Why do geographers study human systems and human environment relationships?

Geographers are people who study the earth and all things that exist on earth. One study of the geographers is the human system. In order to know what the needs of human are, they also study the human environment and the relationship of human to the environment. How human reacts to the changes that is happening in the environment. How people depends on the environment and how environment affects the life of every human. By this study, they can foresee some possible outcome and discover some important things that can change our lives.