Examine Two Evolutionary Explanations of Behaviour

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Charles Darwin’s theory of evolution puts forward a statement, ‘Survival of the fittest’. This is widely considered true, but in reality truth is a slight variation of this, more commonly known as natural selection. The survivors are the ones who adapt best to their environment and are then able to reproduce. This means that there genes carry on through the generations and we gradually see the preferred characteristics for survival become more common. Over time the human race will become more and more adapted for survival on earth and this process is called evolution.

Psychologists look at the behavioural aspects of people in order to work out whether the behaviour of humans has been determined through evolution. They have done this by studying our mechanism determining levels of disgust and the way we prefer one food or type of food over another food, e.g. taste.

Our way of determining what is ‘disgusting’ is really a way of stopping us from touching or coming into contact with things that would be harmful to us. This is because these things are supposed to impede our ability to survive. Therefore, humans have adapted so that we are disgusted by these objects.

In 2006 Fessler conducted a study on pregnant women who were in their first trimester of their pregnancy and studied their nausea in reaction to certain samples. Fessler hypothesised that these pregnant women would have a higher level of disgust because of their pregnancy. In the first trimester of pregnancy, the immune system of the mother is suppressed so that the foreign body (the baby) growing their womb is safer. Therefore, to keep the women safer, the body develops a heightened sense of disgust to protect itself.

Fessler conducted his research on 496 participants (Ps), pregnant women, who were aged 18-50, but were at different points in their pregnancies. This was in order to separate the results and compare the results of women in their first trimester to those of women in their second or third trimestres. All of these women had had normal pregnancies thus far and were considered healthy. He gave each of the women 32 scenarios and asked the women to rate the scenarios by level of disgust.

Fessler found that women in their first trimester of pregnancy had a higher sense of disgust than those in their second or third trimesters. This supported Fessler’s hypothesis. Therefore, he concluded that the heightened sense of disgust was advantageous, because it allowed our ancestors to survive for much longer and also allowed their genes, which helped them to surviv, to pass to their offspring. The results also show that there was a diminishing level of disease threat when women are pregnant, because there is not as much of a chance that women will become ill from food, because they will be disgusted by these foods. Therefore, the will be more picky about food. This proves the fact that their disgust mechanism has over-compensated, because the immune system is being suppressed.

This study uses a large sample of 496 women. Therefore, the study has population validity. As a result, we can apply the researcher’s findings to a large part of society. Furthermore, the study has cultural validity, because of its large sample. Therefore, it can be applied to people who are from vastly different backgrounds. Lastly, Fessler had a control group to compare results to. This was a group that contained women who were sick in their first trimester and women who were not. The fact that Fessler had a control group makes the results much more reliable. Consequently, we can say that these results are both reliable and valid.

On the other hand, the research has many problems with it. One of which is that there are too many scenarios to rate for disgust. Therefore, the Ps may have become de-sensitised by the end of the scenarios or may have felt more disgusted. Furthermore, these results may not reliable. To obtain more reliable results, Fessler should have only used 15-20...
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