ABSTRACT
Given the chimpanzee evidence, Manson and Wrangham68 propose that imbalance of power must have been an important factor favouring the evolution of damaging aggression in humans also and that, through variability in subgroup size alone, power imbalances may have favoured lethal raiding even before the evolution of weapons. Accordingly, Manson and Wrangham hypothesize that, among foraging humans, where crucial material resources are alienable, inter-group aggression will occur primarily over those resources, while where they are not it will occur over women.
