Re: Cambrian explosion bit of an embarassment

On 11 Sep 2006 13:37:32 -0700, "UC" <uraniumcommittee@xxxxxxxxx>
wrote:


r norman wrote:
On 11 Sep 2006 10:00:31 -0700, "UC"
<uraniumcommitteechairman@xxxxxxxxx> wrote:


r norman wrote:
On 11 Sep 2006 08:47:04 -0700, "UC" <uraniumcommittee@xxxxxxxxx>
wrote:


topmind wrote:
You have to admit that the Cambrian Explosion is a bit of an
embarassment from an evidence standpoint. Out of a period of no more
than about 5-10 million years, these features "popped" out of nowhere
in the fossil record:

* Movable and jointed limbs
* Mouths
* Eyes
* Digestive tracks
* Body armor
* Nervious system

Parker argues that the development of vision drove most of the others.

I have several times pointed out a review of Parker's argument by a
noted specialist in that particular field that strongly criticizes the
argument, pointing out many flaws and fallacies in it.

There are many ideas and hypothesis put forward by otherwise sane and
capable biologists, citing evidence and producing logical arguments
that seem to be sound by those not familiar with the details of the
field, but are nonetheless rejected by those working in that area.
You can cite Parker as long as you want but you also have to answer
Parker's critics.

The fact is that whether or not the development of vision was a
critical factor in the production of the characters listed is quite
irrelevant to the fact that the Cambrian "explosion" took place of
tens of millions of years, possibly more, and that there exists a
fossil record predating the Cambrian so that there no longer is even
an impression of a "sudden explosion" of animal types to embarrass
anybody.

Have you read Parker's book?

We have been all through this one before with a different author,
different book.

I have read aspects of Parker's work in technical form
In particular, I have read the full text of

Colour in Burgess Shale animals and the effect of light
on evolution in the Cambrian
Proc RoylSoc B 265: 967 - 972 (1998)

515 million years of structural colour
J. Opt. A: 2: R15-R28 (2000)

The Diversity and Implications of Animal Structural Colour
J Exp Biol 201, 2343-2347 (1998)

Unfortunately, I do not have access to
The Cambrian light switch.
Biologist 46 (1), 26-30 (1999)

I also have read the one review in the scientific literature of
Parker's book that I can find, Simon Conway Morris' at

http://www.americanscientist.org/template/BookReviewTypeDetail/assetid/21926;jsessionid=baa65GQXFsT7Oa

I do not have on-line access to the review in
IEEE Spectrum 40(6):40-41(2003)
but this is not a journal of, by, and for biologists.

I did not find a review of the book in Nature or in Science.

Parker presents an interesting hypothesis on the evolution of Cambrian
animals but, in my mind, not a convincing one. However there are far
more publications in science than any one individual can follow and
far too many fields for any one individual to specialize in. So I
read, I evaluate, and I value the opinion of people who I believe to
be experts in the field and whose evaluations I have reason to trust.
I do not put any faith in the opinions expressed in press releases by
institutions where a researcher works or by institutions that publish
popular non-technical books and television shows that are clearly
designed to promote their own products. So I put more stock in
Morris' assessment of Parker's work than I do in your assessment.

Where do I offer an 'assessment'? I simply stated that he gives an
account of the Cambrian 'explosion'.

You wrote "Parker argues (rather persuasively) that the evolution of
vision caused the Cambrian explosion.". Then, after several posts I
made quoting Morris as being highly critical of Parker's hypothesis,
you posted four separate responses still arguing that Parker "gives an
account" of the Cambrian 'explosion'. He does not give an account, he
tries to give an explanation. Whether he succeeded or failed is a
matter of opinion.


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