In my kitchen, as I turn my homegrown habaneros into hot sauce while wearing a respirator (I’m not kidding) I have my own small celebration of the evolutionary serendipity that has allowed pain-loving humans to enjoy such tasty pain.
Some experts argue that we like chilies because they are good for us. They can help lower blood pressure, may have some antimicrobial effects, and they increase salivation, which is good if you eat a boring diet based on one bland staple crop like corn or rice. The pain of chilies can even kill other pain, a concept supported by recent research.
Others, notably Dr. Paul Rozin at the University of Pennsylvania, argue that the beneficial effects are too small to explain the great human love of chili-spiced food. “I don’t think they have anything to with why people eat and like it,” he said in an interview. Dr. Rozin, who studies other human emotions and likes and dislikes (“I am the father of disgust in psychology,” he says) thinks that we’re in it for the pain. “This is a theory,” he emphasizes. “I don’t know that this is true.” . .
But he has evidence for what he calls benign masochism. For example, he tested chili eaters by gradually increasing the pain, or, as the pros call it, the pungency, of the food, right up to the point at which the subjects said they just could not go further. When asked after the test what level of heat they liked the best, they chose the highest level they could stand, “just below the level of unbearable pain.” As Delbert McClinton sings (about a different line of research), “It felt so good to hurt so bad.”
http://www.nytimes.com/2010/09/21/science/21peppers.html?_r=1