What Evolution Is
Ernst Mayr's work on the "modern synthesis" of systematics and population genetics was one of the major contributions to evolutionary theory in the twentieth century. Now, some sixty years later, the biologist, historian, and philosopher of science has distilled almost eighty years of research into a volume for the non-specialist.
Mayr had three different audiences in mind in writing What Evolution Is. While all three audiences must share a level of sophistication in understanding science, as evident by his writing style and reliance on a fairly technical vocabulary (he does include an extensive glossary), they differ in their acceptance of evolution. His target audiences are those who accept Darwinian evolution, but want additional and reliable information on the subject; those who accept evolution as a concept, but are not convinced that Darwin's flavor of evolution is the correct one; and creationists curious about what their scientific enemies believe.
The book is divided into four sections. The first defines evolution and provides evidence for it. The second focuses on the mechanisms of evolution, including natural selection. In the third section, Mayr tackles the definition of what is a species, one of the fundamental issues of evolutionary biology, and one for which it has been very difficult to reach a consensus. The concluding section reviews the state of knowledge of human evolution.
In addition to the glossary and fairly extensive bibliography, Mayr includes two appendices. One consists of short critiques of criticisms of Darwinian evolution, ranging from creationists to Stephen Jay Gould's theory of punctuated equilibria. The second contains answers to "twenty-four frequently asked questions about evolution."
Although the general reader must remember that not every evolutionary biologist will agree with all of Mayr's conclusions and judgements, it is a treat to study evolution with a scientist of Mayr's distinction.