The Ethological Explanation of Aggression (AQA A Level Psychology): Revision Note

The adaptive & ritualistic functions of aggression

• Ethology is the study of animal behaviour and, by extension, human behaviour in terms of traits, characteristics and rituals which have adapted to become useful for survival, e.g., aggression

• Aggression is adaptive because a defeated animal is rarely killed, but rather is forced to establish territory elsewhere, which means members of a species spread out over a wider area and have to discover resources in a different place

  • This reduces competition pressure and the possibility of starvation

Territoriality

• Another adaptive function of aggression is to establish dominance hierarchies,

  • E.g., male chimpanzees use aggression to climb their troop's social hierarchy, and their dominance gives them special status such as mating rights over females

• Territoriality-linked aggressive behaviour may take the form of

  • stags rutting

  • male sticklebacks displaying a red underbelly as a warning to other males

  • a cat arching its back and hissing at other cats to ‘back off’

• Aggressive territoriality is a useful survival strategy, as it results in one animal claiming rights over a specific territory, which means that the rest of the group has to find alternative feeding and breeding areas

  • This spreads the resources around and prevents overpopulation of one area (and possible starvation)

Ritualistic behaviours

• A ritual is a series of behaviours carried out in a set order

  • Lorenz observed that fights between animals of the same species show how little actual physical damage was done, with most aggressive encounters consisting mainly of a period of ritualistic signalling such as displaying claws and teeth, or facial expressions of threat

• Lorenz also pointed out that intra-species aggressive confrontations end with ritual appeasement displays, which indicate acceptance of defeat and inhibit aggressive behaviour in the victor, preventing any damage to the loser

• Signs of surrender include

  • birds turning their head towards a competitor, this is the most vulnerable part of the bird and signals the end to the fight

  • wolves expose their neck to the victor, deliberately making themselves vulnerable to a single bite to its jugular vein

• Human behaviour has some similarities with animal aggression

  • E.g., wars are fought for territories; males may ‘posture’ in front of other males to warn them away from a desired female via lots of shouting, pushing, arms spread wide, etc.

Innate releasing mechanisms & fixed action patterns

• An innate releasing mechanism (IRM) is a built-in physiological process or structure, for instance a network of neurons in the brain, which is triggered by an environmental stimulus such as a certain facial expression

  • The process is instinctive, i.e., it does not have to be learned

• IRMs are thought to comprise a neural network in the brain, i.e., they are inbuilt biological structures

• The environmental stimulus that triggers an IRM is known as a sign stimulus, or a releaser if it involves communication between members of the same species

• Examples of IRM include:

  • a dog sees a cat running away, so the dog’s IRM produces an innate response: ‘chase the cat!’

  • male sticklebacks signal aggression via their red underbellies

    • Tinbergen (1951) presented sticklebacks with a series of wooden models of different shapes, and found that regardless of shape, if the model had a red spot the stickleback would aggressively display and even attack it

    • If the shape was realistic but had no red spot, there was no aggression even if the model looked realistically like a stickleback

• The behavioural sequence triggered by an IRM is called a fixed action pattern (FAP)

  • Tinbergen also found that aggressive FAPs were unchanging from one encounter to another, and once triggered the FAP always ran its course to completion without any further stimulus

• According to Lea (1984), FAPs have six main features:

  • they are stereotyped (relatively unchanging sequences of behaviour)

  • universal (found in every individual of a species)

  • unaffected by learning

  • ballistic (once triggered the behaviour follows an inevitable course and cannot be altered before completion)

  • single-purpose (occurring only in a specific situation)

  • triggered by an identifiable specific sign stimulus

Research which investigates the ethological explanation of aggression

• Nisbett (1993) found there was a north-south divide in the United States for homicide rates, with killings much more common amongst white males in the southern states than in the northern states, but only for reactive aggression triggered by arguments

  • Nisbett concluded that the difference in homicide rates was caused by a 'culture of honour' - a response to impulsive aggression that was a learned social norm

• Goodall (2010) observed chimpanzees at Gombe Stream National Park during what she called the 'four-year war', in which male chimps from one community systematically slaughtered members of another group in a co-ordinated, premeditated way

  • The violence continued even though victims were offering appeasement signals, which did not inhibit the attackers as the ethological explanation predicts

• Cohen et al. (1996) – threats (real or implied) were met with more aggressive responses from males from the southern states of the USA than males from the northern states, i.e., there may be cultural differences in aggression based on learned social norms

Evaluation of the ethological explanation of aggression

Strengths

• Brunner et al. (1993) showed that the low-activity variant of the MAOA gene is closely associated with aggressive behaviour in humans, suggesting an innate basis, and the limbic system has been shown to trigger aggressive behaviour in both humans and other animals

  • As the ethological explanation argues that aggression is genetically determined and heritable, its validity is supported by evidence demonstrating the genetic and physiological basis of aggression

• Some human aggression may be a result of genes (and hence, innate and instinctive), as seen in Brunner et al.’s (1993) study on aggression and a defective MAOA gene

Limitations

• As with any research based on animal behaviour, it is extremely difficult to generalise to human beings, who are more cognitively and socially sophisticated and nuanced than animals

• Lorenz did not study higher mammals such as primates, and Tinbergen chose not to study the kind of extreme destructive violence that is an all-too-frequent feature of human aggression

  • Lorenz also extrapolated from the behaviour of individual animals to the behaviour of entire countries and states, but as Fox (2000) points out, war is a collective undertaking that cannot be explained by any individual impulse

Issues & Debates

• The ethological explanation takes a nomothetic approach, aiming to establish universal laws of aggression by identifying shared biological mechanisms (e.g. IRMs and FAPs) across species

  • This approach allows for scientific investigation and generalisation, especially through controlled animal studies

  • However, it may overlook individual differences in human aggression (e.g., personal experience), making the explanation less applicable to unique human cases

• The ethological explanation exemplifies the nature side of the nature vs nurture debate, arguing that aggression is innate and evolutionarily programmed

  • This downplays the role of environmental learning, culture, and upbringing in shaping human aggression

  • Research like Cohen et al. (1996) shows aggression can vary culturally, suggesting nurture also plays a role