From: Chris Taylor (firstname.lastname@example.org)
Date: Wed 18 Feb 2004 - 09:52:24 GMT
And let's not forget that organismal form is only the result of the
interaction between genome (plus info in cellular components) and _the
environment_ which is subject to change, confusing any attempt to
The genome is an important environment, for genes -- foreign DNA from
retrowhatevers, conflicts in silencing between the sexes, the constant
trade-offs between suboptimal compromises (neutral evolution at the
phenotypic level -- shorter legs, but longer neck), fiddling with
expression through chromosomal rearrangements, accidentally finding
yourself part of a new species because of a Wolbachia infection. All
these things (and a metric tonne more) confuse the preservation of form.
What you get out of evolution is a real mish mash, that works. There are
about a zillion constraints, most we'll never know about, and yet some
organisms still manage to do flashy things like encode genes on both of
the complementary strands of the same stretch of DNA, or overlaid in
more than one reading frame.
Lesson One: This is really goddamn complicated, and we have a
measurement problem. Sounds a lot like memetics.
Fact we can borrow from biology #1: Selection on individuals is not
appropriate, nor selection on kinds (group/species selectionist);
evolution happens (to repeat Scott) in populations. For instance I'm
sure when talking about French, Canuck French, French creoles etc. it is
a lot easier to talk about populations of speakers than of individuals,
or of 'French'.
Scott Chase wrote:
>> From: "Dace" <email@example.com>
>> Reply-To: firstname.lastname@example.org
>> To: <email@example.com>
>> Subject: Re: memetics-digest V1 #1480
>> Date: Tue, 17 Feb 2004 13:59:44 -0800
>> > From: Keith Henson <firstname.lastname@example.org>
>> > Subject: Re: the meme/brain problem
>> > > > Evolution does not happen to organisms. They live or die,
>> > > > fail.
>> > >
>> > >An organism is not just a sack of molecules. What evolves is the
>> form of
>> > >organisms rather than their material constituents.
>> > When you are talking about Darwin and evolution, *species* are the
>> > subject to evolution. *An* organism (individual) is stuck with the
>> > has.
>> An organism is a living form that's stuck with a particular set of
>> (though, over time, it undergoes a complete changeover of molecular
>> constituents). An individual is a materialization of a collective form.
>> What evolves is not the materializations but the form. However, as
>> emphasized, evolution is propelled forward by adaptations made by
>> organisms. Though Darwin had no idea how such inheritance occurs, he
>> maintained to the end that without this ability to pass on acquired
>> characters, evolution as a theory is dead on the water. For Darwin, the
>> organism is the central actor in natural evolution, and I would add
>> that the
>> same is true of the person in cultural evolution.
> Individual organisms are the level at which selection operates, but
> populations are the level at which evolution occurs. The quick and dirty
> definition of evolution is ("not again!" they scream from the peanut
> gallery) 'changes in allelic frequencies within a population over time'.
> Thus (is this where I insert a Q.E.D.?) evolution requires a group of
> organisms or *population* and a time period, which can be taken as
> subsequent generations. Flail around as you will, you are wrong on two
> counts if you assert evolution happens to individuals. Not only are you
> ignoring populationns, you are ignoring the generational aspect of
> Individuals can change (or adjust) during a lifetime to match the needs
> imposed by the environment within a reaction norm influenced by their
> given genetic repertoire, but they are not evolving. Their success at
> surviving and reproducing may impact the allelic frequencies of their
> population, but this is a shift in focus, from selection operating upon
> an individual to the change in proportions of individuals with given
> traits in a population over generational time.
> And given the definition of evolution above, if the population size is
> small enough, alleles can fluctuate in frequency due to nothing more
> than sampling errors. A selectively advantageous allele could become
> lost to a population because of chance or a selectively detrimental
> allele fixed likewise. This is genetic drift which gives another good
> reason not to equate selection with evolution (evolution occurring in
> populations where selection operates upon individuals being another good
> reason not to conflate evolution and selection).
> Since a species is a group of populations, Keith is way more on target
> than you are. The definition of evolution in the Glossary of Futuyma's
> _Evolutionary Biology_ (3rd edition) mentions changing populational
> proportions within a species as a subdefinition.
> So there.
> Stay informed on Election 2004 and the race to Super Tuesday.
> 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
-- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Chris Taylor (email@example.com) MIAPE Project -- psidev.sf.net ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ =============================================================== 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
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