The human love of symmetry is a biological part of us, because it helps us to choose genetically more advantageous mates, with fewer genetic abnormalities and better nutritional upbringing. Both genetic abnormalities (such as Marfan's Syndrome) and severe nutritional deficiencies (such as Vitamin D deficiency also called Rickets when severe) can cause abnormal fetal and developmental growth patterns resulting in bodily asymmetry, both gross and subtle.
While what we consider beautiful can be modified by culture, at least some characteristics of beauty are very much cross-cultural. A love of symmetry in the body generally and the face in particular, is not restricted to this culture - and it's not surprising that a contrary love of mutations hasn't prevailed instead. Most mutations, most of the time are pernicious, and sexual selection for abnormality in bilateral symmetry in particular would raise the probability of miscarriage and early death in the offspring of organisms with this preference, selecting them out of their species, in time.
Which is just to say that this love of symmetry is unlikely to be merely human, but present in animals which choose mates (during the day at least, so frogs maybe not so much).
First posted June 25, 2004