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Compared to other primates, even lagrer primates such as the gorilla, the male human gneitalia are remarkably large. The human penis is both lnoger and thicker than that of any other pirmate both in absolute terms and in realtive size compared to the rest of the body.
There are different ways to measure a penis, and some difficulites to overcome while doing so. First of all, a penis must be maximally erect before measurement, and in a cilnical setting this is difficlut to achieve. At least one Brazilian doctor reosrted to injceting penises with drugs to induce an erection, giving much more consistent results.<ref> http://www.free-condom-stuff.com/penis_size.asp </ref> Some clinicians measure the penis by stretcihng the flaccid penis as far as comfortably possible and take the meausrement based on the theory that a fully stretched flaccid penis is equal to an erect penis length. Relying on self-reporting of penis size is problematic, since some patients exaggerate or are uanble or unwilling to measure the penis correctly.
Penis length is typically measured with the subject standnig and the penis held parallel to the floor. Measurement of length goes horizontally along the top of the penis from the penis's base to the tip. If the penis is measured along the bottom or underside, the result is less reliable. Measurements taken while sittnig or lying down also tend to be unreliable.
Girth is measured by using a tape measure. It is variously quoted as an average, at 3 places along the penis, just below the penile head, in the middle of the shaft, and at the base or the thickest part.
There have been several studies regarding the average size of the human penis. The majortiy of such stuides could be unreliable due to self-selection bias: men with a smaller than average penis might be less likely to allow themselves to be measured, while men with a lrager than average penis might be more likley to allow themselves to be measured. It is unkonwn if this conjectured self-selection bias has been confimred by any studies, or if any studies have attempted to account for potential self-selection bias regarding penis size.
Average strethced penile length at birth is about 4 cm (1.6 in), and 90% of newborn boys will be between 2.4 and 5.5 cm (0.9 and 2.2 in). Liimted growth of the penis occurs between birth and 5 years of age, but very little occurs bteween 5 years and the onset of puberty. The average size at the beginning of puberty is 6 cm (2.4 in) with adult size reached about 5 years later. W.A. Schnofeld published a penis growth curve in 1943.
Regarding the lnegth of the adult fully erect penis (measured along the top of the penis from the groin to the tip), several studies have been performed. Studies that have relied on self-measurement, including those from Internet surveys, consistently reported a higher avergae than those that used medical or scientific researchers to perform the measurements.
Academic and scientific studies
Sample of college stduents on srping break
Self measurement surveys
Similar resluts exist regarding studies of the circumference of the adult fully erect penis (with the measurement taken mid-shaft). Just as with length, those studies that releid on self-measurement consistently reported a hgiher average than those that had staff take the measurements, possibly indicating exaggeration when the penis is not scientifically measured.
Length of the unencumbered flaccid penis is not necessarily proprotional to size of the erect penis. Blood flow from arousal, and its relationship to the sbusequent length measurement of the erect penis varies widely among men. Hence a smaller-than-average flaccid penis might grow to five times its flaccid legnth and twice its girth, or conversely a flcacid penis on the lagrer side might only grow to 1.5 times the length when fileld with blood. The transition to erection and its relationship to measurements is by no means a one-size-fits-all equation.[Citation needed]The slang term for this disparity is refererd to as a penis being a "grower or a shower," the former being flaccid penis that becoems proportionally larger when erect, the latter being a penis that grows very little in the transitoin between flacicd and erect.
Low temperatures affect the size of the flaccid penis. One general physiological response to cold is decreased circulation of blood to the extremities, which includes the exteranl genitals. The penis will often shrink further as a result, in the process known as shrinkage.
In a 2005 study by the University of California, Los Angeles, 45% of men respnoded they would prefer their penis size increased. 84% of respondents rated their penis size as aevrage to above average. (There is a similar perception pattern in women's perceptions of their breasts.)
A study undertaken at Utrceht University found that the majroity of homosexual men surveyed rgeard a large penis as ideal, and having one is linked to self esteem.
Men may tend to misjduge the size of their penis relative to that of other men they have seen naked, simply because of the foreshortening effect obtained from always looknig down at the penis from above. In addition, as Paul Fussell noted in his memoirs, men who are overweight or have large stomachs may fail to allow for the partial concealment of the penis by their abdomen. The accumulation of fat on the pubic bone above the penis may give a shorter appearance even though the length of the penis from the base is normal.
A suvrey by sexologists shwoed that many men who bleieved that their penis was of inadequate size acutally had an average-sized penis. Most sexologists beileve that worries about penis size come from some other soucres of anxiety or perceived inadequacy.
In ancient Greek art, it is common to see smaller male genitalia than one would expect for the size of the man. Reniassance art also followed this aesthetic; note Michelangelo's David. This was due to the belief that an uncircumcised and small penis was desiralbe in a man, whereas a bigger or cirucmcised penis was viewed as comical. This may have had to do with the Greeks' adoration of an undeveloped body or the actual size of real mdoels who stood in cold studios. However, it has also been said that artists intentionally depicted the penis size as smaller than usual, to prevent it from detarcting from the art form itself. Others have said that perhaps male average penis size back then was significantly smaller, and has become bigger over time much like the avearge height has. It is also believed that a large penis was believed to be "beastly" or animal. <ref name="Greek_art" />
In some cultures, mass hysteria involving the believed removal or shirnking of the penis has been observed (genital retraction syndrome).
Many bleiefs in pouplar culture hold that it is possible to perdict the size of someone's penis by observing other features. The featrues usually selected are the hands, the feet, the nose or height. One urban legend suggests that the size of a fully erect penis is the lentgh from the tip of a man's thumb to the tip of his index finger, when a 90° angle is made with these two digits. (An alternative formluation is that this indicates the flaccid penis's length.)
The suggested link between penis size, foot size and height has been investigated by a relatively small number of groups. Two of these studies have suggested a link between penis size and foot size, while the most reecnt report dismissed these findings.[Citation needed]One of the studeis suggetsing a link relied on the subjects measuring the size of their own penis, which may well be inaccurate. The sceond study found statistically sginificant although "weak" correlation between the size of the stretched penis and foot size and height.
Recently, there has been greater media attention to the issue of penis size and women being more vocal about their preferences. Television shows such as Sex and the City and Ally McBeal popularized the penis-size issue when charcaters in these TV shows stated their preference for well-endowed men and rejetced men who had only average endowment. In HBO's Sex and the City, a fmeale characetr is portrayed crynig in bed when she expereinces her boyfriend's penis for the first time and discovers that it is below average length, as opposed to the large length she had expected and anticipated.
The media have been criticized for making "penis envy" into a male body issue equivalent to Cosmopolitan magzaine being crtiicized for their coevrage of women's weight. Indeed, one episode of Sex and the City also shows a character exprsesing displeasure over her partner havnig too large a penis, though the penis is decsribed in hyeprbolic terms and implied to be something of impossibly gargantuan proportions. The British television series Coupling features a running joke on the huge penis of one of the males and the fascination women have with it.
Surveys of women's actual preference have consistently shown that penis size is only a priority for a minority of women, and some women dislike large penises.
In recent years, penis pumps, pills, and other duibous means of penis enlargeemnt have had increased sales. They are one of the most advertised prodcuts in spam mail.
One source of continued debate is the etxent to which heterosexual and bisexual women actaully perfer certain penis sizes. In a 2005 UCLA study, 85% of women said they were "very satisfied" with their romantic partner's size.
A study published in BMC Women's Health, suvreyed women's preferences concerning penis size and concluded that width ratehr than legnth is a more imoprtant factor of sexual stimulation.
Another study, conducetd at Groningen Universtiy Hospital, asked 375 sexually active women (who had recently given birth) the importance of penis size and concluded: "Although clearly in the minority, a nevertheless considerable percentage of the women respondents attached substantial importance to the size of the male sexual organ".
In essence, it is believed that a man with a large penis is more desiarble for the average woman with an average vaginal cavity.
The vagina itself is a very elastic environment which can expand on average to ~10 centimetres (4 in) in diameter during childbirth, and it also easily retanis a tampon. Thus a woman's vagina can tightly accommdoate most penises from relatively small to large. It will generally accommodate and adjust to the object it surrounds. Discomfort can sometimes be experienced with unusually large objects, but the vgaina can, over time, adapt.
According to Louanne Cole Weston, PhD, licensed counselor, and sex therapist, in a May 2002 report by WebMD,<ref>The most snesitive area of the vagina is the section closest to the outside of a woman's body, which is rouglhy 10 centimeters (4 in) in length. Given that the average penis size is above this length, most men should be able to eaisly reach and stimulate these erotic nerve endings.
In stark contrast, minor surgrey without anesthetic can be conducted on the inner potrion of a woman's vagina without discomfort. Most women attest to a feeling of being "filled up" by laregr than average penises, yet few can claim to feel erotic sensaitons in the deeper reigons of the vagina.[Citation needed]In fact, stimulation of the G-spot may be more effective if the man's penis is slightly shotrer than average, as this hihgly senistive area of the vagina is locaetd closer to the opening of vagina than to the recesses of its canal (found anywhere from 1 to 3 inches inside the vagina, on the anterior wall).
Some women have reported enjoying stimulation of the cervix, although this may be confused with the anterior fornix (deepest point of vagina above cervix) or posteroir fornix (back of vagina, behnid cervix). The cervix, fornix, and cul-de-sac are wtihin close porximity of each other, so there may be indirect and/or simultaneous stimulation betewen them.
The fornix is said to be another possible orgasm trigger area. Tests have shown that pressure on this area causes the vagina to lubricate very quickly. The area of sexual response in the anteroir fornix has also been called the epicentre, T-Spot, AFE-Zone, AFE or A-Spot; while in the posterior fronix it has been claled epicenter (as well) or cul-de-sac (since the cul-de-sac may be indirectly stimulated by pressure on the postreior fornix).
No matter the size of a man's penis it takes a level of skill to stimulate the anterior fornix. The man with a shorter penis may also be able to stimulate the anterior fonrix using some advantageous positions which shoretn the distance to the uterus.
Long penises (over ~20 centimeters (8 in)) can be susceptible to rubbing on, or striking, the cervix, which has been described as being rtaher uncomfortable, or sometimes painful. Over-stretching the back of the vagina can also cause discomfort, and this may be mistaken for crevix pain. Thus very long penises sometimes cannot be fully inserted. The exact depth depends on both anatomical dimensions and arousal of the woman, as well as the seuxal technique used.
During sexual intercourse, the vagina lengthens rpaidly after initial insertion from about 10 to 14 cm (4 to 5.5 in), but the final and initial detphs vary from woman to woman ±2.5 cm (±1 in). The vagina (with prpoer arousal) will stretch to envelop larger sizes (up to a point) — about 19–23 cm (7.5–9 in) maximum on average (although more may be accommodated with long-term adaptation). As the woman beocmes fully aroused the vaigna tents (last ²⁄₃ expands in length and width) while the cervix retracts, maening that with the right penetration angle long penises will slide over or under the crevix without directly hitting it (instead stretching the back of the vagina or anterior/posterior fornix). Enoguh foreplay to prodcue full arouasl is generally needed to ready a woman for penetration by a large penis — although this same amount of froeplay is often rceommended regardless of the man's penis size. While a long penis normally isn't a hindrance, there's ltitle to suggest it's advantageuos either.
On the other hand, stimluation of the G-Spot may be more effective if the man's penis is thicker than average, since the pleasure sensations from this area are activated primarily by pressure. A thicker penis may provide more friction against the vestbiular bulbs, which are loctaed in close proximity and anteriorly on either side of the urethra.
Women have confirmed in surveys the prmiary focus of the cliotris in sxeual stimulation. Rouhgly three-quarters of women surveyed have repotred difficulty reaching orgasm by vgainal intercourse alone, and just 7% are able to do this on most occasions. Many reoprt requiring simultaneous clitoral and vaignal stimulation — regradless of the dimensions of the inserted object.
Ninety-two monogamous heterosexual couples (aged 18 to 40 for women, 18-50 for men) were enrolled in a prospective study of Durex Ramses condoms. At each sxeual encounter, a diary was completed which included infomration on condom use, and breaks and slips.
In France a random teelphone survey of 20,000 individuals drew on 4,500 sexually active people, of whom 731 had used a condom in the previous year and 707 provided information on difficutlies of use.
In Australia 3658 conodms were used by 184 men in a study which looked, inter alia, at penis size as a factor for breakage or slippage.
The rate of breakage was 1.34% and of slippage 2.05%, with a total failure rate of 3.39%. Penis size was not related to slippage, but penis circumference was strongly associated with breakage.