Popcorn might as well have been invented just for movie-watching--the two just go together. But scientists from the Smithsonian National Museum of Natural History and Washington’s Natural History Museum recently discovered that ancient Peruvians were munching on the stuff way before movies--nearly 7,000 years ago, actually.

The corncobs, husks, and stalks that the researchers found at two mound sites along the northern coast of Peru dated from 4,700 B.C. That makes them the first ever discovered in South America. Details in the microfossils of the cobs indicate to scientists that the sites' ancient inhabitants ate the corn in several ways, including popcorn and flour corn. But it wasn't a major component of their diet, according to the new paper in the Proceedings of the National Academy of Sciences.

"Corn was first domesticated in Mexico nearly 9,000 years ago from a wild grass called teosinte," Dolores Piperno, co-author and curator of New World archaeology at the Smithsonian's National Museum of Natural History, said in a written statement. "Our results show that only a few thousand years later corn arrived in South America where its evolution into different varieties that are now common in the Andean region began."

With the hundreds of maize varieties known today, it's hard for scientists to know exactly how each strain of corn came about and when and where it originated. This is particularly true because corncobs and kernels didn't stay well preserved in the humid tropical forests between Central and South America, including Panama, which is the primary dispersal route for the crop after it first left Mexico over 8,000 years ago.

"Because there is so little data available from other places for this time period, the wealth of morphological information about the cobs and other corn remains at this early date is very important for understanding how corn became the crop we know today," said Piperno.

But popcorn isn't the oldest snack we've found to be eaten by prehistoric humans. Last year, scientists found fossilized plant remains stuck in the teeth of Neanderthal fossils, revealing that our ancestors ate a wide range of grains and plants in addition to meat.

Conveniently for paleobiologists, the mineralization process that forms fossils traps and preserves food particles and bacteria in the oral environment, leaving behind traceable clues of Paleolithic meals.

Who knew that poor dental hygiene could be so helpful?