Re: 1980 Eldredge: "time to reexamine" theory of NS

david ford <[EMAIL PROTECTED]> wrote in message news:<[EMAIL PROTECTED]>...
> On Tue, 2 Dec 2003, Alan Hobson wrote:
> david ford:
> 
> > > Eldredge, Niles.  July 1980.  "An Extravagance of Species"
> > > _Natural History_, 47-51.  Paragraphs from 48, 50, and 51:
> > >      Trilobites, including the ones from Bolivia that I studied,
> > >      pose some fundamentally important evolutionary puzzles,
> > >      puzzles whose solutions demand changes in evolutionary
> > >      theory.  It would be tempting to offer a scientific detective
> > >      story of my work, with patterns in the raw data suddenly
> > >      emerging to suggest a new theory.  But no scientist ever
> > >      accumulates facts blindly.  There are always new ideas
> > >      emerging that influence the way we look at new, and old,
> > >      facts.
> > >      ....
> > >      Such similarities [i.e. instances of convergence] offer some
> > >      insight into the evolutionary history of the Gondwana
> > >      trilobites.  But we are left to explain the most striking fact
> > >      about these fossils-- their diversity.  What does all this
> > >      variety suggest?  How and why did ancestral trilobites
> > >      evolve into so many kinds of descendants, so anatomically
> > >      varied?
> > >
> > >      Standard evolutionary theory focuses on anatomical change
> > >      through time by picturing natural selection as the agent that
> > >      preserves the best of the designs available for coping with
> > >      the environment.  This generation by generation process,
> > >      working on small amounts of variation, is thought to
> > >      change, slowly but inexorably, the genetic and anatomical
> > >      makeup of a population.
> > >
> > >      If this theory were correct, then I should have found
> > >      evidence of this smooth progression in the vast numbers of
> > >      Bolivian fossil trilobites I studied.  I should have found
> > >      species gradually changing through time, with smoothly
> > >      intermediate forms connecting descendant species to their
> > >      ancestors.
> > >
> > >      Instead I found most of the various kinds, including some
> > >      unique and advanced ones, present in the earliest-known
> > >      fossil beds.  Species persisted for long periods of time
> > >      without change.  When they were replaced by similar,
> > >      related (presumably descendant) species, I saw no gradual
> > >      change in the older species that would have allowed me to
> > >      predict the anatomical features of its younger relative.
> > >
> > >      The story of anatomical change through time that I read in
> > >      the Devonian trilobites of Gondwana is similar to the
> > >      picture emerging elsewhere in the fossil record:  long
> > >      periods of little or no change, followed by the appearance
> > >      of anatomically modified descendants, usually with no
> > >      smoothly intergradational forms in evidence.
> > >
> > >      If the evidence conflicts with theoretical predictions,
> > >      something must be wrong with the theory.  But for years
> > >      the apparent lack of progressive change within fossil
> > >      species has been ignored or else the evidence-- not the
> > >      theory-- has been attacked.  Attempts to salvage
> > >      evolutionary theory have been made by claiming that the
> > >      pattern of stepwise change usually seen in fossils reflects a
> > >      poor, spotty fossil record.  Were the record sufficiently
> > >      complete, goes the claim, we would see the expected
> > >      pattern of gradational change.  But there are too many
> > >      examples of this pattern of stepwise change to ignore it any
> > >      longer.  It is time to reexamine evolutionary theory itself.
> > >
> > >      There is probably little wrong with the notion of natural
> > >      selection as a means of modifying the genetics of a species
> > >      through time, although it is difficult to put it to the test.
> > >      But the predicted gradual accumulation of change within
> > >      species is seldom (if ever) encountered in our practical
> > >      experience with the fossil record.
> > >      ....
> > >      The internal cohesion of a species predicts the sort of lack
> > >      of anatomical change during its history that we see so often
> > >      in the fossil record.  And speciation, the process of creating
> > >      a new, descendant reproductive community from an
> > >      ancestral one-- in a way other than that proposed by natural
> > >      selection-- must be a crucial step in the evolutionary
> > >      process.
> > >      ....
> > >      During such [speciation] events, behavioral, anatomical,
> > >      and genetic change (sometimes quite rapid) may occur.
> > >      Such change must occur if we are to be able to tell the
> > >      daughter species from the parent.  And the process of
> > >      natural selection must account for part of such change.  But
> > >      natural selection per se does not work to create new
> > >      species.  The pattern of change in so many examples in the
> > >      fossil record is far more a reflection of the origin and
> > >      differential survival (selective extinction) of species than
> > >      the inexorable accumulation of minute changes within
> > >      species through the agency of natural selection.
> > >
> > > compare "internal cohesion of a species" with
> > > 1970 Mayr on organisms' observed resistance to change
> > > http://www.google.com/groups?selm=Pine.SGI.4.44L.01.0309181335410.2863259-100000%40irix2.gl.umbc.edu
> >
> > Sounds like evidence for punctuated equilibrium to me.  This is not
> > evidence against evolution.
> 
> If "evolution" equals "blindwatchmaking via the neo-Darwinian mechanism of
> blindwatchmaking," then Eldredge's expert remarks, as well as similar
> remarks by paleontologists Gould and Eldredge in the peer-reviewed
> scientific literature, constitute evidence against "evolution."
> 
> Since the proposed Darwinian mechanism of blindwatchmaking has had so many
> problems dealing with reality ever since it was proposed, some
> materialists have distinguished
> a) the "fact" that biology came about through blindwatchmaking
> from
> b) the "theory" that the Darwinian mechanism was _how_ biology developed
> through the years.
> 
> Other materialists (e.g. Dawkins) have equated "evolution" with
> "blindwatchmaking via the neo-Darwinian mechanism of blindwatchmaking."
> This is a quite natural thing to do, since it would be difficult to
> rationally conclude that biology was the product of blindwatchmaking
> processes without having a plausible blindwatchmaking mechanism said to be
> responsible for _how_ biology in all its glorious complexity and
> curiosities arose and developed.
> 
> Simpson and Dobzhansky on the need for a mechanism
> http://www.google.com/groups?selm=8beptq%24hgk%241%40nnrp1.deja.com
> 
> > I see you're inching toward modern evolutionary theory.  You've made
> > it to 1980.  Of course, nothing has happened in evolutionary theory in
> > that last 23 years. ;)
> 
> I take it that you have not seen my recent look at the years since 1973:
> http://www.google.com/groups?selm=Pine.LNX.4.44L.01.0311291245550.28927-100000%40linux3.gl.umbc.edu
> 
> I'll also mention
> Essay on Problems with Darwin's Theory of Natural Selection
> http://groups.google.com/groups?selm=Pine.LNX.4.10A.B3.10005310900310.17702-100000%40jabba.gl.umbc.edu
> 
> > -Alan
> > aa#1608 BAAWA


I love how you keep using the term "Neo-Darwinian"... it makes as much
sense as saying "Neo-Capitalist" or "Neo-American"...