In article <3611D747.20CE8221 at notarealaddr.ess>, bmdelaney at notarealaddr.ess
>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!
Not at all. As I said in a previous post this is an important issue to
define maximum life span, since it is the yardstick by which we measure
>> 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?!
I know of no controversy on this issue. As you mentioned the genome does
change through gene deletions and differing genetic expression over time.
The shortening of the telomeres is just another example of this process. You
are a different person than you were when you were 20 years younger but I
think you could still be classified as human.
The difference is the "un-natural" change in telomeric length that you
postulated. Much as an un-natural change in the sequencing of a gene would
be considered a mutation this un-natural change in telomeric length would
also be a mutation.
>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.
Here you are proposing a process and a substance that do not, to our
knowledge, exist. But accepting your premise that such a process and
substance could "naturally" exist, then I would have to agree that human life
span would have to be accepted at that level to which this naturally
occurring substance could get us.
>>>> 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
Accepting this unlikely premise, as noted above, we would have to change the
figure we use for defining human life span.
>> 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
Yes and we have agreed on this as acceptable. If you do in fact find some
process and some substance that could allow humans to live to 140 then we
would have to change our figures. But absent any evidence to support this
hypothetical scenario we are left with that which we do know at the present
time. That is; no one has been known to have lived beyond 122 years of age.
Even allowing for the maximum possible life span, absent actual observation,
you would have to demonstrate a mechanism or process by which this could
occur and have the research to back it up.
>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,
This could very well be argued but until the research shows that this is at
least probable it does not effect our definition of life span.
> 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 gave
>above) we can't say that it extends human life span after
>just one person has taken it and lived to 200.
I agree! Once it has been observed that a person lives 200 years absent
experimental intervention then life span would, of necessity, be accepted at
>This seems to be not a very useful definition.
If processes to extend human life span were that numerous and changing from
year to year I might agree that it wouldn't be very useful. Unfortunately
that isn't the case and no process has demonstrateably shown that human life
span can be extended much beyond 120 years with or without researcher
Thomas Mahoney, Pres.
Lifeline Laboratories, Inc.