If we are in fact what we eat, it would logically follow that food would hold significant sway over the course of our history. Without access to Egypt's vast stores of grain, the Julio-Claudian emperors and their successors might have failed in currying the Roman public's favor. And moldy bread may have been the reason for the hallucinations and convulsions suffered by the girls whose accusations triggered the Salem witch trials. Here are a few other foods that have left an indelible mark on our world:  

  • Fish. A 2001 study led by Erik Trinkhaus of Washington University in St. Louis, Missouri, revealed that early modern humans living 20,000 to 28,000 years ago in places such as Russia, the Czech Republic, and England relied upon a diet that drew as much as 50 percent of its protein from fish. On the other hand, an analysis of the isotopes in Neanderthal bones dating back 28,000 to 130,000 years ago showed that their dietary protein was largely derived from red meat. Nutritionists hailed this discovery as proof that the omega-3 fatty acids contained in seafood played an important role in human brain development.
  • Chocolate. This ancient Mayan concoction remained a Mesoamerican secret until 1521, when Spanish explorers brought it back to Europe and started mixing it with sugar and honey.  Their culinary experiments became a hit among Europe's elite, and its growing popularity encouraged further conquest in the New World. The antioxidant-rich treat continued to be a luxury item until the nineteenth century, when mass production greatly reduced the manufacturing cost, and it was so prized during the Revolutionary War that it was included in soldiers' rations and sometimes used instead of money to pay their wages. Chocolate bars became a permanent part of an American soldier's kit in 1937.
  • Potatoes. Another Mesoamerican transplant, this item wasn't as enthusiastically greeted as chocolate. At first, it was used to feed livestock and prevent starvation, but even peasants often rejected the oddly shaped food. At the end of the eighteenth century, however, it had gained acceptance among Europe's lower classes, thus introducing a novel concept to the British diet: vegetables. By 1800, the potato, which is an excellent source of potassium, fiber, and vitamin C, had become a staple in Ireland and helped double its population over the next 40 years. But those numbers were reversed when a disease started turning the crop into inedible, black mush-and many who had been solely dependant on the potato for sustenance starved to death. By the end of the Great Potato Famine, some 750,000 Irishmen had died and another 2 million had immigrated to America, England, and Canada.  
  • High fructose corn syrup. Developed by Japanese scientists in the 1960s, this controversial substance started making an appearance in almost every mass-produced food in the early '80s, when rising sugar prices prompted companies to seek a cheaper sweetener. About six years ago, scientists at the Pennington Research Center noticed a correlation between a spike in the U.S. obesity rate and the introduction of high fructose corn syrup. Hence, a villain was born-but whether or not that label is justified is a matter that's still being hotly debated, though recently some experts have suggested that the sweetener is no worse for you than sugar.