Many small-scale societies, including nomadic hunter-gatherers, are commonly referred to as “egalitarian,” meaning that equality of political influence is valued and enforced by societal norms. In general, however, the egalitarian principle applies only to married men. Husbands tend to dominate both bachelors and women, thanks partly to their controlling of coercive social institutions, especially law and religion. Egalitarian societies are thus routinely dominated by a sub-group composed principally or entirely of married men. I call this sub-group the alpha-alliance. In non-egalitarian societies male-dominated alpha-alliances appear to be universal, albeit headed by a leader. The conclusion that virtually all human societies are dominated by an alpha-alliance composed mainly of older males is rarely discussed, but it is important because it raises questions about the evolution and dynamics of political systems. Primatological, paleoanthropological and ethnographic data suggest that around 300,000 years ago, alpha-alliances originated in an evolutionary novel style of coalition used by subordinate adult males to eliminate individual alphas as reproductive competitors. This superficially minor novelty had huge consequences, because a subgroup of subordinates who could cooperate to kill an alpha could kill anyone. That meant that when temporary coalitions of killers evolved into a longterm alliance, the alliance had unconstrained power over the rest of society. Nowadays imprisonment has largely replaced execution as the threat used by alpha-alliances, but whether via imprisonment or execution, overwhelming coercive power continues to allow older males to dominate society far more completely than occurs in any non-human mammal. The alpha alliance’s use of coercive power appears to have had diverse evolutionary effects on human society and psychology, including patriarchy and a moral sense of right and wrong.