Revenge appears among a of social interactions that includes competition, alliance building (a prerequisite for tribal revenge raids), and so forth. Rather than a modular directly reflecting evolutionary fitness constraints, revenge may be (another) social cost-benefit calculation involving potential or actual aggression and proximately controlled by individual personality characteristics and beliefs that can work against fitness.
Although emotion may subserve social function, as with anger-maintaining dominance, emotions are more than variant cognitions. Anger promotes risk-taking, attention-narrowing, and cognitive impairment. The proposition that appraised “blameworthiness” is necessary for anger excludes young children's anger as well as adults' pain-induced anger. To be complete, any systems model of anger must account for its temporal characteristics, including escalation and persistence.