By Harold McGee
The most important species of Phaseolus is P. vulgaris, or the common bean. The ancestral plant was a native of southwestern Mexico, and the highest consumption of the common bean is still in Latin America. It first came under cultivation about 7,000 years ago, and gradually diffused both north and south, reaching the major continents about 2,000 years ago, and Europe during the age of exploration. The common bean has been developed into many hundreds of varieties of different sizes, shapes, seed-coat colors and color patterns, shininess, and flavors. Most large-seeded varieties (kidney, cranberry, large red, and white) came originally from the Andes, and became established in the American Northeast, Europe, and Africa; smaller-seeded central American types (pinto, black, small red, and white) were concentrated in the American Southwest. In the United States, there are more than a dozen commercial categories based on color and size. Beans are cooked in many ways: simply boiled, made into stews, soups, pastes, cakes, and sweet desserts.