Reducescompetition as a defeatedanimal is rarelykilled but forced into territoryelsewhere, reducingcompetitionpressure
Establishes dominancehierarchies. A malechimpanzee'sdominance gives him specialstatus (e.g. matingrights)
Pettit et al (1988) observed how aggression in children at play led to dominancehierarchies - this is adaptive (therefore naturallyselected) because dominance over others bring benefits
Ritualistic - a series of behaviors carried out in a setorder
Lorenz (1966) observed most intra-species aggression consisted of ritualisticsignalling (e.g. displayingteeth) and rarely caused physicaldamage
Intra-species aggression usually ends with an appeasementdisplay - indicatesacceptance of defeat and inhibitsaggression in the winner, preventinginjury to the loser
This is adaptive because everyaggressiveencounterending with the death of an individual could threatenexistence of species
IRM - triggered by an environmentalstimulus
An innnatereleasingmechanism (IRM) is an inbuiltphysiologicalprocess or structure (e.g. a network of neurons in the brain)
An environmentalstimulus (e.g. facialexpression) activates the IRM. It triggers or 'releases' a fixedactionpattern (FAP)
FAP - universal and ballistic
A fixed actionpattern (FAP) is a pattern of behaviors triggered by an IRM
Lea (1984) argues that a FAP is a relativelyunchangingbehavioralsequence (ritualistic) found in everyindividual of a species (universal) and follows an inevitablecourse which cannot be altered before it is completed (ballistic)
Tinbergen (1951) Malestickleback and aggression: Procedure
Another maleentering a stickleback'sterritory in the matingseasoninitiates a sequence of aggressive behaviors (a FAP) - red on the competingmale'sunderbelly is the stimulus thaat triggers the IRM that in turn leads to the aggressiveFAP
Tinbergen (1951) presented malesticklebacks with a series of woodenmodels of differentshapes
Tinbergen (1951) Male stickleback and aggression: Findings and conclusions
If the model had a redunderside the stickleback would aggressivelydisplay and attack it - but nored meant noaggression
Tinbergen also found the aggressiveFAP did notchange from one encounter to another - once triggered it always ran its course to completionwithout any further stimulus
One strength is support from research related to genetics and evolution
Geneticevidence is strong e.g. Brunnner et al (1993) showed a link between MAOA-Lgene and aggression, twin and adoption studies also suggest a geneticcomponent
Research by Wilson and Daly (1996) shows aggression as an adaptive behavior and therefore genetically-based
This suggests the ethological approach is correct in claiming that aggression is geneticallydeterminedheritable and adaptivebehavior
Counterpoint for support from research related to genetics and evolution
Nisbett (1993) found homicides based on reactiveaggression (responding to threat) were more common in the southernUS than in the north - 'culture of honor' less prevalent in the north
Therefore culture can overrideinnateinfluences, which is hard for ethologicaltheory to explain
One limitation is that same-species aggression is not always just ritualistic
Goodall (2010) observed malechimpskillingmembers of another community - the aggression was systematic
The killing continued even when victims were offeringappeasementsignals, which did not inhibitaggressivebehavior as would be predicted by ethologicaltheory
This challenges the ethologicalview that same-speciesaggression has evolved into a self-limiting and relatively harmlessritual
Another limitation is that Lorenz's view of FAPs is outdated
Hunt (1973) argued that FAPs are influenced by environment and learning. The sequence of behaviors in an aggressiveFAPvaries between individuals and situations
FAPs are not fixed but modifiable by experience, so ethologists prefer the term 'modalbehaviorpattern' to reflect this flexibility
Therefore patterns of aggressivebehavior are much more flexible than Lorenz thought, especially in humans
Evaluation extra: Born to be aggressive?
Ethologists argue aggression is an innateinstinct, which implies that humans are inevitablyaggressive and will fight each other (e.g. wars), FAPs show this
However, other approaches (e.g. cognitive) suggest aggression is not inevitable, is under rationalcontrol and more affected by learning and socialnorms
Therefore aggression may have instinctiveelements but in humans it is more stronglyinfluenced by cognitive and social factors