What is responsible for the differences between the sexes in so many animals, from the brilliant plumage of birds of paradise to the antlers on deer? And why are the traits that distinguish the sexes sometimes apparently detrimental to survival? Even when they look more or less alike, why do males and females sometimes behave differently? Questions like these have intrigued scientists and the public alike for many years, and new discoveries are showing us both howwildly variable the natural world is, and how some basic principles can help explain much of that variation. Like natural selection, sexual selection is a process that results from differential representation of genes in successive generations. Under sexual selection, however, the crucialcharacteristics that determine whether an individual reproduces depend on sexual competition, rather than survival ability. This Very Short Introduction considers the history of our understanding of sexual selection, from Darwin''s key insight
