Plagues and Peoples (14 page)

There was, however, another powerful factor in the macroparasitic balance that began to define itself in ancient China. As Chinese landowners consolidated claims on the peasantry, a distinctive set of ideas and ideals of conduct also took root among the landlord and official classes. These are commonly called Confucian because the sage Confucius (traditional dates 551–479
B.C
.) did a great deal to articulate and define the new ideals. The propagation of Confucian culture among imperial officials and private landowners internalized an ethic that strenuously restrained arbitrary or innovative use of power. One critically important consequence was to keep exactions imposed upon the peasantry within traditional and, under most circumstances, tolerable limits.

As a result, by the time of the Emperor Wu-ti (140–87
B.C
.), a remarkably stable and long-lasting balance was achieved within Chinese society between peasant farmers and the two social classes most directly parasitic upon them. This balance survived, with some important elaboration but no real structural breaks, until the twentieth century. Overall, we can be sure that the demands of landlord and official tax collector, heavy though they were, did not take more from the Chinese farmers than they were capable of producing over and above the minimum required for their own survival. Otherwise the slow, majestic march of the Chinese population throughout the Yellow River flood plain and adjacent regions, and then southward into and beyond the Yangtze Valley, could not have occurred; nor could the Chinese peasantry have offered a persistently expanding base (despite innumerable local and some general and long-lasting setbacks) for the imposing cultural and imperial structures of traditional China.

Existing literature does not permit anyone to follow the pace of this Chinese advance with any exactitude. Yet massive development of the South did not occur until after the end of the Han Dynasty. In other words, almost a thousand years elapsed from the time when the taming of the Yellow River
flood plain got seriously under way before comparable development took place in the valley of the Yangtze River.
¹³

At first glance this relatively slow pace of Chinese settlement in more southerly parts of what is today China may seem surprising. Political-military obstacles were relatively unimportant. Agricultural conditions favored settlement, since milder climates meant longer growing seasons, and more abundant rainfall removed the risk of drought that often endangered crops on unirrigated land in the North. Moreover, the fact that the Yangtze passes through lakes after it emerges from the mountains of the West means that no troublesome quantities of sediment clog its lower reaches. The awkward buildup of the river bed, characteristic of the Yellow River, was thus absent. Correspondingly, dikes and artificial networks for water distribution escape the extraordinary pressures they encounter in the North. The awesome, recurrent, and inescapable technical disasters that distinguished the history of the Yellow River valley simply do not occur.

Despite these obvious and real advantages, an invisible and unrecorded but, one must still believe, very potent obstacle stood in the way of the swift and successful development of rice paddies and urban life in lands to the south of the historic cradle of Chinese civilization: for in moving southward and into better farming regions, Chinese pioneers were also climbing a rather steep disease gradient!

The climatic shift involved is comparable to the difference between New England and Florida, but the lie of the land and prevailing wind patterns make the transition sharper than any climatic gradient occurring along the East Coast of North America. A mountain barrier shelters the Yangtze Valley from the cold and dry northwest winds that pour across the Yellow River valley from the Mongolian plateau in winter, constituting the winter monsoon. Correspondingly, in summer, when the monsoon winds blow the opposite way, warm, moist air sucked in from the South China Sea assures abundant precipitation in the Yangtze region. But these summer winds shed most of their moisture while crossing the mountain barrier
before reaching the Yellow River valley, so that rainfall there is frequently insufficient to ward off damaging drought on unirrigated fields.

The result is a sharp climatic difference between northern and central China. Among other things, the warmer, moister condition of the South allowed a greater variety of parasites to flourish than could survive in the North. Throughout the Yellow River flood plain, the severe winters killed off parasites that lacked dormant forms capable of resisting prolonged freezing. Important insect carriers of disease were similarly inhibited from establishing themselves because they could not survive the cold and dry conditions of the North. Nothing of the kind occurs in the Yangtze Valley south of the sheltering mountains. Populations accustomed to disease conditions of the North therefore faced formidable problems in adjusting to the markedly different patterns of parasitism that prevailed farther south.

The earlier shift from dry farming on loess soils to irrigation farming in the Yellow River flood plain must also have exposed Chinese peasants to new and perhaps initially formidable disease risks. But whatever microparasitic adjustments occurred in connection with this change went hand in hand with far more conspicuous and time-consuming adjustments of a technical and macroparasitic kind. Centuries of effort were required to learn the arts of water management on a scale suitable for taming the Yellow River, and problems of political consolidation and modulation of human macroparasitism upon the peasantry were no less critical and time-consuming. Any adjustments to intensified disease risks could and did therefore occur simultaneously with these other more conspicuous transformations of Chinese society and techniques.

Which process was the critical one? It is of course impossible to say for sure, but the macroparasitic side seems to have been the slower to come into balance. The reason for making such a judgment is that political-military stability did not come to China until the very end of the third century
B.C
. Before that time, organized violence mounted in intensity
throughout the Warring States epoch of Chinese history (403–221
B.C
.), climaxing with the conquest of the entire Chinese area by a still semi-barbarous state of Ch’in in 221
B.C
. By the time the macroparasitic balances of ancient China attained a new imperial definition under the Han Dynasty (202
B.C.—A.D
. 221) Chinese peasants already had four centuries of experience with the conditions of rice paddy farming behind them. Such a length of time gave ample opportunity for the epidemiological consequences of irrigation agriculture to stabilize themselves in the Yellow River valley, generations or even centuries before the macroparasitic side came into balance.

Clearly, whatever intensification of infection and infestation occurred when Chinese farmers began to spend a significant part of their working time in shallow standing water—and there must have been striking consequences of such a change from the semi-arid conditions of loess farming—the new patterns of disease did not forestall a steady increase in human numbers. Otherwise manpower for building and maintaining an ever-expanding network of dikes and water channels, not to mention the manpower for increasingly massive armies, would simply not have been available. When, however, engineering techniques along with the administrative and moral bases for stable imperial government had been achieved by the end of the third century
B.C
., nothing remained to inhibit the rapid development of central and southern China except the disease barrier. The power of that barrier is attested by the five to six additional centuries that elapsed before massive occupation of the Yangtze Valley by Chinese settlers became an accomplished fact. Put very simply, too many immigrants from the cooler, drier North died to permit a more rapid buildup.

All these assertions remain uncomfortably abstract and
a priori
. As in the case of the Middle East, there is little hope of discovering from ancient texts exactly what the humanly dangerous parasites may have been. Still, ancient writers often betray keen awareness of the disease risks of the South. Thus, Ssu-ma Ch’ien, the founder of Chinese historiography, who
lived from about 145 to 87
B.C
., tells us: “In the area south of the Yangtse the land is low and the climate humid; adult males die young.”
¹⁴
He also comments on the abundance of land suitable for cultivation and the sparsity of population in the region. This is authoritative testimony, for Ssu-ma Ch’ien made a personal tour of the country to prepare himself for writing his history. In later literature, the unhealthiness of the South was taken for granted. Special handbooks for southern travelers prescribed suitably exotic regimens and medicines for the malignant diseases encountered there.
¹⁵
These did not help very much, as the remarkably short tenure of office and high mortality recorded for officials sent to the South attests.

Modern disease distributions, so far as they can be plotted on the map of China, also confirm the expectation that a richer variety of infection and infestation flourishes in the warmer and wetter South. A number of modern disease boundaries fall between the Yellow River and the Yangtze, and climatic patterns certainly suggest that such a disease gradient is age-old.
¹⁶
The form in which ancient Chinese medical texts have come down to us, however, tends to hide regional differentiations, for the long list of distinct diseases Chinese medical writers recognized were organized around the seasons at which they were most prevalent. Some, such as malaria, can be confidently recognized today; for many others such identification with modern classifications of infection is as difficult as it is to translate Galen’s language into twentieth-century medical terminology.
¹⁷

Malaria, although occurring occasionally in the North, is a modern health problem only in the South.
¹⁸
In fact it may have constituted the principal obstacle to early Chinese expansion southward. Another mosquito-borne disease, dengue fever, which is closely related to yellow fever though not as lethal in modern times, also affects southern parts of China. Like malaria, dengue fever may have been present from time immemorial, lying in wait for immigrants from more northerly climes among whom prior exposure had not built up any sort of natural resistance. Fevers, including regularly
recurring fevers that must have been malarial, figure very prominently in ancient Chinese medical writings, a fact that supports the notion that such afflictions mattered a good deal in the early centuries of Chinese expansion.
¹⁹
Chinese
materia medica
of the nineteenth century also embraced several effective febrifuges—so much so that imported quinine scarcely seemed superior, even in the eyes of European doctors.
²⁰

Schistosomiasis is another major health problem of southern and central China in modern times. It, too, has probably always conformed to climatically defined boundaries. The recent discovery of a corpse from the second century
B.C. SO
well preserved that evidence of chronic schistosomiasis could be positively discerned proves that this affliction had established itself in China before Chinese pioneers were able to develop the Yangtze Valley to anything like the levels familiar in the North.
²¹

All in all, one may say that the Chinese met with striking success—technical and political as well as epidemiological—in penetrating the difficult environment of the Yellow River flood plain in the centuries about 600
B.C
. They achieved a no less striking success after about 200
B.C
. in arriving at a tolerable and unusually stable macroparasitic balance between food producers and those who lived off peasant harvests. At the microparasitic level, however, far-reaching adjustments within the vast regions to the South were still under way during the pre- and post-Christian centuries. The Yangtze Valley and other territories under Chinese political domination from 211
B.C
. (or earlier) could not be fully incorporated into the Chinese body social because of disease barriers until after the fall of the Han Dynasty (
A.D
. 221), when, as we shall presently see, other drastic and far-reaching disease adjustments also occurred.

In India, information about the early agricultural development of the middle Ganges Valley and of adjacent regions closer to the Bay of Bengal is practically nil. Rice cultivation became important at an early time—but just when seems impossible to tell. Nor is it even clear how important irrigation
was. In the Ganges Valley monsoon rains were fully adequate for most agricultural purposes without bothering to tap the Ganges’ waters. Irrigation was, however, essential for multiple cropping in a single year, since in summer and fall monsoon rains cease, and artificial means for bringing water to the fields became necessary if the land were not to lie idle until the rains returned. Multiple cropping has been widespread in recent centuries; how ancient it may be has never been satisfactorily established.

What is known is that powerful and extensive kingdoms developed in the Ganges Valley beginning about 600
B.C
. Soon after Alexander’s invasion (327–325
B.C
.), one such state, ruled by Chandragupta Maurya (ca. 321–297
B.C.)
, united the entire region into a single imperial structure, and his successors extended their authority throughout most of the Indian subcontinent. Early in this political development, Prince Gautama, the Buddha (traditional dates: 563–483
B.C
.), played a role strikingly parallel to that of his Chinese contemporary, Confucius. For like Confucius in China, Buddha in India articulated a world view and exemplified a style of life that became widely influential.