Re: Pitt professor's theory of evolution gets boost from cell research

On Sat, 28 Jan 2006 17:20:36 -0500, in talk.origins , r norman
<NotMyRealEmail@xxxxxxxxxxxx> in
<8onnt19gftk88prt1plkqs6ebnk4do0017@xxxxxxx> wrote:

><snip all previous discussion of J. Schwartz's book "Sudden Origins">
>
>My impression is that the Hershey/Silberstein exchange is about the
>book not the new paper.

Actually, I based it on the review originally references. I just saw
you response and I am reading the paper itself now.

I haven't read the book and don't know
>whether it is filled with error or not, I will just concentrate on the
>paper
> B. Maresca and J. Schwartz,
> "Sudden Origins: A General Mechanism of Evolution Based on Stress
>Protein Concentration and Rapid Environmental Change"
> Anat. Rec. B (New Anat), 289B:38-46, 2006.
>The paper is available at
>
>http://www3.interscience.wiley.com/cgi-bin/fulltext/112349521/PDFSTART

Well, it starts out with what looks like a gross distortion of
standard evolution theory. From the first paragraph:

"Morgan provided Darwinism and the evolutionary synthesis with the
idea that minor mutations produce the minuscule morphological
variations on which natural selection then acts, and that,
although mutation is random, once a process of gradual genetic
modification begins, it becomes directional and leads
to morphological, and consequently organismal, transformation."

Huh? Did he just forget to say that if it is "directional" it is
selection that causes the direction?


>The basic idea is a mechanism by which environmental stress can cause
>a substantial increase in mutations.

The notion that the *rate* of uncorrected mutation can change is
already know.

> For a variety of reasons, this
>will lead to an apparent "sudden" origin of a new form. The details
>and explanation seem sound to me. Full analysis requires more
>knowledge of the mechanism of action of Heat Shock proteins and the
>dynamics of evolutionary change than I possess. I would be greatly
>interested to hear from people with expertise in these areas (Hershey?
>Harshman? plus many others in this group?) Please comment
>specifically about this paper, not about the earlier book. Note: the
>first author of the paper, Maresca, is a biochemist; Schwartz is a
>physical anthropologist. The previous work was Schwartz's alone.
>That might make all the difference.

As a non-H I can offer little. But here is a bit I find troubling:

"Nevertheless, intermediates between living pro- and eukaryotes do
not exist, variation within species reflects fluctuating frequencies
of existing features, and the fossil record does not document seamless
transformation of lineages." (page 2 of the pdf, pg 39 of the article)

Assuming they do not mean an intermediary between a prokaryote and a
eukaryote (which would be an irrelevant claim) they means that there
are no intermediaries in a eukaryote lineage. But that is just silly,
what does he think that variation he mentions is? And they, like so
many others, confuse a small number of fossil transitional sequences
with an absence of any such sequences.


[snip]

>There is an important new twist to this particular mechanism. The
>membrane state can adapt to relatively slow changes in the
>environment. As a result, organisms subjected to one environmental
>condition will respond to shock differently from organisms of the same
>genotype that have been exposed earlier to a different environment but
>are now exposed to the same shock. That is, the environment can
>condition one subset of a population to undergo rapid mutation while
>another subset of identical genotype will continue the repair
>mechanism and remain static in the face of the same new environmental
>challenge. In a sense, that allows for some Lamarckian aspect to the
>change. The presence of new forms, but not their direction, are
>influenced by experience.

Which is, in no sense, Lamarckian.

>Now we get to the "recessive" and "sudden origin" argument. There are
>two aspects to the "sudden origin". First, under normal circumstance,
>the repair mechanism produces stasis. It is only under high stress
>conditions that the mutational mechanism is invoked. Second, the
>mutations produced are likely to be recessive -- that is, deleterious
>in homozygous form but benign if heterozygous.

That is not what recessive means. Nor is the claim itself justified. I
suspect that you mean that dominant deleterious mutations are more
likely to be removed by selection. That, of course, is not
particularly a new thought.

[snip]


>Nevertheless, you do have a specific model for punctuated equilibrium
>-- long periods of evolutionary stasis followed by periods of rapid
>change. Incidentally, you do not need geographical isolation nor
>directional selection multiplying gene frequencies resulting from a
>series of small changes occurring serially.

Unfortunately Punk Eek does not suggest in any way that these sudden
changes occur across multiple species at the same time. If Maresca and
Schwartz are correct I would expect to see that.

Here is an interesting bit:

"Finally, there is no adaptive correlation between phenotypic novelty
and the environment in which organisms with the novelty live;
novelties persist if they do not interfere with their bearers?
viability or ability to reproduce." (page 7)

I have been trying to argue that many people miss that selection has
this dual nature. Those who are better at reproducing have more
descendents, those who are worse at reproducing/living has less. That
is, this is a continuum with selection acting all across from
positive, through neutral, to negative. Maresca and Schwartz, it
seems, want to just see it as the not killing of the acceptable. I
was also struck by the effort the authors seem to go to avoid using
the term "selection". They also keep talking about how adaption is not
evolution.

--
Matt Silberstein

Do something today about the Darfur Genocide

http://www.beawitness.org
http://www.darfurgenocide.org
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.

Relevant Pages

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  • Re: How can the evolutionary progress from slime to humans be linear?
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