Let me first start by talking about the purpose of taste. An apple tastes good to us, not because it's just inherently tasty (if that makes sense at all) but it's because our taste buds have evolved indicate that apples (and other items as well) are fit for human consumption. I mean, it's no surprise that items which we can consume for nutritional value tastes good (bread, fruits, vegetables, etc.) while things that harm us don't (feces, mud, rocks, dirt, etc.) In the same sense, beauty can be thought of as an isomorphism of taste. What we percieve as beautiful may actually be an evolutionary impulse, telling us what who we should try to breed with and who to avoid. Now, I know some of you will come reply with stuff like: "My last girlfriend was sooo hot, but she totally was bad for me." That's not exactly the type of beauty I'm talking about. I'm talking about the general/universal indicators of beauty: curvature on a woman (fit for child-bearing), broad shoulders on a man (powerful, hence able to support the family), smooth complexion (overall good health), etc. In this sense, beauty is simply natural selection at work. But also keep in mind that the invention of modern cosmetics, as well as new cultural influences have distorted these natural indicators of universal beauty. A classic example is how curved and voluptuous woman are no longer attractive, while wire-thin and overly tall is allegedly beautiful now. It would be interesting to consider how these cultural influences (sexual selection if you will) will interact with the natural selection of beauty.