On the evolution of conspecific aggression

Aggression is defined biologically as a type of social interaction aiming a t a conspecific and reducing its fitness. In order to classify kinds of agg ressive behaviour and violence, evolution of social behaviour has been simu lated by a computer model. Results suggest that the evolution of aggression between conspecifics starts with "unconditional aggression", where injuryi ng fights with everybody are the rule, continues to "unconditional aggressi on paired with the ability to flee,,, and ends with "conditional aggression paired with the ability to flee,,, where injurying fights are avoided betw een g-relatives, but not with non-g-relatives. Thereby, gene relationship, or shortly "g-relationship", is defined as a genetical correspondence betwe en persons or animals with respect to the particular attribute under consid eration, here aggression and its control whereby ritual threatening, domina nce behaviour and peaceful competition function as relationship detectors. Conditional aggression is a strong evolutionarily stable strategy (ESS) sup erseding completely all other aggressive strategies. The evolutionary proce ss results in a homogeneous population of g-relatives behaving non aggressi vely when meeting each other, but who are highly hostile against non-g-rela tives or persons classified as "foreigners". The considerations are useful to discriminate spiteful aggression from other types of violence such as in strumental, explorative, pedagogic, punishing or defending aggression.