Establishing a link between cultural evolution and sexually transmitted diseases.

It is argued that archaic sexually transmitted diseases influenced cultural traditions by reducing multiple sexual partners within communities. In this article, the adverse consequences of current sexually transmitted diseases are surveyed: Such infections decrease fertility of women and increase infant mortality; those adverse consequences are especially potent when antibiotics are not readily available. Cultural (cross-generational transmission of learned) responses to the threat of widespread infertility and elevated infant mortality rates are hypothesized to include the implementation of expectations for restricted numbers of sexual partners. These expectations, formal or informal, have been instituted within the context of biological predispositions, the "certainty of paternity" model, already-established traditions, and the need for a social father to be aligned with the mother-child dyad. A case study of the contemporary United States is offered as a heuristic example of how and why cultural choices may be developed and sustained.