Julian Steward was a student of A.L.Kroeber and started his research under the influence of Cultural Possibilism. Steward, however moved away from culture area approach and emphasised more on the close relationship between technology and environment but Steward was not an Environmental Determinist. While both groups of scholars within the fold of Environmental Determinism and Cultural Possibilsm viewed ‘Culture’ and ‘Environment’ as separate domains which influence each other, Steward treated them as interacting entities in a single framework. He viewed culture as an adaptive mechanism by which human beings adjust with their natural environment. According to Steward, every aspect of a culture does not adapt with the physical environment in the same manner. Although, he began his research in Archaeology, Steward gradually moved towards ethnographic studies of small populations. He found that the technologies of production and the related behaviour patterns and social organisational features of a small community are linked more intensively with the immediate natural environment and forms a constellation, which he termed as the ‘culture core’. Thus, among the Shoshone hunter-gatherers of North America Steward found that the technology of hunting is related with patrilineal kinship, patrilocal residence, band exogamy and low population density, which in turn helped the community members to successfully use their scarce hunting game resource base within a restricted area. According to him, hunter-gatherers under restricted and scarce resource base may have different types of hunting implements but patrilineal band structure is the common feature among them, and this is the ‘core’ of the hunting-gathering societies which has evolved over a long period of time in order to adapt in a specific type of environmental conditions. So, there is a causal relation between environment and the behaviour of human beings related to the productive technology and this relation recurs through history. The idea of Ecosystem was embedded in Steward’s thought since he viewed environment, productive technologies and related cultural behaviour is a causally interrelated network of relation which persist over time. For Steward, the principal meaning of ecology is concerned with the adaptation of human beings with the natural environment but human beings do not only adapt like animals, they adapt by means of culture(Steward, 1955:31). To understand human adaptations to the natural environment, Steward employed a new concept which he termed as Cultural Ecology. According to Steward, Cultural Ecology is the study of the relationship between culture and natural environment in which two orders of phenomena are involved: (i) all the biotic and abiotic features of the natural environment and (ii) the cultural elements by which human beings adapt with the environment including technology and economic organisation (Hatch 1973: 114-115). But Steward did not believe in a circular causality of all the parts of the ecosystem in which every part has an equal role to play for the maintenance of the whole. This is the reason that he subdivided culture into ‘core’ and ‘secondary features’. Another important aspect of the contribution of Julian Steward lies in the field of Cultural Evolution. For him, human ecosystems are dynamic and social evolution is not unilinear, it is multilinear, since each culture adapts to its local environment and also changes in its unique way.