The Anatomy of Violence

by Adrian Raine

  In evolutionary terms, the human capacity for antisocial and violent behavior wasn’t a random occurrence. Even as early hominids developed the ability to reason, communicate, and cooperate, brute violence remained a successful “cheating” strategy. Most criminal acts can be seen, directly or indirectly, as a way to take resources away from others. The more resources or status a man has, the better able he is to attract young, fertile females. These women in turn are on the lookout for men who can give them the protection and the resources they need to raise their future children.

  Many violent crimes may sound mindless, but they are informed by a primitive evolutionary logic. The mugger who kills for $1.79 is not getting much for his efforts, yet the general strategy of theft can pay off in the long run in terms of acquiring goods. Drive-by shootings may seem senseless, but they help establish dominance and status in the neighborhood. And while a barroom brawl over who’s next at the pool table may sound to you like fighting over nothing, the real game being played has nothing to do with pool.

  From rape to robbery and even to theft, evolution has made violence and antisocial behavior a profitable way of life for a small minority of the population. The ultimate capacity for our antisocial misdeeds can be understood with reference to evolutionary biology. And it is from fundamental evolutionary mechanisms that genetic differences among us have come into play and shaped the anatomy of violence.

  We think of aggression today as maladaptive and aberrant. We give heavy legal sentences to violent offenders to deter them and others from committing such crimes, so surely it cannot be viewed as adaptive. But evolutionary psychologists think differently. Aggression is used to grab resources from others, and resources are the name of the evolutionary game. Resources are needed to live, reproduce, and care for offspring. There is an evolutionary root to actions that run the gamut from bullies threatening other kids for candy to men robbing banks for money. And aggression—more specifically defensive aggression—is also important in warding off others who may wish to steal our precious resources. Bar fights help establish a pecking order of dominance and power, helping to put down rivals in the eyes of desirable women and other potential competitors. The mating game for males is about developing desirable status in society. Gaining a reputation for aggression not only increases status in one’s social group and allows more access to resources but also deters aggression from others. And that is true whether we are talking about a child in a playground or an inmate in a prison.

  From a chubby-faced baby to a crooked-faced criminal, there is a development and unfolding of antisocial behavior predicated on biology and a cheating strategy to living out life. As a tiny kid, you took what you wanted without a care. All that mattered in the world was you and your selfish desires. You may have forgotten those days, but in that untamed, uncivilized period of your life, you were standing on the threshold of a life of crime.

  Of course culture quickly took care of that. You were taught by parents, and maybe your older siblings, the rules of social behavior—“Don’t hit your sister,” “Don’t take your brother’s toys”—and your evolving brain began to slowly learn not just that there were others in the world, but that selfishness was not always a wise guiding principle on life’s long, arduous journey. You never exactly gave up on looking out for yourself and what was good for you, but at least you began to take into account others’ feelings and to express appropriate concern for others at appropriate moments—at times genuinely, and perhaps at other times disingenuously. But is there more to explaining antisocial behavior than the presence or absence of familial socializing forces?

  There is. The thesis that really challenges our perspective on ourselves and our evolutionary history first appeared in 1976, in a radical book called The Selfish Gene, by Richard Dawkins.6 I’ll not forget this book, or Richard Dawkins, for that matter. As an undergraduate I had one-on-one tutorials with him on evolutionary theory. They were thrilling lessons on the all-embracing influence of evolution on behavior, and they led me to start thinking of violence and crime in evolutionary terms.

  The central thesis in his landmark book was that “successful” genes are ruthlessly selfish in their struggle for survival, giving rise to selfish individual behavior. In this context, human and animal bodies are little more than containers, or “survival machines,” for armies of ruthless renegade genes. These machines plot a merciless campaign of success in the world, where success is defined solely in terms of survival and achieving greater representation in the next gene pool. However, the gene is the basic unit of “selfishness” rather than the individual. The individual eventually dies, but selfish genes are passed on from body to body, from generation to generation, and potentially from millennium to millennium.

  It all boils down to how “fit” you are. Not so much whether you can run a marathon or how much you can lift, but how many children you can produce that are yours. The more kids you have that are genetically yours, the more copies of your genes there will be in the following gene pool. That, and only that, is success in the gene’s-eye view of the world. If more lofty perspectives come to mind when you contemplate the meaning of “success”—like doing well in school, having a great job, or writing a book—then consider this: your gene machine has been built to generate these fanciful ideas to maliciously motivate you into gaining status and resources that will translate into reproductive success. It’s a genetic con.

  As a male you can maximize your genetic fitness in one of two ways. One, you can invest a lot of parental effort and resources into just a few offspring. You put all your eggs into a small basket, nurturing and protecting a couple of kids, ensuring their survival into full maturity, and even helping them look after their own children. Alternatively, you can put all your eggs, or rather sperm, into a lot of baskets. Here you maximize the number of your offspring without really doing very much to support them, spreading your parental effort more thinly.

  A male can much more easily adopt this latter reproductive strategy of high offspring–low effort if he “cheats” on his many female partners by misrepresenting his ability to acquire resources and his long-term parenting intentions. Mate support and resources are critical for women. Once fertilized, females are largely lumbered with their progeny. They make the bigger investment in raising the child, so they are on the lookout for men who can come up with the goods, and will commit to long-term support.

  So fitness—an organism’s ability to pass on its genetic material—is central to the evolution of all behavior and the driving force behind selfishness. Certainly in the animal world, it is easy to see how antisocial and aggressive behaviors have evolved. Animals fight for food and they fight for mates. And whether we like it or not, it’s not too much of a stretch from the animal kingdom to us humans. The temptation to “cheat”—whether it is not sharing resources after having accepted them from others or manipulation of others to selfishly acquire resources—is always there.

  But surely we humans are different from animals. We have a strong capacity for social cooperation, altruism, and selflessness. Reciprocal altruism has indeed evolved because in the long run it benefits the performer. It ultimately pays you to help save a stranger if that stranger will reciprocate your help in the future, and save your life.7 Today, by and large, we live in a world populated by reciprocal altruists. And yet, at the same time, reciprocal altruism can itself give rise to “cheating.” If you accept acts of altruism from others, but fail to reciprocate in the future, you’re cheating. There is room for a bit of cheating—truth be told, we all do it from time to time. But a small number of us cheat a lot—and in this group we find the psychopath. The trouble for psychopaths, however, is that sooner or later they get a bad reputation. People stop helping them out, and potential mates pass them over. In this scenario the psychopathic cheat is on a downward spiral.

  Fortunately for the psychopath there is a slippery way out. After he’s been spotted by reciprocal altruists he leaves this social network and migr
ates to a new population, where he can begin to fleece a different set of unsuspecting victims. It’s easy to see in this analysis, therefore, how a small minority of antisocial cheats could survive in a world largely populated by reciprocal altruists. The proportion of cheats within any population would have to stay relatively small—cheats lose out when they meet one another—but otherwise cheats can survive, as long as they are prepared to tough it out and take a few hits before moving on.

  Such a scenario would lead to the prediction that these hard-core antisocials drift from population to population. Consistent with this prediction, the modern-day psychopath has been characterized as an impulsive, sensation-seeking individual who fails to follow any life plan, aimlessly drifting from person to person, job to job, and town to town.8 Probably the best assessment tool for psychopathy—the Psychopathy Checklist—makes reference to the psychopath’s short-term plans and goals, nomadic existence, frequent breaking off of relationships, poor parenting, moving from one place to another, frequent changes of jobs and addresses, and parasitic lifestyle.9 The “pure” cheat strategy is therefore entirely consistent with present-day psychopaths who manifest a nomadic lifestyle.

  In any game there is more than one winning strategy, and that holds true in the game of reproductive fitness. Reciprocal altruism can pay for most, and for a few the psychopathic cheating strategy wins out. We’ll now turn to how certain environmental conditions could nudge some whole societies to become altruistic or selfish, and how psychopathic behaviors could have evolved. Given certain environmental circumstances, whole populations of cheats could evolve, and studies of primitive societies provide some interesting clues on the evolution of psychopathic behavior.

  PSYCHOPATHS ACROSS CULTURES

  Environmental conditions vary greatly across the world, and throughout prehistory behaviors have evolved in an adaptive response to changing environmental circumstances. Building on this notion, some anthropological studies lend support to the idea that whole populations can develop an antisocial trait. The main method of these studies has been to compare cultures differing in antisocial conduct on ecological and environmental factors that give rise to different reproductive strategies and social behaviors. If certain ecological niches are associated with certain types of behavior, this could support the notion that what we call antisocial traits could be advantageous in cultures found in certain environments. Such cultures could have jump-started the evolution of antisocial, psychopathic-like lifestyles.

  When comparing, for instance, the cultures of the !Kung Bushmen of the Kalahari Desert in Southern Africa and the Mundurucú villagers in the Amazon Basin, anthropologists have found that the strikingly different environments they inhabit correlate with altruistic and antisocial behavior, respectively.10 The !Kung Bushmen live in a relatively inhospitable desert environment. Due to the extremely difficult living conditions, cooperation is prized. Men need to hunt together in search of food, and game is shared in the camp.11 There is also a high degree of parental investment in children, who are highly supervised and weaned gradually. Because of that high parental investment, fertility is relatively low. A disruption of a pair bond by either partner could have fatal consequences for the offspring, who are highly dependent on parental care. The personal characteristics adapted to the !Kung’s environment are good hunting skills, reliable reciprocation of altruistic acts, the careful choosing of mates, and high parental investment in offspring. This personality profile is clearly more aligned to altruism than to cheating, a trait that is argued to be in part an adaptation to an inhospitable environment.

  In contrast, the Mundurucú are low-intensity tropical gardeners living in a relatively rich ecological niche along the Tapajós and Trombetas Rivers in the Amazon basin. Everything grows there, and life is relatively easy. In an interesting role-reversal, women carry out most of the food production.12 This environment makes for a very different way of life and a different male personality profile. The relatively greater availability of food frees males to engage in male-male competitive interactions centered around politics, planning raids and warfare, gossiping, fighting, and elaborate ritual ceremonies. Occasionally they engage in hunting game that they trade for sex with the village women. Men sleep together in a house separate from the women, whom they hold in disdain. Indeed, females are viewed as sources of pollution and danger. Males in the Gainj tribe, low-intensity gardeners in the highlands of New Guinea, also view sexual contact with women as dangerous, especially during menstruation.

  In contrast to the !Kung, Mundurucú mothers provide little care to their infants once they are weaned, and these children must quickly learn to fend for themselves. Mundurucú men play a minimal role in caring for their offspring. Personal characteristics of the successful Mundurucú male in this competitive society consist of good verbal skills for political oratory, fearlessness, skill at fighting and carrying out raids, bluff and bravado to avoid the risk of battle, and the ability to manipulate and deceive prospective mates on what resources he can offer to maximize offspring. Furthermore, he should not be gullible, since belief in the folklore regarding the dangers of sex and women as a source of pollution would not foster the passing on of one’s genes.13

  Similarly, for females living in a social context of low parental investment, those who can manipulate their menfolk by deception over an offspring’s paternity, exaggeration of requirements, and resistance to the development of monogamous bonds are the most successful. The Mundurucú’s way of life is then more associated with a cheating, antisocial strategy than with reciprocal altruism. Figure 1.1 summarizes the key features of these two societies and how they stand in sharp contrast.

  Figure 1.1 Contrasting environmental features of two societies that shape different personality traits

  The nature of the Mundurucú’s social environment clearly favors the expression of aggressive, psychopathic-like behavior. Certainly when one considers the fact that the Mundurucú were in the past fiercely aggressive headhunters, this parallel to psychopathy becomes clearer. Intriguingly, many of the features of the Mundurucú have parallels with features of psychopathic behavior in modern industrialized societies.14 For example, psychopaths show lack of conscience, superficial charm, high verbal skills, promiscuity, and lack of long-term interpersonal bonds.15 While these traits are advantageous in the Mundurucú environment, they are clearly disadvantageous in the milieu of the !Kung Bushmen, which demands high male parental effort, reciprocal altruism, and monogamous relationships.

  The Yanomamo Indians in the tropical rain forests of northern Brazil and southern Venezuela provide another parallel culture to the Mundurucú. With a total population of about 20,000, they live in villages that can range in size from 90 people to about 300. As with the Mundurucú, they subsist on plants and vegetables and only need to do about three hours of work a day. They too live in a rich ecological niche.

  Napoleon Chagnon, in his intensive anthropological studies on the Yanomamo, has documented a number of striking features of this culture.16 They’ll break rules when it’s in their interest. They participate in the forcible appropriation of women. They call themselves waiteri—meaning “fierce.” And they are indeed both fearless and highly aggressive. Boys are socialized into acts of aggression from a surprisingly young age, with their “play” consisting of throwing spears and shooting arrows at other boys. Initially they are scared by this initiation into violence, but soon they come to revel in the adrenaline rush that the mock battles provide.

  To give you a perspective on their level of aggression, 30 percent of all male deaths among the Yanomamo are due to violence, an astonishing level. If you think the United States is a violent society, consider that 44 percent of all Yanomamo men over the age of twenty-five have killed someone, thus achieving the status of being a unokai. Some kill more than once, and one unokai had killed sixteen times. The source of the killing in the majority of cases is sexual jealousy—exactly what you’d expect from an evolutionary perspective and a spec
ies whose females make the greater parental investment. They also conduct raids on other villages for revenge killings that can take up to four days to execute, involving from ten to twenty men in the raiding party.

  From our perspective on the evolution of violence, however, the most interesting element of the Yanomamo is what happens to unokais, the men who kill. They have an average of 1.63 wives compared with 0.63 wives of men who do not kill. The unokais have an average of 4.91 children compared with an average of 1.59 children for non-killers. In terms of reproductive fitness, serious violence pays handsomely in two critical resources. First, lots of kids. Second, lots of wives to look after them. We can see how planned violence and the lack of remorse over killing others have been rewarded in the unokais’ society. These are precisely the features of Western psychopaths,17 who also commit more aggressive acts than non-psychopaths, and are more likely to commit homicide for gain.18

  Inevitably, Western society does not condone such violence. We hardly applaud and reward people who kill others. Or do we? With significant pomp and ceremony we decorate and reward soldiers who have taken significant risks to kill others in warfare. Crowds cheer wildly as boxers punch each other senseless in a sport that we know results in brain damage. We certainly revel in kung fu movies or other film genres when the good guy beats the living daylights out of the bad guy.

  Whatever our cultivated minds may publicly say about the senselessness of warfare, do not our primitive hearts still thrill to the drums of combat? Is this why we enjoy sports competitions, to watch the dominant winner end up on top? Is that what gives us the vicarious thrill and excitement of seeing someone win a gold medal at the Olympics? Or when a violent tackle occurs in a football game? Our present-day cultured minds weave an alternative story to explain the feeling—we just love sports, that’s all. But why? Isn’t it because selection pressures have built into us a mechanism to carefully observe who ranks where, empathic skills to imagine ourselves as a winner, basking in that reflected glory, giving us that “feel-good” mood and a desire to emulate such achievements?