Food has functioned both as a source of continuity and as a subject of adaptation in the course of human history. Onions have been a staple of the European diet since the Paleolithic era, while the orange is once again being cultivated in great quantities in Southern China, where it was originally cultivated. Other foods--such as the apple and pear in Central Asia, the tomato in Mexico, the chili pepper in South America, and rice in South Asia--remain...