63. The Gray Areas of Life: Misconceptions and Discoveries

Tom unpacks the complex definitions of life and challenges common misconceptions about living organisms, from mules and parasites to viruses. Listeners gain insights into the key characteristics that define life while exploring philosophical questions surrounding it.

Chapters

• 0:00 Introduction and Updates
• 6:38 Diving into Astrobiology
• 20:00 Misconceptions About Life
• 1:06:18 What Constitutes Life?
• 2:37:50 Viruses and Their Status
• 3:00:00 Closing Thoughts and Future Plans

Transcript

Tom: 0:01

Hello out there and welcome to another episode of Tom's SciCast. I'm your host, Tom Kennedy. I know I've been gone a while, I've been busy and in fact next week I'm actually leaving to go to Costa Rica with my buddy to go find some sleeping lizards and collect more data on them. Well, since I've been gone, I've been doing a lot of work actually. I know I'm really diving into some astrobiology and then I'm hopefully going to publish some papers on astrobiology. Very excited about that and, yes, I will podcast that.

Tom: 0:34

But as I've been doing some research and listening to lots of other podcasts and reading books and reading up on the whole field, I've realized that there's been a few misconceptions out there and I got to do something about this. Right, I want to see if I can dispel some of these misconceptions, and the first paper I hope to publish on some of these in March is actually a theory of life which I'm not going to publish it quite yet as a podcast. I'll wait till I actually submit the paper. But let's kind of jump into some of these misconceptions and of course, one of these has to do with what are living organisms exactly, or what is life. So my paper is going to be on, so I'm not going to jump into all of it here. But there's lots of definitions out there on life. If you took an intro to biology you may have gotten five descriptive things about life, something about metabolism, reproduction, evolution using energy. If you took an AMP class, their textbook mentioned something about moving and of course there's response to the environment. And if you're NASA, you call it a self-sustaining chemical reaction capable of Darwinian evolution. I kind of like that one, but there's more to that. But these definitions on some level are all problematic. I mean, let's just take NASA's definition, which I think is actually pretty good as a simple definition. It says a self-sustaining chemical reaction. All right, I'm not exactly sure what they mean by self-sustaining. I imagine it's somehow autocatalytic and can read the environment right To take in nutrients and information or take in nutrients and energy from the environment and keep going over time. And if that's your system, well, it can't be an organism, because organisms don't evolve. An organism cannot evolve because we define evolution as a change in allele frequencies. It's the change in your DNA. So a population that's the smallest unit of evolution DNA. So a population that's the smallest unit of evolution. So even NASA's definition the organisms can't evolve. So what is your system? That is self-sustaining, that is continually evolving through natural selection. I just thought I'd throw that out there to get us warmed up here Now listening to a few podcasts on astrobiology.

Tom: 3:03

Of course, astrobiology is pre-paradigmatic, right, which means there's not a really underlying or overarching theme or set of theories to unify the field. You go to physics you've got relativity, you've got Maxwell's equations, you've got gravity, you've got relativity, you've got quantum mechanics, but you have these bases to unify the field. Biology has evolution by natural selection, but astrobiology is a little bit preparative at it because we're still trying to figure out what life is. So all right. So if something's live, if there's life, so what does life do? And of course I've already mentioned these things. You know most people think that life reproduces, it evolves over time. There's some metabolism going on, there's some self-organization going on.

Tom: 3:57

So invariably on these podcasts listen to some pretty entertaining astrobiologists. They would invariably ask a question like is a mule life? Because a mule is sterile, it cannot reproduce. Well, wait a second. How about a person? If they don't reproduce, are they not life? Of course mules are life, they're alive. They're just a dead end of that information driving that system right. There's still life. They just can't reproduce. The way I like to think of this is a living organism is the physical embodiment of life, right? So life is a phenomenon, it's a process, it's doing these things, a mule that's sterile, it's alive and it is part of life.

Tom: 4:44

Here's another misconception where somebody who hasn't studied biology their whole life may make a simple mistake and that's okay. I mean, biology is complicated and I'll tell you what I don't get all of quantum physics either, or relativity. That stuff's pretty tough, it's very mathematically driven and I'm not that mathematically inclined I only went up through differential equations in college and so some of that stuff escapes me. But physicists often come to biology and well, they don't get some of the nuances just because biology really takes a long time to understand it at a broad level.

Tom: 5:26

And one of the interesting things I've heard an astrobiologist muse or contemplate or throw out there is they asked if parasites are alive. And the reason why they asked if a parasite is alive is because they made the observation that many parasites depend solely on a single host. All right. So the idea for these guys was like well, maybe they're not alive because they're like a virus. A virus depends on a bacteria or another cell. Viruses depend on life. I'll come back to that one in a second because I know you guys are ready to hear about the viruses. But let me dispatch this thing really quick about parasites. Parasites are organisms. They are made of cells. Some parasites are as small as bacteria. Some are eukaryotic cells, like Plasmodium falciparum that causes malaria. That's an intracellular parasite. Malaria that's an intracellular parasite.

Tom: 6:27

There are parasites that include many, many types of worms, tapeworms and liverworms and all the flukes and trematodes and nematodes so many different types of parasitic worms. They are organisms, they are cellular, they have cell metabolism, they extract nutrients from their environment and they reproduce, and some of them produce millions of eggs over years. And some of them are so highly evolved like a tapeworm. They don't have a mouth, they don't need a mouth. They're flat Hence flatworm and they look like tape Hence tapeworm and they absorb all the nutrients in your gut right across their cuticle, right across their skin, right so they don't even need a mouth. They are just incredibly specialized animals or bacteria or cells Right, so they're incredibly specialized to live in a very specific environment with very specific requirements.

Tom: 7:27

Like some parasites can only attack one particular type of host. That's how specific some of these can get. So they're totally alive, right, they're living, they're metabolizing, they're they're reproducing. They're just highly derived, okay, okay now, um, I'll go ahead and let's get to this viruses. There's a virus alive.

Tom: 7:48

There's a camp that says, yes, viruses are alive. The reason why some people say that viruses are alive is that they are able to reproduce, they are able to evolve over time, as we've seen with this little coronavirus. And not only can they evolve over time, they also take over the metabolism of cells to make more viruses. So some people say they're alive. There's even more to that. I'll come back to it. There's another camp that says no, they are not alive. And the reason why is because most viruses are basically some genetic programming, whether it's RNA or DNA, encapsulated in a protein coat. And when that virus attacks a cell, it unleashes that viral software, that DNA or RNA, that programming, to take over the functioning of a cell and therefore make more copies.

Tom: 8:54

Now, I know that sounds parasitic. The difference is a parasite has cellular structure, it is respiring, it is doing metabolism, it is taking an energy and it's doing it on its own. It's just extracting this energy from you or whatever organism is infected. A virus is reprogramming the cell based on genetic information. So in my mind, viruses are typically not alive, they are information. They can be no more alive than DNA. Yeah, that's what I think Now in biology. One of the most beautiful things about biology is that it's messy, it's nuanced and there's exceptions. Yeah, there's exceptions out there. There are viruses that are huge. They have genes for maybe several thousand different types of proteins. Some of them have rudimentary metabolism. Now, those particular viruses that are very large, very complex, maybe a hint of metabolism.

Tom: 10:00

We can debate back and forth of whether or not they're alive or not, and to me that's not quite that important. I would still say probably still not alive because of the lack of metabolism being driven by information, but they're definitely like kind of in that gray area, or at least in my mind they are. Now here's the thing Viruses may or may not be alive. I'm going to say that they're not alive, but they are part of life. So if you're out in space and you find a space virus, guess what you have to have Life. Life has to be somewhere. So viruses are derived from life, they are part of it, even though they may not be living. All right, I hope that works out for everybody, okay.

Tom: 10:48

Now, every now, now and then I get some pretty good questions from very insightful students that you know they come up with these really good questions and you know you start defining life based on these intro to biology books and a lot of them not a lot, but a few. Every now and then we'll say, hey, you know, what about crystals, hurricanes, stars and planets? Are they alive? And that's actually a pretty interesting question, right? Because in my classes I often define life as a dissipative structure, right? So here's how a dissipative structure works.

Tom: 11:20

Imagine ice forming in your freezer. Water is moving around randomly, all the individual molecules are moving around randomly, and then, as you remove heat, as you remove energy from the water, there's not enough energy to break those weak hydrogen bonds Holding the liquid water together. Those hydrogen bonds become set and ice crystals begin to form. And when ice crystals begin to form, the water molecules go from a state of high entropy to low entropy as they become organized. Don't worry, we are not violating any laws of thermodynamics here. This is a self-organizing dissipative system because what happens is that, as the water molecules arrange them into a regular pattern. When those hydrogen bonds are formed, it releases energy and in fact it releases about six kilojoules. A mole for you know, for everything of, for every mole of water that's formed that's about 18 grams releases about six kilojoules of energy. So when ice is formed, it's releasing heat into the environment. That's why when you hit the dew point at night and water or ice starts forming on the ground, nighttime temperatures often stop declining so fast, because as the water condenses out of the air, it releases energy, it releases heat back into the environment. So ice is a self-organized dissipative system.

Tom: 12:49

It's a crystal. And students have asked me hey, is that alive? Because it's self-organizing? And to me that's a really fantastic question. Right? The answer is they're not alive. And the reason why is because things like a crystal, even though they can reproduce, what they're not doing is metabolizing. They aren't taking in information from the environment, reacting to it and doing metabolism and releasing more energy and, in fact, metabolism of life. When a living thing takes in energy from the environment and uses information in his DNA to extract that energy from the environment, it's much more efficient than just pure abiotic dissipation. What I mean by that abiotic dissipation is think of a crystal forming, right? Life is much more efficient at it. But life is using information, right, to extract that energy and create order at the level of the organism, right? So that's why a crystal is not alive, even though it can reproduce. Hurricanes are also a dissipative system. They're created by energy gradients and as hurricanes move across the oceans, they are transporting large amounts of heat energy from the water to to northward areas. And these hurricanes self-organize as well.

Tom: 14:14

Stars and planets. They form a circle, a ball right, a sphere, and as they compact they're releasing energy. And being in a sphere is a is a stable structure that releases energy. So they are self-organized. Minerals do the same thing as well, but there's just no coupling of information to these metabolic processes. And people have pointed out that. You know. The universe evolves. Stars evolve, planets evolve, they do. They do change over time. Our star is changing over time. Our planet is changing over time. Our planet is changing over time. It is evolving, but the way they are evolving is not due to changes in their information, this controlling their systems, right. They're just evolving to dissipate more and more energy and go toward equilibrium, right? Okay, and then, oh, there's fire. Yeah, my inner Beavis just came out. I think a little bit there. Fire, yes, yes, we used to stop studying in college to go watch Beavis and Butthead and I think I just dated myself.

Tom: 15:22

Fire people say oh, you know, fire metabolizes, it breaks down carbohydrates. You know, fire metabolizes, it breaks down carbohydrates. You know the fuel of wood, and it releases energy into the environment. It can grow, it can reproduce. The problem here is that fire is clearly not alive. It does not self-organize. Right, there's no self-organization. There's no self-organization or release of entropy. Fire is just this redox, reaction, reduction, oxidation. Right, you're taking carbohydrates and other things inside the wood and you're basically making carbon dioxide and water and some other things out of that and you're releasing a ton of energy, but you are getting absolutely no local organization out of that. And you're releasing a ton of energy, but you are getting absolutely no local organization out of that. It is not a dissipative structure at all. And, yes, it does release more energy than life does, which is using information to extract energy and dissipate that into the environment.

Tom: 16:23

Okay, now that brings me to my next point, and I don't think that this is much of a misconception at all amongst scientists, people studying the evolution of universe and life in it. But it sure, as a biologist, threw me for a loop, because when you mentioned adaptation, as a biologist that has a very precise meaning. It basically means that a population is evolving in some way to become better fit to its environment so it can survive and reproduce and pass on those genes to the next generation. So an adaptation is part of evolution, right? You're changing to better fit to the environment and that is driven by that filter of natural selection, by changing the information of your genetic code, of your genes. Okay, so when I saw dissipation-driven adaptation, I was like what, what does that mean? You know, dissipation-driven adaptation? So this isn't a misconception at all, this is just a clarification and it took me a while to figure this out as well.

Tom: 17:31

So, as I mentioned, things like crystals, minerals, planets, stars, hurricanes, these are all dissipative structures. So what that means is they are self-organizing in a way that releases energy to the environment. They're increasing entropy. I know, isn't it weird that the universe started off in low entropy and is going toward high entropy? But that pathway from low entropy to high entropy, that's where all the fun stuff happens, including life.

Tom: 18:04

Okay, so what is dissipation-driven adaptation? Yes, these things are adapting in a way to become more stable. So, as, like salt crystals form or water crystals form, they're adapting in a way that they release energy to the environment. And yet if it's a crystal, that repeating structure is thermodynamically favorable, so it's going to last longer, right, it's more stable. But that adaptation is not driven by algorithmic information. There's no, there's no code, there's no way of like okay, crystal goes, okay, I need to put this molecule here, this molecule here, this molecule here. We're going to use this metabolic pathway to do like okay, crystal goes, okay, I need to put this molecule here, this molecule here, this molecule here. We're going to use this metabolic pathway to do X, y and Z. No, these molecules are just arranging in the most stable state they can and it's an adaptation in the sense that it becomes more stable, not violating any laws here, because, like I said, it's dissipating energy. So the dissipative structure itself is organizing because that's more stable. It's creating local order, but the overall entropy of the universe is is, uh, going up. And then biological adaptation that's providing some advantage based on stored information. Now for anybody out there that has studied like information theory oh man, that's kind of blown my mind a little bit, their way of defining information is very different than the way you and I think of information, but the way I'm going to say information is we can call it algorithmic information. So you've got a set of instructions that tell you what to do under certain circumstances. Now, lastly, there's one more thing that's always kind of bothered me a little bit, and in fact this is going to be the basis of one of my next papers that I hope to publish, maybe later this spring. I've got a trip to Costa Rica and to and to colombia coming up, so it's going to be a fun spring.

Tom: 20:11

This question that often comes up life as we know it or life as we don't know it has become quite popular now amongst astrobiologists. So as a biologist that studied ecology, evolution, physiology, you know anatomy i've've looked at biology from multiple scales here I like to ask what do you mean? Life as we don't know it, or what do you mean we have no idea what alien life would look like? That's a loaded question, right? And it's also, I think people say that in response to like, we have to be open-minded about what life in the universe is going to look like. We only have a sample of one. We do not know all the possibilities out there and we need to be very open-minded about what the potential of life is out there in the universe. Because, like I said, we had that N of one sample problem. Right, we only got an example of one type of life.

Tom: 21:11

That is very true and there is some humility in saying you know, I don't know what life in the universe is going to look like, but what kind of rubs me a little bit. The wrong way is, when people go, we have no idea what life would look like elsewhere in the universe, and life on Earth is not particularly useful for understanding life in the universe. I know, I've heard that and I kind of take some issue here. And here's why I think we can make some predictions about alien life or life in the universe in general. Because if I say you know life is based on the natural laws of the universe, right, we have uniformitarianism. The laws that operate on earth can operate across the universe. Those natural laws are going to drive convergent evolution. Similar ecologies are going to lead to similar morphologies. If you swim in water, you're going to look kind of like a fish. If you swim fast, you're going to look more torpedo-like. If you're going to have quick bursts of speed, you're going to look more like a grouper with rounded wings, right, I would imagine that life is going to be bilaterally symmetrical if it's got a level of sophistication close to humans or animal life on this planet. So there's all kinds of natural laws of the universe, like laws of diffusion, fractal geometry, that can enable us to make predictions about what life might look like.

Tom: 22:40

To make predictions about what life might look like and to say that life doesn't here on Earth is uninformative of life in the universe. I don't think that's right. And here's another reason why. Whether or not the Earth is totally unique is still out for debate. Right, it could be in the fact that it's got a moon, it's got plate tectonics, which could be very important for life.

Tom: 23:08

But as we look out into the universe and we build a catalog of planets, we do see Earth-like planets. We see Earth-like planets in the Goldilocks zone, where you can have liquid water. Now, life is definitely probably not limited to just the Goldilocks zones. We're going to hopefully find out about our ocean worlds and the outer solar system of Enceladus and Europa, but for something like our planet, you need this Goldilocks zone with some rock water interface. You're going to need a geologically active planet and you know, life is going to probably be based on carbon chemistry and water and there's lots of reasons to believe that and life is also probably going to have a set of parameters that is going to operate in. Ph may not affect that very much, because we find life on earth in almost every pH you can imagine.

Tom: 24:02

But temperature matters. You get too cold and the chemistry of life is going to slow way, way, way, way down right Now. That's not in itself super problematic, except it becomes harder to break the bonds and have things moving around, right. So super cold becomes problematic. Let's go the other way, starting to get too hot. I suspect that most life will not exist beyond 150 degrees Celsius. Beyond those temperatures there's just too much kinetic energy. The molecules of life just can't hold up. They break apart. So that's going to put a hard boundary on it.

Tom: 24:42

All right, we already talked about needing water. But also salinity might be a problem too. You need water for the molecules inside of cells to move around and have those chemical reactions. As you add more and more electrolytes, you become saltier and saltier, right. The water loses water potential. It doesn't move around as much and all of those ions are gonna start having problems. They're gonna, you know, start attracting to all of your DNA or whatever your information storage is. Whatever molecules you're gonna have, they're gonna start affecting those chemistries a lot. So there's probably some hard limits to salinity, probably around 25 to 30 percent, maybe a little bit higher or not, but there are going to be limits to salinity. So those are some predictions that I think we can make.

Tom: 25:31

We can also probably predict that life in the universe is going to be cellular. The chemistries might be different. I still suspect they're all going to be based on carbon and water, but maybe on titan we'll find something different. The reason why is, when we look out in the universe, water is everywhere, carbon is everywhere. Guess what's everywhere else too? Silicon it's one of the most abundant elements in our crust. Okay, is life based on silicon on this planet? No, and the reason why is because, unlike carbon, silicon cannot make long chains. It can't form complex molecules like carbon. Can. Carbon's in the Goldilocks zone here. So life? That's why life is carbon-based there. So, taking these first principles, we can start to make lots of predictions about life.

Tom: 26:25

You want to live on land. You got to deal with gravity and desiccation. You want to grow big. You probably have to have a skeleton on the inside, an endoskeleton like vertebrates, because if you have an exoskeleton on a planet that's similar size to earth, well, you run into things like allometric scaling and you get bigger and bigger and bigger. The wall of your exoskeleton gets thicker and thicker and thicker. At a very disproportionate rate we would say that non-linear. It gets thicker faster and you're going to be. There's a hard limit to how big you can get. You'll probably need a closed circulatory system if you want to be big, because you got to pump blood against gravity.

Tom: 27:05

So, like I said, there's all kinds of things we can make predictions about here. You want to detect a light and there's some things that can see in the near infrared and things that can see in the near ultraviolet, but much beyond 700, you know, 730 nanometers gets hard for life to detect because the that's infrared, by the way, because that light, the electromagnetic radiation, lacks sufficient energy to, you know, cause a shape change in a protein for you to detect it. I mean feel it's heat, but we can't see it very well as light much beyond about 730 nanometers go the other other way get up into the ultraviolet and there's some birds and bees that can see around 380, 350. You get shorter than that and the energy packs too much of a punch right and you damage your molecules. So, once again, no life will probably detect light. Okay, I'm really having fun with this and I could continue on, but I'm actually getting ready to write a paper on this, so I've actually I've got some more information that I will share once I get that publication out. And uh, yeah, this has been fun. So there it is.

Tom: 28:19

There's some misconceptions about life. One of them, not. Some people have some very good questions, but you know, I often hear our meals have some very good questions, but you know, I often hear our mules alive and of course, they're alive. You know they're part of life. Or viruses, alive or not? Well, you know, probably not. They're not dissipative structure doing metabolism, you know. You know being controlled by some form of information, um, but they are a part of life, they're derived from life, right, and then I don't think I talked about this. I'm rambling a little bit because I forgot to write this down.

Tom: 28:50

Invariably, somebody might talk about artificial life or artificial intelligence, or artificial general intelligence that might have the ability to be self-aware or have consciousness. It can pass a Turing test ability to be self-aware or have consciousness, they can pass a Turing test, so to speak. I think they can already do that. Or they may have agency. Whether or not we consider artificial intelligence to be alive or not, I think is more in the realm of philosophers. Once you get a cognition and agency and self-awareness, you start asking questions. Yeah, I, I think in some ways you are alive. The question is, it's a different type of life. Uh, it's not organic life. Like you know, I said, living things cells and organisms are the living embodiment of the process of life. Uh, but this ai, I think that's going to be kind of in the realm of philosophers. But what I would say about that is that, even if we consider AI alive or not, it is still part of the planetary phenomena known as life.

Tom: 30:02

Okay, so, yeah, I got off track a little bit there. Yeah, I was kind of rambling a little bit tonight and that's okay. I had some notes written down, but my brain is really thinking about this, this theory of life that I hope to publish in a couple of weeks. Like I said, I got to get to Costa Rica first and whip this paper intoelet. Let my friends read it and make sure I'm not full of it, all right. Well, until next time. This has been Tom Sykast, and I promise you this year will be different. I just bought a new microphone, a new preamp, and I'm really looking forward to creating more podcasts this year. All right, I will post again soon. This is Tom Sykast.