Robert Sapolsky is a neuroendocrinologist and primatologist at Stanford University, and the recipient of a MacArthur Genius Grant. In this episode, we discuss his new book, Behave: The Biology of Humans at Our Best and Worst, which is the most accessible discussion of brain science you will find. And for those of you who want more talk about free will, about the fact that the concept doesn t make much sense, and about why that matters, we get into that at the end. We also talk about how he got into neuroscience, and why he thinks primatology and neurobiology are such a good combination. And, of course, we talk about why you should read Behave before you get into the details of the brain, because it's the best book you'll find about the brain you can read. If you like what you hear here, please consider becoming a supporter of the podcast by becoming a subscriber. We don't run ads on the podcast, and therefore, therefore, we are made possible entirely through the support of our subscribers, who support what we're doing here, through becoming a member of the Making Sense Club. Thanks to all of our supporters, we can't do this without you! Thank you to Sam Harris for being a supporter, and for supporting the podcast. You're making sense of this podcast, making sense. Sam Harris - making sense and making sense, of it all. - and we're making it all of us better, so we can all be better. Thank you, and more of you, too, and we can be more like you. . Thanks, Sam Harris, too! - Your support is so much appreciated, and you'll be helping us make sense, more of this, and it helps us all get a better of it. and we'll all have a better listening experience, too much more of it, and that helps us to make sense of the world. -- thank you, more listening to the podcast -- more of that, and better listening to us, and a better podcast, more sense of us all, and so much more! -- and more listening, and less of us, more understanding of the things we can help us all can do more of us making sense in the world, and they'll be better listening of it -- thanks, you'll get a chance to help us, too.
00:15:33.120The punchline here, obviously, is that once you grant that the brain is the final common
00:15:39.240pathway of all these influences when you're talking about human thought and intention and
00:15:43.520behavior, well then you have to grant that what the brain is doing is the proximate cause of what the person is doing.
00:15:51.560And either you're going to sign on to the laws of physics here or you're not, so we'll get back to that.
00:15:59.240But there's a common misunderstanding around the relationship between reason and emotion, just across the board, but in particular with respect to human behavior and the answering of moral questions,
00:16:14.520the way in which we just form a worldview that is this idea that you can be emotionally motivated
00:16:21.160or you can be motivated by emotion-free rationality.
00:16:26.520Let's perform a little psychosurgery on that idea.
00:16:31.940How do you think about reason and emotion?
00:16:33.920Well, it's the inevitable like Coke versus Pepsi dichotomy there.
00:16:39.240And as to which is more important, which influences the other more in terms of our actions, and of course, it turns out, as with most sort of dichotomies with behavior, it's a false one.
00:16:51.960They're utterly intertwined and intertwined on a neurobiological level.
00:16:57.960You have a thought, you think of something terrifying that happened to you long ago and emotional parts of your brain activate and you secrete stress hormones.
00:17:08.280Or you have an aroused emotion, you're in an agitated, frightened state, and suddenly you think and reason in a way that's like imprudent and ridiculous.
00:17:22.060When we're aroused, the two parts are equally intertwined.
00:17:25.080But probably where the most progress in thinking about this intertwining has come in recent years is, you know, there's a certain sort of comfort and I think chauvinism we take as these like creatures with big cortexes and thinking that nonetheless reason is sort of at the core of most of our decision making.
00:17:45.660And an awful lot of work has shown that far more often than we would like to think, we make our decisions based on implicit emotional automatic reflexes.
00:18:00.820Parts of the brain that are marinated in emotion and hormones are activating from the standpoint of the brain long, long before the more cortical rational parts activate.
00:18:12.100And often what we believe is rational thinking is instead our cognitive selves playing catch up to try to rationalize why our emotional instincts actually are perfectly logical and make wonderful sense.
00:18:26.180And in lots of ways, the best way to show this is you manipulate the affective, the emotional, the automatic, the implicit, the subterranean aspects of our brains where we may not even be aware of it.
00:18:43.400And it changes our decisions and then we come up with highfalutin explanations for why it's actually because of some philosopher we read freshman year.
00:18:59.120So there are really two sides of this.
00:19:00.780So that's one side which is kind of deflationary of cognition and reason.
00:19:06.160So you think your reasoning and that your reasoning is driving your cognition or your belief formation.
00:19:12.800But then when you look closely, you find that it's being driven from below by emotion.
00:19:18.040But the flip side of that is that in order to make even the most coolly calculated reasoning effective, it needs to be integrated with parts of the brain.
00:19:28.680In this case, the ventromedial prefrontal cortex, that you need a felt sense of the consequences of being right or wrong.
00:19:35.580And this connects to Damasio's work and others where people who have neurological damage there, they may know the correct strategy, say, in a gambling task.
00:19:45.880They may understand the probabilities, but they can't make that understanding effective because it doesn't actually mean anything.
00:19:57.440And it turns out this is like a tremendous rebuke for the people out there who would say, if only we could be purely rational creatures, if only we can get rid of all that affective muck from underneath, why we'd all be Mr. Spock and it would be a wondrous world.
00:20:14.200And exactly as you say, ventromedial prefrontal cortex work of people like Damasio, people who have damage to this part of the brain that's basically the means by which your emotional parts of the brain talk to your most rational ones and tell them what they're feeling, get damaged there.
00:20:33.080And people make decisions about things that we view as appalling, as beyond the pale of cold-blooded, as detached.
00:20:42.500As one example, you take any normal person on Earth and you give them sort of a philosophy problem.
00:20:50.560Would you kill one stranger to save the life of five?
00:21:17.900They don't process relatedness in the same way.
00:21:20.900And every primate on Earth would look at that and say there's something desperately wrong with this person's brain.
00:21:28.080On this issue of emotion and rationality, one point I have begun making, which I haven't heard made, and I just want to bounce it off of you.
00:21:37.460So I've begun to think about doubt, which really is one of the core foundations of our rationality, right?
00:21:45.420I mean, so you say something which I find implausible, kind of my error detection mechanism, whether it's logical or factual or semantic or based on memory.
00:21:57.800You utter a sentence and I don't buy it.
00:22:01.160That feeling of doubt, in my view, really is an emotion.
00:22:05.200And, you know, we actually have some neuroimaging data to back this up in that all the fMRI studies I did on belief showed that disbelief, doubting the veracity of a proposition, was associated with activity in the anterior insula.
00:22:20.460And I've actually begun to think of doubt as a kind of emotion on the continuum of disgust, as kind of propositional disgust or cognitive disgust.
00:22:31.600And, you know, frankly, when I see our president speak, I find I'm viscerally in touch with doubt as disgust, right?
00:22:38.980I mean, like there's a certain level of incredulity in the face of, you know, a confident utterance that precipitates in me, at least, a fairly strong emotion of disgust.
00:22:49.400So I just I want to put those data in front of you and just get your take.
00:22:53.560Well, my my insular cortex is right with you on that one.
00:23:01.080Obviously, there's some domains where doubt is just a purely rational process.
00:23:06.620You sit there and you add up two and two and somehow it comes out to five.
00:23:12.000And that's a fairly pure cognitive state of saying, I doubt if that actually is correct.
00:23:18.080But most of the doubts we have and in our social world, I think you're absolutely right, is steeped in emotion, emotion, disgust, perhaps at the person who is sowing that doubt, emotion.
00:23:33.220Robert, just to clarify, if we put you in a scanner and give you propositions just like that, two plus two equals five, you're six foot five inches tall, you're a woman with blonde hair, George Washington was never president of the United States.
00:23:48.940I just give you propositional statements which you recognize to be untrue, but which are not, in fact, emotionally laden.
00:23:57.480I would certainly predict on the basis of now three neuroimaging studies that those would be associated with insular activity in you and the same statements in a positive light that you would accept.
00:24:11.820You know, George Washington was the first president of the United States wouldn't.
00:24:14.720I completely agree because it's very much context dependent.
00:24:19.460If I were sitting there on my own and adding up two and two and I got five, I would have, you know, a half seconds worth of pure rationality.
00:24:54.800Are they going to lock me up in the scanner, et cetera?
00:24:57.340And often running with emotional aspects.
00:24:59.960I think one of the most perfect realms for looking at this is when you look at conformity studies and where people go along with something that is patently untrue, yet they go along.
00:25:13.880A certain percentage of them are just being affable.
00:25:46.480And doubting even seemingly the most cerebral and sort of soulless of issues out there, nonetheless readily taps into all these senses of anxiety running underneath there.
00:26:01.660There's this other piece here, which is that the brain doesn't have, I mean, this is just a constraint of evolution.
00:26:08.480We were not built so as to acquire new cognitive abilities de novo.
00:26:17.040The only material to use for modern human cognition are these ancient structures that have to be commandeered to new purposes.
00:26:26.780So everything we do is built on the back of these apish structures.
00:26:33.920You know, here we're talking about the insula, which does receive the inputs from the viscera.
00:26:40.020You know, you find rotting food disgusting.
00:26:43.000You know, that is the tale told by the insula.
00:26:45.200And the only way to build a mind that has the capacity to find abstract ideas repugnant is to be repurposing or extending the purpose of these brain areas that were doing nothing of the kind in apes like ourselves that couldn't form abstract ideas.
00:27:06.720Absolutely. And it's a totally fascinating domain, the fact that this insular cortex, which if you're like a mole, will tell you if you're eating something rotten, activates in humans thinking about moral disgust.
00:27:22.140That a part of the brain that does temperature sensing for you is also activated when you're contemplating whether somebody has a warm or cold personality, that the parts of your brain, some parts that are involved in pain detection, in a very literal sense, also activate when you're feeling empathic about somebody else's pain.
00:27:42.600And all of these speak to this sort of altruism about evolution. Evolution is not an inventor. It's a tinkerer. It makes do with what's already there.
00:27:54.280I don't know. When did humans come up with the concept of moral outrage and moral disgust? Maybe in the last 20,000 years, 50,000, whatever.
00:28:02.800When did we come up with the concept of having warm or cold personalities? A lot shorter than that.
00:28:08.080And at that point, nobody sits down and says, okay, we need to evolve an entirely new part of the brain that does moral disgust.
00:28:17.060They say, insula. I know. That kind of sounds the same. They do food disgust.
00:28:23.040Like, here, give me some duct tape. We're just going to push that into the insula.
00:28:27.040And now the insula also does metaphorical moral disgust.
00:28:30.440And it's a brain that's winging it in a lot of ways for some really interesting ways in which it's better and ways in which that's for the worse.
00:28:41.000When you think about the role of the brain in producing these kinds of purely human-level distinctions, things like the birth of civilization, really,
00:28:51.900I mean, it's largely a story of what the frontal cortex is doing.
00:28:56.680I think you say at one point in the book that this region of the brain is what makes you do the hard thing when the hard thing is the right thing to do.
00:29:04.820Let's talk for a moment about the role of the frontal cortex in our species.
00:29:09.900That's exactly sort of a summary of what it does.
00:29:14.180More jargony, it does impulse control and emotional regulation and long-term planning and gratification postponement and executive function.
00:29:24.900It's the part of the brain that attempts to tell you, you know, this seems like a good idea right now, but trust me, you're going to regret it.
00:29:33.780Of great importance, it's the most recently evolved part of our brains.
00:29:38.800Our frontal cortex is proportionately bigger and or more complex than in any other primate.
00:29:45.860And most interestingly, it's the last part of the brain to get fully wired up.
00:29:52.100I mean, we're accustomed to images of, you know, your brain is pretty much set to go by the time you're at kindergarten.
00:29:57.900The frontal cortex is not fully online until people are on the average about a quarter century old, which is boggling, which is boggling.
00:30:08.940But it also tells you a whole lot about why adolescents act in adolescent ways because the frontal cortex isn't very powerful yet.
00:30:16.860But in that is an incredibly interesting implication, which is if the frontal cortex that does all this complex, like culture-specific reasoning and regulating your behavior,
00:30:32.840if the frontal cortex is the last part of the brain to fully mature, by definition, it's the part of the brain that is least constrained by genes and most shaped by experience.
00:30:47.880Because think about, I mean, sort of, okay, the frontal cortex, it's your moral barometer, if that's the right metaphor, it's your Calvinist voice whispering in your head.
00:30:59.160So the frontal cortex, for example, plays a central role if you're tempted to lie about something.
00:31:05.560And if you manage to avoid that temptation, your frontal cortex had something to do with it.
00:31:10.740But at the same time, if you do decide to lie, your frontal cortex plays an enormous role in you doing an effective job at lying, because that's a version of frontal regulation also.
00:31:29.900So, you know, if you're talking about a part of the brain that is both central to you avoiding lying, but once you've decided to lie, is central to you doing it effectively, this is a very human, very complicated part of our brains.
00:31:44.880Yeah, and so to follow on what you just said there about the implications of it being so late to develop, this is really where it matters what culture you're in and what early life experience you have.
00:31:58.820What kind of person you become with respect to your beliefs about ethical norms and, you know, what constitutes honor and everything that stands out as a salient, consequential difference between groups and societies.
00:32:16.020Now, none of this is just floating around in the ether, it's not just in the books on our shelves, this is getting etched in the brains of all concerned, and largely this is a story of what is happening in the frontal cortex.
00:32:32.340Yep, and that's exactly why it can't mature until you're 25.
00:32:36.800It's not that it's a more complex construction project than wiring up the rest of your brain is.
00:32:43.580You need the first 25 years to learn your situational ethics and your culture-specific beliefs and that sort of thing, and those are subtle, and they're often unstated, and they're often exactly the opposite of what people tell you things are supposed to be about.
00:32:59.000I mean, think about it, every culture on earth bans some types of killing and allows others, and they all do different ones.
00:33:08.540Every culture on earth supports some types of lying and bans others.
00:33:13.320In our culture, it's okay to lie to grandma to say, ooh, I don't have that toy, this is wonderful, thank you, thank you, when you've got the actual toy in your closet.
00:33:21.920And it's okay for us to lie if somebody says, are you harboring those refugees in your attic, and you say, no, of course not, sir, of course not, SS officer.
00:33:32.380You know, that one's okay, but there's other ones we've had.
00:33:34.760Every culture has prohibitions about sexual behaviors, where some types of behaviors are wondrous and others are blasphemous, and they all differ, and that's a lot of subtle stuff to have to master as to what counts as doing the right thing.
00:33:49.980Although I'm doing my part to not spare grandma the brutal truth about the toy.
00:33:55.100That's a meme I'm trying to knock down.
00:33:57.140I know, your book, Lying, certainly makes the most convincing sort of argument I've seen for it's not okay in any domain.
00:34:05.980Yeah, although I think there's a misunderstanding there.
00:34:08.880I think I saw in a footnote or an endnote, you said that I'm against lying in all conceivable circumstances, kind of the Kantian view, which is not the case.
00:34:18.360I actually, if you're at the door with the Nazis and you've got Anne Frank in the attic, then I view lying the way most people do as an adequate and even necessary act of self-defense or the defense of others in those cases.
00:34:31.980I really view it as being on a continuum of violence where it's the least violent thing you can do to someone who's no longer behaving as a rational actor or someone whose behavior you can modify with honest speech.
00:34:45.280Okay, sorry for that misrepresentation.
00:34:48.620Nobody was supposed to read the footnotes, so...
00:35:11.680It's not as faced with complex of a task as we do when learning sort of the complexities of our frontal-dependent prohibitions.
00:35:23.160But no, we're not the only species that invented the idea that this is a very good part of the brain to make very malleable in the face of experience.
00:35:32.260We've just got the most dramatic version.
00:35:36.020There are other interesting bits of neuroanatomy here that you don't often hear talked about, at least in the popular press.
00:35:43.600There's something called von Economo neurons, which are unique in primates and cetaceans and elephants, I believe.
00:35:51.240And they're, I think, uniquely in the insula and anterior cingulate, or preferentially there, and they relate to social cognition and self-awareness.
00:36:01.100Give us a potted description of what's happening there with these neurons.
00:36:07.260And you study human brains, and one of the first things you have to recognize is we're not humans because we've invented a totally novel type of neurotransmitter or a completely new brand of neuron.
00:36:18.620It's just that we've got more of them.
00:36:22.680But then people found this one neuron type that did seem to be unique to humans, these von Economos.
00:36:29.560They're almost entirely found in anterior cingulate, insulate cortex, having to do with empathy and moral disgust and all that cool, interesting stuff.
00:36:43.000But as you say, then people looked further, and it turns up in other species and all the usual suspects when you're looking for the most complex social worlds.
00:36:52.840Yeah, other apes, other primates, cetaceans, elephants.
00:36:57.660And the best guess is that they play a role in some very complex aspects of sociality.
00:37:19.400But one of the most interesting things is these are the first neurons that die in a very obscure neurological disease called frontotemporal dementia.
00:37:28.080And one that predominantly damages the frontal cortex.
00:37:32.920And the first neurons that go are von Economo neurons.
00:37:37.220And two interesting things about that.
00:37:39.060What that tells you is these are really expensive, vulnerable neurons to operate if they're the first ones that keel over.
00:37:46.760But the other thing is, what does the disease look like?
00:37:53.280And often it's initially viewed as a psychiatric disorder until you realize this is a massive neurological sort of carpet bombing of the front part of your brain.
00:38:03.140Whatever these neurons are doing, they are very, very much sort of specialized for the most complex social things we fancy species do.
00:38:13.260Yeah, well, so I think the last stop on our Cook's tour of the brain here, or at least the Cook's tour of the frontal cortex, is the dorsolateral PFC, which is associated with much of what we consider to be higher rationality or executive control.
00:38:30.320And activity here is able to dampen activity in emotional parts of the brain, like the limbic system, for instance, the amygdala in particular, reducing negative affect.
00:38:43.740It can do this by becoming active in a relevant way.
00:38:48.420And this is something that I think people understand, that if you cognitively reappraise what an experience means.
00:38:55.140So, for instance, you know, you think someone's being rude to you, then you reconstrue that, realizing, say, that maybe he's just nervous.
00:39:03.320And then that will dampen your initial negative emotional response to what you perceive to be rudeness.
00:39:10.660But what's also interesting is that really any use of your dorsolateral prefrontal cortex can dampen negative arousal.
00:39:20.780And if you just, if you're feeling negative emotion and you just put your attention on something else, you just start doing math problems,
00:39:27.800or you do anything that requires an alternate form of cognition, that can have a similar effect of dampening arousal.
00:39:35.380In thinking about this, it's always interesting to consider how someone like yourself, who spends a lot of time thinking about the mechanics of emotion and cognition from the brain side,
00:39:47.760does this ever become relevant to you in your life, behaviorally?
00:39:52.360I mean, do you ever, is there anything that you do differently in your moment-to-moment experience,
00:39:57.400given how much time you spend thinking about what's going on under the hood?