Photo illustration is copyright AAAS
When another person’s behavior leaves you with “a bad taste in your mouth,” is that phrase more than a colorful metaphor? A new study of the facial muscles of disgust suggests that moral judgment may have deep biological roots. A distasteful drink, a repulsive photo, and unfair treatment in a game all raise the upper lip and wrinkle the nose via the levator labii muscle, according to experiments by Hanah Chapman and colleagues. The study provides some of the first direct evidence that the human moral system is built—at least in part—from more ancient evolutionary adaptations, the Toronto researchers say in the upcoming issue of Science magazine.