I remember a Discover magazine article on something similar from when I was just a little kid. I can't recall the exact thesis, but the basics was that researchers were using an algorithm to combine pictures of people into a single face.

The interesting thing was that the more pictures they combined into a face, the more attractive the face became! Of course, once they added enough faces, and the male and female pictures became almost the same androgynous face - still attractive but too average to be appealing in my (3rd grader at the time) opinion.

Beauty as an average seems like a strange concept at first, but I suppose it's true that people aren't usually attracted to sharp or surprising facial characteristics.