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Try out PMC Labs and tell us what you think. Learn More. Human female orgasm is a vexed question in the field while there is credible evidence of cryptic female choice that has many hallmarks of orgasm in other species. Our initial goal was to produce a proof of concept for allowing females to study an aspect of infertility in a home setting, specifically by aligning the study of human infertility and increased fertility with the study of other mammalian fertility.
In the latter case - the realm of oxytocin-mediated sperm retention mechanisms seems to be at work in terms of ultimate function differential sperm retention while the proximate function rapid transport or cervical tenting remains unresolved. A repeated measures de using an easily taught technique in a natural setting was used. The sperm flowback simulated was measured using a technique that can be used in a home setting. This indicates a medium to small effect size. This method could allow females to test an aspect of sexual response that has been linked to lowered fertility in a home setting with minimal training.
It needs to be replicated with a larger sample size. Debate concerning the nature and function of human female orgasm has been intense — although frequently producing far more heat than light. In this latter case, the most promising candidate would be the strong selection on the sensitivity of the male homologue of the clitoris — namely the penis Gould, ; Lloyd, ; Symons, whereby female orgasms exist only because male ones do — having no function of their own.
A by-product typically emphasizes the allegedly poor location of centers of female sexual sensitivity for coitally produced orgasm to occur. Candidates for an adaptive function for female orgasm have broadly fallen into two types. There are those who argue that female orgasms help to cement pair bonds, in a species requiring bi-parental care Eschler, , ; Morris, ; Rancour-Laferriere, Sperm selection is a feature of female choice mechanisms.
In contrast to Bateman's principle, there is a large body of evidence across taxa that female fitness increases as sexual partners increase, just in case that there is some mechanism for picking the best sperm among sexual partners Simmons, Note that there is no requirement for these to be concurrent sexual partners. It need not be the case that sperm from multiple partners is simultaneously present in the female — just that there operates some sort of differential sorting mechanism that privileges some matings over others. It could be argued that these two adaptive s are to some extent orthogonal to one another, generating a somewhat different set of testable predictions.
They are part of a female choice mechanism that responds differentially to different partners. However, the physiological nature of such a mechanism is still in dispute — with anatomical authorities in disagreement about whether it is the proximate mechanism of cervical tenting Levin, or rapid transport Zervomanolakis et al.
The clitoris is crucial to understanding the nature of female orgasm. Levin, personal communication, July Surprisingly, even women who have had the clitoral glans entirely, even brutally, excised still report the experience of coital orgasm Lightfoot-Klein, In addition, it has been found that there are a variety of neural pathways in the vaginal area, independent of the clitoris, that are important in female sexual response — even to the point of triggering orgasm in cases of complete spinal transection Komisaruk et al.
Recently, these multifarious and separate neural pathways of genital sensitivity have been mapped onto the sensory cortex Komisaruk et al. An underlying assumption of much research into female orgasm has been that all orgasms are the same, and in this respect, the work of Masters and Johnson , has been foundational.
However, their pioneering research is not the last word on the topic. In particular, there are good reasons to believe that their methodology of studying unpartnered masturbation in a laboratory setting may not have quite captured all of the salient features of the human sexual experience.
Specifically, humans typically perform sex in private consortships where they can focus on reproductively salient features of their prospective partners. Although Masters and Johnson , found no evidence of sperm insuck in their pioneering research, their methodology lacked key ingredients of ecological validity. First, the six experiments on which their null sperm insuck findings were based involved no actual intercourse at all — they involved unpartnered masturbation of the clitoral glans while a rigid transparent insertable was inside the vagina.
For certain key experiments, Masters and Johnson , used inserted metal specula that covered all of these sensitive areas. Thus, it is likely that their methodologies effectively sidelined key features of female orgasms, and therefore, their conclusion that female orgasm was a unitary phenomenon — always the same no matter how achieved or with whom — may have reflected nothing more than an experimental artifact.
Female orgasms can vary in sensation, location, and important features of phenomenology. Taken together, it is very likely that in studies, including those of Masters and Johnston, the full length of the clitoris, most of which is internal, had not been aroused. Some orgasms are reported as being accompanied by deep internal sensations that could be the corollary of orgasmic function itself. It has been reported that the Fox et al. Specifically, some researchers have said that the Fox et al. However, close inspection of the original paper shows that such criticisms rest on a misreading of the original graphs — which are admittedly laid out in a somewhat confusing manner.
Specifically, critics have read them as saying the opposite of what they actually showed. Usually graphs have a time line along the x -axis that runs with time flowing from left time 0 to right. For one reason or another, the Fox et al.
Critics who thought that the graphs showed the opposite of what the Fox et al. of these studies, therefore, do suggest that pressure changes occur in the predicted direction following coitally generated orgasm. However, it must be admitted that these pioneering studies did not measure fluid movement per se — only the potential for such movement driven by uterine pressure changes.
Wildt et al. Oxytocin is a known correlate of female orgasm Blaicher et al. For example, following administration of oxytocin, there was insuck of suitable material into the fallopian tube ipsilateral to the dominant ovary. Furthermore, pregnancy rates have been observed to be higher in those women in whom such transport could be demonstrated Zervomanolakis et al. There has been some criticism Levin, that the amounts of oxytocin in the bloodstream 3IU used in such studies are unrealistically high. However, the peripheral amounts in the bloodstream are much less important than those found at the site of action — that is the uterus L.
Wildt, personal communication, August Baker and Bellis a , b assumed the insuck mechanism in their promising, and much cited, research into the putative functionality of female orgasm. Some Lloyd, have found the Baker and Bellis b statistical analysis of these data to be confusing.
For example, Lloyd , p. Sperm transport by some form of intra-uterine action is a phenomenon that has been found across mammalian taxa — as one might expect of an adaptation West-Eberhard, If such transport responds differentially to salient features of the partner — in other words becomes sperm selection — then this would help complete the picture of a function for female orgasm.
To clarify, it is hypothesized that at least some of the phenomenological features of female orgasm, such as feelings of deep uterine peristalsis, may be exactly as they appear to be. In the farming industry, the generation of uterine peristalsis — via techniques that more accurately simulate insemination by a dominant male — is commonplace to increase sperm uptake through artificial insemination Knox, If humans do not show sperm transport, then they are the exception among mammals.
All of the mammals in which differential sperm transport of which insuck could be a component has been demonstrated show some degree of promiscuity — or, more properly, polyandrous mating. However, some have expressed skepticism that ancestral or modern female humans might have benefitted greatly from polyandrous behaviors Birkhead, For there to be a mechanism to privilege some matings over others — it follows that, over evolutionary time, enough female humans must have been engaging in enough polyandry for such an adaptation to develop.
Across taxa there are patterns of physiological adaptation that are understood in terms of responses to the degree of female polyandry. For example, monandrous gorillas have small testicles, polyandrous chimpanzees have large ones to produce the necessary amounts of material to compete effectively inside the females Dixon, Human testicle size falls in between the extremes of monandry and polyandry Short, There exist other similar male physiological adaptations hypothesized to be ed for by female polyandry — such as proportionate sperm increase in multi-male, single-female, sexual encounters Pound, and, perhaps, a penis adapted to excavate the sperm of prior partners Gallup et al.
It has also been argued that there are specific male psychological adaptations to the possibility of sperm competition, such as violent male sexual jealousy Buss, The lower figure is reported by said scholars as probably more accurate, but may well be high enough to drive adaptations. Zubrow showed that just such a mortality difference in two overlapping populations would extinguish one of them within 30 generations — less than a millennium. Some have even argued that female orgasmic response evolved in an environment of frequent multi-partner sexual encounters Hrdy, In any case, it is generally becoming accepted that models of sexuality that imply females to be coy and passive in the face of aggressive male sexual ardor are seriously at variance with the facts — whether in humans or other animals Gowaty, ; Hrdy, , , ; Judson, ; Zuk, Put bluntly, Bateman's principle — that females do not benefit from multiple matings — is wrong.
Female choice mechanisms are key drivers in primate evolution Cronin, , and facultative polyandry is a suite of mechanisms that can instantiate such choice. In an effort to move the debate forward, we decided to investigate the phenomenon of sperm retention — possibly through orgasmic insuck — directly in human females. To our knowledge, this has not yet been measured directly in humans. Measurement of backflow provides a way to compare the amount of sperm taken up following orgasm, even of different kinds of female orgasm, perhaps produced in different ways.
This exploratory study involved six females, mean age All were white, European, or American and had been educated to at least undergraduate degree level. None were using oral contraceptives. All were sexually active with a current male partner. Five of the six reported that they experienced regular periods.Beautiful ladies looking orgasm Great Falls
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