3. The ethological explanation for aggression

• Aggression is adaptive - AO1

  - Reduces competition

  - Establishes dominance hierarchy
• Reduces competition - AO1

  - Defeated animal is rarely killed but forced into territory elsewhere. This reduces competition pressure
• Establishes dominance hierarchy - AO1


  - Male chimpanzees dominance gives them special status as it allows them to move up the social hierarchy - like mating rights with women.
• Pettiti et al (1988) - AO1


  - Observed how aggression in playgrounds played an important role in how some children become dominant over others.

  - Adaptive (naturally selective) - dominance brings benefits
• Ritualistic aggression - AO1


  - A series of behaviours carried out in a set order
• Lorenz (1966) - AO1


  - Observed most aggression between organisms from the same spices was mainly ritualistic and rarely became physical
• Intra species aggression - AO1

  - Aggression between same species

  - Usually ends with a display/acceptance of defeat - appeasement

  - Adaptive - death of an individual could threaten existence of species
• Inmate realising mechanism - AO1

  - IRM

  - Built in psychological process or structure

  - e,.g network of neurons

  - Allows us to identify threatening stimuli

  - Activated by environmental stimulus
• A fixed action patterns - AO1

  - FAP

  - pattern of behaviours triggered by IRM
• Lea (1984) - AO1


  - found six main features of FAP
• Six features of FAP identified by Lea (1984)


  - Stereotype - behaviour always occurs in same form

  - Universality - The behaviour is found throughout the spices

  - Independence of experience - the behaviour is not learnt

  - Ballistic - The action cannot be changed once imitated

  - Singleness of purpose - Behaviour used for a single context

  - Triggering stimulus - behaviour triggered by known stimulus
• Tinbergen (1951) - background - AO1


  - Male sticklebacks are highly territorial during spring mating season when they also develop a red spot on them under belly

  - If another male enters their territory - sequence of highly stereotyped aggressive behaviours is initiated - a FAP

  -Seeing the red sport acts as a stimulus which triggers their IRM that in tern leads to aggressive FAP
• Tinbergen (1951) - procedure - AO1


  - Presented male sticklebacks with a series of different shapes
• Tinbergen (1951) - findings - AO1


  - Regardless of shape if model had a red spot the sticklebacks would aggressively display or even attack it

  - No red spot there was no aggression even if model looked like stickleback

  - Tinbergen found that these aggressive FAPs were unchanging from one encounter to another.

  - Once triggered, the FAP also ran its course of completion without further stimulus
• Supporting research - 😊

  - Research support for ethological explanation can be supported by research looking at genetic and neural influence on aggression

  - Han Brunner et al (1933) - showing low-activity variant of MAOA gene is closely assassinated with aggressive behaviour in humans suggesting innate basis

  - Evidence for existence of innate releasing mechanisms for aggression in the brain - activity in limbic system had been shown to trigger aggressive behaviour

  - As ethological explanation argues that aggression is genetically determined and heritable - its validity is supported by evidence that demonstrates there is a gentic and physiological basis for aggression
• Cultural differences in aggression - 🙁


  - there is evidence to that aggressive behaviour is more common in some human cultures than in others

  - Richard Nisbett (1993) found there was a north-south divide in the United States for homicide rates

  - Killing is more common against white males in southern states than in northern states

  - This was only true for reactive aggression triggered by arguments

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

  - Nisbett's later conducts a study in 1996 which supports his first hypothesis

  - Found that when white males from the south who were insulted in the research situation, were more likely than northern white males to become aggressive

  - Difficult for ethological theory to explain how culture can override innate influences with this view that aggression is an Instinctive behavioural charteristic
• Evidence against ritualistic aggression - 🙁

  - The view that aggression has evolved into self-limiting and physically harmless ritual has been challenged

  - Jane Goodall (2010) - Observed chimpanzees at national park in Tanzania During what she calls 'four-year war' - male chimps from one community set about slaughtering all members of another group

  - This was in a co-ordinated and pre-mediated fashion

  - On one occasion victim was held down while others hit and bit it in an attack lasting up to 20 minutes

  - Violence continued like this despite the fact the victims were offering signs of appeasement and defencelessness.

  - Signals did not stop aggressive behaviour of attacking chips as predicted by ethological explanations