The structure and function of pathogen disgust.

Researchers have long noted that many of the multiple elicitors of disgust have some relation to infectious disease. There is an emerging consensus that disgust evolved in Animalia to direct the behaviours that reduce risk of infection, so-called 'parasite avoidance theory'. If this is correct, then the disgust motive should be structured in a manner that reflects the ways in which infectious disease can be avoided. In this study, we generated a set of items based on the epidemiology of disease transmission. These were then rated for their capacity to elicit disgust by a large, predominantly North American/UK sample and subjected to factor analysis to identify latent variables. While a number of plausible factor solutions emerged, Velicer's MAP (minimum average partial) test suggested six domains: atypical appearance, lesions, sex, hygiene, food and animals. This structure did not exactly mirror the transmission routes of infections, as we initially predicted, but it may rather reflect distinct kinds of behavioural tasks involved in avoiding disease. This finding makes sense from the perspective of a cognitive system that evolved under selection for a behavioural response to threats from the social and biological environment. We suggest that regularly occurring types of infectious disease problems have produced regularities in the domain structure of pathogen disgust and discuss the implications of these results for understanding the structure, function and measurement of motives such as disgust in humans and other animals.This article is part of the Theo Murphy meeting issue 'Evolution of pathogen and parasite avoidance behaviours'.