|A man saw something that made him feel disgusted. / Photo by: Master1305 via Shutterstock|
Disgust is a natural human behavior. In most cases, humans feel this whenever they see or touch what they deem is "icky" or unpleasant. Individuals might sometimes feel ashamed for feeling disgust towards certain situations, such as being presented with raw food and meat. However, recent studies show that disgust had been protecting humans from harmful diseases over the past centuries.
Disgust from the Ancient Past
The feeling of disgust has been discovered to save humans from obtaining unwanted bacteria and harmful viruses. Disgust has six triggers that prevent humans from walking towards pathogens even before these bacteria were identified. According to Mícheál de Barra from the Brunel University of London, “It is unlikely to be a coincidence that many of the stimuli that elicit the emotion of disgust in humans are also implicated in the transmission of infectious disease.” To prove this connection, authors Val Curtis and De Barra conducted a survey among 2,500 individuals. They were asked about the situations or instances when they felt disgust. The pictures to be rated from "no disgust" to "extreme disgust" were the following:
* Your friend shows you a big, oozing lesion on his foot.
* Feeling something sticky on a door handle.
* You pour lumpy stale milk on your cereal.
* A hairless old cat rubs up against your leg.
* Watching a woman pick her nose
* On television you see someone eat a raw fish head.
* Seeing a cockroach run across your path.
Their survey showed that most of the participants felt disgust toward wounds containing pus. The second leading instance is when they smelled bad body odor. Curtis and De Barra further categorized the results into six common instances, including poor hygiene, promiscuous sex, atypical appearance, blisters, and spoiled food.
This is the first time researchers considered diseases as triggers of disgust. As mentioned in the article published in the journal by the London School of Hygiene and Tropical Medicine, "The researchers say these findings could help to target public health messaging, for example, to encourage handwashing with soap or to counter the stigma associated with sickness.” The results led the researchers to identify the categories that have protected human ancestors from diseases like cholera, leprosy, syphilis, and other plagues. Curtis and De Barra’s research also supports the "parasite avoidance theory" that discussed how disgust was included in the evolution of animals. They adopted certain behaviors, protecting them from infection. As stated by Curtis, "This type of disease avoidance behavior is increasingly evident in animals, and so leads us to believe it is evolutionarily very ancient.”
The research also showed gender differences among the various reactions of disgust. Women have rated more factors than men, which also supports the theory that men are more capable of indulging in risky situations than women.
However, Psychology Professor Paul Rozin from the University of Pennsylvania argued by saying that for researchers to fully understand the factors of disgust, they must first look into human evolution. On the other hand, assistant researcher Schaich Borg at Duke Institute for Brain Sciences claimed that “disgust types may be better understood by the behaviors they elicit … than by the cues that elicit them.” Although other researchers consider collecting online data as a weak presentation of the study, Curtis and de Barra continued working on their study. As they mentioned in an interview with CNN, “We are using disgust in behavior change campaigns, for example, to get people to build toilets and wash their hands with soap in countries like India and Tanzania.”
Studying Disgust Among Animals
|A dog saw something disgusting. / Photo by: Kalamurzing via Shutterstock|
Animals can experience disgust too. In fact, researchers from Kyoto University conducted a study focusing on bonobos and their reactions showing disgust. Just as Curtis and De Barra discovered the effect of disgust on humans, these researchers have also proven that disgust can also protect animals from certain infections and diseases. As stated by lead author Cecile Sarabian, “Current studies suggest that animals evolved a system to protect against such threats, now known as the adaptive system of disgust; For example, bodily fluids are universal disgust elicitors in humans, and recently, we published evidence that the same reaction exists in our primate cousins."
Moreover, bonobos were discovered to avoid contaminated food. They also have the tendency to prevent engaging in "exploratory activities" like touching and using materials reeking of a foul smell. Their infants, however, display the same traits as human children. They have less precaution when it comes to the factors that trigger disgust.
The study continues to explore the connection of disgust between primates and humans. One of the authors in this research, Andrew Macintosh, stated: “...We need more information about how they might react to a range of new foods before we can try to link food-neophobia with contamination sensitivity in other primates."