Wired for Culture: Origins of the Human Social Mind
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Let’s assume the value of the help the altruists provide exceeds the costs to them of providing it. Maybe this is something as simple as allowing someone to shelter in your house during a lightning storm. It costs you almost nothing, but it could save that person’s life. If people with this disposition can identify each other and then behave as we have assumed, two things will follow. One is that people carrying the disposition will be more likely to survive and prosper from the mutual help they provide, and this will make it more likely that the gene or idea survives and can get passed on to someone else. If it is a gene, it will spread in the usual way as people who carry it will produce more offspring. If it is an idea, it could spread by people observing others and then copying this successful strategy—it would then spread by social learning. The second thing we can expect is that as this tendency to help becomes widespread in this group, cooperation will come to take on the diffuse character that we recognize in some of our own actions. We could even think of the emotion as something akin to modern feelings of nationalism, but at this stage we might think of it as a kind of tribalism, a partiality toward others in your group, or others like you. Being among these people but not being a helper would be like being at a party without anyone noticing you.
It is an idea of such simplicity that we must wonder if it could lead to anything of importance in real social life. In fact, William Hamilton anticipated our imaginary scenario in 1964. Hamilton imagined a gene that had three simultaneous effects: it causes its bearer to have some sort of recognizable external marker; the gene grants the ability to recognize others with the marker; and it gets its carriers to target assistance toward others who have it. Richard Dawkins later named these hypothetical genes greenbeard genes as a vivid way of calling to mind the mechanism by which such genes might recognize copies of themselves in other bodies. The idea is that those with the gene produce a conspicuous marker that allows those carrying the gene easily to spot each other and then direct their assistance toward them, and only toward them. We needn’t take the green beard literally; it is simply any kind of conspicuous marker; maybe ginger hair or blue eyes, misshapen ears, or the wearing of a particular kind of hat.
It is tempting to caricature the greenbeard idea as little more than an amusing anecdote. And it is fair to say that greenbeard genes have long been regarded as fanciful playthings dreamt up by theoreticians. The charge against them is that they require an implausible combination of three effects from a single gene. Why should a gene that produces some conspicuous marker also be linked to an ability to recognize others with it, and then to behave altruistically toward them? There is no reason. If the gene did produce more than one effect, it is just as likely to be for a taste for lemonade or a preference for cloudy skies as for helping others. If it is easy for us to imagine a gene having all three properties, this might be because we have minds that have already managed to understand the power of cooperation. But we must act as if this system could arise in other animals that do not have our sophistication and therefore the single gene would have to cause all three effects at once.
In fact, some remarkable evidence lends plausibility to the idea of greenbeard genes, and hints at parallels to human behavior. There is a species of fire ant (Solenopsis invicta) in which workers carry a gene that causes them to kill queens in their nests, but only queens who don’t carry a copy of this gene. Most ant species have just a single queen, but in this species there can sometimes be more than one. The ants recognize queens that lack this particular gene because those queens produce a chemical that appears on their outer surface. Queens that do have the gene don’t produce this chemical. Workers who carry the gene recognize the chemical, and then attack and kill the queens that produce it: her green beard is her death warrant. These same workers avoid attacking queens that don’t produce the chemical.
This is just the reverse of the usual greenbeard story, but the mechanism is the same. Workers carrying a particular genetic trait are able to recognize queens that don’t, and execute them. Their behavior is an act of altruism toward their brothers and sisters, who will make up a sizable proportion of the workers in the nest. It is an act of altruism because by killing the queens who display the chemical, the killers ensure that she will not produce offspring that would compete with their siblings.
Whatever one thinks of this example, it is difficult to avoid the suggestion of parallels to human xenophobia and bigotry—the ants direct their hostility toward someone else solely on the basis of some identifiable external marker or characteristic. Another instance of a greenbeard gene gets those with an external feature to help each other. Among the single-celled amoebae or slime molds, individuals normally live a solitary existence. But at times of food shortages they form into towers of many thousands of individual cells. Amoebae near the top of the tower form part of the fruiting body or spore cells that will reproduce and form the next generation, but the others in the tower will die. Only a lucky few get to reproduce so this means that, for most of the amoebae, building the tower is an altruistic act. But in one amoeba species the altruism is more focused. Some individuals carry a gene that makes a protein that is expressed on their outer surface. This protein causes them to stick to other amoebae that express the same protein, but not to amoebae that lack it. Experiments show that by sticking to each other, these amoebae exclude other amoebae that aren’t sticky, and this means the sticky ones are more likely to get into the fruiting body at the top. The gene for this sticky protein simultaneously fulfills the roles of producing a marker, recognizing those with it, and then assisting them. It creates a prejudice to favor those who are like you.
Still, our lives are not as simple and rule-bound as those of ants and slime molds. Our social lives are complicated: we miss things or mistakenly help selfish people, we blunder into a situation not knowing what to do, and people try to deceive us—impostors, con men, liars, and other tricksters are always lurking around looking to take advantage of someone’s good nature. Can this greenbeard altruism still evolve? Evolutionary biologists often study questions such as this about the success or not of various strategies, using mathematics to represent the interactions among groups of imaginary players who suffer or enjoy imaginary outcomes. These mathematical models describe different strategies that players can adopt, and then ask how these strategies fare in competition with one another. The strategies can even be altered to see how this affects their success. I have studied just such a model for this case and it turns out we can make mistakes, or simply fail sometimes to provide help, and still the greenbeard altruism gene will prosper so long as two things are true. One is that the altruists need to help each other at least some of the time; and the second is that altruists (the greenbeards) help other altruists more often than they help selfish or non-cooperative people.
This makes sense. If altruists help each other even just some of the time, but avoid helping non-altruists or non-cooperators, collectively the altruists will be better off than the non-altruistic or selfish players who never help each other. Avoiding selfish or uncooperative people is important because helping a non-altruist means helping a competitor to the fledgling mutual aid society. This raises the possibility that natural selection has favored in us a heightened sensitivity to detecting what we might think of as social cheats or free riders, people who might take advantage of others’ goodwill without intending to return it—they are the enemies of the mutual aid societies. Remarkably, the evolutionary psychologists Leah Cosmides and John Tooby have proposed just this capability in studies of human cooperation. Here is one of their examples. You walk into a bar and want to find out who is following the rule of having to be over the age of eighteen to buy an alcoholic drink. There are people of all ages in the bar; some have drinks and some don’t. Which of these people should you check to work out who is following the rule? Should you target young people or people with drinks? Most of us instinctively realize that it is people with drinks—and especially young ones—who can potentially tes
t the rule. You could find out the ages of all the people without drinks, but this alone would tell you nothing about whether any of them individually is likely or not to follow the rule. And this is Tooby and Cosmides’s point: without even thinking about it, our brains instinctively know how to detect the cheats among us.
The rules that guide our cooperative behaviors toward others lead to an important “principle of information,” which if followed not only makes altruism possible but profitable to the altruists. It says that if we know enough about someone, we can make a decision about whether to cooperate; but if we don’t, it is better not to cooperate, because you might just be helping a selfish person. We can think of the principle this way. Let’s allow i (for information) to stand for a number that can range between 0 and 1. An i of 1 says you are certain the other person is an altruist and an i of 0 says you have no confidence at all. Then the principle of information says our actions should be guided by this rule: that i multiplied by the benefit you provide to someone else must exceed the cost to you. This can be written as i × b > c.
When we are certain the other person is a cooperator (i is 1), we should help if the help we provide more than pays for the costs to us of giving it. This rule makes sense: only when the benefits the altruists dole out to each other make up for the costs of providing them do they prosper as a group. The action might be something like the example I gave earlier of providing shelter to someone during a storm, or you might give someone some information or hold a door for a weak or disabled person. These actions cost you little but can be of big help to the other person.
The principle of information reveals more about our evolved psychology when we consider what it says about how we should behave when we don’t know much about another person. By “should” here, we mean behave in a way that will serve our interests. Not knowing the other person well means that i is less than 1. Following the rule, it says we should never cooperate when i = 0. From our definition of i, when i = 0, you have no information about the person, and this means you are just as likely to help a non-cooperator as a fellow cooperator. For example, parents often tell their children, “Don’t trust strangers.” There is no particular reason to believe that a stranger is someone who will take advantage of you (a stranger to you is, after all, familiar to someone else). But not knowing what strangers are like, this has probably been a useful rule to follow in our past, and it is the rule the principle of information predicts.
The situation that is most relevant to our everyday lives is when i lies somewhere between 0 and 1. When i is a small number, it tells us that we are not certain whether the person we are helping is a cooperator. A small i also makes it hard for i × b > c, and so the rule tells us to avoid cooperating with people we don’t know very much about. The reason is that in effect the benefit you provide has to be discounted by the likelihood that it might go to someone who does not share your altruistic disposition. A more optimistic view is that the rule tells us our best strategy is maybe to cooperate but only on small matters. That way if we are wrong about the person, they don’t gain much at our expense. This gives cooperation a way of gaining a foothold and then larger acts of cooperation can follow if the information you gain leads you to believe someone is a cooperator.
The principle of information can be seen as a psychological disposition that puts great emphasis on identifying traits in others that we think tell us something about the likelihood that they are a fellow cooperator. It might be why we are so sensitive to such things as how people dress or speak, and what their manners are like. These are not necessarily good indicators of what someone is really like, but natural selection will have favored any tendencies with a high enough accuracy rate that they have worked in the past. Our simple model tells us we don’t even have to be accurate; we just have to be more likely to help someone who is an altruist than someone who is not. Natural selection seems to be telling us that it might often be useful to “judge a book by its cover,” at least if that is all you have to go by. Of course, in any given circumstance, other factors can override these rules. But our all too easily felt prejudicial emotions might just be natural selection’s way of making sure we follow an evolutionary rule that worked for our ancestors. If in doubt, the rule says, it is better to avoid the risk. Prejudicial emotions have no place in the modern world, but wariness of strangers or of people unlike ourselves might have deep origins in the evolution of cooperation, not so different from what we saw with the fire ants.
Incidentally, evolutionary biologists will recognize the principle of information and its simple rule as the same one that governs our altruism toward relatives. One of the most famous rules of evolutionary biology is called Hamilton’s rule, named for the same William Hamilton who first thought up greenbeard genes. The rule says we should help relatives when r × b > c. Here b and c are the same as for greenbeards but r is now your genetic relatedness to someone else, rather than the “information” you have about them. By “relatedness” we mean roughly the percentage of genes you have in common by virtue of sharing parents, grandparents, or other ancestors. Hamilton’s rule tells us why siblings (r = 1/2) are more likely to help each other than they are to help their cousins (r = 1/8). Hamilton’s rule also tells us why strangers (assume r = 0) are unlikely to help each other, and why clones (such as the cells in your body, r = 1) are only too happy to assist each other.
In fact, the connection between the greenbeard principle of information and Hamilton’s rule is closer than we might expect. The quantity i in the principle of information can be thought of as your relatedness to someone else on the altruism gene (or idea) itself. The greenbeard is just a model of one gene or idea helping its relatives and the green beard is how it recognizes them! You might be unrelated to someone else on all your other genes, but you just might share this one gene (or idea). If we think about it, the familiar emotions of nationalism might be how our impulse to act altruistically toward certain others whom we think share our dispositions manifests itself. If this sounds familiar to some of the discussion in Chapter 2 about our “special and limited” form of cultural nepotism, that is so. The green beard is a way of identifying someone who is related to you at your altruism locus.
We should not be lulled by all this discussion of cooperation into thinking that the greenbeard style of altruism simply helps others. Our cooperation evolves because altruists effectively surround themselves with other altruists and thereby get back as much or more than they put in. In fact, the self-interested nature of greenbeard altruism is revealed most clearly when we realize that once cooperation spreads and becomes the norm in society, a new kind of cooperator can arise that is less discriminating than the greenbeards. This cooperator doesn’t look for others like itself, it just indiscriminately helps everyone. We can think of them as Good Samaritans—they are kind without first judging what someone else is like. If cooperation is widespread anyway, the Good Samaritans will fare no worse than the greenbeard altruists. Good Samaritans might even do slightly better by virtue of not wasting time and effort trying to work out who is a cooperator and who is not.
However, the Good Samaritans create a problem for the altruists who follow the greenbeard rule. The presence of Good Samaritans makes the society once again vulnerable to selfish or non-cooperating people who can flourish by taking advantage of Good Samaritans. These could even be other green beards who might have a tendency to cheat when they can get away with it. Selfish people will grow in numbers, but at the expense of the Good Samaritans, whose numbers will now dwindle. The greenbeard altruists on the other hand are less vulnerable, just so long as they continue to recognize each other even just a little bit better than they recognize the reemerged selfish cheaters. If they can recognize the cheats, they will once again drive them out, or at least down to low numbers. At this point Good Samaritans can reappear, and this cyclical process will go on forever, with societies always containing a majority of greenbeard cooperators, but some numbers also of Good Samaritans and selfis
h individuals.
This tells us two things. One is that greenbeard altruists—and by implications ourselves—are not so much “good guys” in white hats who help everyone as “shrewd guys” who direct their aid strategically. When it comes to cooperation, we are far more like venture capitalists than Good Samaritans. We are willing to invest in other altruists like ourselves because we derive returns from having them around. Our investment is in the society of cooperators, not in anyone in particular. Cooperation itself becomes something like a “common good,”—a resource, like common grazing land, that everyone benefits from but that must continually be replenished to avoid being used up. The second thing we learn is that our cultural setting will always strongly favor those who are vigilant about and good at detecting selfish cheats because they continually deplete the common good of the cooperative society. Good Samaritans may inadvertently imperil our societies by helping people who may not always be deserving of their aid. It is no secret that the Mother Teresas of the world are often treated with a hint of ambivalence, and this could be one reason why. Another we will come to later on.
REPUTATION AND THE GREEN BEARD
SO FAR, we have ignored a nagging problem. If we are like venture capitalists when it comes to cooperation, how do we know whom to invest in? The idea of a green beard provides a useful image, but what if people could produce it without actually being a cooperator. These people would attract all the benefits of being a cooperator without ever having to pay the costs of being altruistic toward others. This is one of the failings of the greenbeard idea, and not just in the setting of human cooperation. If anyone can grow a green beard, then there is no way to tell altruists from selfish cheaters and altruism of the greenbeard variety will never evolve.