Most interesting quote:
"Steve Jones regards this [The Blind Watchmaker --BH] as
'the best general book about evolution since the second
world war'."
Steve, has he quoted you correctly? ;-)
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published in <The THES> May 19 1995
<THES = Times Higher Education Supplement>
downloaded from:
http://thesis.newsint.co.uk/SPECIAL/goodwin.html
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Neo-Darwinism has failed as
an evolutionary theory
Brian Goodwin
Professor of Biology
the Open University
Darwinism is a theory of evolution based upon inherited
variations in organisms and natural selection of fitter
variants to produce species adapted to their habitats.
Twentieth-century biology added a theory of inheritance, the
science of genetics, to give Neo-Darwinism. In the past 20
years the techniques of genetics and molecular biology have
converged to provide both a remarkably detailed understanding
of the genes that define the molecular composition of any
organism and the ability to transfer genes from one species
to another.
There is no doubt about the importance of the insights that
have resulted from this increased genetic and molecular focus.
The problem is that the claims made for these revelations are
frequently so misleading and distorted that the whole field
becomes tarnished by exaggeration and real scientific problems
are obscured. Biology then suffers. A widely quoted example with
which many biologists agree is the description by Delisi
(American Scientist) of what the human genome project will reveal
about human development. "This collection of chromosomes in the
fertilised egg constitutes the complete set of instructions for
development, determining the timing and details of the formation
of the heart, the central nervous system, the immune system, and
every other organ and tissue required for life."
A colleague in the States who is a firm believer in the importance
of genes in development and evolution says he uses the Delisi
quotation in his developmental biology class to show the
stupidity of the reductionist paradigm. So biology is a broad
church that contains many points of view. But the most prominent
public voices present the reductionist position. Richard Dawkins,
a fervent adherent of extreme genetic reductionism, describes in
The Blind Watchmaker a willow tree releasing seeds within which
is the "DNA whose coded characters spell out specific instructions
for building willow trees". For him the genes define the essence
of life and the organism is just a survival machine built by
genes for their own perpetuation. Steve Jones regards this as
"the best general book about evolution since the second world
war". And Lewis Wolpert delivers the same message as Dawkins:
"DNA provides the programme which controls development of the
embryo and brings about epigenesis" (The Triumph of the Embryo ).
What is wrong with these statements is that they define scientific
positions that need to be backed up by models that demonstrate
precisely how a knowledge of genes in the developing organism
will lead to an understanding of the three-dimensional form of the
human heart or limb or eye, the arrangement of leaves on a plant
and the organs of the flower, or the wings of a fruit fly. But
this is not provided. The discussion always stops at the spatial
patterns of gene products in developing organisms, if indeed it gets
even that far. The crucial step of generating the actual three-
dimensional structures that characterise the distinctive
morphology of species is left unexplained.
To understand why organisms look the way they do we need models that
involve physical forces as well as biological variables, organised
to produce organisms with specific morphologies, as described in
my book, How the Leopard Changed its Spots . To say there is a
program in DNA that constructs the organism is to use a misleading
shorthand or to fail to understand the problem. It is like saying
that all you need to know to understand high-temperature
superconductors is what they are made of and where the atoms are
relative to one another. Try that on a physicist. And organisms
are at least as complex as superconductors. Yet we are constantly
being told that molecular analysis will reveal all. The rhetoric here
frequently overwhelms the science, which is doubly unfortunate:
the science is sufficiently exciting in its own right and does not
need the hyperbole, while the problems it cannot address are
being neglected.
Nowhere is this more evident than in the claim that Neo-Darwinism
explains evolution. Evolution is about the origin of species,
the emergence of new types of organism characterised by distinctive
morphologies and behaviours. This requires a theory of organisms
as life-cycles, including morphogenesis (how organisms of specific
form are generated) and of their interactions with one another and
the physical environment in producing communities and ecosystems.
But far from concentrating on the development of theories of
organisms and ecosystems, Neo-Darwinism concentrates on genes
as the fundamental entities in biology.
This cannot succeed because it leaves out too much. Organisms are
large-scale physical systems that grow and develop, run, fly,
produce leaves and flowers, and generate patterns of relationships
with each other. Some of them even love and write poetry. Genes
do none of these things, and neither do molecules.
Neo-Darwinism has failed as an evolutionary theory that can explain
the origin of species, understood as organisms of distinctive form
and behaviour. In other words, it is not an adequate theory of
evolution. What it does provide is a partial theory of adaptation,
or microevolution (small-scale adaptive changes in organisms). It is
partial in two senses. First, Neo-Darwinism assumes random genetic
variation followed by selection, whereas there is now evidence for
a role of directed mutation in adaptive response. That is, genes
can evidently respond to environmental circumstances by non-random,
adaptive mutation. And second, many of the adaptive "explanations"
advanced for biological characteristics simply cannot be taken as
serious science. In 1979, Steven Jay Gould and Richard Lewontin
published a classic paper that ridiculed much of the adaptationist
literature as constituting a "panglossian paradigm", Just So
Stories of such dubious scientific value that they discredit the
subject. For a few years after that, adaptationists watched their
p's and q's more closely. However, the salutary influence of that
paper has unfortunately diminished to the point where Just So
Stories are again proliferating wildly. A recent example is why
the hour-glass shape in women is an adaptive trait, determined by
genes. Men select women with large hips and breasts because these
are indicators of reproductive potential, or at least men think
they are. Women who satisfy these criteria but do not have a
small waist are simply fat, which, we are told, is not a good
indicator of reproductive potential. Hence the selection of the
hour-glass shape. You might think I overheard this in a pub, but it
is in fact advanced as a serious proposition by Matt Ridley in
The Red Queen following the original proposal by Low, Alexander,
and Noonan in Ethology and Sociobiology. If this is science then
Rudyard Kipling was a great scientist.
Adaptation is an important problem, but it is not the same as
evolution. Still less is it the same as macroevolution, which is
about large-scale evolutionary change: the emergence of algae,
mosses, ferns, grasses, flowers, trees; of protozoa, sea urchins,
octopus, fish, amphibia, birds, mammals. For these qualitative
changes, the stuff of evolution, there is no adequate theory. A
primary reason for this absence is the narrative style that has
been adopted within biology since Darwin's re-description of the
subject as an historical science. Species have come to be seen
as individuals, the results of historical contingencies, so that
the morphological relationships between species have become
unintelligible because they are accidental, not necessary. And yet
there is plenty of evidence for a deep level of structural order
that underlies the taxonomic regularity of the biological realm,
the systematic similarities and differences of species. This is
the level of structural constraint that Gould and Lewontin were
reminding us of: biological form cannot be explained away in
functional (adaptational) terms, nor is any form possible. There
is a long tradition in biology of seeking to understand this
intrinsic order in terms of a theory of biological form and
transformation that is now re-emerging from more sophisticated
non-linear dynamic modelling of morphogenesis and a deeper
understanding of the causal mechanisms involved.
It is clear biology needs a theory of organisms as self-organising
systems that generate emergent order if evolution is to be
understood. This is now a very real and exciting possibility, but
it is an interdisciplinary task that requires mathematical,
physical, and biological input. It simply cannot come from the study
of genes and molecules alone, useful as this is.
There is another dimension of Neo-Darwinism that is also problematic.
The analytical power of molecular genetics has resulted in a new
expansion of Neo-Darwinism with a strongly applied, technological
dimension. One manifestation of this is the project to identify
every human gene, coordinated by the international Human Genome
Organisation (HUGO), with associated squabbling over patent rights
on potentially lucrative applications in the fields of medicine
and designer gene engineering. The French geneticist Daniel Cohen
has led the movement to have this information recognised by the
United Nations as the property of humanity to use freely for any
appropriate purpose. But 17 companies are now in a position to
patent many of the 100,000 genes of the human body so that,
unless patent rights are paid for use, they can withhold the
information that would otherwise be valuable for medical research.
There are immense social and ethical issues involved. It is obvious
extreme caution is required because of our ignorance of the
genetic, biological, and ecological consequences of gene
manipulation. Any applications should be governed by principles
such as no use of the technology unless there is a clearly
demonstrated need, extensive testing of safety before any application,
and establishment of rigorous safety protocols on international
movements of transgenics and their use in the field. There is a
call for a moratorium on the large-scale release of genetically
engineered organisms into the environment until such safety protocols
have been put in place. Without this, we shall find that Neo-Darwinism
is not only prone to misleading rhetoric and inadequate science,
but its applications may result in ecologically dangerous agricultural
applications.
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Brian Harper |
Associate Professor | "It is not certain that all is uncertain,
Applied Mechanics | to the glory of skepticism" -- Pascal
Ohio State University |
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