Received: by alpheratz.cpm.aca.mmu.ac.uk id KAA28524 (8.6.9/5.3[ref pg@gmsl.co.uk] for cpm.aca.mmu.ac.uk from fmb-majordomo@mmu.ac.uk); Thu, 17 Jan 2002 10:49:48 GMT Message-ID: <3C46AB64.7060406@bioinf.man.ac.uk> Date: Thu, 17 Jan 2002 10:45:56 +0000 From: Chris Taylor <Christopher.Taylor@man.ac.uk> Organization: University of Manchester User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.0; en-GB; rv:0.9.4) Gecko/20011019 Netscape6/6.2 X-Accept-Language: en-gb To: memetics@mmu.ac.uk Subject: Re: Do all memes die out or evolve? I think not. References: <F217O4SLC7mnRrqnZ6t00020384@hotmail.com> <008d01c19f26$4e9a6740$4c87b2d1@teddace> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 8bit Sender: fmb-majordomo@mmu.ac.uk Precedence: bulk Reply-To: memetics@mmu.ac.uk
Dace wrote:
>>>Just because memes are liable to arrive at an optimal state doesn't mean
>>>they aren't still products of evolution. The same thing occurs in the
>>>natural environment all the time. Organisms get to a certain point where
>>>they fit their ecosystem perfectly.
>>>
>>>
>>I didn't realize evolution was about perfection. Are you sure you haven't
>>conflated evolution with some outdated natural theological view long
>>replaced by Darwin's evolution via selection?
>>
>
> No one has said anything about theology except you. Try not to be so
> literal. We're just chatting here, Scott.
>
>
>>There's the difference between stabilizing selection which would keep a
>>feature of a population at a satisfactory (ie- just getting by) state
>>within
>>a stable ecological context and directional selection which takes the
>>population toward a different state "better" for a different ecological
>>context when this context has itself changed, along with the playing
Sorry in advance - this bloated out of all proportion...
What we're on about here is local optima and (the usually impossible to
find or even define especially in a dynamic world) global optima. It is
quite legitimate to sit on a local optimum for ages. Coelacanths
(spelling time...), tuataras, some cycad ferns, cyanobacteria etc.,
ginkgos, sharks and other cartilaginous fish to an extent, crocodilians,
arachnids - all offer examples of not really changing a whole hell of a
lot over a long time. If we talk about ecosystems, many persist for
extended periods, even though the players may change, because ecosystems
have two opportunities for neutral change between their three levels.
Nothing is ever a perfect fit though, it's just a question of staying as
high on the fitness landscape as you can. If nothing better comes along
(through external [ecological-environmental] or internal [genetic]
change), and noone wipes you out, you'll probably stay more or less the
same. That's it. I'd (just about) guarantee though that there'll always
be something you could 'improve' but there will be some conflict
(antagonistic pleiotropy and or epistasis and or some phenotypic design
tradeoff) preventing the 'improvement' from evolving. Therefore lasting,
but not perfect. Unless you mean perfect to be 'as good as it can get'.
Also considering genes in isolation, homeobox genes are *really* ancient
(animal) patterning genes that you can take out of a human, put in a fly
(for god's sake) and they work fine - that is what I call sitting on
your optimum; bear in mind though that that optimum is defined wholly by
context (Francesca's point), but then most are - what do arbitrarily
designed creatures consume - other arbitrarily designed creatures (plus
light and/or some chemicals).
Neutral evolution needs to be considered here, but only to be dismissed
as long as we stick to considering phenotypes (which is all that memes
have - more akin to Kauffman's coadapted complexes / Maynard Smith and
Szathmary's hypercycles than a genotype/phenotype structure).
Memes seem to have a phenotypic and ecological level, but what about the
encoding? Are they an expression of something, or are they just sort of
run 'in simulation' in their mind in the sense that they are their own
encoding (I'd go for the latter, or a latte).
As an aside it annoys me that coffee bars *have* to have a name for
normal coffee (not latte/espresso/cappucino/mocha whatever) so it
becomes cafe americano. There you go - that naming is only fit in the
context of all the others having an extra bit of name...
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Chris Taylor (chris@bioinf.man.ac.uk)
http://bioinf.man.ac.uk/ »people»chris
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
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