Mark Vernon authored Not so highly evolved, an article worth reviewing, both for its analysis of Richard Dawkins and for its commentary about an evolutionary phenomenon known as convergence. The article begins:

The 2009 Darwin celebrations are officially under way, now that we are halfway through Richard Dawkins' flagship TV series, The Genius of Charles Darwin. But I can't help but feel they have not begun well. Dawkins' exploration of the science seems to be driven mostly by his desire to score atheistic points: this is not evolution as survival of the fittest but as zero-sum game.

I have not seen the TV series but based on prior behavior a charge that Dawkins is using science to score atheistic points comes as no surprise. If Dawkins is indeed guilty as charged he needs to be taken to task. The Trojan Horse imagary is apt for all who would use science to introduce a side agenda. Vernon also had this to say:

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Despite the stunning variety of photoreceptor organs, every animal uses the same kind of light-capturing molecule to do this job. Insects, humans, clams, and scallops all use opsins. Not only can we trace the history of eyes through differences in the structure of their opsins, but we have good evidence that we can thank bacteria for these molecules in the first place.

The bacterial past can be used to our advantage in studying the diseases of mitochondria — in fact, some of the best experimental models for these diseases are bacteria. This is powerful because we can do all kinds of experiments with bacteria that are not possible with human cells… [European researchers] were able to simulate parts of a human mitochondrial disease in a bacterium, with virtually the same change in metabolism. This is putting a many-billion-year part of our history to work for us.

Your Inner Fish: A Journey into the 3.5-Billion-Year History of the Human Body

Here's the abstract of an old paper that uncovered a nice example of convergent evolution at the molecular scale:

We have isolated and sequenced genes from the blind cave fish, Astyanaxfasciatus, that are homologous to the human red and green visual pigment genes. The data strongly suggest that, like human, these fish have one red-like visual pigment gene and multiple green-like visual pigment genes. By comparing the DNA sequences of the human and fish visual pigment genes and knowing their phylogenetic relationship, one can infer the direction of amino acid substitutions in the red and green visual pigments. The results indicate that the red pigments in human and fish evolved from the green pigment independently by identical amino acid substitutions in only a few key positions.

Yokoyama R, Yokoyama S. 1990. Convergent evolution of the red- and green-like visual pigment genes in fish, Astyanax fasciatus, and human. Proc Natl Acad Sci U S A. 87:9315-8.