In the early twentieth century, environmental geography was strongly tied to the single idea of environmental determinism, the doctrine that human activities are controlled by the environment. Scholars in this field attempted to create a causal science creating ties between environmental causes and human results.This belief has waxed and waned over the years, but found dominance within the field of human geography in the work of such scholars as Americans Ellen Churchill Semple and Ellsworth Huntington, and Briton Halford Mackinder whose work traced linkages between natural and human patterns, following in the tradition of the German Friedrich Ratzel. The theories of environmental determinism are quite controversial and linked to Social Darwinism, utilized to justify colonial expansion and racial typecasting, and Ratzel, as Hitler's geographer, was influential in German expansionism.
Today, environmental determinism is disfavored, replaced by ideas of environmental influence (where nature shapes but does not mandate human activity), and complex multi-directional influences between nature and society. Carl Sauer's work was important in showing how humans change nature as well as nature shaping humans.