Disgust - Evolutionary Significance

Evolutionary Significance

It is believed that the emotion of disgust has evolved as a response to offensive foods that may cause harm to the organism. A common example of this is found in human beings who show disgust reactions to mouldy milk or contaminated meat. Many researchers have claimed that the emotion of disgust functions to protect us from disease. Disgust appears to be triggered by objects or people who possess particular types of features that signify disease.

Self-report and behavioural studies found that disgust elicitors include:

• body products (feces, urine, vomit, sexual fluids, saliva, and mucus);
• foods (spoiled foods);
• animals (fleas, ticks, lice, cockroaches, worms, flies, rats, and mice);
• hygiene (visible dirt and "inappropriate" acts );
• body envelope violations (blood, gore, and mutilation);
• death (dead bodies and organic decay);
• visible signs of infection

The above-mentioned main disgust stimuli are similar to one another in the sense that they can all potentially transmit infections, and are the most common referenced elicitors of disgust cross-culturally. Because of this, disgust is believed to have evolved as a component of a behavioral immune system in which the body attempts to avoid disease-carrying pathogens as opposed to having to fight them after they have entered the body. This behavioral immune system has been found to make sweeping generalizations because "it is more costly to perceive a sick person as healthy than to perceive a healthy person as sickly". Researchers have found that sensitivity to disgust is negatively correlated to aggression because feelings of disgust typically bring about a need to withdraw while aggression results in a need to approach. This can be explained in terms of each of the types of disgust. For those especially sensitive to moral disgust, they would want to be less aggressive because they want to avoid hurting others. Those especially sensitive to pathogen disgust might be motivated by a desire to avoid the possibility of an open wound on the victim of the aggression; however, for those sensitive to sexual disgust, some sexual object must be present for them to be especially avoidant of aggression. Based on these findings, disgust may be used as an emotional tool to decrease aggression in individuals. Disgust may produce specific autonomic responses, such as reduced blood pressure, lowered heart-rate and decreased skin conductance along with changes in respiratory behaviour.

Research has also found that people who are more sensitive to disgust tend to find their own in-group more attractive. This is because people begin to associate outsiders and foreigners with disease and danger while simultaneously associating health, freedom from disease, and safety with people similar to themselves. Although not a justification by any means, this could be an evolutionary explanation for why some people feel racism. When they see others different from themselves, they have an evolved sense of danger arising from a biological desire to avoid potential pathogens brought on by foreigners.

Taking a further look into hygiene, disgust was strongest predictor of negative attitudes toward obese individuals. A disgust reaction to obese individuals was also connected with views of moral values