Although heredity and environment are the determinants of public health, the great advances in the science of public health have in the past been based chiefly upon the control of environmental factors. In the field of heredity, knowledge of the functions of chromosomes and their constituent genes has elucidated the transmission of morphological changes from generation to generation. However, the basic chemical mechanisms of heredity variation have remained wholly obscure until the past decade.
During this decade, George Wells Beadle, chairman of the Division of Biology at the California Institute of Technology, together with his associates, has for the first time cast light upon this fundamental chemical problem. Professor Beadle, turning away from classical approaches to genetics, became concerned with the effects of changes produced experimentally in genes upon specific metabolic activities in the cell. Employing as an object of study the common mold Neurospora, he has demonstrated that each of the individual biochemical reactions of the cell is governed by a particular gene. Consequently, the loss of this gene is followed by the hereditary transmission to subsequent generations of a characteristic disturbance of metabolic activity.
Fulfillment of the implications of these pioneer studies will undoubtedly lead to an understanding of human constitution as related to the vital problems of host resistance and susceptibility in both metabolic and infectious disease.