CALGARY, Alberta, March 26 (UPI) -- A Canadian study suggests corn, the primary food in prehistoric North and Central America, has been part of South American diets for longer than thought.

University of Calgary Professor Scott Raymond and doctoral student Sonia Zarrillo used a new technique for examining ancient cooking pots and found the earliest directly dated examples of domesticated corn being consumed on the South American continent.

Their discovery shows the spread of maize from Mexico more than 9,000 years ago occurred much faster than previously believed and provides evidence that corn was likely a vital food crop for villages in tropical Ecuador at least 5,000 years ago.

"The domestication and dispersal of maize has been a hot topic in archeology for decades and these are the earliest indisputable dates for its presence in South America," Raymond said. "It has long been thought that maize may have been used south of Panama at this time for ritual purposes, but this shows it was also being consumed as food."

The findings are detailed in the online edition of the Proceedings of the National Academy of Sciences.

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