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From: bjm@dcs.ed.ac.uk (Bruce McAdam)
Subject: Replica/replicant, evolution of crystals (was Re: Exact Duplicate? (Was Re:Brain and body . . .)
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Date: Mon, 5 Feb 1996 09:18:42 GMT
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In article <4ehd83$a9u@cloner2.ix.netcom.com>, attila1@ix.netcom.com(Libertarius )
writes:
[Regarding 'exact' duplication of a brain]
>     There is no such thing as an "exact Duplicate". Otherwise your
> cells would duplicate themselves exactly and you would go on as an
> infant (or an egg and sperm) forever. There would be no evolution,
> since evolution results from inexact duplication. Etc. etc.

This is a completely irrelevant point, the duplication in question is not
gained through the normal apparent biological duplication it is more like
photocopying a person (or moulding from an imprint or building a model
from a photograph).  The discussion is also about the brain in a particular
state and this is not inherited (you would be born with your mother's
memories if it was).

The apparent duplication we see in biology (I am a bit like a duplicate of
my Dad, a bacteria are a bit like duplicates of each other) is definately
not duplication as only the DNA is duplicated (and not accuratly), not
the cells.  We have to draw a distinction between replicas (people, cells)
and replicants (genes, DNA).

Libertarius' argument can be extended to simpler structures though.  A
salt crystal forms by a duplication of a simple structure, this does replicate
very accurately so we only see one form of crystal at a particular place
and do not get evolution of improved salt crystal structures.

(This is why we need plastic programming structures like Tierra code in 
alife rather than the rigid code of normal computers)

-- 
   ___          ___     Bruce J. McAdam
__/__ \__    __/__ \___ Computer Science Undergraduate
_____|_| \__/_____| |__ The University of Edinburgh
  \____| |_____| |_/    bjm@dcs.ed.ac.uk
     \___/  \___/       http://www.tardis.ed.ac.uk/~bjm/
