From the physorg.com article:
In everyday language, people sometimes say that immoral behaviours “leave a bad taste in your mouth”. But this may be more than a metaphor according to new scientific evidence from the University of Toronto that shows a link between moral disgust and more primitive forms of disgust related to poison and disease.
“Morality is often pointed to as the pinnacle of human evolution and development,” says lead author Hanah Chapman, a graduate student in the Department of Psychology. “However, disgust is an ancient and rather primitive emotion which played a key evolutionary role in survival. Our research shows the involvement of disgust in morality, suggesting that moral judgment may depend as much on simple emotional processes as on complex thought.” The research is being published in Science on February 27, 2009.
Read the article here.