A01

• Ethological explanations focus on the adaptive function of the behaviour. Aggression is beneficial for survival as it can force a defeated animal to establish territory elsewhere, allowing the victor greater access to resources. It also helps establish dominance hierarchies, which facilitates access to mates.
• Actual physical aggression does not happen often, but instead animals rely on ritualistic signalling during most aggressive encounters (e.g. displaying claws and teeth). This also includes appeasement displays, which are behaviours which indicate acceptance of defeat (e.g. wolf exposing its neck). Ritualistic aggression is adaptive because it potentially prevents the extinction of a species if every aggressive encounter would end in a death.
• An innate release mechanism (IRM) is a physiological process (e.g. network of neurons) that can trigger a fixed action pattern (FAP) following an environmental stimulus. A FAP is a specific sequence of behaviour which is stereotyped (always the same) and universal (same behaviour for all members of a species). Research has shown that male stickleback fish are triggered by red underbellies (environmental stimulus) which causes them to behave aggressively (FAP).