A study suggests a possible evolutionary origin of female orgasm. Female orgasm is a complex neuroendocrine process that is unlikely to have evolved by chance but is unnecessary for successful reproduction. Many hypotheses for the evolutionary origin of female orgasm have been proposed, but few have empirical support. Günter P. Wagner, Mihaela Pavlicev, and colleagues conducted an experimental test of one such hypothesis, the ovulatory homolog model (OHM), which proposes that the physiological mechanisms underlying female orgasm originally developed for inducing ovulation during copulation. Such copulation-induced ovulation (CIO) occurs in various mammals, such as rabbits, cats, ferrets, and camels, but not in humans or great apes. To test the OHM, the authors treated female rabbits daily with fluoxetine, a selective serotonin reuptake inhibitor that inhibits orgasm, for 2 weeks before copulation. One day after copulation, the authors measured the number of ovulations, which was 30% lower in fluoxetine-treated rabbits than in control rabbits. In a second experiment, the authors induced ovulation by injection of human chorionic gonadotropin (hCG) following fluoxetine treatment. Fluoxetine treatment did not significantly affect hCG-induced ovulation. According to the authors, the results support the hypothesis that CIO in rabbits is homologous to female orgasm in humans, suggesting that these processes share a common evolutionary origin.
Article #19-10295: "An experimental test of the ovulatory homolog model of female orgasm," by Mihaela Pavlicev et al.
MEDIA CONTACT: Günter P. Wagner, Yale University, New Haven, CT; tel: 203-737-3091, 203-710-2235; e-mail: gunter.wagner@yale.edu ; Mihaela Pavlicev, University of Cincinnati, OH; tel: +386-31-474-991; e-mail: mihaela.pavlicev@univie.ac.at
###
Proceedings of the National Academy of Sciences