The Better Angels of Our Nature: Why Vio - By Steven Pinker Page 0,215

expensive item is transportation to an Israeli town.”204 The only real technological hurdle is the willingness of the young man. Ordinarily a human being is unwilling to die, the legacy of half a billion years of natural selection. How have terrorist leaders overcome this obstacle?

People have exposed themselves to the risk of dying in wars for as long as there have been wars, but the key term is risk. Natural selection works on averages, so a willingness to take a small chance of dying as part of an aggressive coalition that offers a large chance of a big fitness payoff—more land, more women, or more safety—can be favored over the course of evolution.205 What cannot be favored is a willingness to die with certainty, which would take any genes that allow such willingness along with the dead body. It’s not surprising that suicide missions are uncommon in the history of warfare. Foraging bands prefer the safety of raids and ambushes to the hazards of set-piece battles, and even then warriors are not above claiming to have had dreams and omens that conveniently keep them out of risky encounters planned by their comrades.206

Modern armies cultivate incentives for soldiers to increase the risk they take on, such as esteem and decorations for bravery, and disincentives for them to reduce the risk, such as the shaming or punishment of cowards and the summary execution of deserters. Sometimes a special class of soldier called file closers trails behind a unit with orders to kill any soldier who fails to advance. The conflicts of interest between war leaders and foot soldiers leads to the well-known hypocrisy of military rhetoric. Here is how a British general waxed about the carnage of World War I: “Not a man shirked going through the extremely heavy barrage, or facing the machine gun and rifle fire that finally wiped them out.... I have never seen, indeed could never have imagined, such a magnificent display of gallantry, discipline, and determination.” A sergeant described it differently: “We knew it was pointless, even before we went over—crossing open ground like that. But you had to go. You were between the devil and the deep blue sea. If you go forward, you’ll likely be shot. If you go back, you’ll be court-martialed and shot. What can you do?”207

Warriors may accept the risk of death in battle for another reason. The evolutionary biologist J.B.S. Haldane, when asked whether he would lay down his life for his brother, replied, “No, but for two brothers or eight cousins.” He was invoking the phenomenon that would later be known as kin selection, inclusive fitness, and nepotistic altruism. Natural selection favors any genes that incline an organism toward making a sacrifice that helps a blood relative, as long as the benefit to the relative, discounted by the degree of relatedness, exceeds the cost to the organism. The reason is that the genes would be helping copies of themselves inside the bodies of those relatives and would have a long-term advantage over their narrowly selfish alternatives. Critics who are determined to misunderstand this theory imagine that it requires that organisms consciously calculate their genetic overlap with their kin and anticipate the good it will do their DNA.208 Of course it requires only that organisms be inclined to pursue goals that help organisms that are statistically likely to be their genetic relatives. In complex organisms such as humans, this inclination is implemented as the emotion of brotherly love.

The small-scale bands in which humans spent much of their evolutionary history were held together by kinship, and people tended to be related to their neighbors. Among the Yanomamö, for example, two individuals picked at random from a village are related almost as closely as first cousins, and people who consider each other relatives are related, on average, even more closely.209 The genetic overlap tilts the evolutionary payoff toward taking greater risks to life and limb if the risky act might benefit one’s fellow warriors. One of the reasons that chimpanzees, unlike other primates, engage in cooperative raiding is that the females, rather than the males, disperse from the troop at sexual maturity, so the males in a troop tend to be related.210

As with all aspects of our psychology that have been illuminated by evolutionary theory, what matters is not actual genetic relatedness (it’s not as if hunter-gatherers, to say nothing of chimpanzees, send off cheek swabs to a genotyping service) but the perception of relatedness, as long as the perception was correlated with