This volume is a unique review of the theories and mechanisms, as opposed to the mere patterns, of alternative life-history styles in animals and includes examples from detailed field studies of invertebrates and vertebrates which test and contest current theories. Fresh and controversial insights are provided on the consequences of bifurcation for epigenesis and evolution, and a suggestion is made that new paradigms are emerging which emphasize the harmonious self-organization of natural systems (cells, organisms, communities and ecosystems).