1 00:00:41,200 --> 00:00:45,273 Childhood - from newborn baby to infant. 2 00:00:46,520 --> 00:00:50,115 From toddler to the first day at school. 3 00:00:50,840 --> 00:00:56,278 To crawl, to walk, to talk, to become an individual, 4 00:00:56,400 --> 00:00:59,392 it is four years of miraculous achievement. 5 00:00:59,520 --> 00:01:05,152 Never again will the human body change so fast or learn so much. 6 00:01:05,280 --> 00:01:09,068 This is the story of that remarkable time. 7 00:01:24,680 --> 00:01:28,798 It all begins with the most treacherous journey of our lives, 8 00:01:28,920 --> 00:01:32,230 from our mother's womb to the outside world. 9 00:01:32,360 --> 00:01:38,196 As recently as Victorian times, one in 20 babies died during birth. 10 00:01:38,320 --> 00:01:41,517 Death affected everybody, including royalty. 11 00:01:41,640 --> 00:01:46,953 Here in Windsor Castle is a memorial to Princess Charlotte and her son. 12 00:01:47,080 --> 00:01:51,995 Just one year after her marriage in 1816, she was expecting a baby. 13 00:01:54,400 --> 00:01:57,312 Tragically, the birth was a disaster. 14 00:01:57,440 --> 00:02:00,591 The baby boy became stuck inside his mother. 15 00:02:00,720 --> 00:02:05,157 After two days and two nights of labour, the unborn prince was dead, 16 00:02:05,280 --> 00:02:07,840 and a few hours later, Charlotte died as well. 17 00:02:08,680 --> 00:02:14,755 Their deaths meant the crown eventually passed to Queen Victoria, and the rest is history. 18 00:02:16,720 --> 00:02:21,032 With modern medicine, Princess Charlotte almost certainly would have survived, 19 00:02:21,160 --> 00:02:23,720 and her little boy would have become king. 20 00:02:23,840 --> 00:02:26,832 Today in Britain, very few babies will die. 21 00:02:26,960 --> 00:02:33,035 But that journey, just ten centimetres in length, remains as fraught with danger as ever. 22 00:02:33,240 --> 00:02:35,879 (HEART BEATING) 23 00:02:40,760 --> 00:02:42,591 (W0MAN) Go on, Jane. 24 00:02:42,720 --> 00:02:47,510 For nine months, the baby's been fully equipped for life in the warm liquid world of the womb, 25 00:02:47,640 --> 00:02:50,632 relying on its mother for food and oxygen. 26 00:02:52,120 --> 00:02:54,793 It's in for a rude shock. 27 00:02:57,440 --> 00:03:02,150 As the baby is squeezed down the birth canal, dramatic changes have to happen. 28 00:03:02,280 --> 00:03:06,432 The key to success is the trauma of the birth itself. 29 00:03:06,560 --> 00:03:10,155 It's so severe, the baby has adrenalin levels 30 00:03:10,280 --> 00:03:13,431 even higher than that of a person suffering a heart attack. 31 00:03:13,560 --> 00:03:17,872 This rush of adrenalin will kick-start the baby's breathing. 32 00:03:20,200 --> 00:03:23,351 (W0MAN) Well done, that's brilliant. Here he comes. 33 00:03:23,480 --> 00:03:29,635 Yet even now during birth, the baby's windpipe and lungs are still full of liquid from the womb. 34 00:03:29,760 --> 00:03:32,194 If they aren't quickly emptied, it will drown. 35 00:03:32,320 --> 00:03:37,075 The fluid drains away as it's absorbed into the lung walls. 36 00:03:43,400 --> 00:03:44,958 Air rushes in. 37 00:03:45,920 --> 00:03:49,879 Life-giving oxygen can enter the blood vessels of the lungs. 38 00:03:50,000 --> 00:03:54,596 The first breath triggers further upheavals inside the tiny body. 39 00:03:57,080 --> 00:04:01,198 (W0MAN) That's it, Jane. Well done, sweetheart. Well done. 40 00:04:01,320 --> 00:04:07,793 (MAN) Excellent! Well done! (W0MAN) Well done. 41 00:04:07,920 --> 00:04:10,832 Remarkably, even at this late stage, 42 00:04:10,960 --> 00:04:15,670 the heart of the baby is not yet ready for life outside the womb. 43 00:04:19,040 --> 00:04:22,919 In one of the interior walls of the heart there is a hole. 44 00:04:23,040 --> 00:04:27,158 This opening was vital when the baby had to pump blood to the placenta. 45 00:04:27,280 --> 00:04:29,191 Now it's a liability. 46 00:04:31,120 --> 00:04:33,315 Blood flowing through a newly-opened vessel 47 00:04:33,440 --> 00:04:37,797 will slam shut a flap of tissue to seal the vulnerable hole. 48 00:04:43,080 --> 00:04:48,154 It forms a solid wall, and the four chambers of the heart are finally complete. 49 00:04:48,280 --> 00:04:53,035 In an adult, such major changes would require open-heart surgery, 50 00:04:53,160 --> 00:04:58,439 but here they are happening instantaneously and unseen inside the baby. 51 00:04:58,560 --> 00:05:01,518 This is the miracle of birth. 52 00:05:01,640 --> 00:05:04,996 (W0MAN) Now we'll cut his cord. Can Richard cut the cord? 53 00:05:05,120 --> 00:05:07,793 It's a boy - Bob. 54 00:05:07,920 --> 00:05:12,675 The umbilical cord, the last link to his mother, is cut. 55 00:05:13,520 --> 00:05:15,954 Bob's first challenge is to keep warm. 56 00:05:16,080 --> 00:05:20,596 A heat-sensitive camera reveals the coldest parts as blue. 57 00:05:20,720 --> 00:05:23,109 Bob's toes and nose suffer most. 58 00:05:24,080 --> 00:05:28,232 The delivery room is 15 degrees colder than his mother's womb. 59 00:05:28,360 --> 00:05:31,796 (W0MAN) He looks fine. Yes! 60 00:05:31,920 --> 00:05:36,948 A special type of fat is concentrated on his back and around his chest. 61 00:05:37,080 --> 00:05:41,596 This baby fat can be broken down to release emergency heat. 62 00:05:41,720 --> 00:05:47,909 But for the first six months of life, Bob's ability to control his temperature is very limited. 63 00:05:48,040 --> 00:05:52,397 For the moment, he relies on blankets and cuddles. 64 00:05:52,520 --> 00:05:54,112 (MAN) He's shivering a bit. 65 00:05:54,240 --> 00:06:00,509 (W0MAN) You see his little lips going. (M0THER) He's cold. A little bit cold. 66 00:06:01,240 --> 00:06:05,631 He looks...dark hair, yeah. 67 00:06:06,640 --> 00:06:09,712 (W0MAN) Those little marks will be gone by tomorrow. 68 00:06:09,840 --> 00:06:14,152 (MAN) It'll take no time at all. (W0MAN) It was all a bit of a push. 69 00:06:14,280 --> 00:06:19,877 Bob's tight squeeze through the birth canal has left his head an odd, pointed shape. 70 00:06:20,000 --> 00:06:24,630 His skull is so pliable because the 22 different bones that make it up 71 00:06:24,760 --> 00:06:29,709 haven't yet fused together, leaving holes between the bone plates. 72 00:06:33,040 --> 00:06:38,797 Bob would never have made it out of the womb if his skull hadn't evolved to be this way. 73 00:06:44,840 --> 00:06:50,949 From now on Bob will live under the watchful eye of his proud parents, Jane and Richard Jeffers. 74 00:06:51,080 --> 00:06:54,197 His hazardous journey into the world is over. 75 00:06:54,320 --> 00:06:58,359 - Thanks, Richard. That's brilliant. - There we are. Just pop him down here. 76 00:07:06,800 --> 00:07:10,270 (JANE) It's just amazing to see that he's perfectly formed 77 00:07:10,400 --> 00:07:14,313 in absolutely every way, his arms, his legs. 78 00:07:14,440 --> 00:07:17,238 He's got quite a tidy little nose. 79 00:07:17,360 --> 00:07:20,591 He's got a nice mouth. He's got quite a wide mouth. 80 00:07:20,720 --> 00:07:24,679 Everything is just perfect. It's just a miracle. 81 00:07:24,800 --> 00:07:28,839 You don't see that they're wrinkled up and all those other things. 82 00:07:28,960 --> 00:07:33,397 His face looks really quite well established 83 00:07:33,520 --> 00:07:36,318 for a small baby. He's got a lot of character. 84 00:07:36,440 --> 00:07:40,911 In a strange sort of way, he looks like a little old man. 85 00:07:42,160 --> 00:07:46,631 Although Bob is helpless, he has a fantastic survival strategy. 86 00:07:46,760 --> 00:07:50,070 Parents find their new baby irresistible. 87 00:07:50,200 --> 00:07:55,672 (JANE) Oh, Bob. Is that nappy bothering you? 88 00:07:55,800 --> 00:07:59,190 They do control you to a point. Their demands are paramount. 89 00:07:59,320 --> 00:08:03,108 If they cry and want feeding, you've got to do that. 90 00:08:03,240 --> 00:08:08,758 If they need changing... You can't ignore their needs, because they're dependant on you. 91 00:08:08,880 --> 00:08:13,795 This is the best bit, isn't it? A bit of fresh air to that bottom. 92 00:08:16,240 --> 00:08:20,074 It's almost as if Bob has put his parents under a spell. 93 00:08:20,960 --> 00:08:25,158 # You're just too good to be true 94 00:08:25,280 --> 00:08:28,397 # Can't take my eyes off of you 95 00:08:28,520 --> 00:08:32,433 # You'll be like heaven to touch 96 00:08:32,560 --> 00:08:36,519 # And I want to hold you so much 97 00:08:36,640 --> 00:08:38,710 # At long last love has arrived... # 98 00:08:38,840 --> 00:08:43,550 (RICHARD) Bob's...first...picture. 99 00:08:43,680 --> 00:08:46,911 # You're just too good to be true 100 00:08:47,040 --> 00:08:51,636 # Can't take my eyes off of you # 101 00:09:00,000 --> 00:09:04,357 0ver a period of six months, we followed Bob's rapid development. 102 00:09:06,720 --> 00:09:10,349 Just a few weeks after birth he was a bundle of reflexes, 103 00:09:10,480 --> 00:09:15,395 a handy set of automatic responses that help him survive. 104 00:09:15,520 --> 00:09:17,511 Can he hear you? 105 00:09:17,640 --> 00:09:22,031 Yes, he's startled by loud noises, and he can definitely hear me. 106 00:09:22,160 --> 00:09:26,312 A young baby will try to grip with his hands anything he touches. 107 00:09:26,440 --> 00:09:29,477 Young apes grasp on to their mother's fur. 108 00:09:29,600 --> 00:09:34,833 But even in hairless humans this grasping reflex can be useful for holding on. 109 00:09:37,040 --> 00:09:40,112 I'm just going to check his reflexes. 110 00:09:40,240 --> 00:09:44,199 A reflex is activated by any touch to the palm. 111 00:09:44,320 --> 00:09:47,551 Here, the baby's hand has grasped a finger. 112 00:09:47,680 --> 00:09:52,435 Inside the hand, you can see the muscles that even just after birth 113 00:09:52,560 --> 00:09:55,279 can support the weight of the baby. 114 00:09:55,400 --> 00:09:59,632 Ironically, the hardest thing for babies to learn is to let go. 115 00:09:59,760 --> 00:10:02,194 Their fingers have to be prised open. 116 00:10:03,600 --> 00:10:06,239 And Bob's toes will try to grip as well, 117 00:10:06,360 --> 00:10:10,956 a throwback to our ape-like ancestors who held on to things with their feet. 118 00:10:11,080 --> 00:10:13,992 These reflexes are completely involuntary. 119 00:10:14,120 --> 00:10:19,797 They require no more conscious control than the contraction of the eye's pupil to light. 120 00:10:24,920 --> 00:10:28,469 Are you ready? Ready for your milk? 121 00:10:28,600 --> 00:10:31,353 Another reflex helps Bob find food. 122 00:10:31,480 --> 00:10:34,552 Although he doesn't know where food comes from, 123 00:10:34,680 --> 00:10:39,196 whenever something brushes his cheek he automatically turns his head from side to side 124 00:10:39,320 --> 00:10:44,758 and parts his lips. This is the rooting reflex. 125 00:10:44,880 --> 00:10:47,678 He just finds it himself. 126 00:10:47,800 --> 00:10:52,828 He'll find it. You just need to put his head somewhere remotely near, 127 00:10:52,960 --> 00:10:55,520 and he's there. 128 00:10:59,240 --> 00:11:02,994 And that's not all. The milk that's produced in the mother's breast 129 00:11:03,120 --> 00:11:06,635 can be activated merely by the sound of the baby crying. 130 00:11:08,680 --> 00:11:10,238 That's a lovely boy. 131 00:11:10,360 --> 00:11:14,956 Bob not only manipulates his mother's behaviour but also her body. 132 00:11:15,080 --> 00:11:18,072 What a face. Got a full tummy there. 133 00:11:25,320 --> 00:11:29,950 Newborn babies have another reflex which is much more mysterious. 134 00:11:30,080 --> 00:11:35,837 In fact, it's an ability so odd that until recently we didn't even realise it existed. 135 00:11:35,960 --> 00:11:40,397 Actually, it's a reflex we all had in the first six months of life. 136 00:11:40,520 --> 00:11:42,636 Watch this. 137 00:11:52,480 --> 00:11:57,679 It's called the diving reflex, because it stops the baby from breathing under water. 138 00:12:02,280 --> 00:12:03,759 Wow. 139 00:12:06,160 --> 00:12:08,196 She's more comfortable than I am, I think. 140 00:12:10,720 --> 00:12:12,756 The mouth can be wide open, 141 00:12:12,880 --> 00:12:16,156 but inside the baby the top of her lungs is sealed off, 142 00:12:16,280 --> 00:12:21,035 and any water is diverted down the oesophagus into the stomach. 143 00:12:24,760 --> 00:12:27,752 Perhaps more amazing are the baby's movements. 144 00:12:27,880 --> 00:12:31,873 Not only do the arms and legs move in a coordinated stroke, 145 00:12:32,000 --> 00:12:37,552 but the torso flexes enough to propel him through the water for over a metre. 146 00:12:38,480 --> 00:12:40,948 However, after a few seconds 147 00:12:41,080 --> 00:12:46,108 they all need adult help to regain the surface and the vital next breath. 148 00:12:46,240 --> 00:12:48,959 Hey, up you go. 149 00:12:52,560 --> 00:12:56,394 Some people believe these abilities come from a long-lost ancestor 150 00:12:56,520 --> 00:12:59,592 who spent most of its time in the sea. 151 00:12:59,720 --> 00:13:04,714 0thers think it is a hangover from our life in the liquid-filled womb. 152 00:13:05,800 --> 00:13:10,794 The truth is we don't even understand the origins of this remarkable ability. 153 00:13:10,920 --> 00:13:14,913 For the moment at least, it remains a delightful mystery. 154 00:13:21,240 --> 00:13:23,196 As the baby's mind matures, 155 00:13:23,320 --> 00:13:28,110 these involuntary reflexes are suppressed by conscious thoughts and movements. 156 00:13:28,240 --> 00:13:32,119 This has already happened with Max, Bob's three-year-old brother. 157 00:13:32,240 --> 00:13:37,360 The reflexes are no longer needed, so they eventually disappear. 158 00:13:39,480 --> 00:13:41,516 In the buzzing, booming world, 159 00:13:41,640 --> 00:13:45,758 both reflexes and conscious thoughts depend on the senses. 160 00:13:45,880 --> 00:13:50,431 But at first Bob can see little. Contrast is poor. 161 00:13:50,560 --> 00:13:53,597 Anything beyond half a metre is out of focus and blurred, 162 00:13:53,720 --> 00:13:56,393 and he may even see double. 163 00:13:56,520 --> 00:14:02,117 0ne of the reasons Bob is so bad at focusing is hidden inside the eyes. 164 00:14:02,240 --> 00:14:06,028 A very young baby does not have proper control of the muscles 165 00:14:06,160 --> 00:14:08,469 that change the shape of the lens. 166 00:14:08,600 --> 00:14:14,118 The lens, here coloured white, is fixed at one set shape. 167 00:14:14,240 --> 00:14:18,756 To focus on objects far away, the tiny muscles around the lens 168 00:14:18,880 --> 00:14:21,997 need to stretch it into a thinner shape. 169 00:14:22,120 --> 00:14:25,430 It'll be a while before Bob learns to do this. 170 00:14:26,320 --> 00:14:29,835 Are you gonna try? Yes! Clever boy! 171 00:14:29,960 --> 00:14:33,748 By two months, his vision will have improved. 172 00:14:33,880 --> 00:14:36,553 He seems to like looking at faces best, 173 00:14:36,680 --> 00:14:40,309 and it's at this time he will first smile, 174 00:14:40,440 --> 00:14:43,432 a magic moment for any parent. 175 00:14:46,960 --> 00:14:49,520 He still was only about three weeks. 176 00:14:51,840 --> 00:14:55,276 Then I realised that he was actually smiling back at me. 177 00:14:59,680 --> 00:15:04,117 Smiling and recognising a smile are crucial milestones. 178 00:15:04,240 --> 00:15:06,435 So a team in London are finding out 179 00:15:06,560 --> 00:15:11,111 what's going on inside the head of this baby girl to see how she does it. 180 00:15:11,240 --> 00:15:14,516 You're a very good baby. Very smiley. 181 00:15:15,520 --> 00:15:20,514 They measure the electrical activity in the brain when she looks at different faces. 182 00:15:21,480 --> 00:15:23,755 A scowling face. 183 00:15:23,880 --> 00:15:26,030 A smiling face. 184 00:15:27,320 --> 00:15:29,550 And an upside-down face. 185 00:15:33,080 --> 00:15:39,838 The patterns of brain waves prove that the baby first sees it as a face, right way up or not. 186 00:15:39,960 --> 00:15:42,315 And then, a fraction of a second later, 187 00:15:42,440 --> 00:15:45,159 she checks out what emotion is showing. 188 00:15:45,280 --> 00:15:50,593 And these two tasks actually happen in different parts of the brain. 189 00:15:51,680 --> 00:15:57,437 You might assume a baby's brain is just the same as an adult's, only smaller. 190 00:15:57,560 --> 00:16:01,951 But it's not. A baby's brain is nowhere near finished. 191 00:16:02,080 --> 00:16:07,393 New connections between the hundred billion brain cells are being made all the time. 192 00:16:07,520 --> 00:16:10,637 Throughout babyhood, the brain is sculpted. 193 00:16:10,760 --> 00:16:17,393 So our experiences in our first few years will determine the brain we have as adults. 194 00:16:19,480 --> 00:16:22,790 This developing brain is so demanding 195 00:16:22,920 --> 00:16:27,710 that over half of all the food Bob eats goes to driving it. 196 00:16:27,840 --> 00:16:31,799 To supply this much energy, it is essential that he moves on from milk. 197 00:16:32,680 --> 00:16:38,437 To deal with solid food, things are stirring underneath his gums. 198 00:16:38,560 --> 00:16:42,235 His first teeth will grow up from tiny tooth buds 199 00:16:42,360 --> 00:16:47,275 that have been hidden in his jaw since long before he was born. 200 00:16:47,480 --> 00:16:52,349 But they won't start to burst through his gums until he's around six months old. 201 00:16:52,480 --> 00:16:58,191 For the first time, over 40 days, this dramatic event has been filmed. 202 00:17:11,640 --> 00:17:14,916 No wonder babies cry when their teeth come through. 203 00:17:24,200 --> 00:17:28,910 At birth, Bob was a tiny bundle of reflexes and flailing limbs. 204 00:17:29,040 --> 00:17:33,477 0ver the following six months, he has grown quicker than he ever will again. 205 00:17:33,600 --> 00:17:36,797 He has more than doubled in size. 206 00:17:39,320 --> 00:17:41,629 But he hasn't just been putting on weight. 207 00:17:41,760 --> 00:17:44,911 What is less obvious is that his mind has matured. 208 00:17:46,240 --> 00:17:52,554 For the first time, he can control his hands and reach out to grab objects. 209 00:17:52,680 --> 00:17:58,835 He is turning his desires into actions, a sign of his burgeoning personality. 210 00:17:59,880 --> 00:18:04,829 A baby at this age is soon ready for the next key advance: mobility. 211 00:18:13,640 --> 00:18:16,837 0ne stage ahead of Bob is Zak Troullous. 212 00:18:16,960 --> 00:18:20,270 Zak is already seven months old and lives in London. 213 00:18:20,400 --> 00:18:25,679 0ver the next few months, he'll take his first steps and speak his first words. 214 00:18:25,800 --> 00:18:29,031 But for now that's all in the future. 215 00:18:32,440 --> 00:18:36,558 He seems to be developing very normally. 216 00:18:36,680 --> 00:18:39,035 And that's great. 217 00:18:39,160 --> 00:18:42,311 Has he tried to pull himself to stand or anything like that? 218 00:18:42,440 --> 00:18:45,955 When he's sitting down, he goes forward or falls on his face. 219 00:18:46,080 --> 00:18:48,833 So he's a bit scared. 220 00:18:48,960 --> 00:18:51,952 Right, it's a good time now while he's sitting 221 00:18:52,080 --> 00:18:56,278 to think about making sure that the environment is safe for him. 222 00:18:56,400 --> 00:19:01,793 Because everything tends to go straight from hand to mouth. 223 00:19:01,920 --> 00:19:04,798 He's trying to chew his shoe. 224 00:19:04,920 --> 00:19:09,277 Zak's mouth is the most sensitive part of his body. 225 00:19:09,400 --> 00:19:12,472 The tongue is teaming with nerve endings. 226 00:19:12,600 --> 00:19:17,355 That's why babies are so keen to use their mouths to explore the world. 227 00:19:24,480 --> 00:19:27,631 But Zak's scope for exploration is limited. 228 00:19:27,760 --> 00:19:33,073 He still relies on his parents to get around. Things will have to change. 229 00:19:40,720 --> 00:19:44,110 We normally associate crawling with reptiles. 230 00:19:44,240 --> 00:19:47,550 Think of the sprawling waddle of a lizard. 231 00:19:47,680 --> 00:19:51,389 But it's actually a powerful way of getting around. 232 00:19:54,800 --> 00:20:00,511 All movement of the human body is surprisingly complicated and difficult to analyse. 233 00:20:00,640 --> 00:20:04,713 But in order to understand motion, analysis is what you need. 234 00:20:04,840 --> 00:20:08,310 That's what these little markers are all about. 235 00:20:08,440 --> 00:20:14,549 They can be tracked on a computer to reveal the underlying motion of my skeleton. 236 00:20:14,680 --> 00:20:20,994 It's the only way you can follow something even as seemingly simple as the movement of a limb. 237 00:20:21,120 --> 00:20:24,999 Dozens of joints and bones moving in harmony. 238 00:20:26,640 --> 00:20:29,916 Even a clapping stick man is characteristically human. 239 00:20:38,080 --> 00:20:41,516 This baby is doing the diagonal crawl, 240 00:20:41,640 --> 00:20:47,909 moving opposite limbs together, right arm, left leg, then left arm, right leg. 241 00:20:48,040 --> 00:20:53,751 The arms absorb the shock of impact, while the power is provided by the legs. 242 00:21:08,640 --> 00:21:13,589 The top speed of a crawling baby is about two kilometres an hour, 243 00:21:13,720 --> 00:21:17,679 and the average baby crawls perhaps 200 metres a day. 244 00:21:17,800 --> 00:21:23,432 If you look carefully, motion capture can identify seven different types of crawling. 245 00:21:25,080 --> 00:21:29,710 The elephant crawl is where just one limb is moved at a time. 246 00:21:29,840 --> 00:21:32,718 But the diagonal crawl is the most popular. 247 00:21:32,840 --> 00:21:36,515 It's extremely efficient, combining stability with speed. 248 00:21:36,640 --> 00:21:40,918 This crawl takes a while to perfect, as Zak is finding out. 249 00:21:41,120 --> 00:21:45,352 (W0MAN) He's crawling slowly. (MAN) But he's still got that wobble. 250 00:21:45,480 --> 00:21:50,474 - As each day goes by, he gets better. - Bad coordination. Once he gets that... 251 00:21:50,600 --> 00:21:53,910 (W0MAN) He needs a bit more confidence. 252 00:21:54,040 --> 00:21:57,828 Before I put him down, I gather a few toys, 253 00:21:57,960 --> 00:22:02,431 and I go into the kitchen for a few minutes. I know he won't move. 254 00:22:02,560 --> 00:22:05,916 But now, because he's crawling, he's going to the stairs. 255 00:22:06,040 --> 00:22:10,352 You've got to keep an eye on him every second of the day. 256 00:22:10,480 --> 00:22:14,632 Until he started crawling, Zak had no fear of heights. 257 00:22:14,760 --> 00:22:16,910 Now he is increasingly wary. 258 00:22:21,440 --> 00:22:23,396 We're gonna put your weights on. 259 00:22:23,520 --> 00:22:28,469 At a university in America, Karen Adolph experiments with crawling babies 260 00:22:28,600 --> 00:22:31,672 to discover how they deal with treacherous slopes. 261 00:22:31,800 --> 00:22:36,828 As a further challenge, the babies are weighed down with two kilograms of lead. 262 00:22:36,960 --> 00:22:39,599 They then meet the apparatus. 263 00:22:41,200 --> 00:22:44,272 Mother tempts her daughter from the other end of the ramp. 264 00:22:44,400 --> 00:22:46,277 Come on, Natalie! 265 00:22:46,400 --> 00:22:50,951 0nce she's scoped her target, the baby visually assesses the slope. 266 00:22:51,080 --> 00:22:55,153 She confirms the severity of it with careful touches of her hands. 267 00:22:55,280 --> 00:23:00,752 Karen has discovered that they can gauge the angle of a safe slope to within just two degrees, 268 00:23:00,960 --> 00:23:04,509 a tiny fraction of the slope overall. 269 00:23:07,880 --> 00:23:11,998 If they decide it's a bit too steep, they'll adjust their crawl, 270 00:23:12,120 --> 00:23:14,588 maybe even coming down backwards. 271 00:23:17,240 --> 00:23:22,872 Crawling is not just about how to crawl, but what's sensible to crawl down. 272 00:23:23,000 --> 00:23:28,199 If it's way too steep, the baby will wisely avoid the drop altogether. 273 00:23:30,920 --> 00:23:35,232 However, the real revolution in getting around is still to come. 274 00:23:36,600 --> 00:23:40,559 Zak, are you gonna walk over to Daddy? Are you gonna make it? 275 00:23:40,680 --> 00:23:42,955 Zak is 11 months old. 276 00:23:43,080 --> 00:23:48,791 He's about to express what human beings have felt throughout 3,500,000 years of evolution: 277 00:23:48,920 --> 00:23:54,358 an overwhelming desire to rise up on two feet and free the hands. 278 00:23:54,480 --> 00:23:56,198 Can you walk to Daddy? 279 00:23:56,320 --> 00:24:00,757 Zak already has the strength to stand up with a bit of support. 280 00:24:00,880 --> 00:24:04,236 But his ability to walk comes not just from his legs, 281 00:24:04,360 --> 00:24:07,636 but also from deep inside his ear of all places. 282 00:24:10,280 --> 00:24:14,432 At the end of the ear canal are the bones we use for hearing. 283 00:24:14,560 --> 00:24:17,552 Behind these is the balance organ. 284 00:24:17,680 --> 00:24:24,358 The balance organ is a miracle of engineering, made up of three circular tubes full of liquid. 285 00:24:25,600 --> 00:24:29,832 Anchored to the inside walls of these tubes are tiny hairs. 286 00:24:29,960 --> 00:24:36,229 As Zak moves, the hairs also move, telling him the position of his head. 287 00:24:37,080 --> 00:24:40,197 The three tubes each have their own orientation, 288 00:24:40,320 --> 00:24:43,676 which detect the three basic types of movement in space: 289 00:24:43,800 --> 00:24:46,189 roll, 290 00:24:46,320 --> 00:24:48,880 pitch 291 00:24:49,000 --> 00:24:51,275 and yaw. 292 00:24:51,400 --> 00:24:56,349 This device will allow him to take his first independent steps. 293 00:24:58,280 --> 00:25:00,794 (MUSIC: ''WALK LIKE A MAN'') 294 00:25:11,160 --> 00:25:14,948 # Walk, walk, walk, walk 295 00:25:18,880 --> 00:25:23,556 # Walk like a man...# 296 00:25:27,720 --> 00:25:32,919 When he realises he's let go of something and he's standing on his own two feet, 297 00:25:33,040 --> 00:25:36,476 he realises what he's doing. He gets scared. 298 00:25:36,600 --> 00:25:39,512 He loses his balance completely. 299 00:25:39,640 --> 00:25:43,428 But he tries. He's a hard trier, keeps going for it. 300 00:25:53,200 --> 00:25:56,351 It's been a long 12 months for Zak. 301 00:25:58,480 --> 00:26:03,918 Learning to crawl and then get up on two feet have been key achievements. 302 00:26:04,040 --> 00:26:07,510 Zak can now walk tall on his own. 303 00:26:15,640 --> 00:26:19,553 # Happy birthday to you 304 00:26:19,680 --> 00:26:23,992 # Happy birthday to you... # 305 00:26:25,280 --> 00:26:28,590 Zak is a new-experience junkie. 306 00:26:28,720 --> 00:26:30,915 As eating is food for physical growth, 307 00:26:31,040 --> 00:26:35,192 so experience is food for brain development. 308 00:27:11,760 --> 00:27:14,115 (MAN) Oh, where's it gone? 309 00:27:14,240 --> 00:27:15,798 It's gone! 310 00:27:15,920 --> 00:27:20,072 Zak may be walking, but he faces another barrier to further progress. 311 00:27:24,880 --> 00:27:30,716 Imagine what it's like for an infant to understand so very little of what's going on around it... 312 00:27:32,720 --> 00:27:35,871 ..to feel lost and excluded from the social world. 313 00:27:40,520 --> 00:27:45,196 The closest we get to it is a holiday abroad. 314 00:27:46,400 --> 00:27:50,279 - These are too old. I want something new. - (IN ARABIC) 315 00:27:59,080 --> 00:28:03,995 Trouble is you can only get so far with mime and pointing. 316 00:28:04,120 --> 00:28:09,114 Can you take me to the pyramids, where the kings are buried? 317 00:28:28,880 --> 00:28:35,149 As a child, one thing you lack is an accurate way of explaining your desires, exactly what you feel, 318 00:28:35,280 --> 00:28:40,718 what you really want, or any way, really, of telling your parents what to get for you. 319 00:28:40,840 --> 00:28:43,912 What you need, of course, are words. 320 00:28:47,920 --> 00:28:50,878 Every human culture has depended on them, 321 00:28:51,000 --> 00:28:54,470 be they spoken or written, like these hieroglyphics. 322 00:28:57,640 --> 00:29:02,998 Words and language are the most important thing a child will ever learn. 323 00:29:04,440 --> 00:29:09,150 Not just words to describe things you can point at, like sand or rock, 324 00:29:09,280 --> 00:29:11,475 but words to describe abstract things: 325 00:29:11,600 --> 00:29:15,957 your past, your future, your fears, your hopes; 326 00:29:16,080 --> 00:29:19,550 words to describe discoveries and ideas, 327 00:29:19,680 --> 00:29:22,877 to communicate them to other people 328 00:29:23,000 --> 00:29:28,154 down the generations, ever expanding the wealth of human knowledge and experience. 329 00:29:44,640 --> 00:29:48,758 The whole world we have built is built upon language, 330 00:29:48,880 --> 00:29:52,350 and yet it all begins so simply. 331 00:29:52,480 --> 00:29:53,754 Mama. 332 00:29:55,520 --> 00:29:58,193 It seems a miracle, but 15-month-old Zak 333 00:29:58,320 --> 00:30:01,835 can begin to master the complex power of language, 334 00:30:01,960 --> 00:30:07,239 an infinitely flexible symbolic system, and yet still needs nappies. 335 00:30:07,360 --> 00:30:11,114 Bravo! (IN GREEK) 336 00:30:11,240 --> 00:30:16,951 Even more impressively, Zak is learning English and his parents' other language, Greek. 337 00:30:17,080 --> 00:30:19,036 When babies first learn to speak, 338 00:30:19,160 --> 00:30:24,473 they use a completely different part of the brain from adults trying to learn a foreign language. 339 00:30:24,600 --> 00:30:27,956 That's why it's so natural for babies and such an effort for adults. 340 00:30:28,080 --> 00:30:31,390 (IN GREEK) 341 00:30:31,520 --> 00:30:35,308 But it's not just Zak's brain that gives him his power. 342 00:30:37,320 --> 00:30:40,949 A newborn baby has a vocal tract just like any other animal. 343 00:30:41,080 --> 00:30:43,878 The larynx, a pipe at the top of the lungs, 344 00:30:44,000 --> 00:30:46,958 is positioned high up, right at the back of the throat. 345 00:30:47,080 --> 00:30:51,392 It sticks up like a snorkel above the flow of milk to the stomach. 346 00:30:51,520 --> 00:30:57,834 This ingenious arrangement allows the baby to breathe and suckle at the same time. 347 00:30:57,960 --> 00:31:04,115 But with the larynx so high it can't perform its major function in life - speech. 348 00:31:04,240 --> 00:31:10,839 By the time Zak is a year old, the larynx needs to have dropped a whole three centimetres lower. 349 00:31:16,240 --> 00:31:17,832 Where's Mummy? 350 00:31:17,960 --> 00:31:22,875 The lowered larynx now lives up to its other name, the voice box. 351 00:31:23,000 --> 00:31:24,956 With more space at the back of the throat, 352 00:31:25,080 --> 00:31:28,595 the voice box can make an extraordinary variety of sounds. 353 00:31:29,480 --> 00:31:32,711 As air passes through the gap between the vocal chords, 354 00:31:32,840 --> 00:31:35,070 it causes them to vibrate. 355 00:31:35,200 --> 00:31:38,749 The tighter the chords are, the higher the pitch. 356 00:31:38,880 --> 00:31:42,953 And the final sounds are shaped by subtle movements of the tongue. 357 00:31:46,680 --> 00:31:49,433 To create just one recognisable word, 358 00:31:49,560 --> 00:31:53,758 Zak has to coordinate over 30 different muscles. 359 00:31:53,880 --> 00:31:56,474 Mummy, Mummy! 360 00:31:59,480 --> 00:32:01,914 - Daddy! - Yeah, you're in the water. 361 00:32:02,040 --> 00:32:03,553 Cold. 362 00:32:03,680 --> 00:32:06,752 Unfortunately, this lowered voice box 363 00:32:06,880 --> 00:32:10,395 makes humans especially vulnerable to choking on food. 364 00:32:10,520 --> 00:32:12,431 As a species, however, 365 00:32:12,560 --> 00:32:16,633 this occasional problem is outweighed by the power of language. 366 00:32:16,760 --> 00:32:22,198 The human larynx has evolved so that the way it changes suits each stage in life. 367 00:32:22,320 --> 00:32:25,676 Zak can finally communicate. 368 00:32:25,800 --> 00:32:29,588 - (IN GREEK) - Mummy, vroom vroom. 369 00:32:32,120 --> 00:32:35,669 We'll go later on the vroom vroom. Later. 370 00:32:35,800 --> 00:32:37,631 - Uh-oh. - Uh-oh. 371 00:32:44,320 --> 00:32:48,393 0ver the previous year, Zak has progressed from baby to toddler. 372 00:32:48,520 --> 00:32:51,512 But the pace of change does not let up. 373 00:32:53,240 --> 00:32:57,153 Look ahead another year and the child will have raced ahead again. 374 00:32:57,960 --> 00:33:00,633 Boom, boom. 375 00:33:02,240 --> 00:33:04,674 My name is Moira. 376 00:33:04,800 --> 00:33:08,315 Oh, lovely! Look at that! We're good at this! 377 00:33:08,440 --> 00:33:11,079 High five to both of us. Yeah! 378 00:33:11,200 --> 00:33:14,875 # Now I know my ABC... # 379 00:33:15,000 --> 00:33:17,389 This little girl is two-and-a-half years old. 380 00:33:17,520 --> 00:33:21,035 Moira lives in a peaceful suburb in New Jersey. 381 00:33:21,160 --> 00:33:24,118 I'm gonna go water. 382 00:33:24,240 --> 00:33:29,189 Like all toddlers, she's learning a staggering ten new words a day. 383 00:33:29,320 --> 00:33:33,950 It did seem quite quick that she was able to communicate 384 00:33:34,080 --> 00:33:37,152 or to describe things in detail. It seemed really fast. 385 00:33:37,280 --> 00:33:39,748 Uhm...thank you. 386 00:33:39,880 --> 00:33:44,670 At one point, you think she's able to just sort of react with words, 387 00:33:44,800 --> 00:33:47,951 and then it's amazing when she's able to take words 388 00:33:48,080 --> 00:33:50,833 and think about the future and what could be possible. 389 00:33:55,160 --> 00:33:57,833 You know what this is over here? 390 00:33:59,320 --> 00:34:00,992 What do you think it is? 391 00:34:01,120 --> 00:34:04,351 (B0Y) Turkey. (W0MAN) Very good. You like turkeys? 392 00:34:04,480 --> 00:34:08,234 - Can you make the noise? - Gobble, gobble. 393 00:34:08,360 --> 00:34:11,636 - Gobble... - Gobble... 394 00:34:13,560 --> 00:34:18,190 Moira has never seen a baby deer before and doesn't know the word for it. 395 00:34:18,320 --> 00:34:21,869 This is the first time she will ever say it. 396 00:34:22,000 --> 00:34:25,117 (W0MAN) Do you know what to call one of these things? 397 00:34:25,240 --> 00:34:28,994 Well, some people call them Bambi, but that's after the movie. 398 00:34:29,120 --> 00:34:31,270 They're called a fawn. 399 00:34:32,320 --> 00:34:35,835 - Can you say that word? - Fawn. 400 00:34:41,000 --> 00:34:44,629 Not only is Moira an enormous sponge soaking up new words, 401 00:34:44,760 --> 00:34:48,639 she knows automatically how to construct them into proper sentences. 402 00:34:48,760 --> 00:34:54,869 Children have an instinctive knack for language and get the grammar right virtually all the time. 403 00:34:58,720 --> 00:35:01,029 But their occasional mistakes are telling. 404 00:35:01,160 --> 00:35:05,073 It's almost always when the grammar is irregular. 405 00:35:05,200 --> 00:35:09,637 What if I had one mouse and I had another mouse, I'd have two what? 406 00:35:09,760 --> 00:35:13,673 - Two mouses. - Two mouses? 407 00:35:13,800 --> 00:35:18,396 There's another word for plural for mouse. What is it? Do you remember? 408 00:35:19,040 --> 00:35:21,156 It'd be two...? 409 00:35:23,320 --> 00:35:25,754 - Mi... - Mice. 410 00:35:25,880 --> 00:35:28,155 Two mice, that's right. 411 00:35:28,280 --> 00:35:30,635 Very good. Good job. 412 00:35:30,760 --> 00:35:35,788 Moira created the word ''mouses'' herself by just adding an S. 413 00:35:35,920 --> 00:35:39,833 It's impossible for her to have imitated the word from an adult, 414 00:35:39,960 --> 00:35:45,080 because they never use it. Instead she applied the logical rule for making a plural 415 00:35:45,200 --> 00:35:47,430 and has to be taught the exception. 416 00:35:49,680 --> 00:35:53,229 So why is it that toddlers can learn language so rapidly? 417 00:35:53,360 --> 00:35:56,750 The theory is that throughout evolution 418 00:35:56,880 --> 00:36:00,429 little children have always faced grave dangers. 419 00:36:00,560 --> 00:36:04,599 The quicker they learnt language, and the better they understood the warnings, 420 00:36:04,720 --> 00:36:07,393 the more likely they were to survive. 421 00:36:07,520 --> 00:36:12,275 In just the same way that a clam has evolved a tough shell to protect it, 422 00:36:12,400 --> 00:36:16,029 we have evolved language as our defence. 423 00:36:16,160 --> 00:36:20,790 (W0MAN) Guys, you need to be careful of the water! Come back up here! 424 00:36:24,280 --> 00:36:28,478 But language is not just a simple one-off trick like the clam shell. 425 00:36:28,600 --> 00:36:31,637 Its power and flexibility are unique. 426 00:36:31,760 --> 00:36:35,230 It's given rise to our rich social world, 427 00:36:35,360 --> 00:36:39,717 delivering us a decisive advantage over other animals. 428 00:36:41,440 --> 00:36:45,069 Alongside language, children learn another skill, 429 00:36:45,200 --> 00:36:48,556 a skill adults rarely give much thought to. 430 00:36:49,680 --> 00:36:52,638 You and I know that this is me, 431 00:36:52,760 --> 00:36:58,118 but we also know that this is me, too. It's so simple it sounds silly. 432 00:36:58,240 --> 00:37:02,791 But, in fact, though we take our ability to understand mirrors completely for granted, 433 00:37:02,920 --> 00:37:07,357 we're one of very few animal species that has the slightest idea what's going on with them. 434 00:37:13,000 --> 00:37:16,470 A monkey can't recognise itself in a mirror. 435 00:37:18,600 --> 00:37:20,795 But a chimp can. 436 00:37:28,800 --> 00:37:33,476 Interestingly, it's a skill humans are not born with. 437 00:37:33,600 --> 00:37:38,390 14-month-old Julia ignores the red dye painted on her nose. 438 00:37:38,520 --> 00:37:41,159 She fails to recognise the reflection is her, 439 00:37:41,280 --> 00:37:44,477 because she doesn't yet have a proper sense of herself. 440 00:37:44,600 --> 00:37:47,512 Julia lacks self-awareness. 441 00:37:48,600 --> 00:37:51,160 Unlike Moira, who's over a year older. 442 00:37:51,280 --> 00:37:54,636 Yeah! Look at those pretty things! 443 00:37:54,760 --> 00:37:58,799 Moira also uses words like ''I'', ''me'', ''mine'', 444 00:37:58,920 --> 00:38:03,675 proving she is now aware she is a separate person from everyone else. 445 00:38:04,680 --> 00:38:06,636 Got you. 446 00:38:06,760 --> 00:38:08,830 - Who's that? - You and me. 447 00:38:08,960 --> 00:38:11,030 - You? - And you. 448 00:38:11,160 --> 00:38:14,391 - And me? - Yes. 449 00:38:15,640 --> 00:38:19,952 Unfortunately, there's a dark side to self-awareness, too. 450 00:38:20,080 --> 00:38:24,312 - Liam, I want Sharky! - Liam, bring the shark back, please. 451 00:38:24,440 --> 00:38:29,389 - Liam, bring the shark back, please. - I want Sharky! 452 00:38:29,520 --> 00:38:34,036 - I want Sharky! - Look, the shark's going through the sand. 453 00:38:36,840 --> 00:38:38,239 Thank you. 454 00:38:38,360 --> 00:38:41,113 Moira sometimes uses tantrums to get her way. 455 00:38:41,240 --> 00:38:43,834 This is the Terrible Twos, 456 00:38:43,960 --> 00:38:46,997 when she has the self-awareness to recognise her needs 457 00:38:47,120 --> 00:38:50,874 and the language to express them all too clearly. 458 00:38:53,440 --> 00:38:56,352 All the changes in Moira's view of the world 459 00:38:56,480 --> 00:39:01,508 are taking place because of alterations inside her maturing brain. 460 00:39:01,640 --> 00:39:04,996 Different skills, such as language and self-awareness, 461 00:39:05,120 --> 00:39:08,999 are clamouring for space in particular parts of the brain. 462 00:39:09,120 --> 00:39:11,076 But there's still something missing. 463 00:39:11,200 --> 00:39:15,352 It's a series of developments that will take two years to perfect, 464 00:39:15,480 --> 00:39:18,552 and it's all about getting on with other people. 465 00:39:24,000 --> 00:39:28,790 James is an active four-year-old who lives near Philadelphia. 466 00:39:28,920 --> 00:39:33,630 But he's unusual in that he has two brothers exactly the same age, 467 00:39:33,760 --> 00:39:35,716 Sean and Evan. 468 00:39:37,360 --> 00:39:39,715 (B0Y) I will give it back. 469 00:39:39,840 --> 00:39:44,436 (W0MAN) James. We call him our athlete. He's very athletic and pretty strong. 470 00:39:44,560 --> 00:39:48,712 Sort of acts like the older brother, because he is so much more advanced. 471 00:39:48,840 --> 00:39:52,037 - Wow! - A big one. 472 00:39:52,160 --> 00:39:54,674 Look at that bubble Evan has! 473 00:39:54,800 --> 00:39:59,635 Evan is different. He's very moody. We call him our moody artist type. 474 00:39:59,760 --> 00:40:02,149 Sean is the smallest of the three. 475 00:40:02,280 --> 00:40:05,636 And because of that, he learns to compensate a little bit. 476 00:40:05,760 --> 00:40:10,788 And so we call him our politician, because he's used to trying to negotiate for things 477 00:40:10,920 --> 00:40:13,992 and is a little more tolerant of things in general. 478 00:40:16,200 --> 00:40:19,636 Part of getting on with one another and dealing with the social world 479 00:40:19,760 --> 00:40:23,309 is learning and complying with rules. 480 00:40:23,440 --> 00:40:26,477 We got a set of rules based on their interaction. 481 00:40:26,600 --> 00:40:31,799 Mostly like, you know, no-fighting rules, no playing on the stairs. 482 00:40:31,920 --> 00:40:34,195 (W0MAN) No hitting, pulling hair. 483 00:40:34,320 --> 00:40:38,711 No hitting, no fighting, no biting, no scratching. 484 00:40:38,840 --> 00:40:42,833 No throwing, no throwing suitcases, 485 00:40:42,960 --> 00:40:45,838 no throwing bottles, no throwing houses. 486 00:40:45,960 --> 00:40:50,875 If somebody does get out of hand they do end up in their room by themselves 487 00:40:51,000 --> 00:40:54,549 for some quiet sort of time-out-themselves time. 488 00:40:54,680 --> 00:40:59,674 James! Are you supposed to be taking those cookies now? 489 00:40:59,800 --> 00:41:02,758 - Mom, just a little. - No, that's not OK. 490 00:41:02,880 --> 00:41:07,510 Are those cookies for now? No, those are special cookies. Those are for later. 491 00:41:08,880 --> 00:41:13,317 No, that's not OK. Now put the cookies back. 492 00:41:14,360 --> 00:41:17,397 Breaking the rules leads to shame. 493 00:41:17,520 --> 00:41:20,876 Look at the classic hunched shoulders and the drooped head. 494 00:41:21,000 --> 00:41:26,393 James knows he's done wrong. He's starting to acquire a conscience. 495 00:41:30,600 --> 00:41:35,435 But no sooner are children taught the rules than they discover a way to get around them. 496 00:41:35,560 --> 00:41:38,632 Lying starts surprisingly early. 497 00:41:38,760 --> 00:41:43,550 But until recently it's been considered well nigh impossible to study. 498 00:41:44,240 --> 00:41:46,435 Child psychologist Michael Lewis 499 00:41:46,560 --> 00:41:50,678 has created an ingenious test to reveal more about lying. 500 00:41:50,800 --> 00:41:55,157 He and the mother of the child he's studying hide behind a one-way mirror. 501 00:41:56,160 --> 00:41:59,948 I have a toy under here. I'm gonna uncover it, but don't look. 502 00:42:00,080 --> 00:42:04,517 I want you to keep looking straight ahead. Don't turn around, don't peek. 503 00:42:04,640 --> 00:42:08,269 I'm gonna uncover it and turn it on, but don't look. 504 00:42:08,400 --> 00:42:13,315 I have to get something I left in the hall, so I'll be back in a minute. 505 00:42:13,440 --> 00:42:17,115 But don't look at the toy while I'm gone. Keep looking straight ahead. 506 00:42:17,240 --> 00:42:20,277 When I come back we can play with it, but don't look at it, OK? 507 00:42:22,480 --> 00:42:24,357 Don't peek. 508 00:42:27,960 --> 00:42:30,190 So, what do you think he's gonna do? 509 00:42:30,320 --> 00:42:35,075 - I think he'll lie. I think he'll look. - He'll look and lie. OK. 510 00:42:35,200 --> 00:42:38,078 Let's look and see. 511 00:42:44,840 --> 00:42:47,718 He's holding out. He's holding out. 512 00:42:47,840 --> 00:42:52,197 His eyes are starting to... He's gonna peek. 513 00:42:55,040 --> 00:42:58,430 OK. You know, I have to tell you 514 00:42:58,560 --> 00:43:03,270 that three-year-old children, about 70 percent of them peek. 515 00:43:03,400 --> 00:43:07,598 And when they peek, almost all of them lie. 516 00:43:07,720 --> 00:43:10,234 Jerry, did you peek? No? Good for you. 517 00:43:10,360 --> 00:43:14,433 You wanna turn around and play? All right, go ahead and play. 518 00:43:14,560 --> 00:43:19,076 Well, you were right. They peek and then they lie about peeking. 519 00:43:19,200 --> 00:43:22,829 And they lie because they don't want to get into trouble. 520 00:43:22,960 --> 00:43:25,474 And if you think about it, it makes sense. 521 00:43:25,600 --> 00:43:30,071 Not only didn't they do something right, but they may get punished for it. 522 00:43:30,200 --> 00:43:35,672 And so it turns out that the smartest kids are not the ones who tell the truth, 523 00:43:35,800 --> 00:43:38,678 but, in fact, the ones who lie about it. 524 00:43:40,200 --> 00:43:46,435 And it's true. At this age, the higher your IQ, the more likely you are to lie. 525 00:43:50,800 --> 00:43:53,997 To lie deliberately, these children have to be aware 526 00:43:54,120 --> 00:43:58,033 that the experimenter doesn't know whether or not they've peeked. 527 00:43:58,160 --> 00:44:01,357 - Did you peek at it behind you? - No. 528 00:44:02,240 --> 00:44:07,553 This awareness that other people can have different beliefs and thoughts from your own 529 00:44:07,680 --> 00:44:12,515 is not just useful for the occasional fib. It's a crucial stage. 530 00:44:12,640 --> 00:44:17,430 All children need to pass it before they are ready for the adult world. 531 00:44:20,440 --> 00:44:26,436 Scientists call it ''theory of mind''. But it's not as difficult as it sounds. 532 00:44:26,560 --> 00:44:31,429 It's our human skill of working out what another person might be thinking. 533 00:44:31,560 --> 00:44:33,676 To do it, we need to realise 534 00:44:33,800 --> 00:44:38,669 that each of us has different wishes and intentions, likes and dislikes. 535 00:44:38,800 --> 00:44:42,270 My thoughts and desires are not necessarily the same as yours. 536 00:44:43,400 --> 00:44:46,631 We do it all the time without even being aware of it. 537 00:44:46,760 --> 00:44:51,117 Yet theory of mind is the very cornerstone of all our relationships with other people. 538 00:44:51,880 --> 00:44:56,351 But at three years old these children are too young to have learnt it. 539 00:44:57,280 --> 00:45:00,716 # Jack and Jill went up a hill... # 540 00:45:00,840 --> 00:45:05,391 The triplets are just four, and HAVE developed theory of mind. 541 00:45:05,520 --> 00:45:10,674 Take hide-and-seek. If you think about it, it's quite a sophisticated game. 542 00:45:10,800 --> 00:45:16,158 The boys know their dad won't be able to see them if they hide themselves properly. 543 00:45:16,280 --> 00:45:19,352 Roar, roar! 544 00:45:19,480 --> 00:45:22,199 Sweet, look at the hiding guys. 545 00:45:22,320 --> 00:45:25,392 They realise his view of the world can be different from their own. 546 00:45:25,520 --> 00:45:29,195 I see a hip-hop. There is the James-boy. 547 00:45:29,320 --> 00:45:34,474 Theory of mind is even more essential in making sense of stories. 548 00:45:34,600 --> 00:45:37,398 To follow what's going on in Snow White, 549 00:45:37,520 --> 00:45:42,355 the triplets need to grasp that different people will see the world differently. 550 00:45:49,160 --> 00:45:55,235 Most children younger than three will assume Snow White has the same knowledge they do: 551 00:45:55,360 --> 00:45:58,989 that the apple is poisoned and Snow White shouldn't eat it. 552 00:45:59,120 --> 00:46:02,954 This makes a nonsense of the story. The triplets, though, know better. 553 00:46:03,080 --> 00:46:07,312 - What was the old woman giving her? - An apple. 554 00:46:07,440 --> 00:46:11,831 - But what was it really? - A poisoned apple. 555 00:46:11,960 --> 00:46:15,509 - But what did Snow White think it was? - A present. 556 00:46:15,640 --> 00:46:17,631 A present. Who was that? 557 00:46:17,760 --> 00:46:20,274 A mean queen. 558 00:46:20,400 --> 00:46:25,474 - And what was she trying to do? - Hurt Snow White. 559 00:46:25,600 --> 00:46:28,478 Was it a nice thing to do? 560 00:46:28,600 --> 00:46:30,670 It was a BAD thing to do. 561 00:46:32,160 --> 00:46:38,315 Understanding what motivates others, in fairy tales or real life, seems obvious to us. 562 00:46:38,440 --> 00:46:43,036 But it's a key turning point in every child's development. 563 00:46:45,360 --> 00:46:47,749 By scanning people's brain activity, 564 00:46:47,880 --> 00:46:53,318 it's been possible to identify the part of the brain where theory of mind develops. 565 00:46:53,440 --> 00:46:55,476 Tell stories that require it, 566 00:46:55,600 --> 00:47:01,038 and this important section right at the front of the brain literally lights up. 567 00:47:01,160 --> 00:47:06,712 In the triplets, the brain connections of this area are now almost complete. 568 00:47:09,640 --> 00:47:13,394 Theory of mind is the final piece of the jigsaw. 569 00:47:13,520 --> 00:47:17,069 It marks the transition from babyhood to childhood. 570 00:47:17,200 --> 00:47:22,274 0nce a child has made it, the world will never seem the same again. 571 00:47:23,520 --> 00:47:26,990 # La cucaracha, la cucaracha 572 00:47:27,120 --> 00:47:29,588 # La, la, la, la, la, la... # 573 00:47:29,720 --> 00:47:31,790 (W0MAN) We'll miss them when they go off to school, 574 00:47:31,920 --> 00:47:36,391 because pretty much all of our time and energy goes into managing them. 575 00:47:36,520 --> 00:47:40,718 This is our favourite song again. Can you guys sing along to the song? 576 00:47:42,360 --> 00:47:46,069 We have mixed feelings. It would be great to have some time, 577 00:47:46,200 --> 00:47:52,912 but then it'll be scary to send them out into the world, just to be so independent. 578 00:47:53,040 --> 00:47:55,793 Do you have your backpacks ready? 579 00:47:57,360 --> 00:47:59,510 # La, la, la, la, la, la, la 580 00:47:59,640 --> 00:48:01,631 # 0le # 581 00:48:02,920 --> 00:48:06,037 OK, hold on. And you're next, big guy. 582 00:48:06,160 --> 00:48:08,310 - Have a good day, OK? - Bye. 583 00:48:09,080 --> 00:48:11,116 I wanna see you climb those big steps. 584 00:48:11,880 --> 00:48:15,668 Yeah. Hold on to the railing, and have a good day at school. 585 00:48:15,800 --> 00:48:17,756 0ver just four years 586 00:48:17,880 --> 00:48:23,716 the triplets have met all the challenges this new and exciting world has thrown at them: 587 00:48:23,840 --> 00:48:28,789 to walk, to talk, to understand the thoughts of others. 588 00:48:28,920 --> 00:48:32,959 They are ready for the next stage of their lives.