|MadSci Network: General Biology|
Beauty is a matter of perception. If we think about this in evolutionary terms it will make sense why symmetry would affect beauty. When choosing a mate, it is important for animals to chose a mate that will produce healthy strong offspring. It becomes important then for the animal to be able to detect the health and strength of their mate by looking and interacting with that mate. Many animals do this be looking at the brightness of plummage, the ability to dance in a complicated fashion, the ability to fight of competitors, or some combination of these.
For humans, one way for us to perceive the health of our mate is to look at them and see if they are 'beautiful'. The mind is programmed to see something that is perfectly symmetrical as most beautiful. If you think about this, perfect symmetry would imply that the person was healthy, or lacked genes that would cause assymetry.
There are of course other factors that we use in choosing a mate.
I hope this answers your question.
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