Wednesday, January 02, 2008

Do Morphological Similarities Imply Common Descent?

One of the most commonly used evidences for Darwinism is the fact of morphological similarities between various organisms. To put it simply, many organisms look like each other. These similarities extend not just through the physical phenotype, but also into the genotype as well. Indeed, much hay is made over the fact that chimp DNA is 98% similar to human DNA (although that figure has been questioned recently).

Rather than looking at some specific examples, I want to first look at the concept as a whole. Is it true that morphological similarities imply common descent from an original species?

It is certainly true that similarities can indicate descent. We see examples of this in the genome all the time, especially with recessive and dominant genes that obviously follow a hereditary tree. But we have equal evidence of similarities that do not follow heredity, that do not imply common descent.

One obvious example of this is found if you look in the parking lot at your local mall. You will see various “organisms” of vehicles out there: Ford, Chevy, Nissan, Mazda, etc. All of these vehicles have similar structure, are made from similar materials, and are used in similar manners. Yet we know that the Chevy did not evolve from Ford except insofar as the design was copied by an intelligent agent. As a result of this simple concept, we see that morphological similarities need not imply common descent; they can also imply design.

And we do not need to restrict ourselves to non-biological aspects to see this. Ernst Mayr, for instance, argued that eyes evolved independently over 40 times in the fossil record. That is, eyes formed in various species in the fossil record after the theorized branching point between the two species had already occurred, which is to say that both daughter species came from a common ancestor that was blind, yet both developed eyes anyway. Further evidence is found in the concept of Convergent Evolution, which states (for example) that all birds have the same basic wing shape because it is necessary for flight, not because they all share a common ancestor. In other words, convergent evolution of the wing shape, of eyes, and of myriad other aspects are already acknowledged by Darwinists to not be evidence of common descent, but instead of common use.

Because morphological similarities need not be evidence of common descent (as evidenced by the convergent evolution theory) and they can be evidence of common design (as seen in a myriad number of intelligently designed machines that look alike in order to perform a specific similar function), morphological similarities do not imply common descent. At most, all a Darwinist can say is that morphological similarities are consistent with Darwinism; but the intelligent design advocate can make the same claim about I.D. As such, this often offered argument for Darwinism proves nothing.

35 comments:

  1. :::YAWN!!!:::

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  2. There's nothing that can be said in response to the intellect of a man like Anonymous. His responses are expressed in such manner that one need not even read them in order to grasp them. Truly, he is a teacher who is capable in one word to bring the entire room to his intellectual level. I cannot recommend his style highly enough to those wishing to egange in intellectual discourse. Indeed, were all of us at his intellectual level I daresay we'd no longer be concerned with any opposing rational arguments at all.

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  3. Anonymous,

    I let you have the one :::YAWN!!!::: and that's all you get. The rest are going to continue to be deleted.

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  4. Except that the "designed" similarities are not evidence of a good-smart-god-design because they suck. Therefore, since we can deny the one side of the disjunct, it appears that similarities favor the evolutionary story rather than the goddidit story. Try to familiarize yourself with the counter arguments before posting.

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  5. Bob said:
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    Except that the "designed" similarities are not evidence of a good-smart-god-design because they suck.
    ---

    I suppose that's why geneticists often talk about how amazing the chemical pathways are, and what a "magnificent feat of engineering" DNA turns out to be, etc. etc. etc. I suppose that's why botanists spend so much time looking at plants. I suppose that's why Jane Goodall spent so much time looking in awe upon apes.

    Secondly, who are you to say they "suck"? Note that first in order to say the design sucks you have to acknowledge that there is a designer, even if just an implicit acknowledgement for the sake of arguing. As such, in order to say that the designer "sucks" you must establish 1) What did the designer intend to do? 2) How the design fails to accomplish 1). Barring that, you haven't established that the design "sucks."

    You said:
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    Therefore, since we can deny the one side of the disjunct, it appears that similarities favor the evolutionary story rather than the goddidit story.
    ---

    A) Anyone can "deny" whatever they want to deny. That you can deny something doesn't rid the disjunct.

    B) In order to deny the design aspect, you have to put forth an actual argument rather than "that sucks."

    You said:
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    Try to familiarize yourself with the counter arguments before posting.
    ---

    Take your own advice.

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  6. BTW, Bob's argument amounts to the following:

    The Honda Accord in the parkinglot was obviously not designed because it cannot win the Indy 500.

    Therefore, the designer must have been stupid.

    Therefore, Darwindidit.

    Yet that argument is far from convincing (unless you're anonymous, in which case you're sold).

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  7. Bob said:

    "Except that the 'designed' similarities are not evidence of a good-smart-god-design because they suck. Therefore, since we can deny the one side of the disjunct, it appears that similarities favor the evolutionary story rather than the goddidit story."

    So Bob is admitting that he's poorly designed. And to judge by the quality of his argumentation, his level of functionality leaves much to be desired.

    But from a theological standpoint, we can attribute his dysfunctionality to the noetic effects of sin rather than any design flaws.

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  8. Scientists laud the pathways, DNA structure, and apes because it _is_ amazing what happened. In fact, it's more amazing that it happened by chance and without a grand purpose than if an all powerful goddidit.

    Who am I to say it sucks? Me and my bad back. I guess that's what the designer "intended."

    Yeah, anyone can deny propositions. I don't find your argument compelling. So, I don't find your conclusion that:

    "At most, all a Darwinist can say is that morphological similarities are consistent with Darwinism [...] As such, this often offered argument for Darwinism proves nothing."

    to persuasive. If I deny one side of the disjunct, and I see no reason to believe your story, then it's not the case that the argument "proves nothing." You have to establish "godditit." You haven't done that. Pointing out cars in parking lots doesn't do that for you.

    My "it sucks" argument is just fine. If "goddidit" works for you, "it sucks" works for me.

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  9. Bob said:
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    Scientists laud the pathways, DNA structure, and apes because it _is_ amazing what happened. In fact, it's more amazing that it happened by chance and without a grand purpose than if an all powerful goddidit.
    ---

    Except that chance doesn't exist. It's a non-entity. It has no ontology. Nothing can happen "by chance" in any meaningful sense of the word. (BTW: here you are invariably falling into teleology while attempting to deny teleology by imputing design to a non-existent "cause" (i.e., "chance"), but that's what happens when you're irrational.)

    Bob said:
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    Who am I to say it sucks? Me and my bad back. I guess that's what the designer "intended."
    ---

    But this begs a host of questions. 1) Have you used your back properly? (i.e., if you misuse your back how is that a flaw with the design any more than driving your Buick into a brick wall is flaw in the design of the engine block?) 2) It likewise ignores the effects of sin, as Steve pointed out, although this aspect is irrelevant to the logical portion of my argument. 3) That certain things wear out over time is not an indication of poor design either (e.g., your car isn't designed to last forever yet that doesn't make it poorly designed).

    Bob said:
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    Yeah, anyone can deny propositions. I don't find your argument compelling.
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    I don't care if you find it compelling. I'm presenting a logical argument, and the validity of my logical argument doesn't depend on whether you like a specific outcome.

    Bob said:
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    If I deny one side of the disjunct, and I see no reason to believe your story, then it's not the case that the argument "proves nothing."
    ---

    Except that your mere denial of one side of the disjunct says nothing about the argument. Both sides of the disjunct remain logically possible, which is my very point. That you don't like one of them doesn't make it go away. That you don't believe one of them doesn't render it implausible.

    You can wave your hands all you want, it won't make the disjunct go away.

    Bob said:
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    You have to establish "godditit."
    ---

    No I don't. All I have to establish is that morphological similarities do not imply common descent, which I did. There are other things that can explain morphological similarities, and I've given you several already. I don't have to prove God did anything to make this point.

    On the other hand, you do have to prove that only evolution can cause morphological similarities in order to disprove the alternates in the disjunct. Have at it.

    Bob said:
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    My "it sucks" argument is just fine.
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    It's not an argument; it's emoting. And it is not "just fine" since it doesn't address the issue.

    Bob said:
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    If "goddidit" works for you, "it sucks" works for me.
    ---

    Since I've never used "goddidit" then, using the above correlation, you must refrain from using "it sucks".

    Now are you going to present an argument or are you just going to continue to sulk?

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  10. And at the risk of pointing out the obvious for dear old Bob, I've already given examples of evolutionary theory that denies morphological similarities = common descent. Namely, convergent evolution.

    Mayr talks a great deal about convergent evolution. Does that mean he's employing "goddidit", Bob?

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  11. Notice that the argument Bob presents is a metaphysical, not scientific, argument.

    Because the design is not perfect (according to Bob's specifications), and if there was a Creator, then He would have created according to Bob's specifications.

    Ergo, chancedidit.

    Darwinism is the humanist's creation-myth.

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  12. I simply expressed why scientists are amazed at certain facts within our universe. To take this as me giving an argument outside what was asked of me, is simply dishonest. Perhaps your noetic effects are getting the best of you guys?

    I was born with my bad back through no fault of my own. So, your only comeback at this point is to beg the question by bringing up the fall. Nice. I mean, who needs design? This world could be the most absurd, sloppy, undesigned world ever, and you could attribute it to "sin."

    I obviously never said that I denied the one disjunct because I "didn't like it." Apparently the "fall" is affecting your ability to judge my arguments. What I've done is a perfectly reasonable reason to proceed. Your side of the disjunct rests upon designer-god, and creation. I don't find any reason to believe that that took place (and no, pointing to a parking lot full of cars doesn't persuade me). Thus, for me, according to how I see the arguments, commonality _does_ provide evidence for Darwinism. That's all I was saying. Feel free to contort my position to suit yours.

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  13. Bob,

    Your arguments suck, therefore they are not the product of an intelligent designer.

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  14. Dear Peter,
    There is a lot of ground to cover concerning morphological similarities. I rejected creationism after going over loads of tiny details that were not accommodated by the hypothesis of separately created organisms.

    For instance, Human chromosome #2 contains evidence of having been formed from two separate chromosomes. The overall structure of that chromosome features evidence of a second centromere and telomeres inside that chromosome's midst where the joining of the two formerly separte chromosomes took place. There is no apparent reason to add the remnant of a second centromere and to add telomeres in the midst of such a chromosome, since chromosomes have and need only a single centromere to divide, and since telomeres lay only at the ends of other chromosomes and break off with age. There is no reason to have them in the midst, unless the chromosome is an example of one that was formed by a past fusion of two separate chromosomes. The biologist Kenneth Miller has lectured on this topic, and even presented it as evidence at the I.D. trial in Dover. The only explanation I've heard from creationists is that perhaps the joining of the chromosomes took place AFTER man had already been created, but in that case, man was originally created with the exact same number and length and banding patterns of the chromosomes of the chimpanzees which God had created just previous to creating the first male and female. So we were even nearer to the ape-kind to begin with and could have easily cross-mated with them "in the beginning" in Eden, say. But then we wouldn't be separate "kinds." Such questions go on and on.

    Secondly, I also investigated in detail creationist arguments for a young-earth and found them wanting, but that's another story. Let me just say that the relative order of in which fossils are found consists of early strata with single-celled bacteria fossils, and later multi-cellular, then worm-like organisms. The earliest fish were not like later fish, but barely had fins, and didn't have jaws either. The earliest vertebrate had a mere eye spot, and after fish with jaws there came amphibian-like fish with boney appendages, then the first amphibians (which still had fish-like characteristics and skull shapes including dorsal fins), and later, reptile-like amphibians, and then reptiles, then mammal-like reptiles, then mammals, first monkeys, then primitive apes, then hominids, then human beings, in that relative order. If not descended from one another over time, then the "Flood" did a helluva job sorting fossils in relative order, including even fossil fragments and micro-fossils as well, even sorting them according to the relative closeness of their genomes, their DNA, as modern day studies corroborate the relative fossil order.

    Neither were the early forms the most suited to the environment that the latter modern day forms would inhabit. For instance the earliest fossilized birds exhibit a heavy tringular shaped reptile-like skull with teeth, and long bony tailbones, neither of which made them great fliers, but added weight and drag. Neither did the earliest known fossil birds have a large keel bone running down their midst. They had relatively tiny keel bones to which smaller flight/flap muscles would have been attached. Neither were their wrist bones fused, so they would have had to exert more force to keep their wrists from flapping and ruining their flight patterns. So the earliest known fossilized birds were no where near as well adapted for flight as later species were. So the designer was what, starting out by designing things in baby steps over millions of years?

    The same goes for the earliest known cetacean fossils. They were were not as well adapted for a mammal living its whole life in the deep sea. The nostrils were only halfway up the snout, not at the tops of their heads yet. And their diminished rear appendages still created drag. Neither did they have any sonar bulges in their skulls. Those all came later. Even the krill sifting baleen wouldn't evolve until later in some species. But fossils exist of some of the transitional forms, such as an early whale with half teeth and half baleen. Even in the womb today, baleen whales begin by having teeth that are then reabsorbed and the baleen structure then forms. Heck, all cetacean embyoes also have hind limb buds as well that get reabsorbed, so the evidence still exists in their embryoes of their four-footed ancestors.

    Thirdly, consider the five-digits of your hands and feet we share with very nearly all amphibians, reptiles and mammals. The earliest amphibians in the fossil record had a variety of numbers of digits, from 5-7. Perhaps that's because the evolution of amphibians began with fish that didn't have a strict number of digits yet defined, so neither did the earliest amphibians in the fossil record. But the five-digit sequence won out at that point in the evolutionary branching, hence the later species of reptiles and mammals now have five digits instead of either five, six or seven as ancient amphibians had.

    Just some stuff to ponder. Also google: Christian Evolutionist Resources to find some fellow brethren to discuss such matters with, as I know you may be a bit more willing to take their word for it than mine. Kenneth Miller's got a new book coming out, his first was "Finding Darwin's God" and is worth perusing for the evidence for common ancestry section. Also, at least two major I.D. authors now fully agree that the evidence for common ancestry is strong, both Denton and Behe. Neither of them doubt common ancestry now, though Behe expressed some doubts ten years ago, he's now changed his mind in favor of agreeing with common ancestry, including being swayed by the evidence for cetacean evolution.

    Edward T. Babinski (I sent J.P. Holding something similar to this post over at Tweb a while back when he pursued a line of argumentation similar to your own.)

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  15. Hello, Ed.

    It appears that you are under the impression that I am a YEC. Otherwise, I'm not sure I see the relevance to much of what you've written to me.

    One thing I will address, you said:
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    I rejected creationism after going over loads of tiny details that were not accommodated by the hypothesis of separately created organisms.
    ---

    I wonder if you ever considered, when you held to the belief of separately created organisms, how this would have been accomplished. That is, it appears to me that many naive Creationists view distinct creation as a process that ought to have no overlap at all, and I presume you may have thought the same.

    This is not how I view it.

    The fact is, there are only a certain limited number of combinations and patterns that molecules can bind together in. There are only four bases used in DNA, and there are only twenty amino acids. Every living organism is built from these same particles.

    Pretend that they are Lego blocks, for instance. If you are going to build an object out of Legos and you want to it to do a certain function, you'll use certain types of blocks. If you build another object that does a similar function, would it not necessarily look similar and use the same types of blocks, etc.?

    The fact is, if someone designed two organisms that behave similarly, I would expect there to be similarities in the DNA structure, etc. since a designer isn't necessarily going to ad hoc invent different rules for everything he is creating. These similarities are not ipso facto evidence for common descent any more than they are evidence for common design. That is my point of this whole post.

    If the same evidence can be used by two contradictory parties, then that specific evidence is unable to be the determining factor in deciding between the two positions. Since this is the strongest evidence that Darwinists put forth, I conclude Darwinism is pretty weak.

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  16. The fact is, there are only a certain limited number of combinations and patterns that molecules can bind together in.

    I'm sorry, Peter, but this is just silly. The degrees of freedom in building organisms from scratch is nearly infinite to an infinite God.

    There are only four bases used in DNA, and there are only twenty amino acids. Every living organism is built from these same particles.

    And you seem to be missing this as an obvious clue: God made everything from the exact same set of materials...something that is an absolute requirement if common ancestry is true, and something that is not required in any wise if it is not.

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  17. I would note in passing that many of the objections leveled by Babinski, as well as "The Badger," have already been addressed in the new textbook by Dembski and Wells, entitled The Design of Life.

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  18. The Badger said:
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    I'm sorry, Peter, but this is just silly.
    ---

    I agree. Your objection is silly.

    You said:
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    The degrees of freedom in building organisms from scratch is nearly infinite to an infinite God.
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    How is this an argument against my position? That God could have done otherwise doesn't mean He must have done otherwise. This is just a stupid assertion on your part.

    You said:
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    And you seem to be missing this as an obvious clue: God made everything from the exact same set of materials...something that is an absolute requirement if common ancestry is true, and something that is not required in any wise if it is not.
    ---

    That is only a clue if you can show why God must do something the way that you want Him to do something.

    God creating everything with the same building blocks is a perfectly consistent notion. Why should God create different processes for everything, especially if God wishes to communicate with His creation? How are we to learn the laws of logic if there are no laws governing matter, and hence by extention how are we to learn to communicate with God without these in place? And this is just one simple explanation of those events.

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  19. Steve: "I would note in passing that many of the objections leveled by Babinski, as well as "The Badger," have already been addressed in the new textbook by Dembski and Wells, entitled The Design of Life."

    You can read about this new book right here.

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  20. Like anyone cares about the number of stars a reviewer on Amazon.com gives an item.

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  21. You can read about this new book right here.

    Wow! Dembski's in there trying to give his own book a high review rating. And he's doing it under the guise of anonymous reviewers! What an amazingly small mind he must have.

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  22. I'd also like to point out a book relevant to the topic:

    "Darwin's God" by Cornelius Hunter

    He points out that all of the arguments for Darwinism rely on a theodicy and view of God in general that is foreign to the Bible but was spawned by 19th century natural theologians.

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  23. "Wow! Dembski's in there trying to give his own book a high review rating. And he's doing it under the guise of anonymous reviewers! What an amazingly small mind he must have."

    Wow! Darwinists giving the book a one-star rating without having actually *read* the book. What an amazingly small mind they must have.

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  24. S&S Said:
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    He points out that all of the arguments for Darwinism rely on a theodicy and view of God in general that is foreign to the Bible but was spawned by 19th century natural theologians.
    ---

    This is an excellent point that is often overlooked.

    Darwinists are lousy theologians and almost all of their arguments against God rely on a caricature of God.

    By the way, have you ever noticed that Darwinists are quick to jump back and say, "Even if you disprove Evolution that won't make God real" but then they go off and operate on the idea that if Evolution then ~God?

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  25. "By the way, have you ever noticed that Darwinists are quick to jump back and say, "Even if you disprove Evolution that won't make God real" but then they go off and operate on the idea that if Evolution then ~God?"

    Yeah. They always have the 'goddidit' but never the 'chancedidit' or 'naturalselectiondidit' (though the latter is quite apparent in their just-so stories).

    In the end, they're operating on the assumption that a natural explanation, no matter how far-fetched, should be accepted before a non-supernatural one. This then begs the very question under dispute.

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  26. Dembski's in there trying to give his own book a high review rating. And he's doing it under the guise of anonymous reviewers!

    --------------

    No wonder Steve Hays plugs this book! It's written by someone after his own heart!

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  27. I notice that critics are referring to book *reviews* rather than the book itself. Clearly they haven't read it.

    They allow their opinions of the book to be spoonfed to them by hostile reviewers. Ironic that freethinkers exhibit such groupthink.

    I own the book. I've read it. If you want to attack the book, you need to attack the actual book. Interact with the arguments in the text and CD-ROM which comes with the book. Otherwise, you're just blowing smoke.

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  28. bob said...

    “I simply expressed why scientists are amazed at certain facts within our universe. To take this as me giving an argument outside what was asked of me, is simply dishonest. Perhaps your noetic effects are getting the best of you guys?… Apparently the ‘fall’ is affecting your ability to judge my arguments. What I've done is a perfectly reasonable reason to proceed.”

    This is what you originally said:

    “Except that the ‘designed’ similarities are not evidence of a good-smart-god-design because they suck..”

    If we try to turn your objection into something resembling an argument, it would go something like this:

    i) There are various unspecified maladaptations in nature.
    ii) If nature was designed by God, then these are design flaws.
    iii) Ergo, God doesn’t exist.

    I, then, building on your own argument, asked you if you regard yourself as poorly engineered.

    You responded as follows:

    “Who am I to say it sucks? Me and my bad back.”

    One of the problems with that response is that it’s overly restrictive. Why do you limit suboptimal adaptations (as you view them) to a bad back rather than, say, a bad brain?

    Why wouldn’t your argument also undermine the reliability of human reason itself? According to you, the brain is a product of the same defective process that produced your bad back.

    “I guess that's what the designer ‘intended’."

    Yes, according to Scripture, natural evils were part of God’s plan for the world.

    “I was born with my bad back through no fault of my own.”

    You can blame that on Adam, and if Adam hadn’t sinned, Bob wouldn’t even exist. In an unfallen world, someone else, without a bad back, would exist in Bob’s place.

    “So, your only comeback at this point is to beg the question by bringing up the fall.”

    What question does that beg?

    “Nice. I mean, who needs design? This world could be the most absurd, sloppy, undesigned world ever, and you could attribute it to ‘sin’."

    The Bible is well aware of birth defects. People born blind, or deaf, &c. Jesus spent a lot of time healing the sick. So the existence of natural evils is not a defeater or undercutter for Biblical theology.

    At it is not ad hoc for me to mention this. This is not something I improvised on the spot to deflect your objection.

    Finally, teleology and dysteleology are asymmetrical. For dysteleology is, itself, a teleological category.

    You can’t point to suboptimal adaptations without tacit reliance on a teleological framework. If the “Watchmaker” is truly blind, then there’s no distinction between optimal and suboptimal adaptation. So you yourself are having to assume in your premise what you deny in your conclusion.

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  29. ETB said:

    Human chromosome #2 contains evidence of having been formed from two separate chromosomes.

    This and the other points in ETB's comment beg the question.
    What evidence could you bring forward to argue that this isn't the result of design?
    On what basis would that evidence be scientific and not metaphysical?

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  30. W. J. Tiffman1/03/2008 9:47 AM

    "If you want to attack the book, you need to attack the actual book."

    I've read the book, and I've read other writings of Dumbski's. And I've read the reviews, both positive and negative. The negative reviews are quite accurate - if anything, they're understated. Overall, Dumbski is a waste of time. As a visiting associate professor in the sciences, I've not found anyone in the sciences who take him seriously. Sorry for the bad news, but them's the breaks.

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  31. hemulds said:

    "Dembski's in there trying to give his own book a high review rating. And he's doing it under the guise of anonymous reviewers!"

    How would you be in a position to know the identity of anonymous reviewers?

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  32. w. j. tiffman said...

    “I've read the book, and I've read other writings of Dumbski's. And I've read the reviews, both positive and negative. The negative reviews are quite accurate - if anything, they're understated. Overall, Dumbski is a waste of time.”

    Notice that Tiffman merely characterized the book. He doesn’t begin to interact with the argumentation. So he’s just a poseur.

    “As a visiting associate professor in the sciences, I've not found anyone in the sciences who take him seriously. Sorry for the bad news, but them's the breaks.”

    This is demonstrably false. Dembski’s books typically come highly recommended by experts in various fields of science. Men far more distinguished than some adjunct science prof.

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  33. Could you please provide more biological evidence for this?

    I plan to use this argument some time in the future but I would like to have better examples than just cars in a parking lot.

    Thanks!

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  34. The reason for the cars in the parking lot is because it's a structure that is indisputably designed. We know who the designers are, and we know that the product is designed. The same is true for many other aspects that look similar: Macs & PCs, iPods and Zunes, etc. They have morphological similarities but we know they have been intentionally designed that way (BTW: they've also been put into a market and are under sales pressures, which can mimic Darwinistic principals wherein the products that are bought more often are the products that are cloned more often, with the end result being intelligently directed Darwinism at Target...)

    Obviously, I believe many structures of the cell demonstrate design too; but these are disputed by Darwinists. I'm planning a post in the near future on one of these, but until then you can focus on the other aspects where Darwinists admit that morphological similarities do not imply descent. Here are just three examples from three evolutionists:

    ---
    It had been shown by morphological-phylogenetic research that photoreceptor organs (eyes) had developed at least 40 times independently during the evolution of animal diversity. A developmental geneticist, however, showed that all animals with eyes have the same regulatory gene, Pax 6, which organizes the construction of the eye. It was therefore at first concluded that all eyes were derrived from a single ancestral eye with the Pax 6 gene. But then the geneticist also found Pax 6 in species without eyes, and proposed that they must have descended from ancestors with eyes. However, this scenario teruned out to be quite improbable and the wide distribution of Pax 6, even before the origin of eyes, had an unknown function in eyeless organisms, and was subsequently recruited for its role as an eye organizer (Mayr, What Evolution Is, p. 113).
    ---

    ---
    If we are going to accept an exclusive [genetic] human-chimp association, then we are going to have to accept the consequences that go along with it. The most profound consequence is, I think, that morphology has to be viewed as unrevealing when it comes to resolving the evolutionary relationships of organisms. Otherwise, the uniquenesses shared by chimps and gorillas, especially in their forearm anatomy, provide overwhelming evidence of their close evolutionary relationship. If we accept molecularly based phylogenies exclusively, and not as potential alternative hypotheses, we must reject fossils as being informative sources of data, because fossils are known only as preserved morphological entitites. And, thus, because fossils cannot be placed reliably in schemes of phylogenetic relationships--that can result only from a morphological analysis--they cannot be used to provide dates from which to calibrate any evolutionary clock, molecular or otherwise (Schwartz, What The Bones Tell Us, p. 262).
    ---

    ---
    The striking similarity of structure shared by all birds must reflect a response to a similar set of adaptive pressures. It is easy to see that flight is the principal source of these pressures. Almost all birds fly, and those that are flightless are secondarily flightless. That is, they show signs of having evolved from flying ancestors. As far as we know, no bird alive today is primarily flightless.

    Heavier-than-air flight is an extremely energetic and dangerous activity. Natural selection will cull any flying animal not perfectly adapted to the task. This means that all birds will come to look rather similar, despite any differences in heritage (Gee, In Search of Deep Time, p. 156).
    ---

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  35. biblelighthouse1/09/2008 1:15 AM

    There are at least 3 fallacies I see in this particular blog post regarding morphological similarities. . . . http://www.biblelighthouse.com/forum/viewthread.php?tid=1583

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