Asked by: Sam Ayling, Surrey
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.
Subscribe to BBC Focus magazine for fascinating new Q&As every month and follow @sciencefocusQA on Twitter for your daily dose of fun science facts.
Authors
Dr Christian Jarrett is a cognitive neuroscientist, science writer and author. He is the Deputy Editor of Psyche, the sister magazine to Aeon that illuminates the human condition through psychology, philosophy and the arts. Jarrett also created the British Psychological Society's Research Digest blog and was the first ever staff journalist on the Society's magazine, The Psychologist. He is author of Great Myths of The Brain and Be Who You Want: Unlocking the Science of Personality Change.
