Theory of the GapsResearch out of Israel continues to hammer away at the once powerful proof text for evolution, that our retina is one big kludge given that the photocells were obviously installed backwards. Not only that, but to add insult to injury, the resulting neuron wire bundle had to go somewhere, and the result was a blind spot in our retina. Such a kludge could only be ascribed to the blind process of evolution. The problem with such arguments, aside being nonscientific, is that they are vulnerable to the inexorable march of scientific progress. The act has played out repeatedly: When we first observe a design we don’t understand it and conclude it must be mostly nonsense and another confirmation of evolution. Then, years later, science discovers a nifty function for the design.
So it is with our retina and its “backward” photocells. They were celebrated as an example of nature’s “errors and bungles” and yet another vindication of the Epicurean call for a designer-less world.
But that was then and this is now. It turns out those backward photocells, along with the retina’s Müller cells, work to focus the green-red part of the light spectrum onto the cone photoreceptors and pass the shorter-wavelength blue-purple light through to the rod photoreceptors. As Professor Erez Ribak put it, those backward photocells and the overall retina “optical structure is optimized for our vision purposes.”
This is another example of the danger of constructing theories on the gaps in our knowledge.