I've always wondered about the evolutionary value of hiccups. I used to hiccup a lot and they seemed strange and inexplicable. How might hiccups have helped us?
It happened to me again today. I was eating way too much food, way too fast and I had an uncomfortable feeling in my throat. It is a strong sensation that usually induces a bit of panic. This often happens when I eat something dry without drinking anything. Have you ever eaten a hard-boiled egg first thing in the morning? When this happens I always hiccup, but only a couple of times. The hiccuping tends to push the food down my esophagus, relieving me of the choking feeling. Could most cases of the hiccups represent misfirings of this important, hair-trigger reflex meant to keep our airway clear?
Important reflexes come out sometimes even when they are not needed. At times we salivate despite the fact that we are not about to eat. We often stress out, releasing adrenaline and cortisol despite the fact that we are not about to engage in strenuous physical activity. For a long time now I have concluded that random bouts of hiccuping are triggered accidentally but represent a means to constrict the middle respiratory tract forcing large boluses of food down so that they do not obstruct the trachea. I can think of many ways to test this hypothesis experimentally, anyone want to help?
Here are some of my favorite books that explain how common human traits are actually adaptive biological responses: