Robert Sapolsky: The Biology of Humans at Our Best and Worst

hi welcome everybody and I want to share it takes about Robert Sapolsky that I have pirated from web somebody has written elegantly about him I wouldn't be able to as a boy in New York City Robert Sapolsky dreamed of living inside the African dioramas in the Museum of Natural History by the age of 21 he made it to Africa and joined the troop of baboons although the life of a naturalist appealed to him because it was a chance to get the hell out of Brooklyn he never really left people behind his gift for storytelling led the New York Times to suggest if you cross Jane Goodall with a brougt belt comedian she might have written a book like a primates memoir suppose keys account of his early years as a field biologist the uniqueness of Sapolsky his perspective on the human condition comes from the ease with which he combines his insights from the field with his findings as a neuroscientist what makes Sapolsky great is that he connects science with society and human life and with human nature he tackles the question of human mind with similar questions that kept our total Copernicus and Shakespeare awake in the middle of the night for more than 30 years Sapolsky has divided his time between fieldwork and primates and highly technical neurological research in his laboratory at stanford as a result he can effortlessly move from a discussion of pecking orders in primates to an explanation of how neurotransmitters work during stress and gets laugh during it Sapolsky regards is this sobering news with characteristic good humor finding hope in our own capacity to prevent some of these problems in the small steps with which we live our everyday life the humor and human he brings two sometimes sobering subject matter makes Sapolsky a fascinating speaker as you will witness he he lectures widely on topics as diverse as stress and stress-related diseases baboon's the biology of our individuality and so on you name it Sapolsky is a MacArthur Genius fellow a professor of biology at neurology and department of biology at Stanford University and a research associate with the Institute of primate research at the National Museum of Kenya in 2008 National Geographic and PBS aired an hour-long special on stress featuring Robert Sapolsky and his research on the subject matter Sapolsky was awarded Rockefeller University's Lewis Thomas Prix prize for writing about science his articles have appeared in publications such as Discover and The New Yorker and he writes a biweekly column for The Wall Street Journal entitled mind and matter in addition to a primates memoir suppose he has written for other books including the trouble with testosterone why zebras don't get ulcers and monkey love and other essays on our lives as animals and his most recent book behaved the biology of humans at our best and worst to quote my colleague David Eagleman a neuroscientist at Stanford University his latest book as wide as it is deep it is colorful electrifying and moving Sapolsky leverages his deep expertise to ask the most fundamental questions about being human from acts of hate to acts of love from our compulsion to dehumanize and to rehumanize we are delighted that Robert has accepted our invitation to talk about the biology of humans at our best and worst this lecture is kindly and generously sponsored by a gift from Christina and Hameed macadam to iranian studies program at Stanford and by the laboratory of cognitive and behavioral neuroscience and cognitive neuroscience interest group I welcome everybody and joining me to welcome Robert Sapolsky thank you well singer Lee strange to have so many people in an audience not wondering if this is gonna be on the final so thank you all for being here now let me start off a little bit unorthodox Lee here let me start off with a fantasy I first had as a kid and it was a fantasy of the day I captured Hitler I over powered his elite guard I burst into his secret bunker I wrestled his Luger out of his hand we grappled with each other I pinned him down got handcuffs on him and was able to say Adolf Hitler I arrest you for crimes against humanity and at that point the the Medal of Honor version of this fantasy would get a little bit harder to maintain and viscera would start to creep in what would I do if I had had Hitler and if I let myself go there it wasn't actually hard to think about it sever his spine at the neck take out his eyes puncture his eardrum cut out his tongue inject him with some sort of cancer that would just postulate on every cell in his body I had this fantasy at various points when I was a kid and sometimes I still do and when I do my heart beats faster and my breathing gets faster all this planning for the most evil human and all of history the sole most deserving of damage of punishment except I have a problem with that which is I don't believe in Souls and I don't believe in evil and I don't believe in punishment I think wicked only belongs in the title of the musical but at the same time at the same time there's all sorts of people I would like to see dead but I'm against the death penalty but there's lots of violence schlocky movies I like going to but I'm for very strict gun control but then there was a time I went to that laser quest place such a good time hiding in a corner shooting at people in other words I'm your basic confused human when it comes to feelings about violence now I don't need to get up on the soapbox here about the problems we've got with violence as a species we've used shower heads to deliver poison gas letters with anthrax passenger planes as weapons rape as a military strategy we are a miserably violent species but there's two problems with that at least the first one is we don't hate violence we hate the wrong kind of violence when it's the right kind we get all excited we leap in to see it we hand out medals we disproportionately vote for meet with the people who are best at that when it's the right kind of violence we love it the other complication is when it comes to being a violent species we're just extraordinarily weird I mean some of the time we're just like any old ship we take some big old heavy rock and cuddle somebody's brain and but some of the time we can be wildly violent to mean nothing more metabolically taxing than pulling a trigger or signing an order or looking the other way or damning with faint praise or being passive-aggressive we do the theory odd thing when it comes to violence let me give you one of the single strangest examples of violence I've ever heard of and this is one having to do with Indonesia in the 1960s mid 60s there was a coup that overthrew the government there instituted a right-wing military dictatorship for the next thirty years and in the year afterward approximately half a million Indonesians were killed by right-wing death squads if you were an intellectual if you were a leftist if you were of any of the ethnic minorities that were out-groups their savagery death squads would come to a village systematically kill every single person in that village so decades later the writer VS Naipaul was traveling through Indonesia and he would hear stories about what happened at the time and he kept hearing this crazy story which was sometimes these death squads would show up at a village to kill everyone and they would bring along a traditional Indonesian gamelan orchestra nuts one day he runs across one of these old grizzled veterans of one of these death squads he's talking to the guy he's proud to sort of brag about all the villagers and civilians he killed saving the nation and lipo finally said you know this crazy thing about how sometimes you people would bring like gamelan orchestras to these massacres is that and the guy said oh yes yes whenever we could we would bring an orchestra along an eyeball said why would you do that and in one sentence the guy looked puzzled and just encapsulated everything that's weird about our violence he said to make it more beautiful of course there is no other primate on earth that could make sense of our violence when we're bringing along orchestras to make it more beautiful now the single most complicated about thing about us being this miserably violent species is at the same time we're the most altruistic most cooperative most empathic species on earth and we're getting better at it consider every single thing up here was invented in the last century all these ways in which we are extending sort of an umbrella of empathy and protection and all sorts of unlikely directions where this phenomenally violent species were this phenomenally cooperative empathic one how do we begin to possibly make sense of the biology of us at our best and worst now one of the things is clear about it it is utterly boring if all you want to figure out try to make sense of us as a primate amid all the others where are these extremes of our behavior come from it's totally boring if all you want to do is understand the motoric aspects of the behavior your brain tells your spine tells your muscles to do something and hurray you've behaved what's much more interesting is to understand the meaning of the behavior because in one setting you pull a trigger and it's an appalling act and another setting you heroically suicidally pull fire onto yourself and it's an awe-inspiring act in one setting you put your hand on someone else's and it's a moment of deep compassion and another the exact same motoric behavior and it's first step of a deep betrayal the challenge with us and understanding our behavior is understanding the context of it and that's real challenging now one of the things that is absolutely clear with that is you were gonna get nowhere and understanding these features of our behavior if you decide here is the part of the brain that explains everything that's going on or here is the hormone or the gene or the childhood experience or the anything here's the whatever that explains everything instead if we're going to make any sense of these complex context dependent behaviors of ours we have to look at many layers so one of these behaviors happens it's wonderful it's appalling it's ambiguously somewhere in between and we ask the biological question why did that behavior just happen and when we do that we're actually asking a whole array of questions what went on one second before and that person's nervous system that instructed those muscles to do that good bad in between behavior but we're also asking what was going on seconds to minutes before in the sensory world that triggered those neurons and we're also asking what was going on with hormone levels hours two days before that made that organism more or less sensitive to certain sensory stimuli that caused and then back to adolescence and childhood in fetal life and back to when you were just a fertilized egg and then back to what sort of culture your ancestors came up with and what sort of echo systems and what evolutionary forces sculpted all of that if you want to get a sense you're going to have to ask that question on all these levels ok so beginning with that one of our behaviors has happened and we do our first version of saying why did that occur what went on of the brain one second before that context dependent trigger was pulled that context dependent hand was touched why did that occur so if we're going to start off with the worst of our human behaviors right off the bat we start off with a part of the brain the amygdala the amygdala is about aggression it's about violence stimulate the amygdala and a rat monkey a human you get unprovoked aggression destroy the amygdala you're unable to elicit aggression anymore the amygdala is about aggression if you take an amygdala gist though and you sit him down and you say what's the amygdala about aggression is not the first word they're gonna mention the first one is fear the amygdala is about fear it's about phobias and eight fears even more importantly it's about where you learn to be afraid of things fear conditioning and such in other words you cannot understand the neurobiology of violence without understanding the neurobiology of fear and in a world in which no amygdaloid neuron need be afraid there'd be a lot more of us sleeping between lions and labs now the whole thing about the amygdala and processing fear is it does something very interesting with sensory information ok so you see something officially scary oh no there's a rattlesnake how does this get processed in your brain the most straightforward thing is visual information goes to the sensory Waystation the thalamus and then it sends it on to the visual cortex and then begins a whole science fair project the first layer of your visual cortex breaks this down into pixels and then as it hands it to the second layer which turns it into lines and then the next layer moving lines and layer after that and layer and going through your memory and like your golden book of snakes and finally somewhere up in your cortex it says oh my that's a rattlesnake perhaps we should let those fellows down in the amygdala know about it this is glacial from the standpoint of the nervous system turns out in addition to that pathway there's a shortcut that very first volley of visual information getting into that thalamus has a shortcut that gets to the amygdala in other words the amygdala knows that you're looking at a rattlesnake while your visual cortex is still fussing around with the instruction manuals and later - in other words your amygdala can know what that is before you're even consciously aware of it and this is all in the course of hundreds of milliseconds tenths of a second okay that's great that's very good if your amygdala already knows you're looking at a rattlesnake that's terrific but there's a downside which is there's a reason why you've got your visual cortex doing all that complexity it's to make sure you're accurate about what you decide you're looking at and that amygdala getting that lightning fast reflexive information is all set up to make a mistake and before you know it you think the guy who just happens to look in a certain way the guys holding the cell phone is actually holding a handgun instead and you pull that trigger in other words the amygdala gets all this privileged information at the intersection of aggression and fear this privileged information but catastrophic Lee at times the information is not terribly accurate next part of the brain area called the insula insular cortex take any mammal out there and give it some rotten disgusting spoiled food to bite into and as soon as it does the insula activates and that triggers all these reflexes animal gags it spits it out as stomach heaves it throws up whatever the insula keeps you from poisoning yourself with toxic food that's great so you get someone like college freshmen to volunteers for this and goes into a brain scanner and bites into some rancid fetid food and same deal insula activates but now instead don't have the person eat something disgusting have them just think about it think about those little legs pushing against your lips as you try to and you're gonna activate your insular cortex ah in most mammals it does gustatory disgust and us it also does thoughts about gustatory disgust but then something even more interesting well don't give the person something disgusting to eat don't make them think about something disgusting eat make them think about something else that's disgusting make them think about something that is morally disgusting and the insula activates in humans this part of the brain also mediates moral disgust and presumably forty fifty thousand years ago when we came with the notion of norm violations that could be so extreme that it winds up being appalling they had a meeting they said we can't invent a new part of the brain watch that insula does disgusting foods disgusting behavior I don't know sounds similar expand it in there give me some duct tape and now suddenly your insulin also does moral disgust that's why if something is sufficiently morally disgusting we feel sick to our stomachs it leaves a bad taste in our mouth we feel queasy now this is great because this certainly gives a lot of visceral force to things that we find to be morally appalling but there's a problem with us which of course is that one person's morally disgusting behavior is somebody else's perfectly normal loving lifestyle in other words moral disgust is a moving target and the trouble with the visceral force of moral disgust is it just begs you to use it as a litmus test to decide how do I figure out what's right and wrong in the world well if it seems so different from what I normally do that I'm feeling a little queasy it's wrong wrong and wrong and this wisdom of repugnance is a way of making some very bad moral choices okay so what we see with the insula most mammals it's about sensory disgust in us instead it's about moral discussed which is intensely context dependent and what we see there is the insula is central to us deciding that just because something is so different that it's hitting all sorts of visceral alarms that there's something that's got to be where I can't tell you why but when they do that it's just simply wrong and the first place in the brain the insula screams that news - next is the amygdala meanwhile another part of the brain in reference to all of this frontal cortex frontal cortex the most interesting part of the brain it's most recently evolved we've got more of it proportionately than any other species what is the frontal cortex - it makes you do the harder thing when it's the right thing to do gratification postponement long-term planning impulse control emotional regulation the frontal cortex is the part of the brain that says hold on hold on hold on are going to be happy you did it it does all of those harder things when it's the right thing now of course the picture is frontal cortex and amygdala have a lot to do with each other which is the frontal cortex spends a whole lot of time sending inhibitory projections down into the amygdala saying I wouldn't do that if I were you I know it seems really tempting right now you're gonna regret it I wouldn't do that I wouldn't racing to the amygdala before that shortcut gets the amygdala to do something stupid and impulsive there and the picture you get is basically all of the frontal cortical amygdaloid interactions are top-down the only thing the frontal cortex has to do with the amygdala is like showing up and preaching Christian Temperance and things like that and other than that it's this very one directional relationship in actuality it's two directional because we see versions of this all the time this is every single time in some moment of arousal a fear of stress of who knows what you make some decision that seems brilliant at the timing you spend the rest of your life regretting it ah it's not just one direction bottom-up explains an awful lot of when we decide something is the right thing to do in one given moment and may not think that way one and a half seconds from now and what this speaks to is the whole notion of doing the harder thing when it's the right thing to do the right thing is once again very context dependent I mean think about this all of these are circumstances where you need self-control to pull things off I mean look at this you are in a circumstance where you're being tempted to lie about something for personal gain and you're trying to avoid the temptation to do that your frontal cortex is playing a central role if you're going to resist that temptation but the second you decide you are going to lie your frontal cortex is essential for you doing a good job at it remember make eye contact now and then and don't let my voice crack in control if you've got a part of the brain that's both central to resisting the temptation to lie but once you decide to lie doing a good job at it this is a very very complex brain region here okay so the frontal cortex makes you do the harder thing when it's the right thing to do that's very much a contact dependent behavior and the main thing is the frontal cortex is not this gleaming cerebral bit of like cognition it's just marinating all the visceral yuck coming up from underneath it's a very bi-directional relationship few more brain regions one more the dopamine system dopamine a neurotransmitter one use of it in the brain in the mesolimbic dopamine system dopamine has to do with pleasure with reward cocaine works on the dopamine system give a rat a monkey a human a reward from out of nowhere the don't the dopamine system activates dopamine is about reward but then people figure it out it's actually about something much more interesting than that now set up this paradigm a little light comes on of the room as a signal and that means if you go to this lever and you press it ten times you get a reward signal saying it's the start of one of those sessions go do the work you get a reward once that rat monkey human learns this relationship what happens now when does dopamine rise does arise when you get the reward absolutely not it rises when the signal comes on that's the yeah I know how this works this is gonna be great I'm all over this lever pressing stuff this is terrific the dopamine is about reward but even more so it's about the anticipation of reward and remarkably if you block the rise and dopamine there the organism doesn't press the lever it's about the goal directed the behavior it's about the pursuit of reward rather than about reward itself now what I just showed you in these circumstances was you press the lever you got the reward press the lever reward a hundred percent of the time what if now you switch things switch things to you press the lever and only 50% of the time you get a reward what happens to dopamine now it goes through the roof like crazy because what have you done you've just inserted a critical word into this neuro chemistry the word maybe and nothing fuels dopamine like maybe being right on that fulcrum of today's my lucky day but I'm such a screw-up but no today is my lucky socks but I'm a total dork and just going back and forth on that and that may be nothing cranks out reward related behavior motivated behavior like intermittent reinforcement and maybe put in there and this is what the neuroscientist she built Las Vegas no inside out the power of this okay so what's dopamine doing here it's about reward even more so anticipation reward even more so goal directed behavior in order to get that reward and what we see is maybe putting uncertainty into the system is crazy ly crazily stimulating and if you want to take an organism and get it pumping out dopamine like crazy all you need to do is put it in the circumstance when they are punishing an individual that has done a norm violation we will come back to that okay couple more brain regions fusiform cortex it's a primate specialty recognizes faces and Terrier cingulate it has to do with empathy feeling somebody else's pain but they both come with fine print flash up faces fusiform cortex is activating flash up the face of someone from a different race and on the average the fusiform doesn't activate as much the face doesn't register as much you don't remember it as accurately show somebody a film clip of a hand being poked with a needle and the anterior cingulate activates an empathy if the hand skin colour is different from your own it doesn't activate as much whose face whose pain all of these as qualifiers okay so this begins to give us just a sense tip of the iceberg of what's going on of that one second before that behavior occurs but no brain is an island and when we look at one of these behaviors good/bad in between we're asking why did this behavior occur we're now also asking something about seconds to minutes before what sensory information had an effect on the amygdala the frontal cortex etc where do these whine to being relevant and what I put in this slide here is summarizing gazillion different studies showing sensory information is altering our behavior in ways where we have in a clue this is happening for example put up a pair of eyes on a bus stop and people literally have a pair of eyes like that flash up subliminally for less than a second while somebody is playing in an online game and they cheat less they become more generous you're being watched give somebody some horrible cod liver oil to drink and just tastes Harlin and for minutes afterward people will be more punitive about norm violations they're confusing a bad taste with a bad act or how about this one put somebody in a room and give them a questionnaire to fill out about their political views and if there's smelly garbage in the room people become more socially conservative doesn't do a thing to your economic views your geopolitical views you feel the same way about our trade deficit with Swaziland that you did this morning but them and their different lifestyles suddenly begin to seem them and disgusting and wrong wrong wrong just because visceral disgust alarms are going off because there's smelly garbage in the room how about this one sit somebody in a chair either a hard wooden one or a nice plush sofa like that and give them job applications from like resumes of suppose of applicants and they evaluate them afterward if you sit in a hard wooden chair on the average you were more likely to assess applicants as having a rigid inflexible personality you are more likely to think they're hard asses because of the chair you're sitting in or how about this one up on the right there this was a study in PNAS very prestigious journal a few years ago looking in a country all of the parole board hearings in that country over the course of a year 5,000 hearings looking at who was sent back to jail versus who was given parole looking at all sorts of variables and out of it popped an extraordinary finding the single biggest predictor of whether or not a prisoner got parole or not while how many hours it had been since the judge had had a meal if you went before a judge right after a meal 60% chance of being paroled four hours later down to zero just this line along comes lunch down again a little snack afterward down again it goes and what is extraordinary about this is two things first we understand the biology of this blood glucose levels have something to do with whether your neurons can work really hard and what counts is working really hard near frontal cortex viewing the world from someone else's perspective trying to think about their mitigating circumstances the frontal cortex takes a lot of energy to do the harder thing and what's even more striking is if you took any of those judges two seconds after they made that decision and you said okay so why'd you send this guy back to jail but this guy walk they're not gonna say oh because of my blood glucose no they're you get a site like freshman philosophy class or something and all the while this is the interceptive the internal sensory information that was shaping that decision finally top left the most depressing finding in this whole field is you take people put them in a brain scanner and you're flashing up faces like tenth of a second barely noticeable high-speed and for your average person you flash up the face of someone of a different race and the amygdala activates oh crap hardwired on a tenth of a second to have a racist response like that is this inevitable are we like is this hopeless for us there again now do the experiment a little bit differently I recently found out that apparently San Francisco has a baseball team so and that supposedly they have this rival that they get very worked up about and now you're flashing up the faces and each face is wearing a baseball cap and if you get the right San Francisco baseball fanatic if it's the home team you get one response if it's the rival the amygdala activates and you not processing skin-color oh my god the innate nature of human racism my ass all it takes is this cultural thing we invented one or two centuries ago and which one counts as an us or them and baseball loyalties overrides that and you've recategorize people within milliseconds there okay so in terms of the sensory stuff we are constantly being buffeted constantly being influenced by sensory information like this and half the time we haven't a clue it's there or it can imagine it's relevant to our and judicial decisions okay so now pushing further back our behaviors occurred what's relevant in the hours two days before what two hormones have to do with what goes on here now if we're talking about humans that they're worse - right off the bat we know which hormone to roundup testosterone so what's the deal with testosterone why are males of every species in every cultures such a pain in the rear on this planet here it's because testosterone makes you aggressive testosteron doesn't make you aggressive here's what it actually does take five male rhesus monkeys put them in a group let them form a dominance hierarchy Aida feeds be three times B and ever defeats a this is hierarchy now take C and inject C with testosterone give C like so much testosterone like every amygdaloid neuron is growing antlers and that God just enormous so now to see get involved in more fights absolutely is this the pattern that occurs now is see suddenly challenging a and B and rising in the hot absolutely not C never does a thing with a and B what happens instead is C becomes a total nightmare at D and E testosterone does not invent aggression testosterone exaggerated spree existing social patterns of aggression and it turns out it does something even more subtle than that and this is people beginning to realize what testosterone really does is when your status is being challenged testosterone makes you do whatever you need to do to maintain now if you're a baboon and somebody's challenging your status the way you maintain it is you have a fight with them it's anonymous but with your human things can more complicated and for example you can have an economic game where people get status by making generous offers and give people testosterone and they become more generous in the game in other words if you shot up a whole bunch of Buddhist monks with testosterone they would run amok doing random acts of kindness all over the place the trouble isn't that testosterone makes us aggressive the trouble is that we reward aggression with status so readily meanwhile if we're talking about sort of the good side of our behavior the hormone that immediately comes to mind is oxytocin oxytocin is officially the grooviest hormone of the world oxytocin promotes mother-infant bonding pair bonding trust expressivity cooperation generosity give fruitflies oxytocin they become better listeners all sorts of stuff like that oxytocin promotes pro-social behavior oxytocin doesn't no such thing once you look more closely one example of this this was worked on a few years ago in the Netherlands and volunteers there were given this classic problem in philosophy the runaway trolley problem a trolley is broken loose from its brakes is hurtling down the tracks it's going to kill five people is it okay to push one person onto the track who will be killed what will slow down the trolley can you sacrifice one to save five basic utilitarian stuff philosophers have been dealing with the runaway trolley problem since I'm a no Aristotle took his first trolley it turns out how you frame it matters is it okay to push your person versus is okay to pull a lever that dumps the person you get totally different answers from people okay so they give these volunteers the runaway trolley problem and the key thing in this study was they gave a name to the person you were pushing on the track either it was somebody with a classic good-old-boy dutch name like dirt or Peter or something or it was one of two groups that consistently invoke negative connotations in Holland people from Germany oh that's right World War two or people with Muslim names so now you got a choice so are you gonna push Dirk onto the tracks what about Wolfgang what about Mahmud and it turns out you give people oxytocin and they're far more likely to spare Dirk and they fall over themselves to throw Otto and Wolfgang and Mahmud under the tracks there oxytocin doesn't make us more pro-social and makes us more pro-social to people who feel like in us if it's a them and makes us crappier and more xenophobic to them so in both cases we've got hormones affecting our brains or sensory systems but far more subtly than you might think and the problem with testosterone is that we reward status to aggression so readily not a testosterone causes it and the thing about oxytocin is it doesn't make us more pro-social it exaggerated s' this divide between us as and vamps okay so now pushing further back with our behavior what about weeks to months before and the critical thing in this realm is it turns out over that time span the brain changes the brain changes dramatically neurons form new connections they shrivel up old ones brain regions get bigger they get smaller it's the biggest revolution top left it turns out the adult brain and one region makes new neurons completely new neurons under certain sir the brain shows neuroplasticity incredibly exciting stuff with all sorts of fine print there first off amid having the brain having this enormous potential Thunder a plasticity there's limits no amount of neuroplasticity is going to make any of us into a yo-yo ma or no amount of neuroplasticity currently is good to do much for you if your spinal cord has been severed moreover more importantly neuroplasticity is a value-free phenomenon because sometimes neuroplasticity can make you much better at being a saint and sometimes it can make you better at ethnically cleansing villages it's not an intrinsic good or bad now pushing further back how about back to your adolescence and it turns out everything about adolescent behavior is explained by two facts first off your dopamine system is going full blast by the time you're about 11 or 12 second your frontal cortex is half-baked when you're a teenager frontal cortex is not fully online amazingly enough until you're about 25 years old in other words this is why juveniles behave in juvenile ways impulse issues and sensation seeking and novelty seeking and peer effects and conformity and all of that and what's this for our purposes what is this relevant to in terms of that second where you eye there are aren't going to pull that trigger what this tells you is late adolescence early adulthood is when environment is having its bigger this affects what kind of frontal cortex you're gonna have it as an adult and that has a critical implication okay so adolescence is all about dopaminergic maturity frontal cortical immaturity with the critical thing there is if the frontal cortex is the last part of the brain to come online by definition it's the part of the brain least shaped by your genes and most shaped by your experience and environment and it's gotta be that way because what's the difficult subtle doing the right thing when it's the harder thing to do kind of stuff that takes forever to master cultural relativity context-dependent rules thou shalt not kill but it's really good to kill them and you don't lie but this is a good time to lie and hypocrisy and self-serving sty and that no genes are gonna code for that your frontal cortex needs 25 years to master stuff like that hurdling further back how about now back to childhood what does that have to do with the adult brain an adult decision you will make in that one second there as to what to do all of it is built around something that is totally obvious which is childhood matters and different types of childhoods produce different types of adults and the central question of that field is how do different types of childhoods produce different frontal cortexes and different amygdalas and different what are the mechanisms by which early experience has a lifelong organizational effect on brain and behavior now what this brings us into is this insanely trendy field called epigenetics genetics your genes your DNA sequences experience doesn't change those what epigenetic experience changes though is the regulation of those genes when they are activated okay what would this look like amazingly enough it turns out in the world of rat mother's some rat mothers are better at mothering than other rat mothers okay what counts as a good rat mother she picks up her pup a lot she licks up a lot she grooms that a lot this is a wonderful rat mother and it turns out if you are subject as a rat pup to such attentive rat mothering that causes an epigenetic change in a part of your brain and as a result as an adult you secrete lower levels of stress hormones into your bloodstream great book with an interesting implication so because you were groomed and licked a lot as an infant your brain epigenetically shifted and now as an adult you have nice low levels of stress hormones when you are a mother because of those low levels you're gonna lick and groom your kids more and thus this trait is going to be passed on to the next generation not through genes but through environmental experience dependent changes in regulation of genes and the same thing works prenatally you're a rat fetus and you're being exposed to tons of stress hormones why because your mom is stressed and secreting a lot into her circulation which gets into your circulation we get into your brain and causes epigenetic changes such that as an adult your amygdala is going to be bigger and it's going to be more reactive to threat and you're gonna have higher stress hormone levels and as a result when you're pregnant your fetus is going to be exposed to more of these stress hormones in other words we have early environment shaping all sorts of aspects of how the brain and the endocrine systems are put together and most importantly thanks to these epigenetic changes starting during fetal life environment does not begin at birth these changes can be long lasting lifelong even multi-generational ok but now one step further back forget when you were a kid or a fetus how about back when you were nothing more than just a fertilized egg what do genes have to do with it and there's no subject in this whole lecture that's more contentious than the role of a genes and behavior and this is because we live in an hysterically giddy period about genetics these days we've sequenced the human genome they can do it in the evening now if you go into the right like you know McDonald's or whatever the genome with a code of codes the Holy Grail the notion that your genes shape everything that happens in you and the thing is your genes have no idea what they're doing saying that a gene knows for example when it is going to regulate cell biology saying that a gene knows what it's doing is like saying that a cake recipe knows when you're going to make the cake or decides when you were going to make the cake genes don't regulate themselves what regulates genes environment does environment can be very local the local environment in a Cell that's running out of energy and that turns on a gene which makes more of a glucose transporter protein and the cell takes up more energy change an environment alters gene activity and you fix the problem or environment could be on the level of the whole body high levels of testosterone and as a result in this muscle cell certain genes are turned on and the muscle cell grows bigger you put on muscle mass or environment could be environment in the conventional sense you've just given birth you smell your baby and as a result genes are turned on and you start making oxytocin Oh jeans run all of life there this that's you smell your baby's tush and as a result you change gene transcription genes don't really know what they're doing genes are being regulated by environment and the critical thing is different environments regulate the same genes in different ways do not dream of writing down any of this but what we have here are a whole bunch of genes that have effects on behavior only in certain environments for our purpose the most interesting one in red they're a gene called Mao health of monoamine oxidase alpha it's got something to do with this inner transmitter serotonin all that matters is it comes in two different flavors and by all logic one of those flavors should set you up for higher levels of aggression and a huge huge study was done some years ago following 17,000 kids for decades and the answer comes back if you've got the wrong version of this gene you are indeed as a young adult more likely to already have a history of antisocial violent behavior if and only if you were abused as a child if you weren't raised with abuse 0 effect whatsoever in other words it's not what the gene is it's not what the environment is but the interaction between the two in other words genes decide nothing instead they're being regulated by environments efficiently so that it never makes sense to ask what a gene does or an environment does only in a particular context of interaction ok that's great so that tells us something about why jeans and a penguin may work differently in the middle of the Sahara or something but yeah you're not gonna see penguins there but you're going to see humans there and in Antarctica and in tundra and in rainforests and polygamous society is a monogamous and capitalist and socialist there's no species on earth that lives in more different environments thus by definition there's no species on earth that is freer of genetic determination than we are ok so now we're back to fertilized egg that's the end of us but amazingly we got to push further back because to make sense of all of this we after I asked what were your ancestors doing what sort of cultures were they inventing because that's gonna influence how you are going to turn into that adult that you are what sort of cultures did they invent turns out to be very sensitive to what sort of ecosystems they lived in for example across the world desert dwellers are statistically more likely than chance to invent monotheistic religions rain forest dwellers invent polytheistic ones and all sorts of baggage that goes along with that another pattern when you look at humans living in small hunter-gatherer bands the religions they invent involve almost all the time involved gods who could care less what humans are doing it's not until humans are living in sufficiently high density that you're interacting with strangers that you interact anonymously then humans start inventing what are called moralizing gods gods who were watching us and gods who were judging us and gods who are the pair of eyes up there on the bus stop there when we're getting complex enough that we can't do it ourselves or another critical status ting ssin has to do with traditional ways of making a livelihood the original world people are either top left hunter-gatherers top right agriculturalists or horticulturalist or in the center pastoralists pastoralists people wandering the grasslands or the deserts with their herds of camels and cows and goats and all of that and there's a particular vulnerability if you're a pastoralist if you're a rainforest hunter-gatherer bad people cannot come at night and steal your rainforest if you're an agriculturist they can't come at night and steal twenty acres if you're maize but if you're a pastoralist people could come a night and steal your herds rustle your herds there and everywhere around the world pastoralists come up with cultures of honor built around violent retribution warrior classes honor killings vendetta's that stretch for centuries and what is most remarkable is with minutes of birth if you were a child in a culture of honor your mother is speaking to you at a higher volume and holding you for a shorter length of time than if you were a child in one of these other cultures if you were born into a collectivist culture on the average your mother is nursing you for longer lengths of time in your first week of life than if you were born in an individualist culture in other words within minutes of birth everything we've already seen is now being shaped by what your ancestors were doing for a living centuries before in other words ecosystems shaped cultures shape brains shape behaviors and some of these differences are manifest within minutes of birth in other words brains and bodies and behaviors and cultures and jeans all co-evolve finally if we're gotten this far back and we're talking about things like genes by definition we're talking about evolution what does the evolution of behavior have to do with any of this and modern thinking about the evolution behavior is long ago trash the notion that we behave for the good of the species or behave in order to survive we behave in order to pass on copies of genes contemporary thinking about the evolution of behavior is built around three building blocks first one individual selection what organisms do is try to leave as many copies of their genes in the next generation as possible maximizing reproductive success The Selfish Gene concept and this explains a ton of human behavior for example remarkably 16 percent of Earth's humans are direct descendants of djenka scon the most reproductively successful human of all time all sorts of powerful humans act to maximize the reproductive success next building block yes some of the time you pass on as many copies of genes as you can but some of the time an even better way of doing it is helping your relatives pass on copies and genes kin selection and humans have invented a version of kin selection that makes other primates shrivel up with envy we can bequeath our in the real wealth to our relatives there's inheritance we have a way of magnifying differences through generations that way we do kin selection like nobody else out there final building block individual selection or helping relatives or sometimes their selection for cooperating with utter strangers being cooperative altruistic with them as long as they do it back reciprocal relationships of cooperation and we obviously do that on a level like no other species out there forget scratching your back and you scratch mine we've invented barter and economic system all of that in other words the building blocks of modern evolutionary thinking explain a ton about human behavior until you look more closely individual selection and then we have religious sects that are celibate that choose to go extinct like the shakers who don't pass on copies of your genes behaving only for the good of close relatives and then we have blended families with children adopted from all over the planet or reciprocal altruism we will cooperate with strangers if they cooperate back think of this this is a behavior we do which chimps could not possibly make any sense of you're in a foreign country you're going to the airport you're about to leave there you are never going to set foot in that country again no person you see there you will ever set flies on again and as you walk into the terminal you pause for a second and hold the door open for someone everything about the evolution of reciprocity and cooperation says there's no way that could ever become commonplace and that defines us in other words evolution of behavior built around those three principles they explain a ton about social behavior lots of other species and they explain a ton about us until you look more closely ok so what have we gotten to now we've now officially seen one of our behaviors occur and if you want to understand if that behaviors you've got to incorporate everything from one millisecond before to millions of years of selection and evolutionary pressure in other words one can officially conclude at this point it's called located oh great I had to sit through 50 minutes of this to get to that point it's complicated let's try to make that conclusion a little bit more useful it's complicated so be real careful and real cautious and real sure you really understand what's going on if you decide you understand why some behaviors happens especially if it's a behavior that you're judging harshly now for my purposes the single most important thing about all of this is all of these realms of factoids I've been downloading here all of them have one thing in common they change they can change over time they change in response to experience they change in the most fundamental ways over long periods over short periods ecosystems change this is a rock carving of a hippo which was carved 3000 years ago in the middle of the Sahara when the Sahara was lush grassland ecosystems change cultures change in the 18th century the most terrifying people in Europe were the Swedes they spent the whole century rampaging through Europe and then something happened something changed and this is what the Swedish military does now instead they haven't had a war in more than a century cultures change cultures change dramatically most importantly brains change new connections lose old ones expansion contractions brains change behaviors change people change sometimes astounding magnitudes of change occur they could take decades this man John Newton was a British theologian who in his old age played a central role in the abolition of slavery in the British Empire in the beginning of the 1800s and amazingly enough as a young man and John Newton made a living as the captain of a slave ship and after he retired from the sea he spent decades investing in the slave trade and growing wealthy from it until one day something changed something changed celebrated into him that he wrote that his maid famous to him Amazing Grace another version of change that can happen over decades on the left is a man named Zen Jia Bay on the morning of December 6 1941 about to lead one of the squadrons of bombers Japanese bombers that attacked Pearl Harbor he was one of the lead pilots in it and on the right is Zhen Jia Bay to the day fifty years later where as an old man he came to Pearl Harbor where there is a ceremony happening for the elderly survivors of the attack and in broken English he went up to those men and he apologized to them for what he had done so change can occur on that level sometimes change can occur over the course of hours today's one of the most remarkable events in World War one was the Christmas truce of 1914 the first Christmas the first December various powers that be decreed that there would be a three-hour truce along the trenches in France three hours in the afternoon before Christmas Eve so that soldiers from both sides had come out retrieve their dead from no-man's land so the fighting stopped and people came out and retrieved their dead and then they started helping soldiers from the other side carry their dead back and then they started helping each other dig graves in the frozen ground and then they started having ceremonies and funerals together and praying over each other's dead and before it was over with they were sharing Christmas dinner and praying together and exchanging presents and singing and by the next day up and down the trench lines of France German and British soldiers were playing soccer together and weren't keeping score and they exchanged weapons and they exchanged addresses so that they could visit each other after the war was over with and they made vows with each other to shoot over each other's heads so they wouldn't hurt each other and it took the officers arriving two to three days into this and threatening to shoot these men to get them to go back to trying to kill each other and the main point there is all of that acculturation and all of that millet rating millet training and all of that propaganda evaporated in the course of hours as to who counted as an us and who was the them us is us in the trenches all of us in the damn trenches and them as any officer in the back lines who would have his die for their power and that just happened over the course of hours and sometimes change can occur in minutes one of the things that galvanized the anti-war movement during the Vietnam War in the United States more than anything was the me Lai massacre a brigade of American soldiers went into the village of nilai undefended no weapons made up of elderly people and children went in there and killed 350 to 500 civilians mutilated bodies gang-raped before killing killed every animal and there burned the fields and appalling atrocity appalling in part because the US government covered it up for a year appalling because when it finally had to admit it it handed out to still slap on the wrists of the commanding officer and appalling because almost certainly this was not the only instance of that on the right is a man named Hugh Thompson this is the man who stopped the meal i massacre Thompson was a helicopter pilot he was piloting a gunship that was flying over the village and he had gotten reports of shooting they're assumed that American troops were under attack from Viet Cong flew over landed there to see what help he could give got out of the helicopter and saw American troops shooting old women in the head so American troops pulling babies underneath from out of their dead mothers to kill them and this man saw what was happening and at that point there was a small surviving number of villagers huddling at one end of the village and a group of American soldiers coming towards them and this man got in his helicopter and landed it in between the two and he trained his machine guns on the American soldiers and said if you make one more move I will mow you down in other words over the course of minutes he had completely changed who was an us and who is a them and the main point of all of these people is none of them have any brain regions that us that we don't have none of them invented any new types of neurotransmitters they do epigenetics the same way we do the same hormones the same everything they put their pants on one leg at a time the same way we do almost none of them had any indications beforehand that this was going to be someone capable of this sort of extraordinary change so what I think we're left with here at the end is sort of an inversion of that like inevitable santen Jana cliche of those who don't hunt and study history are destined to repeat it well we have here I think is in fact quite the opposite those who don't study the history of astonishing human change and don't understand the science that begins to explain why to make that more likely those of us who don't study that are destined not to be able to repeat moments like these so on that note thank you for your attention and good luck with your own best and worst moments [Music] let's see questions well that's pretty rude well actually that's not rude at all because you know if I'm trying to be a good houseguest what I would say is well if there is some free will you know it's in increasingly boring places and you know if you want to claim it was free will such that you've lost your lower teeth today instead of your top ones instead of the other go for it be happy you know you got free will there in actuality I don't think it's possible to look at this whole range of ways in which our behavior is being shaped by biology I don't see there to be a shred of possibility of freewill sitting in there as far as I'm concerned free will is what we call the biology that hasn't been discovered yet I've absolutely no problem at all with the notion that there's no free will I have vast problems with trying to imagine how are we supposed to live with that conclusion and I have no idea what that should look like but all I know is if we're drunk going to do the hard work to try to get a sense of where that should be accepted is we should probably start with the criminal justice system and worry about flossing somewhere down the line there it's an enormous challenge but there's some domains where it is absolutely essential that we do it because basically the science that informed the current criminal justice system is based on neuroscience from the mid 19th century and that's appalling young if you happen to know the president of Stanford can you kind of mention that but actually I don't know if you paid your bills okay because very few things out there have a hundred percent certainty of you do the work you get the reward and what we hopefully get very good at is sensing where the optimum point is on that curve between effort and likelihood of reward now what people are even better at is manipulating us into distorting what that curve looks like and that's what Las Vegas is we're in actuality you have what a hundredth of one percent of a chance of good but because today you're the lucky one who got the free drink and you're on the penthouse that they put you in that's actually on the second floor and all of that and all of that is to set you up to mistake one chance on a hundred thousand for at about the 50% mark up goes dopamine there ago the life savings we're very good at realizing this early dopaminergic Lee that intermittent reward demands a whole lot of behavior because it's very rewarding we're lousy at accurately assessing exactly what the curve looks like well it depends when my kids are doing great I don't believe that for a second context dependency that's the whole point there Harris is a psychologist who produced sort of the wildly controversial book in the mid 90s that in the most inflammatory form said parents don't matter give me a break but she did a very good critique of a lot of the developmental literature in terms of parental effects what she very legitimately emphasized was how it a surprisingly young age how strong peer effects are on kids enormous ly powerful and where that is never more apparent is in teenagers pure conformity effects are astonishing there for example put an adult in a brain scanner ask somebody okay how do you think of yourself and they think of it and there will be a certain pattern of neural activation now you say how do other people think of you and there's a partially overlapping pattern of cortical and subcortical activation take a teenager and say what do you think of yourself what do people think of you you get the exact same pattern what do I think of myself whatever anybody else thinks of me because I'm gonna go along with whatever thing that's just one measure of it and that's a measure of that frontal cortexes job it is in us as adults to say you know maybe they're actually jerks and you shouldn't like take their opinions to heart and that's all the rationalizing and wait a second type stuff she's absolutely right childhood and adolescence even more so enormous amount of peer effects I I have a question here okay good I have two questions actually the first look what you started okay is that precedent the first question has to do with your discussion of the fear response to the rattlesnake and later you mentioned that that fear response is conditioned so I was wondering if you can talk a little bit about some of the ways that of the fear responses are conditioned particularly with regard to other races and then the second this is not a question it's really a point but you mentioned there were studies where you know adults had a higher amygdala really reaction looking at faces that were different races there than there's there's another similar study but then they assess how much contact these individuals that had with these races over the course of their life and they found that that was inversely correlated so that the more contact they had with other races the lower the amygdala response was and vice-versa good perfect okay so in terms of the first one rattlesnakes what are these get your amygdala going things are innate even the things that are traditionally viewed as innate phobias that we have about snakes and spiders the more technical term is that we show prepared learning for them we are not innately afraid of spiders it takes less aversive okay it takes less it takes less aversive experience with a spider to decide that you're afraid of it then with say like a Teletubby for example we are predisposed towards making some associations more readily than others that's closer to what a phobia actually is so the question becomes do we have prepared learning for considering people of other races to be them's a priori intuitively that makes perfect sense I mean it's such a marker and it's discernible at a distance and all of that but then you think anthropologically for a second and race evolved I don't know 40 50 hundred thousand years ago or so at most somewhere during that period and we've been to monsford on that but most importantly it only has been okay most importantly it's only been I know in the last couple of millennia that your average person wound up within a thousand miles of somebody from another hominid history was not sculpted by encountering somebody from another race who represented as much of an other as you can imagine your whole life he was utterly irrelevant because somebody's entire life was spent interacting with the people from the hunter-gatherer bands at most 2 or 3 valleys away terms of that other issue the amygdaloid response what you get out there is exactly if one was being boringly technical and careful every single time I would have said something during the talk I would have said on the average this is what happens on the average people's amygdala activates when seeing the face of somebody from another race so who are the people who are the exceptions people who grew up in racially diverse neighborhoods and other words skin color is not a criterion for their us to them divide people who have had a close intimate relationship with somebody of another race same exact conclusion okay so good let's put all of us back into kindergarten and we can undo some of the world's animosity in those lines but then wonderful work by somebody at Princeton named Susan Fiske has shown something remarkable forget having to go back to preschool and the diversity in it what Fiske does in these studies is putting somebody in a scanner and you're flashing up the faces there and the usual sort of deal and she instructs people beforehand okay with each face that you see decide yes or no this button or that one decide is this the sort of person who would like broccoli broccoli like a lot of wars have been fought over broccoli this is like totally innocuous broccoli and what are you doing then you're looking at each face and you're imagining them in a market you're imagining them in a restaurant you're imagining them coming home and sitting down to dinner and does this taste good and is it and in other words you're imagining them as an individual and when you individuate people like that the amygdala doesn't activate because you're too busy thinking about if they look happy you're not biting into whatever you're thinking about them as a person and you completely unwire the ask them at that point so on one hand we have the option to go back and put everyone back in kinder the different sorts of neighborhoods but in a study like this this is over the course of seconds you rewire it in other words I think by the fact that we do us them stuff and our amygdala in the course of a hundred milliseconds I think we are incredibly hard-wired to divide the world and to us and them and to not be all the fun all that fond of the them's but it is incredibly easy to manipulate us as to who counts us in us and who counts as of them and put a baseball cap on somebody in the neurobiology is different a hundred milliseconds later and that's the greatest example of that you can imagine there's an experiment being conducted to with transmit transcranial magnetic induction to suppress the amygdala and stimulate the frontal lobes do you think this will work well depends what working counts as but one of the most extraordinary things I mean neuroimaging put somebody in a brain scanner you're getting functional MRIs we've seen what parts of the brain activating different certain it's totally cool but it's correlative this part of the brains active activity correlates with this behavior this emotional state whatever transcranial magnetic stimulation is a means by which you can actually activate or inhibit small sets of subsets of cortical neurons and that is amazing some of the stuff that has come out of that you turn off a part of the frontal cortex temporarily in somebody and they make different sorts of moral decisions you shift how utilitarian they are and runaway trolley type problems and you are controlling their behavior in that case this is mostly just a phenomenal research tool because you're moving away from a correlative relationship to a causal one AHA make those neurons fire and suddenly this person is far more likely to say yeah I push them in front of the trolley that's a strong causal relationship what you can actually do with that down the line is the stuff of dreams and nightmares and everything in between my guess is it's not going to be used in terribly exciting abusive ways anytime soon but a phenomenal research tool [Applause] [Music]

Channel: Stanford Iranian Studies Program

Views: 140,761

Rating: 4.8678679 out of 5

Keywords: iran, iranian studies, robert sapolsky, biology, human behavior, stanford university

Id: GRYcSuyLiJk

Length: 73min 12sec (4392 seconds)

Published: Tue Jun 12 2018

Reddit Comments

[u/meanturing]

Great talk, highly recommend.