dubois@uwmacc.UUCP (Paul DuBois) (05/22/85)
>>> [Jeff Sonntag] >>> What about all of the biochemical evidence showing that enzymes from >>> closely related species are much more similar to each other than enzymes >>> which perform the same function in other, more distantly related species? >>> Are we supposed to write this off to coincidence, or should we assume that >>> God set things up this way in order to fool us into thinking that evolution >>> is correct? >> >> [Gary Samuelson] >> Actually, I write it off as circular reasoning. "Closely related >> species?" Assuming that species are "related," and further that >> some such relations are "close" and others are "distant" sounds >> like you have assumed that which you wish to prove. > Since you don't seem to understand what I meant, I'll try again. Long > before any biochemical similarities were studied, people noticed that some > species shared many common traits, while other sets of species shared few. > For example, men and apes share many common traits, while men and bullfrogs > share far fewer. Then, biochemistry advanced far enough to be a useful > science, someone got the bright idea to check and see if sets of species > like men and apes, which share common traits might also be very similar > biochemically. It turned out that sets of species which share more common > traits are more similar biochemically. This was easily predicted by > evolution, since sets of species which share more common traits are thought > to have more recent common ancestors. > If creation is correct, why is it that species which share many common > physical characteristics also have many more biochemical similarities than > randomly selected sets of species? Would you genuninely expect that if all life were created, that randomly chosen organisms would share just as many biochemical similarities as species sharing many common physical characteristics? One doesn't need creation OR evolution to predict that organisms which are physically similar are going to be more biochemically alike than organisms which are physically dissimilar. I suspect that most people would predict this intuitively. Even so, it's not so simple as that (as usual in biology). Dogs are remarkably interfertile, even ones morphologically quite dissimilar. But if you take a leopard frog (_Rana pipiens_) from a Northern state and mate it with one from a Southern state, you'll end up with a bunch of dead embryos in spite of the morphological near-identity [1p896, 2p178]. Investigation of the rates of change of protein and nucleotide sequences (e.g., Wilson et al) finds that the rates are basically constant, in contrast to the non-constant rate of morphological evolution. This has certain implications for our topic. [3p616] "Molecular evolutionists were slow to recognize this surpising and intriguing fact. They had assumed that organismal evolution depends on sequence evolution in proteins and expected a simple relationship between two types of evolution. In particular it was expected that morphologically conservative organisms should have experienced slower macromolecular evolution than organisms that had evolved unusually rapidly at the morphological level. To date, however, there is no convincing evidence that the proteins or nucleic acids of conservative creatures are conservative in regard to their amino acid or nucleotide sequences." As an example, frogs and placental mammals may be compared. All of the thousands of species of frogs are placed within a single order, due to their high degree of phenotypic similarity. Placental mammals, on the other hand, are categorized into about 16 orders. Evolutionarily, frogs are much older than mammals; obviously morphological evolution must have been much slower. Yet at the sequence level, rate of evolution is about the same as that of mammals. "Species of frogs that are similar enough to be included within a single genus can differ as much at the sequence level as does a bat from a whale." [p618] Bacteria (prokaryotes) do not differ much from each other morphologically. But *within* the Rhodospirillaceae bacteria family, greater variability of cytochrome _c_ is found than *among* all eukaryotic organisms studied. Would you predict these sorts of things from evolution? Would you predict it from creation? Probably not. How could you? --- References [1] Helena Curtis, _Biology_ (2nd ed). Worth Publishers, New York, 1976. [2] Theodosius Dobzhansky, _Evolution, Genetics and Man_. John Wiley and Sons, New York, 1955. [3] Allan C Wilson, Steven S Carlson, Thomas J White, "Biochemical Evolution". Annual Review of Biochemistry, 46, 1977, 573-639. -- | Paul DuBois {allegra,ihnp4,seismo}!uwvax!uwmacc!dubois --+-- | |
ethan@utastro.UUCP (Ethan Vishniac) (05/23/85)
Referring to arguments concerning biochemical and morphological evolution Paul Dubois, after nicely summarizing the evidence, writes > > Would you predict these sorts of things from evolution? Would you > predict it from creation? > > Probably not. How could you? Of course you could predict it from evolution. All you need to realize is that morphological evolution is constrained by the available ecological niches but most complicated biochemical substances have numerous alternative and equally useful forms. In most large organisms this is exagerated by the fact that much the genetic material present is "silent" and so can be scrambled indefinitely without causing any untoward effects (as long as it stays silent). How could you predict this from creation? "Don't argue with a fool. Ethan Vishniac Borrow his money." {charm,ut-sally,ut-ngp,noao}!utastro!ethan Department of Astronomy University of Texas
ethan@utastro.UUCP (Ethan Vishniac) (05/24/85)
[]
One more comment about biochemical affinities. Paul provided
one example (there are many more) in which we can see that biochemical
affinity is a measure of the degree of relationship *as deduced from
the fossil record*, not necessarily by present characteristics.
What can one make of this? The obvious conclusion is that both methods
measure the same thing. If one believes, as Paul evidently does, that
relationships based on the fossil record are totally fictitious than
this becomes a coincidence beyond understanding. Faith in God is not
a sufficient reason for swallowing this coincidence. One must also believe
that he (she?) is hell of a practical joker. Alternatively one could
abandon creationism as bad science and bad theology. Any takers?
"Don't argue with a fool. Ethan Vishniac
Borrow his money." {charm,ut-sally,ut-ngp,noao}!utastro!ethan
Department of Astronomy
University of Texasmrh@cybvax0.UUCP (Mike Huybensz) (05/28/85)
In article <1125@uwmacc.UUCP> dubois@uwmacc.UUCP (Paul DuBois) writes: > Would you genuninely expect that if all life were created, that > randomly chosen organisms would share just as many biochemical > similarities as species sharing many common physical characteristics? Why not? > One doesn't need creation OR evolution to predict that organisms which > are physically similar are going to be more biochemically alike than > organisms which are physically dissimilar. I suspect that most people > would predict this intuitively. How similar? In what compounds? Why should some portions of the biochemistry be conservative while others vary a great deal? > Investigation of the rates of change of protein and nucleotide > sequences (e.g., Wilson et al) finds that the rates are basically > constant, in contrast to the non-constant rate of morphological > evolution. This has certain implications for our topic. Investigation of HOMOLOGOUS proteins and nucleotides sequences reveals basically constant rates. But different rates for different sets of homologues. On the other hand, rates of morphological evolution are extremely hard to characterize because of anthropocentrism. Take your leopard frog, for example. There are at least four species on the east coast that are "morpologically identical" as far as our senses are concerned: enhance our senses and we can perceive the differences. The species were distinguished by sonograms of their mating calls, as well as hybrid inviability. > [3p616] "Molecular evolutionists were slow to recognize this surpising > and intriguing fact. They had assumed that organismal evolution > depends on sequence evolution in proteins and expected a simple > relationship between two types of evolution. In particular it was > expected that morphologically conservative organisms should have > experienced slower macromolecular evolution than organisms that had > evolved unusually rapidly at the morphological level. To date, > however, there is no convincing evidence that the proteins or nucleic > acids of conservative creatures are conservative in regard to their > amino acid or nucleotide sequences." > > As an example, frogs and placental mammals may be compared. All of the > thousands of species of frogs are placed within a single order, due to > their high degree of phenotypic similarity. Placental mammals, on the > other hand, are categorized into about 16 orders. Evolutionarily, > frogs are much older than mammals; obviously morphological evolution > must have been much slower. Yet at the sequence level, rate of > evolution is about the same as that of mammals. > > "Species of frogs that are similar enough to be included within a > single genus can differ as much at the sequence level as does a bat > from a whale." [p618] > > Would you predict these sorts of things from evolution? Would you > predict it from creation? Note now that this provides evolutionists a way to predict the magnitude of biochemical differences within groups depending on their evolutionary conservatism as shown by the fossil record. Creationists CANNOT make those predictions because they cannot identify conservatism because they cannot measure ages of groups. > Bacteria (prokaryotes) do not differ much from each other > morphologically. But *within* the Rhodospirillaceae bacteria family, > greater variability of cytochrome _c_ is found than *among* all > eukaryotic organisms studied. Here is a perfect example of the inadequacy of morphological criteria for classification. There are many groups where (because of the limitations of our senses) we have not been able to make good phylogenetic classifications. Bacterial, protozoan, and some other classifications are rife with "garbage bin" groups which are acknowledged not to be monophyletic, simply because there isn't enough data to classify them any more specifically (yet.) So there are really two possible explanations for cytochrome variability among Rhodospirillaceae: that the group is good but very ancient, or that the group is polyphyletic. -- Mike Huybensz ...decvax!genrad!mit-eddie!cybvax0!mrh