<<I've been amazed over the past few years when I've heard people prophecy
about the immenent demise of evolutionary theory as a credible scientific
theory. My own assessment is that evolutionary theory is alive and well
and in better shape than ever. How we can possibly come to such different
viewpoints is one of those mysteries of human intercourse..
I was prompted to post this message after having read the editorial in the
25 September 1998 issue of Science (p. 1959).
(snip)
It's called "A Revolution in Evolution" by Jim Bull and Holly Winchman. It
starts out
"Evolutionary biology has emerged from its 19th-century state; the
image of naturalists collecting butterflies and museum curators
dusting fossils has faded. Evolution is now widely perceived and
appreciated as the organizing principle at all levels of life. This
principle so pervades research that the evolutionary underpinning
of many experimental approaches is unstated."
It also contains the honest line:
"Notwithstanding this recent metamorphosis, many mysteries in the field
remain to challenge us. Complex evolutionary phenomena are difficult to
explain from well-understood elemental mechanisms, just as the weather
proves difficult to predict despite advances in basic physics."
>>
Terry,
I agree with you that evolution is alive today. Whether it is well and "and
in better shape than ever" is another question. You failed to mention that
Bull and Winchman specifically assert that a "fundamental challenge is to
understand the extent to which the mechanisms that account for microevolution
can explain the elaboration of forms in macroevolution" (p. 1959). Until this
fundamental challenge is satisfactorily resolved to everyone's satisfaction, I
do not think the theory of evolution can be considered well. This is not to
mention the intractable problem of the origin of life itself. Another
fundamental challenge.
The editorial of Bull and Winchman is an introduction to the special section
on the "Evolution of Sex". If the introductory review article to the section
by Bernice Wuethrich ("Why sex? Putting Theory to the Test" pp. 1980-1982)
is a correct assessment of the state of research in the field, it is
reasonable to conclude that the problem of the evolutionary theory of sex
remains fundamentally unresolved.
All the articles, including Wuethrich's, assume the that sexual reproduction
is already present. The problem then is how sexual reproduction is
_maintained_. That is the how the problem of "Why sex?" is defined in all the
articles.
But that's not the critical problem IMHO. The prior and more weighty problem
is how did sexual reproduction _originate_ in the first place? This is the
funadmental problem.
By almost every measure, asexual reproduction is superior to sexual
reproduction in the short run. It can out-perform sexual reproduction hands
down. It is more genetically faithful and energy efficient. So who needs
sexual reproduction? Since evolution cannot foresee the distant future, in
which sexual reproduction proves to be superior, how did sexual reproduction
ever get started?
Who addresses this problem? No one, to my knowledge. No one has
conceptualized the biological and biochemical steps that must have been taken
to go beyond asexual reproduction to originate sexual reproduction.
Thus in all honesty, Bull and Winchman should add "How did sexual reproduction
originate?" and "How did life originate?" to the fundamental unresolved
challenges of evolution, as well to the one they did identify: "How did major
morphological innovations arise in the metazoa?"
These and other problems of origins are seen by some people as the rocks on
which the theory of evolution will eventually founder. It is because of them
that they predict the eventual demise of Darwinian evolutionary theory, and
are searching for alternate explanations.
Thanks, Terry, for bringing B & W's editorial to our attention.
Respectfully,
Bob