TOBACCO. Now used recreationally throughout the world, tobacco originated in South America as long as eight thousand years ago as a product of two cultivated hybrid species of the genus Nicotiana, N. rustica and N. tabacum. The genus, which belongs to the nightshade or potato family (Solanaceae), occurs naturally in many parts of the world, including North and South America, Australia, some of the South Pacific Islands, and—with but a single species—Africa. The greatest number is native to North and South America, but even with this relative abundance of nicotine-bearing species, only in one small area of the New World, most likely fertile valleys located between Peru and Ecuador, did early food cultivators discover and make use of the extraordinary effects on mind and body of the powerful alkaloid from which the genus derives its name.

More than likely the early experiments with cross-fertilization that resulted...