Conception risk affects in-pair and extrapair desire similarly: a comment on Shimoda et al. (2018)

Although sexual behavior is not under strict hormonal regulation across primates, a large body of work suggests robust ovulatory cycle shifts in women’s sexual psychology and behavior. The adaptive value of such shifts, and the factors that modulate them, are actively debated. Do ovulatory cycle shifts in general libido facultatively allocate resources toward reproduction near ovulation when the benefit–cost ratio of engaging in sexual behavior is high (the motivational priorities hypothesis; Roney and Simmons 2013)? Do within-woman shifts in relative levels of in-pair versus extrapair sexual desire function to recruit good genes for offspring when conception risk is high (dual-mating hypothesis; Pillsworth and Haselton 2006)? Or are any observed shifts simply “spandrels,” or nonfunctional byproducts of between-woman relationships (Havlíček et al. 2015)?