Skin: Skin tissue has been successfully grown in the laboratory, and biotechnology companies are now producing it in quantity for use with burn victims.
Cartilage: One of the most common effects of aging is the wear and tear on cartilage. Surgeons can now use cartilage grown in the lab to treat joint injuries.
Bone: Hip replacements have long been a staple of geriatric medicine—even Elizabeth Taylor had one. Today, biotechnology companies are selling bone substitutes manufactured from artificial substances. Companies are working on grafts that would enable the body to replace living tissue with artificial bone.
More exciting innovations are on the horizon with the expanding field of regenerative biology and medicine (Stocum, 2012):
Breast tissue regeneration: Breast implants made of silicone have long been in use, but the results have been controversial. Tissue engineers are working on new techniques to stimulate women’s bodies to grow new breast tissue. Already, plastic surgery has become enormously popular. Tissue engineering and “body sculpting” are likely to become even more important in years to come.
Artificial vision: In Star Trek: The Next Generation, the character Geordi (played by LeVar Burton) is able to see by using a “VISOR”—an artificial vision device worn over the eyes. Today, older adults are the age group most likely to be afflicted with impaired vision or total blindness. But in the future, electronic devices may replace lost visual capacity.
Heart valves: Cardiovascular disease is the biggest cause of death among older Americans. Researchers have long been at work on a totally implantable artificial heart. Today, heart valves from pigs have been transplanted into humans. Researchers have discovered how to grow valves from blood vessel cells in the laboratory, and these lab-grown valves work well in lambs. In the future, thousands of people could benefit from artificially grown heart valves.
Bladder: Urinary incontinence is one of the most troubling afflictions for older adults, and it is a factor in nursing home placement. But scientists are working on producing molded lab-grown cartilage that could function as a valve to keep urine flowing in the proper direction.
Pancreas: Late-life diabetes is one of the most serious diseases of old age, entailing complications such as blindness, amputation, and heart failure. Diabetes results from basic organ failure. The pancreas doesn’t produce enough insulin to metabolize sugar properly. Bioengineers are now working on implants made of pig islet cells, which could produce insulin without injections for people who develop diabetes.
Brain: No one expects medical science to produce anything like Donovan’s Brain, a tissue-culture brain that was the centerpiece of a 1950s science fiction movie. But drugs to stimulate nerve growth are under investigation today, and techniques may soon be available to implant cells or introduce growth factors that would reverse damage to the central nervous system.
So far, cyborgs, like those in Star Trek, are just science fiction. But bioengineering work on transplants and artificial organs is not fictional. Moreover, other scenarios are possible. For instance, Bruce Sterling’s novel Holy Fire (1996) has as its heroine a wealthy 94-year-old woman who gets total cellular rejuvenation based on new genetic material added to chromosomes in her body. The result is an organism constructed from “designer genes,” which is different from Cynthia and her replacement parts. Stay tuned as the 21st century progresses and biomedical technology reshapes our vision of what human aging is all about.
Questions for Writing, Reflection, and Debate
1 What are the arguments for and against the view that aging in and of itself is actually a disease? Pick one side of this issue and then try listing the points that can rebut the opposing point of view.
2 What do James F. Fries and Lawrence Crapo mean by natural death? What is the relationship between natural death and the natural life span? Should we consider the natural life span to be identical to the maximum life span?
3 Swedish data have turned up the surprising fact that death rates for the oldest-old (85+) have actually been going down. Some scientific studies suggest an ever-increasing life expectancy is quite possible. These findings sound like good news. Do we have any reasons to believe that these findings are not good news? What would be Fries and Crapo’s response to these claims?
4 The Human Genome Project has now produced a complete map of all human chromosomes. Considering the different theories of aging, what are some of the ways in which new genetic knowledge might change how we think about the causes of biological aging? What are the social and ethical implications of that knowledge?
5 Write a science fiction or imaginary scenario of how the United States might look in the year 2030 if dramatic breakthroughs in the genetics of aging occur. In developing this scenario, be sure to state the year you expect the key discoveries or inventions to occur, and describe the likely social consequences of those discoveries or inventions.
6 What is the best scientific evidence in favor of, or against, the compression-of-morbidity thesis? Conduct an online search of current journal articles to consider how various researchers are consider this topic, including changes in rates of disability over time. What questions are left open by this research—for example, what exactly is “disability” as measured across different subgroups? What are the most effective ways to intervene to “compress” morbidity?
Suggested Readings
Austad, S. N., Why We Age: What Science Is Discovering About the Body’s Journey Through Life, New York: Wiley, 1999.
Kirkwood, T., Time of Our Lives: The Science of Human Aging, Oxford, UK: Oxford University Press, 2001.
McDonald, R. B., Biology of Aging, New York: Garland Science, 2013.
Scientific American Editors, Forever Young: The Science of Aging, New York: Scientific American, 2013.
Silvertown, J., The Long and the Short of It: The Science of Life Span and Aging, Chicago: University of Chicago Press, 2013.
Descriptions of Images and Figures
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The horizontal axis is labeled age, and ranges from 0 to 100 in increments of 10. The vertical axis is labeled percent surviving, and ranges from 0 to 100 in increments of 25. The curves in the graph decrease in a concave down manner. Approximate data from the graph are tabulated as follows.
Back to Figure
The horizontal axis is labeled age in days, and ranges from 0 to 1400 in increments of 200. The vertical axis is labeled percent survivors, and ranges from 0 to 100 in increments of 20. All data are approximate. The graph shows eight curves. The first four curves decrease in a concave-up manner from (0, 90) to (300, 0), (450, 0), (550, 0), and (850, 0), with the degree of concavity decreasing from left to right. A curve decreases without concavity from (0, 100) to (1050, 0). The remaining three curves decrease in a concave-up manner from (0, 100) to (1050, 0), with the degree of concavity increasing from left to right.
Back to Figure
The horizontal axis is labeled age in years, and ranges from 0 to 100 in increments of 10. The vertical axis is labeled average percentage property remaining, ranging from 0 to 100 in increments of 10. All data are approximate. The graph shows five numbered lines that slope downward. Line 1 is between (33, 100) and (83, 85). Line 2 is between (33, 100) and (83, 81). Line 3 is between (35, 97) and (83, 61). Line 4 is between (35, 97) and (83, 45). Line 5 is between (33, 100) and (83, 34).
Back to Figure
The horizontal axis is labeled age, and ranges from 0 to 100 in increments of 10. The vertical axis is labeled