Daniel Smith
Posts: 970
Joined: Sep. 2007
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| Quote (mitschlag @ Feb. 23 2009,14:21) | | Quote (Daniel Smith @ Feb. 22 2009,12:55) |
One thing you repeatedly fail to mention is that Schindewolf's area of expertise and study was not horses - it was cephalopods and stony corals - for which he documented extensive patterns of evolution. Horses were a periphery issue for him - one for which he probably accepted the commonly delineated pathway for his day.
Thus I can understand why you'd want to focus on horses, since - as you've just documented - all Schindewolf's contemporaries missed the mark to a degree, but no discussion of Schindewolf is worth having if it's not about the area he excelled in - cephalopods and stony corals. |
Daniel, please, enough with the ad hominems. I'm working here in good faith. You want to discuss cephalopods and stony corals, we'll discuss them.
Here is what Schindewolf says on pages 269-270:
| Quote | Examples of Orthogenesis
In ammonites, after the frilling of the suture has been introduced as a fundamentally new process, it continues to develop step by step until the last tiny bit of lobe and saddle margin is broken up into extremely fine teeth and notches. Further, as soon as the principle of the differentiation of the suture line through saddle splitting has been acquired, it is unswervingly pursued, and one by one,one after another, new lobal elements are emplaced. This saddle splitting may affect different saddles, either the inner or the outer ones; at first, the choice was open. But after the decision was made in favor of one site or the other, further development was inevitable, preordained. The same is true for the increase in the number of lobal elements through lobe splitting. Once this mode had been “invented” by a particular form, its descendants carried it on; the mode prevailed, and there was no stopping it, no going back, and no breaking away from the evolutionary direction once it was established.
In the nautiloids and the ammonoids, the coiling of the shell progressed in an orderly way. in the process, however, a decided difference appeared between the two groups, as we have seen (figs. 3.34 and 3.35): in the ammonoids, the axis of coiling runs through the protoconch, located at the center of the shell; in the nautiloids, however, the protoconch is eccentric, lying next to the axis of the shell. Thus, the further course of evolution is dictated in advance by the respective initial forms: as the move toward ever tighter coiling progressed, the protoconch of the ammonoids had to participate in the process and acquired a spiral torsion; in contrast, in the nautiloids, in order to arrive at as tightly closed a spiral as possible, one with no perforation, the protoconch had to become increasingly smaller and assume a flat, cowled form. Once the preconditions were established, no other mechanical possibilities were open to the protoconch, and we then see evolution proceeding in a straight line along the path marked out for it.
The unfolding of the stony corals is dominated by a progressive replacement of the original bilateral arrangement of the septal apparatuses by a radial one (fig. 3.46). The direction of this course is determined ahead of time by the decidedly hexamerous stage of the six protosepta, which makes a temporary appearance early in the ontogeny of the pterocorals. Thus, the structural design of the lineage is laid down from the beginning and is executed as a complete, pure realization of this hexamerous emplacement by suppression and progressive dissolution of the bilateral features, which at first dominated the mature stages of the pterocorals. In those mature stages, as we recall, only four quadrants were completely developed, and remarkably, this peculiarity was also passed on to the heterocorals, which issued from the pterocorals, as a general morphological capability, although there, it was carried out in a completely different way. |
I have bolded sections that trouble me. Can you guess why I'm troubled? |
Probably because you stopped reading.
On page 272 he continues:
| Quote | The unwary observer could easily form the impression that evolution is purposeful, that right from the beginning it is directed toward a predetermined goal and that the path it follows is determined by the goal. Such a finalistic explanation, however cannot be seriously supported; there is no basis for it in natural science, and the observed facts do not warrant it in the least.
Rather things are just the opposite, in that it is not the conceptual final point but the concrete starting point that determines and brings about the orientation of evolution. Such a view can be based on actual, causative mechanisms and does not take refuge in mystical principles of any kind. The explanation lies in the fact that the set of rudiments in the first representatives of each lineage largely determines later evolution, and that subsequent differentiational steps entail a progressive narrowing of evolutionary creative potential
[italics his] |
I don't agree with Schindewolf on this point, but he is basing his argument on "natural science", while I am basing mine on theology.
The question you are asking is whether the actual evidence supports orthogenesis or not. As you know, Schindewolf cataloged volumes of evidence which he thought supported such an interpretation. Others think differently. I don't know that horse evolution proves or disproves either conclusion. Gould seemed much more concerned with all the branches on the evolutionary tree while Schindewolf seemed intent on the specific lineage that led to the North American Horse.
Orthogenesis is not the main issue for me - although I'm inclined to believe it is a real phenomenon. Schindewolf, as you know, felt that evolution could be divided into three phases. He did not believe the first phase - the saltational typogenesis - to be constrained by orthogenetic forces. That is the phase of evolution I am most concerned about - the saltational, creative phase.
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"If we all worked on the assumption that what is accepted as true is really true, there would be little hope of advance." Orville Wright
"The presence or absence of a creative super-intelligence is unequivocally a scientific question." Richard Dawkins
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