Characteristic sex differences in mating strategies (e.g., choosy females, unselective males) have been claimed by Trivers and other theorists to evolve as an automatic consequence of sex differences in minimum parental investment, arising chiefly from greater female reproductive refractoriness. The theory has been supported by correlational evidence and conceptual analogies to economics. A simulated evolution experiment was performed to provide a clearer test of whether female reproductive refractoriness alone can drive the emergence of differences in mating selectivity. A population of male and female replicators initially differed only in that females were unavailable to mate for a fixed period prior to the appearance of offspring. Over succeeding generations, females evolved far greater selectivity than males with respect to the longevity of potential mates. This greater selectivity was relatively robust with respect to population and genetic parameters, but quantitatively unstable with realistic breeding population sizes.