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Anti-Aging Research, according to Tom Mahoney

Brian Manning Delaney bmdelaney at notarealaddr.ess
Tue Sep 29 15:44:04 EST 1998



Excelife wrote:
> 
> In article <360FFC1E.AA250F23 at uchicago.edu>, b-delaney at uchicago.edu says...

[....]

> I see your point and do agree that the
> definition of aging as stated below
> is  the criteria we should utilize in evaluating
> aging research.

>> No matter, we now seem to have a working
>> definition -- "that achievable without researcher-
>> intervention" -- which, while somewhat flawed, will be good
>> insofar as it's something we can all agree to stick to,
>> notwithstanding explicit qualifications of the definition.

[....]


>> To say, however, as you have been doing, that CR doesn't
>> increase the maximum life span of rodents AT ALL is, to
>> repeat, without warrant.

> Since it is unlikely that any mice in the wild
> have encountered the  restrictive conditions
> imposed by CR I have agreed that there is a
> slight  increase in life span utilizing the
> definition above.  But this isn't because  they
> can't live that long just that they haven't.
> The research into CR has  done little to change
> the fundamental limit on life span.

I'm surprised to see the word "fundamental" appear in a
qualification on life span limit. I thought we had agreed to
stick with already agreed upon definitions, and that we
wouldn't be shifting yardsticks. If "fundamental" means
genetic, you need to argue why you have, yet again, changed
your mind on what yardstick matters. If it means something
else, you need to define it.


>> Thus, your definition of maximum life span seems to be: "the
>> life span achievable without researcher intervention in any
>> extraordinary circumstances we can imagine possibly existing
>> in nature, even if we haven't actually encountered such
>> circumstances."
>>
>> This seems a rather forced definition.

> For our purposes, of determining if experimental
> conditions have an effect on  life span this is
> the definition which *should* be used.  If the
> interventions that are being tested can only
> reach this limit but not exceed  it then "life
> span" has not been increased.  Using a
> definition of life span  that is less than the
> maximum "possible" without researcher
> intervention,  just clouds the issues. 

Were it a simple matter to understand what "possible" means,
I would agree with you. Yet we are having difficulties with
precisely this matter. To wit:

>> Let me return to one of my earlier hypothetical examples:
>>
>> BMD> Take another example. Say we had evolved a
>> BMD> mechanism whereby eating a certain substance
>> BMD> found in a now rare plant turns on telomerase in
>> BMD> enough cells, in the right way, to slow aging.
>> BMD> No one has been known to eat the substnce
>> BMD> because our dietary habits over the last few
>> BMD> centuries have precluded its consumption. But
>> BMD> suddenly we discover it, and people start taking
>> BMD> it and living to be 140 years old. Since this
>> BMD> ability to age slowly under the conditions of
>> BMD> the presence of this substance is an
>> BMD> evolutionary adaptive response, would you say
>> BMD> people living to 140 by means of this substance
>> BMD> aren't extending their life span?
>>
>> You responded by saying I had "changed the premise" by
>> stipulating that humans would live to over ~120, and that
>> therefore such a substance WAS increasing maximum life span.
>>
>> Then you changed your mind, and came to agree with the
>> definition of maximum life span we've been working with: the
>> "non-intervened" life span. So then, with the discovery of
>> this substance, we wouldn't be altering the maximum life
>> span of humans, because researchers wouldn't be needed to
>> produce the change (since the substance is natural, and
>> naturally available).

> This is a "straw man" argument.  By making the
> assumption that such a  substance can exist you
> are disregarding the research that shows there
> is a  fixed life span for each species.

No. Either you don't know what a "straw man argument" means,
or you have once again misunderstood the point of my
hypothetical example.

A "straw man" is a false, and easily defeated representation
of an opponent. I'm not setting up a straw man here at all.
Rather, my point is -- especially now, after reading more of
your recent responses -- to get you to see that you are
ultimately relying on a definition of maximum life span such
that only a genetic (perhaps even genomic) change can extend
it. That is to say, you don't agree with the
researcher-intervention definition, but rather only with
this:

"Maximum life span is that achievable without the
intervention of a genetic-tinkerer."

> If some substance were found in nature that had
> an effect on the genetic  code, it would be
> considered a mutation and the resulting animal
> would be a  "different" breed or species.

My example didn't stipulate that there was a substance that
changed the genetic code, rather that we were such,
naturally, that telomeres could be lengthened by means of a
substance found in nature. (I'm assuming you don't mean that
lengthening telomeres would amount to changing the genetic
code.)

[....]

> More to the point, however, is that since the
> substance has not yet been  encountered it's
> effects would not be an "adaptive" response.

I specified only that it hadn't been known about until
recent times. The example assumes that it HAD been
encountered -- that's why we evolved a way to utilize it. I
specified specifically that we had evolved a mechanism to
utilize it.


>> One last thing:
>>
>> Please don't say things that are false, or very misleading,
>> when you almost certainly know better, like this:
>>
>> > The beneficial effects of CR, including the
>> > suppression of mitotic  activities, is related
>> > to a decrease in body temperature in both mice
>> > and  Rhesus monkeys.
>>
>> There was ONE study, not yet repeated, that showed that some
>> of the beneficial effects of CR are abolished when ambient
>> temperature is raised, in RODENTS. We have NOTHING to
>> support the idea that this would happen with monkeys on CR.
>> The finding that monkeys' body temperature is lowered on CR
>> does not bear in any empirical way on this. We would need to
>> change the ambient temperature and see what happens. This
>> hasn't been done.


> I'm not sure if raising body temperature would
> negate the beneficial effects  of CR nor was I
> implying that it would, in the statement above.

I took the statement out of a context that more strongly
suggested that you meant that the "relation" was at least
partly causative. But you didn't directly say that it was
causative, to be sure. Sorry if I was reading in more than
was there. Still, it seems like the most natural
interpretation of "is related to" is "is at least partially
caused by". When scientists mean "is correlated with,"
that's usually precisely what they say.

No matter. I now know what you meant.

(For the record, I actually think it's more likely than not
that lowered body temperature IS actually partly responsible
for some of CR's benefits. But we don't know yet.)

Brian.
--
Brian Manning Delaney
My email address is here:
http://xyz.uchicago.edu/users/bmdelane/email4.htm
[Wrists: "Leave unambiguous typos."]
Note: All statements in this article are in jest; they
are not statements of fact.
"Mein Genie ist in meinen Nuestern." -Nietzsche.
** Please do not CC your Usenet articles to me. I'll find
them.




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