Page 1Page 2Page 3Page 4Page 5Page 6Page 7Page 8Page 9Page 10Page 11Page 12Page 13Page 14Page 15Page 16Page 17Page 18Page 19Page 20sJ5Diseases of PovertyDiseases due to Deficiencies and HazardsI suggested in Part I that a pivotal question in the history of human healthis whether, by restraints on numbers population size was in generalmaintained at a level that the resources of the environment, particularly thefood supply, could support. Since infanticide was probably the mosteffective means of limiting population growth the question might almost berephrased by asking whether in the inglorious past parents were preparedto kill their children in order to maintain a tolerable existence, or only whendriven by extreme necessity to reduce their numbers. After reviewing theevidence I concluded that population growth was not effectively restricted,and that until the nineteenth century man was no exception to Malthus'generalization that 'the tendency of all animated life is to increase beyondthe nourishment prepared for it'. The consumption of unfamiliar foods, thesearch for new territories and finally, the transition to a more productiveform of life under agriculture, were all motivated by the need for food,This conclusion has a large bearing on interpretation of the determinantsof health and disease. Our predecessors lived in an environment to whichthey were well adapted through natural selection, and they were largely freefrom disease due to maladaptation or defective genes. Even food deficiencywas probably met to some extent by genetic selection of people who couldsurvive on low food intakes, the ancestors of the unfortunates who todayhave to reduce their daily consumption to a few hundred calories in order tolose weight. But beyond a certain point lack of food could not be counteredby genetic adaptation, and ill health was due mainly to the direct andindirect effects of food deficiency. As direct effects I refer to starvation andmalnutrition; as indirect effects to hazards due to the conditions of life and,to the extent that it is influenced by nutrition and infectious disease.Until 10,000 years ago the hazards from conditions of life wereconsiderable. For hunters and gatherers trauma was a common cause ofDISEASES OF POVERTY121injury and death, the nature of the injuries being determined largely by thecharacter of the habitat: Eskimos were at risk from cold and drowning, theAborigines from fractures, the Siriono from falls from trees. Of course notall hazards were food related, and some human beings have always beenready to injure to kill their fellows or themselves for love or hate or for noapparent reason. But with due regard for such exceptions, the environmen-tal risks to which hunter-gatherers were exposed were determined mainlyby the nature of the habitat, which depended on the source and availabilityof food.As previously noted (see pp. 29-40), conditions in the Pleistocene epochwere unsuited to the spread of human infectious diseases. Hunter-gathererslived an open air, nomadic life in small groups, meeting only a few hundredpeople in a lifetime. Under such conditions most of the diseases which werelater predominant could not have existed, and infection was due mainly tothe zoonoses (which have other animal hosts), to commensals (such as thehelminths) and possibly to a few human infections (such as tuberculosis andchicken pox) characterized by latency and recurrent disease. Response tosuch infections must have been determined substantially by the generalstate of health which in turn was influenced by nutrition.The food provided by agriculture made it possible for numbers toexpand; but as fertility was not effectively controlled, they expanded to thesize at which food resources again became marginal. It is hardly possible toread an account of everyday life in the past without being acutely aware ofthe frequency and devastating effects of famine. As recently as the periodbetween the fifteenth and eighteenth centuries the world consisted of onevast peasantry, and 'the rhythm, quality and deficiency of harvests orderedall material life'. I 'Famine recurred so insistently for centuries on end thatit became incorporated into man's biological regime and built into his dailylife. Dearth and penury were continual, and familiar even in Europe,despite its privileged position. "Things were far worse in Asia, China andIndia. Famine there seemed like the end of the world.'2 It is on suchgrounds that it seems justified to conclude that the direct effects of fooddeficiency - starvation and malnutrition - were major determinants ofdisease and death in the historical period, at least until the nineteenthcentury.But the indirect effects of food shortage were also important. After theintroduction of agriculture and a more settled way of life, some physicalhazards were probably reduced; but those due to infectious diseases weregreatly increased, particularly after the establishment of cities about 5000years ago. With large populations, living in unhygienic conditions, theBraude!, F. The Structures of Everyday Life. London, Fontana Press, 1985: 49, 73, 76.2 Ibid.122DISEASES OF. POVERTYhuman infections which have no other animal host became the predomi-nant causes of sickness and death. In chapter 2 I discussed reasons forthinking that although the effects of malnutrition are not the same in everydisease, it has a profound influence on the frequency and seriousness ofinfection. Perhaps the most persuasive evidence for this conclusion is thefact that mortality from infectious diseases declined rapidly in somecountries in Europe in the nineteenth century when nutrition improved,although there was little vaccination, no effective treatment, and exposureto infections in the industrial towns initially increased.Conclusions concerning the origins of human diseases before theeighteenth century turn largely on the answers to two questions: Werenumbers in general maintained at a level that food resources could support?And was experience of infectious diseases determined mainly by conditionsof life, particularly by the food supply, or was it essentially fortuitous, thatis independent of identifiable environmental or medical influences? We cansee that the answers to these questions are closely related. If food wasadequate, the high mortality and slow rate of population growth must beattributed largely to the fortuitous behaviour of the infections; but if foodwas seriously deficient, they can be