1 00:00:15,966 --> 00:00:18,401 Why does shape matter? 2 00:00:18,401 --> 00:00:21,671 I told you shape mattered in the very beginning, 3 00:00:21,671 --> 00:00:25,041 but why does it matter? 4 00:00:25,041 --> 00:00:28,445 Isn't it just important to know what the chemistry is 5 00:00:28,445 --> 00:00:29,512 and not the actual shape? 6 00:00:29,512 --> 00:00:30,547 Why does the shape matter? 7 00:00:30,547 --> 00:00:31,915 And so I thought I would give you 8 00:00:31,915 --> 00:00:35,719 an example of that with smell. 9 00:00:35,719 --> 00:00:38,888 And yeah, right? 10 00:00:38,888 --> 00:00:39,689 Exactly. 11 00:00:39,689 --> 00:00:42,392 And actually, I think we should do this more often. 12 00:00:42,392 --> 00:00:44,094 You know, I feel like this is inspiring. 13 00:00:44,094 --> 00:00:47,030 We talk about stopping and smelling the flowers, 14 00:00:47,030 --> 00:00:48,999 but do we actually do it? 15 00:00:48,999 --> 00:00:49,699 And look at that. 16 00:00:49,699 --> 00:00:52,202 They've got one arm around the other. 17 00:00:52,202 --> 00:00:53,970 This is a moment. 18 00:00:53,970 --> 00:00:57,340 You can't share this moment on Instagram. 19 00:00:57,340 --> 00:00:58,975 You have to put your phone down and be 20 00:00:58,975 --> 00:01:01,511 there to have this moment. 21 00:01:01,511 --> 00:01:05,849 And I highly encourage you to be inspired by this. 22 00:01:05,849 --> 00:01:08,885 Now, smell and taste are actually related. 23 00:01:08,885 --> 00:01:12,622 And smell is, you know, it's actually a fascinating thing. 24 00:01:12,622 --> 00:01:18,395 We can smell about 10,000 different smells. 25 00:01:18,395 --> 00:01:19,662 It's remarkable. 26 00:01:19,662 --> 00:01:24,033 A dog can smell between 10 and 100,000 times more. 27 00:01:24,033 --> 00:01:27,404 Right, so if you do the analogy that people do with vision, 28 00:01:27,404 --> 00:01:28,605 we can see a third of a mile. 29 00:01:28,605 --> 00:01:31,007 A dog can see about 3,000 miles. 30 00:01:31,007 --> 00:01:35,045 Right, that's pretty cool. 31 00:01:35,045 --> 00:01:36,913 But the question is why do we smell? 32 00:01:36,913 --> 00:01:38,281 How do we smell? 33 00:01:38,281 --> 00:01:39,783 How do we taste? 34 00:01:39,783 --> 00:01:42,619 And it turns out that the way that we distinguish 35 00:01:42,619 --> 00:01:45,121 from one smell and one taste and another 36 00:01:45,121 --> 00:01:47,289 has to do with the shape of the molecule. 37 00:01:47,289 --> 00:01:50,759 And so just like a key right, with a key, 38 00:01:50,759 --> 00:01:52,295 it's all of the same material. 39 00:01:52,295 --> 00:01:53,763 It's the same chemistry in the key. 40 00:01:53,763 --> 00:01:56,633 But the shape is different that can unlock the door or not. 41 00:01:56,633 --> 00:01:59,335 That is literally how our receptor cells 42 00:01:59,335 --> 00:02:02,172 work for taste and smell. 43 00:02:02,172 --> 00:02:04,074 This is a cartoon I found that I kind of like. 44 00:02:04,074 --> 00:02:08,912 See, OK, shapes, circles, squares, right. 45 00:02:08,912 --> 00:02:13,616 OK, and some shapes come in, and they make happiness, happiness, 46 00:02:13,616 --> 00:02:15,051 flowers and stuff. 47 00:02:15,051 --> 00:02:15,618 I don't know. 48 00:02:15,618 --> 00:02:16,386 Is cheese happy? 49 00:02:16,386 --> 00:02:17,587 It looks neutral. 50 00:02:17,587 --> 00:02:19,289 I would get happy with cheese. 51 00:02:19,289 --> 00:02:21,391 But anyway, fish for some reason, 52 00:02:21,391 --> 00:02:23,026 but you know, it depends. 53 00:02:23,026 --> 00:02:24,160 But it's shape dependent. 54 00:02:24,160 --> 00:02:26,029 Now the thing is, taste works that way, too. 55 00:02:26,029 --> 00:02:29,432 So this is what's happening in your tongue. 56 00:02:29,432 --> 00:02:31,734 You've got these taste buds. 57 00:02:31,734 --> 00:02:34,671 We've all heard the word taste bud, right? 58 00:02:34,671 --> 00:02:37,240 But what is really going on? 59 00:02:37,240 --> 00:02:41,177 What is really going on is a combination of chemistry 60 00:02:41,177 --> 00:02:44,347 and shape recognition. 61 00:02:44,347 --> 00:02:46,382 So the taste bud, if you look at the taste bud, 62 00:02:46,382 --> 00:02:50,019 that's inside of the little pores inside your tongue. 63 00:02:50,019 --> 00:02:51,187 There's a blow up of it. 64 00:02:51,187 --> 00:02:53,323 And so this is what the surface of your tongue looks like. 65 00:02:53,323 --> 00:02:54,491 And there's a little pore. 66 00:02:54,491 --> 00:02:56,091 And there's little filters in there 67 00:02:56,091 --> 00:02:58,595 that helps certain molecules kind of get in there. 68 00:02:58,595 --> 00:03:00,997 And what happens when they get in there. 69 00:03:00,997 --> 00:03:04,267 Well, what happens is you've got these taste receptor cells that 70 00:03:04,267 --> 00:03:06,002 are like lock key pairs. 71 00:03:06,002 --> 00:03:09,172 They actually only look at like the circle or the diamond, 72 00:03:09,172 --> 00:03:11,674 and they can tell you which one is which. 73 00:03:11,674 --> 00:03:15,612 And that's a major part of how we distinguish from one shape 74 00:03:15,612 --> 00:03:19,149 to another, and it's actually so-- 75 00:03:19,149 --> 00:03:21,584 it goes back a long way. 76 00:03:21,584 --> 00:03:22,385 Why? 77 00:03:22,385 --> 00:03:28,391 Because shape and smell are literally survival. 78 00:03:28,391 --> 00:03:29,959 They are literally like you can-- 79 00:03:29,959 --> 00:03:35,832 if you taste something, and it tastes poisonous, don't eat it. 80 00:03:35,832 --> 00:03:37,033 You live. 81 00:03:37,033 --> 00:03:38,567 Right? 82 00:03:38,567 --> 00:03:42,338 So it is a very emotional thing to smell and taste, 83 00:03:42,338 --> 00:03:45,909 because it is actually coupled to your very survival. 84 00:03:45,909 --> 00:03:50,113 And Democritus himself, Democritus, 85 00:03:50,113 --> 00:03:54,684 our friend Democritus, said that shape must be involved. 86 00:03:54,684 --> 00:03:57,420 He thought that because things that taste bitter 87 00:03:57,420 --> 00:04:01,524 are sharp that the bitter molecules were sharp. 88 00:04:01,524 --> 00:04:05,328 They must have sharpness to them, like shards of glass. 89 00:04:05,328 --> 00:04:06,296 That's how he imagined. 90 00:04:06,296 --> 00:04:08,097 And the sweet molecules were sort 91 00:04:08,097 --> 00:04:11,668 of the soft, fluffy spheres. 92 00:04:11,668 --> 00:04:14,837 That's not that far off from being sort 93 00:04:14,837 --> 00:04:19,409 of what happens a little bit. 94 00:04:19,409 --> 00:04:23,646 But when we look at it like, you know, glucose and quinine, 95 00:04:23,646 --> 00:04:27,417 we say, OK, those are very different chemistries. 96 00:04:27,417 --> 00:04:30,687 So it might not be as obvious why one of them 97 00:04:30,687 --> 00:04:33,022 taste so different than the other. 98 00:04:33,022 --> 00:04:35,358 But check out this example. 99 00:04:35,358 --> 00:04:38,394 This is the same molecule, the carvone molecule 100 00:04:38,394 --> 00:04:40,163 that is called an enantiomer, which 101 00:04:40,163 --> 00:04:42,298 means that it has handedness. 102 00:04:42,298 --> 00:04:44,834 It's the exact same chemical formula 103 00:04:44,834 --> 00:04:48,004 and the exact same structure, except for one is like this, 104 00:04:48,004 --> 00:04:49,839 and one is like that. 105 00:04:49,839 --> 00:04:51,407 That's handedness. 106 00:04:51,407 --> 00:04:52,175 Right. 107 00:04:52,175 --> 00:04:55,945 And that difference makes one of them 108 00:04:55,945 --> 00:04:58,481 taste and smell like spearmint and the other like caraway 109 00:04:58,481 --> 00:04:59,949 seeds, right? 110 00:04:59,949 --> 00:05:02,518 It's incredible. 111 00:05:02,518 --> 00:05:04,320 It means that in our tongues in our noses 112 00:05:04,320 --> 00:05:09,559 we must have chiral, the ability to determine the chirality. 113 00:05:09,559 --> 00:05:10,827 It's pretty cool. 114 00:05:10,827 --> 00:05:11,327 Right. 115 00:05:11,327 --> 00:05:14,330 So shape is critical, and this is one example of why. 116 00:05:14,330 --> 00:05:15,431 This is one example of why. 117 00:05:15,431 --> 00:05:15,932 OK.