Maize Domesticated in Mexico

Maize, known in much of the world as corn, was domesticated from a wild grass in southern Mexico, a process generally placed around 9,000 years ago and traditionally dated in broad terms to about 5000 BCE. It became one of the most consequential plants in human history. Maize fed the societies of the Americas for millennia, and today it is among the world's most widely grown crops, used for food, animal feed, and industrial products.

The wild ancestor of maize is teosinte, a grass native to Mexico that looks very little like modern corn. Its seed heads carry only a handful of kernels, each enclosed in a hard casing. Genetic studies have pointed to a teosinte population in the Balsas River valley of southwestern Mexico as the closest living relative of maize. Early inhabitants of the region were mobile foragers who also cultivated some plants, and they likely first valued teosinte for its edible seeds or perhaps for the sugary pith of its stalks, a possibility some researchers have raised.

Domestication was not a single event but a long process of selection. People saved and replanted seed from plants with desirable traits, such as larger ears, more kernels, and softer casings that made the grain easier to eat. Over many generations, changes in a small number of genes helped reshape the plant's branching and the structure of its seed. Archaeological evidence, including starch grains and phytoliths from sites in the Balsas region and cob remains from caves in Oaxaca and Tehuacán, shows maize in use for thousands of years. The earliest cobs were tiny, only a few centimeters long, and the dates for fully developed maize remain debated.

Maize spread widely over the following millennia, moving north into what is now the American Southwest and south into Central and South America. As it traveled, farmers adapted it to different altitudes, climates, and tastes, producing the great variety of landraces known today. Its importance grew as people developed nixtamalization, soaking and cooking the grain with alkaline substances such as lime, which improves its nutritional value and makes it easier to grind into dough.

The consequences were profound. Maize underpinned settled village life and later supported complex societies, including the Maya and the Aztec, in which it held deep religious and cultural meaning. After 1492, it spread across the globe, becoming a staple in Africa, Europe, and Asia. Modern agriculture has made it a leading crop, while its long domestication continues to interest scientists studying how humans reshaped plants.