Duration of Cunnilingus Predicts Estimated Ejaculate Volume in Humans: a Content Analysis of Pornography

Humans perform copulatory behaviors that do not contribute directly to reproduction (e.g., cunnilingus, prolonged copulation). We conducted a content analysis of pornography to investigate whether such behaviors might contribute indirectly to reproduction by influencing ejaculate volume—an indicator of ejaculate quality. We coded 100 professional pornography scenes depicting the same male actor copulating with 100 different females, affording control for between-male differences in estimated ejaculate volume. Coders visually estimated ejaculate volume and recorded the time the actor spent engaged in cunnilingus, penile-vaginal penetration, and in any physical contact with his partner. We found support for the hypothesis that a man who spends more time performing cunnilingus produces an ejaculate with greater estimated volume, even after controlling statistically for the age and attractiveness of the actress, and time spent in physical contact with his partner. Additionally, we tested the ejaculate adjustment hypothesis for prolonged copulation and found no support. Prolonged copulation does not facilitate production of an ejaculate with greater estimated volume, even after controlling statistically for time spent in physical contact with a partner. This research is the first to use content analysis to document that pre-ejaculatory copulatory behavior predicts estimated ejaculate volume and also is the first to document a relationship between the time spent performing cunnilingus and ejaculate quality.