Hi all;
I'm no following either sides arguments all that well, so perhaps a few of you can clarify them for me.
My understanding of biologicdal evoltion is that it is a process of descent from one, or no more than a few, common ancestors. That is, that it is a matter of continuous subdivision of categories from one general category down through several alterations or sub-categories withinn that overall category. This is the notion of 'nested hierarchy'-- am I right.
Next, the "Cambrian Explosion" was a geologically brief time period during which, after several billions of years of 'life' subdividing into 'kingdoms'and 'sub-kingdoms, suddenly sprout more subdivisions we call 'phyla. Now, according to the theory these 'phyla' are subdivions of a 'nested hierarchy' within ;'life' which is over 'kingdoms' which is over 'sub-kingdoms' which is over 'phyla' which is over... and so on. Am I right so far?
Now, here is where it gets tricky. The darwinian side rejects the argument that something is wrong when the sub-kingdoms, kingdoms, and 'life' [per se] that produced the 'phyla' during the relatively short pre- and post- "Cambriam Explosion" epoch simply shut down and produced no more of them. Indeed, if memory serves, allowed some of the cambriam phyla to go extinct. Now, if the argument is the one darwinians are making, i.e., the 'nested hierarchy' argument, they cannot use it for post-phyla evolution without using it for pre-phyla evolution, and in that case, they cannot use it against randman's argument that pre-phyla nested hierarchies [kingdom, sub-kingdom]should still be generating new phyla, just as they did in the first place. But they do not.
The only objection to randman's argument that I can see is extinction. If life still exists, and evidently it does, then some of the 'kingdoms', [or at least some of the 'sub-kingdoms'], that first produced the 'nested' sub-divisions, and were necessary to their generation, the phyla, must themselves have gone extinct at that time, thus shutting down phylum production for good and all.
If there is no evidence of whole kingdom or sub-kingdom extinction in the fossil record, then it would appear that randman has a valid point. Which raises the issue that if 'nested hierarchies' were not responsible for the evolution of the the phyla by 'common descent', as 'nested hierarchies' appear to explain post-phyla evolution, into more and different sub-categories , then something else must have been present at that time which no longer exists, or at least, no longer acts. If it exists but no longer acts, that would be quite irrational, so I opt for 'no longer exists', whatever it was. I just can't imagine what it might have been?!?
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