To: All Msg #88, Oct1292 07:37PM Subject: Molecular Homologies Alan M Feuerbacher wrote, +

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From: L.A. Moran To: All Msg #88, Oct-12-92 07:37PM Subject: Molecular Homologies Organization: UTCS Public Access From: (L.A. Moran) Message-ID: Newsgroups: Alan M Feuerbacher wrote, "Indeed, in a larger perspective, the close resemblance of human and chimp DNA really represents another evolutionary problem, rather than a solution. Comparisons of DNA in frogs show that there is much greater DNA variation among them than there is between the bat and the blue whale; yet the world's three thousand species of frogs are all much more similar to each other than man is to any of the other primates, to say nothing about comparing bats and whales." I believe that Alan is referring to an old problem in molecular biology that goes by the name of the "C-value paradox". The so-called paradox is that oraganisms that are very similar morphologically can have very different amounts of DNA (the amount of DNA in one complete set of chromosomes is called the C-value). Some of the most obvious examples are seen with frogs that differ in DNA content by factors of two or four even though they look pretty much the same. The explanation is that some organisms have doubled the size of their genome and that this does not have much effect on their overall morphology. Another explanation of the "paradox" is that much of the DNA in some organisms is junk. Alan's suggestion that the world's three thousand species of frogs are all much more similar to each other than man is to any of the other primates is a classic example of anthropomorphism. Most biology books will have pictures of some of the strange and exotic species of frogs - they sure look different to me! I wonder if these frogs see much of a difference between us and monkeys? Loren I. Petrich also responed to this point by saying, "Good grief!!! In macroscopic features, the batrachians (frogs and toads) are more similar in overall appearance than our species and the great apes. There was even an article in _Science_ some years back that reported on comparing human and chimp skeletons by the same kinds of measurements as are used to classify frogs. The result: more difference." I don't agree. It seems to me that the tree frogs of the South American rain forest are very different from the bullfrogs that I am familiar with, even though they share many features. It's a silly argument in any case. Alan M Feuerbacher expands on the point that there are greater differences at the molecular level between species of frogs and species of primates. "... The author of virtually every contemporary book supporting evolution trots out the human-chimp DNA comparison, but very few mention the frogs or another discovery of microbiology that has been known for some time." Species of frogs diverged from each other a long time before humans and chimps had a common ancestor. Therefore, evolution predicted that frogs would differ at the molecular level by a greater amount than primates. The prediction turned out to be correct. Alan does not understand evolution. BTW, the differences that I am referring to are not the same as the C-value differences mentioned above. Laurence A. Moran (Larry)


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