_Plausibility of Life_ -- facilitated variation in evolution

Remember all the hundreds of debates in t.o. between creationists/IDiots 
and evolutionists about whether random mutation can produce the 
complexity of life?  Sean Pitman comes to mind here.  This book suggests 
that both sides have been wrong, or at least the evolution side has not 
been completely right in the details.

The Plausibility of Life: Resolving Darwin's Dilemma (Hardcover)
by Marc W. Kirschner, John C. Gerhart, John Norton (Illustrator)

www.amazon.com/exec/obidos/tg/detail/-/0300108656?v=glance

 From Booklist

*Starred Review* Since its publication a century and a half ago, 
Darwin's revolutionary theory of evolution has explained very well how 
natural selection winnows out the mutations most helpful in fitting a 
species to survive. Now two neo-Darwinian biologists have boldly 
extended the original paradigm by showing how the deep molecular biology 
of the cell actually fosters biological novelties when plants and 
animals need them most, not merely when random chance generates them. 
Surveying the latest genetic research, Kirschner and Gerhart adduce 
evidence that nature has preserved and compartmentalized those core 
innovations that maximize the adaptive flexibility of species from 
yeasts to humans. The dynamics of protein chemistry and the plasticity 
of embryonic cells combine to make creatures capable of assuming many 
different forms in a wide range of environments. The deepest and most 
stable processes in biology, thus, are those that prime species for 
further evolution. It is this biological priming for evolutionary change 
that Darwin's great rival Larmark was groping toward when he stumbled 
into error. And it is a theoretical realignment that acknowledges this 
"facilitated variation" that Darwin's disciples now need in order to 
fend off skeptics who have latched onto the implausibility of the old 
scientific orthodoxy premised on entirely random and gradual change in 
species. Remarkably lucid and comprehensive, this new theoretical 
synthesis will thus shift the grounds for debate in the controversy 
surrounding organic evolution.

 From one of the reviews:

The authors emphasize early on that mutation only alters what already 
exists, and so it is imperative that an explanation be found that shows 
how one structure can be transformed into another. It must be shown how 
random genetic changes can result in innovations that have high utility 
for the evolved organism. The pillar of the authors' theory for how this 
is done centers on the notion of `facilitated variation', and they give 
detailed arguments throughout the book that support it. Most 
interestingly, this notion is not based on the genotype of the organism, 
but rather on its phenotype: random mutations lead to nonrandom 
phenotypic variation. The authors are careful though to point out to the 
skeptical reader that this notion is not Lamarkian, but instead refers 
to the capacity of the organism to generate phenotypic variation as a 
response to genotypic variation and the nature of this variation. They 
leave to other researchers the study of the capacity of a particular 
population to evolve.

Facilitated variation holds that since phenotypic variation is dependent 
on the modification of what already exists, it cannot be random (even 
though mutation is itself random). In addition, the variation of the 
phenotype of an organism, which involves the changes of components and 
processes, is subject to constraints. However, in this same variation, 
other components and processes of the phenotype can be deconstrained. 
There is therefore a trade-off involved, with the result that (less 
lethal) phenotypic variation can be accelerated when these deconstraints 
are present. The parts of the organism that are constrained that authors 
refer to as the `conserved core processes' of the organism. These 
processes can be viewed as those that remain fixed under the 
evolutionary transformations of the organism. Although the authors do 
not refer to it in the book, and in fact may not be aware of it, this 
view of conserved processes in evolution is discussed in the 
mathematical literature under the guise of what are called `evolution 
strategies.'


    --dkomo@xxxxxxxx

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Relevant Pages

  • Re: Speculative Design Hypothesis (with predictions)
    ... So where is the testable falsifiable hypothesis for how evolution ... so why hasn't our species been extinguished by random ... they depends on the environment plus all the other erstwhile mutation. ... You speak of "miscopying" as the source of variation. ...
    (talk.origins)
  • Re: goalpost "whosh" in re What evidence do you require?
    ... mechanism of evolution is inherited random genetic ... organism A is inherited by its offspring, ... This mutation must not prevent organism B from ... and in which the variation ...
    (talk.origins)
  • Re: goalpost "whosh" in re What evidence do you require?
    ... mechanism of evolution is inherited random genetic ... organism A is inherited by its offspring, ... This mutation must not prevent organism B from ... and in which the variation ...
    (talk.origins)
  • Re: goalpost "whosh" in re What evidence do you require?
    ... mechanism of evolution is inherited random genetic ... organism A is inherited by its offspring, ... This mutation must not prevent organism B from ... and in which the variation ...
    (talk.origins)
  • Re: An introduction
    ... selection and an oversimplified concept of mutation via genetic ... variation, but it speaks little to the source of variation. ... and itself is a stronger force of evolution than mutation. ...
    (talk.origins)