June 26, 2010 | David F. Coppedge

Fish Feet: Can Evolution Add by Subtraction?

How did fish grow feet?  One would think that feet require adding a lot of new parts: bones, muscles, nerves, blood vessels, and additional supporting tissues.  Each of those would require genetic instructions and changes to embryonic development.  One evolutionist, however, feels that switching genes off paved the way to the invasion of land.  The story was told on PhysOrg and the BBC News.
    PhysOrg stated matter-of-factly, “Fossil evidence suggests that around 365 million years ago, fish, or fish-like creatures, emerged from shallow seas, moving onto land with the help of primitive, eight-fingered limbs, which later simplified to five digits under evolutionary pressure.”  Victoria Gill said for the BBC, “Fin to limb evolution clue found.”  What kind of clue?  Marie-Andree Akimenko, from the University of Ottawa in Canada, discovered two genes that are not found in animals possessing feet.  These genes create ray-forming fibers in the fins of fish.  When the genes were knocked out of zebrafish, the fin rays did not develop.  Moreover, she did not find the genes in mice embryos.  Akimenko surmised that a necessary step in the evolution of limbs from fins was the subtraction of these genes.  That would get rid of the fibers, and allow the emergence of bones, digits, and feet: “The loss of these fin rays, the scientists say, was a key step in fin-to-limb evolution.
    The BBC article quoted John Bard, a retired Oxford biologist.  He thought the work was interesting, but only a small part of the story.  He did not think it explained “how the broad, multi-ray fins of fishes became transformed into the eight digits of the hand or foot plate of the first tetrapods.”  Besides, he said, hundreds of millions of years separate fish and mice.  The PhysOrg article ended, “Further work is needed to confirm the theory, as it is unclear whether the fin genes were knocked out to help make the transition to land – or whether they were eliminated after the transition, as they were no longer needed.”  The BBC was certain, nevertheless, that this is an ongoing part of the Darwin Enlightenment: “A study has shed light on a key genetic step in the evolution of animals’ limbs from the fins of fish, scientists say.”

This scientist feels that for Darwin to build a complex new organ, all that is needed is paving the way.  It would be like building a shopping center by sending in the bulldozers.  Is that how evolution works?  Keep subtracting genes from an already complex animal, and maybe something wonderful will “emerge” from the empty space.
    The usual other fallacies are present here: (1) Dodging with passive voice verbs: “whether the fin genes were knocked out to help make the transition” (who knocked them out?).  (2) Personification: “to help make the transition” (who was the foreman of this project?).  (3) Composite explanations: “whether… the genes were knocked out to help make the transition… or whether they were eliminated after the transition” (which is it?).  (4) Making “evolutionary pressure” a creative force; and (5) Promissory notes: Escaping responsibility by saying, “Further work is needed to confirm the theory.”  Did anyone call this a theory?  Aren’t the Darwinians the very ones who insist that a theory is a well-tested hypothesis that has stood the test of time and become widely accepted?  It appears that anyone can toss out a “suggestion” or fairy tale and grace it with the honorable word theory.
    Since the Darwinians love to raise zebrafish, let them pursue this line of experiment.  Keep knocking out genes and see what emerges.  Subtract enough genetic information, and a Darwin theorist can’t be far behind.

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