August 15, 2007 | David F. Coppedge

Stupid Evolution Quote of the Week: Shark Chefs and Finger Food

A press release from University of Florida wins this week’s prize for trying to make dogmatism funny (or at least appealing to snackers):

When the first four-legged animals sprouted fingers and toes, they took an ancient genetic recipe and simply extended the cooking time, say University of Florida scientists writing in Wednesday’s issue of the journal PLoS ONE.
    Even sharks – which have existed for more than half a billion years – have the recipe for fingers in their genetic cookbook – not to eat them, but to grow them.

But sharks don’t have fingers, you say?  Right; they just had the recipe but never used it: “the genetic processes necessary to muster fingers and toes existed more than 500 million years ago in the common ancestor of fish with cartilaginous skeletons and bony fish – more than 135 million years before digits debuted in the earliest limbed animals,” the article says.
    And what were these finger genes doing 135 million years before they were used?  Just making fins, apparently.  “…sharks and many other types of fish do not form more dramatic appendages during this late phase of Hox gene expression because it occurs briefly and only in a narrow band of cells, compared with the more extended time frame and larger anatomical area needed to prefigure the hand and foot in limbed animals.”
    So for 135 million years, no animal ever tried the latent innovation.  But when it was time for fingers and toes to debut, their appearance was “an extremely dramatic, important point in evolution that has captured the interest of many.”  Otherwise we would be playing finball instead of handball.
    “The finding shows what was thought to be a relatively recent evolutionary innovation existed eons earlier than previously believed,” the article says.  The following paragraph makes it all so plausible:

“We’ve uncovered a surprising degree of genetic complexity in place at an early point in the evolution of appendages,” said developmental biologist Martin Cohn, an associate professor with the UF departments of zoology and anatomy and cell biology and a member of the UF Genetics Institute.  “Genetic processes were not simple in early aquatic vertebrates only to become more complex as the animals adapted to terrestrial living.  They were complex from the outset.  Some major evolutionary innovations, like digits at the end of limbs, may have been achieved by prolonging the activity of a genetic program that existed in a common ancestor of sharks and bony fishes.”

Question: What was the observation that gave rise to all this kitchen prose?  Scientists at UFL watched the pattern of expression in Hox genes in living sharks, and “discovered a phase of gene expression in sharks that was thought until recently to occur only when digits began to form in limbed animals.”  Well, then, (snap fingers): evolution is the only possible explanation.

It’s the only possible answer because it is the only answer the Darwin Party will allow in the arena, which has become a circus.  Let’s all do Steve Martin’s rendition of “When the shark bites…” while re-reading the quote at top right of this page.
Update: National Geographic was quick to join the feeding frenzy.  “The discovery pushes back the date of the evolutionary ‘fin to limb’ advance by some 135 million years,” the article said.  Which quote do you think should win?  The one above or this one by Marcus C. Davis?

Dramatically different ways of being—new forms, new functionsmay evolve through relatively minor adjustments to existing genes and gene functions,” Davis said.
    “It only requires modifications—‘tweaks’—if you will, to previously existing genetic systems,” he said.
    “A symphony can play dramatically different compositions by changing the role each musician plays, [but] only on occasion are instruments added or lost.”

And here you thought all along that symphonies were played by intelligent design.  Not this one.  It’s Darwin’s overture to his comic opera Farcical, dopus 135M, starring the fat lady who always sings last, Tinker Bell.

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