Copulatory urgency is produced by a psychological adaptation that evolved to solve the adaptive problem of sexual conflict resulting from the use of conditional mating strategies. Deployment of a long-term mating strategy, in which individuals invest substantially in the formation and maintenance of an enduring, committed relationship with one partner, puts those individuals at risk of loss of that investment (and more) should their long-term partner pursue a conflicting mating strategy. Consequently, people have evolved motivations, such as copulatory urgency, which protect against that loss. As the potential costs of a partner’s use of a conflicting mating strategy are sex-specific, so too are the manifestations of copulatory urgency. Among men, for whom paternity uncertainty, sperm competition, and cuckoldry are of primary evolutionary concern, copulatory urgency is demonstrated in response to increased risk of a partner’s sexual infidelity and results in behaviors that functioned ancestrally to reduce the risk of cuckoldry. Women, on the other hand, are not subject to maternal uncertainty or cuckoldry. However, women are more likely to be reliant on their long-term male partner’s investment of resources into the ongoing relationship, and so are more likely to demonstrate copulatory urgency and associated motivated behaviors when they are at particular risk of loss of that investment and when the loss of that investment would be particularly costly.

Unlike extensive research conducted on courtship, foreplay, and intercourse, what happens after ejaculation is one of the most neglected dimensions of human sexual behavior. As described in this chapter, postejaculatory adaptations have important and diverse implications for such things as penis hypersensitivity, the refractory period, female infidelity, sperm competition, semen displacement, self-semen displacement, spousal rape, the risk of transmitting sexually transmitted diseases for uncircumcised men, and the incidence of nonpaternity. This chapter also outlines ways to test the Bruce effect in human females and provides a novel explanation for the absence of the Coolidge effect in women.