Abstract
History is full of violence and oppression within and between groups, and although group conflicts enhance within-group cooperation (mediated by oxytocin, which promotes parochial altruism) the hierarchy within groups ensures that spoils accrue very unevenly. Darwin suggested, and we now know, that sexual selection is as powerful as selection by mortality, and the main purpose of survival is reproduction. Male reproductive skew is greater than that among females in all societies, but the difference became much greater after the hunting-gathering era, and the rise of so-called "civilization" was everywhere a process of predatory expansion, producing kingdoms and empires where top males achieved astounding heights of reproductive success. This was shown by historical and ethnographic data now strongly confirmed by genomic science. Psychological research confirms that group identity, out-group stigmatization, leadership characterized by charisma, the will to power, narcissism, sociopathy, and cruelty, and followership characterized by hypnotic obedience, loss of individuality, and cruelty are integral parts of human nature. We can thank at least ten or twelve millennia of microevolutionary processes such as those described above, all more prominent in males than females. Followers in wars have faced a difficult risk-benefit analysis, but if they survived and won they too could increase their reproductive success through the rape and other sexual exploitation that have accompanied almost all wars. For modern leaders, social monogamy and contraception have separated autocracy from reproductive success, but only partly, and current worldwide autocratic trends still depend on the evolved will to power, obedience, and cruelty.