WASHINGTON, D.C.—According to a Science News report, the domestication of the corn plant began in southern Mexico some 9,000 years ago, and continued in Mexico and the southwestern Amazon for several thousand years. It had been previously thought that corn domestication was accomplished in southern Mexico relatively quickly. Logan Kistler of the Smithsonian Institution and his colleagues reconstructed the genetic history of the maize plant by analyzing and comparing the genomes of 108 varieties of modern maize, 11 samples taken from ancient maize remains, and one sample obtained from ancient teosinte, the wild ancestor of the modern maize plant. The study suggests that when the ancestor of modern maize was carried to South America from Mexico more than 6,500 years ago, it still carried many teosinte genes. Kistler suspects farmers in southwestern Amazonia continued the process of domestication by planting the partly domesticated maize with rice and cassava in soil that had been enriched with charcoal, compost, and other ingredients. To read about the ancient nutritional role of corn fungus in what is now Utah, go to “Eat More Spore.”