Final answer:
The staple crop of early Mesoamericans was maize, which was crucial for the development of civilization in that region. Used in conjunction with beans and squash, it formed the Mesoamerican triad, which was a dietary foundation for advanced cultures such as the Olmecs and the Mayans.
Step-by-step explanation:
The staple crop of early Mesoamericans was maize (commonly known as corn in the United States), which was domesticated from a native grass called teosinte around 9,000 years ago in what is now Mexico. Maize cultivation played a crucial role in the development of Mesoamerican civilizations, allowing for the rise of sedentary agricultural communities and the growth of populations. The domestication of maize, along with other staple crops like beans and squash, led to the Mesoamerican triad, which provided a well-rounded diet that was further enhanced through the process of nixtamalization with lime water. This dietary foundation supported the rise of advanced cultures such as the Olmec, Maya, and Aztec civilizations. Additionally, the absence of large domesticable animals in the Americas resulted in unique farming practices, and the role of women in breeding staple crops underlines the gender-specific divisions of labor in these societies.