By 2030, the number of older Americans will have more than doubled to 70 million, or one in every five Americans. The general consideration for this advance is due to improvements in sanitation and personal hygiene, the discovery and use of antibiotics, advance in medical care, general education and so on. Even life span is now not surrendered to the chronic diseases like cancer and heart disease due to scientists' development."

Life expectancy in Bangladesh has also increased to 62/63 (male/female) years from 44 years in 1970 (UNICEF 2002). People are using improved drinking water sources (75%), total population using adequate sanitation facilities (45%), improved antenatal care coverage (40%) and so on. Life expectancy of people in other neighboring countries has also increased. In India, Bhutan, Myanmar, Indonesia and Sri Lanka the male/female life expectancies are 61/63 years, 62/65 years, 56/63 years, 65/68 years and 68/75 years respectively. Life expectancy has improved more for women than their male counterparts. One implication is that women should be more prepared for the difficulties, discomforts, disabilities and diseases related to aging.

As far as it is known, the world has seen the maximum biological limit to the human life span to 122 years, which is the longest that anyone has ever lived. A woman in France, Jeanne Calment, reached that age in 1997, according to details provided by her retirement home. No precise cause of death was recorded.

Those "blessed" with long lives always made the researchers speculate: What is the secret? Does it lie in the human genes? Is it the way the people live or where they live? Something they do or do not do? Something they eat or do not eat? Can human lifespan be extended with modern technology? Did Jeanne Calment approach some built-in, biological limit? Is there a maximum human life span beyond which we cannot live no matter how optimal our environment or good our genes are?

Whether or not there is such a limit, what is important is to understand the dynamics of the aging process. Would such insights provide ways to extend the human life span to 120 or even more, as some scientists speculate? And finally and most importantly, how can those insights be used to fight diseases and disabilities associated with old age so that despite old age we can live healthily and independently?

There are some theories on Aging Process. This process can be divided into three general categories: genetic, biochemical, and physiological. But the theories of aging fall into two categories, the Programmed and Error Theories.

The "Programmed" theories maintain that aging follows a biological timetable, perhaps a continuation of the one that regulates childhood growth and development. The Error or damage theories emphasize environmental assaults to our systems that gradually cause things to go wrong. Important to note here is that many of the theories of aging are not mutually exclusive.

More simplified rundown of the Programmed Theories are:

a. Programmed Senescence: Aging is the result of the sequential switching on and off of certain genes, with senescence being defined as the time when age-associated deficits are manifested.

b. Endocrine Theory: Biological clocks act through hormones to control the pace of aging.

c. Immunological Theory: A programmed decline in immune system functions leads to an increased vulnerability to infectious disease and thus aging and death.

More basic rundown of the Error Theories are:

a. Wear and Tear: Cells and tissues have vital parts that wear out.

b. Rate of Living: The greater is an organism's rate of oxygen basal metabolism, the shorter is its life span.

c. Cross linking: An accumulation of cross linked proteins damages cells and tissues, slowing down bodily processes.

d. Free Radicals: Accumulated damage caused by oxygen radicals causes cells and eventually organs to stop functioning.

e. Error Catastrophe: Damage to mechanisms that synthesize proteins results in faulty proteins which accumulate to a level that causes catastrophic damage to cells, tissues, and organs.

f. Somatic Mutation: Genetic mutations occur and accumulate with increasing age, causing cells to deteriorate and malfunction.

These theories have motivated many scientific studies, including one by Dr. James Jessup at the University of Florida that finds people who are over 40 can benefit from regular moderate exercise and vitamin E. [Breakthrough Digest, July 30, 2003].