New research explains the mysterious hiccup reflex as a burping mechanism allowing young, feeding mammals to consume more milk.

The hiccup has long remained an enigma for clinicians and researchers, who have struggled to connect the physical mechanisms of a hiccup to a plausible evolutionary advantage.

 “We have a lot of explanations for how a hiccup happens, but no one until now has explained why hiccups happen only in mammals, or why they’re so much more frequent in newborns than infants and adults,” says Daniel Howes, author of the study, an associate professor in the Emergency Medicine and Critical Care Program at Queen’s University and the director of the Regional Trauma Program at Kingston General Hospital. “We’re suggesting that hiccupping is actually triggered by the presence of air in the stomach.”

The hiccupping reflex causes a forceful entry of air into the lungs, followed by an abrupt closure of the vocal cords and a loosening of the sphincter above the stomach. The result is a vacuum that pushes air from the stomach into the esophagus.

As for why hiccups continue into adulthood, Howes says the reflex helps to alert us to when we’ve eaten too much.

The results of the study will be published in BioEssays.