Corn (Zea mays) was domesticated from Mexican wild grass teosinte 6,300 years ago. Traditionally, archaeologists have studied corn domestication based on the shape of corncobs found at archaeological sites. Ancient DNA technology now allows tracking how and when early farmers selected for other features. Using corn samples from Mexico and the U.S., Viviane Jaenicke-Despres and Svante Pääbo at the Max-Planck Institute, Germany, discovered that, by 4,400 years ago, farmers had considerably reduced corn’s natural genomic diversity. They selected variants for at least three genes influencing plant morphology and starch content in corn kernels.
Did you know? An ear of teosinte bears only five to 12 kernels; but thanks to selective breeding by generations of farmers, one ear of corn now contains more than 500!