Other genes that affect dopamine have been associated with delinquency as well, including a version of a gene that affects the density of dopamine receptors (DRD2) and a version of a gene for a dopamine transporter (DAT1) that mops up excess dopamine from the synapse and transports it back into the neurons that release it.158 Any of them could be fair game for rapid natural selection.
Genetic tendencies toward or away from violence, then, could have been selected during the historical transitions we have examined. The question is, were they? The mere existence of pathways to evolutionary change does not prove that those pathways were taken. Evolution depends not just on the genetic raw material but on factors such as the demography of a population (including both sheer numbers and the degree to which they have absorbed immigrants from other groups), the roll of the genetic and environmental dice, and the dilution of genetic effects by learned adjustments to the cultural milieu.
So is there evidence that the Pacification or Civilizing Process ever rendered the pacified or civilized peoples constitutionally less susceptible to violence? Casual impressions can be misleading. History offers many examples in which one nation has considered another to be peopled by “savages” or “barbarians,” but the impressions were motivated more by racism and observations of differences in societal type than by any attempt to tease apart nature and nurture. Between 1788 and 1868, 168,000 British convicts were sent to penal colonies in Australia, and one might have expected that Australians today would have inherited the obstreperous traits of their founding population. But Australia’s homicide rate is lower than that of the mother country; in fact it is one of the lowest in the world. Before 1945 the Germans had a reputation as the most militaristic people on earth; today they may be the most pacifistic.
What about hard evidence from the revolution in evolutionary genomics? In their manifesto The 10,000 Year Explosion: How Civilization Accelerated Human Evolution, the physicist Gregory Cochran and the anthropologist Henry Harpending reviewed the evidence for recent selection in humans and speculated that it includes changes in temperament and behavior. But none of the selected genes they describe has been implicated in behavior; all are restricted to digestion, disease resistance, and skin pigmentation.159
I know of only two claims of recent evolutionary changes in violence that have at least a soupçon of scientific evidence behind them. One involves the Maori, a Polynesian people who settled in New Zealand about a thousand years ago. Like many nonstate hunter-horticulturalists, the Maori engaged in extensive warfare, including a genocide of the Moriori people in the nearby Chatham Islands. Today their culture preserves many symbols of their warrior past, including the haka war dance that fires up New Zealand’s All-Blacks rugby team, and an armamentarium of beautiful greenstone weapons. (I have a lovely battle-ax in my office, a gift of the University of Auckland for giving a set of lectures there.) The acclaimed 1994 film Once Were Warriors vividly depicts the crime and domestic violence that currently plague some of the Maori communities in New Zealand.
Against this cultural backdrop, the New Zealand press quickly picked up on a 2005 report showing that the low-activity version of the MAO-A gene is more common among the Maori (70 percent) than among descendants of Europeans (40 percent).160 The lead geneticist, Rod Lea, suggested that the gene had been selected in the Maori because it made them more accepting of risk during the arduous canoe voyages that brought them to New Zealand, and more effective in their internecine tribal battles thereafter. The press dubbed it the Warrior Gene and speculated that it could help explain the higher levels of social pathology among the Maori in modern New Zealand.
The Warrior Gene theory has not fared well in warfare with skeptical scientists. 161 One problem is that the signatures of selection for the gene could also have been caused by a genetic bottleneck, in which a random assortment of genes that happened to be carried by a few founders of a population was multiplied in their burgeoning descendants. Another is that the low-activity version of the gene is even more common in Chinese men (77 percent of whom carry it), and the Chinese are neither descended from warriors in their recent history nor particularly prone to social pathology in modern societies. A third and related problem is that an association between the gene and aggression has not been found in non-European populations, perhaps because they have evolved other ways of regulating their catecholamine levels.162 (Genes often act in networks regulated by feedback loops, so in populations in which a particular gene is less effective, other genes may step up their activity to compensate.) For now, the Warrior Gene theory is staggering around with possibly fatal wounds.
The other claim of a recent evolutionary change appeals to a civilizing rather than a pacification process. In A Farewell to Alms: A Brief Economic History of the World, Gregory Clark sought to explain the timing and location of the Industrial Revolution, which for the first time in history increased material well-being faster than the increase could be eaten up by population growth (see, for example, figure 4–7, taken from his book). Why, Clark asked, was it England that hosted this onetime escape from the Malthusian trap?
The answer, he suggested, was that the nature of Englishmen had changed. Starting around 1250, when England began to shift from a knightly society to “a nation of shopkeepers” (as Napoleon would sneeringly call it), the wealthier commoners had more surviving children than the poorer ones, presumably because they married younger and could afford better food and cleaner living conditions. Clark calls it “the survival of the richest”: the rich got richer and they got children. This upper middle class was also outreproducing the aristocrats, who were splitting heads and chopping off body parts in their tournaments and private wars, as we saw in figure 3–7, also taken from Clark’s data. Since the economy as a whole would not begin to expand until the 19th century, the extra surviving children of the wealthier merchants and tradesmen had nowhere to go on the economic ladder but downward. They continuously replaced the poorer commoners, bringing with them their bourgeois traits of thrift, hard work, self-control, patient future discounting, and avoidance of violence. The population of England literally evolved middle-class values. That in turn positioned them to take advantage of the commercial opportunities opened up by the innovations of the Industrial Revolution. Though Clark occasionally dodges the political correctness police by noting that nonviolence and self-control can be passed from parent to child as cultural habits, in a précis of his book entitled “Genetically Capitalist?” he offers the full-strength version of his thesis:The highly capitalistic nature of English society by 1800—individualism, low time preference rates, long work hours, high levels of human capital—may thus stem from the nature of the Darwinian struggle in a very stable agrarian society in the long run up to the Industrial Revolution. The triumph of capitalism in the modern world thus may lie as much in our genes as in ideology or rationality.163
A Farewell to Alms is filled with illuminating statistics and gripping narratives about the historical precursors to the Industrial Revolution. But the Genetically Capitalist theory has not competed well in the struggle for survival among theories of economic growth.164 One problem is that until recently, the rich have outreproduced the poor in pretty much every society, not just the one that later blasted off in an industrial revolution. Another is that while aristocrats and royals may have had no more legitimate heirs than the bourgeoisie, they more than made up for it in bastards, which could have contributed a disproportionate share of their genes to the next generation. A third is that when institutions change, a nation can vault to spectacular rates of economic growth in the absence of a recent history of selection for middle-class values, such as postwar Japan and post-communist China. And most important, Clark cites no data showing that the English are innately more self-controlled or less violent than the citizenries of countries that did not host an industrial revolution.
So while recent biological evolution may, in theory, have tweaked our inclinations toward violence and nonviolence, we have no goo
d evidence that it actually has. At the same time, we do have good evidence for changes that could not possibly be genetic, because they unfolded on time scales that are too rapid to be explained by natural selection, even with the new understanding of how recently it has acted. The abolition of slavery and cruel punishments during the Humanitarian Revolution; the reduction of violence against minorities, women, children, homosexuals, and animals during the Rights Revolutions; and the plummeting of war and genocide during the Long Peace and the New Peace, all unfolded over a span of decades or even years, sometimes within a single generation. A particularly dramatic decline is the near-halving of the homicide rate during the Great American Crime Decline of the 1990s. The decay rate of that decline, around 7 percent a year, is powerful enough to drag a measure of violence down to 1 percent of its original level over just two generations, all without the slightest change in gene frequencies. Since it is indisputable that cultural and social inputs can adjust the settings of our better angels (such as self-control and empathy) and thereby control our violent inclinations, we have the means to explain all the declines of violence without invoking recent biological evolution. At least for the time being, we have no need for that hypothesis.
MORALITY AND TABOO
The world has far too much morality. If you added up all the homicides committed in pursuit of self-help justice, the casualties of religious and revolutionary wars, the people executed for victimless crimes and misdemeanors, and the targets of ideological genocides, they would surely outnumber the fatalities from amoral predation and conquest. The human moral sense can excuse any atrocity in the minds of those who commit it, and it furnishes them with motives for acts of violence that bring them no tangible benefit. The torture of heretics and conversos, the burning of witches, the imprisonment of homosexuals, and the honor killing of unchaste sisters and daughters are just a few examples. The incalculable suffering that has been visited on the world by people motivated by a moral cause is enough to make one sympathize with the comedian George Carlin when he said, “I think motivation is overrated. You show me some lazy prick who’s lying around all day watching game shows and stroking his penis, and I’ll show you someone who’s not causing any fucking trouble!”
Though the net contribution of the human moral sense to human well-being may well be negative, on those occasions when it is suitably deployed it can claim some monumental advances, including the humanitarian reforms of the Enlightenment and the Rights Revolutions of recent decades. When it comes to virulent ideologies, morality may be the disease, but morality is also the cure. The mentality of taboo, like the mentality of morality of which it is part, also can pull in either direction. It can turn religious or sexual nonconformity into an outrage that calls for ghastly punishment, but it can also prevent the mind from sliding into dangerous territory such as wars of conquest, the use of chemical and nuclear weapons, dehumanizing racial stereotypes, casual allusions to rape, and the taking of identifiable human lives.
How can we make sense of this crazy angel—the part of human nature that would seem to have the strongest claim to be the source of our goodness, but that in practice can be more diabolical than our worst inner demon?
To understand the role of the moral sense in the decline of violence, we have to solve a number of psychological enigmas. One is how people in different times and cultures can be driven by goals that they experience as “moral” but that are unrecognizable to our own standards of morality. Another is why the moral sense does not, in general, push toward the reduction of suffering but so often increases it. A third is how the moral sense can be so compartmentalized: why upstanding citizens can beat their wives and children; why liberal democracies can practice slavery and colonial oppression; why Nazi Germany could treat animals with unequaled kindness. A fourth is why, for better and for worse, morality can be extended to thoughts as well as deeds, leading to the paradox of taboo. And the overriding puzzle, of course, is: What changed? What degree of freedom in the human moral sense has been engaged by the processes of history to drive violence downward?
The starting point is to distinguish morality per se, a topic in philosophy (in particular, normative ethics), from the human moral sense, a topic in psychology. Unless one is a radical moral relativist, one believes that people can in some sense be mistaken about their moral convictions; that their justifications of genocide, rape, honor killings, and the torture of heretics are erroneous, not just distasteful to our sensibilities.165 Whether one is a moral realist and believes that moral truths are objectively out there somewhere like mathematical truths, or simply allows that moral statements have some degree of warrant in terms of consistency with universally held convictions or the best understanding that arises out of our collective rational deliberation, one can distinguish questions of morality from questions of moral psychology. The latter ask about the mental processes that people experience as moral, and they can be studied in the lab and field, just like any other cognitive or emotional faculty.
The next step in understanding the moral sense is to recognize that it is a distinctive mode of thinking about an action, not just the avoidance of an action. There are important psychological distinctions between avoiding an action because it is deemed immoral (“Killing is wrong”) and avoiding it because it is merely disagreeable (“I hate cauliflower”), unfashionable (“Bellbottoms are out”), or imprudent (“Don’t scratch mosquito bites”).166
One difference is that disapproval of a moralized act is universalized. If you think cauliflower is distasteful, then whether other people eat it is of no concern to you. But if you think that murder and torture and rape are immoral, then you cannot simply avoid these activities yourself and be indifferent to whether other people indulge in them. You have to disapprove of anyone committing such acts.
Second, moralized beliefs are actionable. While people may not unfailingly carry out Socrates’ dictum that “To know the good is to do the good,” they tacitly aspire to it. People see moral actions as intrinsically worthy goals, which need no ulterior motive. If people believe that murder is immoral, they don’t need to be paid or even esteemed to refrain from murdering someone. When people do breach a moral precept, they rationalize the failure by invoking some countervailing precept, by finding an exculpatory excuse, or by acknowledging that the failure is a regrettable personal weakness. Other than devils and storybook villains, no one says, “I believe murder is a heinous atrocity, and I do it whenever it serves my purposes.”167
Finally, moralized infractions are punishable. If one believes that murder is wrong, one is not just entitled to see a murderer punished, but one is obligated to make it happen. One may not, as we say, let someone get away with murder. Now just substitute “idolatry” or “homosexuality” or “blasphemy” or “subversion” or “indecency” or “insubordination” for “murder,” and you can see how the human moral sense can be a major force for evil.
Another design feature of the moral sense is that many moral convictions operate as norms and taboos rather than as principles the believer can articulate and defend. In the psychologist Lawrence Kohlberg’s famous six-stage progression of moral development, from a child’s avoidance of punishment to a philosopher’s universal principles, the middle two stages (which many people never get out of) consist of conforming to norms to be a good boy or girl, and maintaining conventions to preserve social stability. When reasoning through the moral dilemma that Kohlberg made famous, in which Heinz must break into a drugstore to steal an overpriced drug that will save his dying wife, people in these stages can muster no better justification for their answers than that Heinz shouldn’t steal the drug because stealing is bad and illegal and he is not a criminal, or that Heinz should steal the drug because that’s what a good husband does.168 Fewer people can articulate a principled justification, such as that human life is a cardinal value that trumps social norms, social stability, or obedience to the law.
The psychologist Jonathan Haidt has underscored the inef
fability of moral norms in a phenomenon he calls moral dumbfounding. Often people have an instant intuition that an action is immoral, and then struggle, often unsuccessfully, to come up with reasons why it is immoral.169 When Haidt asked participants, for example, whether it would be all right for a brother and sister to have voluntary protected sex, for a person to clean a toilet with a discarded American flag, for a family to eat a pet dog that had been killed by a car, for a man to buy a dead chicken and have sex with it, or for a person to break a deathbed vow to visit the grave of his mother, they said no in each case. But when asked for justifications, they floundered ineffectually before giving up and saying, “I don’t know, I can’t explain it, I just know it’s wrong.”