Introduction to How Orgasms Work
When gynecologist William H. Masters received official approval for his research project from Washington University in 1954, it was one of academia's closest-kept secrets at the time [source: Kolodny]. Masters even recruited a group of influential community leaders to help ward off any negative public reaction should his scholarly pursuits leak out. Sure, Alfred Kinsey had published "Sexual Behavior in the Human Female" the previous year, but the more hands-on tack Masters intended to take would've certainly ruffled moralistic feathers in that "Leave It to Beaver" era.
Over the next 12 years, Masters and his research assistant Virginia Johnson would analyze the sexual arousal patterns among 694 men and women. But instead of largely relying on self-reports of past experiences, Masters and Johnson were interested in the exact, real-time physiology of sex, which meant they needed to actually witness people in the throes of ecstasy. The duo filmed couples engaging in sexual intercourse, as well as individual participants masturbating, and simultaneously monitored the research subjects' blood flow and electrical activity in the brain [source: Severo]. To clarify what happens inside the mystifying vagina, Masters and Johnson even built a phallic device equipped with a tiny camera.
Compiling more than a decade's-worth of clinical research, Masters and Johnson outlined how men and women achieve sexual orgasms in their 1966 best-seller "Human Sexual Response." The revolutionary research helped pave the way for sexology as an accepted, credible discipline and is still a cornerstone of our collective knowledge about human sexual function.
But more than 50 years after that seminal publication, there's still a lot that isn't known about sex, and about orgasm specifically. In 2001, for instance, a pair of researchers from McGill University in Canada identified 26 different clinical descriptions for that coveted climax [source: Mah and Binik]. And though the crux of what an orgasm is -- a climactic, pleasurable sexual sensation -- is known, sex comprises only a sliver of the science behind the Big O.
Anatomy of an Orgasm
In their 1966 book "Human Sexual Response," Masters and Johnson divided the sexual response cycle into four phases: excitement, plateau, orgasm and resolution [source: Bolin and Whelehan]. Boiling down one of humans' most subjective physiological experiences to a discrete flowchart attracted criticism in subsequent decades, but the phases still offer an instructive framework for describing how orgasms generally happen inside the body.
Although differences between male and female orgasms abound, both share similar respiratory, circulatory and muscular hallmarks. Sexual excitement in the brain stimulates increased blood flow to the genitals, engorging the penis in men and enlarging and lubricating the clitoris and labia in women. Pulses quicken, and the elevated heartbeats are heard in more intensive inhalations. Central nervous systems fully engage, directing messages of escalating enjoyment along the pelvic, pudendal and hypogastric nerve endings in the genital regions back to the brain's reward system and vice versa during plateau [source: Nuzzo]. This full-body workout then crests with a series of pelvic, cervical and anal muscle contractions in 0.8-second increments that correspond with orgasmic sensations and ejaculation [source: Elliott]. Deep relaxation and resolution typically follow as muscles relax and heart rates slow to a resting pace.
You can easily visualize the clinical description of an orgasm as an "explosive cerebrally encoded neuromuscular response" by watching the brain conduct and react to orgasms via functional MRI (fMRI) screening [source: Komisaruk, Beyer and Whipple]. In one experiment involving participants stimulating themselves to climax, the experience energized more than 30 discrete places in the brain [source: Sukel]. For instance, the nucleus accumbens and ventral tegmental area work in tandem to open the floodgates of pleasure-prompting dopamine, while the pituitary gland pumps out oxytocin, a hormone that mediates bonding [source: Freeman].
As men and women close in on the grand finale, their orgasmic brain activity appears strikingly similar on PET scans, save a couple telling distinctions [source: Georgiadis]. In female brains, orgasms flip off the lateral orbitofrontal cortex, a mechanism located behind the left eye that promotes self-evaluation [source: Portner]. In male brains, activity in the amygdala slows during coitus, dampening aggressive instincts [source: Portner]. But when sexologists move away from mechanics and compare frequency, subjective sensation and environmental components that contribute to orgasms, they quickly encounter distinct biological divides.
Orgasms: His vs. Hers
Speaking to The Daily Beast in 2009, Stanford University sociologist Paula England declared the uneven ratio of male to female orgasms "as serious as" the $6-per-hour gender wage gap in the U.S. [source: Seligson]. Virtually any way researchers slice it, men edge out women in terms of how often they're experiencing the Big O. During one-night stands in particular, female participants are extremely unlikely to orgasm. According to a Stanford University survey of almost 13,000 heterosexual college students, 44 percent of guys were likely to finish during those fleeting encounters, compared to 19 percent of the female co-eds [source: Young and England].
Even in steady relationships, straight men may overestimate female partners' orgasm frequency. The 2010 National Survey of Sexual Health and Behavior conducted by Indiana University found that 85 percent of men say their partners climaxed during their last sexual encounter, whereas only 65 percent of women concur. Perhaps unsurprisingly then, 64 percent of women reported being "very satisfied" with how often they achieve orgasm [source: Indiana University].
Granted, the orgasm gap closes when focusing in on different categories of sex. For starters, when discussing intercourse with dedicated sexual partners, the regularity of female orgasm surges to 79 percent [source: Pappas]. Integrating clitoral stimulation, as opposed to exclusively vaginal penetration, also greatly improves the chances of climaxing to roughly 90 percent [source: Kinsey Institute]. That may underlie why Alfred Kinsey's early surveys found that nearly 68 percent of lesbian partners report climaxing 90 to 100 percent of the time, versus 40 percent of heterosexual married women [source: Goldstein and Davis]. In addition, multiple reports have shown that women tend to rate clitoral orgasms as more satiating throughout the entire body, compared to vaginally-stimulated orgasms [source: Mah and Binik].
On average, men's orgasmic latency through vaginal intercourse, or the time it takes from start to finish, is faster than women's by a difference of between 8 and 15 minutes, on average [source: Brown University]. That said, women may well be justly rewarded for their patience with orgasms lasting between 13 to 51 seconds, while men max out at 10 to 30 seconds [source: Bolin and Whelehan]. And unlike the male refractory period following ejaculation that prevents the body from immediately chasing down another orgasm, women's pelvic floor muscle contractions can continue to deliver multiple orgasms. In 1953, Kinsey estimated that 14 percent of the American female population could muster multiple orgasms, whereas a 1991 study published in the Archives of Sexual Behavior found that 42 percent of its female sample self-reported multiorgasmic events [source: Darling, Davidson and Jennings].
At the same time, those ladies-only bonuses complicate one of the most burning -- and contentious -- questions in the evolutionary biology community: Why do women have orgasms to begin with?
The Great Female Orgasm Debate: Adaptive Theory
To evolutionary biologists, the male orgasmic function makes perfect sense. In decidedly unromantic terms, it ensures the survival of the human species by offering a physiological motivation to pursue and inseminate sexual partners. The speed and consistency with which heterosexual men achieve orgasm via vaginal intercourse also supports its classification as a beneficial adaptation [source: Keim].
Not so for the female orgasm. Partly because of the previously discussed gender gap in orgasm frequency and disparities between clitoral and vaginally stimulated climaxes in women, evolutionary biologists have yet to conclusively explain why women also experience the Big O. But that doesn't mean they're lacking in theories, which collectively split into an academic tug-of-war between two major camps: adaptation and byproduct.
Adaptation proponents spin the female orgasm as an evolutionarily favorable trait like the male orgasm. To them, natural selection rooted for the pleasurable physiological response because it enhanced female's reproductive fitness. Orgasms not only sexually satisfy females, bonding them to a partner, but also provide a rubric for evaluating suitable mates by revealing who could excite them toward ecstasy [source: Keim].
Another contribution to the adaptation school of thought is the "sperm up-suck theory," which contends that uterine contractions along with oxytocin release during orgasm suction potent semen upward into the vaginal canal [source: Lloyd]. According to zoologist Robin Baker, who popularized the long-held theory with his 1996 book "Sperm Wars," orgasms lend women a helping hand by innately spotting -- or at least up-sucking -- the most virile men. If the up-suck theory, which was originally tested on female pigs, was true, that would endow female orgasms with a reproductive advantage by increasing a woman's fertility.
But Baker's thesis didn't go unchallenged, and a June 2011 reanalysis of the related scientific literature poked holes in the up-suck strategy for a number of reasons. For instance, Baker's research included only a single subject, and additional studies found no conclusive evidence of orgasm-induced sperm retention in sexually aroused women [source: Levin]. Hence, the great female orgasm debate continues.
Rule of ThumbIn 1924, French author and psychoanalyst Princess Marie Bonaparte published a theory of why she had difficulty achieving orgasms: Her clitoris was too far from her vaginal opening. Bonaparte measured the clitoral-vaginal (C-V) distances of female psychiatric patients and discovered that those with shorter C-Vs, roughly the length of the thumb tip, climaxed more often. Emory University professor Kim Wallen reviewed Bonaparte's data in 2008, and determined that the "rule of thumb" held water, possibly illuminating female orgasm inconsistency [source: Nuzzo].
The Female Orgasm Debate Continues: Byproduct Theory
Supporters of the byproduct theory liken the female orgasm to male nipples [source: Yoder]. As fetuses develop, all are outfitted with the anatomical precursors to nipples, although they only offer a direct reproductive advantage to women for feeding their babies. But since that's such a favorable trait, evolution didn't go to the painstaking trouble of weeding nipples out of the male population. In other words, men have nipples because women do. Likewise, clitoral and penile tissues are borne of the same embryological stuff, developing into one or the other once biological sex traits set in. The hooded glans, packed with 8,000 nerve endings, is just the visible tip of the internal clitoral structure that extends up and around the vagina and engorges during arousal much like the penis [source: Gonzalez]. Therefore, female orgasms could exist because that clitoral anatomy was under no evolutionary pressure to disappear.
A pair of 2011 studies led by Brendan P. Zietsch at Australia's University of Queensland exemplifies why reconciling the two camps -- adaptive and byproduct -- has remained implausible. In one study of orgasmic function among 1,457 sets of female twins, Zietsch and his colleagues found no correlation between female orgasmic function and 19 other evolutionarily significant traits, including impulsiveness, risky sexual behavior and masculinity [source: Zietsch et al]. One point for team byproduct.
Then, Zietsch's team conducted a follow-up study comparing the orgasmic function of opposite-sex twins, since they share identical genetic information, hypothetically putting them on an even orgasmic playing field. According to byproduct theory, the self-reporting should've resulted in twins with matching self-reported rates of orgasms. For same-sex sets in the study, that was the case. But brother-sister pairs had no such luck. Sisters consistently tallied up fewer than their brothers, effectively tipping the hat back toward adaptation [source: Keim].
Chances are, however, the more burning question on lay people's minds regarding women and sex relates not to the orgasmic sensations, but rather their byproduct.
Everything You Wanted to Know About Ejaculation but Were Too Afraid to Ask
Eyebrow-raising sex researcher Alfred Kinsey was as curious about ejaculation as the next fellow. Luckily for him, he had the academic credentials to settle the matter. Recruiting a couple hundred male volunteers to his Indiana University laboratory in the late 1940s, he placed sheets on the floor and asked the men to masturbate, notating how far their seminal fluid traveled. The long-distance winner's semen traversed almost 8 feet [source: Roach].
Propelled by a handful of pelvic contractions, ejaculate moves through the urethra at a swift 28 miles per hour (45 kilometers per hour), on average. It then slows down drastically during its narrow escape, and once inside the vagina, the typical 1 to 2 teaspoons of ejaculate eases to a veritable crawl, clocking in at 0.0011 miles per hour (0.0017 kilometers per hour)[source: Margolis]. And what's contained in that masculine elixir? Sperm, of course, but it's only a minor ingredient. The nutrient-packed fluid primarily originates in the seminal vesicles -- male glands tucked up near the bladder and attached to the vas deferens -- and combines with secretions from the prostate glands and vas deferens collected during sperms' ejaculatory journey [source: Elliott].
As if the female orgasm isn't fraught with enough issues of unpredictability and doubt as to why it even exists, the existence of female ejaculation is often a subject of debate as well. In a 1950 study published in The International Journal of Sexology, gynecologist Ernest Gräfenberg first hypothesized that stimulation of tissue surrounding the female urethra could prompt orgasm accompanied by an ejaculate-like fluid [source: Korda et al]. Although the location of Gräfenberg's namesake G-spot remains contentious, scientific evidence confirms that women can ejaculate -- but few do [source: Moalem].
Alternately known as the female prostate, paraurethral glands, and Skene's glands, this tissue's ducts can release fluid into the urethra, which is then expelled during orgasm [source: Wimpissinger et al]. A 1981 analysis of female ejaculate confirmed that though the liquid comes from the urethra, it didn't match urine's chemical composition [source: Addiego et al]. Rather, female ejaculate is more reminiscent of male ejaculate, compellingly containing prostate-specific antigen and prostate-specific acid phosphatase, two proteins that show up in semen [source: Adams]. Large-scale studies are still needed to determine the prevalence rate of female ejaculation and whether it serves any purpose, aside from adding yet another wrinkle to women's sexual function.
Premature Ejaculation Happens -- A LotAlthough uniform criteria for what constitutes premature ejaculation don't exist, lack of control over orgasmic release certainly affects many adult men. According to a 2007 global survey, 22 percent of men across all age groups struggled with it, and a 2005 survey calculated an even higher prevalence rate of 30 percent [sources: Porst et al and Montorsi].
Faking It
In 1989, Nora Ephron publicized on the big screen what had already been confirmed in a series of studies. In one of the most iconic scenes in contemporary film history, Ephron's leading lady Sally Albright fakes an orgasm for leading man Harry Burns during the lunch rush at Katz's Deli in New York. And Meg Ryan's finicky character in "When Harry Met Sally" wasn't among the statistical minority, either. Since the early 1970s, research has concluded repeatedly that between 53 percent and 65 percent of heterosexual women have pulled a counterfeit climax during vaginal intercourse [source: Muehlenhard].
Temple University psychologist Erin Cooper wanted to better understand women's motivations for faking orgasms. Sure, it's a begrudgingly accepted part of sexual culture -- though only 20 percent of heterosexual men could imagine their partner pulling such a prank -- but what's the use [source: Dingfelder]?
In 2010 interviews conducted with more than 300 female college students, a sliver of the population sample told Cooper that their theatrics actually enhanced the experience and heightened their arousal -- but that was the exception to the fake-it-for-his-sake rule [source: Welsh]. For 67 percent who had done it, altruism was a major driver behind the bedroom kabuki [source: Welsh]. In particular, women feared emasculating male partners by betraying their inability to work the female body into a full-blown frenzy.
But the real bombshell landed in November 2010, with the revelation that a decent proportion of men fake orgasms as well, flying in the face of some sexologists who so closely associated vaginal intercourse with male orgasm, they deemed it a moot point [source: Muehlenhard]. University of Kansas psychology professor Charlene Muehlenhard surveyed about 350 male and female college students about orgasm deception, and 24 percent of the guys copped to it [source: Muehlenhard]. Men employed fake-out tactics similar to those of their female counterparts, such as aping sexual excitement. And in addition to condoms protecting against sexually transmitted diseases, they can also offer men an added bonus of hiding a lack of ejaculatory evidence [source: Sohn]. Unlike women, however, their main motivation for the mimicry was getting intercourse over with [source: Muehlenhard].
This relatively high proportion of the sexually active population that acts out bogus big bangs may also be attributed to the rarely discussed, but not-so-rare issue of orgasmic dysfunction.
Female Brain on a Fake OrgasmA 2005 fMRI study conducted at the University of Groningen in the Netherlands showed activity in female fakers' motor cortex that controls conscious thought [source: Roberts]. During the real thing, that brain region lets go and shuts down.
The Big No
For the record, orgasms aren't explicitly required in order for people to enjoy sex. Consider, for instance, the small group of female Temple University students who said that faking orgasms enhanced their arousal [source: Welsh]. They probably weren't just putting on a happy face for researchers, because as much as orgasms are a symphony of purely physiological responses, people's states of mind play a first-chair role as well [source: Mah and Binik]. Moreover, it's helpful to remember the strong correlation between partner emotional intimacy and sexual satisfaction; healthier relationships predict happier sexual outlooks, regardless of whether partners orgasm each time [source: Kinsey Institute].
Nevertheless, sexual culture has long prized the orgasm as the pinnacle of pleasure, but many women especially have never reached those heights. Indeed, 10 to 15 percent of adult females haven't experienced an orgasm, thus meeting the clinical definition of primary orgasmic dysfunction, also known as anorgasmia. Even more -- 33 to 50 percent -- wish they could climax more often [source: MedlinePlus]. Although female sexual dysfunction is more readily pathologized, women aren't alone in feeling frustrated in the bedroom. Up to 31 percent of men also report sexual problems, such as erectile dysfunction and premature ejaculation [source: WebMD].
Hormonal imbalances, chronic disease and medications, such as antidepressants, certainly sap people's sex drives, but orgasmic dysfunction is highly treatable [source: MedlinePlus]. To alleviate the anxiety associated with sexual contact, therapists may initially recommend patients get to know themselves first [source: Thomas]. By practicing solo masturbation, people suffering from anorgasmia may better understand the specific physical and mental prompting their bodies desire. Also, in relationships, sexual dissatisfaction may be symptomatic of a lack of communication, rather than a lack of physiological potential. For instance, psychologists at the University of Utah compared communication styles among couples that were and weren't dealing with anorgasmia; those struggling in the bedroom were the most uncomfortable discussing sex and enumerating intimate needs to partners [source: Kelly, Strassberg and Turner].
In that light, we shouldn't fret the possibility of not finding an orgasm; that happens to almost everyone at some point. What deserves more attention and relish, in the end perhaps, is the mental and physical duet that ushers us toward that final, toe-curling cymbal clash.
Give Vibrators a ChanceA 2011 survey from Indiana University's Center for Sexual Health Promotion found that women who incorporated vibrators into their sex lives reported higher arousal and satisfaction. Moreover, 70 percent have a favorable view of the pleasurable props [source: Abbasi].