[FRIAM] FW: Heritability and generative entrenchment

[Phil]

Part of the problem with these conceptual models is that it's very hard
to correlate them with observations.  I do entirely agree with your
proposition, though, that given the idea of fitness landscapes, that
neutral genetic change could accumulate and provide a way of 'tunneling'
your way out of a canyon.   That's particularly because of the
phenomenon of random walk that applies to neutral variation alone as far
as I can tell.   Paleo's for years have tried to apply random walk to
non-neutral change to explain unusual progressions, failing to make the
critical observation that random walk only operates when the individual
steps have no effect.   

To test that as a dominant mode of evolution would probably take data
that does not exist (the gaps problem) but could potentially be done if
large changes could be shown to not also demonstrate flow.  Flow and
random walk are anathema to each other, the structural difference
between continuity and noise.  Some of my math helps for that, but
better is needed.

The reason for my initial caution in agreeing, though, is that the whole
concept of fitness landscapes, however useful as a thought experiment,
has dubious physical existence.  The question, after all, is where form
comes from and if you just postulate that form comes from a 'template'
for everything to just jostle around and fit into, we're begging the
question entirely.  Then there's the infinite dimensionality problem,
and that innovation has to be treated and the discovery of new
dimensions of relationships.  Perhaps fitness landscapes are a mental
note pad or projection and not part of the actual subject of study.
They also presume universal random variation in the genome and what you
find is form branching in history with more change at the tips than in
the trunk.  They don't explain the kind of stability observed. 




Phil Henshaw                       ¸¸¸¸.·´ ¯ `·.¸¸¸¸
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> -----Original Message-----
> From: Friam-bounces at redfish.com 
> [mailto:Friam-bounces at redfish.com] On Behalf Of Carlos Gershenson
> Sent: Sunday, May 28, 2006 11:53 PM
> To: nickthompson at earthlink.net; The Friday Morning Applied 
> Complexity Coffee Group
> Cc: ppgb at cam.ac.uk; Jaan Valsiner; rsokol at clarku.edu; 
> lrudolph; dwilson at binghamton.edu; echarles; jogreen; 
> jcschank at ucdavis.edu; w-wimsatt at uchicago.edu; sbarr; Gbarker; elescak
> Subject: Re: [FRIAM] FW: Heritability and generative entrenchment
> 
> 
> Nick,
> 
> I don't know if somebody has mentioned already neutrality (search  
> Google Scholar for Kimura): neutral mutations that have no effect in  
> the phenotype allow the exploration of the parameter space without  
> losing fitness, so it is a way out of local 
> optima/entrenchment... And actually there's lots of 
> neutrality in genomes, not only to  
> explore the genome space, but also as a robustness measure against  
> random mutations... If every mutation you could do would change your  
> phenotype/fitness, it would be very difficult to evolve anything...
> 
> Best regards,
> 
>      Carlos Gershenson...
>      Centrum Leo Apostel, Vrije Universiteit Brussel
>      Krijgskundestraat 33. B-1160 Brussels, Belgium
>      http://homepages.vub.ac.be/~cgershen/
> 
>    “Tendencies tend to change...”
> 
> 
> 
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