Posted: Aug 30, 2010 10:49 am
by Shrunk
stevebee92653 wrote: "the common ancestor of all tetrapods already had a highly developed visual system" (Where did they get it from? And ALL of the other systems they had to have to pass on all organs/systems extant and common to their descendants? The CA species had to have them ALL, or extant species descendants of the CA would be missing "things".)
This is such a simple concept. It amazes me the hoops you will jump through to pretend like it's not a problem. You blind yourself to reality.

And how is this a problem? Let's again quote your post to which hallucigenia was responding:

Your explanation is clear, but not correct. The common ancestor to all tetrapods with the visual system you example, also had to evolve ALL of the other organs and systems common to all tetrapods. Hepatic systems, multi-chambered heart/lung/blood/blood vessel/brain controller/cardiac muscle systems, pancreas, gastro-intestinal system, auditory, and on and on, all in one species. You can't simply choose to isolate and discuss one system without addressing all systems. Do you actually think all systems extant and common to all tetrapods evolved in that one single species CA?
Now we must multiply everything that so that all CA's of all modern groups must have evolved all systems common and extant to all species in each CA's descendant groups. Your problem is you isolate one single system, vision, and tell me that that single CA spread that one system to all future tetrapods. You totally ignore the fact that there are many systems to deal with in many different species groups. For example, vision had to evolve independently in each one of those SINGLE species common ancestors to all eyed groups of species. According to you, the approximately 36 phyla would each have to have their own single CA, and each single CA would have to evolve all of the organ/systems extant and common to that phylum.

That's your problem right there. You can't seem to understand that each of those 36 CA for those phyla are also related by common descent. They didn't all have to "evolve" organ systems on their own. They already inherited from their ancestors.

You keep challenging us to draw phylogenetic trees demonstrating the genetic inheritance of these "organ systems", yet you have yet to provide an example of where this seems not to make sense to you. For instance, if your beliefs were correct, we should see the same "organ systems" appearing in various phyla that were not present in any of their respective CA's.

For instance, we should find an "organ system" developing in, say, nematodes that was not present in the CA of all nematodes, and the same organ system also developing in chordates, and/or arthropods and/or flat worms etc that was also not present in their respective CA's. You say you've already worked all this out, so it should be no problem for you to provide abundant examples of such "spread of organ systems" that would require intraspecies procreation.

Ball's in your court, Steve.