ethological explanation of aggression

Question 1

Claims that aggression is adaptive to reduce competition so aggression is beneficial to survive because:

Answer 1

1- reduces competition- a defeated animal is rarely killed but instead forced to establish dominance elsewhere = members of a species spread out and have to discover resources in different niches = reduces competition pressures and consequent potential starvation

2- establishes dominance hierarchies- for example, in male chimpanzees who use aggression to climb their troop’s social hierarchy; their dominance gives them special status such as mating rights over females

Question 2

Explain how established dominance hierarchies occurs in humans too

Answer 2

• Petit et al observed how aggression in playground played an important role in how some children became dominant over others
• therefore adaptive and thus naturally selected because dominance over others brings benefits e.g. power to get your own way and access resources

Question 3

Explain how much aggression is ritualistic

Answer 3

• ritualistic behaviour refers to a series of behaviours carried out in a set order
• Lorenz observed that most aggressive intraspecific encounters consisted predominantly of a period of ritualistic signalling e.g. displaying claws and teeth along with facial expressions of threat and rarely reached the point of becoming physical

Question 4

Most intra-specific aggressive confrontations also usually end with ritualistic appeasement displays which indicate

Answer 4

• acceptance of defeat and inhibit aggressive behaviour in the winner preventing any damage to the surrendered animal
• for instance, at the end of an aggressive confrontation, a wolf will expose its neck to the winner deliberately making itself vulnerable which is adaptive because if every aggressive encounter ended with a death of one of the individuals, that could threaten the existence of a species

Question 5

Explain function of IRMs

Answer 5

• Innate release mechanisms (IRMs) are built-in physiological processes or structures such as a network of neurones in the brain
• an IRM acts as a kind of ‘filter’ identifying and recognising relevant I.e. threatening key stimuli in the environment- sign stimuli
• sign stimuli activate the IRM which then trigger a specific sequence of behaviour- a fixed action pattern (FAP)

Question 6

What is a fixed action pattern?

Answer 6

Sequence of stereotyped or pre-programmed behaviours triggered by an IRM (which is activated by a sign stimulus)

Question 7

FAPs share common characteristics:

Answer 7

• ritualistic
• universal
• ballistic (follows an inevitable course which cannot be altered before it is completed) e.g. yawning

Question 8

What’s a key study supporting the idea of FAPs?

Answer 8

Tinbergen- Male sticklebacks

Question 9

Explain Tinbergen’s procedure

Answer 9

• Male sticklebacks are highly territorial during mating season and they simultaneously develop a red spot on their underbelly
• another male entering their territory initiated a sequence of highly stereotypical, ritualistic aggressive behaviour- FAP
• Tinbergen presented Sticklebacks with a series of wooden models of different shapes but with a red spot visible

Question 10

What were Tinbergen’s findings?

Answer 10

• regardless of shape, if the model had a red spot the Stickleback would aggressively display and even attack it
• but if there was no red spot, there was no aggression (even if the model looked realistically like a Stickleback)
• Tinbergen also found that these aggressive FAPs were unchanging from one encounter to another- once triggered, the FAP always ran its course to completion without further stimulus

Question 11

What are evaluation points for ethological explanation?

Answer 11

✅ Tinbergen + variation 
✅ Eibl- Eibesfeldt human FAPs
❌ fixed action patterns not so fixed 
✅ Hoebel song duels 
❌ lions kill off cubs of rival males and Male chimpanzees often kill members of other groups 
❌ IRMs and biological determinism

Question 12

Explain Tinbergen + variation

Answer 12

• when red spot covered, despite being mating season, Stickleback did not show any signs of aggressive intent or behaviour

Question 13

Explain Eibl- Eibesfeldt human FAPs

Answer 13

• identified human FAPs such as smiling and eyebrow-raising when greeting
• however they claimed that humans developed much make f,edible behaviours and this was more adaptive than FAPs

Question 14

Explain fixed action patterns not so fixed

Answer 14

• sequences of behaviour that appear to be fixed and unchanging are in fact greatly influenced by environmental factors and learning experiences
• so FAPs are more flexible than implied by term ‘fixed’
• many ethologists now prefer the term modal action pattern to reflect this
• in reality, a FAP is typically made up of several aggressive behaviours in a series- the duration of each varies from one individual animal to another, and even in the same animal from one encounter to another
• flexibility of FAPs implies that aggressive behaviours can be learned or at least affected by environmental influences, challenging the validity of the theological explanation

Question 15

Explain IRMs and biological determinism

Answer 15

• explanations which rely on IRMs are biologically deterministic because they ignore the possibility of free will
• suggest that IRM triggered by a single sign stimuli and FAP will occur consistently
• humans though are able to override their innate tendencies e.g. use of contraception