Theories of aging – Anthropology by K.V RAMESH

Introduction

Theories of ageing help to recognize and understand the factors responsible for the age associated changes. The future of ageing research is expected to pay even greater attention to theory, especially with an interdisciplinary approach. Age related changes do not occur uniformly among the individuals, rather they are controlled by genetic, environmental & socio-cultural factors. Theories related to ageing have been analyzed by biologists, sociologists, psychologists, economists, feminists and others.

A. Biological Theories:

These theories explain specific biological mechanisms that cause aging. Aging affects different body systems and tissues and it is a long-term process. Understanding the aging process is important to understand and treat age-related diseases. These theories explain the cause of decline of physical functions of the body. Theories explaining the biological basis of human aging are either stochastic theories that suggest aging to be primarily the result of random damage to the organism, or they are programmed theories which says that senescence is the result of genetically determined processes. According to Shock (1997), biological theories can be classified as primary, secondary and tertiary ageing. Theories that focus on genetic causes are primary ageing theories e.g. prog rammed ageing, free-radical and theory of errors etc. Theories that assign ageing to pathological, degenerative causes and natural wear, with the passage of time are included as secondary ageing like wear and tear theory, cross-linking theory etc. Tertiary ageing postulates that the changes are due to the degeneration of some or of all the physiological systems of the body like decreased immunological function, endocrine system transformation etc.

Primary Theories of Ageing

Programmed aging theory states that old age appears and develops according to the hereditary information and content of the genes (Yuste, 2000). Cell multiplication limit theory given by Hayflick (1974, 1999) argued that studies on old age are much about lengthening the years of greatest energy and activity of the human being. Hayflick (1974) discovered that the number of divisions of normal cells is not unlimited in its regeneration, but restricted, which means that no matter how much medicine progresses in saving life, unlimited life expectations can never be achieved by it (Yuste, 2000).
Theories of endogenous aging of cells have research evidences according to which, cell functions gradually diminish with advancing age. These, upon aging, are less prone to nutrition, to stanch wounds, and to eliminate waste, which accumulates continuously and severely. The reason for these failures in cell behavior is unknown, and has given rise to diverse hypotheses, all of which focus on DNA failures. There are three main theories on endogenous aging of cells. Free-radical/ Peroxidation theory states that the free radicals are very reactive molecules derived from the monovalent reduction of oxygen. It is responsible for the excess of super oxidized free radicals, for severe anomalies in the immune function and for deficient emission to the cell nucleus of adequate stimuli.
Theory of errors was introduced by Orgel (1973). According to this theory death of the cells, and consequently senescence, are outcomes of the errors that arise in some link in the chain between DNA and the final protein required. With aging, cell function diminishes gradually and constantly (Yuste, 2000). Theory of the critical threshold of accumulated errors proposes that cellular death occurs when defense systems are no longer able to resist the continuous alterations in cell components. The theory does not explain how, or why, the level of failures increases (Toussaint, 1993). Accumulated waste theory states that there is an accumulation of waste when the original cellular capacity to eliminate it falls apart, with which the oxidation rate decreases resulting in loss of functions and natural activity of the cell. There is a positive correlation between aging of the subject and progress of cell dissipation due to piling up of sub-products and cellular waste.

Secondary Theories of Aging

These theories argue that pathological and degenerative causes are responsible for changes in the cells, which could be due to very poor oxygenation, or infiltration of chemicals, or to poor nutrition, that reduce their competence and provoke cellular death which is aging. Some of the examples of these theories are Wear and tear theory, Theory of accumulation of deleterious molecules in blood, Deprivation theory and Cross-linking theory etc.

Wear and tear theory explains aging of the cells as a consequence of continued exposure throughout life, to toxic factors, from both endogenous and exogenous sources. This results in progressive detriment to the capacity for survival. However, human body has a self-repair system (Yuste, 2000).
Theory of accumulation of deleterious molecules in blood states that there is an accumulation of toxic molecules in plasma, which hinders cell development. This accumulation of pigments impedes the diffusing potential of the cell membranes. However, there is lack of research evidences in support of this theory.
Cross-linking Theory is based on extracellular and intra-cellular post translational molecular modifications that are generated with age. Bjorksten (1968) was the first to speak of certain connections, macromolecules which over the years are formed by binding the component parts of different molecules together forming loops between them. These form rigid, lasting joints which keep them from working properly or being restored.

Tertiary Theories of Aging

These theories emphasize the degeneration of some of the control systems or mechanisms, such as the immune, neuroendocrine, cardiovascular or nervous system, so there are diverse theories depending on the system described.

Decreased immunological function theory is supported by Robbins (1990). According to this theory the quantitative and qualitative production of antibodies is gradually incapacitated, so the elderly are more susceptible to infection, later, as age advances, there is a propensity to more development of autoimmune diseases and finally, an acute decrease in the function of T-lymphocytes, with respect to age. The Endocrine system transformation theory states that the structure of endocrine system is made up of various glands such as the thyroid, suprarenal and gonads. These glands are controlled and governed by the anterior pituitary. This theory is supported by several different authors including Finch and Hayflick (1977). The theory of changes in the endocrine system sustains that the main cause of old age, is chemical alteration in the organism. Thyroid gland deterioration theory believes that the alteration of this gland determines aging.
The cardiovascular aging theory supports that majority of deaths, are due to a problem in the heart. According to this theory, the cardiovascular system is directly responsible for the aging process due to gradual dissipation and degradation of the blood vessels, which is translated into arteriosclerosis resulting in diminished blood supply.
According to Multifactorial theory of aging the process of aging can be attributed to the multiple factors including an excess of superoxidized free radicals due to endogenous enzymatic reactions and environmental attack for severe anomalies in immune functions and deficient emission of the proper stimuli to the cell nucleus (Olson, 1987).
Stress Theories of Ageing : These theories argue that excessive physiological activation have pathological consequences. Hence differences in neuroendocrine reactivity might influence patterns of aging. The focus of such theories is on the possibility that neuroendocrine reactivity might be related generally to increased risk of disease and disabilities. Stress mechanisms are thought to interact with age changes in the Hypothalamic Pituitary Adrenal (HPA) axis, which is one of the body’s two major regulatory systems for responding to stressors and maintaining internal homeostatic integrity. Gender differences in neuroendocrine reactivity are also suggested because of the known postmenopausal increase in cortisol secretion in women not treated with estrogen replacement therapy ( Finch and Seeman, 1999).

The error theory, wear-and-tear theory and error accumulation theory ignore the restorative capacity of the organism. The critics have pointed out that biological theories do not take into account cohort or generational differences. Only the programmed ageing theory addresses individual differences. None of the biological theories for ageing appear to be fully agreeable (Davidovic et al., 2010).

B. Psychological Theories

Developmental Tasks Theory states that a developmental task arises at or about a certain period in life of the individual, successful achievement of which leads to his/her happiness and success with later tasks, while failure leads to unhappiness in the individual, disapproval by the society, and difficulty with later tasks (Havighurst, 1948). All of these tasks have biological (physical maturation), psychological i.e. aspiration or values, and cultural (i.e. expectations of society) basis. Havighurst (1973) has described six developmental stages or age periods in total, each with its own developmental task.
Psychosocial Theory of Personality Development identifies eight stages of personality development, each with its own characteristic crisis that arises out of the conflict between two opposite tendencies (Erikson, 1950). The developmental task of each age period is to resolve its conflict, which requires the integration of personal needs with the demands of society. The successful resolution of each conflict leads to developmental strength in terms of a new virtue. Failure, however, to deal adequately with a task is damaging to personality development. Erikson’s psychosocial stages of development are not tied closely to specific age periods.
Personality Theory of Age and Ageing is given by Neugarten (1968) and associates and they studied the life cycle with two theoretical emphases. The first emphasis is on the timing of events in the lives and roles of individuals. Life events, such as marriage or parenthood, are normatively scheduled as, they are expected to occur within certain ages and in a certain sequence and they bring in changes in self-concept and identity. However, unexpected events (like accidents) or age-normative events that occur “off time” (like early widowhood) may have negative developmental consequences, such as life crises. The second emphasis is on the study of personality type as predictor for successful aging. Aging is viewed as a process of adaptation in which personality is the key element.
According to Need theory of ageing given by Maslow (1968), there is hierarchical order of an individual needs. As each succeeding layer of needs is addressed, the individual is motivated to look to the needs at the next higher level. Maslow’s fully developed, self-actualized person displays high levels of all of the characteristics like perception of reality; acceptance of self, others, and nature; spontaneity; problem-solving ability; self-direction; detachment, desire for privacy; identification with other human beings; satisfying and changing relationships with other people; a democratic character structure; creativity; and a sense of values (Maslow, 1968; Fig 1). However, the Maslow’s ideal selfactualized person is probably only attained by about 1% of the population (Thomas, 1977).
According to personality and ageing theory, ‘Personality’ is defined as the set of characteristic dispositions that determine emotional, interpersonal, experiential, attitudinal, and motivational styles. Two theoretical traditions can be distinguished in this field, trait and developmental stage models. In both traditions, the central issue concerns the extent and nature of personality stability and change over the life span.
Behavioral Genetics and Ageing Theory is concerned with the extent to which hereditary factors influence age-related changes over the life span of the individual. Heritability, a descriptive statistic referring to the portion of observed, phenotypic variation in the population, can be accounted for by genetic differences among individuals. The rest of the variation, the non-genetic portion, is called environmental. Thus, change in heritability over the life span indicates that the relative roles of genetic and environmental influences can change with age in terms of their effects on biological and behavioral differences among individuals in the population.
The lifespan development theory has given rise to an overall psychological theory of successful ageing (Baltes & Baltes 1990) called Selective Optimization with Compensation Theory (SOC). Theory on SOC explains how individuals can manage adaptive or successful (social, cognitive and physical) development in old age. According to cognitive plasticity, the development is assumed to be modifiable during all phases of the life span, including old age (Willis et al., 2009).
Psychological theories of ageing explain the psychological changes in individuals in their middle and later years of the lifespan (Bengtson et al., 2005). Self-concept is considered to be the organized, coherent and integrated pattern of self-perceptions which include self-esteem and self-image (Cavanaugh et al., 2002; Whitbourne, 2005). Life-span theorists advocate the view that personality is determined by the interactions between an inner maturational plan and the external societal demands. The theory defines the concept of ageing as multidimensional and these dimensions include the possibility of growth, recovery and learning of new skills at older ages (Baltes et al., 2005).

C. Sociological Theories

The broad focus of sociological theories is on the changing roles and relationships & how it has an effect on the individual’s ability to adapt.

According to Disengagement Theory people develop new types of relationships with society with advancing age. Older people’s desire to remain occupied and their involvement with activities is not taken into consideration. Imposed withdrawal from society may be harmful to elders as well as society in the same manner. This theory is indifferent towards old age and related issues (Bond & Coleman 1993) by understating the cultural and economic structures. Disengagement theory of ageing has no empirical support. This theory is being criticized as it does not explain the large number of older people who do not withdraw from society. The Gero-transdence theory promoted by Tornstam is a modification of disengagement theory of normal ageing.
According to the Gero-transcendence theory, human aging encompasses a general potential towards gero-transcendence; that is, a shift in metaperspective from a materialistic and rational vision to a more cosmic and transcendent one, normally followed by an increase in life satisfaction (Tornstam, 1989). On the basis of qualitative and quantitative studies, Tornstam (1992, 1994) developed the theoretical concept of gero-transcendence at three levels of age-related ontological change: (1) cosmic level including changes in the perception of time, space and objects,; (2) self-level including discovery of hidden aspects of the self, decrease of self-centeredness, selftranscendence and ego integrity; (3) social and individual relations level incorporating less interest in superficial relations,.
Activity Theory was developed in 1953 by Havighurst and colleagues. It was based on the assumption that remaining active and engaged with society is very important to ensure satisfaction in old age. This theory highlights a positive association between activity and life satisfaction (Sana & Sajatovic 2008). Life task participation has been linked to greater life satisfaction and positive effect, lower levels of stress with low score in depressive symptoms (Park, 2009). Activities show protecting and benefiting effects on subjective well-being. However the abilities with satisfaction to perform those activities are more important than the activities themselves (Sharma 2013). This theory tends to deny ageing to a certain extent.
Continuity theory views life as a continuous process and each stage in life helps to prepare for the next stage in a positive direction. However, individual’s behaviour is complex & maintaining the consistency in each stage & given context could be unrealistic. The criticism of the continuity theory is its definition of normal ageing (Quadagno, 2007). The theory distinguishes normal ageing from pathological ageing, neglecting the older adults with chronic illness.
According to Exchange Theory; positive relationships are considered where the benefits are more than the expense & the negative relationships involve more costs compared to the acquired benefits. However, such analysis fails to acknowledge that older people have knowledge and experience to offer to the younger generation (Bernheim et al., 1985, Bengtson et al., 1997).
Modernisation theory can be more contextualized in developing countries where family has important role in extending support to the elderly (Bali, 2002; Patel 2005). Due to modernization and industrialization, large scale migration has taken place deserting a large number of elderly. The social stratification theory divides people, according to age and age is viewed as a way of explaining how people should behave or else the individuality of people is denied.
Modernization and ageing theory supports the notion that the status and support of older people decline as societies ‘westernize’ and as extended families give way to the modern nuclear family,
The political economy theory puts a challenge for both the theoretical dominance of functionalist view and the bio-medical models of age and ageing. The important argument to be made is that inequalities in the distribution of resources should be understood in relation to the distribution of power within society.
Feminist Theories focus that women face, greater problems in old age than men as evidenced by many empirical studies. The issue of women’s vulnerability and dependency through the life course have received significant attention in the recent decades. More difficult task is to change attitudes and society, reshaping values and practice in favour of women (Patel 2007). The challenge of missing link between theories & applications need to be addressed (Hendricks et al, 2010).

An integrative theory of social gerontology can blend a macro perspective, examining the social, economic, environmental, cultural, and political contexts influencing human behaviour and health, with the micro-individual and family (Bengtson et al 2009).

D. Anthropological Theories

Anthropologists paid attention to ageing with an examination of ethnographic data in the Human Relations Area Files in 1945 while considering the role of the aged in 71 primitive societies. Early theoretical formulations propose a quasi-evolutionary theory that links the marginalization of older people to modernization. Current anthropological theorizing is informed by investigations involving older adults living in age-integrated communities, city, urban settings, tribal settings and older people with disabilities. Common theoretical themes currently addressed include variation of the older population leading to differential experiences of aging in different cultural context, the diversity of aging within cultures, and the understanding of change over the life course across different cultural settings. Anthropological theories argue that every human society has generational principles that organize social lives.

Cultural theories of ageing begin with the argument that human beings seek meaning in life which is particularly significant in later life. Theories from the social sciences, as well as those from psychology and psychiatry, have suggested the importance of finding a sense of meaning in later life. Research suggests that older people who receive emotional support from family members and close relatives are more likely to find a sense of meaning in life than older adults who do not have well-developed social support systems (Krause, 2004).
Postmodern Gerontology originates from analysis of the discovery and elaboration of Alzheimer’s disease in the USA (Gubrium 1975). There has been a postmodern perspective of age and ageing identity. Postmodernism has been supported for better lifestyles and increased leisure opportunities for older people due to increasing use of bio-technologies (Powell & Biggs 2002). Direct use of new technologies which modify the performance of an individual with advancing age is an important aspect of this theoretical discourse (Powell and Biggs, 2000). Through the application of the advance technology, human body can be strengthened. Proper diet and exercise are the techniques connected to the growth identities during late life (Powell & Biggs 2000, 2002). However postmodern gerontology is critiqued on account of laying too much emphasis on technology in reversing the ageing process. An integrative biopsycho-social approach to ageing is identified by Ryff and Singer (2009). Policy can influence most, but maybe not all of these contributing factors.