The biological explanation of aggression suggests that aggression is caused by genetics, brain structure or bio-chemical influences – hormones such as testosterone and neurotransmitters such as serotonin. It includes only biological factors ignoring environmental, psychological and social factors which are better explained by of the social-psychological explanation.
The first theory linking genetics to aggression was Court-Brown’s research study. Sandberg was the first to identify the 47 XYY karyotype. Normally every human has 46 chromosomes – 23 from the mother and 23 from the father. When a male, has an extra Y chromosome the 47th chromosome it makes them XYY and this would be a genetic disorder. Court-Brown conducted a longitudinal study on 314 males with XYY chromosome and suggested that males with this chromosome would be better hospitalised ‘due to an increased likelihood of aggressive behaviour’. Many institutions took on this idea without further research and as a result many males where hospitalised.
This would support the biological view that genetics can cause a person to become aggressive as Court-Brown provided evidence for this, however after further research he further retracted his comments as much of it was based on assumption. Further research into the XYY karyotype found that the only thing that the extra chromosome affected was physical characteristics such as increased height and it did not affect aggressive behaviour in any way.
Theilgaard also did research comparing XYY to XY and XYY males. She used thematic apperception tests (TATs). She compared prison inmates to the general population. She found that although XYY males were more likely to give aggressive interpretations of the images this did not mean that they would perform aggressive acts in real-life situations. So this would go against what Court-Brown found.
Court-Brown used a lab experiment to conduct his study. A lab experiment is prone to confounding variables because there may be other factors that may influence the outcome of the result. A lab experiment also lacks ecological validity because it is set in an artificial setting and it would be hard to extrapolate findings to real life settings. This would make the study invalid. Also Court-Brown did not operationalize aggression. Many people view aggression in many different ways – from verbal aggression to physical aggression. So what kind of aggression did the males show? As aggression was not clearly defined this could lead to inaccurate results.
Therefore Court-Brown’s research would be hard to rely on as it is hard to measure aggression in a uniform way. Theilgaard’s research also had some short-comings – She used a TAT test to measure aggression within her sample. TAT tests have no empirical validity as they are just images, by describing what is in a picture the participate won’t be acting aggressively they are merely stating/interpreting what they see, therefore the use of TAT tests does not show the XXY male is aggressive in real life situations and findings should be treated with caution.
Overall the genetic approach is heavily reductionist as it does not include other approaches such as social and cognitive approaches. It just assumes that genetics are the main cause of aggression. However by being reductionist it could lead to further psychological research into the area and this might produce more insights into the theory. The genetic theory also over-emphasises the importance of nature and ignores nurture completely. They may be other factors other that genetics that play a role in aggression for example, a person’s up-bringing may cause them to act aggressively or the type of culture they belong to may also play a part so to improve its explanation the genetic theory could input some of these ideas into the theory.
Another theory from the biological approach which suffers similar problems like reductionism and determinism is the hormonal/neurotransmitter approach. The approach argues that high levels of the hormone testosterone lead to aggression while low levels of the neurotransmitter serotonin lead to aggression. Wagner et al. did research which supported the link between aggression and testosterone.
They castrated mice and found that levels of aggression decreased and that there was also a drop in male typical behaviours such as biting. When the mice received testosterone injections levels of aggression started to increase. This would support the view that levels of testosterone can lead to aggression. Another study in this area was by Harrison, he gave male participants aged 20 -56 testosterone injections and then gave them a frustrating game to play. He noted that aggression did increases in all of the men but to differing extents. Furthermore affects were mainly psychological and there were few physical affects.