January 8, 2008 | David F. Coppedge

Blind Cave Fish Can See Again

Can blind cave fish get their lost eyes back?  Yes, if they hybridize with other cave fish that lost them due to different mutations.  An article on Science Daily described experiments at New York University that showed that the progeny of two independent cave populations could have fully functioning eyes.  Why?  Because “the genetic deficiencies in one lineage are compensated for by strengths in the other, and vice-versa.”
    Nearly 40 percent of the progeny from their crossing experiments could see again, even though the scientists believe the fish populations had independently lost their vision a million years ago.  Getting back functioning eyesight means that not only the eyeballs came back, but “all the connections to the brain for proper processing of information not used for that enormous length of time are restored.
    Professor Richard Borowsky at NYU, who published his research in Current Biology,1 attributed this to evolution.  “Evolution has many ways to accomplish the same end result, which in the case of cave fish is blindness.”  Yet loss of function is not the same as gaining functional eyes in the first place.  The loss of sight was apparently due to non-overlapping mutations in the two populations.  The same was true for loss of pigment.  National Geographic’s report on the regeneration of sight in blind cave fish began, “It’s a miracle!”  Borowsky calmly stated, “Evolution’s palette is varied.”

1.  Richard Borowsky, “Restoring sight in blind cavefish,” Current Biology, Volume 18, Issue 1, 8 January 2008, Pages R23-R24.

There are a hundred ways to break a car, but only one way to build it: intelligent design.  Attributing blindness to evolution is like attributing a car crash to Ford.  (On second thought, maybe we had better say BMW.)
    Getting a broken car back into working condition by blending parts from two broken cars also takes intelligent design.  The Creator put built-in redundancy into pairs of chromosomes, and scattered the functionality across genes to reduce the probability of a single point of failure.  In the cave environment, the usefulness of eyes and pigment was lost.  This suggests that functioning organs involve a cost that is burdensome when the benefit is gone (see 02/16/2007).
    Natural selection can jettison useless baggage.  That premise is not controversial even among staunch creationists.  A television set is a nice benefit unless you are a hiker trying to carry one through a snowstorm.  Getting eyes back without the input of complex specified information, or getting a new TV to emerge from the snow, is a completely different claim.  Creationists might ask an additional question that did not occur to these researchers.  How plausible is it that useless but costly genetic information was retained for a million years, only to become fully functional again in one generation?
    The only way these fish were able to see again was that the genetic information for eyes and all the brain wiring was available in the union of data sets from the two populations, and could be reconstructed by the elaborate quality control mechanisms designed into development.  The 40% who could see were the lucky ones who got all the information in their zygotes.
    To call this evolution, let’s see them experiment with one blind population, and find out whether functioning eyesight, complete with all the brain wiring, emerges from scratch via genetic mutations alone.  Darwin is good at breaking things, not designing them.  Random mutation is the way an eye goes blind – and a Mercedes bends.

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Categories: Genetics

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