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Evolution of Aging - Implications For Aging Research

age physiological genetic evolutionary life theory span

Evolutionary biologists have always been very generous with gerontologists in providing advice and guidance on how to do aging research "in directions that are likely to be fruitful" (Williams). Surprisingly, this generous intellectual assistance proved to be extremely injurious for aging studies in the past. This happened because evolutionary theory was interpreted in such a way that the search for single-gene mutations (or life-extending interventions) with very large positive effects on life span was considered a completely futile task, destined for failure for fundamental evolutionary reasons. Researchers were convinced by the forceful evolutionary arguments of George Williams that "natural selection will always be in greatest opposition to the decline of the most senescence-prone system" and, therefore, "senescence should always be a generalized deterioration, and never due largely to changes in a single system. . . . This conclusion banishes the fountain of youth to the limbo of scientific impossibilities where other human aspirations, like the perpetual motion machine and Laplace's 'superman' have already been placed by other theoretical considerations. Such conclusions are always disappointing, but they have the desirable consequence of channeling research in directions that are likely to be fruitful."

As a result of this triumphant evolutionary indoctrination, many exciting research opportunities for life span extension were squandered for a half a century, until the astonishing discovery of single-gene mutants with profoundly extended longevity was ultimately made (see Lin et al., 1997; 1998; Migliaccio et al.), despite all discouraging predictions and warnings based on evolutionary arguments.

Recent discoveries of life-span-extending mutations are spectacular. A single-gene mutation (daf-2) more than doubles the life span of nematodes, keeping them active, fully fertile (contrary to predictions of the disposable soma theory), and having normal metabolic rates. Another single-gene mutation, called methuselah, extends the average life span of fruit flies by about 35 percent, enhancing also their resistance to various forms of stress, including starvation, high temperature, and toxic chemicals. Finally, a single-gene mutation was found in mice, extending their life span by about 30 percent and also increasing their resistance to toxic chemicals. Researchers involved in these studies came to the following conclusion:

The field of ageing research has been completely transformed in the past decade. . . . When single genes are changed, animals that should be old stay young. In humans, these mutants would be analogous to a ninety year old who looks and feels forty-five. On this basis we begin to think of ageing as a disease that can be cured, or at least postponed. . . . The field of ageing is beginning to explode, because so many are so excited about the prospect of searching for—and finding—the causes of ageing, and maybe even the fountain of youth itself. (Guarente and Kenyon).

Now, when single-gene, life-extending mutations are found, evolutionary biologists are presented with the task of reconciling these new discoveries with the evolutionary theory of aging. They are certain to succeed in this task, however, as evolutionary theories of aging are very flexible and can be adjusted to almost any new finding.

However, gerontologists will also have to learn their lessons from the damage caused by decades of misguided research, when the search for major life-extending mutations and other life-extension interventions was equated by evolutionary biologists with the construction of a perpetual motion machine. Perhaps some leads for getting wisdom from this lesson can be found in the title of a recent scientific review on evolution of aging: "Evolutionary Theories of Aging: Handle With Care" (Le Bourg, 1998).

NATALIA S. GAVRILOVA LEONID A. GAVRILOV

BIBLIOGRAPHY

BECKMAN, K. B., and AMES, B. N. "The Free Radical Theory of Aging Matures." Physiological Reviews 78 (1998): 547–581.

CARNES, B. A., and OLSHANSKY, S. J. "Evolutionary Perspectives on Human Senescence." Population and Development Review 19 (1993): 793–806.

CHARLESWORTH, B. Evolution in Age-Structured Populations. Cambridge, U.K.: Cambridge University Press, 1994.

CHARLESWORTH, B., and PARTRIDGE, L. "Ageing: Leveling of the Grim Reaper." Curr Biol 7 (1997): R440–R442.

FISHER, R. A. The Genetical Theory of Natural Selection. Oxford, U.K.: Oxford University Press, 1930.

GAVRILOV, L. A., and GAVRILOVA, N. S. The Biology of Life Span: A Quantitative Approach. New York: Harwood, 1991.

GAVRILOV, L. A., and GAVRILOVA, N. S. "Is There a Reproductive Cost for Human Longevity?" Journal of Anti-Aging Medicine 2 (1999): 121–123.

GAVRILOV, L. A., and GAVRILOVA, N. S. "The Reliability Theory of Aging and Longevity." Journal of Theoretical Biology (2001): 527–545.

GAVRILOVA, N. S., et al. "Evolution, Mutations and Human Longevity: European Royal and Noble Families." Human Biology 70 (1998): 799–804.

GERSHON, D. "The Mitochondrial Theory of Aging: Is the Culprit a Faulty Disposal System Rather Than Indigenous Mitochondrial Alterations?" Experimental Gerontology 34 (1999): 613–619.

GUARENTE, L., and KENYON, C. "Genetic Pathways That Regulate Ageing in Model Organisms" Nature 408 (2000): 255–262.

HAMILTON, W. D. "The Moulding of Senescence By Natural Selection." Journal of Theoretical Biology 12 (1966): 12–45.

HARMAN, D. "Free Radical Theory of Aging: Alzheimer's Disease Pathogenesis." AGE 18 (1995): 97–119.

HOLLIDAY, R. "The Error Catastrophe Theory of Aging: Point Counterpoint." Experimental Gerontology 32 (1997): 337–339.

KIRKWOOD, T. B. L. "Evolution of Aging." Nature 270 (1997): 301–304.

KIRKWOOD, T. B. L., and HOLLIDAY, R. "The Evolution of Ageing and Longevity." Proceedings of the Royal Society London. Series B, Biological Sciences 205 (1979): 531–546.

LE BOURG, É. "Evolutionary Theories of Aging: Handle With Care." Gerontology 44 (1998): 345–348.

LE BOURG, É. "A Mini-Review of the Evolutionary Theories of Aging. Is it the Time to Accept Them?" Demographic Research 4, article 1 (2001): 1–28.

LIN, K.; DORMAN, J. B.; RODAN, A.; and KENYON, C. "daf-16: An HNF3/Forkhead Family Member That Can Function to Double the Life-Span in Caenorhabditis elegans." Science 278 (1997): 1319–1322.

LIN, Y.; SEROUDE, L.; and BENZER, S. "Extended Life-Span and Stress Resistance in the Drosophila Mutant methuselah." Science 282 (1998): 943–946.

MEDAWAR, P. B. An Unsolved Problem of Biology. London: H. K. Lewis, 1952.

MIGLIACCIO, E.; GIORGIO, M.; MELE, S.; PELICCI, G.; REBOLDI, P.; PANDOLFI, P. P.; LANFRANCONE, L.; and PELICCI, G. "The p66 shc Adaptor Protein Controls Oxidative Stress Response and Life Span in Mammals." Nature 402 (1999): 309–313.

MORLEY, A. A. "The Somatic Mutation Theory of Aging." Mutation Research 338 (1995): 19–23.

MUELLER, L. D., and ROSE, M. R. "Evolutionary Theory Predicts Late-Life Mortality Plateaus." Proceedings of the National Academy of Science U.S.A. 93 (1996): 15249–15253.

REZNICK, D.; BUCKWALTER, G.; GROFF, J.; and ELDER, D. "The Evolution of Senescence in Natural Populations of Guppies (Poecilia reticulata): A Comparative Approach." Experimental Gerontology 36 (2001): 791–812.

ROSE, M. R. Evolutionary Biology of Aging. New York: Oxford University Press, 1991.

STEARNS, S. C. "Life History Evolution: Successes, Limitations, and Prospects." Naturwissenschaften 87 (2000): 476–486.

STEARNS, S. C.; ACKERMANN, M.; DOEBELI, M. and KAISER, M. "Experimental Evolution of Aging, Growth, and Reproduction in Fruitflies." Proceedings of the National Academy of Science U.S.A. 97 (2000): 3309–3313.

SWIM, H. E. "Microbiological Aspects of Tissue Culture." Annual Review of Microbiology 313 (1959): 141–176.

TERMAN, A. "Garbage Catastrophe Theory of Aging: Imperfect Removal of Oxidative Damage?" Redox Report 6 (2001): 15–26.

WACHTER, K. W. "Evolutionary Demographic Models for Mortality Plateaus." Proceedings of the National Academy of Science U.S.A. 96 (1999): 10544–10547.

WEISMANN, A. Essays Upon Heredity and Kindred Biological Problems. Oxford, U.K.: Clarendon Press, 1889.

WEISMANN, A. Über die Dauer des Lebens. Jena: Verlag von Gustav Fisher, 1882.

WEISMANN, A. Über Leben und Tod. Jena: Verlag von Gustav Fisher, 1892.

WESTENDORP, R. G. J., and KIRKWOOD, T. B. L. "Human Longevity at the Cost of Reproductive Success." Nature 396 (1998): 743–746.

WILLIAMS, G. C. "Pleiotropy, Natural Selection and the Evolution of Senescence." Evolution 11 (1957): 398–411.

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