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The other thing we might do is accept Gary Nelson's optimistic view that every set of data is a glimpse of the truth. We might combine the 3 cladograms. Try that and let's see what we get. Comes out like this...(works on board) This is the cladogram we get with nice data. You like it? You don't. So what do a do? I'll take one more of these....and than I'll drop it. We have no more reptile sequences but we have plenty of mammal sequences. Let's try mammals, I think if we were to put mammals with birds and crocodiles in Mayr's diagram again I still do him no injustice if I assume that the diagram would look like this - that 3 is a mammal; C is a common ancestor, mammals that diverge very far in one direction, crocodiles a little in the other one and birds like that; B mammal, C crocodiles and D birds. B is a man, C is a crocodile and D is a chicken again. If we use the alpha hemoglobin data, this what we get.
What's going on? BC should be smaller than CD if the diagram is roughly right. In fact, they are both the same. BD should be the smallest of all, the 2 are miles apart. Something is wrong.
Well, I don't know what an evolutionist would do with this but I could guess. When I ask them about evolution the only answer I get from them is, "Convergence is everywhere." Well, I'm pretty sure they would take this as an example of convergence and they would read off the diagram: After all, birds and mammals converge into the endothermic adaptive zone.
This hemoglobin data might have given you another instance of convergence. Here the BC and CD proportion of the genotype are the same. What am I talking about? Haven't the faintest idea, not the faintest. I'll ask you what I mean. Yes. First time I put it up I meant to put it like this but that wouldn't do because these are both the same distance from C so you have to do it like this- they converge until the bird now converged until they are identical. But then the problem is they are each different from the turtle by 7.7%. Those 7.7%s are entirely different. They have to be apart by 15% whatever you do with it, convergence won't explain it. There is something funny in there.
So, after all, the question does seem insoluble. There is one more thing we can do with this. This data does give a diagram. It's not the diagram that is there (another diagram). The birds and mammals appear together and crocodiles and lizards so we follow Gary's recommendation and combine the cladogram and add mammals here. There's the cladogram we get with all this playing around. Do you like this any better? No, I'm sure youo? Well, luckily I don t have to keep asking you rhetorical questions because I'm talking about Mayr's example and I know what he did.
You remember Mayr published his original diagram in talking about the fortunes of genomes in 1974, when there very few samples of the genome available in the form of proteins or amino or nucleic acid sequences. And the two examples he offered to conform to his example were birds and crocs and apes. Well, far from matching his scheme, they all said the same thing that.... genome. So Mayr's prediction was falsified there.
(Patterson C., "Evolutionism and Creationism," Transcript of Address at the American Museum of Natural History, New York NY, November 5, 1981, p.11) [Top of page]
As I said before, falsification is never absolute and in this case, I suggested that there 3 possible things that might be false: genome data, diagram, or the claims about evolution. Well, with man and ape Mayr still believes in the diagram, and he still believes he knows about evolution so all he counted on is his data. So he dropped the genome and returned to morphology and so last week we got Broca's center and the hippocampus question all over again or its equivalent.
There are two points. to be made there. The first concerns another of the parallels between evolutionism and creationism. Back in 1974, Mayr appealed to the genotype as the holder to true knowledge. At that time the genotype was still very much a mystery. Now that we have samples of a genotype from a wide variety of organisms it's no longer quite so mysterious, its dropped and a new mystery is proposed, Broca's center and that long list of unspecified autapomorphies of man. It seems that just like creationists, evolutionists are liable to appeal to mystery.
The second point is a much more important one and it concerns the levels at which we can investigate characters in systematics. The traditional level is morphology, and we're all pretty familiar with morphology. We feel at home with morphological data and competent to handle it just by its complexities. We have a good grasp of what homology means at the morphological level and we have the transformations of ontogeny as a guide in ordering characters into transformation series.
Back in 1978 Gary Nelson suggested, "The concept of evolution is an extrapolation or interpretation of the orderliness or ontogeny." So far as I know, at the morphological level, that is at all true. As Gary said it's Von Baer's* law that ontogeny goes from the general to the particular, that it's behind the transformations we invoke in morphology and behind the systematic hierarchy being built on those morphological characters.
Of course, all the transformations we invoke are not directly observed in ontogeny but I think you'll find that every transformation that is inferred is congruent with Von Baer's* law. So at the morphological level we have a sound concept of homology and we have ontogeny to help us in ordering homology. Morphology or in the most general terms, the phenotype, is the highest level of investigation in systematics.
The next level down is the level of gene products- proteins. Here the concept of homology becomes very general. In the first place we have the problem of plurality. Plurality is what the people who play with protein sequences call the relation between gene products that we think are the results of the duplication. So plurality is the molecular version of serial homology in morphology. The difference is that in morphology you can be fairly sure that you've struck the serial homolog because you have ontogeny in which to observe whether they really are duplications or something new. But with protein sequences and this question of plurality and inferred gene duplication, the inferred duplication is somewhat ... there is no way to investigate them. It does seem to me gene duplication is often invoked simply to explain away all the data.
When you are comparing two protein sequences as a whole rather than amino acid by amino acid, homology for a molecular biologist is a purely statistical concept. You compare the two sequences and if the masses between them pass certain statistical tests, they're homologous. There was a paper by Doolittle in Science two weeks ago explaining this concept.
* Note: the original has "Conbear's"
(Patterson C., "Evolutionism and Creationism," Transcript of Address at the American Museum of Natural History, New York NY, November 5, 1981, p.12) [Top of page]
Well, having decided that two sequences of the whole are homologous, you can then align them and compare them to specify position, and that is to say amino acid is a homology of a finer level. But here the problem is whether the amino acid is really the same, the same in .... because of the redundancy of the genetic code, they are only two amino acids out of the 20, tryptophan and methiamine, that are coded by a single triplet. All the rest are coded by two or more. So there are only two amino acids that are always the same in terms of the triplet that coded them and they are the rarest amino acids. They account for less than 2% of the average sequence. All the other amino acids coded by two or more triplets, so that the amino acid level, the protein level, the gene-product level and that can never be treated or hardly ever be treated as a homology at the DNA level. You're making a guess.
So at the gene product level, homology becomes a a pretty vague concept. And also we don't have ontogeny of the gene product level with which to help us to help us order the homology for the transformation series.
Now, I used to think that because there is no ontogeny in proteins, yet somehow we seem to need the notion of transformation to order sequences, that they provided some sort of proof of evolution. And I'm no longer sure that follows because the homology ..... that we infer and the transformations that we infer in ordering them are subject to the uncertainty because of the ambiguity of the genetic code. So the real molecular homology must lie further down than the level of DNA. Below the level of DNA we know virtually nothing because there is hardly any comparative data in the form of sequences that can be aligned and compared.
Last Saturday up in Ann Arbor I was lucky enough to meet Arnold... and talk to him about the first sets, of the datas - DNA sequences. This is mitochondria ... DNA of man, chimpanzee, gorilla, orangutan and gibbon. The work was done by Prager and Wilson and their group. The sequences are each: (works on board) (mitochondria of DNA) 896 nucleotides, of those 612 are invariant and the rest variant. This is the most parsimonious tree that the Berkeley people got out the data.
This their tree. The numbers on here are the evolutionary events, lineages. This tells us lots of things about evolution. For example, it says gorilla has evolved fastest and man slowest. It says that the mitochondria of DNA evolved about times as fast as nuclear DNA. It says that sibling substitutions are several times as likely as coding substitutions and that being. the result of every comparison of DNA sequences that has yet been done. OK. That's what, the evolutionists made of the data.
Will you permit me to show you what a creationist makes of it? We've got 5 taxa, B, C, D, E there, so the first set of characters that we need to look at are the ones that pick 4 out of every 5. There are ... characters. That's the same nucleotide in every 4 and a different one in ..... ABCD there are 53, ABDE there are 21, ACDE 19, ...DE 40. There are 2 strong signals here - 53 (ABCD) and 6s here - 53 (ABCD)6 (ABCE) but unfortunately those 2 groups are incongruent. The 2 strong signals are congruent one with the other so its best to treat these rather than groupings of 4 as
(Patterson C., "Evolutionism and Creationism," Transcript of Address at the American Museum of Natural History, New York NY, November 5, 1981, p.13) [Top of page]
much hazier at those levels and we don't have ontogeny and Von Baer's* law to guide us. Now I suggested it and commented on the DNA data that the hierarchy is recognized by massaging the data with evolutionary theory. Put it through a program based on evolutionary theory and that will ....... get a hierarchy out. I wonder if the data is hierarchical without massaging of that sort? I don't know. At the protein sequence level where I have played about a lot, my impression is that it is very strongly hierarchical when you have a few sequences for when you take selected them so that you are just doing 5 or 6 problems but when you take a complete set of data, like the myoglobin that is now available, my experience is that the hierarchy can be melted away and this forces it by massaging it with evolutionary theory...
I think I'll stop and go into some quotes. This one is by Darwin the Origin.
"When the views entertained in this volume are generally admitted, systematists will be able to pursue their labors as at present.
By "present" Darwin means as in pre-Darwinian times, as in pre- evolutionary biology. He is saying don't let the theory get in the way of systematics.
The last quote is from Gillespie again and it concerns Hooker. If you think about it, Hooker was the only professional systematist amongst the Darwin coterie. He was also Darwin's oldest confidant in reading all of Darwin's manuscripts and talking to him solidly since 1840 and yet he remained unconverted to evolution until 1859. Here is Gillespie on the reason Hooker was not converted.
"Hooker adopted a view that species were immutable and each descended from a single parent. It was not necessarily his belief but a methodological postulate to make classification possible...Hooker believed that a taxonomist, who was an evolutionist, must ignore his theory and proceed as if species were immutable."
In other words, evolution may very well be true but basing one's systematics on that belief will give bad systematics.
* Note: the original has "Conbear's"
(Patterson C., "Evolutionism and Creationism," Transcript of Address at the American Museum of Natural History, New York NY, November 5, 1981, p.14)
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