The sociologist's contribution stems from other interests. Early sociologists were concerned, in large measure, with social problems—poverty, crime, illegitimacy, immigration, insanity. They postulated a connection between these problems and particular aspects of the social environment; for example, the relationship between occupation and tuberculosis was emphasized. Out of these concerns emerged an impulse towards social reform which had a considerable impact on the early public health movement and on the beginnings of social work.