Aging Theory Research Implications
T. C. Goldsmith September 2003
This is a summary of the impact various theories of aging have on anti-aging research. More comprehensive treatment of this subject may be found in the short book: The Evolution of Aging. (PDF version) (HTML version) Paperback version ISBN: 0595280692. See http://www.azinet.com/aging/.
There are many theories of aging but from a practical standpoint aging theories seem to fall into two categories:
Adaptive theories consider that aging is an evolved characteristic or adaptation that developed through the process of evolution in the same manner as any physical characteristic of an animal. Aging is a feature of an animal, part of its design, and provides a necessary evolutionary function. Examples of adaptive theories of aging include the Evolvability Theory, the Group Selection Theory, and Weismann’s Programmed Death Theory.
Non-Adaptive Theories consider that aging is either a fundamental limitation of life, a defect, or an adverse side effect of some necessary process. Examples of non-adaptive theories include the Mutation Accumulation Theory, the Antagonistic Pleiotropy Theory, and the Disposable Soma Theory. Non-adaptive theories are currently more popular among biologists and health professionals. This has a significant negative impact on anti-aging research as follows.
Depending on the category, theories influence anti-aging research in two important ways: Optimism and Direction.
Optimism – Non-adaptive theories are generally very pessimistic regarding the possibility of significant medical intervention in the aging process. Obviously, if aging is a fundamental limitation, intervention is very unlikely. If aging is a defect, it is so severe and intractable that evolution operating during billions of years has been unable to find a solution. If it is a side effect, presumably the primary process is essential and evolution has been unable to find an alternate path. One of the theories specifically teaches that significant medical intervention in the aging process is impossible. Followers of non-adaptive theories tend to oppose fundamental anti-aging research as foolish and wasteful relative to research on amelioration of symptoms and treatment of the end results of aging.
Adaptive theories are much more optimistic regarding intervention. If aging is part of an animal’s design, a specific mechanism, a sort of clock function, then it is probably similar to other biological clock functions. An anti-aging methodology would involve finding some way of interfering with the aging mechanism or slowing down its clock without interfering with all the other functions needed for happy life. Few would doubt that if we really tried we could delay or advance puberty, delay or advance menopause, or modify menstrual cycles. (Some of these things have already been done.) If aging involves a similar evolved mechanism, major medical intervention would appear to be possible in the relatively near future. Aging, considered as a disease, is relatively mild and long-term in nature. As a result an even relatively modest interference in the aging process would have a major positive impact.
Direction – Depending on which category theory he favors, a researcher is going to be looking in different places for insight into the aging problem. Followers of non-adaptive theories tend to look at relatively simple processes that could plausibly result from random mutations or fundamental degradation. Followers of adaptive theories will tend to look at much more complex processes typical of evolved biological mechanisms such as hormone mediated processes and complex control chains.
Public opinion obviously influences research budgets, career choices, and other critical aspects of research. Our informal survey indicates that for reasons having little or no scientific justification, about 80 percent of the general public considers major medical intervention in the aging process to be either impossible or a very distant possibility. Aging, as a universal affliction, is a very popular subject for scams and fringe medical and pharmaceutical remedies. (Our survey shows that about 8 percent of the public believes that significant anti-aging agents have already been developed and are available in the form of HGH, etc.) This probably contributes to (so far well deserved) skepticism regarding anti-aging research and inhibits taking full advantage of favorable recent discoveries and theoretical work.
Copyright 9/2003 T. C. Goldsmith