Origins of life (featuring Dr. Katrine Whiteson)

26:06He hadn't been on a plane before without his family. It was so pure. Listen to Joy 101 with Hoda Kotb on the iHeartRadio app, Apple Podcasts, or wherever you get your podcasts.

26:21Our town is small taters by most standards, right? But to the people who grew up here, it's everything. What happens when a quiet Tennessee town becomes the front line in a battle over the future of America? Developers with right-wing ties have purchased hundreds of acres of land in the area. The first thing you see when it pops up is pioneers in Appalachia. But they weren't just planting houses. We need cities on a shining hill that exemplify and embody the Christian way of life. Stop right there. Is that normal? A podcast about what happens when a small town becomes the site of a social experiment.

26:58God need men to rule. Great. And decides to fight back. Do not use my hard work to sell your bull. They're not just opposing what's being planned for here. Our hometown is not a test tube. They feel like they're standing in opposition to an entire administration. Guess you didn't move in on a bunch of dumb hillbillies now, did you? Listen to Our Town on the iHeartRadio app, Apple Podcasts, or wherever you get your podcasts.

27:36All right, we're back. We're talking about what is life, the origins of life. and we're trying to keep Katrina from being too bored. Kelly, what are we talking about next? Oh, no. Well, the good news is we're talking about bacteria-related stuff. So I think that's going to – yeah, there we go. All right. So I'm on track now. She's interested, folks. That's right. So if you're trying to figure out how life came to be, you want to sort of know what the environment was like when life started. And to do that, you need to know when life started. And so basically we have to go to the fossil record to try to figure out where is the first evidence that we see something that could be life showing up.

28:17Also, this is like amazing, fascinating history, right? Like the deep history of life on Earth, like how things began. Wow, I would love to jump in a time machine and see all this stuff happen. And it's our history, right? And it happened a certain way and there might be clues that reveal it. So it's like some of the most fascinating science there is, in my opinion. Yeah, I agree with you, physicist, because it's biology that we're looking at. Okay, so there's a bunch of fossils out there from varying time points, and some of them we agree are definitely evidence of bacteria way more than we agree about some other stuff.

28:55So the most widely agreed upon fossil, as far as I could tell, was from Australia, and it's stromatolites that are three and a half billion years old. Yeah. Wow. About three and a half billion. Yeah. And so, Katrina, at this point, I was hoping I could throw to you and be like, what are stromatolites? But I didn't prepare you for that at all. So stromatolites are amazing evidence, we think, of life that's 3.5 billion years old. And it comes from microbial mats. We've talked about biofilms before. And so the stromatolites are layered rock structures that built up over time by microbial mats. We think they were primarily cyanobacteria.

29:37And they changed the shape of the rocks. This is like a morphological piece of evidence. So they would trap sediment and calcify the rock, and they created this huge macroscopic evidence of life on Earth. And it is a little controversial because there's questions about whether that could have been created by something that's not alive. But we think that biofilms, essentially, microbial mats of these cyanobacteria that did an ancient form of photosynthesis, so they were getting energy from sunlight, we think, and maybe also from some of the sediments in the rocks. and they left behind massive changes in the shapes of the rocks.

30:16And that's why we think there was life there. Wow. What is it about these things that makes it convincing that there's no abiotic way to reproduce them? Well, we know what those look like in modern times. And it really is the shape of the leftover calcified sediment that happened in a massive scale. And so it's a guess, or that's maybe the wrong word. But it's - It's an inference, yeah. It's just based on how they look. I don't think we have great other kinds of chemical, physical evidence. There is some isotope ratio, carbon isotope ratio evidence, but that signal can be debated. Also, they look really weird.

30:58There are these funny blobs sitting in the ocean, right? It's cool. Gotta be aliens. Yeah. Gotta be aliens. Kelly, don't go with the conspiracy theories. Come on. Sorry. That's what I do. All right. So in Australia, there's this stromatolite that is pretty broadly agreed upon as like definitely being a stromatolite. And that ages to about three and a half billion years old. There's also some other things that we found in like Canada, Greenland, some other parts of the world that could age older. Something like 3.7, maybe even up to 4.2 billion years old. And so definitely older than what we've seen in Australia.

31:36But all of these other instances are things where people debate, like, is that a stromatolite? We're not really sure. So we feel pretty good about this three and a half billion year old date. But it could be even older. It's just really hard to date stuff that's that old. And you're saying 3.7, and it might not sound like a big difference, like 3.5, 3.7, but that's 200 million years. Remember, it's been 66 million since the dinosaurs. So like 200 million years is a long time. It's a lot of podcasts. Yes. That's the best way to measure things. When I was a kid, we used to measure things in Ghostbuster episodes, that cartoon that was – so I asked my dad how many more Ghostbuster episodes.

32:18Anyway, 0.2 billion years is a lot of Ghostbuster episodes. Yes, exactly. So we're not totally sure. But now, Daniel, I'm going to put you on the spot. Oh, boy. There's a limit for how much we know about what the early Earth was like, or even our ability to age the early Earth. And we usually have to go outside of Earth to get these estimates for how old Earth is, for example. Why is that, Daniel? Well, the early solar system was hot and nasty, you know? That sounds like a judgment call. I mean that only in a positive way. This is getting too personal. Move on!

32:58Like, you know, somebody asks me, how's that pasta sauce? I get, ooh, hot and nasty. That sounds delicious. Anyway, so the early solar system, you know, collapses from a big cloud of gas and you get the sun and then you have little other gravitational seeds that coalesce heavier stuff to make like the earth and in rocky planets. And then the radiation from the sun blows off most of the gas. And so you expose the, you know, heavier stuff, silicon and carbon and all this kind of stuff and oxygen that makes up the earth, but it's hot. And so, you know, the rocks are constantly being reformed and because of the pressure, the gravitational pressure.

33:37So the early stuff is mostly destroyed. And so like, if you want to find out the age of the earth, you have to find like the age of the oldest rock, but a lot of the rocks from the early days had been remelted, right? They're gone. So that's why the age of the solar system is easiest to discover away from the earth and like asteroids right smaller chunks that were still molten early but cooled and have been frozen essentially ever since and have been like pushed down into the earth magma and melted yeah awesome yeah and so there's a limit on what we can even say about the early earth because it doesn't really exist in the same form anymore it's been like melted and reorganized and so we have found life that's 3.5 billion years old maybe there's life that's 4.6 billion years old i doubt it.

34:22That's as old as the Earth and the solar system is. But if it had shown up right at the beginning, it would have been just like obliterated and we wouldn't have fossil evidence of it anymore. But it's really important to understand this gap between when the Earth formed and when life formed because it's the only piece of data we have to speculate about how long it takes life to form, which is a big question, right? If life forms like almost as soon as possible after conditions are ready for it, that suggests with n equals one that it forms often when conditions are ready, right? Whereas if it took like billions of years, that suggests that it might take a long time on average and we shouldn't expect to find it everywhere.

35:01So it's like super valuable piece of information. Yeah, absolutely. Yeah, that's really interesting. But I feel like it also depends on having gradients of temperature and water and those conditions. I mean, if you got those right, you know, maybe it really just takes a much smaller amount of time with those conditions, which we obviously are not going to triangulate from evidence on Earth, but it's fun to think about. Yeah, totally. But another nice thing about knowing about when life popped up is that then you can try to figure out what Earth was like at that time so that then you can say, okay, what things were in the atmosphere?

35:37What are like the starting materials that we're likely to have? What's the temperature like and this isn't i'll note this isn't perfect because just because the earth was an average of i'm making a number up 100 degrees fahrenheit or something everywhere there's still a ton of variability right depending on if you're at the bottom of the ocean or something like that and so it's helpful to know but it doesn't necessarily tell us everything we need to know because there was a lot of variability depending on where you are on the earth but now that i've gone ahead and been like we're going to tell you what earth is like but it's not interesting because there was variability.

36:11Let's go ahead and talk about what Earth was like about three and a half billion years old. And we call this time period the Hadean, which is like the hell like. Hot and nasty. Hot and nasty, which Daniel's into. And so we could also call it like an autoclave. Oh, because, you know, these days, if we want to sterilize something, we put it in an autoclave, which is hot and high pressure. And I would call it extremely clean. So, you know. Oh, good. That's good. Maybe not great for life, but clean is good. Useful, yeah. Useful. That's right. So another thing is that the sun back then was dimmer, but because we didn't have an ozone layer, space radiation, UV radiation, hit the surface a lot more often, which probably also contributed to some of this sterilizing of the surface like an autoclave.

37:05The temperature and the atmospheric pressure were probably different than what we experience today. And partly that's because the atmosphere we think was made of different stuff than we see now. So eventually when life came around, we started producing a bunch of oxygen that got into the atmosphere, produced ozone, etc. But we think that some of the starting materials in Earth's atmosphere were things like carbon dioxide, methane, ammonia and water vapor. But again, not a lot of oxygen. And this mostly came from volcanoes, right? We talked earlier about how Earth's first atmosphere, like most of the universe and most of the solar system, is hydrogen and helium, but that was blown away because of the sun's radiation.

37:46And then we had a second atmosphere, which came from volcanic outgassing. And also you get like a bombardment from asteroids, and so some of the stuff on those melt. And that's where the second atmosphere comes from. Cool. Yeah, thank you for that. And yeah, so the asteroids that you're talking about, a lot of those fell during the late heavy bombardment, which was 4.1 to like 3.8 billion years ago, where we were just getting absolutely hammered. Though it sounds like a battle in World War II, doesn't it? It does. It does. But yeah, we got totally hammered. As I understand it, a lot of the craters on the moon are evidence of the late heavy bombardment because our craters got sort of like eroded away over time and you can't see them anymore.

38:25But there's evidence on the moon of them still. Although I think that's suspect now because we only landed in a small region on the moon and that might have been unrepresentative. So there's controversy now about whether the late heavy bombardment was a real thing or not. Really? I thought we knew a lot about the geography of the moon. We only know about the areas where we landed. We know a lot from observations, but we don't have samples from a lot of the moon. Oh, I see. Anyway, that's a whole other topic we can dig into in another episode. Well, but that's actually totally related to my next point, because now that we've laid out like, okay, this is what the early Earth was like, there are other people you can talk to, other experts who are like, yes, this story of what the early Earth was like has become very popular, very well known.

39:07But actually, there's a lot of evidence that we can't be totally sure that the early atmosphere had exactly the compounds that we were talking about. We could be wrong about a lot of this stuff. And it could be that the early Earth wasn't super different than Earth today, except that it definitely wouldn't have had as much oxygen in the atmosphere because that's definitely a sign of life. But so we're doing our best to guess what it was like, you know, billions and billions of years ago. It's amazing that we have anything to work from for something that's that old. But yeah, so I'm waving my hands in the air a little bit when I'm telling you about what Earth was like 4 billion years ago, because this is just the best evidence that we have right now.

39:46And it's amazing that we know anything about what happened billions of years ago. Like what incredible detective work, right? And as Hazel likes to say, science is like, stuff happened and we're trying to figure out what. Yes, that's totally, that's a good explanation. Okay, so now that we have talked about what early Earth was like, or now that we've admitted that we're not totally sure, let's talk about how life arose. And to figure out how life arose, we tend to want to think about how certain things that we usually see in life popped up. So, for example, lipids, these are things that are usually used to make the cell membranes.

40:28So to like give you a compartment that you can use to separate yourself from the rest of the world, for example. Carbohydrates, these are like sugars and cellulose. They are delicious. Amino acids, these are used to make up proteins. And nucleic acids, which are used to make up DNA and RNA. And so a lot of the folks who study origins of life are looking for conditions where you mix stuff together that were likely to be together about three and a half billion years ago or older. And then you wait to see, do any of these things pop up? And so like, what do you need to do to start getting these? But this is actually a pretty hard problem to think about because like often to get one of these things that we're talking about, you need others.

41:13So, for example, to get DNA or to copy DNA, that's done with proteins. So what came first, the protein or the DNA? And so trying to figure out how these things pop up and work together and in what order they show up is like a huge part of what this field is doing, as I understand it. Yeah, 100%. I mean, most things that happen in biology are possible without the help of all of our fancy proteins and cellular machinery. They're just very unlikely. They just take like a massive amount of time and energy. Biology is just easing the process and making it faster and more doable. So if you were to give things a lot of time and a couple of lightning strikes for some energy, then that's the theory is that a lot of these molecules may have started to just form on their own without any biology to guide them.

42:04and then maybe you're going to get into the RNA world hypothesis, Kelly. But, you know, we don't have to debate between DNA and protein because we have this intermediate molecule, RNA, ribonucleic acids that are able to do some of this chemistry that proteins are good at, and also they can store information. So they're kind of a jack of all trades of a molecule. So we think that life probably started there. But RNA doesn't have the same PR that DNA has, It's like fewer people know about it. It doesn't seem to get as much press. Like does Starbucks put it in their coffees with the big sign about protein shakes and stuff?

42:43So Katrina was talking about ribozymes, right? Yeah. We're going to jump into that a little bit more when we come back. But I wanted to end this segment, if that's okay, with aliens again. That woke Daniel right up. Yeah, what? Yeah. Before we go to the break, let's real quick jump into aliens again. And so there are some people who are talking about like, well, how do you get these four things with the conditions that we had here on Earth four billion years ago or something? And there are others that say, well, what if life just came here from space? And this is the panspermia idea where, you know, maybe life arose on Mars, something smashed into Mars and that rock eventually lands on Earth.

43:24And now Earth is seeded with life that started somewhere else. What do you think, Daniel? I think that's a really cool story. and it's really important to understand whether life started on Earth or somewhere else, because it changes how we feel about ourselves and who we are, and it's interesting. But I don't think it's really relevant to this scientific question of how life starts, because it just sort of says, well, maybe life started on Earth, or maybe it started somewhere else. It doesn't answer the question of how did it start. It doesn't really matter to me if it started on Mars and then landed here for the biological question of how does life start.

44:01Of course, I'm curious about whether we're all secretly Martians, but it sort of seems to me like kicking the question down the road instead of answering it. Yeah. It also impacts how often these things happen, though, getting back to understanding the initial conditions. I mean, if the conditions are so rare that it really only happened once somewhere in the universe, not even on Earth, that makes it seem even harder. Yeah. And I think we have no evidence at all really for like panspermia, especially directed panspermia, as some like professor from Harvard likes to talk about our interstellar visitors, maybe being like alien capsules containing seeds of life.

44:39Like there's no evidence for that. And if anybody was going to be excited about that, it would be me. So the fact that I'm being skeptical about it should tell you something. Daniel's never an alien's wet blanket, but but in this case, he is. So that's all you need to know. Follow the data. All right. Let's take a break. And when we get back, we'll talk about the Miller-Urey experiment and whether metabolism or RNA came first.

45:16home. This is Prose Society, the weekly podcast that's part book club, part group chat for thought daughters, pop culture obsessives, and anyone who thinks Pride and Prejudice and Love Island deserve the same level of discourse. I'm Eli Rallo, and every week we're connecting the dots between books, the internet, and the conversations everyone can't stop having. I'm gonna have to look up this story. I'm obsessed, so obsessed. From best-selling authors and your favorite book talk creators to the latest pop culture moments, nothing is off the table. It's like if you can hide some real messages inside compelling characters, then that is a Trojan horse.

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47:58He hadn't been on a plane before without his family. It was so pure. Listen to Joy 101 with Hoda Kotb on the iHeartRadio app, Apple Podcasts, or wherever you get your podcasts.

48:14Our town is small taters by most standards, right? but to the people who grew up here, it's everything. What happens when a quiet Tennessee town becomes the front line in a battle over the future of America? Developers with right-wing ties have purchased hundreds of acres of land in the area. The first thing you see when it pops up is pioneers in Appalachia. But they weren't just planting houses. We need cities on a shining hill that exemplify and embody the Christian way of life. Stop right there. Is that normal? A podcast about what happens when a small town becomes the site of a social experiment.

48:51God need men to rule. Great. And decides to fight back. Do not use my hard work to sell your bull. They're not just opposing what's being planned for here. Our hometown is not a test tube. They feel like they're standing in opposition to an entire administration. Guess you didn't move in on a bunch of dumb hillbillies now, did you? Listen to Our Town on the iHeartRadio app, Apple Podcasts, or wherever you get your podcasts.

49:29All right, we're back. Do you two remember learning about the Miller-Urey experiment when you were in school? Definitely. Yeah, they had like a flask of some stuff and they zapped it and it turned into more interesting lifelike stuff. Is that right? Yeah, I don't need to explain it. I mean, that's almost exactly what my notes have. I mean, in particular, they had ammonia, methane and hydrogen. So they had stuff that they thought was present on early Earth. Actually, they were using Jupiter's atmosphere as sort of a proxy for what they thought early Earth was like, which we no longer necessarily think was the right thing to be working with.

50:06But anyway, then they zapped it with some electricity to simulate lightning strikes and they ended up getting some amino acids. But one of the problems is that we no longer necessarily think that the world they created in this flask is necessarily like what we thought early Earth was going to be like. But it did show that, like, you throw some stuff together that isn't life and you start getting the building blocks of life out of it, which is pretty darn exciting. And since we've done a bunch of experiments where we've sort of updated the gases that are in there, the sources of energy that are being input into the system.

50:40And surprisingly, pretty often you do still get like things that look like the building blocks of life popping up. And so getting things like amino acids just sort of randomly in the environment doesn't actually seem like it's that hard. And so then the question is, how do you go from there to something that, you know, responds to Darwinian evolution or something like that? And so the question there is, do you start with metabolism? So the ability to do like chemical reactions that give yourself energy so that then you can do other stuff. And I've probably done a really bad job of defining metabolism because it still kind of blows my mind.

51:16So I'm going to throw to Katrina in a second. And then the other hypothesis is the RNA world, that maybe you started with RNA first. And then from RNA, you sort of structure things together and then start using metabolism to build things that are more complicated. So Katrina, go. I don't even really know. This is where I start to feel overwhelmed because this is where it becomes a lot of biochemistry. Yeah. Well, metabolism as a word, I find fascinating. And when I get asked that question when I'm over at the Integrative Health Center in the teaching kitchen and people ask me about metabolism, they're asking, you know, how can I boost my metabolic rate so I can, you know, lose weight and eat lots of delicious things.

51:59A good goal. Which is a good goal. But for, you know, what we're talking about for life is the chemistry of getting energy and using that energy. So, yeah, it's really interesting to think about that in the context of early life. I think it gets back to some of the seclusion and compartmentalization definitions that you were bringing up earlier, because everything runs on gradients. And so building up differences in concentration of molecules against a membrane of some kind is a way to store energy and to use energy to propel your processes forward. So in my mind, metabolism comes down to being able to organize systems for obtaining energy and using chemicals to do that.

52:45So let me see if I understand from a physics point of view. You're saying that we're looking for a process that we see a lot in life, which is use of energy to run yourself. And that we do this chemically by storing stuff up gradients, which sounds complicated, but it's basically like if you carried a bunch of rocks up a hill and left them at the top of the hill, that would have stored energy in it, which you could release when you wanted to by rolling them down the hill. And then the rock gets all this speed, which you could then use to like, you know, spin a wheel and grind your flower or something.

53:16Exactly. Yeah, that's a really good analogy. I like that a lot. But yeah, exactly. It's like pushing chemical molecules onto one side of a barrier and then that stores energy. I'm going to do my best to summarize one hypothesis for how life could have started around hydrothermal vents. but I'm going to preface this by saying this is pretty chemistry heavy, which we all know how I feel about that. Okay, so here's one idea for how life could have started. So if you are at a hydrothermal vent, the stuff that's getting pushed out of the vent is at a very different pH than the water outside of the vent.

53:54And so this is a gradient that can be used to generate energy. And so at these hydrothermal vents, you've got this energy source. These hydrothermal vents also have rocks that tend to be sort of sponge shaped. And if you look at a sponge, there's like all of these little sort of like pores and holes in it. And each one of those pores or holes could have acted sort of like a cell membrane, sort of separating into compartments so that stuff could happen in each of those different compartments. And so now you have like primitive compartments and you have a source of energy and some of the minerals in that area can be used to catalyze reactions.

54:31And when I say used to catalyze reactions, I'm not even totally sure I know what that means. But anyway, so hydrothermal vents are supposed to have all of these different features where you could imagine metabolism arising first. And then you're able to, through some other kind of chemistry magic, get RNA and the ball gets rolling. And for anyone who wants a really great book on it by a chemist who knows what he's talking about, check out Nick Lane's book, The Vital Question, which is all about the metabolism first. hypothesis. What do you think? Did that make any sense, Katrina? Yeah, very much so.

55:06I mean, I really like that idea of almost like a life rock hybrid scenario where the shapes of all those porous rocks around the hydrothermal vents are providing some of the structure that modern cells provide. And so they could just kind of borrow that. And, you know, I could imagine like little seals of lipids forming at the surface of a little pore. And then that's almost like a little prototype for a cell where you could get concentrated organic molecules on one side or the other. And yeah, I really love thinking about that. There's so much room for heterogeneity and diversity in that environment.

55:46Yeah. And is it going to be ironic if like down the road it turns out that this worked and like life depended on rocks? And all the time we're like, you go from a gradient of rocks to life. It's like the rocks will be like, you really didn't appreciate us. You couldn't be here without us. Yeah, they're not just this like impartial, inert bystander. They were like important. Yeah. So you're saying essentially that like you're building a little chemical engine here, something that's taking advantage of energy to do something. There's no like genome. There's no heredity. You just have like little bags of stuff that have an energy source and some kind of driving reaction.

56:26And it's being contained by these little rocks. And, you know, if we found just that on an alien planet, would you call that life? No. And I don't think that the people who study origins of life would call that life either. But I think that they would argue that this is a first step. And I should say that there are like many, many, many different hypotheses for where this stuff started. Maybe it's not hydrothermal vents. Maybe it's hot springs somewhere. And maybe it's not the white smokers. It's the black smokers because there's different kinds of hydrothermal vents. I've been talking about a very early step for one hypothesis, but there's a ton of different other ideas.

57:04And I suspect the people who study the idea that I tried to summarize would say, yeah, and then we have like a whole different set of hypotheses for what happens next. But first, we're just trying to get this one step going. And what's kind of amazing is that by creating these very specific hypotheses, they've created scenarios that they can recreate in the lab. And they do a bunch of these experiments. They're actually trying to create the origin of life in the lab or simulate the conditions under which life started in the lab. And then they go out in the field and they try to see, well, are we seeing similar things happening in the field?

57:39So this isn't just a philosophical debate, although the philosophical debate part is amazing. This is actually like there's experiments going on where, you know, year after year, we're sort of whittling away at which one of these options that we talk about are feasible and which ones aren't. So we're actually, you know, we're making progress. It's chemistry progress. So it's hard to share exactly what's happening, but people are working on it. And then there's the RNA world hypothesis. Katrina, could you go into a little bit more detail about ribozymes, which are amazing because they both store genetic information and replicate themselves, which we used to think you needed proteins for?

58:14Yeah, exactly. So, you know, in my mind, this hypothesis about the RNA world goes hand in hand with the metabolism first thinking because you're going to need energy and those building blocks of life to build up the kinds of polymers that have been so important for the basis of life. But RNA ribonucleic acids are very similar to DNA, just one of the important building blocks. The ribonucleic acid molecule itself has an additional oxygen. And so RNA molecules are inherently both more unstable, but also more creative and capable of interesting kinds of catalysis. And so when you build a chain of RNA molecules, they have the capacity to fold over on themselves and build structures that you can use to do the same kind of projects that proteins do.

59:07So the chains of RNA that build themselves up into a little macromolecule called a ribozyme, they are capable of some of the same chemistry that proteins can do. So what proteins do is they go grab a couple of substrates that they want to put together into a reaction and they hold them in a position that makes it favorable for that reaction to happen. And so ribozymes can do that too. They can build a little structure and then they can grab onto molecules in their environment and put the two substrates near each other and like let the magic happen. So that's really all they're doing. They're not like forcing the reaction.

59:44They're just making it way more likely. And so ribozymes are chains of RNA. They're still a big part of the molecular central dogma of how molecular biology works in our current modern cells. But in those days, we probably didn't have DNA or proteins yet. We only had RNA. So that's the RNA world hypothesis was that the first molecules to form were chains of RNA that can store energy just like DNA. The molecules that comprise RNA are super similar to DNA. There's just one extra hydroxyl group. But then because of that extra hydroxyl group, they have more capacity for catalysis. They're not as good for storing genetic information because they break more easily.

1:00:26That oxygen makes them less stable. Huh. I didn't know most of that, which probably means I slept through a really important lecture. But that's amazing. It's such a good story. Yeah, I love getting to tell that one to students because it's like so apparent to just look at that hydroxyl hanging off the ribose. And you're like, look at all the stuff that made happen, you know? Mm-hmm. So you're clearly team RNA in the RNA versus DNA debate. I mean, I would not give up my DNA, man. DNA is like critical. Yeah. But I mean. But you did have a sparkle in your eye when you were talking about the RNA.

1:01:01Yeah, I think it's fun to imagine that world before we had the DNA or the protein. And I think it's cool that we understand why. But when it comes down to it, you know, I trust my DNA. Okay, so, you know, this is a Daniel and Kelly's Extraordinary Universe episode. So we talked a lot about what we don't know and sort of the limits of our knowledge. But I am still super excited about how far we've gotten, like how many different conditions we've considered in the lab and in the field and how we've seen the building blocks of life showing up in these different sorts of environments. I mean, there have been papers that I read where like something had to happen in the ocean and then it got thrown up on top of the land and then it dried and the drying was important for a step and then it gets washed back into the ocean and that's important for the next step.

1:01:49And they've simulated all of this stuff in the lab. Totally amazing. But of course, the more steps that are involved, the more complicated it probably is for life to arise. And one of the questions that really stuck with me while I was doing this reading was, you know, in situation after situation, it seems like we're figuring out how to come up with the building blocks of life, which makes it surprising to me that we don't see life popping up more often. And I guess the point is that, you know, if you're talking about it, you know, first it happens in the ocean, then it gets washed up on a volcano bank, and then it has to, you know, fall back in.

1:02:23There's a lot of steps, and it's super complicated. But it's kind of amazing that this thing may have only happened and then really taken off once. And now here we all are. And I don't really know where I'm going with this, but I had a lot of fun researching this, even though there's a lot of chemistry. And I'm really fascinated in this question of, like, how often did it happen? Like, it's true that there's a lot of evidence that all life on Earth has a single common ancestor, but I'm not sure that rules out an independent strain of life developing and then getting squashed by or outcompeted, right?

1:02:57Yeah, and that was a point that I saw made in these articles over and over again, is that what we see is the one instance where life sort of really got going and then stuck around and diversified. But then to me, there's this other question of, are the conditions so different now that it just could never happen again? Like, why does life not start fresh now? And maybe it is something about the Earth being so different, our conditions being so different now that you just couldn't get it happening again. But it makes me feel pretty lucky to be here. I think, yeah, I also thought about that a lot.

1:03:30I think that the oxygen in the atmosphere, I'm sure you read all about this, is a major reason that it's harder for these delicate initial life forms that were probably emerging three and a half billion years ago. You know, those guys could not stand the sight of a molecule of oxygen. They would immediately croak. So I think our current conditions make that harder. But, you know, it could be that down in the deep sea thermal vents, those conditions are still ripe for new origins. And so it could be that some of those initial steps are happening. They might not make it that far these days because there's so much competition.

1:04:05But I would not be surprised if there are places where those conditions still exist on Earth. And check out our interview with Dr. Andrew David Thaler, where he's talking about what's happening at hydrothermal vents and why we might want to be careful about mining them. Because this could be, these vents could be a really great place for us to be studying the origins of life and trying to see if, you know, maybe it could ever happen again. But if we mine the heck out of them and destroy them, we'd lose the ability to study them. Well, we don't know, but I suspect the origins of life are hot and nasty and not very boring.

1:04:43Thanks, everybody, for listening. Please go and do us a favor and rate the show on whatever podcast app you're using. It really helps people find us. Daniel and Kelly's Extraordinary Universe is edited by the amazing Matt Kesselman. He really is a wizard. You can also find us online on Blue Sky, Instagram, and XDNKUniverse. Come engage with us. You can email us at questions at danielandkelly.org. We really do want to hear from you. And you can find our website, www.danielandkelly.org, where you'll also find an invitation to join our Discord, where everybody comes and talks about the amazing universe.

1:05:23And we also have the most amazing moderators. This is an iHeart Podcast. Thanks for joining us.

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