In article <36021FF5.2CF95D48 at notarealaddr.ess>, bmdelaney at notarealaddr.ess
>>>>>Thomas Mahoney/ Excelife wrote:
>> Quite correct. Mice in the wild undoubtedly
>> encounter periods where food is scarce and the
>> effects seen in CR are likely an adaptive
>> response to these conditions. Thus the actual
>> life span of the mice is that seen in CR.
>>I'm not sure how this way of looking at it is helpful.
>>If we had evolved a mechanism whereby certain chemicals
>found in foods can be utilized by the body to slow free
>radical damage in a systematic way that results in aging
>being retarded, and then we put those chemicals in a pill,
>and they increased longevity, would we not be increasng our
>"actual life span" by taking this pill?
You would be increasing life expectancy, which is a legitimate and laudable
goal, but you would not be increasing the maximum life span.
>Take another example. Say we had evolved a mechanism whereby
>eating a certain substance found in a now rare plant turns
>on telomerase in enough cells, in the right way, to slow
>aging. No one has been known to eat the substnce because our
>dietary habits over the last few centuries have precluded
>its consumption. But suddenly we discover it, and people
>start taking it and living to be 140 years old. Since this
>ability to age slowly under the conditions of the presence
>of this substance is an evolutionary adaptive response,
>would you say people living to 140 by means of this
>substance aren't extending their life span?
Here you changed the premise. By stating that they lived to 140 you have, by
definition, increased the maximum life span in humans.
>How about if your lab creates the substance?
If the substance produced allowed the subject to live longer than any other
subject has ever been known to live before then you have increased their life
span. If it only allows the subject to live up to that limit but not beyond
then you have increased their life expectancy.
>I don't think these questions are simple. But I do think, in
>studies with mortality as an end-point, it makes sense to
>differentiate between average and maximum life span, for
>both the control and experimental groups. Going beyond that
>-- like arguing that some experiments are merely reproducing
>conditions that existed over the course of evolution, and
>some aren't, and therefore some are extending our natural
>life span and some aren't -- may be fruitful in certain
>contexts, but I'm not sure how it bears on the question of
>anti-aging research priorities.
It is fundamental to the research priorities. On the one hand you are merely
trying to improve quality of life and increase life expectancy. This has
been the goal of medical research through out time. Anti-biotics, vaccines,
drugs, vitamins, dietary supplements etc... are all methods of improving our
ability to survive as long and as heathfully as possible.
Research into the basic causes of why we age and research to find methods of
intervening in these processes are attempts at letting us live longer than
any one ever has before.
NIH, Pharmaceutical Companies and most University research is directed toward
the first category. Only an infinitesimal amount of research fund are being
used to find the underlying causes of aging. I'd like to see these priorities
revised to allow for more basic research into the causes and cures for aging.
>>> It might make it clearer if we looked at those
>> mice who are fed regularly as being overfed and
>> dying earlier than their "normal" life span.
>>Definitely not clearer. The CR rodents are at close to
>starvation-levels of eating, and the females can't even
>reproduce. Maybe you can call the control rodents overfed,
>but you can't call the CR rodents normal, given that they
>aren't fit to reproduce. Therefore, their life spans are not
Your right that full CR is an artifact of the experimental conditions but so
is the environment for the control laboratory mice. Wild mice are more
likely go through a feast or famine type feeding process. Several
experiments have tried to mimic this condition and the results, as expected,
showed a switching between the aging processes in the mice. The mice in
these studies lived longer than the laboratory controls but shorter than
those mice on full CR.
The point of all of this is that CR does not really increase life span.
Thomas Mahoney, Pres.
Lifeline Laboratories, Inc.