An adult penis with an erect length of less than 7 cm (2.8 in), but otherwise formed normally, is referred to in medicine as a micropenis. Studies
While results vary slightly across reputable studies, the consensus is that the mean human penis, when erect, is in the range 12.9–15 cm (5.1–5.9 in) in length. A 2015 systematic review published by Veale et al. of medical research on the topic over the previous 30 years published in BJU International showed similar results, giving mean flaccid, stretched non-erect, and erect lengths of 9.16 cm, 13.24 cm, and 13.12 cm respectively, and mean flaccid and erect circumferences of 9.31 cm and 11.66 cm respectively. Erect lengths in the included studies were measured by pushing the pre-pubic fat pad to the bone, and flaccid or erect girth (circumference) was measured at the base or mid-shaft of the penis. Length
Flaccid
One study (published in 1996) found the mean flaccid penis length to be 3.5 inches (8.9 cm) (measured by staff). A review of several studies found average flaccid length to be 9–10 cm (3.5–3.9 in). Length of the flaccid penis does not necessarily correspond to length of the erect penis; some smaller flaccid penises grow much longer, while some larger flaccid penises grow comparatively less.The penis and scrotum can contract involuntarily in reaction to cold temperatures, anxious or nervous level and participation in sports. This decrease of flaccid penis size is referred to by the slang term "shrinkage", due to action by the cremaster muscle.
The mate competition hypothesis involves the prediction that a human with a larger penis would be able to displace the sperm of another. Studies have found that larger penises do not displace other sperm more effectively than smaller penises, but rather longer penises may ejaculate sperm inside the vagina in places that would be harder for a following penis to displace. The depth of pelvic thrusting was correlated to the displacement of competing sperm. See also
Digit ratio
Human vaginal size
Jonah Falcon
Penis enlargement
Penis envy
Phalloplasty
Sexual selection in humans
The Third Chimpanzee
Why Is Sex Fun? References
Citations
General and cited sources
"Men worry more about penile size than women, says 60-year-old research review" (Press release). Blackwell. 31 May 2007. Retrieved 11 August 2018. Lee, P. A; Mazur, T; Danish, R; Amrhein, J; Blizzard, R. M; Money, J; Migeon, C. J (1980). "Micropenis. I. Criteria, etiologies and classification". The Johns Hopkins Medical Journal. 146 (4): 156–63. PMID 7366061. NAID 10010056499. Lauersen, Niels; Whitney, Steven (1983). Its Your Body: A Womans Guide to Gynecology (3rd ed.). New York: Berkley Publishing. p. 480. ISBN 978-0-425-09917-9. Rushton, J.Philippe; Bogaert, Anthony F (1987). "Race differences in sexual behavior: Testing an evolutionary hypothesis". Journal of Research in Personality. 21 (4): 529–51. doi:10.1016/0092-6566(87)90038-9. Sutherland, Ronald S; Kogan, Barry A; Baskin, Laurence S; Mevorach, Robert A; Conte, Felix; Kaplan, Selna L; Grumbach, Melvin M (1996). "The Effect of Prepubertal Androgen Exposure on Adult Penile Length". The Journal of Urology. 156 (2): 783–7, discussion 787. doi:10.1016/S0022-5347(01)65814-2. PMID 8683783. == External links ==