re: computer virus

John Wilkins (wilkins@wehi.EDU.AU)
Fri, 05 Nov 1999 09:51:40 +1000

Date: Fri, 05 Nov 1999 09:51:40 +1000
From: John Wilkins <wilkins@wehi.EDU.AU>
Subject: re: computer virus
In-Reply-To: <>

On Thu, 4 Nov 1999 09:18:34 +0100
(Gatherer, D. (Derek)) wrote:

>One of the highest spontaneous mutation rates per gamete per sexual
>generation, is at the yellow body locus in Drosophila where it is as
>high as
>1 in 10,000, but of course the yellow body locus is probably a few
>bases in length, so that would be a rate of about 1 in 20 million bases
>gamete per generation.
>At the other extreme, the streptomycin sensitivity locus in E.Coli is
>only 1
>in a billion per cell per division, or about 1 in 2000 billion bases.
>These figures neglect neutral mutations eg. mutations which are
>in terms of phenotype, so for the sake of caution we could cut them by
>order of magnitude, and say that the lowest fidelity biological system
>one error per 2 million bits, and the highest is one error per 200
>Are self-replicating computer programs higher fidelity than that?
>Figures from Sager R and Ryan FJ (1961) Cell Heredity, Wiley, New York.

It's not so much the fidelity as the difference in functionality. A bit
shift or other kind of point mutation in a von Neumann program is likely
to generate a crash because the system is lacking in redundancy. But
molecules have a vastly greater and less strict set of binding
affinities. If a molecules is deformed, it will still probably bind to
or act as a substrate to *something*. Hence, gene products are able to
vary a lot and still function, while machine code tends to be much more
restricted - the only code that can vary randomly and still work is code
that doesn't get executed.

This limits the possible states the code can occupy and makes random
changes unlikely to hit on a functional alternative, where molecular
evolution is able to do this all the time.


John Wilkins, Head, Graphic Production The Walter and Eliza Hall Institute of Medical Research Melbourne, Australia <mailto:wilkins@WEHI.EDU.AU><> Homo homini aut deus aut lupus - Erasmus of Rotterdam

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