What Is a Penile Bone?
Almost every mammal has a penile bone or baculum except for humans, donkeys, horses, zebras, hyenas, rabbits, and pikas. Walruses have the longest penis, averaging 2-3 feet in length. In species with a penile bone, it is stored in the abdomen and, when needed, a set of muscles slips it into the fleshy sheath in the penis. This mechanism comes in handy when animals are attempting to mate under less than optimal circumstances such as out in the open while trying to avoid predators. Thus, having the baculum ensured a short but successful encounter.
Females of the same species that have a penile bone have something comparable, a baubellum or clitoridis. Most species with a penile bone and a baubellum only reproduce through induced ovulation where intercourse stimulates the female to release the egg to be fertilized. The females of these species do not release eggs at regular intervals as humans do. Thus, the baculum was essential to reproduction.
Both gorillas and chimpanzees have a baculum. In chimps, the baculum is less than an inch in length and located at the base of the penis.
Richard Dawkins in his book, The Selfish Gene, speculates that the loss of the bone in humans, when it is present in our nearest related species, the chimpanzee, is probably a result of sexual selection by females looking for signs of good health in prospective mates. “The reliance of the human penis solely on hydraulic means to achieve a rigid state makes it particularly vulnerable to blood pressure variation. Poor erectile function betrays not only physical states such as diabetes and neurological disorders but mental states such as stress and depression."
In the Book of Genesis, God creates Eve from Adam’s rib. Biblical Hebrew does not have a word for the penis. Gilbert, Scott F. and Ziony, Zevit. 2001. Congenital human baculum deficiency: The generative bone of Genesis 2:21–23. American Journal of Medical Genetics 101(3): 284–285, suggest this is an explanatory myth for the absence of a bone in the human penis rather than the proverbial missing rib. By the way, human males and females have the same number of ribs.
According to Skin Flutes and Velvet Gloves: A Collection of Facts and Fancies, Legends and Oddities About the Body’s Private Parts by Dr. Terri Hamilton, the penis cannot break but the delicate erectile tissue can be torn or fractured and the ligament that supports the penis can be snapped. Should this happen, wrap the unfortunate organ in ice and get to a doctor or ER immediately.
Maybe another reason that humans did not evolve a penis bone is because we are surviving pretty well without it. For those who disagree, there is always the penile prosthesis.
Any type of natural or replica baculum is available at skullsunlimited.com. The raccoon baculum is sometimes worn for good luck charm or a symbol of fertility.