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9 Fascinating Things You May Not Know About the Penis

There’s all kinds of interesting facts and facets to the human penis. Here's your chance to learn more.

“Isn’t it awfully good to have a penis,” Eric Idle mused in   the greatest 35-second song ever written and I believe he’s telling the truth: having a stiffy is probably spiffy. Erections are such hopeful things, like carrying a little optimist around in your pocket, one imagines.

The penis provides lots of pleasure and keeps the human race going in its capacity as a reproductive organ. There’s all kinds of interesting facts and facets to the human penis and there are some in the animal world that could easily have been designed by Dali. Now’s your chance to get to know them a little better. 

1. Spiny Norman no more.

Evolution has discarded many parts of the human penis, including ... its spines?

Penile spines are little tiny ridges made of a hard tissue called keratin, and line the outside of the penis. They look (I think) a bit like those punk-inspired accessories that are so popular these days. Lots of animals, including the chimpanzees, still have penis spikes.  Christine Dell-Amore of National Geographic News writes that the human genome project gave us the information that the ancestor we share with the chimps also had the spines.

But that was so six million years ago. The code for the “penile spine enhancer” was deleted from the human androgen receptor gene, says  Nature (androgens are male sex hormones) and Dell-Amore reports that it happened “before our common ancestor split into modern humans and Neanderthals about 700,000 years ago." Quite a few deletions were discovered -- 510, if you please -- and gave us other spiffy changes like having bigger brains and not having whiskers.

It’s not yet certain just what the spines are for, though  there are theories, Jen Quaraishi reports in Mother Jones like a correlation between spines and greater promiscuity, also that they make for faster copulation time. If you want to see what they look like, here’s a picture of a cat penis on a blog called Sand Walk.

2. How the human lost his bone, er, baculum.

Another thing the human penis lost along the way -- gosh, is it forgetful or what? -- was its baculum, or penis bone. Some animals have what’s called an os penis, one containing a bone which keeps them rigid long enough to deliver sperm into the female’s reproductive tract. Most primates have one, but human males rely solely on blood pressure or hemodynamics for rigidity. Lauren Reid of Science Alert writes that the baculum is usually stored in the animal’s abdomen until needed, when abdominal muscles push it out. One of its good qualities is speed: it’s more reliable than waiting for blood flow to work and allows for quick copulation. 

In The Selfish Gene, evolutionary biologist Richard Dawkins describes the os penis as clearly being an easier way to maintain an erection. He theorizes that the reason we lost such a helpful trait is that hemodynamics allow females to better gauge male sexual health when choosing a partner. From diabetes to depression, there are numerous health factors that can cause erectile trouble and “females could glean all kinds of clues about a male’s health and the robustness of his ability to cope with stress, from the tone and bearing of his penis,” clues a bone would obfuscate because “anybody can grow a bone in the penis; you don’t have to be particularly healthy or tough.”

Another charming tidbit from Reid: “There is also a female version of the baculum in some species which has a rather lovely name – the “baubellum," or “os clitoris."

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