X-Message-Number: 10631
Date: Fri, 23 Oct 1998 10:10:24 -0400
From: Thomas Donaldson <>
Subject: CryoNet #10626 - #10629

Hi Mike!

I'll have to hunt up the reference, but at one time someone interested
in what the "natural lifespan" of mice might be actually studied the
population of mice on an island off the coast of Britain. Very few
mice managed to live for longer than 1.5 years. Lots of disease,
predation, etc. 

In that context the whole idea of CR as increasing "natural lifespan"
becomes hard to define in the first place. CR does increase lifespan.
I'm not arguing against that. The problem is that even the mice in 
our labs aren't living a natural lifespan --- even if they overeat
they live much longer than their fellows in the wild. Moreover, from
what I hear from those who have raised CR mice, they tend to be 
weaker than normal (yes, this is hearsay). CR mice in the wild
might well live for less time than normal mice, that eat as much
as they can when they can get it. (CR restriction is not the same
as mild starvation: there is much care taken to make sure the animals
get all their needed vitamins, minerals, etc). 

Frankly I strongly suspect that the entire idea of lifespan (natural
or not) arose among human beings after we became urbanized and 
came to realize that people die no matter how rich they are and
how well they take care of themselves. Many primitive peoples (fast
ceasing to be primitive) have been reported to believe that ALL
deaths were caused, by some human enemy or other mistake. Since 
they did not naturally live much beyond 50 years, not long enough
to show the signs of real old age, such a belief would even be 
natural. "He died because someone put a spell on him that made him
sick". This would be hard to prove without a time machine, since
people aren't stupid, and once the idea of "natural inevitable
death" arose in the cities, it would spread easily everywhere, even
to nonurbanized hunter-gatherers, at least those who lived nearby.

Even a few centuries ago the collective lifespan curves were closer
to exponential falloff than now (when we have a big bump, with
relatively few deaths occurring for some time until the rate starts
increasing). Individual wealthy people did live much longer even
in Classical times, but then they were a very small part of the
population which bulks large in our imagination only because they
tended to be literate and wrote books to tell us about themselves.

And the Epic of Gilgamesh comes down to us from the times of early
cities, when people generally came to realize that death would
get everyone --- not just the poor, but even the wealthy. (It's
much more profound than the Greek and Roman myths, and deserves to
be read by more people even now). 

			Best and long long life to all,

				Thomas Donaldson

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