RE: [Marxism] Re: human origins

["David McDonald" <dbmcdonald@xxxxxxxxxxx>]

It is not true, as John Enyang writes, that "new species, by definition, can
only arise
> from "significant change" in a population of an existing species, for
> otherwise the terms themselves are rendered meaningless."

This is not about definitions, but about the most significant challenge to
Darwinism since it became the generally accepted theory of evolution. New
species can arise, for instance, when some portion of a species  is cut off
from the main population for whatever reason.

The CORE of Darwin's argument for natural selection as the main driving
force in evolition is that natural selection proceeds by a unending series
of small changes in individual organisms, each specific change conferring a
selective advantage for that organism and leading to its differential
reproductive success and thus eventually the "fixing" of the particular
change in the population. This explanation works well for some things, like
the evolution of vision, where even the smallest evolutionary change
allowing an organism to respond to contrast confers an enormous advantage.
The problem comes about when it is realized that evidence for a chain of
small changes, each conferring a selective advantage, is exceedingly rare in
nature. (Darwin himself, an exceedingly honest scientist, acknowledged this
difficulty with his theory). Hence Gould's hypothesis of punctuated
equilibrium, which at the very least describes the data.

This is the esssence of his fight with Richard Dawkins. For, if some other
process it as work beyond the gradual accumulation of changes that reach a
qualitative point, as it must be for punctuated equilibrium to be accurate,
that process must be identified and the theory of evolution must be adapted
to encompass it. So far, Gould and people who agree with him have described,
but not explained the higher order mechanism they assert is happening
("higher order" meaning not spiritual, but evolution operating on a level
other than that of the individual organism). If evolution proceeds by a
gradual accumulation of individually small changes, for instance, why would
there be the observable "rigor" or "liveliness" of evolutionary change in
the beginning of the historical run of a genus or family, which suddenly
peters out into "equilibrium?"  Dawkins asserts flatly that Gould's approach
abandons Darwin, while Gould's "Structure of Evolutionary Theory" is a very,
very extended argument that his insight into punctuated equilibrium
preserves the "core" of Darwinism while adapting the theory overall to fit
the observed facts.

It appears to me that things are at approximately the point that the
discussion of continental drift had reached when I was in college.
Continental drift was, at that time, considered a quaint theory based on
observations about the way the continents would seem to "fit together" if
smushed and on otherwise unexplained continuities of animal and plant
distribution in far-flung parts of the world. It was dismissed because no
evidence existed for any mechanism that could push the continents around.
Then along came plate tectonics and suddenly continental drift became a
satisfactory explanation for the facts. It is not at all unusual for facts
to precede adequate theorizing. One of the amazing things about Darwin's
work is that he got so far without the slightest hint at what caused
variation, which was not understood until almost one hundred years after the
publication of The Origin of Species.




> -----Original Message-----
> From: marxism-bounces@xxxxxxxxxxxxxxxxxxx
> [mailto:marxism-bounces@xxxxxxxxxxxxxxxxxxx]On Behalf Of John Enyang
> Sent: Tuesday, August 09, 2005 7:29 PM
> To: marxism@xxxxxxxxxxxxxxxxxxx
> Subject: Re: [Marxism] Re: human origins
>
>
> Carrol Cox writes:
> >
> > Repeat: Most species, very nearly all of multi-cellular species, remain
> > biologically stable, with no significant change, during their whole
> > existence. See the passages in Gould's work that argue "absence is
> > data."
> > Carrol
> >
> While I agree with the general thrust of Carrol's argument, the statement
> above is close to tautological: new species, by definition, can only arise
> from "significant change" in a population of an existing species, for
> otherwise the terms themselves are rendered meaningless.
>
> Is the way around this to say that populations of species generally remain
> biologically stable over time, change being punctuated?
> je
>
>
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