After nearly a century of research, scientists in Switzerland — of course — have finally discovered why Swiss cheese has holes, and it has nothing to do with hungry mice. Rather, it's tiny flecks of hay that fall into the milk during production that give Swiss cheese its distinctive appearance, according to experts from Agroscope, a governmental agriculture research group.

The Hole Deal

In 1917, American William Clark became the first scientist to systematically study the origin of Swiss cheese's holes, and he published a detailed paper in the Journal of Dairy Science. He concluded that carbon dioxide burps from microscopic bacteria floating in the milk. Still, Clark couldn't provide an exact description of the bubble-forming mechanism, and ever since he published his landmark study, myriad researchers around the world have attempted to pin down the origin of Swiss cheese's holes.