The Long and the Short of it: Testing the Conversion and Cuckold Strategies of Ancestral Human Outgroup Mating

The human social group likely aided in ancestral human’s survival. However, the small-knit extended kin group in which human ancestors evolved posed a plausible reproductive threat in the form of inbreeding. The outgroup mating hypothesis (Salvatore, Meltzer, & Gaertner, under review) proposed that, as a solution to the inbreeding dilemma, ancestral females may have mated outside their social group. The current work examines two competing hypotheses by which ancestral females mated with outgroup males and balanced parental investment concerns. The conversion hypothesis posits that ancestral females mated with an outgroup male under the provision that he and his group would care for the offspring. The cuckold hypothesis proposes that ancestral females furtively mated with an outgroup male while retaining primary partner and group support for the offspring. The current work uses multiple methods and measures to test the competing hypotheses against one another. Study 1 manipulates women’s motivational state to reflect a short-term sexual (i.e., one-night-stand) or long-term committed (i.e., marriage) mate-seeking strategy and measures attraction to ingroup and outgroup men. Study 2 uses a restricted response window and assesses evaluations of ingroup and outgroup men for sex and marriage partners. Study 3 uses a version of the affect misattribution procedure (Payne et al., 2006). Results of Study 1 indicated strong support for the conversion hypothesis. Results of Study 2 and Study 3 were inconclusive. I suggest that ancestral women who mated with an outgroup man and converted to his collective received a fitness benefit over ancestral women who did not. Implications of results and future directions are discussed.