Hiccups are one of those annoying things our bodies do that serve absolutely no purpose. We do not have to hiccup, but according to Dr. Michael Mosley it is something we have left over from evolving from fish.
In fish, the nerves responsible for breathing only need to make a short journey from the brainstem to the throat and gills. In humans, through evolution, it has become a much more complex route.
For us to breathe properly the brainstem has to send messages to the throat, but also all the way down to the chest and the diaphragm. Because of this increased complexity, the nerves are prone to spasm which can start a hiccup.
Once started, the hiccups are kept going by a simple motor reflex which, according to Mosley, we inherited from an amphibian ancestor. He reckons this served a purpose for the ancient tadpole because it allowed the entrance to the lungs to remain open when breathing air, but shut when gulping water – allowing it to be directed to the gills.
Hiccups therefore have no value for humans or other mammals, but according to Dr. Mosley it does provide evidence of our common ancestry.
