[FONT=Arial, Helvetica, Verdana]by Prof Dr Omar Hasan Kasule [/FONT]Demographic change: Medical science with the help of general general socio-economic development has led to an increase of longevity in many countries generally through decrease of mortality rates at all ages (1). This has given hope of increasing human longevity by controlling causes of aging. Research at the cellular, clinical, and epidemiological levels is being undertaken on aging with this purpose in mind. Human desire for long life: Longevity has always been a desirable objective of humans of all ages and all places. The desire for long life is very strong in most individual humans (2:90). The primary motivation for prevention and cure of disease is to achieve longevity. Humans of all ages have desired youth and looked for the elixir of permanent youthfulness. Thus attempts to find the causes of aging in order to delay and if possible prevent it serve to perpetuate human kind as much as possible. Longer life has advantages. There is more to contribute to society, to do good deeds to expiate for past failures. However the physical disabilities of old age reach a point when they outweigh the psychological and social advantages. This is the point of life that the Prophet (PBUH) referred to as ardhal al 'umr. Nature of aging: It is difficult to define aging exactly. Aging is a natural process. It is a long and variable process with much individual variation. Factors that affect the rate and extent of aging are: genetic variability, environmental insults, accumulation of changes in somatic cells, mutations and chemical damage (2). Old age is associated with degeneration and decreased or deranged physiological function. It is not true that old age is illness. The changes seen are part of a natural process. A practical definition of disease in the elderly must take this into consideration. The elderly are old and not necessarily sick. Human life-span: The life-span of each individual is fixed by Allah (Sahih Muslim #6438, 6440). No human effort or endeavor will alter the span. When the appointed hour arrives, death ensues. From the historical record and also from study of living communities we know that the maximum human longevity does not go much above 100 years. Life beyond the age of 100 years is rare (Mukhtasar Sahih al Bukhari #368, MB # 96). This is however not the upper ceiling and the possibility of longer longevity exists. The Qur'an tells us about 2 exceptions to the average longevity mentioned above. The Prophet Nuh (PBUH) lived over 900 years. The Prophet Isa (PBUH) who was carried alive to heaven is now aged nearly 2000 years. The observation of increasing life expectancy at birth in all communities where socio-economic and health conditions have improved is another indication that the observed life-span can change. There are gender and ethnic differences in longevity. All these indicate the possibility of life-span variation upwards or downwards. Types of cells and their replicative ability: Cell biology can explain many phenomena of aging. Cells can be classified according to their replication properties. (a) Cells that are continuously renewed: epithelial cells, spermatozoa, blood cells. (b) cells with the potential to proliferate: liver, kidney tubules, exocrine glands, endocrine glands, connective tissue (c) cells not renewed or replaced: myocardium, somatic muscle cells, nerve cells, and retinal cells. The capacity for cell division declines with age. Embryonic cells can divide up to a total of 50 times thus one embryonic cell can over its life-span produce 10E15 cells. Mature cells are capable of fewer divisions; the older they are they less divisions they can make. The reasons for this loss of division capacity is not known but it seems to be part of genetic programming. Cells can increase in number by mitotic division (hyperplasia) or may increase in size without increase in number (hypertrophy). They can also undergo meiotic division. With age the number of irreplaceable cells decreases through the normal process of tear and wear. Cellular aging: Aging, degeneration, and eventual death can be explained at the cellular level. Aging starts with the cells. Normal cells age and die and others take their place. Cellular function declines gradually with age. There is decline of oxidative phosphorylation, DNA and RNA synthesis, synthesis of proteins and cell receptors. Aging cells have definite morphological changes that distinguish them from the younger cells. The causes of cellular aging are: (a) endogenous molecular program of cell senescence (b) wear and tear is a result of damage by free radicals, post-translational modification of intracellular and extra-cellular proteins, and alterations in the induction of heat-shock proteins. The cells are also damaged by accumulation of adverse changes that may happen randomly or under the influence of environmental insults. Nothing can be an error in the function of the cell. All is deliberate plan by Allah and all is pre-designed. With age the following phenomena increase and their cumulative effects lead to aging or death of the cell: the accumulation of somatic mutations, error rates in protein synthesis, and failure of correcting mechanisms. Changes in aging. Aging in accompanied by physical, psychological and social changes as well as challenges (3). There is no point in time when development ceases and degeneration starts. The two processes are contemporaneous. In advanced age degeneration becomes predominant. Normal aging is a gradual process of physical decline and degeneration. It affects the structure and function of all organs. Old age because of its multiple incapacities is sometimes not a pleasant period. The Prophet (PBUH) prayed not to live to advanced age ardhal al 'umr (Mukhtasar Sahih al Bukhari # 1750). Some people with physical aging may psychologically be young. The Prophet mentioned that some people stay young in 2 aspects: love of the world and long hopes (Mukhtasar Sahih al Bukhari # 2096). There are social aspects in aging: The rights of the elderly, huquuq, are sometimes neglected. The elderly are often disrespected in materialistic societies. The elderly lose their autonomy and are dependent physically and emotionally (4). Quality of life in old age: The issue of quality is relevant in discussions of longevity (5). As people age, the quality of their life deteriorates. It is possible that with better understanding of the aging process, procedures will be available to maintain or even improve quality of life in the elderly. It is also possible that with increasing longevity new problems will appear that lower the quality of life. These issues will have to be addressed. Epidemiological studies have shown that physical activity even in moderation reduces morbidity (1), protects against neoplasia and aging (6). Prompt diagnosis and treatment of disease has a positive impact on the quality of life (7). It is wrong to assume that such disease is normal and does not need treatment. The ethical issues of research on aging and its prevention: There is basically no ethical problem in the scientific research on cell aging as well as epidemiological studies on risk factors of senescence. What matters is the intention behind the research and to what use that research will be put. If the underlying intention is to prevent or delay death, the research is not ethical. The life-span is fixed for each individual and can not be changed. If the intention of the research is to understand the aging process so that preventive measures can be taken to maintain as high a quality of life as possible, then such research is ethical and is acceptable. Ethics of health resource allocation: In an era of scarce resources, arguments have been made that the elderly consume disproportionately high resources. It may also be argued that the economic utility of the elderly is low.