Cause of aging

Steven B. Harris sbharris at
Tue Aug 25 01:44:32 EST 1998

In <35E2332A.54E407FC at> Iuval Clejan <clejan at> writes: 

>p 37: "Are aspens, creosote bushes, prairie grasses, or fairy rings
>immortal? Do the individuals age? When is each born and when does each
>die? There are no simple answers.
>    One could also make a powerful argument that even trees and plants
>that propagate only by seeds are immortal. The seeds, although they
>eventually separate from the plant, are a physical continuation of the
>parent and give birth to living progeny. This argument applies equally
>well to humans and other animals, whose 'seed' also separates from its
>producer, fuses with another cell, and starts a new individual.
>Individuals may die, but the germ plasm is immortal."
>So I had forgotten that the aspen brings a new generation forth by
>out shoots instead of (of in addition to?) seeds. But I think you
>have a hard time arguing that an individual aspen is potentially
>You would have to then concede that an individual human is also
>potentially immortal (as long as he and his descendents keep
>The differences between detaching the seed from the individual, and
>sending out shoots a few feet a way (which are still connected by the
>roots to the original live individual at the time of their sprouting)
>probably purely semantic.

    There's no such thing as a "purely semantic" question in talking
about the aging of the individual, unless you're willing to conceed
that what you call an "individual" is purely semantic.  At that point,
as you note, we're done with questions of aging.  Germ lines don't age.
The only question is where, among all that replicating plasm, you have
separate individuals.  If they remain all connected together (as in
aspens), it's a toughie.

    For organisms with central nervous systems (essentially: brains),
the division into separate individuals is more natural.  Chang and Eng
may stay connected as Siamese twins, but you still call them two
individuals due to the two brains.  Thus, brains introduce aging.  It's
liguistic.  If you grew a new head every 100 years and the old one
beside it then died, and otherwise you didn't age, would you be
ageless?   That would all depend on the survival of your memories.
If they were somehow transfered to the new head, we'd say you were
ageless (but had really bad dandruff).  If not, we'd say you died and
your body grew a new head, and a new person.

   So now we see that "aging" as we talk about it here on this form, is
not really a biological process, but one of definition of the
individual, which is not really a biological entity in humans, but
rather a more insubstantial being composed of information (software). 
"You" are not your cells, but rather your memories.  The cells may be
replaced, but if your memories stay intact, "you" survive.  And by
definition, do not "age" (though you may grow older).  

                                     Steve Harris, M.D.

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