Definition
Disgust is the emotion of rejection — the visceral "get this away from me" response. It evolved to protect the body from contamination: spoiled food, waste, signs of disease. Its facial expression and physiology are recognizable across cultures.
Behave is interested in what happens when this ancient food-and-disease system gets pointed at people and ideas. Disgust extends readily from the physical to the moral, and that extension has serious consequences.
Why it matters
How it works
The insula, a brain region that registers physical disgust at something rotten, also activates at moral disgust — at unfairness, betrayal, or a person deemed repugnant. Behave argues this overlap is not a coincidence of metaphor but a real piece of shared machinery: the moral system borrowed the contamination system.
That borrowing is dangerous. When a group becomes an object of disgust, people treat it the way they treat a contaminant — to be avoided, excluded, or eliminated rather than reasoned with. Propaganda exploits this directly, describing despised groups as filth, vermin, or disease. Because disgust sensitivity differs across people and tracks with political orientation, the same social situation can feel neutral to one person and contaminating to another.