[0:00] If you think about it, humans themselves are 99.9% genetically identical or at least similar. All of us, whether we're talking about bacteria or mosquitoes or earthworms, we're all made of the same stuff. And we all have the same fundamental challenges to find enough to eat, to find a way to reproduce. I like to think about the whole living world as sort of little tiny hurricanes, hurricanes of energy and matter and information. And when you look around, you see so much beauty and wonder in the world. And we're connected to it through ancestry and through the connections of the air and the sky. And we're all part of the same thing. And I find that amazing.
[0:54] I love to just catch the little chit chat. And sometimes it's just fun to throw in. But again, thank you for coming on. I found your work beyond fascinating. Unfortunately, I don't even have the vocabulary to express to you how cool what you study is. And your episode is actually the last episode of the first season. And I think it's perfect because the podcast is called The Science of Life. And what better question to ask than what is life itself, right? We've gone nine episodes talking about biology related things, but haven't really gotten to that essential question of what even is biology. And I've heard you on another podcast, and you've said that there's as many definitions of biology as there are people in the field, which is a really interesting way of looking at it. And of course, I'm going to throw you the million dollar question, right, that we're going to spend an hour talking about. But what is life?
[2:02] I think the curious thing is that nobody agrees. And so people end up falling back on a sort of description. So life forms move, they grow, they repair themselves, they reproduce, but that doesn't actually tell you why they do any of those things. So I think that we still haven't really honed in on the answer to that. But what we do know is that life forms appear to be completely different from other entities. And that they seem to have, one of the things that really interests me is that they seem to have transformative powers. So that's partly because they have metabolism. And so what goes in is not the same as what comes out. But it's also partly because they have a, they have a whole series of powers that allow them to change the world. And that's the thing that has really been interesting me over the last 15 years or so.
[2:53] Really? Okay. And so I think that there is, there are a few theories to how life came to be on Earth. But I actually would love to pick your brain about things. So I read up on hypothetical life forms, like alternative views of what life is. And they were so abstract to the point where it came down to cosmic strings as life forms. Like what, how abstract can we view life? Like if we wanted to even expand beyond the lens of Earth, could we look at like other things that we've not considered beyond Earth as life forms? Well, I think it's a, I think that's a very deep philosophical question that we don't have the answers to yet, because we haven't yet discovered any other living world. So I think, I think it's something of a parlor game. I think people like to sit around and sort of say, well, you know, maybe this is life, or maybe there are life forms inside the sun or, and personally, I don't buy it. I have to say,
[4:00] I, I think that life is very likely to be chemistry, as life is here. And I'm personally betting on carbon and water as the most likely elements of that chemistry, not least because both are extremely abundant in the universe. And so I think although some of the details might be different, you know, maybe they wouldn't be using something like DNA, maybe they would have something else. But I do think that carbon chemistry is, is pretty incredible. It's, it's extraordinarily carbon is a very gregarious element that's able to form all kinds of bonds with all kinds of different elements and including itself. And so it can build chains, it can build rings, it can, and it can build things of indefinite length, but also very varied. So it's, I think it's really, I think it's a really amazing material.
[4:54] And that's kind of why it has its own branch of science, right? I mean, organic chemistry, is essentially the chemistry of carbon. Um, and, and so, and so I, personally, I am betting on, I don't personally, I don't think cosmic strings are going to qualify. I don't, I'm not sure I even really know what they are, but I, I don't think they're going to qualify. Um, and I think that maybe it's a lack of imagination on my part, but I think that wherever there is life, we will recognize it as life and it will be something not unlike what we have here. Um, but I think that there are really interesting questions as to how much like what we have here, will it be? Um, and also, frankly, if we don't find it somewhere else within the solar system, I don't think we're ever going to be confident that we have identified it unless they
[5:49] come to visit us, whoever they is. Oh boy. I'm imagining bacteria-sized spaceships. And maybe they've been here, but maybe we just couldn't see them. Well, and we don't, we don't have the, you know, I mean, so far we don't have, you know, so far all life can trace its origins back to a single common ancestor. It's still conceivable. We haven't discovered everything. Maybe there's something that's completely different that is already living here. We don't know. Um, but I, I think, I think it's, uh, I think it's a fascinating set of questions. I mean, maybe there's nothing more fundamental to understanding ourselves would be to find life somewhere else.
[6:29] Yes. And so I guess I'm a molecular biologist and I've studied the evolution of proteins and protein structure and function. So that's kind of where my lens is, but looking at a broader scope of biology, um, the way that you describe how life evolved is really different from how I was taught in school, but, but like also correct and also very fascinating. So in school, if anyone listening is not a biology person, we pretty much learned like the Darwin, um, evolution model, right? Like everything has a common ancestor. Um, but from your perspective, it really seems like you're looking at it from a totally different lens of things becoming more complex, but in terms of the things that they consume, am I correct?
[7:23] So I totally think that Darwin was basically right. Um, in terms of, you know, natural selection is the principle way that, that, um, organisms change over time. But I think that the driving force of that change is not as arbitrary as we sometimes like to imagine. I think that energy is central to, um, all life. Um, and I think that the, um, one of the ways that one can understand the history of the planet is to think about it in terms of, um, an expanding realm of energy available to life. And that's because life evolves to open up new energetic sources, but also the activities of life make new energetic sources in turn available. So you get a, you get a sort of constant expansion over time.
[8:14] And, and I think that that's, um, that helps to, um, to make sense of some of the patterns that we see in earth history. Uh, and I personally have found it really fascinating to, uh, to think about. What are some of the most concrete evidences of this being true? So if you look back in time, you can, you can, you can divide, and I don't really quite know the right word to use. I don't think English has the right word. So I used to use the word epoch, but I don't think that that's quite right because epoch sort of suggests something that has a beginning and an end. And I want to suggest something that is open-ended so that it starts, but it doesn't finish. And instead there's, so layer would be one possibility. So you get, you get a sort of set of layers, but each layer is itself an expansion and together you get more of an expansion. So,
[9:07] so if you look back in time, you could, I think you can divide earth history up into five energetic layers. And I know that sounds a bit odd, but that's the best I can do at the moment. But the first one would be life forms that evolve in the context of geochemical energy. So there are plenty of life forms around today, bacteria, but also archaea, which to those who don't know what archaea are, they look like bacteria. So for a long time, they were thought to be bacteria, but it turns out that inside there, they work in quite a different way. And bacteria and archaea, some of them can, they, they live from, from just eating gases and rocks. They live from the, from the raw materials of the planet. And they can, they can take carbon dioxide into the, into them themselves and make cell tissue the way that plants can, except that where plants use light, these organisms are instead
[9:59] they're using the energy from rocks and gases. And there's, the chemistry of doing that is quite a lot easier, um, less sophisticated, less complex than the chemistry of using light. So you can imagine a situation where the first epoch or layer was organisms that use geochemical energy. And I think that there's some evidence that this is the case, although going back that far in earth history is very difficult and we don't have a good sense of exactly what was there or even when life started. I mean, the planet is 4.5 billion years old, but most of the first 500 million years is obliterated completely. There's almost nothing left. So we don't have a good sense of what it was like. And by the time we start to see clear evidence of life in the fossil record, uh, it's clear that life had already, was already thriving and abundant. And so the, the transition period has been wiped out. And the reason that that's the case is that
[10:56] earth itself is a very active planet. It has volcanoes. It has plate tectonics. It's constantly, things are constantly being eroded. And, and so ancient rocks are just in very short supply. It's possible that there are places we haven't looked yet. Um, it's possible that the, you know, there are parts of central Africa, there are parts of Brazil and China, possibly even parts of Russia that might have some ancient rocks that would reveal things. It's also possible that the moon has some ancient rocks because early in earth history, there would have been a lot of meteorite impacts and maybe some bits of earth are sitting on the surface of the moon. And if we were to explore the surface of the moon, perhaps we would be able to find remnant bits of earth that are older than anything that we know about here. Um, and so that might also give us some insight. Um, but the point is that, that this also suggests
[11:48] that, that if, if the first life forms, um, lived from geochemical energy, they might also have been produced in the context of geochemical energy. So they might've emerged within the planet, um, perhaps even quite deep within the planet before going on to, to, to colonize more broadly. Um, so that seems to be, from what we can tell from looking at genetics, from looking at what there is in the rock record, it seems that geochemistry was the first energy source for life. And then, but then fairly soon, you start to get organisms that can use light. And these would not have been plants. They would instead have been bacteria mostly. And so the other ones haven't gone away. So you have a new layer of life on top. Um, and together they start to, to live in maybe quite large communities because as you know, bacteria often live in, they're often very sociable. They live together in big communities or, or mats.
[12:45] And you start, you start to get things, these large communities of bacteria living together, um, in the shallow waters of, of the earth. And some of these went on to be able to, we don't really know the sequence again, it's pretty obscure, but some of them went on to be able to, in the process of using light to, to basically what they do is the light, uh, excites electrons. And then they use the electrons as they float, as they fall down to lower excite states of excitement. They use those that, that, that, that sort of run of energy. Think of, you know, water flowing down a hill. That is the same sort of, the same sort of idea. Um, they're, they are able to, um, to use the energy of, of light to, fuel their metabolism. And some of them started to use light to split water molecules.
[13:36] And once that happens, I mean, it's, it's really quite an astonishing thing, but once that happens, then you start to have the availability of molecular oxygen O2. And so that's one of the things that I think is really surprising when you look at earth history, actually the first half, all of the oxygen atoms were tied up in water or in carbon dioxide or in rocks. And they were not, there was no oxygen to speak of in the air. And so it's only thanks to the activity of these cyanobacteria, as they are called, that they used to be called blue green algae. When I was first studying biology, they were blue green algae, but the cyanobacteria, um, evolved to split water and release oxygen gas as the, the way that we breathe out carbon dioxide. And that would go on to transform the earth. Um, first of all, it, it makes the, uh, it completely transforms the, the physical
[14:34] environment. Um, but it also transform, it, it permits a different kind of biology, a much more, um, a much more abundant kind of biology, because it's, uh, it, it is in the context of oxygen that something like eukaryotes, which are the first complex cells or more complex because bacteria actually pretty complex. Um, but it's in the context of oxygen that we start to get this, that we start to get the sorts of processes that would eventually, uh, result in something like you and me. And so I know that you said that we don't know where the origin of these bacteria came from. Like, what is the origin? I've heard the term primordial soup, um, being used in this context. What are your thoughts on the primordial soup?
[15:25] I think it's nonsense. Really? Well, I would love to know why, like what, what's your, what is your rationale? So there are a couple of different ways that one can think about the origin of life. And you know, this is my analysis of reading the literature. I don't have any original ideas about how life began. I think all I have to contribute is a, is an assessment of some of those ideas. And there are several different ways that one can approach thinking about the origin of life. And I should say that there are a few fields of science that are more acrimonious where people dislike each other more. And it's partly because there just isn't that much data. And so, and you know, nobody has managed to generate life in the laboratory. Now, even if they did, it wouldn't mean that that's how life happened here because ultimately it's a historical question. What happened? And we don't know because we don't
[16:27] have any evidence from that time. Nevertheless, if somebody generated life in the laboratory, it would be very impressive, interesting, exciting, and a powerful proof of concept. But the, so, okay, so, so there are, you can approach, uh, the origin of life from biology working backwards, or you can approach it from chemistry working forwards. You can also think, well, biology is, um, you know, there are two general types of lifestyles. One is like us where we eat things in the environment and one, and we require organic molecules. We require complicated carbon molecules to support ourselves. And the other is like, like these, these bacteria and plants where they, they, they basically are growing from the inorganic world. And so those are sort of two camps, the, the eating organic molecules and the, uh, inorganic world camp. And the primordial soup camp is the, is eating the organic molecules. So primordial soup somehow suggests, well, there's all these organic molecules floating around and somehow they come together. And
[17:36] I don't know. I never had any soup come alive myself. I mean, I, I'm maybe, but it just seems to me to be very unlikely. And I think when you start to look at some of the other ideas, which are much more around process, um, it, to my mind is much more compelling. Mm-hmm. So my partner is a theoretical astrophysicist. And so he uses math to explore black holes. And you said that we can use biology to work our way backwards and chemistry to work our way forward. Where does math come into all of this? Does math play a role in this at all? Um, I think for this, maybe not because it's mostly experiments. Um, so, so I think, I mean, you know, I think math, math certainly comes into biology, uh, and math comes into understanding, um, energy in biology. But I, but I think that it's, I think that for the origin of life,
[18:42] I'm not convinced that that a theoretical model of the origin of life would get us any nearer than any number of experiments. But I do want to say a couple of things about the primordial soup, which is the, about the idea, which is that it is true that when you look at some kinds of meteorites, they are full of carbon compounds. They are absent. Some of them are so rich in carbon compounds that when they're first discovered that they still smell of oil, um, because they are so, but that doesn't mean that it was the delivery of that sort of material that facilitated the first life forms. What it does tell us is that carbon chemistry is very prevalent in the universe.
[19:28] And I guess the ultimate question, one of them, there's many ultimate questions. Um, what would drive something like a primordial soup to want to generate metabolic activity? I think that that's right. And so, you know, again, this is where there are lots of questions around what is the fundamental process of life and are the processes of life that we see today the same as the ones that initiated life. And, you know, a biologist, I think, would say, yes, a chemist might say no. Um, so I think that there are still open questions and fundamental disagreements. But my feeling is that primordial soup has nothing whatsoever to do with it.
[20:11] Fantastic. Everyone, you heard it first here, primordial soup, throw it in the trash. I can get down with that too. I couldn't really quite make sense of it either. And it just seems like a lazy, a lazy theory, really. I think that it's, it's fun. It might be a great sci-fi film, but probably a lazy theory for us to base like all of biology on. So let's talk more about the layers. Okay. We talked about the organisms that metabolize inorganic material. And then we moved to plants. Bacteria, photosynthetic bacteria, photosynthetic bacteria. Okay. Yeah. So we're before plants, but I'm guessing that this is going to lead us to plants.
[21:05] Would you mind if I put it a little differently? Would you mind if I say, would you mind if I say that it results in plants? Oh, because leading us to suggests that evolution is attempting to go somewhere. Yes. And a lot of the time, well, all of the time, it's not attempting to get somewhere. It just sometimes does get somewhere. But I mean, there's, I think there's a big difference between looking forwards as time is, as, as, as you move forward in the history of the earth and backwards from here and backwards from here, you sort of think, wow, you know, it's really weird land plants. They don't appear until 400 million years ago, but the earth is four, more than 4 billion years old. And, and, you know, land plants are late and that's true. But at the same time, evolution isn't attempting to make land plants. And so that it, it just took that long for the particular sequence of
[21:59] events to unfold that resulted in land plants. And I think, so, so I think this is really interesting, actually, because it reveals that from such a fundamental aspect of our own world. I mean, when I look out of the window, I see leaves and I see trees and, but those, that was missing. If you were, if you had a time machine for most of earth history, for more than nine cents of earth history, the only thing you would have seen on land were, were basically bacterial mats. It was a flat land, a mass slime, slime and crusts. And, uh, yeah, exactly. Wow. Huh? Like a huge biofilm.
[22:43] It sounds like exactly, exactly. I would like to talk about endosymbiosis. This is actually something that I don't understand. Um, and I can say that proudly, you know, that's a huge thing on this podcast is there, there are a lot of things I do know and a lot of things that we don't know. So can you explain endosymbiosis and where does that place, does that have in this process? Can I answer that question by backing up a little and just, I'm just talking about earth history. So, so it seems that these two groups of bacteria like organisms, the bacteria themselves and the archaea, it seems that they evolved simultaneously. Neither seems to have been first. They're very, they're close cousins, but neither is descended from the other. And let's say that the origin of life was around 4 billion years ago, sometime between 3.7 and 4 billion years ago. And so the ability to use light starts, nobody really knows, but maybe let's say, let's, let's say 3.4 billion years ago,
[23:49] maybe it was a bit earlier, maybe it was a bit later. And then oxygen appears in the air in large quantities around 2.3 billion years ago, which is roughly halfway through earth history. So for all of that time, the only inhabitants were bacteria and archaea. That's a long time for just bacteria and archaea. Then after oxygen appeared in the air, and I should say that it wasn't enough oxygen for you or me to have enjoyed ourselves. It would, we would, you would still have needed an air supply had you gone back to, to the earth after this transition to an oxygenated atmosphere. But at some point, something odd seems to have happened, which is that a lineage of bacteria and a lineage of archaea and archaea seem to have fused together. And that fusion produced what we call the eukaryotic cell. And the eukaryotic cell, so, you know, I know that you know what a eukaryote is, but I think
[24:44] it's a really interesting word because within biology, everybody knows it. And outside biology, nobody knows it. That is pretty bizarre. And yet it's a fundamental distinction, right? Because the eukaryotes, they all have, they have a cell nucleus, which bacteria and archaea do not. They, they generally reproduce by, um, meiosis and, and syngami, which we casually call sex, but bacteria and archaea do not. Um, and, and so it's, it's sort of, there's a, there's a, they're really quite different from what was there before. And yet they emerge from some process that led two forms to grow together. And they also have mitochondria. Now I should say that, that you can, there's a, there's an interesting thing about the history of the word eukaryote. So for most of the history of people, you didn't need a word like eukaryote because everything you could see with your naked eye actually was one, you know, all of the plants, all of the animals, all of the mushrooms, they all belong to the, to the group
[25:44] known as eukaryotes. And so do amoebas and a lot of other single celled organisms. And they all, initially the word was coined to tell the difference between two kinds of single celled organisms, bacteria on the one hand, and these other things that had a cell nucleus and mitochondria. So mitochondria are often called the powerhouses of the cell. But they are actually the relics of bacteria. And so this seems to have been the first, a genuinely new phase in the history of earth is you get these new cells called eukaryotes. And they seem to have arisen as a fusion between bacteria and archaea. And they do seem to be, you know, you see the relict of this fusion in the form of the mitochondria, which was once upon a time of free living bacteria. But the cell is not just an archaeal cell with a bacteria inside. It's a much more complete remaking than that. They both became
[26:47] remade and integrated together. And then that happens maybe 1.8 billion years ago. And then nothing happens after that. There was no really big change. There's a time in earth history that geologists like to call the boring billion. And it seems to really be so that everybody else can say, no, no, no, no, it's really the very interesting billion. Because nothing happens. So like, population, looking at the population of the different species, species on the planet, they were growing in number, right? Like, during this boring billion, just really hilarious. The eukaryotes were having, they were doing sexual reproduction, right? And then the archaea were doing asexual reproduction, the bacteria were doing asexual reproduction. So the eukaryotes are doing sexual reproduction with each other, and they just stayed separate?
[27:49] It seems to have been a complex ecosystem with everybody there, but just not very much change. It seems to have been rather static. Nobody knows why. Nobody knows why. And then around weird. It is odd. And I think it's very interesting because it does also, it's a good reminder, again, that evolution is not trying to go anywhere. Just that, you know, things are evolving, things are changing, but there's nothing particularly dramatic going on. Question. Because endosymbiosis really just seems at face value that a bacteria decided to just eat in archaea. And it just was like, well, we're going to just be stuck together. And like, so what exactly do we think happened?
[28:35] That is almost as contentious as the origin of life. Oh, really? Come on. I'm so tired. Nobody really knows. Nobody really knows. Because bacteria in archaea don't usually eat each other. They usually import small molecules. They just don't usually eat each other. Sometimes they kill each other and then eat the remains. But they usually don't do this thing of gobbling somebody else up. And so it's very puzzling how it happened. And it's puzzling what happened. But the thing that is interesting about this is that once you have it, it's actually a feature of eukaryotes that they are able to do it again and again and again. So in fact, and it's a feature of bacteria in archaea that they do not have endosymbionts. They sometimes have close associations. I think there's five examples, five or six examples known. And they are all super weird. And none of them is in the cytoplasm. So a lot of bacteria, as you know, they kind of have, they have a cell wall. And then
[29:38] sometimes they have a, they have a sort of space between the cell wall and the cell membrane. And a lot of the, insofar as there, there are these, these endosymbiotic relationships, it's stuck, it's stuck between the cell wall and the cell membrane. It's not actually really inside the cell proper. And so something fundamentally different and certainly singular, as far as we know it only happened once, something peculiar happened. And, but once it did happen, it happened again and again. So the relationship, you know, the, the origin of green algae, for example, involves another endosymbiotic event where the eukaryotic cell took up a cyanobacterium and the cyanobacterium became the chloroplast. And so, and ultimately that would result in land plants. And so all of, all of land plants have, you know, so, and each of these things has their own genome. So the nucleus has a genome, the mitochondria has a genome, the chloroplast has a genome. And so land plants,
[30:43] they have three genomes. And this is me not ever having delved into plant science. I did not realize that chloroplasts had DNA. They had their own DNA. They have their own DNA. And that is probably why plant genetics are so, was so frustrating to me because there's a lot going on. Oh, plants lead super complicated lives. Yeah. I think I, I did study that at one point and I just completely erased it from my memory. Cause I'm like, you know what? I'm just going to stick to the eukaryotic system. This is too much. Shout out to the plant geneticists, but whoa. Okay. So I'm thinking, and maybe this is already a field of thought. I'm sure it is. Cause nothing's new under the sun these days, but is it just possible that there is a change in like receptor, um, surface receptors on these, um, two organisms that became compatible and then just ended up being that, oh, I just triggered like
[31:46] a phagic event. Like, I don't know. Yeah. I don't know. I don't know how it happened. I mean, I, I mean, the thing that's so puzzling is that, is that it does only seem to have happened once, which suggests that normally, yeah. What does that mean? Like one, it means it happened in one population. So we, we, it's not like we look around and we see that, that, you know, there's lots of different things that we would call eukaryotes that had completely different, um, that arrived at this way of life completely independently. Everything that, so if you, if you think of the, the tree of life, you have this sort of, you know, you have the, the typical thing where you have an origination and then speciation and, and sort of branching off. But then what seems to have happened is that these two lineages fused again, and then you have a new branching off and all eukaryotes can trace the,
[32:41] can trace their ancestry to that fusion. Um, and, and so it seems like, I don't know. It just seems like it was, it was something that happened around 1.8 billion years ago. And yeah. Wow. I mean, it's kind of humbling. And I think the fact that it only happened once, it has made me feel less optimistic because this was the event that permitted ultimately the evolution of something like animals and plants. And I think had that never happened, it's likely that it would have just remained bacteria and archaea. Absolutely fascinating. So that makes me sort of a bit more pessimistic about the chances of finding large life forms somewhere else.
[33:32] Not even looking at the planetary Goldilocks situation that has to occur for life to be like Earth-like life to be on in other places, then the chemical reactions that have to take place and the perturbations of like the genetics and, oh my gosh. And the chances of the genetics even being the same. I know. Because genetics isn't even like the same across the board in, on Earth. Like we've got, we've got circular DNA, we've got linear DNA, we've got RNA, like there's so much stuff going on. Okay. So can we talk about RNA? Do you get into RNA at all? And like the, the different kinds of genetics that we see here on Earth?
[34:20] I'm not the best person to talk to about RNA. I think I'm, I'm very interested by RNA, but I'm by no means an expert on RNA. So I think I'm probably not the best person to talk to about that. Okay. Except to say that it's, it's infinitely surprising. Exactly. I think so too. And I mean, while we're on the topic of microbes, do you have any opinions on viruses? Um, I do. Uh, I, I, so one of the historical questions has always been, are viruses alive or not? And so for readers who are not sure about these things are not sure of what a virus even is apart from something to avoid. Um, viruses are, they're not cells. So all life forms that we know about have originally, they were single cells and then some of them came together and lived in, in sort of communities. And, and so you do have, you know, you and I are, uh, uh, are multiple,
[35:16] multiple cells, um, you know, but still the fundamental unit is the cell and they, they organize themselves into organs and tissues and so on and so forth, but still cells and viruses are not cells. And they don't have all of the processes of cells. In fact, they don't have any processes at all. They're basically just nucleic acids. So either DNA or RNA inside a protein envelope with occasionally some fats as well. And for a long time, people thought, well, maybe viruses are somehow on the border between life and non-life, or maybe they're somehow, um, they were part of the transition from non-life to life. But to my mind, so I used to think the viruses were alive because I used to think about life as being about evolution and because viruses evolve over time, I thought, well, that allowed them to count as being alive. But as I've expanded my understanding of life and it's gone
[36:13] less about evolution and reproduction and more about, about the processes of metabolism, I have concluded that viruses are not alive. Um, that doesn't mean that they're not important. So they can, they are of life, they're created by life and they affect life and shape life in all sorts of ways that we don't usually appreciate when we just think about them as disease. Um, but they are not alive in my view. I agree. And I'm glad to hear you say that because I got flamed on Twitter for suggesting that viruses were not alive. And I, then that prompted me to create a quiz or a poll rather of my audience of over 150,000. And it was almost split 50 50 on viruses being alive or not alive. Granted, I don't have a fully scientific audience, but there were scientists in the thread discussing this and saying, well, you know, have you looked at the megalovirus and, you know, well, it can, it's capable of hijacking
[37:21] host machinery to replicate itself. So doesn't that count as alive? Like, even though it can't do it on its own, but then I'm like, well, that's the whole point. Like it needs to be able to do all this on its own. So do you think that it is something that should still be up for debate? Or do you think we should kind of close the book on this? I think we should close the book. I think that one of the distinctions one can make is that viruses do not replicate themselves. They are replicated by cells. So there's always an intermediate step where the cell is making new materials on behalf of the virus. This doesn't mean that viruses are not complex and that they don't, I mean, you know, plant viruses have proteins that, that help viruses become transported through the plant tissue. I mean, these things are extremely important and interesting, but personally, I don't think they count as life.
[38:13] But I think to some extent it's also, you know, I mean, if you looked at corpses, you would see the corpses evolve over time. Corpses are produced by life, but they're not alive. That's the point. They're deceased. And, and so I think it's, I think it's the same. I mean, there's another interesting difference, which is that there's no great family tree of viruses. Viruses appear to have originated multiple times. Nobody knows exactly how many times, but it seems that there's, and nobody knows exactly how, but there do seem to be different processes going on. I would also say that there's something, you know, this, when you look closely at what bacteria are getting up to, there's all kinds of weird stuff. And first of all, they can put naked DNA from the environment into their own DNA. That's kind of weird. Um, they, they also, they, they make, some of them make something called a membrane, membrane bound vesicle. And basically they sort of bleb off a bit of
[39:07] themselves, which has some proteins and some DNA, and that can be used by other bacteria to do things. So I sort of think of viruses as being in that sort of category. It's a sort of subcellular thing that is produced by life. Certainly it has big impacts, but I, yeah, I, I'm, I don't think it's necessary to think of them as, as alive. And I think it clarifies things actually to not think of them as alive. Yeah. I agree. And so how do we get from a cyanobacteria, from a eukaryote, from archaea? How do we get to us? Like what, what exactly do you think was going on to get to us? And now we're on a podcast on zoom.
[39:52] I'm like, yeah, it's strange, isn't it? Isn't it? Isn't it? Isn't it cosmically strange? I mean, yeah. So, so the eukaryotic cell, the origin of the eukaryotic cell explains how you go from bacteria and archaea to a different kind of evolutionary potential. And the eukaryotic cell appears to have the potential to have many more genes, many more proteins, capture more energy. And eukaryotic cells also began eating other things. I mean, if you think about an amoeba, it goes around and it eats things. And there was an amazing paper published more than a hundred years ago in the American Journal of Psychology called A Day in the Life of Amoeba Proteus. And in this paper, a couple of guys spent, I don't know, a week watching amoebas 24 seven. And they reported on what the amoeba did.
[40:48] And this was interesting because at the time, amoebas were actually thought to be more primordial than bacteria. And that's because until you have an electron microscope, you can't see the cytoplasmic membrane. So a bacteria has a cell wall and you can see that with a light microscope, but an amoeba without a, if you just have a light microscope of a, of an early kind, all you see is this sort of blob of cellular material doing things. And, and it's not clear how it holds itself together. Later, it became clear that actually it's much more complex than most bacteria and it, but one of the observations that these people made in the course of their, their research was that amoebas have voracious appetites, but they always rest after lunch, which is to say that once they've eaten something, they, they rest and digest. Um, and they never eat dead things. So they only take up live prey. And so this, the eukaryotic cell allowed the
[41:46] origin of a certain kind of hunting and there's devouring, um, taking up other organisms and needing them whole. And ultimately some lineage became a cooperative. And again, unfortunately, unfortunately, we don't know how it happened, but led to, or resulted in, resulted in animals. Uh, and the first animals that we know about, it's not exactly clear what they were. Maybe they were something like a jellyfish. Maybe they were more like a sponge. It's argued over and controversial, but then at some point you ended up with bilaterians, which are the one, the organisms with bilateral symmetry. And at that point, the earth changed again. So if you look back in time, you see these, these sort of pulses of big change. And one pulse of big change happens after the oxygen accumulated in the air for the first time when you have a proliferation of new minerals, for example, because oxygen is so reactive. And then after, once you have hunting animals, you again get a big pulse
[42:56] of geological change. Um, but you also get far more life. And this is really, it's really remarkable because, okay, so I'm going to get really enthusiastic here. I think this is fascinating. So when you think about the sea, it's very different from what happens on land, what the ecological processes are different in the sense that on land today, there are trees that are, that, you know, and you have insects that eat trees and birds that eat insects and birds that eat other birds and so on and so forth. But in the sea, everything is being supported by the activities of single cell organisms to a very, to a first approximation. So you have bacteria and you have algae on, and that is supporting the fundamental primary energy, um, that comes into the system is coming through those organisms. And then you have other things eating them. And all of the animal biomass is being supported by single cell organisms. And it's
[43:55] really, I find this incredible. I mean, it basically, and what it basically seems to do. So, you know, if you have, if you're growing bacteria in the lab, um, they'll grow in an exponential way, and then they'll, and then they'll sort of flatten off, they'll reach a stationary phase when they can't, they just can't have more bacteria in the, in the food broth. But in the sea, because you have this constant mowing, you have a constant keeping of everything in a sort of exponential growth phase. Um, and that permits all of the abundant marine life that we see today. And I find that really cool, that it's all being supported by single cell organisms.
[44:30] Yeah, that was something that I found fascinating. Um, when I thought about, I was thinking about how people usually take like fish oil to get their omega-3 fatty acids. But then I learned that it actually comes like the fatty acids actually come from the algae, um, that the fish are eating. And I was like, dang. So I didn't need to have this fishy breath after I was taking those, um, fish oil pills. Uh, thank you, science. So, um, now I take plant-based omega-3 pills. Um, but that is something that really caught my attention. And I'm like, wow, algae is really important. It's, it's creating oxygen. It's generating nutrients that not only the fish need that we eat, but like we need as people or that keep us sustained and healthy and nourished. And yeah, I, I kind of want to dig deeper into that. Um, what are some fascinating things about the single celled organisms in the sea that maybe we don't think about on a regular basis?
[45:39] Well, I think one of the things that's fascinating is when you're a single cell, you are able to detect differences in the environment that we really don't notice at all, because we're just too big. We, there are, so there are gradients of oxygen, for example. And it turns out that let's say you have a green alga, a single cell green alga in the sea, it's giving off a stream of oxygen. It's being chased by bacteria, trying to get into the oxygen, trying to use the oxygen. And what? Oh my God. Are you serious? Yes. And they're like, are they like trying to swim? Like they're swimming along there. They're moving along there. And this is the thing that I find so interesting is that there is so much, um, sensitivity to the world that, that we can't detect easily. That is beyond our easy, um, understanding or, or appreciation. And yet these other organisms, they, they can, they, you know, they can detect things. I mean, they,
[46:39] there are some bacteria that, uh, that they, they make, um, they, they take in iron and they use the iron to make magnetite, which is a metallic, which is a magnetic mineral. I was just going to ask you about magnetic field sensing. Please keep going. I'm so excited. And they use these, they basically are like living compass needles. They're full of, they're full of magnetite and this allows them, well, I don't know if this is really true, but the Italian who discovered them claimed that he noticed a whole load of bacteria swimming north. I don't know if that, I don't know if that's really true. It sounds apocryphal to me.
[47:16] Um, I'd be really scared and intrigued, but it is true that they are able to, they are able to detect magnetic fields and to use the magnetic fields essentially to narrow down how they're looking for food. Um, because they just, they use it to, to, you know, and some swim towards light, some follow the magnetic field lines of the earth, and that brings them into an environment that is good for them. I find that fascinating. I often wonder, like everyone else in the world wonders, what would it feel like to have that, that sense? Like we have what, five senses? I forget all the time.
[47:57] Um, taste, touch, see, smell, hear. Um, but what about like magnet, magnet feeling? Like, what would that be like? Would I feel physically drawn to true north? Like, what does that, what, what is, what would even, I don't know. It's really hard for me to think about. I think about birds, have this bacteria, dolphins, I think some, like some marine mammals have this. I don't know. This is not my field, my, or my lane, but really cool. Some people think that humans do, but the experiments are, um, not universally appreciated. Oh, interesting. I'd be, I'd, I'd want to look into that. I feel as though a lot of conspiracy theorists are going to like, really, really get on that and be like, I am a compass. Like,
[48:51] oh my gosh. I don't, I don't know how that would interfere with the tinfoil hat. I think you'd be fine. Oh my gosh. Okay. Wait, so I want to, I want to go back to something really interesting. You said that the amoebas at some point became cooperative. So we don't know, and not necessarily amoebas, but some kind of single-celled eukaryote ended up living in communities. Okay. Okay. And so how did it become that we got stuck together? Like multicellular? We don't know. Oh no, we don't know anything. That's the fun part about being a scientist is like, we get to explore the things that we don't know yet.
[49:41] Well, and that's the thing. I mean, I think that that's what I didn't understand when I was studying science in high school, for example, I didn't, I mean, in high school science, when I was doing it, it was, it was really presented as, as information you needed to learn. It wasn't presented as a world of mystery and wonder with a lot of open questions, but actually it's a world of mystery and wonder with a lot of open questions. Yeah. I mean, I, I wonder like if people knew that science was as cool as reading a thriller novel or watching your favorite Netflix show, like it's really fun.
[50:22] But I do want to get back to the multicellular aspect of us. We are so complex, right? Like we have a brain, like brains are even in itself ridiculous and cool, but the brain does one thing. Our nervous system relays messages to the rest of our body. Like we have, um, neural transmitters, we have digestive systems, we have all these like small and large and everything is complex. Everything is a system. And also when you look at like the time, it seems like the complexity really didn't come until later. And so what kind of environment or I guess what series of events could encourage such a fast boom of complex nature?
[51:17] Well, I think the way that I would think about it is that, is that a series of changes started and then it's like it opened a door and, and there was, and this particular series of changes turned out to have enormous potential for more change. And there was something about the world at that time that allowed those changes to be expressed. Um, and so you really do, I mean, you know, starting around 400 and 540 million years ago, you really do see an explosion of new kinds of, of, of animal forms. And that really hasn't stopped. I mean, it's, you know, there, there have been continued to be new animal forms, um, since that time. And it's, and it does seem that however it happened, some, something arrived at what you might, I, I think of it as a new energetic architecture. You arrive at a, at a, at a, at a, uh, physiology that, that permits much more change. Um, and, and that this
[52:23] then went on to, to change the earth. Um, I mean, no doubt. I think this is fascinating. And so what about, since we're talking about like consuming things, I sometimes think about information as well, like as a source of just, it's a thing, right? I, I don't know. Maybe it's because I study like DNA and molecules and I, I kind of view that as information. And this is a really abstract thought, but how do you feel about technology being sort of a fuel for the next layer unraveling? So, I mean, I, I mean, one can certainly imagine that, you know, there was the eukaryotic cell and then there was, then there was the animal and then there was the animal machine fusion. One can imagine that. I don't know if that's what's going to happen. Um, and obviously, I mean, information is something that can be looked at mathematically. I mean, that's a good place for,
[53:27] for math and biology to intersect. Um, I mean, we do seem to be in a new information phase. I mean, humans, that seems to be part of, part of being human seems to have been new modes of information, like culture, for example. Um, and in the process of that, we seem to have generated, um, machines that are themselves able to engage with information. Um, I think that it's going to be a very exciting time in the next, uh, in the next period. We don't know how long it's going to be, how fast it's going to happen, but it, one feels that one is in a big informational change. But I want to say just to, just to remind everybody about energy that, that all of that information processing requires a lot of energy and the, for example, all of these large language models and chat GPT and so on, they need a lot of energy to keep going. Um, so, so ultimately the, the, you know, the, the ultimate driver of all
[54:31] of it or, or the, the ultimate, the ultimate, the quantity that allows all of it is again, energy, the availability of energy. Wow. I honestly wasn't expecting you to say that. That is very thought provoking. And we are going to be speaking with an AI, um, scientist in the next season. So I'm really interested to hear what they have to say about like the evolution of AI. Um, Oh, interesting. Okay. So what if, and this is kind of like a playful hypothetical, I've seen that we're trying to do like, well, not trying we have done, we've created nano robots, right? What if nano robots fused with eukaryotic cells and they in themselves developed their own endosymbiont that went on like, is that plausible? I have no idea, but it's certainly fun to think about, right? Oh my gosh. Yeah. You've given me a lot of creative juices to get flowing. Oh my gosh. Okay. I, we're coming up on time. I know
[55:46] I'm going to like, want to reach out to you in the future with a list of questions from our audience. But in the meantime, I would love for people to know where they can find you so that they can bug you with all of these amazing thoughts that they're going to have. Well, I'm kind of hermit like, um, Oh my gosh. Um, I, I'm, and I'm sort of embarrassed to say that the easiest way to find me is, is on LinkedIn. Um, that's not embarrassing. That's at least you're somewhere. I, I plan to emerge on blue sky, but I, but I'm still, I'm still, um, the, the difficulty is I've been, I've been very absorbed in, in thinking about earth history and, and I, I've, I've been not very, uh, not very hands-on with social media. That's fine. We want to protect you anyways, because it's a dumpster fire in a cesspool and you don't need to be there.
[56:43] Well, I, I feel that I would like to be, but I, but I, I'm not, I'm not quite ready. I'm standing on the brink. I'm, I'm getting ready to jump. Well, we'll be here with you every step of the way. Yes. So that means everyone listening, you're going to have to go through me to get to her. I feel kind of like an important safeguard of like this precious gem of science. No, no, no. So you're very kind. Thank you very much for, for inviting me. And, and it's lovely to, it's great to chat. Of course. Thank you for your time. Like I, this is the stuff that I'm very passionate about and you obviously are as well. And I can only hope that we inspire the people listening to think deeper about themselves and, um, really just take the time to reflect on how special we all are. And, you know, to extend this out to the social lens,
[57:33] um, the differences that exist between us really aren't that different. I read that humans themselves are 99.9% genetically identical or at least similar. So if you think about it and also we share like 50% of our DNA, at least with bananas or something I've read. I mean, we're all very alike more than you know. Well, I think, I think I would, I would like to add to that, that we're all of us, whether we're talking about bacteria or mosquitoes or, or earthworms, we're all made of the same stuff and we all have the same fundamental challenges and the same fundamental challenges to find enough to eat, to find a way to reproduce. We're all, and, and what I like to think about it, I like to think about the, the whole living world is, as sort of little tiny hurricanes, hurricanes of energy and matter and information. And when you look around, you see so much beauty and wonder in the world and we're
[58:32] connected to it through, through ancestry and through, through the, the connections of the air and the sky. And we're all part of the same thing. And I find that amazing. I can't think of a better way to end. Thank you all for listening. I can't think of a better way to end. I can't think of a better way to end.