The principle of sexual selection, wrote naturalist Charles Darwin, deals with “the advantage which certain individuals have over others of the same sex and species solely in respect of reproduction.” A peacock’s tail, its marvelous length and iridescence sculpted by female choice, is the iconic example. Beetle horns, the elaborate nests of bower birds, and even the human brain, engine of art, music and speech, further illustrate the power of a positive feedback loop. The more refined a trait, the better suited to attracting mates shall a specimen be. Life, when not about brute struggle, becomes both beauty pageant and talent show.