Re: OOL X - The origin of the RNA world.

tinyurl.com/uh3t <rem642b@xxxxxxxxx> wrote or quoted:
> > From: Tim Tyler <tim@xxxxxxxxxxx>

> > I think you have to have some sort of evolving system before the term
> > "genetic" becomes very useful.
>
> I'm not sure what you mean by "useful", like useful as a word to
> describe what's happening, or useful as a process for evolution. If the
> latter, I agree. But if the former: "Genetic" merely refers to any data
> that is usually retained across many generations (of replication).
> Already when the first successful replicator occurs, the single "1" bit
> in the bitmask of possible replicators is turned on and stays on for a
> very long time, so it surely qualifies as "genetic".

Evolving systems don't necessarily have to have clearly defined
generations - nor do they need to replicate anything.

What they do need to do is preserve information across reasonable
spans of time.

> > I do have some sympathies for the position of requiring a minimum
> > amount of heritable information to qualify.
>
> Summarizing what I posted a few months ago: With a single replicator,
> it's all or nothing, if that one replicator mutates to something else,
> it probably no longer replicates, so it goes extinct while the original
> replicator continues as before, so no evolution is possible with that
> one replicator per se. But when many different replicators are trapped
> together in some kind of "cell", so their fates are linked, then for
> that "cell" as a whole there's a "genome" consisting of the bitmask
> saying which particular replicators are each such "cell". If such a
> cell can grow physically and then split somehow, such as by being torn
> apart by shear forces, then each daughter "cell" will have a copy of
> the bitmask (with occasional losses, but all high-quantity replicators
> would surely get at least one copy in each daughter cell, so generally
> both daughter bitmasks are identical to the parent). That genome can
> then evolve (change what bits are on) by some random replicator from
> outside joining the collective by accident, or by some already-member
> replicator going locally extinct. The various different such "cells"
> with different bitmask genomes can then compete with each other for
> ability to grow and divide given limited food resources, so we have
> true Darwinian evolution already.
>
> So for just the definitin of "genetic", a single bit turned on is
> sufficient, but for something that can evolve via group selection of
> the many replicators sharing a "cell", you need several replicators not
> just one.

The issue isn't simple. For one thing, you can't assume identifiable
replicators exist in the system.

If you can only go on information in the system which is preserved
over time - and if you fail to specify some minimum threshold of
such information - then you wind up with rivers storing their paths
"genetically" and the earth remembering which way it is spinning
"genetically".

IMO, such usage would go far beyond conventional usage of the term.
--
__________
|im |yler http://timtyler.org/ tim@xxxxxxxxxxx Remove lock to reply.

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