1 00:00:06,464 --> 00:00:07,507 [narrator] Hey, you. 2 00:00:07,590 --> 00:00:10,260 Do you usually fall for the cool, rebellious type? 3 00:00:10,510 --> 00:00:12,846 Or are you more into the brooding artist? 4 00:00:13,805 --> 00:00:15,432 Do you vibe with shy and nerdy 5 00:00:15,724 --> 00:00:17,183 or charming and flirty? 6 00:00:17,767 --> 00:00:19,811 Are you all about guys? Hmm. 7 00:00:19,894 --> 00:00:21,646 Maybe you also like girls. 8 00:00:22,564 --> 00:00:23,398 Does it matter? 9 00:00:24,441 --> 00:00:26,651 Lanky, ripped, buzz cuts, 10 00:00:26,735 --> 00:00:29,738 man buns, full beards, strong brows, 11 00:00:29,821 --> 00:00:32,032 small breasts, big butts... 12 00:00:32,115 --> 00:00:34,200 -[chattering] -[narrator] Is it more about their smile 13 00:00:34,284 --> 00:00:35,952 -or how they make you laugh? -[laughs] 14 00:00:36,036 --> 00:00:38,496 [narrator] Are you attracted to people you're embarrassed about, 15 00:00:38,621 --> 00:00:40,331 -so you keep it a secret? -[gasps] 16 00:00:40,832 --> 00:00:43,251 [narrator] We all have a type or a few types. 17 00:00:43,752 --> 00:00:45,420 -I know I do. -[woman] Oh! 18 00:00:45,503 --> 00:00:47,797 [narrator] So where do these types come from? 19 00:00:48,048 --> 00:00:51,718 Why are we attracted to some people... and not others? 20 00:00:52,469 --> 00:00:54,429 I think you're cute. 21 00:00:54,512 --> 00:00:56,139 [theme music playing] 22 00:00:56,222 --> 00:00:58,933 [Justin Timberlake] I mean, you know it if you have a chemistry with somebody. 23 00:00:59,017 --> 00:01:00,852 If I'm vibin' that person, then that's... 24 00:01:00,935 --> 00:01:02,687 You know, don't think about it too much. 25 00:01:02,979 --> 00:01:04,522 [man] What you're sniffing 26 00:01:04,606 --> 00:01:07,442 and searching for are the smells of somebody 27 00:01:07,525 --> 00:01:11,154 who you think might be genetically compatible with you. 28 00:01:11,571 --> 00:01:14,324 [narrator 2] Our brains are designed to latch onto people's attractive features 29 00:01:14,407 --> 00:01:16,618 on our quest to find the right mate. 30 00:01:25,835 --> 00:01:28,588 My body temperature changes. Um... [clicks tongue] 31 00:01:28,671 --> 00:01:33,093 And I get-- I get that, like, warm, fuzzy feeling 32 00:01:33,176 --> 00:01:35,386 usually, like, in the, you know, the guts. 33 00:01:35,553 --> 00:01:38,014 And then it kind of, like, moves down the body. 34 00:01:38,515 --> 00:01:41,935 [narrator] In the moment of attraction, your brain floods you with hormones 35 00:01:42,018 --> 00:01:43,394 that make you feel... 36 00:01:43,561 --> 00:01:45,855 [woman 1] Warm... and tingly, 37 00:01:46,439 --> 00:01:49,526 and it's like my hair stands on end. 38 00:01:49,609 --> 00:01:52,278 All of my senses feel like they're awake. 39 00:01:52,612 --> 00:01:53,988 My heart flutters. 40 00:01:54,614 --> 00:01:57,158 [man] My heart is beating extremely fast. I don't know what to say. 41 00:01:57,242 --> 00:01:59,786 I'm shy. Sometimes I talk way too fast. 42 00:02:00,370 --> 00:02:02,664 [narrator] Dopamine gives you the same pleasurable boost 43 00:02:02,747 --> 00:02:05,416 -as eating sugar or taking drugs, -[person inhales] 44 00:02:05,500 --> 00:02:07,335 with the same powerful cravings. 45 00:02:07,669 --> 00:02:10,130 [woman 2] I feel myself, like, wanting to banter 46 00:02:10,213 --> 00:02:12,549 or wanting to engage in, like, a debate 47 00:02:13,133 --> 00:02:15,093 or, like, looking at their arms. 48 00:02:15,176 --> 00:02:17,011 I'm, like, super into arms. [laughs] 49 00:02:17,595 --> 00:02:20,265 [narrator] And then there's norepinephrine and adrenaline. 50 00:02:20,348 --> 00:02:22,058 The fight-or-flight hormones. 51 00:02:22,142 --> 00:02:25,603 I might get a little nervous feeling, a little anxious... 52 00:02:25,687 --> 00:02:27,313 or I get really excited. 53 00:02:27,939 --> 00:02:31,025 [narrator] Which can make it hard to sleep and eat. 54 00:02:31,943 --> 00:02:35,864 In France, they call the moment of attraction "coup de foudre" 55 00:02:36,072 --> 00:02:38,199 -or a "lightning bolt." -[thunder rumbles] 56 00:02:38,283 --> 00:02:40,910 [narrator] In Arabic, it's "hawa," a wind. 57 00:02:41,411 --> 00:02:44,247 In China, "yuanfen," a fated force. 58 00:02:45,081 --> 00:02:48,168 And in Japan, they say "koi no yokan," 59 00:02:48,251 --> 00:02:51,629 the feeling when you meet someone that you're bound to fall in love. 60 00:02:51,963 --> 00:02:55,675 How do I know if I'm attracted to someone? Um... 61 00:02:56,050 --> 00:02:59,637 It's just kind of this, like, magnetic... [laughs] 62 00:02:59,721 --> 00:03:01,014 Like, it's just kind of like... 63 00:03:01,764 --> 00:03:03,600 I just feel drawn to that person. 64 00:03:04,058 --> 00:03:07,770 When you're attracted to somebody, you shouldn't really be able to explain it 65 00:03:07,854 --> 00:03:09,856 beyond just, like, I'm attracted to them, right? 66 00:03:09,939 --> 00:03:12,150 It should just be visceral, and you should know it. 67 00:03:13,109 --> 00:03:15,612 [narrator] But humans have tried to explain it. 68 00:03:15,695 --> 00:03:17,447 I mean, how could we not? 69 00:03:18,156 --> 00:03:19,949 And we have all kinds of theories. 70 00:03:20,575 --> 00:03:23,494 An astrologer would say, if you're a Taurus, 71 00:03:23,578 --> 00:03:25,246 try to match with a Capricorn. 72 00:03:25,538 --> 00:03:28,249 -But a Sagittarius? No way. -[buzzer sounds] 73 00:03:29,042 --> 00:03:31,377 [narrator] Indian astrologers have long used 74 00:03:31,461 --> 00:03:34,797 an intricate, 36-point analysis to match the bride and groom. 75 00:03:35,381 --> 00:03:38,509 You need at least 18 points for a successful marriage. 76 00:03:39,135 --> 00:03:41,888 And then, in 2015, an article went viral 77 00:03:41,971 --> 00:03:45,975 that claimed when two strangers asked each other these 36 questions, 78 00:03:46,059 --> 00:03:47,352 it's led to love. 79 00:03:48,019 --> 00:03:50,688 Questions like, "What is your most treasured memory?" 80 00:03:51,189 --> 00:03:53,233 "What is your most terrible memory?" 81 00:03:53,316 --> 00:03:56,319 And "Do you have a secret hunch about how you will die?" 82 00:03:56,986 --> 00:04:00,698 According to the magazine Cosmo, you can make anyone fall in love with you 83 00:04:00,782 --> 00:04:02,867 in 12 easy steps, including: 84 00:04:03,368 --> 00:04:04,285 eye contact, 85 00:04:04,494 --> 00:04:06,412 focusing on the ways you're similar, 86 00:04:06,496 --> 00:04:08,414 hanging around them a lot, 87 00:04:08,498 --> 00:04:11,125 and, uh, "love them"? 88 00:04:11,209 --> 00:04:12,502 Okay, sure. 89 00:04:12,919 --> 00:04:14,587 But scientists, for decades, 90 00:04:14,671 --> 00:04:16,923 said it pretty much all came down to our genes, 91 00:04:17,298 --> 00:04:19,425 and we're all attracted to the same type: 92 00:04:20,343 --> 00:04:22,637 a fit and fertile mating partner. 93 00:04:22,720 --> 00:04:26,474 Because we're animals, we just want to reproduce. 94 00:04:27,058 --> 00:04:29,894 [man] More symmetric men smell better to women, 95 00:04:29,978 --> 00:04:32,438 specifically to women who are at the fertile phase 96 00:04:32,522 --> 00:04:33,856 of the menstrual cycle. 97 00:04:33,940 --> 00:04:36,567 [narrator 2] Men are thought to have a preference for curved hips, 98 00:04:36,651 --> 00:04:39,821 because this signals enough fat deposits on the hips 99 00:04:39,904 --> 00:04:41,614 for health and fertility. 100 00:04:42,198 --> 00:04:44,826 [narrator 3] Men choose women with large breasts 101 00:04:44,909 --> 00:04:48,288 because they're seen as good child-rearing material. 102 00:04:48,705 --> 00:04:50,665 So, there is a sense in which the body 103 00:04:50,748 --> 00:04:53,293 of a woman has been designed through evolution 104 00:04:53,376 --> 00:04:55,378 for the delectation of males. 105 00:04:55,920 --> 00:04:58,881 [narrator] Maybe that's why male video game designers 106 00:04:58,965 --> 00:05:02,260 make pretty much every female character look like this... 107 00:05:02,760 --> 00:05:05,888 'cause they're more fertile. Mm-hmm. 108 00:05:06,014 --> 00:05:09,392 There's definitely an evolutionary component to attraction, 109 00:05:09,767 --> 00:05:12,729 but I think we have to be really careful 110 00:05:12,812 --> 00:05:16,357 in distinguishing between "just so" stories: 111 00:05:16,607 --> 00:05:20,570 Men like women with big breasts because it's good for the species. 112 00:05:21,112 --> 00:05:25,241 There is no evidence of any link 113 00:05:25,325 --> 00:05:30,496 between large breasts and a pretty face and fertility, all right? 114 00:05:30,580 --> 00:05:33,958 If that were true, our planet would be populated 115 00:05:34,042 --> 00:05:37,795 only with beautiful, large-breasted women, 116 00:05:37,879 --> 00:05:39,714 and that is obviously not true. 117 00:05:39,797 --> 00:05:41,716 One of the things we find quite consistently 118 00:05:41,799 --> 00:05:43,801 is that the social culture in which you grow up 119 00:05:43,885 --> 00:05:47,305 and which you live in has an impact on your body size ideal. 120 00:05:48,181 --> 00:05:50,266 [narrator] Viren traveled to a region of South Africa 121 00:05:50,350 --> 00:05:54,437 with incredibly high rates of HIV and conducted a study, 122 00:05:54,520 --> 00:05:56,606 asking Zulu men living there 123 00:05:56,689 --> 00:05:59,859 to rate a series of photos of women with different body sizes. 124 00:06:00,234 --> 00:06:03,112 On average, the men found this body size 125 00:06:03,196 --> 00:06:05,406 just as attractive as this one, 126 00:06:05,490 --> 00:06:08,868 while all these body sizes were rated as less attractive. 127 00:06:08,951 --> 00:06:11,496 Being extremely thin, in that particular context, 128 00:06:11,579 --> 00:06:13,081 was associated with HIV. 129 00:06:13,915 --> 00:06:16,501 [narrator] Viren also showed these images to Zulu men 130 00:06:16,584 --> 00:06:18,836 who had recently moved to the UK. 131 00:06:19,003 --> 00:06:22,173 Those men rated this body size as the ideal... 132 00:06:22,632 --> 00:06:25,635 and rated these body sizes as less attractive. 133 00:06:25,927 --> 00:06:28,346 The ideal body size changed very quickly 134 00:06:28,429 --> 00:06:32,016 to match what was ideal in the UK, which was a relatively thin body. 135 00:06:32,100 --> 00:06:34,519 [narrator] And if humans are just like any other animal, 136 00:06:34,602 --> 00:06:36,104 something else doesn't make sense. 137 00:06:36,646 --> 00:06:39,315 In a lot of animal species, the males are the ones 138 00:06:39,399 --> 00:06:41,984 with the pressure to look pretty and impress the females. 139 00:06:42,568 --> 00:06:45,238 Like in birds, where they get pretty sexy, 140 00:06:46,697 --> 00:06:49,033 because they often have to compete for mates. 141 00:06:50,493 --> 00:06:52,745 But mating in the human world looks different. 142 00:06:52,829 --> 00:06:56,707 A 1989 study of 37 cultures around the world found that 143 00:06:56,791 --> 00:07:00,253 men care more about their female partners being attractive and young... 144 00:07:00,336 --> 00:07:03,798 as in "fertile," to have more babies to pass on their genes, 145 00:07:04,340 --> 00:07:07,343 while women cared more about financial capacity, 146 00:07:07,427 --> 00:07:09,470 ambition, and industriousness. 147 00:07:09,554 --> 00:07:14,183 As in, they were or were going to be rich to provide for all those babies. 148 00:07:14,684 --> 00:07:18,604 And especially if you watch a lot of reality TV, that feels true, 149 00:07:18,855 --> 00:07:21,190 because these shows play up those different motives. 150 00:07:21,274 --> 00:07:22,733 [woman 1] I know you're traveling a lot, 151 00:07:22,817 --> 00:07:25,403 so thank you for letting me borrow the plane. I really appreciate it. 152 00:07:25,486 --> 00:07:26,988 [Ronnie] Stereotypes for a guido, 153 00:07:27,071 --> 00:07:29,407 the guy that always looks prettier than his girlfriend, 154 00:07:29,490 --> 00:07:30,741 which is completely unacceptable. 155 00:07:30,825 --> 00:07:32,910 I can't be with a girl that doesn't look prettier than me. 156 00:07:32,994 --> 00:07:34,328 [woman 2] Bri, how old are you? 157 00:07:34,787 --> 00:07:36,247 -So, I am 21. -Oh. 158 00:07:38,916 --> 00:07:41,502 [narrator] A study of profile pictures on the dating app Tinder 159 00:07:41,586 --> 00:07:43,546 also seemed to back this story. 160 00:07:43,671 --> 00:07:46,132 Straight women were more likely than men 161 00:07:46,215 --> 00:07:48,301 to take selfies angled from above, 162 00:07:48,426 --> 00:07:50,636 so their eyes and foreheads looked big, 163 00:07:50,761 --> 00:07:52,763 and everything else looked smaller. 164 00:07:52,847 --> 00:07:56,225 So they look younger, aka, more fertile. 165 00:07:56,309 --> 00:07:59,479 While men were more likely to use selfies angled from below, 166 00:07:59,645 --> 00:08:01,731 so they look taller and more dominant. 167 00:08:02,064 --> 00:08:05,860 In the animal world, that means "better able to acquire resources." 168 00:08:05,943 --> 00:08:08,488 In the human world, that means "rich." 169 00:08:10,156 --> 00:08:13,367 But a 2001 study that reviewed half a century of data 170 00:08:14,285 --> 00:08:17,663 found that as more women entered the workplace and made their own money, 171 00:08:17,747 --> 00:08:20,416 they started caring more about being with a good-looking guy. 172 00:08:21,751 --> 00:08:24,462 And men started caring more about being with a woman 173 00:08:24,545 --> 00:08:26,297 with good financial prospects. 174 00:08:27,215 --> 00:08:29,342 [Viren Swami] The idea that we are simply animals 175 00:08:29,425 --> 00:08:32,637 that only really care about reproducing, 176 00:08:32,720 --> 00:08:35,431 -seems incredibly reductive. -[frog croaks] 177 00:08:35,515 --> 00:08:37,517 It's not simply a biological drive 178 00:08:37,600 --> 00:08:40,061 to have sex with that individual so you can produce offspring. 179 00:08:40,144 --> 00:08:42,146 Now, I'm not saying that that doesn't happen 180 00:08:42,230 --> 00:08:44,106 and that that's not shaping how we might behave 181 00:08:44,190 --> 00:08:45,274 in some situations. 182 00:08:45,733 --> 00:08:48,444 The point, more generally, is that to have a relationship, 183 00:08:48,528 --> 00:08:50,363 to form a relationship with an individual, 184 00:08:50,446 --> 00:08:52,532 or even just to have sex with an individual 185 00:08:52,615 --> 00:08:55,368 requires so much more than just biology. 186 00:08:56,160 --> 00:08:57,662 [narrator] Even identical twins... 187 00:08:57,745 --> 00:09:00,581 same genes, same upbringing, same culture... 188 00:09:01,082 --> 00:09:02,416 don't all have the same type. 189 00:09:03,543 --> 00:09:08,005 In 2015, researchers had hundreds of identical twins rate faces 190 00:09:08,089 --> 00:09:09,298 and plotted the results. 191 00:09:09,590 --> 00:09:11,592 Each dot represents a twin pair. 192 00:09:11,676 --> 00:09:13,719 The X-axis is one twin's rating, 193 00:09:13,803 --> 00:09:15,972 and the Y-axis is the other twin's rating. 194 00:09:16,264 --> 00:09:18,266 If the twins all agreed with each other, 195 00:09:18,349 --> 00:09:20,893 you'd expect the correlations to look like this. 196 00:09:21,143 --> 00:09:22,186 But it didn't. 197 00:09:22,270 --> 00:09:25,398 The researchers found that a lot of what we're attracted to 198 00:09:25,481 --> 00:09:28,276 comes down to unique environmental factors, 199 00:09:28,359 --> 00:09:30,778 as in your individual life history. 200 00:09:30,861 --> 00:09:33,322 I think I've always had a little bit 201 00:09:33,406 --> 00:09:35,783 of the bad boy that I was attracted to. 202 00:09:36,325 --> 00:09:40,162 [laughing] And that keeps coming back over and over again. 203 00:09:40,246 --> 00:09:41,581 But I had-- 204 00:09:41,664 --> 00:09:44,584 You know, my father was a-- had a little of the "bad boy" in him. 205 00:09:44,667 --> 00:09:47,211 I used to never like dating people who looked like me. 206 00:09:47,295 --> 00:09:48,629 And then, I don't know, recently, 207 00:09:48,713 --> 00:09:50,965 I've been mistaken for people that I've been attracted to. 208 00:09:51,048 --> 00:09:54,594 [laughing] So, it's like, "This person actually looks just like me." 209 00:09:54,677 --> 00:09:57,763 So, I guess it's about loving the self ultimately, you know? 210 00:09:57,847 --> 00:09:58,973 All the guys that I like 211 00:09:59,056 --> 00:10:01,809 end up looking like the stuffed animals I had when I was a kid. 212 00:10:01,892 --> 00:10:04,604 [laughs] So I'm like, "Oh, maybe I'm just looking for security 213 00:10:04,687 --> 00:10:06,272 and comfort that way." 214 00:10:06,355 --> 00:10:10,109 Generally, what a lot of evolutionary psychology suggests 215 00:10:10,192 --> 00:10:13,613 is that as long as you are having enough sex 216 00:10:13,738 --> 00:10:15,823 with other sex partners to reproduce, 217 00:10:16,073 --> 00:10:18,492 it really doesn't matter what else you're attracted to. 218 00:10:18,576 --> 00:10:21,996 Really, evolution doesn't care what else you do with sexuality. 219 00:10:23,080 --> 00:10:26,542 [narrator] Identical twins don't always have the same sexuality either. 220 00:10:26,834 --> 00:10:29,003 In fact, a gay twin is more likely 221 00:10:29,086 --> 00:10:31,672 to have a twin that's straight than gay. 222 00:10:31,922 --> 00:10:34,884 Researchers found when it comes to sexual orientation, 223 00:10:35,092 --> 00:10:38,512 environmental factors play a much more important role than genes. 224 00:10:38,929 --> 00:10:41,891 For women, they're at least four times as important. 225 00:10:42,808 --> 00:10:46,812 But environmental factors, in this case, doesn't mean culture or upbringing. 226 00:10:47,146 --> 00:10:49,982 So, I think when we talk about environment, 227 00:10:50,066 --> 00:10:52,777 we're often thinking, "Oh, your friends or your parents." 228 00:10:52,860 --> 00:10:54,987 But when geneticists are talking about the environment, 229 00:10:55,071 --> 00:10:58,949 we're talking about literally everything that's not a gene. 230 00:10:59,033 --> 00:11:00,826 That's the placenta, right? 231 00:11:00,910 --> 00:11:02,203 That's an environment, too. 232 00:11:02,912 --> 00:11:05,498 [narrator] The womb is everyone's first environment, 233 00:11:05,581 --> 00:11:06,666 and what happens there 234 00:11:06,749 --> 00:11:09,543 may affect who you're attracted to when you grow up. 235 00:11:10,002 --> 00:11:13,381 The amount and timing of hormones a fetus is exposed to 236 00:11:13,464 --> 00:11:14,590 may play a role. 237 00:11:14,799 --> 00:11:17,468 And for males, so could maternal antibodies 238 00:11:17,551 --> 00:11:20,888 that target a certain brain protein made by the Y chromosome. 239 00:11:22,098 --> 00:11:24,892 In some women, those can build up over time 240 00:11:25,017 --> 00:11:26,644 with every male baby she has. 241 00:11:27,436 --> 00:11:30,106 Which may explain why gay men, on average, 242 00:11:30,189 --> 00:11:32,692 have more older brothers than straight men. 243 00:11:33,192 --> 00:11:35,945 There are plenty of environmental influences 244 00:11:36,278 --> 00:11:39,198 that are as fixed as any gene. 245 00:11:39,490 --> 00:11:41,617 So, it's important to remember 246 00:11:41,701 --> 00:11:43,869 that "genetic" doesn't mean "fixed," 247 00:11:44,078 --> 00:11:47,873 and "environmental" doesn't mean "unfixed." 248 00:11:47,957 --> 00:11:50,710 The gene environment balance 249 00:11:50,793 --> 00:11:53,963 for a trait doesn't really say anything 250 00:11:54,046 --> 00:11:56,507 about the fixedness of that trait. 251 00:11:57,299 --> 00:11:59,510 As a child I was like, "Oh, no, I just like boys. 252 00:11:59,593 --> 00:12:00,720 I just like boys." 253 00:12:00,803 --> 00:12:02,346 And my mother would always say to me, 254 00:12:02,430 --> 00:12:04,682 "If you liked girls, too, it'd be okay." Like, she knew. 255 00:12:04,765 --> 00:12:05,891 So, as I've grown up 256 00:12:05,975 --> 00:12:08,436 and as I've started experiencing more sexuality 257 00:12:08,519 --> 00:12:10,146 and getting out into the world more, 258 00:12:10,229 --> 00:12:12,398 my sexuality has also changed. 259 00:12:12,481 --> 00:12:15,317 If you're a man or if you're a woman, if you're trans, if you're not trans-- 260 00:12:15,401 --> 00:12:17,403 You know, those things, I think... 261 00:12:17,486 --> 00:12:19,572 I've met all kinds of people, all kinds of ways, 262 00:12:19,655 --> 00:12:21,991 and they've all been attractive, you know? [laughs] 263 00:12:22,074 --> 00:12:24,160 [narrator] Gender is just another type. 264 00:12:24,744 --> 00:12:27,955 [Lisa Diamond] Some individuals don't necessarily have 265 00:12:28,038 --> 00:12:29,707 a gender-based orientation. 266 00:12:30,166 --> 00:12:32,918 They are more focused on the individual. 267 00:12:33,419 --> 00:12:37,256 Some individuals are just more gender-y than others. 268 00:12:37,715 --> 00:12:40,176 [narrator] In early 19th century Iran, 269 00:12:40,259 --> 00:12:43,721 people were drawn to characteristics that were not very gendered at all. 270 00:12:44,180 --> 00:12:46,891 These young lovers look pretty similar. 271 00:12:46,974 --> 00:12:48,100 And in recent years, 272 00:12:48,184 --> 00:12:50,728 that beauty ideal has become popular in the West, 273 00:12:50,978 --> 00:12:53,856 with some male and female models looking pretty similar, 274 00:12:54,565 --> 00:12:56,567 as ideas of gender have become more fluid. 275 00:12:58,360 --> 00:13:02,740 There is a lot of evidence that suggests that men are a bit more rigid 276 00:13:02,823 --> 00:13:05,576 when it comes to the type of people that they're attracted to. 277 00:13:06,202 --> 00:13:08,871 Women show a lot more flexibility. 278 00:13:09,663 --> 00:13:12,958 [narrator] In one study, a small sample of gay and straight men and women 279 00:13:13,042 --> 00:13:15,878 had their genital sexual response measured 280 00:13:16,545 --> 00:13:18,631 while they were shown a variety of videos. 281 00:13:19,465 --> 00:13:21,717 One was a man and a woman having sex. 282 00:13:22,259 --> 00:13:24,512 Another was men having sex... 283 00:13:24,929 --> 00:13:26,680 and women having sex... 284 00:13:27,014 --> 00:13:28,474 and a man masturbating. 285 00:13:28,808 --> 00:13:30,100 A woman masturbating. 286 00:13:30,684 --> 00:13:33,020 A buff naked man taking a stroll. 287 00:13:33,604 --> 00:13:35,815 A toned naked lady exercising. 288 00:13:36,357 --> 00:13:38,859 And bonobos gettin' it on. 289 00:13:39,902 --> 00:13:41,153 As you might expect, 290 00:13:41,237 --> 00:13:44,824 straight men were more turned on by the videos with women in them. 291 00:13:45,241 --> 00:13:46,867 And also, as you might expect, 292 00:13:46,951 --> 00:13:49,286 gay men preferred the videos featuring men. 293 00:13:49,787 --> 00:13:50,830 But the women, 294 00:13:50,913 --> 00:13:53,624 they were turned on by pretty much everything. 295 00:13:54,208 --> 00:13:58,796 Lesbians were even slightly more aroused by the bonobos than the strolling man. 296 00:13:59,880 --> 00:14:03,592 One of the hallmarks of human sexuality 297 00:14:03,926 --> 00:14:07,346 is that humans are able to use sexuality 298 00:14:07,429 --> 00:14:09,265 for purposes other than reproduction. 299 00:14:09,849 --> 00:14:13,644 It cements social alliances. It reduces stress. 300 00:14:14,103 --> 00:14:18,107 And so, flexibility in the sexual system is a good thing. 301 00:14:18,190 --> 00:14:22,903 It's a part of the ability of sex to serve multiple functions. 302 00:14:23,863 --> 00:14:25,906 [narrator] And according to the latest research, 303 00:14:25,990 --> 00:14:28,659 attraction mostly comes down to four main pillars... 304 00:14:29,368 --> 00:14:30,744 and they're pretty simple. 305 00:14:30,828 --> 00:14:33,914 The first one is physical appearance, obviously. 306 00:14:34,039 --> 00:14:37,418 But then, the second pillar of attraction is... geography? 307 00:14:37,501 --> 00:14:40,629 In the UK, for example, the majority of relationships 308 00:14:40,713 --> 00:14:44,049 are formed between people who live relatively nearby, 309 00:14:44,133 --> 00:14:47,678 probably between five and ten kilometers away at most. 310 00:14:48,137 --> 00:14:51,807 [narrator] And we like people who have the qualities we value in ourselves. 311 00:14:51,891 --> 00:14:53,809 Opposites almost never attract. 312 00:14:53,893 --> 00:14:56,687 People who are too different or who have different values to us, 313 00:14:56,770 --> 00:14:59,398 we often find that they-- they cause discomfort in us. 314 00:15:00,107 --> 00:15:01,442 [narrator] The fact that you and your partner 315 00:15:01,525 --> 00:15:02,902 have compatible star signs 316 00:15:02,985 --> 00:15:06,447 matters less than the fact that you both care about star signs. 317 00:15:07,114 --> 00:15:08,616 Well, you gotta be smart. 318 00:15:08,699 --> 00:15:11,243 I always like someone who's smart. Down-to-earth, definitely. 319 00:15:11,327 --> 00:15:14,121 Someone who's spiritual. That's really big for me. 320 00:15:14,204 --> 00:15:18,834 Their kindness, their ability to be present. 321 00:15:18,918 --> 00:15:22,296 Adventurous, playful, good communicator... 322 00:15:22,796 --> 00:15:25,049 [narrator] And finally, we tend to find comfort 323 00:15:25,132 --> 00:15:27,885 in people who reciprocate our expressions of intimacy. 324 00:15:28,218 --> 00:15:30,596 For example, if I-- If I told you something 325 00:15:30,679 --> 00:15:33,557 about my true self, who I really, really am, 326 00:15:33,641 --> 00:15:34,934 are you going to reciprocate? 327 00:15:35,017 --> 00:15:37,019 Are you going to tell me something about yourself in return? 328 00:15:37,561 --> 00:15:39,146 [narrator] That could be why this experiment 329 00:15:39,229 --> 00:15:41,649 of asking 36 questions to a stranger 330 00:15:42,232 --> 00:15:43,776 actually worked for people. 331 00:15:43,859 --> 00:15:45,903 Sharing your most treasured memories... 332 00:15:46,403 --> 00:15:47,655 terrible memories... 333 00:15:47,738 --> 00:15:50,783 and your secret hunches about how you're going to die 334 00:15:50,866 --> 00:15:52,576 could get pretty intimate. 335 00:15:53,202 --> 00:15:57,748 So, it turns out, Cosmo's advice is surprisingly scientific. 336 00:15:57,831 --> 00:16:01,126 Focusing on the ways you're similar, mm-hmm. 337 00:16:01,210 --> 00:16:02,544 Hanging around them a lot... 338 00:16:02,628 --> 00:16:03,837 That's geography. 339 00:16:04,213 --> 00:16:05,089 Loving them... 340 00:16:05,172 --> 00:16:07,508 That's opening yourself up to reciprocity. 341 00:16:07,716 --> 00:16:11,011 And eye contact... Well, that's just really sexy. 342 00:16:15,599 --> 00:16:17,601 [theme music playing]