They talked until three, from biology to organized religion, and when Amory crept shivering into bed it was with his mind aglow…

(Fitzgerald, This Side of Paradise)

Readers familiar with F. Scott Fitzgerald's early work might recall that in those years just before the Scopes trial he wrote of Victorians who “shuddered when they found what Mr. Darwin was about”; or that he joined in the fashionable comic attacks on people who could not accept their “most animal existence,” describing one such character as “a hairless ape with two dozen tricks.” But few would guess the extent to which his interest in evolutionary biology shaped his work. He was particularly concerned with three interrelated biological problems: (1) the question of eugenics as a possible solution to civilization's many ills, (2) the linked principles of accident and heredity (as he understood these through the lens of Ernst Haeckel's biogenetic law), and (3) the revolutionary theory of sexual selection that Darwin had presented in The Descent of Man and Selection in Relation to Sex (1871). As I hope to show in the following pages, his concern with these issues underlies such well-known features in the Fitzgerald landscape as his insecurity in the “social hierarchy” (his sense of its “terrifying fluidity”), his emphasis on the element of time, his interest in “the musk of money,” his interest in Spengler and the naturalists, and his negative portraiture of male violence. The principles of eugenics, accidental heredity, and sexual selection flow together as the prevailing undercurrent in most of Fitzgerald's work before and after The Great Gatsby, producing more anxiety than love from the tangled courtships of characters he deemed both beautiful and damned.