Creationism in Crisis - Another One in the Eye For Intelligent Design Creationists

Creationism in Crisis

Another One in the Eye For Intelligent Design Creationists

Credit: Jenessa Daugherty

Eye-opening Origin Story: Scientists Trace Key Innovation in Our Camera-like Vision to Bacteria

A discovery by scientists at the University of California San Diego School of Biological Science has scuppered yet another creationist fallacy, usually backup up by a blatant misrepresentation of what Darwin actually said (as though that matters anyway).

Creationists like to try to fool their dupes with the lie that Darwin admitted that the eye could not be explained by evolution, as though Darwin was a secret intelligent design creationist who let it slip in a book he wrote, and repeated that blunder in several editions. The quote you'll often see attributed to Darwin is:

To suppose that the eye with all its inimitable contrivances for adjusting the focus to different distances, for admitting different amounts of light, and for the correction of spherical and chromatic aberration, could have been formed by natural selection, seems, I freely confess, absurd in the highest possible degree.

But Darwin, in typical style, was merely setting out the problem before giving the solution. What you'll never see posted by a creationist is the full quote, which continues:

Yet reason tells me, that if numerous gradations from a simple and imperfect eye to one complex and perfect can be shown to exist, each grade being useful to its possessor, as is certainly the case; if further, the eye ever varies and the variations be inherited, as is likewise certainly the case; and if such variations should be useful to any animal under changing conditions of life, then the difficulty of believing that a perfect and complex eye could be formed by natural selection, though insuperable by our imagination, can hardly be considered real.

Charles Darwin, “On the Origin of Species by Means of Natural Selection, or the Preservation of Favoured Races in the Struggle for Life," first edition (1859). Chapter 6, "Difficulties on Theory", page 187, 6th edition, page 217.

Since then, numerous experiments have shown how a patch of light-sensitive cells will quickly evolve into a functional eye if there is a benefit to each step. In other words, Darwinian gradualism perfectly explains the evolution of the eye.

Stages in the evolution of the vertebrate eye

All that remains to explain is the evolution of light-sensitive cells.

And this was done by the University of California San Diego team, who show that mammals acquired light-sensitivity, in a way that also refutes another creationist lie.

They acquired it by horizontal gene transfer. Horizontal gene transfer is the way genes can cross from one taxon to another, giving the lie to creationists dogma which states that new information can only arise withing a genome with the assistance of a magic designer.

The team have shown that the protein needed by cells to respond to light comes from simple bacteria, and, because it is not present in other vertebrates, but have entered the genome of the last common ancestor of mammals.
The University of California, San Diego news release explains the research:

Humans and other organisms with backbones come equipped with an evolutionary marvel: eyes that function like cameras to provide a finely tuned visual system. Due to its complexity, Charles Darwin described the eye as one of the greatest potential challenges to his theory of natural selection through incremental evolutionary steps.

A notable difference between vertebrate and invertebrate vision is rooted in a unique protein responsible for the specialization of cells that are critical for vision. Mutations in the protein, called the have been known to cause a variety of diseases such as retinitis pigmentosa, but its evolutionary origin has remained elusive with no obvious genetic precursor.

Scientists in the University of California San Diego School of Biological Sciences, publishing in the Proceedings of the National Academy of Sciences, have now traced the 500 million-year-old origin of vertebrate IRBP to a bacterial source. Their discovery, using phylogenetic reconstruction methods, was made possible because of the growing number of fully detailed genomes now available. Their analysis of more than 900 genomes across the tree of life revealed that the IRBP integration in vertebrate eyes was not the result of traditional vertical gene transfer, in which an evolutionary advancement is adapted, or “tinkered with” using available genetic material. Rather, the IRBP was acquired, duplicated and integrated through horizontal gene transfer from foreign bacterial genes.

It’s a massive shift because this is an entirely new piece of genetic material that’s been introduced from bacteria.

In order to see in different wavelengths, there needs to be enough light around and that’s one of the arguments for why we can see in the dark really well—we have this enzymatic recycling system that many invertebrates don’t seem to have. Eyes are diverse and complicated, and we’ve gone down this path because of this system.

This reshapes the way that we think about evolution and the way we think about complex structures that seem like they’ve emerged out of nowhere,

,Professor Matthew D. Daugherty, senior author.
Department of Molecular Biology
University of California, San Diego, La Jolla, C., USA

Researchers compared the structure of vertebrate IRBP (blue) with a predicted structure of a similar gene in bacteria.

A schematic of the vertebrate visual cycle highlighting the physical separation of light sensing.

Biological Sciences Associate Former UC San Diego undergraduate student Chinmay Kalluraya led the study, and UC San Diego graduate students Alexander Weitzel and Brian Tsu contributed computational expertise. “This study shows that a major innovation that distinguishes vertebrate eyes from all the rest of the eyes out there wasn’t done by molecular tinkering but rather a big leap of genetic innovation.”

Once the key gene that eventually became IRBP was acquired from bacteria, a new door opened in vertebrates that allowed retinoids, molecules in the eye that directly sense light, to be shuttled between cell types to efficiently recycle it for further light sensing. This separation of photoreception, or light sensing, and retinoid recycling provides unique functionality to vertebrates and the way they can see.

With more genomes from more organisms becoming available, the researchers believe that other critical functions and systems will similarly trace their roots to bacteria.

What Creationists will hate about this research is that it not only weakens their lie about Darwin's supposed admission about the evolution of the eye being impossible to explain, but it also shows that the basic condition for the eye to begin to evolve in the first place - light-sensitive cells - has a perfectly natural explanation. An explanation moreover that refutes another of their traditional lies - that new information in a genome requires a magic creator because it can't happen naturally. Horizontal gene transfer is, of course, just one of many ways in which new genetic information can appear in a genome.

No wonder creationism is a notion being increasingly rejected, even by non-biologists, while the Theory of Evolution continues to form the foundation of modern bio-medical science and is confirmed as such by just about every bio-medical research paper ever published.

---

Thank you for sharing!

Tweet Link