All hail the uber-tuber

Propitious Esculent: The Potato in World Historyby John Reader315pp, Heinemann, £18.99

There is ordinary food, and then there is the potato: the superfood. It grows at the altitude of Mont Blanc, or at sea level. It survives in the arid lands, it flourishes in the glacial north, it runs wild in the rainforest. Each tuber contains all the vitamins, minerals, proteins, calories and cellulose necessary for life: a healthy adult could survive indefinitely, though perhaps unenthusiastically, on potatoes alone.

The potato can be eaten fresh, or it can be stored over winter. It can be boiled, baked, fried, roasted, grated, mashed or turned into soup. What doesn't get eaten can be dried, frozen, ground into flour or turned into vodka. Old sprouting spuds are clones poised to do what clones do best: replicate. Potatoes trail wheat, rice, and maize in the global staple stakes, but overall are more nourishing and more versatile than any of the grains. Food writers sometimes refer to the simple spud: what could be humble about the uber-tuber? For most of the world, life without the potato would be unthinkable. The mystery is that western civilisation got by without it for so long.

How Solanum tuberosum arrived on the menu at all remains a riddle. In its wild state this relative of the tomato, chilli pepper, tobacco, petunia and deadly nightshade is a dangerous little dish, rich in lethal alkaloids. Yet 8,000 years ago, unknown stone age humans in the high Andes planted it, tended it, selected it for human-friendly mutations, bred it and spread it across a continent. Its arrival in Europe is easier to date, but still guesswork. The vegetable that Columbus encountered in 1492 was the sweet potato, Ipomoea batatas, a different thing altogether. The conquistador Francisco Pizarro probably first saw the potato in 1532. Walter Raleigh could hardly have introduced it to England from Virginia, because the tuber did not then grow in Virginia. It may have arrived in Europe as a medicinal, or an ornamental plant: Fletcher and Shakespeare hint at aphrodisiac properties; John Gerard's Great Herball of 1597 mentions its flowers.

The first convincing reference to the potato as food, however, occurs in the records of the Hospital de la Sangre in Seville: the purchase of 19lb of potatoes in 1573. Since the purchase was made in December, the crop could only have been grown in Spain. Since it would take at least three years to multiply imported seed tubers into a crop, potatoes, perhaps imported via the Canary Islands, must have been grown in Spain since 1570. Wider introduction could hardly have been smooth: Gerard makes reference to a Burgundian belief that potatoes caused leprosy.

By 1642, the potato was a field crop in Holland: within a century it was a peasant food in some of the more fought-over parts of Europe. The same area of land under potatoes could yield four times the calories delivered by grain. Even better, the potato could be left in the ground, which meant that foraging armies were less likely to take everything that farmers had grown. Parmentier, a prisoner of the Prussians during the seven years' war, lived entirely on potatoes for three years, and introduced them to the Parisian court in 1785. The king told him "France will thank you some day for having found bread for the poor."

Populations grew because the potato could buffer them against famine: indirectly, the potato may have fed the industrial revolution. It almost certainly subsidised the population growth that so alarmed Thomas Malthus. With the potato as a crop, four families could survive on land that once supported only one. More food meant more mouths: it also meant more security. It became, in the judgment of one historian, "the definitive solution" to the problem of feeding Europe. By 1841, potato-addicted Ireland was home to more than 8 million people. And then the crop failed, almost everywhere, with terrible suffering and loss of life. By 1961, Ireland's population was still only around 4 million. The potato blight helped alter the course of history, as dramatically as the crop's success had done.

John Reader's salute to Solanum tuberosum has been decades in the making: more than 40 years ago, he watched Irish families in Connemara tend their beds and harvest a crop. In his cracking 1988 study of humans and their environment, Man on Earth, he talked to - and above all listened to - peasant farmers in the high Andes and dairymen in a Swiss canton. In this book he goes back, this time precisely with the potato in mind.

There is a commodity approach to history that follows the human narrative through one product - cod, sugar, salt, clocks, phosphorus and so on. Propitious Esculent is thought-provoking provender from Clio's capacious emporium: history through the eye, so to speak, of the potato. Reader takes care not to make too many claims on behalf of King Edward and Desiree, potage parmentier and gratin dauphinoise, clapshot and freedom fries. Humans choose to act, plants just provide the energy to do so. Even so, a lot rides on the potato, including a mission to Mars two decades from now.

A stand of potatoes large enough to provide an astronaut's nourishment for the day will also, Reader reports, supply all the oxygen that the space traveller needs, and mop up all the exhaled carbon dioxide as well. It won't be the only crop in tomorrow's zero-gravity garden, but it could be the most vital. So the down-to-earth potato has, you might say, a role in the wide blue yonder. Without the potato, most of us wouldn't be here. And without the potato, we won't be going anywhere.