The Mechanics of a Hiccup
We don’t all agree yet on why we hiccup, but there are two good answers to this question: the simple mechanical one, and the complex theoretical one.
A hiccup occurs when we have a spasm of the diaphragm, the sheet of muscle below the lungs that partially controls breathing. When the diaphragm spasms, it brings air into your lungs suddenly. At the same time, the epiglottis, a flap of skin in your vocal chords, closes, cutting off the airflow and causing the sound.
Hiccups can be caused by many things, such as a full stomach, which irritates the phrenic nerve that controls the diaphragm. Other irritants of the throat or nerve can cause hiccups.
A Radical Hiccup Theory
The simple mechanics of the hiccup don’t really explain why we get them, though, so scientists have developed a theory that really explains hiccups. In this theory, a hiccup is actually a remnant of our evolutionary past, particularly our amphibian days.
Tadpoles begin breathing water and later become air breathers. About halfway through the process, they have both gills and lungs, and in order to breathe through their gills, they have to fill their mouth with water, then close their glottis before pushing water out through its gills. Primitive amphibians that have gills through their entire life exhibit a similar behavior.
Scientists also note that the signals controlling hiccups come from the most primitive part of our brain, the brain stem, which is largely inherited from our amphibian ancestors.
The only problem with this theory? It’s hard to accept that a function like this might persist through 370 million years of evolution despite having no useful purpose and a significant potential for negative selection pressure. (Imagine small rodent hiding from a Herrerasaurus when it suddenly breaks into hiccups.) To get past this problem, researchers have proposed that the hiccup might have some useful function in helping mammals learn how to suck. This means it may have only had to persist about 150 million years or less, and much less of that time would it be considered maladaptive.
What’s the Right Hiccup Treatment?
Whichever one works! Seriously, there are lots of different ways that people get rid of hiccups. Try many different ones until you find one that works. If you hiccups persist or keep recurring for more than a couple days, you should see a doctor.
If you are looking for a doctor in Littleton, please schedule an appointment with Dr. Andy Fine today.