https://www.eurekalert.org/pub_releases/...092519.php
https://www.cbc.ca/news/technology/femal...-1.5250834
EXCERPTS: 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.
[...] Some years ago, Mihaela Pavlicev, then a researcher at the Boston Children's Hospital, was cataloguing information about the ovarian cycle in different mammals when she stumbled on a pattern — in animals where ovulation is induced by mating, the hormones involved are the same ones released during the human orgasm. Further research showed that animals where ovulation is induced by mating had a different anatomy — their clitoris was inside the "copulatory canal" as opposed to outside, in the case of humans.
And the genetic relationships between the animals were consistent with the idea that both kinds of mammals shared a common evolutionary ancestor whose ovulation was triggered by mating. Pavlicev hypothesized that what humans experience as female orgasm originally evolved to trigger ovulation, and it's a "leftover" trait that no longer has the same purpose. "It's a good suggestion, a good hypothesis with a lot of support, but we really wanted to test it somehow," said Pavlicev, now a professor at the University of Vienna.
[...] 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.
https://www.cbc.ca/news/technology/femal...-1.5250834
EXCERPTS: 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.
[...] Some years ago, Mihaela Pavlicev, then a researcher at the Boston Children's Hospital, was cataloguing information about the ovarian cycle in different mammals when she stumbled on a pattern — in animals where ovulation is induced by mating, the hormones involved are the same ones released during the human orgasm. Further research showed that animals where ovulation is induced by mating had a different anatomy — their clitoris was inside the "copulatory canal" as opposed to outside, in the case of humans.
And the genetic relationships between the animals were consistent with the idea that both kinds of mammals shared a common evolutionary ancestor whose ovulation was triggered by mating. Pavlicev hypothesized that what humans experience as female orgasm originally evolved to trigger ovulation, and it's a "leftover" trait that no longer has the same purpose. "It's a good suggestion, a good hypothesis with a lot of support, but we really wanted to test it somehow," said Pavlicev, now a professor at the University of Vienna.
[...] 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.