WEBVTT - Ep22 "What do we find beautiful?" 0:00:04.640 --> 0:00:09.320 Why do briefly glimpsed people appear to be more attractive? 0:00:10.000 --> 0:00:14.080 Why did portrait photographers used to put vaciline on their 0:00:14.160 --> 0:00:17.360 lenses and what does that have to do with Instagram filters? 0:00:17.920 --> 0:00:22.360 Why are thirsty people more likely to perceive something as transparent? 0:00:23.040 --> 0:00:24.680 And what does any of this have to do with 0:00:25.200 --> 0:00:29.800 mating or optimal decision making or puberty or frogs or 0:00:29.840 --> 0:00:37.200 instincts or movie stars. Welcome to another episode of Inner 0:00:37.280 --> 0:00:41.360 Cosmos with me David Eagleman. I'm a neuroscientist and an 0:00:41.400 --> 0:00:45.320 author at Stanford and in these episodes, we sail deeply 0:00:45.520 --> 0:00:49.680 into our three pound universe to understand the relationship between 0:00:50.040 --> 0:01:00.560 our brains and our lives. Throughout this podcast, we're gonna 0:01:00.640 --> 0:01:04.119 try to gain a better understanding of ourselves by practicing 0:01:04.120 --> 0:01:09.560 the technique of viewing the familiar as strange. We'll look 0:01:09.600 --> 0:01:14.440 at instincts, things that we do naturally, so naturally that 0:01:14.520 --> 0:01:18.280 we never even think to question them. But digging in 0:01:18.400 --> 0:01:21.600 on these things is how we come to develop a 0:01:21.640 --> 0:01:25.399 deeper understanding of ourselves. And today's episode is about the 0:01:25.600 --> 0:01:31.119 absolutely fascinating topic about how our brains determine for us 0:01:31.240 --> 0:01:35.880 what we find beautiful. So beauty is found all around us, 0:01:35.880 --> 0:01:39.399 in nature and in art and in music, and a 0:01:39.440 --> 0:01:42.399 good life is full of beautiful moments like a sunset 0:01:42.520 --> 0:01:46.800 or a compliment or a child's smile. But our interest 0:01:46.800 --> 0:01:51.680 today is in people, and specifically on the notion of attraction, 0:01:52.560 --> 0:01:55.720 So the notion of the movie star whose next movie 0:01:55.800 --> 0:01:58.480 you just can't wait to see, mostly because you find 0:01:58.520 --> 0:02:03.280 that person just so magnetically good looking, or the work 0:02:03.320 --> 0:02:05.560 made or the neighbor or the person you knew from 0:02:05.560 --> 0:02:10.040 your childhood who's just so amazingly attractive. So what is 0:02:10.120 --> 0:02:13.200 going on in the brain here, What are the signals 0:02:13.720 --> 0:02:16.799 that tell you that person is attractive? And what does 0:02:16.840 --> 0:02:19.960 all that have to do with the propagation of the species. 0:02:20.520 --> 0:02:25.480 So let's get started. There are hundreds of ways that 0:02:25.520 --> 0:02:28.480 a person can be attractive to you, based on their 0:02:28.960 --> 0:02:32.239 with or their brawn, or their kindness or their dedication 0:02:32.320 --> 0:02:34.920 to a cause or whatever. But what we're going to 0:02:35.000 --> 0:02:39.080 zoom in on today is about the first glimpse of someone, 0:02:39.120 --> 0:02:46.680 the rapid assessment that takes your breath away, and that 0:02:46.840 --> 0:02:51.000 magic moment is actually the end result of a great 0:02:51.080 --> 0:02:55.639 deal of computation that your brain is doing under the hood. Now, 0:02:55.639 --> 0:02:59.639 to start off, there's plenty of variation in what any 0:02:59.680 --> 0:03:03.600 given person finds beautiful, and there's some amount of variation 0:03:03.720 --> 0:03:07.600 across cultures too, in terms of how people dress and 0:03:07.639 --> 0:03:10.480 how they act, and their bone structure and their facial 0:03:10.520 --> 0:03:14.400 structure and all that. But what's interesting is that attractiveness 0:03:14.480 --> 0:03:17.639 is not all in the eye of the beholder, and 0:03:17.680 --> 0:03:22.400 beyond the personal and the cultural variations, some of the 0:03:22.400 --> 0:03:29.160 most salient elements of attractiveness are hardwired. When researchers study attractiveness, 0:03:29.200 --> 0:03:34.040 even cross culturally, they find a surprising concurrence in what 0:03:34.160 --> 0:03:39.360 gets rated highly. There are particular things that draw us, 0:03:40.000 --> 0:03:44.800 and mostly this has to do with largely unconscious signals 0:03:44.840 --> 0:03:48.120 of health and fertility. And in a sense, you already 0:03:48.160 --> 0:03:52.040 know this. Just look at the massive popularity of Instagram 0:03:52.080 --> 0:03:55.560 and TikTok filters, which are used around the world. These 0:03:55.640 --> 0:04:00.240 beautification filters aren't random. Instead, they move things in a 0:04:00.280 --> 0:04:04.520 particular direction such that the photos look better to us, 0:04:04.840 --> 0:04:07.560 and they work so much so that many young people 0:04:07.600 --> 0:04:11.640 are totally unwilling to post photos without these filters in place. 0:04:14.320 --> 0:04:17.359 So why what are these about? Let's look at this 0:04:17.400 --> 0:04:20.279 from the point of view of biology. When you open 0:04:20.360 --> 0:04:24.920 a biology textbook or watch a David Attenborough special, you 0:04:24.960 --> 0:04:30.960 see bower birds or lions, or frogs, or butterflies or fish, 0:04:31.200 --> 0:04:35.200 and you see these elaborate mating rituals. And of course, 0:04:35.600 --> 0:04:38.520 being members of the animal kingdom, we can't pretend that 0:04:38.640 --> 0:04:42.159 we don't have neural circuitry devoted to the same thing 0:04:42.279 --> 0:04:45.479 as well, because one of the most important drives for 0:04:45.560 --> 0:04:50.719 all creatures, including humans, is mate selection. How an animal 0:04:50.800 --> 0:04:53.760 chooses who to reproduce with. And we see this all 0:04:53.800 --> 0:04:57.960 across the animal kingdom, with feathers, with colors, with pheromones, 0:04:58.040 --> 0:05:01.720 with behavioral displays, all all creatures are trying to do 0:05:01.760 --> 0:05:05.560 things to make themselves more attractive to mate with. Now 0:05:05.560 --> 0:05:08.920 the question is how does this play out in humans. 0:05:09.640 --> 0:05:13.320 Needless to say, the reason you exist is because every 0:05:13.360 --> 0:05:17.760 single one of your ancestors successfully mate it. That's the 0:05:17.880 --> 0:05:21.560 single reason that you are here. Our species is so 0:05:21.600 --> 0:05:25.320 successful at reproduction that we've taken over the entire planet 0:05:25.880 --> 0:05:30.239 and the whole history of our species. Reproduction is driven 0:05:30.360 --> 0:05:34.599 by attraction, judgments and issues of mate choice. Now, the 0:05:34.800 --> 0:05:37.320 very first thing that blows my mind is how these 0:05:37.600 --> 0:05:42.840 algorithms for finding something attractive get programmed into the genes, 0:05:43.400 --> 0:05:47.640 which unfold the wiring of the brain and allow us 0:05:47.680 --> 0:05:51.479 to grow up and have this attraction and sexual drive. 0:05:51.920 --> 0:05:56.279 Because the weird thing is we inherit this psychological drive 0:05:56.360 --> 0:06:00.000 for sexual interaction, but it doesn't kick in for years. 0:06:00.120 --> 0:06:05.800 Is like thirteen years. So somehow the psychological machine code 0:06:06.320 --> 0:06:11.640 is pre programmed genetically, but it gets archived for years 0:06:11.640 --> 0:06:14.640 and years. So let's think about that. Everything that we 0:06:14.680 --> 0:06:18.800 study in biology happens on the scale of milliseconds. You've 0:06:18.800 --> 0:06:21.839 heard me talk about electrical spikes and neurons these last 0:06:21.880 --> 0:06:26.760 one millisecond, and gene expression and chemical reactions and cells 0:06:26.800 --> 0:06:29.159 and the CREB cycle and so on. All these things 0:06:29.200 --> 0:06:33.080 are trucking along at the nanosecond time scale. So the 0:06:33.120 --> 0:06:36.760 idea of programming something out of this material that takes 0:06:36.839 --> 0:06:41.839 thirteen years to unpack is mind blowing. Now, how do 0:06:41.920 --> 0:06:47.160 we know that sexuality isn't something that's learned? Well, Sometimes 0:06:47.200 --> 0:06:50.680 young children get damage to their brains, usually via an 0:06:50.720 --> 0:06:53.760 infection that leads to encephalitis, and then they end up 0:06:53.800 --> 0:06:57.520 doing things that look like sexual acts, even though they're 0:06:57.560 --> 0:07:00.360 too young to understand what they're doing. They end up 0:07:00.400 --> 0:07:04.080 expressing these programs too early. And that's how we know 0:07:04.160 --> 0:07:08.440 that these programs are in there, just waiting to be unpacked. 0:07:08.880 --> 0:07:11.800 So for everyone else, for whom this program unpacks at 0:07:11.840 --> 0:07:16.360 the right time. Once we've hit puberty, suddenly kids find 0:07:16.400 --> 0:07:20.080 themselves paying attention to body parts that they never paid 0:07:20.120 --> 0:07:24.360 much attention to before. If you draw a curvy line 0:07:24.640 --> 0:07:27.040 and show it to a seven year old boy and 0:07:27.120 --> 0:07:30.920 ask him to describe what he sees, he'll describe it 0:07:30.960 --> 0:07:34.480 as mountains or an ocean wave or something. But show 0:07:34.560 --> 0:07:38.520 him this exact same curved line when he's thirteen, and 0:07:38.560 --> 0:07:42.160 he can't help but interpret the line as breasts and 0:07:42.200 --> 0:07:45.720 buttocks and so on. Nothing changed in the outside world, 0:07:45.800 --> 0:07:48.840 but his brain changed on the inside such that the 0:07:49.120 --> 0:07:53.680 interpretation of the world changes. So we are hardwired. We're 0:07:53.720 --> 0:07:58.200 preprogrammed to, at the right time be attracted to others, 0:07:58.360 --> 0:08:01.240 like frogs to smell or by, or flies to colors, 0:08:01.360 --> 0:08:03.600 or bower birds to a good nest and so on, 0:08:04.160 --> 0:08:06.840 And suddenly it sucks up a lot of our mental energy. 0:08:07.360 --> 0:08:09.960 And I'm stating the obvious here. This is because there 0:08:10.000 --> 0:08:16.120 are few pressures as important as the evolutionary pressure to mate. Now, 0:08:16.160 --> 0:08:19.000 something that's wild about this pre programming is that it 0:08:19.080 --> 0:08:24.240 is very species specific. You don't find a horse's lips 0:08:24.480 --> 0:08:28.400 kissable or a monkey's eyes something that you want to 0:08:28.480 --> 0:08:32.760 gaze into romantically. But from a biologist's point of view, 0:08:33.320 --> 0:08:36.920 they're not that different. They accomplish the same function using 0:08:36.960 --> 0:08:40.600 the same machinery running on the same biological program. So 0:08:40.679 --> 0:08:44.000 what's the difference. The difference is that you are pre 0:08:44.040 --> 0:08:48.800 programmed to be mesmerized by the equipment of your own species, 0:08:49.200 --> 0:08:51.880 and not by the wrong keys to a different lock, 0:08:51.960 --> 0:08:55.840 even though they're so similar biologically. Now, note that to 0:08:55.920 --> 0:08:59.440 the frog or the monkey or the turkey vulture, their 0:08:59.559 --> 0:09:03.240 mate is the most magnetic thing in their world. You 0:09:03.280 --> 0:09:06.320 could stand all day naked in front of a frog 0:09:06.440 --> 0:09:08.480 and it just wouldn't care at all. It would have 0:09:09.000 --> 0:09:12.320 zero interest in you. But if you stick the right 0:09:12.440 --> 0:09:17.520 frog in front of it, that's the most wonderful, magnetic, 0:09:17.760 --> 0:09:21.080 dizzying thing in the world, and they'll expend great effort 0:09:21.360 --> 0:09:26.319 to get over there. So this notion of attractiveness drives everything, 0:09:26.520 --> 0:09:31.120 But you typically don't have conscious access to the details 0:09:31.200 --> 0:09:34.640 running under the hood. I mentioned in an earlier episode 0:09:34.679 --> 0:09:38.360 about the unconscious brain. An experiment in which men were 0:09:38.400 --> 0:09:42.800 asked to rank the attractiveness of different women's faces and photographs. 0:09:43.480 --> 0:09:46.040 So the men flipped through all these photographs and ranked 0:09:46.040 --> 0:09:50.320 each one from one to ten. Unbeknownst to the men, 0:09:50.720 --> 0:09:53.920 in half the photos the women's eyes were dilated, but 0:09:54.000 --> 0:09:56.760 in the other half they weren't, and the men were 0:09:56.840 --> 0:10:00.720 consistently more attracted to the women with di dilated eyes. 0:10:01.040 --> 0:10:04.720 But the men didn't have any insight into their decision making. 0:10:05.040 --> 0:10:07.960 None of them said, oh, I noticed that her pupils 0:10:07.960 --> 0:10:11.120 were two millimeters larger in this photo than this other one. Instead, 0:10:11.160 --> 0:10:14.920 they simply felt more drawn towards some women than others, 0:10:15.280 --> 0:10:18.680 for reasons they couldn't put a finger on. In the 0:10:18.760 --> 0:10:23.680 largely inaccessible workings of their brains, something new that a 0:10:23.880 --> 0:10:29.320 woman's dilated eyes correlates with sexual excitement. Their brains knew this, 0:10:29.440 --> 0:10:33.840 but the men did not, not explicitly. They also presumably 0:10:33.920 --> 0:10:38.600 didn't know that their feelings of attraction are deeply hardwired, 0:10:39.000 --> 0:10:42.880 steered in the right direction by programs carved over millions 0:10:42.880 --> 0:10:46.040 of years of natural selection. So when the men were 0:10:46.040 --> 0:10:49.120 picking up their pencil and making their choices, they didn't 0:10:49.160 --> 0:10:53.280 know that the choice was not theirs. Really, but instead 0:10:53.320 --> 0:10:57.760 the choice of successful programs that had been burned deep 0:10:57.840 --> 0:11:01.440 into the brain's circuitry over the course of hundreds of 0:11:01.559 --> 0:11:23.240 thousands of generations. The great psychologist William James was one 0:11:23.280 --> 0:11:26.360 of the first to really point to the hidden nature 0:11:26.520 --> 0:11:31.199 of instincts, and he suggested that we coax instincts into 0:11:31.240 --> 0:11:34.560 the light by a simple mental exercise. Try to make 0:11:34.920 --> 0:11:40.160 the natural theme strange by asking the why of any 0:11:40.280 --> 0:11:43.080 instinctive human act. So I'm going to read you an 0:11:43.120 --> 0:11:46.560 incredible passage that he wrote in eighteen ninety, and it 0:11:46.600 --> 0:11:50.760 goes like this quote, Why do we smile when pleased 0:11:50.880 --> 0:11:54.280 and not scowl? Why are we unable to talk to 0:11:54.400 --> 0:11:57.240 a crowd as we talk to a single friend. Why 0:11:57.280 --> 0:12:01.040 does a particular maiden turn our wits so upside down? 0:12:01.720 --> 0:12:04.560 The common man can only say, of course we smile. 0:12:04.880 --> 0:12:07.880 Of course our heart palpitates at the sight of a crowd. 0:12:08.200 --> 0:12:12.000 Of course we love the maiden, that beautiful soul clad 0:12:12.040 --> 0:12:15.960 in the perfect form, so palpably and flagrantly made for 0:12:16.000 --> 0:12:20.760 all eternity to be loved. And so probably does each 0:12:20.880 --> 0:12:24.280 animal feel about the particular things it tends to do 0:12:24.679 --> 0:12:28.680 in the presence of particular objects. To the lion. It 0:12:28.800 --> 0:12:31.520 is the lioness which is made to be loved to 0:12:31.600 --> 0:12:35.720 the bear, the she bear to the bruty. Hen the 0:12:35.760 --> 0:12:39.280 notion would probably seem monstrous that there would be a 0:12:39.320 --> 0:12:41.760 creature in the world to whom a nest full of 0:12:41.880 --> 0:12:46.480 eggs was not the utterly fascinating and precious, and never 0:12:46.559 --> 0:12:49.240 to be too much sad upon object which it is 0:12:49.280 --> 0:12:53.880 to her. Thus we may be sure that, however mysterious 0:12:53.960 --> 0:12:58.320 some animal's instincts may appear to us, our instincts will 0:12:58.360 --> 0:13:04.520 appear no less mysterious to them end quote. So our 0:13:04.640 --> 0:13:08.560 most hardwired instincts have usually been left out of the 0:13:08.600 --> 0:13:11.600 spotlight of inquiry because we don't think to ask them, 0:13:11.960 --> 0:13:15.240 and because psychologists have spent a lot of time working 0:13:15.280 --> 0:13:20.400 to understand uniquely human acts like higher cognition, or how 0:13:20.440 --> 0:13:25.000 things go wrong like human mental disorders. But the most automatic, 0:13:25.240 --> 0:13:29.520 effortless acts, those that require the most specialized in complex 0:13:29.559 --> 0:13:32.560 neural circuitry, they've been in front of us all along, 0:13:33.440 --> 0:13:35.959 and in the case of today's exploration, that's the notion 0:13:36.040 --> 0:13:39.360 of sexual attraction. Now, before I get back to that, 0:13:39.400 --> 0:13:42.680 I want to make a general neuroscience point. The more 0:13:42.840 --> 0:13:46.520 obvious and effortless something seems, the more we need to 0:13:46.600 --> 0:13:49.720 suspect that it seems that way only because of the 0:13:49.840 --> 0:13:54.280 massive circuitry that's living behind it. Take something like seeing, 0:13:54.640 --> 0:13:59.280 the active seeing is so easy and rapid precisely because 0:13:59.280 --> 0:14:02.960 we have so much circuitry dedicated to it. About a 0:14:03.000 --> 0:14:06.600 third of the brain is devoted to vision. The more 0:14:06.760 --> 0:14:10.559 effortless something seems, the more we can be pretty sure 0:14:10.679 --> 0:14:13.040 that there's a lot of cycles being burned under the 0:14:13.080 --> 0:14:16.920 hood to make it appear so. And the same principle 0:14:16.960 --> 0:14:20.600 applies to our sexual attractions. Our lust circuits are not 0:14:20.720 --> 0:14:24.680 driven by the shiny faced frog because we cannot mate 0:14:24.760 --> 0:14:27.000 with frogs and they have nothing to do with our 0:14:27.120 --> 0:14:30.560 genetic future. On the other hand, we do care quite 0:14:30.600 --> 0:14:34.480 a bit about subtle human body language, or the dilation 0:14:34.600 --> 0:14:37.840 of eyes or the fleshing of skin, because those things 0:14:37.880 --> 0:14:43.160 broadcast important information about something that could impact our genetic future. 0:14:43.480 --> 0:14:46.920 We live inside the fish bowl of our instincts, and 0:14:46.960 --> 0:14:51.000 we typically have as little perception of them as the 0:14:51.040 --> 0:14:54.880 fish does of its water. So our sense of beauty 0:14:54.920 --> 0:14:59.640 and attraction is burned deeply and inaccessibly into the brain, 0:15:00.320 --> 0:15:05.080 all with the purpose of accomplishing something biologically useful. So 0:15:05.160 --> 0:15:09.040 think about the most beautiful person you know, just magnetic, 0:15:09.200 --> 0:15:12.360 just some shouldn't say kuhah. When that person walks into 0:15:12.360 --> 0:15:15.560 the room. The geography of the room changes a bit 0:15:15.600 --> 0:15:19.720 as everyone turns to look. Our brains are exquisitely honed 0:15:20.040 --> 0:15:23.800 to pick up on those signals. Simply because of small 0:15:23.920 --> 0:15:29.440 details of symmetry and structure, that person enjoys a destiny 0:15:29.480 --> 0:15:34.000 of greater popularity and faster promotions and a more successful career. 0:15:34.560 --> 0:15:37.520 Our sense of attraction is not something just to be 0:15:37.600 --> 0:15:41.240 studied by the pens of poets, but instead, our sense 0:15:41.280 --> 0:15:45.760 of beauty results from specific signals that plug into dedicated 0:15:45.840 --> 0:15:49.320 neural software the key in the lock. So I'll share 0:15:49.360 --> 0:15:52.280 with you some data, and this is all research that 0:15:52.360 --> 0:15:55.920 scientists have performed in the laboratory and published peer reviewed 0:15:55.920 --> 0:15:58.320 papers on. I will say that there seems to be 0:15:58.360 --> 0:16:01.680 more literature on what males attractive. But keep in mind 0:16:01.840 --> 0:16:04.200 that even though it's often said that males are more 0:16:04.360 --> 0:16:07.760 visually driven, much of this research goes the other way too. 0:16:08.360 --> 0:16:10.240 And if you hear this data and you think, well, wait, 0:16:10.280 --> 0:16:12.880 what about our gay friends, keep in mind that the 0:16:13.040 --> 0:16:17.320 drive of attraction is deeply built into our psychology, and 0:16:17.360 --> 0:16:20.760 sometimes the gender someone is attracted to can switch, but 0:16:20.880 --> 0:16:24.920 the fundamental drives in the brain remain the same. This 0:16:25.040 --> 0:16:28.840 is because the drive to reproduce is really the most 0:16:28.880 --> 0:16:32.760 ancient brain circuitry we have, So even if someone does 0:16:32.800 --> 0:16:36.040 not reproduce personally, they're still equipped with and driven by 0:16:36.600 --> 0:16:40.400 the same circuitry which drives them towards sex. So let's 0:16:40.400 --> 0:16:42.280 return to what I said at the beginning, which is 0:16:42.280 --> 0:16:46.360 that the signals driving us are generally correlated with signals 0:16:46.360 --> 0:16:50.560 of health and fertility. So until puberty, the faces and 0:16:50.600 --> 0:16:54.960 body shapes of boys and girls are essentially similar. But 0:16:55.040 --> 0:17:00.000 the rise in estrogen in pubescent girls gives them fuller lifts, 0:17:00.560 --> 0:17:04.960 while testosterone and boys produces a more prominent chin and 0:17:05.000 --> 0:17:09.680 a larger nose and a fuller jaw. Estrogen causes the 0:17:09.720 --> 0:17:14.679 growth of breasts and buttocks, while testosterone encourages the growth 0:17:14.720 --> 0:17:20.480 of muscles and broad shoulders. So for a female, full lips, 0:17:20.680 --> 0:17:25.800 full buttocks, narrow waste. This broadcasts a clear message I'm 0:17:25.840 --> 0:17:30.720 full of estrogen and fertile. For a male, it's the 0:17:30.760 --> 0:17:34.840 full jaw, the stubble, the broad chest. This is the 0:17:34.920 --> 0:17:38.600 kind of stuff that we're programmed to find beautiful. The 0:17:38.840 --> 0:17:43.320 external signs tell us something about the internal, and our 0:17:43.400 --> 0:17:47.360 neural programs are so ingrained that there's not much variation 0:17:47.520 --> 0:17:53.000 across the population. Researchers have measured a surprisingly narrow range 0:17:53.119 --> 0:17:57.440 of the female proportions that males find most attractive. The 0:17:57.520 --> 0:18:01.240 optimal ratio between the waist and hips is typically between 0:18:01.560 --> 0:18:05.960 point sixty seven and point eight. Back when Playboy centerfolds 0:18:06.000 --> 0:18:09.400 were a thing, researchers studied those and found that their 0:18:09.440 --> 0:18:13.680 waist hip ratios remained at about point seven over time, 0:18:13.800 --> 0:18:17.000 even over the decades as the average weight of a 0:18:17.040 --> 0:18:21.440 centerfold moved up or down. As women grow older, their 0:18:21.520 --> 0:18:26.000 features change in ways that depart from these proportions, their 0:18:26.040 --> 0:18:30.400 middles sticking, their lips thin, their breasts sag, and so on, 0:18:30.560 --> 0:18:33.840 all of which broadcasts the visual signal that they are 0:18:34.000 --> 0:18:37.640 past peak fertility. So a young man ends up being 0:18:37.760 --> 0:18:41.160 less attracted to an elderly woman than to a young 0:18:41.200 --> 0:18:45.760 adult woman. His neural circuits have a clear mission reproduce, 0:18:45.880 --> 0:18:50.040 and his conscious mind receives only the need to know headline, 0:18:50.119 --> 0:18:54.280 she's really attractive, and nothing more. All these computations are 0:18:54.359 --> 0:18:59.760 performed unconsciously. Now, males are often more visually driven than females, 0:18:59.760 --> 0:19:03.800 but women are nonetheless subject to the same internal forces. 0:19:03.800 --> 0:19:08.280 They are drawn by the attractive features that flag the 0:19:08.320 --> 0:19:11.840 maturity of manhood. Now, an interesting twist is that a 0:19:11.920 --> 0:19:16.520 woman's preferences can change depending on the time of month. 0:19:17.040 --> 0:19:21.480 Women prefer masculine looking men when they're ovulating, but when 0:19:21.480 --> 0:19:25.600 they're not ovulating, the data suggests that they prefer softer features, 0:19:25.640 --> 0:19:30.159 which presumably flag more social and caring behavior. Although the 0:19:30.320 --> 0:19:35.360 programs of seduction and pursuit run almost entirely unconsciously, the 0:19:35.520 --> 0:19:38.640 endgame is obvious to everyone, and this is why millions 0:19:38.720 --> 0:19:43.159 of people shell out billions of dollars for facelifts and 0:19:43.240 --> 0:19:47.040 tummy tucks and implants and light bosuction and botox. They're 0:19:47.160 --> 0:19:52.199 working to tap into that strong correlation in other people's 0:19:52.280 --> 0:19:57.600 brains between their external and internal. They're working to maintain 0:19:57.680 --> 0:20:23.560 the keys that unlock the pro programs in other people's brains. So, 0:20:23.640 --> 0:20:27.240 as I've said, we have almost no direct access into 0:20:27.280 --> 0:20:32.800 the mechanics of our attractions. Instead, visual information plugs into 0:20:33.080 --> 0:20:37.240 ancient neural modules that drive our behavior. Recall that experiment 0:20:37.280 --> 0:20:39.840 that I just mentioned when men ranked the beauty of 0:20:39.880 --> 0:20:43.280 women's faces. They found the women with dilated eyes more 0:20:43.320 --> 0:20:47.600 attractive because dilated eyes signal sexual interest, but the men 0:20:47.680 --> 0:20:51.119 had no conscious access to their decision making process. Now 0:20:51.160 --> 0:20:53.240 I'll give you another piece of data which is sort 0:20:53.240 --> 0:20:57.199 of mind blowing and demonstrates how deeply and unconsciously we 0:20:57.280 --> 0:21:01.520 pick up on signals. First, consider this strange fact that 0:21:01.960 --> 0:21:06.120 human females are unique among primates and that they participate 0:21:06.200 --> 0:21:10.760 in mating year round. They don't broadcast any special signal 0:21:11.160 --> 0:21:14.119 to publicize when they are fertile, and this is totally 0:21:14.160 --> 0:21:18.720 different from other primates who have these periodic cycles of 0:21:18.800 --> 0:21:22.840 being in heat. All other female mammals give off clear 0:21:22.960 --> 0:21:26.080 signals when they're in heat. For example, in female babboons, 0:21:26.160 --> 0:21:29.920 the rear end turns bright pink, which is an unmistakable 0:21:29.920 --> 0:21:34.199 and irresistible invitation for a male baboon. Human females just 0:21:34.240 --> 0:21:37.359 don't give off signals like this, or don't they. It 0:21:37.440 --> 0:21:40.720 turns out that a woman is considered to be most 0:21:40.800 --> 0:21:44.840 beautiful just at the peak of fertility in her menstrual cycle, 0:21:45.080 --> 0:21:48.560 about ten days before mensi's. This is true whether she 0:21:48.680 --> 0:21:51.560 is judged by men or by women, and it's not 0:21:51.640 --> 0:21:54.360 a matter of how she acts. It's perceived this way, 0:21:54.440 --> 0:21:57.399 even if people are just looking at her photograph, so 0:21:57.560 --> 0:22:02.600 her good looks broadcast her level of fertility. Her signals 0:22:02.680 --> 0:22:05.840 are more subtle than the baboons, but they only need 0:22:05.880 --> 0:22:10.359 to be clear enough to tickle the dedicated, unconscious machinery 0:22:10.760 --> 0:22:13.560 of the males in the room. If the signals can 0:22:13.640 --> 0:22:17.240 reach those circuits, the mission is accomplished. The signals also 0:22:17.320 --> 0:22:21.320 reach the circuitry of other females. Women are quite sensitive 0:22:21.359 --> 0:22:25.280 to the effect of other women's cycles, perhaps because this 0:22:25.400 --> 0:22:29.360 lets them assess their competitors when competing for mates. It's 0:22:29.400 --> 0:22:32.480 not yet clear what the tip offs for fertility are. 0:22:32.960 --> 0:22:35.919 They may include some qualities of the skin, or the 0:22:35.960 --> 0:22:39.920 fact that a women's ears and breasts become more symmetrical 0:22:40.440 --> 0:22:43.960 in the days leading up to ovulation. Whatever the constellation 0:22:44.080 --> 0:22:47.760 of clues are, our brains are engineered to latch on. 0:22:48.040 --> 0:22:51.119 Even while the conscious mind has no axis. Your mind 0:22:51.240 --> 0:22:56.879 simply senses the almighty and inexplicable tug of desire. The 0:22:57.000 --> 0:23:00.880 effects of ovulation and beauty are not not just assessed 0:23:00.960 --> 0:23:04.680 in the laboratory. They are measurable in real life situations. 0:23:05.200 --> 0:23:07.280 Some years ago I'm not making this up. There was 0:23:07.280 --> 0:23:11.840 a study by scientists who counted up the tips made 0:23:11.840 --> 0:23:16.200 by exotic dancers at the local strip clubs and correlated 0:23:16.240 --> 0:23:20.119 this with the menstrual cycles of the dancers. And what 0:23:20.200 --> 0:23:24.639 they found is that during peak fertility, dancers raked in 0:23:24.720 --> 0:23:27.560 an average of sixty eight dollars an hour. When they 0:23:27.600 --> 0:23:31.359 were menstruating, they earned only about thirty five dollars, and 0:23:31.640 --> 0:23:35.360 in between they averaged about fifty two dollars. So although 0:23:35.359 --> 0:23:40.240 these women were presumably acting flirtatiously throughout the month, their 0:23:40.440 --> 0:23:45.840 change in fertility was broadcast to hopeful customers by changes 0:23:45.960 --> 0:23:50.760 in body odor, skin, wasted, hip ratio, and possibly their 0:23:50.760 --> 0:23:55.560 own confidence as well. Now, interestingly, dancers on birth control 0:23:55.640 --> 0:23:59.160 didn't show any clear peak in performance and earned only 0:23:59.240 --> 0:24:02.560 a monthly average of thirty seven dollars per hour versus 0:24:02.560 --> 0:24:05.760 an average of fifty three dollars per hour for dancers 0:24:05.800 --> 0:24:10.479 not on birth control. Presumably they earned less because the 0:24:10.560 --> 0:24:16.760 pill leads to hormonal changes and cues indicative of early pregnancy, 0:24:17.160 --> 0:24:20.800 and so the dancers were presumably slightly less magnetic to 0:24:20.920 --> 0:24:24.520 the customers in the club. All this research drives home 0:24:24.600 --> 0:24:28.920 the point that the pulls we feel are built deeply 0:24:29.040 --> 0:24:32.080 into our neural machinery. We don't have conscious access to 0:24:32.119 --> 0:24:36.760 the programs and can only surface these issues with careful studies. 0:24:37.359 --> 0:24:39.880 And the part that's always amazed me is how subtle 0:24:39.880 --> 0:24:42.359 these signals are. The brain is picking up on these 0:24:42.480 --> 0:24:46.959 really small signals. So think again about that really attractive 0:24:47.000 --> 0:24:51.119 person you know, and imagine that you measured the distance 0:24:51.359 --> 0:24:54.320 between his or her eyes and nose length and lip 0:24:54.440 --> 0:24:57.760 thickness and chin shape and so on. If you compare 0:24:57.840 --> 0:25:01.560 those measurements to those of a a not so attractive 0:25:01.600 --> 0:25:04.480 person you know, you would find that the differences are 0:25:04.520 --> 0:25:08.480 really subtle, like a centimeter here, a centimeter there, But 0:25:08.560 --> 0:25:12.000 it makes a big difference in your final judgment. So 0:25:12.119 --> 0:25:15.040 imagine you took these two people, one attractive, one not 0:25:15.119 --> 0:25:19.320 so attractive, and showed them to a space alien. That 0:25:19.440 --> 0:25:22.919 two humans would look indistinguishable to the alien in the 0:25:22.960 --> 0:25:26.520 same way that attractive and unattractive space aliens would be 0:25:26.520 --> 0:25:29.760 difficult for you to tell apart, But the small differences 0:25:29.800 --> 0:25:32.960 within your own species, these have a great deal of 0:25:33.000 --> 0:25:36.480 effect in your brain. As an example of tiny differences, 0:25:36.600 --> 0:25:40.000 just consider that some people might find the site of 0:25:40.040 --> 0:25:44.399 a woman in short shorts intoxicating, and a male in 0:25:44.440 --> 0:25:48.280 short shorts less attractive. Even though the two scenes are 0:25:48.359 --> 0:25:53.159 hardly different. From a geometrical perspective, male and female legs 0:25:53.480 --> 0:25:55.800 just don't look that different. Both are built on the 0:25:55.880 --> 0:25:59.639 same architecture. They're both hinged limbs made of femurs and 0:25:59.720 --> 0:26:02.919 knee caps and skin and so on, and the differences 0:26:02.960 --> 0:26:06.640 between them are swamped by the similarities. I mean, if 0:26:06.640 --> 0:26:10.080 I showed you a female hawk and a male hawk, 0:26:10.160 --> 0:26:13.080 you really couldn't tell the difference between them. But other 0:26:13.200 --> 0:26:18.120 hawks are exquisitely sensitive to these differences. With all these animals, 0:26:18.119 --> 0:26:20.880 they're so similar that you really have to train up 0:26:21.000 --> 0:26:24.080 to see the differences. And this is the point I 0:26:24.119 --> 0:26:28.280 want to make. We are so exquisitely tuned to the 0:26:28.320 --> 0:26:31.720 differences in humans, and we don't even realize it. Our 0:26:31.760 --> 0:26:36.480 ability to make subtle distinctions is exquisitely fine grained. Our 0:26:36.520 --> 0:26:40.600 brains are engineered to accomplish the clear cut task of 0:26:40.680 --> 0:26:44.359 mate selection. In pursuit, all of the computation lives under 0:26:44.359 --> 0:26:48.240 the surface of conscious awareness. We get to simply enjoy 0:26:48.359 --> 0:26:51.440 the lovely feelings that bubble up. And I'll give you 0:26:51.520 --> 0:26:56.040 another example of this attractive misjudgments are not only constructed 0:26:56.040 --> 0:26:59.920 by your visual system, but they're influenced as well by smell. 0:27:00.560 --> 0:27:05.000 So odor carries a great deal of information, including information 0:27:05.040 --> 0:27:11.720 about a potential mate's age, sex, fertility, identity, emotions, health. 0:27:12.359 --> 0:27:17.280 The information is carried by a flotilla of drifting molecules, 0:27:17.800 --> 0:27:22.560 so in many animal species, these compounds drive behavior almost entirely. 0:27:23.200 --> 0:27:27.600 In humans, the information often flies beneath the radar of 0:27:27.640 --> 0:27:31.480 conscious perception, but they nonetheless influence our behavior a bit. 0:27:31.920 --> 0:27:35.679 So imagine we give a female mouse a selection of 0:27:35.760 --> 0:27:40.800