The Collective Brain and Human Evolution

Hey there, Shankar here with some exciting news. Our live Perceptions Tour is returning this summer in partnership with public radio stations around the country. This time we're heading to Northampton, Massachusetts, Burlington, Vermont, Boulder, Colorado, Grand Rapids, Michigan, Blacksburg, Virginia, San Luis Obispo, California, and Oklahoma City, Oklahoma. More information is at hiddenbrain.org slash tour. I hope to see you at one of our upcoming stops. Okay, here's today's show . This is Hidden Brain. I'm Shankar Vedantham. Think about a time you flipped through an old family album. Maybe you paused on a photo of your grandparents as young adults. Their clothes look outdated, their expressions too formal. Perhaps you imagined what it was like to live in that time and found it impossible . Or think of a film set in medieval times. You may have thought, wow, these people lived in a completely different universe. I have so little in common with them . It's easy to believe the past is sealed off from us, that those lives, those cultures, those ways of thinking, have vanished from the world . But is that true? In ways we don't even notice, the choices , beliefs, and habits of people who lived long before us continue to shape how we see the world today. They influence what we value, the kinds of societies we live in, even how we relate to one another . This week on Hidden Brain and in a companion story on Hidden Brain Plus, how culture and history shape the way we think Support for Hidden Brain comes from Lily. On this show, it's fascinating to discuss the unseen forces shaping the human brain. Consider conditions like Alzheimer's disease, where changes in the brain may develop up to 20 years before noticing symptoms. Talk to your doctor to understand your potential risk factors for dementia due to Alzheimer's disease and ask for a cognitive assessment. Visit brainhealthmatters.com for more information and resources . 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When you woke up this morning, you turned off your alarm and brushed your teeth, you had a bite to eat, said goodbye to your spouse, and commuted to work. You're clocked in for the day. All of this seems so routine, so commonplace, that we don't stop to think about it. We don't realize how the patterns of our lives are shaped by the long ago and the far away. As the novelist William Faulkner once said, the past is never dead. It's not even past . At Harvard University, Joseph Hendrick has studied how people who lived in previous centuries continue to shape our lives today. Joe Hendrick, welcome to Hidden Brain. Joe, I find myself checking the time constantly. I'm always running from one thing to the other. I sometimes feel like I live my Yeah, that was a world governed by sunrise and sunset, where there were still twelve hours in a day, but the length of those hours varied. There were seasonal rhythms that helped people organize farming and uh and it was just a very different world than the constant uh um interest in time and how my and saving time and getting more time and uh thinking of time as money. I'm imagining that given that people lived in different time zones and in different latitudes, uh people really, you know, started and ended their days at different times in different places of the world. Yeah, I mean everything was organized around sunrise. So and of course that varies if you're not along the equator, that changes throughout the year. There were no electric lights, candles were expensive , uh, so people had to adapt to the availability of light. And of course everybody was farmers, or almost everyone, so that meant that the seasons really mattered a lot, the weather mattered a lot, and you had to organize your work around those cycles . I understand the first mechanical clocks appeared around the thirteenth century. That's right. They began spreading in northern Italy, so places like Milan and Parma, but then they were very popular, so they rapidly began spreading amongst the urbanizing parts of Europe. So getting to Paris and London. Uh and initially there wasn't a clock per se, it was just uh tied to bells. So the cities and towns, everybody was within earshot of the ringing bells, and so it would ring the beginning of the day and breakfast and uh lunch and whatnot. So the entire city would move in clockwork with the ringing bells, and then eventually there you get a clock face and things go from there. I understand that various towns began to compete with one another to to install uh beautiful and magnificent clocks. That's right. So clocks were a sign of town wealth and prestige. Famous artisans would construct the clocks and clockmakers became I'm wondering how this invention changed the way people lived. Uh so now all of a sudden, you know, you're not just going according to the the rhythms and cycles of the sun. You actually have uh something that tells you it's eleven o'clock in the morning or ten o'clock in the morning or two o'clock in the after If you were late, uh contracts began to have exact dates when you had to have things due. Uh witnesses were told to report at court at a certain hour. So it really just reorganized the society. Not only that, it was seen as uh a good and So punctuality began to be tied to probity and all this was woven in with religion. So of course monks had long been timing their prayers using candles and uh hourglasses and then they began to incorporate the clocks in the bells. I understand that there's fascinating research looking at towns and uh cities that install clocks before other towns and cities and that this had a profound effect on productivity and and wealth ? Yeah, so this is a fascinating research coming out of economics. And uh if you look at the few centuries after these towns throughout Europe adopt a clock, you actually see an uptick in economic growth in the centuries after the clock arrives. So it's not an instantaneous effect because people actually have to adapt their thinking. And it takes a long time to get used to thinking in this time-thrift way in which we all , you know, we're all very tied to the clock and we've internalized it. But that's not something that automatically happens. And do you think this increase in productivity, this increase in wealth was really a result of people harmonizing their schedules. In other words, I can show up somewhere and I know that someone's gonna meet me at a certain time and place. I don't have to wait two hours for them to show up because in fact they're following some different cyc.le. Yeah So it increased people's ability to coordinate, but it also began to affect other things like payment schedules. So once you have clocks, you can pay people by the hour, uh, and then at the same time you get the spreading of piece rates. So people begin manufacturing, markets are spreading across these towns. And then if you if you pay a piece rate, so per horseshoe that you're making, then people begin to think about and that they have a clock, they can figure out, well, how many horseshoes can I make in an hour? Maybe I can make five. Well, what if I can make six? You know, then you you begin to think about the world like that. So you're an anthropologist, uh Joe. I understand that you were once working in Fiji , and you notice that the way that you think of time was very different from your collaborators in Fiji . Yeah, so I was starting a project and I was hiring uh some students from the University of the South Pacific, excellent research assistants, were assisting me in this village, and we were doing interviews and observations on daily life. We were doing some behavioral experiments, all kinds of different things. So I was kind of running the project in the style I was accustomed to, which meant we had morning meetings and certain appointments and I would give people a certain amount of time to finish things. Uh and initially I wasn't uh having much luck although the the research assistants were excellent in many ways, they didn't seem to be very tied into the clock the way I was. And so then I bought I bought everyone watches. So I figured, you know, maybe I can solve this with technology. And of course I was paying everyone. This still didn't seem to change anything at all. Everybody was wearing the watches. And then on one funny occasion, I was working closely, we were looking at this laptop with a research assistant, and I happened to look down at his watch and it said something like 1120. And it turned out his watch was about 25 minutes off. And Aaron Powell So what's striking, of course, is that people like me certainly sort of bemoan the fact that other people are not punctual or they don't show up, but in some ways, you know, not paying attention to the clock is actually a more natural state of things, if you will. Yeah, that's right. In lots of places it's considered um bad to be paying too much attention to the time. When you meet with somebody you shouldn't be rushing off to your next thing. You should be taking time to connect with them, see how their family is, swap stories, you know, sort of reconnect, focusing on the social. I mean, you know, in some societies the clock is seen as the kind of the devil, right? Because it's what drives people away from uh really forming these tight social bonds and nurturing the social bonds through time. Psychologists, R. Nor and Zion and colleagues, have actually gone around the world and tried to measure this in different cities. And they found that things like how long it takes to get to a stamp, the the the rate at which the guy behind the counter is moving actually varies from city to city. And they actually correlate with it the measures of individualism for those cities. Meaning that places with higher individualism are more punctual and and vice versa? That's right. And the person behind the counter is actually moving faster, and the clocks in public places are more accurate . So that you can measure the accuracy of the clocks in public places of time have seeped into our lives to the point that we're not things and you can find this in the work of Ben Franklin, is that he emphasizes the equation between time and money, which is not something you find elsewhere. And of course this metaphor has now spread globally. And this is one of the things that dominates our life. You know, we're always wasting time We like to think our choices, our thoughts, and our habits are entirely our own. But in reality, our individual choices are often echoes of centuries of cultural evolution . When we come back, the role of history in shaping our behavior, thoughts and feelings . You're listening to Hidden Brain, I'm Shankar Vedanta . Support for Hidden Brain comes from Lily. On this show, it's fascinating to discuss the unseen forces shaping the human brain . Consider conditions like Alzheimer's disease, where changes in the brain may develop up to 20 years before noticing symptoms. Talk to your doctor to understand your potential risk factors for dementia due to Alzheimer's disease and ask for a cognitive assessment. Visit brainhealthmatters.com for more information and resources. Support for Hidden Brand comes from LinkedIn. Running a small business means every hire matters. A bad hire can cost you time, money, and momentum. A good hire, they can help grow your business. LinkedIn's new h iring pro screens candidates for you, so instead of sorting through applicants, you spend time talking to only the right ones. Get started by posting your job for free at LinkedIn.com slash hb. This is Hidden Brain. I'm Shankar Vedanta . We think that the lives we lead are sh aped by the choices we make. But many of the routines we follow were shaped by centuries of history and cultural evolution . Anthropologist Joseph Hendrick looks at the way history and cultural evol ution shape what we think, how we see the world, and the decisions we make. He's found that even things we see today as moral and right were often inventions by ancient actors who had specific goals and political aims in mind . I want to talk about the relationships that undergird most of our lives today, Joe. Marriage, the nuclear family, rules of inheritance. Transport me back to pre-Christian Europe. What were familiar relationships like for most people back then ? Well, at that point in European history, the kinship systems, the families, the clans look like large extended families. In Europe is patrilineal. In lots of other places in the world it's matrilineal. People inherit through the family by custom. Their societies are organized by clans. The economic system, the political system is all very tied into these kin relationships. So for example, many kin groups have corporate responsibility, which means if someone else in your clan , or including especially your brother, d commits a crime, then you can be held responsible. So you're considered synonymous with your your close kin. If someone within your kin group does something shameful, then it actually brings shame on you. So shame is contagious through these kin networks. Marriages are often arranged, people play bride price or dowry. This forms a bond between uh groups. And people are also tending to mar ry endogamously, so with c uh close close kin, some uh like cousins, things like that, uh or other other relatives. And and and and kin also provided a kind of um social I mean, so you had these large groups in some ways, and they were all responsible for each other, looking out for each other. That's right. So they're not only the core of the economic system, but they provided a social safety net. So if your husband dies, a typical thing would be you would marry his brother. And then you would maintain the bond and and as a as a woman you would be taken care of and your children would still be part of that kin group. So there was all these social norms to kind of take care of things. If both parents were killed, then the children would automatically go to other members of the family where they'd be raised and and taken care of and whatnot. So at one point the Roman Catholic Church begins to spread across uh Europe. Pope Gregory dispatches a mission with specific instructions regarding marriage in particular? Yeah, this is happening all throughout Europe as missionaries are moving from the Roman Empire and from Rome out to the Celtic tribes and other Anglo-Saxon tribes, other Germanic tribes to try to spread Christianity to these places. And when this monk named Augustine arrives in Kent, he begins to convert the king and his wife who was who was already Christian, she married and she was a Frankish princess. So Augustine queried the Pope to find out what kinds of things he should be conveying as he faces these challenges from the local people in Kent. And so one question he asked the Pope is , how distant must a relative be uh for a Christian marriage to be permissible? So can I marry second cousins? Can I marry third cousins? Another question was, can a man marry his stepmother or his brother's wife . And then can two brothers marry two sisters, and can a man receive communion after a sex dream? How did the Pope respond to these questions? Yeah, so the Pope uh to the first question, he said, definitely can't marry first cousins. During this period in history, the church was definitely banning first cousins. They would go on to ban all the way out to six co usins, but at this point you could marry your second cousins. And you cannot marry your stepmother. So it's not about genetic relatedness. It's about these family relationships that are created. And certainly not your brother's wife . So that would be a kind of le Leverett marriage. And the church banned that pretty early on uh in the history of the Catholic Church. Two brothers can marry two sisters, so that was okay. So another papal commission arrives in England a couple of centuries later. They're checking in on the progress of Christianizing the Anglo Saxons. Um what does it find? Yes, and in general there's a lot of progress on uh people officially accepting Christianity . Lots of people have been baptized. But there's still problems around what they describe as incest, by which they mean cousin marriage of various kinds, and also polygyny. So elite men are taking one primary wife, but they're also mar rying uh other women as secondary wives and concubines. And so I'm imagining the church might not look kindly on these developments. Yeah. So the question was is how do we put an end to this? You know, we like the idea that the church is spreading and these people are becoming Christians, but these forms of family are weren't acceptable. Uh so one of the things that the Christians really pushed, the the church leadership really pushed was the the notion of illegitimate children. So the the lever they used was that unless you were married in an official Christian church, then you're an illegitimate child, which meant secondary wives in this system, like in many places around the world, their children still had some inheritance rights. They were still recognized by the community, but the church tries to put an end to that to prevent not only inheritance of wealth, but succession and this is going to affect the royalty a lot because that means the church controls who gets to be the next leader when you have uh descent of power down the bloodline. One of the other things that the church required was to ask newly married couples to set up independent households. Talk about this idea, Joe. Yeah, that's right. So that's called neolocal residence, and it's very rare in a global and historical perspective. So when young couples will marry, typically they would live either with the groom's family or the bride's family, depending on whether they're patrolocal or matrolocal. So that's the anthropological terminology. But what we find in in Europe during this period is the church are encouraging them to uh marry later and set up an independent residence so that they're independent from either side of the family. And so you have new couple making their own decisions independent of the family. Now I imagine that there must have been some people who looked at these new rules and said, you know, the hell with these rules, I'm just going to go my own way and do my own thing. Were they punishments for people who violated these rules? Yeah, there could be quite severe punishments. So the church can always excommunicate you, uh, and then there's something even more severe called an anathema. And excommunication might in the modern context not sound very severe, but it meant you couldn't enter into contracts with other Christians. You were ostracized , those who might associate with an excommunicated individual got some of this spiritual taint on them, and it could affect their relationships. And in some cases, the church's protection of you was withdrawn. So if someone killed you or injured you it wasn't considered a crime. So being excommunicated had real uh heft. Um , did all this change the way people behave, Joe? It took a long time, but it eventually breaks European families in different parts of Europe to differing degrees down into monogamous nuclear So you went from large clans and kindreds down to, you know, the the husband, wife, and the children, and that was the basic family unit. One of the things that happened as a byproduct of this is that people started to think in terms of individual rights and personal responsibility rather than always prioritiz ing family loyalty and kin. Talk about this. I find this fascinating, Joe. Yeah, because what the church did by having these prohibitions and prescriptions about marriage in the family is you no longer had a big clan or this large extended family that you could rely on. You couldn't build a l alliances by marriage very easily . So people began to set up voluntary associations where people would join. These were often Christian-based. You'd have to take an oath. And in order to get those organizations interested in you, you'd have to have certain attributes and accomplishments and things you brought to the table. So rather than having a large number of relationships that you inherited by birth and had via all these various kin ties, you had more of these optional relationships where you had it was kind of a more of a marketplace for relationships. So this affected finding mates. So rather than arranged marriages, you had to find your own mates, uh, friends, business partners, all these sorts of things. And it led to the proliferation of these voluntary associations. Hmm. You talked earlier about how um kin groups would look after one another. So if someone was in trouble or if someone lost uh a spouse or or if children lost their parents , the the kin, the larger kin would look after the the person who needed help. Uh what happened to those systems as things became more individualized? Yeah, a few different things. So the the one thing the church did it had to step forward almost immediately on this, is to take care of orphans and widows. Because normally they were sort of just slotted right into the kinsip system and there were norms that took care of them. What the church did meant that there was really no one to care for orphans and widows. So the church began to take them in and they've, you know, they became core members of the church in that sense. These these voluntary associations that people would join were also mutual self-help groups. So you would all mutually agree to help each other out if you were injured or had a period of unemployment or you know in in your old age and whatnot. And then eventually after the beginning of Protestant ism, when the church is not doing this in places like England, um after Henry VIII gets rid of all the all the Catholic institutions, uh Queen Elizabeth initiates the poor laws of 1600. And this is the beginning to lay an official secular social safety net under, you know, under people who might, you know, need it. So in some ways, the picture that you're painting, of course, uh shows us how many of the institutions that we're familiar with today actually had a point of origin that in fact they they arose as a result of choices made by specific actors in specific circumstances and many of them had specific political and social go That's right. But a lot of it is also unintended consequences. So the church, of course, was doing this because they c they believe that this is how God wanted it. And so when plagues would hit, uh the church would explain the plague as a consequence of there being too much incest, by which they meant too much cousin marriage. And the the the the breakdown of these families into monogamous nuclear families inadvertently led to the rise of these voluntary associations, which gave us the many charter towns of Europe, universities, new kinds of monasteries, and these mutual self-help associations which eventually become occup So many of those things become some of the core institutions of Western society. Talk about the family, the the kind of family that we are used to seeing around these days. The the nuclear family, you know, husband, wife, kids living by themselves. Talk about how that's actually quite unusual in the history of the species on the planet. Yeah. So when you uh look at the anthropological data on this, so anthropologists have put together something called the ethnographic atlas, which is over 12 ,00 diverse societies that have been studied in ethnographic detail. You find that most 85% of societies allow elite and high-status men to marry additional wives. You find cousin marriage in most societies is permitted. Um, neo-local residence is very rare, although common in the West, as we discussed, and just many other kinship practices like leverett marriage, which you don't find in the West, are common around the world. So it's as if these norms evolved to build these dense networks of kin to organize production and consumption and distribution. And by preventing this from happening in parts of Western Europe , the church actually opened the door to new kinds of institutions and new ways of thinking about the world . You coined the term for the kind of modern psychology that animates Western educated, industrialized, rich, and democratic societies. Tell me about this term, Joe. Yeah, so this began in about 2005 , when I arrived at the University of British Columbia. And there I was moving out of anthropology into psychology, and I encountered two colleagues, Steve Heine and R. Nor in Zion . And we we would go to lunch together and we were each talking about our research and we were studying all studying cultural differences. And what we had each independently found is that not only was there interesting cultural variation around the world, but that the populations most studied by psychologists and economists were psychologically peculiar when placed in a global and historical perspective. So we, you know, we began to think about and try to put together a case trying to convince psychologist s and economists that they needed to think more broadly about psychological variation and just not generalized to all of humans based on one common culture that they they most commonly studied. So we coined this acronym or, I guess it's a backronym, uh weird. It stands for Western Educated, Industrialized, Rich and Democratic. You notice differences between uh these so-called weird societies and other types of cultures while you were working with uh tribe in the Peruvian Amazon. Uh tell me about this work and what you found. Yeah, so this was my very first anthropological field work, and I went to the Peruvian Amazon. I flew in on missionary planes and land ed on the river and went into the village. And then I traveled around in a dugout canoe around to the different villages. And at this point in my career, this is kind of the mid-1990s now, studying cooper ation. And one of the ideas that we were thinking about was the possibility that the willingness of other people to punish poor behavior, non-cooperative behavior, unfair behavior might be part of the reason why humans are able to cooperate so much uh compared to other species. And so we were thinking about that. And then I heard about this experiment called the ultimatum game. And the ultimatum game is a simple bargaining game from economics in which two players are allotted a sum of money and the first player can offer a portion of this money to the second player. The second player can either accept or reject. If they accept, both players get the amounts that uh were allocated, or if they reject, then both players get zero. So for example, if the first player offers ten dollars out of the hundred to the second player and the second player accepts, they get 10 and the first player gets 90. If they reject, both players get zero. So when this had been done by economists in places like the US and Zurich and elsewhere, uh they had found that most people offer fifty fifty and that low offers are frequently rejected. That sort of fit my intuitions. So I thought that I could perform this experiment among the Macha Ganga and they would show um similar results. It seemed intuitive , and that then this would be an interesting uh piece of the puzzle in trying to explain human cooperation. But what I found was that they they didn't feel inclined to reject it all, and people gave pretty low offers. Uh so on average people gave only 25% of the stake instead of 50%, and lots of people gave uh 15% . So this led to a big project, and we we did this experiment in many different places and we found a great deal of global variation A.aron Powell What do you think explains this? What's happening in the minds of people in uh in Peru that is different from Los Angeles? Well, I think it relates to a larger story that you and I discussed with the spread of the clocks. It has to do with market integration. And so what we found across these communities is that the more market integrated communities seem to have norms about fair dealing with anonymous others, with impersonal uh uh people you would just meet and not know their name or not know anything about their families. So more market integrated societies have norms that say you should just generally be fair-minded with people who you don't know and won't see again. Whereas the Machu Ganga lifestyle is uh small-scale farming, they live scattered throughout the tropical forests of of Peru, north of Cusco where Machu Picchu is. And uh, you know, they just not a lot of trade and exchange. So they don't have these market norms. And so to them, when I would interview them after, they would be like, Yeah, well, why would anyone reject free money in this case? Which is pretty close to the rational thing one might expect based on game theory. Right. The differences between um these so-called weird cultures and and other cultures also show up in different psychological tests. Um research has been conducted looking at eye tracking movements between Americans and East Asians. Tell me about this work. Yeah, so this is very interesting because it's perceptual. So uh psychologists have shown there's this tremendous variation in analytic versus holistic thinking. And one of the hallmarks that they found in terms of attention is what people pay attention to when they look at a scene or a picture or a video. And uh Americans, more analytically oriented societies, will tend to focus on the central object. So in this case, imagine uh it's a scene, an underwater scene with fish swimming around. The Americans tend to focus on the central fish and they watch what the central fish does. They don't tend to notice very much stuff in the background. The uh folks from East Asia would remember a lot more about what was going in the background and their eyes would cover more of the scene and just not kind of glue to the central actor. Do you think this is again evidence of the propensity of weird societies to focus on individualism and individual objects? Yeah, so this is this seems to be part of a larger package. Um you know, in an individualistic society , people tend to focus on themselves and their own attributes and they think about others dispositionally. So what are the attributes of another person, honest or dishonest, without thinking of all the contextual variation. Whereas if you're from a more holistic society, a more collectivistic society, you're thinking about the relationships between individuals. People aren't either honest or dishonest. They're honest in some circumstances with some kinds of people So there's this uh this interesting uh different ways of thinking about the world. One of the things that I find fascinating about all of this is that it highlights just how much we can take culture for granted. Uh so for example, we might live in mostly monogamous societies, and so we assume that humans must be wired for monogamy. Uh that in fact might not be the case. Yeah, it's amazing how strong the intuition is is that however it is where I live is how it is to be human. Uh so yeah, w one of the things I've been most interested over my career is trying to figure out what is actually panhuman and what is just the the particular societies that we grow up in the invention of clerks and religious rules for marriage all profoundly influenced the way modern people think and behave. More about how culture shapes our minds when we come back. You're listening to Hidden Brain, I'm Shankar Vedanta . Support for Hidden Brand comes from Pacific Life Insurance. Everyone knows promises have power. From pinky swe ars to Cross My Heart to I Do , we make them throughout our entire lives. Anyone can make promises. What matters is keeping them. For nearly 160 years, the people at Pacific Life have been helping you keep yours. Whether it's protecting your today or planning your tomorrow, they're with you every step of the way. Pacific Life, the power of a promise. Ask a financial professional about how Pacific Life Insurance Company, Omaha, Nebraska. And in New York, Pacific Life and Annuity, Phoenix, Arizona . Support for Hidden Brent comes from Sleep Number. Life changes. Your mattress should too. Sleep Number's new collections are designed for personalized comfort that evolves with you. As your body, health, and lifestyle change, you can adjust firmness anytime for lasting support. It's the Everything on Sale Memorial Day event from Sleep Number. Every bed and base is on sale now. Visit a sleep number store near you or learn more at sleepnumber.com This is Hidden Brain. I'm Shankar Vedanta . Have you ever given thought to how your daily life might be shaped by events from the distant past or by traditions thousands of miles away? If you have a personal example you'd be willing to share with the hidden brain audience about how the past shapes your behavior today, please find a very quiet room and record a voice memo on your phone. Two or three minutes is plenty. Email the file to us at feedback at hiddenbrain.org. Use the subject line cul ture. Again, that's feedback at hiddenbrain.org. Anthropologist Joseph Hendrick is the author of the books The Secret of Our Success, how culture is driving human evolution, domesticating our species and making us smarter, and the weirdest people in the world, how the West became psychologically peculiar and particularly prosperous . Joe, in june eighteen forty five, two ships set sail from Britain in search of the fabled Northwest Passage. Tell me about this mission and and the man who was leading it. Yeah, so this mission was led by Sir John Franklin, and it was an effort to find the fabled Northwest Passage with economic goals of energizing trade and uh connecting Europe and East Asia, and also doing some mapping of that area, understanding the magnetic field. And it was a fascinating expedition because it was kind of the Apollo mission of the 19th century. This was a super well outfitted ship. It had icebreaker technology. It had retractable screw propellers. It was insulated with cork. There were desalinators on board. And it had a new technology, canned food, which was meant to allow the crews to live for over a year uh in trapped in the ice in the north. So they were ready to engage in this exploration. And they were led by this experienced guy, John Franklin. And so they headed out, and the very beginning of the trip went fine. They were exploring the i islands north of Canada. Uh they wintered near an island uh called Devon Island. The ice came in around the ship as expected. You know, I guess they cracked open the canned food and waited the winter out until the ice retracted and then they kept exploring. But the next year, uh, they were near King William Island, then they were exploring around there, and the ice came in again and froze them in. That was all expected. But the next summer, the ice didn't seem to retract. And so they were gonna have to winter again, and that seemed like that was gonna be a problem. Their leader, uh Franklin, promptly died . So the men were trapped in the ice and they were faced with a challenge of living off the land. Because they have to see if they can use their big brains and great intelligence to figure out how to do something very basic, which is surviving in the Arctic. What happened? Well, uh things did not go well. So the men eventually left the ship and they began trying to survive on King Williams Island. Um they left some notes along the way which were later found, and the ships have soon been found. So we're not exactly sure what happened, although we know from tales from the Inuit bands that they encountered that there was probably some cannibalism going on. One Inuit story has them first encountering them and beginning to exchange some some meat, uh but then they realize the men are carrying frozen limbs, and it turned out the frozen limbs are their comrades probably. Uh and then the men all just disappear and and leave no trace of them other than the stories and the minds of the Inuit. It led to a big rescue expedition, so explorers from all around the world converged on the Canadian Arctic to try to find these guys. Now, you pointed out something really interesting in passing here, which is that there were people who were living in this area, presumably successfully for a long period of time. Why couldn't these men survive. Yeah, it's amazing. The group the Nescalet that was living there inuit uh their word for the island that Franklin was trapped on is land of fat, because for them it was a rich environment uh that they could live on and winter on the ice and hunt seals and in other seasons, shoot caribou with their bows. They could uh render seal blubber or seal uh seal fat into um oil that they could use for lights, they to the for for for illumination and heating. Uh they could spear salmon during certain seasons. They made kayaks there. To them there was just a lot of resources there, but to Franklin's men, you know it, was this barren expanse and you know it was almost it seemed impossible to survive there. I understand that some years before this expedition another crew had found themselves stranded in the same area. Tell me about this group and what happened to them. Yeah, that was led by an explorer named Ross. And uh I think it's a great example because we can compare the explorers that did well on King Williams Island with what happened to the Franklin expedition, and the main difference is in how they interacted with the Inuit. So the Ross Expedition uh begins to open up trade relationships with the Inuit. They're able to get all kinds of uh clothing and food and so they're just able to survive much more easily by taking advantage of the vast knowledge of the Inuit. They travel and explore uh through their through their new allies and new friends with the Inuit. You described several things that the Inuit were able to teach uh the visitors, uh, including fairly complex tasks involving, you know, hunting and trapping. Um, can you describe some of these for me just to show how intricate this knowledge system was . Yeah, I mean the r the amount of insight and knowledge and skill that you would have to survive in this environment is really incredible. So uh one thing that is the Inuit routinely did during this period was they would be able to hunt seals. And so you had to uh figure out where the seals are going to be, and it had to be an area that was covered with snow so you could And then you would use a a uh spear to to wait there until you got a sense that the seal was there and there had little uh feather markers that would tell you if the seal was there and then you would um plunge your harpoon into the hole. Uh you needed a special bare bone handle because you needed some really strong um materials to for the end of it that you would use to drive into the seal. And then of course you had to know what to do with the seal once you got it out. Uh they also made sleds and they made use of dogs and they made this special cold weather clot clothing , uh. So just an immense range of cultural knowledge. And of course, this is not testament to the fact that the Inuit were necessarily smarter than their visitors, they'd had more time, and they'd passed on this knowledge, presumably from generation to generation, each generation adding some new insights. Yeah, so that's the key thing is that the Neskelit benefited from this cumulative cultural evolution. So over generations , this large body of knowledge had increasingly adapted the Inuit to surviving in this environment. So it wasn't that they were smarter, it's that they had this large body of cumulative knowledge, which Franklin's men did not have. So this gets at something that researchers call the cultural intelligence hypothesis. What is this hypothesis, Joe? Well, this is the idea that really what our brains have evolved and why they've gotten so much bigger than our primate relatives or than our ancestors two million years ago is that our brains evolved to acquire, store, and organize cultural information. So it's not that our brains have evolved to individually solve problems. What we're really good at is taking advantage of all the information stored in the minds around us in the minds of others and then we acquire that and we can even create new things by recombining things that we acquire from different people . So this kind of cultural transmission of knowledge and ideas leads to an idea that you call the collective brain Well uh the collective brain emerges when people are learning from each other because information is flowing around from different minds. And once you have this view, the ability of a society to generate innovation or creative ideas, this process of cumulative cultural evolution that we referred to before is going to depend on the size of the population, the social interconnectedness among individuals because that allows the information to flow and the cognitive diversity in those minds. So you're actually going to get more creativity and more innovation out of a population when you have a larger population that's more interconnected and more cognitively diverse. And that's the collective brain. And you can see this in places like Silicon Valley, for example, where lots of people are interacting with each other, lots of people are learning from each other, uh and things are able to progress relatively quickly because people are building very rapidly on top of what other people have bu ilt. That's right. And you see this all over the place. So for example, when the when railroads were spreading across the US or in Sweden or in Germany, when a town got hooked into the larger collective brain, you begin to get more creative products coming from that town. Just the simple physical link. This touches on something that you call gene culture coevolution. Um what does this mean? Well, one of the key elements of human history that is really emerging now is that a lot of the interesting aspects of our physiology, anatomy, and biology were actually driven by selection pressures created by cultural evolution. And so uh one of the best studied cases of gene culture coevolution is the uh spread of fire, uh making of fire and and cooking. And so if you look at our anatomy and physiology, our digestive tract, and you compare it to other species, our fellow apes and stuff, we seem to have uh stomachs that are too small, colons that are too small, we have these tiny teeth, but these actually make sense once you realize that we've long been a primate that cooks its food, because cooking acts as a kind of pre-estidig on, food food processing more generally. And then this allowed natural selection to reduce the size of our stomachs, shrink our colons, give us these small teeth, because we do the digestion in this cultural way by taking advantage of fire and cooking. But of course we don't innately know how to make fire or cook, so this is something that is completely culturally transmitted, but then has dramatically shaped our physiology and anatomy. Another example of how our genetic inheritance and cultural practices are intertwined has to do with uh the practice of monogamy and testosterone levels in men. Uh tell me about this research, Joe. Yeah, so uh this is one of these things where the assumption that everybody was monogamous, people began to make generalizations, and and one of the things that they generalized is that testosterone declines over men's lives. But then anthropologists began to study other societies and looking and comparing what happens to men's testosterone in polygynous versus monogamous societies. So the standard result from monogamous societies is that men't testosterone declines after they marry, and then it declines again after they have their first child. And this makes good sense in in uh you know comparisons with other species because declines in testosterones are associated with fatherhood in other species. You're beginning to engage in the nest, you've stopped your pursuit of mates, and you're not engaging in much competition with other males at this point because you're moving into a fatherhood phase. But in polygynous societies, we don't see the decline, which fits the theory really well, but it just shows how institutions, whether you're going to have polygamy or anogamy, affects the endocrinology of human bodies. And so you need to think of cultural endocrin ology. So the institutions affect the hormonal uh life cycle patterns. So we've talked about all the ways in which history influences our culture. Culture then influences not just our psychology but also our biology. That feeds back into the whole cycle and can influence history again. Talk about sort of the role that this is playing in transforming our understanding of our minds and our societies. Because I think when most of us think about human psychology, you know, we tend to think of it in terms of what's happening inside the individual brain, what's happening inside this one person's head, and really what you're painting is a picture that is far, far larger. Yes, that's right. So in the picture that I'm painting, our institutions, our langu,ages and our technologies feed back and they shape our psychology. Now, of course, that what we just talked about was gene culture coevolution, so in the long run, they might affect our genetic evolution. But what's underappreciated is how much these things shape our psychology in the short term, because our minds have evolved through this gene culture coevolutionary process to adapt developmentally as we're growing up in these different environments. So something like our cell phones, you know, are going to affect things like our memory and our attention. Uh so they're actually changing how uh things are processed in our minds. One of my favorite examples of this is, you know, for most of human history, people didn't read. It was really not until the 16th century that large segments of the population began to read. But when you learn to read as a child, it actually reshapes the wiring in your brain so that you get uh thicker corpus c allosum, that's the information highway that connects the right and left hemispheres. You get specialized circuitry in your in your in your left ventral hemisphere, and you get more whole brain activation even when you hear spoken language. So it doesn't just affect the reading. It actually affects how we process spoken language. So it's just a case where a a cultural practice learning to read actually changes a bunch of things about our brains and about uh how we take in information