Hiccups are one of the great mysteries of human biology. Scientists understand how they happen, but have basically no clue why they happen. In the short TED-Ed video above, educator John Cameron explains exactly what’s going on in your body when you find yourself with an annoying case of the hiccups, and summarizes a few theories regarding the strange, seemingly pointless phenomenon’s origins.

Cameron explains that the hiccups are caused when your diaphragm contracts—initiating an intake of air—while, at the same time, your vocal cords close, stopping the air from getting to your lungs. The closure of your vocal cords is, according to Cameron, what’s causing that annoying hiccup sound. Cameron also notes that scientists have diverging theories on why humans hiccup: Some believe it helps nursing babies keep milk out of their lungs, while others think hiccups got their start millions of years ago, before animals even made the transition from water to land. Whatever the cause, Cameron makes one thing very clear: There’s still no known cure.

[h/t AV Club]

Banner Image Credit: TED-Ed, YouTube