the ethological explanation of aggression

• fixed action patterns + innate releasing mechanisms: the ethological explanation states that all members of the same species (i.e. conspecifics) have a repertoire of stereotyped behaviours which occur in specific conditions and which do not require learning i.e. innate
• fixed action patterns + innate releasing mechanisms: ethologist Niko Tinbergen called these innate behaviours fixed action patterns (FAPs) , FAPs are produced by a neural mechanism known as an innate releasing mechanism (IRM) and are triggered by a very specific stimulus known as a sign stimulus
• fixed action patterns + innate releasing mechanisms: the IRM receives its input from sensory recognition circuits that are stimulated by the presence of the sign stimulus
• fixed action patterns + innate releasing mechanisms: the IRM then communicates w/ motor control circuits to activate (i.e. release) the FAP associated w/ that sign stimulus
• fixed action patterns + innate releasing mechanisms: Tinbergen's research w/ sticklebacks showed that a male stickleback fish will produce a fixed sequence of aggressive actions when another male enters its territory
• fixed action patterns + innate releasing mechanisms: the sign stimulus in this case is not the presence of the other male but the sight of its distinctive red underbelly that acts as the sign stimulus, if it is covered up the intruder is not attacked (Tinbergen 1951)
• ritualistic aggression: ethologists have shown that not all aggressive behaviour involves fighting but may be ritualised in the form of threat displays
• ritualistic aggression: these threat displays are important for contestants because they help individuals to assess their relative strength before deciding to escalate a conflict
• ritualistic aggression: as a result they make costly and dangerous physical aggression less likely to occur e.g. male gorillas use a variety of different vocalisations (such as hooting) and gestures (such as chest pounding) to intimidate an opponent w/o the need for physical contact
• ritualistic aggression: threat displays are intended to make an opponent back down and are the last step before an animal either fights or submits and leaves
• ritualistic aggression: anthropologists have found evidence of the use of ritualised aggression in tribal warfare in human cultures, Gander and Heider (1968) described how the Dani of New Guinea engaged in highly ritualised patterns of intergroup hostility
• ritualistic aggression: Fox (1978) also found evidence of highly ritualised 'fighting' among males of the Gaelic-speaking Tory Island off the coast of Ireland, where threat displays appear to take the place of actual aggression
• wolves + doves: some species have evolved fearsome weapons that make them effective hunters - wolves e.g. have powerful jaws and strong teeth
• wolves + doves: Lorenz (1952) claimed that such species must also have instinctive inhibitions that prevent them using these weapons against members of their own species
• wolves + doves: when 2 wolves fight the individual who is losing submissively exposes its neck to its adversary then instinctive inhibitions prevent the dominant animal from continuing the fight
• wolves + doves: non-hunting species argues Lorenz have no such powerful natural weapons and therefore have not developed the same inhibitions against hurting their own kind e.g. when 2 birds (such as doves) fight the loser can simply fly away
• wolves + doves: Lorenz believed this comparison had implications for the human species, Humans he argues are more like the dove than the wolf when it comes to dealing w/ other human beings
• wolves + doves: we do not have powerful natural weapons like wolves do and thus have had no need to develop strong instinctive inhibitions against killing one another
• wolves + doves: science and technology has far outpaced out biological evolution as humans have developed weapons of tremendous destructive power w/o also developing instinctive inhibitions against using them
• characteristics of FAPs = stereotyped, universal, independent of individual experience, ballistic and specific triggers
• stereotyped is the behaviour that always occurs in the same way
• universal is the behaviour that is the same in all conspecifics
• independent of individual experience is when the behaviour is innate w/ no learning involved
• ballistic is once triggered the FAP can't be changed or stopped
• specific triggers is when each FAP has a specific trigger (sign stimulus)
• the 'hydraulic model': each FAP has a reservoir of 'action-specific energy' (ASE) that builds us over time, the appropriate sign stimulus causes the IRM to release this energy and the animal then performs the FAP
• the 'hydraulic model': after performing the FAP the reservoir of ASE is empty and the behaviour can't be repeated until the hydraulic model of instinctive behaviour (Lorenz 1950)
• the 'hydraulic model': Lorenz's model provides a way of visualising how these various hypothetical systems might work together to organise an animal's response to its internal and external environment
• the 'hydraulic model': in the model ASE is represented by fluid in reservoir that as it builds up, places pressure on a spring (the IRM) which is also being pulled by weights (the sign stimulus)
• the 'hydraulic model': together these lead to the release of the FAP when ASE is high enough and the appropriate sign stimulus is present, however the FAP may also be produced in the absence of the sign stimulus if the level of ASE is sufficiently high i.e. a behaviour can occur spontaneously
• evaluation S: Lorenz's research has remained a key part of the evolutionary theory of aggression
• evaluation L: ethology when applied to human aggressive behaviour is both determinist and reductionist, it oversimplifies the complex differences between humans and animals, it also suggests that even if humans experience the innate releasing mechanism it does not always determine their behaviour not all humans act upon it as some people exert free will
• evaluation L: the idea of generalising ethological research on aggression to humans is problematic, in humans aggression is used w/ intent to inflict harm whereas in ethology it is used as a ritual, humans females do not want an aggressive male as her partner - this would not be considered an adaptive behaviour
• evaluation L: a problem for the ethological explanation of aggression concerns the claim that predator species must also have instinctive inhibitions that prevent them using their natural weapons against members of their own species, these findings pose a challenge for the ethological explanation of aggression as they cast doubt on the claim that much on animal aggression is ritualistic rather than real