Re: Musings about the Cambrian Explosion


"Catherine Woodgold" <an588@xxxxxxxxxxxxxxxxxxx> wrote in message
news:dhv9l5$1mlo$1@xxxxxxxxxxxxxxxxxxxxxx
>> "g" <gillawton@xxxxxxxxxxxxx> wrote in message
>> news:dhii29$2s7v$1@xxxxxxxxxxxxxxxxxxxxxx
>>> be more or less favored. The atmosphere's oxygen content and carbon
>>> dioxide
>>> content increased and, as the percentage of oxygen increased, there was
>>> more
>>> of it that could be utilized by fauna if they mutated in ways that
>>> availed
>>> them of the opportunity.
>
> I think that may have been the theory I read: when the oxygen
> level increased, there was a lot more energy and opportunity
> available and life went wild. Sounds reasonable to me.
> --
> Cathy Woodgold
> http://www.ncf.ca/~an588/par_home.html
> We are all Iraqis now.
>
Cathy,

Thank you for the input.

I have taken the issues involved beyond the blanket (or general) level of
opportunities as opportunities, and into ramifications of constraints and
challenges proffered by those opportunities, and varying in
accordance with their lack of homogeneity. The increase in the ratio of
oxygen to other gasses in 'air' would seem to have been primarily
advantageous, but would have presented also the challenge of evolving ways
of respiring the energy from that, and constraints of evolving to tolerate
it. (And, of course, anaerobic "packages of life characteristics" did not
"do it thataway," nor did the creatures deeper in the earth and sea that
respire sulfur instead of oxygen.

As you can see, I am welcoming your support on the "oxygen ratio increase,"
and inviting more on some of the complexitities.

But the main thing nagging at me (as set out more fully in the post directed
to Jim, a moment ago, is the question of whether the full acceleration known
as the Cambrian "explosion" (of diversity) might have derived not only from
opportunities over a heterogeneous climate and geography... not only from
the constraints of same... not only from challenges to avail of same... but
also... whether some factors might have impacted the very mechanisms and
pre-organs or organs, themselves, whereby replication and reproduction
occurred.

It seems to me that any mechanism or organ of the body can be impacted by
differences in circumstances surrounding (external to the body or internal
in it). And, therefore, it seems to me that a full accounting of why there
was such an "explosion" of diversification of living things during the
Cambrian might required more than what is known nowadays as the normal and
usual rate of mutation in various
species.

Some (I won't say who) who have metaphysical or doctrinal motives have
questioned whether the normal and usual rate of mutations would account for
the amount of diversification that is evidenced by
paleontological fossils. I do not take any side on that and can only say,
"I don't know whether that is true or not."

What I AM trying to say is that I cannot conceive of any reason why that
rate could not have been accelerated during the Cambrian by more than the
heterogeneity of opportunities of the time, more than by constraints
attaching to that heterogeneity, more than by challenges of that
heterogeneity and by
one or more factors that worked DIRECTLY to accelerate mutation rate, by
acting upon the replicatory, or reproductive mechanisms/organs THEMSELVES.

This is not a hypothesis. It is merely a brainstorming... an asking of
questions... which -- in my wildest dreams -- MIGHT have a chance of leading
someone to a hypothesis supported by results of other
hypotheses that HAVE been tested -- sufficiently to steer something that can
be empirically tested.

As one poster said, "We cannot recreate a diversification explosion in a
test tube."

Duhhhhh. Okay.

But the question is: Can we increase the rate of mutation in a test tube?
And, also, if we succeed, will we accomplish nothing more than to render the
sample sterile, by pushing it too fast.

Alas, there are some experiments that might take us a couple of hundred
million years to run.

As another poster has said, "A computer simulation is not real life."

Sometimes, when a football team cannot make it to the goal line, within the
allotted time, a field goal can be the next best thing. Maybe a computer
simulation is, similarly, a better choice than an impossible one.

This poster makes NO PRETENSE of expertise nor originality. This is a
brainstorming, not an argument nor a bragfest. (:>)

Your response much appreciated. Hope it won't be your last.

g




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