Biological basis of determinants of health.

Clinical medicine and health policy planning find common cause as they seek to define the determinants of health. There is substantial recent interest in the social ecology in which health is embedded. However, biology is where these contributing environmental factors are translated. I provide a new conceptual framework for the biological determinants of health. The old public health rubric of host, agent, and environment as the features that define the root elements of health is an impoverished scheme, because it does not represent our new appreciation of genetic and aging contributions to phenotypic health. I propose genes, external agency, internal agency, and aging as more operationally helpful determinants that effectively describe the biological experience of the organism. This scheme has the advantage of differentiating those agencies that are practically approachable, and therefore deserving of increased attention and investment, and those that are currently intractable.