<P> In 1972 Alfred W. Crosby, an American historian at the University of Texas at Austin, published The Columbian Exchange . He published subsequent volumes within the same decade . His primary focus was mapping the biological and cultural transfers that occurred between the Old and New World . He studied the effects of Columbus' voyages between the two . Specifically, the global diffusion of crops, seeds, and plants from the New World back into the Old . His research made a lasting contribution to the way scholars understand the variety of contemporary ecosystems that arose due to these transfers . </P> <P> The term has become popular among historians and journalists, such as Charles C. Mann, whose book 1493 expands and updates Crosby's original research . </P> <P> Several plants native to the Americas have spread around the world, including potato, maize, tomato, and tobacco . Before 1500, potatoes were not grown outside of South America . By the 1840s, Ireland was so dependent on the potato that the proximate cause of the Great Famine was a potato disease . Potatoes eventually became an important staple of the diet in much of Europe, contributing to about 25% of the population growth in Afro - Eurasia between 1700 and 1900 . Many European rulers, including Frederick the Great of Prussia and Catherine the Great of Russia, encouraged the cultivation of the potato . </P> <P> Maize and cassava, introduced by the Portuguese from South America in the 16th century, have replaced sorghum and millet as Africa's most important food crops . 16th - century Spanish colonizers introduced new staple crops to Asia from the Americas, including maize and sweet potatoes, and thereby contributed to population growth in Asia . On a larger scale, the coming of potatoes and maize to the old world "resulted in caloric and nutritional improvements over previously existing staples" throughout the Eurasian landmass as they created more varied and abundant food production . </P>

Where did tomatoes come from in the columbian exchange