Some scientists have proposed a theory that hiccups are produced by “brain circuitry” left over from that used by air breathers that also have gills.

In the latest issue of BioEssays (vol 25, p 182), a team led by Straus proposes that the brain circuitry controlling gill ventilation in these early ancestors has persisted into modern mammals.

There are many similarities between hiccuping and gill ventilation in animals like tadpoles, the researchers argue. Both are inhibited when the lungs are inflated, for example, and by high carbon dioxide levels in air or water.

Of course this is just a theory and it will be difficult to prove.  But it’s intriguing, nonetheless.