Rhino horns aren't really horns

Last week, I got to visit the Museum of Osteology in Oklahoma City. It's an amazing collection — well worth driving out of your way to see. I was expecting just a selection of different animal skeletons. The actual collection was a lot bigger and more awesome than I'd guessed it would be, and included some really nice exhibits on evolutionary adaptation, convergent evolution, deformed skeletons of both humans and animals, and the process of stripping a body down to a clean and shiny bone structure.

One of the things I found really fascinating was the skeletal features that you can't see just by looking at the outside of an animal. Take this Indian Rhinoceros, for instance. You'll notice that his horn is not a part of the skull. That's because the horn isn't really bone. The "horn" isn't a horn, at all.

Horns are made of bone. They're hard on the outside thanks to a thin layer of keratin — the stuff that makes up your fingernails and hair. But the majority of that material is living bone. Rhinos, on the other hand, have "horns" that are almost 100% keratin. They're really thick bundles of protein fibers.

That's a pretty well-known fact. But it's one thing to know it intellectually, and another thing entirely to see the place where that keratin horn attaches to the animal's actual bone structure. The intricate, lacy network of spongy bone was absolutely fascinating to me. It reminded me of the way ceramic artists will attach one piece of clay to another by scoring little cuts into both pieces and then applying a layer of thin, goopy clay that cements the cuts together as it dries. Seeing the rhino skull really drove home the idea that the "horn" was something else entirely. The horn was attached to the bone. It wasn't part of the bone.


  1. And they grow back if carefully removed.  One of the strategies that is being considered to save the Rhino from poachers is to harvest rhino horns as a sustainable farmed commodity.   Of course the market for them as snake-oil medicine should also be attacked through better education, but in the meantime, it is not necessary to kill rhinos for their horns.

    1. The part I totally don’t get is why they don’t just substitute ground-up cockroach or something?  If the medicine only works by placebo effect, then quality control isn’t of the utmost importance.

    2. We should start the myth that a much more potent version of the rhino horn “medicine” is the dessicated, powdered genitals of someone who has killed a rhino!

      Poachers, beware!

  2. This reminds me of something that happened in the fifth grade.
    The teacher was explaining that rhino horns are not horns, really, but essentially compressed hair. One student asked how that was even possible. The teacher  insisted that it was possible and was indeed true. The student, now in the throes of cognitive dissonance, could only restate that she still just couldn’t see how such a thing was even possible and couldn’t believe it, which began to frustrate the teacher. After this went on for a while longer, it emerged that the student had misheard “compressed hair” as “compressed air”. The tension was broken and hilarity ensued.

    1.  …and from that moment on, all the spam came to address impacted follicles and fingernails; have you looked at your hands lately, they’d say, 4 people have fused mantles you should know about. The mastication of brush is really going to help cut out brushfire, too.

  3. The rhino is my absolute favorite animal. To use their horns to fill the sick market and in turn generate income to pay for their protection might be the only necessary evil that is available to the cause. Because people who think fingernail flakes is gonna rev your sex drive are clearly of the right mind.

  4. San Diego Zoo’s Safari Park has a rhino skull on display, and as you say the horn’s not attached, because it’s really not a horn, more of a large fingernail.  They’ve got several species of rhino in the park – one of the African white rhino species is starting to make a comeback, though all of the black rhinos and Asian rhinos are still in serious trouble.

    (At this point, probably the cheapest way to protect the rhino would be to declare Viagra to be off-patent, and give all the men in China a free package of the stuff, whether they believe in traditional medicine or not…  Only a small percentage of them are contributing to rhino extinction, but the rest can probably find uses for theirs.)

  5. Does rhino horn / keratin fossilise? The conventional answer is “No”. But does anyone know of an example of fossilised horn / keratin?

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