Outline and Evaluate Biological Explanations of Aggression

Outline and evaluate biological explanations of aggression

Research that seeks to explain aggression in terms of our biological make up have found numerous factors within our biology that can have on impact upon our aggressive behaviour. Our neural and hormonal mechanism have been said to impact upon aggression. Gregg purposed that basic aggrieve behaviour comes from certain parts of our brain such as the pre frontal cortex, hypothalamus and the amygdala, which all play a part in our limbic system. Serotonin is one of three important chemicals called neurotransmitters that have an important role in the limbic system. The other two neurotransmitters are called norepinephrine and dopamine. Goodwin et al found that people whom have a history of criminal behaviour, tend to have lower levels of serotonin suggesting that our neurotransmitters within our limbic system can cause a disposition too aggression if there is less serotonin in our system. Similarly, Brunner et al researched into a Dutch family with a long history of violently aggressive males and found that they also had low levels of an enzyme known as monoamine oxidase A (MAOA). This enzyme degrades serotonin, adrenaline and nor adrenaline. Therefore this suggests that neurotransmitters issue the hormones that then pre dispose humans to having aggressive behaviours. Hormones such as adrenaline, noradrenaline and glucocorticoids stress hormones and are influenced by the limbic system. Kruk et al found that aggressive behaviours increased with the levels of ACTH hormone and glucocorticoid hormones. This suggests that long lasting stressors that issue the secretion of such hormones could lead to aggressive behaviour. This could explain why people who are normally non aggressive can sometimes snap, since there may be a sudden rise in our levels of ACTH or a longer lasting period of heightened ATCH. Therefore it can be said that our neural anatomy and hormonal mechanisms can factors into biological explanations of aggression.

Another factors within our biological make up that can effect aggression is our genetic makeup. One of the genes responsible for producing MAOA is associated with aggression.  As previously mentioned low levels of serotonin are associated with aggression. It’s evident that within Brunner’s study of the Dutch family (A large proportion had been involved in serious crimes of violence including rape and arson) the men were found to have abnormally low levels of MAOA in their bodies. A defect in this gene was later found. This suggests that there is a genetic defect that in passed down through our genes.  The role of genetic factors in aggression can also be tested in twin studies. Genes are identical in sets of monozygotic twins but are different between sets of dizygotic twins, meaning that if monozygotic twins are more alike in terms of aggression than dizygotic twins are, this similarity can be attributed to genetics Rhee and Walderman tested the levels of anti-social behaviour of twins using a meta-analysis. They found that monozygotic twins were higher in antisocial behaviour compared to dizygotic twins, this was even more apparent in monozygotic twins that shared the exact same genes and environment. This suggests that levels of aggression can be impacted by our genes, and therefore can explain why some people are more likely to be aggressive. If we have innate genes that control our hormones and aggression levels, we are therefore more likely to act out these aggressive behaviours.

The research into biological explanations does appear to be methodologically flawed due to the lack of internal validity. Brunner’s research into the Dutch family was carried out using self-reported questionnaires and interviews. This therefore may have been impacted by investigator effects. When questioning participants, Brunner may have used leading questions or language that creates demand characteristic such as ‘how aggressive are you and your brother?’ this means that the participants guess that Bruner was researching aggression and genetics. This then impacts on the findings since they will not be true and accurate due to the lack of honesty behind the participant’s answers. Also the findings may have been effected by social desirability. All participants within Brunner’s study had a history of criminal offences, therefore the likelihood that the participants when asked about their criminal history will be more likely to play upon the aggressive role they played during the offences. This then effects the validity of the research because we cannot tell whether the participant has really shown such signs of aggression or if they are playing up to the role of being a criminal. Therefore the research findings cannot be externally applied since it lacks validity and may not be a true and accurate reflection of biological explanations of aggression.

The research can also be criticised for being highly deterministic and ignoring free will. Much of the research into biological explanations of aggression claims that our behaviour is determined by factors outside of our control. For example, Rhee and Waldman suggest that we are born with genes that create per dispositions of how aggressive we are going to be which then will lead to a life with increased anti-social behaviour. This assumes that we are not responsible for our behaviour and this takes away the notion of free will. Humans are therefore deemed as passive and not in control of their behaviour. However Caspi et al studied 500 male children and found those with low levels of MAOA were significantly more likely to display aggressive behaviour but only if they has been maltreated as children. Children with low levels of MAOA and who were not maltreated did not display anti-social behaviour. This suggests that it is even though both children had low levels of MAOA, one set could choose not to act upon their pre dispositions, and this also suggests that our environment has a part to play as well as genes. Therefore the research is also reductionist for not taking environmental factors into account. Children whom had been experienced both aggression from environmental factors and pre disposed were more likely to be aggressive. This suggests that environment plays a part alongside our genes. This is supported by the diathesis stress model that states we are born with pre dispositions but there needs to be a certain stimulus to trigger the predisposition, such as environmental factors. Therefore such biological explanations cannot be used to make universal generalisations since the atomistic view over simplifies and ignores important factors such as our environment and free will.

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