Maize ( ; Zea mays subsp. mays, from after ), also known as corn in North American and Australian English, is a cereal grain first domesticated by indigenous peoples in southern Mexico about 10,000 years ago. The leafy stalk of the plant gives rise to inflorescences (or "tassels") which produce pollen and separate ovuliferous inflorescences called ears that when fertilized yield kernels or seeds, which are botanical fruits. The term maize is preferred in formal, scientific, and international usage as the common name because it refers specifically to this one grain whereas corn refers to any principal cereal crop cultivated in a country. For example, in North America and Australia corn is often used for maize, but in England and Wales it can refer to wheat or barley, and in Scotland and Ireland to oats.
Maize has become a staple food in many parts of the world, with the total production of maize surpassing that of wheat or rice. In addition to being consumed directly by humans (often in the form of masa), maize is also used for corn ethanol, animal feed and other maize products, such as corn starch and corn syrup. The six major types of maize are dent corn, flint corn, pod corn, popcorn, flour corn, and sweet corn. Sugar-rich varieties called sweet corn are usually grown for human consumption as kernels, while field corn varieties are used for animal feed, various corn-based human food uses (including grinding into cornmeal or masa, pressing into corn oil, fermentation and distillation into alcoholic beverages like bourbon whiskey), and as feedstocks for the chemical industry. Maize is also used in making ethanol and other biofuels.
Maize is widely cultivated throughout the world, and a greater weight of maize is produced each year than any other grain. In 2021, total world production was . Maize is the most widely grown grain crop throughout the Americas, with grown in the United States alone in 2021. Genetically modified maize made up 85% of the maize planted in the United States in 2009. Subsidies in the United States help to account for its high level of cultivation of maize and its position as the largest producer in the world.
History
Pre-Columbian development
Maize is a cultigen; human intervention is required for it to propagate. Whether or not the kernels fall off the cob on their own is a key piece of evidence used in archaeology to distinguish domesticated maize from its naturally-propagating teosinte ancestor. Genetic evidence can also be used to determine when various lineages split.
Most historians believe maize was domesticated in the Tehuacán 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.
An 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.
Archaeologist Dolores Piperno has said:
Since then, even earlier dates have been published.
According to a genetic study by the Brazilian Agricultural Research Corporation (Embrapa), corn cultivation was introduced in South America from Mexico, in two great waves: the first, more than 6000 years ago, spread through the Andes. Evidence of cultivation in Peru has been found dating to about 6700 years ago. The second wave, about 2000 years ago, through the lowlands of South America.
The earliest maize plants grew only small, corn ears, and only one per plant. In Jackson Spielvogel's view, many centuries of artificial selection (rather than the current view that maize was exploited by interplanting with teosinte) by the indigenous people of the Americas resulted in the development of maize plants capable of growing several ears per plant, which were usually several centimetres/inches long each. The Olmec and Maya cultivated maize in numerous varieties throughout Mesoamerica; they cooked, ground and processed it through nixtamalization. It was believed that beginning about 2500 BC, the crop spread through much of the Americas. Research of the 21st century has established even earlier dates. The region developed a trade network based on surplus and varieties of maize crops.