WEBVTT 00:00:07.290 --> 00:00:10.117 We like to think of romantic feelings as spontaneous, 00:00:10.117 --> 00:00:13.283 and indescribable things that come from the heart. 00:00:13.283 --> 00:00:15.571 But it's actually your brain running a complex 00:00:15.571 --> 00:00:18.770 series of calculations within a matter of seconds 00:00:18.770 --> 00:00:21.757 that's responsible for determining attraction. 00:00:21.757 --> 00:00:23.883 Doesn't sound quite as poetic, does it? 00:00:23.883 --> 00:00:26.393 But just because the calculations are happening in your brain 00:00:26.393 --> 00:00:30.158 doesn't mean those warm, fuzzy feelings are all in your head. 00:00:30.158 --> 00:00:32.675 In fact, all five of your senses play a role, 00:00:32.675 --> 00:00:36.805 each able to vote for, or veto, a budding attraction. 00:00:36.805 --> 00:00:39.549 The eyes are the first components in attraction. 00:00:39.549 --> 00:00:41.237 Many visual beauty standards vary 00:00:41.237 --> 00:00:43.116 between cultures and eras, 00:00:43.116 --> 00:00:45.665 and signs of youth, fertility and good health, 00:00:45.665 --> 00:00:47.482 such as long lustrous hair, 00:00:47.482 --> 00:00:49.851 or smooth, scar-free skin, 00:00:49.851 --> 00:00:51.312 are almost always in demand 00:00:51.312 --> 00:00:54.384 because they're associated with reproductive fitness. 00:00:54.384 --> 00:00:56.331 And when the eyes spot something they like, 00:00:56.331 --> 00:00:58.598 our instinct is to move closer 00:00:58.598 --> 00:01:00.943 so the other sense can investigate. 00:01:00.943 --> 00:01:02.819 The nose's contribution to romance 00:01:02.819 --> 00:01:05.612 is more than noticing perfume or cologne. 00:01:05.612 --> 00:01:08.237 It's able to pick up on natural chemicals signals 00:01:08.237 --> 00:01:09.803 known as pheromones. 00:01:09.803 --> 00:01:11.659 These not only convey important 00:01:11.659 --> 00:01:14.553 physical or genetic information about their source, 00:01:14.553 --> 00:01:16.764 but are able to activate a physiological 00:01:16.764 --> 00:01:20.054 or behavioral response in the recipient. 00:01:20.054 --> 00:01:24.196 In one study, a group of women at different points in their ovulation cycles 00:01:24.196 --> 00:01:26.525 wore the same t-shirts for three nights. 00:01:26.525 --> 00:01:29.005 After male volunteers were randomly assigned 00:01:29.005 --> 00:01:31.266 to smell either one of the worn shirts, 00:01:31.266 --> 00:01:32.997 or a new unworn one, 00:01:32.997 --> 00:01:36.765 saliva samples showed an increase in testosterone 00:01:36.765 --> 00:01:40.531 in those who had smelled a shirt worn by an ovulating woman. 00:01:40.531 --> 00:01:42.199 Such a testosterone boost 00:01:42.199 --> 00:01:44.768 may give a man the nudge to persue a woman 00:01:44.768 --> 00:01:47.028 he might not have otherwise noticed. 00:01:47.028 --> 00:01:49.183 A woman's nose is particularly attuned 00:01:49.183 --> 00:01:51.303 to MHC molecules, 00:01:51.303 --> 00:01:53.361 which are used to fight disease. 00:01:53.361 --> 00:01:55.617 In this case, opposites attract. 00:01:55.617 --> 00:01:58.148 When a study asked women to smell t-shirts 00:01:58.148 --> 00:02:00.056 that had been worn by different men, 00:02:00.056 --> 00:02:02.193 they preferred the odors of those whose 00:02:02.193 --> 00:02:05.176 MHC molecules differed from theirs. 00:02:05.176 --> 00:02:06.402 This makes sense. 00:02:06.402 --> 00:02:09.109 Genes that result in a greater variety of immunities 00:02:09.109 --> 00:02:12.507 may give offspring a major survival advantage. 00:02:12.507 --> 00:02:15.235 Our ears also determine attraction. 00:02:15.235 --> 00:02:18.660 Men prefer females with high-pitched, breathy voices, 00:02:18.660 --> 00:02:20.828 and wide formant spacing, 00:02:20.828 --> 00:02:22.864 correlated with smaller body size. 00:02:22.864 --> 00:02:25.402 While women prefer low-pitched voices 00:02:25.402 --> 00:02:27.316 with a narrow formant spacing 00:02:27.316 --> 00:02:29.565 that suggest a larger body size. 00:02:29.565 --> 00:02:31.013 And not surprisingly, 00:02:31.013 --> 00:02:33.530 touch turns out to be crucial for romance. 00:02:33.530 --> 00:02:34.921 In this experiment, 00:02:34.921 --> 00:02:37.220 not realizing the study had begun, 00:02:37.220 --> 00:02:40.998 participants were asked to briefly hold the coffee, 00:02:40.998 --> 00:02:42.746 either hot or iced. 00:02:42.746 --> 00:02:44.505 Later, the participants read a story 00:02:44.505 --> 00:02:46.274 about a hypothetical person, 00:02:46.274 --> 00:02:48.406 and were asked to rate their personality. 00:02:48.406 --> 00:02:50.843 Those who had held the hot cup of coffee 00:02:50.843 --> 00:02:53.738 perceived the person in the story as happier, 00:02:53.738 --> 00:02:57.556 more social, more generous and better natured 00:02:57.556 --> 00:03:00.270 than those who had held the cup of ice coffee, 00:03:00.270 --> 00:03:04.793 who rated the person as cold, stoic, and unaffectionate. 00:03:04.793 --> 00:03:06.583 If a potential mate has managed to pass 00:03:06.583 --> 00:03:09.378 all these tests, there's still one more: 00:03:09.378 --> 00:03:11.979 the infamous first kiss, 00:03:11.979 --> 00:03:13.976 a rich and complex exchange 00:03:13.976 --> 00:03:16.508 of tacticle and chemical cues, 00:03:16.508 --> 00:03:18.210 such as the smell of one's breath, 00:03:18.210 --> 00:03:20.234 and the taste of their mouth. 00:03:20.234 --> 00:03:22.076 This magical moment is so critical 00:03:22.076 --> 00:03:24.052 that a majority of men and women 00:03:24.052 --> 00:03:26.377 have reported losing their attraction to someone 00:03:26.377 --> 00:03:28.931 after a bad first kiss. 00:03:28.931 --> 00:03:30.318 Once attraction is confirmed, 00:03:30.318 --> 00:03:31.696 your bloodstream is flooded 00:03:31.696 --> 00:03:33.229 with norepinephrine, 00:03:33.229 --> 00:03:35.541 activating your fight or flight system. 00:03:35.541 --> 00:03:37.163 Your heart beats faster, 00:03:37.163 --> 00:03:38.533 your pupils dialate, 00:03:38.533 --> 00:03:41.647 and your body releases glucose for additional energy, 00:03:41.647 --> 00:03:43.084 not because you're in danger, 00:03:43.084 --> 00:03:44.608 but because your body is telling you 00:03:44.608 --> 00:03:46.308 that something important is happening. 00:03:46.318 --> 00:03:47.828 To help you focus, 00:03:47.828 --> 00:03:50.330 norepinephrine creates a sort of tunnel-vision, 00:03:50.330 --> 00:03:52.625 blocking out surrounding distractions, 00:03:52.625 --> 00:03:55.047 possibly even warping your sense of time, 00:03:55.047 --> 00:03:57.338 and enhancing your memory. 00:03:57.338 --> 00:04:01.139 This might explain why people never forget their first kiss. 00:04:01.139 --> 00:04:03.058 The idea of so much of our attraction 00:04:03.058 --> 00:04:06.323 being influenced by chemicals and evolutionary biology 00:04:06.323 --> 00:04:09.287 may seem cold and scientific rather than romantic, 00:04:09.287 --> 00:04:11.323 but the next time you see someone you like 00:04:11.323 --> 00:04:15.344 try to appreciate how your entire body is playing matchmaker 00:04:15.344 --> 00:04:18.700 to decide if that beautiful stranger is right for you.