Seasonal fluctuations in food price, foreign trade, and their interaction with technophysio evolution

This dissertation examines the connection between economics and human physiology that operates in the early life of children through seasonal variations in food supply. The dissertation demonstrates that there exist substantial seasonal variations in the number of births, birth weight, and life span in the United States during the nineteenth and the twentieth centuries. It then discusses a hypothesis that these variations are behavioral and can be understood in an economic model of decision making in response to seasonal variations in food prices. Regression analysis of birth weight and life span based on micro-level data provide some evidences on the price effect. The dissertation argues that the observed decline in the magnitude of seasonal fluctuations in all physiological variables is the result of the reduction in seasonal variations of food prices. Foreign trade between countries with different agricultural cycles is one of the mechanisms that brought about such a decline. The dissertation also finds the effects of seasonal variations in infectious diseases on birth weight. Since the incidence of infectious diseases is found to be higher in low income countries, the reduction in the magnitude of the disease effect will decline with economic development. The final chapter argues that the reduction in the magnitude of the seasonality of life span reduces the variance of annual mortality rates.