Cultural Evolution with Rob Boyd
2026-03-10 12:00:00.000 +00:00

Oh, we got another comment. People hate this is interesting to the theory of humor. Some people hate our screwing up the intro. Like uh, like there's a comment on X where somebody's like, Well, what it's it's really interesting, actually. I don't know. I wonder why people get so pissed off about that. Yeah, I don't know. Yeah, I don't know. All right. Yeah. This is Evolutionary Psychology the Podcast. I'm David Pietrazuski. I'm David Pinsov, and this is actual evolutionary psychology. By actual evolutionary psychologists. David, I am really excited about this episode. Today we have two guests. Uh Christina Moya, who's returner, who is a guest co-host, and our guest proper is Rob Boyd. Yes. This was a really fun and interesting episode.

Uh many tidbits about E. coli bacteria and Enola lizards and anecdotes from you know evolutionary biology, mathematics. What was so interesting about this is um there was some disagreements that we we navigated. Uh and we usually don't navigate too many disagreements on this podcast because um Dave and I are optimally rational agents who uh who cannot disagree on anything. Yes, and to the extent that we do we we we disagree, we we quickly realize largely that we're we're just exploring the larger space that we would both agree about from different perspectives. Yes, but uh Rob Boyd and Pete Richardson uh pioneered the study of cultural evolution, the the modeling of culture as its own kind of

evolutionary process, and the story of how culture uh has been involved in the evolution of humanity and what role it has played uh in our preeminence on this planet. And I think we're still trying to reconcile how this analysis of culture can be fit into the Darwinian paradigm or the evolutionary behavioral sciences. I think Dave and I are of the camp that uh it can be reconciled, that this view of cultural evolution is compatible with even the most extreme Santa Barbara uh evolutionary psychology model of the mind. And we try to explore that, but at the end of the day, there may still be some disagreements, and that's part of what makes science fun and awesome is that we get to disagree with each other and do some research and get to the bottom of it.

Yeah, I think I and I think this episode is a lovely example of Rob, is an incredibly brilliant. I mean, he is a giant whose uh shoulders we're all standing on. And a lot of what we take for granted, our our generation, meaning like David and I's uh generation, is because of John. Um, John and Lita and Rob and Joan and other folks like that. And I think Rob talked a lot. We talked also about that and just sort of the debates that were had um in their generation were sort of necessary for uh for coming to uh what you know uh you me and christina's uh view is now and not everybody agrees with us but that's that's part of the fun it's also a good example of uh not disagreeing to the point of vilifying

but do the opposite of like we're all friends we can all be nice uh interpersonally but still disagree um uh or have debates we should that's the point of science yep absolutely. So it was it was a really fun time uh chatting with Rob and Christina about these big issues confronting the evolutionary social sciences and also the history of our field and how our field itself has evolved. Um I think you'll get a lot out of this conversation. Yeah, enjoy. Rob, it's really great to see you. Um thanks for being on. Um I wanted to start out by asking a simple question, which is um when I when I think of you and Pete's uh and other people's work, um the the sort of not by genes alone expression. Um so the idea of sort of uh biological evolution and gene uh gene

selection um being adequate for an organism to be adapted or survive in an environment. My understanding is that one of the things that you did was to think about these other selective regimes that are on top of genetic selection, like cultural selection, as an additional mechanism. Is it accurate to say that that's something that you and the people around you really initiated and plugged in? Where did that idea come from? Um we Pete and I got started in the mid-1970s. And um it's hard to understand now, actually, um, or hard to behavioral ecology, um game theory, you know, evolutionary game theory was at best nascent. I mean, Hamilton had written these landmark papers in the 60s uh about kin selection, about senescence, um uh about sexual bunch of

stuff. And and Maynard Smith had written, uh, and Parker and some other people had written these um taken basically the very surface ideas of game theory and and shown how they could be used to formalize the frequency dependent selection that arises when when you have social interactions of various kinds. But uh I mean the the textbook I went to graduate school in 1970 and the textbook that was the main textbook in ecology was a by a guy named Eugene Odom and it set out as its central premise that species evolve for the good of the species. And um and in the US, people just didn't think the same way that we do now about, you know, I mean, if you want to call it individual advantage or gene centered, there are various ways to think about it.

But but and then in 1976 Wilson published sociobiology, which had a huge impact, uh, but was only sort of I mean, he never really completely understood, in my view, modern evolutionary theory. He was he kinda understood it, but you know, it he was still rooted, I think, in in to some degree in the older ecological, you know, Tinbergen style picture of things. Now things were somewhat different in Great Britain, where people were more centered in the in the modern way of thinking about things. Anyway, and then Dick Alexander, uh sort of, I think of Dick and and uh Wilson as kind of the fathers of American anyway, evolutionary thinking. And Dick wrote this long paper in uh the annual review of ecology

and systematics. And unlike Wilson, it was completely rooted in the new way of thinking. And and was also full. I mean, Wilson famously had this last chapter where he said this is all going to change the social sciences. But it was kind of vague. And whereas Alexander got down to cases and I don't know if you ever met Dick but he was kind of a dark character in some ways but but very insightful guy and the the paper is just full of intriguing ideas about human evolution so people did the obvious thing they started thinking you know how how can we explain human evolution in evolutionary terms And there's a lot of enthusiasm. And both Pete and I, our initial reaction is yes, but it it doesn't, it's it's not enough that people are are as different from other

vertebrates as you know uh multicellular organisms are from single cell. I mean it's and so anyway, that's why we started thinking about this. And so from the start, our idea was to try to understand. I mean, I mean, the obvious difference is different groups of people behave differently. It must have something to do with non-genetic transmission. Try to build a theory where that's something that could be favored by natural selection and at the same time lead to divergent results. And Mark Feldman and Luca Kowali-Sforza had written this book. Well, not a book yet, a bunch of papers in the early and mid-70s showing how you could use population genetic ideas, ideas from population genetics theories,

to think about cultural transmission. They were not interested in the same questions we were. Mark was has been and still is very interested in genes and IQ and trying to make proper inferences from phenotypic variation, you know, amongst families and stuff. And only much later became interested in what I think of as the as the adaptationist questions, really not until the late 80s and 90s, but we were greatly benefited by what they taught, basically, in these papers about how you could use ideas in population genetics. And in our 84 book, I think what we mainly added was, well, two things. A bunch of ideas about directional processes that would lead to adapt culturally mediated adaptation. Because what it's got to be, you know, whatever it is, besides making things different,

it's if it evolved, it's the system has to make has to be adaptive, the psychology has to pay. And also, uh, I think the thing that that we did that made people take notice was we said, okay, but yeah, how how can you make a system like that evolve from an organism that doesn't have a system like that? How can it produce fitness benefits? Um and then of course we're interested and at the same time you know lead to all the weird things that people do so that's uh we got started because we were interested in that question and uh we just kept plugging away uh what was the was the were the tools that these that was in the water that was new was it this frequency dependent the game theory or ESS analysis and then then that was

the that was sort of the idea that was those were the tools. Is that correct? Or what would you say are were the well I think the the that was you needed those tools to do a proper job of asking what natural selection would do. You know, I mean you're making lots of simplifications like usual. But what Kavali Sforz and Feldman added and we added was seeing that uh once you have sufficiently accurate social learning, however that works, it creates another system which carries information through time, creates history. And in most organisms, I mean there are a bunch of things. There's succession and and you know all this extended evolutionary synthesis stuff. You know, so Pete Pete was raised on a farm and he likes farming examples.

And uh if you think about transmitting farms, that's a kind of example of how you can have a non-genetic transmission. If you inherit a farm, your the behaviors that are good for you, everything else, is different than if you don't inherit a farm. But farms can't spread the way the idea about how to farm can spread. Because energetically small things, you know, knowing when to plant and knowing how to fertilize and stuff like that, they can spread extremely rapidly because they don't the the information itself doesn't count for much. Uh so I think that's personally, I think that's what makes culture different than other forms of. I mean, fins are a good example, but how you get from fins to legs, um

uh knowing something about development and knowing something about homeobox genes and all these things that that encode developmental rules gives you a lot of purchase and understanding. So you know the story of TikTolic, this I think it's still the oldest fit, uh oldest land vertebrate. And this this guy whose work I'm uh what's his name? Uh your inner fish um I can't remember his name. This is a the hazard of old age. But anyway, I can't remember anything from the screen. My my proper noun module is failing on me. But but um so if you look at the you know, invertebrates, the uh uh landvertebrates, the you know, you get one bone in the upper arm, two bones in the next length, and then all kinds of little bones.

You don't get any of that in fish. You just get this. and the question is, how do you get from fish to land vertebrates? And this guy whose name I will remember eventually, um he was he's a paleontologist. He worked on yep in North Greenland on these sediments that had um, you know, uh 500 million year old um no, that's not right, must be more like 300 million year old, anyway, early land vertebrates, and um and he and he found these forelimbs of these early fishy um land vertebrates. And to understand how you got there from fins, you really do need to understand. Well, I don't know if you need, but it it's immensely it makes it much easier to understand what happens if you understand how limb development works.

And so, you know, um, you know, the phenotypic gambit gets you why these organisms needed rigid forelimbs and and a bunch of other stuff, but it doesn't tell you why they're built the way they are. Yeah, no, no, no, for sure. It's not the whole picture and it's not satisfying for explaining what what which part of organism space to to use the talk. Exactly. It's yeah evolution is depends on where the variation is. And the phenotype gamba just essentially says, I don't know about that, so I'm not going to worry about it. Exactly. And I think this is actually something Christina and I have talked a lot about over the decades that that also, you know, you simplify what's not relevant for your particular

um right goals. Right. Um and I think, you know, and one of the other things too is, you know, I uh obviously I was a student of Lita Cosby's and John Tube. Yeah. And I know there was a history of, you know, it was sort of uh love and conflict in the sense of you both had uh there were similar missions of evolutionizing the human behavioral sciences, using evolution to understand human behavior. But then there was um and yeah I know Rob, you and I have had conversations over the years too. Um uh yeah I mean maybe the well yeah and Christina no exactly. Um uh I mean do you I don't even know where to start with that. I don't I don't know if I even have a question, but like that might lead into um yeah I

think it the contrast I think is um uh is useful. Uh I mean, and I wouldn't have said was, Lita's still around and right, still working, is that right? Yeah, no, Lita, yes, of course. Yeah, no, Lita's and we spent six months together at a institute in Germany and um and uh I would say we're friends, but um or were with John and but definitely pretty deep disagreements about uh how to think about both evolution and um and then about human evolution in particular. Um I was my evolution training came uh at UC Davis, which in those days was the heartland of selectionist biology. And then I did a postdoc at the University of Chicago, um, where the there was a renaissance. Uh it didn't last that long, but uh in uh monitative

genetics and genetics of characters that are affected by genes at many loci. And and I would say that John and I had real disagreements about, forget about culture, about how evolution worked. And um, I mean, I still think I'm right or was right, but but I'm sure he thought the same. Uh he had a very fisherian view of of i and i don't really know i never talked to lead about this very much but s selection being acting on dragging genes slowly and he put a lot of emphasis on species as a real thing and i think they're at best an abstraction uh and the picture of evolution that that i think is is correct is that m most evolution now isn't always true. Sometimes it does work in a fisheron way, but but it's working on standing variation.

So I don't know if you take uh so I mean there's been a lot of water under the bridge since, but um so this guy, John Losos, I don't know if you know his work at all. He works on anoles in in um the Caribbean. And um so it turns out that on each of the Caribbean islands there are a whole community of these lizards, anoless lizards. And there's big ones that live in the top of the trees and the little skinny ones that run along branches, and other ones that hold, you know, and And they've got typical phenotypic, these are mainly morphological color differences. And none of the of these guys on the different islands are related. On each island, these um morphs evolved from some generalist that made it to the island and then differentiated into all these things.

Okay, not so radical already. They've done experiments where they in Loso says, and this is there's lots of work like this now, where they introduce lizards to islands with no lizards. And within five years, you begin to see these species first track the ones that run the little branches end up being having shorter legs, and the ones that live higher up in the trees have longer legs. but five years. This isn't gene new mutations happening and being dragged slowly across to fixation. This is taking standing variation that affects morphology and rapidly shifting. And there's lots and lots of examples like this coloration in deer mice, um uh coloration in guppies, life history variables in guppies.

So you can so in Guppies, there are these rivers in Trinidad where all this work has been done. And as you go up the river, eventually you get to a pond above a waterfall where there are no predators. And the guppies up there are have slow life histories, and the guppies just below the waterfall have fast life histories, right? Because they got to get going before they get eaten. And so this guy Dave Resnick, who's at at Riverside, um put various predators, two different kinds of predators in these things above the things. And within three or four years, you've got faster life histories. And um so can I ask if if the implication of this difference in thinking is that evolution can happen much quicker if it's acting on standing

variation. But is it also something about the nature of the variation, like that these are something like packages of traits, something going back a little bit to the phenotypic problems of the phenotypic gambit? Yeah. don't yeah. Are there constraints that you think are important to consider or no? There are, I'm certain, but I don't think we know what they are. I think um so resnik also, I mean, so these are all pretty simple changes, although life history, I don't think we really understand exactly what's going on there. Um but uh he he did uh in the same genus as guppies, but not guppies. Um he worked on um the evolution of live birth. So um uh a lot of fish have live birth. They retain the eggs inside their bodies.

The the little developing embryos feed on the yolk, and then they have live birth. That's not such a big deal. But there are three species in this genus that have evolved placentas, basically. So they they lay eggs with hardly any yolk. And then they have uh an organ that uh it's not like our placenta particularly, it's designed differently, but still it's a complex organ whose job it is to provide nutrients to these little developing embryos that don't have any yolk to eat. And uh at a minimum, they've evolved that those have evolved in 250,000 years in one of the species, maybe a million in the other two. And that's a minimum. That's from the last common ancestor that doesn't that doesn't have this tray.

Um, So I don't think we really know about the evolution of I mean simple things like morphology, we know for sure that can evolve fast. And it it evolves fast, not because it's one gene, it evolves fast because it's many genes, each with small effect. You make a wolf into a Pekinese and you know, in hardly any time at all. And and I don't think we know about um but I do think it makes you think twice about the EEA and and th that our mind is a or our brain is a series of modules that were designed to deal with things ten thousand years ago and haven't changed since. Uh I actually think this is a problem that so my colleague here, um uh Kevin Langergraber has has argued that chimps have menopause.

Uh and that's hugely controversial right this second, and people argue back and forth. I don't want to get in the middle of that one. But menopause, uh, people have measured the heritability of menopause. I had a student a long time ago, Jocelyn Pichet. You knew Jocelyn, didn't you? No, it was before my time. Before your time. She measured the heritability of menopause about 0.3. And her there were some problems with her work, but it's been done twice since, and estimates are about the same. So what that tells you is if there were a selected, so now you have peasant populations, agricultural populations, where, you know, women could keep having kids. Why aren't they keep having kids? Um and if you I mean the selective advantage ought to be pretty big.

You could move menopause, this is the age of menopause, which in most populations is around 50, pretty easily in a few thousand years. Not even that. I mean, and we know a thousand years, well, we know historical evidence, let's say, that suggests it hasn't changed much in the age of menopause in 2000 years. Now that's not very good data, but so anyway, I think there are I I don't have an answer to this question. I mean, in the end, uh I'm more of a agnostic about these things than than Lita and John were. And uh yeah, go ahead. Maybe like one of their arguments would be, or maybe not them. I don't know. I've seen Ed Hagen recently, like Yeah, it's a good good foil because he's so smart. Be so careful, right?

Yeah. And I my understanding of some of their argument is that um complex adaptations, which is I mean, it is a complex adaptation because like now we're talking about, you know, quantitative traits that have multiple those sides, multiple phenotypes, but that um you know, I guess it's not arguable to say that the human brain is a complex adaptation, but there might be diff, you know, differences. Obviously, there's genetic variation in various cognitive, but I'm sure memory is I'm sure so so many things. Yeah, yeah, yeah. What isn't? Um, but that like the fundamental kind of um questions about human cognition that are like more species typical are unlikely to have changed as much in the last,

I don't know, 10,000 years or something like that. Um, what do you make? I guess obviously it can't be any kind of um categorical break um in terms of what has and hasn't changed, but I guess there is, you know, there there's the equivalent of um biological anthropologists who look at kind of lumbar morphology and bipedalism and how it kind of works generally in humans. And I guess maybe their argument, but you guys might represent it better, would be something like there's the the equivalent attempt at doing something like that for the human mind. Um and and I think, you know, yeah, I there are things like lumbar morphology that are species typical in humans, but there's a lot of other stuff that's, you know, family

typical and and uh you know so uh and and I don't think uh you know how much of I No what's exactly species also but yeah we are very, very you know uh living as I am living amongst paleoanthropologists these days, um uh No mess. Well, you know, I mean my my the director of the Institute of Human Origins, uh Johannes Heile Selassie, has just published in Nature a few weeks ago this species of Australopithecus uh Deridimata. Derridimata. When he first published it, I thought, ah, come on. You know, is that really that different? Is that as well? How the heck do we know? Living at exactly the same time as Aphorensis? And now he's got pretty good evidence that it had a significantly different mode of

locomotion, that it had a opposable, semi-opposable toe and and um much longer arms. And you know, is that a species? Uh you know, I mean, all dogs are the same species, right? But if but if people found those fossils in the fossil record, Actually, this goes back to a story when Lyle visited Darwin in the mid-1850s. And you know, Darwin was a pigeon. He he kept pigeons of and and people had bred all these and you know, just as diverse as dogs, basically. And Lyle said, you know, shuddered that this basically wrecked everything because if we found these pigeons in the fossil record, they'd be different families. Yeah, more from based on their morphology. So you know, so I don't know how I got there exactly.

As a very short person, oftentimes, like with towering people around me, I think how paleontologic would have surely classified as a but I'm not enough of a paleontologist to know. I mean maybe if they only got like my humorous or something like that. Yeah, exactly. Joan says that uh uh if you don't know David, Joan's about the same height as Christina, roughly, don't you think, Christina? I think maybe she has an inch on me. So I'm 4'11. Oh, she's five feet. Yeah. Those inches really make yeah, yeah. So she claims five feet. Uh and um she says all people are tall. You know, I can't tell a difference between okay. So I I don't know about John and Lita. I mean, I uh their method required them that there were these modules and by looking at contemporary behaviors, because they

were the result of modules or some kind of enclosed I know you've written about modules. Yeah, but I mean but I mean it doesn't I don't mean modules in that technical psychological sense. Yeah yeah uh but that you could map particular input output relations back to some problem in the police. If you can't do that you've got problems, right? And I'm skeptical about that and uh you know uh and I'll I'll rat Pete out here. Uh Pete and I have ferocious arguments about this, basically. Um, he thinks there are none, no modules. And he bases this on, he's read a lot more than I have, of neurobiology. And um, there was a paper in Nature um some nature reviews a few a year or two ago uh which argued basically human brains

just have more of the same they're just chimp brains with more of everything and no special f features i i can't i have no idea how to evaluate those kind of arguments And so I say, Pete, what about birds' nests? What about you know, beaver dams? Those look like modules to me. And you know, beavers, I've read quite a bit about beavers and uh little beavers. So beavers live in ponds where the everybody behind the dam is fairly closely related. The ecologists have studied them, you know, the averages are like 0.3 or 0.4 or something like that. So, and you know, pretty impressive, actually. But when the little beavers leave, they disperse, and they beavers build different kinds of structures and different kinds of aquatic environments.

Sometimes they build little canals back to a pond they make for themselves. Sometimes they just build lodges on the side of streams. Sometimes they build dams. They build dams in different ways depending on how much water pressure there is. And those little beavers seem to know how to do that without ever having seen a dam being built. There's no social learning involved. And the same thing is true of birds' nest. Uh there uh so weaver birds, people have done raised weaver birds uh without any um exposure to nest building. And they build now, they don't do there is learning involved. So the first nest a weaver bird built is not as good as the second nest that he builds. And they are all the men or the males are building the nest, so he is okay.

But um so there's some kind of information encoded in weaver bird brains and in beaver brains that tells them how to build a nest. Uh and so that makes me skeptical of the neurobiological arguments. Uh and I can't convince Pete. He's he's really really gone over to the everything is is um plastic kind of picture. And it's based on, you know, he's not stupid. He doesn't think it's a blank slate, but but he thinks it's there are these general motivational and embodied principles. And then that's where all the details come from. And I don't know. So I I just know that I'm I can't, I'm not convinced that anybody knows the answer to that. So do you think it's like an ontogenetic phylogenetic distinction?

Like, I mean, do you think the people are saying it's just more of they're looking at the ontogeny and then the sort of to to to be really glossy about it, like John and Lita are thinking about sort of the the phylogenetic design on the developmental system to kind of bring it back to what we talked about before. But they weren't emphasizing that because they weren't studying the developmental system. Yeah, I don't know. I mean, uh uh every time I read neurobiology, I think, you know, they don't know what they're talking about, but at the same time they know a huge amount of stuff. And uh so I don't know. I just don't, you know, I I I never have had the enough background or ambition to um really and I don't think my own guess is I mean I bet

my career on this kind of that it's not there yet. They don't know enough to know how it all works and um and uh and firm conclusions one way or the other, yeah, uh are dubious. But yeah, I I remember uh Randy Gallstell gave his talk because he's got that Gallastel um uh and I can't think of the other person's name because I can't think of nouns either. Um, but uh but they've got this book about you know memory requires addressable read write format. Yeah. And uh, you know, neural conductance changes don't doesn't buy you that. And I remember he gave a talk at Yale when I was a postdoc and he gave the talk in front of the neuroscientists at Yale and he gave this like hour long talk and they went crazy.

And actually he was like the nobody had a good answer. And really when it came down to literally one of the people said, Yeah, but it's hard. So yeah, so I think your career is fine, Rob. I think they don't know. We don't know. No, we don't know anything. None of us know how this stuff works. I will tell you a Randy Gallstall anecdote, which is on the same theme. So I was at a conference in Paris, and and uh I was sitting next to Randy, who is a has a wicked sense of humor. And um uh and it's kind of a contrary, you know. And uh so this guy was giving this, you know, it was kind of a typical um neurobiology talk. He was an anatomist, and he was, you know, this is kind of like the old song, you know, the

thigh bones connected to the neck bones. They have all these circuits in the brain and and different pieces are connected. And he had done a whole bunch of fancy work to to learn how, you know, information, we presume, is being transmitted between these uh uh anatomically different parts of the brain. And so somebody, and I don't know who raised their hand and said, Uh can you explain uh how the information that's transmitted all along these circuits is encoded? And Randy leaned over to me and he said, Now a glimpse into the abyss. And and and uh so uh and the guy had no answer. I said, We have no idea. And uh no, this is 20 years ago, but yeah. Well, at least it was an honest answer. Yeah, no, I mean, and that's yeah, I think that's I mean, I I appreciate that about all of

us here is you know, I don't know, it's a good thing to Didn't you say I Rob, I feel like this is a story you told about John Maynard Smith where something somebody said something, Oh, you changed your mind once. And he said, Of course I did. I I knew the data. Like, is that no, I don't know that story. Okay, yeah, yeah. But I think that yeah, thinking that feeling like you have to know something is is a curse of the ac the account. Yeah, yeah. No, he was uh John is my intellectual hero and um and uh he was an honest guy that way. Yeah. Did you know him? Um kind of. Uh I uh I met him at various conferences and then we we got invited to this, both got invited to this. Uh that it's in Steyr, um, Austria, every year they

have a kind of a school on on um some topic. And uh uh the I got invited to give a bunch of lectures on, and and they invite a bunch of students for a week, and then the last day a bunch of big shots show up. And uh so I wasn't a very big shot, but I they talked me into giving lectures about game theory and kin selection to all these students, you know, four days, hour and a half lecture every day. And uh so I get there, and who's in the audience but John Maynard Smith? Holy crap! And uh and um so unlike the other big shots, he showed up the first day, listened to the whole thing, talked to the students. Uh, he was great. And it turned out that like me, he's an early riser. So, you know, at 6 30 every morning, he and I were there at the beginning of the line to

get breakfast. And so I had breakfast with him every morning for the week. And I hung out with them. We got to be, you know, we were hanging out together a lot. Yeah. And then I met him some other times. And I I mean, he was a prickly guy, but I thought great. And um and um you know, not a modest fellow, but but uh I don't think he probably had good reason not to be honest. That's that that is true. Um I I wanna see if I could so uh it'll probably be um of interest to our listeners to see if we could really nail down on what the disagreements are between uh you and Lita and John. So in discussing these differences about how evolution works, it's gonna really make me fess up here now. But okay sorry.

No I think it's important for us to get a handle on precisely what the disagreements are and whether they even exist. Because I think there are some people who think that we can all just get along and these disagreements are just kind of narcissism of petty differences. Um but uh so in talking about your your differences between Lita and John, you mentioned rapid evolutionary change and guppies and lizards. You talked about uh the evolution of menopause, how it has surprisingly low heritability and how there may have been surprisingly high heritability. Oh, you think? Okay. Regardless of the thing. 0.3 means that if you get a one standard deviation change due to selection, you get a three tenths of a standard deviation change per generation.

Do the math. You get Yeah, that's true. Um but nevertheless, uh I I believe the suggestion was that um, you know, there could have been selection for uh increased menopause in recent human evolutionary history, but the fact that we didn't see that suggests that there's some kind of constraint to um to adaptiveness. Is that the same thing? No, or that, or that for some reason a 50-year-old menopause is is fitness maximized. Uh okay. All right. Um well so the I I'm still trying to nail down what the disagreement is then. Is it just that um uh there's been more recent uh evolution than perhaps Tubian Cosmodies think? That uh maybe the EEA is more recent than they they might have thought, or is it is the

point that there are constraints on optimality that limit the utility of adaptationist analysis. What what what is Yeah, no, I uh all this is secondary. Uh um uh the real disagreement between John, Lita, Pete and I uh is I think about um cultural evolution and its role in explaining behavior. Um Pete and I think that uh, well, to put it as bluntly as possible, that in humans, selection has favored a psychology that does stuff that causes people to do stuff that they see people around them doing, even though they have no uh adaptive reason to think that's the correct thing to do. And uh I've got models, of course, that show that's possible. Now that's you know, why maybe as as Pete's kid used to say.

Um and uh uh uh philosophers use talk about why possibly, that's what models but I like why maybe better. Um and uh I mean I think, I mean, I've talked to John about this. Uh he just I had never talked to Lita about this, but uh uh he thought that was impossible, that our psychology couldn't be built in a way that uh you would learn to be celibate, or you would learn to risk your life climbing mountains, or you would learn all those things would have to arise from motivations and information processing that would have been favored by selection in a hunter-gatherer existence. Um small bubble bands, et cetera, et cetera. And I just think that's wrong that that selection has created a psychology that causes us to be susceptible to

the social environment, informational environment in which we live. And because it it it's so social learning is a two-edged sword. It gives us immense adaptive power, much greater adaptive power than any other vertebrate. Since now I'm giving a speech, but I'll give the speech anyway. It depends who you listen to, emerged from Africa. And they spread across the world in a few thousand years. So this is a a um a vertebrate uh a tropical forager living in warm environments with a particular mix of of adaptations that are necessary. And it looks like within a few thousand years they're living north of the Arctic Circle, and in which the suite of adaptations necessary to make a living is immensely different.

And you need clothing, you need housing, you need all kinds of stuff. And uh this people were able to acquire all these adaptations for all the different parts of the world they lived in because they could evolve culturally and acquire inf so it's not individual humans that adapt. Human populations adapt because they can share information and they can it only works if you adopt adaptations that you don't understand why they're the way they are. Credulity, yeah, like the kayakism. Yeah, so you have to be credulous. And what you get for that is this huge adaptive machine that gives you things that individual cognition, as smart as we are, is grotesquely underpowered to acquire. And uh but that means that you're prone to picking up ideas that

you know aren't that sensible sometimes. And so I think it's a it's like lots of stuff in evolution, there's a trade-off. There's a trade-off between having cultural adaptation, and I'll say just as an aside, David, uh I think selection's important, but so are non-selective processes. So it it it it it cultural selection is only part of the story. Um I mean transformative processes like spurber and all those guys are are for sure important. And um uh uh and we can talk about that if you want. But but so uh and I think I mean maybe I'm caricaturizing caricaturing um uh John and Lita, but I I think and I've talked more to John about this than Lita. He just thought that was nonsense. That uh that um um people were smart.

They had all these domain-specific adaptations and um it it seems like though that there's a compatibility between the two views. I the only disagreement that I can pick up on is on the extent of of credulity about this cultural information. But it seems like you could get that kind of cultural adaptation with a fair amount of credulity and a fair amount of scrutiny of the different cultural variants and a fair amount of sensitivity to, say, the success of a particular hunting practice or a particular person who's adopting that practice or the particular social benefits. You know, all of these, the psychology could be sensitive to all of these variables, and you could still get this cultural adaptation.

And in fact, it could even facilitate this cultural adaptation if you have these psychological sensitivities. Of course. Yeah. I mean, this is um, you know, what people say about scientific theories. Um uh the first the first reaction is well, that's complete nonsense. How could that possibly be? The second reaction is, well, maybe under particular circumstances, and the third reaction is that's what we thought all along. And um, and uh, you know, uh I maybe I think maybe there's a sociological pr point here to make which is that like I think for the point of showing the novelty and the of of being able to make new predictions. Um I think you know culturalists have often pointed to really amazing things that are weird

in humans, like you mentioned celibacy, like sacrificing for and Kind of the in-group. And I do bet that like some people don't think that that's, you know, there are different explanation people propose different explanations for those extreme examples. Um, but I think that that has maybe sometimes lended to be characterized as like uh people are dumb perspective, or that like the the credit like that's the extreme level of credulity, right? Like that is credulous, yeah. Right. I I I mean, um so if you think people are endowed with a so the thing is well, I mean, celibacy is an interesting one because people obviously like sex, right? And um and so the question is, how could it be? I mean, I've not just from John Alita, I mean Dick Alexander and all

those people. Come on, you know, I mean try to find an adaptation like people know what they're doing right now that it's worth and the thing is uh the selection can't I mean in my view, selection can't endow us with you know have sex no matter what, because uh there are always trade-offs. So um it I mean uh to take an example, uh in in uh the Maasai, um young men, Maran E, uh are the warriors were supposed to be celibate. And um when they graduated from that age set, then they could get married and have sex. And of course, big surprise, sometimes they had sex, but you know, as Murani, not as as as seniors. But it was costly, right? There were norms in place that people imposed costs. And so people, sure, they like sex, but they're also sensitive to, you know.

And so where do the norms come from? The norms on John Alita's account, I would say, have to come from some module somewhere. And um on my account, they can evolve all over the place because we don't know. It we're not very good at figuring out how society should be organized. That's another thing we don't understand very well. I mean, I I've argued sort of endlessly that selection of cultural differences between groups is one force that shapes norms. I am surely that can't be the only thing. It doesn't explain a lot of change. It's too slow. There are a lot of reasons why it can't be the main, the only main process, and I don't think we're very good at at there's some papers by Lehman and Powers and some other people

about bargaining. I I think there are problems with that way of looking at it, but I think within group processes uh must be important. And um and so we got to figure that out. But it's I I think that the fact that these things are heritable at the group level, that they meaning that groups persist, you ship shift environments and and they'll shift eventually, but there it often is quite slow. And you can predict a lot about what people's norms are from what language they speak. And all these things are not the signatures of a universal psychology mapping environment, meaning the ecological physical environment, onto social behavior. It's there's some history and and um if evolutionary psychologists want to th say that's what we believe, fine.

I've won. But uh and I think that's right. I mean to just put it like you know like I think Christina and I have these conversations. I think I like you know I wonder when you and John were talking, I think we're we're hindsight is 2020 and I think we wouldn't have the understanding we have if you and John hadn't had that debate, but I mean one thing I appreciate as a John Lita student was you know the kayak example where you don't just to to caricature the the the the the the john and leita uh my training would be sort of there's no account of kayak design right in the mind right that that there's you can have to explain that complexity and that adaptation and why that kayak does so well what I like about this.

Or bicycle. Yeah, or bicycle or anything. Exactly. Yes. I prefer bikes as we know. Yeah. Yeah, exactly. But um, yeah, no, I I mean I like that there's an extra thing to explain, which is this uh shorter time span, the trial and error. Everything is trial and error, you just don't see the error all the time, but it's you know, just variance in the world, and there's selective retention of variation in the design. And I think, you know, Christina and I, my feeling is that now evolutionary psychologists are often thinking about like, what's the EEA of the class of things that are like kayak design, exactly in the day way that David's talking about it, where there's sort of there are entries for I'm gonna accept something with credulity,

right? Um because this has been an aspect that has recurrently been so I actually think we've come, I believe we've come to completely both both being integrated, but I think we didn't we couldn't have gotten there if you guys hadn't had that argument because I do think it was missing. You know, I will say that as a student of John Leader, like I do think that the extra um I mean, I think the the idea was there. I mean the true to be DeVore paper had that idea, but I don't I do think it was under emphasized. And I do think you we needed to have that argument. Maybe that's maybe that's my buffalo everybody can get along upbringing, but I but that's my opinion. That's my two cents about it. I don't know what Christina uh thinks about it.

Um I think that there's a method I'm not we've been skirting around like the methodological difficulty of it. I mean I I generally agree that they're compatible, Rob, for what it's doing with. And I don't, and maybe historically they weren't. Um but there's a methodological difficulty as well in like parsing out, you know, no, if we all agree that the kayak isn't the EEA, but there's like a kayak-like things. There's no kayak module, but there's maybe is like, you know, a cock, there has to be a cognition that's capable of accepting and processing kayak-like things. And what is the category of kayak-like things? The difficulty is that, like, I'm not sure that we the kayak is a is a good or bicycle is a

good example of that because we know it's like technological evolutionary history. But things like kinship structures or social systems, we have no idea. And then it becomes, I think, a much harder process of like disentangling of like, well, you know, is the reason that we have these kinds of like intuitions about kinship or about um, I don't know, maybe reciprocity or maybe about fatherhood? Like, is that like a kayak? I see. Yeah. So you're just don't have like the the historical knowledge of when this kind of fatherhood institution or this social system evolved? Or is that really a deep seated part of human cognition? Well, I mean, kinship. We know that there's a lot of cultural variation in kinship, yeah.

And and we've got some idea of the timescales on which um those systems are. I guess with like phylogenetic kind of from Ruth Mace kind of stuff. Yeah. Yeah. And so I mean, throughout Western central Australia, all the dry bits basically, people had these incredibly complicated eight-section kinship systems. Do you guys know about those? Yeah, Christina knows. She's around. Yeah, exactly. And uh there's I tried to learn that it's really complicated. And and you know, that's evolved on something like 10,000 year timescales, right? Um and well we know from the geographical extent, I think, that and linguistic correlation that we don't really know. But but I mean it's not like bicycles, it's not the last hundred years.

It's it's uh and kayaks we don't really know. I mean, I wish we did, but we the history of kayaks, there's some toy kayaks from about 4,000 years ago. They look like the modern ones, but and that's about all we have. Uh, and then some that are a few hundred years old. Um, so we don't really know very much about the time scale. Um and surprisingly, people on the north coast of Asia and Kamcheka and places like that, which you'd think present pretty similar ecological problems. They do build skin boats, but they're really crude compared to the skin boats of people in North America. So I wish we knew more about that. And um the only good examples I think we really have are uh pretty recent um things.

Uh there's a gor there's this guy whose name I forget again, sorry, who English guy who um studies the evolution of looms in East Asia. Uh they're fantastic. He really understands the history and the phylogenetic patterns, and there's a bunch of horizontal transmission, which makes, I mean, horizontal not in the between group transmission of ideas. And anyway. So I don't think we know. But I guess what I was trying to argue, Rob, is that like we know that we we we have good reason to believe that like 50,000 years ago we didn't have kayaks everywhere. Uh I don't buy that. Okay. Okay. No, I don't buy that at all. So so there could have been like we could have, I mean, I know there's debate about like

Neanderthals also doing some level of like seafaring or Oh, I think the evidence evidence for seafaring uh and the first people who got to actually of all people, Kristen Hawks has a paper, uh, Kristen and Jim O'Connell. Um, quite good, I think, for my taste, quite good evidence that the earliest settlers of Australia had ocean-going boats. Oh, wow, okay. Um they get this from the settlement of offshore islands, which are which would have been you know 50 or 100 kilometers. Or maybe there is a kayak module. No, but they weren't the same boats. You know, the uh all the details about how to make the kayak. No, I agree. You know, it it's there may be some boat module, possibly. I I'm skeptical actually, but but um uh But more more plausibly there

are folk physics modules. I mean, I don't like the term module, but there are systems that have intuitions or expectations about the physical world and how objects interact. Surely there are there are probably uh you know folk engineering or tool use modules where we have a concept of what a tool is and that it has a specific function. That's what this guy uh o Suriak, this French guy. Uh Anyway, sorry to interrupt. Yeah, no, and and Clark Barrett has argued this in his book Um Uh The Shape of Thought. So it seems to me that even the extreme uh Santa Barbara school picture of the mind, which is filled with these context sensitive, specialized modules, right? Is totally compatible with cultural evolution and cultural adaptation.

Do you see any kind of incompatibility there? Because it seems like those those two pictures of the mind could both be true. We could both have really sophisticated minds with complex specialized adaptations, and we could have cultural evolution and culturally adaptive processes at the same time. And it may be even be the case that the two complement each other, that you're more likely to get cultural evolution in a more adaptive direction if you have the the the sophisticated mind to evaluate the different outputs of culture. But then you can't Yes, I agree with everything you just said. Okay. Um, but that's not what John Alita said. Okay. Uh they wanted to go from stories about I that's pejorative, I shouldn't say that.

They wanted to go from hypotheses about uh life in mobile foraging bands in um the late Pleistocene, and make inferences about how people should behave now. And that means that there's a direct correspondence between some adaptive, I mean, I'm quoting them now almost, some adaptive problem that people faced in these Pleistocene societies and how behavior is expressed now in response to cues that people get. And uh I'm sure that's true to some extent. I mean, but um I also think there's a huge range of behavior, which that doesn't help you with. But John John, I think, thought that got you the whole package. I mean it well, it could it could well get you the whole like what if some of those modules

involve evaluating potential uh tools or uh uh potential uh foraging strategies or potential social norms in terms of whether they advocate for one's interests or through the norm or the tool should be like correct they don't but they could nevertheless right I think that's that's true. That that's the key difference, right. But it seems like i if if we're assuming that they don't tell you the content of the norms or the content of the tool, then it seems like they're entirely compatible perspectives that you could yeah yeah but we got to fill in the details and you know uh yeah I don't think we're very close to that actually and I think Christina's point I mean just want to echo Christina's point it also then means that there is this issue of at what

level of abstraction and the the concern would be that you're looking at um something that so just to be clear, like we were talking about like where does the evolved psychology end and where does the information stored in the environment begin? And Christina's point, if I understood it, was that you it's hard to know, and there may be cases where we think something is so well designed that uh we're really looking at it as like this is something that's in the phenotype, that's you know, reliably developing, and that's why it has the problem-solving and form fit relationship we do. But then there's this other thing of once we once we accept that cultural selection can create form-fit relationships, then we might be

inferring, for just for lack of a better way of putting it, like genetic selection systems, where in fact it's more cultural selection systems. It's oh when we know the clear distinction, like Christina always talks about like reading, I think is a good example where you know if we didn't know about the history of reading, we might think it's just it's a module. It's a module. I mean maybe not. I don't I don't know. Like 'cause the fact that not everybody learns to read. Like I I I you know like any example has its issues. But I think that's a fair point, Christine. I want to make sure like that like is that fair, Christina? Yeah, and I think that so I was trying to also I not to be like material versus social is

like a clear distinction, but I think that the social world is fuller of that ambiguity. Like we don't know very much about about Paleolithic social life. It probably was super diverse. Um we don't know what it was like two million years ago, three million years ago, like forget it, right? Um, and like to to do a parallel to the reading example, like almost every society has marriage today. I know there are exceptions. Um, and so we might infer that there's like a marriage-like modular world cognition that really favors marriage when you know we have good theoretical reasons to believe that that's probably a cultural institution. Like, yes, you know, partly driven by like psychological motivations that are patent human

and so forth, but I think it's a real challenge to disentangle those, and more so when we don't have like a good paleontology or archaeology to kind of help with our intuition about it. Yeah, yeah, yeah. The idea that our brain is just uh you know a shapeless mass with no predispositions, that's just obviously stupid. And um I you know, Steve Pinker's book, The Blank Slate. I mean, I know there are lots of social scientists who believe in the blank slate, but they're just not thinking hard about things. It can't be. It just it just no matter what, they can't be, you know, and so it's always about how does it work exactly. And um or I completely agree with you Christina maybe exact we're never

going to get to exactly but maybe a little bit of structure uh and um and uh I so what I would say is questions are not about whether there's evolved stuff in the human brain that shapes the way we respond to cues in the environment. That's gotta be, right? But there are questions about, you know, quantitative questions about where we sit on a kind of continuum. And my picture is um, because we're predisposed strongly to think what people around us do must be sensible, um uh uh we get a lot of stuff from that and um and i i if that's the way that evps psych is going i'm pleased i mean that's um uh uh you know you know when there's gonna be disagreements you know we're scientists right that's the business we're in but but uh but on the other side of things coming from like

what um what questions might have influenced cultural evolutionary theorists um coming from like the more cynical like economists or of psych side, do you think that there's been any shift in like thinking about what that credulity has to look like? Or like what the limits of that credulity are? Yeah, it's a good question. Um I mean I think of it more uh I mean so so I talk to Sarah Matthew quite a bit, and she and I differ about um how likely it is that evolved motivations, I would call them about kinship and stuff, structure, cultural evolution. And, you know, she could be right. I mean, um, I could be right. Uh these are things that we're gonna learn. But I wouldn't say uh I I think of it as a bunch of specific stuff, not

some general limitation about how credulous we are, but how strongly we're motivated in by different kinds of things we experience in the environment to to um to think well no yeah uh there's this xkcd cartoon that that um the mother is asking the kid you know um Are you, you know, the kid says, I I'm, you know, you you're doing this just because all your friends are doing it. And the kid says, is, yeah, that would what would I I I always succumb to kin pressure. And the mother says, why would you do that? You know, suppose you were on a on a burning bridge. And uh, and the kid says, Well, if 50 of my friends, well informed, jump off the bridge, who am I? You know, what's the newspaper the next day gonna say about the people who stayed on the

bridge? And but that depends on the cue. It depends on what inferences you can make from the environment. You know, maybe all those people were stupid. They jumped off the bridge, and you're the smart person who who made the calculation to do it correctly. Um something that makes me super anxious about our enterprise here is that I think I think we can largely agree that there about like certain basic motivations that we have, right? Like motivations like hunger is motivating, um, sex is motivating, so forth. And you know, you might think on a good day, like, okay, we just need to find like the order in which the prior like the algorithm that prioritizes some motivations or the other, including the motivation to conform to others, might be like, I think there might be a

little bit of a debate about how much that's in an uh bit of motivation to conform to what others do. Yeah. Um but on my nihilistic days, I think what's crazy is that those motivations themselves culturally evolve. For sure. So that makes kind of coming up with like a well, but look, I mean motivations to conform, culturally. You're prone to these kinds of motivated by hunger, right? Or like how much you should be motivated by yeah but you're prone to these depressive uh uh uh feelings Christine I've known you this long uh think of where we've come in the last 75 years even 50 years you know I wouldn't we're much less confused now. I'm sorry. Yeah yeah I I wouldn't frame that as the motivation to conform evolving itself.

That doesn't really make a lot of sense to me. What might make sense is that the costs of not conforming might vary from place to place. Well, I think the power imbalances and the alliance structure might be such that there are really powerful people who are really going to do bad things to you if you violate the norms. And in some environments the power structure is different and those costs aren't as high. But I wouldn't explain that as culture shaping the motivation to conform. I would just explain that in terms of, you know, the mind making cost benefit calculations about what what is going to be the likely course of action in this particular social context. Yeah. You're a real evolutionary psychologist.

Uh uh there's quite a bit of evidence that in other creatures that uh there's an innate conformist propensity. It's got nothing to do with norms or other people's punishments. Uh some evidence in people, it's somewhat conflictual, conflicting, um, but models show that in the right kind of environment, having an intrinsic motive to conform can make you better off. Yeah. And uh in the fitness sense. And uh now it hangs on being hard to figure out what the right answer is. And um and uh so and I think I mean now this is I won't live long enough to find out what the answer to this question is, but uh I think we are innately predisposed, or innately, we have, you know, reliably developing whatever you want to call

it, uh um propensity to obey social norms. Um we don't do a cal well, we do do calculations, but we don't need to. We're we uh all other things being equal if if the norm is to um you know play the game a particular way lime in the corn sure yeah so you know these these experiments that Mike Tomasalo has done i watch the videos he te they teach some little German kid a new game Daxing and um and then the kid learns how to play the game, and then they have a f a Schill who then plays the game wrong. And the kids, Nick, not not not Daxing, he says in German, you know, he gets gets really agitated. That's his verboten. Yeah. And uh you know, I don't think uh evolutionary psychology um i i think our

our sense that some things are right and some things are wrong there's morality and uh and we feel intrinsically motivated about uh moral violations that's not in my view now this is a hypothesis not a fact uh uh a calculation based on the cost and benefits of powerful people. It's something we feel and I can make models that show how such a thing could evolve. Doesn't mean evolve that way. And it again depends on uh on the difficulty of doing the calculations. Uh and um um so uh I think uh that one is one which we're gonna make progress on, actually. That uh uh yeah, totally. You you you may be right there, Rob. There may be a real disagreement here, but I want to push you and and uh to acknowledge

that maybe there is no disagreement. We're just talking past each other because even your model of norms is built on the foundations of punishment. What a norm is is something that people are punished for doing and the non-punishers are punished, right? And so the the punish the idea of punishment, the infliction of costs, is built into the model. That's it's built into the evolutionary model, not the contemporary why people do it model. So that explains why we have a norm psychology. Once you've got a norm psychology, you know, the reason that you're outraged that oh, what it was some outrage at the Olympics recently about uh some rule. But anyway, um uh or I mean seriously. But doesn't it presuppose that you have to know what's being punished and what's not being

punished? No, no, no. You just need to know what the norm is. But then how but how do you know what what the norm is if unless you're observing because people teach you, because you see what everybody does. How are they teaching you though? Presumably they have to, you know, threaten you with punishment or actually punish you, right? No, no. Uh so I I don't even think you believe this. Um uh uh so uh is it okay to beat your wife? I mean, obviously not. And well, some I call it. I think it's fine. Uh yeah, when we did this fieldwork in Fiji, um uh Fijian norms uh uh have it that if you don't beat your wife when she's talks back or does some uppity thing, uh you're a not just that you don't get what you want, you're a bad person.

And uh okay, so one of our field assistants was a couple, a married couple. And um uh the guy, you know, beat his wife pretty severely one night. So what do you do about that? Uh you're living in a culture where um that's the right thing to do. Uh we told him he couldn't do it. And so these moral beliefs, by the time you get to be mine, sure are strongly held. And they've got nothing to do with the calculation of of my long-term benefit. Uh I I might disagree there. I mean, like uh it I think if you ask anyone, you know, uh what will happen if you are seen as a domestic abuser, they will say that you will you will suffer horrible reputational consequences. But we pay we took this guy who was our field assistant and we paid a

substantial cost to yell at him and tell him he couldn't do that in a culture where everybody thought what he was doing was fine. I think there may be presumably people understand that there are reputational costs for engaging in certain behaviors. And that was where was the reputational cost to me? Uh I I don't uh I mean maybe to be super cynical, maybe you know it was gonna get back to your colleagues that you had a wife beater already. Yeah I mean that's the argument you'd have to make. But can I subject I don't believe that argument. I I I I mean to give you another example from my failed field work um uh uh in Fiji there's a very strong norm that women must be covered from head to toe in the village and uh

and Fijian guys gossip endlessly about shoulders and ankles uh and uh uh you know they never see anything else young guys that is and uh so we spent three months in this village and we went to the um to um uh we got at the village boat, took us you know several hours down the archipelago and dropped us at this beach where a tourist boat would come and pick us up. And so we're sitting on the beach having lunch, and a tourist walks by, a woman, and she's in a bikini. And I had this overwhelming that woman needs to put some clothes on. She is not dressed properly. And um there you did adapt to the local circumstances. I did, absolutely. Uh but it was, I didn't realize that adapted. You know, it was um this is not science, this is you know, it's my I'm giving

anecdot that living in a place where people thought it was wrong for women, and this is all brand new in Fiji. This is only 150 years old. Uh um, and she was dressed completely fine by you know, we got on this boat and it's covered with college age tourists, all of them bikinis, and in 45 minutes I didn't feel that way anymore. But uh uh um but I speak to like three different timescales at least at which like things like punishment and I mean we could there's a whole debate about what kinds of social costs these are might be acting. So mainly not punishment, I think. Mainly loss of social standing. Yeah. That's a kind a kind of p a kind of cost, yeah. Well, but it doesn't it's not costly punishment, it doesn't cost right.

If if you deprive people of costly services, you'd have to give them with because they were good people, then it actually pays you to punish them. But so there are models that are like this is about intergenerational evolutionary timescales that we're talking about. And this endowed us with some sort of like genetically evolved intuition for conforming to whatever we see other people around us to do in order to avoid those social costs. Then there's a possibility and these are not mutually exclusive because it seems like even your experiences are at different timescales, right? Two different timescales. Two different timescales. Another one is that like you in you like currently there are institutions that ostracize

you, punish you, whatever, for not conforming. And so you learn about that early in childhood, let's say, and you kind of develop these in internalized ideas about what is morally right and wrong. And then like if the social environment changes for you like in adulthood, it's not going to change very quick like those intuitions aren't going to change very quickly. They're shallow, the diff the the things yeah. I I think the only thing there is a third there is a third though, just to be complete. Like there is a third possibility, I don't know if anybody believes this, but that it's like very much in the moment, right? That like the current incentive structures shape in the moment throughout your life.

Like what is right and what is wrong. And I don't know how credible that is. I mean this is these are questions, right? Good questions. Uh um I mean the only thing I would add to to the to the is that once you've internalized that beating your wife is wrong, then when you do the calculation about should I beat my wife? Um uh I mean on David's account, and I I certainly think that's part of it, is I'm thinking about what'll happen to me if I get caught beating my wife. But I'm also have feelings that affect my trade-off that that this is not the right thing to do. I I I I get negative, you know, displeasure, whatever it is, um Because I grew up in a society and and so that tips, that changes the

way I do the the the calculation. And um you know, I so anyway. So yeah, I think some of the issue too is I think with all of these conversations, one of the problems is uh the entire conversation we've had, natural selection or selective selection based thinking of cultural things. We we lack a good nat, we don't have a natural vocabulary of what are the entities, right? Like, is it a piece of um culture design, uh a module? And now we're talking about sort of emotions, and you know, there's sort of well, like cost benefit. There's a sense in which I can calculate the cost benefit. Like Rob, I think the other thing I do is I get really angry when people cross uh pedestrian no walks now after living in Germany.

Exactly. And that's like a very that's like how many times do you get yelled at in Germany from violating some rule you didn't know? Which I yeah, I I I loved it actually. I was dispositionally German. Uh but anyway, um but uh uh but but then like there, but there's another sense of which David, you know, even the emotions, right? Like maybe the emotions baked into the emotions are cost benefit. But of course, there's a difference between the kind of rational cost benefit that sort of like goal or planning systems are considering in this very short time scale versus maybe these longer timescale emotional systems. So I think in a lot of ways, um what typically is failing us is that there's just distinctions that are not made in the natural language that we all sort of have as

organisms or just as cultural beings in the 21st century now. English speakers in the 21st century. Exactly, yeah, precisely. Yeah, exactly. And that's uh yeah, we had Clark on recently and he was making a point that um, you know, it that's is also useful to talk to other people from different cultural backgrounds because they'll make different distinctions that we might be able to use, you know, or or at least see like our cultural bias. But I think, like for me at least, uh there there's a sense in which all of these debates can be resolved, but they really hang on making more distinctions, and you can't start to make those more distinctions till you maybe you have the debates to begin with.

Yeah, I agree with that. Yeah, I think um uh you know we've made progress. That's good. Uh and science is the you know series of hypotheses now refuted. And also, you know, Mox Planck said science progresses one funeral at a time. Um, and I think there's some truth to that too. Um Rob just to push on like I mean for Pete's argument that it's sort of all very general he'll allow motivations yeah but no that can be quite specific motivations but there aren't any um I'm not actually sure how he parses this out but but uh uh there's nothing in there that tells you um what would be good examples I mean, obviously technological examples. There's nothing we're you know, like birds' nests. Uh and um maybe like no propensities

to think about taxonomic categories in a yeah, yeah, exactly. That'd be a good thing. Uh uh that we don't we aren't innately Linnaean in our taxonomic um right way of thinking. Uh and I think the evidence is pretty good we aren't. Uh uh the Fijians put dolphins and and fish in the same category, but um uh yeah, and they don't and you know so they don't have any animals they care about. They're pigs and chickens and and you know and they just don't think about vertebrates very much, but I mean land vertebrates, but anyway. Yeah. But do you think I mean I do the I mean like we all I think we all do this, and I think this is something I learned from Christina, which is this notion of you make the

tentative Almost like a gambit or like a assumption that's helpful for your own carving up the world, right? So, like I, as a as a John and Lita adaptationist, I don't want to study the complexities of like developmental programs or like genetic pleotropy. Like, I want to I want to assume that away. And so I do. And there's an argument in sense which like that's fair of me because of what I'm studying. Somebody else later, even though I'm wrong about saying it doesn't matter if I say that, it does matter, I can assume it away because for what the slice of the world is that I'm studying, I have to assume it away at least for now. Does is Pete what is is Pete assuming he's a hundred percent with that?

I mean I I mean I we think of ourselves as com full adaptationists. Yeah. And and uh but we just see the adaptive problem as different than I see it differently than than maybe John and Lita did. And uh you know in our in Nobajin Salon we have this example of the avocado slicer that uh I was, you know, the the adaptationist paradigm is uh it's not a paradigm, it's a heuristic. And uh it is an extremely powerful heuristic, which sometimes leads you astray. And um uh and depends on a bunch of ancillary hypotheses about trade-offs and costs and benefits and a bunch of other stuff. And um uh and I, you know, I have no time whatsoever for Goodian or or um uh the guy that studied Tiktalic, this fish, he's a big believer in, you

developmental constraints. I I don't think they're constraints. I think there are developmental pathways that affect the patterns of variation that can that do exist now and that will exist in the future if we make if we make some changes. And they're obviously important. And the extent that they're important, they make the adaptation as paradigm. Because if you don't know what those developmental um couldn't is this a I'm thinking something about why you wouldn't call this a constraint. Um like a pathway versus a constraint. Um maybe it comes from my background is doing I did for three years did optimization mathematics as a you know to design things like power plant systems and stuff. And a constraint is something is a relationship between variables that you're trying to

adjust that is fixed. So either, you know, temperature is related to volume and there's a curve and then you have to travel along that curve or um or uh there's a constraint the you know something can't be greater than uh less than zero, say or something like that. Right. If you make the the smokestack higher with less concrete, it would be better, but it's not gonna stay up to the state. There is no smokestack. Yeah. It's a constraint. Yeah. And I think most of the things we ha we see in biology are things that shape the patterns of variation that selection can work on. They don't say it can't go there, but they affect the likelihood that new variants um are produced. And so sometimes it can be absolutely crucial, you know.

So do you guys know the Lensky experiments with with um E. coli? Yeah, like lots of different evolutionary trajectories, right? Yeah. So Lensky did experiments. I think he's got 14 replicants now 65,000 plus generations. Uh in the same it puts them in a new environment 65,000 generations ago and watches what happens. At first, um, they diverge. Some of them uh they go in the same average direction, they get bigger, the individual E. coli get bigger, uh, they do a bunch of other things, but some lines are doing better than other lines. So, and he can prove this because he he's got them in the freezer. He's got fossil E. coli in the freezer. And he creates competition experiments between a thousand generations ago and now.

And sure enough, the new ones always beat the old ones. Okay, so this is all great. And then after 20 or 30,000 generations, a lot of that variation disappears. And they are all pretty much on the same, not quite, but almost on the same trajectory. And now these are not eukaryotes, right? So they don't have full-blown recombination. They have some recombination. But so it takes a while. My picture of this and his picture is that it takes a while for you know the order in which mutations occur matters, right? Both because mutations potentiate other mutations and all this kind of stuff. But then at like 50,000, I don't know the exact number, but in about 50,000 generations, all of a sudden, one of the lines

just beats the crap out of everybody else. So the typical, you know, how this experiment works? He puts he puts in some glucose in the morning. The population expands to carrying capacity, then they shut down. The next morning gives them more glucose. And that goes on for 40,000 generations. And they get better at that environment. Now there's citrate in the medium, and it's very well known in E. coli biology that E. coli cannot digest citrate in the presence of oxygen. The enzyme that's necessary to do the job is inactivated in the presence of oxygen. This is something that people who do, It was thought to be true of all E. coli, but not at 50,000 generations. A series of neutral mutations had occurred, and then eventually, and those are

all improbable that they drift to high enough frequency, and then a new mutation that Coupled with those neutral ones, allowed the E. coli to digest citrate in the presence of oxygen. And all of a sudden, all bets are off. It completely annihilated the the previous um 50,000 generations. You know, in humans, that goes back, you know, to the Mesozoic practically, right? I don't know exactly how far, but but 60,000 times 10 is 600,000 gen uh uh no 600,000 years. Yeah, so it doesn't go back to the Mesozoic, but it goes back well before people, and um, so there is this kind of stuff you would never have predicted that on an adaptationist program if you took this species-specific property of E. coli, namely they can't digest citrate in the presence of oxygen as a fix as a

constraint, right? And um, and it wasn't a constraint, there just wasn't any variation in the necessary genes which gave rise to the necessary phenotypic variation for that to happen. And the series of mutations and events, namely drift, that had to occur for that to happen, um are very improbable. So I you know I think you know the adaptation is it hypothesis extremely powerful, but sometimes it gets you the wrong answer. Yeah. So what do you make of some people are really um kind of concerned about making equilibrium type arguments, which is kind of maybe another version of the phenotypic gambit? I don't know. Just that um even if we're adaptations, like the world is constantly changing and no time

more than today. Um, does this I think Pete has actually made some arguments to this effect and some of his students that like equilibrium thinking is just at odds with what we know about the human experience. Does this give us pause for making adaptationist kinds of we should think about the timescale on which variation takes place? And and I know Pete knows all about this, but he likes to argue. I have not argued with Pete about this particular item. Uh I mean there's variation on all kinds of timescales, right? And um and uh on some time scales, I think you know that technically, so if we have variation on um say we have an organism that has a one-year generation time and and we have temporal variation on 100-year timescales.

Um, it's never going to reach an equilibrium, but uh, but there'll be a stationary distribution of types, right? And um it'll respond to some temporal average or in spatial, you know, it's all these averages in population genetics. I think that's clearly of great importance to get the right timescale on which you think adaptation is responding. But it's not an imprinciple thing. It's just one of the things you have to take into account when it's, you know, it's there are trade-offs, right? And and um if only we knew. Well, I think, yeah, uh I I'm more of an optimist than you are, Christina. Yeah. I think so Pete and I have argued that agriculture didn't evolve uh during the Pleistocene because not because you couldn't grow plants, because you know, wheat was

growing somewhere for sure. It didn't just appear magically 10,000 years ago. Um uh but because the timescale of fluctuations during the last glacial was too short for the and I, you know, we would support that with so if you look at the spread of agriculture across the world, agriculture didn't spread, agriculturalists spread. So, um, and so populations which already had the norms, you know, women's roles, you have to be willing when you're an agriculturalist, you've got to be able to save stuff. And so sharing norms have to change. There's a whole bunch of stuff that has to change. And our argument would be that that doesn't change on 500-year timescales. And um, you know, um, now that might be wrong.

Um I have to say, archaeologists haven't taken it very seriously. Um, but uh but um that's a case where our picture of the temporal scale on which norms evolve is related to the temporal scale on which the environment's evolving. And if you you know, I mean I could go on and on, but but the the the environmental variation in the Pleistocene was staggering compared to the to the Holocene. I mean, um, you know, you could be a hunter-gatherer living in what would be now the south coast of France, and 500 years later you're living in northern Norway someplace without having moved at all. That was this that was the scale and and the amplitude and timescale of and now the place, the Holocene is this happy, warm, stable world.

Uh, and um, I really think we really ought to think about that. And and uh uh Eric Smith thinks. So I Pete and I published this paper, this shows you, you know, how you get hoisted on your own petard. Um uh we published this paper a couple years ago about large-scale cooperation in Holocene Hunter-gatherers. That I would argue shows there's plenty of large-scale cooperation in, and we argue, see, These ethnographic studies of the Kung and the Hadza and so on are not good models for the Pleistocene. That um that uh if you think about Pleistocene cooperation, you could you should think about large-scale cooperation amongst non-relatives. And Eric said, Oh yeah, but uh Pleistocene climate variation was so great that the social institutions necessary to

support large-scale cooperation couldn't have evolved, so they were just like the Hodsa. I thought that was mean. Full circle, yeah. At least he cited you, right? He was one of the reviewers. That's how I know. It wasn't that he wrote a paper about this. It's that so we we quoted him in the paper and and uh and we got permission to use his name because Eric is a very smart guy and thoughtful. But yeah. Rob, this is a slight change of or topic, just methodological for a second. I know uh like do you what is your opinion about sort of computer technology? Because a lot of the stuff we're talking about is also like there's you can do if you understand the concepts, you can do the math, but then there's also a lot of computational

modeling of things. Do you view the sort of analytic or you know math um thinking about ESSs versus modeling and simulations? Do you view that as still separate? And is there a cost of losing the first to the second with all the technology? Or what's your st what's your take on that? You know? I I I think they've always been complementary. Um I think they're the the you know the cheapness and speed of of computing has made agent based simulations better and more practical. Um I think that agent based simulations uh there's a temptation to over specify uh that people because it's easy, people have a tendency to to build what they think of as realism into the models. And you know, all models are wrong, some are useful.

That's a famous aphorism. And I think that done right, um analytic models and um Computer simulations should be used together to understand things, especially things where random factors are important, like climate change or small population effects, or any of those things. I will say that for kind of sociological reasons, I think, or maybe cultural evolutionary reasons, when I publish an analytical result, the the uh I put nowadays, I didn't used to, but all the math is in the, you know, the the uh what do they call that? The supplementary the supplementary material, but somebody can follow it. Yeah. That's not true. There's no, you know, people always say I put my code in the in you know the supplementary,

but it might as well be on the moon because we don't have any conventions about how to to to and I will tell you a story. Um uh I like stories, but um uh Herb Gintis and I, this 2001 paper that's been cited more than any other paper I've ever written, and I actually think is maybe not such a great paper, um where we looked at uh cultural group selection. Um uh Well, the details are important. But for reasons I don't really remember, Herb and I decided to do um uh uh clean room simulations. So we both wrote simulations, we clearly specified what the model should be like, and then we wrote the simulations and they did completely different things and um uh it took us a month of hard work to find out where they diverged and why they diverged and it was all

stupid reasons none of it had was conceptual and nobody does that, right? The only people who do that are people writing programs to fly airplanes and stuff like that. And um uh I think this is a big problem actually, that that the the reliability of analytical stuff is better than the reliability of simulations because you know I write simulations and I, you know, I've never done that since. It took and uh so I don't know how we're gonna solve that, uh, but we will, I think. We'll we'll come up with and it's gonna make simulations a lot harder, uh, I think uh to to to make sure they're right. And um you might be able to ask AI today what's the difference between those and herbs. Maybe maybe I I I ask AI to look at I I've been doing some simulation so

Moshi and I, you remember those conversations we had. Moshi and I got in this argument about um uh the the paper that minwa and i and christin and uh about continuous norms and uh so mo she said well blah blah blah blah and uh i couldn't the um the uh programming that minwa had written couldn't be modified very easily to to address most these questions so i rewrote an agent based model which fortunately produced the same results that Benoit's produced, um, and was way faster, and so I'd forced Benoit to do all this work because I thought the other way it'd be faster. Anyway, uh and so then I I thought, well, I should ask Chat GPT to look at this code, and and and and it had all kinds of stupid suggestions.

Uh uh, so I I this was now t how long ago was it that we were arguing with Moshi? Two or three years ago, something like that. Two years ago. Yeah. Uh and it may be that it's a lot better. I mean, they're making and I know that from my daughter that that it is getting better. So maybe it would work now. But then it just had uh I thought it it it it made a bunch of suggestions that would have made the code five percent faster and a thousand percent harder to understand what it did. And uh um so anyway, that's my anecdote about ChatGPT. It has no conceptual understanding. Yeah, just do you think that's Yeah, it doesn't it at least then it didn't care about how expressive the code was. Right. Yeah.

Do do you think we ought to be using more just basic analytic models, basic algebra relative to agent based simulations? Is that part of the the argument you're making? That that that way of thinking is kind of underplayed? It's harder and um uh I think, yeah, I do think it's not enough of it being done. And I think part of the problem is, I mean, this is another cultural evolutionary thing. The people who do it, analytical work, are mainly physicists and mathematicians that are looking for another job. And they place a big store on the you know my equations are longer than your equations kind of competition. And uh and so this is really clear in reciprocity theory. So um Rus I I just Sarah and I have just written a review of

reciprocity theory for um for um ticks. And um I would say since 2005, maybe somewhere in there, 95% of modeling and reciprocity is responding to previous models of reciprocity. And almost none of it is in response to questions about observed behavior. And that's because I work with a mathematician, Bertha Schoenmann, who was a wonderful person and a good colleague, but too sensitive to work in the evolutionary biology world. He quit because we were so mean. Reviewers were so mean. Anyway, uh, he said mathematicians, to be a successful mathematician, you have to find a problem that is not too easy, so anybody could do it, and not so hard, so you can't do it. But this sweet spot in between is something you can make progress on.

There's a lot of interesting developments, and that's what reciprocity theory is. It's a really nice problem, a lot of possibilities, and I think mainly a waste of time. Uh um uh and this is uh oh what few friends I have left in that field I'm not gonna have any more after we publish this paper. But um that's why John Minor Smith is my my intellectual hero. Um he never did anything complicated. Yeah. Look at the f the classic, you know, Hamilton's rule, the classic Trevor's paper. This is all this is just basically has no math in it. But but there's a little bit of a little bit of it. But yeah, I I well he he says Bill Hamilton told me that that you could represent this as a prisoner's dilemma.

Here's what Hamilton said. I just you know I've read that paper recently so I'm it's easy for me to be an expert here. But but um uh uh and that paper is full of bad confusions, the Tververs paper. But uh you know, he he well, I won't go into that, but but you know we should have a two hour episode about Trivers. He's one of our you know powerful ancestors, but he's not a clear thinker. He he's uh he's uh extremely brilliant, intuitive thinker, but you you gotta check, right? I mean um you know the key is to find simple enough representations of some problem that you can make analytical progress. And there are some problems you just can't do that way. I mean, you know, uh anything involving random drift-like features.

I mean, there is analytical stuff, but it's hopelessly complicated and it can't do anything. Well, there's lots of interesting stuff it can't do very easily. Uh Anything, any model in which selection varies in time or space, and it isn't white. So if there's any correlations in time and space, there's no analytical method to deal with that. That's completely opaque to analytical approaches. And it's quite easy to deal with. John Gillespie did a lot of work on that. And so, and that's obviously a question of importance. So we ought to do a lot of simulations. but if we can do the analytical stuff, it's very powerful. It gives you intuitions that are hard to get out of the simulations. You can get them, but it's harder because the equations talk to you.

You know, they when you look at the equations, they tell you things without actually having to solve them. And um And as yet, I think we'll fix this, but as yet, our simulation tools don't do this. Um I've been working with a couple of Spaniards uh uh uh economists who do simulations of repeated prisoners' dilemma of all things, but I just got done criticizing. And um they use this thing that's often thought of as kind of a child's play programming language, net logo. And um I'm really impressed to the extent to which they're able to get intuitions out of the way how easy it is. It's very slow and a kind of stupid language and as a computer science kind of project. But in terms of teaching stuff, I'm very impressed.

I'm gonna try to learn it. And anyway, so I think this is technological, a lot of it. We just haven't we haven't been doing it long enough to to be good at it. And um the the Asian-based simulation says, But the idea is that uh the anal the analysis so far or the formulas are you're forced to know what your the concepts and the relationships in a way that you could sort of be agnostic um about in a simulation. Like you might run a simulation where like, well, yeah, I don't know what that I don't know why, I don't know what the relationship is. I just know I got an outcome. And I don't really know what all the things that I fit into what mattered or didn't. It's just in in compared to the analysis or the formula where or the analytic math, you

have to know what the entity is and what the relationships are, or otherwise you're not able to do that. Oh, I I I disagree with that. Okay, yeah. Asian-based simulation. So, in an analytical model, typically you've got a bunch of state variables, you know, frequencies of genes or whatever it is. And you write down a dynamical system in which you posit relationships based on some in my way of thinking, and Christina was forced to go through all this. In my class, you write down a life cycle and you ask what happens to individuals, and you and then you use the law of large numbers to then ask to create relationships for the state variables. Um I think agent-based simulations are exactly the same in the sense you have to

write down a life cycle, you have to write down state variables, but now the state variables aren't these aggregate ones, they're ones at the individual level, you know, what it knows, how big it is, whatever it is. And so your space of possibilities is much bigger. But I think in at least the way I think about things, uh there's a quantitative difference between them, but conceptually they're exactly the same. There's nothing uh you have to specify ahead of time what the possibilities are. Uh you can't have unknown. And I there was a physicist at S of I when I was there who went on and on about what was wrong with evolutionary theory, is that it specified the possibilities in advance, and evolution really didn't do that.

It could go, and I think this is really an argument about how big the space is. And if the space gets big enough, then um yeah, that lends itself to I think I have seen agent-based models that don't give a good intuition at the end, even in the article of or have I I have seen articles where they don't give a good intuition of why it resulted the work that they did. And I do think that's rare in analytical models because I mean I think it could still happen. It happens, but it's much I agree, it's much rarer. It it it um there's like a they because part of the process of publishing the analytical model is like walking you through why the next thing right and and and also the analytical model because the intern internal works of the um of

the simulation model aren't visible to you in the same way, uh it's much harder to figure out what's happening. And um and I think we need to do I mean we we need to do a lot more exp of experimentation with with agent based models you know go in and do experiments look at intermediate values uh and I you know my bet is that over time referees and the scientific process will force people to do that. Uh Now I teach a version of that class, Rob T. Oh, do you? But I think that most of them don't want to be modelers. And so mo a lot of the time is spent just like so their final project is reading a model and making sure that they can understand why the results are the way that they are. It could be a simulation, it could be a mathematical one.

Um, because that's what I think a lot of us well, a lot of the evolutionary social scientists who are not going to be modelers themselves still need that practice to be able to read that literature and understand why the results turn out that way, as opposed to take it for granted that there's going to be this relationship. I think that's actually led to a lot of confusion or taking at face value um kind of conclusions. Yeah. Without thinking about the conditions under which or the assumptions that allow those patterns to arise. Yeah. I think the I mean this is a problem with not just evolutionary social science but evolutionary biology more generally is that it's not a norm that practitioners understand the mathematical

theory. Um and um it's not a norm that mathematical theorists are well versed in the empirical facts. And I mean, so if you interact with physicists or to a lesser extent with economists. Every empiricist knows the theory, at least at some level. I mean, really knows it in a in a substantial way. And um in economics, now economics has become very empirical. I mean, much more than it used to be. And you know, and it's deeply rooted in game theory. Now, my my own personal opinion is most of it is kind of crazy that it it's not very well coupled to anything about real humans, the game theory that, but anyway, be that as it may, when you talk to economists and you they're talking about econom uh I

go three times a year to this group of listen, I'm part of this network, which has got, you know, Samoglu and Robinson and Myerson and all these Nobel Prize winning economists and various students and stuff, and they really understand exactly what how the models work, what they say, and they're not doing modeling themselves at all, the people that I'm listening to. They're doing, you know, mainly these big regression kinds of studies. And um, so that's their version of empiricism. Um, and it is, and then if you listen to biologists, let's forget about evolution or self-c, but they kind of pick and choose theory the way they want. They don't really understand the models that well. you know there this obviously varies from person to person but um um

I think you know it's because when you teach this course you don't you can be a nobody's requiring this course whereas if if you're in physics or con economics you take a year in graduate school where they teach you all the same stuff you learned in undergraduate school all over again you know, theory of the firm, game theory, all this stuff. So they really got it deep. And um, you know, I think what a biologist would say, that's all a waste of time. We don't have enough theory to make that worthwhile. And I think there's some truth to that because the system hasn't developed, so that the theory and the empiricism is inextricably linked together. And um you know it's better integrated in economics the

Oh yeah, much better. But like so, but is it inherent to the body of theory that they've developed that it's no, it comes it's it's just cultural evolutionary. Yeah, right. It's it has to do with the way the institution evolved. Um the it was so theoretical when I took graduate economics in 1971, there was hardly any. I mean, empiricism was kind of like biology, this casual empiricism. And um then in the 90s uh and knots, uh, economics did this big shift to um so now hardly anybody gets a PhD um doing theory. The way you get a PhD is is, you know, it's like a biologist. You find some system that allows you to to test something, but you do that having you're absolutely deeply knowledgeable about game theory, but not game theory the way

we do it, game theory the way economists do it, which I think is, well, you don't care what I think about it, but it it's kind of yeah it's you know wacky basic. I shouldn't say that on a podcast. It's a technical term. Yeah. You know, I mean their equilibrium concepts are not evolutionary. They're about you think that I think that you think that I think uh and um uh and they're deeply committed to those. And if you uh you know, I go to these meetings and I voice mild skepticism in people and they're very very ethnocentric about economics. They don't think the rest of the social sciences is worth listening to, except history, maybe hardly at all. And um, but you know I I figure I'm doing missionary work on yeah and uh

fighting the good fight, yeah. You know, missionaries end up in the stewpot sometimes. Uh yeah, but I think I think the connection, I mean theory, I think theory to sort because we're wrapping up here, theory and empirics, I think, is a theme of sort of Rob, your contribution, and I think all the evolutionary sciences is that we've sort of, you know, for a while there was a lot of theory, not a lot of empirical work. Maybe we've swung to there's lots of empirical work, but not enough theory. But I think, I don't know, I mean, I think uh um I'm I'm at least heartened that we're we compared to a lot of human psychology, for example, and and uh I'm I'm speaking as a psychologist, yeah, yeah. Um, you know, there's a lot more theory we have at our disposal as a fish and and a lot of

psychologists per se. Yeah, I think I mean Joe and Michael have written this paper about that and yeah and uh when I interact with the social psychologists here, Doug Kenrick and and uh um oh gosh. Anyway, um and Steve Newberg. Uh yeah, really smart, accomplished people. Yeah. But they they would do better if they had more theory. Yeah, I think. Yeah. Yeah. Different histories. Yeah. Different so as you said, different, different different institutions. Different institutional selection, different histories. Absolutely. Yeah. Um uh Christina, do you have any uh final questions? Uh oh, that's a really tough spot to put. Yeah. I mean we can always ask Rob if we should have asked him anything. That also is a tough before.

I wanted to ask if there's anything that you've changed your mind about like over the last several decades. Um maybe based on the empirics or maybe better theories. Yeah, uh I used to be more gung-ho about cultural group selection than I am now. Um I'm more aware of the empirical um I mean a lot of the criticism of cultural group selection has kind of been in principle group selection can't work and that's wrong, right, for sure. But the problem is there are well, first of all, I worry a lot. I have been worried ever since 1985 about how fast it is and can it explain enough? Uh you know, it's a lot of norms we've got evolved, and is there enough cultural group selection? And um, And I worry about that actually.

And I have come to think that within group processes have got to be more important, both based on that and based on lots of empirical examples, which just there's no there's no group selection involved, and yet there's lots of change. I am bothered by the fact that I can't think of a good theory. I I think the bargaining theories don't make sense because, or at least they can't explain the variation we see, because um the scale on which I mean small scale people can bargain on the scale of a few thousand people, maybe, and we see norms on the scale of continents and and so there has to be something else that causes successful norms to spread from one group to another. It can't all be within group bargaining.

And I've got some ideas about that. But and Sarah has got some ideas about that. And I'm less convinced about conformism than I used to be as a learning strategy. Um is that because there are better ones out like basically we're gonna be able to do that. No, just because uh because the the the the data are ambiguous is what I would say mixed. Um uh the data for other animals surprisingly stronger are much stronger yeah so these wonderful experiments that Lucy Applin has done uh on bird learning, or you know, they're they they are conformists for sure. Um and interestingly, so the the the so a kind of psychology you might think, well, the number of instances is what people would respond to. But the theory tells you it's the number of individuals, not the number of instances,

because that's well because that's what generates adaptive information and sure enough those birds don't care about instances they care about the number of individuals and can I can I put a pause and just say something that is like common knowledge according to like the rest of the social sciences if you repeat something more people will believe it. Yeah and that is that doesn't make sense to me like why but what are the what is the radical side but is the empirical side true As far as I'm aware, at least in humans, the empirical side hasn't been holding up on that. This is what they call it. Yeah. Yeah. And uh I think they need a theory to tell them what you know what kinds of repeats are important.

And repeats across individuals are important. Repeats within individuals will matter in an environment which is changing on time scales that are fast enough. But anyway, um, so what else have I changed my mind about? Um and just to be clear, the the um slight increased skepticism about cultural group selection is just that it doesn't account for as many norm changes as you might have thought that they did because that um change is happening too quickly, culture change is happening too quickly. Too quickly. And you know, so the shift in norms about tobacco smoking in the US. Right. No group selection there. There, you know, it's, you know. They're running migrants to like the no smoking zone. Right.

Right. It's it's it's it it's not that. Um and um uh now, well, I don't want to go in all the details, but this is an area which I thought when I first started, I thought I had the answer. Now I think it's part of the answer. Uh how big a part? I don't know. Um uh uh Joe gets really mad when I say that. But um uh at least I think he does. Um I mean it could be faster. You don't want to hear all this. It might have mattered more historically than it does now, like when there was so much lots of sort of variation. Yeah. Well, I think the main form is gonna be differential spread. Yeah. So I groups imitating successful other groups, individuals in imitating people and successful neighbors. But I still don't think that explains a lot of stuff.

And um I don't know. I can't think of anything else off the top of my head. I've been right about so many things. You can't show that you're a good scientist if you're just right all the way. I have to I have to think of something. But I do think I mean Rob, just to say like as we're closing up too, like I do appreciate that, you know, as a student of John Alitas, like you've been very gracious over the years. And and I think talking about the evolved psychology explicitly, and I do think that you are part of the reason why for people like Christina and David, that the the the gap between sort of cultural evolution and evpsych, uh at least in principle, and maybe a lot of times in practice is very narrow and and and and nowadays

this I don't even think most people I don't even I don't know. I mean I'm in my experience it's it's more in Christina language sort of people's uh um emphasis in terms of their methods, less thus than their sort of deep commitments um you know where I think somebody who's an evolutionary psychologist like yeah there's cultural evolution and somebody who's cultural evolutionist like oh yeah there's evolved psychology I may not use it in my model but you know that yeah yeah I unfortunately have another thing that I need to get to yeah so um but yeah it was this was great thank you Rob thank you for my pleasure yeah this was a lot of fun yeah thank you you never know what to say for the outro Thanks for listening.

Yeah, this was great. Uh everybody have a good week. You know, do the usual Patreon um show. Patreon, social media, kind review, you know the drill. Yep. We should get t shirts, David. T shirts, fanny packs. Can I say our logo? I don't love our logo. In terms of like I I like our logo for the purposes of a podcast, but I don't know if I would want the brain on a shirt for me. What do you think? Hmm. Yeah, I don't know. I don't really have any aesthetic taste or fashion sensibility. Here's my vision of a t-shirt. A black t-shirt that says nothing except the podcast in parentheses. Oh, that like kind of a minimalist direction. It's like you gotta be on the end. It's sort of like you know, bank.

Ah, sort of small small dino in covert signal. Exactly. Oh, okay. I like that. Yeah. All right. Well, maybe that's what we'll do. All right. Yeah. Cool. Well, we can't do it w unless you um support us. Yeah. And, you know, maybe give us some some money on Patreon for the t shirts. If you if you run a a t shirt concern and have the ability to silk screen um, you know, however many of those, let us know. Yeah. Totally. Okay. All right. See you next week. Bye. Have a good week, everybody.