Are Humans Still Evolving? (Featuring Scott Solomon)

Daniel and Kelly chat with Dr. Scott Solomon about how we measure evolution, and whether or not humans are still evolving. See omnystudio.com/listener https://omnystudio.com/listener for privacy information.

Speaker names marked ? are inferred from speaking time and the show’s known hosts — they are not voice-verified.

• 0:00Daniel Whiteson?

  This is an iHeart Podcast. Guaranteed Human.

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  Every small business owner has that one moment that could have broken them, but remarkably, it didn't. Hi, I'm Kathleen Griffith, co-host of The Unshakeables, along with Stevie Barron, CEO of Chase for Business. We have more incredible stories of overcoming the impossible still to come in season three. Listen to The Unshakeables wherever you get your podcasts and learn more at chase.com/podcast. JPMorgan Chase Bank, N A, Member FDIC. Copyright 2026 JPMorgan Chase and Company.

• 2:20Daniel Whiteson?

  What are the greatest mysteries in science? Surely up near the top of the list have to be questions like, how did the universe begin? Or how will it all end? Or how can anyone understand organic chemistry? These are all amazing questions and I'd love to know the answers to any of them. But in my opinion, the biggest mysteries are the most personal ones. The questions we have about why we are here, how we came to be who we are. The answers to those questions are the context of our existence and they can't help but shape the way we live and guide our future. So that's why the history of humanity's evolution has always been so fascinating to me, because it's our story. Where did humanity originate? How did we spread around the globe?

• 3:05Daniel Whiteson?

  What catastrophes did we barely survive? And what marks did that leave in our genetic heritage? Why are we so smart? Or why aren't we much smarter? What happened to all of our hominid cousins? And what was it like to live on an earth with several closely related interbreeding intelligent communities? We don't have the answers to all of those questions, but modern techniques are beginning to flesh out some of the biggest blank spots we have in our history and to help us grapple with the other side of that question. What does the future hold? Is humanity fixed or still changing? Has evolution had its day or are we still evolving? Today on the podcast, we'll chat with Dr. Scott Solomon about all of that and of course, about aliens.

• 3:49Daniel Whiteson?

  Welcome to Daniel and Kelly's Extraordinary Evolving Universe.

• 4:07Daniel Whiteson?

  Hi, I'm Daniel. I'm a particle physicist, but I love biology and biologists. Well, maybe one or two in particular.

• 4:14Kelly Weinersmith?

  I'm Kelly Weiner-Smith. I'm a parasitologist and you are singing a different tune than you did the other day, Daniel. Because the other day, you told me you weren't a huge fan of biology. So I'm glad to see you're coming around.

• 4:24Daniel Whiteson?

  Well, it may be that my biologist's wife heard that episode and so we had a conversation.

• 4:30Kelly Weinersmith?

  Good, good. I'm glad. My cartoonist husband, the other day, when I told him that there was a physics topic I wasn't super excited about, he was like, "You are exhibiting a distinct lack of curiosity." And I was like, "All right, fine." So anyway, our partners are keeping us in line.

• 4:47Daniel Whiteson?

  I love the wealth of topics that anybody can dive into because there's so many things to be curious about in this universe. And that's why we call the podcast, The Extraordinary Universe, right? Because it's filled with amazing things to learn about from our own particular history to whether antelopes do string theory.

• 5:03Kelly Weinersmith?

  Yeah, I totally agree. One of the things that stresses me out about having a shortened lifespan is that I will never get to like, know about all the topics that I want to know about. There's so many cool things I could be learning about, but I don't have time to read about all of them. But on the show, we get through a lot of them.

• 5:17Daniel Whiteson?

  So that's my question for you, actually. So in an alternative universe where you got to pick a different kind of science to do, instead of being a parasitologist, you would have been a?

• 5:26Kelly Weinersmith?

  Oh, my gosh. That is really hard. I think there's a world where I could have really enjoyed being a historian, or being someone who like spent all day digging in the dirt. Although, as we'll hear later in the episode, that requires a degree of patience that I might not have realized when I was excited about those ideas when I was younger.

• 5:44Daniel Whiteson?

  But that makes sense to me because you always do a deep dive in the research of asking a question like, I read three books about this and here's 10 pages of notes. I'm like, whoa.

• 5:52Kelly Weinersmith?

  Well, I really like to feel confident before I open my mouth. So I'm quiet a lot of times when I don't feel confident. But I don't know, just any job that involves a lot of time reading and trying to understand something deeply. I think there's lots of things I could have done with my life that I really would have enjoyed. But I only have this one lifetime. What about you?

• 6:13Daniel Whiteson?

  Oh, that's a good question.

• 6:14Kelly Weinersmith?

  It's your question, Daniel. You don't get to say that's a great question when it's your question.

• 6:20Daniel Whiteson?

  It's a way for me to delay giving an answer because I didn't have one ready.

• 6:25Kelly Weinersmith?

  Got it.

• 6:26Daniel Whiteson?

  You know, everybody else in my family is a computer scientist of some sort. And I actually have a degree in computer science. And so I couldn't decide between physics and computer science. And I took both paths until basically I applied to grad school in both areas. And then I had to make a decision. So I chose physics because I wanted to be a tool user instead of a tool builder. But I still love building tools for other people to use. And so in some other universe, I'm a programmer, you know, maybe working on scientific tools, maybe something else, who knows? But I love writing. Programs. And so I could have just done that as a career rather than having it be like the day to day work of my science career.

• 7:01Kelly Weinersmith?

  That's pretty cool that like if you could rewind and do a completely different career, the other career you would have done is something that you get to do a lot of in your day to day life. That suggests to me that you have really like made some good choices in your life.

• 7:15Daniel Whiteson?

  Yeah, except if I did the other career, I'd probably be making a lot more money.

• 7:18Kelly Weinersmith?

  Oh, yeah, yeah. Yeah, I also did not pick a lucrative career. Most people don't care about what's happening to brain infecting parasites on little fishies. But what are you gonna do?

• 7:27Daniel Whiteson?

  Yeah, but you're right. And I feel lucky that the day to day work of my job does connect with my other interests. And the people who work for me end up going off to make a lot more money than I do working for Google or Facebook or whatever. So yeah, it worked out pretty well. And I just love that there's so many things to be excited about and so many ways life could go and so many things to be curious about. And I love that our listeners seem to share that that really resonates with them because they seem to be curious about all sorts of topics from, you know, the details of quantum gravity, all the way to how are we here and what is the history and future of humanity?

• 8:01Kelly Weinersmith?

  And I have been loving that we've been getting more biology questions lately. And today's episode is essentially the answer to a wonderful biology question that we got from our listener named Seth. So let's go ahead and listen to Seth's awesome question before we introduce the guest we brought on the show to answer the question.

• 8:18Speaker 06

  Hi, Daniel and Kelly. I have some questions related to human evolution. Are we still evolving as a species as we have in the past? If we are, in what ways are we evolving? And what is driving that evolution? Are there pockets or groups of people evolving at different rates where natural selection may still play a large role? What changes might arise in humans from future evolution? And finally, what might evolution look like in a future society living on another planet? Thanks.

• 8:45Daniel Whiteson?

  Love the question. The only complaint I have about it is that you don't need to apologize at the end for asking questions. We love questions. Send us as many as you have. Really, no limits. Please write to us with your questions to questions at danielandkelly.org, not danielandkelly.com. That's the wedding website for a very nice looking couple.

• 9:03Kelly Weinersmith?

  That's right. That's right. So it turns out I have a really good friend named Scott Solomon, who wrote a book on whether or not humans are still evolving. And he's just wrapped up his second book about what human evolution might look like when humans move out and become interplanetary. So today, we're going to have Scott on the show to answer the first set of questions about human evolution here on Earth. Yay, and we'll have him back on the show some other time to talk about his next book and the questions about the future of human evolution when that book becomes available.

• 9:31Daniel Whiteson?

  Future yay.

• 9:32Kelly Weinersmith?

  Future yay. So let's go ahead and bring Scott on the show.

• 9:39Kelly Weinersmith?

  Scott Solomon is a teaching professor at the Department of Biosciences at Rice University. He's the author of Future Humans: Inside the Science of Our Continuing Evolution. And his upcoming book, tentatively entitled Becoming Martian: How Living in Space Will Change Our Bodies and Minds, is coming out through MIT Press in late 2025, early 2026. He hosts the podcast Wild World with Scott Solomon, taught What Darwin Didn't Know: The Modern Science of Evolution for the Great Courses, and you can check out his streaming series Becoming Martian on Curiosity Stream. And that's like a small subset of the many things that my good friend Scott Solomon does. He's incredible. We had to just take a couple. So anyway, welcome to the show, Scott.

• 10:21Speaker 07

  Hey, Kelly. Hey, Daniel.

• 10:23Daniel Whiteson?

  Can you also leap buildings in a single bound?

• 10:26Speaker 07

  I wish. Oh, my gosh. Maybe I'll evolve to be able to in the future.

• 10:30Kelly Weinersmith?

  Right there, we can hit an interesting misconception. Do humans evolve, Scott? Or is it populations and species that evolve?

• 10:37Speaker 07

  Well, humans as a species can evolve, but yeah, individual people, like any individual organism, can maybe change a little bit. We like to think we can improve ourselves over time, but we wouldn't call that evolution.

• 10:50Daniel Whiteson?

  Even if you're bitten by a radioactive spider?

• 10:52Speaker 07

  Well, that's a change I keep hoping for, but I'm going for radioactive ants ideally, but still not evolution unless your kids also inherit those extraordinary abilities. Yep.

• 11:03Kelly Weinersmith?

  All right. I mean, you go lots of dangerous places. Is that kind of like the goal that some radioactive animal will get you?

• 11:09Speaker 07

  Searching everywhere for the radioactive ant to bite me? Yeah, I'm still looking. I was just in Antarctica, and contrary to what you might imagine, there are no ants in Antarctica. So, yeah, well, at least not that we found. Yeah.

• 11:23Kelly Weinersmith?

  There are no Kelly Wiener Smiths in Antarctica either because it is way too cold, but you jumped into the water in Antarctica.

• 11:29Speaker 07

  I did. It was crazy.

• 11:31Kelly Weinersmith?

  Yes, I would describe it as crazy.

• 11:33Daniel Whiteson?

  I would describe that as poor judgment.

• 11:37Speaker 07

  Well, there was a diver in a dry suit perched on the edge of the platform you dive from, prepared to basically drag your lifeless body out of the water. So I felt like they had all the contingencies covered.

• 11:49Kelly Weinersmith?

  All right, but you've already had your kids. And so in terms of evolution, you've like checked that box. Good move. So you've mentioned that you are super into ants already. So as a person whose PhD was in ant work and evolutionary questions, what got you interested in studying human evolution in particular?

• 12:08Speaker 07

  Yeah, so I've been interested in human evolution for a very long time. Actually, I took a class as a college student in anthropology where I first really was introduced to human evolution and what we do and don't know about it. And I was just absolutely fascinated and actually considered going into the field of paleoanthropology, which is the field where people are studying human evolution. But I ended up going a different route. I was actually pre-med at the time and thought I was going to be a doctor mainly because I didn't know that there were a lot of other options for people who like biology and want to have a career. And so I did the pre-med thing.

• 12:46Daniel Whiteson?

  You were like, doctor, or I can work at a zoo. Those are the options.

• 12:49Speaker 07

  Yeah, right. Yeah, exactly. Yeah, yeah. It's just, I didn't have role models in my life of people who were doing other kinds of biology careers, I guess.

• 12:58Daniel Whiteson?

  Were your parents academics or not?

• 13:00Speaker 07

  Yeah, so my dad was a professor, but an accounting professor. So quite different. I thought I was going in a very different direction by going into biology. And then it turns out that I ended up having an academic career, very much like his in some ways. So not so different after all.

• 13:17Daniel Whiteson?

  You're both wrangling spreadsheets and email, but he's probably not jumping into the water in Antarctica.

• 13:22Speaker 07

  That's true. That's true. Yeah.

• 13:24Daniel Whiteson?

  Accounting is a little safer as a profession.

• 13:26Speaker 07

  Indeed, indeed. Yes, yes.

• 13:28Daniel Whiteson?

  But what you say really resonates with me, thinking about anthropology. I remember hearing about that field and thinking like, wow, this is it. I mean, all of science is some kind of attempt to understand the universe and our context of our lives. But like anthropology is literally like, what is the history? How did we get here? Why are we here? In terms of like, why are we who we are? So absolutely, I think it's, it's like, one of the most fascinating questions in science.

• 13:53Speaker 07

  No, exactly. I mean, I've always been fascinated by these big idea questions like, who are we? Where do we come from? And where are we headed? Right? And that's what this stuff is all about. So, yeah, I took a few twists and turns in my career. And as you mentioned, Kelly, I ended up for my PhD research studying ants, which seems like it has nothing to do with human evolution, except that ants, in some ways, are sort of similar to humans, right? They have like, complex societies. And the ants that I was studying, leaf cutter ants, they grow their own food. They have agriculture, and they manage disease outbreaks. And they do all these sort of complicated things that we normally associate with people. And so, in a sort of strange way, studying ants helped me eventually to get back to thinking

• 14:35Speaker 07

  about people. Because I knew that ants never stopped evolving, right? It's very clear from our studies of ants that they have evolved and are evolving, and expect them to continue evolving. So why not people? And that got me to think, as a young faculty member, and actually, the question came to me as actually a question I asked my students. I was teaching a class, an introductory biology class, and we were learning about evolution. And I just said to the students, well, do you think humans are still evolving? And, you know, that was a question that clearly struck a chord with my class. They had a lot of thoughts about that. They had their own questions. It was like, you know, if you're a professor, right? You guys know, like, you get your students talking, that's gold, right? That's

• 15:19Speaker 07

  what you want to do. And so, I was like, oh, this is an interesting topic. I wonder what we really know about it. And that led me down this path of eventually researching and writing a whole book on the topic of whether humans are still evolving, and if so, how?

• 15:35Daniel Whiteson?

  How hard is it to make that kind of transition professionally? I mean, if you were like, known in the ant world, and you published on ants, and you can get ant grants, is it then hard to be taken seriously in another field? I mean, I know in physics, for example, we're so niche that like, if you do collider physics, and then you write a grant proposal on, you know, cosmic ray physics, they're like, who is this guy? He knows nothing. How hard is it to make that kind of leap?

• 16:02Speaker 07

  Yeah, I mean, I think it's interesting. I guess the challenge for me was that if you look at a lot of popular science, often it's either written by somebody who is writing about their own field, right? And we're used to that, or somebody who isn't necessarily a scientist themselves, but they're writing about a particular topic that they've researched. And I was trying to do something that was sort of in between those two, right? And Kelly, I mean, you've done, you know, very similar things in your career as well, right? Where you sort of have a certain amount of expertise that you can apply to the thing that you're researching and writing about. But you're still, at the end of the day, an outsider in this very particular field that you're researching and writing about. So I found the transition to be, for myself, kind of straightforward, because, you know, we are used to talking

• 16:46Speaker 07

  to one another about research that is not exactly what we work on. I mean, we all have conversations with our colleagues and go to meetings. And it's just sort of like that, but you have to kind of encourage people to answer questions in a way that is a little different from how you would speak to, you know, your peers, which, of course, you guys know very well, because it's what you do here on the podcast.

• 17:05Kelly Weinersmith?

  Woo, it's a lot of fun.

• 17:06Speaker 07

  It is, it is.

• 17:07Daniel Whiteson?

  It's one of my favorite side benefits of doing the podcast is we'll be working on an episode about, you know, how galaxies formed. And I'm like, well, I never took a class on that. Let me go learn about it. It's like an excuse to learn something about it and go talk to the experts and digest it. Yeah, it's a lot of fun.

• 17:22Speaker 07

  Yeah.

• 17:23Kelly Weinersmith?

  The other day, I was embarrassed to realize that I didn't know why the Y chromosome is smaller than the X chromosome. And I was like, oh, I need to explain that on a show. So I guess I'm spending four hours reading about that. And it ended up being great. And also, my insecurities are slowly going away. Because I'm like, oh, I didn't know that, but now I know that. Anyway.

• 17:41Speaker 07

  Well, and I think partly, like, I'm sure you've both experienced this, in teaching university classes, we're often asked to teach something that is a little outside, or a lot outside of our own research areas. And so, yeah, we have to like, learn as much as we can about it, so that we can explain it to students and keep ahead of them. So we do that, right? I think it's just a slightly different way. I mean, Daniel, you've done this too, right? So like, I find it to be kind of a natural thing to do. I think maybe it looks weird from the outside to certain people. I don't know. I don't know if it does. But I really enjoy it. Like you said, it's fun to explore topics that are not the things that we, you know, are always reading about and doing and talking about on a daily basis.

• 18:18Kelly Weinersmith?

  Yeah. So let's back up and let's get into the meat of the content of the book. So let's just start with like, a simple definition of like, what is evolution? And how do you go about measuring evolution and like, showing that it's happening?

• 18:31Speaker 07

  Yeah, so biologists define evolution as change over generations. And I guess specifically, we these days define evolution and measure it by talking about evolution as change in allele frequencies over generations. So an allele is just a version of a gene. So to give a like overly simplistic example, you can have a gene for hair color. And the different alleles would be like an allele for brown hair, an allele for black hair, an allele for blonde hair, for red hair, et cetera. So how common each of those alleles is in a population, if that changes over time, if they either become more common or less common, then we say evolution has happened.

• 19:16Speaker 07

  And so that's something that is very quantifiable. It's something we can go out and look for in a population and say, look, this allele has become more common, it's become less common. The next question, of course, is why? But just whether or not evolution has taken place is really just as simple as is this allele or the trait that it codes for changing in how common it is?

• 19:39Daniel Whiteson?

  Isn't there always change happening just due to randomness? I mean, if you measured like the fraction of the population that had brown hair, even if there wasn't large scale change happening, you'd be going up and down this noise in that measurement, right? Is there like a threshold beyond which you say, okay, this is meaningful change and this is statistical noise?

• 19:56Speaker 07

  Yeah, so we actually have an equation that we can use to measure whether there has been significant change from one generation to the next. It's called the Hardy Weinberg equilibrium equation, and we can measure it. The key thing here is that it has certain assumptions. And the assumptions actually are sort of the thing that makes it most interesting, I would say. Because as you point out, we actually almost never find that a population is not evolving, is not changing in allele frequencies. So the only ways that it would not be changing were if a set of five very strict assumptions are in fact taking place. And those assumptions are that everybody has equal chances of survival, not just change.

• 20:41Speaker 07

  equal actual outcomes of survival. There's completely random mating. So who's mating with whom? It's all completely random.

• 20:50Daniel Whiteson?

  That sounds like an interesting society.

• 20:52Speaker 07

  Yes, exactly. Right, right. Well, it gets even more implausible. An infinite population size or a near infinite population size. Good luck with that. No movement. Nobody's allowed to move around. Everybody has to stay in the same geographical location.

• 21:07Daniel Whiteson?

  Then how are you going to mate with a random person in this infinite society? If you can't.

• 21:10Speaker 07

  Exactly. Exactly. Right. Exactly.

• 21:13Daniel Whiteson?

  You've been assigned a mate in China. Oops. Well, I can't go there. So.

• 21:18Speaker 07

  You've got it exactly right. And then the last one is no mutation. So no genetic changes can pop up spontaneously. And of course, the point here is that we know that all of those are constantly taking place in any real population, whether it's humans or any other species. So because of that, we expect that there's always going to be evolution taking place. And that is in fact what we see.

• 21:41Daniel Whiteson?

  I think there's also a sometimes disconnect between the public conception of a topic and the scientific use of the word. So when you say evolution, you just defined it very crisply. But when the public hears evolution, I think they mean big changes over a long time, like, you know, we used to have common ancestors with apes and chimpanzees and everything on earth. And so can you help us disentangle like the difference between macro evolution and micro evolution? And, you know, I often see on social media creationists that are admitting like, okay, micro evolution happens, but macro evolution is nonsense.

• 22:16Speaker 07

  Yeah.

• 22:16Daniel Whiteson?

  Is there an important scientific distinction there?

• 22:19Speaker 07

  Yeah, exactly. So we have this kind of historical distinction that we've made between micro and macro evolution. And basically, the difference between them is that micro evolution is any change that is happening within a species. And it's all the things that we were just talking about. mutations, violation of random mating, or individuals moving around. And we can get into all of those types of things. Macro evolution is evolutionary changes at the species level or above. And so the question then becomes, can we explain macro evolution through the processes that we understand very well of micro evolution? And I think there's still ongoing work in doing that, but I think the the short answer is yes, we can, right? We can look at how new species come into existence and we can

• 23:02Speaker 07

  point to the micro evolutionary processes that are giving rise to the evolution of a new species. And then, once you've got different species, then, of course, there are sort of other processes that can take place over long periods of time that can lead to those sort of large scale patterns that we see, like, you know, increases in body size and like dinosaurs and things like that. Those are macro evolutionary trends. But at the end of the day, we can boil everything down to those micro evolutionary processes that are operating within a particular species.

• 23:33Kelly Weinersmith?

  On the topic of popular misconceptions about evolution, I think that when people in the general public talk about evolution, they also sort of imply a value judgment, like when evolution is happening, that always results in improvement. Is that true?

• 23:48Speaker 07

  It is not true, and I agree with you, Kelly. I think that is a common misconception. Yeah, I mean, we have this notion of progress, right? That like every time evolution is happening, it's making a species better. And basically, the way that we would typically talk about this in evolutionary biology is natural selection is one of the mechanisms of micro evolution. Natural selection, of course, this is what Darwin figured out, right? And that is the process that makes a species better adapted to its environment. So in that sense, you can see it as a kind of progress, perhaps. But the other mechanisms of evolution that can change allele frequencies, they do not necessarily, in fact, they do

• 24:29Speaker 07

  not, we would not expect them to make a species better adapted to its environment. So just getting like, you know, Daniel, you were saying about like, what about just random changes in an allele becoming more or less common? Absolutely, that can happen. And of course, you wouldn't expect that randomness to make a species better at living in its environment. So those changes do not lead to what we sort of might look at and call progress or improvement.

• 24:53Daniel Whiteson?

  And it's not hard to think of an example of a random natural selection. Say, for example, there's a supernova that sends incredible amounts of radiation towards our solar system and kills everybody on one half of the planet instantly. And the other half are protected by the earth. Doesn't make the people who survived better or even better adapted at living, right? They're just like flipped a coin. They happen to survive.

• 25:17Speaker 07

  Yeah, exactly.

• 25:18Daniel Whiteson?

  It sort of puzzles me sometimes that people think that things that survive are always better, or the things that are probably getting to the future are always better. Like every time I get an upgrade on my iPhone, I'm like, man, this sucks. You know?

• 25:31Daniel Whiteson?

  It's a pretty common experience where I'd be like, man, the good old days were better.

• 25:36Speaker 07

  Change is not always good.

• 25:37Daniel Whiteson?

  Exactly, right?

• 25:38Speaker 07

  It can just be change. Yeah, yeah, exactly. Yeah, yeah. We have a name for this process, right? So in biology, the process of this kind of random fluctuation in allele frequencies, we call genetic drift. So the idea is that the frequency of an allele is just drifting up or drifting down over time. And it's hard to predict because it's random, right? If something's getting more common, it's not because it's better in some way. It's just because of of random change. And we actually see that operating all the time in species, especially in small populations where it can be a pretty powerful agent of change.

• 26:13Kelly Weinersmith?

  All right, so I think we should dig into that topic a little bit more. And when we get back, Scott Solomon is going to tell us about whether or not we can see genetic drift happening in humans.

• 26:32Speaker 01

  That sound? That's pro squash. Some of the fastest rallies in sport played inches from the crowd. The National Squash League is back in full swing for season four. The sport is heading to the 2028 Olympics for the first time, and you can see it up close right now in a city near you. Watch every match for free on YouTube. Search National Squash League and hit subscribe or follow live updates on Instagram at NSL.Sport.

• 27:01Daniel Whiteson?

  Hey, it's Nile Rodgers, host of Before the Moment, a Lincoln original series. I'm driving across the country, meeting some of today's most fascinating artists. We're exploring the stories before the moment.

• 27:15Speaker 03

  That changed everything. This week, I'm joined by my friend, John Legend. How does music actually enter your mind?

• 27:23Daniel Whiteson?

  I'm not sure why or how the music comes to me, but I think people who love music and write music, our brains are just filled with music.

• 27:33Speaker 03

  Right.

• 27:33Daniel Whiteson?

  Like, we have listened to so much music. We've been a part of so much music. I think of the story that I want to tell, the mood that I want to create with the music, start playing chords, see where they lead me.

• 27:44Speaker 03

  Sometimes, I'm just not even thinking about music, right? And I hear this little thing, and I go, oh, that could be this.

• 27:55Daniel Whiteson?

  You know, you just have to be ready for when the inspiration hits.

• 27:58Speaker 03

  And it comes.

• 27:58Daniel Whiteson?

  Yeah.

• 27:59Speaker 03

  Experience before the moment. A Lincoln original series on the iHeart Radio app, YouTube, or wherever you get your podcasts. OnDeck is built to back small businesses like yours. Whether you're buying equipment, expanding your team, or bridging cash flow gaps, OnDeck's loans up to $400,000 help make it happen fast. Rated A+ by the Better Business Bureau and earning thousands of five-star TrustPilot reviews, OnDeck delivers funding you can count on.

• 28:27Kelly Weinersmith?

  Apply in minutes at ondeck.com. Depending on certain loan attributes, your business loan may be issued by OnDeck or Celtic Bank. OnDeck does not lend in North Dakota. All loans and amounts subject to lender approval.

• 28:46Kelly Weinersmith?

  And we're back. So Scott Solomon was telling us about genetic drift, which is sort of random changes in allele frequencies over time. And so, Scott, is this our first example of evolution happening in humans? Do we see this happening in our species?

• 28:58Speaker 07

  Yeah, so actually, there are some interesting examples of genetic drift operating in humans. And one of the, I think, really interesting examples is from an island in the Pacific, the island of Pingalap. It's called Pingalap Atoll. And this is out in the Western Pacific. And in 1775, there was a major typhoon that struck this island, and it was very catastrophic. Out of about 1,000 people that were living on this island, there were only 20 survivors. So it was a devastating disaster for the people living there. And it turned out that one of the 20 survivors was the ruler.

• 29:39Speaker 07

  And this ruler happened to be a carrier for a genetic condition known as achromatopsia, better known as complete color blindness. And he himself was not colorblind. He was a carrier, meaning that this is a recessive allele and you have to have two copies of the recessive allele to actually have the condition of complete colorblindness. But because there were only 20 survivors, what that meant is that after a few generations, that rare recessive allele had actually become much more common in the population. And after about four generations, you started seeing the first individuals that had two

• 30:20Speaker 07

  copies of that rare allele, and they in fact were colorblind, completely colorblind. And so if you go to that population today, it's something like one in every 10 people are colorblind. And if you compare that with the sort of frequency of that condition in humans in general, it's normally more like one in 30,000 people. So you have this rare condition that just happened to become more common due to chance, due to genetic drift operating once that population became very small. And as it recovered, it just happened to get more common over time. And now it's surprisingly common.

• 31:01Daniel Whiteson?

  And just to close off a potential avenue of criticism there, it's not like the reason this guy survived is that he had this gene. It's not like it made him better adapted. Do we know why those 20 people survived out of the thousand? Was it just totally random?

• 31:15Speaker 07

  I don't think we do know, although I would hazard a guess that it probably wasn't random that the ruler survived. I'm guessing the ruler may have had access to things that not everybody else had access to that might have made it more likely for him to survive. But in terms of the other 19, I don't know if there was any particular reason why they happened to survive.

• 31:34Daniel Whiteson?

  So I'm really fascinated here about current human evolution, but I'm also really curious about the history of human evolution. How well we know that story? I keep reading articles about how we've discovered a new fossil, which completely upends our story of human evolution. Is that just clickbait? Are we constantly learning new things about the story of human evolution? Do we have a complete picture? Is the concept of a missing link a popular misunderstanding, an out of date concept? Or are there really gaps in the story?

• 32:02Speaker 07

  Yeah, so you know, this idea of a missing link, which I think we hear about all the time, not only in the context of human evolution, but in evolution in general. That concept goes back to the 1800s, when the idea of evolution was still new. And in fact, there were no fossils of early humans. So Darwin speculated that eventually somebody would find fossils of an early human or some human-like species that can kind of make the connection between us and what he assumed were our closest living relatives, the great apes. And we now know, first of all, that in fact, the great apes, the chimpanzees, gorillas and orangutans are in fact our closest living relatives.

• 32:47Speaker 07

  We can tell from looking at genetic and genomic data. It's quite clear that's not disputed at all anymore. And we know in fact specifically that chimpanzees are our closest living relatives.

• 32:58Daniel Whiteson?

  And that doesn't mean that we are descended from chimpanzees, but that we and chimpanzees have a common ancestor.

• 33:03Speaker 07

  Yes, that's exactly right. So what it means is that about six to seven million years ago, there was a species that was not a chimpanzee and was not a human. And there was a split. And one lineage eventually gave rise to the chimpanzees and the other lineage eventually gave rise to humans. So this concept of a missing link was, you know, it made sense back in the mid 1800s, when there weren't any fossils that kind of spanned that time period. But that is definitely not the case today. So we have had an incredible last, you know, 100, 150 years in the fields of paleoanthropology, archaeology and paleontology. And the number of specimens that has come into our

• 33:49Speaker 07

  Collections or scientific understanding is just remarkable. So yes, there are still questions, there are still gaps, there are still a lot of things that we don't fully understand. But the picture of human evolution in the past is much clearer than it used to be. And so one of the things I think that's really clear, like one of the big take home messages from the study of human evolution in the past is that this old idea of what's called the march of progress, if you like, just close your eyes and picture human evolution, right? You very likely have this image in your mind of like a hunched over ape looking thing that kind of is moving from left to right and standing up a little bit straighter and eventually upright.

• 34:31Speaker 07

  And then, you know, if this is like a funny meme, then it might kind of go from there to like being hunched over a computer or something like that. But the idea of this march of progress is that, you know, there was a linear progression from something that was more like an ape to us. And we now know that that notion is really not correct. In fact, there was not a linear progression, one, you know, A leading to B, leading to C, leading to D. But instead, there was really this incredible explosion of diversity that took place, meaning that at any one point in time, there were multiple species of humans or human-like species, we call these hominids, alive at any one point in time.

• 35:15Speaker 07

  And that always blows my mind. It's actually only very, very recently that we live in a world where there's only one type of human.

• 35:22Daniel Whiteson?

  How disappointing, too. Wouldn't it be awesome to have like six or seven different kinds of humans? The politics would probably be insane.

• 35:29Speaker 07

  Yeah, for sure, for sure. Yeah, exactly. But intriguing, right? Like, how did they interact and they view one another? And, and this is what a lot of people are trying to work on today. But yeah, we definitely have way more information about.

• 35:42Speaker 07

  The history of human evolution, how we became human than we've ever had in the past. But as you point out, there are new discoveries still being made that kind of shake up that understanding. And part of that involves discovery of new species. So these keep happening. People are out there finding these incredible things. So in South Africa, and I think it was in 2013, there was the discovery in a cave of a species called Homo naledi. And this is just remarkable. A lot of unanswered questions about it. But that species hadn't been seen previously. And then in 2019, Homo luzanensis was discovered in the Philippines. So we keep finding new species that contribute to a clearer picture

• 36:25Speaker 07

  of our evolution. They still give us some new mysteries to solve, but they also help to fill in some of those gaps.

• 36:33Daniel Whiteson?

  It's so amazing, but also to me so frustrating to think that there are fossils out there waiting to be unearthed or just lying in a cave that could reveal so much about our story. And we just don't know where they are. Somebody could just say, over here and over there, and these fossils, by the way, because they're just sitting there waiting. It's like in physics, if somebody had done a bunch of experiments that revealed the nature of the universe, and then just hidden them around the globe.

• 36:58Speaker 07

  Yes, it's absolutely true. And the people that are doing this work are incredibly patient people, I have to say. So I co teach a class at Rice University in the summer where I co teach this with my colleague Manuel Dominguez Rodrigo, who is himself a paleoanthropologist and an archaeologist. And he works at Oldenby Gorge in Tanzania. And we brought students out there. And one of the things that the students got to do was help with the excavations that his team is doing at these sites that are like one and a half million years old. One of the things that I took away from that is you can see the excavations that they're doing, and you can understand what they're unearthing. But you look at the hill that they're digging into. And as you point out, Daniel, there's so much more in there. They

• 37:42Speaker 07

  know there's more in there. They don't know exactly what, but they know there's more in there. But it takes them years, and sometimes more than years, like decades, to very slow And very carefully chip away at that hillside at that slope because they want to very, very meticulously, not only unearth it, but be able to describe the exact spatial relationships between each of the things that they're finding because they get so much information from that. So they're very, very careful people and, you know, very patient people. I would struggle with that.

• 38:15Daniel Whiteson?

  It's incredible that we found anything, you know, it takes so much time, so much luck. I have these fantasies about like developing scanning technology that you could just like see everything inside the earth and automatically just like identify this stuff. Man, maybe someday there'll be a transformational leap in our technology.

• 38:30Speaker 07

  Oh, that'd be great.

• 38:31Kelly Weinersmith?

  Like in Jurassic Park.

• 38:32Speaker 07

  There you go. Exactly.

• 38:33Kelly Weinersmith?

  If only we could recreate all the stuff in Jurassic Park. That would be.

• 38:37Speaker 07

  What could possibly go wrong?

• 38:39Kelly Weinersmith?

  That's right. That's right. No downsides at all.

• 38:41Daniel Whiteson?

  That's definitely not a cautionary tale. No, no, no.

• 38:43Kelly Weinersmith?

  No, no. I think when most people read the title of today's episode, are humans still evolving? They were expecting that they would hear a story about how we're getting better at dealing with some stressor. Are there examples like that as well where we can show that humans are evolving in response to something that's bad and we're doing better now because of that?

• 39:02Daniel Whiteson?

  Yeah. Tell us some good news, Scott.

• 39:06Speaker 07

  Well, I think one of the clear examples of ways in which evolution is still happening for humans today has to do with disease, right? So we know that disease has been a major player in our species history. We can look at malaria as an example of a disease that we know has a very long history in humans. And unfortunately, because it has a tendency to not only kill people, but to kill people when they're very young, it has had a major effect on human evolution. Because any individual that happens to have a slight ability to kind of, you know, tolerate malaria or might be able to survive a little bit longer with malaria, or even to really kind

• 39:46Speaker 07

  of fight it off completely, those individuals are likely to survive longer and are more likely to, you know, pass on their genes to children who are going to inherit those abilities. And so we see examples of traits that are Related to resistance to malaria popping up in different human populations in areas where malaria was common. So examples of this include sickle cell disease. So sickle cell disease, we think of it as a disease and it very much is for people living today, especially in areas where there isn't malaria. But it just so happens that if you have one copy of the allele for sickle cell disease, you have a certain amount of resistance to severe malaria.

• 40:30Speaker 07

  And because of that, that allele was favored by natural selection for many, many years in parts of the world that have a lot of malaria. Thalassemia is another example of that, particularly in the Mediterranean region. Different types of thalassemia like beta thalassemia is a condition that can help you to survive a malarial infection. So that was the case in the past. It's much less the case today because of course we have access to, you know, other types of prevention and treatment for malaria. Actually, there are still some places in the world where there isn't sufficient access to modern medicine. And there's some indication that natural selection actually still does favor those conditions in those parts of the world.

• 41:15Speaker 07

  There've been some studies that have documented that. But we can also point to more recent disease outbreaks, right? And so, for example, COVID-19. Actually, there's some studies that suggest that there are genetic traits that are correlated with people having a more severe reaction to COVID-19. And that suggests that that is a trait that is at least capable of evolving, meaning that the genetic condition that would make somebody sort of better able to handle COVID-19 without having a severe reaction to it could become more common over time. And, you know, while nobody wishes for there to be more pandemics,

• 41:58Speaker 07

  it is unfortunately likely that new diseases will continue to pop up in the future. And, you know, we should expect that any individuals that have a little bit of an advantage when it comes to tolerating those diseases are going to be more likely to pass those traits on to their children.

• 42:15Kelly Weinersmith?

  Yeah, this is of course the thing that sucks about natural selection is it requires people to die for it to happen.

• 42:19Speaker 07

  Exactly right. Yeah, it is not a pleasant process. It's not a good process in a sense, but it does work.

• 42:25Kelly Weinersmith?

  When I talk to people about Are humans still evolving? The question that I usually get asked is like, well, we've got all of these antibiotics. We've got all of these ways of keeping people alive. So evolution is probably not happening anymore because all of these things that used to kill us, we can protect ourselves from now. And I feel like what you're saying is to some extent that's true, but we don't have that great stuff everywhere. And there's still some new stuff that pops up from time to time to kill us. So yeah, how do you respond to that critique?

• 42:52Speaker 07

  Yeah, so you're absolutely right that natural selection is not operating in the same way as it has in the past because we have all sorts of things, not only modern medicine, but other types of technologies that can, you know, help us to deal with all of these things. And that means that we're not just stuck with whatever sort of the genetic cards that you were dealt at birth, right? Like, it's not only about those traits that we inherit from our parents. They do play a role. And so there is still the possibility for natural selection to operate. And the data suggests that natural selection is operating. But I think increasingly, we have this kind of separation where other factors, our culture, our society, our behaviors, our collective intelligence can play some of the role that

• 43:37Speaker 07

  natural selection used to play.

• 43:38Daniel Whiteson?

  The way I think about it is natural selection still happens, of course. It's just that the environment we're adapted to is being changed and manipulated. We're modifying what's required to survive, which means natural selection selects for different things, right? In this case, you know, the wealth of your parents is probably a factor because of the healthcare they can provide and all sorts of stuff.

• 44:00Speaker 07

  Yeah, for sure. No, that's definitely operating today in a way that probably was the case in the past. But of course, those differences in wealth are so exaggerated today in a way that they wouldn't have been if you look back at early humans.

• 44:13Kelly Weinersmith?

  And this is why biologists don't get invited to a lot of parties. We're going to take a break. And when we get back, we're going to ask Scott about whether or not our microbiome is evolving with us.

• 44:35Speaker 01

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• 45:04Speaker 03

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• 45:22Speaker 02

  My small experience with the discrepancy in the business of music made me angry in the best way, and I wanted to, I wanted to finish. So I started really leaning into my therapy, trying to get down to like, what matters now? Somewhere, Miguelito felt like he didn't have a place to say how he felt. And music was the place that I went to to say how I felt.

• 45:44Speaker 03

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• 45:53Kelly Weinersmith?

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• 46:32Daniel Whiteson?

  All right, we're back and Kelly's joking about how biologists don't get invited to parties, but as a physicist, I knew that the best thing to do to make a physics party fun was to invite a bunch of biologists.

• 46:42Kelly Weinersmith?

  Well, that's because every party's better with poop jokes. And that's what we bring to the table.

• 46:50Daniel Whiteson?

  And it also improved the gender balance.

• 46:52Kelly Weinersmith?

  All right, Scott, so microbiomes, right? We've got a lot of interest in microbiomes these days. Do they play a role in our evolution? Or do we impact how they evolve? Is there cross-play there? What's going on with our microbiomes?

• 47:06Speaker 07

  I'm fascinated by the microbiome. I mean, I feel like this is one of the areas in biology in the last just couple of decades that's totally changed the way that we think about the world, nature, ourselves. So I think part of the answer is it's still such a new field that we're still trying to sort of, you know, wrap our heads around it and fully understand it. But we do know a few things. So one of the things that is known is that, first of all, many of the microbes that live in and on our bodies, what we call the microbiome, they do things that are helpful, are useful, right? And we also know that there are certain types of microbes that only live in our bodies. Like, you don't find that same species of microbe in other species, even in our closest relatives.

• 47:50Speaker 07

  And in fact, if you look at the evolutionary history of some of those species and trace it not only in our own lineage, but also in our closest living relatives, like chimps and gorillas and orangutans, the relationships among the microbes mirror the relationships among the apes. And what that tells us is that as we evolved, they evolved too. They've been co-evolving together with us. And so combining that with the knowledge that many of these microbes are helpful does sort of lead us to think that, yeah, you know, these species may have influenced our evolution, we may have influenced their evolution, it's probably a little of both.

• 48:33Daniel Whiteson?

  How do you learn about the history of evolution of microbes? Is it just looking at the genetic codes and how much variation there is?

• 48:39Speaker 07

  Yeah, it is looking at the genetics. So basically, we need to get samples of the microbes. And this is often done looking at gut microbes. We have got microbes all over us, but the greatest number and diversity is in our digestive tract, in our stomach, in our, especially our intestines. So you need to get access to like a gorilla's gut microbiome. And that is not something that, you know, people are normally citing up to, you know, volunteer to do.

• 49:09Daniel Whiteson?

  Aren't chimpanzees constantly throwing their poop at people? Seems like it'd be pretty easy.

• 49:13Speaker 07

  Yeah, you just grab a butterfly net and wait, right?

• 49:17Speaker 07

  Make it angry and then catch what comes at you. That's, yeah. Let's write a proposal.

• 49:21Daniel Whiteson?

  Yeah, that's a protocol.

• 49:26Speaker 07

  Luckily, it turns out that, yeah, actually poop is the answer. So yes, see? Yeah, it all comes back to the poop. Right, Kelly?

• 49:33Kelly Weinersmith?

  I knew we'd get there. I knew it.

• 49:34Speaker 07

  Yeah, yeah. So it turns out the microbes that are in poop are a pretty good representation of the microbes that are in the intestines more generally. And so what you need to do is go out and like find gorilla poop. And so, you know, researchers will do things like, for example, to train dogs to sniff out gorilla poop. And then, you know, you can go around the forest and look for gorilla poop, take some samples and sequence the DNA.

• 50:00Daniel Whiteson?

  Science is always glamorous, isn't it? It's just always glamorous. It's like James Bond every day.

• 50:08Kelly Weinersmith?

  Imagine being trained for that job.

• 50:11Speaker 07

  The poop sniffing dog? Yeah, this is like the dogs that didn't make it to the like drug sniffing school or something like that.

• 50:17Kelly Weinersmith?

  But you know, I bet the real challenge there is getting the poop away from the dog before it rolls in it.

• 50:22Speaker 07

  Yeah, that's true. My dogs would not be good at that.

• 50:24Daniel Whiteson?

  I bet that dog is very proud of the roles playing in our scientific understanding, as it should be.

• 50:30Speaker 07

  They should be. They should be. Yeah.

• 50:32Daniel Whiteson?

  Who's the best boy of science? Yes, good job.

• 50:37Kelly Weinersmith?

  Our listener also had a question about are humans affecting the evolution of other species on the planet more than we have in the past? What do you think about that?

• 50:45Speaker 07

  We definitely are. I mean, look, first of all, there's just more of us than there ever have been by, you know, orders of magnitude. So of course, you would expect us to have a bigger impact. And of course, we also have much more technology than we've ever had in the past. And that means that our ability to affect the rest of the world is enhanced. So yeah, I mean, there's tons of examples, right? Some of them actually, I would say, are reminiscent of the impacts that we've had in the past, like, for example, through hunting. So there's actually an interesting study of elephants in Mozambique that showed that they are evolving to become tuskless. And the reason is very sad. It's because, of course, the elephants are being killed for the ivory that their tusks are made out

• 51:30Speaker 07

  of. But what it means is that any elephant that happens to be born without tusks has a real survival advantage. And there is a genetic trait in some of these elephants in which some of the females, it's only females, unfortunately for the males, they can be born without tusks. And so there was a study that showed that because of how much poaching was taking place in Mozambique, particularly during the civil war that took place there, that actually the rise in tusklessness was like threefold. So in other words, it used to be pretty rare for an elephant to be born tuskless. And now it's something like about

• 52:10Speaker 07

  half of the females are born without tusks. So that is clearly humans having a major impact on this particular population. And I say that's like the things that, you know, I mean, humans have been hunting elephants since before we were Homo sapiens, right? So in that sense, it's not new. It's just that we're so good at it now that the elephants don't stand a chance, unfortunately. But yeah, we're having other impacts, right? I mean, climate change, of course, is a huge one. And we see examples of coral evolving to be able to tolerate warmer sea temperatures, right? The question is, can they evolve fast enough? And can all of them evolve that ability, or only some of them?

• 52:51Daniel Whiteson?

  Right. Because evolution is not omnipotent, right? It's possible to just wipe out a species if there isn't enough diversity and just zero it out. And then it just can't recover, right?

• 53:01Speaker 07

  Exactly. And, you know, evolution only is dealing with whatever is the immediate challenge to it. It can't sort of predict what's coming down the line. So that stuff is concerning, but we do see a lot of examples of humans having this impact. I mean, one of the other clear examples through our agricultural practices and use of pesticides. So we can see the evolution of pesticide resistant insects, or in medicine, the evolution of antibiotic resistant bacteria, another microorganism. So this is clearly an impact that humans are having on the natural world that is a much bigger impact than what we've ever been able to have before. And it is very clearly an evolutionary impact.

• 53:40Daniel Whiteson?

  The comment you just made reminds me of a question I've long had, which is basically, why are humans so smart? I mean, we evolved in a situation where we needed to learn to stay dry and feed ourselves and make friends, but not necessarily to like play chess and think about 11 dimensional spatial manifolds and do super complicated mathematics. Why are humans so smart? Do we understand that from an evolutionary point of view? What happened in our ancient past to create this brain, which as far as I understand, is equivalent to the brain people had 50,000 years ago? Why did we end up so intelligent?

• 54:17Speaker 07

  Yeah. So I mean, this is actually a really interesting question, and it's one of the things that paleoanthropologists are trying to study in terms of looking at what we can see from the fossil evidence. And one thing that is clear is that there was a big expansion in the size of the cranium, the part of the skull that holds the brain, that happened during the Pleistocene era. So this is a period that going back about million and a half to, you know, two or three million years ago, in which there were dramatic climatic changes, dramatic climate changes that were happening around the world, and specifically changes that were happening in Africa, where our ancestors were living at the time. And actually, the reason there were such dramatic climatic changes has to

• 55:01Speaker 07

  do with changes in the tilt of the earth, right? So we are on a planet that has a tilt of about 23 and a half degrees at the moment, but that tilt changes over time. There's sort of fluctuations and also in the shape of our planet's orbit around the sun. It can be sort of more round or more stretched out. And as you sort of put those two changes together, you get time periods in which the climate is especially volatile, in which you can have relatively rapid swings from really wet to really dry, really cold to really warm. And that type of change was happening worldwide, but especially in Africa during this time period.

• 55:43Speaker 07

  And that is the time in which we see this really dramatic rise in the size of the cranium in different species of humans. So we think that this was basically natural selection favoring greater intelligence. Now, the correlation between brain size and intelligence isn't perfect, right? Just because the brain grows larger doesn't necessarily mean that they get smarter. I mean, the largest brain of any animal species in the world is that of, you know, certain species of whales, which are they intelligent? Yeah, they're pretty intelligent. Are they more intelligent than us? Probably not. But in general, we do think that that increase in brain size probably had to do with an increase in intelligence to a certain extent.

• 56:27Speaker 07

  So it probably did have to do with the ability to handle and cope with those dramatic changes. I mean, if you're sort of living out on the African savanna and just trying to, you know, feed your children and not get eaten by lions, you know, and you've sort of figured that out to a certain extent, and then all of a sudden, the climate completely changes, right? You have to figure out a new way to do those things. That is really going to be a tall order. So we think natural selection was really operating at that time to help people to deal with those dramatic changes. They had to work together, right? So part of what we think is driving some of this change in intelligence

• 57:10Speaker 07

  is the ability to communicate with one another, the ability to work together, to understand what another person is thinking and maybe predict what the other person is going to do. We all know that's a hard thing to do. So that intelligence would have been favored by natural selection as our species was just having to cope with these new challenges to our survival.

• 57:32Daniel Whiteson?

  There has to be something more than that, right? I mean, I know that we don't have the whole picture, of course, and I don't expect you to have the whole picture. But like other species existed at the same times in the same environment and antelopes can't do string theory, right? As far as I know, maybe they are and they're just not sharing the answers with us.

• 57:48Kelly Weinersmith?

  Maybe string theory is maladaptive.

• 57:51Daniel Whiteson?

  Maybe having physicists is bad for humans. Is that what you're saying? But my point is we aren't the only ones to face that environment. Yet we seem to be the only ones to develop this capacity, not just to solve the problems of that era because you didn't have to be able to do string theory to survive in those volatile circumstances, but to do this crazy intellectual wrestling matches that we do today. So it seems like there's got to be more to the story, don't you think?

• 58:14Speaker 07

  Yeah, well, it is definitely true that, you know, not all species became more intelligent during that time. So what was it about us, right? And I think one of the answers to that seems to be that we already had a bit of a head start. So if you look at the change in brain size over the last like six million years, like going back to the time in which we shared a common ancestor with chimpanzees, there was already a trend towards bigger brain size in some of the early human ancestors. But then it really just sort of rapidly increased in size during this period from around one to two million years ago. So what was happening then? Well, that's when you get these climate changes. So it's probably something to do with that. Of course, we need a time machine to go back and be able to tell for sure.

• 59:00Speaker 07

  But the reason that other species didn't also become more intelligent during that time probably has something to do with the fact that they didn't have much genetic variation for brain size or intelligence. So that's like a really key thing to recognize is that natural selection by itself is powerless unless there's some kind of variation that already exists that selection can sort of sift through and say, okay, this version is going to do a better job than this other version and do a better job. Just means basically make more babies. At the end of the day, right? Evolution, it's just all about babies and who's making more babies. So if there were some individuals that happened to have a slightly bigger brain, happened to be more intelligent.

• 59:46Speaker 07

  And if that led to them making more babies, then you know, that was what became more common.

• 59:51Daniel Whiteson?

  In some alternate universe where a population of humans found a different strategy for surviving those volatile times by being like really good climbers or super fast, then we might all be Usain Bolt today, for example.

• 1:00:02Speaker 07

  Yeah, exactly. Yeah.

• 1:00:04Daniel Whiteson?

  Fascinating.

• 1:00:04Speaker 07

  It's pretty stochastic at the end of the day, and there's a lot of things that could have gone differently that would have turned us into a very different species or caused us to not exist at all.

• 1:00:14Kelly Weinersmith?

  You talked a lot today about different misconceptions people have about evolution and human evolution. Are there any others that you encounter when you talk to people about evolution that are worth debunking while you're on the show?

• 1:00:26Speaker 07

  Yeah, I guess to me, the one that comes up most often is this idea that just because a trait seems like it would be useful, that we should expect it to evolve.

• 1:00:34Daniel Whiteson?

  Like, where are my wings, Scott?

• 1:00:36Speaker 07

  Yeah, exactly. Right. Or the one that I hear so often is like, you know, hey, everybody's playing video games these days. Does that mean our thumbs are going to be bigger and stronger in the future because, you know, be better at playing video games? And my answer to that is, well, do people, first of all, have variation in thumb size and strength? I don't know. Maybe they do, but that would be one thing that would have to be true. The other thing is that the people with the big, strong thumbs would have to have more babies. And that's where I have my doubts.

• 1:01:09Kelly Weinersmith?

  So I've read both of your books and yeah, that's right. I got to read his second book early. And I get the sense from reading your books that you really enjoy the travel that goes into researching the book. What was your favorite research trip that you've taken for a book so far?

• 1:01:24Speaker 07

  Well, first of all, Kelly, I love that you have been willing to read my books, including in advance. And you've given me some really great feedback and suggestions. So thank you for that.

• 1:01:35Daniel Whiteson?

  Kelly is so good at that.

• 1:01:36Speaker 07

  She is.

• 1:01:36Kelly Weinersmith?

  Oh, thanks, guys. It's my pleasure. I love getting to read early copies of books.

• 1:01:40Speaker 07

  But you're right. I do like to. Travel. And so, you know, one of the things that I've enjoyed in researching that these books that I've written is traveling around and, you know, meeting people who are doing interesting work. And I really enjoy being able to kind of describe the work that someone's doing by kind of, you know, showing people how they do it and, you know, getting to know them in their natural environment, so to speak. So, yeah, I mean, I've done some interesting trips for this book, Future Humans. I think the trip that was maybe the most fun that I got to do was to go to Quebec. And there's an island in the Saint Lawrence River with a French name that I will not attempt to pronounce. Apologies to my high school French teacher.

• 1:02:21Speaker 07

  But the reason is that this island is a place where there has been a very interesting series of research studies by a biologist named Emmanuel Milot. And I got to go actually to this island with Emmanuel Milot. We traveled there together. And what was interesting about it is that this island was first settled by French Canadians in the 1700s. And that he and some of his colleagues, Emmanuel and some of his colleagues, were able to basically trace the history of the human population on this island and show that there has actually been evolutionary change among the people living on that island between about 1800 and the 1960s.

• 1:03:06Speaker 07

  So this is like, you know, roughly sort of seven or eight generations of people that lived on this island. And because it was an island and because it's kind of hard to get to, it was relatively isolated from the surrounding communities. And so what they showed is that actually the age at which women had their first child changed on that island from averaging about 26 years old to about age 22 over that time span. So the women started having their first child at a younger age during that time period. And what was especially interesting about this population is that they had a complete genealogical record of the entire population

• 1:03:50Speaker 07

  because of church records. So everybody pretty much went to the same church and the church keeps track of births, deaths and marriages. And so because of that, they had this whole genealogy of this population. And they were able to basically rule out that this change in the age of first birth. It could have been due to other factors. You might imagine that it was like, well, some people might have been, you know, richer or poorer, or had access to more food, or a different culture, whatever it is, right? And basically, they were able to rule out all of those other possibilities and show that, in fact, it was a response to natural selection. So basically, natural selection was favoring women starting their families at a younger

• 1:04:33Speaker 07

  age, because women that do, on average, tend to have more children. And that is actually something that is predicted from evolutionary theory, but it had never been shown before in humans, particularly not in a modern human population. So it was really interesting. It's a beautiful place. They are lovely people. We got to go and spend several days on this island. We met a lot of great folks there, got to learn a little bit more about the history of the island. It was really interesting to go with Emmanuel Milot and actually see this place that had been, you know, this subject of this really interesting study he had done.

• 1:05:09Daniel Whiteson?

  It's amazing how important islands are to the history of evolution and our study and understanding of it, right? We're lucky we have islands.

• 1:05:15Speaker 07

  Yeah, it's true. I mean, partly because they're sort of like these little miniature versions of what are normally much more complex systems. So, you know, going back to Darwin, right, you know, in the Galapagos, I mean, biologists still go to islands because they often help to kind of reveal more complicated phenomena in a somewhat simpler way.

• 1:05:33Kelly Weinersmith?

  I also feel like if I could go back and have a different career, being a historian would be really cool, to just be able to like handle old documents and see like old writings. I don't know, something about like really old stuff.

• 1:05:44Speaker 07

  Oh, yeah.

• 1:05:45Kelly Weinersmith?

  Is really exciting to me.

• 1:05:46Speaker 07

  Absolutely. I mean, one of the things that we did was we actually visited the Archdiocese of Quebec and got to see the archives where they actually had these original records of births, deaths, and marriages. We had to open up those books and see for ourselves. And I get goosebumps when I see that kind of thing, right? I mean, it's just getting to have that immediate connection with history. I think it's super cool.

• 1:06:05Daniel Whiteson?

  That reminds me of the exhibit in the British Museum where they have original manuscripts from famous people. So you can see like Mozart's scribbles and Beethoven like crossing stuff out and really fascinating to think like, that guy actually wrote on this piece of paper. I don't know why, but it is really Powerful, right?

• 1:06:21Speaker 07

  It is. We actually at Rice in our library collection, we have the collection of work from a biologist named Julian Huxley, who was a famous biologist in the early 20th century. His grandfather, Thomas Henry Huxley, was one of Darwin's closest friends. And there is a copy of The Origin of Species in the library that was given by Charles Darwin to Thomas Henry Huxley. And it has both Thomas Henry Huxley and Julian Huxley's notes in the margin. It's just the coolest thing to see. No, I still get chills thinking about it. Yeah, it's so cool.

• 1:06:53Daniel Whiteson?

  Speaking of chills and connecting back to Antarctica, one of the things they have in the British Museum is like the logbook of one of these journeys to the South Pole. And you can see like the last page where the guy writes, it is very cold. And then that's it. Like that's the end of the logbook. Yeah, they found him with it.

• 1:07:11Speaker 07

  Oh, that's ominous.

• 1:07:11Kelly Weinersmith?

  Was that the Scott expedition?

• 1:07:13Daniel Whiteson?

  Yeah, it might have been. Yeah, exactly. But you know, he was taking data till the end, a real scientist, you know?

• 1:07:19Speaker 07

  Oh, my gosh.

• 1:07:20Daniel Whiteson?

  Keeping records. But now I want to get to the inevitable place we always get to on this podcast because everything leads to aliens and

• 1:07:28Kelly Weinersmith?

  Or cannibalism.

• 1:07:30Daniel Whiteson?

  And I want to ask you about aliens because I want to know if what we've learned here on Earth is particular to our experience here, where we tend to have islands and we have this particular history, or if this is something general and universal, we've learned about life in the universe. So we're landing on an alien planet and we brought you along, Scott. Are you expecting to learn that on this planet, there's natural selection and this evolution? Or do you think that that those are things that just happen here on Earth because of our particular set of circumstances?

• 1:07:58Speaker 07

  Yeah, I love this question because it forces us to ask like, what is life? And do the things that we know about life actually apply universally or only to this particular version of life that we know? We actually in biology, struggle to even define what life is. And there's a lot of things that are sort of like gray areas, like for example, viruses, right? I don't know, Kelly, if you have opinions on are viruses alive? That's like a way to start a fight at a biology conference, right?

• 1:08:29Speaker 07

  But one of the definitions that people have proposed for what is life is that life is capable of evolving. And so like by definition, then if we see life, then yes, it should be capable of evolving. But that's like a circular definition. So it's not very satisfying. So I think another way of thinking about it is. Unless another form of life is immortal, if it has immortality and one individual can just live forever, then no, they wouldn't evolve the way that we think about it. But as long as there is mortality, as long as there is death, and as long as there is reproduction, and as long as there is some way for individuals to pass something of themselves to their offspring,

• 1:09:13Speaker 07

  to the next generation, in that basic setup, you will always expect natural selection to work. You would always expect the basic principles that we've been talking about of evolution to work. And that, to me, is one of the most powerful things about it that I think people don't often realize. We're not just saying evolution can happen or, you know, under some circumstances, you might get changed. No, it's actually inevitable. It's sort of built into the system that anytime you have a thing that lives for some amount of time, reproduces, passes something on somehow to the next generation, right? That there will be changes that are heritable that are happening from one generation to the next. Now, the specific things that are evolving,

• 1:09:56Speaker 07

  the traits, the rules that maybe govern who survives and how they reproduce, that's all up for grabs.

• 1:10:02Daniel Whiteson?

  The biochemical mechanism, whether it's DNA or not, yeah.

• 1:10:05Speaker 07

  Exactly. It doesn't have to be DNA. It doesn't have to be anything like the way genetics works for Earth life. But as long as there is some mechanism of inheritance and as long as there is reproduction and multiple generations, there will be evolution.

• 1:10:20Daniel Whiteson?

  I like that you're very clear about the assumptions that go into that conclusion because that immediately opens doors for like potential science fiction stories. Like I imagine now a planet where a biogenesis is very common. It didn't just happen once, but it's like constantly happening. And you're always getting like new forms of life propping up. And they don't reproduce, they just die out. I guess in that scenario, you wouldn't have evolution, right? You just have like a constant random genesis of weird kinds of life.

• 1:10:44Speaker 07

  Yeah, and that is an interesting thing that I often think about is how come we only see the evolution of the origin of life one single time here on Earth that we know of? Or at least only one lineage of life has left descendants that we can't remember. can find today. Why doesn't it keep happening? And I think there's reasons for that that we think we understand. But yeah, it could be that in some other world that it is much more common for life to just pop up spontaneously. And yeah, in that circumstance, each individual origin of life could give rise to separate sort of evolutionary trajectories. But we would still expect them to evolve if they could reproduce.

• 1:11:24Daniel Whiteson?

  Eventually, they would end up with podcasts, right?

• 1:11:28Kelly Weinersmith?

  Everyone podcasts.

• 1:11:29Speaker 07

  We can hope.

• 1:11:32Kelly Weinersmith?

  That's right. Everyone on the show today has their own podcast.

• 1:11:36Daniel Whiteson?

  Therefore, dot, dot, dot.

• 1:11:38Kelly Weinersmith?

  That's right. All right. Well, Scott, this has been amazing and informative and a ton of fun. And thank you so much for being on the show. And we plan on having you back to talk about the future of human evolution, which is the second half of the question that we got from the listener. What would happen when our species moves out into space? So we look forward to having you back when you are ready to talk about your next book.

• 1:11:57Speaker 07

  Well, thanks so much, Kelly and Daniel. This has been fun and I can't wait to come back.

• 1:12:01Daniel Whiteson?

  Thanks for evolving our understanding of biology.

• 1:12:04Speaker 07

  Anytime.

• 1:12:13Kelly Weinersmith?

  Daniel and Kelly's Extraordinary Universe is produced by iHeartRadio. We would love to hear from you.

• 1:12:18Daniel Whiteson?

  We really would. We want to know what questions you have about this extraordinary universe.

• 1:12:24Kelly Weinersmith?

  Want to know your thoughts on recent shows, suggestions for future shows? If you contact us, we will get back to you.

• 1:12:30Daniel Whiteson?

  We really mean it. We answer every message. Email us at questions at danielandkelly.org.

• 1:12:37Kelly Weinersmith?

  You can find us on social media. We have accounts on X, Instagram, Blue Sky. And on all of those platforms, you can find us at D and K Universe.

• 1:12:46Daniel Whiteson?

  Don't be shy. Write to us.

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