When psychologists ask people around the world what they find most disgusting, the same things usually crop up. Mostly these are bodily fluids that have the potential to spread disease, such as vomit, mucus, excrement and blood. The implication, which makes a lot of intuitive sense, is that we’ve evolved the disgust reaction as a behavioural defence against contamination.
What’s particularly intriguing is that this system seems to have been adopted by our moral instinct, which is newer in evolutionary terms. For example, many people say they’d refuse to wear a jumper owned by Hitler, as if they could somehow be contaminated by his evil.
