Chapter 5 expands on concepts related to classification introduced in Chapter 4. Humans are primates, a group that also includes prosimians, monkeys, and our closest living relatives, the apes. We are also mammals and vertebrates. This chapter focuses on general issues of mammalian and primate taxonomy, beginning with an expanded explanation of classification methods. Humans and their place in the classification system are specifically discussed.

Following this introduction, the chapter then considers humans as animals, chordates, vertebrates, and mammals. Mammalian features and characteristics are emphasized: reproduction, temperature regulation, teeth, skeletal structure, and behavior. These features will be important to know for later chapters when discussion progresses to the fossil record and identifying features of primates, then hominin.

The final part of the chapter examines primate characteristics, behavior, and social groups. These distinguishing physical and behavioral features further refine an understanding of how primates and ancestral hominin are identified and classified. Specific behavioral characteristics of non-human primates and relevance to human behavior are also considered.