The "ant" and the "peacock" stand for two puzzles in Darwinism—altruism and sexual selection. How can natural selection favor those, such as the worker ant, that renounce tooth and claw in favor of the public-spirited ways of the commune? And how can "peacocks"—flamboyant, ornamental and apparently useless—be tolerated by the grimly economical Darwinian reaper? Helena Cronin has a deep understanding of today's answers to these riddles and their roots in the nineteenth century; the analysis is new and exciting and the explanations lucid and compelling.