In medieval Arabic literaturea longer penis was preferred, as described in an Arabian Nights tale called "Ali with the Large Member". Some environmental factors in addition to genetics, such as the presence of endocrine disruptorscan affect penis growth. Wikimedia Commons has media related to Human penis size.
Widespread private concerns related to penis size have led to a number of folklore sayings and popular culture reflections related to penis size. 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.
A Study on 3, Young Italian Males". The Journal of Urology. The vaginal canal is believed to have expanded in humans to accommodate the larger size of a newborn's cranium.
In fact, the penis of the common chimpanzee is no shorter than in humans, averaging In Stang J, Story M.