Re: The Cambrian again?

Cliff Lundberg (cliff@noe.com)
Tue, 30 Nov 1999 21:00:00 -0800

Susan B wrote:
>At 03:54 PM 11/29/99 -0800, you wrote:
>>Susan Brassfield wrote:
>>
>>>In Darwin's day it was thought that the earth was millions of years old. It
>>>was a weakness in Darwin's theory because that was not enough time for
>>>evolution to have happened. Almost a half-century after he died
>>>cosmologists and physicists discovered that the earth and the universe were
>>>*billions* of years old. They changed everyone's mind about the short
>>>life-span of the earth, but not by saying "well, we feel it's lots older,
>>>that's our opinion and we're entitled to our opinion." They did it by
>>>presenting convincing evidence.
>
>Cliff Lundberg:
>>Like the evidence that shows that the formation of all the major metazoan
>>phyla took place within 5 million years?
>>
>>Maybe you need to put that argument away; it doesn't work anymore.
>
>I was talking about cosmology and the scientific principle of collecting
>evidence. What the heck are *you* talking about?

I'm talking about your assertion that in Darwin's time the planet was
thought to be mere millions of years old, and that this was a problem for
his theory, which was solved by more modern geological dating, which
allowed much more time for evolution to take place. If this was a problem,
as you assert, it has been revived by recent findings about the pace of
evolution in the Cambrian. The time frame for the emergence of the major
phyla is down to 5 million years, and those capable of extrapolating trends
won't be amazed to learn that the window is even smaller.

>The Cambrian again?

'The Cambrian, never again' would be more apt. Evolutionary events
occurred then that were qualitatively different from what happened before
or since.

>Do you
>realize that 5 million years is *500 TIMES* the length of time our own
>species has been on the earth? It's not exactly a snap of the fingers.

550 million is years is a long time too, a long time with no new
phyla appearing. What's the explanation?

>Also you seem to be ignoring the fact that there are plenty of
>pre-Cambrian fossils.

Yep, they just don't seem that complex, compared to the Cambrian
fauna.

>You also seem to think that the rapid origin of *phyla* is
>significant. Why?

Rapid origin of whole complex new forms is antithetical to the
evolutionary theory I was taught. When the facts conflict with the
theory, that's significant.

>So what? What about all the classes, orders and families
>that have evolved since that time?

Incremental Darwinian change. Why no new phyla?

>What about the fact that almost none of the animals and plants
>living then still exist?

Their descendants have been modified through Darwinian
evolution. No problem. The problem is the absence of major
new developments, in contrast to the rapidity of new developments
in the early Cambrian.

I don't see what fun there is in indignantly arguing for old evolutionary
dogma, and ignoring the anomalies that make the subject interesting.

--Cliff Lundberg  ~  San Francisco  ~  cliff@noe.com