Ethological and Evolutionary Explanations of Aggression

Ethology is the scientific study of animal behaviour in natural environments. Ethological explanations of aggression draw on observations of animal behaviour to develop theories about the biological basis and evolutionary function of aggression. This lesson examines Lorenz's hydraulic model, Tinbergen's four questions, evolutionary stable strategies, and group display as explanations of aggression.

Key Definition: Ethology is the study of animal behaviour under natural conditions, with a focus on the biological and evolutionary bases of behaviour. Ethological explanations of aggression emphasise innate, species-specific patterns of aggressive behaviour.

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Lorenz's Hydraulic Model (1966)

Konrad Lorenz (1966), in his influential book On Aggression, proposed that aggression in animals (and by extension, humans) is an innate, instinctive drive that builds up over time and must be periodically released.

Key Concepts

Innate Releasing Mechanisms (IRMs)

Lorenz proposed that aggressive behaviour is triggered by specific environmental stimuli called sign stimuli (or releasers). These stimuli activate an innate releasing mechanism (IRM) — a neural circuit that "unlocks" a fixed pattern of aggressive behaviour.