The evolutionary argument from homology is notoriously circular:
The anatomical structures are similar because they are derived from a common ancestor.
And we know they share a common ancestor because of the similarity of the anatomical structures.
The same circular reasoning, but on a molecular level.
Not even close.
I forget now who originally posted these on this forum, but I keep it in my archives because it offers a nice 'linear' progression of testing a methodology and then applying it - I have posted this more than a dozen times for creationists who claim that there is no evidence for evolution:
The tested methodology:
Science 25 October 1991:
Vol. 254. no. 5031, pp. 554 - 558
Gene trees and the origins of inbred strains of mice
WR Atchley and WM Fitch
Extensive data on genetic divergence among 24 inbred strains of mice provide an opportunity to examine the concordance of gene trees and species trees, especially whether structured subsamples of loci give congruent estimates of phylogenetic relationships. Phylogenetic analyses of 144 separate loci reproduce almost exactly the known genealogical relationships among these 24 strains. Partitioning these loci into structured subsets representing loci coding for proteins, the immune system and endogenous viruses give incongruent phylogenetic results. The gene tree based on protein loci provides an accurate picture of the genealogical relationships among strains; however, gene trees based upon immune and viral data show significant deviations from known genealogical affinities.
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Science, Vol 255, Issue 5044, 589-592
Experimental phylogenetics: generation of a known phylogeny
DM Hillis, JJ Bull, ME White, MR Badgett, and IJ Molineux
Department of Zoology, University of Texas, Austin 78712.
Although methods of phylogenetic estimation are used routinely in comparative biology, direct tests of these methods are hampered by the lack of known phylogenies. Here a system based on serial propagation of bacteriophage T7 in the presence of a mutagen was used to create the first completely known phylogeny. Restriction-site maps of the terminal lineages were used to infer the evolutionary history of the experimental lines for comparison to the known history and actual ancestors. The five methods used to reconstruct branching pattern all predicted the correct topology but varied in their predictions of branch lengths; one method also predicts ancestral restriction maps and was found to be greater than 98 percent accurate.
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Science, Vol 264, Issue 5159, 671-677
Application and accuracy of molecular phylogenies
DM Hillis, JP Huelsenbeck, and CW Cunningham
Department of Zoology, University of Texas, Austin 78712.
Molecular investigations of evolutionary history are being used to study subjects as diverse as the epidemiology of acquired immune deficiency syndrome and the origin of life. These studies depend on accurate estimates of phylogeny. The performance of methods of phylogenetic analysis can be assessed by numerical simulation studies and by the experimental evolution of organisms in controlled laboratory situations. Both kinds of assessment indicate that existing methods are effective at estimating phylogenies over a wide range of evolutionary conditions, especially if information about substitution bias is used to provide differential weightings for character transformations.
We can ASSUME that the results of an application of those methods have merit.
Application of the tested methodology:
Implications of natural selection in shaping 99.4% nonsynonymous DNA identity between humans and chimpanzees: Enlarging genus Homo
"Here we compare ≈90 kb of coding DNA nucleotide sequence from 97 human genes to their sequenced chimpanzee counterparts and to available sequenced gorilla, orangutan, and Old World monkey counterparts, and, on a more limited basis, to mouse. The nonsynonymous changes (functionally important), like synonymous changes (functionally much less important), show chimpanzees and humans to be most closely related, sharing 99.4% identity at nonsynonymous sites and 98.4% at synonymous sites. "
Mitochondrial Insertions into Primate Nuclear Genomes Suggest the Use of numts as a Tool for Phylogeny
"Moreover, numts identified in gorilla Supercontigs were used to test the human–chimp–gorilla trichotomy, yielding a high level of support for the sister relationship of human and chimpanzee."
A Molecular Phylogeny of Living Primates
"Once contentiously debated, the closest human relative of chimpanzee (Pan) within subfamily Homininae (Gorilla, Pan, Homo) is now generally undisputed. The branch forming the Homo andPanlineage apart from Gorilla is relatively short (node 73, 27 steps MP, 0 indels) compared with that of thePan genus (node 72, 91 steps MP, 2 indels) and suggests rapid speciation into the 3 genera occurred early in Homininae evolution. Based on 54 gene regions, Homo-Pan genetic distance range from 6.92 to 7.90×10−3 substitutions/site (P. paniscus and P. troglodytes, respectively), which is less than previous estimates based on large scale sequencing of specific regions such as chromosome 7[50]. "
Catarrhine phylogeny: noncoding DNA evidence for a diphyletic origin of the mangabeys and for a human-chimpanzee clade.
"The Superfamily Hominoidea for apes and humans is reduced to family Hominidae within Superfamily Cercopithecoidea, with all living hominids placed in subfamily Homininae; and (4) chimpanzees and humans are members of a single genus, Homo, with common and bonobo chimpanzees placed in subgenus H. (Pan) and humans placed in subgenus H. (Homo). It may be noted that humans and chimpanzees are more than 98.3% identical in their typical nuclear noncoding DNA and probably more than 99.5% identical in the active coding nucleotide sequences of their functional nuclear genes (Goodman et al., 1989, 1990). In mammals such high genetic correspondence is commonly found between sibling species below the generic level but not between species in different genera."
