Makes Sense - with Dr. JC Doornick - He Was Given 12 Months to Live. Here's What He Wants You to Know About Identity - David Linden - E199

Starting point is 00:00:00 Every once in a while, a guest comes along who completely changes the way that we think about ourselves. We've all heard the debate, nature versus nurture. Were you born this way or did life make you this way? Well, my guest today says that the entire debate is just simply outdated. Dr. David Linden is a neuroscientist at Johns Hopkins University whose career has been devoted to understanding how the brain actually works. So you can imagine how excited I am about this guy. Have you noticed that the world that we live in has been doing most of the thinking for you? That your beliefs, perceptions, reactions, fears and doubts have been shaped by unsolicited outside noise?

Starting point is 00:00:44 How easy it's been for you to slip into that default sleep walking mode and label it as life and reality. Yeah, that ends here. Welcome to the Make Sense with Dr. J.C. podcast. This is your opportunity to start. Thinking for yourself, reclaim control, and step back into that role as the shock caller and dominant force of your own reality. It's when you change the way that you look at things, that the things that you look at begin to change. So let's wake up. Let's rise up. And let's make sense of why and how shift happens.

Starting point is 00:01:19 Makes sense. We're going to talk about why identical twins become different people. while your personality may have begun forming before you were even born, and whether free will will survive modern neuroscience. And later, we're going to discuss something deeply personal. David was told that he only had months to live after being diagnosed with a very rare cancer. Years later, he's still here. We're going to be exploring what facing mortality taught one of the world's leading neuroscientists about gratitude, identity, and what really matters. This is going to challenge what you think you know about yourself.

Starting point is 00:02:00 Let me tell you what I like about David. As many of you know, one of our core tenets of the Make Sense ecosystem is that it's who you are that determines how well what you do works. And I believe David's words and his work validate this. Also notable, I really admire people who are willing to destroy their own fields over simplifications. Most scientists spend their careers adding tiny pieces to existing knowledge. David looked at one of the biggest ideas that we've grown up believing, nature versus nurture, and basically said, we've been asking the wrong question.

Starting point is 00:02:34 What I also appreciate it about David is that he doesn't just stop at neuroscience. Welcome to the Make Sense with Dr. J.C. podcast, Mr. David Linton. So honored and privileged to have you here. I've been a big fan, the stuff that you write about, pop into YouTube and watch anything about David Linton, and it's just amazing. You've been on so many different shows. and I just love somebody that has the ability to never be satisfied with the status quo of their industry and just ask different questions. And I just think it's a breath of fresh air to read a book like unique.

Starting point is 00:03:08 So my first question that I always ask people on the show, which will put you at a disadvantage if you've never watched the show, is what does it like to be David Linden these days? What does it like to be David Linden these days? Well, you know, that's quite a good question. This crucial story that's relevant to this. Five years ago, I was diagnosed with a serious cancer called synovial sarcoma, and I was told by my oncologist to expect to live for six months to 18 months. Well, you know, I mean, I have a lot of sympathy for oncologists because there, you know, people demand that they give these lifespan estimates and they can't always do it. The cancer I have is a rare one. And it usually manifests in the synovium, which is the lining of the joints. But in my case, it manifests in my heart. So that's very unusual. So it's hard to know what the prognosis or something is because there's so few cases of it in the medical literature. But anyway, I was told to expect to die pretty soon.

Starting point is 00:04:08 And then I didn't. So I had to have a massive surgery to debulk the tumor. But the tumor had grown into the wall of my heart and became part of its structure. So if they removed that, I'd have a hole in my heart and I'd be dead right away. So there is to this day a walnut-sized tumor in the wall of my heart. And every six months, I go in for a scan. And so far, every six months, they say, well, it's not growing and it hasn't spread. So enjoy another six months of life.

Starting point is 00:04:36 And so when you ask, what's it like to be David Linden, you know, right now, I would say it's been a blessing. I'm happy to be on this side of the dirt. I am seizing every opportunity to ring as much as I can out of this time. have been granted. I, in a very, very, very aligned and ironic way can relate because I come to you two weeks after receiving a diagnosis that I have cancer. Oh, no. I'm sorry to hear that. Well, but I was so excited to bring that to you after I had read your book, not as peculiar and odd as yours. It's kidney cancer, but it's really, really fascinating and I'll bring it up later because prior to that, I had no idea how long I had to live. Nobody could tell me.

Starting point is 00:05:20 And what's interesting is as soon as you get that diagnosis, the conversation starts to come up. And what I find so fascinating and you use the word blessed is that there's a lot of perks, finally realizing, which we should do anyway, that we're terminal. You know, that there is, because what it does is it forces you to live in the present moment, all these things that we try so hard to do. So a lot of people ask me, how are you doing? Oh, my God, this is so terrible. And I said, I hope that this doesn't bother you, but I feel really, really good.

Starting point is 00:05:50 very, very blessed. So we'll tie that in later. I want to get into a little bit of the neuroscience and unique, but before we get into the science, I'd love to know what question kept bothering you enough that you felt that you had to write the book unique. Well, so the book unique is about human individuality and how it arises. And I think that the thing to realize about this question is that it's a deeply political question. It gets very quickly, you know, not just to like fun, cute things like eye color or, you know, can you, can you, do you like the smell of cilantro or not?

Starting point is 00:06:31 Or, you know, the things that are, you know, fun to talk about at parties. But it gets very, very quickly to issues of race and sex and gender and the way decisions are made and policies are made. So to me, writing it was very much a political act. I felt that the science of human individuality has been very confused and not very well, always very well expressed, either by scientists or by people who want to use it for their own political answer. And the history of human individuality has, in the science world, a nefarious past, it has been used to justify eugenics, for example, and is used to this day to justify aspects of, of racism and sexism. So for me, I was really most motivated politically to write this book. It wasn't so much that, oh, there's something new that happened the last day scientifically that I just got to tell

Starting point is 00:07:29 because there are new things happening about human individuality all the time, but it was the slow accretion of those sort of coupled with really a political motivation. Was the question primarily devoted to the whole nature versus nurture thing? Because I mean, I think that's what the most fascinating part of individuality is, is like how much of it is actually unique to the person, you know, maybe even I know you speak about things that are happening before we're even born, versus mother, father, teacher, preacher for formative years and things like that. Was that just uncertain to you? And is that where you wanted to go with it? Well, it's not so much that it was uncertain to me, but I felt like it was uncertain to the world.

Starting point is 00:08:08 And it called on me to be an explainer. And I actually hate phrase nature versus nurture. And the reason, I'm not ragging on you, everybody uses it. The phrase, by the way, was coined by Francis Galton, so-called Darwin's Bulldog back in the late 19th century. And it's been around in some form ever since. And the reason I don't like nature versus nurture is that, you know, in this case, nature means genetics. Well, that's all right. So what? That's just terminology. But nurture makes it seem like the only experiences that matter in determining your individual, individuality are social experiences. Nurture is a word we use just the way we say.

Starting point is 00:08:49 How are you affected by your family, your friends, your mentors, the people who surround you in social interaction. And while that is an important influence on human individuality, the much more broader and inclusive term would be experience. So experience in your life molds you, but not just social experience. You are molded by the diseases that you have fought off, even those that were fought off by your mother, while you're in uter. You are molded by the temperature in the first few years of your life and by the foods you eat and by the bacterial community in your gut and other parts of your bodies. So experience is a much better term than nurture because it subsumed nurture within it and then includes all these other things that are so deeply important to our individuality.

Starting point is 00:09:36 And then the other reason I don't like it is because if I were to place Nasor v. nurture, I would say genetics coupled with the... experience throughout life that is as broadly considered. But then there's a third thing that people don't talk about. So imagine we've got monozygotic twins, what people like to call identical twins. And I think if anybody has ever actually been around identical twins, even as infants, you know, they're not really identical, actually, either in their bodies or in their personalities. If I take two babies that share the same DNA because they resulted from a fertilized egg then splitting before development. They've got essentially the same DNA, but they don't come out exactly alike. Like,

Starting point is 00:10:22 if we put them in a scanning machine and we looked at the volume of their livers, they wouldn't have identical volume of their livers. In spite of the fact, they've got the same DNA and they develop lying right next to each other in the womb. And so had very similar, if not identical experiences during that period of development. Nonetheless, they're not born exactly the same. Well, where does that come from? Like, where is the third thing besides nature and nurture? And the third thing besides nature and nurture is the pseudo-random nature of development. And so the DNA that instructs the proteins that are crucial for forming us as individuals, your genome, all of your genes put together, all 20,000 or so human genes, plus the spaces in between that are also important, they are not a blueprint. They're not like a wiring dial. diagram for your brain. It's not like, you know, the 86 billion neurons in your brain, each of which have about 5,000 different connections, that we could take an electrical circuit diagram and say, okay, this one connects to this one, and this one connects to this one. And if we could just make it on a big enough piece of paper, we could say, all right, well, this genome will produce this brain down to the last wire. No, these instructions are kind of vague. So the instructions the genome makes in the brain might say to neurons when they're developing. Now neurons have long, thin information sending ends. And so the instructions, you know, called axons from which they release neurotransmitter typically. And so axons can go in different places to connect to other neurons.

Starting point is 00:11:49 So, you know, your DNA might be saying, okay, hey, you neurons that use the neurotransmitter acetal coline in the medial septum, which is a brain region, half of you go up towards the surface of the brain, the other half of you cross the midline and go to the other side of the brain. But in one identical twin, maybe 40% will cross the midline. And on another one with the exact same DNA, maybe 50 or 60% will. across the midline. It's not a precise instruction. It's an approximate instruction. And that pseudo-random nature of development that comes from these instructions in the DNA being approximate

Starting point is 00:12:24 rather than precise is the third thing that gives rise to individuality beyond nature and nurture. And is the reason why so-called identical twins aren't really identical even at the moment of birth, even before they've had the chance to accumulate different experiences in their life outside the womb. So what does this say for individuality? Is it something that we're just for whatever reason so entrenched and inclined to figure out, but it's unfigureoutable? Because of the, I mean, I believe you're saying it's nature experience and randomness. So add the word random into something and it says, hey, don't spend too much time on that. Well, what it means is that, you know, even if I knew your genetic sequence entirely and I

Starting point is 00:13:11 not only knew it, but had a heavy, a deep understanding of it, which we don't have, because there are many genes. We don't understand what they do, and we don't understand what all their variants do. Even if I have that, and even if I knew the experiences you're going to have in your life, there's a third thing that would get in there and introduce some variability. Now, the important thing to remember is that we can't speak generally. There are some traits that are 100% genetically determined. Like, every human has either wet or dry earwax. And whether you have wet or dry earwax. It doesn't matter what happened to you in utero. It doesn't matter what foods you eat or where you grew up or how your parents raised you or what kind of football coach you had when

Starting point is 00:13:50 you were a child. Your earwax is 100% determined by your DNA and it's 100% determined by a single gene in your DNA. And on the other hand of the scale, there are traits like speech accent. Now, I'm not talking about like the qualities in your speech or like do you have a high or a low voice or is it nasal or clear. I'm talking about your accent, your speech. Your speech. speech accent is entirely determined by your experience of language in the first years of your life, particularly from your peers. This is why people who emigrate to a new country, for example, as children usually don't speak like their parents. They usually have the accent of their peers where they grew up in school. And so it turns out that speech accent has no heritable qualities

Starting point is 00:14:34 whatsoever. Your DNA has zipped to do with it. So these are the two ends of the spectrum. Here is one trait, speech accent, no heritability. Here's another trait, earwax type, 100% heritable, but most traits fall somewhere in between. Either physical trait, like, for example, height in a affluent country where we get enough food to eat and we're not battling terrible infectious diseases, is in the ballpark of 80% heritable. So that's pretty heritable, but not 100% heritable. Most behavioral trait, like extroversion or shyness or like the so-called ocean traits that the psychologists use the acronym for agreeable-thvenous, neuroticism, openness, conscientiousness, et cetera. Those traits, usually they have a heritability of somewhere between 20 and 40 percent.

Starting point is 00:15:24 So while you can find human traits, either physical ones or behavioral ones, that are either all heritable or not heritable, most traits are somewhere in the middle. And they vary quite a bit. The other thing that I think is important to realize is that when I say something like height is 80% heritable, I gave you the caveat that that is the number for affluent population. Now, if you live in a place, like let's say you're a poor person living in rural India and you don't always get enough nutrition and you're battling communicable diseases and then maybe you have to work with toxic chemicals in your farm fields because that's the only option you have, then actually your height is less heritable. than it would be from someone in Western Europe in the United States because you can't live up to your genetic potential for height because you're not getting the nutrition or these other things that I said

Starting point is 00:16:14 that are negative. So these estimates of heritability for traits vary a bit depending on what population you're talking about. And generally, they vary between, you know, affluent versus less affluent societies and individuals. Yeah, see, this is what I mean when I was talking about some of the things that I like about your work is that, you know, you can look at the field that you're in and just accept it or say, well, you know, there's a little, there's more to it than that and go deeper.

Starting point is 00:16:44 And I love that kind of work. Well, thank you. That's right. I should say, I should tell you that these things that I'm saying, they're not radical. In other words, this is more or less the consensus among geneticists. It's not like I'm a firebrand by saying this. If you asked most biologists, how does human individually happen, you'd get an answer that's pretty close to what I just told you. It's not a radical idiosyncratic view. It's actually the majority.

Starting point is 00:17:09 So therefore, what was your goal with writing unique? If someone picked up unique today and read it, what would be the biggest misconception that you would hope disappears by the time that they finished the book? Well, I think the biggest misconception is that I think people tend to overestimate the heritability of a lot of traits. Like a lot of people, if you would ask them, well, okay, intelligence is a trait. How heritable is intelligence? A lot of people would say, oh, it's really heritable. It's going to be like 80 percent. And it's way, way, way less than that, for example. So I guess, you know, the main thing I want people to know is that the heritability of a trait varies enormously from trait to trait, and that the heritability varies on circumstance. So the same way that a height is a

Starting point is 00:18:01 trait that is more heritable when you're more affluent. Intelligence is also a trait that is more heritable when you're more affluent. In the same way that if you are poorly nourished and fighting disease and don't get a chance to play and explore as a kid and have toxic things in your environment that you can't live up to your genetic potential for height, it also makes it harder to live up to your genetic potential for intelligence. as well. So in that way, these traits are very, very similar. They come about as a mixture of heritable and experiential factors. Some of those experiential factors being social, some of them being

Starting point is 00:18:45 non-social. They have an aspect of the randomness of development in them, and they're not the same for all populations. These estimates of heritability are not the same for all population. And so if you're asking, what am I hoping that like when people close, you know, finish the last page of unique, and someone asks them for a couple of sentences about what do they learn. I'm hoping they say something roughly like what I just said. You know, it's interesting because you've got me thinking, and it makes sense to me why we would be so attached to saying something's heritable because part of that is implying that it's, no, it's not my fault.

Starting point is 00:19:21 I'm like this. Like if there's something wrong with my car, I believe in the manufacturer. But it seems that you're saying that that there is, that is a factor in some cases. but it seems like you're putting the locus of control back over to the person and saying there's a lot of things that you control. Well, right. It depends on the trait. You have no control over your earwax type. You don't have any control over your eye color. But you do have some control over your features of personality and over your, say, susceptibility to addiction or things of that nature. And we should say also that, you know, when I make these heritability efforts, And, you know, like I might say, like, for example, like a good thing is like, what is the heritability of major depression?

Starting point is 00:20:06 All right. Well, you know, a good estimate is about 40%, 30% that ballpark. All right. So that's a significant chunk. It's not everything. It leaves a lot of room for experience, both social and non-social experience to contribute. But the other thing is that doesn't mean that for any individual, that's the formula. And others, there may be people who have been dealt such an unfortunate genetic hand that even with the most beneficial experiences, they're probably going to get major depression because they just got a bad set of gene variants. And it may be on the other side of the coin that are some people that are so resilient because they got a good set of gene variant that even the kind of experiences in their life that might produce major depression and other folks wouldn't produce it in them. So I think it's important to realize that, you know, when I bowed out these numbers about the estimated heritability of certain traits, particularly behavioral traits, that's for a population. That measurement is not for an individual. And for an individual, it can be very, very different, as I just said.

Starting point is 00:21:07 I'm sure that's a bit unsettling to people that are now saying, Sue, you mean I have to try, Sue? In some ways, I mean, maybe it's not the earwax that they're going to try, but, you know. Well, you know, I mean, I think we've got to be really compassionate, right? You know, so I really like this comedian from many years ago named Mitch Hedberg. And he said, he would get up in front of events. He'd say, well, alcoholism might be a disease, but it's the only disease you can get yelled out for having. Otto, damn it, you're an alcoholic. Otto, damn it, you have heart disease.

Starting point is 00:21:40 Like one of these doesn't sound right, you know. Yeah, you know, they're both diseases. So when you say alcoholism is a disease. And when you say alcohol, the propensity for addiction, including alcohol, alcoholism, which alcoholism is one type, has a genetic component. That is not relieving people of their individual responsibility. It's not just saying, oh, well, all right, you got Delta's gene. So go be an alcoholic and be bad to people in your life, treat yourself.

Starting point is 00:22:07 And like, it's all fine. It was just your genes like you're not responsible. It's not saying that at all. There's still individual responsibility, even when traits have a heritable component. Like to go back to heart disease, well, okay, you may have a genetic pre-exposition for heart disease, but, you know, still, you should eat a heart-healthy diet and exercise and take your statin drugs if your doctor prescribes them. And if you don't, it's on you. And that's another funny thing.

Starting point is 00:22:31 You know, I mean, first of all, I come family line of alcoholics and I couldn't become an alcoholic if I tried. I tried in college. And I just over-liked alcohol at all. And then the other piece of the irony is that there's not a lot of cancer in my family. And I've lived an unusually healthy life. I don't drink. I don't smoke. I exercise.

Starting point is 00:22:51 I'm actually 96 years old. You're looking great, grandpa, yeah. But I mean, I'm 54 and I'm in the best shape of my life, but here I am getting cancer. So, you know, that would prompt my brain to say, well, that's got to be heredity. Well, no, the thing to realize about cancer is there are gene variants that predispose you for cancer. That's absolutely true. And I think some of them you're probably familiar with. There are some famous gene variants that dispose women to breast or ovarian cancer.

Starting point is 00:23:21 for example, that are very well known. And there are other ones that increase your probability a bit, maybe not as dramatically as some of those. And there are somewhere you're almost certain to get it. But cancer is just unrestrained cell growth. And you've got cells that it's their business to divide all the time, like the cells that, you know, line your gut, they divide all the time. The cells that line your respiratory system, they divide all the time. You got to make new ones and shed the old one. That's how biology works. And so when cells divide, there's a chance you'll make an error and you'll accrue a mutation that makes cells start dividing in an uncontrolled manner. And that's what cancer is. And most of the time that happens, the body can shut it down with the immune system, but sometimes not.

Starting point is 00:24:06 So most cancers are just on some level bad luck. You got a cell division that just happened in a single cell that just happened to go wrong. and it just so happened that your body couldn't kill it off. And so it'd become a cancer. And this can be influenced by environmental toxins. It can be influenced by going out in the sun without sunscreen and UV rays, mutating the DNA in your skin cells. You know, it can be influenced by genetic predisposition. But there is a whole, for most cancers, there's a whole lot of randomness in it. So even though you've led an unusually healthy life and are feeling great,

Starting point is 00:24:46 in midlife and you got cancer, it doesn't necessarily mean that you had a genetic predisposition. And whether I understand what it is or not, I still have it, and it's my new part of my journey. I want to talk about individuality and when it actually begins, because I've heard you talk about your birth, before birth, you know, even conception. When does individuality begin? Yeah, well, individuality starts in fetal development. So if you were, look at newborns, you can already see differences between genetically identical ones. So that suggests, I mean, certainly, for example, we know that if your mother is fighting off a viral infection during a certain period during pregnancy, that the incidence of your chance of becoming schizophrenia

Starting point is 00:25:38 or autistic is raised. And there are a number of these. So for example, we know this, the pandemic flu of 1918, there were a lot of women who were pregnant during that terrible winter. And we know that the babies that were born who were being carried in utero during that terrible flu season, that they grew up to be one inch shorter in height. Sounds like not very much, but in a whole giant population of millions of people, that's a highly statistically significant effect. We know that the incidence of schizophrenia was higher. autism wasn't really identified with that name yet, but sort of post hoc, I think we can infer that the incidence of autism was higher, and that there are a number of other somatic conditions that were higher. So certainly, experience in utero, it starts there. But, you know, then these experiences accrue throughout your life. And of course, early development, you're unusually plastic. Your brain, for example, is growing and being formed. You're going from having about a 400 cubic centimeter volume. brain as a newborn to having about a 1,200 cubic centimeter brain as an adult, and that, you know, happens over the first 20-odd years of your life. So that's a period where you're unusually

Starting point is 00:26:54 susceptible to things in your environment, whether they be social or, you know, what you eat or toxins or the way you behave. The other thing to realize is that genes and environment interact. So, you know, you've talked a little bit about athleticism. Let's give an example. Let's say you're a kid and when you're five years old, you realize that you're faster than the other kids on the schoolyard. Probably that's going to make you more motivated to do sports when you're growing up. And then you're going to practice and that practice will make you better at sports. So in other words, the genetic advantage of being quick then is influencing your behavior and then you're having experience because you practice sports and get better at kids who didn't do sports as much. And so that's an example of a gene environment interaction.

Starting point is 00:27:41 Another example of this is that there is a genetic disease called phenyl ketanuria or PQU. All babies are tested for it. So you can't metabolize the dietary amino acid called phenylalanine. So you're born with the mutation. You can't metabolize phenylalanine, but you don't get any symptoms unless you eat foods rich in feralaline. And if you adopt a low phenylalanine diet, then you won't have complication. That's another example of a gene environment interaction. The gene alone isn't enough to do it.

Starting point is 00:28:11 gene plus eating foods rich in phenylalanine is enough to do it. It's an interaction between the two. So yeah, your individuality starts being formed before you're even born and it never stopped. We're being formed by our experiences to our last breath. And God, we live in a world today where people are unconsciously consuming so much data without even knowing how that it's affecting them. I have an interesting vantage point because that we've adopted a little girl. So I have two boys that are by blood and we adopted my daughter, who

Starting point is 00:28:41 who's my pride and joy. She was about six when we adopted her. And she's 16 now. And she is, looks like my boys. I mean, she, she is a Dornick, my last name, like true. True. So I've had the opportunity to either, I've had some sort of a role in mutating her genes or this is just, or if she's just, it's all behavior. So I've, I've been able to see a learned behavior kind of a modification to the point where, like, I watch her from a distance and she does a lot of the same things that my boys do and that make them unique and think that. So it's fascinating. Well, yeah, no, I mean, absolutely parents are important. Siblings are important. So, you know, your daughter has been presumably raised in a similar way and eaten similar foods and live in the same community and have the same,

Starting point is 00:29:29 you know, economic advantages as your son. So, you know, all those things are important and are going to make them much more similar than if they had grown up in different families. Let's talk a little bit more about food. Let's talk about cilantro. Okay. You mentioned that briefly before, but how is it that two siblings, one of them can kind of grow up thinking that they like the smell or taste of cilantro and the other one can claim that it tastes like soap?

Starting point is 00:29:57 Yeah. Well, so that's a good question. So, in other words, food preferences are very, very plastic and determined by experience. And you only have to think about cultures a little bit. Like, you know, if you grow up in Thailand, you're going to like spicy food. You're going to like chili, right? Not everyone growing up in the United States likes chili. Some people do and some people don't.

Starting point is 00:30:14 If you grew up with them, you're much more likely to like them. So we're very, you know, our food preferences are very determined by our experiences. In the case of cilantro, one big contributor is that there is a very specific odor receptor in our nose. So it's not actually in your tongue. It's in your nose. You know, a lot of taste is actually smell. I mean, a lot of flavor is actually smell. It's not just the five basic tastes on your tongue, sweet, sour, salty, bitter, umami. It's also

Starting point is 00:30:39 all the smells that that produce the complexity of flavor. And we now know that certain genetic variant in a particular odorant receptor give rise to the soapy perception of cilantro flavor. And of course, because you inherit one from your mother or one for your father, you know, you roll the dice every time you have a child. Right. If you have identical twins, presumably they're going to have the same cilantro odor scent. But for conventional siblings or, of course, adopted siblings, you know, it could be anything. It could be, you could have two of the soapy kind or one soapy, one non-sopi or two of the non-sopi kind. And I actually don't know whether the cilantro soapy trait is dominant or recessive.

Starting point is 00:31:22 I'm sure people out there know that. I just don't happen to have that piece of trivia at my fingertips right now. But, you know, that is a very simple trait that's pretty easy to understand genetically. I like to say about food that we're the anti-pandas. Giant pandas, they only live in one environment in South China. They only eat one thing, bamboo. That's it. That's it.

Starting point is 00:31:45 That's their whole thing. Humans, on the other hand, we live everywhere from the tropics to the pole, everywhere in between, and we can survive on all kinds of different foods. We're generalists. We can eat a meat-only diet. We can eat a vegetarian diet. We can eat this plant, that plant, this meat, that meat. We can survive in many, many different environments by not being too picky about what we eat

Starting point is 00:32:10 and by having the ability to metabolize and make use of a lot of different foods. So in that sense, I like to say that humans are the anti-pandas. And it also puts the lie to people. There are people out there in the world who say, oh, well, we evolved to be carnivores. You know, and if you eat an all-meat diet, you're just doing what your ancestors had. No, you're not. I mean, you're only doing that if your ancestors lived in the Arctic. Most places, your ancestors did not have an all-meat diet.

Starting point is 00:32:36 And if we look at the shape of your teeth, you're not, your teeth aren't there to eat an all-meat diet. They're there to eat an omnivorous diet. We've got some rippers for meat, and we've got some grinders for grains and veggies. And the idea that we evolved to be obligate carnivores is nonsense. This is an interesting question to ask a guy like you with your research is because you just, you bring up a very, very hot topic right now that has created a trillion dollar industry. It's like all of these different diets that people are saying are for everybody.

Starting point is 00:33:09 So what is your take on the, do you have a general piece of advice on a healthy diet or is it different for everybody? Yeah, I have some very particular advice and the advice is very boring. eat the Mediterranean or Japanese diet that the nutrition specimens have been telling you to do for the last 30 years and couple it with exercise including load-bearing exercise and aerobic exercise. That's the advice and this is the consensus medical advice. This isn't Lyndon's special secret sauce. What I will tell you, don't bother.

Starting point is 00:33:42 There's no supplement that you need unless you're in a very special situation. If you're a bodybuilder, okay, maybe a little creatine, a little protein powder. If you're putting on massive amounts of muscle, if you're putting on massive amounts of muscle, If you want to eat a vegan diet, yeah, you got to watch your protein. Maybe there's some B12 you should take. If you're pregnant, you should take folic acid and also be careful about your protein. If you are breastfeeding, there are certain things in your diet that you want to be specially attentive of. For most people who don't fall into that special category, and they're just looking to be generally healthy, a Mediterranean or European fish, lean meat, omnivorous, veggie, healthy diet is one.

Starting point is 00:34:21 You don't need to go all meat. You don't need to avoid seed oils. You don't, there's nothing wrong with seed oils. They're perfectly fine. You know, you don't need to eat beef tallow. You don't need to buy anyone's supplements. All that stuff is only enriching people. Eat a fish, eat a walnut, exercise, and you're good.

Starting point is 00:34:40 So, I mean, I have you here, and there's too much irony, is when you found out that you had cancer, did you change your diet? No, I didn't. I was already eating a healthy diet. Which was Mediterranean. Yeah, pretty much. I mean, you know, I fall down every once in a while, and, you know, I've been known to eat a Heathbar Klondike for dessert, but all things in moderation. You know, I eat a pretty healthy diet, and I did that before cancer, and I'm doing it after. And I don't take supplements. I think it was Deepak Chopra that said that the world's most, you know, stocked and vast pharmacy is the human body, meaning everything's already in there. And you just have to, you know, live a certain way where you allow it to have. to manifest. The idea of not taking supplements is saying that I don't need to put anything new in. Yeah. Well, you know, every once in a while, for those cases I said, you know, there's a few cases

Starting point is 00:35:33 where supplements are special cases where supplements are a good idea and there's certain disease states where supplement is a good idea. If you have kidney disease, a lot of times, you know, your doctor will tell you, we'll take a little extra vitamin D for in your case, that would be good. You know, it's not like one should have religion against supplements. But 99. 99.9% of the supplements that I see being peddled by people right now only serve to enrich the peddler. There's really no basis for them. And some of them are really risky and dangerous. I wouldn't take rapamycin, for example.

Starting point is 00:36:04 You know, there are lots of longevity enthusiasts who are all about rapamycin because rapamycin will make mice live older. Well, it also suppressed their immune system. So no rapamycin for me. You know, there's a lot of stuff that's being peddled. And some of it, undoubtedly, there's going to be a few things in there that are going to turn out to be beneficial, right? We've got to keep an open mind.

Starting point is 00:36:22 You know, we shouldn't have absolutely no supplements, never, ever. A few of those things are going to be turned out to be viable, but most of them are not. I think that the biggest problem that we face is certainty. When you're certain of something that you're immediate or something, any of these things, are that you're a supplement taker. There's nothing wrong with being open and curious and trying everything. If you can have a Klondike, Heathbar ice cream, and take supplements for a while, too. it's the certainty that builds up a wall of, you know, not accepting anything else.

Starting point is 00:36:53 So I always like to say, if I could go back and teach myself something sooner, it would be to allow myself to be more open and curious and uncertain of things. I think that's a great mindset. And basically what you're talking about is the mindset of the scientist. Yes. Right. In other words, scientists are famous for not being certain. The scientific process is like it's not like every scientific paper is right or adds to our understanding. You know, sometimes people get things wrong or they, it's like, you know, sort of understood the wrong way or the interpretation is wrong.

Starting point is 00:37:31 But in the long term, science progresses because scientists are always questioning the status quo. Somebody publishes something. Say, well, can I replicate it? Can I interpret it? Is there another possible explanation? It is always subject to falsification. This is what the philosopher Carl Popper famously said. If it's not falsifiable, it's not science, then it's just faith.

Starting point is 00:37:53 And I don't want to say just faith to denigrate faith, because faith has its own importance and should be respected. But it's in a different magistrarium. It's in a different realm than when science is. When you have faith, you say, well, this is what I believe, and I believe it because I believe it. And maybe my parents believe it or my friends believe it. And it's a mark of my identity. I like to hang out with other people who also hold with this. And that's great.

Starting point is 00:38:17 That's its thing. But science is a different beast. In science, you are always questioning the present explanations. And nothing is ever beyond questioning. I mean, there are times in scientific history where it seemed like things were all wrapped up. Like, you know, Newton described fundamental things in physics about bodies in motion and in rest and certain things about optic. At that moment, people are, oh, God, you know, we kind of tied this up real nicely. And, you know, and then some other people came along and said, well, you know, there are things you can't just, you know, there are things we can observe that we just can't explain with Newtonian physics.

Starting point is 00:38:52 We've got to posit relativity and we've got to posit subatomic particles and we got to posit these forces that Newton didn't imagine. And that's how science progresses. And it's not like right now at this particular moment in time, we figured it all out. And like now we can just rest on our loyals. No, it isn't. you know, this is just another moment in science, and there are things that we, that are the consensus in science now that are going to turn out to be wrong. And that's okay, because that's the way the scientific process works. So I'm old, right? I started training as a neuroscientist

Starting point is 00:39:28 45 years ago, and there were things, I would say maybe a third of what I was taught, 45 years ago, has turned out to be wrong. Roughly, I'm ballparking here, you know. I mean, you could argue about that number, but, you know, roughly speaking, about a third of what I was taught about the brain turned out to be wrong. Was it wrong or like the scientists did something better come up? At the time you knew that it was right. Well, sometimes it was dead wrong. And sometimes it was kind of right, but a partial explanation. And sometimes the observation was right, but the interpretation was wrong. So I'll give you an example. Like one of the central acts that happens in brain cells is the release of neurotransmitter the way one neuron signals to another neuron. And that in almost all cases happens by

Starting point is 00:40:16 little voltage-operated holes in the membrane proteins called voltage-gated ion channels opening, and calcium ions rushed from the outside to the inside of the cell, and they trigger neurotransmitter release. And I was told that, well, that happens because calcium ions come in, and they bind to the negatively charged polar head groups on lipids, on the vesicles containing neurotransmitter, on the presnaptic membrane on that. What makes the vesicle fuse and its content squirts out into the synapse and that's how neurotransmission happens. It was a plausible theory. It turned out to be dead wrong. It turns out they're actually special calcium sensing proteins in both the vesicle and in the presynaptic membrane. And it's those interactions that trigger it. So there's a case, well, you could say,

Starting point is 00:40:59 well, the part of it that says the calcium was involved was right. The actual mechanism was dead wrong. It wasn't just a little wrong. It was dead wrong. So, you know, I was taught that every kind of neuron has only one kind of neurotransmitter. That turned out to be dead wrong. Neurons can release multiple kinds of neurotransmitter. One neuron can release multiple kinds of neurotransmitter. That's now very, very well established. So, you know, there are things that were fundamental to the way why I was taught that we are not, in a few weeks when I go into teach my students at Hopkins, I will not be teaching them that. That's so interesting. How about this? How would you answer this question? with all of the advancements of science and technology,

Starting point is 00:41:38 but also human awareness and consciousness, and in my observation seems to be improving a little bit. Are we getting writer in our, you know, so like, does the kid that go to school at Hopkins now, is he going to be doing a podcast interview in 20 years saying like, oh, you know, Professor Lyndon told me this turned out to be dead wrong. Is it going to be the same ratio or are we getting better? Are we getting right?

Starting point is 00:42:01 Well, you know, undoubtedly, some of the ideas we have, have now are going to turn out to be wrong. Absolutely no question. Whether that is different than the one-third I gave you from 45 years ago, I don't know. It's hard to say it. Let me put it this way. Science is cumulative. In the long-term science progresses. It might take a step forward and two steps back and then three steps forward. It's staggering like a drunken person's walk, but eventually it moves forward. So our understanding of the natural world now is superior to our understanding of the natural world 40 years ago, definitely. But are there things in our understanding of the natural world now that will turn out to be mistaken?

Starting point is 00:42:41 Absolutely. No question. We shouldn't be so arrogant to think that we have it all figured out at this moment because we don't. And I don't think any scientists would claim that we do. And any scientists that would claim that we do, I would argue with them. I teach, and this is a part of my book as well, I'll send you a copy of it. I teach a form of cognitive distancing that has got a great lesson in it. And when people, when I invite people to pause before they claim to be right and they let their

Starting point is 00:43:12 program knee-jerk reflex, you know, come into play, distance yourself by saying, hmm, and there's a specific way to spell, hmm, it's H-M-M-M, and what that stands for is, haven't made up my mind. So all of the people that are subjected to my work goes to go around. Of course, my wife says, don't, hmm, me. But what happens is it opens up this conversation of allowing the brain or the voice in your head to say, well, JC, what else might be true? And I just find, once again, this is kind of how we started off our conversation. I just think that that's such a healthy thing to do to allow yourself to not have to be right. Yeah, I think you're onto something important there.

Starting point is 00:43:59 And what I would say is that this is kind of the cousin of empathy, right? In other words, when you don't think of yourself as always right, you're imagining that the truth of others has validity. And that is kind of the first step to be in. Or nobody has validity. Right. Yeah, right. Well, that's even better.

Starting point is 00:44:20 And that's, you know, kind of the buddistic path, which I also respect. Yeah. What questions about human individuality still keep you awake at night? Well, I mean, there are a lot of things we really don't understand. I mean, so one of them would have to do with sexuality, right? So-called sexual orientation. I'm not talking about who you like now, not who you feel yourself to be, right? So who you like, there is a small, heritable component to it.

Starting point is 00:44:53 it's about estimated to be about 20% in men and maybe a little higher, 30, 40% in women. And we don't understand why that's different. And then so you say, well, okay, what's the rest? Well, it seems that hormonal influences in utero can have something to do with it. So, for example, we know that female fetuses who are exposed to androgens, to male hormones in utero, are more likely to be attracted to women when they grow up and become sexual. But still, that doesn't account for much. And so the vast majority, not only of the general categories, like who's straight or who's

Starting point is 00:45:36 gay or who's by or who's A or, you know, all the different ways that people like to label their sexuality, not only do we, is there much that we don't understand that, but the details, like, why do we like this person and not that person? or why do we have this thing we like to do in bed more than that thing we like to do in bed? That is very, very poorly understood. And so, I mean, that's a crucial aspect of individuality that really molds how people live, that we have, for which we have a very poor understanding. One last question I had for you is, if you were to rewrite unique today, as an author,

Starting point is 00:46:11 I know that I always want to rewrite my books, if you were to rewrite unique today, what new chapter would you add to it? Well, yeah. Is that the new book coming out? Well, you know, you always struggle with things that you left out. It's not so much that I would add a new chapter, but there are some things where the science has progressed and I would like to change it. So, for example, I reported an estimated heritability for general intelligence or 50 to 60 percent. And the best indications now were that is significantly lower, that there were some flaws in those studies.

Starting point is 00:46:47 and the best estimates for the heritability of general intelligence in affluent populations is now more like in the ballpark of 25%. And I think that's important because the heritability of intelligence is a deeply political issue that really influences people. I mean, you know, you've read in the news, there are people who, you know, particularly wealthy people, particularly wealthy guys who, you know, think that they're so smart and their genes are so great that, you know, they want to have a gazillion. children. You know, I'm not going to mention any Elon Musk names or anything, but this is a phenomenon. And, you know, I think if people understood that the herability of intelligence is really more like 25%, you know, maybe, maybe the wisdom of that approach would diminish. Interesting. Good answer. Okay, a couple of lightning round questions. I love these because I just want to see what your brain pops out. What is the biggest myth in neuroscience? I would say the biggest myth in neuroscience. I would say the biggest myth in neuroscience. is that the brain sits around waiting for something to happen.

Starting point is 00:47:51 So, for example, I was taught that the brain is kind of sitting there idling, do, do, do, do, do, do, not very doing much. And then some information comes into the senses. You hear something. You see something. Something touches your skin. You feel something. And then only then does your brain, you know, those signals are passed into your brain and your brain shoes on them a little bit.

Starting point is 00:48:11 I learned something. It makes a decision. And then you contract some muscles or secret a hormone in response. hormone in response and that's behavior in response to sensation. And that's not true. It turns out what we really are understanding more and more is that even when you're spacing out, even when you're kind of staring into the distance, you don't feel like you're thinking about anything, our brain's a prediction machine. Our brain is always built to try to anticipate the near future, to figure out what's going to happen, particularly in the next few seconds, but also in the next few minutes. And that doesn't

Starting point is 00:48:46 get turned off, even when you're distracted, even when you're tired, even when you're facing out. So this idea that the brain is fundamentally reactive and only springs into action in response to the sensory experience, that's, I would say, a false idea. The brain is always idling, the brain is always predicting the future. I think that's such an important thing for people to understand. What is one trait about yourself that has surprised you? I would say one thing that has one trait that's changed since my cancer diagnosis and treatment is that I have a much stronger emotional response to like music and stories and even sappy shit on TV. I find that I will tear up at manipulated soldiers coming home videos on the internet or, you know, people being

Starting point is 00:49:40 reunited with their pets or, you know, other stuff that's like deeply designed to manipulate my emotions that I could kind of shrug off before and now it gets me every time. And so, you know, that was a transformation that changed me. And, you know, I don't know quite how it happened, but, but it did. And my wife teases me about it, which is good. I am with you on that. I find myself at 54, that's turned 55. Yeah, getting getting much more emotional about, you know, the soldier coming home and surprising his kids and things like that. You know, like I have to watch that stuff online by myself. Me too.

Starting point is 00:50:23 What is one book that everybody should read right away? The book that everyone should read right away is called Dr. Tatiana's Sex Advice for All Creation by Olivia Judson. And this is the funniest science book that's ever been written and also the science in it is really good and important. And the conceit she adopts is that she is a sex advice columnist for all kinds of different animals. And so people write in, Dear Dr. Tatiana, I'm a Madagascar stick insect female. And this male has been on my back mating with me for a week now. Why does he persist in doing this and how do I get him to stop?

Starting point is 00:51:03 And Dr. Tatiana will write back, well, honey. You know, the reason he's doing that is not because he's so in love with you, but he knows as long as he stays up there, no other male can come along and inseminate you. and so that increases his chance of getting his genes into the next generation. So she uses this really clever and humorous approach to actually get to some very important deep insights into the evolutionary biology of sex. So it's probably my favorite science book of all time. Okay, so here's your last question. What is one scientific question that you hope gets answered before you go?

Starting point is 00:51:38 I would say, how is memory stored in the brain? right this is the question that I spent most of my scientists for a career working on at a very cellular and molecular level and we learned a lot but there's so much that we really really really don't understand and one of the things that's both fascinating and also puzzling right now is it seems like the changes the physical changes in the brain that store memories move around over time they're not just locked in in one place like in a chip in your computer they move around throughout your life. And why that is and why that's a good idea, there's lots of different ideas and people argue about them. Some people say it's a feature.

Starting point is 00:52:21 Some people say it's a bug. I think it's probably a feature. And how it is that you can still have stable memories when they move around to different parts of your brain, it's a total fascinating mystery. So that's the question that I would love to see answered, but I am unlikely to live long enough to see that answered. Can you tell us anything about what's coming?

Starting point is 00:52:40 Yes, so my new book will be called Entwined, The Real Science of Mind, Body Medicine, and it will appear in mid-2020, and it will all be about how the two-way communication happens, how the body talks to the brain and how the brain talks to the body. And this has implications for all of medicine, but I have specific chapters on cancer and on depression and on pain and also on appetizing. That's what's coming up. How could people begin to stalk you? Do you have a reference? Well, they can go to Davidlinden.org. So Unique is book number five. So if you're interested in the sense of touch, I wrote a book called Touch. If they're interested in pleasure and reward, I wrote a book called The Compass of Pleasure.

Starting point is 00:53:31 If they're interested in Brain, Arab Evolution, I wrote a book called The Accidental Mind. And if they'd like to read a collection of essays by interesting, prominent, neuroscientists that I edited, there's a book called Think Tank. So all these are, are good places for folks to get started. And that's all that at Davidlinden.org. They can get in touch with all those. Yes. Okay. Or naturally on the Amazon world. David, thank you so much for being here. I mean, just from somebody that just consumes a lot of information and, you know, your work really gets me thinking. And I, appreciate that because we live in a world that is kind of quietly doing the thinking for us.

Starting point is 00:54:16 And you bring up these topics that make me go, hmm. Indeed, yes. Well, thank you very much for having me on. It's been a lot of fun. Yeah, we'll definitely have you back when the new book comes out. And thanks so much for being here. Hi, this is David Linden and this podcast Makes Sense. That's it for today.

Starting point is 00:54:36 To support the Make Sense with Dr. J.C. podcast, be sure to subscribe, like, and share, as well as follow the Make Sense substack for free daily quotes, live streams, and blogs. And remember, learning without action is just another form of distraction. If something hit home and you learn something today, give it away. That's the only way it's going to stay. See you next time. Makes sense. If you like the show, please take a moment to rate, review, and subscribe. It really does help the show to grow.

Starting point is 00:55:15 Thank you for listening.

Makes Sense - with Dr. JC Doornick - He Was Given 12 Months to Live. Here's What He Wants You to Know About Identity - David Linden - E199

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