Ethological Explanations for Aggression
Ethology = the study of the behaviour patterns of non-human animals (including aggression),
usually in their natural environment. (can also use laboratory experiments).
Ethologists believe that the potential to be aggressive is innate, but actual aggression is triggered
by a specific cue (called a sign stimulus) in the environment.
Key ethologists include Lorenz and Tinbergen. They attempt to explain why NHAs behave
aggressively.
Psychologists often try to apply ethological research (theories and studies) to help us understand
human behaviour.
Tinbergen believes that all members of the same species have innate action patterns of
behaviour called fixed action patterns. These include aggressive behaviours.
Fixed action patterns are released by an innate neural circuit in the brain called an innate
releasing mechanism.
1. Build up of action-specific energy
-> (e.g. stickleback males being ready to chase other males out of territory)
-> internal
-> the NHA is preparing to be aggressive e.g. sticklebacks in Tinbergen’s study identifying and
defending territory and access to potential mates in that territory
2. Sign stimulus in the environment
-> (e.g. red underbelly)
-> external
-> triggers aggression
3. Innate releasing mechanism
-> internal
-> a neural circuit that triggers the aggressive behaviour e.g. in humans = amygdala
4. Fixed action pattern
-> external
-> ethologists believe that each conspecific (member of the same species) will behave in the same
aggressive way every time they encounter the same sign stimulus
Adaptive functions of aggression
Ethological explanations suggest that the main function of aggression is adaptive. That is,
aggression is beneficial to survival because a ‘defeated’ animal is rarely killed but rather is
forced to establish territory elsewhere. This means that members of a specific species spread
, out over a wider area and have to discover resources in a different place, which reduces
competition pressure and the possibility of starvation.
Another adaptive function of aggression is to establish dominance hierarchies. male
chimpanzees use aggression to climb their troop’s social hierarchy. Their dominance gives them
special status (for example, mating rights over females). This happens in humans too. This would
be adaptive (and thus naturally selected) because dominance over others brings benefits such
as the power to get your own way and access to resources.
Ritualistic Aggression
A ritual is a series of behaviours carried out in a set order. One of Lorenz’ intriguing early
observations of fights between animals of the same species was how little actual physical
damage was done. Most aggressive encounters consisted mainly of a period of ritualistic
signalling (e.g. displaying claws and teeth, facial expressions of threat) and rarely reached the
point of becoming physical.
Furthermore, Lorenz pointed out that intra-species aggressive confrontations end with ritual
appeasement displays. These indicate acceptance of defeat and inhibit aggressive behaviour in
the victor, preventing any damage to the loser. For instance, at the end of an aggressive
confrontation, a wolf will expose its neck to the victor, deliberately making itself vulnerable to a
single bite to its jugular vein. This is adaptive because if every aggressive encounter ended with
the death of one of the combatants, that could threaten the existence of the species.
Innate Releasing Mechanisms and Fixed Action Patterns
An innate releasing mechanism (IRM) is a built-in physiological process or structure, for
instance a network of neurons (a circuit) in the brain. An environmental stimulus (such as a
certain facial expression) triggers the IRM which then ‘releases’ a specific sequence of
behaviours. This behavioural sequence is called a fixed action pattern (FAP). According to
Stephen Lea (1984), FAPs have six main features:
- Stereotyped, or relatively unchanging sequences of behaviours
- Universal, because the same behaviour is found in every individual of a species
- Unaffected by learning, the same for every individual regardless of experience
- ‘Ballistic’, once the behaviour is triggered it follows an inevitable course and cannot be
altered before it is completed
- Single purpose, the behaviour only occurs in a specific situation and not in any other
- A response to an identifiable specific sign stimulus (or, if it involves communication
between members of the same species, it is known as a releaser)
A03
Ethology = the study of the behaviour patterns of non-human animals (including aggression),
usually in their natural environment. (can also use laboratory experiments).
Ethologists believe that the potential to be aggressive is innate, but actual aggression is triggered
by a specific cue (called a sign stimulus) in the environment.
Key ethologists include Lorenz and Tinbergen. They attempt to explain why NHAs behave
aggressively.
Psychologists often try to apply ethological research (theories and studies) to help us understand
human behaviour.
Tinbergen believes that all members of the same species have innate action patterns of
behaviour called fixed action patterns. These include aggressive behaviours.
Fixed action patterns are released by an innate neural circuit in the brain called an innate
releasing mechanism.
1. Build up of action-specific energy
-> (e.g. stickleback males being ready to chase other males out of territory)
-> internal
-> the NHA is preparing to be aggressive e.g. sticklebacks in Tinbergen’s study identifying and
defending territory and access to potential mates in that territory
2. Sign stimulus in the environment
-> (e.g. red underbelly)
-> external
-> triggers aggression
3. Innate releasing mechanism
-> internal
-> a neural circuit that triggers the aggressive behaviour e.g. in humans = amygdala
4. Fixed action pattern
-> external
-> ethologists believe that each conspecific (member of the same species) will behave in the same
aggressive way every time they encounter the same sign stimulus
Adaptive functions of aggression
Ethological explanations suggest that the main function of aggression is adaptive. That is,
aggression is beneficial to survival because a ‘defeated’ animal is rarely killed but rather is
forced to establish territory elsewhere. This means that members of a specific species spread
, out over a wider area and have to discover resources in a different place, which reduces
competition pressure and the possibility of starvation.
Another adaptive function of aggression is to establish dominance hierarchies. male
chimpanzees use aggression to climb their troop’s social hierarchy. Their dominance gives them
special status (for example, mating rights over females). This happens in humans too. This would
be adaptive (and thus naturally selected) because dominance over others brings benefits such
as the power to get your own way and access to resources.
Ritualistic Aggression
A ritual is a series of behaviours carried out in a set order. One of Lorenz’ intriguing early
observations of fights between animals of the same species was how little actual physical
damage was done. Most aggressive encounters consisted mainly of a period of ritualistic
signalling (e.g. displaying claws and teeth, facial expressions of threat) and rarely reached the
point of becoming physical.
Furthermore, Lorenz pointed out that intra-species aggressive confrontations end with ritual
appeasement displays. These indicate acceptance of defeat and inhibit aggressive behaviour in
the victor, preventing any damage to the loser. For instance, at the end of an aggressive
confrontation, a wolf will expose its neck to the victor, deliberately making itself vulnerable to a
single bite to its jugular vein. This is adaptive because if every aggressive encounter ended with
the death of one of the combatants, that could threaten the existence of the species.
Innate Releasing Mechanisms and Fixed Action Patterns
An innate releasing mechanism (IRM) is a built-in physiological process or structure, for
instance a network of neurons (a circuit) in the brain. An environmental stimulus (such as a
certain facial expression) triggers the IRM which then ‘releases’ a specific sequence of
behaviours. This behavioural sequence is called a fixed action pattern (FAP). According to
Stephen Lea (1984), FAPs have six main features:
- Stereotyped, or relatively unchanging sequences of behaviours
- Universal, because the same behaviour is found in every individual of a species
- Unaffected by learning, the same for every individual regardless of experience
- ‘Ballistic’, once the behaviour is triggered it follows an inevitable course and cannot be
altered before it is completed
- Single purpose, the behaviour only occurs in a specific situation and not in any other
- A response to an identifiable specific sign stimulus (or, if it involves communication
between members of the same species, it is known as a releaser)
A03
