Nutrition, Mortality, and Population Size: Malthus' Court of Last Resort

Abstract

The relevance of the Malthusian equilibrium between resources and population is often exaggerated and the mechanisms linking fertility and mortality to food supplies require empirical support which is not yet convincing. The graphical presentation usually employed to summarize the equilibrium between population and resources is too schematic to indicate the mechanisms involved. It fails to depict the inequalities in entitlement or the possible diversity in what is needed for survival. Malthus does not clearly distinguish between those sources of mortality which are only tenuously if at all linked to resources and those in which the relationship is apparent. If the concept of an equilibrium is flawed then what remains of the necessary relationship which Malthus postulated between population and resources. Assuming closed population in which individuals are equal in entitlement and in survival requirements the edogenous aspects of the Malthusian equation are examined specifically the way in which resources are linked to the stream of births and deaths which jointly determine population size. Fertility may play role in the homeostatic adjustment. In many historical societies births were essentially confined to married women. Thus an important determinant of the yearly number of births was the proportion of women in childbearing age who were married. There is an a priori reason to expect that similar relationship may be found in other populations characterized by the Western European marriage pattern. Once marriage was separated from menarche and neither its timing nor its incidence was function of biology it was free to fluctuate with changes in the economic environment. In many nonEuropean societies marriage was closely linked to menarche. Under some assumptions substantial decline in the age of menarche could have considerable effect on overall fertility. Resources could affect the length of time from 1 live birth to another. The most obvious path is through nutrition. The evidence that ovulation ceases when nutritional deprivation is extreme is convincing but such periods are also likely to be times in which ordinary family life is atypical in other ways. Nutrition is not the only factor to be considered. Coital frequency may be reduced when times are bad. It is unclear whether customs regulating nursing are associated with resources but it may be that populations in which these customs took hold were better able to cope with chronic insufficiency of resources than were those in which births normally followed 1 another with great rapidity. There is too little evidence to treat these possible connections between births and resources as more than speculative. Excluding periods of crisis mortality neither the high death rates of the past nor the comparatively high death rates of some contemporary countries can be attributed to widespread starvation. Mortality may be tied to the availability of food at levels of undernourishment that fall short of starvation.