The Power of Plagues. Irwin W. Sherman

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The Power of Plagues - Irwin W. Sherman


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of the diet. All this attests to the fact that between 100,000 and 50,000 years ago there was a significant change in the cognitive capacity of the human brain without a significant change in its size. Coupled with this change in brain organization was the anatomical improvement of the voice box; now humans could not only speak but also begin to develop language.

      For 99% of human existence we were hunter-gatherers, so why some 10,000 years ago did we settle down to become farmers? This change from hunting and gathering to farming has been termed the agricultural revolution, the time when humans domesticated plants and animals and exerted control over food production. Although the term “revolution” would seem to indicate that it appeared suddenly and dramatically, this was certainly not the case. The human control of food production was not discovered or invented, nor was it a conscious choice made by our ancestors “to farm” or “not to farm,” since at the time there would have been no farmers to serve as role models. No, domestication of plants and animals evolved as a consequence of human choice made without any awareness of its future long-term consequences.

      Development of techniques and practices for agriculture and animal husbandry progressed step by step in sequential fashion. They were not developed over a short time, and not all the wild animals and wild plants that would eventually be domesticated in a particular region would be domesticated at the same time. Indeed, it probably took thousands of years to shift the human diet from wild foods alone to foods both cultivated and wild. The reason for this time lag is that food production evolved as a result of the accumulation of many separate choices, and there were trade-offs, especially in the allocation of time and effort.

      Consider for the moment that you are a hunter-gatherer who has accumulated enough wisdom and technology to set up a small garden. Some of the choices you would be faced with are: Which plants should I grow? How much time should I spend planting instead of hunting or scavenging? What are the benefits of tending the garden over going out to hunt and gather wild plants? Perhaps your most important consideration might be which of the two, hunting or gardening, will save you from starvation in the future. It has been speculated by Jared Diamond that “all other things being equal, people seek to maximize their return of calories, protein or other specific food categories by foraging in a way that yields the most return with the greatest certainty in the least time for the least effort. Simultaneously they seek to minimize the risk of starving. … One suggested function of the first gardeners 11,000 years ago was to provide a reliable reserve larder as insurance in case wild food supplies failed.” Although the factors that contributed to the shift from hunting and gathering to farming still remain controversial with regard to their relative importance, one thing is certain: once there was a shift from nomadic hunting and gathering to more-sedentary food production, there could be no turning back.

      Farming populations became better nourished thanks to an increase in the availability of the number of edible calories per square mile, and eventually farmers replaced the nomadic groups of hunter-gatherers by converting them to engage in the practice of farming or by displacing them by the sheer force of greater numbers.

      The life of nomadic hunter-gatherers was such that population levels were well below the maximum limit that would be imposed by their reproductive biology and the availability of food. What then limited their increase? The inability of the hunter-gatherer mother to carry more than a single child along with her normal baggage, coupled with her inability to nurse more than one child at a time, limited the practical interval between births to four years. It is likely that hunter-gatherers effectively spaced their children by means of lactation amenorrhea, sexual abstinence, infanticide, and spontaneous abortion. In contrast, once humans settled down, they were freed from the encumbrances imposed on the hunters and gatherers who had to carry their children around, so that now they could have as many children as they could bear and raise. Consequently, the birth interval for the “farmer” was reduced to two years. Agriculture also encouraged higher birth rates because additional children provided cheap labor. Further, farming had another advantage over hunting and gathering: more calories could be produced per unit land area and time expended. While 200 square miles could support 50 to 60 hunter-gatherers, more than 10,000 “farmers” could be supported on this same land area. The higher birth rate of the food producers, together with their ability to feed more people per square mile, allowed these “farmers” to achieve much higher population densities than those who were engaged in hunting and gathering.

      Some of the surplus food could be used to feed those “who provide religious justification for wars of conquest, artisans such as metalworkers who develop swords, guns and other technologies; and scribes, who preserve far more information than can be remembered accurately.” In time, political stratification would develop: heading the settled community would be the elite, consisting of hereditary chiefs (or kings) and bureaucrats. Under the appropriate circumstances these complex political units, which governed “the settled,” could also be mustered into formidable armies of conquest. Stored food and the land upon which it was grown became valuable resources that could be taxed, and surpluses could be traded for other goods; commerce and banking began to emerge. Thus, with larger populations family and inheritance


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