Anonymous Coward writes: "The human penis is comparatively larger than that of the other great apes because of our comparatively larger brains, gynecologist Edwin A. Bowman explains in the journal Archives of Sexual Behavior. Through millions of years evolution the infant babies' skulls became larger in order to accommodate bigger brains, explained Dr. Bowman. This in turn led to a female pelvis become larger to allow women to give birth to children with larger brains, and this led to the female vagina also becoming less tight."