The life cycle is the socially defined, age-related sequence of stages individuals pass through beginning with birth and ending with death. Underlying the life cycle is the recognition that humans are biological organisms that are born, mature, and die. As with other biological organisms, reproduction is a key feature of human maturation, ensuring the persistence of the species.
FORMS OF THE LIFE CYCLE
In very simple societies, the life cycle may consist simply of two stages—infant and adult. Once infant survivorship is reasonably certain (typically by about age 6) young persons participate in adult work life, doing jobs that are suitable to their physical strength or as apprentices learning more complex skills. Work continues until death. But such a simple definition of the life cycle rarely endures the complexities attendant on reproduction. Among women, physical maturation separates childhood from the age when childbearing is possible. For men, marriage entails responsibility for supporting a family and guaranteeing their safety, something that typically must await completion of puberty and the achievement of economic viability. Even in societies with a low life expectancy, some adults survive to the point at which they are no longer able to work.
These examples illustrate how individual social roles (such as work or having a child) define a human life cycle that is more complex than the biological minimum. These roles are almost always defined as age related, and typically are also different for men and women. The concept of age-appropriate roles enables societies to regulate or prohibit behavior that is occurring ”too early.” These societies also use the concept of age appropriateness to move individuals along in their maturation process, urging the adoption of a social role before it is ”too late.”
Age. In most societies, chronological age is a handy proxy for maturity, with particular age groups assigned certain responsibilities and rights. In some societies (such as in postwar Japan) the age appropriateness of the sequence of social roles is rigorously defined by cultural values and enforced by social institutions (such as schools or labor markets) which impose strict age rules on entry, promotion, and exit. In African age-set societies the system is even more rigid: Groups of persons born during contiguous years are defined as members of a particular age group (age set). These age sets experience together the transition from one life cycle stage to the next, under community traditions that specify the formal requirements and ceremonies necessary to move from one set of social roles to another. Typically this process is one of considerable dispute—the moving up of one age set causes all members of the society to move to the next life-cycle stage so that one group will have to give up preferred adult roles for old age.
Age Stratification and Cohort Succession.
Individual childbearing and the aging of individuals ready to assume new age-appropriate roles drive the societal process of age stratification and cohort succession (Riley 1985). The more complex the society, the more social roles that need to be filled. Most such roles in the society are gender linked and age stratified (defined as age appropriate and differing markedly from age to age). The use of chronological age rather than maturational capacity to construct the age-stratification system mandates that individuals as they age will move from one age stratum to the next, with an implicit societal mandate of assuming new roles. The birth of persons in contiguous years (what demographers call a ”birth cohort”) reinforces the dynamic of the age-stratification system by producing new role entrants who can only be accommodated by the movement of all age strata to the next life-cycle stage. In the United States we can see this system at work in age-graded schooling: When one group achieves high school graduation, the remaining students are promoted from one grade to the next. This opens entry-level spaces for a new cohort to begin school. Universities develop a variety of incentives to get elderly faculty to retire so that newly trained and presumably more innovative faculty can be hired.
The Life Cycle in Social Science. To summarize, the lives of humans from birth to death are organized as socially defined, age-related sequence of stages individuals pass through over their lifetime. These stages are inherently age related, with individuals maturing from one life-cycle stage to the next. Reproduction is a key feature of human maturation, distinguishing the roles of men and women and linked to the age-related biological capacity to bear children. An ongoing flow of new births ensures the persistence of human populations. Accommodating these new members of society also drives the dynamic of life-cycle change by necessitating the movement of earlier cohorts to more mature positions in the age-stratification system. This process of cohort succession is, in turn, a major source of societal innovation and change, as new cohorts take a fresh look at the content and form of the age strata they have just reached. In this way, the life-cycle concept links individual aging, the organization of roles in society, reproduction, and societal innovation and change.
CONTRIBUTIONS OF THE LIFE CYCLE
The life cycle has proved to be a powerful and flexible tool for the analysis and explanation of human lives, used by researchers from a number of different disciplines. Anthropologists have focused on the process of socialization by which one age stratum is taught to succeed the next over the life cycle, linking social roles to the cultural system of beliefs and values. Age-set societies have been intensively described because of the very visible structure of age stratification and the explicit group-level patterns of life-cycle stages. Rites of passage are the symbolic counterparts of age-set transitions from one age stratum to the next, marking the personal change and announcing it to the entire community.
Developmental psychologists have used the life cycle as an organizing principle for specifying the steps in human development. The process of aging drives this principle, which is defined and structured by social organizations and individual roles. A prominent example is Erikson’s eight stages of life (1968). In this model, psychosocial stages are identified, consisting of times in which opportunities for success and the risk of failure are present. For example, the young adult stage is marked by the capacity for intimacy versus isolation, and integration, while a choice between wisdom and despair marks old age. The passage from one of the eight life stages to the next is regarded as a turning point that is fraught with vulnerability and heightened potential.
The life cycle forced gerontologists to recognize that the study of old age in isolation from the prior life cycle is not viable. The economic resources, health, knowledge, and family situations of the elderly result from the cumulating of life-cycle experiences. These same factors influence the chronological age at which people take on characteristics of the aged. Gerontology as a field has expanded to encompass the dynamics of life-cycle transitions. Immediately noteworthy when one adopts this aging approach is the fact that persons currently reaching old age have prior life-cycle experiences that may better prepare them for becoming old than did prior cohorts. The sociological interest in aging motivates gerontologists to attend to both the lifelong process of aging and potentially dramatic intercohort changes in successive cohorts of the aged.
Life Cycle Squeeze. Economists have relied on the life cycle and the gendered division of labor to study household and family economics. Wages follow a curvilinear pattern over the life cycle: Young workers receive the lowest wages; wages increase over the life cycle, peaking at midlife; while workers older than 55 tend to experience stability or even a decline in earnings. Women’s earnings show much less of an age profile, both because young women frequently interrupt or reduce labor-force involvement when children are born, and because women’s jobs are less likely to take the form of careers in which progression upward from one job to the next occurs.
This life-cycle pattern of earnings does not always match family income needs. Early in the life cycle, children are net consumers of income. As societies require a more educated population, youth and adolescents also become net income consumers. While this has long-term payoff for the society and for new cohorts of workers, it increases the costs and reduces the economic value of children to families. These costs most often occur when workers are at the low point in their earnings. Later in the life cycle, earnings are higher but the cost of a college education and assisting children in getting started also may be high. At the same time, elderly parents may become a social and financial obligation for children, leading to the powerful concept of the ”life-cycle squeeze.”
Cohorts facing this new mix of obligations with the traditional earnings profile have acted to reduce desynchronies in the stages of the life cycle.
Credit mechanisms (for example, long-term mortgages, home equity loans to pay for college education) smooth income and costs over the lifetime. The intercohort upgrading of the situations of the elderly in the United States means that parents become dependent on their adult children at an older age. The government has intervened to bear much of the cost of the elderly. Life-cycle pressures have also resulted in intercohort changes in the content of the life cycle of men and women— delays in marriage and first birth, a reduction in family size, the shift to two-earner families, and increases in divorce.
Sociologists have devoted considerable attention to the cohort-level study of life-cycle transitions. Turning points imply inevitability and potential crisis. Sociologists study the form of the transition (for example, cohabitation or marriage), whether or not a transition occurs (for example, parenthood), and the average age and variability in age of a transition across individuals of the same cohort. This approach recognizes (building on the idea of an age-stratification system) that a variety of transitions are crosscutting (for example, work and marriage, birth of a first child and marriage).
The Life Cycle in Demographic Models. It is the educational, labor-force, and family outcomes that interest demographers. The study of family life has proceeded with the measurement of marriage and then the progression to first birth, second birth, and so forth (taking into account both the number and the timing of births). A special tool called parity progression analysis has enabled demographers to identify turning points in fertility decisions, and how these have changed across cohorts. This approach to the study of demographic life-cycle stages, along with the recognition that fertility is inherently a biological process, has led demographers to develop population models of fertility that take into account marriage patterns, the level of marital fertility, and birth limitation. The life-cycle model also has informed research on age patterns of migration, and its regularities across time and place.
The life-cycle perspective has produced a variety of unexpected results. The American baby boom of the late 1940s and the 1950s was largely due to the temporal coincidence of childbearing by successive cohorts, rather than to a dramatic increase in family size. During the baby boom, women 35 and older made up childbearing that had been delayed by the Great Depression and World War II. Women reaching adulthood during the baby boom years responded to favorable economic conditions for young families by having their first child at a younger age and having subsequent children more quickly.
Family Life Cycle. Family sociologists made a great leap in developing the family life cycle as a variant form of the life cycle (Glick 1965). The family life cycle is unusual in that it focuses on family formation and childbearing, ignoring such linked transitions as completion of schooling and work. The family life cycle stretched the life-cycle model to incorporate role changes associated with the transitions of other individuals. (For example, a husband makes the transition to marriage at the same time as the wife. Only when all children grow up and leave the home does the family experience an ”empty nest.”) The family life cycle became a predominant research paradigm in family studies.
The family life cycle can be a useful analytic tool for understanding the succession of family roles in populations in which families predominate over individual interests. The family life-cycle model works only for those populations in which marriage precedes childbearing, the ages of each are specified within a narrow time band, and marriages do not end (by widowhood or divorce) before the last child leaves home.
None of these assumptions are even approximately satisfied for the United States. First births often precede marriage (among blacks this is the typical pattern). Many couples postpone child-bearing within marriage, and as many as one-fifth remain voluntarily childless. Over half of all first marriages end within twenty years. Remarriage often follows. This degree of inconstancy in household membership begs the question of how to define the family whose life cycle is being described, and followed over time. The family life cycle is now widely regarded as a useless conceptual tool because it utterly fails to capture the realities of contemporary family life.
LIFE CYCLE AND LIFE COURSE
The life cycle defines pathways for individuals as they age from birth to death, specifying usual expectations about the sequence and timing of roles (for example, a first birth when married and at age 18 or older). Empirical research that uses the life cycle to analyze the lives of population cohorts typically find that these life-cycle stages, as socially defined and demarcated, follow expected patterns.
Research on the transitions of individuals over their lifetime has demonstrated the essential incorrectness of this supposition. For many individuals, childbearing precedes marriage, parenthood occurs when the parents are not yet economically self-sufficient, and adult children return to their parental household after they have assumed (and sometimes failed at) adult family and economic roles. This has caused researchers to consider whether new life-cycle patterns are emerging, or whether a group of individuals is somehow ”deviant” from the established life cycle.
Clearly there have been marked intercohort changes in the life cycle, reflecting the varying opportunity structures of time periods and cultural change. For example, the availability of the GI Bill for college education and interruptions in education associated with wartime military service allowed many men to marry and have children before they finished school and became economically established. In recent cohorts of young women there is a decreasing emphasis on the necessity of marrying before having a child, and, on the part of all adults, a greater readiness to assist rather than condemn single mothers.
An even greater source of departure from the population life-cycle model is the large number of persons in each cohort who never make a transition to a given life-cycle stage (e.g., those not marrying or not becoming parents), who retreat from a given life-cycle stage to an earlier stage (e.g., fathers who divorce and abandon their families, and retired persons who return to work), and who are not part of the typical life cycle (e.g., the severely disabled, persons who die before reaching old age). These features of the life cycle vary by such primary sociological variables as social class origin, education, race and ethnic group, and place of residence.
Among Americans the seeming conformity of cohorts to the life-cycle patterns masks the overwhelming number and frequency of individual departures. In this situation the life cycle seems to be a far less useful analytic device. Social scientists have adopted in its place the more sophisticated and flexible ”life-course” perspective. The life course sees individual lives as a series of trajectories (such as family or career) that are socially recognized and defined. Age is significant in the life-course approach because it is an indicator of biological aging and locates individuals in historical context through birth cohorts. The social meaning of age helps define life-course pathways (recognized routes of trajectories) through age norms and sanctions, and social timetables for the occurrence and order of events. Transitions (leaving home, getting a job, marrying) define trajectories. Interlocking transitions and their trajectories lead to multiple roles that define the individual life course from birth to death.
Because of the emphasis on variations in trajectories across individuals, every individual life course has the potential to be unique. Much of the population-level research with the life-course model has focused on transitions—the proportion of cohorts making a transition, average age at transitions, and the range of ages at which cohorts typically make these transitions. The life cycle gives analytic meaning to these life-course transitions by providing a standard against which to measure how transitions vary across cohorts and differ among key population groups within cohorts.
Causal analyses of the life course are usually done at the individual level, typically with a class of statistical methods called ”event history” or ”hazards” models. These statistical methods enable investigators to examine empirical data on individual transitions, modeling the age-graded pattern of transitions from one social role to another and identifying ”heterogeneity” (sources of variation in transitions at the individual level).
The Necessity for Life Cycle in Studies of the Life Course. This points to a dilemma for social scien-tists—the very life-cycle model that the life-course approach undermines provides the essential theoretical framework that gives meaning to individual behaviors. Because social scientists are part of the societies they study, they also carry in their own heads models of the life cycle—what should be done when it should be done, and what denotes success or failure. The life-course perspective on pathways that define typical trajectories and the social meanings of age capture the essence of a life-cycle model. The apparent tension between the life-cycle and life-course conceptualizations is perhaps overdrawn.
The life-cycle model retains many valuable features that are typically missing from life-course studies. Life-course transitions focus on individuals at particular times during their lives (adolescents becoming adults, older workers becoming disabled or retired). While past experiences and current opportunities are often included in life-course models, the life-course perspective has not lent itself well to viewing transitions at particular ages in the context of the lifelong process of aging, an idea that is innate in the life-cycle approach. Economic research, which is theoretically driven and uses a life-cycle model, has been most successful at integrating findings from transitions at a given age into the lifetimes of individuals.
With such an approach it is also possible to simulate the effects of changes in transition rates (resulting from heterogeneity in rates and changes in population composition) on cohort-life cycle behaviors. The life-course perspective typically views cohorts as proxies for age-specific experiences with the social structure; the life-cycle model brings a necessary emphasis on intercohort change as a method of social innovation.
The life-course approach emphasizes variability in transitions and trajectories to such an extent that many social scientists have neglected regularities and consistencies in behaviors, and the advantages they may entail. There is a great deal of research on adolescent mothers but relatively little research on why married women have children. There is more interest in unemployment and poverty than in the advantages of paid employment and career lines. While children of welfare mothers disproportionately go on to become welfare mothers themselves (the subject of much research), the overwhelming majority grow up to be free of welfare dependence (a subject about which we know very little). Nor do we have a strong explanation of the reasons persons marry. The life-cycle approach draws attention to these questions of social organization, and the matching of individual behaviors to necessary social roles.
FUTURE OF LIFE CYCLE
The life cycle thus remains a viable and valuable conceptual tool for studying human lives. In much of the developing world, transitions and trajectories are sufficiently universal and age regulated that the life-cycle model remains a highly useful tool for social science. In societies where such regularities are no longer the norm, the life-course approach is the more appropriate. To be meaningful, the life course must be interpreted in light of the life cycle—the underlying beliefs about the shape and timing of the life stages to understand the social meanings of age, identify alternative pathways for life trajectories, draw attention to the strong regularities in transition behaviors and linkages, and direct attention to intercohort stability and change. The concept of the life cycle thus will continue to be a valuable and necessary tool for the social sciences.
