AIDS and its threat to mankind, especially in africa, naturally provokes a quest for a silver lining, not of course to be confused with a moral justification for such misery. For those who can stomach it, the legacy of the Black Death, which killed 30 million Europeans during the 14th century, provides, not consolation (how could there be?), but a lesson in how human tragedy can sometimes pave the way for a triumph of sorts.
Between 1346 and 1351 about a third of Europe's population was wiped out by an epidemic of bubonic plague that arrived from Asia via the Crimea. The immediate impact was catastrophic. Agricultural production and commercial life were devastated, especially in the economic heartlands around the north-south axis from Italy to the Low Countries and East Anglia. Total production and trade were lower in 1400 than they had been a century earlier and it took roughly 200 years for Europe's population to regain its 1340 level.
But in the medium term the main consequence of the plague — discernible with hindsight — was to upset the traditional balance between laborer and landowner. By devastating the peasantry, the Black Death eliminated a surplus of labor and reversed what had been an incipient Malthusian crisis. With demand for labor outstripping supply, the peasantry became more assertive — hence the rural conflicts of the time including England's Peasants' Revolt of 1381 and the Jacquerie Wars in northern France in 1358. The authorities made conspicuous efforts to thwart the law of supply and demand. Lords tried to require their laborers to perform their traditional feudal duties, including on occasions the duties of their dead neighbors, and strove to restrict wages to their traditional level.
In eastern Europe, where the population was much thinner on the ground and where town life was virtually obliterated, the peasants were unable to exploit their new scarcity value because there was no functioning labor market to which they could take their services. Landlords were able to forbid them from moving, effectively enslaving them and forcing them into a more abject servitude than anything that had existed in western Europe since the time of Charlemagne. But elsewhere in Europe the established order of things was unhinged by the inescapable facts that there was no one to do the work and no one to buy the merchandise; and so the balance of bargaining power — not to mention purchasing power — shifted for a while decisively in favour of the peasantry, even where their revolts were brutally suppressed.
Everywhere else the long-run effects of the Black Death, which manifested themselves increasingly in the 15th century, reflected the restricted supply and higher price of labor. In 1363, an observer lamented the changing times in tones that became all too familiar in post-World War II Europe: "Serving girls and unskilled women with no experience in service and stable boys want at least 12 florins per year, and the most arrogant among them 18 or 24 florins per year, and so also nurses and minor artisans working with their hands want three times or nearly the usual pay, and laborers on the land all want oxen and all seed, and want to work the best lands, and to abandon all others."
We can hear the same contemporary ring of European condescension in Africa in a late medieval comment on builders enjoying full employment: "They waste much part of the day in late coming to work, early departing therefrom, long sitting at their breakfast and longtime of sleeping afternoon."
The effects of expensive labor were entirely predictable — people tried to do without it, and they invented and invested to that end. Land was switched from arable wheat growing to pasture, cowherds and shepherds being able to service more acres than plowmen and harvesters. Oxen were bred; and fertilizers were spread. Urban artisans were equipped with more and better tools and machines. In 1421 Florence issued the first known patent — for a canal boat equipped with cranes. By reversing the labor surplus of the early 14th century, the plague removed a number of constraints on the generation of agricultural surplus, the further division of labor and the improvement in productivity. Change became possible, indeed inevitable, and a new economic advance began.
By 1500 total production and trade in Europe had both recovered the ground they lost in the decades after the Black Death and probably exceeded their previous peaks. Population itself was also rising again, though it did not return to its pre-plague level until the middle of the 16th century.
No sane person would think this end justified the means, then or now, in Europe or Africa. But if AIDS cannot be stopped and if it does revolutionize traditional social and economic structures in Africa and elsewhere, there may in the end be some compensating benefits to generations yet unborn. Still, not much of a silver lining.