Men pursuing a relatively slow life history strategy produced higher quality ejaculates, reflecting resource allocation decisions for greater parenting effort, as opposed to greater mating effort

Barbaro, N., Shackelford, T. K., Holub, A. M., Jeffery, A. J., Lopes, G. S., & Zeigler-Hill, V. (2018). Life history correlates of human (Homo sapiens) ejaculate quality. Journal of Comparative Psychology. http://dx.doi.org/10.1037/com0000161

Abstract: Life history strategies reflect resource allocation decisions, which manifest as physiological, psychological, and behavioral traits. We investigated whether human ejaculate quality is associated with indicators of relatively fast (greater resource allocation to mating effort) or slow (greater resource allocation to parenting effort) life history strategies in a test of two competing hypotheses: (a) The phenotype-linked fertility hypothesis, which predicts that men pursuing a relatively fast life history strategy will produce higher quality ejaculates, and (b) the cuckoldry-risk hypothesis, which predicts that men pursuing a relatively slow life history strategy will produce higher quality ejaculates. Men (n = 41) completed a self-report measure assessing life history strategy and provided two masturbatory ejaculate samples. Results provide preliminary support for the cuckoldry-risk hypothesis: Men pursuing a relatively slow life history strategy produced higher quality ejaculates. Ejaculate quality may therefore reflect resource allocation decisions for greater parenting effort, as opposed to greater mating effort. The findings contribute informative data on correlations between physiological and phenotypic indicators of human life history strategies.