<P>At once a spirited defense of Darwinian explanations of biology and an elegant primer on evolution for the general listener <I>What Evolution Is</I> poses the questions at the heart of evolutionary theory and considers how our improved understanding of evolution has affected the viewpoints and values of modern man.</P><P>With rare clarity Mayr poses the questions at the heart of evolution — What is the evidence for evolution on earth? What is the origin and role of organic diversity? — and describes in refreshingly nontechnical language how the search for answers has over the years revealed solutions to the most challenging problems posed by evolutionary theory.</P><P>In a provocative final section Mayr considers how our improved understanding of evolution has affected the viewpoints and values of modern man.</P>
