Sunday, January 15, 2006

life extension

Humanity has been searching in vain for the well-spring of eternal life since the beginning of recorded history , sometimes in ways so bizarre as to defy common sense. Ponce de Leon, well known to Americans for his explorations of Florida in the early 1500s while seeking to find the spring of the waters of eternal youth, could perhaps be excused because of the lack of scientific knowledge in his time.
Novelist Aldous Huxley wrote a fictional account of the strange results of an 18thcentury search for eternal life that mocked modern fantasies about survival in present life held by some contemporary seekers after a biological rather than spiritual eternity. In this tale, titled After Many a Summer Dies the Swan, Huxley included a harshly satirical subplot involving a French nobleman of the late 1700s and his wife, who together eagerly sought to prolong their lives by consuming a secret formula made of bacteria extracted from the entrails of fish. Huxley's use of this fantastic idea was premised on his knowledge of the theories like those of Russian scientist Elie Metchnikoff, who hypothesized that the putrefying poisons, which develop within our bodies during digestion when intestinal flora break down food, cause aging and death. According to Huxley's tale, the nobleman and his wife did succeed in prolonging their lives by destroying the toxins caused by the process of digestion going on in their aristocratic bellies, but at a considerable cost-their bodies went into reverse evolution as they aged, and they eventually turned into barely human, apelike creatures who had to live in a cage.
In the real world of everyday life, the most powerful force in extending life has been the improvement of sanitation-the unexciting but profoundly important construction of modern sewage and water systems that dispose of disease-carrying human wastes, eliminate stagnant pools of water that breed malaria mosquitoes and other maladies, and supply us with fresh, clean water free of cholera, salmonella, and other infections. These have eliminated from most developed nations the plagues and epidemics that, until this century, destroyed people throughout infancy and youth and kept human life expectancy below age 40.
Better nutrition, with greater quantity and higher quality of food, has also been a factor in extending human life, as has the now prosaic but still revolutionary development of medical immunization against childhood diseases. We take such factors for granted these days, but they alone probably account for most of the increase in life expectancy since 1900, a year when the average length of life was about 30 years shorter than it is today.
More recent increases in length of life have been wrung from nature with greater difficulty, resting on the spectacular victories of scientific research and medical know-how that produced antibiotics, immunization against polio, artery bypasses, angioplasty, pacemakers, organ transplants, joint replacements, blood pressure medications, chemical and surgical therapies for cancer, cataract excisions and corneal transplants, and all the many other scientific and medical breakthroughs that have made late life more healthful and hopeful than ever in human history. Sometimes called "life-extension technologies," these most recent advances in human health sciences not only lengthen life but substantially improve the quality of daily human experience by reducing ill health and overcoming, or at least mitigating, the effects of acute and chronic illness in old age. A number of researchers studying the biological causes of aging at the cellular level predict even more remarkable progress if we can successfully attack the causes of aging within human cells themselves. No major researcher, however, has yet forecast the total elimination of death-only the prolongation of the average length of life.
Widespread lifestyle change on the part of the American public can also contribute to increased longevity in the future. Dr. Roy Walford of UCLA, for example, is personally experimenting with a reduced calorie intake following experiments that enabled researchers to prolong the lives of minimally fed laboratory mice. This research, he believes, suggests that people who control and reduce their food intake will bring their years closer to the maximum life span of the human species-about 120 years.
Further, research on exercise has shown a relationship between even moderate levels of physical activity and increased age. Still more, it has proven that exercise can forestall, and actually even reverse, the process of aging at the same time as it contributes to the greater enjoyment of life.
It is also known that major lifestyle changes in the use of tobacco will increase average longevity. To cite just one example, the well-known association between smoking, cancer, lung disease, and, ultimately, death, was strikingly documented in The General Social Survey, which showed that the vast majority -- nearly 83 percent -- of men over 85 report being nonsmokers. Women generally outlive men, and GSS showed that none of the women over 85 were smokers.
Consideration of past advances and the possibility of future lifestyle changes has led some gerontologists to predict that we may expect more people in the future to live to the biological limit of the human life span. The term used to describe this possible development is known as curve rectangularization, which simply means that the curve of human survival, which now begins to slide downward like a ski slope in the late fifties, will continue on as a straight line past 110 years of age as more people reach toward the full potential for human years. After age 110 the curve of survival will drop off sharply, and it will look like the side of a square rather than a sloping hillside. Even now thousands of people live beyond age 90 and 100, but the George Burnses and centenarians (a centenarian is 100 years old or more) are so few that they represent only very small numbers in the last decades of life. If we do succeed in extending life--or rectangularizing the curve of life-then everyone will reach close to the limit of the human life span-120 years.
See also AGING, BIOLOGICAL THEORY OF.
Kinney, T.: "Living Longer," in Aging, Goldstein, E. C., ed'. Vol. 3, Art. 10. Boca Raton, Fl.: Social Issues Resource Series, Inc., 1981.
Russell, C. H. Good News About Aging. New York: John Wiley and Sons, 1989.
Russell, C. H., and Megaard, I. J. The General Social Survey, 1972-1986: the State of the American People. New York: Springer-Verlag, 1988.
Walford, R. L. The 120 Year Diet. New York: Simon and Schuster, 1986.

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