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According to Shweder and his colleagues (1997), purity norms can govern a range of issues, including what foods can be eaten, who is fit and unfit to prepare them, and how foods must be cleaned or treated before they can be eaten. Purity norms also address the specifics of which sexual activities are permissible and what is forbidden, deviant, or “dirty”; allowable and inappropriate sleeping arrangements involving the members of nuclear and extended families; what sorts of clothes can and cannot be worn at different times or in specific places and settings, especially in temples and other sacred locations, or during religious rituals; how a range of organic matter, such as corpses, blood, feces, and so on, should properly be dealt with to avoid the risk of pollution; and which other social groups one can interact with, as well as how and when it is permissible to interact with them, and how to avoid becoming tainted by members of “lower” groups. The subject matter of the issues governed by such norms shows a fairly clear affinity with the subject matter regulated by disgust, and the defining contrast between purity, on the one hand, and dirt and contamination, on the other, further implicates the emotion. The Co-opt thesis holds that disgust will provide the motivation for individuals to comply with purity norms that they have acquired, and that disgust also shapes the punitive motivations that are directed at violators. Initial experimental evidence has begun to flesh out this picture in more detail (Rozin et al. 1999).
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Daniel Kelly (Yuck!: The Nature and Moral Significance of Disgust (Life and Mind: Philosophical Issues in Biology and Psychology))