Life Course

The life course is both a theoretical perspective and a concept (Elder and O'Rand). The theoretical perspective provides an organizing theme for research on aging, emphasizing aging as a process occurring within historical time. Because theoretical perspectives guide research questions and analysis designs, emerging perspectives such as the life course perspective are particularly exciting because they provide new ways of looking at issues and problems.

Within this perspective, the concept of the life course refers to the successive role statuses held by individuals as they age. By focusing on social roles, this concept targets the sociological dimensions of aging, viewing these life-long processes as a succession of interactions between the individual and work, family, education, and other institutions. It posits that much of what defines various life stages, such as when one becomes an adult, enters midlife, or is defined as "elderly" is shaped by these institutions and their associated roles. It is the patterns and sequences of these various roles, such as student, parent, or worker that we refer to as the life course.

The concept of the life course can be distinguished from several related terms. The term life cycle is often used interchangeably with life course, but a more strict definition of life cycle refers to distinct stages, maturation, and generational replacement. It is more applicable to populations, organizations, or groups such as the family, which undergo a series of stages (O'Rand and Krecker). The concept of life span is applicable to individuals and refers to the duration of time from birth to death. While all three concepts reference temporal processes, only the life course concept taps the changing social roles that individuals hold as they age.

Understanding the dynamics of social roles making up the life course has required new concepts. The two most important are transitions and trajectories (Elder and O'Rand). Transitions are the short-term changes in roles such as getting married, becoming widowed, or changing jobs. Trajectories are the longer-term patterns such as the work career or family history. Trajectories are made up of various transitions, but also provide the larger context that gives individual transitions their meaning. For example, an exit from a full-time job for someone in their early sixties may or may not be a major transition in the life course. Whether or not it is defined as one's "retirement" will depend on its location in the larger trajectory of the work career.

Separating variation that is due to age, historical period, and birth cohort is central to understanding individual aging in changing societies. Age variation refers to the biological or social maturation that occurs as people age, such as age-related physical changes. Variation by historical period refers to large-scale social change and events such as wars, economic downturns, and changing divorce rates. Although the influences of these macro changes are widespread, their impact on individuals may vary depending on where they fall in the person's life course. For example, Elder's research shows that the influence of the Great Depression depended on the individual's life stage in the early 1930s. These varying effects in turn produce variation across birth cohorts as each cohort develops within a unique set of historical conditions (Ryder).

While age, period, and cohort are conceptually distinct, all are marked by the passage of time. Differences across age groups may reflect maturational changes or birth cohort variation. Because both types of variation are measured by an individual's age, research designs often cannot distinguish these two types of variation. Even studies following multiple cohorts over time cannot completely separate all three sources of variation. More precise measures of at least one of these effects, such as how individuals experience a key historical event, are needed to fully separate age, period, and cohort influences (Hardy).