Genes and Development Conference

Arthur V. Chadwick (
Fri, 26 Mar 1999 11:31:42 -0800

The following is an excerpt from a posting on another listserve. The
subject matter is of interest because of the growing recognition among
molecular biologists that evolution is being unmasked by their research,
particularly in the area of development.

On March 19 and 20, the Institut fuer Ethik und Geschichte der Medizin held
a conference on "Genes and Development" in Basel, Switzerland. It was an
international gathering of over 50 scholars critical of (and seeking
alternatives to) genetic reductionism in biology and medicine. Here is a
brief report of relevant parts of the meeting.

The first speaker was German molecular biologist Markus Althofer, who gave
a general overview of developmental genetics, mostly from Drosophila work
-- i.e., the evidence commonly cited by proponents of genetic programs.

Next, German developmental biologist Gerd Mueller pointed out that the
patterns of gene expression described by Althofer were not equivalent to a
causal story for form-generation. Specifically, Mueller listed six
problems which cannot be solved by a genetic-program approach: (1) the
Cambrian explosion (which he called "the Burgess shale effect"), (2)
homoplasy (similar morphologies in different lineages), (3) homology
("stasis of body plans"), (4) constraint (which prevents "phenotypic space"
from being "filled"), (5) punctuation (inequality of rates of evolution),
and (6) innovation (emergence of evolutionary novelties). Mueller argued
that these could not be reduced to genetic explanations because (a) there
is an incongruity between morphological and genetic evolution, (b) similar
genotypes yield different phenotypes, and (c) different developmental
pathways yield similar phenotypes. He listed the actual form-generating
processes as (i) differential cell adhesion plus diffusion gradients, (ii)
sedimentation gradients, (iii) chemical oscillations, and (iv) directional
growth, which he claimed could account for major differences in body plans.

Mueller was followed by Australian philosopher Paul Griffiths. Griffiths's
title was cumbersome, but intriguing: "The Fearless Vampire Conservator:
Phillip Kitcher on Genetic Determinism." Griffiths began by pointing out
that biologists have known for decades that development depends on both
genetic and non-genetic factors -- the "interactionist consensus."
Officially, genetic determinism is dead, but like a vampire it keeps rising
from the dead. Accordingly, some people (like Griffiths) have proposed a
stake-in-the-heart approach, to kill it forever; but others (like Kitcher)
think that approach is too radical, and argue that biologists are merely
being careless in mis-applying a generally correct view. Griffiths went on
to describe two concepts of information: (1) causal and context-dependent
(e.g., DNA makes RNA makes protein, under the influence of various cellular
factors), and (2) intentional and language-like (i.e., instructive and
programmatic). Confusion between these two is common, even among
scientists, and leads to the mistaken public perception that genes are
determinative of phenotypes. In the question-and-answer session, British
developmental biologist Brian Goodwin suggested that Griffiths's critique
would be "anathema" to Darwinists.

German biologist Eva Neumann-Held spoke next, and began by joking about the
confessions of faith in Darwinism that seem to be expected of speakers at
scientific conferences; she observed that anyone who tries to introduce new
ideas into biology risks being marginalized. Neumann-Held pointed out that
even polypeptide synthesis involves far more than DNA; because of
alternative RNA splicing and differential RNA editing, the outcome is not
uniquely determined by DNA sequences. She proposed a "developmental gene
concept" to embrace all the processes involved in producing a given
phenotype. The only sense in which DNA is really "causal" is that it can
account for some differences. One participant commented that biologists
already know this (i.e., that a naked DNA sequence is relatively
uninformative). In response, Neumann-Held asked why biologists don't say
this; the participant answered that saying so would reduce their chances of
getting money.

Next, British developmental biologist Brian Goodwin pointed out that
organisms are the causes and effects of themselves, not the effects of
genes. He attributed the popular notion of organisms to Darwin -- i.e.,
historically contingent collections of characters which promote survival
and are encoded by genes. Since biology has had such an impact on the
world, it's necessary to re-conceptualize it. After showing some pictures
of marine molluscs whose intricate shell patterns are clearly non-adaptive
because they're covered by an opaque membrane. According to Goodwin, the
patterns can be explained mathematically, though this does not amount to a
causal explanation; they have no known function, but they're beautiful.
Goodwin proposed that science should move from the quantitative to the
qualitative, and become a "science of qualities" which takes into account
senses and feelings. Instead of emphasizing control over the environment,
science should emphasize appreciation of it. Paul Griffiths countered
that, according to American embryologist Scott Gilbert, developmental
biology used to be a science of qualities, and only now is becoming a
science of quantities.

That evening, historian of science Evelyn Fox Keller (M.I.T.) gave a public
lecture on "Deconstructing the Genetic Program." She began by asserting
that the critique of genetic programs has come to the fore in recent years
for 3 reasons: (1) a recognition that the "gene" -- defined as the unit of
stability across generations -- is no such thing, because replication is so
unfaithful, requiring much in the way of proofreading and editing; (2)
knowledge of alternative RNA splicing and editing; and (3) the revelation
by molecular biology of the unexpected complexity of development. Keller
maintained that the "paradigm body," the "minimal representation of the
organism," is the zygote, or fertilized egg. She affirmed the value of
program-thinking, but insisted that we should move from genetic programs to
developmental programs. Although the public almost universally assumes
that the developmental program is written into the sequence of nucleotide
bases in DNA, it is actually distributed throughout the zygote. The
information content of DNA is significant, but it would be more accurate to
regard it as "data" used by the developmental program, rather than the
program itself (just as a computer tape provides data for a computer). She
quoted Lewontin's term, "vulgar biology," to refer to the idea that only
genes are passed from parent to child, maintaining that "we have always
known" that more than genes are transmitted.

The following day, Swiss molecular biologist Jackie Leach Scully lectured
about the recent upsurge in genetic thinking in biology, medicine and
ethics. She maintained that the real ethical issues enter "far upstream"
of where most ethicists intervene -- i.e., the ethical issues are more
fundamental than whether a person's DNA sequences should be made available
to insurance companies. She decried the increasingly "medicalization" of
health, and the increasing "geneticization" of medicine. Is someone with
an "abnormal" gene necessarily "ill"? When Evelyn Fox Keller asked her
during the question-and-answer session why, in her opinion, genetic
thinking has become so dominant in recent decades, Scully replied that it
was due, in part, to the failure of the liberal social engineering agenda
following WWII, with the result that genetic determinism seems more
plausible. She also maintained that "genetic immortality" has in some
respects replaced religious believe in an afterlife.

At one point over lunch a participant told me about an interesting
experience she had had a few months earlier at a conference in Germany.
There she had made some remarks mildly critical of Darwinian evolution;
afterwards American embryologist and textbook-writer Scott Gilbert had come
up to her and, by way of friendly advice, told her that she would be wise
to omit such criticisms if she ever found herself speaking to an American
audience, because they would write her off as a creationist. The
participant laughed as she told me this; obviously, she was more amused
than intimidated.

Two things struck me about this meeting: (1) the popular impression that
development depends on genetic programs is coming under increasingly heavy
fire from biologists and philosophers; and (2) genetic reductionism and
Darwinian evolution are more openly criticized in Europe than in the U.S.
(where it is risky to question the reigning orthodoxy).

Jonathan Wells
Department of Molecular & Cell Biology
University of California, Berkeley
Senior Fellow
Discovery Institute, Seattle