Smithsonian magazine has a very nice article by Charles C. Mann, "How the Potato Changed the World", focusing on the effects of the Columbian exchange on Europe.
“For the first time in the history of western Europe, a definitive solution had been found to the food problem,” the Belgian historian Christian Vandenbroeke concluded in the 1970s. By the end of the 18th century, potatoes had become in much of Europe what they were in the Andes—a staple. Roughly 40 percent of the Irish ate no solid food other than potatoes; the figure was between 10 percent and 30 percent in the Netherlands, Belgium, Prussia and perhaps Poland. Routine famine almost disappeared in potato country, a 2,000-mile band that stretched from Ireland in the west to Russia’s Ural Mountains in the east. At long last, the continent could produce its own dinner.
When I toured through the Altai this summer, I was impressed at the healthy potato patch outside nearly every house. How unlikely it seems that this American crop should have become a central part of people's lives in some of the most remote parts of Central Asia.