What are the "four vital physical process that create food" that Pollan focuses on in his book Cooked?

In his book Cooked, Michael Pollan investigates the four main physical processes that are used to cook food: fire, air, water, and earth (fermentation). He starts with fire because, as he says, "fire is the first and most fundamental form of cookery" (page 29). In studying cooking with fire, he wants to "learn something about the deeper meaning of this curious, uniquely human activity called cooking" (page 29). He wants to learn how to cook without gadgets and to strip the process of preparing food down to its fundamentals. Humans' control of fire is, as he points out, what enabled us to advance our civilization. In the chapter on fire, Pollan describes ancient and more modern forms of cooking with this technique. 

In later chapters, Pollan uncovers and examines the processes of cooking with air (baking bread, primarily); water (braising); and the earth (fermenting). He believes these are essential and ancient processes that return us to the fundamentals of what it means to prepare food. The author is interested in examining these processes because Americans spend so little time actually cooking and cleaning today--an amount of time that has declined drastically since his childhood in the 1960s. He wants to go back to the fundamentals of cooking to restore healthfulness and community to the process of eating.