What archaeological evidence shows that corn was grown in ancient Mexico?

Archaeological evidence for the cultivation of corn in ancient Mexico comes primarily from excavations of dry caves and rock shelters, particularly in the states of Oaxaca and Puebla.12

Key findings include:

• Guilá Naquitz Cave: Located in Oaxaca, this site has yielded the oldest recovered corn cob, which dates to between 6300 and 6000 bp.1
• Tehuacán Valley: Excavations in this region of Puebla have provided substantial evidence of early plant domestication. Between 5000 and 3500 bce, inhabitants were planting mutant forms of corn that already exhibited the husks characteristic of domesticated varieties.2
• San Andrés: Pollen from domesticated corn has been identified at this site in the state of Tabasco, dating to between 7000 and 6000 bp.1

The rarity of early corn in the archaeological record may be due to its initial use for the sugar content in its stalks and leaves rather than its kernels, or because early processing methods—such as grinding with metates—left different types of physical traces.12