False Economy - Alan Beattie [41]
Apart from the extraordinary advantage of irrigated agriculture, two things helped to make longer-range Egyptian grain trade economic. One was the massive urban concentration in Rome, as we saw in the chapter about cities. Rome's size created a demand for food that any surrounding agricultural breadbasket would be hard-pressed to meet. The second was the Mediterranean itself as a supply network.
Transport by water was much faster and cheaper than by land. In ancient Egyptian script, symbols of ships were used to denote travel. One modern estimate has it that in the Roman empire, transporting a given load one mile by land in an ox cart would cost the same as moving it 5.7 miles by river or 57 miles by sea, meaning that it was more cost-effective to ship grain from a port at one end of the Mediterranean to a port at the other than to haul it by road up the length of the Italian mainland.
To begin with, river transport helped Egypt itself become closer to a single market, bringing grain from the inland provinces more than 400 miles away to the ancient capital of Memphis, near modern-day Cairo. And then it was grain shipped by sea from Egypt and Sicily that enabled ancient Greece and Rome to free themselves from reliance on their own agricultural hinterlands and, particularly in the Greek case, highly unreliable rains. As Aristode observed, "Food comes to the rulers of the seas."
This trade was greatly enhanced when Rome conquered Egypt in 30 b.c. Henceforth it could exact grain as taxes in kind rather than going to the bother of having to find its own exports to pay for them. Indeed, much of the Egyptian trade in grain, within country as well as without, had more to do with forced transfers by a rigid hierarchical society than it did the free exchange of goods in an open market. The very peak appears to have been reached in the first century a.d., in response to a drive to supply Rome with grain. In other words, the height of the Egyptian grain production came not in response to prosperity and freedom for its citizens but colonial exploitation by a controlling foreign power. This is a pattern that recurs.
The Romans spent a great deal of effort to reduce the risks to grain shipments. They more or less stamped out piracy throughout the Mediterranean, and at one point the emperor Claudius indemnified merchants against losses caused by storms. Panic sometimes set in when the grain shipments from North Africa to Rome were delayed, and the New Testament records Saint Paul traveling on an Alexandria grain ship that was wrecked en route off Malta. But in practice ancient Rome suffered remarkably little from food crises, thanks to its supplies from abroad.
Despite the limited ship-building technologies of the time, a reasonably large chunk of the Roman empire's total grain consumption was traded around the Mediterranean. One estimate suggests the empire's agricultural output was about 18 million tons of grain. Perhaps half a million tons was traded freely over medium or long-term distances and more than twice that in shorter journeys. Another 1.8 million tons traveled long-distance after being exacted as taxes in kind. If we count taxes in kind as trade—and even without taking it by force, Rome would still have had to get the grain somehow—that is a substantial amount. In truth, it was remarkable how much was traded at all. Relative luxuries such as olive oil and wine, which could not be produced in all parts of the Greek or Roman empires, were fairly obvious contenders for trade. Grain, being bulkier, heavier, cheaper, and more likely to spoil or be eaten by rats, was another matter.
The infrastructure of long-distance commerce was increasingly impressive. In a.d. 301, the emperor Diocletian declared an edict of costs for transport journeys, which