Hiccups 'a throwback to gill-breathing ancestors'
Hiccups could be a reminder that our ancient ancestors had gills.
The sudden contractions of the muscles used for breathing in serve no purpose in adult humans.
The only group of animals which would need it are primitive air breathers like lungfish and other amphibians that still possess gills.
New Scientist magazine says these creatures push water across their gills by squeezing their mouth cavity while closing the glottis to stop water getting into their lungs.
A group of scientists led by Christian Straus, at Pitie-Saltpetriere Hospital in Paris believes the brain circuitry controlling gill ventilation has persisted into modern mammals.
The researchers point to many similarities between hiccuping and gill ventilation in animals such as tadpoles.
Both are inhibited when the lungs are inflated, for example, and by high carbon dioxide levels in air or water.
Straus and his colleagues suspect the habit persists because it helps mammals learn to suckle.
Story filed: 19:13 Wednesday 5th February 2003