Think About Aging
Aging. We’re all doing it. Yet most of us do not know much about growing older. Many of our ideas about what aging means are mainly projections – both fears and hopes – about our future selves. Why do we age? Were we always afraid to age? In a long-lived society, when does old age begin? On this web page we will explore what we need to know to think about our own aging.
Theories of Aging
Why Do We Age?
What causes the changes in our bodies and minds that occur in later life?
Why do we become increasingly vulnerable to diseases such as cancer and Alzheimer’s?
Hundreds of theories have proposed answers to these questions. Some have led to current research as scientists search for ways to slow the rate at which we age so that we can live longer, healthier lives. The most optimistic researchers believe that in the future science will extend the human life span. Others, however, are unconvinced.
To understand why the scientists disagree, consider two of the major theories about the biological causes of aging. One attributes the physical and mental changes that occur in old age to wear and tear of one kind or another; the other holds that genes control the aging process.
We’re Aged by Wear and Tear
The older, wear-and-tear theory maintains that, over time, our bodies suffer random damage and the effects accumulate on many levels. The damage has multiple causes and it makes us more vulnerable to disease. Provided we live long enough, it also leaves us frail and barely able to function.
If it’s true that there is no single, biological mechanism that causes aging, it follows that science is unlikely to be able to slow down the process of growing old.
For more about the wear and tear theory:
“The Way We Age Now” by Atul Gawande. The New Yorker, April 30, 2007, p. 50-59. www.newyorker.com/reporting/2007/04/30/070430fa_fact_gawande
“How do we age? Theories of aging based on random events.” AFAR, the American Federation for Aging Research. http://www.healthandage.com/html/min/afar/content/other2_2.htm
“Position Statement on Human Aging,” by S. Jay Olshansky, Ph.D., Leonard Hayflick, Ph.D., and Bruce A. Carnes, Ph.D. http://www.quackwatch.org/01QuackeryRelatedTopics/antiagingpp.html
“Pushing The Limit: An Interview with Dr. Leonard Hayflick,” by David Jay Brown. http://www.smart-publications.com/articles/MOM-hayflick.php
“Emerging Area of Aging Research: Long-lived Animals with ‘Negligible Senescence.’" http://www.agelessanimals.org/
“Learning From Ageless Animals: An Interview with John Guerin,” by David Jay Brown. http://www.smart-publications.com/articles/MOM-guerin.php
We’re Aged by our Genes
A newer theory asserts that particular genes can control aging and that, by manipulating them, we may someday be able to rein in the rate at which we age. Already, researchers studying roundworms, fruit flies, and mice have learned how to extend their lives by affecting particular genes.
This is not done, however, by interfering with a genetic program that dictates when the animals will age and die. Rather, researchers have identified what some call “longevity genes” that can lengthen an animal’s life.
In manipulating those genes, they believe they are taking advantage of a mechanism created by evolution to help creatures survive times of long-lasting stress - when food is in short supply, for example. At such times, researchers have found, laboratory animals age more slowly, remain active and vigorous for much longer, and the diseases that generally kill them in old age develop later in their lives. Investigators believe this complex biological response evolved to help individual animals stay alive during lean times so that when their situation improves, they can still reproduce and pass on their genes – including the ones that can slow the aging process.
Scientists are hoping that this response to stress exists in humans, as well, and can be triggered by medications. Most emphasize, however, that their main goal is not to increase the human life span (though that would be a stunning achievement) but to extend the health span - the number of years of vigorous, healthy living that most people can expect.
For more about the genetic theory:
“Old Worms, New Aging Genes: Biologists look into DNA for the secrets of long life,” by John Travis. Science News Online, Aug. 2, 2003. http://www.sciencenews.org/articles/20030802/bob9.asp
“Unlocking the Secrets of Longevity Genes,” by David A. Sinclair and Lenny Guarente. Scientific American, February 20, 2006. http://www.sciam.com/article.cfm?id=000B73EB-3380-13F6-B38083414B7F0000&print=true
“A Longer, Better Life: Sara Davidson Talks to Two Medical Scientists about How the Body Ages and the Research on Trying to Extend Our Healthy Life Span.” By Sara Davidson New York Times Magazine, May 6, 2007, pp 52-56. http://www.nytimes.com/2007/05/06/magazine/06dialogue-t.html?_r=1&oref=slogin
“A Conversation With Elizabeth H. Blackburn: Finding Clues to Aging in the Fraying Tips of Chromosomes,” by Claudia Dreifus. http://www.nytimes.com/2007/07/03/science/03conv.html?ex=1341115200&en=5cb9eec5df0ed7fc&ei=5088&partner=rssnyt&emc=rss
