Plagues and Peoples (33 page)

Thus there emerged a new relation between humankind and parasitic micro-organisms. It was a more stable pattern of parasitism, less destructive to human hosts, and correspondingly more secure for the parasites. The infectious organisms could count on a fresh supply of susceptible children, whose numbers and availability were subject to far smaller statistical variation than had been the case when epidemic patterns of disease produced alternate feast and famine for the organisms infecting humanity. Both sides were therefore more secure, and in that sense better off. As endemicity set in at one port city after another, filtering inland along main routes of movement and seeping more slowly into the countryside, a new ecological era dawned. Massive growth of civilized populations, and correspondingly accelerated destruction of the remaining isolated human groups was the first and most obvious consequence of the new disease regime, a disease regime we can appropriately call “modern.” Imminent collision with limits on food supply, as well as other strains upon human adaptation to the environment, was the other side of this modern microparasitic regime.

The shift from epidemic to endemic forms of infection was, of course, not complete; the next chapter will have something to say about smallpox and cholera and some other notable encounters with epidemics that humanity has experienced in recent centuries. Nonetheless, the force of the modern pattern of infection was clearly evident by 1700, or by 1750 at the latest—and not only in Europe, but throughout the world.
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Before turning briefly to consider what little can be said of disease and population histories of Asia and Africa, however, another point about Europe’s disease experience should be made. The fundamental character of the changing incidence of epidemic disease was obscured in early modern times by the onset of particularly severe weather conditions that created frequent crop failures and famines in northern Europe.
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Simultaneously, the Mediterranean lands underwent a general crisis owing to mounting shortages of food and fuel.
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Parts of Europe were also devastated by war—e.g., Italy between 1494 and 1559, and Germany between 1618 and 1648. These wars were waged with more than customary brutality, owing to difficulties regularly constituted governments faced in supplying mercenary troops. Armies tended, therefore, to plunder friend and foe almost indiscriminately.
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Moreover, urban growth in northern Europe often put strains on pre-existing sanitary arrangements, so that death rates in thriving cities like London or Amsterdam may well have edged upward.
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Yet on the whole it seems safe to say that intensified efforts at public sanitation forestalled major disaster. These were largely initiated in times of plague, stimulated in the North by the example of Italian cities whose public sanitation and health services were more highly developed than elsewhere in Europe.
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The result, therefore, was that the tendency toward systematic population growth inherent in the changing pattern of disease incidence was partially masked for two centuries by factors that acted in a contrary sense. Yet the fundamental fact remains: European population did continue a slight increase despite local setbacks and temporary crises; and did so despite adverse weather and war.

Europe’s expansion is such a central fact of modern history that we are likely to take it almost for granted and fail to recognize the quite exceptional ecological circumstances that provided sufficient numbers of exportable (and often expendable) human beings needed to undertake such multifarious, risky, and demographically costly ventures. The fact was that Europe found itself in a position to capitalize handsomely on
the new capacity for demographic growth which the altered disease pattern conferred on all civilized peoples of the Old World.
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Lands emptying of Amerindians were supplemented by lands emptying of Pacific islanders and Australians, of Siberian tribesmen, and of Hottentots.
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In all these disparate regions, Europeans were uniquely in a position to move in, thanks to their control of transoceanic shipping and other means of transport, and to the possession of other technological skills superior to those which disease-decimated local peoples could command. In all of this vast process, bacteriology was at least as important as technology. The decay of native numbers and the availability of European populations to occupy such vast and varied emptied spaces both derived from the distinctive modern pattern of epidemiology.

The key significance of the altered pattern of infectious disease in the complex of factors sustaining Europe’s expansion is confirmed if we turn attention to what happened among other civilized peoples of the Old World. For there, too, the opening of the oceans to regular shipping and the intensification of contacts resulting from circulation of ships and crews had noticeable effects on populations and disease.

The only new disease known to have come to India, China, Japan, and the Middle East was syphilis; and its demographic impact in these lands seems no different from that in Europe. That is to say, initial dismay and extended comment ebbed away as the infection became less florid in its symptoms and subsided toward chronic endemicity.
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Familiar infections continued to manifest themselves as epidemics, in Asia as much as in Europe; and there is reason to think that the frequency of epidemics may have increased. Certainly, Chinese records show a sharp upsurge in epidemic outbreaks, as the following table, based on the researches of Dr. Joseph Cha, makes obvious
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Unfortunately one cannot conclude that the number of pestilences increased as suddenly as this table suggests, since records from the earlier times are more fragmentary than from recent centuries. All the same, the apparent doubling of recorded instances of epidemic disease in the sixteenth century probably corresponds to a real increase in the frequency with which epidemics arrived in China. China’s political system was then in good order, so that wars and rebellions cannot account for the disease record. New contacts arising from European transoceanic voyaging seem a far more plausible cause. If so, we can safely assume that an epidemiological basis was being laid in China after 1500 for the pattern of population growth that became such a prominent feature of subsequent Chinese history. The best available estimates for China’s total population are as follows
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The setback to China’s population growth apparent between 1600 and 1700 corresponds to the slowing of western Europe’s population growth in the same period. Colder winters and shortened growing seasons probably played a part in keeping Chinese population almost steady during the seventeenth century. A graph of temperatures, based on the frequency with which the Yangtze lakes froze over in wintertime, shows the coldest time in all recorded history to have fallen in the middle decades of the seventeenth century, precisely at the time when disorders incident to the displacement of the Ming by the Manchu Dynasty were at their peak.
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Such a coincidence of cold weather and civil disorder offers an obvious and adequate explanation for the cessation of China’s population
growth in the seventeenth century. But only a changing disease regime, reflecting the increasing homogenization of infections around the world, seems adequate to explain the systematic population growth before and after the seventeenth-century halt.

China’s modern demography and disease experience therefore seems to correspond to that of Europe. Japan’s population curve stands sharply in contrast. After rather rapid growth in the four centuries before 1726, when the first reasonably accurate census becomes available, Japanese population remained nearly constant until the middle of the 19th century. Estimates are as follows
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Widespread infanticide is believed responsible for this stabilization of population. But disease may have played a part in what happened, for the number of recorded epidemics, as compiled by Fujikawa Yu, also showed a notable increase after 1700, when the leveling off of population growth occurred.
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No worthwhile estimates for Indian or Middle Eastern demographic history can be made on the basis of existing scholarship. Ottoman population history probably paralleled developments in other parts of the Mediterranean; and some bold demographers have suggested that the number of India’s inhabitants increased with the establishment of a more perfect internal peace in the second half of the seventeenth century, following the Mughal conquest of most of the peninsula, 1526–1605.
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What exact course infectious disease may have followed in India and inner Asia remains unascertainable; but inasmuch as Indian ports shared on the intensified trade network that European ships extended across the world’s oceans, an intensified disease circulation surely must have existed in India also. Thus, despite gross lacunae in the evidence, nothing obstructs
the inference that the modern disease pattern also established itself among civilized populations of Asia, perhaps less uniformly and more slowly than in Europe; but in parallel, indeed identical, fashion all the same.

Diseases, however, were not the only biologically significant items that diffused more uniformly throughout the civilized world as a result of intensified transoceanic voyaging. Food crops did the same; and wherever a strange new plant offered some sort of value—including initially often merely the value of novelty—it was cherished and introduced into gardens and fields.

By far the most important new food crops came from the Americas. Maize, potatoes, tomatoes, chili peppers, peanuts, and manioc all became available in Eurasia and Africa only after Columbus’ discovery of America. In many regions of the Old World, one or another of these crops was capable of producing far more calories per acre than anything known before. Older ceilings on population rose correspondingly wherever the new crops became generally cultivated. China, Africa, and Europe all were profoundly affected.
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American food crops were important not solely for the increased calorie production per cultivated acre they permitted. Chili peppers and tomatoes, for instance, supplied a rich vitamin source whose importance in the diets of Mediterranean and Indian populations in modern times is very great indeed. How rapidly these American novelties became commonly available to supplement earlier and sometimes vitamin-deficient diets is unclear, though the first introduction of the new plants dates to the sixteenth century. As these foods entered into widespread use among rich and poor alike, one can be sure that a more adequate diet became available to the Indian and Mediterranean peoples, and health levels presumably reflected this fact.
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Oranges, originally cultivated in China, and other citrus fruits were also diffused widely by Europeans, even before the sovereign value of their juices against shipboard scurvy became widely known. But exactly when and
where consumption of citrus fruits assumed dietary significance is impossible to say.

Obviously enough, without the capacity to produce additional quantities of food, the population growth that set in toward the end of the seventeenth century in so many parts of the civilized world could not have gone very far. The superior productivity and nutritiousness of American food crops was therefore of the greatest importance for human life in every part of the Old World.

Changes in disease patterns and the increase in productivity that the spread of American food crops permitted were probably the two most active factors in triggering civilized population growth in early modern times. They operated worldwide, and in parallel fashion to allow more human beings to survive and grow to maturity than had ever been possible before. There was, however, another significant change, this time on the macroparasitic side. Governments became fewer and more capable of maintaining domestic peace over broader regions of the earth, thanks to the global diffusion of a new weapon: the cannon. Cannon spread just as disease germs and plants did—along the world’s seaways. Everywhere that the big guns established themselves, the effect was to concentrate overwhelming force in fewer hands. Cannon were expensive, requiring large amounts of metal for their manufacture and rare skills for their management. Yet when the technique was new, a simple big gun brought into position against a defended place was capable within a few hours of blasting a hole even in the stoutest fortification.

Such sovereign power to penetrate otherwise redoubtable strongholds radically diminished the military power of local potentates. Whoever possessed a few of the new weapons or commanded the skills needed for manufacturing them on the spot, was in a position to enforce his will much more effectively and overpoweringly than ever before. The result, naturally, was the consolidation of a relatively small number of “gunpowder empires.” Thus the late Ming and Manchu empires of China, together with the Mughal, Tokugawa, Safavid,
Ottoman, Muscovite, Spanish, and Portuguese empires all may be classed as imperial states held together by a monopoly of decisive force exercised by a few cannoneers in the employ of the respective imperial governments. The territorial expansion of these states and the predictability with which imperial cannoneers could batter down the defending walls of local rivals meant that most of Asia and much of Europe began to enjoy a superior level of public peace from the latter part of the seventeenth century when these empires all came to be firmly established. War and plunder diminished their scope accordingly, being more and more brought under bureaucratic control, and directed toward distant and often thinly populated frontiers.
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