Isaac is curling against my shoulder, head up to the burp cloth after he has finished a bottle. I want him to burp, and he lets out a few small ones, but then come the hiccups. His little chest spasms and I can feel it against mine. Although I don’t have to smell the milky formula like I do when he’s burping, I hear the little hics that would almost sound cute if they were not so annoying. I’m mostly annoyed for him, that his little body would force him through such a silly routine. The hiccups do not look painful, but because he’s so small they make his entire body move. I want him to breathe and relax, but he can’t until they pass. And of course, of the few self-remedies that may work in adults, Isaac cannot try these himself yet. So I wait for them to stop.
Hiccuping. It’s so weird, like yawning or getting goosebumps. What is up with this stuff? What’s the point of it? Turns out, there really isn’t one–at least not in humans. I sought out Neil Shubin’s book Your Inner Fish to get the scoop on hiccups. The action comes from our shared ancestry with two creatures: fish and tadpoles. On the fish side of things, we share a basic set of nerves that control, among other things, breathing. In fish, the nerves take a somewhat straightforward route to and from where they need to go, without straying far from the brain stem. But as this body plan shifted to suit mammals, the nerves got stretched into inefficient routes and patterns because they have to reach the diaphragm area and back. As movement happens inside our bodies (as might come from eating or drinking), the nerves can be interrupted and a spasm occurs.
As for the tadpoles: these guys are the core causes of hiccups. A tadpole needs to breathe both air and water, depending on which element it exists in at any given time. When gill-breathing, a tadpole needs water to circulate through parts of their body, but the water must be blocked from entering the lungs so as not to drown the creature. Enter the glottis, a flap of skin that can close over the part of the throat with the breathing tube and which allows the magnificent dual-approach lifestyle. Humans have a glottis, because for whatever reason it was not evolutionarily advantageous to lose the glottis over the years. It’s one of those hangers-on, like an appendix or tailbone. (And there may still be a small advantage to the glottis, I’m not positive.)
If, like me, you remember nearly nothing from middle school health class, it’s worth it to read up on some of these bodily origins. It lets you cut people a little slack because we’re all trying to deal with these bodies that are fantastic in many ways, but strained and illogical in others. In The Greatest Show on Earth, Richard Dawkins talks about the human back. What a sad piece of work. It’s because we have had an upright back for only about 1% of our evolutionary history, while almost all other mammals have backs that are built for moving horizontally on four legs. Look at the back of a horse or dog–there’s no great gravitational strain on it, and presumably the muscles are doing a fine job keeping it in place (plus those animals never lift anything…not sure what pulling does to their backs though). Humans, the most erect of the primates, took something horizontal and made it vertical. Can you imagine trying to breed dogs or horses to walk on hind legs over the years? All that strain, not to mention the bending and twisting. Ouch. No wonder our backs fail so many of us. They are good enough to get by, but woefully far from perfect.
One of these spines looks more comfortable than the other. Photo by P. Griès.
Since most parents spend a lot of time staring at their baby, thoughts of body structure our bound to pop up. The fontanelle is a fascinating, disturbing area on the top of a newborn’s skull that I have actually seen pulse from the throb of Isaac’s brain. His skull has not closed and solidified yet, because it needed to be malleable to fit through the vaginal canal. I suggest looking up the National Geographic special Science of Babies (2007) for a great illustration of how a baby’s head turns at various points to fit through the mother’s hips. I had never really understood it before, but seeing the example with a skull going through a skeleton was cool. Women’s bodies are just barely capable of giving birth to a human, who him- or herself is just barely capable of doing the simple tasks it needs to survive, such as suck, swallow, and breathe. All because we have to maintain a huge dome for our brains, without which we wouldn’t be human at all. Our brainpower allows us to procreate despite these difficult births and first years, and then the cycle repeats. It’s a wonder you and I are even here today.
But we are. We are the survivors. Every time you hiccup, or yawn, or sneeze, or slip a disc, or have to give birth, try to remind yourself that you come from a lineage that made it. Through chance genes and the willfulness of your ancestors, you are here today. Everyone alive has to die, but not everyone gets to be alive in the first place. It’s a strange, painful lottery, but we won it.