Animals With a Penis Bone (And Why Humans Lost It)

These Animals Have Penis Bones—So Why Did Humans Lose Theirs?

Here’s a wild sex fact you probably didn’t learn in school: many animals have a penis bone. It’s called a baculum, and it comes in all shapes and sizes. From bats with dagger-like structures to walruses with bones longer than your forearm, the animal kingdom isn’t shy when it comes to hard facts. But here’s the kicker—humans don’t have one. So why did we lose it?

What is the baculum, exactly?

The baculum is a bone found in the penis of many mammals. It helps support the shaft during intercourse, especially when quick or multiple matings are necessary. Think of it as biological reinforcement. You’ll find it in primates, rodents, carnivores—and even seals.

Which animals have the biggest penis bones?

– Walruses: Their baculum can reach up to 24 inches long.
– Bats: Some have thin, sharp bacula used during penetration.
– Otters: Small but mighty, theirs aid in prolonged mating sessions.
– Raccoons, dogs, and chimpanzees: Yep, all carry the bone.
– Even fossilized bacula have been found, dating back millions of years.

Also worth reading: Curved Penis and Growers vs Showers.

Wait… do monkeys have penis bones?

Yes, but here’s the twist: not all primates do. Our closest relatives like chimpanzees and bonobos still have bacula, but it’s thinner and more fragile. That makes our total lack of it even more intriguing.

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So why did humans lose the baculum?

There are a few theories. One says it’s tied to monogamy—humans evolved toward longer, more intimate pair bonding, making constant quick matings less essential. Another theory connects it to trust: without a bone, an erection requires full arousal and blood flow. No faking it.

The trust theory is kind of romantic, right?

In a way, yeah. Without a baculum, erections become a sign of genuine interest, mental arousal, and emotional connection. It’s not just about biology—it’s about timing, readiness, and desire. Your erection is earned, not automatic.

Penis bones come in strange shapes

The baculum isn’t just a straight rod—it varies wildly between species. Some are forked, others curved. In some species, the shape helps lock the penis in place during mating. In bats, the baculum can look like a dagger. In minks, it’s curved like a hook. Nature doesn’t hold back.

What happens when an animal doesn’t have one?

In species without a baculum (like humans), erections rely purely on blood flow and vascular pressure. That means we’re more vulnerable to performance issues—poor circulation, stress, or fatigue can ruin the mood. But on the flip side, it also means stronger selection for overall health and arousal.

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Is there an evolutionary advantage to losing it?

Possibly. Scientists think humans may have ditched the bone as we evolved more stable pair bonds and focused more on emotional intimacy and long-term parenting. It also means the ability to get and maintain an erection became a health signal—if you can’t get hard, something’s off.

Does size matter in animals?

In some species, yes. For example, larger bacula may help males win in sperm competition. In others, it’s more about shape and mating style. In species that mate quickly and often, like rodents, the baculum is crucial for speed and stability. In whales? They don’t need a baculum—they just have massive blood flow.

Fun fact: You can buy a walrus penis bone

Yes, really. In Alaska and parts of Canada, native cultures have used fossilized or preserved walrus bacula—called “oosiks”—as tools, walking sticks, or even art. Some collectors treat them like rare relics of evolutionary oddity.

Penis bones and mating style

Species that engage in quick, frequent mating sessions tend to have bacula. Those with longer, more selective mating rituals (like humans and some apes) rely on blood pressure alone. That makes the penis bone a kind of evolutionary shortcut—a biological cheat code for survival sex.

How humans compensate for not having one

Since we don’t have a baculum, human males rely on strong pelvic muscles, proper blood flow, and mental arousal. That’s why things like exercise, diet, and stress reduction can make or break your performance. At supremepenis.com, we break down how to boost these naturally.

Do women notice the difference?

Honestly? Most don’t even know bacula exist. But one thing is clear—humans evolved to focus more on intimacy, rhythm, and technique. So it’s less about having a bone and more about knowing how to use what you’ve got.

Why this matters for men today

Understanding your body—how it evolved, what it lacks, and what it compensates for—gives you power. The penis bone is just one bizarre chapter in the story of masculinity. The real strength is how you adapt, connect, and perform without it.

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While you don’t have a baculum, you’ve got something better: the ability to upgrade blood flow, stamina, and size through smart, natural training. At supremepenis.com, we’ll show you how to do it safely and effectively—no gimmicks, no bones about it.

Can penis bones break?

Yes—and no. In animals that have bacula, the bone can fracture under extreme force, though it’s rare. In humans, we talk about “penile fracture,” but it’s not bone—it’s tearing of the tunica albuginea, the sheath that surrounds erectile tissue. Still painful. Still serious. Just not a literal bone break.

Are there animals without a penis?

Sure are. Birds, for example, generally lack penises altogether. They reproduce via a “cloacal kiss”—a quick touch between openings. But ducks? They break the rule with giant corkscrew-shaped penises that defy logic and probably physics.

Does having a penis bone make mating easier?

In some ways, yes. It allows animals to mate quickly without needing to be fully aroused. That’s useful when you’re trying not to get eaten or interrupted. But it also means less control and sensation. Humans may have lost the bone—but we gained finesse.

Penis bones in fossils?

Yep. Paleontologists have found bacula in fossils going back millions of years. It’s one of the few genital structures that fossilizes well, giving scientists a glimpse into how extinct animals got down. Evolution has receipts.

Own your biology—even without the bone

You might not have a baculum, but you have something better: choice. You can train, improve, and master your sexual health. Learn exactly how to enhance blood flow, stamina, and size naturally at supremepenis.com—your evolution continues.