The ethological explanation of aggression Flashcards
Explain adaptive functions of aggression.
Ethological explanations suggest that the main function of aggression is adaptive and innate. A defeated animal is rarely killed but rather forced to establish territory somewhere else which means members of a species will spread out over a wider area and have to discover resources in another place which reduces competition and the possibility of starvation.
Explain ritualistic aggression.
A ritual is a series of behaviours carried out in a set order. One of Lorenz’s intriguing early observations of fights between animals of the same species was how little damage was actually done. Most aggressive encounters consisted of ritualistic signalling e.g showing teeth and rarely reached the physical point. Furthermore, Lorenz pointed out that intra-species aggressive confrontations end with ritual appeasement displays. These indicate acceptance of defeat and inhibit aggressive behaviour in the victor which prevents damage to the loser. E.g a wolf will expose its neck to the victor deliberately making itself vulnerable.
What is an innate releasing mechanism?
An innate releasing mechanism is a built in hard wired, physiological process or structure e.g a network of neurones in the brain.
What is a fixed action pattern?
An environmental stimulus triggers the innate releasing mechanism which then releases a specific sequence of behaviours called a fixed action pattern.
What are the 6 main features of fixed action patterns?
- Stereotyped
- Universal, the same behaviour is found in every individual of a species
- Unaffected by learning, the same for everyone regardless of experience.
- Ballistic, once the behaviour is triggered it follows an inevitable course and cannot be altered until it is completed.
- Single-purpose, the behaviour only occurs in a specific situation.
- A response to an identifiable specific sign stimulus.
Key study into IRMS and FAP’s (sticklebacks).
Male sticklebacks are highly territorial during their spring mating season when they develop red spot on their underbelly. If another male enters their territory, a sequence of highly stereotyped aggressive behaviours is imitated (a FAP). The sign stimulus that’s triggers this is the sight of the other males’ red spot (innate releasing mechanism). Tinbergen presented sticklebacks with a series of wooden models of different shapes. Regardless of shape, if the model had a red spot then the stickleback would aggressively display or even attack it. If there was no red spot, there was no aggression even if the model was realistic. Tinbergen also found these aggressive FAPs were unchanging from one encounter to another. Once triggered, the FAP always ran its course until completed.
Give a strength of the ethological explanation of aggression. (applicability to humans).
As an evolutionary explanation, genetics form an important element of the explanation. There is evidence that genetics can explain aggression in humans. For example, the low variant of the MAOA gene is linked to aggression as well as concordance rates in twin studies. Therefore, due to the genetic evidence for human aggression which says that aggression is genetically determined and heritable. the ethnological explanation for aggression is strengthened.
Give a limitation of the ethological explanation of aggression. (evidence against ritualistic aggression)
The view that aggression has evolved into a self-limiting and relatively physically harmless ritual has been challenged by observations made by Goodall on Chimpanzees at the Gombe Stream National Park in Tanzania. During what she called the “four-year war”, male chimps from one community set about systematically slaughtering all of the members of another group. They did this in a coordinated and premeditated fashion. On some occasions, the victim was held down by rival chimpanzees and the others hit it, bit it and attacked it. The violence continued even when the victims showed signs of appeasement. These signs did not inhibit the aggressive behaviour as predicted by the ethological explanation.
Give a limitation of the ethological explanation of aggression. (cultural differences in aggression)
There is evidence that aggressive behaviour is more common in some human cultures than others. For example, Nisbett found there was a north-south divide in the United States for homicide rates. Killings are much more common amongst white males in southern states than in northern states. Nisbett concluded that the difference in homicide rates was caused by social norms.
This was supported in his lab study which found that when white males from the south were insulted in a research situation, they were more likely to become aggressive than northern white males.
Give a limitation of the ethological explanation of aggression. (unjustified generalisation to humans)
Lorenz did not study higher mammals such as primates and Tinbergen chose not to study the kind of extreme destructive violence that is a feature of human aggression. However, they both made generalisations to humans from their animal studies. Lorenz extrapolated from the behaviour of individual animals to the behaviour of individual countries and states.
Give a limitation of the ethological explanation of aggression. (fixed action patterns are not that fixed)
Hunt pointed out that sequences of behaviours that appear to be fixed and unchanging are in fact greatly influenced by environmental factors and learning experiences. So fixed action patterns are more flexible than implied by the term fixed. For instance, a FAP is typically made up of several aggressive behaviours in a series. The duration of each behaviour varies from one in ideal animal to another.
