• DOI:10.1007/S10508-007-9297-6
• Corpus ID: 28199803

Why the Human Penis is Larger than in the Great Apes

@article{Bowman2008WhyTH,
  title={Why the Human Penis is Larger than in the Great Apes},
  author={Edwin A Bowman},
  journal={Archives of Sexual Behavior},
  year={2008},
  volume={37},
  pages={361}
}

• Edwin A Bowman
• Published 1 June 2008
• Medicine
• Archives of Sexual Behavior

In Diamond’s (1997) book Why is Sex Fun? The Evolution of Human Sexuality, he draws attention to the fact that, as yet, no one has come up with a satisfactory explanation as to why the human penis is comparatively larger than that of the other great apes. Consider the following briefly outlined argument. It is generally accepted that the human female bony pelvis enlarged over millions of years as an adaptation to the increasing size of the newborn infant’s brain case. However, to my knowledge, no one has given proper consideration to the concurrent changes that took place in the soft tissues of the female pelvis, i.e., the vagina and the paravaginal supporting structures. The vagina is a multifunctional organ. Not only does it serve as the passageway for the infant to exit the mother’s body, but also in a woman’s upright position it supports the bladder, the rectum, and the internal reproductive organs. It does all this and additionally manages to serve as a coital organ, especially structured to accommodate the male organ and to induce orgasm and ejaculation. In its normal position, the vagina is a potential space, the anterior (top) and the posterior (bottom) walls of the muscular sheath in apposition and supported laterally by attachments to the bony pelvis. As the diameter of the bony pelvis increased over time to permit passage of an infant with a larger cranium, the size of the vaginal canal necessarily also became larger, potentially resulting in a vaginal–penile discrepancy in size. Sexually satisfying coitus requires a satisfactory ‘‘fit’’ for both partners. Over the long evolutionary period involved, men with larger penises would be selected out by receptive women because of the more gratifying sexual experience, and a more certain ejaculation and impregnation, examples of adaptive evolution and sexual selection. In sum, man’s larger penis is a consequence of his larger brain. As a gynecologist, I have had many occasions to discuss penile size with women contemplating vaginal plastic surgery. In general and within reason, women prefer larger penises. The preference is ingrained in our culture and probably has been so since prehistoric times.