Today I was thinking about convergent evolution and wondering if anyone has ever tried to calculate the odds of the amount of convergent evolution that we see in the world today. For those who are new to biological terms, convergent evolution is the occurrence of similar traits arising in organisms that are not closely related. For example, the zebrafish has an eye that closely matches the human eye. Some have even put the similarity at 97%. In fact, eyes are a structure that have supposedly independently evolved many times throughout history (Richard Dawkins puts the number of independent evolutions of the eye at about 40). Other examples include the similarities between tasmanian wolves (marsupials) and canines. A broader list of examples can be found at the wiki page for convergent evolution.
So, what are the chances of 40 different eyes independently evolving? I’m aware of no study that tackles this problem, and I’m not surprised. The probability would most likely be so slim as to not be worth considering.
One might contend, however, that in the case of the zebrafish and humans, that it somehow shows common descent. The argument is that certain features of the eye are highly conserved, so we might expect those features to persevere in the face of RM + NS. But, this is such a weak argument it almost doesn’t need answering. This argument completely ignores the fact that many of the transitional forms in between do not have those same features. We would have to believe that these features somehow were conserved, but not expressed until zebrafish and humans both came onto the scene. This is simply not realistic. Once again, we find some pretty shoddy “science” used to prop up evolution. The more likely explanation is common design.