The new synthesis about disgust is that it is a system that evolved to motivate infectious disease avoidance. There are vital practical and intellectual reasons why we need to understand disgust better. Practically, disgust can be harnessed to combat the behavioural causes of infectious and chronic disease such as diarrhoeal disease, pandemic flu and smoking. Disgust is also a source of much human suffering; it plays an underappreciated role in anxieties and phobias such as obsessive compulsive disorder, social phobia and post-traumatic stress syndromes; it is a hidden cost of many occupations such as caring for the sick and dealing with wastes, and self-directed disgust afflicts the lives of many, such as the obese and fistula patients. Di...