The researchers determined that damage in the maize granules found at Waynuna was due to grinding and pounding from the outside and not caused by rotting from the inside.
The researchers also found corn remains on tools that were used for grinding and pounding corn to make flour.
There were two different kinds of corn being used at the site, one that was soft enough to be made into flour and another with a harder kernel similar to modern popcorn.
The Waynuna site, they conclude, was a place where corn was both grown and processed more than 2,000 years before the appearance of the great South American empires built on corn cultivationthe Wari, the Tiwanaku, and the Inca (see photos).
Uprooting Conventional Methods
For some experts, though, the arrowroot find is more interesting than the evidence of early corn use.
Richard Burger, a professor of archeology at Yale University in New Haven, Connecticut, who was not involved in the study, said that most scholars have already accepted that corn was cultivated in central and northern Peru around this time.
But, he said, "the identification of arrowroot is in some respects more exciting and unexpected, particularly since it is relevant to models of highland/eastern lowland interaction during the early stages of agriculture."
Arrowroot cannot be cultivated at high altitudes, so the material must have been brought to Waynuna11,800 feet (3,600 meters) above sea levelfrom the Amazonian rain forest to the east.
This means that goods and people must have moved between the eastern lowlands and the Andean highlands, and that arrowroot was a trade commodity well before European contact.
"There is no question that this is an important contribution to the field," Burger said.
The researchers were also praised for their cutting-edge analysis techniques.
Because Waynuna experiences seasonal rainfall, plant material decomposes rapidly on the ground. But Perry's team was able to perform microscopic analyses of starches and silica phytoliths, which are fossilized plant remains.
Jose Iriarte, professor of archaeology at the University of Exeter in England, said that the research was "a welcome expansion in the application of microbotanical techniques to the Central Andean highlands."
"Plants are one of the most important items that people exchanged in the past," Iriarte said.
"And documenting these interactions will prove crucial to unraveling the connections between the eastern tropical forest and the Andean highlands on the brink of complex societies."
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