Sex, Drugs and Chocolate: The Science of Pleasure. Paul Martin

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СКАЧАТЬ the reality is a little more muted than the popular image of ‘gushers’ would suggest. Many, if not most, women emit some fluid from their genitalia at orgasm or when they are at a peak of sexual arousal. One study found that women who were aware of their G spot were twice as likely to be ‘ejaculators’. In most cases, however, the amount of fluid emitted is too small to be easily noticeable.⁶ Moreover, its release does not depend on having a ‘G spot orgasm’. Experiments have shown that when the front wall of the vagina is stimulated, some women have an orgasm but do not ejaculate, some women ejaculate but do not have an orgasm, and some do neither.

      Since Ernst Gräfenberg first unveiled what became known as the G spot more than half a century ago, the quest for new erogenous zones has continued. More recent erotic explorers have laid claim to discovering the A spot, the U spot and the X spot. What and where are these alleged pleasure troves? In reverse alphabetical order, the X spot is an erotically sensitive spot on the cervix. According to the American sexologist who ‘discovered’ it, the X spot is even better than the G spot and easier to find. The U spot is a small sensitive area just above, and on either side of, the opening to the urethra. Finally, the A spot, or anterior fornix erogenous zone, is a sensitive patch at the inner end of the vagina, just above the cervix. Stimulation of the A spot is said to produce violent orgasmic contractions. In addition to the G, A, U and X spots there is, of course, the clitoris – that fabulously sensitive organ whose visible tip contains many thousands of nerve endings, all of them dedicated to the production of pleasure. Meanwhile, not one single new flag of discovery has been planted on the male genitalia. The general assumption appears to be that the male organ, like the male psyche, is a simple thing, altogether lacking in mystery.

      All of these glaring gender disparities in sexual pleasure call to mind the ancient Greek myth of Tiresias, a priest who had been transformed from male into female then back to a man again. Tiresias became embroiled in an argument between the goddess Hera and her husband Zeus about whether men or women derived the most pleasure from sex. As someone who had been both a man and a woman, Tiresias would have known. His considered opinion was that, on a ten-point scale, men enjoy only one part in ten whereas women enjoy all ten in full.

      As well as possessing a larger collection of erogenous hotspots than the average man, the average woman’s potential for orgasmic pleasure is much greater. Not all women fulfil this potential, however. Individual women differ considerably in the frequency with which they have orgasms. Research has shown that part of this individual variation is linked to genetic differences.

      Scientists at St Thomas’ Hospital in London investigated the influence of genes on orgasmic function by gathering data from pairs of identical and non-identical twins.⁷ A large sample of adult female twins provided information about their sexual histories. Virtually all the women had been sexually active, with an average of four or five sexual partners each. The data revealed a striking variability in the ease with which they had orgasms. One in three women said they reached orgasm during sexual intercourse either infrequently (less than a quarter of the time) or never, and one in five reported the same for masturbation. Overall, one in seven women never had an orgasm, not even when masturbating. At the other end of the scale, one in seven women always had an orgasm during intercourse.

      By comparing data from identical and non-identical twins, the scientists were able to estimate that 34 per cent of the individual variation in reaching orgasm from intercourse was genetically inherited, while for orgasm from masturbation the heritability was 45 per cent. In other words, somewhere between 34 and 45 per cent of the individual differences between women in their ability to have orgasms could be explained by genetic differences. Other twin studies have produced similar findings.

      Genetic factors could affect a woman’s orgasmic potential in many different ways, both direct and indirect, ranging from subtle influences on anatomy to variations in how the brain responds to sensory stimuli or perceives pleasure. Genetic predispositions aside, most sexologists would argue that an overwhelming majority of women are ultimately capable of reliably achieving orgasm, provided they have suitable circumstances, the right attitudes, a little knowledge and enough time.

      Research has highlighted the role of one particular gene in human sexuality. The gene in question, which is called DRD4, affects how the brain responds to the neurotransmitter substance dopamine.⁸ As we shall see in chapter 6, dopamine plays a central role in the perception of pleasure and desire. Most people carry one of two different variants of the DRD4 gene: about 70 per cent of us have one version and about 20 per cent have the other. Individuals with the less common version of the gene score higher on self-reported measures of sexual desire, sexual arousal and sexual function than those who have the more common variant.

      As you may have noticed, the pleasure of orgasm does not stop abruptly when the exquisite peaks of the orgasm itself have passed. It lingers on in a different and more subdued form. The pleasant feeling of satiated relaxation that follows a good orgasm stems from the sudden release into the bloodstream of the hormone prolactin. This post-orgasmic surge in prolactin, which occurs in men and women, has the effect of damping down sexual arousal. (Scientists have yet to investigate whether it also stimulates the desire for a cigarette.) However, not all orgasms are equal in this regard. Research has discovered that the prolactin surge is four times bigger following orgasms that result from sexual intercourse than following orgasms achieved through masturbation. This helps to explain why having good sex with a partner tends to produce a more satisfying wave of post-orgasmic relaxation than having sex with oneself.

      What are orgasms for? The delightful capacity to experience orgasms is built into our biological makeup and should therefore have some form of biological function. But how might orgasms have helped our evolutionary ancestors to survive and reproduce? The answer is not quite as obvious as it might seem. The male orgasm coincides with ejaculation, which is essential for making babies. But ejaculating semen and having an orgasm are two different things. There is no inherent reason why males should not be built to ejaculate without experiencing the accompanying spasms of orgasmic pleasure. Indeed, some men with spinal cord injuries are capable of ejaculating without being able to feel the sensations of orgasm.

      In females, the connection between orgasm and reproduction is even less obvious. A fertile woman is biologically capable of conceiving without ever having an orgasm. And, as we saw, a substantial minority of women rarely or never have orgasms during sex. Furthermore, this difficulty in achieving orgasm has a strong genetic component, implying that the female orgasm is unlikely to have been crucial for human survival and reproduction. This line of thinking led the biologist Elisabeth Lloyd to conclude that the female orgasm may have no biological function at all, but may instead be an evolutionary by-product of the male capacity for orgasm. Lloyd has likened the female orgasm to the male nipple, which serves no biological purpose but exists because it is constructed at an early stage in embryonic development. Similarly, Lloyd argues, women are equipped with a clitoris, and hence the capacity for orgasm, as an evolutionary by-product of constructing the male penis. She believes this is why most women only have an orgasm if their clitoris is stimulated and why some women find it hard to have orgasms at all.

      The female orgasm may not be essential for conception, but that does not mean it is entirely irrelevant. Having an orgasm could influence a woman’s chances of conceiving, possibly as a result of the muscular contractions helping to draw semen into the uterus. This theory is supported by research evidence that women who have a strong desire to become pregnant are more likely to have an orgasm after, rather than before, their partner ejaculates, other things being equal. Somewhat more controversial evidence indicates that women who have an orgasm after their partner ejaculates retain more of his sperm in their vagina and are therefore more likely to conceive. Having an orgasm at the right time could make a difference. Having an orgasm with the right partner at the right time could make even more of a difference. We are therefore drawn back to the simplest and most compelling explanation, which is that the СКАЧАТЬ