Re: Structuralism and evolutionary theory

From: Terry M. Gray <>
Date: Sun Oct 30 2005 - 18:59:18 EST


We've been down this path several times on the list over the years
(check the archives!)--although I'm not sure we've always called it

One scientist who has written on this is Brian Goodwin, How the
Leopard Changed Its Spots and Signs of Life (with Ricard Sole). You
also see this in Stuart Kauffman. The early 20th century biologist
D'Arcy Thompson (On Growth and Form) is part of this school. Stephen
Jay Gould wrote a Foreward to a 1992 reprint.

Structuralism does not deny evolution. However, it admits that
natural selection is not the only force at work in biology. There are
"laws of physics", "laws of chemistry" (like those mentioned by Pim),
and also "laws of biological form". Personally, I think that some of
Cornelius's questions about convergence and developmental pathways
are answered by this point of view. Natural selection and common
descent are NOT the only "forces" that dictate the biological
landscape. This appeal to non-Darwinian forces in biology is what,
among other things, resulted in the rift between Stephen Jay Gould
and Richard Dawkins.

These "laws of form" perspectives are finding more recent advocates
in complexity and self-organization theories (hence Goodwin and
Kauffman). This perspective is on the fringe of biology in these
heady "genome" days where molecular biology is king and rich
explanations do come from genetics. But, I've long argued that the
genome, while important, isn't everything. Not everything in an
organism is determined by its genes.

Personally, I think that some of the more difficult problems in
biology--origin of life, developmental biology, the anomalies in
evolutionary biology--have their most promising solutions in this
kind of thinking.


On Oct 30, 2005, at 6:55 AM, Pim van Meurs wrote:

> Denyse posted some links to comments by Stuart Pivar
> on Gould but one aspect caught my eye "structuralism".
> I have done a little bit of research and structuralism
> is an interesting concept which combines evolution
> with morphogenesis. As many evolutionists and
> philosphers (Ruse) have pointed out evolution is in
> many ways constrained. It is constrained
> mechanically, it is constrained by laws of physics,
> it's constrained by laws of chemistry.
> I am reading a book called "the plausibility of life"
> by Kirschner and Gerhart which describes what they
> call 'facilitated variation'which argues that while at
> the genome level variation is 'random', at the
> phenotype it is not.
> Structuralism looks at the laws of physics to show how
> the embryo 'self organizes', driven by laws of physics
> and genetic information.
> The work by Gordon from the University of Manitoba is
> quite interesting
> rgordon.html
> While his main career focuses on radiology, Gordon has
> been interested and involved in emergence for quite
> some time and there are some interesting papers in his
> collection.
> Gordon shows that via gene duplication the
> dimensionality of the genome increases, disputing thus
> statements by IDCers (a discussion on ISCID's
> brainstorms comes to mind...)
> Variation and selection come to play on the copy of
> the gene (or the original).Physics however is an
> important process in emergence as well since to get
> new capabilities (emergence) physics needs to be
> represented so that selection has 'something to work
> against'.
> Structuralism argues that there is a genotype to
> phenotype mapping and that this mapping happens via
> genetics and physics.
> This concept of self-emergence means that the organism
> is both observer and designer.
> This also resolves the question raised by for instance
> Paley namely that design requires a designer.
> And although people have also argued that emergence
> requires an observer (god?),Gordon argues that the
> designer and observer are part of the same system.
> (see
> Gordon:
> <quote>Artificial life research begins from the
> premise that Alife subsumes real life. A criterion for
> emergence in Alife has been formulated that, however,
> excludes real life and postulates the need for a real
> life Designer and an Observer. This in effect
> nullifies the premise of Alife and takes us back to
> the argument for God from design of Bishop Paley in
> 1802. An alternative is to realize that Alife could
> include two properties: simulated organisms that both
> design themselves and are the observers. Self-design
> can come about via evolution in a population of mating
> organisms, especially via mutations that are gene or
> higher order duplications. Duplications permit novelty
> while retaining previously attained functions. The
> ability to observe can itself evolve, if its
> construction process evolves. This may now be possible
> to simulate, if new paradigms for embryogenesis, such
> as positional information or differentiation waves,
> prove accurate, or at least sufficiently robust to
> construct a wide diversity of observational abilities.
> The evolution of perception, however, may be limited
> by the physics available to the Alife organisms, which
> can come in three forms: simulated physics, real
> physics accessible to robots, or "Cyberspace physics".
> </quote>
> The emergence of emergence: a critique of "design,
> observation, surprise!" Riv Biol. 2000
> May-Aug;93(2):349-56.
> Rather than seeing structuralism as a replacement for
> Darwinian theory, it complements it as it provides the
> third prong of what is needed for evolution
> 1. A theory of natural selection
> 2. A theory of heredity
> 3. a theory of generation of variation.
> Alan Love, in his review of:
> Ron Amundson, The Changing Role of the Embryo in
> Evolutionary Thought: Roots of Evo-Devo, Cambridge
> University Press, 2005, 296pp, $75.00 (hbk), ISBN
> 0521806992.
> writes
> <quote>
> Another of these principles is a criterion of
> explanatory adequacy on evolutionary explanations
> adhered to by structuralist biologists, the 'Causal
> Completeness Principle': "In order to achieve a
> modification in adult form, evolution must modify the
> embryological processes responsible for that form.
> Therefore an understanding of evolution requires an
> understanding of development" (p. 176). This principle
> underlies the structuralist conception of evolutionary
> transitions, which is very different from that of
> functionalists. Functionalists explain the process of
> evolutionary change from one adult phenotype to
> another via population processes such as natural
> selection, which sorts genotypes and thereby alters
> allele frequencies. Structuralists explain the process
> of evolutionary change from one ontogeny to another
> via developmental processes such as morphogenesis,
> which can be altered in different ways to generate
> novel phenotypes. The 'Causal Completeness Principle'
> is irrelevant to the evolutionary explanations of
> functionalists.</quote>
> On Pandasthumb Andreas Bottaro comments
> <quote>Structuralism is more about the development of
> complex forms according to basic natural principles
> and rules which are not genetically/epigenetically
> encoded, but may reside in the structural organization
> of the organism itself</quote>
> of_form_over_substance_a_review_of_sermonti.html
> In "Defining Evolution" John Wilkins writes
> <quote>Process structuralism: Some changes are biased
> by their structural relations and form. The foundation
> of process structuralism was laid by D'Arcy Thompson
> (1917) and recently revived by Brian Goodwin (1994),
> and others. Complex structures and systems are not
> free to vary independent of their relationships with
> other components of the complex.
> </quote>
> vol21/1610_defining_evolution_12_30_1899.asp
> Denyse makes some predictions
> (
> challenge-to.html)
> <quote>
> 1. The structuralists will provide the best
> explanation for the Cambrian explosion (when most of
> the general types of life forms arose rather suddenly
> 525 million years ago).
> </quote>
> In fact, whether one wants to call it structuralist or
> not, James Valentine (and many others) argue that hox
> genes and the evolution of regulatory genes explains
> much of the Cambrian explosion. In the end it seems
> that it is a combination of genetics, variation,
> selection and physical constraints that explain the
> Cambrian explosion and undermine one of the icons of
> ID.
> <quote>2. However, some structures will elude a
> structuralist explanation and be accepted as
> irreducibly complex. That one goes to ID, along with
> the origin of life.</quote>
> In other words, our ignorance will guide us to infer
> design rather than admit that we just don'tknow. Seems
> that the role for ID is scientifically speaking
> minimal or nonexistent.

Terry M. Gray, Ph.D.
Computer Support Scientist
Chemistry Department
Colorado State University
Fort Collins, CO 80523
(o) 970-491-7003 (f) 970-491-1801
Received on Sun Oct 30 19:01:20 2005

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