Category Archives: Human Body / Medicine

The Boneless Boner. How monogamy killed the Penis Bone – Carrie Weisman. 

Because sex is responsible for the creation of new life, we don’t often associate it with loss. But our mating habits may be to blame for the disappearance of something inside ourselves, leading some to ask, what was the human penis bone, and where did it go?

The baculum, as it’s more formally known, has been described as the “most diverse bone” ever to exist, or certainly the most individualized. Believed to have “evolved in mammals more than 95 million years ago,” the size of the penis bone changes from owner to owner. In chimpanzees, the penis bone is roughly the size of a human fingernail. In walruses, it measures upward of two feet. In humans, it simply doesn’t exist. Or doesn’t exist anymore.

The penis bone grew larger in males who engaged in something called “prolonged intromission,” a fancy phrase that refers to sex lasting more than three minutes. While these days, lengthy sex sessions are linked to pleasure and stamina, evolution offers a more practical reason for shagging so long.

A male who spends more time penetrating a female has a better chance of impregnating her. At the same time, a long romp helps keep her away from the competition. It’s believed that males with longer penis bones are armed with more structural support to accomplish that task.

But somewhere around 1.9 million years ago, something changed in human mating habits. We started pairing off. We started to practice monogamy. Males no longer had to worry so much about competing figures impregnating their female partners, and it was no longer necessary for sex to last more than, say, three minutes.

“We think that is when the human baculum would have disappeared because the mating system changed at that point. This may have been the final nail in the coffin for the already diminished baculum, which was then lost in ancestral humans.

With the reduced competition for mates, you are less likely to need a Bacula. Despite what we might want to think, we are actually one of the species that comes in below the three minute cut-off where these things come in handy.”

So we might have monogamy to thank for the boneless boner.


The baculum (also penis bonepenile bone or os penis) is a bone found in the penis of many placental animals. It is absent in the human penis, but present in the penises of other primates, such as the gorilla and chimpanzee. The bone is located above the male urethra, and it aids sexual reproduction by maintaining sufficient stiffness during sexual penetration. The homologue to the baculum in female mammals is known as the baubellum or os clitoridis, a bone in the clitoris. 


The Occipito Temporal doesn’t get much interest.

The brain bank is the collection of donated brains at Auckland University, a remarkable asset for researchers seeking ways to treat devastating neurological disorders such as Huntington’s disease, Parkinson’s, Alzheimer’s, stroke and motor neurone disease.

No one can predict what parts of the brain will be needed in the future, so they are all stored with great care and respect. NZ Herald