Monday, April 4, 2011

Could Hiccups Represent An Evolutionary Reflexive Response to Choking?

I have long wondered about the evolutionary or adaptive value of hiccups. As a child I used to hiccup a lot and they seemed strange and inexplicable. Some recent experiences helped me to see that hiccups may play a role in swallowing. More precisely they may serve to help mammals recover from choking by clearing the esophagus. On several occasions I have had a mouthful of food block my esophageal airway. When this happens with a particularly large mouthful, it can partially occlude the tracheal airway making it hard to breathe. Several times now I have been saved by a hiccup. The hiccup literally squeezed the food down my esophagus and into my stomach.

A hiccup is like a cough in reverse. During a cough the diaphragm expels air from the lungs as the glottis opens. During a hiccup the diaphragm pulls air into the lungs while the glottis is closed and I firmly believe that this can pull food down the esophagus. Most people experience several hiccups in a row usually not coinciding with a meal or with choking. Perhaps these normal hiccups are the body practicing this important reflex. I would be very interested to know how many other people have experienced a hiccup while choking and had their airway cleared because of it.

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:


  1. I am 61 years old and have gotten hiccups from eating hard boiled eggs (most times) as long as I can remember. This also happens sometimes when I eat egg salad or deviled eggs. No other form of egg (scrambled, soft boiled, etc.) causes this reaction.

    I have searched all of the Internet for the reason this happens, only to come up with people (who also have the problem) guessing why it might happen. Most of these guesses have no solid scientific reasoning behind them.

    I might be willing to test your hypothesis.

  2. a piece of advice which work for me each time:

    Take a small bites specially the yellow egg yolks.
    Do not swallow the whole egg yolks, bite it as portion maybe 4 times, mustify and do not swallo quickly. Take your time and if you do this, you notice the hiccups will not happen.

    1. I've tried that and still got the stuck feeling in my throat followed by hiccups.

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  4. I hiccup a few times when I eat hard boiled eggs. Googled it and found this website that others have the same reaction too!

  5. I have the same problem. I think hard boiled egg is very dry and does not go down easily creating a sort of fear to die feeling in the pharynx which is close to the larynx. Also the digestion starts in the month with saliva and chewing. A solution is to eat little bites with warm calming tea after each bite and go slow.

  6. haha...just noticed this happens to ne and decided to google it/
    now if i could figure out why i get an itchy rash on my lower back when eating fruit....i could save a lot of time

  7. Happens to me too guys. Everytime I eat a hard boiled egg.

  8. I am so glad to find I am not alone! I always hiccup when I eat a hard-boiled egg and thought it was just a strange, personal nuance.