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Re: the advanced trilobite schizochroal eye is the original!

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  • Stephen E. Jones
    Group In researching an assignment on trilobites, I have just realised that Darwinists have an even greater problem with the trilobite schizochroal eye (that
    Message 1 of 1 , Sep 1, 2002
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      Group

      In researching an assignment on trilobites, I have just realised that
      Darwinists have an even greater problem with the trilobite schizochroal eye
      (that is the advanced one-the "fiendishly clever" one:

      "Euan noticed something else about the construction of the
      trilobite's eyes: the smaller lenses were concentrated at the top of
      many eyes. The eye surface - known as the corneal surface had to
      be moulted along with the rest of the animal's hard exoskeleton as it
      grew. The eye itself grew in size in harmony with the rest of the
      animal: more lenses were added after each moult as the new
      skeleton hardened. New crystals were added in from the top of the
      eye in a zone of generation. With successive moults these lenses
      were incorporated into the main body of the eye, passed
      downwards in a graded chain. These differences in lens size also
      helped to maintain the regularity of the design across the curved
      surface of the eye. It is fiendishly clever (as Hercule Poirot would
      to say) that these 'primitive' animals could play such games with the
      mineral world in the service of eye geometry." (Fortey R.A.,
      "Trilobite!: Eyewitness to Evolution," [2000], Flamingo: London,
      2001, reprint, p.97)

      the "sports coupe in the age of the boneshaker" one-see tagline), as opposed
      to the holochroal eye which itself is highly sophisticated.

      The problem for Darwinists is that it turns out that the schizochroal eye is the
      *original* trilobite eye because "The eyes of immature holochroal Cambrian
      trilobites were basically miniature schizochroal eyes":

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      http://www.aloha.net/~smgon/eyes.htm [...]
      How did schizochroal eyes evolve? All early trilobites (Cambrian), had
      holochroal eyes and it would seem hard to evolve the distinctive
      phacopid schizochroal eye from this form. The answer is thought to lie
      in ontogenetic (developmental) processes on an evolutionary time
      scale. Paedomorphosis is the retention of ancestral juvenile
      characteristics into adulthood in the descendent. Paedomorphosis can
      occur three ways: Progenesis (early sexual maturation in an otherwise
      juvenile body), Neoteny (reduced rate of morphological development),
      and Post-displacement (delayed growth of certain structures relative to
      others). The development of schizochroal eyes in phacopid trilobites is
      a good example of post-displacement paedomorphosis. The eyes of
      immature holochroal Cambrian trilobites were basically miniature
      schizochroal eyes. In Phacopida, these were retained, via delayed
      growth of these immature structures (post-displacement), into the adult
      form. [...]
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      So what we have here is a highly advanced optical system (arguable the
      most advanced ever) which arose in the Cambrian Explosion with the
      original trilobite eyes!

      There is a lot more to than meets the eye (pun intended!) but I don't have
      time to go into it now (I am after all supposed to be doing the assignment! :-(.

      But this quote from Taylor an agnostic engineer, should give a feeling for
      the problem:

      "Let us start, not with the eyes of vertebrates or of insects, but with
      the sophisticated eyes of trilobites and shrimps, already in existence
      when the first crustacean fossils were formed more than half a
      billion years ago. It was the first use of optics in combination with
      sensory perception in nature and, for my money, the most incredible
      event in the history of evolution. The trilobites were the first highly
      organised animals to populate the primordial seas and they were
      everywhere. The first trilobite fossils known come from the early
      Cambrian: they are already highly evolved so that the first trilobites
      must have emerged very much earlier. .... The eye of arthropods, I
      must explain, is built on a totally different plan from the human or
      even the reptilian eye. It consists of closely packed columns, each
      with its own lens at the top and its photoreceptor at the bottom, the
      whole protected by a cornea. They are known as ommatidia. The
      columns are not quite parallel but are fanned out, so that each
      points at a different part of the horizon. The trilobite eye was the
      first based on this plan. In later trilobites the eyes were in addition
      sometimes raised like turrets, or wrapped around the body until
      they nearly met, thus giving an all-round view. ....

      The marvel of the trilobite eye became apparent only in 1973, when
      Kenneth Towe of the Smithsonian Institute reported that the lenses
      in the eyes of fossil trilobites consisted of precisely aligned crystals
      of calcite. Mounting carefully prepared fossil eyes on the
      microscope, he found that they produced a sharp image at distances
      ranging from a few millimetres to infinity, without further focusing.
      Up to this time paleontologists had always assumed that the calcite
      crystals were a relic of the mineralisation process which had
      preserved the whole carcass - but in that case the arrangement of
      crystals would have been random. Now, calcite crystals transmit
      light with the transparency of glass only if they are exactly aligned
      with the beam of light entering them. At any other angle, the light
      bounces off the walls and splits into various colours. Some modern
      arthropods have calcite crystals in their eyes, but these- and Towe
      finds this 'an altogether surprising thing' - are arranged randomly,
      and do not correspond with the ommatidia or optical units of which
      the compound eye is composed. By what mechanism did these
      'primitive' creatures discover how to incorporate calcite crystals,
      align them precisely and protect them with a cornea? Answer comes
      there none.

      But that is only half the story of the trilobite eye. The second half
      likewise started in 1973 when Chicago University's Dr Riccardo
      LeviSetti met Edinburgh's Dr E. N. K. Clarkson at the Oslo
      International Conference on Trilobites. As far back as 1901 a
      Swedish worker had commented on the peculiar substructure of the
      more evolved trilobite eyes. In 1968 Dr Clarkson began to
      investigate this structure with techniques, such as the scanning
      electron microscope, which had not hitherto been available to
      zoologists. He found that the lens of these eyes was a doublet: an
      upper part of calcite separated by a wavy boundary from a lower
      half of chitin. After Levi-Setti had delivered his lecture on the
      amazing lightcollecting properties of the trilobite eye, he had coffee
      with Clarkson, who told him of his work. Levi-Setti at once had a
      hunch that this doublet structure must represent some form of
      optical correction Armed with sketches made on the paper napkins
      of the canteen, he returned to Chicago, where he brooded over the
      problem. One day reading that bible of all students of vision, the
      Traite de la Lumiere of Christian Huyghens, published in 1690, he
      found the description of an aplanatic or spherically corrected lens
      'which resembled unmistakably the wavy shape seen in Clarkson's
      sketches'. Huyghens' mention of some earlier results by Descartes
      led him to peruse the latter's La Geometrie, published in 1637.
      'There I found a second construction somewhat different from that
      of Huyghens, but designed to perform the same function. This
      matched a second version of the trilobite lens-shapes described by
      Clarkson. Armed with the conviction that trilobites had solved a
      very elegant physical problem and apparently knew about Fermat's
      principle, Abbe's sine law, Snell's laws of refraction, and the optics
      of birefringent crystals I set out to inform Dr Clarkson of the
      meaning of his trilobites' lensshapes.' Thus the trilobites evolved a
      lens shaped to correct for optical aberration identical to that
      proposed (quite independently of any knowledge of trilobites) by
      Descartes and Huyghens half a billion years later. Why was such
      perfection needed? Dr Clarkson suggests that trilobites may have
      lived in very muddy, turbid water. Or perhaps they only came out at
      night or at dusk. The thick lenses, thanks to the optical correction,
      would be more efficient light-collectors. But to make the matter
      more puzzling still there is the fact that some trilobites were blind.

      How did the earliest trilobites collect together the intricate genetic
      information needed to construct this semi-miraculous structure?" ...
      One could perhaps accept the idea that a happy accident caused the
      sensitive spots to become more numerous, and that another happy
      accident placed them at the bottom of tubes. It is a little harder to
      accept that by chance the tubes were not parallel, which would have
      been the obvious pattern of repetition, but were slightly divergent.
      But by what conceivable chance could the trilobite have
      accumulated the one material in the universe- namely calcite -
      which had the required optical properties and then imposed on it
      the one type of curved surface which would achieve the required
      result? There are innumerable possible shapes, none of which offer
      the unique advantage of spherical correction, except the one I have
      described. Now if anything were needed to cap this evolutionary
      feat it is the fact that the refractive index of calcite and of chitin are
      precisely those needed to produce an aplanatic lens."

      (Taylor G.R., "The Great Evolution Mystery," [1983], Abacus:
      London, 1984, reprint, pp.95-98)

      Steve

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      "The optical arrangement is clearly a very sophisticated structure which
      quite belies the antiquity of the animal. This may come as something of a
      surprise: we might expect an eye from half-way along optical history to
      have a slightly slung-together look, or at least broadly to resemble the eyes
      of many other lowly animals, as does the run-of-the-mill trilobite eye. But
      the eye of Phacops is something unexpected, a sports coupe in the age of
      the boneshaker." (Fortey R.A., "Trilobite!: Eyewitness to Evolution,"
      [2000], Flamingo: London, 2001, reprint, pp.98,100)
      Stephen E. Jones sejones@... or senojes@...
      Home: http://members.iinet.net.au/~sejones
      Group: http://groups.yahoo.com/group/CreationEvolutionDesign
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