ericmurphy
Posts: 2460
Joined: Oct. 2005
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| Quote (The Ghost of Paley @ Nov. 08 2005,19:18) | | You do realise that this "astronomical number of possible trees" business is derived solely from Hubert Yockey's cytochrome c analysis... |
This is wrong. The "astronomical number of possible trees" has nothing to do with cytochrome c analysis, or any analysis at all. It has to do with mathematics.
I know you said you've read Theobald closely, Bill, but you keep providing me evidence to the contrary. As Theobald points out, as the number of taxa (or, for that matter, any kind of object -- cars, asteroids, library books) that you're trying to relate to each other increases, the number of possible genealogical "trees" you can construct goes up geometrically. Theobald presents a handy little chart (Table 1.3.1). I'll excerpt a few entries so you can get the general flavor of what we're talking about:
2 taxa: 1 relationship
4: 15
7: 10,395
11: 34,459,425
20: 8,200,794,532,637,891,559,375
30: 4.95 E 38
This has nothing to do with how you analyze the objects you're trying to relate to each other. It's a matter of pure mathematics.
Which brings me way, way back to what I said in this thread about six or seven pages ago. The consensus phylogenetic tree that Theobald depicts is based on, not a few proteins, not a few genes, and not a lot of proteins or a lot of genes. It's based on genetics, protein analysis, the fossil record, morphological studies, developmental evolution, geology, and other lines of inquiry. All of these lines of evidence converge on the tree as Theobald shows it.
Now, you've pointed out that different individual lines of evidence can show discordant trees. You won't get an argument from me there. But you're talking about individual lines of evidence showing weird relationships between two different species. There are tons of organisms, as I stated a couple of messages ago, which are problematic in terms of what their exact phylogeny is. But for the 30 major taxa in Theobald's tree (note there are no species mentioned, or genera, or families, for that matter), there is an overwhelming consensus opinion that the phylogenetic tree as pictured is correct.
The tree shows that fungi are more closely related to animals than either are to plants. It shows that birds are more closely related to mammals than either are to insects. Surely you don't deny phylogenies at this level of detail, do you, Bill? When you get down either to the level of genera, or conversely to the base of the tree (are archae more closely related to eubacteria, or to eukaryotes?) things get murky. But the worst you can say about the consensus tree is that it's a solid beginning, supported by solid independent lines of evidence. And the fact that a dozen or more lines of evidence all converge on the same tree, out of ~5 E 38 possibilities, is pretty persuasive evidence for common descent, don't you think? Even if cladistic analysis could get the number of trees down to only a million different ones, isn't that an unbelievable level of precision? How many physical constants are known to 32 decimal places? The mass of the electron is known to seven places. G, the universal gravitation constant, is known to three places.
I think you greatly overestimate the problems with phylogeny, Mr. Paley.
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2006 MVD award for most dogged defense of scientific sanity
"Atheism is a religion the same way NOT collecting stamps is a hobby." —Scott Adams
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