Esquema del ojo human. Image: www.fisicanet.com
The complicated sophistication around the eye and vision system that accompanies it, already worried Darwin himself mentioned the problem of vision, saying that sometimes " took away the dream. " In the first editions of his book "The Origin of Species", boasting of sincerity, wrote:
"If you could prove the existence of any complex organ could not have formed by numerous successive slight modifications, my theory fall apart completely. "
Later in the sixth edition of his book, considered as the "definitive", Darwin, and more emboldened by knowing Haeckel publications and other colleagues who supported him completely changed perspective and wrote:
"seems absurd in every way, I confess spontaneously, suppose that the eye, with all his inimitable down to bring the focus to different distances, for admitting light and variable amount for the correction of spherical and chromatic aberration, could have formed by natural selection ...... But reason tells me that if they can demonstrate there are many gradations from a simple and imperfect eye to one complex and perfect eyes, each degree useful to the animal that possesses it, as indeed; if in addition the eye ever varies and the variations are inherited, as is also true, and if these variations are useful to an animal under changing conditions of life, then the difficulty of believing that a perfect and complex eye could be formed by natural selection even though insuperable to our imagination, should not be considered as destructive of our theory. " [1]
is clear that Mr. Darwin was a master of rhetoric, so if we understand correctly, if we can find among all living things, different types of eyes from what can be understood as a body vision "simple", to what our eye can be "complex" and demonstrated that our eye has arisen for a number of modifications, or "beneficial bugs" from the organ of vision simple. Well despite the obvious absurdity of that conclusion from those premises, there have been eminent scientists who have established, as the idea of \u200b\u200bDarwin, this list of "ancestors" of our eye. [2]
They all seem to agree that the simpler visual organ is the one with the Euglena, [3] which is a type of protozoan flagellate, sometimes confused with algae. Lives in fresh water and has a photosensitive organelle lets you target the direction from which light arrives.
• In first place, it seems possible to see what advantage has meant to the Euglena have this organelle, as calm as still living together with other algae and other protozoa that have no photosensitive organelle.
• In second place would have to prove that the Euglena lived in remote times when life began, and check that I had the photosensitive organelle.
• Third would have to explain why it has evolved since then.
• And fourth, should demonstrate how you can go from this organelle to our sophisticated eye with its lens, the iris, the retina, her pupil, her tear ducts, eyelids, eyelashes, their photoreceptors, their muscles to focus, their optic nerves, brain mechanisms for the interpretation of the images, the arteries that supply everything, etc. etc. And to answer that "it is possible with the passage of millions of years" is not answering anything, just using a loophole.
Image: http://laimagendeuninstituto.blospot.com ■ EYE of trilobites
Let's discuss the case of the eye of trilobites, and thus, we considered settled this matter. You could write millions of pages to remove the assumption of gradualism, but we believe that what we said and with this example is sufficient.
Trilobites are considered highly organized the first animals that inhabited the primitive seas, their fossils are fairly abundant and well studied. The oldest appears at the beginning of the Cambrian period, and were very abundant until at least the Permian, virtually the entire era Primaria.
is therefore expected that, having appeared so early in the earth, its vision system to be quite "simple", according to the Darwinian theory, but reality once more, it seems that does not fit. Consider what is known of the "primitive" visual system of trilobites. To this end, we summarize the well-documented presentation that makes this issue Mr G. Rattray. [4]
Trilobites belonging to the arthropods, have eyes that consist of a bundle of columns, each with its lens on the top, and the photoreceptor at the bottom, and the whole beam is protected by a cornea. The columns are not completely parallel, but fan out, each run in one direction, the combination does not produce an image like that is our eye, each column produces its own image. Have been able to count in some eyes of trilobites fossils up to 770 columns.
In 1973, Towe Keenneth [5] published an interesting study that stated that the eyes of trilobites consisted of calcite crystals with column-shaped, lined with exquisite precision. Removed the eye of a fossil with a microscope could see that as the column to focus, producing a clear and crisp but varied from one column to another, each "focused" to a different distance, allowing the trilobites have both a set of sharp images of everything around him, from what it was several millimeters from his eye to what was in the distance.
until now been assumed that these crystals of calcite that "stuffed" the eye of trilobites were the result of the fossilization process, but as Towe found in most modern fossil arthropods, whose eyes have appeared filled with calcite crystals, they were arranged without any order, and not let in light. For a calcite crystal miss the light, it is essential that the glass is exactly aligned with the direction of the ray of light entering it, otherwise the beam of light begins to bounce off the walls and breaks down into various colors . But in the eye of trilobites, each calcite crystal transmits light with the transparency of glass. So Towe demonstrated, with several cases, calcite crystals in the eyes of trilobites was his way of seeing, not a result of fossilization. But not even stop.
The eye of a trilobite fossil. Image: http://photos2extreblog.com In the same year took place in Oslo 1973 International Conference on trilobites. There, R. Levi-Setti [6] said the whole affair of the eye of trilobites with Professor Clarkson, who, back to Edinburgh University where he worked, began to spin until he found the "Traité de la lumiere" of Christian Huygens published in 1690, the description of an aplanatic lens [7] produces no aberration ball, which was similar to drawings of the cornea of \u200b\u200bthe eyes of trilobites that had left Levi-Setti. After
, Clarkson found in "geometry" of Descartes, published in 1637, other pictures of another model to correct lens aberrations, different from Huygens, but it coincided with the pictures I had of the second lens (which is placed on top of each column of calcite) in the eyes of the trilobites. Thus
concluded Mr. Clarkson: [8] Trilobites at the beginning of the Cambrian, and had solved the problem of aberration of lenses, the delicate question of approach to different distances, had made in their eyes the models of Descartes and Huygens, applied the principle of phenate, Abbé law, the laws of refraction and Snell all known optical birefringent crystal.
seems sufficient.
We can not name the eye of the shrimp with the trilobites lived in the seas of the primary and who were trained by a sophisticated system of mirrors that reminds the reader of bar code which is usually built into the counter Box of existing supermarkets. [9]
[1] Darwin Ch. "The Origin of Species." P. 1988 Espasa Calpe. 230.
[2] H. Hass. "From fish to man." Salvat 1987. pg. 48 to 58. Sir G.
De Beer. "Atlas of Evolution, Nelson. London 1964.
Dawkins [3] About Euglena photosensitive organ, see: Diehn and Tollin, Arizona Univ. Atome - 249, December 1967.
[4] G. Rattray. "The great mystery of evolution" Edit. 1983 Metro. pg. 94 to 97.
[5] Towe, Kenneth, "The eyes of trilobites: calcified lenses in vivo", Science - 179 - 1007 to 1973.
[6] Ricardo Levi-Setti , "Trilobites: a photographic atlas. " Univ Chicago Press - 1975.
[7] aplanatic is called a lens with a socket so that all light rays coming from the same point when passing the lens will meet in one focus, without any distortion or aberration.
[8] ENK Clarkson, "Invertebrate Paleontology", Allen and Unwin, London, 1979.
[9] G. Rattray. op. cit. pg. 97 - 100c
Semogil June 13, 2010 - Feast of San Antonio de Padua.
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