To feel disgust is a fundamental part of human nature. It is one of the most powerful emotions as it drives our innermost habits, social interactions and moral judgement.
Although most of us would rather not feel this unpleasant emotion, feeling disgust is actually an evolved response that protects us from diseases or harm.
Why Disgust Is Good for You
Did you know that even though disgust is an emotion, it comes with physiological elements as well?
Unlike emotions such as fear and anger which can cause your heartbeat to speed up, disgust does the opposite.
It causes your heartbeat to slow down, accompanied with a slight pang of nausea or an upset stomach. This aversion uses the same physiological elements that make up the digestive system.
6 Common Categories of Disgust
The purpose of disgust has been quantitatively revealed for the first time in a new study published in an issue of Royal Society’s Philosophical Transactions B.
Led by the London School of Hygiene & Tropical Medicine (LSHTM), the study doubled down on the theory that humans evolved revulsion to avoid infections and diseases.
More than 2,500 people were surveyed online, listing 75 potentially disgusting situations they might encounter. These include sick, deformed, or unhygienic people, pus-filled skin lesions, dirty environments, and objects with swarmed insects.
The participants were asked to rate the extent of their disgust in response to each scenario from ‘no disgust’ to ‘extreme disgust’.
Of all scenarios presented, pus-filled skin with lesions was rated as the most disgusting, followed by poor hygiene such as having bad body odour.
By analysing these responses, the team was able to identify the 6 common categories of disgust:
Back to the Past
Each category was associated with the threat of infectious diseases in our ancestral past.
For example, historically, consuming rotten food could have led to cholera, promiscuity could risk sexually transmitted diseases, and contact with open wounds could have led to the plague or smallpox infection.
Parasite Avoidance Theory
The results also confirm the ‘parasite avoidance theory’ in which disgusted animals are more prone to adopting behaviours to reduce the risk of infection.
It is also referred to as the behavioural immune system. It is a suite of psychological mechanisms in our brain designed to detect disease-causing parasites in our immediate environment to help us avoid contact with them.
Professor Val Curtis, lead author of the study at LSHTM said, “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, recognising and responding to infection threats to protect us. This type of disease avoidance behaviour is increasingly evident in animals, and so leads us to believe it is evolutionarily very ancient.”
The survey results also showed that there were gender differences in reactions to the disgusting scenarios that were presented, with women rating every category more disgusting than men. This is consistent with the fact that men are known to indulge in riskier behaviour than women on average.
While the 6 categories generally encompass most disgusting things, the extent of disgust may vary depending on the individual.