Several questions on evolution, and mutation (rate)

Doug Yanega dyanega at denr1.igis.uiuc.edu
Sat Aug 31 15:16:27 EST 1996


In article <96Aug31.150143edt.1020 at neuron.ai.toronto.edu>,
radford at cs.toronto.edu (Radford Neal) wrote:

> In article <dyanega-3008962128250001 at catalpa.inhs.uiuc.edu>,
> Doug Yanega <dyanega at denr1.igis.uiuc.edu> wrote:
> 
> > Evolution is defined as a change in the frequencies of alleles (different
> > forms of the same genes) present in a population from generation to
> > generation.
> 
> There's a slight historical problem with this definition:  Darwin's
> theory of evolution was formulated without knowledge of genetics,
> including the concept of "allele".  Now, formal definitions can change
> over time, to take advantage of the precision allowed by new
> discoveries, but this one misses the point in any case.  It certainly
> is not an appropriate definition to use when debating fundamental
> questions, such as, for instance, whether evolution is the result of
> natural selection, or might instead be Lamarkian in nature.

AU contraire. It is the most appropriate definition, as it is the genetic
level at which evolution operates; if a trait has no heritable component
(i.e., genetic), it cannot be involved in evolution. Whether evolution
occurs via natural selection, drift, mutation, or migration, the change is
at the genetic level. Whether Darwin was aware of this or not is
irrelevant. It's time to stop criticizing models from the 1700's, and
appreciate our *present* understanding of evolution. It's like people
trying to challenge physics by criticizing Newton - we've come farther
along now, and we know better.

> > That's it. I would wager 10 years' salary that this is not at all what
> > Dave THOUGHT the definition of evolution was...  Dave is trying to make 
> > "evolution" synonymous with "speciation" and it never was and never will 
> > be.
> 
> This is a fatuous argument.  The primary purpose of the theory of
> evolution is to explain the diversity and similarity of form between
> different species.  If evolution were in fact incapable of explaining
> speciation, being instead confined to explaining variation within a
> species, it would be of only minor interest, rather than being the
> central organizing principle of biology that it is.

A species does not have to speciate in order to evolve, but it does have
to evolve in order to speciate. Does that make things clearer? The
"theory" is that biological systems change over time; that this leads to
diversity and similarity of form is a logical consequence. The first of
these points is a fact of nature and indisputable; the second may be more
disputable, but only in the sense that it is harder to obtain direct
evidence. It is certainly the most logical explanation for all the facts,
and thus at that level also virtually as much a fact as the Law of
Gravitation.

Doug Yanega     (dyanega at mail.inhs.uiuc.edu)
Illinois Natural History Survey, 607 E. Peabody Dr. 
Champaign, IL 61820  USA  (217) 244-6817 fax:(217) 333-4949
affiliate, University of Illinois Dept. of Entomology
  http://www.inhs.uiuc.edu:80/~dyanega/my_home.html
"There are some enterprises in which a careful disorderliness is
    the true method" - Herman Melville, Moby Dick



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