Humans have been directing the process of evolution ever since the first crops were domesticated in the Fertile Crescent of the Middle East over 10,000 years ago. By growing plants, then selecting and breeding from those which have useful features such as a high seed yield or disease resistance, we have been able to shape crops to best suit us.
Teosinte is the wild plant from which Maize was domesticated. The two plants have greatly different plant architecture: Teosinte has many long branches on which can be found several ‘ears’ bearing ten grains each, while Maize typically has an erect stem bearing two or three ears with several hundred grains each, making it much easier to harvest. Maize and Teosinte are classed as different subspecies of the same species (Zea mays), but some domesticated crops (including banana and several citrus) are new species bred by humans.