Erythroxlon coca, a shrub indigenous to the upper jungles of the Andes mountains in South America, has been consumed for millennia by the various Indian tribes that have inhabited the region. The primary alkaloid of this plant, cocaine (first called erythroxyline), earned a reputation throughout the twentieth century as the quintessential American drug. Psychologist Ronald Siegel noted that "its stimulating and pleasure-causing properties reinforce the American character with its initiative, its energy, its restless activity and its boundless optimism." Cocaine—which one scholar called "probably the least understood and most consistently misrep-resented drug in the pharmacopoeia"—symbolizes more than any other illicit drug the twin extremes of decadent indulgence and dire poverty that characterize the excesses of American capitalism. The drug has provoked both wondrous praise and intense moral condemnation for centuries.

For the Yunga and Aymara Indians of South America, the practice of chewing coca...