October 29, 2004 | David F. Coppedge

“Evolution Stories Are Subtle and Complex” – Truth or Euphemism?

A worm brain has photoreceptors similar to those in humans.  What does it mean?  Elizabeth Pennisi in Science1 sets the stage, commenting on work by Arendt et al. in the same issue,2 “Ciliary Photoreceptors with a Vertebrate-Type Opsin in an Invertebrate Brain.”  One might think this demonstrates common ancestry, but Pennisi explains that it’s not a simple evolutionary story:

Despite incredible variation in size and shape, eyes come in just two basic models.  The vertebrates’ photoreceptor cells, typified by rods and cones, are quite distinctive from the invertebrates’.  And although both use light-sensing pigments called opsins, the opsins are quite different in their amino acid makeup.
    For years biologists have argued about how these varied components came to be.  Some insist that eyes evolved only once, despite this modern difference.  Others have argued that optical structures evolved at least once in invertebrates and again in vertebrates.
    New data showing unexpected similarities between photoreceptors of a marine worm and humans add a new twist to this debate.  Detlev Arendt and Joachim Wittbrodt, developmental biologists at the European Molecular Biology Laboratory (EMBL) in Heidelberg, Germany, and their colleagues have found that in addition to its regular opsin pigment, the worm contains another one almost identical to the human’s.  Their finding suggests that even the earliest animals had the makings of both vertebrate and invertebrate visual systems, and that some of the photoreceptor cells in the invertebrate brain were transformed over a series of steps into vertebrate eyes.  Although some researchers are skeptical, others think the data are sound….

The research team thinks this “sheds new light on vertebrate eye evolution,” but the problem is that it pushes the origin of sight, a complex interaction of multiple functional parts, even farther back in time.  Another problem is that the human-like opsin in the worm has been conserved (unevolved) for 500 million years, according to the standard evolutionary time scale:

Arendt and Wittbrodt jumped into the fray over eye evolution after Arendt noticed some odd cells in the brains of ragworms, a relic marine annelid species that’s been relatively unchanged for the past 500 million years.  “We were surprised,” Arendt recalls, as these cells looked very much like rods and cones.

Further molecular and genetic studies showed that “Not only the morphology [outward appearance] but also the molecular biology of the two types of receptors was already set in our common ancestor”, according to a French biologist.  To put this new discovery into an evolutionary context, Arendt et al. had to invent a hypothetical ancestor even further back in time from the hypothetical ancestor of vertebrates and invertebrates, dubbed Urbilateria: 

They go further to suggest that the two types likely arose in a predecessor of Urbilateria.  In that organism, they speculate, the gene for one opsin and the genes to build the one type of photoreceptor cell were duplicated.  The extra set of genes might have evolved into a different visual system: “We think both photoreceptor cells track back to one cell type,” [Joachim] Wittbrodt [one of the authors of the paper] says.

As the authors put it in conclusion, “The vertebrate eye thus represents a composite structure, combining distinct types of light-sensitive cells with independent evolutionary histories”.  So although this proposal seems to favor those who argue for the single origin of eyes, it illustrates that “evolution stories are subtle and complex.


1Elizabeth Pennisi, “Worm’s Light-Sensing Proteins Suggest Eye’s Single Origin,” Science, Vol 306, Issue 5697, 796-797, 29 October 2004, [DOI: 10.1126/science.306.5697.796a].
2Arendt et al., “Ciliary Photoreceptors with a Vertebrate-Type Opsin in an Invertebrate Brain,” Science, Vol 306, Issue 5697, 869-871, 29 October 2004, [DOI: 10.1126/science.1099955].

“A likely story” can have opposite meanings depending on the tone of voice.  Is the phrase, “subtle and complex” descriptive of a truth, or a euphemism for a dodge?  Suppose you were a teacher, and your student’s story about the origin of his term paper, which was clearly a hodgepodge of plagiarisms from several internet sources, he described as “subtle and complex.”  Suppose a politician described his flipflops over the years as being subtle and complex.  Suppose your husband’s disastrous room addition project was defended with a story he said was subtle and complex.  One thing is clear about this evolutionary story, as admitted by Pennisi: it is not simple and straightforward.
  The PBS Evolution series tried to claim in 2001 that the eye followed a simple and straightforward progression from simple to complex, using the visual power of suggestion that a series of pictures of animal eyes in a progression from apparently simple to complex suggested an ancestral relationship.  Evolutionists love the word “suggest”.  Scattered similarities between distant organisms, all thriving in their own environments, all using highly-complex functional systems only “suggest” an evolutionary story when you have put yourself under Charlie’s spell and have opened yourself up to the power of suggestion.  Snap out of it.
    Read this evolutionary story with the wide-awake understanding that opsins are very complex proteins (see 10/01/2004 headline and Michael Behe’s Darwin’s Black Box, pp. 15-25).  But their complexity alone is useless without even more complex organs and neurons that can interpret their responses.  Evolutionists want to hypnotize us into the suggestion that stories relating worms to humans by common ancestry are scientific.  Be a clear-headed judge of the evidence.  When missing links have to be invented out of thin air, and when complex functions have to be presumed to have “arisen” [a miracle word] earlier than previously believed, the burden of proof is on the storyteller that the statement, “evolution stories are subtle and complex,” is not just pulling wool over the eyes. 

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Categories: Terrestrial Zoology

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