Re: Mutationism Redux

On Jan 17, 1:34 pm, Bill Morse <wdNOSPAmo...@xxxxxxxxxxxxxxxx> wrote:
Discontinuity: As has been oft noted, the extent of discontinuity depends
heavily on scale. At the lowest scales, change is clearly discontinuous,
simply because of the way genetics works. I think it also true that much of
observed variation is incremental, and remember that both Darwin and Mayr
had encyclopedic knowledge of biology. So if they both espoused theories
that were based on incremental change, I will be slow to accept a theory
that argues otherwise.

Bill, I scarcely know how to respond to such an authoritarian
argument, other than to repeat that my characterization of the status
of infinitesimalism is based on a contemporary scientific analysis
that I cited. The infinitesimalist argument (specifically the
empirical side of the argument) has two parts: 1) show that
differences between closely related species are composed entirely of
infinitesimal changes and 2) extrapolate from this to all evolved
differences. The problem is that *the facts never allowed the first
step*. Orr and Coyne, 1992, systematically review the results of
quantitative analyses on this very question, and they write "We
conclude-- unexpectedly-- that there is little evidence for the neo-
Darwinian view: its theoretical foundations and the experimental
evidence supporting it are weak, and there is no doubt that mutations
of large effect are sometimes important in evolution." Furthermore,
they conclude that the MS architects *given the evidence available to
them at the time* were not justified in their conclusions either.

A scientist simply does *not* have the choice to ignore this kind of
hard quantitative empirical evidence in favor of generalizations from
dead authorities. Darwin's knowledge may have been "encyclopedic"
150 years ago, but it was neither quantitative nor even systematic by
modern standards. As Lord Kelvin said in a statement often quoted by
scientists (at least by the ones who value rigor) "When you can
measure what you are speaking about, you know something about it; when
you cannot measure it ... your knowledge is of a meager and
unsatisfactory kind".

Creativity: I really don't want to touch this one. Sorry, Arlin, but the
language is too easily confused with creationism. And I don't think
mutation etc. is creative in any useful meaning of the word. The whole
point of evolution by natural causes is that no creativity is required.

First, I did not invent this issue of creativity-- its been part of
evolutionary discourse for 150 years. The notion that "natural
selection" is "creative" is a well established doctrine that is
referred to *explicitly* again and again in writings of the MS, as
documented by Gould in Ch. 4 of "Ever Since Darwin" (1977) and in his
giant 2002 book. Here is what Gould says (p. 44 of Ever Since Darwin,
1977)

"But why was natural selection compared to a composer by Dobzhansky;
to a poet by Simpson; to a sculptor by Mayr; and to, of all people,
Mr. Shakespeare by Julian Huxley? I won't defend the choice of
metaphors, but I will uphold the intent, namely, to illustrate the
essence of Darwinism-- the creativity of natural selection. Natural
selection has a place in all anti-Darwinian theories that I know. It
is cast in a negative role as an executioner, a headsman for the unfit
(while the fit arise by such non-Darwinian mechanisms as the
inheritance of acquired characters or direct induction of favorable
variation by the environment). The essence of Darwinism lies in its
claim that natural selection creates the fit. Variation is ubiquitous
and random in direction. It supplies the raw material only. Natural
selection directs the course of evolutionary change. It preserves
favorable variants and builds fitness gradually. In fact, since
artists fashion their creations from the raw material of notes, words,
and stone, the metaphors do not strike me as inappropriate."

Second, we could all agree to stop using the word "creativity" for
superficial reasons, but we cannot choose to ignore the issue of how
to account for the origin of novelty, which remains an issue of great
interest to evolutionary biologists (e.g, type "origin of novelty"
into PubMed). So, saying that "no creativity is required" is a
rhetorical gesture that solves nothing.

Directionality: I should discuss this using the math, but even though it was
kept at a simple level I don't do it enough to completely understand it.

The maths are there for the sake of rigor (to prove to skeptics that
there is a population-genetic basis for the effect), but they are not
needed to understand the intuitive concept of "first come, first
served".

Arlin

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Relevant Pages

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