Discrimination against unattractive people

Beauty is entirely subjective. Even as such, it has no place in determining a person's inner worth.

Symmetry plays an important role in the mating preferences of many animals. A well proportioned body may indicate that the animal possesses an immune system capable of resisting infection by parasites, which are known to cause uneven growth of feathers, wings, fur or bone. Or it may signal a more global robustness, one capable of withstanding scarcity of food, extreme temperatures and other environmental rigours. In theory, a symmetrical mate will provide superior genes; just as individuals who have had a good developmental background are more symmetrical.

Beauty is only skin deep, but ugly goes clean to the bone.

We are becoming more tolerant of adult disabilities, but less tolerant of imperfection in children. Via ultrasound, parents can learn that their foetus will have physical abnormality and may choose to abort it. Consequently, fewer disabled children are now born in industrial countries.