Ancient maize, the progenitor of modern corn, underwent a significant transformation from a wild grass into a staple crop. This development sustained societies across the Americas for millennia, allowing for settled communities, the rise of complex cultures, and the shaping of ancient economies.
From Wild Grass to Cultivated Crop
The journey of maize began in Mesoamerica, within the Central Balsas River Valley of Mexico. Here, around 9,000 years ago, ancient peoples began cultivating a wild grass called teosinte ( Zea mays subspecies parviglumis ). Unlike modern corn, teosinte produced small ears with only 5 to 12 kernels, each encased in a hard shell.
Over thousands of years, through careful selection and cultivation by early farmers, teosinte underwent significant genetic changes. These changes led to the development of larger cobs with more numerous, exposed kernels, eventually transforming it into what we recognize as ancient maize. Archaeological evidence, such as 8,700-year-old maize starch grains and phytoliths, confirms the Balsas Valley as the cradle of maize domestication.
Ancient Maize Across the Americas
Once domesticated in the Balsas River Valley, ancient maize began its extensive journey across the Americas. It spread from its origin point, reaching lowland Central America by 7,600 years ago and the valleys of the Colombian Andes between 7,000 and 6,000 years ago. Maize arrived in highland Ecuador at least 8,000 years ago and continued its dispersal, eventually reaching as far south as Chile.
To the north, maize was cultivated in New Mexico and Arizona approximately 4,100 years ago. Its journey into eastern North America occurred later, with widespread adoption of maize agriculture and consumption taking place around 900 CE. This dispersal was facilitated by human migration and trade networks, allowing maize to adapt to diverse environments and leading to the development of numerous ancient varieties, or landraces.
Life with Ancient Maize
Early ancient maize cobs were significantly smaller than modern corn, often less than 0.8 inches (2 cm) long, and typically had about eight rows of kernels, which is roughly half the number found on modern cobs. Ancient peoples developed sophisticated agricultural practices to cultivate this crop. In Mesoamerica and North America, Indigenous groups often interplanted maize with squash and beans in a system known as milpa, or the Three Sisters, which provided a balanced agricultural system.
Maize quickly became a foundational element of ancient American civilizations, serving as a primary dietary staple. Its nutritional value, ease of storage, and adaptability to various growing conditions made it a reliable food source. Beyond sustenance, ancient maize held deep cultural and spiritual significance, appearing in the myths, art, and ceremonies of groups like the Olmec, Maya, and Aztec. For example, Mayan legends describe humans being created from maize, and depictions of maize gods were common in their iconography.
Unearthing Ancient Maize’s Story
Scientists piece together the history of ancient maize using a combination of archaeological and genetic methods. Archaeological excavations uncover physical evidence, such as ancient cobs, pollen, and microscopic plant remains called phytoliths, which reveal the presence and use of maize at various sites. Tools used for grinding and milling these plants also provide clues about early processing techniques.
Genetic analysis, particularly DNA sequencing from ancient maize samples, offers detailed insights into its evolutionary journey. By reconstructing the genomes of ancient cobs and kernels, researchers can trace the lineage of maize, identify genetic changes associated with domestication, and map its dispersal routes. These techniques allow scientists to understand how ancient farmers selected for specific traits, such as starch characteristics that influenced texture and taste, revealing their skilled agricultural practices.