WEBVTT - Ep29 "What does it mean to know thyself?" Part 1 0:00:05.120 --> 0:00:06.000 In this episode. 0:00:06.000 --> 0:00:08.920 In the next one, I want to dive into a 0:00:09.119 --> 0:00:13.880 fundamental philosophical question, probably the most important one that we 0:00:14.040 --> 0:00:18.840 have as humans, which is what it means to know ourselves? 0:00:19.400 --> 0:00:22.600 In other words, as people living in the twenty first century, 0:00:23.079 --> 0:00:27.200 with all of this massive biological data and the insights, 0:00:27.800 --> 0:00:31.160 what does that tell us about the ancient question of 0:00:31.760 --> 0:00:35.120 who we are? Do we have something like souls? Are 0:00:35.159 --> 0:00:38.040 we just a bunch of neurons? Are there other ways 0:00:38.080 --> 0:00:41.880 to look at this? There's a sense in which I'm 0:00:42.040 --> 0:00:46.880 constantly surprised that this question who am I? Isn't talked 0:00:46.880 --> 0:00:50.040 about all the time. I mean, most people spend most 0:00:50.080 --> 0:00:54.800 of their time talking about sports teams or the latest celebrity, 0:00:54.920 --> 0:00:58.120 or traffic or whatever food they like or whatever. 0:00:58.600 --> 0:01:00.240 But we find ourselves. 0:00:59.840 --> 0:01:05.240 Here in this mysterious existence where you don't really remember 0:01:05.319 --> 0:01:08.839 getting here, and you're told that one day you'll disappear 0:01:08.880 --> 0:01:12.600 from here. And it surprises me that this isn't what 0:01:12.640 --> 0:01:16.600 we're talking about all the time. Why isn't this what 0:01:16.680 --> 0:01:20.160 we're using the internet to discuss. Why don't we have 0:01:20.600 --> 0:01:25.399 world leaders coming together not for the United Nations Annual Meeting, 0:01:25.760 --> 0:01:28.920 but to dig their teeth into this question and bring 0:01:28.959 --> 0:01:33.560 evidence to bear on different hypotheses. Why isn't this the 0:01:33.640 --> 0:01:38.360 topic of conversation on every single news program? So for 0:01:38.400 --> 0:01:41.600 the next two episodes, we're going to dig in and 0:01:41.640 --> 0:01:43.960 I always start with some questions to give you a 0:01:44.000 --> 0:01:46.040 sense of the weirdness of the roadmap. 0:01:46.160 --> 0:01:46.800 So here we go. 0:01:47.319 --> 0:01:51.160 Would you appreciate Taylor Swift if you only had an 0:01:51.280 --> 0:01:55.400 internal camera to watch her vocal cords jumping around? What 0:01:55.440 --> 0:01:59.680 do almost all drugs of abuse have in common? How 0:01:59.720 --> 0:02:04.600 can the tiny molecules of the rabies virus control your behavior? 0:02:05.360 --> 0:02:07.600 Did Joan of arc turn the tide of the one 0:02:07.680 --> 0:02:11.240 hundred Years War as the result of a brain disorder? 0:02:11.840 --> 0:02:14.280 And what does any of this have to do with 0:02:14.440 --> 0:02:18.359 who you are? And the question of your essence as 0:02:18.360 --> 0:02:21.880 a person, the essence that your friends know and love 0:02:22.160 --> 0:02:22.680 as you? 0:02:23.440 --> 0:02:29.960 Where does that come from? Welcome to Inner. 0:02:29.760 --> 0:02:33.680 Cosmos with me David Eagleman. I'm a neuroscientist and an 0:02:33.680 --> 0:02:36.919 author at Stanford and in the next couple of episodes, 0:02:36.960 --> 0:02:40.600 we're going to sail deeply into our three pound universe 0:02:40.960 --> 0:02:44.080 to dig in to one of the most fundamental questions 0:02:44.120 --> 0:02:53.640 of our experience in the world. Now I've talked about 0:02:53.680 --> 0:02:56.400 this fact before, but I need to emphasize for this 0:02:56.560 --> 0:03:00.600 episode that the brain is the most complex structure we 0:03:00.680 --> 0:03:04.760 have ever discovered in our universe. It's got almost one 0:03:04.880 --> 0:03:11.519 hundred billion neurons and hundreds of trillions of connections. Now, 0:03:11.560 --> 0:03:16.640 this kind of complexity is simply not understandable by a 0:03:16.800 --> 0:03:20.600 human mind. And yet we know that somehow your brain 0:03:21.000 --> 0:03:25.320 is you. All of your hopes and dreams and aspirations, 0:03:25.639 --> 0:03:29.800 the agony, the ecstasy, it's all contained in that three 0:03:29.919 --> 0:03:33.120 pound organ in your skull. Now how do we know 0:03:33.200 --> 0:03:36.400 that because every day in clinics all over the world, 0:03:36.680 --> 0:03:40.200 we see people with damage to their brains, even very 0:03:40.320 --> 0:03:45.800 tiny damage, and that changes who they are. Small bits 0:03:45.800 --> 0:03:49.920 of damage caused by a stroke or a traumatic brain injury, 0:03:50.160 --> 0:03:55.080 or a tumor or whatever. These can change your decision 0:03:55.120 --> 0:03:59.920 making or your ability to see colors, or understand music 0:04:00.440 --> 0:04:04.240 or name animals. It can make you more or less 0:04:04.280 --> 0:04:09.640 prone to gambling, or more talkative or less talkative. It 0:04:09.680 --> 0:04:12.880 can make you not know the names of objects or 0:04:12.960 --> 0:04:16.560 not know how to interact with objects anymore, or make 0:04:16.600 --> 0:04:20.320 you unable to speak or to understand speech, or one 0:04:20.440 --> 0:04:23.640 hundred other things. And this is how we came to 0:04:23.680 --> 0:04:31.360 have this strange hypothesis that you are your brain. So 0:04:31.480 --> 0:04:34.320 to start this question of who are we, let's step 0:04:34.360 --> 0:04:37.040 back a little bit. In history, people have always been 0:04:37.080 --> 0:04:41.600 wondering who we are, mostly because our existence is so 0:04:41.920 --> 0:04:47.080 deeply weird, and traditionally the answer has been about deities 0:04:47.160 --> 0:04:51.360 and immortal souls, but not everyone has been willing to 0:04:51.400 --> 0:04:54.400 stop there. So I was impressed some years ago when 0:04:54.440 --> 0:04:58.440 I read about the French essayist Montaigne, who in fifteen 0:04:58.520 --> 0:05:01.480 seventy one, on the morning of his thirty eighth birthday, 0:05:02.120 --> 0:05:06.160 decided to make a radical change in his life's trajectory. 0:05:06.640 --> 0:05:09.800 He quit his career in public life, and he set 0:05:09.880 --> 0:05:13.680 up a library with one thousand books in a tower 0:05:14.040 --> 0:05:16.400 at the back of his large estate, and he spent 0:05:16.480 --> 0:05:20.160 the rest of his life writing essays about the subject 0:05:20.520 --> 0:05:25.880 that interested him the most, the search for oneself. His 0:05:25.920 --> 0:05:28.960 first conclusion was that the search to no one's self 0:05:29.160 --> 0:05:33.120 is a fool's errand because the self who I am, 0:05:33.640 --> 0:05:37.240 is always changing and staying a few steps ahead of 0:05:37.279 --> 0:05:41.440 a firm description. But that didn't stop him from searching, 0:05:41.960 --> 0:05:45.920 and his question has resonated through the centuries. 0:05:46.520 --> 0:05:48.599 Causasia, what do. I know. 0:05:49.720 --> 0:05:52.919 That was a good question, and it remains so because 0:05:52.960 --> 0:05:57.000 when we dive in to explore the inner cosmos, as 0:05:57.040 --> 0:06:00.479 we've been doing on this podcast, we can't help find 0:06:00.480 --> 0:06:06.000 ourselves disabused of our initial notions that knowing ourselves will 0:06:06.040 --> 0:06:10.719 be uncomplicated and intuitive, because we see that self knowledge 0:06:11.080 --> 0:06:14.800 requires as much work from the outside in the form 0:06:14.839 --> 0:06:18.000 of science as from the inside introspection. 0:06:18.880 --> 0:06:19.479 And this is not to. 0:06:19.520 --> 0:06:23.560 Say that we can't grow better at introspection. After all, 0:06:23.600 --> 0:06:26.279 we can learn how to pay attention to what we're 0:06:26.320 --> 0:06:29.880 really seeing out there, like painters do, and we can 0:06:30.200 --> 0:06:34.680 attend more closely to our internal signals like Yogi's do. 0:06:35.520 --> 0:06:40.360 But there are limits to introspection. Just consider the fact 0:06:40.400 --> 0:06:45.479 that your peripheral nervous system employs one hundred million neurons 0:06:45.560 --> 0:06:48.880 to control the activities in your gut. This is called 0:06:48.920 --> 0:06:53.479 the enteric nervous system one hundred million neurons, and no 0:06:53.760 --> 0:06:58.320 amount of your introspection can touch this, nor by the way, 0:06:58.360 --> 0:07:00.679 would you want it to be. In The tek nervous 0:07:00.720 --> 0:07:05.760 system is better off running as the automated optimized machinery 0:07:05.800 --> 0:07:09.320 that it is, routing food along your gut and providing 0:07:09.400 --> 0:07:14.440 chemical signals to control the digestion factory without asking your 0:07:14.600 --> 0:07:17.960 opinion on the matter. Now, this has always fascinated me 0:07:18.040 --> 0:07:20.640 to think that in some cases there may be not 0:07:20.760 --> 0:07:25.280 only a lack of access, but even an active prevention 0:07:25.520 --> 0:07:28.760 of access. For example, I was once chewing on this 0:07:28.880 --> 0:07:32.640 with my thesis advisor, Read Montague, and he speculated that 0:07:32.680 --> 0:07:37.880 we might have algorithms that protect us from ourselves. This 0:07:37.920 --> 0:07:42.000 is analogous to your laptop computer, which has a boot 0:07:42.120 --> 0:07:46.600 sector that's inaccessible by the operating system, because the boot 0:07:46.680 --> 0:07:50.160 sector is too important for the operation of the computer 0:07:50.680 --> 0:07:54.400 for any high level systems to find inroads and gain 0:07:54.560 --> 0:07:56.520 admission under any circumstances. 0:07:57.200 --> 0:07:59.160 So Read noted. 0:07:58.800 --> 0:08:01.559 That whenever we try to think about ourselves too much, 0:08:01.640 --> 0:08:04.960 we tend to blink out, and the analogy was that 0:08:05.000 --> 0:08:07.600 we're getting too close to the boot sector. Now, he 0:08:07.680 --> 0:08:10.640 was just speculating here, but the idea is fascinating that 0:08:10.720 --> 0:08:15.320 maybe our system has evolved to make certain that we 0:08:15.600 --> 0:08:20.080 can't access the details too deeply. Or, as Ralph Waldo 0:08:20.120 --> 0:08:23.080 Emerson put the same idea from a more poetic point 0:08:23.080 --> 0:08:29.560 of view, everything intercepts us from ourselves. So whether it's 0:08:29.600 --> 0:08:33.200 just a lack of access or an active prevention of access. 0:08:33.480 --> 0:08:36.600 The bottom line is that much of who we are 0:08:37.200 --> 0:08:41.400 remains outside of our conscious control, or our opinion or 0:08:41.440 --> 0:08:45.960 our choice. We talked in an earlier episode about the 0:08:46.120 --> 0:08:51.640 impossibility of changing your sense of beauty or attraction. What 0:08:51.679 --> 0:08:55.400 would happen if someone commanded you to be attracted to 0:08:55.480 --> 0:08:58.360 someone that you're not, or to be attracted to a 0:08:58.559 --> 0:09:01.559 gender that you're not attracted to, or to an animal 0:09:01.600 --> 0:09:02.840 outside your species. 0:09:03.120 --> 0:09:06.120 Could you muster attraction there? Doubtful. 0:09:06.559 --> 0:09:11.000 Your most fundamental drives are stitched into the fabric of 0:09:11.040 --> 0:09:14.880 your neural circuitry, and they are inaccessible to you. You 0:09:14.960 --> 0:09:18.559 can't reach in there and change them around. You find 0:09:18.559 --> 0:09:22.640 certain things more attractive than others, and you don't know why. So, 0:09:23.000 --> 0:09:25.640 like your nervous system in your gut and your sense 0:09:25.679 --> 0:09:31.120 of attraction, almost the entirety of your inner universe is 0:09:31.240 --> 0:09:35.280 foreign to you. Consider when an idea strikes you, you 0:09:35.360 --> 0:09:37.640 don't know where the heck that came from. One minute 0:09:37.679 --> 0:09:40.120 you didn't have it, and the next moment it's there. 0:09:40.480 --> 0:09:43.679 It just appears even though it came from your brain, 0:09:43.800 --> 0:09:46.360 it may as well have been handed to you from 0:09:46.400 --> 0:09:50.400 somewhere else. You don't know the neuronal history of the idea, 0:09:50.840 --> 0:09:52.800 and you don't care. You just think, oh, that's a 0:09:52.800 --> 0:09:56.000 good idea. And this is the same with your train 0:09:56.160 --> 0:10:00.440 of thought during a day dream, or the bizarre content 0:10:00.520 --> 0:10:04.520 of your nighttime dreams. All these are just served up 0:10:04.600 --> 0:10:10.839 to you from unseen intracranial caverns. So what does all 0:10:10.880 --> 0:10:15.679 of this mean for the Greek admonition to know thyself? 0:10:16.360 --> 0:10:19.880 These were the words inscribed in the Temple of Apollo 0:10:19.960 --> 0:10:24.720 at Delphi, know thyself? Can we ever know ourselves more 0:10:24.800 --> 0:10:30.120 deeply by studying our neurobiology? And I'm going to argue yes, 0:10:30.640 --> 0:10:34.200 but with some interesting nuances, And I'll give you an 0:10:34.280 --> 0:10:38.520 analogy here to physics. In the face of the deep 0:10:38.640 --> 0:10:44.040 mysteries presented by quantum physics, the physicist Neils Brer suggested 0:10:44.400 --> 0:10:48.200 that an understanding of the structure of the atom could 0:10:48.200 --> 0:10:54.160 be accomplished only by changing the definition of to understand, 0:10:54.880 --> 0:10:59.200 because with quantum mechanics you couldn't any longer draw pictures 0:10:59.200 --> 0:11:02.559 of an atom, so that was lost. But instead one 0:11:02.600 --> 0:11:06.600 could now predict experiments about an atom's behavior out to 0:11:06.640 --> 0:11:12.680 fourteen decimal places, So lost assumptions were replaced by something richer. 0:11:13.520 --> 0:11:17.439 And by the same token, to know one's self may 0:11:17.520 --> 0:11:23.000 require a change of definition of to know. Knowing yourself 0:11:23.320 --> 0:11:28.199 now requires the understanding that the conscious you occupies only 0:11:28.240 --> 0:11:31.040 a small room in the mansion of the brain, and 0:11:31.120 --> 0:11:34.080 that it has very little control over the reality that 0:11:34.120 --> 0:11:38.599 gets constructed for you. So the invocation to know thyself 0:11:38.679 --> 0:11:43.280 needs to be considered in new ways because when we 0:11:43.320 --> 0:11:46.679 look at the trillions of neurons and there are sex 0:11:46.800 --> 0:11:51.840 tillions of proteins and biochemicals, what does it mean to 0:11:52.000 --> 0:12:14.240 know ourselves from that totally unfamiliar perspective, As we're going 0:12:14.280 --> 0:12:19.040 to see, we need the neurobiological data and we also 0:12:19.120 --> 0:12:23.400 need quite a bit more to know ourselves. Why because 0:12:23.440 --> 0:12:27.800 the biological data is fundamental, but it has its limitations. 0:12:28.720 --> 0:12:32.360 Imagine that you got Taylor Swift to come to your 0:12:32.360 --> 0:12:35.679 house and sing for you, but instead of listening to her, 0:12:36.080 --> 0:12:39.720 you put on ear muffs and you lower a medical 0:12:39.800 --> 0:12:41.640 scope down her throat and you get. 0:12:41.520 --> 0:12:44.880 A good close up view of her vocal chords. 0:12:44.960 --> 0:12:48.840 They're slimy and shiny, and they're contracting in and out 0:12:48.880 --> 0:12:52.280 and spasms. Now, you could watch this and study the 0:12:52.320 --> 0:12:55.720 details all day, but it wouldn't get you any closer 0:12:55.760 --> 0:13:00.080 to understanding why her songs are big hits, or what 0:13:00.120 --> 0:13:02.720 the words mean to you, or how they make you feel. 0:13:03.440 --> 0:13:07.320 By itself, in its raw form, the biology is only 0:13:07.360 --> 0:13:10.920 going to give you partial insight there. It's the best 0:13:10.920 --> 0:13:13.520 that we can do for now, but it's far from complete. 0:13:13.559 --> 0:13:15.600 So this is what we're going to talk about today. 0:13:15.960 --> 0:13:20.120 What does and doesn't it mean to be constructed out 0:13:20.120 --> 0:13:24.120 of physical parts. So let's start with a clear and 0:13:24.240 --> 0:13:27.680 famous example of brain damage. I've mentioned this story in 0:13:27.720 --> 0:13:31.120 a previous episode, but i'll retell it here with more detail. 0:13:31.920 --> 0:13:35.439 In eighteen forty eight, there was a work gang foreman 0:13:35.600 --> 0:13:38.960 twenty five years old. His name was Phineas Gage. On 0:13:39.120 --> 0:13:42.760 September twenty first of that year, the Boston Post wrote 0:13:42.760 --> 0:13:47.160 a short article under the headline horrible accident. Here's how 0:13:47.160 --> 0:13:50.839 it went. Quote as Phineas P. Gage, a foreman on 0:13:50.880 --> 0:13:55.599 the railroad in Cavendish, was yesterday engaged in tamping. 0:13:55.160 --> 0:13:56.080 For a blast. 0:13:56.640 --> 0:14:01.360 The powder exploded, carrying an instrument and threw his head 0:14:01.920 --> 0:14:05.400 an inch and a fourth in diameter and three feet 0:14:05.440 --> 0:14:07.720 and seven inches in length, which he was using at 0:14:07.760 --> 0:14:11.440 the time. The iron entered on the side of his face, 0:14:11.840 --> 0:14:15.559 shattering the upper jaw and passing back of the left 0:14:15.600 --> 0:14:18.079 eye and out at the top of the head. 0:14:19.080 --> 0:14:21.680 So this was an iron tamping rod, and. 0:14:21.600 --> 0:14:24.920 Because of an explosion of gunpowder, this blew through his 0:14:25.040 --> 0:14:29.760 head and it clattered to the ground twenty five yards away. Now, 0:14:30.080 --> 0:14:33.200 while Phineas Gage wasn't the first person to have his 0:14:33.400 --> 0:14:37.640 skull punctured and a portion of his brain spirited away 0:14:37.720 --> 0:14:40.600 by a projectile, he was the first, so far as 0:14:40.640 --> 0:14:44.120 we know, to not die from it. And in fact, 0:14:44.400 --> 0:14:48.800 Gauge didn't even lose consciousness. So the first physician to 0:14:49.000 --> 0:14:53.080 arrive at the scene, a doctor Williams, didn't believe Gauge's 0:14:53.080 --> 0:14:57.120 statements of what had just happened, but instead he quote 0:14:57.520 --> 0:15:03.080 thought that he Gauge was this. But doctor Williams soon 0:15:03.240 --> 0:15:07.160 understood the gravity of what had happened when quote mister 0:15:07.280 --> 0:15:11.120 Gage got up and vomited, and the effort of vomiting 0:15:11.400 --> 0:15:15.480 pressed out about half a tea cupful of brain, which 0:15:15.560 --> 0:15:19.680 fell upon the floor end quote. The Harvard surgeon who 0:15:19.720 --> 0:15:24.120 studied his case noted that quote, the leading feature of 0:15:24.160 --> 0:15:28.640 this case is its improbability. It is unparalleled in the 0:15:28.680 --> 0:15:30.080 annals of surgery. 0:15:30.240 --> 0:15:31.600 End quote. 0:15:31.680 --> 0:15:36.080 The Boston Post article summarized this improbability with just one 0:15:36.120 --> 0:15:40.680 more sentence. Quote, The most singular circumstance connected with this 0:15:40.800 --> 0:15:44.760 melancholy affair is that he was alive at two o'clock 0:15:44.800 --> 0:15:48.600 this afternoon and in full possession of his reason and 0:15:48.760 --> 0:15:55.080 free from pain unquote. Now Gage's survival alone would have 0:15:55.120 --> 0:15:58.359 made this an interesting medical case, it became a famous 0:15:58.440 --> 0:16:01.480 case because of some thing else that came to light. 0:16:02.040 --> 0:16:07.000 Two months after the accident, his physician reported that Gage 0:16:07.200 --> 0:16:10.840 was quote feeling better in every respect walking about the 0:16:10.840 --> 0:16:14.800 house again, says he feels no pain in the head unquote, 0:16:15.720 --> 0:16:19.440 but foreshadowing a larger problem. The doctor also noted that 0:16:19.520 --> 0:16:23.239 Gauge quote appears to be in a way of recovering 0:16:23.800 --> 0:16:28.040 if he can be controlled end quote. So what did 0:16:28.040 --> 0:16:31.720 he mean here, if he can be controlled? It turned 0:16:31.720 --> 0:16:36.640 out that the pre accident, Phineas Gage had been described 0:16:36.680 --> 0:16:40.720 as a great favorite among his team, and his employers 0:16:40.840 --> 0:16:44.680 had hailed him as the most efficient and capable foreman 0:16:44.840 --> 0:16:48.920 in their employ But after the brain damage, his employers 0:16:48.960 --> 0:16:52.840 considered him to be such a different person that they 0:16:52.880 --> 0:16:56.240 decided they couldn't give him his place again. Now, what 0:16:56.440 --> 0:17:00.000 was this change in his personality. Here's what Gauge's Physics 0:17:00.320 --> 0:17:03.160 wrote twenty years later in eighteen sixty eight. This is 0:17:03.160 --> 0:17:05.280 a long quotation, but I'm going to read the whole 0:17:05.320 --> 0:17:09.399 thing because it's fascinating and gives us insight into how 0:17:09.440 --> 0:17:12.960 a person can change when his brain changes. 0:17:13.840 --> 0:17:14.280 Quote. 0:17:14.680 --> 0:17:19.240 The equilibrium or balance, so to speak, between his intellectual 0:17:19.280 --> 0:17:25.000 faculties and animal propensities seems to have been destroyed. He 0:17:25.160 --> 0:17:30.080 is fitful, irreverent, indulging at times in the grossest profanity, 0:17:30.160 --> 0:17:34.760 which was not previously his custom manifesting, but little deference 0:17:34.840 --> 0:17:38.959 for his fellows, impatient of restraint or advice when it 0:17:39.000 --> 0:17:45.400 conflicts with his desires, at times pertinaciously obstinate, yet capricious 0:17:45.480 --> 0:17:50.520 and vacillating, devising many plans of future operations which are 0:17:50.560 --> 0:17:54.959 no sooner arranged than they are abandoned in turn for others, 0:17:55.000 --> 0:17:59.680 Appearing more feasible a child in his intellectual capacity and 0:17:59.720 --> 0:18:04.400 manner infestations. He has the animal passions of a strong 0:18:04.480 --> 0:18:09.240 man previous to his injury. Although untrained in the schools, 0:18:09.600 --> 0:18:13.160 he possessed a well balanced mind and was looked upon 0:18:13.280 --> 0:18:16.800 by those who knew him as a shrewd, smart businessman. 0:18:17.280 --> 0:18:21.600 Very energetic and persistent in executing all his plans of operation. 0:18:22.200 --> 0:18:27.480 In this regard, his mind was radically changed, so decidedly 0:18:27.560 --> 0:18:32.080 that his friends and acquaintances said he was quote no 0:18:32.359 --> 0:18:38.679 longer gauge end quote. Now in the intervening century in half, 0:18:38.840 --> 0:18:43.959 we've seen lots of cases like Phineas Gages, because tragically, 0:18:44.440 --> 0:18:47.960 there are lots of ways for the delicate pink material 0:18:48.080 --> 0:18:51.520 of the brain to get hurt, and they all surface 0:18:51.640 --> 0:18:56.240 the same lesson. When the brain changes, the person changes. 0:18:56.840 --> 0:18:59.960 And of course the more common thing seen in hospitals 0:19:00.080 --> 0:19:08.000 every day are all of nature's tragic experiments strokes, tumors, neurodegeneration, 0:19:08.440 --> 0:19:11.960 And it's the same lesson. The condition of your brain 0:19:12.600 --> 0:19:17.399 is central to who you are. You that all your 0:19:17.440 --> 0:19:21.919 friends know and love cannot exist unless all the fine 0:19:22.119 --> 0:19:25.760 microscopic details of your brain, all the nuts and bolts, 0:19:25.840 --> 0:19:30.040 are in place. If you don't believe me, step into 0:19:30.080 --> 0:19:34.920 any neurology ward in any hospital. Damaged to even small 0:19:35.040 --> 0:19:38.159 parts of the brain can lead to the loss of 0:19:38.320 --> 0:19:43.600 shockingly specific abilities, the ability to understand music, or to 0:19:43.760 --> 0:19:49.000 manage risky behavior, or to distinguish colors, or to arbitrate 0:19:49.119 --> 0:19:53.320 simple decisions. We see examples of this when we meet 0:19:53.359 --> 0:19:57.159 patients who lose the ability to see movement even though 0:19:57.160 --> 0:19:59.879 they're not blind. We see it when a person gets 0:20:00.280 --> 0:20:04.320 front do temporal dementia and starts shoplifting, even though that's 0:20:04.359 --> 0:20:07.080 something they would have never done before. We see it 0:20:07.119 --> 0:20:11.959 when a person no longer understand how a mirror reflection works. 0:20:12.800 --> 0:20:17.080 We see it when medications for Parkinson's disease turn someone 0:20:17.160 --> 0:20:21.640 into a compulsive gambler, or a million other examples that 0:20:21.720 --> 0:20:26.080 tell us that your essence can be changed by changes 0:20:26.160 --> 0:20:29.320 in your brain. So all of this leads to a 0:20:29.440 --> 0:20:33.840 key question. Do we possess a soul that is separate 0:20:33.840 --> 0:20:37.719 from our physical biology? Or are we simply an enormously 0:20:37.840 --> 0:20:43.840 complex biological network that mechanically produces our hopes and aspirations 0:20:43.880 --> 0:20:48.440 and dreams and desires and humor and passion. So over 0:20:48.520 --> 0:20:51.280 this and the next episode, this is the question I'm 0:20:51.280 --> 0:20:54.960 going to unpack. Now, the majority of people on the 0:20:55.000 --> 0:20:59.760 planet vote for the extra biological soul, but all the 0:21:00.000 --> 0:21:05.080 evidence from neuroscience suggests it's the biology. It's a vast 0:21:05.240 --> 0:21:09.600 physical system from which the essence of a person emerges, 0:21:10.040 --> 0:21:13.200 and nothing more than that. Now, do we know which 0:21:13.240 --> 0:21:17.400 answer is correct, not with certainty, but cases like Phineas 0:21:17.520 --> 0:21:20.800 Gauges and every case of brain damage we see in 0:21:20.840 --> 0:21:24.200 the hospitals certainly seem to weigh in on the problem. 0:21:24.480 --> 0:21:28.480 They make it more and more difficult to ignore or 0:21:28.600 --> 0:21:35.440 deny that we are biological creatures. So the materialist viewpoint 0:21:35.520 --> 0:21:40.120 holds that we are fundamentally made only of physical materials. 0:21:40.720 --> 0:21:44.159 In this view, the brain is a system whose operation 0:21:44.440 --> 0:21:47.679 is governed by the laws of chemistry and physics, with 0:21:47.840 --> 0:21:51.920 the end result that all of your thoughts and emotions 0:21:51.960 --> 0:21:57.560 and decisions are produced by natural reactions following local laws 0:21:57.640 --> 0:22:02.719 to lowest potential energy. We are our brain and its chemicals, 0:22:02.760 --> 0:22:06.040 and any dialing of the knobs of your neural system 0:22:06.680 --> 0:22:11.920 changes who you are now. A common approach to materialism 0:22:12.119 --> 0:22:16.359 is called reductionism, and this theory puts forth the hope 0:22:16.400 --> 0:22:21.080 that we can successively reduce the problems down to their 0:22:21.119 --> 0:22:25.159 small scale biological pieces and parts, and eventually come to 0:22:25.280 --> 0:22:31.679 explain complex phenomena like happiness or greed, or narcissism or 0:22:31.760 --> 0:22:37.639 compassion or malice or caution or amazement by understanding the 0:22:37.680 --> 0:22:43.080 pieces and parts at first blush the materialist and reductionist 0:22:43.200 --> 0:22:47.199 viewpoints sound absurd to a lot of people. Not to 0:22:47.240 --> 0:22:49.360 everyone I work with, and possibly not to a lot 0:22:49.400 --> 0:22:53.560 of the listeners of this podcast, but probably to many 0:22:53.600 --> 0:22:56.399 of the people on this planet. And I know this 0:22:56.480 --> 0:22:59.439 in part because when I sit next to strangers on 0:22:59.480 --> 0:23:02.119 a plane or a subway, I ask their opinions about 0:23:02.119 --> 0:23:06.479 this kind of stuff, and people will often say something like, look, 0:23:06.720 --> 0:23:09.800 why I chose my job, how I fell in love 0:23:09.880 --> 0:23:12.639 with my wife, what TV shows I like to watch? 0:23:12.840 --> 0:23:15.480 That has nothing to do with the cells of my brain. 0:23:15.520 --> 0:23:19.600 That's just who I am. And they're right to think 0:23:19.680 --> 0:23:23.040 that the connection between your essence as a person and 0:23:23.200 --> 0:23:28.200 a squishy confederacy of cells that seems distant at best, 0:23:28.920 --> 0:23:32.639 that person's decisions came from them, not from a bunch 0:23:32.640 --> 0:23:35.920 of chemicals cascading through invisibly small cycles. 0:23:36.000 --> 0:23:36.200 Right. 0:23:37.400 --> 0:23:40.960 But what happens when we run into enough cases like 0:23:41.040 --> 0:23:46.320 Phineas Gauges or people who have strokes or tumors or neurodegeneration, 0:23:46.920 --> 0:23:50.320 And what happens when we turn the spotlight on even 0:23:50.359 --> 0:23:54.040 more subtle influences, far more subtle than a tamping rod, 0:23:54.560 --> 0:24:00.760 where changes in the brain change people's personalities. Just consider 0:24:00.840 --> 0:24:04.479 this as an example, Think about the powerful effects of 0:24:04.520 --> 0:24:09.760 the small molecules that we call narcotics. These are invisibly small, 0:24:09.840 --> 0:24:15.480 but they alter consciousness, they affect cognition, they navigate behavior. 0:24:16.040 --> 0:24:20.960 We are slave to these molecules tobacco, alcohol, and cocaine. 0:24:21.240 --> 0:24:26.360 These are self administered universally for the purpose of mood changing. 0:24:26.720 --> 0:24:30.359 And if we knew nothing else about neurobiology, the mere 0:24:30.600 --> 0:24:34.000 existence of narcotics would give us all the evidence we 0:24:34.119 --> 0:24:38.880 need to tell us that our behavior and psychology can 0:24:38.920 --> 0:24:44.040 be commandeered at the molecular level. Take cocaine as an example. 0:24:44.600 --> 0:24:47.840 Cocaine interacts with a very specific network in the brain, 0:24:47.920 --> 0:24:51.959 one that registers rewarding events. This is known as the 0:24:52.359 --> 0:24:59.199 mesolimbic dopamine system. It registers rewarding events like you satisfying 0:24:59.240 --> 0:25:02.600 your thirst with a a cool iced tea, or winning 0:25:02.640 --> 0:25:06.440 a smile from the right person, or cracking a tough 0:25:06.520 --> 0:25:09.960 problem at work and your boss says good job. By 0:25:10.440 --> 0:25:14.400 tying positive outcomes to the behaviors that led to them, 0:25:14.680 --> 0:25:19.600 this neural circuit learns how to optimize behavior in the world. 0:25:20.200 --> 0:25:23.520 It's what helps us get food and drink and mates 0:25:23.920 --> 0:25:47.840 and navigate life's daily decisions now out of context. Cocaine 0:25:47.960 --> 0:25:52.199 is a totally uninteresting molecule. It has seventeen carbon atoms 0:25:52.240 --> 0:25:55.960 and twenty one hydrogens and one nitrogen and four oxygens. 0:25:56.680 --> 0:26:01.760 What makes cocaine cocaine is the fact that its shape 0:26:02.119 --> 0:26:06.840 happens to fit lock and key into the microscopic machinery 0:26:07.400 --> 0:26:12.080 of this reward circuit. So suddenly the cocaine gets to 0:26:12.680 --> 0:26:17.280 act like the most rewarding thing you've done, which causes you, 0:26:17.560 --> 0:26:20.280 in the language of the reward system, to want to 0:26:20.400 --> 0:26:23.840 do that again. And by the way, the same thing 0:26:23.920 --> 0:26:29.240 goes for all four major classes of drugs of abuse, alcohol, nicotine, 0:26:29.320 --> 0:26:34.960 psychostimulants like amphetamines, and opiates like morphine. By one inroad 0:26:35.040 --> 0:26:39.040 or another, they all plug into this same reward circuitry. 0:26:39.119 --> 0:26:43.719 All these types of molecules rev the engine of the 0:26:43.760 --> 0:26:49.120 mesolimbic dopamine system, and so they all become self reinforcing. 0:26:49.720 --> 0:26:53.160 Your brain experiences them and then chases. 0:26:52.840 --> 0:26:53.520 More of that. 0:26:54.280 --> 0:26:57.760 And these effects are so powerful that users will end 0:26:57.840 --> 0:27:02.760 up robbing stores and mugging elderly people to continue obtaining 0:27:03.160 --> 0:27:07.919 these specific molecular shapes. And what's really amazing to note 0:27:08.000 --> 0:27:12.640 is that These chemicals work their magic at scales one 0:27:12.800 --> 0:27:15.440 thousand times smaller than the width of a human hair, 0:27:15.960 --> 0:27:19.480 but by attaching in the right spots, they can make 0:27:19.640 --> 0:27:24.800 the consumers feel invincible and euphoric. By plugging into this 0:27:24.880 --> 0:27:30.880 dopamine system, cocaine and its cousins command beer the reward system, 0:27:31.119 --> 0:27:33.440 and they tell the brain that this is the best 0:27:33.520 --> 0:27:38.000 possible thing that could be happening. So these ancient circuits 0:27:38.040 --> 0:27:44.159 that are there for steering our behavior, these become hijacked. Now, 0:27:44.359 --> 0:27:49.480 these cocaine molecules are hundreds of millions of times smaller 0:27:49.520 --> 0:27:53.280 than the tamping rod that shot through Phineas Gage's brain, 0:27:53.840 --> 0:27:57.920 But the lesson is the same. Who you are depends 0:27:57.960 --> 0:28:03.040 on the precise details of your neurobiology, and the dopamine 0:28:03.080 --> 0:28:06.600 system is only one of hundreds of examples. The exact 0:28:06.680 --> 0:28:11.600 levels of other neurotransmitters, for example, serotonin, are critical for 0:28:11.720 --> 0:28:15.400 who you believe yourself to be. If you suffer from 0:28:15.440 --> 0:28:19.720