For example, according to evolutionary psychology, coalitional aggression is more commonly found with males. This is because of their psychological mechanism designed since ancestral times. During those times men had more to earn when winning wars compared to women (they had more chance of finding a mate, or even many mates). Also, the victorious men had more chance of reproduction which eventually led to the succession of aggressive, eager-to-war DNAs. As a result, the authors hypothesize that countries with more men will tend to show more aggressive politics thereby having more possibility of triggering conflicts within and especially among states.