The US Corn Belt and European maize owe their existence to a historic change: the ability of this plant, originally from the tropics, to flower early enough to avoid winter. Research led by Cornell University in New York and the Max Planck Institute for Developmental Biology in Tuebingen, Germany reveals that indigenous people in the American southwest started the process of adapting maize to temperate growing seasons 4000 years ago and refined it over the following 2000 years.