EP. 139: ABOLISHING DEATH

Nov 27

WITH ARIEL ZELEZNIKOW-JOHNSON, PHD

A neuroscientist discusses cryonics and the science of life extension — along the way exploring whether there is an “ideal” lifespan, the neurological basis of human identity, and what ultimately gives life meaning.

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Episode Summary

Variations of cryonics — the long term storage of human beings, usually at low temperatures — have long been featured in science fiction. In stories involving space travel, it’s often used as a solution for long-duration journeys. But increasingly, this is not just the stuff of fiction anymore.

The prospect of preserving ourselves, potentially indefinitely, forces us to ask some of the most profound questions we have ever faced: are we meant to transcend the boundaries of our mortal lives? What does it mean to be alive? If life can be extended, what happens to its meaning, urgency, and beauty? These questions, by turns technological, philosophical, ethical and even spiritual, are what we explore in this episode.

Ariel Zeleznikow-Johnson, PhD is a neuroscientist who studies the nature of conscious experiences to better understand how we can preserve cognitive function. His book The Future Loves You: How and Why We Should Abolish Death (2024), explores the viability of delaying death and its societal implications. Over the course of our conversation, we discuss the science of human preservation, definitions of life and death, broader questions about how we derive meaning from life, whether or not the finitude of human experience is essential to our conceptions of a well-lived life, our social contract with future generations, and more.

Ariel Zeleznikow-Johnston, PhD is a neuroscientist at Monash University, Australia, where he investigates methods for characterising the nature of conscious experiences. In 2019, he obtained his PhD from The University of Melbourne, where he researched how genetic and environmental factors affect cognition. His research interests range from the decline, preservation and rescue of cognitive function at different stages of the lifespan, through to comparing different people’s conscious experience of colour.

By contributing to research that clarifies the neurobiological, cognitive, and philosophical basis of what it is to be a person, he hopes to accelerate the development of medical infrastructure that will help prevent him and everyone else from dying.
In this episode, you will hear about:
• 2:44 - How Dr. Zeleznikow-Johnson became interested in the future of longevity
• 6:00 - Dr. Zeleznikow-Johnson’s definitions of “life” and “death”
• 14:29 - Why Dr. Zeleznikow-Johnson thinks that believing death is inevitable is a form of “learned helplessness”
• 17:52 - The level of faith one would need to have in the future of technology to consent to cryosleep
• 24:16: - Whether the finitude of human existence is essential to its meaning
• 29:05 - Whether every death is an inherent tragedy
• 30:25 - How the limitations of the human brain could impede longevity
• 33:16 - The ethical dilemma that would arise due to the financial costs of this technology
• 36:30 - Why Dr. Zeleznikow-Johnson is confident that cryonics will be successful
• 46:42 - The core thesis of Dr. Zeleznikow-Johnson’s book The Future Loves You
• 50:15 - Whether immortality is a desirable objective
Henry Bair: [00:00:01] Hi, I'm Henry Bair.
Tyler Johnson: [00:00:02] And I'm Tyler Johnson.
Henry Bair: [00:00:04] And you're listening to The Doctor's Art, a podcast that explores meaning in medicine. Throughout our medical training and career, we have pondered what makes medicine meaningful. Can a stronger understanding of this meaning create better doctors? How can we build healthcare institutions that nurture the doctor patient connection? What can we learn about the human condition from accompanying our patients in times of suffering?
Tyler Johnson: [00:00:27] In seeking answers to these questions, we meet with deep thinkers working across healthcare, from doctors and nurses to patients and healthcare executives those who have collected a career's worth of hard earned wisdom probing the moral heart that beats at the core of medicine. We will hear stories that are by turns heartbreaking, amusing, inspiring, challenging, and enlightening. We welcome anyone curious about why doctors do what they do. Join us as we think out loud about what illness and healing can teach us about some of life's biggest questions.
Henry Bair: [00:01:02] Variations on the idea of cryonics, the long term storage of human beings, usually at low temperatures, have long been featured in science fiction movies involving space travel from Alien to Interstellar often use cryosleep as a solution for long duration journeys, but increasingly this is not just the stuff of fiction anymore. The prospect of preserving ourselves, potentially indefinitely, forces us to ask some of the most profound questions humanity has ever faced. Are we meant to transcend the boundaries of our mortal lives? What is the capacity of the human brain to survive our efforts at its preservation? If life can be extended, what happens to its meaning, its urgency, its beauty? These questions by turns technological, philosophical, ethical and even spiritual are what we explore on this episode. Ariel Zeleznikow-Johnson is a neuroscientist who studies the nature of conscious experiences to better understand how we can preserve cognitive function. His 2024 book The Future Loves You: How and Why We Should Abolish Death, explores the viability of delaying death and its societal implications. Over the course of our conversation, we discuss the science of human preservation, definitions of life and death, broader questions about how we derive meaning from life, whether or not the finitude of human experience is essential to our conceptions of a well-lived life, our social contract with future generations, and more. Ariel, welcome to the show and thanks for being here.
Dr. Ariel Zeleznikow-Johnson: [00:02:42] No, it's a pleasure to be here.
Henry Bair: [00:02:44] As we discussed in the introduction, the idea of cryonics, of preserving people in order to revive them at a later time is not new. It's often seen in science fiction, but that's what it's been fiction. But you have taken an intellectually scientifically grounded approach to studying how this can actually be done. What motivated you to dedicate your career to this topic?
Dr. Ariel Zeleznikow-Johnson: [00:03:08] Essentially, when I look back at historical medical progress of how we've gone from having very little liquid work centuries ago to today, where we have hospitals, we have medicine, we have surgeries, we have so many things that we can use to extend and improve people's lives. I've always been fascinated by how is this going to progress into the future? Like, what do we expect to become possible as the decades and centuries continue? And as I have looked backwards, and as I've read fiction and scientists ideas of what could be possible going forwards, what I always found a little bit disheartening is being born now and living now, instead of perhaps living at some point in the future when the technology will have improved and when I become sick, or my friends and family become sick, there's more that we can do about it. Now, there has been one idea, though, in science fiction, which is this idea of cryosleep or cryostasis, this possibility that maybe, even if we can't cure or prevent someone's medical issues at the moment, there might be some way to put them into stasis and take them out at some future point. Once medical science is advanced, or at least to pause aging for a period of time. It's been around, I think, since at least the early 20th century, and particularly since the 1960s onwards or so. What I was fascinated by, though, is I'd never really seen any sort of like, rigorous philosophical, scientific analysis of the idea.
Dr. Ariel Zeleznikow-Johnson: [00:04:43] Was it totally far fetched, or is it something that maybe could actually work at some point? There's certainly circumstantial evidence that elements of it might be possible, like there are some small creatures which can freeze and then be revived later. And increasingly we've been able to use the technology for things like IVF and like the freezing down of embryos to then thaw them out and implant them later. But with a whole human, could it ever be made to work? And the more I thought about it, the more I thought, well, the implications are quite profound because we have I think it's something like, um, roughly 1% of the world's population dies each year. This is millions and millions of people, an enormous tragedy that at the moment we have to accept. But maybe if technology like this could be made to work, maybe there could be something that could be done about it. And the future medical advances still to come would be able to help people today through that sort of mechanism. I essentially became obsessed with this, particularly as it ties in with my interest in neuroscience generally about what is it that makes us who we are? How do our brains function? How does consciousness function? All of these sorts of things. So I think it's a huge question, but I think that gets to it.
Henry Bair: [00:06:00] And that's great because you've given us a lot of threads to tug on, like I want to I want to learn all about if this is possible, what are the challenges? Should we be trying to do this like I'm sure I hope we get into all of that, but I want to start really basic because I think this is, counterintuitively, a tricky concept to expound upon. And it's this what is your definition of life and what is your definition of death?
Dr. Ariel Zeleznikow-Johnson: [00:06:25] So those are two potentially notably different questions. And I focus much more on death than on what life is. So maybe I'll start with death and then we can come back to life if we want to. Sure. So when we think about the death of people, I think it's interesting to take a little bit of a historical perspective. So prior to the mid 20th century, there was essentially no more formal definition than someone dies when they stop breathing and they stop moving around because once someone stopped breathing, that was the end of them. But as we started to develop technologies like mechanical ventilators to assist with breathing, cardiopulmonary bypass machines to assist with heart functions, and today, when we have things like extracorporeal membrane oxygenation or ECMO, which can essentially replace someone's heart and lungs for a period of time, it became increasingly clear that we as a community, and specifically as a medical community, needed a more sophisticated definition of death. So in the US, in 1980 or 1981 or so, there was the introduction of the Uniform Determination of Death Act, which was broadly adopted throughout the US and which defines a person as dead based on irreversible cessation of all circulatory and respiratory functions or irreversible cessation of all functions of the brain.
Dr. Ariel Zeleznikow-Johnson: [00:07:46] Now, the first part of that is clearly a little sketchy when we have things like ECMO. So most of the time these days, we focus on irreversible cessation of all functions of the brain when we're defining an individual as dead. The problem is that there are issues with that definition for a few different reasons. The first is that if you look at brain dead patients who are left on life support, you can see that in the brains of people who we would normally consider brain dead, there's often still isolated areas of brain function remaining, particularly like pituitary functions, hypothalamic functions. Some like regulation of hormones or body temperature. So that's to show that like already at the moment, we're declaring people dead, even if they haven't quite lost 100% of all brain functions. On the other hand, in the same way that irreversible loss of cardiac functions became increasingly reversible over time, we are very slowly starting to do the same for brain damage, where we have increasing implants that can deal with things like spinal cord injuries or restoration of blood pressure regulation to people. And I expect that technology will continue to improve over time. So that really makes unclear like what exactly it is.
Dr. Ariel Zeleznikow-Johnson: [00:09:07] That's irreversible loss of all brain functions. Like where is irreversibility? And doctors have noted and scientists have noted the problems with this definition. There's even, I think, an editorial in nature in 2008, which talks about how doctors are obeying the spirit, but not the letter of the law when it comes to pronouncing patients dead. And so when I read more about this, and when I thought more about this as part of my research, I came across some definitions of death. Rather than being based on the irreversible loss of brain functions. Nonspecifically that talked about, well, what's really important is what makes a person who they are. Their personal identity. Not the loss of their ability to regulate their blood flow or their ability to maintain their body posture, but the loss of their memories, the loss of their personality, the loss of their goals and desire. And so, based on these philosophical definitions that have been provided on defining death as the loss of personal identity, that's the one that I feel like the community is really moving towards over time. And that's what I think is the most philosophically, rigorously defensible position for defining the death of a person.
Henry Bair: [00:10:19] Well, in some ways you're actually answering what life is, too. You're saying you're implying, like life is actually more than just functioning parts of the brain. It's more than just brain perfusion or a pituitary gland that is functioning. Right. Yeah. You're indirectly saying that life is personhood. It's identity, it's memories, it's relationships. It's all those things for a.
Dr. Ariel Zeleznikow-Johnson: [00:10:39] Person at least. I mean, obviously, you can get philosophically technical about what it is to be a living cell. A living organ. A living organism. The same for the death of a cell, an organism. But I think when we're thinking about people, as opposed to amoebae or bacteria or single celled organisms, personhood and personal identity is what we're really concerned by, right?
Henry Bair: [00:11:00] Because, like, if someone took my cells and we can do this and cloned it, and it grew a new me, it would be genetically identical to me. I would not see that as life extension because it's not my lived experience in that person's brain. I wouldn't count that as like a success in terms of life extension, right? Yeah.
Dr. Ariel Zeleznikow-Johnson: [00:11:17] I don't think an identical twin would be pleased. I mean, I'm sure in a situation where an identical twin was dying, their fellow twins surviving would still be good, but they wouldn't see it as their survival. So yes, I agree.
Tyler Johnson: [00:11:30] So let me ask though, what about situations which, and this of course is enormously common, where people slowly lose their identity. Right. So when we think, for example, about something like Alzheimer's disease in effect, and we've spoken about this with multiple guests on the show. In effect, Alzheimer's disease slowly erases a person's identity over years or in some cases, even over decades. Right? And so while I am sort of intuitively drawn towards the definition of saying that to be alive is to have a preserved and recognizable identity, and death comes when that identity ceases to be recognizable or ceases to cohere. It does beg the question of does that mean that a person who is slipping into dementia at some point, even if they are, you know, out and walking around that they have already died?
Dr. Ariel Zeleznikow-Johnson: [00:12:35] Yeah, that's a really important and really profound question to think about. I see the two ends of the spectrum are clear, and then the in-between is is where the difficulty lies. So on the one hand, if someone suffers just a tiny amount of brain damage, they get a concussion. Clearly we don't think of that individual as dead. On the other hand, if someone has suffered such sufficient brain damage, their cortex is destroyed, their brainstem is destroyed, their memories are gone. They'll never be conscious again in that side. We're pretty clear that someone has died. Where in between, though, I think is very unclear. The amount of damage that's required for someone to be lost, for the person to be lost is it's more of a blurry continuum, and I think that's inevitably what you have to think about when you start thinking through the details of exactly what losses are required for someone to die, or how much change a person can take while still being the same person. Now, obviously, that question is like very legally and socially and personally important. And I alone am definitely not wanting to say like, this is clearly where the line is. It's a thing that individuals have to think about. Doctors have to think about, society has to think about altogether. But I do think it is the case that we can have some clarity at the extremes. And if you have someone who is heart is still functioning but unconscious, memories gone, everything gone, definitely dead. Where before that point is, I mean, this is what we need to be discussing, but it's certainly the case that it's not, for example, just me who thinks about this and is concerned by this. There are surveys of doctors that say that there are levels of damage before the legal definition of death that many of them would consider already essentially dead.
Henry Bair: [00:14:29] So in your book, you write that death is not inevitable. It's a solvable problem. Well, yes, I concede that this is an attitude shared by some doctors. I think it's safe to say that most of us in medicine don't necessarily think of death in and of itself as a problem. We do everything we can to delay death to make sure that patients die comfortably. But we don't think of death itself as something that needs to be solved. You describe this attitude as learned helplessness, which is quite provocative. We often have palliative care doctors on the show, whose main message is that we should not be artificially prolonging lives, especially if it means more suffering. Can you tell us more why you think the belief that death is inevitable is learned helplessness?
Dr. Ariel Zeleznikow-Johnson: [00:15:17] I'd love to, but I want to make clear at the start, I think palliative medicine is very important, and I also don't think we should be extending life if it just means extending suffering. My question is, can we get around the suffering and actually very much on the idea of getting around the suffering. So an example I use in the second chapter of my book is that these attitudes about, oh, maybe we shouldn't be trying to extend life. Maybe we should just be accepting death are actually remarkably similar to an attitude that medicine used to hold about surgical pain. So prior to the middle of the 19th century, if a patient underwent surgery, there was very little from an anesthetic and an analgesia sense that could be done for such a patient. And that was terrible because people had immense pain when having tumors removed, or any of the other life saving surgeries that were still necessary back then. What was I find disturbing, and I think many of your listeners will find disturbing, is that it's not that all medical professionals in this time point said, well, it's truly awful that you have to undergo this pain, but you need this procedure to save your life. There were people and there are records of people saying removal of pain from surgery is unnecessary, or the pain is actually good for the patient or in some way part of the healing process.
Dr. Ariel Zeleznikow-Johnson: [00:16:35] And in 1848, when the first demonstrations of anesthesia actually started to occur, even for the first few years, there were still people saying, this is an abomination. Anesthesia shouldn't be removed from painful procedures, and it wasn't for several years after that, this viewpoint was essentially entirely removed. And then we got to the point today where although anesthesia is still can be dangerous, it is something that we see as an integral part of medical practice these days. And I think what changed, and the reason why I labeled this as learned helplessness is because for centuries and millennia, there was nothing that could be done about pain in surgery. And so it provided perhaps some comfort to people to think that the pain was necessary, or at least to accept that the pain was necessary, such that when the technology finally evolved to do something about it, people were still stuck in this mindset. And I think essentially that's the relationship we have with the idea of death today, where because it's historically always been an inevitability, we conceive of it as always going to be an inevitability. And we don't consider always perhaps, what technology really could do something about it.
Tyler Johnson: [00:17:52] So I have to admit that there's a part of me that feels like there's this sort of ironic aspect of the project that you're proposing, which is that this idea of putting people into cryosleep, because we believe that there will be technology that can render them something like effectively immortal at some point in the future, just feels to me like an awfully big leap of faith in the ability of technology to do sort of what we hope and suspect and maybe kind of want to argue at some point will be possible, even though right now, I mean, certainly we have made enormous progress over the last hundred years in extending human lifespan. But even now there are people talking about the fact that that seems to have leveled off and that if you, you know, sort of I mean, you can look at specific changes that came in the early 20th, early 20th century in terms of the advent of antibiotics and then the advent of vaccines and then certain hygienic practices, and more recently, arguably, in terms of things we can do for the heart and for cancer. And those have unquestionably led to enormous gains in average human lifespan. But even now, that seems to be leveling off to some degree. So doesn't it seem like, I don't know, a little bit much to take this leap of faith that okay, yes. But then if we put people into Cryosleep at some point in the future, we'll be able to render them effectively immortal.
Dr. Ariel Zeleznikow-Johnson: [00:19:22] Certainly. I mean, at the extremes, I don't have a proposal for a technology that could render someone truly, inevitably immortal. Like, totally outside the ravages of time. As far as I can tell, the heat death of the universe will still come for us all eventually. But I would point out that, like there are organisms that live substantially longer than humans do, which gives like some boost to the idea that we may be able to live for longer. So, for example, there are some whales that can live for 200, 250 years, some tortoises that can live for 200 250 years. I think there's a sharks that can live maybe 400 years. So certainly the the 80 something years of what humans currently do is something that there are natural examples of extending and improving upon. Now, what I'm proposing is a technology that would be able to put someone in stasis and maybe take them out of stasis at some point when future medical science had advanced and was capable at that point, of giving people more time, exactly how much more time? I can't say exactly. And that would be dependent on the technology of the time, but I think there's not good arguments for why it wouldn't, in principle, be possible to give people much more time than we have today. Even if, as you point out, the idea of infinite time or it like being truly removed from all possible damages beyond what should ever be theoretically possible.
Tyler Johnson: [00:20:48] Okay, so let's take as a given that it's more precise to say, rather than you believing that we will effectively render people immortal in the future. I understand that you're actually saying that we will be able to greatly extend the lifespan, and so, in effect, we don't have to believe in a coming version of immortality. We just have to believe in incrementally better technology, such that if you put someone into cryosleep and then wake them up in 100 years from now, that maybe they can live an average of 200 years rather than an average of 75 years or whatever. So okay. Fair enough. But even then, if you want to put someone into a state of cryosleep for a long enough time that when you wake them up, it will have been an effect worth the effort of keeping them asleep, because they'll be able to live longer enough than, you know what would have happened if you had just let them live naturally. That still, it seems to me, involves an awful lot of faith in the idea that you can put someone into such a perfect state of what amounts to, I don't know, perfect preservation such that nothing is breaking down, nothing is dissolving. Memories are not slipping away. The inner parts of the body are not malfunctioning or dehiscing or, you know, it's like you're sort of almost stopping entropy in its tracks for some very extended amount of time, so that then in the future you can make them up. Doesn't that still seem like a pretty great leap of faith, or placing a pretty great amount of faith in technology that we don't even have yet.
Dr. Ariel Zeleznikow-Johnson: [00:22:31] Maybe it might be worth being a little more precise about what I'm advocating for then, which might help answer that question. So essentially, I'm advocating that we use a preservation procedure. We provide access to that to those who are currently terminally ill, so that these individuals, should they choose to use it, can be preserved with a combination of chemicals and cold temperatures that essentially stop their bodies from decaying. It places them in a state where everything in their brain that encodes their memories, their personality, all those core aspects of their self are held in stasis. As a result, with the idea that we would expect future medical technology might be able to revive them and restore them to health. Now, I agree with you. That's that's a very tall technological order, the revival pot in the future, and the means to do that are far beyond current abilities and seem laughable when we consider how imprecise our current precision medicine is and how much progress we need to make to get there. But the core argument I make in the book is that as long as you keep a person in stasis, you can by that time you have the time you need for medical technology to progress, and then you've sort of got two different forces against each other. One is like, yes, it seems really, really hard. And we see all these medical trials failing. We see all the progress that would need to be made and how difficult that is. But on the other hand, we've made huge progress in science and technology and medicine over the past few centuries, and it seems very odd to me to predict that that will just stop or asymptote off entirely, and that it won't continue to improve into the future, to the point where really, these revivals might be possible.
Tyler Johnson: [00:24:16] So our listeners who have been listening for a long time have heard me reference previously the television show The Good Place. So the Good Place is this sort of a funny but also deceptively philosophical show in which characters are asked to, in effect, fix the afterlife so they show up in what they initially think is heaven. It turns out that it's actually hell, sort of. And then they go through a series of things where they have to sort of escape from hell into heaven and then find. But then once they get there, they find that heaven is not all that heavenly, and they're asked basically to fix heaven, to try to figure out what heaven is really supposed to be like by the architects who put it there in the first place. The reason that I bring this up is because they go through the multiple iterations of trying to sort of fix heaven, and then they get to they make it into a place where it seems like it's really great, and people are really starting to enjoy being there, but they still can tell that something is missing. And the thing that they finally decide is missing is that heaven has no end. And one of the sorry spoilers ahead, but the sort of, uh, poignant ending that you eventually arrive at is that they install this sort of a portal that leads out of heaven.
Tyler Johnson: [00:25:45] And the show is sort of ambiguous about whether it leads to another plane of existence or people just cease existing. You know, you never really learn that. But the point is to say that the show heavily implies that the thing that finally brings meaning to their heavenly lives is precisely the fact that they know that those lives will end. And whatever you think of the afterlife or not, an afterlife, and whatever you think of that television show or of religious ideas in general or what have you, there is a pretty strong philosophical tradition that part of what makes life beautiful and meaningful is precisely its impermanence. It is precisely that it will end. And, you know, there are certainly many, I think, in my line of work where I take care of patients who have cancer, it certainly seems to be the case that people who are approaching the end of their lives seem to experience life in some cases, in this sort of more vivid color palette, like it somehow comes alive for them as they approach the end. And so I guess that I'm just wondering, given what you're envisioning and the things for which you're arguing, what do you make of all of that?
Dr. Ariel Zeleznikow-Johnson: [00:26:59] Yeah, I sort of there's two aspects to that, I would say. The first is that even if it really were true that endings are necessary for meaning, it's not at all clear that like the amount of time we currently have is the correct amount of time. And I could imagine having much, much more time and still maybe the ending after 200 years, 400 years, 1000 years providing meaning in that sense. Certainly, if we look backwards, al like last common ancestors with our fellow great apes, only live for 40 years or so. Humans from centuries ago lived shorter lives than us today. I don't think the exact time we've currently been allocated is necessarily optimal for giving our lives meaning. But to the second part, I am not convinced that it is the endings that provide meaning. Certainly, I agree that we need change and we need exploration, and we need to be able to try new things and expand and have our projects shift over time. We need to continue to be dynamic and to have new projects and find new relationships and connections that I very much agree with. But I don't think people, when they're spending time with their loved ones, when they're pursuing projects to improve the world, when they're going about fulfilling their passions or deriving meaning from the world, are really very often motivated or only enjoying those things because they know someday they will end. I mean, in some sense, this is kind of trivial. I don't think people, you know, enjoy this year's sports competition less because there was already one last year, and there's going to be a new Super Bowl in the year to come. But also with like the more core and deep parts where I don't think people derive meaning from spending time with their family and loved ones because they know one day these times will end. I think it's intrinsically meaningful and enjoyable, and if we got twice as much time or ten times as much time to do these things, at least my impression is that they would be just as meaningful.
Henry Bair: [00:29:05] Do you think that because earlier you said that on average, 1 in 100 humans in the world passes away every year? Is that right? And you characterize that as like a tragedy. Do you believe that death in itself, like not suffering, not death from horrible reasons, but just death and dying like death in general? Like, is that an absolute bad thing? Is that a bad thing that we should be getting over?
Dr. Ariel Zeleznikow-Johnson: [00:29:30] I think what we should be concerned about is a loss of an individual's autonomy, a loss of an individual's ability to make choices for themselves about their life and their health and what they want to continue doing. Insofar as death is the absolute loss of a person, a patient's autonomy, it fully restricts their options from that point onwards. Then I think that is something that we should be trying to abolish and remove. I think we should in general, where possible, be trying to expand people's control over their lives and their health. Now, maybe there are circumstances where an individual might want to say, okay, I've had enough. And in that circumstance, it's always up for, I think ultimately individuals to have control over their own lives. But with respect to any sort of involuntary death, yes, I think that is essentially an absolute tragedy.
Henry Bair: [00:30:25] It is exciting to think about living 200 years, 400 years, 1000 years, but at the same time, there's an element of it that actually makes me. It fills me with a lot of fear to think about what a society like that would look like, right? I mean, just from a fundamental level, our brains have limited storage capacity. For example, I think there have been various studies on this fascinating studies showing that the average person can sustain between 150 and 200 relationships, and the average human brain can recognize like 5000 faces. And that's okay if you only have lived 100 years. But if we were to live a thousand years, you're going to be encountering a lot more than that. Every 100 years. You're going to be like forgetting the people you met a century ago. You're going to be forming new relationships. And if our identity as to go back to the definition of life, if you will, earlier, if what it means to be a person is defined by your memories, your experiences and your relationships, then you're basically a new person, like every 100 or 200 years. If your social context is different, if you're doing different things, if you don't remember what you did the last century, I don't know. It's just it's like an intellectually very scary thing to think about, but also kind of exciting.
Dr. Ariel Zeleznikow-Johnson: [00:31:36] Yeah. So I think if we're thinking about that long into the future of someone living 500 years, 1000 years, maybe what makes it a little bit less scary is we think about what already naturally happens within a human lifetime. So when someone's in their 50s, they have far more social connections. They've accumulated so much more knowledge. There's essentially a lot more information that they have acquired compared to when they were in their 20s. But the 50 year old holds on to the memories they have. Typically a very similar personality. They often have similar goals and desires. It is these psychological properties that bind them together as the same person across time. Now, what I would expect is if we truly develop the technology to revive people who'd been preserved and to restore them to health, we would want to ensure that we did so in a way that didn't mean that as people continued to live and to age essentially, that all of their older memories were slowly forgotten and erased, that that would essentially not achieve what we are trying to achieve with this sort of life extension. Now, it's very weird to imagine a situation in which people's memories are expanded, where people can hold on to more information than they currently do. Although I would point out, we don't actually know what the information storage capacity of a human brain is because normally people die before they get to those sorts of limits. So perhaps we really could already hold on to that sort of stuff. But I would agree that unless you manage to provide someone the means of maintaining their personality, maintaining their memories, then you haven't really extended their life.
Tyler Johnson: [00:33:16] So let's just pretend for a moment. Let's make all of the assumptions. Let's assume that technology is already, or will soon be at a place where you can effectively preserve a person with no deterioration or degradation of their biological tissues and brain parenchyma and everything else, so that you can preserve them effectively, indefinitely. Let's assume that that's the case, and let's also assume that it's the case that you would be able to wake them up. And let's also, you know, somewhere down the line where there is a significantly longer expected lifespan. And let's third make that assumption that somewhere in reasonably not too far down the line, that our society will have progressed to a place where we can people can live, on average, much longer, even if all of those things were true. Isn't it then going to become the case pretty quickly that this will become a procedure that is available only to the wealthy, and that those who have means will be able to preserve themselves in this state of stasis indefinitely, while the poor will be left to die, as determined by their natural lifespan. And what do you make of the ethics of that question?
Dr. Ariel Zeleznikow-Johnson: [00:34:32] The short answer to that is I actually don't think it should be that expensive. So my estimate in the book is that a a preservation procedure would cost something like 10,000 USD if provided at scale, maybe a few hundred dollars to $1,000 per year in storage costs, which is well below what we already accept spending for life extending medical procedures. I think the US, we use something like a 50 to $100,000 per quality adjusted life year threshold. It's similar in many other developed countries, and the reason why it doesn't really need to be that expensive is the preservation procedure is not actually all that complicated. It's essentially introducing chemicals which preserve someone's body into them and then cooling them down. It's unclear exactly how cold you need to keep someone, but cooling them down and storing them in that cooled state. Obviously at the moment it is more expensive because these procedures are still fairly uncommon, although they are continuing to get cheaper already. But certainly there's no reason why this needs to be restricted to billionaires or multi-millionaires. If taken up at any degree of scale, then it should be well within the sort of scope of what we already expect and are willing to pay. And I go through all these details and one of the the later chapters of the book. But even if it were super expensive, one of the things I'd point out is that's not an argument for not providing it. It's an argument for just as quickly as possible, trying to get the prices down. I mean, think of something like a car T cell therapy. These new bespoke cancer treatments where you take out someone's immune cells, re-engineer them, put them back into the patient and use that to cure what was previously incurable cancers that can cost something, I think, on the order of hundreds of thousands of dollars to $1 million. And we don't look at that and say, oh, that's too expensive. We should just not be providing it. We look at that and we say we need to get that cheaper so we can give it to everyone.
Henry Bair: [00:36:30] So I want to dive a little bit into the details of how this actually works, because I think it's probably on the mind of a lot of our listeners. You mentioned that you inject some chemicals into a person's system, and then you cool the body down, but you don't know to what temperature. And yet people are already doing this. What gives you the confidence that you know this is going to work?
Dr. Ariel Zeleznikow-Johnson: [00:36:50] Okay. So essentially if you want to be preserving someone and holding on to their brain structures, you need something which you can use such that when you later analyze a sample from that brain, you can see that it looks pretty much the same as what you would expect to see in a living animal's brain, or a brain analyzed with the best neuroscientific techniques that we have for what we think the natural structure of the brain looks like. And this is what's really improved in the last ten years or so, these sorts of preservation techniques. So specifically the technique that I advocate for that I'm aware is the best one at the moment is a procedure called aldehyde stabilized cryopreservation. And what that involves doing is initially perfusing someone with aldehydes glutaraldehyde specifically, which initially cross-links all the biomolecules, particularly proteins, but essentially all the key biomolecules within seconds of introduction into someone's circulatory system. That initial cross-linking already alone is enough that if you analyze a brain that's been preserved in that way, that it looks almost essentially like what you would expect in a native brain state. The problem is that maybe over time, if you tried to hold someone, store someone in that manner, there'd be some slippage and movement of like the fatty parts of people's cells, like the lipid layers of people's neurons and those sorts of things. A way of getting around that is by cooling down someone's body so that this movement, which isn't prevented by the fixation procedure, also starts to slow down and stop.
Dr. Ariel Zeleznikow-Johnson: [00:38:30] We know that if we get it to what's called the vitrification temperature, so the temperature at which molecules entirely cease moving, then at that point there's essentially no decay, no movement, no change whatsoever. Why? I was a little ambiguous about the temperature before is that there might be a temperature above that at which the movement level is so low that we don't really need to take it all the way down to vitrification. And what would be great about that is the warmer you can keep the body, the less expensive the procedure is, because the less expensive the storage is. But how? We know that these sorts of procedures can work at perfectly preserving brains is essentially what has been done is people have shown in animals, and it's been published for animal work, and it's ongoing in human work is that if you put brains through this procedure and then you warm them up again and you take samples and you analyze them under electron microscopy, you see that you can easily trace the neurons out in the same way that they do for neural tracing studies in traditional neuroscience. I should point out as well that these new techniques, this aldehyde stabilized cryopreservation, I think, first published in 2015, is notably different from the sorts of cryonics ideas which people might have heard about that have been ongoing since the 1960s, which did much more damage to brains and really have not been shown to sufficiently prevent decay and maintain a well preserved brain.
Henry Bair: [00:39:57] Right. What's the difference?
Dr. Ariel Zeleznikow-Johnson: [00:39:58] So the difference is those prior techniques. I think the first ones that were tried were straight freezing techniques, essentially, just like submerging someone or their brain in liquid nitrogen. The problem with that is you get a lot of ice crystal formation and uneven cooling, and the ice crystals puncture cells destroy neurons. Doesn't work at all. More sophisticated techniques were called vitrification, which is where you would add cryoprotectant, essentially something like antifreeze, and that would prevent the formation of ice. And indeed, vitrification is what's used for the preservation of sperm, eggs, embryos very successfully because with small tissue samples, it works really well at being able to ensure that they can be cooled down and then stored indefinitely without decay. The problem is that vitrification alone doesn't work very well for larger organs. That's why we can't, for example, bank kidneys or larger organs as of yet, because introducing the cryoprotectants is difficult and slow. They're essentially very viscous. And also they can cause dehydration like osmotic damage. So people who've tried to preserve people and brains using just vitrification alone typically show like a 50% shrinkage in brain volume. And if you look at it under an electron microscope or a light microscope, the brain tissue looks really bad. It might be preserving memories and personality, but certainly that's unverifiable. Whereas if instead you use this initial fixation step, then you see much better preservation quality. And it looks good essentially.
Tyler Johnson: [00:41:31] I feel like there's a pretty basic tension in a lot of the things that we're talking about in terms of the the science that undergirds the idea that you are promulgating here. Because on the one hand, I hear a lot of talk about incremental benefit, right. So, for example, in the description that you were just giving of exactly how the preservation process works, right? First there was this thing, and then we figured that this was a problem. So then we solved it by this thing. And then we figured that this was a problem. And now we have vitrification and so on. Right. All of which is fair enough. But what is so striking to me is that, like if if I were a person who was, you know, and let's say that there was a company now that was offering this process that said, come have yourself cryopreserved and, you know, we'll put you away in some Han Solo esque whatever, you know, place where you can be preserved until the technology has improved so much that then we can bring you back to have 100 more years of life or whatever. Right? Some version of that, like the idea of slipping into that cryosleep of like giving myself up to the technology and and saying, okay, here I am. Take me away. That just feels to me like. Like I know I brought some version of this up multiple times in the interview, but I don't know how to describe that except as a leap of faith. It's a way of saying, you know, even though this is an iterative process and a and, you know, it's incremental and whatever else, I believe that if I allow myself to be taken into this cryosleep, that the technology will progress in such a way that I will eventually that I will a be preserved. B eventually be woken up and see that things will be good enough when that happens, that I will be glad I underwent the process. It just feels like a funny sort of combination of it is faith in technology. At least that's how it feels to me.
Dr. Ariel Zeleznikow-Johnson: [00:43:44] It's an interesting philosophical question. For me, it feels more like what I do when I extrapolate how I expect futures to go generally, like when I think about, I don't know how, um, investments and stocks will continue to improve in their performance or when new treatments will become available or when, I don't know, improved air travel will occur or when rocketry will be developed. These all feel like estimations, extrapolations trying to make some sort of guess about what will occur in the future. Based on what I've seen previously and based on what I think is theoretically possible. So for me, it just feels very much like the same reasoning I use generally.
Henry Bair: [00:44:28] So it's interesting that for you, going back to the the technical aspect of how this actually works, it sounds like why you're so confident in this current in this method is because it preserves structure, the structure of neurons, and the connections far better than any previous method, which is kind of makes me think that, you know, my brain functions differently now than it did ten years ago, and it will function very differently when I'm 60 or 70. Wouldn't it make more sense for me to basically preserve myself when I like? I don't know, turn 40 or 50 as opposed to wait until I'm like, close to death? I mean, what do you make of that?
Dr. Ariel Zeleznikow-Johnson: [00:45:03] I mean, to Tyler's point, uh, I don't have absolute confidence that these sorts of techniques will work both because, like, I don't have perfect faith in the preservation method. Absolutely. 100% working until revival has been demonstrated that there's no absolute proof. And the second part is like, even if it's true that the technology does work, we may destroy the world. Before we get to that point. There's always the possibility of nuclear war of other severe issues which which prevent that from occurring. So there's a trade off between continuing on now as per normal and making use of the technology. I think generally the time which makes sense to use it would be the time when someone is terminally ill, essentially getting to the point where there's no alternative, and the choice is between maybe having a chance at longer life and nothing.
Henry Bair: [00:45:55] Are we talking about just preserving someone's head, by the way?
Dr. Ariel Zeleznikow-Johnson: [00:45:58] I think it would be best to preserve their entire body. While I think that psychological properties are most important things like memories and personality and the capacity for consciousness, those are influenced by our bodies, by our physical bodies, and there's information encoded in the structure of our bodies that would be useful to hold on to. So I anticipate using this for whole body preservation. I mean, I do think probably the head would be sufficient, but if you can bring more information along then then why not?
Henry Bair: [00:46:29] Sure. Yeah. Well, I mean, it might be more expensive.
Dr. Ariel Zeleznikow-Johnson: [00:46:31] Yeah. I guess.
Henry Bair: [00:46:32] Preserving more tissue,
Dr. Ariel Zeleznikow-Johnson: [00:46:33] that's the trade off to be made. But it seems like something we would want to do because we would want to ensure we had the capacity to understand someone's embodiment in the future.
Henry Bair: [00:46:42] Mhm. I want to talk a little bit about a related concept that you revisit in your book at several points, including the title. The title of your book is The Future Loves You, and you talk about the concept of intergenerational responsibility. What do you mean by that?
Dr. Ariel Zeleznikow-Johnson: [00:46:58] Essentially, what I mean is that if we take my proposal seriously, this idea that we should be preserving people today for the hope that we might be able to revive them in the future, that's only going to happen in a future where things are going well, where the future has the capacity and the desire to look upon their ancestors, and to say, we would like to return these people to the world. I think the idea that that may be a mindset that I hold does have some justification. When we look around us at the world that we have today. So I've mentioned it a few times already over the course of our conversation. But we live in a world where life expectancy is much greater than it used to be, where people are much wealthier and healthier and live safer lives compared to what their ancestors experienced. This didn't come from nowhere. This world that we live in today is due to the efforts of generations and generations of people to improve their world, for themselves, for their children, for their grandchildren, and for future generations to come. And so when I when I think about this, when I think about how people have tried to make the world better and are continuing to try to make the world better, that gives me motivation to myself.
Dr. Ariel Zeleznikow-Johnson: [00:48:16] Want to continue to improve things for individuals to come. And that can be like the weird life extension stuff I'm talking about. It can be traditional improvements to medical practice. It can be standard medical practice that enables other people to contribute to society. It can be anything that anyone does to try and improve the world in some way, shape or form. But I think there's reason for optimism that if as a society, we continue to improve things, we continue to be good stewards of the world, and we obviously solve the challenges of our time and and prevent the destruction or impoverishment of the world through failing to live up to our potential. If we overcome these things and we are responsible, then there is a very real chance that should the technology develop, future generations will be grateful to their ancestors and willing to bring them back into the world. That's really the core of what the book is about.
Henry Bair: [00:49:14] Mhm. You know, what's interesting is that when we started this conversation and we started talking about the idea, we started with the idea of abolishing death. It's interesting when I reflect on the hour we've had here, that actually most of what we're talking about isn't about making people immortal. It's about how can we basically pause, push a pause button on people who are dying right now in the hope that in the future, we'll find a way to help them live longer. Maybe not immortal. I think you've been careful about saying that. You don't know that. We'll get to a point where we will live or will become immortal. Is is that correct? Like, is this really what you're what the book is getting at is like not necessarily immortality, but just delaying death, delaying a painful death, a death to illness longer.
Dr. Ariel Zeleznikow-Johnson: [00:50:01] That's correct. It's about trying to provide people more time, trying to essentially move people to a time where there would be better medical technology, that would give them more options with how to live their life. Yes. You've characterized it well.
Henry Bair: [00:50:15] Okay. Great. Do you think and this, you know, as we near the end of our conversation, I just want to kind of really zoom out here. Do you think immortality is a desirable thing? If we did eventually get to a point where I don't know how this might work, as Tyler mentioned, you know, we're all we're all slaves to the the second law of thermodynamics. But, I mean, there are some very tantalizing aspects about uploading our consciousness, for example, to digital models, in which case that might actually be a very real way to become immortal. Whatever the technology, if that becomes possible, is that something that you think is a good thing?
Dr. Ariel Zeleznikow-Johnson: [00:50:49] So I do outline the possibility of whole brain emulation and uploading in the book. So I do think that there's a distinct chance that something like that might be possible, but I think I'll have to repeat myself from earlier where like, really, what I think is important is being able to give people control over their lives, over their choices. And I think the idea of being inescapably immortal, somehow not being able to control one's life to the extent that, like, one could not choose to end under any circumstances, that is probably too far and like not something that we would want because it would limit what an individual could choose to do, but to provide them as much time as possible, to give them the choice over how they would choose to live, how long they would like to live for, whether they would like to stop living at some point. That is what we should be aspiring to, rather than some sort of inescapable Greek myth style like terrible, potentially immortality.
Henry Bair: [00:51:50] Yeah. What's fascinating is that as I throughout the course of this conversation, I have had this inner dialog reflecting on what this would mean for me, how I would approach this. Right. Because on one hand, as Tyler and I have often discussed on the show, we are both quite comfortable and this can come across odd. But let me explain. We're quite comfortable with the concept of death. What we mean by that is that in the world of medicine, at least in the clinical world, we don't see the extension of life, the pure extension of life as the ultimate end all be all of medical treatments. That should not be the goal of medicine, right? And that's why we we share so many enlightening conversations. And I feel spiritually we're quite aligned with palliative medicine, which which emphasizes much more on the autonomy, as you mentioned, or the well-being of a person. And that's what I mean when we say we're comfortable with the idea of death. Like, it's not it doesn't terrify us. We don't see it as a failure if a patient passes away at the same time, you know I do. Just hypothetically, if we were if I lived in a world where, as Tyler mentioned with the TV show The Good Place.
Henry Bair: [00:52:52] If I were in that Paradise. Right. And, you know, I could have I could spend as much time as I wanted here with the option of exiting permanently. I could step through a portal and just exit permanently. Would I do that? I would imagine I have to imagine when I when I put myself in that position where I'm living my life, and then I'll tell myself, okay, in a month's time, I will exit through the portal. I might like, you know, as the day draws nearer, I might get really, really up close to the portal and say, you know what, maybe a week more. Let's delay that by a month. Let's delay it by a year. I don't know, I'm just I'm trying to be honest with myself. Like, would I actually want this to end? You know, I it almost as if the idea, the prospect, the possibility of it ending is actually. What keeps me going, I don't know. I don't know what to make of that, but it's just something that came into my mind.
Dr. Ariel Zeleznikow-Johnson: [00:53:41] So I mean, I agree and I share a similar thoughts. And I think what's reflected here is if you look at surveys of how long people say they want to live for, and you ask people, I don't know, in their 30s or 40s, typically people say statistically about ten more years than their demographic is likely to get. So people, you know, they want a bit more time, but maybe not too much more time, but it changes as soon as you guarantee them you'll live in good health and you'll be healthy of brain and body. They start saying, oh, 120 years, 150 years like much more time. And the more optimistic people are about the future, the more they feel healthy and well, the more time they want to live for. So I think it's true that, like, I don't think there would be many people at death's door if they were still, well, who would say, I'd like to go through the portal now I've had enough. And specifically there is actually surveys of patients who are imminently terminally ill in hospice care on their will to live. That look at what is the will to live of these individuals and the vast majority of them.
Dr. Ariel Zeleznikow-Johnson: [00:54:44] I think it's about 70% of those surveyed show that even those who are imminently dying still report very high degrees of will to live. If only they were able to continue on, they would do so. And what affects that is actually more people's degree of pain and nausea. It's only the people who are really suffering who say, Maybe I've had enough and I would like this to end. But pretty much everyone else who is feeling okay says, I'd like another day in the sun. And I don't think there's really a time where 200 years from now, 300 year life, people would get to the point where they're like, I'm finished. If they do get there, then that should be their choice to make. But I think it's truly the case that the current limitations of our lifespan are a tragedy, and if we could give people more control over their lives, they would choose to have a lot more life and a lot more love to feel in that life.
Henry Bair: [00:55:41] Yeah, I am probably not going to right now. I'm not going to go so far as to say that the amount of life we have right now is a tragedy, but I will say that I think if people were philosophically honest with themselves and reflected deeply, I think they would concur with the second part of what you said. They would probably want a little bit more time.
Dr. Ariel Zeleznikow-Johnson: [00:55:59] Yes.
Henry Bair: [00:56:00] Yeah. Well, it's been a truly wonderful hour. It's been very insightful and enlightening. It's a it's a new perspective. Definitely. It's very tantalizing, honestly, from a personal, philosophical, ethical, sociological perspective. So we really appreciate you, Ariel, for taking the time to come on the show. I know, you know, Tyler and I sort of approach it from slightly different perspectives. And, and I think that it was very helpful for you to be able to counter, to be able to offer some of your, your beliefs, because I'm sure our listeners will sort of come from, you know, different parts of the ideological spectrum, and it's nice to have this engaging conversation.
Dr. Ariel Zeleznikow-Johnson: [00:56:38] That was a pleasure speaking to you both.
Henry Bair: [00:56:44] Thank you for joining our conversation on this week's episode of The Doctor's Art. You can find program notes and transcripts of all episodes at the Doctor's Art.com. If you enjoyed the episode, please subscribe, rate, and review our show available for free on Spotify, Apple Podcasts, or wherever you get your podcasts.
Tyler Johnson: [00:57:03] We also encourage you to share the podcast with any friends or colleagues who you think might enjoy the program. And if you know of a doctor, patient, or anyone working in healthcare who would love to explore meaning in medicine with us on the show, feel free to leave a suggestion in the comments.
Henry Bair: [00:57:16] I'm Henry Bair
Tyler Johnson: [00:57:18] and I'm Tyler Johnson. We hope you can join us next time. Until then, be well.