How the Maya produced enough carbohydrate-rich foods to sustain large cities such as Tikal in Guatemala and Copán in Honduras has long puzzled scientists.
(See an interactive map of the Maya empire.)
Researchers knew that maize, or corn, was a staple of their diet, but corn alone could not have provided enough sustenance.
(Related: "Ancient Chocolate Found in Maya 'Teapot'" [July 17, 2002].)
Experts had theorized that the ancient Maya may have cultivated manioc, which produces large roots, or tubers, that are rich in carbohydrates. But no evidence of manioc crops was known until the recent find.
Sheets and his crew unearthed the new evidence in June while examining an ancient field near Ceren.
The team found that the ancient crop had decomposed but holes in the planting beds had been sealed by ash.
Sheets poured dental plaster into the holes to make molds of what had grown inside. The plaster casts revealed tubers of manioc.
Sheets said the find was "incontrovertible, gorgeous evidence of manioc cultivation."
"I'd like to say that [the discovery] was due to a logical process with geophysical instruments, that it was due to exceptional insight and wisdom on our part," he said.
"But no, it was serendipitous. It was luck."
Where Are the Volcano's Victims?
Despite the lucky find, there are many more questions to be answered, including why no victims of the volcanic explosion have ever been found at Ceren, despite some 30 years of excavations there.
Sheets said the villagers may have been warned that the volcano was about to blow when rising lava turned underground water to steam. When the steam was forced out of cracks in the surface, it could have created a horrifying shriek that sent the Mayans fleeing, he explained.
Perhaps the villagers escaped unharmed, he added, or perhaps they were overtaken by the volcano's fast-moving cloud of ash and gases and their bodies haven't been discovered yet.
Sheets said he hopes these questions will be answered eventually, as continued digs at Ceren work to uncover the site's secrets.
"There's much more than I'll ever do in my lifetime," he said. "There's well over a century of research to be done there."
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