Originally Posted by
Wolfwood
A beautiful face was considered to be so irrespective of the age, gender, sexual preference, race, and culture of the observer. That is to say, a beautiful face is essentially hard-wired into the brain, it's not 'in the eye of the beholder'. These papers focused on faces alone with no makeup, no hair present. In general, those faces with low fluctuating asymmetry were found most attractive, and, surprisingly, the faces that most correlated with a conglomerate average face, were as equally attractive. They found... 'that the average of two human faces was more attractive than either of the faces from which that average was derived. The more faces (of the same gender and age) that were used in the averaging process the more attractive and appealing the average face became. That is so say, average = attractive.
Following the average principle, ugliness would then be defined by extreme deviation away from the average looking face, and then would also have high fluctuating asymmetry. So far as sexual selection goes in animals, this is most certainly the case - it is known as Koinophilia (deviation from average = poor sexual selection), and evidently has a role in humans too, given the evidence on average faces.