Ethological Explanation Flashcards
Outline adaptive functions of aggression
Aggression is beneficial to survival as ‘defeated’ animal rarely killed, but forced to establish territory elsewhere
This means members of species spread out over wider area & must divscover resources in differente place, reducing competition & possibility of starvation
Another adaptive function of aggression = establishing dominance hierarchies
Male chimps use aggression to climb their troop’s social hierarchy, giving them special status, like mating rights over female
Pettit et al. (1988) studied play groups of young kids & observed how aggression played important role in development of some kid’s dominance over others.
This would be adaptive (thus naturally selective) as dominance over others brings benefits like power to get your own way & assess resources
Outline ritualistic aggression
Ritual = series of behaviours carried out in set order
Lorenz found most of fights between animals of same species had little physical damage
Mostly consisted of ritualistic signalling, e.g. displaying claws & teeth & rarely reached physical
Lorenz pointed out intra-species aggressive confrontations end with ritual appeasement displays
These indicate acceptance of defeat & inhibit aggressive behaviour in victor, preventing damage for loser, e.g. wolf exposes neck to victor, making itself vulnerable to bite to jugular vein
This is adaptive as if every encounter led to death it could threaten existence of species
Outline innate releasing mechanisms (IRM) & fixed action patterns (FAP)
IRM = Inbuilt physiological process/structure, e.g. instance network of neurons in brain
Environmental stimulus (facial expression) triggers IRM, releasing specific sequence of behaviours
Behavioural sequence is called FAP. According to Lea (1984), FAPs have 6 main features:
-Stereotyped/relatively unchanging sequences of behaviours
-Universal as same behaviour found in every individual of species
-Unaffected by learning, same for every individual regardless of xp
-‘Ballistic’: once behaviour triggered it follows inevitable course & can’t be altered before it’s completed
-Single-purpose, behaviour only occurs in specific situation & not in any other
-Response to identifiable specific sign stimulus
USSR BUB
Outline research into the ethological explanation of aggression
Tinbergen research
Male sticklebacks = highly territorial during spring mating season, when they also develop red spot on underbelly
If another male enters territory, highly-stereotyped sequence of aggressive behaviours initiated (FAP)
Sign stimulus triggers innate releasing mechanism = sight of red spot
Tinbergen (1951) presented sticklebacks with series of wooden models of different shapes
Regardless of shape, if model had red spot, male stickleback would aggressively display & attack it
No red spot = no aggression, even if model looked like stickleback
Aggressive FAPs were unchanging from 1 encounter to another, once triggered, FAP always ran its course to completion without any further stimulus
Evaluate ethological explanations for aggression
Strength - RESEARCH SUPPORT RELATED TO GENETICS & EVOLUTIONS
E.g. - Brunner et al. (1993) showed 1 gene (MAOA-L) linked to aggressive behaviour in humans. Twin & adoption studies also showed there’s significant genetic component to aggression in humans. Research points towards innate basis to aggressive behaviour.
Ex. - Suggests ethological approach correct in claiming aggression genetically determined, heritable & adaptive
Limitation - RITUALISTIC AGGRESSION - aggression against members of same species isn’t ritualistic
E.g. - Goodall (2010) observed ‘4-year war’ in which male chimps from 1 community killed all members of another group, they did it in systematic way. Sometimes victim would be held down by rival chimps while others hit in attack lasting minutes. Violence continued even though victims offered appeasement signals. These signals didn’t inhibit aggressive behaviour of attackers as predicted by ethological explanation.
Ex. - Challenges ethological view same-species aggression has evolved into self-limiting & relatively harmless ritual
Limitation - FAPs NOT FIXED - Lorenz’s original view of FAPs is outdated
E.g. - He saw FAPs as innate & unchanging. Hunt (1973) pointed out FAPs actually greatly influenced by environmental factors & learning XPs, e.g. aggressive FAP typically made up of several behaviours in series. Duration of each behaviour varies from 1 person to another & even in same person from 1 encounter to another as they’re modifiable by xp, many ethologists prefer ‘modal behaviour pattern’ to reflect this.
Ex. - Thus, patterns of behaviour more flexible than Lorenz thought, especially in humans
