Ethological Explanation of Aggression (AQA A-Level Psychology): Revision Notes
Ethological Explanation of Aggression
Introduction to the ethological approach
Ethology is the scientific study of animal behaviour in natural environments. Konrad Lorenz, who established this field in 1966, defined aggression as 'the fighting instinct in beast and man which is directed against members of the same species'. This definition highlights two essential aspects of the ethological approach to understanding aggression.
According to ethologists, aggression is an instinct that appears in all members of a species without requiring learning - it is innate and largely genetically determined. Ethologists examine aggression in non-human animals and then apply their findings to humans, based on Darwin's principle that all species are subject to the same evolutionary pressures through natural selection.
The ethological approach is based on three core principles:
- Behaviour is innate rather than learned
- Aggressive behaviour is instinctive and universal across species
- Patterns can be understood through natural selection and evolutionary pressures
Key concepts and definitions
The ethological explanation relies on several interconnected concepts that form the foundation of this theoretical approach.
Core Definitions:
Ethological explanation - An explanation that seeks to understand the innate behaviour of animals (including humans) by studying them in their natural environments.
Innate releasing mechanism (IRM) - A biological structure or process (e.g. in the brain) which is activated by an external stimulus that in turn triggers a fixed action pattern.
Fixed action pattern (FAP) - A sequence of stereotyped pre-programmed behaviours triggered by an innate releasing mechanism.
Stephen Lea identified six key characteristics of FAPs in 1984. These features demonstrate how behaviours are programmed and predictable:
- Stereotyped: relatively unchanging behavioural sequences
- Universal: identical behaviour patterns across all species members
- Unaffected by learning: remains consistent regardless of individual experience
- Ballistic: once initiated, the sequence continues inevitably to completion
- Single-purpose: occurs only in specific situations
- Response to identifiable stimuli: triggered by particular environmental cues (sometimes called releasers in communication contexts)
Adaptive functions of aggression
Ethologists propose that aggression serves important adaptive purposes that enhance survival and reproductive success. When animals are defeated in aggressive encounters, they typically relocate to establish territory elsewhere rather than being killed. This territorial dispersal reduces competition pressure and decreases the likelihood of starvation by spreading individuals across wider geographical areas.
Aggression also establishes dominance hierarchies within species. Male chimpanzees engage in aggressive displays to climb their troop's social ranking, which grants them special status and mating privileges with females. This pattern extends to humans as well.
Gregory Pettit and colleagues studied play groups of young children in 1988 and observed how aggression contributed to establishing dominance relationships among some participants. Such dominance relationships provide adaptive advantages, including greater influence over group decisions and improved access to resources.
Ritualistic aggression
One of Lorenz's most intriguing early observations concerned the limited physical damage that occurred during fights between members of the same species. Rather than engaging in destructive violence, most aggressive encounters consisted primarily of ritualistic signalling behaviours such as displaying claws, baring teeth, or making threatening facial expressions.
Furthermore, Lorenz noted that intra-species aggressive confrontations typically concluded with ritual appeasement displays. These behaviours signal acceptance of defeat and inhibit continued aggressive behaviour in the victor, preventing harm to the losing animal.
Example of Appeasement Behaviour: When a wolf loses an aggressive encounter, it deliberately exposes its neck to the winner, making itself vulnerable to a potentially fatal bite. This adaptive behaviour prevents escalating violence that could threaten species survival.
Innate releasing mechanisms and fixed action patterns
Innate releasing mechanisms function as biological circuits within the brain that respond to specific environmental stimuli. When triggered by appropriate cues, such as particular facial expressions, the IRM releases a corresponding fixed action pattern of behaviours.
The relationship between environmental stimuli, IRMs, and FAPs creates a reliable behavioural system. External triggers activate internal mechanisms, which then produce predictable behavioural responses that serve specific adaptive functions.
The IRM-FAP Relationship: Environmental Stimulus → Innate Releasing Mechanism → Fixed Action Pattern → Adaptive Behaviour
This sequence demonstrates how ethologists believe aggression is automatically triggered and executed without conscious control.
Key study: Research into IRMs and FAPs
Key Study: Tinbergen, Male Stickleback Territorial Behaviour, 1951
Participants: Male stickleback fish during spring mating season
Aim: To investigate whether specific visual stimuli trigger fixed aggressive behaviour patterns
Procedure: Male sticklebacks become highly territorial during spring breeding season when they develop distinctive red spots on their undersides. When other males enter their territory, this initiates a highly stereotyped sequence of aggressive behaviours (a FAP). Tinbergen identified the red spot as the sign stimulus triggering the innate releasing mechanism. He presented male sticklebacks with various wooden models of different shapes to test this hypothesis.
Findings: Regardless of the model's shape or realistic appearance, sticklebacks consistently displayed aggressive behaviour and attempted attacks if the model featured a red spot. However, when models lacked red spots, no aggressive responses occurred, even when the models closely resembled actual sticklebacks. Tinbergen also discovered that these aggressive FAPs remained unchanged across different encounters - once triggered, the behavioural sequence always proceeded to completion without requiring additional stimuli.
Evaluation: Strengths
- Controlled experimental design isolating specific variables
- Clear demonstration of IRM-FAP relationship
- Replicable findings supporting ethological theory
- Natural behaviour studied in appropriate context
Evaluation: Weaknesses
- Limited to single species, reducing generalisability
- Artificial stimuli may not reflect natural triggers
- Cannot directly extrapolate fish behaviour to humans
- Lacks consideration of environmental influences on behaviour
Evaluation
Supporting research
Research by Han Brunner and colleagues in 1993 demonstrated that the low-activity variant of the MAOA gene correlates with aggressive behaviour in humans, suggesting a genetic foundation for aggression. Additionally, studies have shown that limbic system activity triggers aggressive responses in both humans and other animals, supporting the ethological claim that aggression has identifiable biological mechanisms.
These findings validate the ethological explanation by providing evidence for the genetic and physiological bases of aggressive behaviour, consistent with the theory's emphasis on innate mechanisms.
Cultural differences in aggression
Evidence suggests that aggressive behaviour varies considerably between human cultures, challenging the ethological emphasis on universal, instinctive patterns.
Cultural Challenge to Ethological Theory:
Richard Nisbett's 1993 research revealed a north-south divide in United States homicide rates, with significantly higher killing rates among white males in southern states compared to northern states. Since this pattern applied specifically to reactive aggression following disputes, Nisbett concluded that regional differences resulted from a 'culture of honour' - essentially, learned social norms governing responses to perceived threats.
Nisbett and his colleagues supported this interpretation in 1996 by demonstrating that white males from southern regions showed greater aggressive responses to insults in laboratory settings compared to northern participants. This cultural variation poses difficulties for ethological theory, which struggles to explain how learned cultural influences can override supposedly instinctive behaviour patterns.
Evidence against ritualistic aggression
The concept of aggression as primarily ritualistic and physically harmless has been challenged by field observations.
Contradictory Evidence from Field Studies:
Jane Goodall's 2010 studies of chimpanzees at Gombe Stream National Park in Tanzania documented what she termed the 'four-year war', during which male chimps systematically slaughtered members of another community in coordinated, premeditated attacks.
During these encounters, attackers held victims down while others inflicted severe injuries over periods lasting up to 20 minutes. Despite clear appeasement and defencelessness signals from victims, the attacking chimps continued their violence rather than stopping as predicted by ethological theory.
These observations contradict the ethological claim that intra-species aggression naturally limits itself through ritualistic displays.
FAPs are not completely fixed
Morton Hunt pointed out in 1973 that behavioural sequences appearing fixed and unchanging are actually influenced considerably by environmental factors and learning experiences. Rather than being truly 'fixed', action patterns demonstrate more flexibility than the terminology suggests.
Many ethologists now prefer the term modal action patterns to reflect this adaptability. Hunt noted that FAPs typically consist of several component behaviours arranged in sequence, with the duration of each component varying between individual animals and even between different encounters in the same animal.
While this flexibility doesn't necessarily invalidate the ethological explanation - since such adaptability could itself be innate and instinctive - it does raise questions about how truly innate and instinctive aggressive behaviours actually are.
Unjustified generalisation to humans
Lorenz did not study higher mammals such as primates, and Tinbergen chose not to examine the extreme destructive violence characteristic of human aggression. Despite these limitations, both researchers made broad generalisations about human aggressive behaviour, including warfare.
Problems with Human Generalisation:
As anthropologist Robin Fox noted in 2000, war represents 'a collective undertaking that cannot be explained by any individual impulse'. The complexity of human aggressive behaviour, particularly large-scale violence, involves numerous interacting influences including learning, culture, politics, and economics.
Making direct comparisons between simple animal behaviours and complex human social phenomena lacks sufficient justification and undermines the validity of the ethological explanation when applied to humans.
Key Points to Remember:
- Ethological explanation views aggression as an innate instinct triggered by environmental stimuli through biological mechanisms (IRMs) that produce predictable behavioural sequences (FAPs)
- Adaptive functions include territory establishment and dominance hierarchy formation, providing evolutionary advantages for survival and reproduction
- Ritualistic aggression involves signalling and appeasement displays that typically limit physical harm between members of the same species
- Supporting evidence includes genetic research (MAOA gene) and neurological findings (limbic system activity), but contradicting evidence includes cultural variations and observations of extreme intra-species violence
- Major limitations include questionable generalisability from animal studies to complex human behaviours and the flexibility of supposedly 'fixed' action patterns