Hail the humble potato, which fueled global trade

It is the world's fourth-most-important food crop, after corn, wheat and rice. It provides more calories, more quickly, using less land and in a wider range of climates than any other plant. It is, of course, the potato.

The United Nations has declared 2008 the International Year of the Potato. It hopes that greater awareness of the merits of potatoes will contribute to the achievement of its Millennium Development Goals, by helping to alleviate poverty, improve food security and promote economic development.

It is always the international year of this or month of that. But the potato's unusual history means it is well worth celebrating because the potato is intertwined with economic development, trade liberalization and globalization.

Unlikely though it may seem, the potato promoted economic development by underpinning the industrial revolution in England in the 19th century. It provided a cheap source of calories and was easy to cultivate, liberating workers from the land.

Potatoes became popular in the north of England, where people specialized in livestock farming and domestic industry, while farmers in the south (where the soil was more suitable) concentrated on wheat production.

By a happy accident, this concentrated industrial activity in the regions where coal was readily available, and a potato-driven population boom provided ample workers for the new factories. Friedrich Engels even declared that the potato was the equal of iron for its "historically revolutionary role."

Free-trade tuber

Landowners supported the laws, because cheap imported grain would reduce their income, but industrialists opposed them because imports would drive down the cost of food, allowing people to spend more on manufactured goods.

Ultimately, it was not the eloquence of the arguments against the Corn Laws that led to their abolition -- and more's the pity. It was the tragedy of the Irish potato famine of 1845, in which 1 million Irish perished when the crop on which they subsisted succumbed to blight.

The need to import grain to relieve the situation in Ireland forced the government, dominated by landowners who backed the Corn Laws, to reverse its position.

That paved the way for liberalization in other areas, and free trade became British policy. As the Duke of Wellington complained at the time, "rotten potatoes have done it all."

In the form of French fries, served with burgers and Coca-Cola, potatoes have become an icon of globalization. This is quite a turnaround, given the skepticism that greeted them on their arrival in the Old World in the 16th century.

As Adam Smith, one of the potato's many admirers, observed at the time, "The very general use which is made of potatoes in these kingdoms as food for man is a convincing proof that the prejudices of a nation, with regard to diet, however deeply rooted, are by no means unconquerable."