According to Dr. Larousse, the female orgasm “Climax and duration of sexual arousal characterized by intense physical sensations”.
But why do women have orgasms? Unlike men, whose pleasure is associated with ejaculation, for women, reaching the seventh heaven is not at all necessary for reproduction. There is also nothing to indicate that this phenomenon was chosen by evolution to stimulate sexual intercourse and, in particular, its frequency, since only half of the women claim that they regularly achieve this with a man. Therefore, experts have been tearing their hair out for centuries (see. S&V Special Edition No. 258 p. 84) to understand why nature has endowed women with this precious power.
Today, part of the answer may have finally been found. American researchers do suggest, based on scientific arguments, that the main function of the female orgasm in our distant ancestors was the stimulation of ovulation. And that it is precisely on the basis of this primitive orgasm that the female orgasm that many women can enjoy today would gradually be built.
Orgasm is born to stimulate ovulation
The first clue in this direction was given by Mihaela Pavlichev and Günther Wagner in 2016. The two scientists, who worked respectively at the University of Cincinnati and Yale University (USA), then analyzed the phylogenetic tree (which traces evolutionary relationships between species) of mammals, focusing on both the mode of ovulation of each species and the location of their clitoris, the stimulation of which causes orgasm. .
This work was the first to confirm a hypothesis formulated in the 1970s: spontaneous ovulation, triggered autonomously and cyclically without the need for intercourse, is a late innovation in evolution. Prior to this, in the common ancestor of all mammals, ovulation was induced by copulation. ” The distribution of ovulatory mechanisms in modern mammals does suggest that copulation-induced ovulation represents the original model.”confirms Pierre-Henri Guyon, professor at the National Museum of Natural History.
But above all, their work made it possible to discover that this transition from induced ovulation to spontaneous ovulation coincided with the migration of the clitoris: “ In species whose ovulation is induced by copulation, the clitoris is located within the copulatory canal so it can be more easily stimulated during copulation; whereas in species that ovulate spontaneously, such as primates, the clitoris has migrated outside the vagina.”goes back to Michaela Pavlichev (see phylogenetic tree opposite).
Therefore, the researchers suggest that everything could happen in two ways. Or some females in the course of evolution began to ovulate cyclically, and then the stimulation of the clitoris became random. Either the clitoris migrated out of the vagina first, so it was harder to stimulate during intercourse, forcing ovulation to become independent.
Whatever the scenario, the clitoris appears to play a central role in inducing ovulation in our ancestors. This prompted Michaela Pavlicheva and Günter Wagner to formulate the hypothesis that it was the form of orgasm that was responsible for triggering ovulation in our ancestors.
GENERAL MECHANISMS HAVE BEEN IDENTIFIED
A theory in support of which two researchers recently provided an experimental argument through the mating of rabbits under Prozac. The choice of females is easy to understand: in addition to being true to their reputation as zealous copulators, their ovulation is induced by intercourse. Prozac, meanwhile, is an antidepressant that causes up to 70% of women who take it to have difficulty achieving orgasm (some even completely lose the ability to experience pleasure).
Thus, the reasoning of the researchers was as follows: if Prozac reduces the ability of rabbits to ovulate after copulation, as it reduces the ability to achieve orgasm in women, this would mean that there are common mechanisms between the stimulation of ovulation in rabbits and females. orgasm. This would strengthen the hypothesis that our orgasm takes its evolutionary roots from the orgasmic reflex that originally served to trigger ovulation.
Bank! After Michaela Pavlichev and colleagues gave large amounts of Prozac daily to twelve female rabbits for two weeks and then allowed a rabbit named Frank to do his job as a male, Michaela Pavlichev and her colleagues found that Prozac was associated with 30 -percentage reduction in the number of ovulations.
To make sure this result was indeed due to Prozac’s effects on the brain and not on the ovaries, the researchers ran a second experiment identical to the first, except for one detail: this time the Frank rabbit was replaced with a rabbit. the introduction of a hormone that stimulates ovulation. This time, there was no significant difference between the females treated with Prozac and the control group. ” This is evidence that at least most of the action of Prozac does not pass through the ovaries, but through the central nervous system.remove the authors.
Probably the hypothalamic-pituitary complex. The latter is indeed responsible in women for the production of luteinizing hormone (LH), which stimulates ovulation in each menstrual cycle. And it is also responsible for the production of oxytocin and prolactin during orgasm (causing, in particular, uterine muscle spasms and promoting sexual satisfaction).
Based on these results of phylogenetic and experimental analysis, it now appears that ovulation induction in our very distant ancestors took place both through the clitoris and through the brain circuits involved in female orgasm. In short, a kind orgasmic reflex »according to Michaela Pavlichev.
This primitive form of orgasm, systematically induced by copulation and not necessarily associated with pleasure (see box), then evolved heavily to become the modern female orgasm. He lost his ovulatory function for the first time, and one of the hypotheses that can explain this separation of ovulation and copulation is that this would avoid ovulation during pregnancy, which is detrimental to the fetus. ” Long before the advent of pills, we experienced a separation between sexual activity and reproduction.laughs Michaela Pavlichev. In parallel with this separation, and as the clitoris moves away from the vagina (until it is more than 2 cm from the vagina in Homo sapiens !), orgasm during mating became less systematic. But it has also taken on all sorts of new attributes—and perhaps pleasure in particular—as our brains have become more complex (see infographic).
Humans are not the only species to enjoy
While no research has yet been done on rabbits to determine whether orgasm is synonymous with pleasure for them, some clues suggest that the seventh heaven is not reserved for our species. Experiments with rats show, for example, that their copulation experience makes them crave more almond-scented males! As for the great apes, in particular bonobos and chimpanzees, three-quarters of their sexual activities have no reproductive purpose, approaching much more erotic games. Even more amazing: dolphins, male or female, also have sex, alone or in pairs, for pleasure. Arguments of this type suggest that pigs, cats, dogs, bears…whether males or females can also have pleasure.
Of course, much more work will be needed to confirm this theory. ” At the moment, we cannot be sure that the same mechanisms operate between the female orgasm and ovulation induction in rabbits. To do this, it was necessary to study the hormonal basis of these two systems., for example, reacts Julie Bakker, director of the Neuroendocrinology Laboratory at the University of Liege. Elizabeth Lloyd, a philosopher and historian of science at Indiana University and a specialist in female orgasm research, laments the lack of analysis of the nerve and muscle responses, the only ones that can paint a possible picture. parallel between spasm releasing eggs from the ovary and spasmodic contractions of the vaginal walls during orgasm .
Facts and figures
In France about 50% women regularly report difficulty achieving orgasm during intercourse, while 80% to achieve it easily with the help of masturbation. 5 to 15% of women never have an orgasm.
Main scientific publications:
Social Affective Neurosciences and Psychology2016
Molecular and evolutionary evolution of JEB-Z2016