September 22, 2005 | David F. Coppedge

Evolutionists Finally Figure Out the Eye – Well, Partly

As if tackling Darwin’s worst nightmare with gusto, evolutionary biologists published a paper in Current Biology1 about the evolution of the eye – at least the lens.  Though the paper is restricted to a discussion of genes involved in making the crystallin proteins that make up the lens, EurekAlert announced this as “Insight into our sight,” linking this paper to one of evolution’s biggest challenges:

The evolution of complex and physiologically remarkable structures such as the vertebrate eye has long been a focus of intrigue and theorizing by biologists.  In work reported this week in Current Biology, the evolutionary history of a critical eye protein has revealed a previously unrecognized relationship between certain components of vertebrate eyes and those of the more primitive light-sensing systems of invertebrates.  The findings help clarify our conceptual framework for understanding how the vertebrate eye, as we know it, has emerged over evolutionary time….
    Fish, frogs, birds and mammals all experience image-forming vision, thanks to the fact that their eyes all express crystallins and form a lens; however, the vertebrates’ nearest invertebrate relatives, such as sea squirts, have only simple eyes that detect light but are incapable of forming an image.  This has lead to the view that the lens evolved within the vertebrates early in vertebrate evolution, and it raises a long-standing question in evolutionary biology: How could a complex organ with such special physical properties have evolved? (Emphasis added in all quotes.)

The upshot of the paper by Shimeld et al. is that sea squirts have a gene that is similar to the one that codes for crystallin in the eyes of vertebrates.  In the sea squirt, it is only expressed in the palps and otoliths, near the ocellus that senses light without forming an image.  Since the same regulatory circuits that control the gene in the sea squirt also controls the gene that builds a lens in vertebrate eyes, the authors conclude that this gene must have been co-opted by the common ancestor of vertebrates to build a crystallin lens.  From the abstract,

The conservation of the regulatory hierarchy controlling beta-crystallin expression between organisms with and without a lens shows that the evolutionary origin of the lens was based on co-option of pre-existing regulatory circuits controlling the expression of a key structural gene in a primitive light-sensing system.

The team took the same regulatory genes that control crystallin production in the sea squirt and transferred them to a frog.  Those regulatory circuits were used by the frog to build its visual system, including the lens.  This was enough for EurekAlert to nearly declare that the problem of eye evolution, if not solved, is well on the way:

This strongly suggests that prior to the evolution of the lens, there was a regulatory link between two tiers of genes: those that would later become responsible for controlling lens development, and those that would help give the lens its special physical properties.  This combination of genes appears to have then been co-opted in an early vertebrate during the evolution of its visual system, giving rise to the lens.

Presumably, after a working lens emerged, the rest was just fine-tuning.

1Shimeld et al., “Urochordate Beta-Crystallin and the Evolutionary Origin of the Vertebrate Eye Lens,” Current Biology, Volume 15, Issue 18, 20 September 2005, pages 1684-1689.

Let us hope the highly-complex DNA-snipping protein emerged simultaneously (08/28/2003) to keep the lens from becoming opaque out of the factory, as well as mechanisms for stacking the crystallin cells and making them interlock, and supplying them with nutrients from the edges without blocking the light, rewiring the brain to receive and process the new sensory data, and a dozen other things that would make expression of raw crystallin useless to the unidentified, mythical “early vertebrate” that first decided to co-opt sea squirt technology.

A programmer wrote in and observed, “I can take code that performs the same or similar function and use it in a completely different program.  Sometimes I have to change things a little to make it work, sometimes virtually no changes are required.  That is economy of effort.”  Reusability does not demonstrate common ancestry without assuming it, nor does it explain the origin of the crystallin protein and the genes that regulate its expression.  He continued, “I can take 2 bicycle fenders, hammer them into one and make it into a motorcycle fender, but that doesn’t explain how the bicycle got to be a bicycle or how it got fenders.”

Co-option is just a fancy word for the Tinker Bell theory of evolution.  Evolution is a tinkerer, they tell us.  She cobs existing parts to build new things.  Aside from the gratuitous personification fallacy this commits, the idea requires that Tinker Bell be blind, dumb and indifferent.  In Darwinese, there is no teleology: Tinker Bell is not trying to invent an image-forming lens.  She flits from sea squirt to sea squirt with her mutation wand, zapping various individuals recklessly and carelessly.  It’s a lottery which sea squirt will find some benefit in the damage instead of dying from the genetic bomb.  Remember, no functional advantage, no natural selection – except the negative kind (Yikes! Eliminate this mutation before it kills us!).
    Can we get real?  One girder hanging over the canyon does not make a bridge (05/22/2002 commentary).  There is no smoothly graded sequence of transitional forms.  Whenever an organism is suggested as a primitive ancestor, as in the case of the box jellyfish (see 05/13/2005 entry), closer inspection shows the organism has eyes perfectly suited for its habitat and lifestyle.  Each visual system is too different from those of other organisms, and too complex to imagine having evolved on its own.  So the follow-up question to the EurekAlert Darwinist propaganda celebration is, where are science reporters exercising freedom of the press, freedom of conscience and critical thinking skills?  Keep reading.

(Visited 10 times, 1 visits today)

Leave a Reply

This site uses Akismet to reduce spam. Learn how your comment data is processed.