One of the features of the mammalian eye is that the photocells in the retina are installed backwards. The light-sensitive portion is away from the pupil, and the support hardware -- the rest of the cell, and the nerve fibers connecting them to the optic nerve -- are between the photoreceptors and the light they're supposed to detect. "Leon" at the Debunk Creation mailing list, forwarded this for comment:...[M]olecular biologist Michael Denton of the University of Otago who is also one of the most prominent critics of Darwinism today. In "The Inverted Retina: Maladaption or Pre-adaptation?," published in Origins and Design magazine, he explains how the inverted retina that Dawkins presented as faulty is actually created in the most efficient manner possible for the vertebrateeye:. . . consideration of the very high energy demands of the photoreceptor cells in the vertebrate retina suggests that rather than being a challenge to teleology, the curious inverted design of the vertebrate retina may in fact represent a unique solution to the problem of providing the highly active photoreceptor cells of higher vertebrates with copious quantities of oxygen and nutrients.To keep up this high rate of metabolism, of course, the retina cells need a great deal of energy....How do these cells, that enable us to see, meet their extraordinary need for nourishment and oxygen?Through the blood, of course, like the rest of the body.Where, then, does the blood come from?At this point, we see why the inverted retina is a perfect sign of Creation. Right external to the retina layer lies a very important tissue of veins that envelop it like a net.....In a relevant article, Denton examines whether the retina could have been formed in a different way. His conclusion was that it could not. Dawkins' suggestion that the retina should be flat, with the receptor cells facing the light, would distance them from the capillaries that nourish them and in great measure, would rob them of oxygen and nutrients they need. Extending the capillaries into the retina layer would not solve the problem, because this would produce many blind spots and reduce the eye's ability to see.
And comments he got, including:
What are the oxygen requirements of invertebrate eyes in comparison to other cells in their bodies?The question being begged here is: Why couldn't an intelligent designer make a vertebrate eye that doesn't depend on such a convoluted system of interdependency? Also, the "reverse" design of the vertebrate eye leads to relatively easy retinal detachment. Evolution is, of course, a series of tradeoffs between resource requirements and efficiency. To be effective, IDiots have to explain why an intelligent designer would be subject to these same trade offs and why, if the intelligent designer could design such efficient "forward" eyes for invertebrates he/she/it could not also do so for vertebrate eyes.
And:
Just a specific instance of a general form.Summary:1. Darwinist gives explanation X2. Explanation Y is a possible apparent alternative.3. Therefore ALL evolution MUST be false.4. QED Creation must be true.
And:
Point out to this person that Denton now accepts evolution and has written a further book pointing out where he was previously mistaken:It is easier than trying to refute the twit point by point.
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