Swine flu is new chapter in US's troubled agricultural history

As Mexico reels from the swine flu panic, there's angry talk of the disastrous impact on that country of North American methods of intensive livestock production. The initial swine flu deaths came near the huge pig factories in the state of Veracruz, owned by Granjas Carroll, a subsidiary of Smithfield Farms, centered in North Carolina and now expanding into eastern Europe.

Intensive pork production in North Carolina in the 1990s sponsored the emergence of the H1N1 swine flu virus in 1998, the year North Carolina's pig population hit 10m, up from 2m just six years earlier. This was achieved by cramming 25 times more pigs into each factory, each one a stinking nightmare to the people living nearby.

David Hamilton Wright, a biologist at the University of Georgia, once wrote that "an alien ecologist observing... earth might conclude that cattle is the dominant species in our biosphere."

The modern livestock economy and the passion for meat have radically altered the look of the planet. Today, across huge swaths of the globe, from Australia to the western plains of the United States, one sees the conquest landscapes of the meat producers and their herds of ungulates.

In a three-week period in May 1806, as Lewis and Clark moved through Montana in the course of their survey, they and their party - the Corps of Discovery - killed 167 animals, about eight a day. Reviewing their entire itinerary, the historian Donald Worster reckons that over 28 months they probably shot - for their needs as opposed to random slaughter - "something between five and ten thousand".

But there was plenty of random slaughter as well. They killed grizzlies, mountain lions, wolves, bobcats, marmots and of course buffalo. They could pick and choose because the western plains displayed a richness of animal life that overwhelmed many travellers.

It is reckoned hunters killed more than four million buffalo in the mid-1870s

By the end of the 1870s, the buffalo was nearly gone. Among the reasons offered by Andrew Isenberg in his excellent 2001 book The Destruction of the Bison, An Environmental History, 1750-1920, were the introduction of the horse to the Indians, courtesy of the Spanish; the introduction of the rifle, particularly the repeating rifle; and the fungibility of buffalo hides as trading currency for the white man’s goods.

Colonel Richard Dodge, himself a keen hunter, reckoned that hunters killed more than four million in the mid-1870s alone: "Where there were myriads of buffalo... There were now myriads of carcasses. The air was foul with sickening stench and the vast plain... was a dead, solitary, putrid desert".

The plains, mountains and valleys which only half a century earlier had been profuse with creatures were now empty in what one traveller along the South Platte called "the uniformity of its cheerless scenery". Of the Great Plains, Barry Lopez has written: "If you count the buffalo for hides and the antelope for backstraps and the passenger pigeons for target practice and the Indian ponies (killed by whites, to keep the Indian poor), it is conceivable that 500 million creatures died."

The cattle came up from Mexico, west through the Appalachians, or from the Florida panhandle. In 1850, with the exception of coastal California and east Texas, there was barely a cow or a steer west of the Mississippi. By 1870 the total was up to 15m and by 1900 that had more than doubled again, to 35m. Texas alone had 6.5m, and Kansas, Iowa and Oklahoma had some 2.5m each on the range or in feedlots. In that half-century, industrial meat-eating came of age.

From the 14th and 15th centuries - when reliable records began to be kept - to the mid-19th century, the European diet varied little. Grains took up about 90 per cent of a family's food budget: rye, buckwheat, oats, barley, maize.

From the moment that the victuallers and provisioners in the Napoleonic wars pioneered mass-production and also modern methods of food preservation, the stage was set for the annihilation of both time and space in matters of food consumption. The vast cattle herds that began to graze the pastures of the western United States, Australia and Argentina signalled the change.

By 1850 the slaughterhouses of Cincinnati - 'Porkopolis' - had been refining the continuous production line for more than 20 years. Frederick Law Olmsted, the landscape and park designer, visited Cincinnati in the 1850s: "We entered an immense low-ceilinged room and followed a vista of dead swine upon their backs, their paws stretching mutely towards heaven. Amazed beyond all expectation at the celerity, we took out our watches and counted 35 seconds, from the moment when one hog touched the table until the next occupied its place. The numbers of blows required I regret we did not count."

Many a 19th century traveller stopped in Cincinnati or, later, Chicago to marvel at the efficiency and heartlessness of this unending,