In this chapter, Wilson first defines the biosphere. Compared to Earth’s overall immense mass, the biosphere makes up a thin zone and includes the land, sea, and atmosphere where organisms survive. The author argues that humans believe themselves to be “rulers of the biosphere and its supreme achievement” (12). Humans also feel “entitled to do anything to the rest of life” (12). Wilson makes clear that he does not buy into the notion that nature should serve humans.

Wilson points out that humans are not self-sufficient and “remain organisms absolutely dependent on other organisms” (13). For example, we cannot survive without water, food, or shelter. Humans, like other organisms, are also are a product of natural selection. Charles Darwin, an English biologist, geologist, and naturalist, first expounded the theory of natural selection. It is the process whereby organisms better adapted to their environment tend to survive and produce more offspring. The biosphere acts as a “shield” protecting all organisms, including humans. Due to human activity, including the introduction of non-native species to new environments, the biosphere is destabilizing. According to Wilson, humans must remember: “The biosphere does not belong to us; we belong to it” (16). We have the ability to protect the biosphere, and we must do so or risk its irreversible destruction.