<P> Maize has become a staple food in many parts of the world, with total production surpassing that of wheat or rice . However, not all of this maize is consumed directly by humans . Some of the maize production is used for corn ethanol, animal feed and other maize products, such as corn starch and corn syrup . The six major types of corn are dent corn, flint corn, pod corn, popcorn, flour corn, and sweet corn . </P> <P> Most historians believe maize was domesticated in the Tehuacan Valley of Mexico . Recent research in the early 21st century has modified this view somewhat; scholars now indicate the adjacent Balsas River Valley of south - central Mexico as the center of domestication . </P> <P> An influential 2002 study by Matsuoka et al. has demonstrated that, rather than the multiple independent domestications model, all maize arose from a single domestication in southern Mexico about 9,000 years ago . The study also demonstrated that the oldest surviving maize types are those of the Mexican highlands . Later, maize spread from this region over the Americas along two major paths . This is consistent with a model based on the archaeological record suggesting that maize diversified in the highlands of Mexico before spreading to the lowlands . </P> <P> Archaeologist Dolores Piperno has said: </P>

Where did maize cultivation begin in the americas