Life stages analysis has focused on the changing definition, demarcation, and social experience of the phases of individual development. It has shown that over the course of American history the definition of the life stages has grown more ,conceptually precise and more completely organized institutionally, and that the transition between stages has become more abrupt and disjunctive.
The family cycle approach has concentrated on changes in the basic phases through which families go from the time they are formed to the time they are dissolved. It has revealed the impact of such important demographic developments as declining fertility rates, increasing life expectancy, prolonged residence of children in their parents home, and the decline in the practice of boarding on the familial experience of individuals.
. Social and Cultural Construction of the Life Stages
The major differences between modern conceptions of the life stages and early notions of the "ages of man" are that contemporary conceptions of childhood, adolescence, middle age, and old age are much more age specific and conceptually precise, and that the transition between stages has grown more disjunctive. A variety of factors have contributed to a more precise formulation of the life stages. These include scientific and medical discoveries that identify childhood, adolescence, and old age as biologically and psychologically distinct stages of life, with their own needs and characteristics.