The ethological explanation of aggression, including reference to innate…

The idea

Ethology studies behaviour in the wild and treats aggression as innate and adaptive. Lorenz argued that fights within a species are ritualistic, ending in appeasement displays, so they settle hierarchy and spread animals over territory without killing. The mechanism has two parts: an innate releasing mechanism is a hard-wired circuit tripped by a specific sign stimulus, and it releases a fixed action pattern, a stereotyped, universal sequence that is ballistic once begun. Tinbergen's sticklebacks attacked any wooden model with a red underside, ignored a realistic one without it, and ran the sequence to completion after the rival was removed. Evolutionary accounts add function: Shackelford found mate-retention tactics predicted violence towards wives, cuckoldry being the ancestral cost.

What earns the marks

• Ethology defined: aggression is innate, adaptive and studied in the natural environment, with Lorenz as the named theorist.
• Ritualised aggression: threat displays and appeasement signals limit killing within a species, and the benefits are territorial spread, dominance hierarchy and the survival of the defeated animal.
• Innate releasing mechanism: a sign stimulus activates a built-in neural network that releases the behaviour.
• Fixed action pattern: stereotyped, universal, ballistic, unaffected by learning and triggered by a specific stimulus, demonstrated by Tinbergen's red-bellied stickleback models.

Common mistakes and how to put them right

• Blurring the two technical terms.

  Put it right: The innate releasing mechanism is the trigger circuit, the fixed action pattern is the behaviour it releases.

• Describing Tinbergen's study as being about colour preference rather than about a sign stimulus releasing a stereotyped sequence.

• Forgetting that a fixed action pattern is ballistic, so it continues after the stimulus disappears.

  Put it right: That detail is often the discriminating mark.

• Writing as though evolutionary explanations justify aggression or make it inevitable, when they describe adaptive function only.

Exam tips

• Use both technical terms accurately in the opening sentences of an explain answer, each tied to one animal example, because precise use of the terminology is what the knowledge marks are for.
• Evaluate evolutionary explanations with a named cultural counter-case such as Nisbett rather than the vague claim that they ignore nurture.
• Ethological and evolutionary are separate bullets in the specification; answer the one the question names, because content on the other earns nothing.