Exert from the foreword: “As Darwin saw it, natural selection is the fundamental process that accounts for the evolutionary change of organisms through the generations and for the adaptations of organisms. In outline, Darwin’s argument is simple. Organisms with hereditary variations that make them well adapted to the environments in which they live are likely to leave more descendants than organisms with less adaptive variations. It follows that hereditary variations that enhance adaptation will gradually increase in frequency from generation to generation and eventually replaces adaptive alternative variations. Thus, natural selection is a process that explains the occurrence of evolution as well as why living organisms are adapted to their environments and ways of life.”