Frequently Asked Questions - When was maize domesticated?
- Where was maize domesticated?
- What was maize domesticated from?
- What role does Tripsacum play in maize domestication?
- What is teosinte?
When was maize domesticated? Maize was likely domesticated between 7,500 and 12,000 years ago. Archaeological remains of the earliest maize cob, found at Guila Naquitz Cave in the Oaxaca Valley of Mexico, date back roughly 6,250 years, while good evidence of people inhabiting North and South America comes from Mesa Verde and dates to 12,500 years before present. Given that the transformation from wild grass to cultivated crop likely occurred over a period of a few thousand years in south central Mexico, this sets the timeline for maize domestication between 7,500 and 12,000 BP. As new archaeological evidence is discovered, this date may be refined in the future.
Where was maize domesticated? South central Mexico. Based on current research, Zea mays ssp. parviglumis is the immediate ancestor of maize. The principal habitat of Zea mays ssp. parviglumis is restricted to south central Mexico, so the initial steps of domestication most likely occurred within or near the present range of Zea mays ssp. parviglumis. Later steps of domestication and improvement, however, might have occurred elsewhere. There is some evidence that major dispersals of maize races came out of South America. It is quite possible some key traits were modified in South America, but further research will be required to explore this possibility.
What was maize domesticated from? Teosinte, specifically Zea mays ssp. parviglumis. All molecular evidence indicates that maize is closely allied with Zea mays ssp. parviglumis. Genetic studies suggest that as few as five genes could be responsible for the major morphological differences between Zea mays ssp. parviglumis and maize. Many additional genes, however, may have helped to complete the transformation, including those involved in increasing ear size, adapting maize to modern agricultural fields, and modifying the nutrient content of the maize kernel.
What role did Tripsacum play in maize domestication? No role. In the late 1930s, Paul Mangelsdorf suggested that domesticated maize was the result of a hybridization event between an unknown wild maize and Tripsacum. His "Tripartite Hypothesis" dominated much of the genetics literature between the 1930s and 1960s, and still persists in the archaeological literature today. An alternative hypothesis suggests that maize is simply a domesticated form of teosinte, Zea mays. Careful phenotypic studies and genetic analyses have shown that maize is closely related to Zea mays ssp. parviglumis. In addition, even after surveying close to 50 molecular markers in maize, teosinte, and Tripsacum, no evidence of Tripsacum genes has been found in maize.
What is teosinte? Teosintes are the wild members of the genus Zea. Maize (Z. mays ssp. mays) is the only member of Zea that is not a teosinte. Read Taxonomy and Distribution for more information.
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