I'm a biologist by nature, and believe in natural selection and evolution. As a species, the goal of humans, like any other species, is to create good offspring. Note, I said this is the goal of the species, not the goal of mankind -- society and biology are different. Granted, humans are *special* in that we have the ability to adapt our environment to help us suceed when me might not have before (the concept behind agriculture, medicine to cure disease, hell, even glasses and guide dogs helping those with less than perfect eye sight) DESPITE this, we still, as a species, have an inate drive to produce healthy offspring. We may no longer exclude some factors that might have been deal breakers before (I'm so blind I really shouldn't be passing my eye sight genes on, but my kids can wear glasses, so eye sight is not longer a deal breaker)
Many ideals of "beauty" aren't so much beauty, but indicators of health. We like shiny full hair, clear glowing skin, bright open eyes, a symmetrical figure, curves on women, muscle on men. Reason being? Well, the first three indicate that someone has a good diet and a strong immune system (look at any really really sick people who have been sick for a long time, and I assure you they don't have dewy skin and hair out of a Breck ad). Symmetry relates to how well you can perform. Think of it -- would an animal with assymetrical wings or legs be able to survive very well? You'd have a mouse limping along trying to escape a cat . . . . mouse = lunch. Also think of things like visable tumors -- that person isn't symmetrical and isn't healthy. As for the curves thing, science has determined that certain waist to hip ratios correspond to certain fertility rates (tends to go along with increased or decreased fat ratios impact the estrogen production, therefore impacting fertility) *Ironically enough* the hip to waist ration that corresponds to max. fertility is the EXACT figure that a majority of men find most appealing?
Nope -- biology."
--from some blog.