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The study of late adulthood and aging is called gerontology. There are many theories of aging. Some theories suggest that the body just wears out over a period of time.
The immunity theory focuses on stress and the accumulated effects of illness and contaminants in our environment. Eventually, the body loses its ability to protect itself from stress and disease. Some of the most promising research has concentrated on cellular aging. Hayflick (1980) found that human body cells are programmed to reproduce themselves a finite number of times. He took cells and let them reproduce until they eventually died. He found that most human cells die after about fifty doublings under ideal conditions. But Hayflick believes that most cells probably never reach their maximum because of physiological changes that take place in the cell. Early in 1998, Calvin Harley, of Geron Corporation and Jerry Shay of the University of Texas Southwestern Medical Center, announced the discovery of a human gene that resets the number of replications of a cell. The telomerase gene could prolong life significantly by lengthening the telomere, or part of the chromosome involved in cell division. Some other scientists are more skeptical, and argue that this system is also involved in preventing cancer. Thus tinkering with the telomeres might cause cancer in people. Further research will allow us to discover how cellular function is involved in the aging process and whether the fountain of youth has truly been discovered. |
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