1 00:00:08,520 --> 00:00:12,040 I'm Jim Al-Khalili, a professor of theoretical physics, 2 00:00:12,040 --> 00:00:15,800 and I'm exploring how the most complex objects 3 00:00:15,800 --> 00:00:20,000 we know of in the universe - our brains - evolved. 4 00:00:20,000 --> 00:00:21,880 This is what your head looks like inside. 5 00:00:21,880 --> 00:00:23,000 JIM LAUGHS 6 00:00:29,040 --> 00:00:32,240 In the last episode, we went from the first neurons 7 00:00:32,240 --> 00:00:34,040 to the early mammal brain. 8 00:00:34,040 --> 00:00:35,160 Wow! 9 00:00:36,760 --> 00:00:38,280 GIBBON SHRIEKS 10 00:00:38,280 --> 00:00:42,320 In this episode, I learn how life in the forests shaped our brains... 11 00:00:44,520 --> 00:00:50,240 ..and how our primate ancestors solved problems to survive. 12 00:00:50,240 --> 00:00:52,600 Look how quick! Oh, my word! 13 00:00:54,520 --> 00:00:59,080 With my wife, I investigate how relationships made us intelligent... 14 00:00:59,080 --> 00:01:00,800 You're not a show-off like me. 15 00:01:00,800 --> 00:01:03,520 No, I'm not a show-off like you. Not many people are. 16 00:01:03,520 --> 00:01:06,520 ..and how our brains are wired to be social. 17 00:01:06,520 --> 00:01:09,039 The single best predictor 18 00:01:09,039 --> 00:01:11,760 of how long you're going to live into the future, 19 00:01:11,760 --> 00:01:14,680 it's simply the number and quality of close friendships. 20 00:01:16,760 --> 00:01:21,520 As we build artificial intelligence, vying to overtake our brains... 21 00:01:22,520 --> 00:01:27,480 ..I want to find out what makes the thing in our skulls so special. 22 00:01:28,480 --> 00:01:30,520 This is my brain, 23 00:01:30,520 --> 00:01:34,520 and this is its 600 million-year story. 24 00:01:46,039 --> 00:01:51,520 66 million years ago, the Earth lay in desolation and darkness. 25 00:01:51,520 --> 00:01:55,120 An asteroid smashed into the surface of the planet... 26 00:01:56,120 --> 00:02:00,760 ..soot and ash and vaporised bedrock dimming the sun. 27 00:02:00,760 --> 00:02:04,760 Perhaps three-quarters of all life on Earth was wiped out... 28 00:02:07,760 --> 00:02:11,520 ..including the gigantic dinosaurs, which had ruled the world. 29 00:02:12,520 --> 00:02:16,120 But as the Earth slowly recovered, forests returned 30 00:02:16,120 --> 00:02:18,360 and spread across the land. 31 00:02:19,360 --> 00:02:21,720 And with the dinosaurs gone, 32 00:02:21,720 --> 00:02:25,520 small creatures colonised this new habitat. 33 00:02:25,520 --> 00:02:28,040 Among them were our ancestors. 34 00:02:28,040 --> 00:02:32,280 Now, here's the mystery, how did they survive this catastrophe? 35 00:02:38,280 --> 00:02:42,760 Dr Ornella Bertrand studies the extremely limited evidence 36 00:02:42,760 --> 00:02:46,760 that survives from this dark period in the Earth's history. 37 00:02:47,760 --> 00:02:49,240 That is not an easy job. 38 00:02:49,240 --> 00:02:52,640 You've drawn the short straw when it comes to palaeontology, right? 39 00:02:52,640 --> 00:02:55,040 Definitely, because it's very difficult. 40 00:02:55,040 --> 00:02:56,920 There's just not that many fossils. 41 00:02:56,920 --> 00:02:59,560 We find teeth, we find, like, a bit of bone sometimes. 42 00:02:59,560 --> 00:03:02,440 One group that I'm really interested in understanding 43 00:03:02,440 --> 00:03:05,040 is a group called plesiadapiforms. 44 00:03:05,040 --> 00:03:07,920 They were little, like, warm-blooded mammals. 45 00:03:09,520 --> 00:03:13,280 Plesiadapiforms resembled modern shrews. 46 00:03:13,280 --> 00:03:16,040 It's thought they used their sharp claws 47 00:03:16,040 --> 00:03:20,760 to cling onto the branches of trees in the primeval forest. 48 00:03:20,760 --> 00:03:23,480 They're the closest we've found to the predecessors 49 00:03:23,480 --> 00:03:26,680 of all today's primates, including us. 50 00:03:27,680 --> 00:03:32,520 Ornella studies their skulls, but she doesn't have many to work with. 51 00:03:32,520 --> 00:03:35,440 We only have, like, six good specimens so far. 52 00:03:35,440 --> 00:03:40,120 Six specimens in total... In total. ..of these creatures? Yeah, yeah. 53 00:03:40,120 --> 00:03:42,920 So that's very little, but we can learn so much 54 00:03:42,920 --> 00:03:44,920 just from those different skulls. 55 00:03:44,920 --> 00:03:49,520 Ornella has a 3D print of the skull of a specimen 56 00:03:49,520 --> 00:03:55,360 called Ignacius graybullianus, upscaled so we can see the details. 57 00:03:55,360 --> 00:03:58,520 By scanning the cavity inside the skull, 58 00:03:58,520 --> 00:04:02,040 she's been able to produce a cast of the missing brain. 59 00:04:02,040 --> 00:04:05,000 Ta-dah! It's amazing, isn't it? That is incredible. 60 00:04:05,000 --> 00:04:08,040 It gives us, like, so much information about 61 00:04:08,040 --> 00:04:10,520 what actually those animals were able to do. 62 00:04:10,520 --> 00:04:12,960 For example, these structures in front. 63 00:04:12,960 --> 00:04:14,680 I was just going to ask you. 64 00:04:14,680 --> 00:04:17,279 They're funny little knobbly bits at the front. Yes! 65 00:04:17,279 --> 00:04:20,360 We still have that structure, the olfactory bulbs, in humans. 66 00:04:20,360 --> 00:04:22,840 They're olfactory? OK. So that's for smell? 67 00:04:22,840 --> 00:04:24,520 Yeah, yeah, exactly. 68 00:04:25,520 --> 00:04:30,400 Plesiadapiforms had very large smell-processing systems. 69 00:04:31,400 --> 00:04:35,280 Ornella believes they may have scavenged at dusk and at night, 70 00:04:35,280 --> 00:04:38,440 when a strong sense of smell is very useful. 71 00:04:39,440 --> 00:04:42,800 I imagine them being, like, quietly moving among the branches. 72 00:04:42,800 --> 00:04:45,159 That's kind of, yeah, how I see them. 73 00:04:45,159 --> 00:04:49,640 For this documentary, I've had my brain scanned. 74 00:04:49,640 --> 00:04:52,120 I've been carrying around... 75 00:04:53,120 --> 00:04:56,280 ..a 3D-printed version of my brain. Wow! 76 00:04:56,280 --> 00:05:00,000 Which is here, which I'm very proud of. I would be. That's amazing! 77 00:05:00,000 --> 00:05:01,920 Which we can put alongside Ignacius. 78 00:05:01,920 --> 00:05:04,960 Look, I'm not boasting - there's been some evolution. 79 00:05:04,960 --> 00:05:07,280 Some... Just a little bit! 80 00:05:04,960 --> 00:05:07,280 SHE CHUCKLES 81 00:05:08,280 --> 00:05:11,280 I'm interested in a particular part of the brain - 82 00:05:11,280 --> 00:05:13,040 the neocortex. 83 00:05:14,040 --> 00:05:16,680 So, here we have the neocortex of Ignacius. 84 00:05:16,680 --> 00:05:19,920 It's very small. It's actually just this part of the brain. 85 00:05:19,920 --> 00:05:24,520 In Ignacius, it covers about 20% of the top of the brain. 86 00:05:24,520 --> 00:05:27,280 That's very different in a human brain, isn't it? 87 00:05:27,280 --> 00:05:30,520 Very, very different. You can see, like, the neocortex in humans 88 00:05:30,520 --> 00:05:33,000 actually is covering the entire rest of the brain. 89 00:05:33,000 --> 00:05:36,000 This is amazing, how big that it got in humans. 90 00:05:38,520 --> 00:05:41,920 A rudimentary neocortex helped early mammals 91 00:05:41,920 --> 00:05:45,960 analyse the world around them and respond to it. 92 00:05:45,960 --> 00:05:49,520 For humans, it's become the seat of advanced thinking, 93 00:05:49,520 --> 00:05:52,040 reasoning and perception. 94 00:05:52,040 --> 00:05:56,720 But the mystery is, why did our neocortex grow so large 95 00:05:56,720 --> 00:05:59,280 compared to any other mammal? 96 00:05:59,280 --> 00:06:04,040 There's a compelling theory and it's to do with climate change. 97 00:06:05,040 --> 00:06:07,360 About 56 million years ago, 98 00:06:07,360 --> 00:06:09,040 greenhouse gases, 99 00:06:09,040 --> 00:06:11,280 released by volcanic activity, 100 00:06:11,280 --> 00:06:13,720 caused sudden global warming 101 00:06:13,720 --> 00:06:15,520 of up to five degrees. 102 00:06:18,280 --> 00:06:21,440 It was the beginning of the Eocene Era - 103 00:06:21,440 --> 00:06:23,840 a time of astonishing changes. 104 00:06:25,280 --> 00:06:28,360 In the hothouse environment of the Eocene, 105 00:06:28,360 --> 00:06:31,520 dense rainforests spread around the world. 106 00:06:31,520 --> 00:06:33,760 They even reached high enough latitudes 107 00:06:33,760 --> 00:06:36,360 to be within what is today the Arctic Circle. 108 00:06:36,360 --> 00:06:41,040 And, as with the rainforests of today, life proliferated. 109 00:06:42,520 --> 00:06:46,520 Just look at these extraordinary fossils, found near Frankfurt 110 00:06:46,520 --> 00:06:50,520 in Germany, dating nearly 50 million years ago. 111 00:06:50,520 --> 00:06:54,040 They give us an incredible insight into the competition 112 00:06:54,040 --> 00:06:57,280 which raged in the forests of the early Eocene. 113 00:07:00,040 --> 00:07:04,600 There were birds and agile, tree-dwelling rodents. 114 00:07:04,600 --> 00:07:07,520 There were highly-dangerous predators, too. 115 00:07:07,520 --> 00:07:11,760 All of this meant fierce competition for food and resources 116 00:07:11,760 --> 00:07:14,280 and, with all these new predators around, 117 00:07:14,280 --> 00:07:16,520 it was much more dangerous, too. 118 00:07:16,520 --> 00:07:20,040 Only those creatures able to adapt would survive. 119 00:07:23,520 --> 00:07:25,920 In these changed circumstances, 120 00:07:25,920 --> 00:07:30,520 simply staying alive would take brains as well as brawn. 121 00:07:35,000 --> 00:07:37,480 As I'm very quickly finding out, 122 00:07:37,480 --> 00:07:40,280 a tree is a tricky place to call home. 123 00:07:40,280 --> 00:07:43,280 It's actually quite difficult, moving around up here. 124 00:07:43,280 --> 00:07:45,760 It doesn't just take physical strength, 125 00:07:45,760 --> 00:07:48,760 you need judgment, you need to decide whether a branch 126 00:07:48,760 --> 00:07:50,840 is strong enough to hold your weight, 127 00:07:50,840 --> 00:07:54,680 whether it's too wobbly, you need to plan a route through the trees. 128 00:07:54,680 --> 00:07:58,040 On top of the physical and mental agility you need, 129 00:07:58,040 --> 00:08:01,280 coping with the incredibly complex visual field 130 00:08:01,280 --> 00:08:05,040 of a canopy of leaves poses yet more problems. 131 00:08:05,040 --> 00:08:07,080 I'm finding it really difficult, 132 00:08:07,080 --> 00:08:09,560 peering through the leaves and twigs and branches. 133 00:08:09,560 --> 00:08:13,360 Keeping an eye out for predators, as well as foraging for food, 134 00:08:13,360 --> 00:08:15,120 must have been a real challenge. 135 00:08:16,760 --> 00:08:19,680 In the face of these evolutionary pressures, 136 00:08:19,680 --> 00:08:24,520 a new kind of creature appears in the fossil record of the Eocene. 137 00:08:26,040 --> 00:08:29,280 They're called crown primates - the forerunners 138 00:08:29,280 --> 00:08:32,760 of all today's primates - including, of course, us. 139 00:08:39,159 --> 00:08:41,080 Is this the way we sit? 140 00:08:41,080 --> 00:08:43,120 Like this? 141 00:08:43,120 --> 00:08:47,560 Early primates were well-adapted to life in the trees. 142 00:08:47,560 --> 00:08:52,400 What's interesting is the way he's grasping the branch. 143 00:08:56,040 --> 00:09:01,360 During the Eocene, primates evolved gripping hands and feet with nails. 144 00:09:09,760 --> 00:09:11,640 They're much more dextrous. 145 00:09:11,640 --> 00:09:14,280 They're able to hold on to this branch. 146 00:09:14,280 --> 00:09:17,520 It also means they can use these hands to find food, 147 00:09:17,520 --> 00:09:20,840 to forage, to manipulate objects much more easily. 148 00:09:25,760 --> 00:09:28,520 The other thing to notice is that they have eyes 149 00:09:28,520 --> 00:09:31,360 at the front of their heads, not on the side. 150 00:09:32,360 --> 00:09:35,040 Animals with eyes on the side of their heads 151 00:09:35,040 --> 00:09:38,760 have a wider field of view and can spot predators better. 152 00:09:40,760 --> 00:09:44,120 But eyes at the front help with what's ahead of you, 153 00:09:44,120 --> 00:09:48,040 judging the distance to the next branch or locating food. 154 00:09:53,720 --> 00:09:57,440 The effect of millions of years of tree-dwelling is clear 155 00:09:57,440 --> 00:09:59,680 when we look at the fossil record. 156 00:09:59,680 --> 00:10:04,040 This is the brain cast of Ignacius, the plesiadapiform 157 00:10:04,040 --> 00:10:06,920 we've already seen clambering around the forest 158 00:10:06,920 --> 00:10:10,040 in the years after the dinosaur extinction. 159 00:10:10,040 --> 00:10:15,040 And this is the brain cast of a primate called Rooneyia. 160 00:10:15,040 --> 00:10:19,040 It evolved around 20 million years after Ignacius. 161 00:10:20,040 --> 00:10:24,680 With Ignacius, the neocortex covered 20% of its brain. 162 00:10:24,680 --> 00:10:28,760 With Rooneyia, it now covers half its brain. 163 00:10:32,040 --> 00:10:35,560 The neocortex analyses visual data... 164 00:10:38,360 --> 00:10:41,240 ..and it has many other functions besides. 165 00:10:42,240 --> 00:10:45,280 It works in extraordinarily complex ways, 166 00:10:45,280 --> 00:10:48,760 which we take for granted in our everyday lives. 167 00:10:50,280 --> 00:10:53,600 Take, for instance, what happens inside our brains 168 00:10:53,600 --> 00:10:56,280 when we do something as deceptively simple 169 00:10:56,280 --> 00:10:58,920 as reaching out and grabbing an apple. 170 00:10:58,920 --> 00:11:02,040 It's actually far more complicated than you might think. 171 00:11:07,760 --> 00:11:11,280 I'm getting an extraordinary insight into what's involved 172 00:11:11,280 --> 00:11:14,080 when we reach out and grab something. 173 00:11:15,080 --> 00:11:18,520 Dr David Pitcher at the University of York has carried out 174 00:11:18,520 --> 00:11:23,280 a functional MRI, which measures the way the blood flows in my brain... 175 00:11:24,360 --> 00:11:27,440 OK, Jim, this is going to be an eight-minute scan. 176 00:11:27,440 --> 00:11:31,760 ..while he plays me videos of reaching out and grasping an apple. 177 00:11:33,520 --> 00:11:36,920 My colleague, Amelle, is going to put this... Hello. Right. 178 00:11:36,920 --> 00:11:38,520 ..on your head. 179 00:11:38,520 --> 00:11:41,480 Then he uploads my results to this machine... 180 00:11:43,040 --> 00:11:46,280 ..which uses spatial recognition technology 181 00:11:46,280 --> 00:11:49,200 to guide me around my own brain. 182 00:11:49,200 --> 00:11:52,920 Now where she points to with that pointer... Ah! 183 00:11:52,920 --> 00:11:55,280 This is what your head looks like inside. 184 00:11:55,280 --> 00:11:58,040 JIM LAUGHS Lovely death mask well, isn't it? 185 00:11:58,040 --> 00:12:00,960 Oh, I can rotate that for you as well, so we can see. 186 00:12:00,960 --> 00:12:02,680 DAVID LAUGHS 187 00:12:02,680 --> 00:12:07,760 My scan shows astonishing activity across my cerebral cortex 188 00:12:07,760 --> 00:12:09,760 as I watch the video. 189 00:12:09,760 --> 00:12:14,040 First, David shows me how my visual processing works - 190 00:12:14,040 --> 00:12:17,520 a complex system which really started to develop 191 00:12:17,520 --> 00:12:19,840 with those early primates. 192 00:12:19,840 --> 00:12:22,040 Light hits your eyeball, 193 00:12:22,040 --> 00:12:24,920 that's then converted into neural signalling. 194 00:12:24,920 --> 00:12:28,040 That information is then sent down the optic nerve, 195 00:12:28,040 --> 00:12:30,280 all the way to primary visual cortex, 196 00:12:30,280 --> 00:12:33,080 which, in humans, is right at the back of your head. 197 00:12:33,080 --> 00:12:37,520 As I was looking at the apple, my visual cortex connected 198 00:12:37,520 --> 00:12:42,360 with another part of my brain which helps us recognise objects. 199 00:12:42,360 --> 00:12:44,520 You see this pathway that lights up? 200 00:12:44,520 --> 00:12:47,040 This is the ventral object recognition pathway. 201 00:12:47,040 --> 00:12:49,680 And that pathway leads to the bit of the brain 202 00:12:49,680 --> 00:12:53,320 where I'm storing information of what apples look like? Yeah. 203 00:12:53,320 --> 00:12:56,920 The hard drive of my brain. It's where we store everything, yeah. 204 00:12:56,920 --> 00:13:00,520 Then a second connection activates from the visual cortex 205 00:13:00,520 --> 00:13:03,520 at the back of the brain to the parietal lobe. 206 00:13:03,520 --> 00:13:07,520 The parietal lobe judges where things are in space around us 207 00:13:07,520 --> 00:13:09,960 and where our body is positioned. 208 00:13:09,960 --> 00:13:13,120 But to issue the orders to the body to move, 209 00:13:13,120 --> 00:13:15,560 you need a third part of the neocortex - 210 00:13:15,560 --> 00:13:18,040 the primary motor cortex. 211 00:13:19,040 --> 00:13:21,200 This is your motor cortex, 212 00:13:21,200 --> 00:13:24,520 and there's parts that control all the motor function in your body. 213 00:13:24,520 --> 00:13:27,520 And if Amelle moves the pen down the side of your head, 214 00:13:27,520 --> 00:13:31,480 we're sort of tracking through different parts of the motor cortex. 215 00:13:31,480 --> 00:13:34,040 And where we come to... 216 00:13:34,040 --> 00:13:36,760 ..sort of roughly where Amelle is now, 217 00:13:36,760 --> 00:13:38,920 that's roughly where the hand area is. 218 00:13:38,920 --> 00:13:42,040 So that's the... So different parts of the motor cortex 219 00:13:42,040 --> 00:13:47,000 physically relate to different parts of my body? Exactly. 220 00:13:47,000 --> 00:13:50,520 The visual, parietal and motor cortex 221 00:13:50,520 --> 00:13:53,760 all developed in our primate ancestors, 222 00:13:53,760 --> 00:13:58,520 and a new area of the neocortex was also beginning to evolve. 223 00:13:58,520 --> 00:14:01,280 It would become the most sophisticated 224 00:14:01,280 --> 00:14:04,040 cognitive area of our brains. 225 00:14:04,040 --> 00:14:05,840 The other thing you have to do 226 00:14:05,840 --> 00:14:08,520 is be able to plan and control the motor action, 227 00:14:08,520 --> 00:14:11,400 so if Amelle brings the pointer forward a little bit, 228 00:14:11,400 --> 00:14:14,520 is the prefrontal cortex. It's where we do all our thinking, 229 00:14:14,520 --> 00:14:17,800 it's where cognitive control happens - the voice inside your head. 230 00:14:20,040 --> 00:14:24,040 So, just picking up an apple means the visual cortex, 231 00:14:24,040 --> 00:14:29,520 the parietal lobe, the motor cortex, and the prefrontal cortex 232 00:14:29,520 --> 00:14:32,040 all have to work together. 233 00:14:33,520 --> 00:14:37,040 So four different parts of the brain 234 00:14:37,040 --> 00:14:39,760 are all involved in the simple action 235 00:14:39,760 --> 00:14:42,040 of reaching out and picking up an apple - 236 00:14:42,040 --> 00:14:46,840 visual cortex, parietal lobe, motor cortex, frontal cortex. 237 00:14:50,040 --> 00:14:52,040 From 40 million years ago, 238 00:14:52,040 --> 00:14:54,560 the creatures we now call monkeys 239 00:14:54,560 --> 00:14:55,760 were evolving. 240 00:14:55,760 --> 00:14:58,440 Their neocortex was becoming bigger 241 00:14:58,440 --> 00:15:00,760 and more complex in structure. 242 00:15:01,760 --> 00:15:03,120 In today's primates, 243 00:15:03,120 --> 00:15:04,520 the larger the brain, 244 00:15:04,520 --> 00:15:07,760 the denser and more closely packed the neurons, 245 00:15:07,760 --> 00:15:11,760 the more networks they develop, the cleverer they become. 246 00:15:14,640 --> 00:15:17,440 So what were the driving factors 247 00:15:17,440 --> 00:15:22,080 which caused some primates to evolve differently from others? 248 00:15:22,080 --> 00:15:25,280 And why did humans evolve the most intelligence? 249 00:15:25,280 --> 00:15:29,040 One theory has to do with the ability to find the best, 250 00:15:29,040 --> 00:15:32,520 most calorific food, and is something we can study 251 00:15:32,520 --> 00:15:36,920 by looking at two species of modern monkeys side-by-side. 252 00:15:36,920 --> 00:15:40,120 So, this is the viewing deck, and here we can see both species - 253 00:15:40,120 --> 00:15:42,840 the capuchins and the squirrel monkeys. 254 00:15:44,360 --> 00:15:47,040 They're our relatives, but if we study enough 255 00:15:47,040 --> 00:15:50,040 of our primate relatives, we can start to make inferences 256 00:15:50,040 --> 00:15:53,280 about what our ancestors - our primate ancestors - 257 00:15:53,280 --> 00:15:54,840 might have been like. 258 00:15:55,840 --> 00:15:59,680 This is The Living Link Centre at Edinburgh Zoo. 259 00:15:59,680 --> 00:16:04,360 Professor Amanda Seed studies these species side-by-side 260 00:16:04,360 --> 00:16:07,920 to try to understand the story of our own brains. 261 00:16:07,920 --> 00:16:11,200 The capuchin monkeys are our larger monkeys, they're more robust. 262 00:16:11,200 --> 00:16:14,920 They have this characteristic dark colouring on their head 263 00:16:14,920 --> 00:16:17,760 and a little tuft at the front. The squirrel monkeys, 264 00:16:17,760 --> 00:16:20,880 on the other hand, they're smaller, they're more slender. 265 00:16:20,880 --> 00:16:23,760 They look a little bit like they've been dipped in chocolate. 266 00:16:23,760 --> 00:16:26,840 Capuchin monkeys and squirrel monkeys evolved together 267 00:16:26,840 --> 00:16:29,760 in the same place - the forests of the new world, 268 00:16:29,760 --> 00:16:33,760 and yet capuchins have a much larger neocortex 269 00:16:33,760 --> 00:16:38,520 compared to their body size and exhibit greater intelligence. 270 00:16:38,520 --> 00:16:40,520 The question is, why? 271 00:16:40,520 --> 00:16:44,680 And what might that tell us about the evolution of our own brains? 272 00:16:44,680 --> 00:16:47,920 Amanda and her staff have devised a challenge 273 00:16:47,920 --> 00:16:50,760 these monkeys haven't encountered before. 274 00:16:50,760 --> 00:16:54,520 They've hidden food in papier mache boxes. 275 00:16:54,520 --> 00:16:57,800 The challenge is, which species will figure out 276 00:16:57,800 --> 00:17:00,760 that there's food inside and manage to get it? 277 00:17:05,040 --> 00:17:07,440 Straight in. "Thank you very much." 278 00:17:11,520 --> 00:17:14,400 Straight away, the capuchins have come out. 279 00:17:16,319 --> 00:17:19,520 They're very, very curious and their first thought is, 280 00:17:19,520 --> 00:17:21,800 "Can I break it? Is there food inside?" 281 00:17:25,520 --> 00:17:29,440 Meanwhile, the squirrel monkeys hang around on the sides, 282 00:17:29,440 --> 00:17:32,320 and not one of them looks inside a box. 283 00:17:32,320 --> 00:17:35,840 Instead, they wait for the capuchins to finish feasting 284 00:17:35,840 --> 00:17:38,840 and they pick up scraps from their table. 285 00:17:40,520 --> 00:17:44,840 Amanda believes today's test has helped confirm a theory 286 00:17:44,840 --> 00:17:47,520 which links intelligence to diet. 287 00:17:47,520 --> 00:17:51,520 The capuchins rely on fruit to a much greater extent 288 00:17:51,520 --> 00:17:54,200 than the squirrel monkeys. The squirrel monkeys 289 00:17:54,200 --> 00:17:57,800 eat fruit as well, but their diet is largely comprised of insects. 290 00:17:57,800 --> 00:18:01,280 The squirrel monkeys just have to wait for an insect to come along 291 00:18:01,280 --> 00:18:04,280 and grab it, and that happens a lot, 292 00:18:04,280 --> 00:18:08,040 but fruit only appears a few months every year. 293 00:18:08,040 --> 00:18:10,680 It's found around the forest in patches, 294 00:18:10,680 --> 00:18:13,280 in often hard-to-find places. 295 00:18:13,280 --> 00:18:18,040 So, in order to find it, you have to remember and plan ahead. 296 00:18:19,040 --> 00:18:22,520 An ability to map your environment and space, 297 00:18:22,520 --> 00:18:26,040 and even time, to be able to predict when those resources 298 00:18:26,040 --> 00:18:29,040 are going to become available now becomes useful, 299 00:18:29,040 --> 00:18:31,520 and so now we have more selective pressure 300 00:18:31,520 --> 00:18:34,160 for areas of the brain that can deal with that. 301 00:18:34,160 --> 00:18:37,280 The penny's starting to drop for me now, that it's not so much 302 00:18:37,280 --> 00:18:40,760 that they have larger brains, they're smarter, therefore they're 303 00:18:40,760 --> 00:18:43,960 able to figure out things like, you know, how to find food. 304 00:18:43,960 --> 00:18:46,920 The need to look for food has stimulated the growth 305 00:18:46,920 --> 00:18:50,360 of a larger brain over millions of years. Over millions of years. 306 00:18:51,680 --> 00:18:55,120 So it may be that at some point in our evolution, 307 00:18:55,120 --> 00:18:58,040 our ancestors were like the capuchins, 308 00:18:58,040 --> 00:19:01,360 they concentrated more and more on fruit - 309 00:19:01,360 --> 00:19:04,520 high-calorie fuel for growing brains - 310 00:19:04,520 --> 00:19:07,520 but it takes more intelligence to find. 311 00:19:09,280 --> 00:19:11,400 By 25 million years ago, 312 00:19:11,400 --> 00:19:14,040 the first apes were evolving. 313 00:19:14,040 --> 00:19:15,680 Ape brains are generally 314 00:19:15,680 --> 00:19:17,040 larger than monkeys 315 00:19:17,040 --> 00:19:18,880 and they have more complex 316 00:19:18,880 --> 00:19:20,760 structures and networks. 317 00:19:24,280 --> 00:19:27,040 It's now thought that around this time, 318 00:19:27,040 --> 00:19:30,040 our ancestors took their first baby steps 319 00:19:30,040 --> 00:19:33,840 towards one of our most important cognitive abilities - 320 00:19:33,840 --> 00:19:36,440 complex spoken language. 321 00:19:42,040 --> 00:19:45,040 I've come to see something very unexpected, 322 00:19:45,040 --> 00:19:47,760 which might provide a vital clue. 323 00:19:50,040 --> 00:19:54,240 These gorillas live at Port Lympne Safari Park in Kent. 324 00:19:55,240 --> 00:19:57,840 I'm with Professor Gillian Forrester, 325 00:19:57,840 --> 00:20:01,520 who's been studying the primates at this sanctuary for 20 years. 326 00:20:01,520 --> 00:20:04,280 I really like working here at Port Lympne, 327 00:20:04,280 --> 00:20:09,040 because it feels like more of a collaboration with the gorillas. 328 00:20:09,040 --> 00:20:13,280 We work together, but they're in an environment that really suits them. 329 00:20:13,280 --> 00:20:17,480 The enclosure was made for them, not for people to view them. Right. 330 00:20:21,040 --> 00:20:25,040 It's lunchtime, and the gorillas have an unusual treat. 331 00:20:29,040 --> 00:20:32,280 Nettles - which they find very tasty. 332 00:20:35,040 --> 00:20:39,280 They've found a clever strategy to deal with their stinging leaves. 333 00:20:42,040 --> 00:20:45,760 They strip the nettles off the stem in one direction - 334 00:20:45,760 --> 00:20:48,520 a direction which doesn't trigger the spines, 335 00:20:48,520 --> 00:20:50,040 so they don't get stung. 336 00:20:51,280 --> 00:20:55,080 One gorilla decides to literally walk away with her spoils. 337 00:20:55,080 --> 00:20:58,040 "These are mine." Look at her go! Fantastic! 338 00:20:59,040 --> 00:21:02,040 We follow this gorilla to the inside area, 339 00:21:02,040 --> 00:21:07,280 where we catch a glimpse of a more complex form of nettle preparation. 340 00:21:08,280 --> 00:21:13,040 Rolling the leaves into a ball to crush the stinging spines. 341 00:21:13,040 --> 00:21:16,520 This method of preparing nettles has been recorded 342 00:21:16,520 --> 00:21:18,760 in many different gorilla groups. 343 00:21:24,680 --> 00:21:27,280 And you want me to try this, don't you? Yeah. 344 00:21:27,280 --> 00:21:30,360 OK, right, let's see how we go. Let's see. 345 00:21:30,360 --> 00:21:32,920 Ah! Well, OK, there we go. 346 00:21:32,920 --> 00:21:36,640 I was so careful not to get stung, which I think I've survived, 347 00:21:36,640 --> 00:21:39,920 but I've dropped the leaves. Dropped the leaves, yeah. 348 00:21:42,360 --> 00:21:45,560 Not as delicate as you. No, but... But nearly there. Yeah. 349 00:21:45,560 --> 00:21:50,040 I think it's interesting because eating the nettles requires 350 00:21:50,040 --> 00:21:54,760 the gorillas to take certain actions in order to not get stung. OK. 351 00:21:54,760 --> 00:21:57,360 We could think of that as almost like 352 00:21:57,360 --> 00:22:00,000 what we'd call a syntax in language. 353 00:22:00,000 --> 00:22:04,040 When I speak, these are motor action sequences. 354 00:22:04,040 --> 00:22:08,120 So my mouth has to make the right words at the right time 355 00:22:08,120 --> 00:22:10,960 in order for you to understand what I'm saying. 356 00:22:10,960 --> 00:22:13,040 This is a syntax in language, 357 00:22:13,040 --> 00:22:16,200 and this is a syntax in its physical form. 358 00:22:17,200 --> 00:22:20,040 Gillian has created some puzzle boards, 359 00:22:20,040 --> 00:22:24,040 which require an understanding of more complicated syntax 360 00:22:24,040 --> 00:22:25,920 than nettle-stripping. 361 00:22:25,920 --> 00:22:28,840 The boards have a series of cogs. 362 00:22:28,840 --> 00:22:33,280 The question is, can great apes turn them in the right direction, 363 00:22:33,280 --> 00:22:35,880 in the right order, to solve the puzzles? 364 00:22:35,880 --> 00:22:38,600 Sorry, Jim, but you've got that the wrong way 'round. 365 00:22:38,600 --> 00:22:40,400 Argh! 366 00:22:40,400 --> 00:22:41,800 GILLIAN LAUGHS 367 00:22:41,800 --> 00:22:45,840 We're trying out her puzzle boards on two orangutan brothers - 368 00:22:45,840 --> 00:22:47,640 Malu and Haddy. 369 00:22:47,640 --> 00:22:49,360 Oh, here they are. 370 00:22:54,520 --> 00:22:57,760 Oh, look at that. Oh, they're right in there. Straight away. 371 00:22:57,760 --> 00:23:00,560 They've spotted the nuts, which Gillian has put 372 00:23:00,560 --> 00:23:02,760 at the top of the puzzle boards. 373 00:23:02,760 --> 00:23:04,520 But, to get them out, 374 00:23:04,520 --> 00:23:07,920 they'll have to manoeuvre the nuts to the bottom of the board. 375 00:23:08,920 --> 00:23:12,680 On his board, Haddy tries using a twig as a tool, 376 00:23:12,680 --> 00:23:14,760 but that's not going to work. 377 00:23:16,280 --> 00:23:20,680 Over on the other board, Malu lands on the correct solution. 378 00:23:20,680 --> 00:23:24,840 Oh, look at that. OK, that's Malu. Wow. Malu's worked that out. 379 00:23:24,840 --> 00:23:26,760 Well done. Here we go. 380 00:23:27,760 --> 00:23:31,920 Malu's got into the second set of cogs, and now he... 381 00:23:31,920 --> 00:23:35,040 Oh, look how quick! Oh, my word! 382 00:23:36,040 --> 00:23:39,360 I can't believe how fluid his movements are. 383 00:23:43,520 --> 00:23:45,760 He's getting to the last stage now. 384 00:23:45,760 --> 00:23:47,920 This is the double cog, the exciting bit. 385 00:23:47,920 --> 00:23:51,280 Will he think about...? Yes, he's thought about which way to turn it. 386 00:23:51,280 --> 00:23:53,520 Ah! He's gone to the access point. 387 00:23:53,520 --> 00:23:55,680 This could be the solution. 388 00:23:57,520 --> 00:24:00,360 OK, he's been... I mean, the last... 389 00:24:00,360 --> 00:24:04,520 Oh, look, at the last stage... No! ..and big brother has taken over. 390 00:24:04,520 --> 00:24:08,760 Big brother's taken over and Haddy is going to get the reward. 391 00:24:12,040 --> 00:24:16,240 But between them, they've solved it. Yes, it was a collaboration! 392 00:24:16,240 --> 00:24:17,920 GILLIAN LAUGHS 393 00:24:17,920 --> 00:24:21,040 Gillian is convinced that our ape ancestors 394 00:24:21,040 --> 00:24:25,080 developed the ability to solve ever more complicated 395 00:24:25,080 --> 00:24:29,520 physical syntax problems and were unknowingly building 396 00:24:29,520 --> 00:24:34,280 the foundations of what would one day become language. 397 00:24:35,760 --> 00:24:38,680 Our ancestors split from orangutans 398 00:24:38,680 --> 00:24:40,920 around 17 million years ago 399 00:24:40,920 --> 00:24:42,200 and from gorillas 400 00:24:42,200 --> 00:24:44,240 about ten million years ago. 401 00:24:45,240 --> 00:24:49,520 Again, climate change was bringing new threats. 402 00:24:49,520 --> 00:24:53,040 Millions of years of slow global cooling 403 00:24:53,040 --> 00:24:55,520 meant that rainforests were retreating, 404 00:24:55,520 --> 00:24:59,240 to be replaced by open grasslands and woodland. 405 00:24:59,240 --> 00:25:04,040 Competition for the most nutritious and calorific foods 406 00:25:04,040 --> 00:25:07,520 in the rainforest was becoming ever more intense. 407 00:25:07,520 --> 00:25:11,920 Life for our primate ancestors was getting harder and harder. 408 00:25:14,280 --> 00:25:18,920 Survival would now depend on making finely-balanced judgments 409 00:25:18,920 --> 00:25:22,720 based on limited information about where to find food. 410 00:25:24,520 --> 00:25:28,040 To find out what mark climate change made on our brains, 411 00:25:28,040 --> 00:25:30,040 I'm visiting the chimpanzees 412 00:25:30,040 --> 00:25:33,440 who live at Budongo Research Unit at Edinburgh Zoo. 413 00:25:34,440 --> 00:25:38,160 Along with bonobos, they're our closest primate relatives. 414 00:25:39,160 --> 00:25:41,520 I've been told I can play a game with them 415 00:25:41,520 --> 00:25:43,600 to test their cognitive powers... 416 00:25:43,600 --> 00:25:46,120 Not one of you has said thank you yet. 417 00:25:46,120 --> 00:25:50,280 ..so I head to the indoor part of their living quarters. 418 00:25:50,280 --> 00:25:55,080 When the chimps start making their noises, it is really loud in here. 419 00:25:55,080 --> 00:25:57,560 CHIMPANZEES SCREECH 420 00:25:58,560 --> 00:26:03,080 The chimpanzees have complete freedom to do as they like here, 421 00:26:03,080 --> 00:26:06,520 so I have to wait to see if one of them wants to join me. 422 00:26:06,520 --> 00:26:08,520 CHIMPANZEE GRUNTS 423 00:26:12,280 --> 00:26:16,840 Eventually, four-year-old Masindi decides she wants to play. 424 00:26:16,840 --> 00:26:18,840 Masindi, look. 425 00:26:18,840 --> 00:26:22,560 To get the game started, I show her two empty cups. 426 00:26:22,560 --> 00:26:24,200 Nothing. 427 00:26:24,200 --> 00:26:27,040 Then I cover them with a screen... 428 00:26:27,040 --> 00:26:29,600 ..and put a grape under one of them. 429 00:26:29,600 --> 00:26:31,360 Do you feel lucky? 430 00:26:31,360 --> 00:26:35,560 I'll put it under this one, pretend to put it under this one. 431 00:26:35,560 --> 00:26:39,040 She doesn't know which cup has the grape, 432 00:26:39,040 --> 00:26:41,440 so she guesses the cup on the left. 433 00:26:41,440 --> 00:26:43,120 That one? OK. 434 00:26:43,120 --> 00:26:45,480 But now I complicate things. 435 00:26:45,480 --> 00:26:47,360 I move this cup back? Yeah. 436 00:26:47,360 --> 00:26:51,920 I remove the cup she doesn't want and offer her an alternative - 437 00:26:51,920 --> 00:26:53,520 a half-grape. 438 00:26:53,520 --> 00:26:55,400 Now what do you want? 439 00:26:55,400 --> 00:26:57,280 So now she has a choice - 440 00:26:57,280 --> 00:27:00,520 pick up a cup which may or may not have a grape under it, 441 00:27:00,520 --> 00:27:03,760 or settle for a guaranteed half-grape. 442 00:27:04,760 --> 00:27:06,280 This one? 443 00:27:06,280 --> 00:27:08,040 That one, you want? 444 00:27:08,040 --> 00:27:10,760 OK, well, look... Look what you could have won. 445 00:27:10,760 --> 00:27:13,040 But, unfortunately, you have a half. 446 00:27:13,040 --> 00:27:14,920 She's chosen the half-grape. 447 00:27:14,920 --> 00:27:16,760 It's a safe decision, 448 00:27:16,760 --> 00:27:20,040 but she's missed the chance of winning a full one. 449 00:27:21,040 --> 00:27:24,280 And that's the choice they have to make - whether they want 450 00:27:24,280 --> 00:27:28,560 half a grape for sure or a whole grape half of the time. 451 00:27:28,560 --> 00:27:32,680 We play the game again, and this time, she sticks with the cup. 452 00:27:34,040 --> 00:27:36,760 You're going for it, are you? Are you confident? 453 00:27:38,040 --> 00:27:39,440 Clever! 454 00:27:39,440 --> 00:27:43,040 Of course, Masindi's having to guess if the cup has a grape under it. 455 00:27:43,040 --> 00:27:47,600 But now, what happens if I give her more information to act on? 456 00:27:49,280 --> 00:27:53,120 I offer her two cups with one grape, as usual, 457 00:27:53,120 --> 00:27:57,000 but this time I show her that one of them is empty. 458 00:28:01,320 --> 00:28:04,040 Let's see. This is... This is going to be the clincher. 459 00:28:04,040 --> 00:28:05,680 What are you going to...? 460 00:28:05,680 --> 00:28:07,760 Good girl! You... Yes! 461 00:28:07,760 --> 00:28:10,360 You've got it. Well done! 462 00:28:10,360 --> 00:28:14,360 She immediately realises that the other cup must be hiding the grape. 463 00:28:14,360 --> 00:28:16,920 She knew there was definitely a grape under this one, 464 00:28:16,920 --> 00:28:19,280 so a choice between that and the half-grape, 465 00:28:19,280 --> 00:28:22,560 she's sticking with the cup because she knows there's a grape under it. 466 00:28:23,560 --> 00:28:26,040 The chimps also play video games... 467 00:28:27,280 --> 00:28:31,040 ..which simulate complicated foraging tasks... 468 00:28:33,040 --> 00:28:37,040 ..looking for hidden fruit scattered around a complex landscape. 469 00:28:41,040 --> 00:28:43,760 The game is helping investigate the theory 470 00:28:43,760 --> 00:28:48,840 that as the rainforests retreated, the need to find scarcer food 471 00:28:48,840 --> 00:28:53,360 required greater brain power, memory and planning ahead. 472 00:28:58,040 --> 00:29:01,040 These games are posing a vital question - 473 00:29:01,040 --> 00:29:05,680 are the chimps able to keep track of their own awareness of the world? 474 00:29:06,760 --> 00:29:10,040 What they know and what they don't know. 475 00:29:12,280 --> 00:29:16,040 The ability to keep track of what you know and don't know 476 00:29:16,040 --> 00:29:20,040 is a vital and mysterious part of human intelligence 477 00:29:20,040 --> 00:29:22,520 known as metacognition. 478 00:29:22,520 --> 00:29:25,280 It's something which particularly interests 479 00:29:25,280 --> 00:29:28,520 the head of the research unit, Professor Josep Call. 480 00:29:28,520 --> 00:29:30,880 Metacognition is the ability 481 00:29:30,880 --> 00:29:35,280 to monitor and control your own thought processes, 482 00:29:35,280 --> 00:29:37,520 your own mental content. 483 00:29:37,520 --> 00:29:40,040 There is a thing called - in metacognition - 484 00:29:40,040 --> 00:29:43,080 that is called the tip-of-the-tongue phenomenon. 485 00:29:43,080 --> 00:29:45,360 When somebody asks you a question, and you say, 486 00:29:45,360 --> 00:29:48,920 "I cannot give you the answer, but I know that I know this answer"... 487 00:29:48,920 --> 00:29:51,600 It happens all the time. Yes, there you go. 488 00:29:51,600 --> 00:29:54,680 This is metacognition, where even though you cannot 489 00:29:54,680 --> 00:29:58,760 produce the answer, you know that you know the answer. 490 00:29:59,760 --> 00:30:03,520 One theory states that our ancestors developed metacognition 491 00:30:03,520 --> 00:30:06,920 as they solved problems posed by the environment, 492 00:30:06,920 --> 00:30:10,200 such as finding fruit in changing landscapes. 493 00:30:10,200 --> 00:30:15,520 It's thought this led to what's known as the Theory of Mind - 494 00:30:15,520 --> 00:30:20,760 the awareness not just of your own mind, but others' minds, too. 495 00:30:23,280 --> 00:30:26,040 It's about knowing about your own processes 496 00:30:26,040 --> 00:30:29,200 but also inputting processes to others. 497 00:30:29,200 --> 00:30:33,040 What others can see, what others want, 498 00:30:33,040 --> 00:30:36,000 what others intend, what others believe. 499 00:30:39,760 --> 00:30:43,520 Thinking about others is a crucial step towards becoming 500 00:30:43,520 --> 00:30:48,040 the socially-connected creatures which human beings are today. 501 00:30:51,520 --> 00:30:55,280 Our ancestors split from the lineage of chimpanzees 502 00:30:55,280 --> 00:30:58,440 around six to eight million years ago. 503 00:30:58,440 --> 00:31:02,280 After that came a huge change in lifestyle - 504 00:31:02,280 --> 00:31:05,680 a change with astonishing consequences. 505 00:31:05,680 --> 00:31:10,040 No-one knows exactly how, why or when it happened, 506 00:31:10,040 --> 00:31:12,680 but at some point during the millions of years 507 00:31:12,680 --> 00:31:17,040 after our own lineage split from that of chimpanzees and bonobos, 508 00:31:17,040 --> 00:31:19,760 our ancestors left the forests 509 00:31:19,760 --> 00:31:23,040 to make a new life out on the open plains. 510 00:31:23,040 --> 00:31:26,520 They become bipedal, walking up on two legs, 511 00:31:26,520 --> 00:31:31,320 so better able to adapt to different terrains and environments. 512 00:31:31,320 --> 00:31:33,120 Between two and three million 513 00:31:33,120 --> 00:31:34,440 years ago, 514 00:31:34,440 --> 00:31:36,760 homo habilis was evolving - 515 00:31:36,760 --> 00:31:38,920 the first human species. 516 00:31:40,720 --> 00:31:44,920 They were developing areas of the neocortex involved in planning, 517 00:31:44,920 --> 00:31:47,040 thinking, problem-solving, 518 00:31:47,040 --> 00:31:52,880 and we start to see some astonishing results of improved brainpower. 519 00:31:54,760 --> 00:31:58,280 Dr Nada Khreisheh is an experimental archaeologist. 520 00:31:58,280 --> 00:32:02,520 She works at the Ancient Technology Centre in Dorset. 521 00:32:08,760 --> 00:32:12,040 I'm meeting up again with Gillian Forrester. 522 00:32:12,040 --> 00:32:17,160 She and Nada have both investigated the fascinating links between tools 523 00:32:17,160 --> 00:32:19,680 and the story of our brain. 524 00:32:19,680 --> 00:32:22,760 So, Jim, I'm really excited to introduce you to Nada. 525 00:32:22,760 --> 00:32:25,400 She works in this beautiful place, 526 00:32:25,400 --> 00:32:29,920 and she actually teaches people how to make these ancient toolsets. Wow. 527 00:32:29,920 --> 00:32:31,200 OK, teach me. 528 00:32:31,200 --> 00:32:34,120 So, we'll just start with a brief history 529 00:32:34,120 --> 00:32:36,600 of some of the ancient types of stone tool 530 00:32:36,600 --> 00:32:39,040 that were made by our hominid ancestors. 531 00:32:39,040 --> 00:32:41,920 This is a core, a thin core, where sharp pieces, 532 00:32:41,920 --> 00:32:44,920 as you can see down on the floor here, have been knocked off, 533 00:32:44,920 --> 00:32:47,760 and these sharp pieces were used as tools for cutting. 534 00:32:47,760 --> 00:32:51,040 I want to know how much brainpower it takes 535 00:32:51,040 --> 00:32:54,840 to create the kind of tools which our ancestors made, 536 00:32:54,840 --> 00:33:00,760 so Nada sets me a task to make this half-finished hand axe thinner. 537 00:33:03,400 --> 00:33:06,320 So, yeah, you can see that that's... NADA LAUGHS 538 00:33:06,320 --> 00:33:07,920 ..not coming off. 539 00:33:07,920 --> 00:33:11,520 It's not brute force. It's not just brute force, unfortunately. 540 00:33:11,520 --> 00:33:13,960 Ooh. You're breaking the hammer stone. 541 00:33:14,960 --> 00:33:18,840 So he's actually broken the hammer stone and not the actual flint. 542 00:33:18,840 --> 00:33:21,040 Which is quite an achievement, really. 543 00:33:21,040 --> 00:33:22,480 LAUGHTER 544 00:33:22,480 --> 00:33:25,120 So, as you can see, just hitting it as hard as you can 545 00:33:25,120 --> 00:33:28,200 directly on the spot which you want to remove... Isn't working. 546 00:33:28,200 --> 00:33:30,800 ..isn't the right approach, really. NADA CHUCKLES 547 00:33:32,520 --> 00:33:36,040 Making the flint break in the direction you want it to 548 00:33:36,040 --> 00:33:39,040 turns out to be extremely complicated. 549 00:33:39,040 --> 00:33:42,920 It might seem counterintuitive, but you actually have to hit it 550 00:33:42,920 --> 00:33:46,560 from this side to be able to thin it effectively. Ah. 551 00:33:46,560 --> 00:33:50,120 And before we do that even, we need to prepare a place for us to hit, 552 00:33:50,120 --> 00:33:52,760 to take a piece, which should travel down there 553 00:33:52,760 --> 00:33:55,280 and thin the flint, if I do it right. 554 00:33:55,280 --> 00:33:57,960 I just need to do a few more preparatory flakes. 555 00:33:57,960 --> 00:34:03,040 Only after a few minutes of careful preparation can she do this. 556 00:34:03,040 --> 00:34:06,760 I'm going to hit on the top, and that's taken a piece... Ooh. 557 00:34:06,760 --> 00:34:10,280 ..which hasn't travelled as far as I want, but it's kind of isolated 558 00:34:10,280 --> 00:34:13,000 this spot a bit more, so made it stick out a bit more. Mmm. 559 00:34:15,159 --> 00:34:18,199 A lot of times, when people think of stone tools, they're thinking 560 00:34:18,199 --> 00:34:21,120 of cavemen, they're thinking of mighty muscles - big, hard hit - 561 00:34:21,120 --> 00:34:23,520 but it's also about planning and thinking ahead. 562 00:34:23,520 --> 00:34:26,760 Gillian believes this supports the theory that our ancestors 563 00:34:26,760 --> 00:34:28,760 were using cognitive abilities 564 00:34:28,760 --> 00:34:32,360 which had developed millions of years beforehand. 565 00:34:32,360 --> 00:34:35,760 As we've seen, our shared primate ancestors 566 00:34:35,760 --> 00:34:38,520 had likely already developed an ability 567 00:34:38,520 --> 00:34:41,120 to master syntactical problems. 568 00:34:41,120 --> 00:34:44,760 We've looked at nettle processing... Yeah. ..with the gorillas, 569 00:34:44,760 --> 00:34:47,760 we've looked at puzzle-solving with orangutans, 570 00:34:47,760 --> 00:34:50,840 and now we're looking here at stone toolmaking. 571 00:34:50,840 --> 00:34:54,040 They might seem like very, very different kinds of behaviours 572 00:34:54,040 --> 00:34:57,800 on the surface, but they have a commonality. 573 00:34:57,800 --> 00:35:01,520 And that common point is that they require us 574 00:35:01,520 --> 00:35:05,920 to put actions in the right order, and that's not different from 575 00:35:05,920 --> 00:35:10,880 how we put words in the right order to make meaning out of a sentence. 576 00:35:14,280 --> 00:35:17,440 Gillian believes that during our evolution, 577 00:35:17,440 --> 00:35:21,040 carrying out problem-solving actions with our hands 578 00:35:21,040 --> 00:35:24,720 led to our ability to produce spoken language. 579 00:35:28,280 --> 00:35:31,520 She has intriguing evidence from brain scans, 580 00:35:31,520 --> 00:35:35,680 which she explains to me using the 3D model of my own brain. 581 00:35:36,680 --> 00:35:38,880 This is your brain, as you well know. 582 00:35:38,880 --> 00:35:41,760 We've got the back of it here and the front of it here, 583 00:35:41,760 --> 00:35:46,280 and running right down the middle, here, is your motor cortex. 584 00:35:46,280 --> 00:35:49,120 This is telling your body to move, effectively. 585 00:35:49,120 --> 00:35:51,040 The hand area and the mouth area, 586 00:35:51,040 --> 00:35:53,320 they're really quite close to one another, 587 00:35:53,320 --> 00:35:55,680 and just in front of that area here 588 00:35:55,680 --> 00:36:00,040 is a region that we call Broca's area, or Broca's region. 589 00:36:00,040 --> 00:36:04,920 It's always been thought to be a language-specific region. 590 00:36:04,920 --> 00:36:08,040 It is activated when we speak. 591 00:36:08,040 --> 00:36:12,040 But, interestingly, it is also activated 592 00:36:12,040 --> 00:36:15,440 when a deaf signer signs their language. 593 00:36:15,440 --> 00:36:19,640 It doesn't seem to matter if you're vocalising or gesturing. 594 00:36:19,640 --> 00:36:21,680 It likes syntax. 595 00:36:22,680 --> 00:36:25,760 Broca's region is also activated when we carry out 596 00:36:25,760 --> 00:36:29,520 any sequential syntactic tasks with our hands. 597 00:36:32,760 --> 00:36:36,520 As part of an investigation into the evolution of our brains, 598 00:36:36,520 --> 00:36:40,040 Nada co-authored a huge study of volunteers, 599 00:36:40,040 --> 00:36:44,520 who did 100 hours of training in stone knapping. 600 00:36:44,520 --> 00:36:47,000 So one before they'd done any flint knapping 601 00:36:47,000 --> 00:36:50,360 and one after almost 100 hours of flint knapping, 602 00:36:50,360 --> 00:36:54,040 and we could see activations in Broca's area and changes - 603 00:36:54,040 --> 00:36:56,160 so, development in that area as well. 604 00:36:56,160 --> 00:36:57,840 It's fascinating, isn't it? 605 00:36:57,840 --> 00:37:02,760 This connection between language, vocalisation and hand movements, 606 00:37:02,760 --> 00:37:05,800 I'm doing it now as I talk, there is a connection, 607 00:37:05,800 --> 00:37:09,760 and it's the same part of the brain that's controlling different actions 608 00:37:09,760 --> 00:37:14,040 that I do with my hands and the words that come out of my mouth. 609 00:37:14,040 --> 00:37:18,560 A lot of people's mouths will mimic what their fingers are doing. 610 00:37:18,560 --> 00:37:22,360 For example, if you were sewing and you had to thread a needle... 611 00:37:22,360 --> 00:37:24,560 Exactly. 612 00:37:22,360 --> 00:37:24,560 LAUGHTER 613 00:37:24,560 --> 00:37:27,920 You're going to purse your lips when you've got a tight space 614 00:37:27,920 --> 00:37:31,040 and you're going to maybe open your lips more 615 00:37:31,040 --> 00:37:33,920 when you're grabbing larger objects. 616 00:37:33,920 --> 00:37:38,440 This could possibly date all the way back to just feeding behaviour. 617 00:37:38,440 --> 00:37:41,320 If you're going to pick up something small and put it in. 618 00:37:41,320 --> 00:37:44,760 If you're picking up something big, you need to open your mouth wider. 619 00:37:44,760 --> 00:37:49,040 We also have this evolutionary theory that we might have been first 620 00:37:49,040 --> 00:37:53,920 speaking with our hands, before language moved to our mouths. 621 00:37:53,920 --> 00:37:56,520 Only a small portion of the way we communicate 622 00:37:56,520 --> 00:37:58,920 is actually through our vocalisations. 623 00:37:58,920 --> 00:38:02,040 We're still communicating a huge amount about what we think 624 00:38:02,040 --> 00:38:05,280 and feel and intend through our facial expressions, 625 00:38:05,280 --> 00:38:08,280 our body postures and the way we move. 626 00:38:09,280 --> 00:38:13,680 So the theory is that carrying out complex tasks like toolmaking 627 00:38:13,680 --> 00:38:17,040 helped put in place the final bit of the brain 628 00:38:17,040 --> 00:38:19,520 which would be needed for language. 629 00:38:23,040 --> 00:38:25,520 Over the past two million years, 630 00:38:25,520 --> 00:38:28,680 our ancestors' brains tripled in size. 631 00:38:30,520 --> 00:38:33,520 Particularly in the advanced cognitive areas, 632 00:38:33,520 --> 00:38:35,680 such as the prefrontal cortex. 633 00:38:37,280 --> 00:38:39,760 So, why did this happen? 634 00:38:39,760 --> 00:38:43,160 One compelling theory lies in the large groups 635 00:38:43,160 --> 00:38:46,040 which hunter-gatherer societies formed 636 00:38:46,040 --> 00:38:48,760 and which we've inherited today. 637 00:38:48,760 --> 00:38:51,920 It's known as the Social Brain Theory, 638 00:38:51,920 --> 00:38:55,800 and it's something I'm about to explore in a very personal way. 639 00:38:55,800 --> 00:38:57,880 I've been working on these documentaries now 640 00:38:57,880 --> 00:38:59,280 for nearly 20 years. 641 00:38:59,280 --> 00:39:01,000 I've worked with all sorts of people. 642 00:39:01,000 --> 00:39:03,960 This is the first time I'm working with someone I know very well - 643 00:39:03,960 --> 00:39:07,320 my wife Julie. We've been together for over 40 years. 644 00:39:07,320 --> 00:39:11,680 I was asked to bring along either a good friend or my wife, 645 00:39:11,680 --> 00:39:14,280 and I don't have any good friends. JIM LAUGHS 646 00:39:14,280 --> 00:39:18,640 Yeah, not really. You weren't completely happy to come along. 647 00:39:18,640 --> 00:39:21,320 It's not my kind of thing. You're not a show-off like me. 648 00:39:21,320 --> 00:39:24,600 No, I'm not a show-off like you. Not many people are a show-off like you. 649 00:39:24,600 --> 00:39:27,840 Anyway, I hope you know what you're letting yourself in for this time. 650 00:39:27,840 --> 00:39:29,760 Not really, but I might finally get to find out 651 00:39:29,760 --> 00:39:31,000 what you do on these shoots. 652 00:39:31,000 --> 00:39:33,520 Let's stay friendly and see what happens. OK. 653 00:39:36,040 --> 00:39:39,560 Julie and I have been offered an unusual opportunity. 654 00:39:39,560 --> 00:39:43,760 We've been invited to drop in on a major five-year exploration 655 00:39:43,760 --> 00:39:47,520 of a unique aspect of the evolution of the human brain. 656 00:39:48,520 --> 00:39:51,280 Researchers from Nottingham Trent University 657 00:39:51,280 --> 00:39:53,760 have taken over an entire house. 658 00:39:57,600 --> 00:39:59,920 Cameras have been placed everywhere. 659 00:40:01,320 --> 00:40:06,280 And, while we're here, every move will be filmed from different angles 660 00:40:06,280 --> 00:40:09,280 and the footage will be analysed by researchers 661 00:40:09,280 --> 00:40:11,480 hidden away in a different room. 662 00:40:11,480 --> 00:40:13,520 Are you ready to play a game together? Yeah. 663 00:40:13,520 --> 00:40:17,520 For months now, psychological and behavioural tests 664 00:40:17,520 --> 00:40:22,920 have been carried out here, with 120 pairs of best friends or couples. 665 00:40:22,920 --> 00:40:26,080 The game that you're going to play is called Lost on the Moon. 666 00:40:26,080 --> 00:40:28,680 Lost on the Moon is a puzzle game. 667 00:40:28,680 --> 00:40:30,840 Do we need this? Well... 668 00:40:30,840 --> 00:40:34,280 We've been asked to put these items in order of importance 669 00:40:34,280 --> 00:40:36,120 to help us survive on the Moon. 670 00:40:36,120 --> 00:40:38,160 Why would we need a box of matches? 671 00:40:38,160 --> 00:40:40,600 There's no atmosphere on the Moon, so you can't... 672 00:40:40,600 --> 00:40:42,280 You can't... Light a fire. 673 00:40:42,280 --> 00:40:43,840 I'm going to be hungry. 674 00:40:43,840 --> 00:40:46,520 I'm saying I'm going to feel peckish and thirsty. 675 00:40:46,520 --> 00:40:48,640 Yeah, but it's not just about you, Jim. 676 00:40:48,640 --> 00:40:51,120 Well, you'll probably want a snack. 677 00:40:51,120 --> 00:40:54,200 Yeah... What have you got? I've got the pistols. Pistols! 678 00:40:54,200 --> 00:40:57,440 What are we going to shoot? You. LAUGHTER 679 00:40:57,440 --> 00:41:00,360 Apparently we're going to need the pistol because if we run out 680 00:41:00,360 --> 00:41:03,680 of food, Julie's going to get hungry and she's going to want to shoot me. 681 00:41:03,680 --> 00:41:06,520 I'm not going to want to shoot you because I might get hungry. 682 00:41:06,520 --> 00:41:09,320 Just because I'm getting on your nerves. Yeah. Fine. 683 00:41:09,320 --> 00:41:12,040 As far as we're concerned, this is all about, you know, 684 00:41:12,040 --> 00:41:15,480 whether we can survive on the Moon until we're rescued, 685 00:41:15,480 --> 00:41:18,920 but it's clearly about, actually, whether we're cooperating. 686 00:41:18,920 --> 00:41:22,280 We're quite good at that. It might not seem like it all the time, 687 00:41:22,280 --> 00:41:25,640 but we actually do manage to compromise and cooperate. 688 00:41:25,640 --> 00:41:28,040 What do you mean, doesn't seem like that? 689 00:41:28,040 --> 00:41:30,080 JULIE LAUGHS 690 00:41:28,040 --> 00:41:30,080 Sorry, dear. 691 00:41:30,080 --> 00:41:32,320 While all this is happening, 692 00:41:32,320 --> 00:41:35,040 our facial expressions are being recorded 693 00:41:35,040 --> 00:41:37,840 and a team of evolutionary psychologists 694 00:41:37,840 --> 00:41:40,040 are analysing our results. 695 00:41:40,040 --> 00:41:42,960 Then they call us for a meeting. 696 00:41:42,960 --> 00:41:46,520 So we've been videoing you while you've been doing all these tasks 697 00:41:46,520 --> 00:41:49,520 and we've been measuring your facial movement. 698 00:41:49,520 --> 00:41:52,920 Whether you furrow your brow, whether you raise your brow, 699 00:41:52,920 --> 00:41:55,680 whether you smile, whether you wrinkle your nose. 700 00:41:55,680 --> 00:41:57,280 Funny look, isn't it? 701 00:41:57,280 --> 00:41:59,440 Eyebrow raises. Eyebrow raises. 702 00:41:59,440 --> 00:42:02,480 So this gives a huge amount of very detailed information, 703 00:42:02,480 --> 00:42:04,840 behavioural information, that's happening 704 00:42:04,840 --> 00:42:06,520 during a normal conversation. 705 00:42:06,520 --> 00:42:12,080 Jim has a rate of approximately 127 muscle movements per minute. 706 00:42:12,080 --> 00:42:13,840 Woohoo! Is that good? 707 00:42:13,840 --> 00:42:16,120 That's very high. Quite high, yeah. 708 00:42:16,120 --> 00:42:17,920 The average is about 100. 709 00:42:17,920 --> 00:42:21,720 Julie had slightly less facial movements than me, 710 00:42:21,720 --> 00:42:25,280 but it might be because she tends to play her cards close to her chest. 711 00:42:25,280 --> 00:42:27,960 I might just be one of those really deadpan people. 712 00:42:27,960 --> 00:42:30,880 LAUGHTER 713 00:42:27,960 --> 00:42:30,880 The poker face. 714 00:42:30,880 --> 00:42:35,920 This project is investigating how much we use our facial expressions 715 00:42:35,920 --> 00:42:40,120 to bond with others, especially our nearest and dearest, 716 00:42:40,120 --> 00:42:43,520 and comparing it with other primates. 717 00:42:43,520 --> 00:42:46,000 Many primates have facial expressions that are 718 00:42:46,000 --> 00:42:48,920 similar to ours, but our faces are the most expressive, 719 00:42:48,920 --> 00:42:53,040 and we think this sort of complexity is probably really important 720 00:42:53,040 --> 00:42:54,800 to humans as a species 721 00:42:54,800 --> 00:42:59,040 and how we manage these really... Mmm. ..complex, intense 722 00:42:59,040 --> 00:43:01,520 social interactions we have with other people. 723 00:43:01,520 --> 00:43:03,960 That's helped the evolution of our brains, 724 00:43:03,960 --> 00:43:07,040 the fact that we are able to communicate with facial expressions? 725 00:43:07,040 --> 00:43:09,920 That's the basic idea behind the Social Brain Theory - 726 00:43:09,920 --> 00:43:13,040 that what is difficult is the social stuff. 727 00:43:13,040 --> 00:43:16,640 So, forming relationships, understanding the signals of others, 728 00:43:16,640 --> 00:43:20,040 understanding relationships between other individuals, 729 00:43:20,040 --> 00:43:22,040 maintaining your own relationships, 730 00:43:22,040 --> 00:43:26,040 that's the stuff that's difficult to do and that requires big brains. 731 00:43:27,040 --> 00:43:31,520 Proponents of the Social Brain Theory believe there's a direct link 732 00:43:31,520 --> 00:43:34,400 between the relative intelligence of primates 733 00:43:34,400 --> 00:43:37,760 and the social groups they can sustain. 734 00:43:37,760 --> 00:43:41,120 As our ancestors spread out across the lands, 735 00:43:41,120 --> 00:43:43,520 they formed bigger social groups. 736 00:43:44,760 --> 00:43:47,520 This helped keep them safe from predators, 737 00:43:47,520 --> 00:43:50,120 but took more brain power. 738 00:43:50,120 --> 00:43:54,240 Living in groups has costs, but it also has lots of advantages 739 00:43:54,240 --> 00:43:57,480 in terms of access to mates, you can monopolise resources, 740 00:43:57,480 --> 00:44:00,040 and primates are very good at living in groups. 741 00:44:00,040 --> 00:44:03,280 I think it's important to think about humans and what we're good at, 742 00:44:03,280 --> 00:44:06,120 and what we're good at is intense social interaction. 743 00:44:07,120 --> 00:44:10,520 For this programme, we decided to conduct a little test 744 00:44:10,520 --> 00:44:12,520 on the Social Brain Theory. 745 00:44:13,760 --> 00:44:15,760 And what could be more appropriate 746 00:44:15,760 --> 00:44:19,040 than a good old traditional British pub quiz? 747 00:44:20,360 --> 00:44:23,520 I've invited Professor Robin Dunbar to take part. 748 00:44:23,520 --> 00:44:26,600 What are we having? A whisky, Jim, I think. Whisky? 749 00:44:26,600 --> 00:44:28,800 It's a long evening. 750 00:44:26,600 --> 00:44:28,800 JIM LAUGHS 751 00:44:28,800 --> 00:44:31,680 He's the person who came up with the Social Brain Theory 752 00:44:31,680 --> 00:44:33,920 after years studying primates. 753 00:44:36,840 --> 00:44:39,040 I start with some easy questions. 754 00:44:39,040 --> 00:44:42,440 The greatest science communicator of all time 755 00:44:42,440 --> 00:44:45,520 is widely acknowledged to be, A, Carl Sagan, 756 00:44:45,520 --> 00:44:49,480 B, Neil deGrasse Tyson, C, Brian Cox, 757 00:44:49,480 --> 00:44:52,040 or, D, Jim Al-Khalili? 758 00:44:49,480 --> 00:44:52,040 LAUGHTER 759 00:44:53,040 --> 00:44:56,320 I set the questions, by the way. LAUGHTER 760 00:44:56,320 --> 00:44:59,520 According to the Social Brain Theory, 761 00:44:59,520 --> 00:45:02,760 what is the number of meaningful friendships 762 00:45:02,760 --> 00:45:07,200 which the average human being is capable of maintaining? 763 00:45:12,040 --> 00:45:14,520 It's 150. 764 00:45:15,520 --> 00:45:20,120 In fact, that's a very famous number - the Dunbar Number. 765 00:45:22,040 --> 00:45:24,360 CHEERING AND APPLAUSE 766 00:45:25,360 --> 00:45:28,760 The Dunbar Number sets limits to the number of friends 767 00:45:28,760 --> 00:45:33,920 and family we're cognitively capable of having proper relationships with. 768 00:45:33,920 --> 00:45:35,880 The Dunbar Number you have 769 00:45:35,880 --> 00:45:39,800 reflects the cognitive demands of managing relationships. 770 00:45:41,400 --> 00:45:45,040 In fact, it's a concentric circle of numbers, 771 00:45:45,040 --> 00:45:48,520 starting with your closest circle of five people - 772 00:45:48,520 --> 00:45:52,960 the people you think about most, and feel most empathy for. 773 00:45:52,960 --> 00:45:55,320 The single best predictor... 774 00:45:55,320 --> 00:45:59,520 ..of your mental health and wellbeing, 775 00:45:59,520 --> 00:46:01,440 your physical health and wellbeing, 776 00:46:01,440 --> 00:46:04,880 even how long you're going to live into the future from today, 777 00:46:04,880 --> 00:46:08,440 it's simply the number and quality of close friendships. 778 00:46:08,440 --> 00:46:11,520 An average of 50 people are good friends 779 00:46:11,520 --> 00:46:16,040 and 150 is the average limit for meaningful friendships. 780 00:46:16,040 --> 00:46:19,120 Beyond the 150, there's a layer that goes out to about 500, 781 00:46:19,120 --> 00:46:20,600 of acquaintances. 782 00:46:20,600 --> 00:46:23,040 You may spend quite a lot of time chatting to them 783 00:46:23,040 --> 00:46:25,520 but you're probably not going to invite them home. 784 00:46:25,520 --> 00:46:27,840 Robin says many studies show this. 785 00:46:27,840 --> 00:46:32,040 From the average size of a medieval village - 150 - 786 00:46:32,040 --> 00:46:34,960 to a huge study about the number of people 787 00:46:34,960 --> 00:46:37,760 we communicate with properly on social media. 788 00:46:39,040 --> 00:46:41,880 The average is 149. 789 00:46:42,880 --> 00:46:46,040 I'm going to set our audience a cognitive test, 790 00:46:46,040 --> 00:46:50,280 which Robin believes helps prove the Social Brain Theory. 791 00:46:50,280 --> 00:46:52,760 See if you can solve it yourself. 792 00:46:52,760 --> 00:46:58,520 Each card has a number on one side and a colour on the other. 793 00:46:58,520 --> 00:47:02,760 If a card has an even number on one side, 794 00:47:02,760 --> 00:47:06,280 then on the other side it has to be blue. 795 00:47:07,280 --> 00:47:12,440 Which card, or cards, do you have to turn over 796 00:47:12,440 --> 00:47:16,720 to find out if that statement is true or not? 797 00:47:17,720 --> 00:47:21,440 Now, if you find this difficult, don't worry at all. 798 00:47:21,440 --> 00:47:24,640 Up to 90% of people can't work it out. 799 00:47:25,640 --> 00:47:27,280 I got it wrong. 800 00:47:27,280 --> 00:47:28,720 THEY LAUGH 801 00:47:28,720 --> 00:47:32,720 It's because it's deliberately phrased in a complicated 802 00:47:32,720 --> 00:47:34,720 and abstract way. 803 00:47:34,720 --> 00:47:36,440 Here's the answer. 804 00:47:36,440 --> 00:47:38,680 To find out if that statement is true, 805 00:47:38,680 --> 00:47:41,520 you'd have to turn over two cards. 806 00:47:41,520 --> 00:47:44,760 They are the number eight card 807 00:47:44,760 --> 00:47:46,760 and the red card. 808 00:47:46,760 --> 00:47:50,760 How many people got that right? Can I have a show of hands? 809 00:47:50,760 --> 00:47:53,840 Our audience tonight did pretty well, 810 00:47:53,840 --> 00:47:56,480 but the majority didn't get it. 811 00:47:57,480 --> 00:47:59,840 Now a second test. 812 00:47:59,840 --> 00:48:04,720 Jane's going to put up on one side the age of the person, 813 00:48:04,720 --> 00:48:07,360 and on the other side what they're drinking. 814 00:48:08,360 --> 00:48:10,040 Beer... 815 00:48:10,040 --> 00:48:11,800 ..and lemonade. 816 00:48:13,800 --> 00:48:18,040 Which card, or cards, do you have to turn over 817 00:48:18,040 --> 00:48:22,720 to see if there are any underage drinkers in your pub? 818 00:48:22,720 --> 00:48:26,280 This one just feels so much easier. 819 00:48:26,280 --> 00:48:29,680 To check if anyone is an underage drinker, 820 00:48:29,680 --> 00:48:32,280 you just need to check the 16-year-old 821 00:48:32,280 --> 00:48:34,280 to see what they're drinking 822 00:48:34,280 --> 00:48:37,760 and the beer drinker to see how old they are. 823 00:48:37,760 --> 00:48:40,040 How many people got that right? 824 00:48:40,040 --> 00:48:42,040 Oh, there you go! 825 00:48:42,040 --> 00:48:44,680 Just about everyone. 826 00:48:44,680 --> 00:48:49,040 How many people found the first test easier than the second test? 827 00:48:53,040 --> 00:48:54,520 No-one. 828 00:48:54,520 --> 00:48:56,840 And that's the real point, 829 00:48:56,840 --> 00:49:02,760 because, amazingly, these two tests are actually the same test of logic. 830 00:49:02,760 --> 00:49:05,680 The beer is equivalent to the red 831 00:49:05,680 --> 00:49:08,520 and the underage card, the 16, 832 00:49:08,520 --> 00:49:11,720 is equivalent to the even card, the number eight. 833 00:49:11,720 --> 00:49:17,120 But we humans nearly always find one much harder than the other. 834 00:49:17,120 --> 00:49:21,040 Somehow, phrasing it in that way, in terms of social activities 835 00:49:21,040 --> 00:49:23,560 that we're familiar with in everyday life, 836 00:49:23,560 --> 00:49:27,280 makes that logic test seem so much easier, 837 00:49:27,280 --> 00:49:30,040 and yet it's exactly the same. 838 00:49:30,040 --> 00:49:34,040 The argument is that's because the brain is attuned 839 00:49:34,040 --> 00:49:38,520 to constantly checking for people who infringe on social rules. 840 00:49:40,280 --> 00:49:44,680 So we didn't evolve as abstract, logical calculators. 841 00:49:44,680 --> 00:49:49,040 We evolved to work out each other and to solve social problems 842 00:49:49,040 --> 00:49:53,760 and police social rules such as spotting underage drinkers. 843 00:49:57,520 --> 00:50:00,520 A rapidly-developing field of neuroscience 844 00:50:00,520 --> 00:50:04,760 is now making some intriguing breakthroughs, revealing where 845 00:50:04,760 --> 00:50:08,920 in our brains much of our social processing takes place. 846 00:50:11,280 --> 00:50:16,040 Professor Nancy Kanwisher runs a laboratory at MIT in Massachusetts. 847 00:50:16,040 --> 00:50:18,760 This is a slice through the middle of the brain, here. 848 00:50:18,760 --> 00:50:20,840 So, you see, this is the front of the head, 849 00:50:20,840 --> 00:50:22,840 that's the nose, that's the back. 850 00:50:22,840 --> 00:50:28,040 She made a name for herself when she tried to detect brain activity 851 00:50:28,040 --> 00:50:30,280 when we look at each other. 852 00:50:30,280 --> 00:50:33,800 Faces are one of the most important kinds of visual stimuli. 853 00:50:33,800 --> 00:50:36,720 They are the first stimulus that an infant wants to look at. 854 00:50:36,720 --> 00:50:39,680 And for social primates like us, it's absolutely critical 855 00:50:39,680 --> 00:50:42,760 to be able to perceive faces and all the rich information 856 00:50:42,760 --> 00:50:44,760 they tell us about another person. 857 00:50:44,760 --> 00:50:47,440 We popped people in the scanner - me, to start - 858 00:50:47,440 --> 00:50:50,720 and I looked at pictures of faces and pictures of objects. 859 00:50:50,720 --> 00:50:54,120 And so the first time we did this, I remember coming out of the scanner 860 00:50:54,120 --> 00:50:56,680 and finding this little blob in my brain, 861 00:50:56,680 --> 00:50:59,520 and you could just see in the time course of response 862 00:50:59,520 --> 00:51:03,040 in the experiment, a big peak during the times I was looking at faces, 863 00:51:03,040 --> 00:51:06,040 and these little teeny bumps when I was looking at objects. 864 00:51:06,040 --> 00:51:08,680 And I just thought, "That's amazing." 865 00:51:10,280 --> 00:51:14,520 What Nancy had found is called the fusiform face area - 866 00:51:14,520 --> 00:51:17,520 a highly specialised location in the brain. 867 00:51:18,520 --> 00:51:21,400 So the fusiform face area seems to be involved 868 00:51:21,400 --> 00:51:23,040 both in detecting a face - 869 00:51:23,040 --> 00:51:25,520 like, "That thing I'm looking at, that's a face" - 870 00:51:25,520 --> 00:51:27,600 and in figuring out which face that is - 871 00:51:27,600 --> 00:51:29,480 "Is that Joe or Bob or Mary or Jay?" 872 00:51:30,760 --> 00:51:36,520 This is the scan of my own brain and this is my fusiform face area, 873 00:51:36,520 --> 00:51:40,040 activated when I looked at videos of faces. 874 00:51:43,280 --> 00:51:45,760 Nancy and her colleagues have discovered 875 00:51:45,760 --> 00:51:48,760 other specialised social areas of the brain. 876 00:51:51,040 --> 00:51:53,520 This network has recently been discovered. 877 00:51:53,520 --> 00:51:57,040 It's called the dynamic social pathway. 878 00:51:57,040 --> 00:52:01,920 It helps us analyse and identify moving people and faces, 879 00:52:01,920 --> 00:52:05,600 expressions, other people's intentions and moods. 880 00:52:08,080 --> 00:52:12,280 This area is activated when we look at people's bodies. 881 00:52:12,280 --> 00:52:17,040 We even have a spot of our brain called the theory of mind area, 882 00:52:17,040 --> 00:52:21,040 activated when we think about what other people are thinking. 883 00:52:22,040 --> 00:52:24,360 You can think of all of this apparatus 884 00:52:24,360 --> 00:52:26,520 as part of our social mind. 885 00:52:26,520 --> 00:52:28,760 This is how we function in society. 886 00:52:28,760 --> 00:52:32,360 It's a very temping hypothesis to say, "Look, it makes total sense 887 00:52:32,360 --> 00:52:35,040 "for evolution to have built this structure in us." 888 00:52:35,040 --> 00:52:37,760 We are social primates, we care about each other, 889 00:52:37,760 --> 00:52:41,000 we need to detect and recognise each other to survive, 890 00:52:41,000 --> 00:52:44,040 and so it would make sense for evolution to have crafted 891 00:52:44,040 --> 00:52:46,440 a specialised face-processing machine 892 00:52:46,440 --> 00:52:48,240 and built it into a brain. 893 00:52:48,240 --> 00:52:50,120 But we have to be careful. 894 00:52:51,120 --> 00:52:54,440 This is still a fast-developing field of science. 895 00:52:54,440 --> 00:52:58,120 These social networks could have developed in our infancy 896 00:52:58,120 --> 00:53:00,360 as we became exposed to faces. 897 00:53:00,360 --> 00:53:04,680 Or they may be part of our evolutionary inheritance. 898 00:53:05,680 --> 00:53:09,520 What's known for sure is that our ability to bond together 899 00:53:09,520 --> 00:53:12,360 as social creatures starts very early. 900 00:53:12,360 --> 00:53:14,680 I'm convinced he's already saying, "Mama". 901 00:53:16,280 --> 00:53:20,200 Dr Georgina Donati collaborates with Gillian Forrester 902 00:53:20,200 --> 00:53:23,680 in studying brain evolution and development. 903 00:53:23,680 --> 00:53:27,520 Recently, she's brought into the world her own test subject - 904 00:53:27,520 --> 00:53:30,040 four month-old Elio. 905 00:53:30,040 --> 00:53:33,240 Raspberry is a new skill, isn't it? 906 00:53:34,240 --> 00:53:35,560 Ah. 907 00:53:35,560 --> 00:53:39,560 Elio's social brain is already starting to kick in. 908 00:53:40,560 --> 00:53:43,520 He's become very vocal recently. He's talking a lot, 909 00:53:43,520 --> 00:53:46,560 although when other people are talking, he likes to listen. 910 00:53:46,560 --> 00:53:49,520 But, I mean, there are all of these incredible mechanisms 911 00:53:49,520 --> 00:53:51,200 that we've developed. 912 00:53:51,200 --> 00:53:54,600 You know, they come out screaming their heads off, which makes us all 913 00:53:54,600 --> 00:53:59,040 kind of run to them immediately, and then they develop smiles and giggles 914 00:53:59,040 --> 00:54:02,320 and these things which keep us there and keep us interacting with them. 915 00:54:02,320 --> 00:54:05,280 It creates this interaction, which the babies need to learn. 916 00:54:05,280 --> 00:54:07,840 And humans have evolved that? This is something that 917 00:54:07,840 --> 00:54:10,520 I think we're continuing to find out and explore. 918 00:54:10,520 --> 00:54:14,360 How does this compare, humans babies, with other primates, 919 00:54:14,360 --> 00:54:16,520 for example, or indeed other animals? 920 00:54:16,520 --> 00:54:19,280 One of the special characteristics of us humans 921 00:54:19,280 --> 00:54:23,680 is that we're born relatively early and underdeveloped 922 00:54:23,680 --> 00:54:25,920 in comparison to other great apes. 923 00:54:25,920 --> 00:54:29,600 Gorillas, when they're born, they can grip onto their mums better. 924 00:54:29,600 --> 00:54:33,040 They're not independent yet, but they're not quite as vulnerable 925 00:54:33,040 --> 00:54:34,760 as our human babies. 926 00:54:34,760 --> 00:54:39,440 We've got a longer developmental period and it's made us able 927 00:54:39,440 --> 00:54:43,120 to learn things more socially from a very young age. 928 00:54:43,120 --> 00:54:45,080 Who's this? 929 00:54:47,320 --> 00:54:48,840 JIM LAUGHS 930 00:54:48,840 --> 00:54:52,280 Who's that? Of all the toys that he's been introduced to, 931 00:54:52,280 --> 00:54:56,240 this gorilla is definitely the one that makes him happiest. 932 00:54:56,240 --> 00:54:58,280 CONTENTED MOANS 933 00:54:59,520 --> 00:55:03,760 A long childhood gives us what's known as high plasticity - 934 00:55:03,760 --> 00:55:08,360 our brains can adapt according to the different environments we're in. 935 00:55:11,040 --> 00:55:14,200 But it means our ancestors had to look after 936 00:55:14,200 --> 00:55:17,280 a helpless infant for years in the wild. 937 00:55:17,280 --> 00:55:19,360 It poses a huge question. 938 00:55:20,360 --> 00:55:22,280 How did we survive? 939 00:55:22,280 --> 00:55:25,120 Well... So, as you'll know, being a parent, 940 00:55:25,120 --> 00:55:27,920 it's a massive parental investment. 941 00:55:27,920 --> 00:55:30,840 With modern humans, we've often got two parents, 942 00:55:30,840 --> 00:55:35,320 and we also have extended families that help raise these babies, 943 00:55:35,320 --> 00:55:39,040 not just to be fed, but to be socially engaged 944 00:55:39,040 --> 00:55:43,280 and to keep giving the stimulus and the stimulation to the brain. 945 00:55:43,280 --> 00:55:46,040 Our brains carry on developing through adolescence 946 00:55:46,040 --> 00:55:48,280 and we think now that this is carrying on 947 00:55:48,280 --> 00:55:50,280 until we're sort of in our mid-20s. 948 00:55:50,280 --> 00:55:53,280 Potentially, providing these very nurturing environments 949 00:55:53,280 --> 00:55:56,280 really just allows this plasticity, this learning, 950 00:55:56,280 --> 00:55:59,600 this flexibility, to continue for longer and longer. 951 00:56:01,280 --> 00:56:06,040 So the lesson is, without loving, self-sacrificing parents 952 00:56:06,040 --> 00:56:08,360 and supportive social communities, 953 00:56:08,360 --> 00:56:11,520 we'd never have survived the rigours of the wild 954 00:56:11,520 --> 00:56:14,280 and evolved the brains we have today. 955 00:56:17,040 --> 00:56:20,760 The human brain has now started to build machines 956 00:56:20,760 --> 00:56:24,400 which can surpass it in so many ways. 957 00:56:24,400 --> 00:56:28,520 We humans have used our cognitive powers to astonishing effect, 958 00:56:28,520 --> 00:56:32,680 from those very early stone tools to devices like this. 959 00:56:32,680 --> 00:56:36,040 A smartphone is basically a pocket-sized super computer, 960 00:56:36,040 --> 00:56:39,280 capable of processing vast amounts of information, 961 00:56:39,280 --> 00:56:41,840 carrying out operations much more quickly 962 00:56:41,840 --> 00:56:43,760 than our brains could ever do. 963 00:56:43,760 --> 00:56:47,520 And today we're on the brink of a new technological revolution. 964 00:56:47,520 --> 00:56:52,280 Artificial intelligence is already performing complex mental tasks, 965 00:56:52,280 --> 00:56:55,480 from essay writing to composing music. 966 00:56:59,040 --> 00:57:02,920 The future of AI - our most extraordinary creation - 967 00:57:02,920 --> 00:57:06,280 is still unknown, but what I've learnt on my journey 968 00:57:06,280 --> 00:57:10,840 has given me hope that being in a community with others 969 00:57:10,840 --> 00:57:15,640 was the crucial final step in the evolution of our brains. 970 00:57:17,760 --> 00:57:20,680 What has fundamentally shaped our brains 971 00:57:20,680 --> 00:57:23,040 is our relationships with each other. 972 00:57:23,040 --> 00:57:26,040 It's the family and friendship groups we form, 973 00:57:26,040 --> 00:57:29,040 it's our shared histories, our shared cultures, 974 00:57:29,040 --> 00:57:31,520 our beliefs, our memories. 975 00:57:31,520 --> 00:57:36,040 Ultimately, it's our capacity for empathy, 976 00:57:36,040 --> 00:57:38,920 for love, for self-sacrifice, 977 00:57:38,920 --> 00:57:43,040 for thinking about each other, that has made us who we are. 978 00:57:45,160 --> 00:57:51,040 Curious about how MRI technology can reveal the secrets of your brain? 979 00:57:51,040 --> 00:57:54,040 To watch the Open University's new animation 980 00:57:54,040 --> 00:57:57,800 exploring how an MRI works and what it reveals, 981 00:57:57,800 --> 00:58:04,880 scan the QR code or go to bbc.co.uk/secretsofthebrain 982 00:58:04,880 --> 00:58:08,000 and follow the links to the Open University.