Isotopic Evidence for Early Maize Cultivation in New York State

Plants metabolize carbon dioxide photosynthetically either through a 3-carbon (Calvin) or 4-carbon pathway. Most plants are of the C-3 type; C-4 plants are primarily grasses adapted to hot, arid environments. Since C-4 plants have a higher 13 C/ 12 C ratio than C-3 plants, animals and humans with a significant C-4 plant food-intake will have higher 13 C/ 12 C ratios as well. Maize is a C-4 plant, hence maize cultivators living in predominantly C-3 plant environments should show significant isotopic differences from local hunter-gatherers in their skeletal remains; the importance of maize in their diet should also be measurable. The practicability of this method is demonstrated for New York State archaeological materials and wider implications are mentioned.