A brief historical perspective on demography, distribution, abundance, and population dynamics is essential for an appreciation of the paradigmatic shift advocated in this book. Such a view is provided in various sources by experts, which can be consulted for details, and from which I have constructed some of the scenario presented here. In their Principles of animal ecology, W. C. Allee, Alfred E. Emerson, Orlando Park, Thomas Park, and Karl P. Schmidt (1949) devoted Section I to the history of ecology up to 1942. Their authoritative view is valuable because they had experienced first hand much of the development of ecology during the twentieth century. Two books published in 1954 also became classics in ecology: David Lack's The natural regulation of animal numbers and The distribution and abundance of animals by H. G. Andrewartha and L. C. Birch, providing these authors' perspectives on the state of the field in the mid 1950s. LaMont Cole (1957) wrote an excellent review on the history of demography, and Tamarin (1978), in the Benchmark Papers in Ecology series, provided a balanced treatment on Population regulation with readings covering major points of view through the controversial 1960s and into the early 1970s. From the early 1960s I have worked in this field of ecology, so I will provide a more personal view of developments since then. First, I will concentrate on how ideas developed into the 1950s based on field studies and other empirical methods.