Evidence that disgust evolved to protect from risk of disease

TLDR

Disgust is a powerful but understudied emotion, and current theories fail to explain its purpose or why diverse stimuli elicit it. The authors surveyed more than 40,000 participants online using photographic stimuli. Images depicting potential disease threats were rated significantly more disgusting than similar images with little disease relevance, a pattern observed worldwide, with females showing higher sensitivity, sensitivity declining with age, and bodily fluids of strangers being more disgusting than those of close relatives, supporting the hypothesis that disgust evolved to guard against infectious disease.

Abstract

Disgust is a powerful human emotion that has been little studied until recently. Current theories do not coherently explain the purpose of disgust, nor why a wide range of stimuli can provoke a similar emotional response. Over 40 000 individuals completed a web–based survey using photo stimuli. Images of objects holding a potential disease threat were reported as significantly more disgusting than similar images with little or no disease relevance. This pattern of response was found across all regions of the world. Females reported higher disgust sensitivity than males; there was a constant decline in disgust sensitivity over the life course; and the bodily fluids of strangers were found more disgusting than those of close relatives. These data provide evidence that the human disgust emotion may be an evolved response to objects in the environment that represent threats of infectious disease.