A look at disgust from an evolutionary perspective.
Disgust appeared somewhere in the long history of human evolution. We don’t know when and where. The absence of the best sources of evidence leaves the assignment of disgust origins to genetic selection in biological evolution uncertain. Neither contamination sensitivity nor avoidance of decayed substances are present at or shortly after birth in humans, and neither is documented to be present in other primates. The fact that disgust functions to protect humans from microbial contamination is a start for an evolutionary account, but it is far from conclusive. Both fire and antibiotics are parts of the human antimicrobial repertoire, but neither evolved biologically. So just establishing an adaptive value for a trait does not make a strong case for its biological evolution.