Today, I have the pleasure of chatting with Joseph Henrich, who is a professor of human evolutionary biology at Harvard University and an author of two of my favorite books, The Weirdest People in the World and before that, The Secret of Our Success. And I was just mentioning to you that I remember reading this many many years ago when I was in college, and at the time, I didn't think I would get a chance to ask you questions about it. But the most proximal reason I wanted to interview you is, I recently had your colleague, David Reich, on and we were discussing certain things in the record of human history where he said, 'Eventually, you're just gonna have to have Joseph Henrich on and ask him these questions, because he's the one who would know.' So let me ask you one of the questions which I was super intrigued by which he raised, and we didn't come up with an answer to. So one of the things he's discovered through his genetic evidence is that 70,000 years ago across Eurasia, there's so many different human species, from the Denisovans to the Neanderthals to the Hobbits, and then apparently, there's this one group, which was potentially the size of 1 to 10,000 people in the Near East, which subsequently explodes, and now everybody who's descended from Eurasia descends from this one group. And so I guess the question is like, what happened? What did they figure out? A typical assumption when people think about this, if you put it in the Paleolithic, they assume that it has to do with some kind of genetic changes. Now, Reich's lab, there's no obviously big changes in the DNA, so it's a little bit of a puzzle. Neanderthals, for example, had larger brains, and in primates larger brains usually go along with more computational abilities, more ability to solve problems. So the expanding variant out of the Middle East, out of Africa, might've actually been less able at an individual level to process information. But if you look back over the more recent period of human history, you can see that it's a story of expansions of different populations. So for example, in Africa, we have the Bantu expansion about 5,000 years ago, which actually eliminates a whole bunch of hunter-gatherer populations that previously existed in Africa. We have the remnant populations in parts of the Congo, in the Kalahari, in the Hadza, for example, in Tanzania. If you look at the Austronesian expansion, so that's the peopling of the Pacific, that was the expansion of one group of people at the expense of others, and of course, the Neolithic expansion into Europe is another example. So really human history is a story of these different expansions. And it could be that this expansion across Eurasia, which then led to interbreeding, so we know it's the same species. Humans interbred with Denisovans and Neanderthals, as well as probably other species- there's a ghost species in there. This could be just institutional changes, so if you have institutions, for example, that interconnect your population, you can maintain more sophisticated technology. And some paleoanthropologists, for example, have speculated- with some evidence- that the expanding populations had projectile weapons, so bows and arrows. And humans have periodically gained and lost bows and arrows in different parts of the world. So in Australia, for example, bows and arrows are never invented. In the New World, populations probably didn't have bows and arrows, but then later develop bows and arrows. It's also really interesting how some technologies you would just think of as extremely… I don't know what the word is, but the new world, like not having the wheel or something. I guess it kinda makes sense with no domesticated animals, but again, it's like such a… Right. Although the New World, everybody has dogs, and you can pull carts with dogs. So I've never really bought that, and of course, you can use llamas in the New World to pull carts as well. People do that today. Yeah, so what's your explanation for why there's no wheels in the New World?
So there were wheels on Mayan carts or on Mayan toys. My explanation is just the collective brain. So almost every single first invention of something big that we think is important for humans was invented in Eurasia. And Eurasia, as Jared Diamond famously pointed out, building on other people's work, it's the largest continent by far. It has the biggest population. It's also oriented along an east-west axis, which allows ideas and people to more easily flow. And there's a belt, which the historian Ian Morris calls the Lucky Latitudes, which runs from basically southern China all the way through to the Mediterranean. And ideas are just flowing back and forth there, across the center of Eurasia. But you also ended up with more complex state bureaucracies and the kinds of things that allow you to organize and move people around and whatnot.
And what's the explanation for why the collective brain leads to state capacity? Or is it the other way around?
Well, you can think of institutions that eventually lead to state capacity as just part of the innovative process of the collective brain. So if you have more groups experimenting with more different ways of governing groups of people, gradually, you get the accumulation of the pieces that you can put together into different kinds of states.
Got it. Okay, so going back to what happened 70,000 years ago, is the basic answer like, it could be something like bows, but we don't know exactly what it was? Or is it-
Yeah. We definitely don't know exactly what it was. So we know that this population expanded, and there does seem to be some tool indications to suggest more complex technology. Probably, technology usually goes along with social organization. So for example, if you look at Australia, which is a continent of hunter-gatherers, there's an expansion about 6,000 years ago out of northern Australia which eventually takes up seven-eighths of the continent, and they had a new social organization, including rules about who you marry. You had linguistic exogamy, and rituals that interconnected populations. So rather than having local rituals and local myths, many communities would get together periodically to initiate the young men, and this would help bond that whole group. There'd be an exchange of technology, and teaching that goes on at these… they'd spent a few months in the same place so there was a lot of time for transmission.
And then in terms of mechanism, so, if it's the case that you have these sort of convalescing waves of expansion, and David Reich's lab's evidence suggests that this expansion was quite violent, based on whether the genes are passed down through the maternal line or the paternal line. When you think about the mechanism in which technologies develop or these social institutions develop, how much of it is like, look, there's all these different groups that are trying different things, and one of them maybe figures something out, and then they just kind of explode? And how much of it is that within each group, they are experiencing sort of accumulations of learning over time, and it's not necessarily a selective process, it's more of a sort of accumulative process?
Well eventually the groups have to meet, and they're gonna compete over territories, and a bunch of different things can occur. So groups can copy each other. So we know that from the ethnographic record and historical cases, sometimes a group will say, 'Oh, those guys have really good technology tools.' Maybe they'll get some migrants, or something like that, and then they can adopt the practices. So that definitely happens. But there's also plenty of evidence of violent conflict. And the Reich labs evidence and lots of other ancient DNA suggests that there are these dead-end genetic lineages. So, I mean, the Neanderthals are a dead end in a sense, although we interbred with them, so they're in us in some sense, but they don't have their own pure lineage or anything like that.
And if you had to guess, whenever this big wave happens, is it more of a sort of concrete technology? I mean, especially if you consider the range of expansion that can often happen, right? It's like literally that same group goes from Siberia to England. It's hard to imagine it's a single technology lets you explore this wide range. But it's also the idea that some cultural artifact is enough that it gets transmitted over tens of thousands of years and that's what gives you the edge. I'm curious how you think about, what could possibly be this driving engine?
Well the way I describe it in The Secret is that it's a package of things. So another good example would be the Inuit expansion out of the north slope of Alaska. And they expand all the way across the Arctic and eventually get to Greenland. And they have a whole package of social practices which helps keep them interconnected, and then they have bows and arrows, which the group they are exterminating as they go along, the Dorset, doesn't have. They have dogs and sleds. They have, along the coast they have boats, so they're doing whaling. So there's a whole package that puts together that allows them to out-compete and eventually exterminate the Dorset. And one of the things that happens, though, is the Dorset probably had better technology, but they expanded, they spread out, their languages diversified, they lost contact, and they began losing technology. So you wanna see this as a dynamic pulse. There were probably expansions and then collapses, another expansion, another collapse, right? It's not one giant long march to victory. And then this process, which has happened many times where the population gets cut off or something.
When you say it's a sort of cycle, is there some reason why, over time, that knowledge gets fragmented and breaks apart and populations disperse?
Yeah, I think there's a cultural evolutionary dynamic that's part of this, because languages will naturally diversify and then as they diversify, there's less contact. People sometimes get inclined to marry endogamously, and especially if there's enough people around locally, why go all the way over there? And those people are getting more culturally different, so they're seeming a little bit like outsiders… So the tough part that humans have always had is to stay unified because of the natural effect of geography and learning locally is gonna tend to fragment us.
In the Secret, you described this interesting startup problem where if you don't have that much accumulated cultural knowledge, developing the ability to do social learning isn't as valuable. But if you don't have the ability to do social learning, you don't have that much accumulated cultural knowledge in your tribe or group. So how is this problem solved?
Yeah. So before I get to solving the problem, I just want to sketch for the listeners that the question is, why is this cumulative cultural evolutionary process that is so important for humans relatively uncommon in the natural world? It seems like just our lineage. I mean, there were a bunch of split-off lineages, but now it's just us. So to understand that is this idea that you just mentioned, where you're imagining an increase in brain tissue that's gonna be costly, and I can put that towards individually figuring the problem out for myself, or I can put it into learning from others. And in a world without very much cumulative culture, there's not gonna be very much useful information in the minds of everybody else so I should use that brain tissue for individually solving problems. And so it's hard to get this runoff where their brains get bigger for the purposes of learning from others. And then the question is, how do you get past that valley? So the case I make in Secret is that, say, three million years ago, two million years ago, there were several factors that came together. The first factor is the rate of change of environments. So you get this increase in the fluctuation of environments, so you're getting more environmental changes. And in cultural evolution, a lot of theory shows that there's a certain rate of change which is favorable to cultural evolution. It's gotta be slow enough so that the information of your parents and the previous generation is useful, but not so slow that you might as well just encode it in the genes. So that's one. Second thing is, we're a ground-dwelling ape, which means we have hands like chimpanzees and gorillas, and we can potentially use tools and whatnot. But unlike them, our ancestors may have been savanna-dwelling apes, which meant we may have lived in large groups. So in mammals, mammals live in larger groups when they have to deal with predators and the predator guild in Africa at that point was quite thick. There were a lot of deadly predators. So paleo-anthropologists think that our ancestors may have lived in large savanna-dwelling apes. And if you have a lot of individuals, if the culture is sparse, the bigger the group, the more chance that there's someone doing something useful in the larger group. And so that means it's easier to get across the threshold. So those are three of the main factors that might have allowed our lineage, as opposed to all the other lineages around, to cross this. We're already a big-brained primate, we had hands, we're living in these large groups on the savanna, and the climate changed during this period, so as to make us, yeah.
And how big were these groups?
Well, I mean, nobody's really sure, but maybe a few hundred individuals.
Okay. And before the agricultural revolution, was there still this transmission of information across different groups?
Yeah. So lots of different evidence suggests that groups were moving trade goods. So well back into the Paleolithic we see trade. Often we see some genetic transmission. Right, the expansions and so forth. Yes. And so, talking about the expansion, that's something where the ancient DNA is useful because the Neanderthals in Europe, the DNA suggests they lived in very small groups. But the DNA of the expanding groups suggests a larger population. So those would've been two different collective brains there as well.
So in The Secret, you discuss a lot of these lost European explorers with modern technologies as of at least a couple centuries ago encountering peoples who have for tens of thousands of years discovered ways of hunting and processing foods and so forth that, without which even these people with modern technology will starve. And as I was reading that I was wondering: I'm not sure how I understand the process by which, if there's a 10-step process to making sure this bean is actually nutritious, and without any one of those steps, you might poison yourself or something. And at no point do you understand why this process works. You don't have a scientific explanation. How do you even learn that in the first place?
Right. So one of the things we know, even in young children there's a tendency to preferentially learn from healthier, more successful individuals. So if you're processing it better- so something like bitter cassava, which has cyanide in it. If you just eat bitter cassava, it won't taste great. So if you then rinse it somewhat, it'll taste better and maybe you could eat it, but you're going to accumulate cyanide over the long run. So it doesn't kill you right away. But if you do this whole long process that the populations in South America developed, then you're totally fine, you never get any accumulation. So you can imagine that initially this is gonna be very strong and people are gonna sort of do sensible things… but then it gets a little more mysterious. And we know this because bitter cassava gets transported to Africa, and Africans immediately begin eating it improperly processed and getting goitre and the cyanide processing that goes along with it. So then that's gonna be a slow evolution where groups that do this are gonna be more successful and individual families are gonna be more successful. So, for example, you might have a household where they process the cassava more seriously than another family, and they're gonna have more kids and they're gonna be like, 'Oh, that family's really good.' And then people copy what they do in all kinds of ways, but one of them could be copying recipes.
Hmm. I guess it depends on the mechanism of selection here, because when you consider the different ways in which two different individuals might be different or two different households or even two different groups, I guess it makes sense why cyanide poisoning is such a deleterious effect that it is a noticeable or quite a strong signal. But I think you discussed some other ideas in The Secret where it's like, the sort of spices in a region sort of match the antimicrobial properties or the antifungal properties you need to stay, I guess, clean or whatever in that particular region. But it sounds like a small effect, and how could such a small effect actually create a strong enough signal that when you're deciding who to copy, you notice that this family is healthier because they spice their food in a certain way? Or this group takes over the area because they've…
Yeah, I mean, it has to be a big enough effect to matter, but I think if you go back to a world where there's a lot of improperly processed meat, people don't have refrigerators, and the leading cause of death in children is diarrhea. People carry high pathogen loads. If you can knock that pathogen load down, we know from modern research if you wanna make people healthier and even smarter, right? IQ goes up if you knock the pathogen load down.
Got it. So this process of cultural accumulation you're talking about: you think it is not strong enough to pick up minor increases in fitness and it actually has to be quite a significant thing for it to…
I think it operates a lot like natural selection, in the sense that natural selection will pick up tiny things if you give it long enough. Cultural evolution will do the same thing if you give it long enough, because just small differences in who you're paying attention to will affect things, but it might take 1,000 years as opposed to decades, right? But we know culture can spread adaptive traits super quickly if it's a really big effect.
Yeah. So the situation in which our ancestors found themselves, in some ways it's sort of like epistemic hell, in the sense of you don't know why certain things are working, but you do know that if you break with tradition, you might just doom yourself and your family. And that maybe, as you discuss, causes these religious beliefs and taboos and mystical understandings of the world to rise, where you just think like, 'Look, you're gonna burn in hell if you don't do this 10-step process for refining your beans or something.' In some sense, this requires you to abdicate reason because you have to just be like, 'I don't understand this. this is the way it's been done, so we're gonna do it.' Basically: how much reason do you necessarily have to abdicate to survive in the ancestral environment?
I mean, one of the ways we research this is by going out to societies that make bows and arrows or have food taboos that protect them from dangerous marine toxins and ask them questions about why they do it and see if they understand and they don't understand the underlying causal stuff. Right. But then why do they say they do it? Well, a typical answer is, 'It's our custom.' or 'It's important to people around here to do it this way, so we do it this way.' So just Hadza bows, for example- I didn't do this research, Jacob Harris and Kim Hill and Rob Boyd did it- but they asked Hadza about their bows and about how they work and what the mechanics are, so they understood some stuff. So you use the bow and you get some mechanical understanding. But if you asked him, 'What if you used a different wood, different materials,' and they had never tried anything else but what they learned, how to make this bow. So they couldn't speak to a lot of that stuff. And the things about the compression of the wood is very important- didn't understand that.
Okay, so that's quite interesting, right? Because you would think that you have to transmit cultural knowledge over time, but you also need to experiment in order to innovate. But it sounds like because of the belief in these customs, you would be less inclined to innovate.
Right. And the thing is, once something gets good, doing it differently almost always makes it worse. And then there's also, some things are just different because people do it randomly different, like they make a mistake. So I think people often underestimate the power of error in generating novelty.
One question I have is why this process of cultural learning… So humans have extended childhoods, presumably to give us more time to accumulate culture, and then we live after menopause, presumably because older people, our grandparents, can teach us about the situation we find ourself in. And 18 years is such a long time, and when I think back to- I mean, obviously I didn't grow up in the ancestral environment, but when I think back to what I was doing as a teenager I don't think I was learning that much. I was just less productive for no obvious biological reason. So I guess I don't intuitively understand why this process of cultural learning takes decades, and why it can't happen more rapidly.
Well, you probably, as an adolescent, were in school, right? So you were probably accumulating some stuff in school- maybe. And here's an interesting fact about hunters. So anthropologists who studied hunters, hunter-gatherer societies in different places, and the physical peak that at least males have is in their early 20s, right? That's when they run the fastest. They got the best eyesight. But the best hunters in the community are 36 to 40, right? They're not as fast as those guys, but they just know, they know the track, they know the animals, they know exactly what to do in these different- And then hunting skill begins to decline because basically the physicality of things begins to catch up, and so there's this kind of cycle. And at 18 young hunters aren't even producing enough food to feed themselves. So it's not until they get into their 20s that they're actually in surplus and bringing food home for everybody else. And you need to know hundreds, at least, animals, you need to know animal behavior, you gotta be able to spot tracks and spoor, and we're just very knowledge-dependent in terms of our hunting and gathering.
Yeah. Given what you just said and also the experience of these European explorers suggests that you just gotta know a lot of shit to make it in any sort of environment on Earth. But then, there's all these other animals and they seem so dumb and they seem able to get by. So why did humans have such a hard time of it?
Yeah, well, so I think we offloaded a lot of stuff into culture. So in one of my Lost European Explorers, there's a case where they're in Australia and they have camels. And the camels escape, and now central Australia has lots of feral camels. So the camels survived the lost European explorer challenge, because they have innate instincts. They can smell water a mile away. They can detoxify foods in their own- they have a complex digestive system that detoxifies- we've lost all that, and we're worse than chimpanzees at detoxifying foods because we have all these cultural practices that do the work. So we've externalized detoxification and a lot of digestion, actually.
I had this independent researcher and internet writer called Gwern Branwen on my podcast a couple months ago, and we were discussing AI. And I asked him- so his theory is very much like the brain became bigger, more intelligence. And so then I asked him, 'Look, if it's this simple, why did it take so long for evolution to discover intelligence in the first place?' And he had this interesting answer, which is that in terms of the signal that evolution is giving you, there's a very narrow gap between skills that are so useful that they should just be distilled as an instinct into your genome, and then skills that are so worthless that are not worth learning in the first place. And so this narrow gap that's like, you need that generalization ability. It's not so primal that, you know, you're not gonna culturally learn hunger, it's just gonna be in your genome. I don't know if that sounds like an interesting explanation or helps explain anything.
Well in cultural evolutionary models, a typical thing would be to let genes compete with individual learning to compete with cultural learning. And it turns out the rate of change of the environment affects that. So if the environment is changing slowly, then you should put it all in the genes. And if it's changing at moderate speed, then culture is the best way to go, and if it's fast, then individual learning. And the idea, the individual learning is favored because if it's changing too quickly, the previous generation doesn't know anything worth knowing because the world you're dealing with is just so much different from their world. And so it's this intermediate range. So myself and others have argued that the increase in the frequency of change during the Plio-Pleistocene transition 2.5 million years ago is a change that increases the value of cultural transmission of learning from others. I'm not sure what your guest was thinking. I mean as our brains are not very good at solving problems, otherwise the lost European explorers could survive. And human brain size has been declining for the last 10,000 years. So we've actually been getting dumber. Fewer neurons, less computational power.
Why has brain size been declining?
Well, the collective brain argument suggests that at a certain size, you'll begin farming off specialists. So because there's a store of knowledge in the society, and we can all be generalists and learn how to do all the different skills. But at some point it makes efficiency sense for us to specialize in different skills. In order for that to be the case though, we have to have social agreements of some sort that allow us to trade or exchange things like that. So, but then once we're specializing, we don't necessarily need as large a brain and we, because we distribute the overall brain power amongst the society. So it could be that we're becoming more of a superorganism. And you see the same thing in ants. When ants get specialized occupational casts, their individual brains shrink.
Yeah. I think David Reich's lab had a result a month or two ago where they showed that the selective pressure on at least the European samples, which is the samples they studied, was that there's been selection for greater intelligence over the last 10,000 years. I don't know if you saw that or what you make of that?
Well, they didn't say anything about intelligence. They did use the polygenic score for education. But there was no education 8,000 years ago. Which is correlated, right? Yeah, it's correlated. But then the question is, we don't know what goes into that, right? Is that actually computational software? I mean, people do well in school because they stick to it and they can sit in the same place for long periods of time.
I guess it would be interesting for them to sort of deduct the docility hit polygenic score from the education, because we don't have a polygenic score for intelligence yet, right, so which is why you need some proxy.
Well there are IQs, so there are polygenic scores for IQ. I think they actually did that one as well, like you said, it's correlated with education. But the things that go into giving you an IQ, I mean, the correlation between brain size and IQ is only about, well, across populations it's .24, so it's not very big. The other thing is IQ is massively misunderstood, so the way to think about IQ, which has been going up over the 20th century, by quite a bit, so if you rescale modern scores to 1900, it's about 70, it's called the Flynn effect. I think that those are cognitive abilities for navigating the institutional world that we've constructed. And a huge mistake would be to assume that those are the right cognitive abilities for the next century. So it'll be a different constellation. We study herders and cognitive abilities of herders in northern Namibia, and if you're in northern Namibia, you gotta be able to move through the landscape, so being able to just pick a direction and know where you're going and not get lost is super important. So different suites of cognitive abilities are favored in different environments. This idea that there's this generalized thing applicable across all human environments just doesn't… I mean, education massively increases your IQ, right? If you're uneducated, you have a totally different IQ.
And then is the way in which your horsepower is directed, is that a thing that you think is basically set by the time you're an adult? Or, if somebody's 30 now and the AI thing is gonna happen next and they have to totally reorient away from knowledge work, is that a thing?
Well, I think it's a continuous scale. If you look at human brains, they're developing and continuing to add new connections and stuff, at least into the mid-20s. Now, there could be even more plasticity after that. Unlike chimps, we're still not totally myelinized for our whole lives. So there's definitely room. It's just there's less room.
The kind of social learning for which our learning biases are fit, right? Like where you pay attention to elders because they survived somehow and they've accumulated the knowledge from past generations, how much do you think that actually basically applies to the way in which the modern knowledge work economy accumulates knowledge? And how much do you think is just an artifact of the kind of environment our ancestors found themselves in? Right now we're in Silicon Valley, or in San Francisco, and it's very common here for a 20-something to make a new product or service which, without that much- they don't have that much context of how the world works, but they can make big, big innovations and big changes. But at the same time, people on average maybe are more productive in their 40s and 50s in terms of wages or something. So basically, this sort of social learning you're describing, how much does it actually describe the world as it exists today?
Yeah. And so, super important, so we'll take the patent database and if your same-sex parent- has to be same sex- patents in a particular domain, you're nine times more likely to patent in that same domain.
And how do you separate the genetic versus cultural effect there?
So these are very fine domains, so we're talking about, like, natural adhesives versus synthetic adhesives. So unless you think there's genes for that. And same thing with transistors and electronics, so very fine domains. And if you grow up in Silicon Valley, you're much more likely to patent, in general, but you're probably gonna patent in computers. But if you grow up in Boston, it's gonna be biotech. So having a father or mother who did biotech and then growing up in Boston, you're even more likely to patent in biotech. And this is true even if you move to New York. So if you look at people in New York who are from Silicon Valley and from Boston, the Bostoners are more likely to patent in biotech, and the Silicon Valley kids are more likely to patent in computing. So all the same rules apply.
Well, I'm not sure because maybe the location, you learn a lot from the environment. But the fact that it's just kids, and so, if you think these old rules of cultural accumulation and collective brains apply, you would think, 'Ah, you're 50 by the time you're writing your first useful line of Python code or something.' When in fact, a lot of these big innovations come from people who are much, much younger, before they should have accumulated much of the know-how that this theory implies.
So the model here is what to focus your efforts on, so it's the throwing model. So if you grow up in Silicon Valley, you focus your efforts on learning how to code or whatever. And so that means that's where you're likely to make the innovation.
Right. But in terms of, you know, when there's 2% growth a year and a lot of the technologies that are dominant in the economy today, or a lot of the industries, didn't even exist many generations ago. Basically, does that suggest this model of- should we just mistrust our instincts of who to give prestige to and what kinds of people we want to pay attention to, whether it's professors or elders or whatever?
Yeah, so that's definitely something I've thought about and I wrote about in Secret, which is that, as the rate of cultural change gets faster- and we sort of talked about this with environmental change- the value of older and older members of the previous generation declines because the world that they grew up in, and that they honed their skills to, is quite different from the current world. So you would expect the degree to which, I mean, optimally, you would look less far back or you would look to relatively younger individuals to get your inspiration from because the world they adapted to is closer to the world you're gonna need to adapt to.
Yeah. And speaking of Silicon Valley, let me ask you a little bit about AI. So one of the reasons to suspect some incredibly sharp discontinuity from the world as it exists today to a world with AIs. And by AI, I don't mean just, like, GPT-4, I mean, like, replacement at least for anything you can do on a computer screen, the AI can do. One of the reasons we expect this hard discontinuity is that they have potentially the step function increase in social learning and the ability to accumulate knowledge that maybe humans had, or the magnitude of which maybe humans had when, between them and non-human primates. And in particular, the fact that you can just copy everything you know. Like you don't have to teach a young person, right? The constraints of biology mean you can't just replicate brains. You have much more efficient communication. You don't have to communicate through words, you can just shoot your brain state across, the population size can grow arbitrarily large. So to the extent of, the collective brain is the size of the population and how interconnected it is, do you just expect we wouldn't even recognize the kind of world these AIs could make as a result of their cultural skills?
Yeah. No, I mean, I, I definitely think it's pretty interesting, and holds great potential for expanding the collective brain. There are little things in there which might make one worry. So if you study the history of innovation, you find out that, for example, serendipitous meetings are super important. There's a great paper on Silicon Valley showing that companies will cross-reference each other's patents more likely when the people at those companies tend to frequent the same coffee shops, and they track people on their cell phones and stuff to figure this out. So serendipitous meetings are important and improper copying. So a huge number of innovations are mistakes where somebody copied incorrectly and then got something better.
I read this interesting theory that maybe evolution designed transcription and translation to have more errors than it could otherwise have, just so that you can have this sparse reward when you're close to the right sequence.
Yeah, yeah. I think that's a very interesting area of research, and it makes good sense to me. I'm not sure of the current state of the evidence, but there are… Different parts of the genome are more or less susceptible to mutation, which is kind of interesting.
Yeah. So going back to AI, maybe then another way to phrase it is, look, you're talking about these serendipitous meetings where you can learn something another person knows. And the great advantage these AIs have is that they can sort of meet with everybody at once. Future versions of AIs, you could really imagine holding the whole internet in context, right? I mean, we'll be the equivalent of those people isolated in Tasmania according to the AIs, right? Because they just have everything in context. You can get a PhD in every single field, and you can amortize that across all your copies.
Yeah, so are you sort of banking on, in the next 10 years, you're just gonna be living in the singularity or something because of your belief in the value of cultural knowledge?
Yeah, I see there's various potentials, and I'm particularly interested in using AIs to augment problem-solving in human groups. So you can imagine getting the humans together because the humans have the big advantage of having stuff they care about, right? There's stuff they want to invent. So the AI is still a tool at some point. So I'm interested in that, but I'm interested in how these things like running out of training data is gonna be dealt with, the value of making mistakes and serendipity, if you get rid of all those things or how you're gonna reintroduce them, those kinds of things.
Yeah. I mean, it's quite funny because until recently, people were saying the big issue with LLMs is that they hallucinate and make mistakes. And at some level, hallucination is no different than creativity. Well, maybe there's a way to harness that, right? But maybe we just didn't know how to harness it.
That's right. What do you make of the idea that you could have AI firms or AI tribes, whatever way to think about it- is if the effective population size that can communicate with each other is such an important contributor to how much progress a group in history was able to make. If you could just literally run billions of AIs and they have this immediate ability to communicate with each other. And again, I'm not talking about current models, I'm talking about future, human equivalent. Basically I guess I'm just throwing out a bunch of different intuition pumps and I'm curious which one you find most promising or most interesting, or did you just find all of them not as convincing?
Yeah, no, I don't have strong opinions about any of this, but I do think that one thing in order to make all that work is, humans are constantly getting hit with shocks, right? So there's economic shocks, there's weather shocks, there's conflict with other groups, there's pandemics. And the shocks have big effects on how things go. They inject new information into the system. So I'd worry about a system that is too homogeneous and doesn't have enough noise adding shocks and new challenges and things like that. One of the things missing from our conversation is the kind of creativity that cultural evolution has figured out. So to give you an example, at some point in human history, religions invented big, powerful, moralizing gods. And this may have increased the people's ability to cooperate. So forget about the technological element. Some of the most important features of innovation over human history have been institutional and things that get people to cooperate. So in my work, I argue that one branch of Christianity resulted in the transformation of the families in European societies into small monogamous nuclear families. I'm not sure an AI would have thought of that. Cultural evolution thought of it because of how it affected how the societies operated, so it sorted this out over historical time.
Yeah. Can I play with that idea? Yeah. Because that's quite interesting. So again, I think this might even reinforce the advantages of AIs in this sense. So, to the extent that this sort of random fluke by the church led to this modernity and the great divergence or whatever, and it was a result of, there's a bunch of variation, and then you can select over some group that's doing the right thing. The advantage you have with AIs is that you can have much more high fidelity replication of culture and you can explore a wider range of potential cultures. Sorry, and it sounds really vague when you talk about AIs in this way. So what do I mean? One problem companies have today is that, suppose a company's working really well. Maybe it's early Apple, or early Tesla, or SpaceX or something. And suppose it has to do with the culture, the people, something, it's not clear how you replicate that culture, not only across different institutions, right? If I'm running a company, I don't know how to copy SpaceX. Not only can you not replicate it across institutions, you can't even replicate it across time. So over time, many institutions tend to decay, their culture fades as people leave or die or something. And then imagine if all of SpaceX, at least maybe at the time you thought it was the most effective, are just AIs where you know every single byte, and when you can make a copy of it 1,000 times, and you can put it against every single hardware problem we have in the world. And then you can, if you think there's another team that might have some different culture which is better, you can do the same thing with them. And culture here includes not only how they think about their work, but also even how does the board make decisions, right? Do they do this Monte Carlo tree simulation? And there's so many different things you could do here. So because of the wider range of possibilities you can explore and the fact that you can have higher fidelity transmission of cultural information, maybe the ability to do this random evolution also increases. But I'm curious to get your take on that.
Yeah, as a kind of broad sketch, I think that is pretty interesting. I worry about too high a fidelity replication just because it's important to take the details of historical context and time into account. So that same thing, if you fix it, it might not really work a decade later when everything else around it has changed, right? So it's kind of a moving target. But you could fix that just by having lots of different variants that are different versions of that. So yeah, that would be cool.
Sorry, that gives us a good opportunity to go into WEIRD. But before we get there, one more question about before the agricultural revolution. You know, obviously many groups around the world were different and many of those differences were probably inspired by the fact that they were living in different environments, so they needed to come up with different technologies and adaptations to survive best there. How much just random differences that had nothing to do with their environment do you expect there to have been, in terms of… I don't even know what the right category would be, but in the modern world, you might imagine something like, does a society have slavery or not? And maybe pre-modern societies all had slavery, so that's not the right way to think about variation, but that kind of…
Yep. So I think there's lots of reason to think there was lots of variation. And one of the ways that researchers study this is they look at ethological variables and they compare it to phylogenetic variables. And here they mean cultural phylogeny. So if your ancestral populations had matrilineal, matrilocal social organization, how likely are you to have it, controlling for ecology? And it turns out both of these things matter. People adapt to their ecology, but you can still see the signal of past society. So some degree of fidelity of transmission of social institutions, how we make our baskets, those kinds of things. There's lots of examples in the modern world, and we see this all over the place. So if you look at gender inequality in the modern world, you find that a history of the plow leads to greater gender inequality. So males had a particular advantage in using the plow because it requires upper body strength. This meant males became the dominant force in economic production at the household level. And that even today in populations where most people aren't farmers, this persists. So this is cultural persistence that has to do with whether you had the plow. So this is work done by Alberto Alesina and Nathan Nunn. A former postdoc of mine now at the Harvard Business School, Anke Becker, has done a similar thing with pastoralism. So if your ancestors were pastoralists, and pastoralists, for various reasons, have quite strong gender norms that persists into the modern world and still shapes, for example, female entrepreneurship.
Interesting. Yeah, and the reason I'm especially curious about this is because it informs the following question. If the Industrial Revolution didn't happen in Europe but started somewhere else, how different would the world look like today? So obviously you discussed the fact that breaking apart these kin ties was necessary for the Industrial Revolution, but to the extent that was necessary, whichever place had the Industrial Revolution first would have had that, right? But, I mean, separate from the technologies or cultural practices which were necessary for the Industrial Revolution in the first place, still how different would the world look? How much variation was possible given our level of technology?
Yeah, I have a lot of trouble trying to answer that because, I mean, China or some place in the Middle East might have been the obvious alternative place for the Industrial Revolution to happen. But I feel like you have to give those places a lot of stuff that developed only in Europe. So for example, universities begin spreading in the High Middle Ages. So you'd want them to have universities. You'd want them to have universal schooling, which began to spread and wasn't present in these places prior to that. So that begins to spread in the 16th, 17th century. And so by the time you add all this stuff, it basically starts to look a lot like Europe. And these are all things that are global now, right? So the universal schooling that we find around the world today, you know, begins with the Protestant Reformation in Germany and then later England. University's models are the European university, and globalized.
I guess one obviously very salient example of variance which might not have been replicated, but I'm curious if you think it might have been, is, it seems like the British Empire was the first major institution which decided that slavery is just morally wrong and we're gonna throw our weight around to eliminate it. And I don't know if you think that sort of naturally follows the development of social technologies that the Industrial Revolution would have brought about, but that seems super contingent. But I'm curious if you disagree.
Yeah. Well, so my story is that the rise of the Industrial Revolution in Europe has to do with the consolidation of Europe's collective brain. And one of the things that requires is trust in strangers, and at least the beginnings of moral universalism. And it's that moral universalism that eventually causes the British to say, 'We've got to stop with the slave trade thing.' It's a moral decision that they made because it's no longer consistent with the changing moral values over time.
Right, right. Okay, so we've been dancing around the thesis of your book following The Secret, which is The Weirdest People in the World. And before we really jump into it, maybe you can give me a summary of what the thesis there is.
Yeah. So the first observation is that there's a great deal of global psychological variation around the world. So European, American, Australian populations tend to be highly individualistic. They're inclined towards analytic thinking over holistic thinking. They have a lot of impersonal prosociality, so trust in strangers. They're against conformity, willingness to cooperate with strangers. So the question is, how can we explain the global variation in these features of psychology? And towards the end of the book, I actually connect these features of the psychology to economic differences, including the Industrial Revolution that happened in Europe, which reshapes the world. And the story is that the key event is the spread of a particular form of Christianity into Europe, where the Catholic Church- what becomes the Catholic Church- systematically dismantles the intensive kinship systems in Europe, leading to small monogamous nuclear families. And this transformation leads to the creation of new institutions. So by the high Middle Ages, you get the rise of guilds, which are voluntary groups of craftsmen and self-help societies, because people don't have their families to rely on. People begin moving around. There's occupational sorting into different occupations. You get urbanization rising. Charter towns are on the rise. Universities pop up. New kinds of monasteries pop up. And then Europe begins to urbanize, and you get new kinds of law that are based around the individual. Contract law. And then eventually this leads to a lot more innovation because ideas are flowing around Europe and then eventually the Industrial Revolution. So that's the argument in a nutshell.
Can you explain again what exactly the Church did which led to the kin-based existing system breaking down?
Yeah. So the Church outlaws polygyny, and so that stops elite males from having multiple wives and concubines and whatnot, and creating kind of a giant family through that. It outlaws cousin marriage going all the way out to sixth cousins at some point, and that included spiritual kin and other kinds of non-genetic relatives as well as the cousins. It frees up inheritance, so it has inheritance by testimony rather than normal patrilineal inheritance. And a simple example here is in most societies, you inherit access to land corporately, which means you and your brothers and stuff all own the land. And it might be your uncle is actually in charge of the land, your father's brother. And so you can't sell it, you can't move it around, and you're also tied to it. It's where your ancestors are buried, and so there's this big importance of land. So the Church allows people to give land to the Church, the Church becomes the largest landowner in Europe, because you can do it by testament. So those are just some of the examples of the ways it transforms the family structure, and eventually you get these monogamous nuclear families which are basically unheard of around the world, at least if you look at the anthropological record. And you can really see this when you can compare, individuals can move to European cities as individuals or nuclear families. In China when you move to the city, you maintain contacts with the folks back home in the village, and people flow back and forth and you get these little enclaves of different clans and stuff in the cities, the connections. And this is really important because your ancestors, and there's rituals that have to be done back in the home community. But Christianity does away with all those ancestor rituals.
Okay, great. Let's jump into it by starting before- much before- even the church. I wonder how much of the things that make Europe weird existed even in antiquity. If you read about how Roman society worked, or how these Greek polities worked, already you have an emphasis on nuclear families. You have these sort of universal norms around, 'Hey, we believe in republicanism,' or, 'We believe in democracy.' And the structure of the system matters more necessarily than… I guess at least before the empire, right? So yeah, was Europe already weird before the things that its church did?
Well, there were certainly some interesting things going on in Greece and Rome. But I don't think there's good evidence that you had the kinds of monogamous nuclear families that you would find later. I mean, even European law is built around patrilineage. So if your father's still alive, you are not a full citizen. You're in the pater house of these large families. Definitely intensive kinship, for sure, patrilineal, patrilocal. Women, of course, don't have any rights. And republicanism, but the formation of Rome is built around a series of elite families. So it's a clan operation, and they call it republican because the clans all have some say in what's going on. So people sometimes see representative government where it's not really individuals being represented, but families. And so this fools a lot of people into thinking there was a lot more individualistic voting and things like that, whereas there's actually no voting. So in Greece, in Athens, Athens is unique because it does a bunch of things in the laws of Solon, that break down the intensive kinship. So for example, in Greece, you get monogamy for the first time, and Athens is considered unusual. So males can only marry one Athenian woman, which has potentially positive effects among the competition among Athenian men, but they can have as many slave concubines as they want. So when Christianity spreads, it ends the whole slave concubine thing, which was also common in Rome, and that's another effect on this whole thing.
Yeah. But I guess the extent to which these practices were already formed hundreds or thousands of years before the church's intervention, maybe this suggests that Europe was already on this trajectory and the church didn't necessarily move the needle that much. Or what do you make of that thesis?
Well we know that the… in the book, I talk about data where we can look at contemporary kinship practices, and we can look at the number of centuries that that part of Europe was under the church… so we have a database of the diffusion of bishoprics, and there's a clear connection between the intensive kinship practices and the number of years under the church.
Hmm. And then if you think about what the church basically did, I think your work is often used to justify this idea of Chesterton's Fence, where if you don't necessarily understand a cultural practice, you should keep it around because… the stuff we were talking about, The Secret, where you don't understand why the 10 steps lead to the bean being edible, but you should trust the sort of wisdom of the ages. If you think about what the church did here, right? Like, isn't this sort of like a… not necessarily a justification, but at least an example of just breaking down Chesterton's Fence? The church doesn't really understand why these kin-based networks that have existed for thousands of years might have utility. It still just gets rid of all of them. And that results in this lottery ticket that leads to The Great Divergence. So is there evidence for anti-Chesterton's fence from the Weirdest People?
Sure. Sure. So what you're talking about is just the idea that culture has imbued institutions and various practices with a logic that we might not understand. So it's not calling for never changing the institutions. It's saying make sure you figure out the logic and the cost and benefits. So I was an expert witness in Canada for the attorney general of British Columbia, asked the Supreme Court of British Columbia, whether the statutes against polygyny were legal. And so my job was just to inform the court that polygyny has this unfortunate effect of the elite and high-status males tend to get a disproportionate share of the wives, and that creates this pool of low-status unmarried men. Now you can decide what you want to do with that. But you need to understand the kind of underlying social dynamics that you're gonna unleash if you legalize or decriminalize polygyny.
Right. But again, going back to the Church, the Church didn't understand the positive or negative effects they're gonna have, right? They just like, 'Let's rip the Band-Aid, let's see what happens.'
That's right. And it actually benefited the Church because it released people's responsibilities to their families and allowed them to migrate in and join the Church, and more heavily invest in the Church. And these later prohibitions against priests marrying and stuff was all an effort to get greater investment in the Church, because you weren't torn between helping your son and then investing in the Church.
Hmm. And then that end result which benefited the Church, was that their conscious intention in breaking apart these kin-based ties? Or was that just the accidental byproduct?
Yeah, I mean, in the record, I've never been able to find much evidence that they were thinking about the destruction of kinship ties. There is a great quote from Saint Augustine where he talks about the benefits of forcing people to marry more distantly. But, you know, this is something that was debated repeatedly in church councils all across Europe. And it doesn't seem to pop up very often.
And the Church doing this, for obviously selfish reasons, was that in any way related to why the Church spread through Europe in the first place? Or did it end up spreading for separate reasons and it won out over the other potential religious competitors for separate reasons? And basically, was this part of the selective mechanism which allowed the Catholic Church to become dominant in Europe in the first place?
Yeah, I think so, although it's hard to know. There was a lot of randomness going on in the diffusion of the Church. But also as the Church arrived, these places, over a period of time, became more successful. So you can see rising urbanization in the wake of the Church's arrival. That would have meant more trade, their citizens' rights began developing because they were trying to attract citizens to the towns. That would have given the Church more cachet, ability to move. There's also the appearance of these voluntary associations which are new kinds of monasteries. And so the monasteries begin spreading throughout Europe. But they're all linked in a network because, like the Cistercians, they're all connected and they have big meetings. So they're actually spreading a lot of knowledge.
around Europe as well. So that's part of this kind of collective brain story. And if you compare what's happening in Europe at this time to the rest of the world, so starting with China: in 1500, the population of England, where a couple centuries later the Industrial Revolution starts, is three million, and then in Ming dynasty China, it's somewhere between 100 million to 160 million. And if we take your previous perspective of the size of the collective brain really matters a lot, the size of the collective brain in China just seems so much bigger. So what is the best way to understand what went wrong here? Why weren't they able to use their…
