Sunday, March 25, 2007

The Neolithic Revolution I

Hunting and gathering remained the chief economic activity for a long time, and even today they provide supplementary food for many westerners. The bow and arrow as well as the basic tools still used to hook or net fish or to trap game were developed long before the ad­vent of agriculture, pottery, or writing. The domestica­tion of animals probably began at an early date with the use of dogs in hunting, but was later extended to sheep, goats, and cattle that could be herded to provide a reli­able source of protein when game was scarce. Shortly thereafter, about ten thousand years ago, the first efforts were made to cultivate edible plants. The domestication of animals and the invention of agricul­ture marked one of the great turning points in human history. Several species of edible grasses are native to the upper reaches of the Tigris and Euphrates valleys in Asia Minor, including wild barley and two varieties of wheat. Of the latter, einkorn (one-corn), with its single row of seeds per stalk, produces only modest yields, but emmer, with multiple rows on each stem, is the ances­tor of modern wheat. When people learned to convert these seeds into gruel or bread is unknown, but once they did so the value of systematic cultivation became apparent. By 7000 B.C. farming was well established from Iran to Palestine. It spread into the Nile valley and the Aegean by 5000 B.C. and from the Balkans up the Danube and into central Europe in the years that fol­lowed. Radiocarbon dating has established the exis­tence of farming settlements in the Netherlands by 4000 B.C. and in Britain by 3200 B.C. The diffusion of agricultural techniques came about through borrowing and cultural contact as well as through migration. Farming, in other words, developed in response to local conditions. As the last ice age ended and hunting and fishing techniques improved, a general increase in population upset the Paleolithic ecology. Game became scarcer and more elusive while the human competition for dwindling resources grew more intense. Herding and the cultivation of row crops were soon essential to survival. In time, as the human population continued to grow, herding diminished. It provides fewer calories per unit of land than farming and was increasingly restricted to tracts otherwise un­suitable for cultivation. Though crop raising would al­ways be supplemented to some extent by other sources of food, it gradually emerged as the primary activity wherever land could be tilled. The invention of agriculture marked the beginning of the Neolithic or New Stone Age. The cultivation of plants, beginning with grains and expanding to include beans, peas, olives, and eventually grapes, made food supplies far more predictable than in a hunting or herd­ing economy. At the same time, it greatly increased the number of calories that could be produced from a given area of land. Efficiency was further enhanced by the in­vention of the wheel and the wooden plow, both of which came into common use around 3000 B.C. Farm­ing therefore promoted demographic growth both ab­solutely and in the density of population that a given area could support. On the negative side, the transition to a farming economy often resulted in diets that were deficient in protein and other important elements. Bread became the staff of life, largely because land supports more peo­ple if planted with grain. The nuts, animal proteins, and wild fruits typical of the Paleolithic diet became luxu­ries to be eaten only on special occasions. As a result, the skeletal remains of Neolithic farmers indicate that they were shorter and less healthy than their Paleolithic ancestors. Though beans, peas, lentils, and other pulses became a valuable source of protein, ordinary people consumed as much as 80 percent of their calories in the form of carbohydrates. Caloric intake varied widely. An adult male en­gaged in heavy labor requires a minimum of thirty-seven hundred calories per day. No way exists to measure a normal diet in Neolithic or ancient times, but the average peasant or laborer probably made do on far less, perhaps only twenty-five hundred to twenty-seven hundred calories per day. Grain yields on unfertilized land are relatively inelastic, typically ranging from three to twelve bushels per acre with a probable aver­age of five. Populations expand to meet the availability of resources, and Neolithic communities soon reached their ecological limits. If they could not expand the area under cultivation, they reached a balance that barely sustained life. Moreover, because grain harvests depend upon good weather and are susceptible to destruction by pests, shortfalls were common. In years of famine, caloric intake dropped below the level of sustenance. The establishment of permanent farming settle­ments also encouraged the spread of disease. The hunter-gatherers of Paleolithic times had lived in small groups and moved frequently in pursuit of game, a way of life that virtually precluded epidemics. Farming, however, is by definition sedentary. Fields and orchards require constant attention, and the old way of moving about while camping in caves or temporary shelters had to be abandoned. Early farmers built houses of sun-dried brick or of reeds and wood in close proximity to one another for security and to facilitate cooperation. The establishment of such villages encouraged the ac­cumulation of refuse and human waste. Water supplies became contaminated while disease-bearing rats, flies, lice, and cockroaches became the village or town dweller’s constant companions. Inadequate nutrition and susceptibility to epidemic disease created the so-called biological old regime, a demographic pattern that prevailed in Europe until the middle of the nineteenth century. Though few people starved, disease kept death rates high while poor nutri­tion kept birth rates low. Malnutrition raises the age of first menstruation and can prevent ovulation in mature women, thereby reducing the rate of conception. After conception, poor maternal diet led to a high rate of stillbirths and of complications during pregnancy. If a child were brought to term and survived the primitive obstetrics of the age, it faced the possibility that its mother would be too malnourished to nurse. Statistics are unavailable, but infant mortality probably ranged from 30 to 70 percent in the first two years of life.

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