How the Potato Changed the World's History

Social Research, Spring, 1999 by William H. Mcneill

Yet in the course of the eighteenth century, potatoes broke through garden fences and became a field crop, supplementing and eventually also competing with grain. This permitted potatoes to exercise a new, important influence on European demography by enlarging the food supply, thus inaugurating a second era when the tubers began to affect world history in a significant way.

The enhanced importance of potatoes came about in two quite different ways. On the Continent government officials and noble landowners actively forwarded rapid conversion of fallow into potato fields after 1750, whereas in Ireland initiative in expanding potato cultivation rested entirely with landless laborers, renting tiny plots from landowners who were interested only in raising cattle or (after about 1750) in producing grain for market.

Ireland's unique path to dependence on potatoes derived from the failure of English plans to displace the Catholic Irish with a Protestant yeomanry by settling Cromwell's veterans on land confiscated from the defeated Irish. This policy was modeled on an earlier and smaller land transfer that had established Scots Presbyterian farmers in Ulster after 1611. Since natural conditions in Ulster were not very different from those of the Scottish lowlands, the Ulster settlement soon took root and prospered. But forty one years later Cromwell's veterans quickly discovered that the style of grain farming with which they were familiar in England was impractical in Ireland since in most years excessive moisture and coolness prevented wheat and barley from ripening. (Scots by contrast relied on oats, a crop that usually ripened well enough, even in cool, moist Ireland.) Cattle grazing was the traditional alternative upon which the native Irish had long relied, and when English settlers' initial attempts at grain farming failed, a few land speculators bought out almost all of Cromwell's veterans, many of whom were not eager to farm for themselves anyway. The new landowners were solely interested in making money, and found they could best do so by becoming commercial graziers, sending cattle for slaughter to Dublin or Cork and so supplying the Royal Navy and the English merchant marine with cheap salt beef.

Commercial graziers needed a few laborers to work on their new estates. They quickly discovered that Englishmen, whose staple food was bread and cheese, required far higher wages than the native Irish, who were skilled herdsmen from time immemorial, and had recently learned to live on a far cheaper diet of potatoes and milk. That diet was new, for when Cromwell's soldiers herded the dispossessed Irish into Connaught in 1652, potato gardens and milking cattle were what allowed many (perhaps most) of them to survive even on comparatively very small patches of land.

In fact, a single acre of potatoes and the milk of a single cow turned out to be enough to feed a whole family; and such a diet, however monotonous, was nutritionally adequate to sustain what became an exceptionally healthy, vigorous (and desperately poor) rural population. It also became common for even the poorest Irish family to grow enough extra potatoes to feed a pig whose sale could supplement wages and help pay for rent, clothes and other essentials. Since potatoes and cows' milk were just as good a diet for pigs as for humans, subsistence on amazingly small potato patches sufficed to keep the Irish alive, first in Connaught and by 1780 or so, also allowed them to displace English settlers from nearly all the rest of the island. The Scots, however, remained firmly ensconced in Ulster, supplementing their oats with potatoes after crop failure in 1718-20 showed them how valuable the new food could be.