Chapter 2 is concerned with understanding human biological variation and evolution. It provides a brief background in molecular and Mendelian genetics. This is necessary to understand the evolutionary process on both an individual and population level. The goal is to seek reasons behind evolutionary change and understanding long-term patterns of evolution over time. The emphasis is less on the actual biochemistry and more on molecular genetics as the concept of information transmission (cell to cell, parent to child). The current status of the Human Genome Project is discussed.

Mendelian genetics is then covered emphasizing the basic principles of inheritance. While examples are drawn from familiar discrete traits, attention is also given to the genetics of complex traits. Mutations are discussed in terms of "errors" in information transmission. The "nature-nurture" debate is introduced here. An optional primer on cell biology is provided at the end of the chapter, providing greater information if desired on cell structure, mitosis, and meiosis.