Drinking carbonated water has been in vogue since at least 1767, and it doesn't seem to be going anywhere. So what gives us our taste for the sparkling stuff?

It's still not completely clear what characterizes the sensation of carbonation. People assume carbonation is the feeling of bubbles popping on the tongue, but when people drink carbonated beverages in a pressure chamber, where bubbles don't burst, they describe it the same way. So it's not purely mechanical.

Chemically, adding CO2 to water creates carbonic acid, which is tasted by sour-sensing taste cells. Research has suggested that a certain enzyme, carbonic anhydrase, sits on those cells and reacts with the acid to cause carbonated water's familiar popping sensation. (Fun fact: climbers who take altitude-sickness drugs that block the enzyme, then drink champagne, report the bubbly as having a dishwater-y taste.) That enzyme, combined with a reaction occurring in the body's trigeminal nerve, could be what gives carbonated water its unique sensation.