A 40-year-long experiment analyzed the sexual selection of seed beetles—one group was allowed to mate freely (strong sexual selection) while another had one male mated with one female only (weak sexual selection). Every single life form on Earth is the tireless work of evolution spread across billions of years. Of course, within our measly human lifespans, it’s extremely difficult to observe these genetic changes in real time—but not impossible. “The populations that evolved under conditions of strong sexual selection ended up being far more different from each other—both genetically and in reproductive characteristics. They suggest that future studies could employ various methods for strengthening this tenuous-yet-compelling link between the strength of sexual selection and genetic evolution.