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Thread: Evolution (and randomness)

  1. #11
    Gotta catch you all! Array Blackmail!'s Avatar
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    Mar 2008


    Actually, there is a fact that proves our eyes weren't "designed" at all, because they are far from being perfect. Their design contains many oddities or absurd details we inherited through evolution, but they weren't removed because they weren't impairing enough.

    For instance, there is a layer of cells in front of the retina. Octopi eyes don't have this defect, they are better constructed than mammal ones.

    Quote Originally Posted by nozflubber View Post
    I don't think complexity starts with new mutations - it HAS to begin small and subtle for reasons you stated. Basically, somewhere along the line a biological mutation was made in cells that made those particular cells react/sensitive to different forms of electro magnetic radiotion.
    The way we react to light is indeed quite simple. When some proteins called photopsins intercept even a very small amount of energy like a photon, they turn into a more energetic isomer. This process is called photoisomerization. A few moments later, when the extra-energy dissipates, they return to their primary form.

    Rods cells are in fact made of several disks stacked up together, each covered with these proteins (here rhodopsins). The more light, the deeper it gets into the cell, and thus the more disks are eventually affected. Hence, the rod cell transmits a signal that is conveyed to the brain as a single pixel whose grayness vary according to the amount of light.

    Cones cells perceive colours. They are also made of several disks stacked up together, but of increasing diameters, hence the "cone" shape. The light here is diffracted like in a prism, since the goal is colour recognition. Again, the more disks touched by light, the more intense the primary colour will be (whether the cell is configured to recognize blue, red or green wavelengths: you have three variants ; and the cone angle and geometry will be slightly different each time, because the required diffraction won't be the same).

    And after that, the brain processes all the pixels together: first, a black and white image (rod cells) that gives great acuity and precision, and just after that it "paints" it with the informations received by the blue, the red and the green layers (cone cells, which are less numerous and less efficient than rod cells)...

    So you see, when you consider each phase separately, the mechanisms used in our eyes use simple chemical and optical properties, nothing really fanciful!
    "A man who only drinks water has a secret to hide from his fellow-men" -Baudelaire

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  2. #12


    I think we are wrong to put so much emphasis on random mutation though. Even Darwin recognised sexual selection, which amounts to selective breeding. Interference from religion pushers obstructs the very serious problems with simple 'Darwinism' by making the intelligent defend that before they dare to question it. It's always possible that the Cosmos is evolving as an entirety and therefore influences specific evolutionary trends.

    Certainly Darwin was a man of his time who believed that the sum is no greater than its parts and all composites could be explained from the bottom up by their simplest components' actions. We now think in terms of ecological systems and evolutionary theory should take more account of Lamarckian influences operating through feedback as whole environments develop as a unity, not as haphazard individualitie happening to come together.

    I don't believe there is one single Theory of Evolution Many influences go into evolution. Some of them almost support the concept of a Designer (though I'm inclined to a Cosmos that evolves and deigns itself as it goes along - the way it has evolved determines the way it will evolve). Many genes lie dormant for millions of years before a mutation allos them activation. If Creationists were not so stupid, they would use this as a powerful argumetnt to say that millions of years ago, God anticipated future conditions and provided a gene for them.

    Not that I believe that - the gene happened to be there and might never have been activated, Somewhere in our junk DNA there might be genes to allow us to drink seawater and eat sand in a radioactive world. We'll never know unless that happens and the few whose mutation switches them on survive.

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