We have already seen why the sex difference evolved: mammalian males can reproduce more quickly than females, so they compete for sexual opportunities, while females tilt their priorities toward ensuring the survival of themselves and their offspring. Men have more to gain in violent competition, and also less to lose, because fatherless children are more likely to survive than motherless ones. That does not mean that women avoid violence altogether—Chuck Berry speculated that Venus de Milo lost both her arms in a wrestling match over a brown-eyed handsome man—but they find it less appealing. Women’s competitive tactics consist in less physically perilous relational aggression such as gossip and ostracism.
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In theory, violent competition for mates and violent competition for dominance needn’t go together. One doesn’t have to invoke dominance to explain why Genghis Khan inseminated so many women that his Y chromosome is common in Central Asia today; it’s enough to observe that he killed the women’s fathers and husbands. But given that social primates regulate violence by deferring to dominant individuals, dominance and mating success in practice went hand in hand during most of our species’ history. In nonstate societies, dominant men have more wives, more girlfriends, and more affairs with other men’s wives.
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In the six earliest empires, the correlation between status and mating success can be quantified precisely. Laura Betzig found that emperors often had thousands of wives and concubines, princes had hundreds, noblemen had dozens, upper-class men had up to a dozen, and middle-class men had three or four.
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(It follows mathematically that many lower-class men had none—and thus a strong incentive to fight their way out of the lower class.) Recently, with the advent of reliable contraception and the demographic transition, the correlation has been weakened. But wealth, power, and professional success still increase a man’s sex appeal, and the most visible clue to physical dominance—height—still gives a man an edge in economic, political, and romantic competition.
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Whereas instrumental violence deploys the seeking and calculating parts of the brain, dominance deploys the system that Panksepp calls Intermale Aggression. It really should be called Intrasexual Competition, because it is found in women too, and the human habit of male parental investment means that women as well as men have an evolutionary incentive to compete for mates. Still, at least one part of the circuit, a nucleus in the anterior preoptic portion of the hypothalamus, is twice as large in men as it is in women.
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And the entire system is studded with receptors for testosterone, which is about five to ten times more plentiful in the bloodstream of men than of women. The hypothalamus, recall, controls the pituitary gland, which can secrete a hormone that tells the testes or the adrenal glands to produce more testosterone.
Though testosterone is often identified in the popular imagination as the cause of male pugnacity—“the substance that drives men to behave with quintessential guyness, to posture, push, yelp, belch, punch and play air-guitar,” as the journalist Natalie Angier put it—biologists have been nervous about blaming it for male aggression itself.
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Raising testosterone undoubtedly makes most birds and mammals more obstreperous, and lowering it makes them less so, as the owner of any neutered dog or cat is aware. But in humans the effects are less easily measured, for a number of boring biochemical reasons, and they are less directly tied to aggression, for an interesting psychological reason.
Testosterone, according to scientists’ best guess, does not make men more aggressive across the board, but prepares them for a challenge of dominance.
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In chimpanzees, testosterone goes up in the presence of a sexually receptive female, and it is correlated with the male’s dominance rank, which in turn is correlated with his aggressiveness. In men, testosterone levels rise in the presence of an attractive female and in anticipation of competition with other men, such as in sports. Once a match has begun, testosterone rises even more, and when the match has been decided, testosterone continues to rise in the winner but not in the loser. Men who have higher levels of testosterone play more aggressively, have angrier faces during competition, smile less often, and have firmer handshakes. In experiments they are more likely to lock their gaze onto an angry face, and to perceive a neutral face as angry. It’s not just fun and games that pump up the hormone: recall that the southern men who were insulted in Richard Nisbett’s experiment on the psychology of honor responded with a rise in testosterone, and that they looked angrier, shook hands more firmly, and walked out of the lab with more of a swagger. At the tail end of the belligerence spectrum, prisoners with higher levels of testosterone have been found to commit more acts of violence.
Testosterone rises in adolescence and young adulthood, and declines in middle age. It also declines when men get married, have children, and spend time with their children. The hormone, then, is an internal regulator of the fundamental tradeoff between parenting effort and mating effort, where mating effort consists both in wooing the opposite sex and in fending off rivals of the same sex.
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Testosterone may be the knob that turns men into dads or cads.
The rise and fall of testosterone over the life span correlates, more or less, with the rise and fall of male pugnacity. Incidentally, the first law of violence—it’s something that young men do—is easier to document than to explain. Though it’s clear why men should have evolved to be more violent than women, it’s not so clear why young men should be more violent than old men. After all, young men have more years ahead of them, so when they take up a violent challenge, they are gambling with a greater proportion of their unlived lives. On mathematical grounds one might expect the opposite: that as men’s days are numbered, they can afford to become increasingly reckless, and a really old man might go on one last spree of rape and murder until a SWAT team cuts him down.
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One reason this does not happen is that men always have the option of investing in their children, grandchildren, nieces, and nephews, so older men, who are physically weaker but socially and economically stronger, have more to gain in providing for and protecting their families than in siring more offspring.
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The other is that dominance in humans is a matter of reputation, which can be self-sustaining with a long payout. Everyone loves a winner, and nothing succeeds like success. So it is in the earliest rounds of competition that the reputational stakes are highest.
Testosterone, then, prepares men (and to a lesser extent women) for contests of dominance. It doesn’t cause violence directly, because many kinds of violence have nothing to do with dominance, and because many contests of dominance are settled by displays and brinkmanship rather than violence itself. But to the extent that the problem of violence is a problem of young, unmarried, lawless men competing for dominance, whether directly or on behalf of a leader, then violence really is a problem of there being too much testosterone in the world.
The socially constructed nature of dominance can help explain which individuals are most likely to take risks to defend it. Perhaps the most extraordinary popular delusion about violence of the past quarter-century is that it is caused by low self-esteem. That theory has been endorsed by dozens of prominent experts, has inspired school programs designed to get kids to feel better about themselves, and in the late 1980s led the California legislature to form a Task Force to Promote Self-Esteem. Yet Baumeister has shown that the theory could not be more spectacularly, hilariously, achingly wrong. Violence is a problem not of too little self-esteem but of too much, particularly when it is unearned.
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Self-esteem can be measured, and surveys show that it is the psychopaths, street toughs, bullies, abusive husbands, serial rapists, and hatecrime perpetrators who are off the scale. Diana Scully interviewed many rapists in their prison cells who bragged to her that they were “multitalented superachievers.”
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Psychopaths and other violent people are narcissistic: they think well of themselves not in proportion to their accomplishments but out of a congenital sense of entitlement. When reality intrudes, as it inevitably will, they treat the bad news as a personal affront, and its bearer, who is endangering their fragile reputation, as a malicious slanderer.
Violence-prone personality traits are even more consequential when they infect political rulers, because their hang-ups can affect hundreds of millions of people rather than just the unlucky few who live with them or cross their paths. Unimaginable amounts of suffering have been caused by tyrants who callously presided over the immiseration of their peoples or launched destructive wars of conquest. In chapters 5 and 6 we saw that the tail-thickening wars and dekamegamurders of the 20th century can be attributed in part to the personalities of just three men. Tin-pot tyrants like Saddam Hussein, Mobutu Sese Seko, Moammar Khaddafi, Robert Mugabe, Idi Amin, Jean-Bédel Bokassa, and Kim Jong-il have immiserated their people on a scale that is smaller but still tragic.
The study of the psychology of political leaders, to be sure, has a deservedly poor reputation. It’s impossible to test the object of investigation directly, and all too tempting to pathologize people who are morally contemptible. Psychohistory also has a legacy of fanciful psychoanalytic conjectures about what made Hitler Hitler: he had a Jewish grandfather, he had only one testicle, he was a repressed homosexual, he was asexual, he was a sexual fetishist. As the journalist Ron Rosenbaum wrote in
Explaining Hitler
, “The search for Hitler has apprehended not one coherent, consensus image of Hitler but rather many different Hitlers, competing Hitlers, conflicting embodiments of competing visions. Hitlers who might not recognize each other well enough to say ‘
Heil
’ if they came face to face in Hell.”
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For all that, the more modest field of personality classification, which pigeonholes rather than explains people, has something to say about the psychology of modern tyrants. The
Diagnostic and Statistical Manual of Mental Disorders
(DSM) of the American Psychiatric Association defines narcissistic personality disorder as “a pervasive pattern of grandiosity, need for admiration, and a lack of empathy.”
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Like all psychiatric diagnoses, narcissism is a fuzzy category, and overlaps with psychopathy (“a pervasive pattern of disregard for, and violation of, the rights of others”) and with borderline personality disorder (“instability in mood; black and white thinking; chaotic and unstable interpersonal relationships, self-image, identity, and behavior”). But the trio of symptoms at narcissism’s core—grandiosity, need for admiration, and lack of empathy—fits tyrants to a T.
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It is most obvious in their vainglorious monuments, hagiographic iconography, and obsequious mass rallies. And with armies and police forces at their disposal, narcissistic rulers leave their mark in more than statuary; they can authorize vast outlays of violence. As with garden-variety bullies and toughs, the unearned self-regard of tyrants is eternally vulnerable to being popped, so any opposition to their rule is treated not as a criticism but as a heinous crime. At the same time, their lack of empathy imposes no brake on the punishment they mete out to real or imagined opponents. Nor does its allow any consideration of the human costs of another of their DSM symptoms: their “fantasies of unlimited success, power, brilliance, beauty, or ideal love,” which may be realized in rapacious conquest, pharaonic construction projects, or utopian master plans. And we have already seen what overconfidence can do in the waging of war.
All leaders, of course, must have a generous dose of confidence to have become leaders, and in this age of psychology, pundits often diagnose leaders they don’t like with narcissistic personality disorder. But it’s important not to trivialize the distinction between a politician with good teeth and the psychopaths who run their countries into the ground and take large parts of the world with them. Among the pacifying features of democracies is that their leadership-selection procedure penalizes an utter lack of empathy, and their checks and balances limit the damage that a grandiose leader can do. Even within autocracies, the personality of a leader—a Gorbachev as opposed to a Stalin—can have an enormous impact on the statistics of violence.