Joined: Sep. 2006
|Quote (Cornelius Hunter @ Feb. 18 2007,03:41)|
|Addressing the second part of Deadman's post:|
Ahhh... Selective answering (or maybe you think deadmans questions were all encompasing).
|So is this then an evidential problem for evolution? For if basic baupan is hard to evolve, then how did evolution create such a menagerie? On the one hand, you want to argue that homologies such as the pentadactyl pattern are powerful evidence because, after all, it is so very difficult to modify. Therefore, when we observe it in different species, this must be evidence that the design was inherited from a common ancestor. But this is a curious argument to make when, on the other hand, we are saying evolution not only created the pentadactyl pattern, but very many other bauplan features over time.|
Let's find out when the pentadactyl pattern occurs during organism development. If it is early in the embryonic stage then the pattern could be considered "set" for all homologous creatures. After all, within the nested hierarchy of pentadactyl patterns we don't see ANY alterations to this pattern. We do see alterations to the FUNCTION of the pattern, but the pattern remains the same. Maybe alteration (read mutation) of this basic pattern causes too much developmental stress within the organism (there are too many faults expressed in a fully grown creature because of this mutation) that override any potential benefit from a change in this pattern.
Isn't the pentadactyl pattern a fundamental item in embryonic development just like notochords or hemispheric symmetry?
|Look here at the pentadactyl patterns:|
Then look here at thylacine:
and see the similarities with Canis lupus:
| The Thylacine showed many similarities to the members of the Canidae (dog) family of the Northern Hemisphere: sharp teeth, powerful jaws, raised heels and the same general body form. This is an example of convergent evolution. The skulls of the Thylacine (left) and the Timber Wolf, Canis lupus, are almost identical although the species are unrelated. |
Are you saying similarities between thylacines and wolves are insubstantial compared to the bat and horse pentadactyl designs?
The developmental patterns between thylacine and wolves are teeth, jaws, heels and body forms. Answerring without "theory laden" explanations leads me to ask a couple questions about these two creatures.
1. What is the basic food chain of the thylacine and wolves?
2. What is the hunting technique of these two creatures?
In (1.) I would answer that both creatures need to take down a variety of creatures both small and large. These are hunters more than scavengers most likely. The rate of food intake would probably require the creatures to fully consume any prey (as opposed to choice bits like lions) which would require consumption of not only meaty items but also of bone marrow. Since cracking bones requires set amount of forces I would surmise that the heavy set and muscular jaws are needed. Ever seen a hyena? Hunts in packs, hunter more than scavenger, eats (or trys to) everything on the body, looks like a wolf or a thylacine too. Amazing.
In (2.) the hunting technique is a pack technique with a lopeing gait instead of a fast dash. These creatures work together in tandem to wear down their prey over time, not to rush their prey like the cats. If the thylacine hunted like a cat then I would expect the body shape to resemble a leopord or lion more than a wolf or hyena. Are hyena's and wolves related?
|And answer this question: If species can exhibit similarities such as those in thylacines and wolves that are not due to common descent, then why must similarities such as the pentadactyl pattern be due to common descent? Do not merely explain the data according to evolution. This does not explain why it is powerful evidence. And do not presuppose evolution in your answer.|
But the genetic and developmental evidence need not be theory laden (that is, in ways that are peculiar to evolutionary theory). That’s the key.
My premise is that the pentadactyl pattern is buried deep within the embryonic stage of all the organisms that express this pattern. Changes to this pattern result in non-survivable offspring.
However, similarities with creatures who's environmental habits and lifestyle habits coincide lead to body plan developments that take advantage of that niche that they occupy.
What about Allosaurus and Tyranosaurus? They were only seperated by 90 million years (give or take). Yet their body plans are SO SIMILAR. Why don't we make this comparison to support evolution?
Are you going to get specific or do we continue with this charade. Actually, please be MORE condescending with us laymen. I'm just an engineer and my biology terminology stinks. Yet your latest attempt at conflation leaves me chuckling.
As I've said to AFDave before. Is that all you've got?