Maggots, vomit, faeces, sores oozing with pus, putrid meat - these evoke universal reactions of disgust. But why do we have this Yuk! reaction and how did it evolve? Valerie Curtis of the London School of Hygeine and Tropical Medicine, explains the sources and importance of revulsion in this episode of the Social Science Bites podcast. Social Science Bites is made in association with SAGE.