Where are the perfect repair systems?

William Bains william at wbains.u-net.com
Thu Feb 6 12:54:43 EST 1997


In article <Pine.OSF.3.95.970201211028.1421B-100000 at fas.harvard.edu>,
Jurgen Kaljuvee <kaljuvee at husc.harvard.edu> wrote:

> 
> A natural question arises: "If evolution has developed everything
> imaginable, why hasn't it developed perfect repair systems?"
> 
> To answer the question, consider the following thought experiment.
> Suppose that several million years ago there was a species of, say, fish 
> that developed a perfect repair systems and as a result couls achieve a
> lifespan that extended to several hundred or even thousands of years.
> If so, why don't we see the species today?  Where did it disappear? The
> answer is that by attaining perfect repair system, the species lost the
> capacity for mutation and variation and consequently for evolution. It
> was soon outcompeted by a species which, though mortal on the individual
> level, carried superior mutations as a species.  Evolution presumes
> variance, selection and mortality.
> 
> So if human species developed perfect repair systems, not through
> evolution, but artificially in a lab (as we have done so much else) would
> it mean the end of species? Maybe in the long run, say in few thousands
> years, when we would be outcompeted by apes with superior mutations (IQ =
> 250) but that's not my top concern right now as my clock is ticking
> minutes and hours, not in thousands of years...
> 

Is this right? Aging is due to somatic errors - errors in the
non-germ-cell tissues. Mutation is caused by changes in the germ cells. We
could imagine an organism with perfect repair (including DNA repair) in
the soma an organism could attain immortality, and still have a mutation
system that applied to the germ cells, analagous to the directed mutation
mechanism that generates variation in immunoglobulin gene variable
regions. 

In reality, of course, 'perfect' repair requires an unlimited energy
supply, and it is this trade-off between using energy for reproduction and
for repair that means it is evolutionarily advantageous to age.

-- 
William Bains




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