John Tyler Bonner, a major participant in the development of biology as an experimental science, is the author not only of important monographs but also of a wonderfully readable book, Life Cycles, which is both a personal memoir and a profound commentary on the central themes of biology. This volume of essays presents new material that extends the concepts from Life Cycles and his other writings. Its originality lies in comparing key basic biological processes at different levels, from molecular interactions through multicellular development to behavior and social interactions. The first chapter in the book discusses self-organization and natural selection; the second, competition and natural selection; and the third, gene accumulation and gene silencing. The fourth chapter examines the division of labor in organisms at all levels: within the organelles of a cell, within groups of cells in the guise of differentiation, within groups of individuals in an animal society, and within our culturally determined human societies. The work closes with a charming personal history of sixty years of changes in the field of biology, including the transformation in the ways that research work is funded. Originally published in 1996. The Princeton Legacy Library uses the latest print-on-demand technology to again make available previously out-of-print books from the distinguished backlist of Princeton University Press. These editions preserve the original texts of these important books while presenting them in durable paperback and hardcover editions. The goal of the Princeton Legacy Library is to vastly increase access to the rich scholarly heritage found in the thousands of books published by Princeton University Press since its founding in 1905.