It is shown in human mate selection that factors humans find attractive are symmetry, outward cues of good health, physical attributes of reproductive success.
Humans have overtime changed many of their criteria for physical beauty, but the constant seems to be the above traits.
If one accepts the theory of evolution and random mutation then it would stand that overtime the traits that proved advantagous would be passed on generation to generation. However I do not feel the physical beauty of a person was all that important. Otherwise how does one explain so many unattractive people finding mates to procreate with?
"You were not there for the beginning. You will not be there for the end. Your knowledge of what is going on can only be superficial and relative" William S. Burroughs