Even though they're extremely common, hiccups are one of the most mysterious bodily reflexes.
Now, a Canadian researcher has proposed a novel explanation: Hiccups help release air from the stomach, which allows babies to intake more milk.
The theory, published Tuesday in the journal BioEssays, suggests the vacuum created in the chest from hiccupping actually pulls air out of the stomach, similar to the burping reflex.
Daniel Howes, a physician at Kingston General Hospital and associate professor in emergency medicine and critical care at Queen's University, writes that hiccupping may be a mechanism designed to help humans and other mammals consume more milk. This explanation would also help explain why infants tend to hiccup much more often than adults.
"The hiccupping reflex causes the muscles used for breathing to sharply contract. This is followed by a sudden closure of the vocal cords, making the classic 'hic' sound." Dr. Howes' hypothesis is that the vacuum created in the chest by the hiccup pulls air out of the stomach.
He became interested in the subject of hiccups when he realized that no one actually knows what causes them. Dr. Howes came up with the idea that hiccups may be similar to a burping mechanism, but didn't understand what survival instinct would have made the reflex evolve. However, when he was up late feeding his infant daughter one night, it dawned on him that hiccups can make room in the stomach, allowing babies to take in more food.
There is no hard proof to support the theory, but Dr. Howes' article states that this could stimulate further discussion and a deeper look into the reasons behind hiccups.
"There's not really any way to prove these kinds of things," Dr. Howes said. "That's the whole idea of putting it out there."
Of course, this isn't the first hypothesis about the origin of hiccupping. For instance, some researchers have suggested that fetuses use hiccups in the womb for respiration, while others suggest that they may be a leftover from ancient ancestors who lived in the water.