Volcanic ash preserves clues to Mayan staple crop

U. COLORADO (US)—A large manioc field exquisitely preserved under a blanket of ash by a volcanic eruption 1,400 years ago in present-day El Salvador offers new details about cultivation practices of ancient Maya.

Manioc tubers, which can be more than three feet long and as thick as a man’s arm, were a dietary salvation for ancient, indigenous societies in tropical Latin America cities.

Evidence recovered by a research team from the University of Colorado at Boulder shows a manioc field—roughly one-third the size of a football field—was harvested just days before the eruption of the Loma Caldera volcano near San Salvador in roughly A.D. 600, says anthropology professor Payson Sheets, who is directing excavations at the ancient village of Ceren.

The cultivated field was discovered adjacent to Ceren, which was buried under 17 feet of ash and is considered the most well preserved ancient farming village in Latin America.

The ancient planting beds of the carbohydrate-rich manioc tuber—the source of tapioca—are the first and only evidence of an intensive manioc cultivation system at any New World archaeology site, Sheets says, who discovered Ceren in 1978. “This is the first time we have been able to see how ancient Maya grew and harvested manioc.”

Calculations by Sheets indicate the Ceren planting fields would have produced roughly 10 metric tons of manioc annually for the 100 to 200 villagers believed to have lived there. “The question now is what these people in the village were doing with all that manioc that was harvested all at once,” he says. “Even if they were gorging themselves, they could not have consumed that much.”

Ash hollows in the manioc planting beds at Ceren left by decomposed plant material were cast in dental plaster by the team to preserve their shape and size. Evidence shows the field was harvested and then replanted with manioc stalk cuttings just a few days before the volcano’s eruption.

The shape and sizes of individual planting ridges varied widely, the researches found, indicating that individual farmers had some control over their family field “without an external higher authority telling them what to do and how to do it,” Sheets explains.

The team also found that the manioc fields and adjacent cornfields at Ceren were oriented 30 degrees east of magnetic north, the same orientation as the village buildings and the public town center. “The villagers laid out the agricultural fields and the town structures with the same orientation as the nearby river, showing the importance and reverence the Maya had for water,” Sheets says.

Since indigenous peoples in tropical South America use manioc today to brew alcoholic beverages, including beer, the research team plans to test ceramic vessels recovered from various structures at Ceren for traces of manioc.

Ceren’s residents apparently were participating in a spiritual ceremony in the building when the volcano erupted, and did not return to their adobe homes, which excavations showed were void of people and tied shut from the outside. “I think there may have been an emergency evacuation from the ceremonial building when the volcano erupted,” he says. To date, no human remains have been found at Ceren.

The research team also included researchers from the University of Cincinnati, University of Costa Rica, and University of Central Florida. The research was funded by the National Science Foundation. View the team’s 2009 field report.

University of Colorado news: www.colorado.edu/news