The Grapevine

Feeling Disgusted Is A Mechanism To Avoid Diseases

For the first time, a British study revealed distinct categories that trigger the most disgust, which in turn, help us avoid disease. The study titled "The structure and function of pathogen disgust" was published in a special issue of the Philosophical Transactions of the Royal Society

For the study, more than 2,500 participants were surveyed by the London School of Hygiene & Tropical Medicine (LSHTM) in England.

"Although we knew the emotion of disgust was good for us, here we’ve been able to build on that, showing that disgust is structured, recognizing and responding to infection threats to protect us," said Professor Val Curtis, senior author at LSHTM. "This type of disease avoidance behavior is increasingly evident in animals, and so leads us to believe it is evolutionarily very ancient. Increasing our understanding of disgust like this could provide new insights into the mechanisms of disease avoidance behavior, and help us develop new methods to keep our environments, fellow animals and ourselves healthy."

The online survey included 75 potentially "disgusting" scenarios such as people with obvious signs of infection, pus-filled skin lesions, objects teeming with insects, listening to sneezes, defecation in the open etc. As a response to each scenario, the respondents were asked to rate their level of disgust on a scale ranging from "no disgust" to "extreme disgust."

Overall, infected wounds producing pus were rated as the most disgusting. The other top-rated categories included poor hygiene, skin conditions (having lesions or boils), rotting food, having an atypical appearance, animals or insects carrying disease, and risky sexual behavior.

Gender was a major influencer with reactions as women rated every category more disgusting compared to their male counterparts. Previous research that has shown men may indulge in riskier behavior than women on average reflected in the aforementioned difference. Risky sexual behavior and disease-carrying animals were the most disgusting categories according to women in the study.

The researchers were able to correlate these triggers to certain types of infectious disease threats regularly occurring in our ancestral past. Examples include eating rotten food leading to diseases like cholera, contact with unhygienic people transmitting leprosy, promiscuous sexual practices transmitting infections like syphilis, and contact with open wounds causing the plague or smallpox infection.

"Although we only really came to understand how diseases transmit in the 19th century, it’s clear from these results that people have an intuitive sense of what to avoid in their environment. Our long coevolution with disease has 'wired in' this intuitive sense of what can cause infection," said co-researcher Micheal de Barra, a lecturer of psychology at Brunel University in London.

Rather than disgust directly corresponding to categories of a disease threat, the study found disgust in the brain to be more closely linked to actions taken to avoid disease.

"This corresponds to an evolutionary view of the emotions which are for action; emotions make us do things that put us in a better state with respect to our survival and reproduction," stated the press release.

The researchers expressed interest in future studies to compare triggers of disgust across cultures and investigate how moral disgust may relate to disease disgust.