Ethological explanations

Basic assumptions

• Aggression is instinctive, innate and adaptive for survival

• The potential for aggression is innate and triggered by environmental stimuli/releasers

• Aggression has an evolutionary value

Innate releasing mechanism (IRM)

Biological structure in the brain which is activated by releasers

Fixed action pattern (FAP)

Sequence of pre-programmed behaviour triggered by IRM

Ritualistic aggression

Series of behaviour which aims to scare off competitors without physical confrontation

Lorenz

Most aggressive behaviour between species is ritualistic signalling which is beneficial as it stops either individual getting hurt

Tinbergen

Studied stickleback fish during mating season (males become highly territorial and develop a red spot on their bellies).

Used fake fish with red bellies to test whether the red spot triggers aggression and found that males always became aggressive when seeing the red spot and never became aggressive if it wasn’t present, even if the fish otherwise looked like a stickleback.