Potatoes were first eaten and cultivated in the Andean highlands of South America, between Bolivia and Peru. Spread to Europe and North America by Spanish explorers, these tubers are ranked second among the world's most staple crops.
As a member of the nightshade family, the edible root, or tuber, of the wild potato plant contains a considerable amount of poisonous alkaloid compounds. Thus, the first step the Andean farmers made toward domesticating and cultivating it was to select specimens with less poison for replanting. In addition to breeding out toxins, the farmers increased the size of the potatoes by choosing plants with larger tubers.