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

in human females is usually achieved through direct or indirect stimulation of the clitoris – the only biological structure in the known universe whose sole function is the creation of pleasure. The anatomical structure of the clitoris, as distinct from its much more obvious pleasurable effects, was discovered in the mid-sixteenth century by an Italian professor of anatomy called Matteo Realdo Colombo. His discovery led to him being accused of heresy, blasphemy and Satanism, among other things. A century later, in the more liberated environment of Restoration England, one Jane Sharp felt free to write in her 1671 publication The Midwives Book that the clitoris ‘will stand and fall as the yard [penis] doth and makes women lustful and take delight in copulation’.

      The clitoris, for all its awesome pleasure-giving powers, is only part of the story, however. In many women, mechanical stimulation of the vagina or cervix can generate orgasms in the absence of direct clitoral stimulation. This common experience has been confirmed under laboratory conditions in several studies. Many sexologists believe that women are equipped with other anatomical structures that are capable of generating orgasms in their own right. Perhaps the best known of these is the G spot.

      According to one version of history, humanity discovered the G spot in 1950. In that year a German gynaecologist called Ernst Gräfenberg published an academic paper in a medical journal, in which he described a ‘distinct erotogenic zone’ on the anterior (front) wall of the vagina. When stimulated, this zone could produce a distinctive type of orgasm. In fact, descriptions of a G-spot-like entity date back much further than the 1950s. References to an erotically sensitive area on the front wall of the vagina can be found in Indian texts dating from the eleventh, thirteenth and sixteenth centuries. These texts also describe how stimulating this zone causes some women to ejaculate a clear liquid. An explicit account of female ejaculation can be found in the work of a seventh-century Indian poet.

      Gräfenberg’s research was not of the highest quality; his findings were based on a small sample of women, only some of whom displayed signs of erotic sensitivity in this area. Nonetheless, his observation has been backed up by more solid research. In the early 1980s, sex researchers Beverly Whipple and John D. Perry reported that mechanical stimulation of deep-lying tissue in the front wall of the vagina could induce orgasm. They named this erogenous zone the G spot in honour of Gräfenberg. Their eponymous book became a best-seller, the spot itself became an accepted fact and the rest, as they say, is history. Few writers of sex manuals now doubt the existence of the G spot and an industry has grown around its erotic potential, selling instruction manuals, DVDs and specially shaped G spot vibrators to pleasure-seekers around the world. And yet, the G spot is still not mentioned in most medical textbooks and some scientists are openly sceptical about whether it actually exists. One academic who reviewed the published research likened the G spot to UFOs: much searched for and much discussed, but unverified by objective means. The truth is a little more complex, although still broadly good news.

      Evidence from numerous scientific studies leaves little doubt that the front wall of the vagina is erotically sensitive to some degree, and that a majority of women can achieve orgasm with sufficient stimulation of this area, whether manually or during penetrative sex. This was shown, for example, in a laboratory study in which women had the front and back walls of their vagina stimulated. All the women reported that certain areas of their vagina were more erotically sensitive than others, and most of them were able to reach orgasm by stimulating these sensitive zones. Although most women normally achieve orgasm through clitoral stimulation, three out of four women in one study said that vaginal stimulation could also produce orgasm. Most reported that the front wall of their vagina was more sensitive to erotic stimulation than the rear wall. Several other studies reached similar conclusions. That said, there is little solid evidence for the existence of a discrete anatomical structure or erogenous hotspot that corresponds to the ‘G spot’ as it is sometimes portrayed in the popular media.

      The fact that the lower front wall of the vagina is to some extent erotically sensitive is unsurprising. Our primate ancestors would presumably have had sex in the rear-entry (‘doggie’) position, which naturally tends to stimulate this part of the vagina. Another possible explanation for at least some ‘G spot orgasms’ is that they are, in fact, indirect clitoral orgasms. Most vaginal orgasms involve at least some indirect stimulation of the clitoris. Rubbing the lower part of the vaginal front wall can have the effect of moving the clitoral hood back and forth across the clitoris, as though the clitoris itself were being massaged. Stimulating the front wall of the vagina can therefore be pleasant and produce orgasms, whether or not that part of the vagina is an erogenous hotspot in its own right. Either way, I see no problem in continuing to call this friendly region the G spot, even if it is neither a spot nor an anatomically distinct organ.

      What of the related belief that ‘G spot orgasms’ can bring about female ejaculation? Again, 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