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=== Mechanism === | === Mechanism === | ||
[[File:Peacock courting peahen.jpg|alt=|thumb|"The females may be dull looking, but they're very picky." A peacock courting a peahen]] | [[File:Peacock courting peahen.jpg|alt=|thumb|"The females may be dull looking, but they're very picky." A peacock courting a peahen]] | ||
Fisherian runaway is a selection process occurring over many generations, in which the one sex (either male or female) becomes more choosy about a heritable trait for the simple reason that it will make the offspring more attractive. As the the choosiness for the trait increases, the selective pressure to prefer the trait increases too, forming a [https://en.wikipedia.org/wiki/Positive_feedback_loop positive feedback loop]. In response to the increased choosiness, the other sex evolves to enlarge, overcomplicate or beautify that trait in efforts of becoming more attractive, eliciting [https://en.wikipedia.org/wiki/Supernormal_stimulus super-stimuli] in the opposite sex. The exponential nature of positive feedback loops exerts a strong selection pressure that the resulting exaggerate may reduce mobility and increase vulnerability to predators and to sudden environmental changes. | |||
Since females are [[Bateman's principle|more choosy]] in many species throughout the animal kingdom (including humans), the males tend to be more ornamented. | Since females are [[Bateman's principle|more choosy]] in many species throughout the animal kingdom (including humans), the males tend to be more ornamented. |