To the ancient Mayans, it was the food of the gods. Nineteenth-century Cubans used it as an aphrodisiac. In the 20th century American culinary authority Fannie Farmer recommended its “stimulating effect” for “cases of enfeebled digestion.” Throughout history people have prized cocoa—the defining ingredient of chocolate—a tradition that endures in our modern era. This Valentine’s Day alone Americans will drop a projected $700 million on chocolate. Around the world people spend more than $90 billion a year on the treat. And with appetite on the rise thanks to expanding population size and growing numbers of people in the developing world who can afford chocolate, demand may outstrip supply in the near future.