1 00:00:07,290 --> 00:00:10,117 We like to think of romantic feelings as spontaneous, 2 00:00:10,117 --> 00:00:13,283 and indescribable things that come from the heart. 3 00:00:13,283 --> 00:00:15,571 But it's actually your brain running a complex 4 00:00:15,571 --> 00:00:18,770 series of calculations within a matter of seconds 5 00:00:18,770 --> 00:00:21,757 that's responsible for determining attraction. 6 00:00:21,757 --> 00:00:23,883 Doesn't sound quite as poetic, does it? 7 00:00:23,883 --> 00:00:26,393 But just because the calculations are happening in your brain 8 00:00:26,393 --> 00:00:30,158 doesn't mean those warm, fuzzy feelings are all in your head. 9 00:00:30,158 --> 00:00:32,675 In fact, all five of your senses play a role, 10 00:00:32,675 --> 00:00:36,805 each able to vote for, or veto, a budding attraction. 11 00:00:36,805 --> 00:00:39,549 The eyes are the first components in attraction. 12 00:00:39,549 --> 00:00:41,237 Many visual beauty standards vary 13 00:00:41,237 --> 00:00:43,116 between cultures and eras, 14 00:00:43,116 --> 00:00:45,665 and signs of youth, fertility and good health, 15 00:00:45,665 --> 00:00:47,482 such as long lustrous hair, 16 00:00:47,482 --> 00:00:49,851 or smooth, scar-free skin, 17 00:00:49,851 --> 00:00:51,312 are almost always in demand 18 00:00:51,312 --> 00:00:54,384 because they're associated with reproductive fitness. 19 00:00:54,384 --> 00:00:56,331 And when the eyes spot something they like, 20 00:00:56,331 --> 00:00:58,598 our instinct is to move closer 21 00:00:58,598 --> 00:01:00,943 so the other sense can investigate. 22 00:01:00,943 --> 00:01:02,819 The nose's contribution to romance 23 00:01:02,819 --> 00:01:05,612 is more than noticing perfume or cologne. 24 00:01:05,612 --> 00:01:08,237 It's able to pick up on natural chemicals signals 25 00:01:08,237 --> 00:01:09,803 known as pheromones. 26 00:01:09,803 --> 00:01:11,659 These not only convey important 27 00:01:11,659 --> 00:01:14,553 physical or genetic information about their source, 28 00:01:14,553 --> 00:01:16,764 but are able to activate a physiological 29 00:01:16,764 --> 00:01:20,054 or behavioral response in the recipient. 30 00:01:20,054 --> 00:01:24,196 In one study, a group of women at different points in their ovulation cycles 31 00:01:24,196 --> 00:01:26,525 wore the same t-shirts for three nights. 32 00:01:26,525 --> 00:01:29,005 After male volunteers were randomly assigned 33 00:01:29,005 --> 00:01:31,266 to smell either one of the worn shirts, 34 00:01:31,266 --> 00:01:32,997 or a new unworn one, 35 00:01:32,997 --> 00:01:36,765 saliva samples showed an increase in testosterone 36 00:01:36,765 --> 00:01:40,531 in those who had smelled a shirt worn by an ovulating woman. 37 00:01:40,531 --> 00:01:42,199 Such a testosterone boost 38 00:01:42,199 --> 00:01:44,768 may give a man the nudge to persue a woman 39 00:01:44,768 --> 00:01:47,028 he might not have otherwise noticed. 40 00:01:47,028 --> 00:01:49,183 A woman's nose is particularly attuned 41 00:01:49,183 --> 00:01:51,303 to MHC molecules, 42 00:01:51,303 --> 00:01:53,361 which are used to fight disease. 43 00:01:53,361 --> 00:01:55,617 In this case, opposites attract. 44 00:01:55,617 --> 00:01:58,148 When a study asked women to smell t-shirts 45 00:01:58,148 --> 00:02:00,056 that had been worn by different men, 46 00:02:00,056 --> 00:02:02,193 they preferred the odors of those whose 47 00:02:02,193 --> 00:02:05,176 MHC molecules differed from theirs. 48 00:02:05,176 --> 00:02:06,402 This makes sense. 49 00:02:06,402 --> 00:02:09,109 Genes that result in a greater variety of immunities 50 00:02:09,109 --> 00:02:12,507 may give offspring a major survival advantage. 51 00:02:12,507 --> 00:02:15,235 Our ears also determine attraction. 52 00:02:15,235 --> 00:02:18,660 Men prefer females with high-pitched, breathy voices, 53 00:02:18,660 --> 00:02:20,828 and wide formant spacing, 54 00:02:20,828 --> 00:02:22,864 correlated with smaller body size. 55 00:02:22,864 --> 00:02:25,402 While women prefer low-pitched voices 56 00:02:25,402 --> 00:02:27,316 with a narrow formant spacing 57 00:02:27,316 --> 00:02:29,565 that suggest a larger body size. 58 00:02:29,565 --> 00:02:31,013 And not surprisingly, 59 00:02:31,013 --> 00:02:33,530 touch turns out to be crucial for romance. 60 00:02:33,530 --> 00:02:34,921 In this experiment, 61 00:02:34,921 --> 00:02:37,220 not realizing the study had begun, 62 00:02:37,220 --> 00:02:40,998 participants were asked to briefly hold the coffee, 63 00:02:40,998 --> 00:02:42,746 either hot or iced. 64 00:02:42,746 --> 00:02:44,505 Later, the participants read a story 65 00:02:44,505 --> 00:02:46,274 about a hypothetical person, 66 00:02:46,274 --> 00:02:48,406 and were asked to rate their personality. 67 00:02:48,406 --> 00:02:50,843 Those who had held the hot cup of coffee 68 00:02:50,843 --> 00:02:53,738 perceived the person in the story as happier, 69 00:02:53,738 --> 00:02:57,556 more social, more generous and better natured 70 00:02:57,556 --> 00:03:00,270 than those who had held the cup of ice coffee, 71 00:03:00,270 --> 00:03:04,793 who rated the person as cold, stoic, and unaffectionate. 72 00:03:04,793 --> 00:03:06,583 If a potential mate has managed to pass 73 00:03:06,583 --> 00:03:09,378 all these tests, there's still one more: 74 00:03:09,378 --> 00:03:11,979 the infamous first kiss, 75 00:03:11,979 --> 00:03:13,976 a rich and complex exchange 76 00:03:13,976 --> 00:03:16,508 of tacticle and chemical cues, 77 00:03:16,508 --> 00:03:18,210 such as the smell of one's breath, 78 00:03:18,210 --> 00:03:20,234 and the taste of their mouth. 79 00:03:20,234 --> 00:03:22,076 This magical moment is so critical 80 00:03:22,076 --> 00:03:24,052 that a majority of men and women 81 00:03:24,052 --> 00:03:26,377 have reported losing their attraction to someone 82 00:03:26,377 --> 00:03:28,931 after a bad first kiss. 83 00:03:28,931 --> 00:03:30,318 Once attraction is confirmed, 84 00:03:30,318 --> 00:03:31,696 your bloodstream is flooded 85 00:03:31,696 --> 00:03:33,229 with norepinephrine, 86 00:03:33,229 --> 00:03:35,541 activating your fight or flight system. 87 00:03:35,541 --> 00:03:37,163 Your heart beats faster, 88 00:03:37,163 --> 00:03:38,533 your pupils dialate, 89 00:03:38,533 --> 00:03:41,647 and your body releases glucose for additional energy, 90 00:03:41,647 --> 00:03:43,084 not because you're in danger, 91 00:03:43,084 --> 00:03:44,608 but because your body is telling you 92 00:03:44,608 --> 00:03:46,308 that something important is happening. 93 00:03:46,318 --> 00:03:47,828 To help you focus, 94 00:03:47,828 --> 00:03:50,330 norepinephrine creates a sort of tunnel-vision, 95 00:03:50,330 --> 00:03:52,625 blocking out surrounding distractions, 96 00:03:52,625 --> 00:03:55,047 possibly even warping your sense of time, 97 00:03:55,047 --> 00:03:57,338 and enhancing your memory. 98 00:03:57,338 --> 00:04:01,139 This might explain why people never forget their first kiss. 99 00:04:01,139 --> 00:04:03,058 The idea of so much of our attraction 100 00:04:03,058 --> 00:04:06,323 being influenced by chemicals and evolutionary biology 101 00:04:06,323 --> 00:04:09,287 may seem cold and scientific rather than romantic, 102 00:04:09,287 --> 00:04:11,323 but the next time you see someone you like 103 00:04:11,323 --> 00:04:15,344 try to appreciate how your entire body is playing matchmaker 104 00:04:15,344 --> 00:04:18,700 to decide if that beautiful stranger is right for you.