N.Wells
Posts: 1836
Joined: Oct. 2005
|
| Quote | | Having "application to real world problems" is not reliable evidence of biological accuracy, or even indicates being on the right track. That can easily be misleading to the point of eventually derailing your own train. Why bother checking whether inverted retina's have light-guides or other collection systems when you already know that Darwinian theory and your models with such application to real world problems predict that it supposed to all messed up by nerves and blood vessels being top of the receptors blocking light from reaching them? |
A model that produces successful applications is more fruitful than one that doesn't, and fruitfulness is one of several measures of success by which theories are measured. A model that is wrong cannot yield successful applications as readily as a model that is a better approximation to reality.
Your ideas about inverted retinas, evolutionary predictions, and scientific procedures here are bizarre, to put it mildly. Darwinian theory does not predict that chordate eyes will necessarily be a mess. It predicts that organs and systems should generally be as well adapted as they need to be, rather than as perfectly adapted as they might be. (Features have to pay off in terms of benefits conferred versus developmental and maintenance costs incurred, or selection will work against them.) This means that most features should be quite well adapted. However, the possibility exists that (contrary to assertions by the bible) some systems or organs may be messed up if selective pressure against the poor version is not very strong. When this happens, it should most likely result when the organism no longer has need of that organ, or when it has inherited a version from ancestors where the problems were not of concern to those ancestors and the fixes are not readily available, such as the broken Vitamin C genes in ancestral primates whose diets gave them abundant Vitamin C, and broken color-vision systems in ancestral mammals, who were nocturnal.
According to previous anatomical investigations, vertebrate eyes seemed to be quite inefficient in design (inverted, with complex tissues blocking the path between the lens and the photoreceptors at the back of the retina. This was not predicted by evolutionary theory, but can be explained by it. More recent studies show that there are some fixes for the problems that had escaped attention, making the problems less serious than initially realized. Creationists had raised invalid arguments against messed up eyes, on the grounds of their beliefs that there are no vestigial features, but they were not the people who made the important discoveries. The discoverers of the unexpected contributions of Muller cells (K. Franze, J. Grosche, S.N. Skatchkov, S. Schinkinger, C. Foja, D. Schild, O. Uckermann, K. Travis, A. Reichenbach, and J. Guck) aren't creationists or IDists, but are regular biologists who are working within a standard scientific methodology, using a regular evolutionary framework.
Franze et al. write in http://cdn.intechopen.com/pdfs-wm....583.pdf (a lovely paper, well worth reading by anybody as an excellent case study in how to do science and how to explain your ideas clearly and how to present the evidence that leads to your conclusions): "To understand the inversion of the vertebrate retina, it is essential to keep in mind that vertebrates belong to the deuterostomian animals which means that our ancestors belong to the relatives of recent starfish and sea urchins. ..... Notably, this polarity [in the starfish, in the marine environment] is obviously ‘correct’ and easily comprehensible. .......In the further course of evolution, the epithelial nervous system was maintained as such, but was enrolled into a tube and moved below the surface of the body by the overfolding or overgrowing skin and subepidermal layers. Similar events occur during our embryogenesis when the – originally superficial - neural plate is enrolled and overlayed in a process called neurulation (Fig. 2). Inevitably, this mechanism is accompanied by an inside-out turn of the polarized epithelium: the sensory cells which had faced the environment at the surface of the body now extend their sensory processes into the lumen – i.e., the inner surface - of the neural tube. This also explains for the ‘odd’ orientation of our retina (Fig. 1), with the photoreceptor cells directed away from the light. During the evagination of the optic vesicle from the neural tube the ‘sensory surface’ remains at the inner, ‘wrong’ surface (Fig. 2). Thus, the normal developmental mechanisms of our eyes inevitably lead to an inverted retina.[/quote] This shows that they are clearly seeing evolutionary theory as the best theoretical framework for understanding vertebrate eyes.
Notably, they did not do what you do (make groundless assertions that aren't backed up by evidence). They apparently started with a feeling that the textbook explanations weren't satisfactory based on the way the funnel-shapped Muller cells covered both the top and the bottom of the retina while also passing through it, but they backed that up with dissections and other anatomical investigations, experiments, measurements of light transmission, physical modelling using fiber-optic plates as analogs for retinas, mathematical modelling, and logical explanations for what they were seeing. In short, excellent science, completely unlike what you are doing.
All of this aside, it remains the case that the structure of the vertebrate eye is bizarre and needs a fix: the news is that it has a fix, notably a very complicated one, that would not have been necessary had the design been more logical at the outset.
|
