Aggression is seen as having an adaptive advantage, becoming widespreas through natural selection. Lorenz (1996) saw aggression as an instinct that has evolved into rituals, thus protecting animals from incurring harm, because one animal generally backs down. Evolutionary theory sees aggression as a means of solving adaptive problems over a wide range of behaviours, between and within species;
- Between species; prey animals use aggression to defend themselves and their offspring by evolving the ability to gauge the strengthh of predators. The 'fight or flight' respose is depenent on this calculation. Alturistic alarm calls alerting others to the presence of predators have also evolved as a prey defence mechanism.
- Within species; aggression between members of one species serves several purposes, such as establishing dominance hierachies. Males compete for access to females and so are more aggressive to one another.
The emotional response of jealousy is characterised by feeling of resentfulness, bitterness and envy. Jealousy can motivate aggressive behaviours through;