A Wonderful Illustration of Darwinian Logic
This business about human chromosome 2 as the slam-dunk proof of human-ape common ancestry offers a wonderful illustration of Darwinian logic. Cornelius Hunter has posted an excellent explanation of what happens to the evidence for Darwinism when you step back and adopt a "theory-neutral" stance, one that doesn't presuppose Darwinian evolution or intelligent design.
And this is what folks like Carl Zimmer cannot do. They are blind to their own presuppositions and metaphysical pre-commitments.
If you believe evolution is true to begin with, then you would conclude that the human chromosome number two is the result of a fusion of two ancestral chromosomes. There would be no question about it for several reasons. It would reconcile the different chromosome counts in humans and chimpanzees. And there are a great many similarities between the human chromosome number two and the two corresponding chimp chromosomes.Hunter's post walks you through the "typical fallacies and hypocrisies [that are inseparable from evolutionary apologetics] including shifting the burden of proof, naïve falsificationism, affirming the consequent, theological naturalism, abuse of science and circular reasoning." It's well worth reading in full.
But if evolution is not taken as an a priori, then these evidences are far less compelling. From this theory-neutral perspective, what is important is not reconciling chromosome counts or chimp-human chromosome similarities (after all, those are found throughout the respective genomes). What is important is the more direct evidence of a fusion event, such as in the region where the two chromosomes would fuse, and other tell-tale signs in the chromosome two.
Here the evidence is mixed. Certainly it is far less compelling than evolutionists ever tell their audiences. This need not be controversial. But it is.
Why? Because evolutionists are essentially incapable of such a dispassionate analysis where presuppositions and evidences are clearly laid out. Their analysis is deeply influenced by their dogmatic assertion that evolution is a fact. For evolutionists it is a metaphysical certainty and they simply are unable to evaluate the evidence from a theory-neutral perspective.
All of this results in a stubborn type of circular reasoning where evolution is presupposed, evidence is interpreted accordingly, and the results then service evolutionary apologetics as though they were obtained from objective science.
In this case, from the evolutionary perspective the chromosomal fusion event is beyond any reasonable doubt. And that event is then used as powerful evidence for evolution. It is all circular.
This is a subtle yet influential motif in evolutionary thought that often underlies discussions and debates while escaping detection.
The human chromosome number two is a concise illustration of evolutionary thought. There is, of course, much more to evolutionary thought than can be packed into this tight vignette, but it does capture the subtleties and intricacies that inevitably weave their way through any defense of evolution.