Welcome to Chasing Life. Today, we've decided to take on one of the biggest topics, I think, in all of our lives. What is consciousness and where does it come from? In a minute, we're going to be joined by one of my favorite science writers, Michael Pollan, who's written a book about this. But I've got to tell you, this is a topic I think about a lot, consciousness. In fact, when I was in the operating room having just read this book, I was talking to my fellow surgeons and residents about consciousness, that's the very heart of what we do as brain surgeons. Where does it reside in the brain? Does it reside in the brain? That would be dependent on really being able to define what consciousness is in the first place. Look, I'm a brain surgeon. I've spent decades of my life studying the brain, and yet I am still perpetually fascinated by the mystery of sentience. This conversation only deepened my appreciation for the gift of an inner life and also the interior monologue, the conversation that we continuously have with ourselves. Is that a conversation we're having with our own consciousness? I'm Dr. Sanjay Gupta, CNN's chief medical correspondent, and this is Chasing Life.

Okay, welcome back to Chasing Life.

Thanks you Sanjay.

Thanks so much for joining us. I always really enjoy our conversations. I feel like we go in a lot of different directions. And I read your book, congratulations on it. It's a great book. It seems like a different book for you. And, you know, I'm going back to Omnivore's Dilemma. And I'm just wondering, before we get into some of the substance of the book, just tell me about some of the background on deciding to write this book.

Yeah, it was never part of my life plan to write about consciousness or neuroscience. But as you know, I wrote a book called How to Change Your Mind about psychedelic therapy. And as part of the research for that book, I had a series of psychedelic experiences. I also became a meditator. And I think those two activities put consciousness front and center in your attention. It's as if they smudge the windshield through which you normally look at the world and which normally feels completely transparent and you're not really aware of this incredible phenomenon that allows a world to appear to you. I mean, I had, on one of the psilocybin trips, I was in my garden and the plants in my gardens suddenly seemed wide awake, fully conscious. Returning my gaze, they were, I know...

It sounds terrifying.

No, they were... they knew I was their gardener. They weren't going to attack me or anything.

And it wasn't a bad trip, so to speak.

It was a great trip. It felt terrific. I felt like I was among friends. So, I didn't know how to credit that experience. And is there any informational value in that? And that is always a problem with psychedelic experience. People have powerful insights, but are they true or not? You're saying, what's real, what not real? And what is my brain creating? And you realize, okay, your brain is developing these, is giving you these hallucinations. But then you wonder, well, is the brain giving me normal consciousness too? It just all seems much less familiar. And so I just became really curious and I've found the best formula for a book is having some big question that occupies you and then writing the detective story of looking for answers.

'I wrote this when I was reading your book and this is you know I was trying to like summarize the book into a few big questions... A World Appears: A Journey Into Consciousness explores what consciousness is, who or what might possess it -- and I want to come back to that -- and why it matters for how we live. I think people have a general idea that you know consciousness something so integral to who we are How we function is important ...But what is it? How do you define it as a starting point?

You know, there's a paradox here because it's incredibly simple. It's the thing we know better than anything else that we are conscious. And it's the only thing we can be sure of. Everything else is an inference, yet we struggle with the definition. So there are a couple kind of simple one word definitions.

One is awareness, the fact we have awareness. Another is experience. We have experiences, your toaster does not have experiences. And those are serviceable. There's also a famous Thomas Nagel, the philosopher back in the 70s, came up with a wonderful, I don't know if it's a definition exactly, but kind of a test. And that is in an essay called What Is It Like to Be a Bat?

Yes.

And his thesis is that, obviously it's very different to be a bat, but we can kind of. You know, they use echolocation instead of vision to navigate the world, and they hang upside down a lot. So they couldn't be more different than we are, but we can kind of assume that it's like something to navigate world through echolocation. So they're, in all likelihood, they're conscious. So it's that quality of what it is likeness, that there is a qualitative dimension to our experience, and that is consciousness.

'Describing consciousness as you did in the book is an unmapped continent. So if you're on a journey -- you're traversing planet Earth, let's say -- and you find a continent that is unmapped uncharted so far Was there a surprising characteristic of this, landmass call it, when you started to explore consciousness? Were the things about this that that you did not expect?

Oh yeah, many things I did not expect. I was surprised at how difficult it is for a science that's, you know, underlying our scientific enterprise is a metaphysics and that is materialism or what's sometimes called physicalism. And this is the idea that all phenomenon can be reduced to these terms, the laws of physics say it's very hard.

Everyone has assumed that this would be true for consciousness, but the people who work on it many of them are coming to doubt that, that it simply may not be reducible. But when you say unmapped continent, it isn't quite true. There's a lot about consciousness, descriptive information about consciousness. It's been mapped by the psychologists and Freud to some extent, and the artists, but it hasn't been mapped as a physical phenomenon.

I think it's early in the book you talk about Antonio DaMasio, who calls consciousness something akin to deliberate life regulation, and also even talks about where it's located, which is the brain stem. The brain stem, yeah. Not the brain. But let's talk about the first part, this deliberate life regulations.

'So the brain. as he reminded me, the brain exists to keep the body alive. It's not the other way around. Since we're so brain-centric, we assume this body is here to move the brain where it needs to go and do what it needs. And what the brain is doing, a big part of what the is doing is monitoring the body and it is managing homeostasis.

I mean... We all need to stay in a certain range in terms of, you know. Blood gasses, glucose, and heart rate, and I mean, there's all these, I mean you know better than I do, all these variables. And the brain is doing that a lot of the time. Feelings, in his view, arise when there's something amiss and that you have hunger, let's say. And the feeling begins in the brain stem in his theory, and this is also Mark Sommes's theory. And only later does the cortex, which is the rational thought in the front of the brain, the evolutionarily most recent part, get involved. Like, well, we're gonna go to the restaurant and we'll take care of that. And then pictures where you go and how you solve the problem. So this is life regulation, and that is the brain's first job. I said to him, but we have a lot of feelings that aren't related to biological homeostasis. And he pointed out, though, that we have other sort of homeostatic set points. For our social standing, for example. And when we feel shame, we feel off and we have a feeling that comes with it that we need to do something to restore our social stand. Ditto pride is a very positive feeling based on our social standard. So he thinks that homeostasis extends to these more psychological realms and the brain is charged with taking care of it. Basically, his contribution to Neuroscience has been to elevate the importance of feelings. Feelings are the inaugural act of consciousness, not thought, and thought comes later.

I guess, you know, I'm sort of building up to this point, you know I read this in the book, this idea that you spend time with these plant neurobiologists, I think that's what they're called, plant neurobiologists, and they're looking for flickers of awareness in plants, and it turns out that some forms of consciousness are more widely distributed in nature than we thought.

So first of all, plant neurobiologists, they're just trolling people like you by using that.

I was going to say, it was a great term, I wasn't sure exactly what it meant.

'There are no neurons involved, but part of their argument is that you can get brain-like behavior in things that don't have brains.

'Is it brain-like behavior to the point of awareness?

'No, I wouldn't. Well, awareness in terms of, they're sensitive to their environment. So that's a kind of, I guess that's kind of a very basic awareness. I think the term sentience is useful here. It's a simpler form of consciousness. It doesn't have self-consciousness or interiority. It is simply, you register changes in your environment and you have a sense of good ones and bad ones. And you take appropriate action based on that. And that that may be universal in life and that single-celled creatures may have that. I mean, bacteria have chemotaxis, right? They know like this molecule is good for me, this one's bad for me and they act appropriately. Plants turn out to have a very complicated life. And then I tell stories of these experiments where the root of a corn plant can navigate a maze, just like a mouse, and find a little packet of fertilizer buried somewhere in that maze.

When two plants are in a pot together, if they're related, they'll share resources, and if they are not related, they'll compete. So they have some sense of who they are. Some plants change their leaf shape based on, these are vines, if they climbing up a plant, that has a certain kind of shape, they will mimic it. So how do they see it to mimic it? We don't know, but they see in some way, they hear. Plants roots will seek out a pipe that water is running through that has no condensation on it at all, based perhaps on the noise, the sound, so they may hear. Plants hear the chomping of caterpillars on their leaves and then release certain chemicals. So now we could say all this is instinct.

Survival.

'It's definitely survival. But the scientists I was talking to make the point that the world is so changeable and has so many novelties at any given time that evolution focuses on creating creatures that can solve novel problems rather than automating everything. And I found that persuasive. So I didn't come out of this 100% persuaded that plants are sentient or conscious, but it certainly was mind-bending to see what they could do. They have 20 senses to our five or six. It's kind of, it's, yeah, I came out of it with a lot more respect for plants.

I'm talking to one of my favorite science writers, Michael Pollan. His new book, A World Appears: A Journey Into Consciousness. Fascinating read. We'll have much more after this break.

'I remember Michael Lee, the name you might know, he's a Microsoft AI engineer. He said to me once, he said, don't think of AI as a super computer, think of this as a technology that's trying to replicate human consciousness. So it's a much more audacious task and it's much more prone to errors as a result -- you know the hallucinations that people talk about. But I still have a hard time getting my head around it. And I think it comes back to maybe the fundamental question that I started this interview with. How would you know? At what point do you say, okay, this is now crossed over into the territory of having acquired consciousness or even awareness as you describe it?

'Well, you know, the classic test has been the Turing test, right? Alan Turing, back in the 50s, said that we'll know that these machines are conscious or intelligence, he would use both terms, even though they're not identical, when they can fool the majority of intelligent humans in conversation with them. So the test is based on duplicity, which is interesting. And that-.

The fooling part, you're saying?

Yeah, the fooling parts. And that's been part of the deep DNA of computer science for a long time, this idea of the Turing test. I don't think it's the best test because these AIs, these chatbots, have been trained on the human conversation about consciousness.

'I mean, they're reading everything. They will read this book and fold it into their- into their knowledge base. I think the real test would be to build an AI and take any discussion of consciousness out of its training materials and see if it could generate the same kind of conversation that these chatbots are generating now. That I think would be the test we're looking for. I don't know how you do that. If you just let them loose in the internet, they're gonna find this stuff. But you have to somehow create a training set that is completely free of all these terms we use. And, you know, maybe it's gotta be free of fiction too. Maybe they can't read novels because you learn so much about consciousness in novels. I don't know, you'd have to design that very carefully. But that to me would be a more convincing case. Fooling us is not difficult.

Is mortality a necessary ingredient for consciousness?

That's a great question. It may be. I think that feelings are necessary to consciousness as we were discussing earlier. And then you think about, well, what is a feeling or what does a feeling depend on? It depends on having a body. It depends a kind of vulnerability. And it depends on an ability to suffer.

Without these things, which are tied to mortality, obviously, that if a threat to our bodily autonomy is serious enough. We can die. If you take away those things, feelings have no weight at all. They're just kind of more information. But for humans, they have a lot of weight. And that I think computers can't ever achieve. I think there are two big problems with this idea of conscious AI, at least based on the AIs we have and foresee. One is this idea that I don't know without bodies and mortality and ability to suffer whether they can really be conscious. I mean, I think these things are essential. The other is it's based on a faulty metaphor that the brain is a kind of computer. Now the brain does a lot of computation, it's true. And it has aspects of a computer and neurons fire and like transistors, they're either on or off. But there's a lot else going on in the brain. I don't have to tell you. I mean, that there are hormones and neurotransmitters and drugs, all these things can affect how neurons fire. And you also don't have a clear distinction between hardware and software in the brain. Every experience rewires the brain to some extent. Every memory is a physical thing in the brains. Brains are not interchangeable the way computers are because each brain is created by the life experience of that person. So this idea that consciousness is an algorithm or a software program that can run on a variety of different substrates is like, I don't think it works. I don't think, I think it's a faulty metaphor. There's a great quote that I read in Richard Lewontin, the great biologist, late biologist at Harvard. He said, the price of metaphor is eternal vigilance. And I don't think we've been vigilant about this brain computer metaphor. I think that has lots of problems.

So, just keeping with the computer metaphor for a second, even though we agree, the brain is not a super computer. The brain is three and a half pounds of some of the most mysterious tissue in the universe. Is consciousness sort of a parallel operating system or is it integral to the brain?

Do you think, and I guess it gets at this point, Michael, that you've raised a couple of times, where is it? Is it in the brain, after all the research you've done, what do you think?

Honestly, I don't know. I'll be totally frank about it. One of the scientists I talked to said, so what he's describing is something, what is sometimes called transmission theories that there is a field of consciousness and what brains do, they're like TV receivers or radio receivers that they channel consciousness. Henri Bergson, the French philosopher was an exponent of this. Aldous Huxley too, based on his psychedelic experiences. In the doors of perception. So clearly, I see consciousness outside my brain, I'm channeling it, and I'm getting only a measly little bit of it, and there's a lot more to get. And one of the insights he had is that there's reducing valve that limits the amount of consciousness we take in from this field to just what we need to survive, but there's whole lot more out there. But anyway, the scientist was telling me that the brain is still involved, but the brain has not generating consciousness. It's receiving consciousness. It's an interesting idea. It seems kind of crazy to me, but who am I to say?

Sounds like religion.

It sounds a lot like religion, I think there's a religious subtext to a lot of the discussion of consciousness. I think it is our secular version of the soul, Um, but like And I think part of our interest in it has to do with the fact that we have some residual longing for something called the soul. I mean, you know, think about souls, they're indestructible, right? They survive your death. I think there's a kind of a shadow behind consciousness around our mortality. I mean that this is so weird and disconnected from the usual natural categories that maybe this survives.

You know, these are the hard questions. And frankly, you know, just for my, even in preparation for an interview, I spoke to some of my residents and people that I trained with as well, just to, and it's interesting, people have very disparate points of view, even people who study the brain quite regularly. You know going back to your other books, you do, it does feel like when I read your books, you have a thesis. I mean, you know, I mean Omnivore's Dilemma, in some ways that was a clarion call to individuals and to societies from a policy perspective to think about food differently. With this book, is there some call to action? Is there something we should do differently after reading this book?

Yeah, I mean, the one thing, so it's true. I mean Omnivore's Dilemma began with a question too. What should I eat? And where did my food come from? And I was able to answer that question by the end of the book. In this case, no. I mean it was a much bigger question, hard to answer. Learned a lot along the way, but the ultimate exponent, it remains a mystery. Consciousness remains a mistery. Will it always? No, I think eventually we should figure it out, but it may take a different kind of science or a collaboration of science with other ways of knowing. I'm not sure exactly. The call to action is simply to appreciate what you have and defend it against all who would take it over, all who want to buy and sell your consciousness. I think that's the message. And I think the consciousness is under threat from technology and technology, you know, the reason that they wanna distract us. The reason they wanna win our affection and attachment is so we spend more time on their platforms and less time within this wonderful space.

So when you're in line at the cafe.

I resist the urge to pull out the phone and scroll. And I'm really trying to go back to that moment when I had to fill that space myself. And we're losing our ability to do that. We're losing ability to be bored, right? Who's bored anymore? There's always some way to fill, fill that time and space.

You know, it's interesting, Michael, I thought a lot about this book and thought about you and you know, like if life were in some way potentially infinite, I think I would think about certain things very differently than I do.

What do you mean?

Life is finite.

Yeah.

So there's some questions in our lifetime that we're probably not going to answer. And then I get back at this idea that some things just are. Like consciousness seems to fall into that bucket to some extent. I still have a hard time defining it, but I know that I can't live without it, fair?

Yeah, absolutely.

I need to have it as a human being to, but I still don't fully understand its purpose. Awareness is obviously important, but there are people who are very much alive and very much unconscious at the same time. And I take care of those patients all the time. And I don't, it becomes challenging because they are alive. So consciousness is not directly associated with life.

And some small percentage of them might, may be conscious.

That's where I think this argument probably goes. Probably in terms of figuring it out, the fact that we can peer more deeply into the brain, into beings, humans in this case, that we think have some awareness and consciousness, even though they appear externally to be unconscious, I think is probably the next frontier.

And that's the practical implications of this work. It's interesting, Christof Koch, who's a neuroscientist who I profile in the book at some length. He's a character who appears a few times. He's working on a technology to test those patients and determine if they have any consciousness at all, which will be very useful in medicine.

Yeah, I mean, we take care of patients a very specific way based on our perception that they are unconscious. And we make predictions of their lifespan, their remaining lifespan, based on whether or not they are conscious or not. So it could change a lot of things. Are you already thinking about your next book?

No, I'm reveling in the fact that I don't have a book deadline at the moment, which is one of the sweeter feelings in life. I'm sure I will write another book, but I don't know what it is yet.

Always a pleasure, sir.

Likewise.

That was my conversation with Michael Pollan, author of A World Appears, A Journey into Consciousness.