Human penis size

Compared to other primates, even larger primates such as the gorilla, the male human genitalia are remarkably large. The human penis is both longer and thicker than that of any other primate, as are the testes . Nevertheless, penis size is of great concern to many people. Some consider having a large penis a mark of masculinity; others are concerned that their penis is too small to satisfy their sexual partners. These insecurities have led to many myths about penis size, and the creation of a whole industry devoted to penis enlargement.

Measuring the penis

There are a variety of different ways to measure a penis, and there are a number of difficulties in doing so. First of all, a penis must be maximally erect to do so, and in a clinical setting this is difficult to achieve. At least one Brazilian doctor resorted to injecting penises with drugs to induce an erection, giving much more consistent results. Relying on self-reporting of penis size is problematic, since some patients exaggerate or are unable or unwilling to measure the penis correctly.

Length of a penis is typically measured with the subject standing and the penis held parallel to the floor. Measurement of length goes horizontally along the top of the penis from the patient's base to the tip.

Girth is measured by using a tape measure. It is variously quoted as an average, or at 3 places along the penis, or just the penile head, or in the middle of the shaft, at the base, or from the thickest part.

Data

There have been several studies regarding the average size of the human penis. The majority of such studies could be flawed due to self-selection bias: men with a below-average sized penis might be less likely to allow themselves to be measured (making the figures noted below above the true average), or men with a larger-than average sized penis might be more likely to allow themselves to be measured (making the figures noted below also above the true average).

There is an ongoing penis size government study in India, commissioned with the goal of helping reduce the high condom failure rate there.

Size at birth

Average stretched penile length at birth is about 4 cm, and 90% of newborn boys will be between 2.4 and 5.5 cm (0.94 and 2.17 inches). Limited growth of the penis occurs between birth and 5 years of age, but very little occurs between 5 years and the onset of puberty. The average size at the beginning of puberty is 6 cm with adult size reached about 5 years later. W.A. Schonfeld published a penis growth curve in 1943.

Erect length

File:Penis frequency.jpg

Frequency graph of LifeStyles data

Percentile plot of LifeStyles data

Regarding the length 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 consistently reported a higher average than those that had staff take the measurements.

• A study published in the September 1996 Journal of Urology concluded that average erect length was 12.9 cm (5 inches. (Measured by staff).
• A UCSF study by Wessells et.al. published in 1996 found an average of 5.1 inches (13.0 cm). (Measured by researchers)
• A study by a Brazilian urologist found an average of 5.7 inches (14.5 cm). (Measured by researchers)
• A German study in 1996 also reported an average of 5.7 inches (14.5 cm). (Measured by researchers)
• A study conducted by LifeStyles Condoms during 2001 Spring Break in Cancún found an average of 5.9 inches (15.0 cm). (Measured by staff)

Erect circumference

File:Penis circum.jpg

Plot of LifeStyles data of circumference

File:Penis circum percentile.jpg

Percentile plot of LifeStyles data of circumference

Similarly, regarding the circumference of the adult fully erect penis (with the measurement taken from the midshaft of the penis), several studies have been performed. Just as with length, those studies that relied on self-measurement consistently reported a higher average than those that had staff take the measurements.

• An UCSF study by Wessells et.al. published in 1996 found an average of 4.9 inches (12.5 cm). (Measured by staff)

• A study by a Brazilian urologist found an average of 4.7 inches (12.0 cm). (Measured by researchers)

• A study conducted by LifeStyles Condoms during 2001 Spring Break in Cancún found an average of 5.0 inches (12.7 cm). (Measured by researchers)

Flaccid length

The flaccid penis is measured when fully stretched, from the belly to the tip, excluding the foreskin. The length of a stretched flaccid penis closely conforms to erect length.

The length of the unstretched flaccid penis is no guide to the size of the erect penis ; indeed, some men with small flaccid penes may have larger erections than men with larger flaccid penes. When a man with a relatively large flaccid penis has a normal or below average length penis when he is fully aroused, or when a man with a relatively small flaccid penis has a normal or above average length penis when he is fully aroused, they are known by the slang terms "showers" and "growers" respectively.

Although there are differences in flaccid penis sizes, it is generally accepted that every man's flaccid penis is approximately the same size. At most, there is usually only 0.5cm of a difference between all men over 18, however irregularities do exist.

Present environmental conditions play a role in the size of a relaxed flaccid penis, in particular cool temperatures. One general physiological response to cold is decreased circulation of blood to the appendages. As the size of the penis very much relies on blood supply, this results in a decreased flaccid size. The slang term "shrinkage" is sometimes used to describe this phenomenon; this was featured in a famous episode of Seinfeld. As humorist Garrison Keillor once said, "At forty degrees below zero, all men are indeed equal."

Perceptions

In a 2005 study by the University of California Los Angeles, 45% of men responded they would prefer their penis size increased.[6] 84% of respondents rated their penis size as average to above average. (There is a similar perception gap in women's perceptions of their breasts.)

Men may tend to misjudge the size of their penis relative to that of other men they have seen naked, simply because of the foreshortening effect obtained from always looking 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 survey by sexologists showed that many men who believed that their penis was of inadequate size actually had a normal-sized penis. Most sexologists believe that worries about penis size come from some other source of anxiety or perceived inadequacy.

Past perceptions

In ancient Greek and Roman art, it is common to see the male genitalia to be smaller than one would expect for the size of the man. [7] Renaissance art also followed this aesthetic; note Michelangelo's David. This was due to the belief that the genitalia should not distract from the male form in sculpture.

Myths

In some cultures, mass hysteria involving the believed removal or shrinking of the penis has been observed. See penis panic for a detailed discussion.

Many theories are held in popular culture, that it is possible to predict the size of someone's penis by observing other features. The features usually selected are

• Size of hands
• Size of feet, or shoe size
• Size of nose
• Height of a person

One of these theories says that the size of a fully erect penis is the length from the tip of a man's thumb to the tip of his index finger, when a 90° angle is made with those two fingers.

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 recent report dismissed these findings. One of the studies suggesting a link relied on the subjects measuring the size of their own penis, which may well be inaccurate. The second study found statistically significant although "weak correlation" with the size of the stretched penis with foot size and height. A potential explanation for these observations is that the development of the penis in an embryo is controlled by some of the same Hox genes (in particular HOXA13) as the limbs. Mutations of some Hox genes that control the growth of limbs cause malformed genitalia (hand–foot–genital syndrome). However the most recent investigation failed to find any evidence for a link between shoe size and stretched penis size. Given the large number of genes which control the development of the human body shape and effects of hormones during childhood and adolescence it would seem unlikely that an accurate prediction of penis size could be made by measuring a different part of the human body.

Other studies correlating the size of the human penis with other factors have given intriguing results. Notably one study analysing the Kinsey data set found that homosexual men had statistically larger penises than their heterosexual counterparts. One potential explanation given is a difference in the exposure to androgen hormones in the developing embryo.

Penis size and vaginal stimulation

According to Dr. Louanne Cole Weston, in a May 2002 report by WebMD, several misconceptions have developed surrounding penile-vaginal intercourse. Cultural preferences may have enlarged the importance of deep vaginal penetration in obtaining female orgasm.

The vagina itself is a very elastic environment through which an infant can pass, yet it also easily retains a tampon. It will accommodate and adjust to the entity it surrounds.

The perception of the vaginal canal as being the primary source of orgasmic stimulation may be exaggerated in many cultural circles. The most sensitive area of the vagina is the section closest to the outside of a woman's body, which is roughly 4 inches in length. Given that the average penis size is above this length, most men should be able to easily reach and stimulate these erotic nerve endings. [8]

In stark contrast, minor surgery without anesthetic can be conducted on the inner portion of a woman's vagina without discomfort. Most woman attest to a feeling of being "filled up" by larger than average penises, yet few can claim to feel erotic sensations in the deeper regions of the vagina. In fact, stimulation of the G-Spot is often more effective if the man's penis is slightly shorter than average, as this highly sensitive area of the vagina is located closer to the opening of vagina than to the recesses of its canal.[9]

Stimulation 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 by pressure more than anything else. A thicker penis supposedly provides more friction against the clitoral bulbs, which are located internally under the clitoris, itself. Additionally, some claim that if a penis is thick enough compared with the vaginal opening, i.e. vulva, stretching will occur. This stretching can supposedly cause the clitoral hood to pass back and forth across the clitoris, effecting extra stimulation of that massive cluster of nerve endings. This stretching is claimed to pull the clitoris down into the path of the thrusting penis, causing it to make contact with, and rub across, the top or dorsal section of the penis. This may facilitate even greater clitoral stimulation.

Women have confirmed in surveys the primary focus of the clitoris in sexual stimulation. Roughly three-quarters of women surveyed have reported difficulty reaching orgasm by vaginal intercourse alone. Many report requiring simultaneous clitoral stimulation -- regardless of the size of the inserted object. [10]

Micropenis

Main article: Micropenis

A penis whose stretched flaccid length is more than approximately 2.5 standard deviations below average size for the age group but otherwise formed normally is referred to in a medical context as a micropenis. Some of the identifiable causes are deficiency of pituitary growth hormone and/or gonadotropins, mild degrees of androgen insensitivity, a variety of genetic syndromes, and variations in certain Homeobox genes. Some types of micropenis can be improved with growth hormone or testosterone treatment in early childhood. Penis-enlargement self-treatments are not effective for this condition.

A news post on New Scientist dated Dec 6, 2004 reads "A new surgical procedure has allowed men with abnormally short penises to enjoy a full sex life and urinate standing up, some for the first time. Tiny "micro-penises" have been enlarged to normal size without losing any erogenous sensation, say UK doctors."

Female preference

One source of continued debate is the extent to which women actually prefer certain penis sizes. In the 2005 UCLA study, 85% of women said they were "very satisfied" with their partner's size.[11] [12]

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 characters in these TV shows stated their preference for well-endowed men and rejected men who had only average endowment. In HBO's Sex and the City, a female character is portrayed crying in bed when she experiences 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. In the same episode the characters debate whether it's proper to dump a man because of displeasure over the size of his penis; they conclude that it's OK and at the end of the episode that one of the women does indeed dump her boyfriend because she doesn't like the size of his penis, even though earlier in the episode she reveals that she thinks she loves him.

The media image of women's preference may have had an impact on some average sized men, and caused even more damage to below-average sized men who are likely already self conscious. In recent years, penis pumps, pills, and other dubious means of penis enlargement have had increased sales.

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. The media have been criticized for making "penis envy" into a male body issue equivalent to Cosmopolitan Magazine being criticized for their coverage of women's weight. Indeed, one episode of Sex and the City also shows a character expressing displeasure over her partner having too large a penis, though the penis is described in hyperbolic terms and implied to be something of impossibly gargantuan proportions. It has also been recorded in many cases that some women have a hard time with men with above average sized penis, with the sexual experience being uncomfortable or painful for the woman. Some women request that the man does not fully penetrate her, making sex somewhat more awkward and controlled.

Race and penis size

Differences in average penis size between different races has been a subject of considerable controversy since it could be taken to imply that one race is "superior" or "inferior" to another.

The cultural issues involved with the question of race and penis size are complex, with both larger and smaller penises used as justification for regarding other races as inferior; as evidence of an oversexed and brutish animal nature in the former case, or of sexual inadequacy in the latter case. In general, there is a tendency to see the penis size of one's own group as the "right" size, compared to those of others.

There is considerable debate as to whether specific racial variations in penis size exist, and if they do, whether observed variations can be explained in terms of other factors such as correlations of penis size to body size. In any case, within-group variation in penis size (±30%, see above) seems to be considerably larger than claimed between-group variation of average penis size (±4%, see below).

One study by the controversial Canadian psychologist J. Philippe Rushton states that "[p]enis size also varies moderately across populations, being largest among African populations, smaller among European populations, and smallest among East Asian populations,..." [13] Rushton has also stated that the World Health Organization specifies 53 mm wide condoms for Africa, 52 mm wide condoms for Europe, and 49 mm condoms for Asia. [14]

According to Family Health International, "The World Health Organization bases its specifications for condom width on consumer preference and penis size, citing three studies. Taken together, the studies show significant variations in penis size within all population groups, but also indicate that men of African descent on average have a slightly wider and longer penis size, Caucasian men have a medium size, and Asian men a slightly narrower and shorter size."

However, this is far from a generally-accepted view. Frantz Fanon covers this subject in some detail in Black Skin, White Masks (1952), where he tends towards the view that the supposed positive correlation between large penises and African ancestry is a myth, a conclusion that he also backs up with statistics.

Penis size and condom use

In a British study examining condom use and reproductive health, the authors stated that "penis size could affect condom failure." The cross-sectional study looked at race factors on condom use. In this study, 18% of people of African descent, 7% of Caucasians and no Asians reported frequent breakage. In contrast, 21% of Asians, 8% of blacks and 2% of whites reported frequent complete slippage.

Based on the hypothesis that anatomical differences exist among regions, a series of FHI studies were conducted in three Asian countries to compare small and standard width condoms (39 mm and 49 mm), and in three African countries to compare larger and standard width condoms (55 mm and 52 mm).

According to FHI, "Among the African sites, breakage rates were slightly higher and slippage was slightly lower for the smaller of the two condoms being compared." The data from the Asian sites was inconsistent.

FHI concluded that "almost none of the differences in breakage and slippage rates from either the Asian or African sites were statistically significant. Thus, results from these studies pertaining to penis size and condom failure were inconclusive."[15]

References

• The Kinsey Institute penis size bibliography
• Sutherland et al. "The effect of prepubertal androgen exposure on adult penile length." Journal of Urology, Vol. 156(2S), 783-787, 1996.
• Lee PA, et al. "Micropenis. I. Criteria, etiologies, and classification." Johns Hopkins Med J 1980; 146:156.
• W.A. Schonfeld, Am J Dis Child 1943;65:135
• Niels Lauersen, M.D. and Steven Whitney, "It's Your Body: A Woman's Guide to Gynecology", 3rd Edition 1983, p. 480 (Berkley Publishing Co.: New York), ISBN 0425099172
• Bogaert, A. F., & Hershberger, S. L. (1999). The relation between sexual orientation and penile size. Archives of Sexual Behavior 28:213-221.(PMID:10410197)[16]
• Mortlock DP, Innis JW (1997) Mutation of HOXA13 in hand-foot-genital syndrome.Nat Genet 15(2):179-80.(PMID:9020844)[17]
• Goodman FR (2002) Limb malformations and the human HOX genes. Am J Med Genet 112(3):256-265(PMID:12357469)[18]
• Shah, J. & Christopher, N. (2002) Can Shoe Size Predict Penile Length? BJU Int 90(6):586-7 (PMID:12230622)[19]
• Siminoski K and Bain J (1993) The Relationship Among Height, Penile Length, and Foot Size. Annals of Sex Research 6(3):231-235
• Kondo T, Zakany J, Innis JW, Duboule D.(1997) Of fingers, toes and penises. Nature 390(6655):29(PMID:9363887)[20]
• Rushton, J.P. & Bogaert, A.F. (1987) Race differences in sexual behavior: Testing an evolutionary hypothesis. Journal Research in Personality 21(4): pp. 536-7

See also

• Penis envy
• Phalloplasty
• Megalopenis

External links

• Kinsey Institute page on the penis
• Penis size based on body parts Investigation into myth that Hands/feet/nose are an indicator of penis size
• Measurection Site dedicated to discussion and support of small to average sized penis issues.
• LPSG Site dedicated to discussion and support of large to average sized penis issues.