i need more sticky notes

I work at a small natural history museum where we receive lots of museum catalogues. Last week, a copy of the 2011 “Bone Clones” product catalog found its way into my hands. Let’s just say that I’ve spent way too much time flipping through it and putting sticky notes on pages that have cool stuff. They've got all different skulls from all different humanoid species. They've got bird skeletons. They've got eggs. They've got reptile and amphibian skeletons. They've got extinct animal bones. I can't even handle it.  I’m going to have to buy more sticky notes.

I love bones. They tell stories- yes, stories in the cheesy “NCIS” forensic way- but they tell more expansive stories too. Bones have been our clearest windows into our evolutionary past. With technology advances, DNA sequencing is becoming the front runner. But bones, I think, will always be the most tangible (and my personal favorite) way to unravel our past’s morphological secrets.

I would like to share with you a few of my favorite human bones- all of which are part of the spine. Our spine is important in that it fostered the major changes in our posture when we became tetrapedal land animals, and then eventually bipedal humans.

Atlas (wikicommons)

The top two vertebrae in your spinal column hold special significance. At the tippy top of the spinal column is your C1 vertebra (first cervical)- known as the atlas. Right below it is the C2 (second cervical) vertebra, called the axis. These two vertebrae are shaped in a way that allows for way more movement than other vertebrae. By articulating against the skull and each other, these two bones allow you to nod and turn your head. Notice how the Atlas has two contoured dips where the skull rests and may articulate, rather than a fused spinal-cerebral junction like you see in fish. (Poor fishies can't nod yes or no, can they?)

Axis (wikicommons)

Way back when we were fishies on our way out of the seas, emerging land animals like Tiktaalik would hide from predators in the shallows. But our fish predecessors were not well-built for air-breathing in the shallows. To make air breathing easier, nose holes migrated to the top of the head and the atlas began to form, allowing it to tip its head up and out of the water. And so, we left the water for drier prospects. As life diverged on land, predatory and prey niches were filled and binocular vision developed, moving eyes to the front of the head and limiting peripheral vision. The Axis stepped in to allow for more side-to-side head movement, allowing for more efficient predation AND predation evasion.

Hyoid (wikicommons)

Not far from your atlas and axis hangs the hyoid bone. The hyoid bone is not the most well known, because it is often missing from skeletons and skeleton drawings. This is because it is unconnected to the rest of the skeleton. It essentially floats in the throat area, suspended only by muscles and ligaments. If you press on the underside of your chin and back a little, that’s about where it is buried. The hyoid bone itself is an evolutionary descendent of a gill arch- a cartilaginous support structure found in the gills of fish. In us, it serves as an anchor for the back of your tongue so you can say words. (On a cheesy NCIS note: the hyoid bone almost never gets broken unless someone tries to strangle you. So fractured hyoid = homicide by strangulation.)

Coccyx (wikicommons)

The coccyx, or the tailbone, is the very last bone in your spine. It’s more of a “bone unit,” actually consisting of several fused vertebrae. Way back in our primate histories, we had tails. As we climbed out of the trees and onto the plains, they disappeared in our current primate lineages. But they left the coccyx remnant- hence the name “tailbone.” Now they’re only good for bruising, breaking, and the occasional vestigial-tailed mutant baby.

If I could choose one art project to work on for the rest of my life, it would be cataloging and illustrating every single vertebra in every major vertebrate family. They themselves are strange little works of art, their contours and projections both beautiful and telling of their function.

But if I don't ever find a life-long job opening for "vertebrae drawer," I'll just name my kids Atlas, Axis, Hyoid, and Coccyx. They'll hate me forever, but man, what cool names they'll have.