Steve Gangestad: University of New Mexico Psychology

Broad, ambitious conceptualizations of the evolution of human sexuality (and accompanying unique social,
developmental, and intellectual adaptations) offered by anthropologists and biologists over the last half
century have been, almost universally, rooted in a foundational assumption: That women evolutionarily “lost”
estrus—a distinct fertile-phase sexuality—and instead evolved “continuous” sexuality across the reproductive
cycle, which functioned to “conceal” ovulation. Recent research suggests that this assumption is wrong;
women clearly do exhibit a distinct “fertile-phase” sexuality. This talk addresses a number of questions about
the conceptual significance and theoretical meaning of these recent findings: (a) Is this fertile phase sexuality
appropriately referred to as human “estrus,” and, if so, on what basis?; (b) What selection pressures shaped
fertile-phase sexuality; was it shaped through direct selection or through indirect selection (i.e., as
byproduct)?; (c) Recent evidence also suggests that men respond differently to women as a function of their
phase (typically, being more attracted to women in their fertile phases than women in their luteal phases); is
women’s fertility in fact not concealed? A general reinterpretation of women’s purported “lost estrus,”
continuous sexuality, and concealment of fertility will be offered. The theme that a proper understanding of
human sexuality requires a broader comparative perspective than is often brought to bear in evolutionary
psychology is stressed.