He Was Given 12 Months to Live. Here's What He Wants You to Know About Identity - David Linden - E199

Makes Sense - with Dr. JC Doornick

Dr. David Linden, a neuroscientist at Johns Hopkins University, shares his profound insights on identity, individuality, and the neuroscience of self. Diagnosed with a rare cancer with

Key takeaways

• The debate between nature and nurture is outdated; individuality arises from a combination of genetic predispositions and early-life experiences that shape neural development.
• Identity is not fixed but evolves dynamically through brain plasticity, with memories constantly reorganizing across different regions.

Main topics

• Nature vs. nurture debate
• Identity formation before birth

Notable quotes

'The entire debate is just simply outdated.'

'I'm seizing every opportunity to ring as much as I can out of this time I've been granted.'

Conclusion

Dr. David Linden's journey—from facing terminal illness to redefining identity through neuroscience—offers a powerful reminder that

Transcript preview

Speaker 2 (0:00) 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 Well, my guest today says that the entire debate is just simply outdated.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? How easy it's been for you to slip into that default Speaker 1 (0:47) sleepwalking mode and label it as life and Speaker 2 (0:50) reality. Yeah. That ends here. Welcome to the Make Sense with Dr. JC podcast. This is your opportunity to start thinking for yourself, reclaim control, and step back into that role as the shock collar 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. Speaker 2 (1:24) We're going to talk about why identical twins become different people, why 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. 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. What I also appreciate about David is that he doesn't just stop at neuroscience. Welcome to the Make Sense with Dr. JC. Speaker 1 (2:41) podcast, Mr. David Linton. So Speaker 2 (2:43) 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 Speaker 1 (2:52) amazing. You've been on so many different shows and Speaker 2 (2:54) I just love somebody that has the ability to never be satisfied with the status quo of their industry and just ask questions. Speaker 1 (3:03) And I just think it's a breath of fresh air to read a book like Unique. Speaker 2 (3:08) 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 is it like to be David Linden these days? Speaker 3 (3:18) What is 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 they're, 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. 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. And so when you ask, what's it like to be David Linden? You know, right now I would say it's been a Speaker 2 (4:42) blessing. I'm happy to be on this side of the dirt. I Speaker 3 (4:45) am seizing every opportunity to ring as much as I can out of this time I've been granted. Speaker 2 (4:51) 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. Speaker 3 (5:02) Oh, no. I'm sorry to hear that. Speaker 2 (5:03) 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. 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. 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. 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? Speaker 3 (6:06) 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? 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 Speaker 2 (6:37) and Speaker 3 (6:37) sex and, and gender and the way decisions are made and policies are made. So to me, it. 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 Speaker 1 (7:02) their Speaker 3 (7:02) own political ends. And the history of human individuality has, in the science world, a nefarious past. It has been used to justify eugenics, for Speaker 2 (7:13) example. Speaker 3 (7:14) and is used to this day to justify aspects 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, 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. Speaker 2 (7:38) 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? Speaker 3 (8:03) Well, it's not so much that it was uncertain to me, but I felt like it was uncertain to the world, and it called on me to be an explainer. And I actually hate the phrase nature versus nurture, and the reason, I'm not ragging on you, everybody uses it. The phrase, by the way, was coined by a man named by Francis Galton, so-called Darwin's Bulldog, back in the late 19th century. And it's been around in some Speaker 2 (8:27) form ever Speaker 3 (8:28) 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 Speaker 2 (8:37) just terminology. But Speaker 3 (8:38) nurture makes it seem like the only experiences that matter in determining your individuality are social experiences. Speaker 2 (8:46) Nurture is a word we use just the way we say. How are you affected by your family, your friends, your mentors, the people who surround you in social interaction? Speaker 3 (8:55) 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 were in utero. 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 body. So experience. is a much better term than nurture because it subsumes nurture within it and then includes all these other things that are so deeply important to our individuality. And then the other reason I don't like it is because if I were to place nature versus 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 Speaker 1 (9:58) I think Speaker 3 (9:58) if anybody has ever actually been around identical twins, even as infants, you know they're not really identical, actually, either Speaker 2 (10:06) in their Speaker 3 (10:07) 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 Speaker 2 (10:19) DNA, but they Speaker 3 (10:21) don't come out. exactly alike. Like if we put them in a scanning machine and we looked at the volume of their livers, they wouldn't have identical volume Speaker 2 (10:27) of their livers in spite Speaker 3 (10:28) 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 Speaker 2 (10:45) nature and nurture? And the third thing besides nature and nurture is Speaker 3 (10:49) 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 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, Speaker 2 (11:23) and this one connects Speaker 3 (11:23) 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 Speaker 2 (11:32) kind of vague. Speaker 3 (11:33) 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 called axons, from which they release neurotransmitter typically. And so axons can go in different places to connect to other neurons. So, you Speaker 2 (11:49) know, your DNA might be saying, okay, hey, you neurons that use the neurotransmitter acetylcholine in the medial septum, which Speaker 3 (11:56) is Speaker 2 (11:56) a Speaker 3 (11:56) brain Speaker 2 (11:56) region, half of Speaker 3 (11:57) you grow up towards the surface Speaker 2 (11:59) of Speaker 3 (11:59) the brain, Speaker 2 (12:00) the other half of you cross the midline and go to the other side of the brain. But Speaker 3 (12:03) in one identical twin, maybe 40 % will cross the midline. And on another one with the exact same DNA, maybe 50 or 60 % will cross the midline. It's not a precise instruction. It's Speaker 1 (12:15) an approximate instruction. And Speaker 3 (12:17) that pseudo-random nature of development that comes from these instructions in the DNA being approximate 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 Speaker 2 (12:36) the moment of birth, Speaker 3 (12:37) even Speaker 2 (12:37) before Speaker 3 (12:38) they've had the chance to accumulate different experiences in their life outside the womb. Speaker 2 (12:42) 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 unfiguratable? 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. Speaker 3 (13:04) Well, what it means is that, you know, even if I knew your genetic sequence entirely, And I 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 had 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. Speaker 2 (13:27) Now, the important thing to remember is that we can't speak generally. There are some traits that are 100 % Speaker 3 (13:34) 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