Why on earth would anyone perform oral sex? Particularly on a woman?!? While these questions seem silly to some of us (I mean, it’s obviously because the people involved find it totally hot, right?), they aren’t to evolutionary biologists. This is because many of our behaviors and choices that seem completely voluntary are actually hard-wired, and have been naturally selected over millennia because they help us have more babies. However, it isn’t necessarily obvious which behaviors have been selected for until one starts testing different hypotheses. Here, scientists are testing the idea that performing oral sex on women is evolutionarily beneficial because it helps the sperm get and remain inside the uterus. They sampled heterosexual men from the United States and Germany, the majority of whom lived with their partners, and asked them details about their sex lives and relationships.
Is cunnilingus-assisted orgasm a male sperm-retention strategy?
“We secured data from 243 men in committed, sexual, heterosexual relationships to test the sperm retention hypothesis of oral sex. We predicted that, among men who perform cunnilingus on their partner, those at greater risk of sperm competition are more likely to perform cunnilingus until their partner achieves orgasm (Prediction 1), and that, among men who ejaculate during penile-vaginal intercourse and whose partner experiences a cunnilingus-assisted orgasm, ejaculation will occur during the brief period in which female orgasm might function to retain sperm (Prediction 2). The results support Prediction 1 but not Prediction 2. We discuss limitations of the current research and discuss how these results may be more consistent with alternative hypotheses regarding female orgasm and oral sex.”
Bonus excerpts from the full text:
“The results of the current study are not consistent with the hypothesis that cunnilingus is designed to promote sperm retention. Men at greater recurrent risk of sperm competition are more likely to perform cunnilingus on their partner until she achieves orgasm; however, ejaculation usually does not occur in the brief time period during which
orgasm might function to retain sperm.
Female orgasm may be designed to increase relationship satisfaction (Pair-Bond Hypothesis), to encourage subsequent copulations (Promoting Future Copulations Hypothesis), to retain preferentially the sperm of men with higher genetic quality (Sire Choice Hypothesis), to promote fertilization (for a critical review, see Levin, 2011), or female orgasm may be a non-functional byproduct of male orgasm (reviewed in Puts, Dawood, and Welling, 2012). The results of the current research provide support for the Pair-Bond Hypothesis and the Promotion of Future Copulations Hypothesis. The Pair-Bond Hypothesis states that female orgasm functions to strengthen the emotional bond between partners, and the Promoting Future Copulations Hypothesis states that female orgasm functions to reward sexual behaviors, thereby promoting future sexual encounters with a particular man. These two hypotheses are consistent with the broader hypothesis that men promote their partner’s orgasm to minimize the risk of her infidelity because women who experience stronger feelings of intimacy and who are more satisfied with their partner are less likely to commit infidelity (Buss and Shackelford, 1997). However, one hypothesis alone may not best explain the function of female orgasm (e.g., McKibbin et al., 2010, who documented that men’s risk of sperm competition moderates the association between men’s relationship satisfaction and their interest in their partner’s orgasm). Given the ongoing debate regarding the function of female orgasm (reviewed in Puts et al., 2012), future research should continue to investigate the several proposed functions of female orgasm and, in particular, should attempt to replicate the research of Baker and Bellis (1993b), which relied on a relatively small sample to document that female orgasm may increase sperm retention. ”
Discoblog: NCBI ROFL: [Insert oral sex joke here].
Discoblog: NCBI ROFL: Does semen have antidepressant properties?
Discoblog: NCBI ROFL: Cunnilingus increases duration of copulation in the Indian flying fox.