Ethological explanation of aggression

AO1

Adaptive functions of aggression: The main function of aggression is adaptive. It is beneficial to survival as a defeated animal is rarely killed, they just have to establish territory elsewhere. Species then spread out, find new resources which reduces competition and chance of starving. Another adaptive function is that it can establish hierarchies. Male chimps use aggression to climb hierachy - they have dominance over resources e.g. fertile females. Pettit found aggression used in play groups played a role in dominance over others. It is adaptive and naturally selected as the dominance allowed them to get their own way and resources.

Ritualistic aggression: Observation by Lorenz showed fights between animals of the same species but little physical damage was done. Most of it was ritualistic signalling e.g. displaying teeth. There are also ritual appeasement displays at the end of intra-species aggressive confrontations which indicates acceptance of defeat to prevent damage to loser. E.g. wolf losers expose their neck to the victor which makes them vulnerable. If all fights ended with death then many more species would't exist. Thus, ritualistic aggression is adaptive.

IRM and FAP: An IRM is a physiological process e.g. neuron networks in the brain. An environmental stimulus triggers the IRM to release a sequence of behaviours called the FAP. Lea states that FAPS have six main features: stereotyped, universal, unaffected by learning, single-purpose, ballistic and are a response to a specific stimulus. 

Research into IRMs and FAPs: Male sticklebacks that are highly territorial during mating season…