Age Differentiation and the Life Course

Age has long been recognized as a basic element in social structure and the life course, but we have only recently achieved some appreciation of its diverse meanings and implications. To interpret the effects or correlates of age and birth year we must specify the variables they represent. complexity of this task is suggested by the following temporal dimensions and locational properties that are derived from age data: (a) the individual life time or life span from birth to death-chronological or developmental age as an approximate index of stage in the aging process; (b) the social timetable of the life course (e.g. entry into marriage, retirement), which is defined by age criteria in norms and social roles; and (c) historical time in the course of social change-birth year or entry into the system as an index of historical location.1 focal point of the lifetime framework is the inevitable and irreversible process of aging; that of social time, age differentiation in the sequential patterning, and configuration of social roles; and that of historical time, cohort membership, differentiation, and succession, with their implications for life histories, aging, and social change. Each temporal focus is associated with a distinctive tradition of theory and research: lifetime, BUhler (1935), the biological cycle of life as reflected in attitudes toward life (see also BUhler & Massarik 1968); social time, theoretical analyses by Linton (1942) and Parsons (1942), and Eisenstadt's (1956) influential synthesis of ethnographic materials on age differentiation; and historical, Mannheim's (1952, orig. 1928) essay on The Problem of Generations. Continuities within the social time perspective are illustrated by theoretical formulations of social transitions in the life course, from Cottrell's (1942) propositional inventory on adjustment to age