Just as negative emotions such as fear, anxiety, and anger serve to protect us from danger or to increase our competitiveness, other emotions ensure that we are sexually attracted to another individual with whom we could potentially reproduce and that we form a long-term pair-bond that will allow for jointly raising children. Sexual and romantic feelings are elicited by cues of individuals and situations that, as with negative emotions, have recurred millions of times in our evolutionary history. We also have emotions to protect the exclusivity of our pair-bonds and prevent infidelity, such as sexual jealousy. Given the importance of parental investment for social success in complex human societies, parental love for children is an emotion that continues to be active and strong even when children become adults and is eventually extended to include grandchildren as well.
Finally, emotions play a role in establishing and coordinating the cooperative relationships with other individuals that are so important for survival and success in human societies. Natural selection has favored emotional processes that motivate and enhance an individual’s ability to engage in, and profit from, cooperative enterprises. As nicely discussed by evolutionary psychologists Daniel Fessler and Kevin Haley in a 2003 essay, different emotions (and other psychological dispositions that may or may not fit the definition of emotions) affect cooperative behavior in different ways. Emotions such as trust, distrust, envy, and guilt play an important role in the implementation of cooperative strategies.9 One needs to trust other individuals at some point in order to cooperate with them. Cosmides and Tooby have also argued that our mind contains a “cheater detection” algorithm that evolved specifically in the context of cooperation.10 Anxiety or fear of being cheated triggers this cognitive subprogram that monitors the partner’s behavior. Anger may also drive individuals to react strongly when they feel they have been cheated. Kindness and generosity play an important role in cooperative interactions as well. People respond with gratitude to spontaneous acts of generosity and feel compelled to reciprocate in kind. This might explain why subjects in behavioral economics games often violate the assumptions of traditional rational models by demonstrating a willingness to incur monetary costs in order to reward partners for perceived cooperative or altruistic behavior. Envy can play a role in market negotiations such as those discussed in Chapter 8: when actors identify a sizable disparity between parties in the possession of, or access to, valued goods or opportunities, those having less wish to obtain more. In addition to the desire to obtain what others possess, envy includes a measure of hostility toward the more fortunate party. Clearly, the emotions that operate in the context of cooperative interactions also operate in other social and nonsocial domains. When the same emotions operate in different domains, their effects are moderated by the characteristics of the context in which they occur.
Cognitive and Behavioral Algorithms
Until recently, many economists considered financial and other decisions to be the result of rational cognitive processes, and particularly of the rational evaluation of the costs and benefits of different options. Emotions, however, can change the subjective importance of costs and benefits, sometimes leading people to behave “irrationally.” In some cases, emotions lead to irrational decisions because of a mismatch between emotion and situation. (The more a contemporary setting deviates from the ancestral environment, the less likely it is that such actions will be rational from an evolutionary perspective.) In other cases, people make seemingly irrational decisions not because their emotions interfere with rational decision-making processes but because emotions activate cognitive subprograms that lead to behavioral decisions different from those predicted by rational models.
Psychologists and economists used to believe that when people are presented with alternatives and must make a decision, they take all variables into account and behave in a way that maximizes their personal interests. It turns out, however, that in many situations people don’t make decisions based on consideration and rational evaluation of all the information at hand. Rather, they use simple rules of thumb to make quick decisions in response to certain cues. Research by German cognitive psychologist Gerd Gigerenzer and others has shown that people possess “fast and frugal” algorithms, or heuristics, to make decisions in circumstances where economic theory has predicted sophisticated rational decisions. It turns out that the decisions made with fast and frugal algorithms are often more effective in dealing with certain situations and result in better outcomes than the decisions made through rational cognitive processes. In their 1999 book Simple Heuristics That Make Us Smart, Gerd Gigerenzer and Peter Todd give many examples of situations in which we use fast and frugal heuristics, from how we buy stocks to how we choose mates or divide resources among our children.11 Incidentally, animals use heuristics too. For example, studies of animals and humans have shown that when individuals have to pick a mate among many possible partners, instead of using all the information at their disposal to evaluate the quality of each individual, they simply copy the choice of the majority of other individuals. Cognitive algorithms are probably the product of natural selection, which has prepared us to make quick and effective decisions in response to problems that have recurred many times in our evolutionary history.
Evolutionary psychologists are a lot more comfortable studying the emotional or cognitive programs of the human mind—how people feel and think—than the behavioral algorithms themselves—how people actually behave. They believe that natural selection shapes the mind’s preferences, biases, and predispositions to respond to certain stimuli or cues, and that it’s best to study emotional and cognitive algorithms in controlled laboratory conditions with a homogenous population of subjects, such as college students. In the lab, they typically look at how college students respond to visual stimuli, such as photos of people’s faces or bodies, or how they solve simple cognitive tasks with paper and pen, or how they play computerized economic games.
Evolutionary psychologists rarely go out in the real world and observe how regular folks behave in their everyday lives. They believe that our behavior is too influenced by the surrounding environment, which is very different from the environment in which our minds evolved, for evolutionary psychology to make any sense of it. In short, they believe that it’s difficult, if not impossible, to recognize and document the action of natural selection on the behavior of human beings living in modern industrialized societies. They may concede that studying primitive people such as the Yanomamo Indians of the Amazon or the !Kung of the Kalahari Desert has something interesting to tell us about human nature, but they are content to leave it at that.
Obviously I disagree. Despite the fact that we ride in elevators and communicate via email, the social problems and dilemmas we must confront in our everyday lives share plenty of similarities with those encountered during much of our evolutionary history. The cues we read and recognize in our everyday social situations don’t simply trigger adaptive emotional and cognitive processes; they activate adaptive behavioral algorithms as well. The way we behave toward strangers in an elevator or during a meeting with our boss is the result of behavioral algorithms that are activated in situations where there is a high risk of aggression or we are confronting a high-status individual who has a great deal of influence over our life. The fact that human beings around the world act the same way in similar social situations suggests that a large part of our social behavior is genetically controlled. Sure, behavior is variable and can be influenced by the environment, but this variability is not infinite or arbitrary or unpredictable or maladaptive. We may not be able to predict the behavior of every individual in a particular situation, but we can predict what individuals will do in that situation on average.
When I was young, and long before I decided to specialize in studying monkey and human behavior, I spent a lot of time observing my pets, which happened to all be cats. Cats are interesting and behaviorally complex creatures. If you don’t believe me, watch a mother cat trying to teach her kittens how
to hunt by bringing back prey to her nest and letting the kittens play with it. After observing not only my own cats but also those that populate the streets, squares, and ancient ruins in Rome, I was struck by how homogeneous and stereotyped cat behavior is. Sure, individual cats have different personalities. But there is huge uniformity in their behavior as well: there is definitely a “cat nature,” different from that of dogs and other animals. Apples come in all kinds of varieties too, differing in size, color, texture, and taste. Yet, as a whole, apples are different from oranges. Cats are cats, apples are apples, and humans are humans. The differences in behavior between animal species are the result of genetic, not environmental, differences. Domestic cats live in the same environment as domestic dogs, and yet they still behave like cats and not dogs.
For pet lovers who remain unconvinced by my observations, consider the differences in behavior among different breeds of dogs. Clearly, there are strong differences among breeds: some dogs can easily be trained to retrieve or to help a shepherd keep his flock of sheep together. There are also differences in how aggressive or friendly different breeds of dogs are toward other dogs and toward people, how docile and cuddly they are, and how excitable or laid back. These differences are largely genetic and the result of selective breeding. To produce highly aggressive Dobermans, a dog breeder picks the most aggressive males and females he can find and allows them to breed, while not breeding the docile Dobermans. After generations of this selective breeding, Dobermans, on average, tend to be aggressive. Darwin used this example of behavior-based selective breeding of domestic animals extensively in On the Origin of Species to prove the point that behavior is heritable and that natural selection favors certain traits over others, the way an animal breeder does. Laboratory mice of different genetic strains also exhibit strong and consistent differences in emotionality and social behavior as a result of systematic selective breeding programs by researchers. Finally, thousands of recent studies in humans and all kinds of animals have shown that there is a correspondence between certain behavioral traits exhibited by individuals and the genes they possess. These traits include complex social behavior. Yes, of course, human behavior is still variable and influenced by early experience and environment. But exactly how variable or homogeneous human behavior is depends on one’s perspective. To an anthropologist from Mars, all humans appear to act pretty much the same toward one another, and not at all like the way the inhabitants of Jupiter treat each other.
The Adaptiveness of Human Social Behavior and Convergent Evolution with Other Animals
Social behavior is, in part, genetically controlled and evolves by natural selection. Even though many of us live in technological and industrialized societies, much of our social behavior is still adaptive and solves the same problems it evolved to solve millions of years ago. For a highly social and competitive species such as Homo sapiens, the main source of problems—the main challenge to survival and reproduction—is not predators or lack of food or inclement weather, but other people. In response to the pressures to cooperate and compete, we behave nepotistically toward our kin at the expense of nonkin. We fight for dominance with enemies, friends, and family members, and depending on our relative status we behave assertively or submissively. We establish social and political alliances to gain access to mates and money. We cooperate with unrelated individuals when we benefit directly (through reciprocation) or indirectly (through reputation and other effects). When resources are limited and competition is harsh, we try to hurt our competitors without having to pay a price for it. We establish bonds when we need them, we develop strategies for testing their strength, and we are sensitive to changes in the ratios of costs and benefits of our partnerships. We choose mates, political allies, and business partners through complex negotiations in a biological market in which the value of individuals and their resources fluctuates according to the laws of supply and demand. Throughout many of these transactions and relationships, we behave according to models from game theory and other branches of economics and evolutionary biology. Again, there is a great deal of individual and cultural variation in human behavior. But the average behavior of human beings in many social situations is adaptive and highly predictable. And in many cases, behavioral variation among individuals is adaptive and highly predictable too.
Some of the social problems confronted by modern humans are also present in other organisms, and their adaptive solutions are similar to ours. Nepotistic behavior is widespread among honeybees and ants, fish play tit-for-tat strategies of cooperation, birds form pair-bonds to jointly rear their offspring, dominance hierarchies and ranks are widespread in birds and mammals, and complex strategies of alliance formation are seen in primates, hyenas, and dolphins. In many cases, different groups of animals confronting similar environmental problems come up with similar adaptive solutions independently of one another, a phenomenon that evolutionary biologists call convergent evolution. When solutions to a particular problem are limited, natural selection sometimes comes up with the same solution over and over again, even in organisms that are distantly related, such as fish and people. In some cases, the solutions are only superficially similar: both fish and people play tit-for-tat strategies of cooperation, but the cognitive mechanisms that these species use to implement the strategy are likely to be very different. People can think about the future and the consequences of their actions, and they can predict others’ responses to their own behavior. Fish probably just have hardwired brain mechanisms that make them do the right thing. In some situations, however, the hardwired mechanisms work so well that there is no need to replace them with more sophisticated cognitive ones. Evolution has to overcome considerable friction to transform a “hardwired” behavioral strategy into a “cognitive” one.12 Even in animals with big brains, including humans, there will be selection against the use of complicated strategies that are costly in time and cognitive processing power if a simple rule of thumb can work just as well.
The Phylogenetic History of Human Social Behavior
All organisms on the planet, including humans, represent a combination of traits that are new and unique to the species because they evolved recently and traits that are ancient because they were inherited from ancestors. When particular behavioral solutions to environmental problems work well for certain organisms, these solutions can last for a long evolutionary time. When species evolve and give rise to new species, the descendants inherit not only anatomical and physiological adaptations from their ancestors but some of their behavioral adaptations as well. Some behavioral programs that humans use to solve particular social problems are similar to the programs used by other primates, not because we independently came up with the same solution to the problem, but because we and the other primates directly inherited these programs from our common ancestors. Some human emotions, such as fear, have a long evolutionary history. We humans didn’t invent anything new in the fear business: we inherited the whole package—the emotion, its physiological mechanisms, and its effects on behavior—from our ancestors. That some emotional programs have a long evolutionary history is not a controversial issue. For other programs, however, the issue of history is controversial. Before I get into the controversy, let me backtrack for a second and go over some very basic information about evolution.
Macroevolution is the process through which species change over time and give rise to new species or go extinct. Evolution can be visualized as a branching process in which some branches of a tree grow and produce new branches while others reach a dead end. All organisms on earth that descended from the same microorganism ancestor are thus evolutionarily interrelated. This can be visualized with a phylogenetic tree, such as the tree of life shown in Figure 9.1. A phylogenetic tree is a branching diagram showing the evolutionary relationships among species or taxonomic groups. These relationships are inferred from similarities and differences in their physical or genetic characteristics. The taxonomic groups joined together in the tree are thought to have desce
nded from a common ancestor. Each node with descendants represents the most recent common ancestor of the descendants, and the edge lengths may be interpreted as estimated time spans between species. Descendant species inherit much of their DNA and the traits coded by the genes from their ancestors. As a result, we can reconstruct the phylogenetic history of traits, such as the presence of mammary glands, by mapping onto a tree and identifying the ancestor in which the trait first appeared. In this case, it is the first mammal that branched off from the vertebrate branch. Some traits can appear for the first time in a species and therefore have no traceable phylogenetic history, or they may look as if they appeared for the first time in a species because information about the ancestors in which the trait evolved has been lost. For instance, language appears to be unique to modern humans. However, it is possible that rudiments of language first evolved in some of our recent ancestors, such as the Australopithecines or other species of the genus Homo, which are now extinct. It is possible that language has its own phylogenetic history but that it is difficult to know what it is because our recent ancestors are no longer around.
Games Primates Play: An Undercover Investigation of the Evolution and Economics of Human Relationships Page 29