EUROPE

The seventeenth and eighteenth centuries marked the maximum extension of that episode of glacial expansion we call the Little Ice Age, when growing seasons were shortened by several weeks and altitudes at which crops could grow were reduced. At the same time Europeans, having recovered from the devastation of the Black Plague, were once more increasing in numbers and in need of extra calories. It was at this point that the American foods, whose earlier adoptions had been scattered and spasmodic, began to achieve widespread acceptance.

A good question is why it took Europeans so long to embrace the American crops. They promised more calories and some, like maize and potatoes, had significant advantages over Old World counterparts. Illustrative are potatoes. In that swath from the North Sea to the Ural Mountains, rye, although temperamental in the face of cold winters and rainy summers, was the only Old World grain that did at all well. But potatoes thrived in such a climate – very like their native environment – and could produce some four times more calories per acre than rye. Moreover, potato crops matured in three or four months, whereas rye and other grains required ten months. Potatoes could be planted on fields fallowed for future rye cultivation, and left in the ground to be dug up when needed.