ABSTRACT
Comparisons of infant mortality in developed and less developed countries are often taken as one of the most significant of international contrasts in well-being. For a period the historic improvement in death control was restricted to the West, but from the 1940s on it spread to the rest of the world. From prehistory to the Middle Ages the human life span doubled, and then it remained almost static until the nineteenth century. If ever it becomes possible to reduce significantly the mortality from cancers and degenerative diseases, then the main causes of death would be those that can be loosely categorized as the consequences of social disorder. A crucial example of recent medical progress is the rise of a concept, immunity, and its application to patients. In the early years of the twentieth century "drug addiction" meant no more than the illicit use of "drugs," without any implication concerning patterns of usage or what drug was taken.
