When discussing the ideas in this book with others, I have come to recognize a certain puzzled look. It usually involves a knitted brow and occasionally a sideways tilt of the head. Then a hand rises and objections follow. One of the most common objections has to do with the definition of evolution: “I think of evolution as speciation,” people have said. “Are you saying people create new species? Didn't speciation take millions of years to accomplish, and didn't it finish a long time ago?” Another common protest has to do with the mechanism of evolution: “Darwin showed that evolution happens because of natural selection. What you are describing is artificial selection, so it does not qualify as the same thing Darwin described at all. That is not real evolution.” If you have similar questions or objections, this chapter is for you.

The goals of this chapter are (1) to explain why processes described in this book qualify as evolution, (2) to provide a primer (or refresher) on ideas about evolution that will be essential for understanding the rest of this book, and (3) to clarify terminology. We will look at current concepts of evolution, list essential elements, and watch those elements at work in the wild and in everyday life. We will clarify the meanings of terms such as natural selection, artificial selection, anthropogenic evolution, drift, sampling effect, and extinction. If all these ideas are familiar to you, please feel free to skip to the next chapter.