Randy J. Nelson

“It is also only in humans that aggression may be used to commit crimes, to enslave others or compel acquiescence to religious or ideological doctrine, or to pursue wars of national interest. At the individual level, men are universally more aggressive than women, and rates of aggressive confrontation are greatest among those who are young, poor, or unmarried. Cultural factors moderate human aggression as well, with men's heightened sensitivity to signs of disrespect, challenge, or threat spawning a high frequency of confrontational violence in so-called “cultures of honor”.”
― Randy J. Nelson, Biology of Aggression

“winning or losing an agonist encounter has a dramatic impact on future aggressive behavior. Winners are more likely to initiate attacks against unknown opponents, whereas losers are more circumspect and likely to retreat from unfamiliar conspecifics, adopting an opportunistic strategy, picking and choosing their fights. In the worst case scenario, animals socially subjugated by constant threat and attack from dominant conspecifics develop a submissive phenotype, showing little or no aggressive behavior, essentially eliminating themselves from the gene pool.”
― Randy J. Nelson, Biology of Aggression