Message-Id: <339F17B6.3B4D@rug.ac.be>
Date: Wed, 11 Jun 1997 14:25:10 -0700
From: Mario Vaneechoutte <Mario.Vaneechoutte@rug.ac.be>
To: memetics@mmu.ac.uk
Subject: Re: Replicators (and the use of code)
Mark_M_Mills wrote:
>
> Mario,
>
> > In that sense a photocopier is a replicator, still genes and
> >memes are not, although also the word replicator is used for them. An
> >enzyme and a photocopier are replicators, cells are self replicators,
> >genes and memes are information which is replicated.
>
> This makes a great deal of sense to me.
>
> There are some real problems with the popular use of the term 'gene.'
>
> We ought to look a the concept 'gene' for a moment. Genes, as
> understood in the popular mind, are not really a valid scientific
> concept any more. The 'bead' model has been discounted for years. A
> segment of DNA code may used in a wide number of processes, linking up
> with different segments of code and producing different proteins. A
> better concept for genes would involve something of a 'holographic' data
> storage system. The code is all discrete, but the data map is
> non-gramatical. The process creates the code unit.
> The 'memory' and 'product' cannot be separated from the process. Genes
> continue to be a useful concept as a reference to 'inhereted' chemical
> processes because a gross segment of code can be identified as
> containing the process code. Isolating the specific code is currently
> impossible.
>
> As pointed out earlier here, there are no 'behavioral' codes
> in the chromosomes. The codes simply create enzymes that interact
> together. The codes are not blueprints, but producers of a balancing act.
>
> Thus a 'gene' is an invisible unit of code. One segment of DNA can mean
> different things in different processes. We can identify genetic code and
> the 'chunks' that hold them with some ease, but not the 'gene' itself.
>
> If we want to use the 'meme' - 'gene' analogy, we are stuck with the same
> subtle problem. Evidence of 'coding' should be easily found. Chunks of
> codes containing a variety of memes should easily be found, but 'memes'
> themselves will be invisible unless we understand all the processes
> involved with code retreival and processing.
>
> The other problem with using the term 'gene' is the popular assumption that
> everything important, the 'whole blueprint' is stored in the gene. This
> of course is missleading. As you pointed out earlier, a wide variety of
> cellular matter is passed on to the offspring. In particular, the host
> cell provide the replica with active processes and a sense of rhythmicity.
>
> The gene/meme analogy looks at first glance, but there are certainly a lot
> of linguistic pitfalls.
Indeed, I agree with the difficulties of the gene and meme concept (and
of almost any concept). The problems are similar to the species concept:
where do you draw the boarder?
Here are some other problems than the ones you address.
When are two copies of genetic information the same gene? When their
sequences are identical they are no doubt the same. What when a single
nucleotide differs? It may be a silent mutation and the material
phenotype (the protein) will have an identical amino acid sequence.
These alleles still encode for exactly the same protein. In case the
single nucleotide difference changes an amino acid we have a different
protein sequence. Still this amino acid change may change nothing to the
functionality or efficacity of the protein. There is no way for
selection to make a difference between both proteins (as is also the
case for silent mutations). Yet, in another situation, the functionality
may change because the changed amino acid happens to be in e.g. the
reactive site of the enzyme. Is this still the same gene? Is the silent
mutant still the same gene?
Similarly, when you look through evolution you see how some genes with
comparable function have been preserved (think of homeobox genes). Is
such a family of genes to be considered as the same gene or as different
genes? How many mutations are needed to consider a gene different from
its predecessors? Etc.
Each time humans make distinctions, these are artificial to some degree.
My interest is in memetics, not in genetics, but I think it is worth
mentioning these problems from genetics to show that there are a lot of
problems with concepts which nonbiologists doing memetics take for
granted. It is only when you know how problematic all these concepts are
and how careful you have to deal with them, that you can go further and
think about things like memetics where many concepts have been borrowed
from genetics (very often erroneous or problematic concepts).
Of course, we meet the same problems with the concept of meme.
-- Mario Vaneechoutte Laboratory Bacteriology & Virology Blok A, De Pintelaan 185 University Hospital Ghent Belgium 9000 Ghent Tel: +32 9 240 36 92 Fax: +32 9 240 36 59 E-mail: Mario.Vaneechoutte@rug.ac.be Editor J. Memetics: http://www.cpm.mmu.ac.uk/jom-emit =============================================================== This was distributed via the memetics list associated with the Journal of Memetics - Evolutionary Models of Information Transmission For information about the journal and the list (e.g. unsubscribing) see: http://www.cpm.mmu.ac.uk/jom-emit