the alleged 'oversized' penis in black people". a study of 253 men from tanzania found that the average stretched flaccid penis length of tanzanian males is 11.5 cm (4.53 inches) long, smaller than the worldwide average, stretched flaccid penis length of 13.24 cm (5.21 inches), and average erect penis length of 13.12 cm (5.17 inches). a 2014 study, conducted from 2011–2013 on 5196 chinese males, reported an average flaccid unstretched penis length of 6.55 cm (2.57 inches) long, an average flaccid stretched length of 12.9 cm (5.08 inches) long, and an average erect length of 12.9 cm (5.08 inches) long. they stated that they had "also found that penile dimensions are different in different ethnicities, but further investigations are needed to validate this". however, the 'different ethnicities' referred to in the study were ethnicities within the chinese population. a 2016 study of 248 korean men identified the average erect penis length to be 13.53 cm (5.33 in). a study of 115 men from nigeria found that the average flaccid stretched penis length of nigerian males is 13.37 cm (5.26 inches) long, which is near identical to the worldwide average, stretched flaccid penis length of 13.24 cm (5.21 inches) and average erect penis length of 13.12 cm (5.17 inches). a 2014 american study by herbenick et al. of 1,661 sexually active men involving asian american, black american, white american, pacific islander/hawaiian, and native american men, found average racial differences in erect penile length and circumference to be generally less than one centimeter, with averages in length being: 14.14 cm (5.56 inches) for asian americans, 14.66 cm (5.77 inches) for black americans, 14.88 cm (5.85 inches) for pacific islanders/hawaiians, 12.86 cm (5.06 inches) for native americans, and 14.18 cm (5.58 inches) for white americans (and in circumference: asians 12.10 cm, blacks 12.29 cm, pacific islanders 11.88 cm, native americans 11.36 cm, and whites 12.25 cm). a 2015 systematic review of 15,521 men found "no indications of differences in racial variability", and stated that it was not possible to draw any conclusions about size and race from the available literature and that further research needed to be conducted. according to aaron spitz, a urologist, many websites and studies promoting variation of penis size between races use unscientific methods of collecting information and often ignore contradictory evidence. he concludes that "when you really take a good look at the naked data, there's not a whole lot there ." size preferences among sexual partners in a 1994 cover story by psychology today, 1,500 readers (about two-thirds women) were surveyed about male body image. many of the women were not particularly concerned with penis size, and over 71% thought men overemphasized the importance of penis size and shape. generally, the women polled cared more about width than men thought, and less about length than men thought, although the strength of caring for either among women showed a similar pattern. in a small study conducted by university of texas–pan american and published in 2001 in bmc women's health, 50 undergraduate women were surveyed by two popular male athletes on campus about their perceptions of sexual satisfaction and it was concluded that the width of a penis feels better than the length of a penis, when subjects are asked to choose between the two (size was left unspecified). it was also concluded that this may show that penis size overall affects sexual satisfaction, since women chose between the two options they were given. a study published in 2002, conducted at groningen university hospital, asked 375 sexually active women (who had recently given birth) the importance of penis size. the results showed that 21% of women felt length was important and 32% felt that girth was important. a study conducted at the australian national university, published in early 2013, showed that penis size influences a man's sex appeal, and the taller the man, the bigger the effect. the study showed life-sized 3d computer-generated images, altering the height and other physical attributes, with women typically registering preferences in under 3 seconds. a preference for taller men's larger penis size was indicated. a us study published in 2015 of the stated preferences of a panel of 75 women using 3d-printed models as scale references showed a preferred penis length of 16 cm (6.3 inches) and a preferred circumference of 12.2 cm for long-term sexual partners, with slightly larger preferred sizes of a length of 16.3 cm (6.4 inches) and circumference of 12.7 cm for one-time sexual encounters. two possible causes of pain for the female during penile-vaginal intercourse shown with diagrams of the female anatomy according to the study, however, when asked to estimate the length of their partner's penis, most women would say a size significantly smaller than what their partner was recorded to be. this suggests that perception of size is not entirely accurate. the visual impression of the size is not necessarily in correlation with the feeling in the vulva and vagina. a very long penis can cause dispareunia, if the man doesn't understand how to use it carefully. condom use one australian study of 184 men looked at penis length and circumference in relationship to condom breakage or slippage. 3,658 condoms were used. the study found that when used correctly, condoms had a breakage rate of 1.34% and a slippage rate of 2.05%, for a total failure rate of 3.39%. penile dimensions did not influence slippage, although penis circumference and broken condoms were strongly correlated, with larger sizes increasing the rate of breakage. biochemistry androgens like testosterone are responsible for penis enlargement and elongation during puberty. penis size is positively correlated with increasing testosterone levels during puberty. but after puberty, administration of testosterone does not affect penis size, and androgen deficiency in adult men only results in a small decrease in size. growth hormone (gh) and insulin-like growth factor 1 (igf-1) are also involved in penis size, with deficiency (such as that observed in growth hormone deficiency or laron syndrome) at critical developmental stages having the potential to result in micropenis. variance wikimedia commons has media related to flaccid and erect human penises in comparison. various size erect penises. there are large individual differences in penis size and shape. genetics there are certain genes, like homeobox (hox a and d) genes, which may have a role in regulating penis size. in humans, the ar gene, located on the x chromosome at xq11-12, may affect penis size. the sry gene located on the y chromosome may have a role to play. variance in size can often be attributed to de novo mutations. deficiency of pituitary growth hormone or gonadotropins or mild degrees of androgen insensitivity can cause small penis size in males and can be addressed with growth hormone or testosterone treatment in early childhood. conditions main article: micropenis an adult penis with an erect length of less than 7 cm or 2.76 inches but otherwise formed normally is referred to in a medical context as having the micropenis condition. the condition affects 0.6% of men. some of the identifiable causes are deficiency of pituitary growth hormone or gonadotropins, mild degrees of androgen insensitivity, a variety of genetic syndromes and variations in certain homeobox genes. some types of micropenis can be addressed with growth hormone or testosterone treatment in early childhood. operations are also available to increase penis size in cases of micropenis in adults. measuring erect micropenis environmental influence it has been suggested that differences in penis size between individuals are caused not only by genetics, but also by environmental factors such as culture, diet and chemical or pollution exposure. endocrine disruption resulting from chemical exposure has been linked to genital deformation in both sexes (among many other problems). chemicals from both synthetic (e.g., pesticides, anti-bacterial triclosan, plasticizers for plastics) and natural (e.g., chemicals found in tea tree oil and lavender oil) sources have been linked to various degrees of endocrine disruption. both pcbs and the plasticizer dehp have been associated with smaller penis size. dehp metabolites measured from the urine of pregnant women have been significantly associated with the decreased penis width, shorter anogenital distance and the incomplete descent of testicles of their newborn sons, replicating effects identified in animals. according to a 2008 study published by the us national library of medicine, approximately 25% of us women have phthalate levels similar to those observed in animals. a 2007 study by the university of ankara, faculty of medicine, found that penile size may decrease as a result of some hormonal therapy combined with external beam radiation therapy. in addition, some estrogen-based fertility drugs like diethylstilbestrol (des) have been linked to genital abnormalities or a smaller than normal penis (microphallus). a 2016 korean study found that newborn male circumcision is associated with shorter penile length. historical perceptions prehistory perceptions of penis size are culture-specific. some prehistoric sculptures and petroglyphs depict male figures with exaggerated erect penises. ancient egyptian cultural and artistic conventions generally prevented large penises from being shown in art, as they were considered obscene, but the scruffy, balding male figures in the turin erotic papyrus are shown with exaggeratedly large genitals. the egyptian god geb is sometimes shown with a massive erect penis and the god min is almost always shown with an erection. ancient ancient greek kouros sculpture from anavyssos dating to c. 530 bc, showing an idealized young man with a flaccid penisancient roman fresco from the house of the vettii in pompeii, dating to the first century ad, showing the god priapus weighing his massive, permanently erect penis against a bag of gold david (1504) by michelangelo the males of ancient greece believed that small penises were ideal. scholars believe that most ancient greeks probably had roughly the same size penises as most other europeans, but greek artistic portrayals of handsome youths show them with inordinately small, uncircumcised penises with disproportionately large foreskins, indicating that these were seen as ideal. large penises in greek art are reserved exclusively for comically grotesque figures, such as satyrs, a class of hideous, horse-like woodland spirits, who are shown in greek art with absurdly massive penises. actors portraying male characters in ancient greek comedy wore enormous, fake, red penises, which dangled underneath their costumes; these were intended as ridiculous and were meant to be laughed at. in aristophanes's comedy the clouds, "mr. good reason" gives the character pheidippides a description of the ideal youth: "a glistening chest and glowing skin / broad shoulders, a small tongue /a mighty bottom and a tiny prong." in greek mythology, priapus, the god of fertility, had an impossibly large penis that was always permanently erect. priapus was widely seen as hideous and unattractive. a scholion on apollonius of rhodes's argonautica states that, when priapus's mother aphrodite, the goddess of love and beauty, gave birth to him, she was so horrified by the size of his penis, his massive potbelly, and his huge tongue that she abandoned him to die in the wilderness. a herdsman found him and raised him as his son, later discovering that priapus could use his massive penis to aid in the growth of plants. nonetheless, there are indications that the greeks had an open mind about large penises. a statue of the god hermes with an exaggerated penis stood outside the main gate of athens and in alexandria in 275 bc, a procession in honor of dionysus hauled a 180-foot phallus through the city and people venerated it by singing hymns and reciting poems. the romans, in contrast to the greeks, seem to have admired large penises and large numbers of large phalli have been recovered from the ruins of pompeii. depictions of priapus were very popular in roman erotic art and literature. over eighty obscene poems dedicated to him have survived. penis size is alluded to in the bible: 18 and she revealed her whorings, and she revealed her nakedness, and so i turned from her just as i turned from her sister. 19 yet she increased her whorings, recalling the days of her childhood when she was prostituted in the land of egypt. 20 and she lusted after her male lovers whose genitalia were the genitalia of male donkeys and their seminal emission was the seminal emission of horses. ezekiel 23:18-20 lexham english bible ancient chinese legend holds that a man named