Scott Faust
Molecular Evidence

Here we go again folks with M. Denton's silly "typology" argument...

ANADI DASA to ALL, 06-09-93, re: "Does Evidence Support Des"

> In recent years, geneticists have discovered that in species of
> similar form the DNA and other proteins have similar molecular
> structures.

 More like recent decades.  This was apparent as much as thirty
 years ago or more.  Also, many proteins show clearly identifiable
 homology in the most widely diverse forms (like, say, bacteria,
 fish and humans), not just in "species of similar form".

> So just as evolutionists have deduced ancestral relationships
> among species from similarities in physical form, some of them now
> deduce such relationships from the genetic similarities.

 And the topography of the phylogenies or cladograms produced from
 these two independent lines of evidence show very good general
 agreement.  But then this is just a coincidence, right?

> It is not, however, very surprising that similar species would
> have similar genetic materials. But the main point is that such
> similarities show nothing definite about how the organisms
> orginated and cannot be used as proof of Darwinian-style
> evolution. If an intelligent designer had produced varieties of
> organisms with certain structural similarities, we would also
> expect to see parallel molecular relationships.

 Maybe, but this is -not- the pattern that we find when all the
 evidence is considered.

 Because rates of morphological change can vary greatly among
 different lineages, and because many standard taxa are therefore
 "paraphyletic" or even "polyphyletic" rather than monophyletic,
 there are cases where the typology of evolutionary relationships
 does not correspond well to the overall "structural similarities"
 upon which conventional classifications are based.  And even when
 taxa are monophyletic, taxa of equal rank do not always (or even, I
 would guess, usually) correspond to equivalent hierarchical levels
 in terms of branching evolutionary relationships.  In such cases
 similarities at the molecular level stubbornly correspond to
 phylogenetic relationships (specifically, the relative amount of
 time since two forms last shared a common ancestor) rather than to
 overall structural similarities.

 For example, we have long known on the basis of comparative anatomy
 and the fossil record that crocodiles are more closely related to
 birds than they are to any of the other living reptiles.

 Crocodilians are the last surviving archosaurs or "ruling
 reptiles".  Dinosaurs were also archosaurs.  All archosaurs,
 including the crocodiles, evolved from a group of reptiles called
 thecodonts.

 As to birds, we know that they either evolved directly from
 dinosaurs (currently the stronger theory), or that they evolved
 more directly from the thecodonts.  In either case they would share
 a common ancestor with crocodiles among the thecodonts.

 But if we want to find ancestors shared by crocodiles and
 non-ruling reptiles (turtles, snakes, lizards) we would have to go
 further back in time, probably back to the stem reptiles.

 Now, if the evolutionary scheme I have described is correct, and
 crocodiles and birds did share a more recent common ancestor than
 crocodiles and non-ruling reptiles, then we should expect them to
 be more similar at the molecular level, not withstanding that
 crocodiles happened to have remained essentially reptilian whereas
 birds have been extensively modified.

 If your non-evolutionary scheme is correct then crocodiles should
 resemble other reptiles at the molecular level more than they do
 birds.

 You want to take a guess as to which is the case?

 Another example along this same line involves humans and apes.  At
 the molecular level is not possible to separate humans and apes at
 all, for chimpanzees and gorillas resemble humans much more closely
 at the molecular level than they do orangutans.  (Indeed, it even
 appears at this point that humans and chimps are more similar than
 chimps and gorillas, but the differences in this case are extremely
 slight and difficult to resolve conclusively.)

 This result jives well with the fossil evidence since the discovery
 that _Siva/Ramapithecus_ was an orangutan like form and not an
 early hominid (human ancestor) as was once thought.  If
 Ramapithecus still stood as a hominid it would place the human /
 african ape split too early to fit with the molecular data.

~~~~~~~~~~~~~~~

 NOTE TO ALL:

 Although I have been told that it is correct, I'm not entirely
 happy with my reference to the fact that crocodiles and birds are
 more similar at the molecular level than crocodiles and
 lepidosaurs.  This was first brought to my attention by the Texas
 antievolutionists and textbook activists Mel and Norma Gabler.

 With characteristic denseness and ironic ineducability, the Gablers
 persist in claiming that this is evidence -against- evolution!
 They also give a similar example based on the fact that horseshoe
 crabs are "more similar to spiders".  Ironically (in light of their
 frequent complaints about poor grammar in textbooks) they don't say
 "more similar" to WHAT; but I assume they mean crustacean type
 crabs.  This, of course, is a case just like the other.  Scientists
 recognized that _Limulus_ is more closely related to arachnoids
 than to crustaceans long before the molecular evidence was even
 available, and in this case I believe that even conventional
 (non-cladistic) classifications reflect that.

 Anyway, if anyone (possibly Jeff Otto) can give me some solid
 references concerning the molecular similarities of
 crocodiles/lepidosaurs/birds (and maybe the horseshoe
 crabs/arachnoids/crustaceans as well, though I don't think its as
 useful an example) I would appreciate it.  I think that I will also
 post this in talk.origins.

 Other examples that could be used in this argument, of cases where
 overall "typological" similarity differs from phylogenetic
 relationships, would also be appreciated.

 This line of argument occurred to me when I first read the Gablers
 bit about crocodiles and birds.  I think it is a useful supplement
 to the more straightforward refutations of Denton's arguments about
 molecular homologies, but I've never seen anyone else use it in the
 various responses to Denton that I have consulted.  As I am a
 scientific lay person, I would thus be interested in comments from
 those more knowledgeable.  Thanks!

~~~~~~~~~~~~~~~

> In one of his recent books, prominent astrophysicist Sir Fred
> Hoyle reproduced a chart purporting to show evolutionary
> relationships among species based upon molecular studies. He
> observed, "One should not be deceived, however, by the elegance of
> this result into thinking that [the chart] proves the existence of
> an evolutionary tree. What it shows is that if a tree existed,
> then it was like this."

 Whatever...  But even Hoyle (who has some -very- strange views
 about evolution) would appear to recognize -- re his comment about
 the "elegance" of the result -- that evolutionary common descent
 -does- explain the evidence in a detail and specific manner.  I
 would invite you to compare this to the arm waving nature of the
 explanation (or, rather, rationalization) that you have offered
 here.  And in spite of its vague and general nature, it can still
 only explain selective portions of the data, whereas evolution
 successfully engages -all- of the data.

> -Anadi

 Your name (which I am guessing is Indian?) leads me to ask you the
 following questions.  I hope that I do not offend...

 Sometime ago, in an echo on a different net, I was asked about
 antievolutionism in other countries and cultures; and in religions
 other than christianity, judaism or islam.  I admitted that I
 didn't know much, but since hinduism was specifically mentioned I
 said I knew that hare-krishna, at least, held an antievolutionary
 position, although I didn't know about mainstream hinduism.

 I'm curious if you might be hindu (or even hare-krishna)?  I would
 also be interested to know if the book you mentioned awhile back,
 which supposedly documents that anatomically modern humans existed
 millions of years ago, might be written by a hindu or other
 non-christian type.

 You see I collect antievolution literature and would like to expand
 both my collection and knowledge of the subject beyond the
 christian and biblical type that predominates in north america.
 Thanks!

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