22. The Impact of Evolutionary Thought on the Social Sciences 
22. The Impact of Evolutionary Thought on the Social Sciences by Yale / Stephen C. Stearns
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Lecture Description


There is a distinct possibility that humans are currently part way through an evolutionary transition between individuals and groups. The conflict between these two units of selection and levels of organization, between biology and culture, may explain some of the tensions in modern human life. Examples of selfishness and altruism exemplify how these types of selection act on humans.




Transcript



March 6, 2009



Professor Stephen Stearns: Now, today I am giving a lecture, on which you're not going to be tested. Okay? So I'm being an idealistic, academic intellectual today, and I'm talking about stuff which is of general interest and is not going to be on the final exam. So I want you to kick back and enjoy this final lecture before Spring Break, and perhaps it will stimulate some things for you to think about.



If you want to read further about this, you can go to the Resources page and look up Major Transitions, right here, and you'll pick up a commentary written in Evolution to which this talk is relevant; it's structured a little bit differently.



Now I want to give you a little bit of background on my current thinking about this area, because I'm likely to run out of time towards the end; so I better tell it to you at the beginning, otherwise you won't hear it. [Laughs]



I began worrying about this issue of whether we're stuck in the middle of a major transition, between individual and group, about now fifteen to eighteen years ago. And in 2005/2006, after I finished being chair of the department, Yale very kindly gave me a full-year sabbatical, and I spent the year reading widely in how evolutionary thought had impacted psychology, anthropology, political science, economics; all of these cognate fields that have something to do with human behavior, and that bear on the issue of whether or not we have been selected to behave in certain ways in social contexts.



And I'm going to give you today a talk that describes my motivation to do that, and the preliminary conclusions that I came to. And you can read about that in more detail in that commentary in Evolution, if you wish. You just download the PDF from the website.



When I finished all that process, and I thought about sitting down to write a book, which I did last summer, what I discovered is that there were certain key elements in the logic of the argument that simply were not well scientifically established at this point. And I therefore had to make a decision: Do I remain agnostic, or do I go for a colorful and publication worthy thrill? I decided to remain agnostic.



I could have published a book that made claims that probably would've gotten into the New York Times fairly easily. And I decided not to. And basically the reason for that is that I'm a natural scientist, and I don't want to make claims, to the broadly educated public, about the nature of the human condition, without having all the links in the chain of logic pinned down by experiments.



I think it's perfectly valid to do what I'm doing today. I'm going to advance some hypotheses. I'm going to tell you where they are or where they are not well established; and I think that by doing that I can show you that there are some really fascinating issues here. But I don't think it would be responsible for me to go out and publish a book, in the general trade industry, that made the central claim.



This is the central claim: That we're stuck in a major evolutionary transition. We're feeling the pain. The pain is caused by the fact that there is a conflict between individual interest and group interest, and that conflict has not been resolved, and the selection mechanisms that have been pushing us in that direction are starting to break down.



So it's an interesting idea. And, in fact, the feedback I've had from that commentary is that people were absolutely amazed that Evolution allowed me to publish it, and it was deeply interesting and troubling, but that clearly it's still an open issue. So I think that the colleagues I have in the evolutionary biology community agree that it's interesting and unresolved. So all of that upfront. Okay, let's go.



This has to do with the impact of evolutionary thought on the social sciences, and its implications for understanding what we are. I begin with some of the remarkable observations that led me to these ideas. I was an early Vietnam War protestor. I was deeply concerned with the issue of why I should die for my country; back in 1966/1967.



Well here are some, to me, really incredible observations about human behavior. The first day of the Battle of the Somme, July 1st, 1916. One day. The British Expeditionary Force lost 58,000 men, in 24 hours. That's as many as were killed- American were killed in the entire Vietnam War, over about eight years.



The British continued to attack until winter. They lost another 420,000 men. During that time the French lost 200,000; the Germans lost half a million. So, over six months more than a million people, led by idiots, died in useless slaughter. And here's the point: throughout the next two years, young males continued to volunteer for service and to obey their leaders. That's one hell of an observation. It tells you something very deep about humans.



Now, we are susceptible to lots of other social emotions besides patriotism. We express love, empathy, compassion, guilt, shame, embarrassment, duty and honor; and we do it by the age of three. Paul Bloom, in the Psych Department, has watched the development of the moral emotions in humans, in his own children, and says that by age three they had already committed all of the Seven Deadly Sins, except lust. Okay?



So it looks like the susceptibility to moral emotions is innate. People who lack moral emotions we call psychopaths, or sociopaths. They commit crimes and end up in prison. We will trust strangers enough to engage in economic transactions; we'll even do it on the web, with our credit cards. That's pretty amazing too.



There's a great story in Paul Seabright's book about this, where about 1500 years ago traders show up on the banks of the Volga River, to trade with the Khazars; and the Khazars are a bloodthirsty people, but they've got money. Right? So the goods are put down on the bank of the river. The traders go away. The Khazars come back, look at the goods. They place a pile of money over there. The people never see each other. They go back and forth for two or three days, kind of bargaining, by just putting stuff down on the ground, until finally a stake is pounded in, and it's a deal, and one side takes the money and the other side takes the goods.



It is not clear under what circumstances people can trust each other enough to engage in an economic transaction; especially not since Bernie Madoff. We are willing to pay taxes to the government, in return for services that benefit the entire country; not just ourselves, not just our relatives.



And if you look at the major religions of the world, you'll find that their central moral messages are mostly about stabilizing social behavior. Okay? So in Christianity we've got the Sermon on the Mount. So you should be gentle. You should be merciful; that means you should be forgiving. You should make peace; so you should stabilize social conflict. If you got angry with your brother, you're going to be guilty before the court, and the central Sermon on the Mount statement is do unto others as you would have them do unto you.



If we look at Islam--this is in the Koran--so do good to your parents and kinsfolk and orphans and needy, and to the neighbor of your kin and the neighbor not of your kin, and to the fellow neighbor, and to the wayfarer. Look at how that sentence neatly expands the moral circle that Peter Singer talks about, of how far, how distantly related does something have to be to us, for us to feel like we should behave morally towards them? And the Koran lays that out very explicitly. Forgive people who offend you. Give to those who refuse you. Stretch a hand of peace to the one who quarrels with you; very much like turn the other cheek. Okay?



Another great tradition, Confucianism. Love others; be benevolent, charitable and kind. Okay? We're now in sixth century BC China. Do your duty to honor your family and neighbors; social relationships. And what you don't want for yourself, don't do to others. So a neat little inversion of the Golden Rule in the Sermon on the Mount, in Confucius 500 years earlier.



Well the idea behind this is that things like nationalism and religion are culturally transmitted value systems, and biology is providing handles on which those value systems can pull. And the way it does it is very probably by genetic influence on hormones and their receptors. There are probably other mechanisms as well, but that's at least one of them, and some of this stuff is now under experimental investigation.



So, for example, oxytocin. If I want to stabilize trust, I can give people lots of oxytocin, and they'll cooperate and trust each other a lot more than they will if I give them an overdose of something like testosterone. Okay? So testosterone is more or less more aggression, and oxytocin is more trust and cooperation. In other words, we contain within ourselves physiological mechanisms that if genes want to, they can dial up and down like rheostats, and that will have some kind of indirect influence on the general level of either aggression or trust, in a group.



So my questions about these kinds of problems are, are we in fact stuck in a major transition between individual and group? Has it gotten stuck because the selection mechanisms have broken down? Has the breakdown left us in a state of tension, caused by conflicts between individual and group? And do these individual group conflicts define a significant part of the human condition?



You know, once you've seen that list, it's easy to start telling just-so stories, and throwing up lists of things: unions in conflict with management; Democrats in conflict with Republicans over the role of the individual and the role of society in constructing government policy; Communism versus Capitalism; the way I feel about whether or not I should donate to a charity or keep the money for my wine cellar. You know? There's lots of different contexts in which that can happen.



You can ask yourself, well what would happen if we really went right through the major transition? Well, some things have. Eusocial insect colonies have gone through this transition; and they are defined by reproductive suppression. So if you were living in a state in which the opportunity to reproduce was in fact determined by the group and not by the individual, that would probably be a pretty strong signal that you had completed the transition. We're nowhere near that at the moment.



However, we are certainly in a circumstance in which some of that happens. The Chinese One-Child Policy is an indication of that. The sort of political correctness of the environmental movement that encourages people towards zero-population growth and only having two children is that kind of thing. So we haven't made the transition, but certainly there are signals that we're partway into it.



So here are the hallmarks of major transitions. And I want to remind you of this; this is from the lecture on genetic conflict, and it's also from the lecture on major events in evolution.



In a major transition, things that were previously independent fuse into a larger whole and lose their independence. Then units in that larger whole specialize on different functions; they achieve a division of labor. That division of labor has to be stabilized, and it then integrates the new unit and improves performance, in competition with like units. And the cohesive integration, that's needed within the group, requires suppression of intra-group conflict, among previously independent units, so that you can be effective at competing with other similar groups. Often during this process a new system of information transmission will emerge.



So this is something that's happened four or five times in evolution: prokaryotes to eukaryotes; single-celled eukaryotes to multi-cellular organisms; multi-cellular organisms into family groups; family groups into insect societies; and in mammals into naked African mole rats and dwarf mongooses, things like that.



And in humans the new system of information transmission is cultural transmission, with language. So we now have a parallel genetic and language transmission of information, and they can be in conflict with each other.



So to see if these ideas make any sense, we need to evaluate hierarchical selection. That sets up conflict between individual and group. We need to see what kind of cultural group selection might be going on, to select for cohesion, promoting group performance. We need to see how conflicts are generated and resolved, in a selective hierarchy; so the origins of group cohesion.



That brings us to the contentious subject of whether there are tribal social instincts and how they might originate. I would claim that if I were to take you guys and put you on a desert island, and call half of you greens and half of you blues, and divide the territory of the island in two, that you would develop green identity and blue identity, within about six hours, and start organizing for competition. I think humans self-organize to do that real quick. There have been experiments done on that.



Then, as part of the claim of the overall hypothesis that we're stuck in the transition and we're probably not going to complete it, is group selection, biological and cultural, breaking down, in our current civilization? So let's run through that.



Here are the basic issues in hierarchical selection. The thing you need to focus on is the distribution of variation within and among units. So if most of the variation in the population is within each group, and the groups don't differ too much from each other--they're all kind of motley, but they're all similarly motley--then you won't really have very much opportunity for group selection. But if the variation in the population is homogenous within groups, and different between groups, you have a much bigger opportunity for group selection.



The strength of selection, in part, is going to be determined by the rate at which units are born and die. So if the little units, inside the groups, do things very rapidly, and the big units, the groups, do things very slowly, then that's going to prejudice things towards the individual and away from the group; and vice-versa. Okay? Then you need to look at the correlation of reproductive success, with trait variation at each level. That just takes us back to the first lecture in the course. Right? Conditions, four conditions, for natural selection.



And when we think about how cultural selection might work, when biological group selection is usually ineffective--and, by the way, there've been a lot of publications on this recently, and they've been in high-end journals, like Nature and Science--we can see that one of the things that happens is that social norms spread rapidly through imitation.



So if, within a group, a new social norm arises, it can spread through that group and homogenize that group pretty rapidly, simply because we are creatures that learn rapidly, and we imitate others, and we respond to social pressure, and to things like political correctness. This is essentially a description of the spread of political correctness.



You can accelerate that spread with moralistic punishment, and that will--that's a very, very powerful force. Moralistic or altruistic punishment is the following: I notice that Blake is doing something that is violating a group norm, and I punish her for it. Blake doesn't like that, and she elicits a- imposes a cost on me, for having the effrontery to having punished her for doing that. However, my punishment continues, and is strong enough finally to force Blake to obey the group norm.



In the process I have--she's really elicited quite a bit of cost from me. Okay? Perhaps I'm battered and miserable, but she's behaving now. Well that's benefited everybody in the group, at my cost. If there is any selection for people who behave that way, who go around going, "Nah, nah, nah, nah, nah," that will actually accelerate the spread of social norms, and rapidly make them uniform, within groups.



Now part of the process of cultural group selection would be the extinction of a group, or the reproduction of a group. And the extinction of a group culturally doesn't require biological group extinction. The Gauls did not die when they were conquered by the Roman Empire, and stopped speaking Celtic, and started speaking in Latin.



There was a horizontal transmission of a language that Latinized France and made it no longer a Celtic, quasi-Germanic society. The people didn't die, but the culture died. Or think of Tibet, if you want a current day example. And cultural group reproduction doesn't require biological group reproduction. So the Romans basically reproduced their culture in France, 2000 years ago.



A horrible statement, isn't it? Very true. I would challenge you to find any individual who has ever lived on this planet, who has lived at a time in which no war was going on anywhere on the planet. Their own particular local group might not have been in warfare, but it's almost impossible to find a time in which war is not going on.



I could put up a slide like this, by the way, for China, and I'd have to redefine the Y-axis, because the number of deaths is so much greater. It's difficult to reconstruct the demography of Central Asia, or of Africa, but one can be pretty sure that similar graphs would be put up. And the take-home message, when you look at this history, is that humans--we think about how nice we are and how aggressive those chimpanzees are, and stuff like that.



But if you were another species, looking at the human race, you would say, "Oh, they are B-A-M-Fs; they are bad-assed mother-fuckers. [Laughter] And I use that--I thought, should I use that term in an introductory biology lecture or not? Should I drop that particular linguistic bomb into the mix? And I decided yes, because I want you to remember it. Okay? That's why I did it.



Now we have some other evidence. Troy and Jericho. You go back in Jericho and you go through forty-two layers of Jericho getting burned down. I've been to the museum in Istanbul and I have looked at the excavation layers of Troy. The Trojan War was sack number nine; or no, sack number six I think. And so Troy was burned down a total of about fifteen times.



You look into our great mythologies, and they are all structured around warfare: Iliad, Mahabharata, Niebelungenlied. You look into the histories of any of the civilizations that we have at hand, you'll find that there's war. Okay? So there's a lot of opportunity for group performance to be tested by lethal competition. That's the take-home message of the prevalence of warfare.



Now the genetic differences between early human groups probably were long enough- large enough for lethal inter-group competition to account for the evolution of altruism and cooperation within the groups. In other words, we all have to band together, because if we don't cooperate with each other, those guys next door are going to wipe us out.



And the necessary condition for that, in the theoretical models, is reproductive leveling within groups, that's generated by food sharing beyond the immediate family, that's generated by monogamy and generated by other cooperative means.



So this is--I told you, this stuff is getting published in Science and Nature. This is Sam Bowles. Sam's a Yale College graduate. His dad was Ambassador to India, under John Kennedy, and Sam's an economist. And he's actually a fairly committed group selectionist--so mainstream evolutionary biologists look on his work with some skepticism, because of that--but he's very much concerned about whether or not there were conditions that would tend to take the selfish Darwinian model of short-term selfishness--homo economicus; strictly short-term, selfish, rational--and tend to convert that into a person who is more socially empathetic and more cooperative, at least within the immediate group. So he's concerned with that kind of process.



Well we would very much like to know, if this is going on, how a social norm, like food sharing or monogamy, gets fixed in a group. Culture is very real. Cultural transmission is there, and it's important, and it's different from biological genetic transmission, and it's a fact on the ground. Okay? And you will find that, if you look across the face of the earth, tremendous cultural variation. And a group of people, who are centered around Sam Bowles and Pete Richardson and Rob Boyd and Joe Henrich and some others, are arguing that cultural group selection will explain the spread of social norms, that promote group cohesion and group performance.



So that one of the things that happened is--language and cultural transmission emerged in the human lineage, and became important probably between about 100 and 50,000 years ago--is that this process could start. And it's been commented on.



There's a great Muslim historiographer named Ibn Khaldun. He was kind of the Henry Kissinger of his day. He was born in Andalucia, in Southern Spain, and he was active politically in kingdoms there, and in North Africa, and he became the leading professor on the Law Faculty in Cairo.



And when Tamerlane, Timur the Lame, invaded Syria--Timur the Lame was one of Genghis Khan's descendants--Ibn Khaldun went up, with the army from Egypt, the Muslim army from Egypt, to defend Damascus, and he was in Damascus when it was besieged, and Tamerlane asked to meet him, because he was such a famous guy.



So he got lowered over the walls of Damascus, in a basket, and was taken to Tamerlane's camp, and gave us the only written description of Tamerlane. Tamerlane himself was illiterate. Okay? So this guy had an interesting life. He also had the tragedy of standing on the breakwater at Alexandria, watching the ship, that was bringing his wife and children in from Spain, sink in front of his eyes, and they all drowned, in front of his eyes. So he was a guy who was marked by intense political and human experience.



And what he said was this: It's religious propaganda that gives a dynasty its power. And he claims that that's how the Arabs managed to achieve these great victories, at the beginning of their conquests in 632, when they radiated, after the death--well it started with Muhammad, but shortly after his death there was a real breakout and they conquered the Middle East and spread across North Africa very rapidly.



And in one case they were fighting at Yarmouk, with 30,000, against 120,000, and against Heracleus, who was in the Eastern Roman Empire, against 400,000 and neither of those big armies could withstand the 30,000 Muslims who were fighting them, and he claims it was religious propaganda that gave that cultural force to that army.



I recommend the Muqaddimah. It's a very interesting piece of work, a brilliant piece of work, by a guy who was writing generally about problems of politics and aggression and stabilization, role of culture, in human life, long before the Social Sciences really emerged as a field in the West.



How does a norm spread through a group? How does something like that propaganda spread through a group? Well we have--and this is one of the places where perhaps biology is providing a handle for culture--we have a number of learning mechanisms. One of them is to copy the successful, the dominant, the frequent.



You may not have thought explicitly about it, but the whole point of education is to try to keep you from having to learn everything by trial and error, so that you don't have to repeat all the mistakes of all of the previous generations of all the humans who ever lived, in order to get to a certain state of enlightenment, by the time you're twenty-one-years-old. Well how do you do it? One of the ways is this. But that won't explain the spread of an individually costly norm, like me trying to punish somebody for violating a social norm.



One can punish defectors from group norms, even if it costs you. That's a very powerful force, and it's powerful enough to overcome inherited biological tendencies. So it's powerful enough to explain why we get celibate nuns and priests, why we get to declining birthrates, why we get other things that reduce lifetime reproductive success.



How do we get it? Well it's not clear. By the way, there are now--if you ever wanted to write a paper on this, there are three or four models in the literature about how altruistic punishment might evolve, and under what conditions it would be stable. You need to have pretty strong inter-group conflict for it to work. And why would that happen? Why would we get altruism?



Okay, here's Nathan Hale, and his individual fitness was strikingly in conflict with the social cohesion that was needed for the revolutionary American army to resist the British. Okay? So this guy graduates from Yale, and he's a school teacher down in New York, and he's spying for the American Army, and gets caught and hanged. And he was executed at age twenty-one. He left no children. He said famously, "I only regret that I have one life to give for my country." And he's a social hero and a Darwinian madman. [Laughter] Okay? That's the tension.



So how can you resolve that kind of conflict? Well there are actually a lot of ways to do it. I've mentioned some of them already, in the course. You can convert individual stakes into common stakes, so that whatever an individual is going to get, out of living its life, is going to be identified with whatever a group can get out of performing better.



Ecological constraint can be imposed on the group; the threat of outside risk will stabilize interactions within a group. One can cooperate with and sacrifice for kin; that's just straightforward kin selection. You all now know how that works. You can punish defectors; that's the punishment of violators of social norms, altruistic punishment.



You can stabilize the division of labor; that will certainly reduce conflict, by making sure that say all the people who are making shoes are not in conflict with all of the people who are making shirts. They're actually cooperating with each other; they're each making something that the other one needs. It's win-win, for them. You can promote reciprocity. There could be cultural norms to promote reciprocity, and that is the basis of trust; and trust is the basis of cooperation. I'll step through these.



How do you convert separate stakes into common stakes? Well you know one of them already. That's how you randomize success. That's meiosis in the parliament of the genes. Once you set up a mechanism that means that every single gene in the genome has the same probability of getting into the next generation, then that is a structure that imposes homogeneity of success, on all of those genes. Meiotic drivers violate it, meiosis stabilizes it.



At the cultural level you can homogenize success with monogamy. So we have the Chinese One-Child Law. You can share food with non-kin. And if competition within a group is not an option, then the only path to better performance is the performance of the whole group. So that's the rising tide lifts all boats part of it.



An example of imposing ecological constraint: We can see in the meerkats, they have sentinels, that altruistically look out for predators and give alarm calls, and larger groups of meerkats have better defense and offense. And if you leave the group--this is a Cape Cobra; here are six meerkats confronting a Cape Cobra. The six of them together have a much better chance of dealing with it, than would one of them alone. And there are Batteleur Eagles and things like that, that are cruising the landscape and that pick off meerkats cats pretty quickly, if they're on their own.



So if you- if it's very risky not to be in a group, that will increase your willingness to bear a cost imposed by group membership. In this particular species, the cost imposed by group membership is that you can't reproduce, if you're a female, so long as the dominant female's in charge. She won't let you in the group. She'll kick you out if you try to have a baby. That's a pretty strong cost. Nevertheless, meerkats go into groups--okay?--because the alternative is death, within about twenty-four hours.



You can cooperate with and sacrifice for kin. So multi-cellular organisms integrate very easily, because they are clones that originate in a single cell. So they're all 100% related to each other. And you can see the division of labor here, between the chlorophyll producing cell, cells that are producing carbohydrates and cells that are going to be actually reproducing that group. This is in a multi-cellular alga. This is a model for the origin of multi-cellularity.



It's well known, from anthropological work, that many hunter-gatherer groups consist mostly of close kin. There are interesting analyses of asymmetries in that, and there's big controversy over some of it. But it is nevertheless, I think, a pretty safe broad generalization that many human groups consist of close kin, and therefore we can expect that kin selection has been operative, and that it has been promoting cooperation, altruism and sacrifice.



You can punish defectors, and in a multi-cellular body one can, for example, eliminate the defecting cancer cells through apoptosis. So there certainly are ways that the immune system does attack, and partially succeeds in controlling cancer cells. And in social groups one can punish those who break social norms. So I'm going through a series now of analogies between multi-cellular organisms and potentially emerging cultural-level group integration in humans.



You can stabilize the division of labor. In biology that's done with epigenetic mechanisms; epigenetic information is what stabilizes development and makes sure that brain cells stay brain cells, and liver cells stay liver cells. And in culture we've got things over history, like guilds, classes, castes, professions, job descriptions. There are all kinds of ways that the division of labor gets stabilized culturally.



You can promote reciprocity. In evolutionary biology it's much easier to promote reciprocity in a two-dimensional surface where people are playing against their neighbors, than in a very well mixed kind of liquid. That's the basic take-home message of Martin Nowak's work on the evolution of cooperation. And a way to stabilize reciprocity culturally is through win-win economic exchange. So transactions in which both sides profit; that's the basis of business.



So lots of ways to resolve or suppress conflict, but there are some problems. If you're going to stabilize conflict within a group, you very probably need a leader. You need the leader both to direct the collective within the group, and you need the leader to basically take over foreign policy [laughs], to deal with extra group relationships. And in the multi-cellular body, that's been done by the central nervous system, and in the emerging social group, that's done by something like a president.



Well this guy wasn't selected at random, and there are some issues. Groups need leaders. A psychological predisposition to defer to authority is what would permit a strong, unrelated leader to emerge. You might trust your dad or your uncle, but the issue here is why is it that in groups humans actually will trust somebody unrelated to lead them? That's, in other words, going beyond the kin selection model.



Most of us, around the world, really just want to be left alone to do our own thing, and we would like to delegate to leaders this business, this complicated business, of interacting with other groups, particularly if it's aggressive. But that's a double-edged sword. Okay?



Deference, which may have evolved--this may be one of the human social instincts that's kind of a handle on which culture can pull--deference to leadership will let a selfish leader exploit the public. And selfish leaders invade. They've got to be controlled, while they're leading. And this is what the U.S. Constitution is all about.



A group that constrains its leaders to pursue public interest will have a competitive advantage, because they will be internally cohesive. If you have a long series of defecting leaders who are corrupt and who subvert the public interest, you will have the breakdown in social reciprocity and trust, and you will end up with situations which are similar today to Zimbabwe, to the Congo, to Sudan, and other failed states. So this defection is a recipe for the creation of a failed state. Nevertheless, leaders are motivated to defect, if they're selfish.



Well let's take a quick look at some very idealistic people in history who have tried to say we should work for the group good. Christ; the invasion of the Christian Church by the Borgia family, and the remarkable situation of corruption in fourteenth and fifteenth century Italy, where the Borgia's essentially managed to make a personal fiefdom out of about a third of Northern Italy.



Karl Marx, who said a lot of things that were quite similar to Christ, and who tried to describe a very idealistic world in which people were sharing property and were really cooperative and were helping each other, getting subverted by the nomenklatura; and again and again, you find that selfish mutants are invading.



The French Revolution, in 1789; Liberté, Equalité, Fraternité, was a very idealistic attempt to overthrow a selfish aristocracy and establish--kind of wipe the slate clean--and establish a new sort of society that was much more egalitarian. And it rapidly got invaded by this guy, who probably was responsible for more deaths of young Frenchman than any other person in history.



I think that Napoleon's armies lost somewhere between 20, 25 million people; a lot. A very dramatic and very effective piece of data presentation showing the width of Napoleon's army, as it went to Moscow and came back. And it goes in as a river and it comes back as a little line on the page.



So there's a problem with defecting leadership. And when you think about that, you think about deference, patriotism, empathy, trust; where do those emotions come from? Where did guilt come from? Why do we get embarrassed? Do you think that it's conceivable that an adult male grizzly bear is capable of embarrassment? No way in hell. He's going to eat all those babies wherever he can get them. Ditto male lion. Okay? I will forbear commentary on provosts.



Now outrage at defection, where does that come from? Why do we want to punish defectors? We're very sensitive to defectors. We're very, very sensitive to people who deceive us. Why do we have a desire for revenge? Often that is a spiteful, self-defeating kind of a thing. Why do we have an impulse to conform? There's been lots of good psychological studies on this one; we have a frightening impulse to conform.



Well the tribal social instincts hypothesis, that Richardson and Boyd have advanced, attempts to explain this kind of thing. They claim basically that gene culture co-evolution built social imperatives into our genes; that genes use hormones that create emotions, that manipulate our phenotypes; and that those emotions then are the biological handles on which culture pulls. Okay?



So that would be an assertion that our minds are not blank slates, and that we entered the world partially pre-programmed, and that some of the programming is for social interactions. That's a big claim. There's some evidence.



Joe Henrich was one of Rob Boyd's Ph.D. students, and Joe and Rob and Pete Richardson and Sam Bowles and others got money from the MacArthur Foundation to fund fifteen anthropologists to go out and play the Ultimatum Game in fifteen different cultures.



So the Ultimatum Game basically works like this. I walk into a room with you guys, and I've got in my hand enough money to make you interested--let's say I've got $1000.00--and I give the $1000.00 to Blake, and I say, "Blake, here's how it works. You make him an offer, and if he accepts it, that's the deal, you get to keep it. If he turns it down, neither of you gets anything."



If Blake is homo-economicus, a selfish Darwinian model, Blake will keep $999.00, and offer him one, on the hypothesis that one is better than zero. Okay? So that's the Ultimatum Game. And if he says, "That's totally unfair. I'm not accepting it. Go to hell." Then neither of them gets anything. Okay? That's why it's called the Ultimatum Game.



Well all cultures tested rejected complete selfishness. Everybody demanded some degree of fairness. The worst that anybody was able to accept was 200 bucks; so 800/200, that was the worst. They varied in how much selfishness they tolerated, and the amount of selfishness was actually related to the cohesion of the culture.



So the ones that demanded the most--so, for example, the one that would say--say Blake offers you $500.00, and you say no, but she offers you 600 and you say yes, and she only gets 400--that would be the Lamalera whale hunters of Malaysia. They get into small boats, unrelated people get into a small boat and go out to hunt whales, and their lives depend upon each other; it's dangerous business. So unrelated people are cooperating, and they're literally in the same boat. Okay? They're the ones that demand the most fairness.



The ones that demand the least, the twenty-percenters, are scattered, wandering, single-family groups of Native American Indians in the Peruvian jungle. They have very little social interchange and very little economic life, and they are willing to accept 20%; but that's the minimum. Okay?



So it seems that for social emotions, biology is important, culture does make a difference. Biology is providing a principle; culture's setting the parameters. That's kind of like language, the way that Chomsky thought of it.



And it looks like we display a lot of symptoms of group adaptations. The mechanisms that might have selected them are plausible; they're not yet strongly supported. So are we going to fuse into a group identity, or are we going to remain torn between private interests and those of the group to which we belong, which is our current state?



Well, when we went from transition- when we transitioned from hunger-gatherers into agricultural settlements, the relationships among group members decreased, group size increased, and the average encounter was no longer with a relative but with a non-relative. That's a big city. Okay? There weren't any cities before agriculture.



Now we then started getting engaged in large-scale economic exchange, and it both reinforces and erodes cultural group selection. So exchange within groups promotes group cohesion; exchange among groups erodes group boundaries. This is a diagram of global trade a few years ago; the width of the arrows is how much is flowing. It shows, as the current economic crisis just shows so clearly, that we are now globally integrated by economics. So group boundaries are being strongly eroded by globalization.



Our group identity is now multi-dimensional. So it used to be, if you were in a hunter-gatherer band, or even if you were in a medieval guild, that your ethnicity, your religion and your politics pretty much overlap. But it's now possible for people to belong to different dimensions of identity, all at the same time. So you can be a Black Catholic Democrat, or you can be a Black Muslim Republican. Right?



And that didn't used to be possible. Those things are now breaking apart. So the power of cultural group selection is decreasing, because these things are not adding up to push all in the same direction; they're pushing in different directions.



In the evolutionary social sciences, by which I mean basically economic psychology and political science, we're stuck in the major transition between individual and group. There's quite a bit of support for that. The transition stalled, and the breakdown has left us in a state of tension.



But, these conclusions are supported by plausibility arguments, and these plausibility arguments basically only achieve the level of consistency with the evidence. Consistency is a weak logical criterion. There's a lot of stuff that's consistent, but not necessarily true. It is much more difficult to demonstrate necessity and sufficiency. Basically to do that, you have to take the Social Sciences and transform them into the Natural Sciences, with the same standards of experimental demonstration and admission of evidence.



Well that is a long-term, big project. That's not easy. So I say that, at the end, because I don't want to leave you with the impression that this idea, that we're stuck in a major transition, is well established.



I think that it is consistent with the evidence that I know of, but I don't think the evidence is strong. And of course, down in my gut, when I take off my scientist hat, and my teacher hat, and I am sitting there alone quietly at 2:00 in the morning, in my house, thinking about this, I think it's probably true. [Laughs] Okay.



[end of transcript]

Course Index

Course Description


In this course, Stephen C. Stearns gives 36 video lectures on Evolution, Ecology and Behavior. This course presents the principles of evolution, ecology, and behavior for students beginning their study of biology and of the environment. It discusses major ideas and results in a manner accessible to all Yale College undergraduates. Recent advances have energized these fields with results that have implications well beyond their boundaries: ideas, mechanisms, and processes that should form part of the toolkit of all biologists and educated citizens.



Course Structure:

This Yale College course, taught on campus three times per week for 50 minutes, was recorded for Open Yale Courses in Spring 2009.

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