[Marxism] evolution, species concepts, final words
mikedf at mail.amnh.org
Wed Dec 29 20:53:08 MST 2004
At 09:33 PM 12/29/2004, you wrote:
>ape/monkey. Further, I am not a bible believer. But, noting the hard
>dogmatism which runs through this discussion, I will reveal my skepticism
>about Darwinism by asking if this theory (called a 'fact') can explain the
>gradual development of insect metamorphosis, a very common life
>phenomenon? Note that the 'Origin of Species', all of which I have read,
>makes numerous references to the necessity for frequent small modifications
Actually, yes, and the mechanism through which insects with complete
metamorphosis (holometabolous) evolved from those with incomplete
metamorphosis (hemimetabolous) is fairly well understood. It has to do with
a favorite mechanism of Gould's, the switching on and off of genes. In this
case we have homeobox genes, which regulate integral development in body
segments. Slight alterations in timing of expression of these genes during
embryonic development can cause dramatic changes in all stages of an
As for Charles' point on my last post:
>Also, couldn't someone just
>respond that the snakes are classified wrong previously , and your
>experiments have demonstrated that they are members of the same species ?
They could, of course. But then you have the same problem with EVERY
taxonomic category, which gets back to my final point in criticizing the
BSC -- in practice it is unknowable if different species have isolating
mechanisms. However, these are long recognized separate genera. And then
there are the plants.
The species concept debate can go on and on and on, believe me, and these
are my final words on the subject, EXCEPT over a dinner or a beer.
As for dialectics and evolution: "punk-eke" is no more "dialectical" than
gradualism. The truth of dialectics is concrete, how closely dialectical
laws reflect reality. Both mechanisms are accepted as applicable in
different circumstances. They are not mutually exclusive explanations for
evolutionary change. Both can involve natural selection. Or genetic drift.
Or some other mechanism. Nor (Mark) was Mayr's application of population
genetics necessarily "dialectical" -- on the contrary, imho, it is somewhat
reductionist to reduce evolution to a change in gene frequencies. It did
provide a concrete mechanism that could be studied, which became crucial in
our Popperian scientific world (Popper considered evolution to be
non-scientific, because he felt it was non-falsifiable).
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