Try to note and understand the interrelationship and assumptions made to justify the emotion of disgust. Definition of Evolution: Evolution is change in the heritable traits of biological populations over successive generations. It was proposed by Charles Darwin, arguing that species assimilate traits over successive generation. These traits are selected according to previous generations that had a higher chance of survival than their counterparts and therefore could lead a more ‘successful’ (in biological terms, had more offspring due to longer lifespan, better mate attraction and retention, etc) lifestyle. Assumptions Made at Beginning: Some behaviours are engraved in our genetics, such as disgust, happiness, aggression etc. And according to the theory, the behaviour that is with us from birth must have had some survival upsides to it for us to have inherited it. This Essay will deal with the behaviour of disgust. The emotion of disgust is largely connected to 2 studies.
First of all, the most recent of the studies if the study conducted by Fessler in 2006. During the first trimester of Pregnancy the immune system is slows its function down so as to have the body accept the baby. He argues that the emotion of disgust allowed our ancestors to survive long enough to produce offspring, who in turn passed the same sensitivities to us. He asked 496 healthy pregnant women between ages 18 – 50 to rank 32 potentially disgusting scenarios. He also asked the women if they were experiencing morning sickness. Women during the first trimester had a higher level of intensity for disgust sensitivity than women in their second and third trimester. With a control on the morning sickness, Fessler could pinpoint food as a major source of disgust in a pregnant women’s day to day life.
A lot of diseases are food borne. Ancestors probably learned disgust as a method to stay away from a food that caused a disease or killed their family member. This can be seen in pregnant women in an enhanced form as said earlier the immune systems shuts down its function to some extent. While this is worse to the pregnant women it is also harmful to the foetus as the foetus could die easily from even a small disease, hence disgust serves as a child protection method ensuring the future of the species. This study supports the role of disgust in helping reproduction, and thus, as an evolutionary behaviour.
The second study is by Curtis et al. done in 2004. Studied the Disgust reaction in over 75000 people from 165 people (Large Reach and can be said to relate to most humans), had them rate 20 images on their level of disgust. Out of the 20 images, there were 7 pairs where one was infectious or harmful to the immune system and the other was similar but non-infectious. The disgust was ranked stronger for images that were infectious/harmful to the immune system than the ones where they were non-infectious. Disgust seemed to decrease with age and women had a higher disgust sensitivity towards the images than the men. Natural selection may have helped human ancestors to be more disgusted at things which threatened the immune system, to avoid things that could potentially lead to diseases or sickness. The decrease of disgust with age may be explained by the fact that the older a member of a species, the less likely they are to reproduce. Therefore, their disgust reaction (that can prevent death of offspring) decreases. The stronger disgust reaction of women may be because of women being carriers for offspring, they have a stronger disgust reaction so as not to threaten the lives of unborn offspring and consequently, the species.
This study supports the role of disgust in aiding reproduction, and thus, as an evolutionary behaviour. Darwin’s theory of evolution is based on the key assumption of Natural Selection, those who adapt best to environmental challenges will have characteristics better suited to the environment and are more likely to reproduce and pass on these traits. Natural selection results in adaptation – successive generations of a species developing characteristics that make it more competitive in its field. Along with these there is an evolutionary explanation of disgust. Fessler (2006) showed that disgust may be an evolutionary behaviour as it assists in reproduction of offspring by compensating for a suppressed immune system. Curtis et al. (2004) found that the disgust reaction may help to prevent illnesses. Research suggests that disgust aids the survival of the human species and is therefore an evolutionary behaviour.
Psychology Review Notes 