penis bone

Is There A Penis Bone?

It’s no secret that most people’s sex education was pretty lackluster and uninformative. So it’s not your fault if you’re still wondering about the particularities of some parts of the human body, yes we’re talking about the penis. 

The term boner has to come from somewhere, so the question on many people’s minds is – is there actually a bone in the penis?

First of all, any and all questions about the human body and sexuality are welcomed here. So while this question may seem obvious to some, this is a judgment-free zone. Education equals empowerment so ask away!

All that to say, the answer is no…at least not anymore. Not surprisingly, humans (or at least our evolutionary ancestors) had bones in their penises until about 1.9 million years ago. They’re called homo erectus for a reason! The reason being that they stood up straight on two legs – get your mind out of the gutter.

The penis bone, also known as the baculum, is found all across placental mammals. Rodents, hedgehogs, dogs, bears, sea lions, actual lions, pandas, otters, and many more all have one. 

The baculum can range anywhere from under a millimeter to nearly a meter long and vary in shape from fork-like prongs to needle-like spines. Length isn’t always relative to the size of the animal either, the baculum of the ring-tailed lemur is about a 40th of its body length while the walrus’ baculum is a whopping sixth of its body length!

We see these displayed at The Icelandic Phallological Museum, yes you read that right, it’s a penis museum that houses the world’s largest collection of penises and features things like a Phallic Cafe with penis waffles and a gift shop with hundreds of penis-themed items. 

They also feature a hamster’s 2mm penis bone under a magnifying glass. According to scientists, the range, shape, and general variation of the penis bone make it the most diverse bone to ever exist. Fascinating.

Your Mate, My Mate, Primate

But most tellingly, virtually all primates have a penis bone, including our nearest cousins, chimpanzees, and the other great apes. There are only three primates that don’t – spider monkeys, woolly monkeys, and humans.

This tells us that it’s far more likely that humans, or our ancestors, had one and lost it than that every other primate grew one spontaneously and independently, and we didn’t.

While there isn’t currently fossil evidence that homo erectus had a baculum, there’s enough other evidence to lead scientists to believe that our way-back ancestors likely had them at some point. 

For example, it still occurs sometimes. Just as a rare few are born with vestigial tails, itself a multi-million-year evolutionary throwback, a very, very, very rare few are born with a vestigial penis bone. Similarly, the penis occasionally generates bone when recovering from trauma. So, at least historically, it’s supposed to do that.

So, where did all the penis bones go amongst the general male population? Well, that’s where it gets even more interesting.

The Evolution of Monogamy 

Let’s talk about sex for a moment, this is LELO after all. In nature, it’s very common for sex to last several minutes. This allows the male to remain in place for longer, allowing for a better chance of conception after ejaculation while fending off competition that might kill the female or impregnate her themselves. 

Sex is highly competitive in the animal world, and having a bone in your penis to keep it in place with the urethra open so you can stay mounted on your mate for as long as it takes to ensure contraception is an advantage. It’s so competitive amongst big cats that they don’t just have a bone – they also have hooks or spines on their penises. These spines may also help stimulate females, triggering ovulation. 

Polygamy is by far the dominant reproductive strategy in nature. Males will seek to impregnate as many females as possible, because of a biological urge to pass on their genes. It’s so competitive that female chimps will have sex with many male partners all at once, in order to make the males believe there’s a chance her offspring will be theirs, and therefore reduce the risk of the baby being killed by one of them.

Humans and our ancestors have always done things a bit differently though. Around two million years ago, probably somewhere around the area of Lake Turkana in Kenya, homo erectus had begun to develop social structures much more complex than other primates, and it led to a change in their mating habits.

In short, monogamy replaced polygamy as the dominant reproductive strategy. Homo erectus and its descendants have long gestation periods, which is a by-product of upright walking. Longer pregnancies meant a higher risk of harm to mother and baby, so it made sense for a male human to remain in the presence of his mate to ensure the baby was born safely and defend it until it could defend itself – thereby ensuring his genes were passed on. 

As a result of humans becoming mostly monogamous, there was less pressure to fend off competition during the act of sex itself, and therefore less need to support the penis with a bone while the male stayed in place. So, over a million years or so, the ancient humans lost their boner.

So while our ancestors likely had a penis bone at some point in time, it was phased out with evolution and our ever-changing mating patterns.