Super-normal stimuli are frequent in many species. The silver-washed fritillary butterfly males are sexually attracted to rotating brown striped cylinders more so than the fluttering wings of their own females. The oystercatcher will abandon its own egg for a supernormal dummy, and the herring gull chicks prefer a red pencil to their own mother’s beak. In humans caucasian and Japanese men are attracted to female faces that are extremely delicate and rare.
The reason for these behaviours is unclear, but it is generally thought that super-normal stimuli indicate a direction in which evolution could proceed. For example a large egg may suggest health and it is better for the oystercatcher to invest energy in incubating it rather than a smaller one that is less likely to hatch. Without such behavioural tendencies evolution would be influenced only by environmental changes, but this shows that animals are ready to select for themselves genetic variation within their own species.
Why then is delicacy such a compelling feature in women? According to Wilson it is likely to be associated with a signal that suggests youth and virginity, both of which are important consideration in selecting a mate for the production of offspring.
Nature, Art & Language
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