Posted: Aug 29, 2010 11:25 am
by halucigenia
stevebee92653 wrote:Thanks for the rare intelligent answer and discussion. I really wish more people here could discuss as you have.
Thanks for the compliment, and I will try very hard not to insult you personally, your ideas and way of thinking is another matter entirely, these are fair game in a debate and if someone spouts nonsense I would expect them to get called on it.
stevebee92653 wrote:This really is such a fun and fascinating subject. Discussing it should be open and respectful. But oh well.
Well I guess you can respect the person without respecting their arguments but as everyone here knows that is a bit of a sham simply for the sake of the decorum of the forum. It is extremely difficult to respect someone who believes in ludicrous ideas, promotes false information and are themselves disrespectful to whole swathes of the scientific and rational community, but of course I say this in all respect and apply it as a generalism to people who do these things and do not direct it specifically at you ;).
Anyway before I show any disrespect to you personally I'd better move on.
stevebee92653 wrote:You run into HUGE problems right at the start. Your explanation is clear, but not correct.
I would agree that it may not be correct and I am open to discussion on exactly how it may not be correct in detail, however it was only meant to be an example of the reasoning behind the argument for common ancestry as the solution to your false dilemma. I am sure that there are many people here on this forum that could correct any mistakes I have made in my outline, however I will continue to show you how you misunderstand or deliberately misconstrue my argument.
stevebee92653 wrote: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.
There's a misunderstanding straight away, what I actually suggested was that the common ancestor of all tetrapods already had a highly developed visual system, that the visual system evolved in the common ancestor of all vertebrates. So the common ancestor of tetrapods did not have to evolve that particular system it inherited it form the common ancestor of all organsims that have that particular visual system, those organisms include tetrapods but are not exclusively tetrapods as fish and all vertebrates have that same visual system. Therefore there does not have to be a single common ancestor that had to evolve all those systems you mention, it is perfectly plausible they inherited them form their own ancestors or that they did not evolve until after that specific ancestor.
stevebee92653 wrote:You can't simply choose to isolate and discuss one system without addressing all systems.
I did not isolate a single system but discussed more than one to get my point across. Although I did not discuss all the systems you mention, this was done simply to simplify the explanation, we could go on to address all the other systems if you want, but the principle is the same, the origins of any biological system will be found to be in a particular species which then goes on to become the common ancestor of all subsequent species that have that particular system. The fact that these systems are currently integrated systems is a consequence of evolution and not evidence that they had to be developed at the same point in time within the same species. Take for example the integration of the circulatory and respiratory system, as per my example, though I did not explicitly state it above, the circulatory system evolved as species gained an advantage in being larger, necessitating a system to supply oxygen to internal tissues, of course this evolved long before lungs as these organisms were aquatic. It was not until aquatic creatures found themselves in an environment in which they benefited from extracting oxygen form the air that the rudimentary lung evolved, with already evolved circulatory systems that were already in place and used to convey oxygen to internal tissues that these lungs could then be integrated with. And of course the tissues that the rudimentary lung was developed from were already integrated with the circulatory system as part of the digestive system (which is a whole other page in the book of evolution and developed in other ancestral species).
stevebee92653 wrote:Do you actually think all systems extant and common to all tetrapods evolved in that one single species CA?
Er, no, that would be part of your false dilemma and a strawman that no one actually holds to be true.
stevebee92653 wrote: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.
Well you could be right if you take that ambiguous statement, which almost describes the nested hierarchies that we do see, to mean that they did not have to evolve all systems at the same time, some earlier common ancestors to larger groups, that for example all have a circulatory system, evolved that system, while the common ancestors of the later groups which already had that system then went on to evolve other systems like for example the respiratory system. So, you could say that all common ancestors had to evolve all systems common and extant to all species in the common ancestors descendant groups, and still be correct, it's just that there were several common ancestors to all extant groups, along the time-line of the ancestry of that group - not that they existed at the same time, the earlier ancestors being the ones which evolved the systems that are extant in many groups spanning more groups in the hierarchy, the more recent ancestors being the ones which evolved the systems that are extant in fewer of the groups so spanning less groups in the hierarchy.
stevebee92653 wrote: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.
No, you totally ignore the fact that I specifically chose more than one system to illustrate the solution to your false dilemma.
stevebee92653 wrote:For example, vision had to evolve independently in each one of those SINGLE species common ancestors to all eyed groups of species.
Well the statement “those SINGLE species common ancestors” makes no sense whatsoever, a common ancestor must be common to more than one species, however, I will try and interpret that the way you are trying to convey that is that the common ancestor of several species is itself a single species which is what I alluded to. So since a common ancestor is in itself a single species there can be only one species in which a particular vision system evolved, this single common ancestor being common to all those groups that have that particular vision system, so it's not necessary to invoke independent evolution of any particular vision system in many different species at the same time. Your dilemma therefore is overcome by postulating that, as we observe, there are several vision systems each of which has a separate common ancestor species which evolved different vision systems and different types of eyes such as the vertebrate eye type and the cephalopod eye type – superficially similar but different enough in detail to postulate separate common ancestors which evolved these eyes independently. And of course completely different eye types such as the compound eye type seen in insects for example also evolved in a different common ancestor which propagated the possibility of using that eye type to all it's descendants.
stevebee92653 wrote: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. If that was not the case, then you run into the problem again of multiple species evolving multiple organs\systems and then having to somehow spread those systems around to other species. And then getting all of those organ/systems, that evolved in multiple species tucked into that one common ancestor.
Of course the species (and Classes, Orders, Families, and Genus) within each of those phyla had the same common ancestor but there are also different common ancestor species for each of the other levels of the nested hierarchy such as Class, Order, Family, and Genus, as well as different points along the way where different biological systems evolved – they don't have to all evolve in the same species that was the common ancestor of any particular level of the hierarchy. What we actually do see is that several groups can have common biological systems, therefore those systems must have evolved in the common ancestors of that group. We also we find that only some classes of any particular higher grouping share a common biological system where other classes don't have this particular system therefore those systems must have evolved in a common ancestor to only that sub group of classes as the system is not shared by all classes of that group etc.etc. - a nested hierarchical suture of sub groups within groups. It just happens that to conveniently delineate these groups that we distinguish that we align the break points to coincide with major biological evolutionary innovations.
stevebee92653 wrote:If you disagree, pencil out a diagrammatic tree and try and track where the organs and systems would go. You will get stuck quickly.
I am sure that there are plenty of examples of cladistic diagrams that have already been drawn up, some examples of which you have been shown or pointed to already. Now, if you have any examples of where you personally get stuck when following these examples I am sure that we could discuss those but it's not worth my while to go to the trouble of drawing a diagrammatic representation just for you to summarily dismiss it. Just try to understand my explanations and how they refute your false dilemma argument for now.
stevebee92653 wrote:BTW, of course you realize that the ISP thing is Tongue In Cheek. I placed "TIC" twice in the vid in case someone thinks it's serious. But the point of the vid IS serious.
Of course I do, love the winking jellyfish BTW, but you are claiming that it's either ISP or ID whereas, once you actually understand it, the concept of nested hierarchies and common descent for the various biological systems actually explains how these systems were propagated to all the species that posses them quite easily and, IMHO, simply, though if you don't understand it after that mammoth explanation I suppose I only have myself to blame, unless you are being wilfully ignorant or simply trolling.