Environmental and biological factors play a role in the manifestation of aggressive behaviour. Discuss the interaction of these variables in the display of hostility.

 The biological triggers for aggression have been widely studied and aggression and fear are behavioural attributes controlled by the amygdala in the hypothalamus within the limbic system. The hypothalamus, apart from its homeostatic control functions, can be associated with behavioural characteristics. These characteristics are usually related to the primitive survival and reproductive instincts of our early human ancestors.2 

        The initial principle of the model signifies that when the neural systems present in our brains are activated, then the individual will respond in an antagonistic manner towards the offending stimulus or stimuli.2 This will usually occur in response to a threat, i.e. in self-defence. These neural systems have a large number of sensory inputs, but only particular patterns of stimuli will cause the neural system to be activated, for example, the predatory aggression neural system in a cat will be activated on seeing a mouse, but not on seeing a dog. Also, these patterns vary for each of the different types of aggression, for example, seeing a mouse triggers the predatory aggressive neural system in the cat but not the neural system for sexual aggression.

        The output to the motor neurons after the neural systems have been activated will also differ depending on the type of neural system stimulated. This can be seen in the outward appearance, or topography, of the aggressive act. For example, when male deer are fighting one another they lower their heads and lock antlers, but when receiving a predatory attack, they raise their hooves.

        The biological framework behind aggression is clear. When an animal is in fear, in pain or sees an opportunity to feed, an aggressive neural system is activated which is reflected in the actions of the animal. The stimulus leads to the response. This is true for humans also. But human aggression is much more complex. Environmental factors play a much bigger role in the onset of aggression in humans than they do in other animals. Examples of these include alcohol, road rage, personal loss, vengeance and the cessation of smoking. To demonstrate that there are factors other than biological, which play a role in the manifestation of aggression and later violent acts, many research groups have thoroughly investigated the environmental factors that can be responsible for these characteristics.

For example, studies have been carried out that have examined the aggressive behaviours of twins and adopted children and they show that, alongside a moderate genetic effect, certain environmental factors, especially the family environment in which a person is introduced to, play the biggest role in the manifestation of aggressive behaviour later in life.3 A study carried out by Bohman suggests that children that are put up for adoption are less likely to become juvenile offenders if they are implemented into a desirable family environment compared to those that are introduced into a less favourable family setting.4 

This study was standardised in such a way that it took into account the genetics of the individuals also. The children were organised into a group with a high congenital risk and a group with a low congenital risk. The genetic risk was estimated based on the biological family history of aggressive behaviour and criminal activity. Those with a higher congenital risk tended to involve themselves in anti-social activities than those adopted children with a lower congenital risk. This suggests that genetics probably plays a role in the manifestation of aggressive behaviour.

        The role of the family environment can therefore be seen to be quite important in the materialization of aggressive conduct. This can be broken down into several key areas of interaction between the parent(s) and the child. There are several types of poor interaction between the parents and their child which can lead to an increased chance of aggression in the child within two years.5 Aspects such as ignoring or rejecting the child and failing to take a large interest in the interests and hobbies of the child have all been continually related to the aggressive behaviours of children.6 But what other environmental factors could play a role in determining whether or not an individual child grows up to be an aggressive adult?

        Children in developed countries now seem to spend more time in front of the television than they do studying in the classroom.7 The violence they are exposed to through this medium has a direct effect on how they will develop as a person, both in their attitude towards themselves and in their social morality in later life. Aggression in their adulthood can be a learned experience from television programmes and films. 23 a recent, and very extreme, example of this was in 1993 when two boys murdered a 3 year old boy, James Bulger, using the same method as they had seen it done in a film, namely “Child’s Play”. 8

        Prior to childhood, there are factors that will induce aggressive behaviour in adults, who have never before shown that they were aggressive individuals. A good example of this is road rage, which is responsible for over two thirds of road traffic fatalities in the United States of America since 2000.9 Road rage can be defined as the resulting violent and criminal behaviour from aggressive driving.10 

A particular driver, being unable to make it to his or her destination in adequate time, usually triggers aggressive driving. Other triggers include congestion and other aggressive drivers. It involves speeding, following too closely and a lack of signalling when changing lanes, along with many other driving offences. This can be dangerous for the aggressive driver and those drivers in the vicinity also. Road rage is not the same thing as aggressive driving however. It is a criminal offence that involves the intensification of a road traffic event. The response of the driver in a road rage incident is usually out of proportion with the offending stimulus they experience and a minor incident can result in a physical fracas or in a violent assault.11

        Another very important factor in manifesting aggressive behaviour and violent acts in an individual is the consumption of alcohol. Alcohol induced violent crimes have become a major problem in society over the last number of years. When a person is under the influence of a large amount of alcohol, they have a false sense of confidence and feel they can handle situations that normally they would avoid when sober. Getting themselves in confrontational situations can lead people, who have consumed a copious amount of alcohol, into violent circumstances. The problem with our society, however, is that drinking a large amount of alcohol and getting drunk has not only become accepted but also sometimes expected.12

        The initial paragraph of this essay gave a brief introduction into the items the essay was planning to discuss. It detailed the points to be discussed in the same order they were actually discussed throughout the main body of the essay. The essay began by defining aggression and giving some general examples of different types of aggression. The essay then centred on the biological signals and biological triggers for aggression and discussed how certain environmental triggers act as stimuli for the onset of a particular type of aggressive behaviour and mannerisms. It achieved this by giving examples of this type of behaviour in animals, which, as we can see, acted as a good model for understanding human aggression. The essay then progressed to talk about the significance of nature versus nurture. It gave details on how significant biological factors and environmental factors are in the onset of aggression. It then gave examples of how this can be proved by studies involving twins and adopted children. Then the essay discussed the role of television in the manifestation of aggression and violent crimes in children giving an extreme recent example of this. The essay then developed into the appearance of aggression and violent acts in adults involving examples of road rage and the consumption of alcohol. Throughout the essay, environmental and biological factors in the manifestation of aggression were discussed along with the interaction of these factors in the presentation of aggressive behaviour. The essay has achieved all its aims.

Word Count: 1898

References

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4. Bohman M. Predisposition to criminality Swedish adoption studies in retrospect. In: Rutter M, ed. Genetics of criminal and antisocial behavior. Chichester: Wiley, 1996.
5. Patterson GR, Reid JB, Dishion JT. Antisocial boys. Eugene, OR: Castalia, 1992
6. Farrington DP. Early developmental prevention of juvenile delinquency. Criminal Behaviour and Mental Health 1994;4:209-27.
7. Black D, Newman M. Television violence and children. BMJ 1995;310:273-274
8. Wolff, S. Children who kill. BMJ 2001;322:61-62
9. Drivers.com staff. The road rage epidemic: hype or reality? .
10. Drivers.com staff. Why it is important to define road rage. .
11. Drivers.com staff. Aggressive driving and road rage: they aren’t the same. .
12. Heather, N. Alcohol, accidents, and aggression. BMJ 1994;308:1254