Introduction
Introduction
Outline and evaluate the role of genetic factors in aggressive behaviour (5+16 marks)
Moghaddom (1998) distinguishes between explanations of aggression which are normative, and those which are causal. Causal explanations, as in this case, suggest aggression is determined by particular factors e.g. genes and are usually biological explanations. The genetic explanation of aggression suggests that it is influenced through our genes, and that such behaviour is therefore inherited.
Para 1 A01
Para 1 A01
It is thought that aggression is due to a defective gene that is inherited by following generations. One possible gene is the Monoamine Oxidase A gene, which produces Monoamine Oxidase A enzyme that breaks down neurotransmitters associated with aggression. It is thought that a build-up of serotonin and dopamine can cause an individual to act aggressively to stress in the fight or flight response. There are two forms of the gene, MAOA-H (produces a high level of the enzyme) and MAOA-L (produces a low amount of the enzyme). The presence of the MAOA-L gene is related to an increase likelihood of aggression. One third of people in Western countries have the MAOA-L gene, compared to two thirds in countries with a history of warfare; leading the gene to be dubbed with the term “warrior gene”.
Para 2 A02
Para 2 A02
Research to support the role of the MAOA gene comes from Cases et al who disabled the gene in the X chromosome of mice. As no enzyme was produced, the levels of serotonin and dopamine in the brain increased. It was observed that males became highly aggressive (females were unaffected) and by restoring the function of the gene, their behaviour retuned back to normal. This suggests that the gene does in fact increase aggression when not working, supporting the role of genetic factors in aggressive behaviour. However, the research cannot account for aggression in females as they also carry the X chromosome, which implies that other extraneous variables may be interacting with the gene to cause aggression only to occur in the male mice. This is a problem, as we cannot fully conclude that the gene was the sole cause of aggression and therefore it does not fully support the genetic explanation.
Para 3 A02
Para 3 A02
One weakness to the theory of the MAOA gene comes from Caspi et al, who found that low levels of the enzyme due to the MAOA-L gene did increase aggression but only where individuals had experienced some form of maltreatment during childhood. This implies that aggression may not be purely down to genes, but also the role of an individual’s environment; thus demonstrating the interplay of the external environment and internal genetics.
Para 4 A02
Para 4 A02
Another supportive piece of evidence comes from Brunner, who discovered the defective MAOA gene in a Dutch family with a history of male violence. This therefore suggests that the defective gene does play a role in human aggression as it shows a correlation between aggression and the defective gene. However, as this is only 1 case it is hard to generalise the findings to a wider population, implying that the evidence may be less reliable. The findings also lack ecological validity as this was only observed in a Dutch family and may not be the general trend for everyone. This is a problem as the evidence cannot fully support the theory that genetic factors influence aggression, and implies that more research is needed for a conclusive explanation.
Para 5 A01/A02
Para 5 A01/A02
Mednick et al observed that adopted children, whose biological fathers were criminals, were more likely to be aggressive than adopted children whose adopted fathers were criminals. He stated that the aggression that may lead to becoming a criminal is influenced by our genetics. Research to support this theory comes from Hutchings & Mednick, who found a significant number of boys with criminal convictions had biological fathers with convictions. This implies that there is a link between aggressive behaviour leading to a conviction and the individuals inherited genetic predisposition. This supports the explanation that aggression is influenced by inherited genetic mechanisms.
Para 6 IDA
Para 6 IDA
The argument that aggressive predisposition can be inherited has been used as a defence for many criminals. They argue that as their family had a history of violence, they too have inherited this genetic tendency to be so and therefore they should not be held accountable for the crimes that they commit. However, this argument is deterministic as it assumes that everyone who inherited the genetic potential to be aggressive will be so. It does not take into account individual differences of exerting free will over aggressive behaviour, which is a problem as this may lead to implications within the legal system regarding whether or not we can hold a person responsible for their aggressive actions, due to pre-programed genetic information. This is therefore a socially sensitive issue.
Para 7 A02/A03
Para 7 A02/A03
Another piece of research to supports the link between genetic factors and aggression comes from Lagerspertz, who bred 25 generations of mice with the most aggressive bred together and least aggressive bred together. This resulted in two different strains of mice; super-aggressive and docile therefore demonstrating how aggressive behaviour is passed down through genetics and supports the role that genes play in influencing such behaviour. However, a weakness of using non-human evidence is the fact that it may not be possible to extrapolate the findings from animal behaviour to human behaviour, due to the fact that human behaviour is too complex and may not be influenced in the same way. This is a problem as it suggests that the reliability of such research is questionable and cannot fully support the genetic explanation of aggression.
Para 8 A02/IDA
Para 8 A02/IDA
Another issue that this particular piece of research raises is the problem of defining aggression as it can be displayed in many forms. The researcher may conclude the mice behaviour as “aggressive” simply because this is their personal opinion of what aggressive behaviour consists of, or because they want to produce the dependent variable that they set out to measure in the research, thus showing observer bias. The mice may simply being showing dominant behaviour, which may be a completely separate behaviour to aggression. This is a problem, as a lot of the research into the influence of genetic factors and aggression may not be measuring what it intends to measure, therefore reducing the validity of the explanation. This implies that a broader definition of aggression is needed to support the genetic explanation of aggression.
Para 9 IDA
Para 9 IDA
A general weakness of the genetic explanation of aggression is the fact that it focuses solely on biological factors and does not take into account the behavioural approach and the role of learning. We can therefore say that it leans towards a nativist theory, rather than an empiricist one. For example, Bandura et al (1961) demonstrated that children’s aggressive behaviour was influenced through the social learning theory. His findings show that an experimental group, that had observed an adult behaving aggressively towards a bobo doll, showed more aggressive behaviour and were more likely to imitate the role model than the control group, who had not. This supports the theory that observation and imitation leads to an influence on aggressive behaviour. This is a problem as a purely biological approach may be too narrow to explain aggressive behaviour as it does not take into account a broader range of factors. A multi- perspective approach may be needed.
Para 10 IDA
Para 10 IDA
A second weakness of the genetic explanation of aggression is due to the fact that it does not take into account the role of environmental factors. For example, McGue et al conducted a twin study and found a concordance rate, between genetics and aggressive behaviour, of 0.43 between MZ twins and 0.30 between DZ twins. This does imply that genes play a role in aggressive behaviour as MZ twins share 100% of their genes whereas DZ only 50%. However, the concordance rate may be due to environmental factors rather than genes as MZ twins may be frustrated by being treated so similarly and therefore this could be the trigger for the increased aggression. This is a problem as it is a reductionist approach to break down a complex behaviour such as aggression into a simple genetic cause and effect. This suggests the explanation less reliable and implies that a holistic approach is needed.
Conclusion
Conclusion
There is a general lack of support for the genetic explanation of aggression which is demonstrated by Watlers, who conducted a meta-analysis and found low correlation between the role of genetics and aggressive behaviour. This implies that there is not a strong enough link to suggest a cause and effect relationship and therefore the genetic explanation lacks validity. Aggression may also be caused by other factors which the explanation does not investigate. For example, genetic factors may cause a potential for aggression but this may only arise from environmental cues. Another problem surrounding the explanation is due to the the ideas that have stemmed from it into treating aggression by genetic engineering. As the explanation highlights the role that genetics plays in violence and aggression, it therefore justifies such treatments, which raises many ethical issues. Can we really engineer human emotion and behaviour? To conclude, a broader range of approaches and factors needs to be assessed before implementing a conclusive explanation for aggressive behaviours