Odd Fish Find Contradicts Intelligent-Design Argument
for National Geographic News
July 9, 2008
The discovery of a missing link in the evolution of bizarre flatfishes—each of which has both eyes on the same side of its head—could give intelligent design advocates a sinking feeling.
CT scans of 50-million-year-old fossils have revealed an intermediate species between primitive flatfishes (with eyes on both sides of their heads) and the modern, lopsided versions, which include sole, flounder, and halibut.
So the change happened gradually, in a way consistent with evolution via natural selection—not suddenly, as researchers once had little choice but to believe, the authors of the new study say.
The longstanding gap in the flatfish fossil record has long been explained by a "hopeful monster"—scientific jargon for an unknown animal blessed with a severe but helpful mutation that was passed down to its descendants.
Ever since a geneticist invoked the hopeful-monster explanation in the 1930s, it has been the conventional wisdom for the origin of modern flatfishes.
Intelligent design advocates have seized on the idea of instant flatfish rearrangement as evidence of God or another higher being intentionally creating new animal forms. (Also see: "Does 'Intelligent Design' Threaten the Definition of Science?" [April 27, 2005].)
Intelligent design advocates often cite the relative scarcity of transitional species in the fossil record as evidence of the intentional creation of species.
Lee James Best, Jr., for example, wrote in his 2003 book, God and Fallacy in the Theory of Evolution, that neither the flounder itself nor "unplanned environmental pressures" caused the change.
"As with aimless squeezing of wet clay, without a mold or other purposeful directed pressures," he wrote, "an intended end to a construction project would not occur."
The new discovery, however, is unlikely to change the minds of many creationists.
Zoologist Frank Sherwin, science editor for the Institute for Creation Research, called the findings "underwhelming."
"We do not deny that there is minor variation that occurs within created groups or kinds," he said, adding that he fails to see the new paper as evidence of a progression from one flatfish form to another.
"Fish have always been fish, all the way down to the lower Cambrian [roughly 542 to 488 million years ago]," he added.
"We have no problem with the variation within flatfish. What we're asking is, Show me how a fish came from a nonfish ancestor."
Part of the argument is that the asymmetrical eye configuration can easily be seen as intelligent, because it is advantageous to flatfish survival.
The feature allows flatfishes to use both of their eyes to look up when lying on the seafloor—part of a suite of adaptations that includes a "top" side camouflaged to fit the fishes' surroundings.