In his article on human evolution Graeme Finlay states that duplicated DNA segments prove evolution. Finlay's proof is straightforward. These duplications of DNA segments arise randomly and yet identical duplications are found in cousin species, such as humans and chimpanzees. Finlay uses as his example opsin genes which produce proteins that are light sensitive. Different opsin genes produce proteins that are sensitive to different colors of light. The proteins are found in the hundreds of millions of photocells in our retina and they allow us to sense the different colors of light that we see. By combining the signals from these different photocells, our brain can assemble a full color image.
Two of our opsin genes are close to each other in our DNA, and they are very similar (except that they are tuned to different colors of light). The evolutionary hypothesis is that the one opsin was formed when the other was duplicated and was inserted into the DNA. At first glance it seems like a perfectly reasonable hypothesis.
But Finlay and the evolutionists go much further--they say it is yet another compelling proof of evolution. Finlay concludes that these genetic similarities demonstrate "that the duplication arose in a unique event, and that it has been inherited by all the species that now possess it."
Can we really be so sure? In fact there are three major problems with this evolutionary logic.
1. Is the genome really so random?
Recall that Finlay's assumption is that these duplications of DNA segments arise randomly. This of course is standard evolutionary reasoning. Everything occurs randomly until proven otherwise. But the empirical evidence does not bear this out and the argument is circular. Indeed, even if evolution is true there are similar DNA duplications in cousin species that violate the evolutionary expected pattern. Evolutionists must explain these convergent duplications with non evolutionary mechanisms. So by their own admission, evolution is not required to explain such duplications.
2. It is at most only a successful prediction.
Ignoring problem #1 above, even if we grant the observed DNA duplications as perfectly fitting evolutionary expectations, they are at most only a successful prediction. They certainly cannot be said to require evolution as an explanation (that would be the fallacy of affirming the consequent). They cannot prove evolution to be true. They would have to be compared with all the false predictions and the totality of the evidence would have to be accounted for before making pronouncements about evolution.
3. A plethora of problems ignored.
Finally, as I have discussed before, Finlay's evidence raises profound problems for evolution. Most obviously, the evolutionist takes for granted the pre existence of the color-coding gene, the photocells, the retina, and the remainder of the vision system and brain. From where did this incredible system come? Are we to believe that it too is simply the result of evolution because evolutionists think a DNA duplication event added more color resolution?
Another problem is that evolutionists vastly underestimate the complexity of the supposed evolutionary change required. A DNA duplication event followed by a few mutations to tweak the color sensitivity does not instantly provide enhanced color resolution. That is only the beginning of what would be required. The product of the new color-coding gene would need to be used in certain photocells. The quantity and locations of these photocells are important.
And on the receiving end, downstream cells would need to be reprogrammed, to interpret properly the new color information. This is because the photocells do not signal their color. The output of the photocell is merely a nerve impulse (action potential), and its interpretation is an extremely complex process. Modifying a color-coding gene without concomitant downstream reprogramming just confuses things.
And yet Finlay is sure these genetic similarities prove evolution. Religion drives science and it matters.