The study of the interactions between humans and their surroundings, and the observed effect of such interactions is called human geography. Studies related to this field attempt to establish the human or natural factors underlying the environmental changes occurring at that site. It also tries to understand the sociocultural evolution of humans based on the stimuli provided by their physical living conditions. Till 1950, philosophers believed that human civilizations form and proliferate in certain parts of the world due to the direct influence of the natural physical environment found in those places. They put forth these beliefs in the form of theories which claimed that the environment had deterministic effects on the nature of human society and culture. The natural environment posed as a limiting factor for the development and progress of people inhabiting the particular area (environmental determinism). This provided a logical reasoning for diversity that was observed among the various civilizations and settlements of humans across the globe. These theories reinforced the idea that human-environment interactions were solely driven by the physical conditions, and that they were unidirectional. However, as time elapsed, scholars and scientists began to question the validity of these theories, as they did not account for the impact of humans on the environment. They also did not take into account the essential factor of human ingenuity and advancement in technology. Due to the availability of advanced technology, humans could have a larger impact on the environment and easily adapt themselves, if not overcome, to the physical conditions. This contradicted the previous claim of the deterministic nature of the environment and in its stead proposed that while the environment did pose a few limiting factors to the prosperity of the inhabiting people, the people or society was also capable of having an impact on the surrounding and molding it as per their needs (environmental possibilism). After 1950, both these sets of theories were revised and improved upon, as they proved inadequate to explain all the aspects related to human-environment interactions. A comprehensive comparison of these two concepts is given below. In order to better explain the development of human cultures with respect to the particular environment, a new theory was proposed, one that has been widely accepted and used. It is the theory of cultural ecology, and it is the study of human adaptation to social and physical environment with respect to biological as well as cultural processes.