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.