The study, published in the journal Philosophical Transactions of the Royal Society B, surveyed more than 2,500 people online.
‘Women regard risky sexual behaviour as very disgusting, apparently as a result of an instinct to minimise the risk of catching diseases.’
The researchers listed 75 potentially 'disgusting' scenarios the participants might encounter, ranging from people with obvious signs of infection, pus-filled skin lesions and objects teeming with insects, to listening to sneezes and defecation in the open.
Participants were asked to rate the strength of their disgust response to each scenario on a scale ranging from "no disgust" to "extreme disgust".
Of all the scenarios presented, infected wounds producing pus were rated as the most disgusting.
The violation of hygiene norms, such as having bad body odour, was also found to be particularly disgusting.
Interestingly, the survey results showed that there were gender differences in reactions to the disgusting scenarios that were presented, with women rating every category more disgusting than men.
The categories women in the study found most disgusting were risky sexual behaviour and animals carrying disease.
"This type of disease avoidance behaviour is increasingly evident in animals, and so leads us to believe it is evolutionarily very ancient," said study senior author Val Curtis, Professor at London School of Hygiene and Tropical Medicine.
"Increasing our understanding of disgust like this could provide new insights into the mechanisms of disease avoidance behaviour, and help us develop new methods to keep our environments, fellow animals and ourselves healthy," Curtis said.
By analysing participants' responses, the researchers were able to identify common categories of disgust, which each relate to regularly occurring types of infectious disease threat in our ancestral past.
Historically for example, eating rotting food could have led to diseases like cholera, close contact with unhygienic people could have transmitted leprosy, promiscuous sexual practices could have put an individual at risk of syphilis and contact with open wounds could have led to the plague or smallpox infection.
The results confirm the 'parasite avoidance theory', in which disgust evolved in animals, encouraging them to adopt behaviours to reduce the risk of infection.
This behaviour is replicated in humans where disgust signals us to act in specific ways, which minimise the risk of catching diseases.