Butterfly Patterns: Convergent Evolution or Design?
Some butterflies are expert mimics of other species. Evolutionists call this "convergent evolution." Recently a single gene was found responsible for the red colors in one genus. Does this strengthen the case for convergent evolution, or any kind of evolution? As usual, what is left unexplained is far more important.
Members of the Heloconius genus of butterflies (also called passion-vine butterflies) are renowned for the brilliant red patterns on their wings. Some of them can even mimic members of other genera that are toxic, using the color to warn predators. The remarkably similar patterns in unrelated species has led some evolutionists to explain it with the phrase "convergent evolution" -- the notion that natural selection somehow hit on the same solution to a problem more than once. Their explanation was strengthened by a recent discovery that a single gene is responsible for these patterns. But is it really evolution, convergent or otherwise?
Robert Reed of the University of California at Irvine, and a team of other biologists, spent a decade studying Heloconius butterflies. They finally isolated a single gene named Optix that is expressed in the red parts of the wings. Interestingly, this same gene is responsible for eye development in other insects. Publishing in Science,1 they said, "Our results show that the cis-regulatory evolution of a single transcription factor can repeatedly drive the convergent evolution of complex color patterns in distantly related species, thus blurring the distinction between convergence and homology." The findings were summarized in PhysOrg and Science Daily accompanied by photos of the flamboyant red wings.
While this is an important finding, it raises other questions about evolution. In fact, the press release from the Smithsonian Tropical Research Institute, reproduced by PhysOrg, said as much: "How the optix gene codes for wing color raises a host of new questions." How, for instance, are the patterns formed in the first place? Identifying a gene that is active at a certain spot on a wing does not explain why it is expressed there, and in neighboring sites, to produce patterns. That would be like claiming that the identification of a red pigment in six paintings by Raphael explains the artwork.
Reed vascillated between confidence and confusion about what his team had found. For one thing, "Blurring the distinction between convergence and homology" raises questions about both. Which is which? And for whatever the team found about the "how," the "why" is as mysterious as ever. Science Daily quoted Reed saying, "This is a beautiful example of how a single gene can control the evolution of complex patterns in nature. Now we want to understand why: What is it about this one gene in particular that makes it so good at driving rapid evolution?"
Certainly the butterfly had nothing to say about it. A gene can no more "drive rapid evolution" than a butterfly engineering design committee could. Natural selection by definition is unguided and blind. It may act to preserve a species that already existed with the correct pattern to imitate a toxic species, but it does not explain the emergence itself. Intelligent design, by contrast, could account for innate variability that allows designed organisms to adapt to changing environments. We see, therefore, that the phrase "convergent evolution" is little more than a vacuous explanation that assumes evolution without explaining how or why the beautiful patterns exist.
Science articles sometimes try to impress people with the power of evolutionary explanations. Explaining the expression of an already-existing gene in a wing is trivial compared to the overpowering difficulty for Darwin of explaining metamorphosis -- the progression of four body plans, from egg to caterpillar to chrysalis to adult flying insect. Why this sequence trumps neo-Darwinism and affirms intelligent design is explained fully in the beautiful new documentary Metamorphosis from Illustra Media.
1. Reed et al., "Optix Drives the Repeated Convergent Evolution of Butterfly Wing Pattern Mimicry," Science, published online July 21, 2011; DOI: 10.1126/science.1208227.
To learn more about butterflies and the evidence they reveal for intelligent design, visit Metamorphosisthefilm.com, where you can order this outstanding film, now available in Blu-Ray.
Heloconius photos courtesy Illustra Media.