Becoming Martian with Dr. Scott Solomon

Disclaimer: Unedited AI Transcript

Larry Barsh (0:05): You might know this show by another name. Specifically for seniors was where it all started. A place built on the idea that people who've lived have a clarity that's hard to fake. That's still true. That's still us.

Larry Barsh (0:26): But the conversation got bigger. The audience got whiner, and the cynicism turns out it's pretty universal. So we evolved. Same sharp eye, same refusal to nod along, just a bigger table. Welcome to the Enlightened Cynic.

Larry Barsh (0:52): You're in the right place. Let's get into it. Welcome to the Enlightened Cynic. I'm your host, Doctor. Larry Barsh.

Larry Barsh (1:02): What if the most profound consequence of sending humans to the moon and Mars isn't the science, the geopolitics, or the engineering, but what it does to us, to our bodies, our DNA, our species. That question is exactly where our guest lives. Doctor. Scott Solomon is a biologist and teaching professor at Rice University, a research associate at the Smithsonian Institute, and one of the most electrifying science communicators out there. His work has appeared in The Washington Post, National Geographic, and Wired.

Larry Barsh (1:48): He's been on NPR, the BBC, and ABC News, and he hosts his own podcast, Wild World with Scott Solomon. His twenty seventeen book, Future Humans, tackled where evolution is taking us here on Earth. His new book goes much further, literally, How Living in Space Will Change Our Bodies and Minds landed from MIT Press in February, just weeks before Artemis II sent humans back toward the moon for the first time in more than fifty years. Scott, I'm so excited to talk with you. Welcome.

Scott Solomon(2:35): Thank you so much, Larry. It's, such a pleasure to be here.

Larry Barsh (2:38): Scott, your bio mentions that you teach evolutionary biology. I was a biology major in college many, many, many years ago. That subject wasn't available. What's your work in the field of evolutionary biology here on Earth?

Scott Solomon (2:59): Well, my training as an evolutionary biologist was actually very focused on ants. So it's a long stretch perhaps to go from studying ants down in the rainforests of Central America, as I've spent a lot of time doing to to thinking about humans on Mars. But I actually was fascinated by ants initially in part because they remind us of ourselves, right? I mean, ants live in actually pretty complex societies, and they do a lot of things that we used to think only humans do. Like, you know, they have a division of labor within their colonies that allows them to, you know, be pretty sophisticated in things like how they construct their nests.

Scott Solomon (3:45): And they do that without any kind of, you know, blueprints. There's no, you know, general contractor sort of telling them where to dig. And, you know, they're really kind of like amazing in how much they can accomplish in such simple ways. They even have agriculture. The ants that I was studying are growing fungi in their underground nests as a form of agriculture.

Scott Solomon (4:08): So, yeah, so that was my initial interest, not just understanding how they behave, but reconstructing how they came to be that sophisticated. So trying to work out the evolutionary history of the ants and the other organisms like those fungi that they're growing, that they've come to be so dependent on.

Larry Barsh (4:29): Long stretch to Mars.

Scott Solomon (4:32): It is. Although, you know, one of the things I always point out is if we're really gonna live on Mars, we probably have to live underground because as and I'm sure we'll get into this, but there's a lot of radiation on the surface of Mars. You really want to be protected from that. Going underground is one of the best ways to do that. So it may end up being that if we're living on Mars, we're living much like ants.

Scott Solomon (4:54): We might have to have these complex networks of, you know, tunnels and underground, you know, habitats, basically a giant ant colony underground on Mars. So, hey, you know, I could always connect the dots.

Larry Barsh (5:10): Now, along those lines, the other night at dinner with a friend, he asked why spend money on spaceflight and a Mars base? Wouldn't that money be better spent on Earth? What kind of research could you get that just can't be done here?

Scott Solomon (5:31): Think it's a really it's a question I hear often. I think it's actually a really important question. And I think, first of all, we have to be clear that if the only benefit that comes from this kind of work, research, effort is what happens out in space, then it might not be the best use. But I think what we see when we look back through the history of space exploration and human spaceflight is that when we go to space, when we figure out the technologies and the, you know, innovations to be able to go to space, it ends up benefiting us here on Earth in all sorts of ways. And there's all these figures that you can find on like, what is the return on investment, you know, for every dollar spent in space?

Scott Solomon (6:15): There's however many times that, you know, amount, you know, that benefits people here on Earth. You know, so there's that notion that like, yes, there will be benefits to us here on Earth. But I actually, you know, I would also think about it from the perspective of, you know, if we don't go, what is the cost? And, you know, everybody has different motivations for why they think, you know, human space exploration, and in particular space settlement, which is what I've really been focusing on, like living on other worlds. You know, why would we want to do that?

Scott Solomon (6:54): Some people think that this is just a great adventure. Others see it as, you know, purely a scientific endeavor. Others see, you know, profits to be made. But the motivation that really kind of resonates the most with me and by the way, these are not like, you know, don't just have to pick one. Like, could be more than one of the above.

Scott Solomon (7:14): But the thing that really, I think, strikes me as ultimately something that we have to take seriously is that if we don't do that, if always remain here on Earth, then we are more vulnerable as a species, right? Humanity has, you know, all its eggs in one planetary basket, so to speak. And that means that if there's ever a disaster here on Earth that, you know, it could spell doom, right? And so that's one of the, to me, most compelling motivations for going is the idea that we increase our chances of long term survival by becoming multiplanetary. Now, it doesn't mean we have to do it tomorrow, right?

Scott Solomon (7:56): So we could talk about what's the timeline by which we should be doing this. But, you know, that to me is the thing that I think justifies a lot of the investment in, you know, a future beyond Earth, because ultimately, life as we know it might might depend on it.

Larry (8:14): Survival of the species as a whole.

Scott Solomon (8:16): That's right. And and you could even make the argument, as some have, that, you know, it's not even just humans, it's Earth life. It's all life that we know of, that we have not yet, you know, found life beyond Earth. It may exist out there. I, for one, think it's likely that it does, but, you know, if it's true that that Earth life is unique and that there isn't anything like it elsewhere, and we had the opportunity to not only go ourselves, but to bring other forms of Earth life with us, which by the way, we would do whether we intend to or not.

Scott Solomon (8:50): But, you know, even if it's just the bacteria on our skin, like we're bringing stuff with us. Plus we have to eat something, so we're gonna be bringing plants and other things to eat. But, you know, we are the only species currently that is capable of extending Earth life beyond Earth. And so some people have argued that we actually have a moral, you know, obligation to try to ensure the long term survival, not only of human life, but of life with a capital l, Earth Life, life life as we know it.

Larry Barsh (9:23): In case there's no other life anywhere in the universe.

Scott Solomon (9:28): In case there's no other life and in case some some disaster would befall, and even if, you know, befall us here on Earth. But even if there is life elsewhere, it's possible that that life is fundamentally different. It may have come about separately through an independent origin of life process, and it might be very, very different from Earth life. So, you know, life on Earth might be unique, not just in the sense that it's the only life, but it might be the only version of life that is is, you know, what we are familiar with.

Larry Barsh (10:02): You had a piece in the Washington Post April, the ripple effects of NASA's Artemis mission. The moon and Mars could create a new human species, you argue. What did you mean by this?

Scott Solomon (10:25): Yeah. So basically, the point that I tried to make in that article, which is really sort of like the main thesis also of my new book, is that we should expect that if humans leave Earth to live elsewhere, as we were just talking about, that that will lead to evolutionary changes. Basically everything that we know about how evolution works tells us that any time you take a small number of individuals and you put them into a new environment, and especially if that new environment is someplace very isolated, very far away, and if the environment there is is quite different from where they came from, that is a recipe for evolutionary change. And we understand that process quite well from studying things like islands here on Earth. You know, think about the Galapagos Islands and how they inspired Charles Darwin and the reason why biologists like me continue to return to the Galapagos Islands and other islands to study and understand evolution.

Scott Solomon (11:22): So my argument is that if we go and if we truly live out there on Mars anywhere, really, that is an isolated place out far away from Earth with a different environment from Earth, that we should expect that future generations living there will become different from from those that first, you know, arrive there, that first establish that population, and that eventually they will likely evolve into new human species. So it's possible that if we don't just, you know, go to Mars, if we keep going, as some would like us to do, that you could eventually end up with kind of this, you know, diaspora of human species kind of spread out among the cosmos. It's very much sounds like a science fiction scenario, but it really follows from what we understand about how evolution works.

Larry Barsh (12:16): Yeah. I'd like to talk about that a little bit more later on. Sure. Your new book, Becoming Martian, follows future humans, your first book, which looked at where evolution is taking us right here on Earth. How did that book lead to this book?

Larry Barsh (12:38): Was evolutionary.

Scott Solomon (12:41): It was a natural evolution. That's right. I mean, kind of was. So with future humans, yeah, you're right. Future humans really looks at like, are we still evolving today?

Scott Solomon (12:50): And it was actually something that came out of classroom teaching at Rice University where I teach students about evolution. One year I asked them if they thought humans were still evolving. And we had this great discussion in class about, you know, well, what do we actually know about this? Are humans evolving? And how is like modern life affecting our evolution?

Scott Solomon (13:10): And I was emphasizing that evolution is not only natural selection, that is one mechanism of evolution, but that there's other ways in which we evolve. And, you know, things like the movement of individuals from one place to the next. We call that gene flow, and it's a mechanism of evolution. And so that's still happening. And in fact, that mechanism, the movement of people around, you know, around the world, that's actually happening at a higher rate today than it has ever happened in our history.

Scott Solomon (13:39): As you know, human migration is made so much easier because of our transportation technology. So yeah, so that book really kind of ended with just kind of glancing into the future. I mean, most of the book is about evolution happening today in the twenty first century as we, you know, are living today. But I wanted to end that book by looking into how we might evolve in the future. So the last chapter of Future Humans considers different scenarios for what our long term fate as a species might be.

Scott Solomon (14:14): So I looked at, you know, extinction. That's a possibility. I looked at the the possibility that we just kind of stay as we are indefinitely, which I actually think is very unlikely, in part because no species has ever accomplished it in the history of life on Earth. And then lastly, I looked at, well, could we evolve into a new human species? And I pointed out in that book that, you know, what we understand about how that process happens is that it's most sort of like well, it's basically the easiest way to get new species is to physically separate individuals from one species so that they can no longer come together and have babies.

Scott Solomon (14:52): And so that is a recipe for speciation. That's why islands are such great hotspots for evolution. And as I point out, well, we're sort of doing the opposite today. We don't really have human populations that are completely isolated in the twenty first century from other human populations. And so it would take something different for that to happen in the future.

Scott Solomon (15:12): Something like if some humans left Earth and went and lived somewhere else on another planet, like Mars. And I even considered that scenario in Future Humans. And I pointed out that, yeah, I mean, that probably would be a recipe for, you know, taking a very different evolutionary path. But at that time that I wrote that, that book came out in 2016, so ten years ago now. And it didn't really seem like a very likely scenario, at least not for any time soon.

Scott Solomon (15:41): But then soon after that book came out and I was going around and giving talks about it and doing interviews, And soon it became clear to me that there are actually people that are quite seriously working on that. And, you know, there were things like, you know, SpaceX started having some pretty big advances in their rockets that are designed to take people to Mars and to stay. And, you know, NASA started announcing their plans for kind of, you know, having a more permanent human presence in space. So all of that led me to just decide, you know what? That little kind of thread that I I began in the end of future humans, I think I wanna follow that and explore it in more detail.

Scott Solomon (16:27): And that's that's what Becoming Martian is.

Larry Barsh (16:30): Who were these books written for? Scientists or the public or what?

Scott Solomon (16:35): No, I really wanted to make these books accessible to the general public. So, you know, something that I really became passionate about as a graduate student really was the idea of, you know, sharing science with everyone, right? Like, you know, as a scientist, I do write, you know, research articles that go into, you know, journals that a handful of experts are going to read if you're, you know, if you're lucky. And that's important. That's how science proceeds.

Scott Solomon (17:05): We need to have that system. But at the same time, you know, there's just so many people that are never going to read those articles. And some of them will get picked up by, you know, science journalists or the news kind of mainstream media, but the vast majority never do. And so I decided as a kind of a young scientist that I really wanted to make an effort to share science more broadly. And it's really become a big part of what I try to do now.

Scott Solomon (17:33): We're actually at launch, I'm helping excuse me, at Rice, I'm helping to launch a new center for science communication and public engagement, where we're trying to help to, you know, train students to be able to do that kind of science communication for the public, because I think it really is important. I think we need that in society, and historically, it hasn't been a part of the the training and education for most scientists. So so, yeah, these books are really meant to be, accessible, interesting, engaging, not just for other scientists who who I'm told enjoyed them as well, but really for for anyone who's interested.

Larry Barsh (18:13): So let's get into the science a little bit.

Scott Solomon (18:16): Alright.

Larry Barsh (18:17): What's happening at the genetic and epigenetic level that isn't making the headlines? How does spaceflight alter the human body? And let's start basically by defining the difference between genetic epigenetic for the listeners.

Scott Solomon (18:40): Sure, yeah, yeah. So basically, when we're talking about genetics, you know, genetic changes, we're talking about changes to your DNA, and specifically to the sequence of DNA. And so, you know, with DNA, this is the code for how to make an organism, right? So it's the alphabet basically, which consists of As, Ts, Cs, and Gs. Those are the four letters of the DNA alphabet.

Scott Solomon (19:05): And with the order of those letters basically is an instruction code that tells the body, make this protein. And that is what then goes on and does all the the the work of the body, basically, allows us to live, build our bodies, and function the way we are intended to. So if you change that sequence, it can result in a change in the structure or function of the body. We are generally given our DNA code by our parents, right? We have our, you know, half of our mother's and half of our father's DNA, and they make a unique combination that makes us.

Scott Solomon (19:45): So, you know, when we think about sort of like, you know, the genetic changes that could take place in space, what we're talking about is something that doesn't normally happen to us here on Earth. We generally think that, like, the DNA that you're born with is pretty much going to be the DNA you have for the rest of your life, except that there are some ways that it can change. And if you have a mutation, which is like a change in the sequence of your DNA, right, that's something that can be problematic because it can interfere with the function of your body. And specifically, we think about like carcinogens are things that cause cancer. Well, what are they doing?

Scott Solomon (20:28): Well, they're specifically changing the sequence of your DNA in a way that causes that cell to turn into a tumor, which of course can be problematic. So that's why mutations are things that we tend to be concerned about because we associate them with cancer. But they don't have to be, right? So mutations can also be just sort of like, you know, not really any big deal. Just sort of depends on the specifics of the mutation.

Scott Solomon (20:54): So one of the things that's been fascinating is that what we've learned is that going to space can cause mutations. It can change the sequence of your DNA. And the first time that we really sort of definitively showed this was with the NASA Twin Study. This was when astronaut Scott Kelly, who spent a year on the International Space Station, agreed to have all sorts of tests done on him before, during, and after his year in space, including taking blood draws so that scientists could sort of monitor these types of things. And then, you know, part of what made it fascinating and why it's called the twin study is Scott Kelly has an identical twin brother, Mark Kelly, who now senator from Arizona, but at the time he was also an astronaut, except Mark was going be on Earth.

Scott Solomon (21:44): So they decided they'd do all the same things with Mark on Earth that they were doing with Scott in space. So doing all the same blood draws and everything. So what this was able to do was show that Scott Kelly's DNA changed during his year in space. It was different from how it was before his flight, and it was different from the DNA of his identical twin brother, Mark, who otherwise has the same DNA as Scott. Now, why does it change?

Scott Solomon (22:12): Well, this is because being in space, you are being exposed to a lot more radiation than we are here on the surface of the earth. So, you know, there's all different forms of of radiation, including, you know, like X rays when we go to the doctor or the dentist and we put the lead apron on when we're getting the x rays, that's to protect our bodies from the potentially harmful effects of radiation because, again, it can cause mutations which could lead to cancer. And so, you know, being up in space, you are in an environment where you're being exposed to much more radiation. And the reason for that is that the atmosphere of the planet is actually blocking a lot of that radiation that exists in space. This is radiation from the sun.

Scott Solomon (22:59): It's radiation from, from other galaxies, what we call galactic cosmic rays. And so being up in space for a year literally changed the sequence of Scott Kelly's DNA. But you asked about genetics and epigenetics. So so far I've been talking about genetics. Epigenetics is something that we've only started to, understand relatively recently, in the last few decades.

Scott Solomon (23:27): And the idea with epigenetics is that it's possible for the body to change the way genes and DNA function, not by not just by changing the sequence of As, Ts, Cs, and Gs, but by basically changing when those, those DNA sequences are actively doing their work, actively being converted into the proteins that do all of the work of the body. That's you know, when we talk about a gene, a gene is something that is performing a function. And not all the genes are always doing that. You can turn them on and you can turn them off. And one of the ways you can do that is, for example, by adding other chemicals to the DNA that basically, like, shuts them off or causes them to be to be activated, turned on.

Scott Solomon (24:13): So those types of changes, like adding these extra chemicals that turns genes on and off, that's something that we call epigenetics. And we now also know that it can be heritable. That's one of the key things, is that changes that happen to us as adults, if they are, you know, turning our genes on and off, that is actually, in some instances, something that could be passed on to your children. And so, you know, that's partly why people are sort of fascinated by them. That's partly why we want to like understand them better.

Scott Solomon (24:47): And we did see in that NASA Twin study that Scott Kelly's DNA had epigenetic changes that happened to him in space. This is probably not due to radiation, or at least not only due to radiation, because we know that any kind of stressful situation that you experience can cause your body to turn certain genes on and off through these kinds of epigenetic changes. So it's unclear so far, like, what specifically about being in space caused these epigenetic changes to Scott Kelly, but we did see them. But here's the biggest difference, and then I'll stop because this has been a long answer. But okay.

Scott Solomon (25:28): So the genetic changes, the changes to the sequence of DNA that Scott Kelly experienced, those are permanent. That's not going to ever go back to the way it was when he comes back to Earth. The epigenetic changes can be reversed. So when he comes back to Earth, we do see some of those epigenetic changes being, you know, being sort of undone. So I think that's an important distinction to make as well between genetic and epigenetic changes.

Larry Barsh (26:00): Do we know if humans can successfully reproduce in space?

Scott Solomon (26:07): Ah, yes. This is a very important example of something that we really don't know very well. So, you know, we have learned a lot about how the human body is affected by space. So my long answer about genetics and epigenetics is only one tiny slice of that. What we have not really done much research on is reproduction.

Scott Solomon (26:26): And this is something that when I was researching the book, I was really kind of struck by, like, how much of a blind spot this seems to be in our understanding of, you know, human biology in space. And it's not that we know nothing, but we've done very few experiments that are specifically looking at aspects of reproduction. So the short answer I'll try to keep this one much shorter the short answer is we really don't know. There are some of these experiments that have suggested that reproduction might not be too severely affected, but there are enough experiments that basically have shown issues arising that give us pause. But the you know, part of the problem is so few experiments have been done that there aren't enough for us to be confident about those conclusions.

Scott Solomon (27:18): So we really need a lot more research on that topic.

Larry Barsh (27:21): And even after that, Mars has about a third the gravity of here on Earth. What is the birth process like?

Scott Solomon (27:32): Yeah. So if we're really serious about living on Mars or or, you know, anywhere else beyond Earth, we we need to not only understand, like, how does, yep, you know, fertilization, embryo development, pregnancy, how does all of that get affected by the conditions there, which include higher radiation and lower gravity, right? But we also need to understand like, yeah, how is childbirth affected by it? And then child development as well, like what happens to a kid that's born there? So, you know, the short answer, again, is that we don't know because nobody has done this.

Scott Solomon (28:08): There have been some experiments on rats conducted in microgravity, in zero G basically, up on the International Space Station and its, you know, precursors, the the space shuttle and some of the the earlier, you know, space stations. But but but very little. And so so the short answer is we don't know. I I argue in Becoming Martian that we should really be concerned about this because specifically about childbirth, because we know that childbirth is risky. It's risky here on Earth, right?

Scott Solomon (28:45): I mean, women die in childbirth, unfortunately, you know, all the time. This is not, you know, this is not like uncommon even here on earth. And so, if we're looking now at somebody who has been in a lower gravity environment for some amount of time, maybe their whole life, one of the things that we know happens to people in a lower gravity environment is their bones start to become brittle. They become weaker. Basically, without gravity pushing down on your body, your muscles get weaker, and because bone responds to muscle, then your bones weaken as well.

Scott Solomon (29:19): And some of the bones that have the most weakening are the hip and the pelvis. These are, you know, some of the bones that help to support our weight. And so it kind of makes sense that, you know, if your weight is lower, that they're going to be most severely impacted. But at the same time, are bones that if they fracture during childbirth, could be some of the most devastating in terms of the risk to mothers and in turn to their children. So I think, you know, the possibility of women experiencing complications in childbirth in a lower gravity environment is something we have to really take seriously and something that we just don't know enough about.

Larry Barsh (30:06): You draw a parallel between what people who settled on Polynesia Islands are like, and those that might settle on Mars. Could you discuss that just for a moment?

Scott Solomon (30:24): Yeah, absolutely. So I mentioned earlier that, you know, we can think of of the planets basically as like islands, right? You know, you have an isolated landmass that is sort of surrounded by a long stretch of inhospitable terrain, right? Mean, that's basically what an island is. And so I try to make the point in the book that we can think about, you know, what do we understand about evolution on islands and apply that to what could happen to our own evolution on planets.

Scott Solomon (30:57): And as we were talking about earlier, I, you know, I argue that we should expect evolutionary change and the evolution of new species on those islands in the, you know, in the solar system. But then you could turn around and say, Well, wait a second. You know, humans once lived on all of these different islands scattered across the planet, right? The very first humans that arrived in some of these islands were isolated for long stretches of time. Why didn't they evolve into new human species?

Scott Solomon (31:34): And, you know, the Pacific in particular is probably the best example that we have because, yeah, the, you know, the Polynesian people, the ancient Polynesians, were really the world's greatest navigators. I mean, they found just about every island that exists in the Pacific and were able to, you know, establish settlements there. And they set out not knowing where they were going and fighting these places and then bringing all the things they needed with them in order to establish a settlement. And so, you know, I think it is a really interesting parallel, and other people have made this comparison in the past as well. So why did they then not evolve into new human species?

Scott Solomon (32:22): Well, I think there's two important factors to consider. One is the amount of time that they were isolated. And if you look at what we know about the timing of the settlement of the Pacific now based on a combination of archaeology genetics and even linguistics. There's a lot of different data that has kind of been combined to reconstruct the timing of this. And it turns out that it wasn't really all that much time that passed a few hundred years at most between the settlement of some of the most remote Pacific Islands, like say, Easter Island, and when the first Europeans arrived, you know, the early explorers like Captain Cook who explored this region.

Scott Solomon (33:08): And that's relevant because soon after the first Europeans arrived, more Europeans arrived and they started moving people around from island to island. So that isolation period kind of ended. So a few hundred years in human generations is not actually that many generations. So as an evolutionary biologist, we tend to think in terms of generations because evolution is defined as change over generations. So it's not really the number of years that matters, it's the number of generations.

Scott Solomon (33:40): So a few hundred years is only, you know, a few dozen human generations at most. So that's actually not that many generations. But there's another factor. The other factor is how isolated were they? I mean, you look at a map of the Pacific and you look at some of these islands and, you know, you have to imagine that anybody living there before they had kind of modern technology couldn't have been, you know, in regular contact with anybody else.

Scott Solomon (34:08): But actually, have evidence now that seems to suggest that they were. So there's, in particular, archaeological evidence and some genetic evidence that suggests that they had trade networks that existed that, you know, allowed at least some individuals to actually move back and forth from one island to another. In many cases, cases, there were a few islands like Easter Island that do seem to have been quite isolated, but most of them actually did engage in trade of goods with other islands, even those quite far away. And as we know from history, anytime people exchange goods, they have often exchanged genes as well. So, you know, they weren't even that genetically isolated for all that much time.

Scott Solomon (34:56): So that, you know, the parallel here to space is to say that, look, if we're living on Mars at some point in the future, it will matter how often we are sending spaceships, rockets back and forth between Earth and Mars. And, you know, if we're exchanging goods, are we also exchanging genes? The more that we do that, the more that we exchange genes in particular, the less likely it will be that people living on different planets evolve to become different. So I've said that that's what we should expect. We should expect evolutionary change.

Scott Solomon (35:30): But it also matters how much contact there is between people living on different worlds. The more contact, the less separation and, evolutionary, change we we should expect.

Larry Barsh (35:44): Does that affect the, choice of people who are sent to Mars? It's a small population.

Scott Solomon (35:52): The choice of people matters a lot. And this is another lesson from from evolutionary biology, which is, you know, the the founders of a new population in a new place have a huge effect on that population moving forward, because whatever traits, whatever genes they happen to have are going to be what is kind of present in that population. And the amount of genetic diversity in that founding population is incredibly important for the future success of that population. The more genetic diversity, basically, the more resilient, the more, you know, adaptable that population is going to be. Genetic diversity is incredibly important for, for evolution.

Scott Solomon (36:35): It's it's the raw material that natural selection uses to allow a species to adapt to its conditions. And as the conditions are changing, you need that variation for natural selection to work. So it's yeah. Sorry. No.

Scott Solomon (36:51): Was just gonna say it really matters who you send, and you really wanna send the most diverse founding population possible if you're trying to set those folks up for for future success.

Unknown Speaker (37:03): So it's not only their abilities, their work on on a new colonization. Yeah. It's also their biology that has.

Scott Solomon (37:19): That's right. And this is where, you know, we're gonna have to think differently from how we've thought about, you know, selecting astronauts in the past. If you think about, you know, the history of how we've chosen who gets to go to space, going back to the early days of human spaceflight, this idea of, you know, the right stuff, as the author Tom Wolfe put it. You know, it's not just about who's the best pilot or has the best, you know, skills at, you know, all this incredible variety of things that astronauts have to do. Yes, that's important, of course.

Scott Solomon (37:52): Also being able to get along well with the crew, that's a really, really important skill that, you know, NASA and other space agencies really, really pay a lot of attention to, rightly so. It'll be that and also their biology. Because if you ignore their biology and for example, get a very genetically similar group of very highly skilled individuals, they might do great initially, but future generations will suffer if there isn't genetic diversity present because they will not be able to adapt to those conditions as effectively.

Larry Barsh (38:29): So how long would it take? How many generations would it take to develop at least the start of a new species?

Scott Solomon (38:41): Yeah. So let's talk about the timeframe. So I have to admit as an evolutionary biologist, I'm guilty of thinking on much longer timeframes than most people are. So when I'm like, Oh, it won't take that long, you know, like just a few hundred years. And people are usually like, What do you mean?

Scott Solomon (38:57): That's a long time. Like, Well, yeah, I guess in a human kind of like lifespan that is a long time. But, you know, by evolutionary standards, that's a blink of an eye. I do think it will happen faster on Mars in space than it would here on Earth. That's what I'll say, because of a number of factors.

Scott Solomon (39:16): One, anytime the environment is very different, it causes evolution to go more quickly. Basically, natural selection is stronger if any individual that happens to be a little bit better at surviving in this new environment, you know, like any advantage they have becomes a really big advantage. And so those traits tend to spread faster. And of course, the environment on Mars is dramatically different from any environment on Earth. Even the most harsh extreme places on Earth like Antarctica are cozy compared to what Mars is like.

Scott Solomon (39:49): Let's let's be clear about that. The other thing, though, is how much genetic variation do you have? If we are wise about this and we start off with a genetically diverse founding population that would be, you know, ideal that would help them to evolve more quickly. But at the same time, you will also be acquiring new mutations through radiation exposure, right? We said before, like, being exposed to radiation causes mutations.

Scott Solomon (40:21): Those mutations can be harmful, but if they're not, every now and then you get a mutation that gives you something useful, something beneficial, something helpful. And because Mars doesn't have a thick atmosphere like Earth does, its atmosphere is less than 1% of Earth's atmosphere, so that's not blocking a lot of the radiation. And then the other thing that Earth benefits from when it comes to radiation is we have a magnetic field that surrounds our planet called the magnetosphere, and that is is blocking, trapping a lot of radiation from space as well. So we have kind of two things working in our favor on Earth. Mars has no magnetosphere.

Scott Solomon (41:01): So the space radiation is hitting the surface of Mars at nearly full strength. So anybody on Mars that's spending any amount of time on the surface is being exposed to a lot of radiation. So that's why I think we'll have to go and live like ants underground. But I also think people are not gonna be satisfied to just stay underground all the time. I know I wouldn't be.

Scott Solomon (41:22): So I don't want to go all the way to Mars just to live in a cave. So if people are spending any amount of time on the surface, they are going to be exposed to radiation. And that is the raw material, that, you know, mutation, that genetic variation is that raw material for natural selection. So if you've got both increased amount of genetic variation and very strong natural selection, that's a recipe for rapid evolutionary change. So I've argued that in as few as, you know, 10 generations, we might see pretty dramatic evolutionary changes in human populations living on Mars.

Scott Solomon (42:01): That is still, you know, we're still talking maybe, you know, two fifty, three hundred years. But again, from my time perspective as an evolutionary biologist, that's pretty quick. So yeah, you know, these things are hard to know with any certainty, but I think applying what we know about how evolution works on Earth and applying what we know about the environment on Mars and how space affects the human body, there are some things that we can say. And and part of what we can say is that if we go there, we will change.

Larry Barsh (42:37): What's the likelihood that these people who are born and grow up on Mars could ever get back to Earth?

Scott Solomon (42:46): This is something that I think we need to really take seriously because, you know, some of the things we've already talked about, like the risks of childbirth, you know, just the harsh environment of being there and the fact that future generations are likely to adapt and to be different. I think that there is a really, you know, a real possibility that people on Mars would have a hard time coming back to Earth. If you think about future generations having adapted to the conditions on Mars, and that includes adapting to the lower gravity, about one third that of Earth. If you're coming from a place that has if you're coming from Mars that has one third gravity and you come to Earth, all of sudden on Earth, you will weigh three times what you weighed back on Mars. So just imagine suddenly weighing three times what you weigh.

Scott Solomon (43:35): And now imagine doing that with weakened bones. Right? I mean, that could be a really dangerous type of situation. And it's not just the bones, it's also the muscles, it's also your heart, you know? So, you know, I think this is actually something that it could be harder than what we normally think of.

Scott Solomon (43:56): And the other thing that I think has not necessarily been given enough consideration is the immune system, right? Our immune system is trained to fight against the microorganisms, the infectious diseases that we encounter in our lives. And as we are exposed to any kind of bacteria or viruses, we develop, you know, resistance to them. We build antibodies. Like this is why, you know, you don't tend to get the same illness more than once, right?

Scott Solomon (44:27): And so it's why vaccines work. So here's the thing. On Mars, the only microorganisms, the only infectious diseases that we'll be exposed to are gonna be the ones that we bring with us. And we will bring some with us, you know, hopefully not many. I think we can easily avoid some infectious diseases like malaria, if we can prevent mosquitoes from boarding our rocket ships, then we can, you know, wipe those out.

Scott Solomon (44:53): But other things will inevitably come with us because we all carry bacteria and viruses in and on our body. Some of those might evolve to be new infectious diseases. But whatever they are, the things that are on Mars are going to be a tiny subset of all of the infectious diseases and all the microbes here on Earth. So a child born on Mars and growing up there who comes back to Earth will all of a sudden be exposed to all of these different infectious diseases, including, you know, microbes that aren't normally harmful to us here on Earth, but could be harmful to somebody who had never had any exposure to them. So I actually think the infectious diseases and the immune system could be one of the biggest things that limits our ability to easily move between planets and something that I I I just think hasn't really been given enough consideration in the past.

Larry Barsh(45:52): A sort of War of the Worlds scenario.

Scott Solomon (45:55): That's exactly right. I mean, H. G. Wells thought about this way back in 1898 when he wrote war of the worlds, and that was the one thing that stopped the Martians with their superior technology from invading Earth, right, was they had no defenses against our bacteria. So, yeah, he was ahead of his time in so many ways.

Larry Barsh (46:14): Is there anything else we missed? I'm sure there is. But anything else you'd like to bring up?

Scott Solomon (46:22): Well, I guess one thing that is another, you know, thing that I write about in the book and I think is worth thinking about is we do have some technologies that we could use now to kind of help us to adapt to the conditions on Mars or elsewhere in space. And I'm talking about, you know, genetic technologies, the ability to edit our DNA with things like CRISPR. This is a, you know, a tool for going in and making very precise, deliberate edits to our DNA. We know how to do that. It's being done in some cases.

Scott Solomon (46:56): It's being used for some, you know, clinical treatments for diseases like, you know, sickle cell disease. So in theory, we could do that and basically edit people's DNA to make them better adapted to the conditions on Mars. And that would really jumpstart the process of being adapted to the conditions there. But of course, it comes with a lot of, you know, ethical concerns, a lot of kind of moral dilemmas. For one thing, there's the possibility that it leads to unintended consequences, right?

Scott Solomon (47:27): That's a real concern. If you're editing people's DNA in a way that's heritable, like you make an edit to one person's DNA and then all of their children, grandchildren, and so on inherit that change, that means we are taking evolution into our own hands. There's a lot of concerns about that. And then there's also the possibility that if we edit someone to be well adapted to the Martian environment, it could be at the expense of being well adapted to Earth. So we might have to make choices about, you know, how important is it to be able to really survive and thrive on another world versus having the flexibility to go between planets.

Scott Solomon (48:10): And that's something that I think, you know, we need more than just biologists to be thinking about these questions. These really are ethical questions that I think are at least as important as the science.

Larry Barsh (48:23): Okay. One sort of silly thing that I want you to comment on. Is there a president on an alien planet who may at this moment be warning that humanoids from outer space are going to be visiting their planet.

Scott Solomon (48:45): Yeah. Well, you know, I mean, you say it's a silly thing, but actually it brings up like this idea that, you know, who who are we to go and and, you know, take over another world, right? Like, it's one thing if we go to a place that we know has no life on it. And so far, we don't know of any life on Mars. There's evidence that there may have once been, microbial life on Mars.

Scott Solomon (49:13): We don't know that for sure, but it's looking increasingly like that may may be the case. We have not yet found any any evidence for for current life on Mars. But if we did find that there was living organisms on Mars today, I think it would really change the whole conversation, because then you have to ask, like, is it, again, is it ethical for us to go and interfere with, you know, life on another world, right? So we talked to was talking about like, why it might be beneficial to Earth and Earth life and humanity, But what about if you turn it around from the perspective of those that are already there, right? Is it, you know, does our benefiting by increasing our odds of survival, does that outweigh the potential cost of, you know, the impact that we would be having on life elsewhere?

Scott Solomon (50:12): Now, you know, people would also probably make a distinction between microbial life versus intelligent life. If there is intelligent life there, then it really gets to be complicated, right? So, you know, if we ever get to the point where we do discover that there is life elsewhere, boy, I hope that happens. That would just be incredibly exciting. Slightly terrifying too, but, you know, but also quite exciting.

Scott Solomon (50:37): But it really changes the nature of conversation. And I'll just, you know, point out that actually there are international treaties in place that basically stipulate that we are not to interfere with the biology of other worlds. Basically, there's this notion of planetary protection. So NASA, for example, has people employed as planetary protection agents whose job it is to make sure that we are not accidentally contaminating other planets with Earth life. And at the same time, their job also involves trying to make sure that if there is any life out there, that we're not accidentally bringing it back here to Earth.

Scott Solomon (51:24): This is why, like, the Apollo eleven astronauts, when they first came back from the moon, they went into quarantine because at that time, we weren't certain that they, you know, that they weren't bringing back any kind of moon diseases with them. Right? And that would have been potentially devastating. So now we think that's very unlikely, but still, like if we go to another planet like Mars or elsewhere, who knows? Could be.

Scott Solomon (51:49): So there is actually a framework in place to try to prevent exactly that scenario of like, you know, contaminating another planet with Earth life, whether that planet has just microbes or has something, you know, something more complex. But I'll just point out, if we're talking about space settlement, if we're talking about going and living on Mars or anywhere else, we're basically throwing out that idea of avoiding contamination because there's no way for us to go and live there without contaminating that world. I mean, we're there, but also all of all of the microorganisms in and on our body, the plants and maybe animals that we bring for food. We have to have an entire ecosystem in order to survive. And so we have to bring that ecosystem with us if we're to have any chance of of surviving there.

Scott Solomon (52:43): So, yeah, you know, it's a real thing. Like, we have to think about these questions of, you know, what are the rights of aliens, of life on other worlds, and how do we weigh their rights against, you know, against our own interests? It's it's a fascinating topic.

Larry Barsh (53:04): Sort of a reverse men in black phenomenon.

Scott Solomon (53:07): That's right. That's a good way to put it.

Larry Barsh (53:09): I'm gonna ask you the last question you pose in the book. Given what we know, should we humans leave Earth?

Scott Solomon (53:22): Yeah. So you're right. It is the less less sort of thing in the book. And in part, I sort of struggled with do I do I make my own opinion about this clear from the beginning of the book or not? And I chose to kind of wait until the end.

Scott Solomon (53:35): I just sort of wanted readers to be able to make up their own minds as we're kind of going through and exploring together. But yeah, I do reveal at the end of the book that, you know, spoiler alert, if you, you know, if you want to read it and not hear, then maybe, you know, pause this and come back to it after you finish the book. I do basically share my opinion at the end, which is that I think that eventually we maybe should be doing that. Like, think that argument that I described earlier that if we don't become multiplanetary, it could mean that we eventually become extinct and that perhaps, you know, Earth life could also, you know, eventually be destroyed. And so that seems like a strong argument for going and sailing.

Unknown Speaker (54:26): It's a comment from my producer.

Scott Solomon (54:28): Oh, okay. Yeah, yeah, yeah, yeah. Speaking of earth life, yeah, so all species of life on earth. Although I do point out in the book that there's reasons why we might not wanna bring our with us, but that's a controversial take. But anyway, I basically point out that I don't think we're ready.

Scott Solomon (54:47): That's really my conclusion is I think eventually we should prioritize living on other worlds. But there's enough things that we don't know, that we don't fully understand, like, you know, human reproduction, like whether a child born on Mars could come back to Earth, right? To me, we need to know those things before it makes sense for us to move forward with plans to, you know, to actually settle there. So until we have those answers and answers to a few other important questions that I point out in the book, I think, you know, I think we should move forward with doing research, but I don't think we're ready yet to actually start, you know, loading up the rockets with settlers who are planning to go and move to Mars. So, yeah, you know, Like I said, I wrestled with whether I should share that opinion early in the book or late in the book.

Scott Solomon (55:45): I chose to kind of save it till the end. But it was my kind of inescapable conclusion after all the research I had done.

Larry Barsh (55:53): Scott. What can I say? This has been fascinating. It's been educational. It's been fun despite what the producer had to say.

Larry Barsh (56:04): Thank you so, so much for coming on the show.

Scott Solomon (56:09): Oh, thank you. I've really enjoyed it. It's been a lot of fun for me too.

Larry (56:12): Thanks, Scott.

Scott Solomon (56:13): All right. Take care.

Larry Barsh(56:17): That's our show for today, and we're glad you were part of the conversation. If you enjoyed what you heard, hit subscribe and share it with a friend or family member who would appreciate a little sharp thinking and hard earned perspective. Until next time, I am Larry Barche reminding you that experience matters, perspective is earned, and this conversation is just getting started. The Enlightened Cynic. Take care, everyone.