People in what is now Peru were eating popcorn as early as 6,700 years ago, according to researchers. Telltale traces of their snacking habits—ancient cobs, husks, stalks and tassels—were recently unearthed at Paredones and Huaca Prieta, two coastal sites that were once home to prehistoric settlements. A study based on the find appeared this week in the Proceedings of the National Academy of Sciences.

After examining the cobs, the researchers determined that the Peruvian sites’ ancient occupants didn’t only pop their corn: they also ground it into flour and may have cooked it in other ways as well. At this early stage of maize’s history, however, it didn’t represent a major component of their diet. This would change by the 12th century, when maize cultivation became vital to the Inca Empire’s rise and subsequent expansion across Peru.

Corn was first domesticated from a wild grass in Mexico nearly 9,000 years ago, according to study co-author Dolores Piperno, a curator at the Smithsonian’s National Museum of Natural History. It then made its way across Central and South America, where hundreds of distinct maize types—including the ancestors of sweet corn, which many people eat today—arose. The cobs and other corn scraps found at Paredones and Huaca Prieta indicate a diversity of kernel shapes and colors, a sign that this process was already in full swing.

“Our results show that only a few thousand years [after its domestication] corn arrived in South America where its evolution into different varieties that are now common in the Andean region began,” Piperno said. “This evidence further indicates that in many areas corn arrived before pots did and that early experimentation with corn as a food was not dependent on the presence of pottery.”

The discovery described in the study suggests that popcorn came about 1,000 years earlier than previously thought. It also represents a rare example of early maize remains; since the humid tropics between Central and South America are not conducive to the grain’s preservation, much of what we know about corn evolution comes from microscopic remnants. “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,” Piperno explained.

How did popcorn’s earliest addicts prepare the crunchy treat in a world without microwaves, stovetops or artificial butter? Since they didn’t even have ceramic pots at their disposal back then, chances are they roasted the cobs directly over coals or flames. Later inhabitants of Peru’s northern coast would perfect the technique by developing the world’s oldest known popper—a shallow vessel with a handle and a hole on top—around 300 A.D. The first popcorn machine made its debut 1,500 years later at the 1893 Chicago World’s Fair.