Sunday, 8 May 2011

WHY DO WE HICCUP


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An American called Charles Osborne has the dubious honour of holding a record for the longest recorded bout of hiccups - 68 years worth in fact - from 1922 to 1990. But what is it that causes us to hiccup? Well, it seems to be partly down to us having fish as our very early ancestors.

A hiccup is caused by a spasm of the diaphragm - the big muscle in the chest that enables you to breath - followed by an involuntary gulp. Both these actions have origins in our watery past.

In fish the nerves that activate breathing take a short journey from an ancient part of the brain, the brain stem, to the throat and gills. In us, it is more complicated.

To breathe properly, our brain stem has to send messages not just to the throat, but down to the chest and diaphragm. This complex arrangement means that the nerves are prone to spasm, which can initiate hiccups.

Once a hiccup has started, it is kept going by a simple motor reflex that we seem to have inherited from an amphibian ancestor.

For the ancient tadpole, the nerve controlling this reflex served a useful purpose, allowing the entrance to the lung to remain open when breathing air but closing it off when gulping water - which would then be directed only to the gills.

For humans and other mammals who hiccup, it has no value but does provide another bit of evidence of our common ancestry.

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Based on an article by Dr Michael Mosley
Picture by way of lonewolffx.com and Smeonethinkingthoughts
Posted by Simon Eade at 22:52
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1 comments:

karenandjeff said...

Very interesting tidbit! I love learning about the origin of our species. If you haven't heard the saying, "ontogeny recapitulates phylogeny" you should look that one up.

9 May 2011 20:05

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