PassingPsych

Evolutionary psychology is a theoretical approach to psychology that attempts to explain useful mental and physiological traits—such as memory, perception, or language—as adaptations. Evolutionary psychologists argue that behaviours are inherited and promote the survival of humans. Any behaviour that is inherited must be beneficial for survival. An example of an inherited behaviour is disgust, an emotion. There are four automatic responses associated with disgust: closing your eyes, closing your mouth, moving away from the stimulus, and vomiting/gagging. Disgust is a protective mechanism and can be triggered by two things: people and environmental stimuli. In this essay, I will provide a detailed account of the reasons and/or causes for behaviours that are inherited during evolution, using the supporting study of Navarrete et al.

Navarrete et al aimed to investigate the evolutionary basis of disgust across cultures, specifically how the sensitivity caused by disgust can play a role in xenophobia and can cause an increase in positive attitudes towards one’s own cultural group (ethnocentrism). Scientists argue that this is due to the heightened risk of people outside of your in-group carrying potentially harmful pathogens that could damage one’s immune system. Navarrete et al focused on pregnant women during their natural experiment, as the first trimester of pregnancy is a period of particular vulnerability to infection. This is due to a woman’s immune system functioning being reduced so that her body doesn’t fight off the foreign body inside her. To investigate, they used a natural experiment, using self-report techniques, the researchers explored the expression of intergroup attitudes in a sample of pregnant women from the United States. Results showed favouritism toward the in-group peaks during the first trimester of pregnancy and decreases during the second and third trimesters (where immune system function increases again). It was also found that there were no attitudes towards culturally familiar immigrant groups.

Navarrete et al demonstrate that disgust is an involuntary behaviour designed to protect. This is seen in the increase in xenophobic attitudes during the first trimester and the decrease in the second and third trimesters. This is important because the increase in xenophobia during the first trimester is due to a decrease in the function of the immune system. As the body tries to protect against vulnerability, women become more disgusted by people from different cultures to protect against pathogens. Therefore, Navarrete’s study is useful in explaining evolutionary behaviour.