The Reason Eyes are Transparent Finally Becomes Clear

The Reason Eyes are Transparent Finally Becomes Clear, Livescience, Abigail W. Leonard, 19 July 2006 ...

[Graphic: MSNBC. Also at CBC, EurekAlert!, Medical News Today, Science Daily and the original PNAS paper. Thanks to Tom Magnuson at ARN's ID in the News where I first saw this.]

It is the transparent part of the eye, but for scientists, its origin was anything but clear. Now researchers have pinpointed why the cornea, the thin covering that allows light into the eye, is completely see-through. The discovery could lead to potential cures for eye disease and possibly even cancer.

Unlike almost every other part of the body, the cornea has no blood vessels and therefore no color. While that much was known, scientists couldn't figure out how the body kept blood vessels from growing there. The new research shows the area harbors large stores of a protein that binds to growth factors, material the body produces to stimulate blood vessel formation. The protein forms a sort of lock on the growth factors, so no blood vessels are produced, leaving the area totally colorless.

"Drugs designed to manipulate the levels of this protein could heal corneas that have undergone severe trauma or help shrink tumors fed by rapidly growing abnormal blood vessels," said Reza Dana, head of the Cornea Service at the Massachusetts Eye and Ear Infirmary and an associate professor at Harvard Medical School. "In fact, the next step in our work is exactly this."

The new discovery, which Dana and colleagues called unexpected, will be published this month in the Proceedings of the National Academy of Sciences ... [The PNAS paper says that "Transparency of the cornea, the window of the eye, is a prerequisite for vision" (my emphasis):

"Transparency of the cornea, the window of the eye, is a prerequisite for vision. Angiogenesis into the normally avascular cornea is incompatible with good vision and, therefore, the cornea is one of the few tissues in the human body where avascularity is actively maintained. Here, we provide evidence for a critical mechanism contributing to corneal avascularity. VEGF receptor, normally present on lymphatic and proliferating blood vascular endothelium, is strongly constitutively expressed by corneal epithelium and is mechanistically responsible for suppressing inflammatory corneal angiogenesis." (Cursiefen, C., et al., "Nonvascular VEGF receptor 3 expression by corneal epithelium maintains avascularity and vision," Proceedings of the National Academy of Sciences USA, July 18, 2006)

If they mean that literally, and what we were told in my biology degree classes is that scientific journal papers these days go through extensive checking, editing and rewriting, which can take many months, so I assume that they do mean that literally. That is, the cornea would have to be free of blood vessels from the beginning, and so could not progress through a Darwinian "6 per cent is better than 5, 7 per cent better than 6, and so on up the gradual, continuous series":

"In a primitive world where some creatures had no eyes at all and others had lensless eyes, the ones with lensless eyes would have all sorts of advantages. And there is a continuous series of Xs, such that each tiny improvement in sharpness of image, from swimming blur to perfect human vision, plausibly increases the organism's chances of surviving. The book [Hitching F., "The Neck of the Giraffe," Pan: London, 1982, p.103)] goes on to quote Stephen Jay Gould, the noted Harvard palaeontologist, as saying: `We avoid the excellent question, What good is 5 percent of an eye? by arguing that the possessor of such an incipient structure did not use it for sight.' [Gould S.J., "Ever Since Darwin," Penguin: London, 1978, p.107) An ancient animal with 5 per cent of an eye might indeed have used it for something other than sight, but it seems to me at least as likely that it used it for 5 per cent vision. And actually I don't think it is an excellent question. Vision that is 5 per cent as good as yours or mine is very much worth having in comparison with no vision at all. So is 1 per cent vision better than total blindness. And 6 per cent is better than 5, 7 per cent better than 6, and so on up the gradual, continuous series." (Dawkins R., "The Blind Watchmaker," Norton: New York, 1986, p.81)

Here is a 1940s quote by the late Edwin G. Conklin, Professor of Biology at Princeton, and an evolutionist, who cites "the beautiful dioptric apparatus of transparent cornea" amongst all the other "multitudes of beautifully coordinated structures and functions leading to an apparently designed end. Consider, for example, the improbability of being able to explain by such means the origin of all the adaptations and coadaptations of the eye" as part of "the enormous difficulty, if not the impossibility, of accounting for" them and it "by the sole method of natural selection, that is, by random mutations followed by the elimination of those individuals that are not well adapted":

"Practically all students of biology recognize the enormous difficulty, if not the impossibility, of accounting for all the numerous adaptations of an organism to its environment and all the multitude of coadaptations of the parts of an organism which are necessary to bring about their harmonious cooperation to a specific end, by the sole method of natural selection, that is, by random mutations followed by the elimination of those individuals that are not well adapted. Even if innumerable mutations and eliminations occur this seems a wholly inadequate cause; almost as improbable as the production of the Tragedy of Hamlet by a series of explosions in a composing room. There must be some other directing principle than mere chance in the production of such multitudes of beautifully coordinated structures and functions leading to an apparently designed end. Consider, for example, the improbability of being able to explain by such means the origin of all the adaptations and coadaptations of the eye of man-the remarkable fitness of the retina with its rods and cones and other elements for receiving and transmitting the stimuli of light of varying intensities and wavelengths; the beautiful dioptric apparatus of transparent cornea, lens and humors, the elastic lens with the ciliary muscles for focusing the light coming from near or far objects, the iris with its intrinsic muscles for controlling the amount of light admitted; the intrinsic nerve supply and blood vessels; the accessory parts for the protection of this delicate apparatus, the eyeball with its tough outer coat, the eye socket and bony orbit, eyelids and eyelashes and eyebrows, lachrymal glands and ducts, etc. Is it possible that all these adaptations and coadaptations have been produced by purely fortuitous mutations followed by elimination of those individuals that were not well adapted? Do we not load upon chance mutations an impossible burden in requiring it to provide all the structures and functions for such remarkable fitness? It is no wonder that Darwin is reported to have said he never thought of attempting to explain the origin of the eye without a shudder. (Conklin, E.G., "Man Real and Ideal: Observations and Reflections on Man's Nature, Development, and Destiny," Charles Scribner's Sons: New York NY, 1943, pp.51-52)

In general, this is just another "example of elegant, complex molecular machinery or system that science" is discovering that poses a further problem for Darwinian, `blind watchmaker' evolution to explain and "The conclusion of intelligent design is strengthened by":

"The future prospects for design are excellent, because they rest not on any person's or group's preferences, but on the data. The rise of the intelligent design hypothesis is not due to anything I or any other individual has written or said, but to the great advance of science in understanding life. In Darwin's day, the cell was thought to be so simple that first-rate scientists such as Thomas Huxley and Ernst Haeckel could seriously think that it might arise spontaneously from sea mud, which would be quite congenial to Darwinism. Even just fifty years ago it was a lot easier to believe that Darwinian evolution might explain the foundation of life, because so much less was known. But as science quickly advanced and the astonishing complexity of the cell became clear, the idea of intelligent design has become more and more compelling. The conclusion of intelligent design is strengthened by each new example of elegant, complex molecular machinery or system that science discovers at the foundation of life. In 1996 that elegance already could be clearly seen, and in the past ten years it has greatly increased. There is no reason to expect it to level off any time soon." (Behe, M.J., "Darwin's Black Box: The Biochemical Challenge to Evolution," [1996], Free Press: New York NY, 10th Anniversary Edition, 2006, p.270)

Perhaps the best evidence of this is that it is not the Darwinists who are seizing on these examples as evidence of the power of `blind watchmaker' natural selection of random micromutations. No, they are sticking with the comparatively trivial examples like, "Finch Beaks Say Darwin Was Right" which wouldn't matter if he was (but they even have problems with that)!]

Stephen E. Jones, BSc (Biol).
`Evolution Quotes Book'