On the evolutionary purpose of disgust:

What is disgust for? Rozin points out that the human species faces “the omnivore’s dilemma.” Unlike, say, koalas, who mainly eat eucalyptus leaves and are vulnerable when those become scarce, omnivores choose from a vast menu of potential foods. The downside is that many are poison. Many fish, amphibians, and invertebrates contain potent neurotoxins. Meats that are ordinarily harmless can house parasites like tape-worms, and when they spoil, meats can be downright deadly, because the microorganisms that cause putrefaction release toxins to deter scavengers and thereby keep the meat for themselves. […]

Rozin ventured that disgust is an adaptation that deterred our ancestors from eating dangerous animal stuff. Feces, carrion, and soft, wet animal parts are home to harmful microorganisms and ought to be kept outside the body. The dynamics of learning about food in childhood fit right in. Which animal parts are safe depends on the local species and their endemic diseases, so particular tastes cannot be innate. Children use their older relatives the way kings used food tastes: if they ate something and lived, it is not poison. Thus very young children are receptive to whatever their parents let them eat, and when they are old enough to forage on their own, they avoid everything else.