File spoon-archives/marxism2.archive/marxism2_1996/96-04-30.191, message 113


Date: Wed, 24 Apr 1996 20:44:06 -0500
From: rahul-AT-peaches.ph.utexas.edu (Rahul Mahajan)
Subject: Punctuated equilibria


Lisa, I agree with your and Dawkins's view that the theory of punctuated
equilibria is well within the pre-existing framework of understanding.
Gould himself has always said that he is talking about ordinary speciation
by natural selection, although he has perhaps overplayed the significance
of the idea. What seems new to me is not the idea that rates of change can
vary greatly, which anyone without an a priori prejudice could see
immediately, but rather that our picture that gradual change within species
occurs over millions of years (in addition to whatever more rapid
change/speciation may occur) is either wrong or much less universal than we
supposed. In effect, they posit a stability of species to small
deformations and present a picture of long periods of almost complete
genetic stasis (in the adaptive sense, of course; nonadaptive genetic drift
continues at a near-constant rate). This, if true, is interesting, but I
have seen little that directly addresses this question, perhaps because
it's difficult to address experimentally. What would be especially
interesting would be to look at the persistence and prevalence of stasis
broken down by complexity of organism. We already know that the more
complex an organism is, the less potential for radical change it has (viz.
the evidence of the Burgess Shale and other post-Cambrian Explosion sites).
This would add another piece to that picture.

Rahul




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