280 --> 00:14:20,480 such as an insect might make. 216 00:14:20,480 --> 00:14:25,520 But what intrigued him most was the speed of the reaction. 217 00:14:25,520 --> 00:14:29,480 He sent one of these flytraps to a friend, Dr Burdon-Sanderson, 218 00:14:29,480 --> 00:14:33,520 who was performing groundbreaking work on muscles and electricity. 219 00:14:33,520 --> 00:14:37,520 His tests confirmed that the tiny electrical discharge 220 00:14:37,520 --> 00:14:41,520 caused by an animal muscle cell contracting was almost identical 221 00:14:41,520 --> 00:14:45,520 to those signals obtained by attaching electrodes to the flytrap 222 00:14:45,520 --> 00:14:47,280 when it was shutting. 223 00:14:48,280 --> 00:14:50,520 Although plants have no muscles, 224 00:14:50,520 --> 00:14:55,040 electrical stimulation enables them to move in a similar way to animals. 225 00:14:57,040 --> 00:15:01,200 Electrical signals cause cells to change the pressure of sap 226 00:15:01,200 --> 00:15:04,040 in their leaves, so creating movement. 227 00:15:05,040 --> 00:15:08,320 As a result, some plants, like animals, 228 00:15:08,320 --> 00:15:10,520 can actively catch their prey. 229 00:15:13,360 --> 00:15:18,320 Recently it's been discovered that other plants use electricity too 230 00:15:18,320 --> 00:15:20,280 but for a very different purpose. 231 00:15:22,960 --> 00:15:27,560 Plants are rooted to the ground and have a small negative charge. 232 00:15:27,560 --> 00:15:31,400 The higher up the plant you go, the greater the electric charge. 233 00:15:31,400 --> 00:15:34,720 This creates an electric field around the flower. 234 00:15:34,720 --> 00:15:39,080 We can't see it but these electrodes are picking up the energy 235 00:15:39,080 --> 00:15:43,080 of this tiny field and converting it into the sound that we can hear. 236 00:15:44,400 --> 00:15:48,040 Bees, on the other hand, have a positive charge. 237 00:15:48,040 --> 00:15:50,000 Friction whilst flying causes them 238 00:15:50,000 --> 00:15:54,200 to lose electrons, leaving them electrically charged. 239 00:15:54,200 --> 00:15:58,760 As a bee approaches a flower, the charge fields around the flower 240 00:15:58,760 --> 00:16:01,040 and the bee interact, and the sound changes... 241 00:16:01,040 --> 00:16:02,640 FALTERING ELECTRONIC BUZZ 242 00:16:02,640 --> 00:16:04,200 ..there. 243 00:16:04,200 --> 00:16:06,480 And when it lands, the positive 244 00:16:06,480 --> 00:16:10,120 and negative fields immediately cancel each other out. 245 00:16:10,120 --> 00:16:13,960 As this happens, there are two very surprising consequences. 246 00:16:13,960 --> 00:16:18,280 Firstly, the plant's negatively charged pollen actually 247 00:16:18,280 --> 00:16:22,520 jumps across onto the positively charged bee. 248 00:16:22,520 --> 00:16:26,440 Secondly, the plant has a changed electrical field 249 00:16:26,440 --> 00:16:30,160 and when another bee comes along, it detects this altered 250 00:16:30,160 --> 00:16:33,120 electrical signature and avoids the flower. 251 00:16:33,120 --> 00:16:37,680 The plant is, in effect, telling the bee that it has no nectar 252 00:16:37,680 --> 00:16:39,120 and to come back later. 253 00:16:40,880 --> 00:16:44,960 When the flower has refilled its stores of nectar, it creates 254 00:16:44,960 --> 00:16:49,760 a new electric charge which attracts another passing bee. 255 00:16:49,760 --> 00:16:54,960 This simple on/off signal benefits both the bee and the flower, 256 00:16:54,960 --> 00:16:57,240 but it does have its limitations. 257 00:16:58,360 --> 00:17:00,360 The electrical field is tiny, 258 00:17:00,360 --> 00:17:03,520 so insects can only detect it at close quarters. 259 00:17:04,920 --> 00:17:08,440 But flowers can also draw attention to themselves over much 260 00:17:08,440 --> 00:17:13,200 greater distances and they do this by floating messages in the air. 261 00:17:15,320 --> 00:17:18,720 The perfume of a flower is not just a pleasant smell, 262 00:17:18,720 --> 00:17:23,000 it's also the primary way in which plants communicate with insects. 263 00:17:23,000 --> 00:17:27,600 A rose can contain over 400 chemical compounds and a bee 264 00:17:27,600 --> 00:17:32,440 can recognise a particular combination from over a mile away. 265 00:17:32,440 --> 00:17:35,000 The very latest research has discovered 266 00:17:35,000 --> 00:17:39,080 that 90% of the chemicals made by plants, are also 267 00:17:39,080 --> 00:17:42,800 produced by insects and that is no coincidence. 268 00:17:45,960 --> 00:17:50,160 Most flowers produce scent to persuade insects to visit them, 269 00:17:51,640 --> 00:17:55,280 but others use it in a more sophisticated way... 270 00:17:55,280 --> 00:17:56,560 for protection. 271 00:17:57,800 --> 00:18:01,440 Cabbages communicate with each other using smell. 272 00:18:03,120 --> 00:18:06,520 When the leaves of one plant are being attacked by caterpillars, 273 00:18:06,520 --> 00:18:10,800 it releases a scent which warns its neighbours. 274 00:18:10,800 --> 00:18:14,280 They then produce chemicals in their leaves that caterpillars 275 00:18:14,280 --> 00:18:16,960 don't like and so they avoid being eaten. 276 00:18:18,360 --> 00:18:21,480 And scent also serves to call in the cavalry. 277 00:18:22,680 --> 00:18:26,800 Leaves that are under attack give off a chemical alarm signal that 278 00:18:26,800 --> 00:18:31,400 attracts wasps which obligingly pick off the caterpillar attackers. 279 00:18:35,280 --> 00:18:39,760 So, vegetables, fruits, leaves and flowers are constantly 280 00:18:39,760 --> 00:18:45,240 communicating with each other using touch, vision and smell. 281 00:18:45,240 --> 00:18:49,080 They seem to exploit all the senses, apart, that is, from hearing. 282 00:18:51,200 --> 00:18:55,520 But there are old stories that one particular plant is able to 283 00:18:55,520 --> 00:18:57,680 produce a very strange sound. 284 00:18:59,440 --> 00:19:03,200 Hundreds of years ago, a plant with a root that was thought to 285 00:19:03,200 --> 00:19:08,560 resemble a human body was said to emit a sound that could kill. 286 00:19:08,560 --> 00:19:10,920 The root was known to have strong anaesthetic 287 00:19:10,920 --> 00:19:14,800 and hallucinogenic properties. And in the first century AD, 288 00:19:14,800 --> 00:19:19,680 it was called a mandragora or mandrake as it's now known. 289 00:19:19,680 --> 00:19:23,000 It was associated with magic and the supernatural 290 00:19:23,000 --> 00:19:27,600 and was thought to derive power from a demon that emitted a dreadful 291 00:19:27,600 --> 00:19:30,080 and fatal shriek if the plant was uprooted. 292 00:19:31,080 --> 00:19:34,400 Fortunately, there were creative ways of avoiding 293 00:19:34,400 --> 00:19:36,160 death from the killer sound. 294 00:19:36,160 --> 00:19:39,080 One account advised plugging one's ears 295 00:19:39,080 --> 00:19:43,760 and then tying a starving dog to the mandrake plant. 296 00:19:43,760 --> 00:19:48,640 And then, as the dog lunged for food, the plant would be uprooted. 297 00:19:48,640 --> 00:19:51,600 The dog would tragically die from the mandrake's shriek 298 00:19:51,600 --> 00:19:53,880 but the man would survive. 299 00:19:56,520 --> 00:20:00,640 This particular story may have arisen because drinks made with 300 00:20:00,640 --> 00:20:03,640 the mandrake root can produce hallucinations. 301 00:20:07,760 --> 00:20:11,200 But we're just beginning to realise that the sensory abilities 302 00:20:11,200 --> 00:20:15,040 of a root could be as sophisticated as the rest of the plant. 303 00:20:20,800 --> 00:20:24,920 Latest research suggests that roots are communicating underground. 304 00:20:27,480 --> 00:20:31,320 And we now have the technology to eavesdrop on the roots' world. 305 00:20:34,200 --> 00:20:39,280 Believe it or not, the roots of these corn seedlings can make 306 00:20:39,280 --> 00:20:41,680 and sense sound. 307 00:20:41,680 --> 00:20:46,440 The noise is very quiet but we can hear it with this equipment, 308 00:20:46,440 --> 00:20:50,560 if I place a corn seedling in front of a laser beam Like this. 309 00:20:55,680 --> 00:20:59,200 Now the sound vibration can be detected 310 00:20:59,200 --> 00:21:01,120 and we can hear it through a speaker... 311 00:21:02,360 --> 00:21:03,920 CRACKLING 312 00:21:03,920 --> 00:21:05,400 ..there. 313 00:21:05,400 --> 00:21:10,240 That strange crackling is the sound of corn roots growing. 314 00:21:10,240 --> 00:21:13,400 It can be seen as pulses on the screen. 315 00:21:13,400 --> 00:21:16,840 It's been shown, too, that the corn roots respond to the sound 316 00:21:16,840 --> 00:21:19,080 when it's played back to them. 317 00:21:19,080 --> 00:21:22,560 Time-lapse footage shot over just a few hours clearly shows 318 00:21:22,560 --> 00:21:26,280 the roots growing towards the tiny speakers that emit the sound. 319 00:21:27,360 --> 00:21:29,040 There is much speculation 320 00:21:29,040 --> 00:21:32,080 about the purpose of this curious phenomenon. 321 00:21:32,080 --> 00:21:36,600 Perhaps it helps roots avoid growing into hard objects or being too 322 00:21:36,600 --> 00:21:39,160 close to competing plants. 323 00:21:39,160 --> 00:21:42,760 It could act like simple echolocation, 324 00:21:42,760 --> 00:21:46,280 we just don't know but it's the first clear evidence that 325 00:21:46,280 --> 00:21:49,280 plants have a rudimentary form of hearing 326 00:21:49,280 --> 00:21:53,760 and might even be communicating underground using sound. 327 00:21:53,760 --> 00:21:57,600 Sensitive equipment is creating a new window into the plant world 328 00:21:57,600 --> 00:22:00,960 and it seems that, like animals, they have a sophisticated 329 00:22:00,960 --> 00:22:04,880 sense of their environment and possess abilities that not 330 00:22:04,880 --> 00:22:08,560 so long ago, we would have thought of as supernatural. 331 00:22:16,840 --> 00:22:22,360 BIRDSONG 332 00:22:27,840 --> 00:22:29,800 Swallows have successfully nested 333 00:22:29,800 --> 00:22:33,000 and raised their young in this barn for several years. 334 00:22:33,000 --> 00:22:36,320 These chicks will soon leave the nest and make their first 335 00:22:36,320 --> 00:22:38,960 exploratory flights around the farm 336 00:22:38,960 --> 00:22:42,840 but in a few weeks' time they will suddenly vanish. 337 00:22:42,840 --> 00:22:44,800 Where do they go to? 338 00:22:44,800 --> 00:22:48,680 In the past, that gave rise to some extraordinary speculations. 339 00:22:48,680 --> 00:22:52,320 In fact, in the 18th century, it became a very long-running 340 00:22:52,320 --> 00:22:55,560 debate, headed by some well-known Church figures. 341 00:22:57,360 --> 00:23:00,480 And swallows are not the only birds that appear 342 00:23:00,480 --> 00:23:03,680 and disappear with the changing seasons. 343 00:23:03,680 --> 00:23:07,880 For centuries, people speculated about where such birds go. 344 00:23:07,880 --> 00:23:12,760 One explanation was that some birds changed into others by growing 345 00:23:12,760 --> 00:23:15,160 different adult plumage. 346 00:23:15,160 --> 00:23:18,960 Perhaps the redstart turned into a robin... 347 00:23:20,800 --> 00:23:23,840 ..or the garden warbler into a blackcap. 348 00:23:24,960 --> 00:23:28,200 Since these species where seldom present at the same time 349 00:23:28,200 --> 00:23:30,880 the explanation seemed entirely plausible. 350 00:23:35,040 --> 00:23:37,560 The barnacle goose was another mystery. 351 00:23:39,640 --> 00:23:42,280 Each winter, huge, noisy flocks of them 352 00:23:42,280 --> 00:23:45,960 appear on European shores, apparently from out of nowhere. 353 00:23:47,920 --> 00:23:51,760 No-one had ever seen them build a nest or raise young. 354 00:23:56,920 --> 00:24:01,520 The barnacle goose gave rise to some extraordinary folklore as this 355 00:24:01,520 --> 00:24:04,400 mediaeval illustration shows. 356 00:24:04,400 --> 00:24:08,360 It was thought that the geese grew on underwater trees, 357 00:24:08,360 --> 00:24:13,880 starting life as small marine creatures called goose barnacles. 358 00:24:13,880 --> 00:24:16,640 Goose barnacles do, of course, exist, they're small 359 00:24:16,640 --> 00:24:20,600 shelled marine organisms with what looks like the head, 360 00:24:20,600 --> 00:24:25,600 which is in fact enclosed by a shell, attached by a stalk, which 361 00:24:25,600 --> 00:24:30,840 was thought to resemble the neck of a bird, to a bit of wood or a rock. 362 00:24:33,760 --> 00:24:37,560 The confusion about the nature of the barnacle goose was put to 363 00:24:37,560 --> 00:24:39,800 good use by some. 364 00:24:39,800 --> 00:24:41,760 Since it was unclear whether it was a bird, 365 00:24:41,760 --> 00:24:44,360 a fish or some other creature, you could surely be 366 00:24:44,360 --> 00:24:48,400 allowed to eat it on days when meat was forbidden by the church. 367 00:24:50,600 --> 00:24:53,960 But the most commonly held belief was that birds 368 00:24:53,960 --> 00:24:56,920 disappear in winter because they hibernated. 369 00:24:58,080 --> 00:25:01,760 Swallows and their close relatives, the swifts and martins, 370 00:25:01,760 --> 00:25:06,120 were thought to do so in mud at the bottom of ponds and rivers 371 00:25:06,120 --> 00:25:09,680 and it's easy to see how this idea originated 372 00:25:09,680 --> 00:25:13,760 because the birds spent much of their time near water, skimming low 373 00:25:13,760 --> 00:25:16,640 over the surface, hunting for insects or taking a drink. 374 00:25:18,720 --> 00:25:22,920 It wasn't until the Middle Ages that another theory was proposed that 375 00:25:22,920 --> 00:25:25,480 some birds may migrate 376 00:25:25,480 --> 00:25:30,120 and one of its strongest proponents was an influential religious leader. 377 00:25:32,720 --> 00:25:37,080 Frederick the second of Hohenstaufen was a powerful holy 378 00:25:37,080 --> 00:25:40,960 Roman Emperor and known for his unorthodox views. 379 00:25:40,960 --> 00:25:43,440 He ignored the philosophy of the Church 380 00:25:43,440 --> 00:25:47,560 and based his knowledge of natural history on direct observation 381 00:25:47,560 --> 00:25:50,040 rather than what was ordained. 382 00:25:50,040 --> 00:25:54,040 Frederick was also a keen falconer and he wrote this book, 383 00:25:54,040 --> 00:25:56,320 The Art Of Falconry, 384 00:25:56,320 --> 00:25:58,400 and in it, surprisingly, 385 00:25:58,400 --> 00:26:02,600 there are entire chapters on the migration of birds. 386 00:26:02,600 --> 00:26:04,760 His confidence came from the fact that, 387 00:26:04,760 --> 00:26:07,640 unlike his contemporaries and those before him, 388 00:26:07,640 --> 00:26:11,640 he had actually observed birds in the field for himself. 389 00:26:11,640 --> 00:26:13,960 He had no doubt about the migration and so, 390 00:26:13,960 --> 00:26:17,920 little patience for the myths surrounding the barnacle goose. 391 00:26:17,920 --> 00:26:20,680 He considered the story to be quite ridiculous 392 00:26:20,680 --> 00:26:24,080 and argued that the birds simply breed in distant lands. 393 00:26:26,760 --> 00:26:31,360 His views started a debate that split people into two camps, 394 00:26:31,360 --> 00:26:34,000 those believing in the old hibernation theory 395 00:26:34,000 --> 00:26:37,800 and those who supported the idea that birds migrate. 396 00:26:38,840 --> 00:26:43,640 This was the start of a new era which was to sweep away myths 397 00:26:43,640 --> 00:26:47,920 and focus instead on facts and careful observation. 398 00:26:47,920 --> 00:26:52,840 Across Europe, the evidence for bird migration started to accumulate. 399 00:26:54,760 --> 00:26:58,000 In Germany, a 12th century monk is said to have taken 400 00:26:58,000 --> 00:27:02,080 a swallow from its nest and attached a parchment note to its leg 401 00:27:02,080 --> 00:27:05,920 that read, "Oh, swallow, where do you live in winter?" 402 00:27:07,640 --> 00:27:10,920 The following spring the bird returned with a note saying, 403 00:27:10,920 --> 00:27:14,080 "In Asia, in the home of Petrus, that is Israel." 404 00:27:16,400 --> 00:27:20,320 The story may not have been true, but it certainly gave the right hint. 405 00:27:24,560 --> 00:27:29,200 In the early 16th century, a Bishop from Sweden called 406 00:27:29,200 --> 00:27:35,040 Olaus Magnus reignited the debate about swallows with this picture. 407 00:27:35,040 --> 00:27:38,640 He claimed that in winter, fishermen often drew up 408 00:27:38,640 --> 00:27:42,920 swallows in their nets, hanging together in a mass. 409 00:27:42,920 --> 00:27:45,800 This astonishing assertion provided ample fuel 410 00:27:45,800 --> 00:27:49,640 for the anti-migration lobby and, unlikely as it was, 411 00:27:49,640 --> 00:27:52,560 the view that swallows spent their winter underwater 412 00:27:52,560 --> 00:27:54,720 became increasingly entrenched. 413 00:27:58,560 --> 00:28:02,840 By the 18th century, the debate about migration versus hibernation 414 00:28:02,840 --> 00:28:08,360 had come to a head and across the continent opinions were divided. 415 00:28:11,240 --> 00:28:15,240 But new evidence was about to come from an unusual source. 416 00:28:16,520 --> 00:28:20,880 Edward Jenner was an English country doctor who also had a deep 417 00:28:20,880 --> 00:28:23,440 interest in natural history. 418 00:28:23,440 --> 00:28:27,040 He noted that although swallows often splash in water 419 00:28:27,040 --> 00:28:31,280 as they skim across it, they never immerse themselves. 420 00:28:31,280 --> 00:28:34,600 Were they to do so, he suggested, their wings would become 421 00:28:34,600 --> 00:28:37,400 so wet that they would be unable to fly. 422 00:28:38,520 --> 00:28:41,800 To test his idea, Jenner reportedly held a swift 423 00:28:41,800 --> 00:28:44,040 underwater for two minutes. 424 00:28:44,040 --> 00:28:46,040 Not surprisingly, it died. 425 00:28:48,000 --> 00:28:51,560 Jenner went on to devise another experiment to 426 00:28:51,560 --> 00:28:53,360 discover where the birds go. 427 00:28:53,360 --> 00:28:57,000 He took 12 swifts from their nests and marked them 428 00:28:57,000 --> 00:28:59,120 by taking off two of their claws. 429 00:28:59,120 --> 00:29:02,200 The following year, some of the birds he'd marked were caught 430 00:29:02,200 --> 00:29:04,800 again in exactly the same spot. 431 00:29:04,800 --> 00:29:08,240 Although Jenner could not discover where his swifts had been 432 00:29:08,240 --> 00:29:11,800 over the winter, he was the first to show that they returned to use 433 00:29:11,800 --> 00:29:15,040 the same breeding sites in the following years. 434 00:29:15,040 --> 00:29:18,520 And we now know that this is true for swallows as well. 435 00:29:20,000 --> 00:29:24,280 About the same time, across the Channel, a German bird enthusiast 436 00:29:24,280 --> 00:29:26,280 had come up with a similar idea. 437 00:29:28,360 --> 00:29:32,360 Johann Frisch caught several birds near his house and attached 438 00:29:32,360 --> 00:29:36,400 to their legs woollen threads like this which he'd dipped 439 00:29:36,400 --> 00:29:38,120 in red watercolour. 440 00:29:38,120 --> 00:29:40,880 He predicted that if swallows really did spend 441 00:29:40,880 --> 00:29:45,640 the winter at the bottom of lakes, the red colour would be washed off. 442 00:29:45,640 --> 00:29:48,880 The following spring, Frisch's swallows returned 443 00:29:48,880 --> 00:29:51,080 and the threads where unchanged. 444 00:29:51,080 --> 00:29:55,560 It was a very simple but very effective experiment. 445 00:29:55,560 --> 00:29:59,520 Evidence against the hibernation theory continued to mount 446 00:29:59,520 --> 00:30:04,200 and eventually a new technique put the final nail in its coffin... 447 00:30:04,200 --> 00:30:06,360 systematic bird ringing. 448 00:30:09,320 --> 00:30:13,800 This bird has just been fitted with its own individual marker. 449 00:30:13,800 --> 00:30:18,800 A small metal ring on its leg with a unique code of numbers. 450 00:30:18,800 --> 00:30:21,920 It's part of a national scheme that's been running for over 100 451 00:30:21,920 --> 00:30:26,320 years and provides scientists with invaluable data on bird movements. 452 00:30:27,520 --> 00:30:31,800 Early in the 20th century, the study of migration really took off. 453 00:30:31,800 --> 00:30:34,640 Birds were recovered on their breeding and wintering grounds 454 00:30:34,640 --> 00:30:37,840 and often en route, too. 455 00:30:37,840 --> 00:30:41,440 600 years after Frederick von Hohenstaufen had first started 456 00:30:41,440 --> 00:30:45,240 the debate, real evidence was beginning to accumulate. 457 00:30:47,560 --> 00:30:51,360 In the summer of 1911, a metal ring just like this one, 458 00:30:51,360 --> 00:30:55,160 was clipped onto the leg of a young swallow in Staffordshire. 459 00:30:55,160 --> 00:30:59,640 The number on the ring was B830. 460 00:30:59,640 --> 00:31:04,280 18 months later, the same bird was caught by a farmer in South Africa. 461 00:31:04,280 --> 00:31:09,240 Here, at last, was the indisputable proof that swallows migrate 462 00:31:09,240 --> 00:31:11,840 and spend the winter thousands of miles away. 463 00:31:13,960 --> 00:31:16,960 Off you go. There we are. 464 00:31:19,880 --> 00:31:23,280 Today, of course, we know that the swallows' migration is 465 00:31:23,280 --> 00:31:26,880 one of the most impressive in all the animal kingdom. 466 00:31:26,880 --> 00:31:31,080 It takes it across the largest desert in the world, the Sahara, 467 00:31:31,080 --> 00:31:33,560 it's a gruelling and dangerous journey 468 00:31:33,560 --> 00:31:38,400 and many die on the way from exhaustion or starvation. 469 00:31:38,400 --> 00:31:43,760 They travel for nearly four months, covering nearly 10,000km 470 00:31:43,760 --> 00:31:46,200 and eventually reach southern Africa. 471 00:31:52,720 --> 00:31:56,280 And bird ringing also helped to dispel the myth of 472 00:31:56,280 --> 00:31:58,080 the barnacle goose. 473 00:31:58,080 --> 00:32:02,640 In the 1960s, a Norwegian expedition, ringed geese nesting 474 00:32:02,640 --> 00:32:07,680 on the Arctic island of Spitsbergen. That autumn, some of the same 475 00:32:07,680 --> 00:32:11,720 birds were sited on the west coast of Scotland, some 2,000km away. 476 00:32:13,520 --> 00:32:18,120 Frederick von Hohenstaufen had been proved to be absolutely correct. 477 00:32:21,760 --> 00:32:26,000 It took centuries to discover the truth behind the swallows' 478 00:32:26,000 --> 00:32:27,960 seasonal movements. 479 00:32:27,960 --> 00:32:32,720 But in their time, they baffled the minds of many great naturalists and 480 00:32:32,720 --> 00:32:36,920 started one of the longest-running of all scientific debates. 481 00:32:36,920 --> 00:32:41,880 But in the end, the true story proved to be even more extraordinary 482 00:32:41,880 --> 00:32:46,280 than the fantastic myths that where invented to explain it. 483 00:32:48,440 --> 00:32:50,160 Just like the swallow, 484 00:32:50,160 --> 00:32:54,160 the painted lady butterfly seems to appear magically out of nowhere 485 00:32:54,160 --> 00:32:57,800 and that started some extraordinary ideas and controversies. 486 00:32:58,960 --> 00:33:02,200 The painted lady is one of our largest butterflies 487 00:33:02,200 --> 00:33:05,080 and a familiar summer visitor to our gardens. 488 00:33:05,080 --> 00:33:06,360 And yet, its appearance 489 00:33:06,360 --> 00:33:10,000 and disappearance each year, has puzzled us for centuries. 490 00:33:10,000 --> 00:33:13,240 It's only now that we're beginning to understand this extraordinary 491 00:33:13,240 --> 00:33:16,520 life cycle and discover where it vanishes each year. 492 00:33:18,080 --> 00:33:20,720 Early naturalists were confused by the sudden 493 00:33:20,720 --> 00:33:23,720 appearance of painted ladies each spring because they were 494 00:33:23,720 --> 00:33:28,960 unaware of the connection between butterflies and caterpillars. 495 00:33:28,960 --> 00:33:32,520 For a very long time it was widely believed that butterflies 496 00:33:32,520 --> 00:33:37,880 arise from rotting material by what was called spontaneous generation. 497 00:33:40,160 --> 00:33:46,360 In the 1830s, a German scientist named Renous was arrested for heresy 498 00:33:46,360 --> 00:33:50,520 for claiming that he could change caterpillars into butterflies. 499 00:33:50,520 --> 00:33:53,600 Arresting someone for something now known to be common knowledge 500 00:33:53,600 --> 00:33:57,280 may seem rather extreme, but at the time, many still believed that 501 00:33:57,280 --> 00:34:00,720 caterpillars and butterflies were completely different creatures, 502 00:34:00,720 --> 00:34:02,440 created by the hand of God. 503 00:34:04,800 --> 00:34:08,520 Needless to say, people had been well aware of the existence of 504 00:34:08,520 --> 00:34:12,240 both butterflies and caterpillars since the earliest times. 505 00:34:14,240 --> 00:34:17,000 But the thought that any two were related, 506 00:34:17,000 --> 00:34:21,200 let alone the same species, seemed impossible... 507 00:34:21,200 --> 00:34:23,960 and it's easy to see why. 508 00:34:26,760 --> 00:34:30,120 Not only do caterpillars and butterflies look like very 509 00:34:30,120 --> 00:34:33,680 different types of animals, but the colours and patterns 510 00:34:33,680 --> 00:34:38,000 of a caterpillar don't match up with those of its adult form. 511 00:34:38,000 --> 00:34:42,520 The only way to know which lava and which butterfly go together 512 00:34:42,520 --> 00:34:46,280 is to keep caterpillars and watch them turn into butterflies. 513 00:34:46,280 --> 00:34:50,040 But it wasn't until the 17th century that anyone left 514 00:34:50,040 --> 00:34:51,640 a record of doing that. 515 00:34:52,720 --> 00:34:57,400 One of the first was a remarkable woman named Maria Sibylla Merian. 516 00:34:58,520 --> 00:35:01,560 Merian was born in Germany at a time 517 00:35:01,560 --> 00:35:04,240 when women still had little formal education 518 00:35:04,240 --> 00:35:08,560 and no role in the scientific world, but she was an accomplished 519 00:35:08,560 --> 00:35:12,840 artist and painted plants and insects she saw around her. 520 00:35:12,840 --> 00:35:17,000 To do that, she kept caterpillars, fed them on leaves 521 00:35:17,000 --> 00:35:19,440 and watched them turn into butterflies. 522 00:35:21,040 --> 00:35:24,560 Merian produced hundreds of beautiful paintings of butterflies 523 00:35:24,560 --> 00:35:26,560 and their stages of development 524 00:35:26,560 --> 00:35:29,000 along with the plants on which they feed. 525 00:35:29,000 --> 00:35:30,840 Her drawings are so exquisite 526 00:35:30,840 --> 00:35:34,280 and detailed that they still rank among the best in the world. 527 00:35:37,320 --> 00:35:41,280 Among the things she observed with great care, were things like this. 528 00:35:42,640 --> 00:35:48,400 A curious, yet strangely beautiful object, it's a chrysalis, 529 00:35:48,400 --> 00:35:52,280 the intermediate stage between a caterpillar and a butterfly. 530 00:35:55,880 --> 00:35:59,080 She was one of the first to record the remarkable change 531 00:35:59,080 --> 00:36:01,080 that takes place in the chrysalis. 532 00:36:02,920 --> 00:36:06,360 It's one of nature's most extraordinary transformations. 533 00:36:11,000 --> 00:36:15,920 At the age of 52, she sailed from Europe to South America on a 534 00:36:15,920 --> 00:36:20,640 two-year expedition to study insects in the tropical jungles of Surinam. 535 00:36:20,640 --> 00:36:23,200 It was an exceptional journey for any naturalist 536 00:36:23,200 --> 00:36:26,480 at the time and particularly for a woman. 537 00:36:26,480 --> 00:36:29,760 When she returned, she produced this beautiful book. 538 00:36:32,280 --> 00:36:34,000 It turned out to be popular 539 00:36:34,000 --> 00:36:36,200 because it was one of the few to be published 540 00:36:36,200 --> 00:36:40,360 not in the scientific language of Latin but in Dutch. 541 00:36:40,360 --> 00:36:41,520 Because of this, 542 00:36:41,520 --> 00:36:45,280 her work was largely dismissed by scientists of the time 543 00:36:45,280 --> 00:36:48,600 but Merian was one of the first naturalists to correctly 544 00:36:48,600 --> 00:36:52,600 connect the caterpillar with its pupa and the adult form. 545 00:36:54,800 --> 00:36:56,920 Today, Merian's book is widely 546 00:36:56,920 --> 00:37:01,440 recognised as a pioneering work of scientific observation 547 00:37:01,440 --> 00:37:06,040 and it put an end to the idea of spontaneous generation. 548 00:37:08,680 --> 00:37:12,240 Around the same time, further evidence for the connection 549 00:37:12,240 --> 00:37:16,280 between butterflies and caterpillars came from a different source. 550 00:37:18,520 --> 00:37:23,240 In 1669, a Dutch scientist by the name of Jan Swammerdam published 551 00:37:23,240 --> 00:37:27,040 the results of experiments which would finally prove that the 552 00:37:27,040 --> 00:37:30,800 caterpillar and butterfly are one and the same animal. 553 00:37:30,800 --> 00:37:33,960 Swammerdam was a master of the miniature and dissected the 554 00:37:33,960 --> 00:37:36,520 caterpillars and pupae of butterflies and moths 555 00:37:36,520 --> 00:37:40,720 under a microscope. With a steady hand and endless patience, 556 00:37:40,720 --> 00:37:44,160 he carefully cut into the layers of skin with tiny scissors 557 00:37:44,160 --> 00:37:47,320 and what he discovered was truly astonishing. 558 00:37:49,600 --> 00:37:54,520 He found some of the body parts of a butterfly. 559 00:37:54,520 --> 00:37:58,920 The structures were fragile and not complete but Swammerdam had proved 560 00:37:58,920 --> 00:38:03,240 that caterpillar and butterfly are, indeed, one and the same animal. 561 00:38:07,920 --> 00:38:12,080 We now know that without the caterpillar, there can be no butterfly. 562 00:38:12,080 --> 00:38:13,360 Yet, for a very long time, 563 00:38:13,360 --> 00:38:16,320 the painted lady seemed to be an exception. 564 00:38:16,320 --> 00:38:19,920 Every spring, the adult butterflies would appear across Britain 565 00:38:19,920 --> 00:38:22,600 without any sightings of their caterpillars. 566 00:38:23,600 --> 00:38:27,360 While some butterflies hibernate in Britain, there was no sign 567 00:38:27,360 --> 00:38:28,920 of painted ladies doing so. 568 00:38:29,920 --> 00:38:34,720 Some speculated that they flew to warmer climates as birds do. 569 00:38:35,720 --> 00:38:39,040 But how could a tiny insect cross the English Channel? 570 00:38:40,160 --> 00:38:43,840 In the 20th century, swarms of butterflies moving across Europe 571 00:38:43,840 --> 00:38:47,640 finally provided evidence that painted ladies do, indeed, 572 00:38:47,640 --> 00:38:49,400 cross the sea. 573 00:38:49,400 --> 00:38:53,800 And they were found to fly all the way from North Africa to Britain. 574 00:38:55,000 --> 00:38:58,240 But there were almost no records of painted ladies making 575 00:38:58,240 --> 00:39:00,320 the reverse trip south. 576 00:39:00,320 --> 00:39:03,680 So, for years, it was thought that Britain must be 577 00:39:03,680 --> 00:39:06,640 a dead-end for the most northerly stragglers. 578 00:39:08,440 --> 00:39:14,120 And then, in 2009, the public was asked to help solve the mystery. 579 00:39:14,120 --> 00:39:18,480 Among 12,000 sightings there were reports of painted ladies 580 00:39:18,480 --> 00:39:21,000 flying out to sea in the autumn. 581 00:39:22,400 --> 00:39:25,680 And a radar station detected them flying south 582 00:39:25,680 --> 00:39:30,240 at heights of 500 metres, way beyond the sight of human eyes. 583 00:39:32,360 --> 00:39:36,240 We now know that the painted ladies migration is a round-trip 584 00:39:36,240 --> 00:39:42,200 of over 12,000km. But it's not made by any one individual. 585 00:39:42,200 --> 00:39:45,040 Each only flies part of the way, 586 00:39:45,040 --> 00:39:48,440 passing on the migratory baton to the next generation. 587 00:39:48,440 --> 00:39:53,360 It's like a relay race with up to six generations of butterflies involved. 588 00:39:55,640 --> 00:39:58,920 The painted ladies epic journey from one continent to the next 589 00:39:58,920 --> 00:40:01,960 would be a truly astonishing feature in any animal 590 00:40:01,960 --> 00:40:05,680 but for a tiny creature like this, it seems really extraordinary. 591 00:40:05,680 --> 00:40:07,280 How does it battle the wind 592 00:40:07,280 --> 00:40:10,880 and the weather and navigate across vast bodies of water? 593 00:40:10,880 --> 00:40:14,400 And with no single individual ever undertaking the whole migration, 594 00:40:14,400 --> 00:40:16,000 how do they find the way? 595 00:40:18,520 --> 00:40:23,000 It seems that painted ladies are pre-programmed to either fly 596 00:40:23,000 --> 00:40:26,800 north or south and this is determined whilst 597 00:40:26,800 --> 00:40:29,600 they are still caterpillars, possibly by temperature 598 00:40:29,600 --> 00:40:34,240 and day length and also by the plants they feed on but how 599 00:40:34,240 --> 00:40:39,320 does this information get passed on from caterpillar to butterfly? 600 00:40:39,320 --> 00:40:42,200 The answer may be hidden within the chrysalis. 601 00:40:43,400 --> 00:40:49,280 Recently CT scanners have allowed us to look inside a pupa. 602 00:40:49,280 --> 00:40:54,480 They reveal that some organs remain intact during the transformation. 603 00:40:56,320 --> 00:41:00,320 A one-day-old pupa clearly shows the gut and breathing tubes 604 00:41:00,320 --> 00:41:03,560 which only change slightly as the chrysalis develops. 605 00:41:07,680 --> 00:41:12,000 Could it be that the brain or nerves also remain intact 606 00:41:12,000 --> 00:41:14,360 and that memories are passed on? 607 00:41:15,720 --> 00:41:20,600 Recent experiments in the lab appear to support this idea. 608 00:41:20,600 --> 00:41:24,080 Scientists taught caterpillars to avoid specific 609 00:41:24,080 --> 00:41:27,480 smells by linking them with an unpleasant reaction. 610 00:41:28,520 --> 00:41:32,280 Later on, as adults, the same individuals remembered these 611 00:41:32,280 --> 00:41:35,520 smells and chose to keep away from them. 612 00:41:35,520 --> 00:41:38,760 If the experiences of a caterpillar can be carried over 613 00:41:38,760 --> 00:41:43,600 to the adult, then maybe cues for migration can also be passed on. 614 00:41:45,800 --> 00:41:49,440 Although we've unravelled much of the painted lady's life-cycle, 615 00:41:49,440 --> 00:41:54,760 many questions remain. How far does each individual travel? 616 00:41:54,760 --> 00:41:59,040 And do offspring follow similar routes to their ancestors? 617 00:41:59,040 --> 00:42:02,680 One day we may know the answers but, for now, 618 00:42:02,680 --> 00:42:06,480 they remain some of the unsolved mysteries of nature. 619 00:42:09,560 --> 00:42:12,680 The arrival each spring of our painted lady butterflies 620 00:42:12,680 --> 00:42:15,800 and our swallows never ceases to delight us 621 00:42:15,800 --> 00:42:18,800 but now we also understand the extraordinary journeys 622 00:42:18,800 --> 00:42:22,640 they undertake when they disappear again at the end of summer. 55727

Can't find what you're looking for?
Get subtitles in any language from opensubtitles.com, and translate them here.