168 - Robin Dunbar: How Many People Can You Be Friends With? (REAIR)

32:02that's stayed 150 people that just seems to have been very stable uh forever probably um and that it seems to be completely cross-cultural and deep you know we can see good evidence for that number through historical time over the last several thousand years in fact um what is different and this really does make a big difference is the fact that our natural living arrangements have changed dramatically since the invention of the bicycle, as it's sometimes famously claimed as the most important thing in human evolution was the invention of the bicycle because it allowed people to move, right? So historically, until very, very recently, and to some extent this is still the case in many parts of the world, it'll be pretty much still the case, you know, in the sort of remoter corners of the U.S., up in the mountain communities or, you know, in the sort of deserts of Arizona and places where you've got quite small communities.

33:05The village of one to 200 people, which is the classic size of the villages, was the basic social grouping. That's who you saw most of the time. Okay, you know, occasionally people turned up from somewhere else, either demanding taxes from you or coming to raid you or just wandering through. But most of your life was involved with just this small group of people. And on top of that, because it was a kind of closed community, everybody shared the same 150. So there's your village of 150. You spend most of your time in it and everybody knows everybody else. OK, your grandmother is not the same as your friend Pete's grandmother.

33:49They happen to be sisters. You know, they're still different people. But nonetheless, everybody fits into your social world and everybody else's social world. And then what seems to have happened kind of really after the Industrial Revolution is that to some extent, I suppose, the agricultural revolution in the near living when people started living in in bigger and bigger towns and cities but what's kind of i think made the big difference was the invention of long distance travel so really actually the big watershed is probably the end of the second world war when cheap air travel and ship travel became widely available people moved much more than they had done previously.

34:35So what happens now is instead of your 150 people being, you know, literally in your block, they're scattered all over the place, you know, and classically so in the US, which has been a much more mobile society than perhaps certainly Europe or other parts of the world, at least until very recently, where, you know, okay, you grew up in Los Angeles, let's say, but your mother's sister and her family live in Florida and granny and grandpa live in New Hampshire, for goodness sakes. So you don't get to see them very often. These are mythical creatures.

35:12Adults keep mentioning once in a while you get to see them. So your kind of life is scattered. And I think what's especially happened now in the recent decades is that then your people are so mobile. So, okay, historically, people have always moved. That's the history of the US, after all. You're all immigrants from other parts of the world. You arrive and bed in somewhere as best you can among strangers. But what happens in those contexts, as happened in the context of cities, where cities have always attracted people to come in from the rural areas outside because of job opportunities, what they've done is recreate local communities on the street where they live.

36:00So if you look at kind of what happened historically to the waves of immigrants coming in from to the US in the 19th century in particular, you know, they kind of built communities on the streets. And that's hard work because these are all strangers and you don't have a kind of natural framework provided by family to provide a structure to that. But, you know, it kind of worked OK. But I think what's happened now with much greater opportunity for travel, particularly for work, go away for college and all these kind of things that we do, is your life ends up as a kind of trajectory around the country.

36:38You know, so quite literally born and grew up in San Francisco, but you decide to go to the University of Utah for college because that sounds interesting or to get away from your parents or whatever these reasons that motivate people to choose the university. You graduate from there and you get offered a job in New York. So if you go to New York for a few years, then the boss says, listen, we need somebody to front up our new office down in Miami. Would you consider it? So you go, okay, fine, let's go down there. And then you get down there and actually you kind of don't like the place. You don't like the people.

37:13I don't know. For some reason you decide to move on and a job comes up in Phoenix, Arizona. Let's go there. And so you end up with this sort of little groups of small groups of friends that you meet in the course of work or socializing in each of these places in your social network, which typically consists for us with our small family size, about half family and half friends. Of course, the family is always stable. That doesn't really change very much, aside from the usual births and deaths, as it were. But the friendships have quite a high turnover. And what you end up with, as would be the place in your sort of ancestral village, where the friends remain stable as well.

37:55Now, in fact, they've broken up into these small groups of maybe five or 15 clusters of friends that you made while you were in a particular location. So you've got your kind of New York friends, your Buttar friends, your Miami friends, your Phoenix friends, and these don't know each other. They never meet. They don't meet your parents either or your family. So it creates these kind of dispersed, much less tightly bound networks. And I think that causes lots of problems in that it means your support networks are much more fragmented and therefore less bound to each other. Because what makes support networks really work is that everybody feels the sense of obligation to each other.

38:42And that part of that obligation is the knowledge that if you kind of fail to provide Jimmy with the support he wants on the one occasion when he needs it, everybody else wags their finger at you. And especially great grandma sitting beside her half. Because Jimmy and you are her descendants. So she's got equal interest in both of you. So that complex web of interrelationship causes people to be self-policing in small communities, whereas you have room to hide in the modern context where your network is more distributed. And I think that contributes to what in part to the reason why a lot of these kind of big sink urban centers are so dysfunctional socially because they just don't have those community structures to support them.

39:39You contrast that with something like the Hutterites or maybe the Amish over in Pennsylvania, Hutterites up in the Dakotas, you know, where they really work very hard to keep their communities at 150 for that, primarily for that very reason. They're very clear about it, the Hutterites in particular. So say, you know, if you have more than about 150 people in your community, you can't manage it by peer pressure alone. You have to have a police force. And we don't want police forces. That's not part of our way of doing stuff. So they deliberately split their communities up once they get, well, the average size at which they split them is about 165.

40:21and that's to try and keep the number within. Because communities have these unfortunate habits of just growing because people will insist on having babies. So a natural consequence of communities is they increase in size. So you have this constant battle to try and keep the numbers down from their point of view. It just means you have to keep splitting communities every decade or so in order to keep pace with it. And it really seems to work very well for them because if you keep your community down below that size, you have this sense of communal obligation, which makes things work somehow more smoothly.

41:03It's an interesting question as to why it won't work when the numbers get too far beyond 150, out towards 500 or 1 ,000 or whatever. It just doesn't work in that way. But this seems to be how the human social brain works, if you like. We have to deal with it as we find it. But it is kind of troubling because I think that this fact that our network become fragmented and dispersed over very big geographical areas, they're not all literally in your block that you can walk around and knock on the door and say, I feel dreadful. Can we go and have a coffee or a walk in the hills or something? It reduces the number of people that provide your support network directly.

41:51Because what really seems to be important is that face-to-face component of it. That physical, the fact that they can put their arm around your shoulder and say, listen, the world isn't so bad. Let's go and have a beer or something. If, as you say, it is so hard to keep track of people in our in-group, in our inner circle, it certainly is hard to keep track of all the people outside of it, right? And there's a lot of work in psychology, of course, on, you know, our tribalistic tendencies, that we like our in-group and we dislike all the out-groups, and we have these crude stereotypes about what the out-groups are like.

42:29How do you think about the relationship between numbers, I guess, the series of numbers, and how we think about out-groups, right? We talk about, you know, those Mexicans and those Australians, and we have all these crude stereotypes that are so vague and nonsensical oftentimes. But maybe we can't help it to some extent. I think this goes actually back to some very deep principles about how we create friendships, but also what the function of communities actually is. So communities exist for all monkeys and apes and therefore humans too, to buffer you against It's the stresses and unexpected disasters that the world we live in keeps throwing at us.

43:13So this form of bonded sociality you find in monkeys and apes and humans has been the secret of our success as the primates as a whole in evolutionary terms. because they've provided us with this ability to cope with the vagaries of the world and still survive and successfully reproduce and so on. So that's why we live in this. And the main problem you're coping, all these species you're coping with, is predation. Group living is the solution for a problem of predation, essentially, or in the case of humans added to that, raiding by people in the next tall valley, which seems to have become an increasing problem as population densities rose in pre-Neolithic times in particular.

44:05So the problem, if you like, is how do you create this sense of belonging, keep that group held together? And the way we seem to do that is essentially built around homophily. So one of the defining characteristics of all group is that they have things like a common history and a common kind of view of the world and these kind of things. And these principles turn out to be fundamental to how we build friendships. So friendships in monkeys' nakes generally is what we psychologists would refer to as the two-process mechanism. It involves two mechanisms in the brain working in parallel to each other.

44:49One is the endorphin system, which is a root part of the brain's pain management system. That's what endorphins are primarily there for. But it turns out also they're extremely good at creating a sense of bondedness to an individual. And that comes from the fact that if you trigger the release of endorphins, you get this sense of calmness and relaxation and all's well with the world and peace and bondedness to the individuals and trust in the individuals to do this. monkeys do this through social grooming. We still do that a lot. We don't have so much fur to groom, just a little bit on the top of the head, but we've replaced that with kind of cuddling and arms around the shoulder and stroking and patting and all these kinds of things, because the mechanism depends on the hand movements across the skin surface, triggering a very specialized neural system that links the skin to particular areas in the brain that trigger eventually the endorphin system.

45:56So we use that. We use it. It's not something we do with everybody because it's a very intimate thing, even in monkeys and apes. We only do it with our more closer members of our social network. What we've done is supplement that with a bunch of other stuff that also turns out to trigger the endorphin system, but on a bigger scale because we don't have to be in physical contact with the person. So laughter, singing, dancing, eating together, the rituals of religion, telling emotional sub-stories, all these trigger the endorphin system and in a way that it can be done virtually and therefore you can do it with many individuals because this physical touch component of social grieving, its intimacy means you can only do it with one person at a time.

46:39So I sometimes challenge people, try cuddling two people in the back row of the cinema next time you go, I can bet you anything you like, one of them will leave in a huff in about 10 minutes because you've not been paying them enough attention. So you just mentioned the keyword. I have been looking for the segue because this is one of the questions I've really wanted to ask you. And I have no idea how to bring it up. But you just mentioned laughter. Laughter can bring us together. It can be bonding. That doesn't answer the question that I have, but it gets to it, which is what makes something funny to begin with?

47:12How does humor work? It is so mysterious to me. I know I just became socially conscious with my 26 years, so what do I know? But what makes something funny? I think that's kind of one of the conundrums of life that has puzzled philosophers and a lot of other people for a very, very long time. Well, even the great Greek philosophers like Aristotle exercised about exactly what it is that makes, well, storytelling in general, but jokes so funny. Why do we laugh? The answer is, to some extent, actually, I suppose historically, in evolutionary terms, laughter probably goes back to slapstick comedy.

47:53So I think it came in very, very early on. So if we think about this kind of social toolkit we have that involves these things like singing and dancing and storytelling, most of those come in quite late, because a lot of them depend on language and being able to have conversations. It gets pretty boring to sit around a dinner table, or if you're a Roman, I suppose you used to lie around the dinner table. It gets pretty boring if you just sit there and eat and can't say anything. The whole point about doing that socially is to be able to have a conversation and talk to each other, as well as engaging in the eating of nice food.

48:32So those kind of things really depend on the evolution of really language as we have it now, let's say really sophisticated language. And that means it probably only came in with our own species a mere 200 ,000 years ago. Now, the kind of immediate precursors, the Heidelberg folk and their descendants, the Neanderthals and Denisovans and so on, the other archaic humans, they certainly had the language of a kind. But it's kind of was a much less sophisticated language because it just did not have the same mentalizing capacities as Sweden. Herein lies the issue with jokes, I think, because how funny we perceive a joke to be depends on the number of mentalizing states in it.

49:13So the number of mind states involved. The more mind states involved in the joke, the funnier it is up to the limit that we can cope with. And if you try and have a joke that has seven mind states in it, including your own, it's just not funny. It's too complicated. It's like trying to read a postmodern novel. Nothing makes sense. And it becomes less funny after that point. So, you know, the difference between Neanderthal jokes and our jokes would kind of caricature it as the difference between, I don't know, 12 or 13 year old joke and adult jokes. Adult jokes are very sophisticated, relatively speaking.

49:53The jokes of 12 to 15 year old boys are very funny to 12 to 15 year old boys. But on the grand scheme of things, they're on the scale of lavatory humor. So, you know, this is not to underpitch the intellectual capacities of Neanderthals, because, you know, most of the rest of the things they could figure out were pretty much the same as ours. But the social domain, you know, they weren't in the same league. So laughter had been really in place for much, much longer than that. It probably dates back about two million years because a lot of it is very visceral. We can't control it. That's what makes me think that it kind of has its origins in slapstick.

50:37It's things that happen. It's a form of chorusing, really. So it's sitting around the campfire, kind of engaged in a form of singing, if you like. And it does depend. The mechanisms of breath control are not the same as those involved in language. But the requirements for singing in terms of the mechanics of it and the neural control of it are for laughter very demanding, being rejigged. Because we share laughter with the great apes. And in fact, the voicing of laughter, the sound we make, comes from the play invitation vocalization of monkeys and apes generally. Or at least the old world monkeys and apes, the very social monkeys and apes.

51:19So they have this sort of pant-like vocalization that they use. These would be things like baboons and the like. Pant-like vocalizations that are kind of invitations to play as they approach somebody they want to play with. But also sometimes they will use it as a commentary on what they're doing, which kind of effectively says, listen, you know, if I bite you too hard, I don't mean it. I'm just playing. Don't bite me back. So it's a kind of commentary on what's going on. Now, this kind of signal seems to have been transformed into humans to make into what we have as laughter. This pant-like vocalization is an inhalation or exhalation inhalations from pant and a drawing in of the breath to fill the lungs again.

52:05And what we've done is disposed of, got rid of the inhalation. So we just pant, pant, pant, pant out. And that exhausts us. And that's probably what triggers the endorphin system from it. the stress on the musculature and the oxygen centers, if you like, detection centers in the brain, all these things going crazy, which is why you kind of end up dying with laughter because you just take all the air from your lungs. But boy, is it giving you endorphin. So this is just a kind of chorusing around the campfire without kind of words in them. But then once language comes into play, it gives you a mechanism for managing the frequency of laughter because otherwise you know slap state comedy it depends on something happening to trigger the laughter it depends on somebody slipping on the banana skin to make people laugh otherwise you know you're not going to laugh so jokes become a way of kind of dropping banana skins through the course of a conversation and And they become, A, they depend on language, and they depend on the complexity of language.

53:12So there is a sense that what makes a joke funny is the surprise element to it. The classic shaggy dog story that takes you off and meanders all around and finally gets to some joke at the end that makes you laugh. But it's that sense of being able to manage that. And it's clearly important because if you have a conversation, if you get stuck at a party in a corner of the room with somebody who never tells jokes in any form and never laughs, it's kind of like having a conversation with Mr. Spock on Star Trek. You kind of, where's the bar? Let me get out of here. We pepper our conversations all the time with kind of little amusing asides, you know, to make you laugh.

54:00We tell stories to make ourselves laugh. And this goes back to this other part of this bonding mechanism, which I never got around to. The other half of this dual process mechanism is basically a shared culture. And that reinforces the fact that you belong to a community. You know, these shared culture elements is what's known as the homophily effect or the birds of the feather effect, birds of the feather flock together. It seems to be extremely important in our friendships, how we create our friendship, and also is the root of creating communities. So in friendships, these are what we refer to as the seven pillars of friendship.

54:38And there's like seven dimensions, like a kind of supermarket barcode. But instead of being on your forehead, they come out of your mouth, right? They're things you say. And they're all cultural, so you have to learn them, quite literally. So there are things like sharing the same language, growing up in the same area, having the same hobbies and interests, having the same worldview, say religious, moral and political views, having the same life trajectory, kind of having been to college in the same place, having studied the same degree, having the same career, these kind of things. And last and not least, sharing the same musical taste and sharing the same sense of humor.

55:15So we're back at laughter again. Now, these are all things which seem to define a community that you belong to. So first of all, they define the community you grew up in, hence speaking the same language and growing up in the same area. Oh, you remember Joe's Cafe? Yeah, we were there. We used to go there when we were kids. You know, maybe a generation before you did, but we know those streets. We know those kind of old watering holes in the town. That was great fun and what we did. So there's those kind of points of shared experience in life and shared way of looking at the world. And I think the problem with that is, and this goes back to the question you were asking earlier, is it just automatically sets up an us versus them distinction.

56:03And that kind of ramifies all the way through the Dunbar circles, as it were, because it turns out that the more of these dimensions you share with somebody, the more emotionally close you feel to them and the more willing you are to be altruistic to them and you automatically those circles themselves are kind of built up on an us versus them principle if it's a question of one of your shoulders to cry on friends falling out with one of the people in in your 150 circle then you support your shoulders to cry on friend against the distant person then you know that's because you share more things in common now i think the reason for that is partly is it identifies whom you can trust if you grow up in the same if you come from the same community you know how that community works you understand what it is that when people say i'll do this for you uh next week you know do they mean it or not you know can you trust them and if we don't have to go around asking it and you it's a kind of shortcut actually it cuts through that 200 hours to know somebody because what you're essentially relying on is the third party approval that this person's okay you've never met them before but you know they come from the same community you know how they think because they're a member of that community you don't need to know anymore you can get on with life with them okay there's some details you may have to figure out but by and large gives you quick basis for building relationships and actually what's kind of interest most interesting in this context is that the one thing which turn or the two things maybe that turn out to be really important for meeting strangers whether you think they will make good friends is shared musical tastes hey you like bed zeppelin too wow and shared worldviews those same moral and political and religious views right and anything else, including ethnicity, kind of fades into the background and becomes unimportant.

58:07In those seven pillars stuff, that kind of eradicates all the other kinds of things that which act as kind of distant cues, you know, things like gender and race and age and all these other things kind of fade into the background, become much less important. So the problem with them, though, is, as I say, is they just automatically seem to be created in terms of an us versus them principle. Some of them work extremely well on a very large scale. And religion specifically is the one I have in mind here, because it seems to have extraordinary capacities, create this sense of belonging to a community with complete strangers that you've never met before, because they live on the other side of the world.

58:49They're a member of your village. And we think of it in terms of village we don't think of it in terms psychologically we don't think of it in terms of i don't know a billion people who belong to the catholic church we think of them as in our village attending our mass at our church or whatever your particular religious uh predilections might be um it seems to be extraordinary and this is this is what the these seven pillars seem to be designed designed to do but a they work extremely well in creating this sense of bonding but it's bonding against everybody else out there. And that's in the end where it kind of falls apart because we are so susceptible to persuasion by, I don't know, charismatic leaders or what have you, in a political context, that this sense of bonding can very easily be triggered for conquering the infidel or whatever it may be.

59:50this brings us to the point that we have to watch out for as you say people who might be friends and who might share our music tastes in common and political preferences but also people who are dangerous to the in group who are a little bit too status seeking or poor hungry selfish psychopathic whatever it is one thing that helps us get this kind of social information of course is gossip right this person did this bad thing over there and they did this and by the way this person is single and you would get critical information. And yet gossip is getting such a bad rep, at least in our society.

1:00:22Maybe this is not an intercultural phenomenon. Why is gossip getting such a bad rep if it's useful? Well, I think this is just a kind of classic case with everything in biology and psychology. You know, there is no such thing as perfection. There is no such place as nirvana on earth. we're always dealing with trade-offs. So everything in both the physical life we lead and the mental life we lead, many things have benefits, but they can be overdone when they're overdone. Salt is good for you, but if you have too much of it, it's bad for you. Protein is good for you if you eat too much of it, it's bad for you, extremely bad.

1:01:05That's why a lot of the expeditions exploring the Midwest in American 18th century history, early 19th century history, came unstuck and all ended up dying because the only thing they had to eat was meat because they could shoot it. And they didn't know which plants you could eat, so they were eating these very, very high meat-based, protein-based diets, and most of them just ended up dying from protein sickness. Oxygen is very good for you, but have too much of it, it kills you. Water is good for you. drink too much of it, and it doesn't do you any favors or so. By the same token, in the psychological world, the same things kind of happen, I guess.

1:01:48So the short answer is these things are always trade-offs. And I suppose the particular case of gossip actually is the classic case because gossip in its original meaning meant literally what you did with your god sibs that's to say your peer group equivalent of your god parents that's where the word comes so it's hanging out that's all it means essentially and you're chatting away and you know what you're learning in the course of conversation like that is how what's going on in in the social world who's been misbehaving and who hasn't and it allows you to work more effectively in the social social context.

1:02:29Well, the problem with practically everything in the psychological world can be exploited for good and for bad. Once you have something in place, it can be exploited for other purposes. Something like that is very... And I guess it also comes about the fact that we're very dependent on reputation. Reputations are very important in a generic sense, because they relate to trust. And therefore, for you to be able to manipulate somebody's perception of a third party's reputation. It holds out the prospect of, you know, offering you an extra kind of leg into the social world, if you like, to get what you want.

1:03:09So, you know, don't go out, you know, socializing with Jimmy. You know, you end up buying him drinks all night because he never paid. You know, these kind of things, you know. Don't go playing golf with so-and-so. You know, they're always cheating. And in some sense, this is also just part and parcel of managing how the social world works, because it's also a form of policing, making sure everybody sticks to the rules. But then you can exploit it. And there's nothing you can do about that, except that it's clearly, whether that's a comment on modern life, I don't know, but it's clear that the word gossip has come to have these very negative overtones.

1:03:52For a term which didn't actually have any negative overtones originally, it was all very positive. Whether that's because we do more and more of it than our ancestors is an interesting question. but it's clear that at the same time we also are very wary of gossips right people who gossip a lot and are perceived as being destructive gossip so are always being very negative about other people are not liked on the whole and okay the classic case i guess is there is a sense in which is kind of well-established effect in social psychology that people who have information to offer about other people in the community are kind of attractive.

1:04:38You want to find out what's going on. You know, what's Jimmy been up to now? So you go and ask so-and-so because they always know. There is a sense in which they can push that too far. You can get a very bad reputation as a gossiper, as it were, which causes people to back off from you. So it's back to this sort of principle that a little bit of something is good for you in life, but too much isn't. we are well running up against time we are above time already and i want to be mindful of your time of course so to wrap this up i want to get personal a little bit and to ask you thinking back when you were young you know before you became socially conscious at 25 in college and figuring things out in terms of what you envisioned for your life and compared to the life you have been living so far and what you might have planned for the future.

1:05:34Do these realities match or did you have very different plans for what you would do as a socially conscious adult? Oh my goodness. I don't think my current life and trajectory, career trajectory, bears any relationship whatsoever to what I thought might be the case. I mean, for starters, I I grew up in Africa in basically a completely different cultural environment. Would have had, I mean, we didn't leave until I was in my 20s. So I really did, you know, sort of grow up there. It's my home, if you like, home environment. And my expectations of what I might have done if we'd stayed there and I hadn't come to high school and college in the UK, would have been very, very different.

1:06:28So early on, I'm not sure I had any great expectations other than the kinds of things people did in Africa in the 50s, and in particular in the 60s. I kind of got sidetracked in a way in my later teens, largely through the influence of my cousin, who was a little older than me, but with whom I, it was his family I lived. and he introduced me to philosophy and got me interested in philosophy and actually by the time I went to university that was all I was interested in so I was not a scientist at high school my specialisms at high school were history and English and I regarded science as kind of the weird stuff which really strange people did intellectuals did serious things like history which is my favorite subject and or philosophy and so i wanted to do philosophy at university but i uh i ended up going to to oxford as a university you can't do philosophy on its own at oxford then or now you have to do it something else and i chose what was then a new course philosophy and psychology i've only been going a couple of years when I went as the least bad option.

1:07:48And I had no idea what psychology was really because in those days, psychology didn't feature a school curriculum at all. Anywhere, I don't think. It was just the early 60s. And so, you know, it sounded vaguely interesting. Certainly a lot better than the alternatives. But what it did was introduce me to the sciences. And there were two key components to this. One was the whole of the first year was taught by the zoologists rather than the psychologists. It was called comparative psychology, but actually it was ethology, animal behavior. And it was taught by Tim Bergen, the great, one of the founding fathers of ethology and behavioral ecology as we have it now, who got the Nobel Prize for that work.

1:08:32So I was introduced to animal behavior in a context where I would never have thought about it because all my experience of animal behavior in Africa was at the other end of a rifle barrel. very familiar with animals but they were all at the other end of a rifle so here was a completely different way of looking at them in terms of their behavior also the psychology of course introduced me to various aspects of the science background to psychology so as to the limiting extent we neuropsychology was developed you know the brain so on in those days physiological psychology was very important uh you know sort of those kind of more hard-nosed ends and and uh statistics statistics is a major component so it introduced me to a branch of life i didn't know existed and it was fun you know numbers are fun to play with that kind of drew me into being a a scientist rather than a humanities person i began to realize that you know you had to have a head the size of a planet to do philosophy properly because it's just damned hard stuff and you know life is easier and more interesting if you do psychology and then also the third kind of thing that happened about that time was i had some friends they want to do an expedition oxford university had this tradition of doing expeditions to obscure parts of the world and some friends of mine wanted to go to ethiopia and they we decided to do a project studying baboons in the wild.

1:10:03And that's what we did. And that kind of introduced me back in Africa, my corner of Africa, to a completely new way of looking at animals through a pair of binoculars and check sheets and recording what they do. That actually sowed the seeds then for the rest of my career. But the rest of it was a series of accidents. Because if you look back on how the ideas around Dunbar's number and all these other things have developed, they developed largely as a result of accidents. So the original social brain hypothesis component with its prediction of Dunbar's number was completely accidental. Had just had the idea of, I was trying to solve another problem and I just thought this was vaguely related to that problem.

1:10:49Plot group size against brain size. It sparked a whole new thing. But everything else that came out of the back of that was in many ways the collaboration with lots of different people from different disciplines. So physicists, neuroimaging people, neurobiologists, economists, historians, name it. A, it was a lot of fun doing stuff in groups. So creating this sense of community. But also having that diversity of inputs from different fields was very enlightening and opened up things which I could never have done on my own. This is very much a communal project in more senses than one. I'm sure there's been around 150 people who helped you along the way.

1:11:37I would probably guess that's about right, actually, which essentially means I have no friends. They're all collaborators. But, you know, collaborators become friends. Well, that's a perfect note to end on. Thank you so much. That was a wonderful conversation. A great pleasure. Thank you so much for listening. We would love to hear what you think of this episode, or if you have any other suggestions for future guests or topics for the podcast. You can reach us at stanfordpsychpodcast at gmail.com. You can also connect with us on Twitter at stanfordpsychpod. Finally, if you enjoy this podcast, please consider leaving us a review on Apple Podcasts or elsewhere so more people can find us.

1:12:23Thank you so much.

1:12:28Thank you.