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The Winnower and is the backstory behind
Yoshizawa, K., R. L. Ferreira, Y. Kamimura, and C. Lienhard. 2014. "Female penis, male vagina, and their correlated evolution in a cave insect." Curr. Biol. 24: 1006-1010. doi: 10.1016/j.cub.2014.03.022.The penis is, by definition, the male copulatory organ (e.g., New Oxford American Dictionary). Sex-specific features are not restricted to copulatory organs, and many examples of sex-specific elaborations are known, such as the horns of antlers or the decorative feather of peacocks. Evolution and exaggeration of sex-specific elaborations have attracted the attention of many biologists, including Darwin (Darwin 1871). It is now widely accepted that sexual selection promotes the evolution of elaborate sex-specific features (Trivers 1972). Because sexual selection usually acts on the male, sex-specific elaborations are frequent in male, and the male penis is highly diversified morphologically and functionally whereas female genitalia are usually simple (Eberhard 1985).