[Marxism] human origins
cbrown at michiganlegal.org
Fri Aug 12 09:34:31 MDT 2005
From: Paul Gallagher
>> Paul Gallagher
During the "equilibria", isn't what is being said that there are
changes, i.e. new characteristics arise, but these characteristics do not
amount to speciating changes ?
Paul: Yes, the changes that are occuring, it's thought, don't give rise to
new species,and they don't lead to substantial differentiation -- that's the
long period of stasis.
But that is consistent with the generalization that speciation and the
acquisition of new charactistics occur at the same time: most morphological
change in species occurs at the time of speciation. It's often thought,
consistent with Mayr's model
of allopatric speciation, that this occurs is small, peripheral
populations, isolated from the main body of the species.
CB: If I might take this a bit further, I understand what you are saying in
that more new traits and occur at speciation punctuations. There is both a
greater quantity _and_ the qualitative change of new species, i.e. certain
populations become internally, physiologically, gonadally incapable of
mating with and producing fertile offspring with populations , and the
ancestor populations of these two populations _could_ fertily mate and
produce fertile offspring.
I believe the Mayr theory is that two populations that are still gondally
capable of mating fertily are geographically ( "patrically" meaning country)
and thereby physically separated and unable to mate because of this physical
separation, not because of organic incompatibility. But that this
geographical separation eventually leads to physiological inability to mate
Seems to me that the big thing biology wants to find out is how is it that
populations lose the physiological ability to mate fertily with each other.
This is the big mystery of speciation. Mayr's theory is sort of , excuse the
expression, the "ground" that sets up the more fundamental reproductive
incomptability that is physiological.
I also wanted to throw out the thought that it is important to note that
though there are , empirically, fewer new traits arising in the equilibria
than in the punctuations, there _are_ new traits arising in equilibria, no ?
The equilibria are "dynamic stabilities". Some of these arise by selection
and some don't (following Gould's general approach). Some are spandrel-like,
some are genetic drift, some are not originated as adaptions, but are
adapted to being adaptions after they arise by non-adaptive causes ( snails
gets shells through adaptive processes; there is space under the shell as a
"spandrel"; then the spandrel is used to store eggs, which activity _is_
adaptive; so not-adaptive in origin , but adapted to being adaptive post
hoc; I don't know whether the shell arises in speciation/punctuation or in
an "equilibrium" phase)
But the main point I am making is that there are new traits that arise in
the non-speciating phases even if fewer and of non-qualitative type changes,
with qualitative change defined as speciating.
Also,no doubt, there is some speciation in "equilibria" and some non
speciating changes in "punctation" periods, empirically.
And what was going on with insects during the dinosaur's trials and
tribulations ,and the mammals triumphs , after the comet hit ?
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