Although early ethnographies of non-literate peoples frequently contained data on medical beliefs and practices, physician-anthropologist, William Hallam Rivers (1864-1922), was the first to attempt to relate systematically native medicine to other aspects of culture and social organization (Wellin 1977:49). Rivers recognized a causal relationship between medical beliefs (independent variable) and practices (dependent variable). He argued that native medical patterns are 'not a medley of disconnected and meaningless customs, but rather inspired by definite ideas concerning the causation of disease' (1924:51). Further, native medical practices and beliefs, taken together, constitute a 'social institution' which can be studied in terms of principles and methods applied in the study of social institutions in general (Rivers 1926:61). In Rivers' scheme, the role and function of curers depend on the particular culture. Sorcerers play key roles in groups in which magic and sorcery predominate; priests in those in which religious and supernatural explanations rule; and in those in which the emphasis is on empirical techniques, it is the 'leech' (Rivers' term for empirical curers). A number of writers approached the problem of native curing practices in various cultural settings in terms of their functions (Ackerknecht 1942, 1946, Hallowell 1935, Field 1937, Rogers 1948). Others examined the process of becoming a curer, of recruitment to the role and the 'articulation' of the curer's role with the social system: most notably, Gillin's (1956) account of 'the making of a witch doctor', Handelman's (1967) 'Washo shaman', Spiro's (1967) analysis of Burmese medical-religious beliefs and practices, and Turner's ( 1964) work on the 'Ndembu doctor'. In recent years, studies began to indicate that healers and healing systems are responding in many parts of the world to the conditions of change in ways that are not always negative and destructive (Landy 1977: 467). The adaptive capacity of native medical systems to change is conceptualized in Paul's (1955) model of 'system and system change'. The approach has two fundamental propositions: (a) The responses of a given sociocul turai (and medical) system to the introduction of new elements are to be explained not solely by the nature of the system or the nature and mode of introduction of new elements but by the complex interaction of both; and (b) Reciprocal or feedback processes occur. That is, the introduction of new health related elements can be expected to affect the host sociocultural (and medical) system; in turn, the latter will also affect (change or reinterpret) the new elements. Empirical data from a number of studies validate Paul's propositions. Erasmus (1952) found that in Quito, Equador, illnesses thought to be caused by supernatural entities were referred to native curers, while those of non-supernatural origin (such as, appendicitis and tuberculosis) were treated by modern physicians. Similarly, in the village of Sherupur in North India, Gould (1957) reported the existence of two medical sys-