Why do so many modern people hate insects? The urbanization-disgust hypothesis

摘要

While negative perceptions of insects and other terrestrial arthropods (hereafter referred to collectively as 'insects') are widespread around the world, the underlying causes of this phenomenon remain unknown. Negative attitudes towards insects manifest as the emotion disgust, which is regarded as a psychological adaptation to produce pathogen-avoidance behavior. Based on theories of evolutionary psychology (parasite avoidance theory of disgust and error management theory), we hypothesized that there are two pathways by which urbanization increases the intensity and breadth of feelings of disgust towards insects: (1) urbanization increases the extent to which people see insects indoors, and insects that are seen more often indoors induce stronger feelings of disgust than is induced by insects seen outdoors; and (2) urbanization reduces people's natural history knowledge about insects, and decreased knowledge results in a broader range of insects eliciting feelings of disgust. To test our hypothesis, we conducted a large-scale online questionnaire survey and questionnaire experiment (n = 13,000) across Japan to quantify the association between the level of urbanization, places of insect sightings (outdoor/ indoor), knowledge about insects, and respondents' feelings of disgust. Our results supported both hypothetical pathway and suggested that psychological mechanisms shaped by past evolutionary pressure to avoid pathogen infection may underlie the current prevalence of insect disgust, and this is being reinforced by urbanization. Because negative perceptions of nature can reduce motivation for its conservation, negative attitudes towards insects exacerbated by ongoing urbanization is a potential global risk for biodiversity.