>> In article <3611468C.672E3870 at notarealaddr.ess>,
>bmdelaney at notarealaddr.ess says....
>>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
>>>>"Maximum life span is that achievable without the
>>intervention of a genetic-tinkerer."
> There are at least two other and probably more
> non-genetic methods of possibly extending human
> life span. One is to maintain cellular viability
> and length between replications.
[Some more mostly off-the-point (though very interesting)
There almost certainly are other ways of extending human
life, and I see now that the "genetic-tinkerer"-based
definition doesn't capture your views completely. But I
still don't see how what you've written helps us with the
def. of max. life span. Maybe you're just tired of the
question -- fair enough!
> To determine if these strategies are successful
> we need to have a reliable yardstick in our
> definition of life span. As you suggested on
> your web pages, any research into life span
> needs to control for the effects of CR or they
> may be getting false results. I suggest this
> also has to be taken into consideration when
> evaluating the results of CR itself.
No argument from me here. I still don't get your emphasis
(or the point of your shift in emphasis) though. "Reliable"
is a different criterion from what you've been putting
forward so far. Maximum life span of animals, of a given
species, fed ad libitum, is extremely reliable.
>>> 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
> Your assumption is in error. Telomeres are an
> integral part of the genome. The research
> often refer to them as Telomere DNA, consisting
> of TTAGGG repeats. Un-natural changes in the
> telomeres would and are considered to be
> genetic mutations.
I think the claim that telomeres are "integral" to the
genome is somewhat controversial. If true, we'd have to say
my genome is changing as I age. My genetic material is
certainly changing, but "my genome"? Even if we decide it
makes sense to say that my genome is changing as I age
because of telomere-shortening, then you'd have to agree
that CR changes the genome as well, since it induces many
changes in genes (fewer deletions, possibly even slower
telomere-shortening!). So I'm now a diff. species because
I'm on CR?!
In any event, the changes in my example aren't "unnatural,"
since they occur as a result of a natural process mediated
by a substance found in nature, to which we respond in a
natural way by lengthening our telomeres.
>>> 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
> And when we find that person who ingested this
> substance and lived to 140 we can then say that
> the natural human life span is 140 years. Until
> we find him it's still 120 years.
Hmm.... I think I'm ready to give up. Earlier, you said that
maximum life span should be defined in a way that _doesn't_
rely on the mere fact of some researcher or other finding or
failing to find an animal that has made it to its "natural"
limit. That is, you agreed to this:
Maximum life span = "the life span achievable without
Now, you're switching YET AGAIN to this: "the life span
achievED without researcher intervention." This is a very
It means that if we had a very good theory that argued that
Calorie Restriction could enable some people to live to 140,
 we can't say yet that the maximum human life span is 140
until someone actually lives to 140 (this part isn't so
strange). And  forevermore after someone lives to 140, we
MUST say that the maximum human life span is 140, and we
CAN'T say that CR extends it, because the record would have
to be broken AGAIN for us to be able to say this. Likewise,
if a natural substance is found which extends human life
span to 200 (a substance that fits the description I hgave
above) we can't say that it extends human life span after
just one person has taken it and lived to 200. This seems to
be not a very useful definition.
Brian Manning Delaney
My email address is here:
[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.
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