May 17 2013

An Interview with Don McLeroy, Part IV

This is the fourth is a series of posts analyzing the claims of Don McLeroy, former chairman of the Texas School Board of Education and young Earth creationist. I recently interviewed Don on the SGU about his successful insertion into the Texas science textbook standards language requiring books to address stasis and suddenness in the fossil record and the complexity of the cell.

In parts 2 and 3 I addressed Don’s stasis and suddenness arguments. They are classic denialist fallacies – focusing on lower order details as if they call into question higher order patterns (they don’t). In this case, Don is arguing that the fact that many (not all) species display relative morphological stability in the fossil record, with episodes of (geologically) rapid speciation events, calls into question the bigger picture of the change of species over time in an exquisitely evolutionary pattern.

The former is a reflection of the tempo of evolutionary change and an artifact of the fossil record, while the latter is home-run unequivocal evidence for common descent and evolutionary change. Don has not provided any explanation for why the pattern of change we see in the fossil record presents any problems for evolutionary theory.

In this post I will address Don’ other main point, which he feels is the greatest weakness of evolutionary theory – the complexity of the cell. His premise seems to be that, if evolution were true, then evolutionary biologists should be able to provide detailed evidence for the specific evolutionary history of many biochemical pathways and cell structures. He argues that they cannot, and therefore the evidence for evolution is weak.

Before I get into what the current evidence for the evolution of cellular complexity is, let me address the logic of Don’s position. First – his major premise is false, and therefore his argument is not sound. Evolution can be true even if we are currently unable to provide robust evidence for the evolution of biochemical pathways.

His false premise reflects a misunderstanding of how science operates. Science operates by posing testable hypotheses. Often the greatest challenge for scientists is to figure out a practical method for testing their ideas. They generally start by picking the low-hanging fruit – looking where the evidence is robust and accessible.

In other words, biologists ask – if evolution is true, then what should the evidence we do have look like? They then see if the evidence matches the predictions of evolution.

If the theory makes predictions about evidence that we are unable to obtain, for practical reasons, this is not a weakness of the theory or evidence that it is wrong, it is simply a reflection of practicality.

Life on Earth is at least 3.4 billion years old. Multicellular creatures first appear in the fossil record about 540 million years ago. That means that most of the history of life on Earth, about 3 billion years, was nothing but single-celled creatures. That is a very long time in which to evolve biochemical pathways and cellular complexity – more that 5 times as long as it took to get from a single cell to a person.

Cells, proteins, RNA, organelles, and biochemical pathways do not fossilize. They are scantly preserved at all. We are therefore limited in our ability to reconstruct the evolutionary history of billions of years of evolution on this scale.

Scientists only have a few methods available from which to infer the evolutionary history of cell structures and biochemical pathways. The main method is to look for patterns in living organisms. By analyzing thousands of species they can partially reconstruct the evolutionary tree.

Perhaps the best method available is genetic analysis. Genes are a sort of fossil – they do record to some degree their evolutionary past. We can see when genes duplicated and then evolved to take on new functions. We can sometimes see inactivated genes, truly fossil genes, and infer past function from them.

Scientists can also investigate plausible pathways – they can demonstrate the functionality of possible antecedents to current biochemical pathways or structures. This is not the same as evidence for the actual evolutionary pathway to current complexity, it just shows possible pathways.

In short scientists are doing the best they can unraveling an extremely complex picture with the relatively little evidence available to them.

An unbiased way to approach this evidence is to ask – does the evidence we do have support evolutionary theory? Is any biochemical evidence incompatible with evolution? The answers are yes and no – what evidence we have supports evolution, and there is nothing that is incompatible with evolution.

Don is not asking those questions, however. He is not really asking any cogent question. He is simply asserting that the paucity of evidence for cellular and biochemical complexity is evidence of the weakness of evolutionary theory. It clearly isn’t.

Further, Don’s assessment of the current state of the evidence is extremely flawed. He is using popular books and high-school level textbooks as if they were an accurate reflection of the current state of the evidence. The evolution of cellular and biochemical complexity is a very advanced area of biology. I would argue it is not suitable for a high-school level textbook. Any treatment of it at that level, and in popular writing, is by necessity superficial. Don is taking this superficiality as evidence for weakness of evidence.

This also gets to another flaw in Don’s reasoning – his belief that he, as a dentist and engineer, can reasonably challenge the conclusions of the broad scientific community. Many scientists have dedicated their careers to studying evolution, and even tiny areas of the evolution of certain biochemical pathways. They are steeped in a highly technical literature. It is a fatal mistake to confuse familiarity with popular writings with deep knowledge of the technical literature.

Of course, scientists can be wrong, and the consensus does at times change. But there are many scientific consensuses that have not changed in decades and will probably never be overturned. DNA is the substrate of inheritance, for example. The brain is the organ of the mind. The Earth and Sun revolve about their center of gravity. Stars are fueled by nuclear fusion. None of these conclusions are going anywhere. New knowledge about the details of genetics or star mechanics do not threaten the more basic conclusions.

Likewise – all life on Earth is related through common descent. Life changes over geological time in an evolutionary pattern. These scientific conclusions are as solid as any in science, and are not going anywhere. The details of what evolved from what and how are another layer to evolutionary history, but don’t address the higher order conclusions.

What is the current evidence base for the evolution of biochemical pathways? Well, I am no expert, and so I am in no position to give a definitive answer to this question. But as a familiar lay person, I am aware of much more evidence than Don claims exists.

Here, for example, is an interesting technical review – Biochemical Pathways in Procaryotes can be Traced Backwards through Evolution Time. The paper reviews current knowledge about aromatic biosynthesis, DAHP synthase, PABA synthase, and many others.

Here is an overview and list of technical papers on the evolution of eukaryotic pathways by endosymbiosiss of prokaryotes.

Here is another paper, the main conclusion of which is that as biochemical pathways evolved, cells became less dependent on exogenous material and more independent.

This brings up another major premise implied by many of Don’s statements, and typical of creationist arguments. Essentially he echoes the “irreducible complexity” arguments of Michael Behe – how could the cell have functioned prior to developing critical complexity? This is addressed by the plausibility research, as with the paper above, showing that simpler pathways and structures were perfectly functional, just inefficient. RNA can replicate itself without ribosomes, just slowly. As complexity developed, cell metabolism became faster, more efficient, and less dependent on specific nutrients from the environment (although, of course, not completely).


The final pillar of Don’s argument, reflected in his proposed changes to science textbooks, has now collapsed. His premises are faulty, his logic is not valid, and therefore his arguments are not sound. He neither understands or accurately represents the process of science or the current findings of evolutionary biology. He further uses popular writing and high-school level textbooks as if they represent the technical literature.

Don also gives away a major flaw in his approach – during the interview I accused him of criticizing one of the weaker legs of support for evolutionary theory, and he essentially responded that of course he is. This is not a scientific approach, however.

The relevant question is – how robust is the scientific evidence for common descent and evolutionary change, and how solid are our current conclusions? In order to answer this question you have to look at all the evidence. When you look at evidence from fossils, geology, genetics, developmental biology, the morphology of living organisms, and laboratory experiments on short term evolutionary change, the picture that emerges is one of highly robust evidence all firmly pointing to evolution as the conclusion. Further, there is no alternative scientific theory that is even compatible with evidence, let alone predicts the evidence.

Evolutionary theory is  a solid scientific conclusion, without rival.

The robustness of the different types of evidence reflects only our practical ability to get at the evidence – not the predictive power of evolutionary theory.

As a research paradigm, evolution has proven to be very powerful and successful. It shows no signs of ever being overturned – no more so than any foundational scientific theory.

Don’s arguments, which are those of the creationist/ID mainstream, reflect pure pseudoscientific denialism.

29 responses so far

29 thoughts on “An Interview with Don McLeroy, Part IV”

  1. daedalus2u says:

    A good argument against irreducible complexity is the heart. The heart is a structure that supposedly is irreducibly complex, except we know it isn’t. We know that every heart grows in an organism that starts out as a single cell. If a heart was irreducibly complex, then it would have to “poof” into existence at that irreducibly complex state. If the heart is irreducibly complex, then Creation Scientists should have videos of hearts “poofing” into existence.

  2. Survivalist13 says:

    Steve makes a thorough and well thought out argument. I eagerly await Don’s reply.

  3. oldmanjenkins says:

    It appears Don is credulous in his thinking. His position rests on the ultimate answer “god exists.” In fact his entire argument rests on this specific conclusion. For Don to accept that evolution explains life on this planet is to deny god. IMO they (YEC’s) have great difficulty in saying either “I don’t understand” or “I/we don’t know.” Since he/they don’t understand evolution or some aspect of evolution does not provide an answer, then godidit. It’s god of the gaps. Science is a beautiful way to explain things, and to investigate where the answer is either incomplete or is lacking. Science will tell you when it does not have an answer. Some say science is cold, but that implies malicious intent. Science is reality, the way things truly are. Whether the YEC’s chose to accept it does not change the outcome. It appears to me as well they believe the Theory of Evolution is a house of cards. If one part of the Theory is revised or is incomplete then the entire Theory crumbles. “Eppur si muove” is not just a statement attributed to Galileo, it is the assertion that even if you deny that which science presents no matter how much you ignore it, no matter how much you “spin” the evidence to “fit” what your claim is…..eppur si muove!

  4. Bruce Woodward says:

    @jenkins, I would argue that you can believe in god and understand and accept evolution. I see no argument to claiming that god is the master of science and created the world with it’s physics and chemistry and biology and evolution and natural beauty and ugliness as all part of a master plan.

    Obviously this is still a massive god in the gaps argument, but it is not falsifiable and much more intellectually honest.

  5. @daedalus2u, the irreducible complexity argument that I usually see is regarding eyes or wings. “What good is half an eye or half a wing?” they ask rhetorically. Umm, half an eye is way better than no eye at all. Half a wing will let you fly a little bit, run faster, jump higher, etc. Lots of good uses for half of things, and would definitely provide survival and reproductive advantages in most environments.

    So hearts, eyes, and wings are 3 examples of irreducible complexity that actually aren’t irreducibly complex and that we can quite clearly trace their development through evolutionary history.

  6. steve12 says:

    Am I the only one who finds this irritating?

    I guess I should like the idea of people discussing these issues in a civil manner. But I don’t. This is like me getting into an argument with my mechanic about how to fix my car, when I in fact have no idea how my car works. It would be pointless for him to argue with me when I have no idea what I’m talking about, wouldn’t it?

    McLeroy doesn’t even understand philosophically what science is, as his comments on naturalism attest. So you have someone who has neither the technical chops nor the broader understanding. But he has an opinion – they always do. Aren’t these Christians supposed to have some humility?

    On top of that, they’re lying about their premises, right to your face – and this is the final straw for me. They constantly say it’s not religious, but everyone – including them – knows they’re full of shit. I find that kind of insulting.

    I suppose Steve’s trying to convince people who are on the fence, not this McLeroy character. I know this: he has a lot more patience than I do.

  7. bulvaii says:

    These arguments concerning biochemical pathways strike me as simply another form of the “missing link” criticism. Just as creationists can walk down a hall filled with transitional fossils while proclaiming how evolution has failed to produce the “missing link”, Don can read books and books detailing powerful lines of evidence while decreeing it allto be meaningless unless this one aspect of evolution is thoroughly demonstrated. There will always be knowledge gaps in our understanding of specific processes just as we cannot possibly find every transitional phase of every species, and in these crevices the creationist arguments will always lurk.
    I have no doubt that if stronger and more plentiful evidence for biochemical complexity emerged, it would only lead to creationists declaring it to simply open up more questions in need of answers to prove the theory convincing.
    Yet another manifestation of a tired denialist strategy.

  8. pdeboer says:

    It’s interesting to see Don caught between denialism and rationality.

    He’s give up just about every point he has, when he’s hard pressed.

    If you press him hard enough until he gives up every point he feels is of substance, will he be able to put the big picture together and conclude that he has been wrong, or will he slip into the more petty denialist techniques?

    I have not noticed him move the goal post. So far so good.

  9. BuckarooSamurai says:

    In regards to cell complexity as Don calls it, even though we all know he is dancing around using term irreducible complexity, I’d point out we don’t even have to use arguments against questions like; “what good is half a wing?”. Irreducible complexity was dealt with approximately 100 years ago.

    or to summerize:

    A clear example of the Mullerian two-step is given by a stone bridge. Consider a crude “precursor bridge” made of three stones. This bridge spans the area needed to be crossed and is thus functional. For step one of the Mullerian two-step, a part is added: a flat stone on top, covering all precursor stones. Whether this improves the functionality of the bridge is irrelevant — it may or may not, the bridge still functions. For step two of the Mullerian two-step, the middle stone is removed. Voilá, we have an irreducibly complex bridge, since the last step made the top-stone necessary for the function.

  10. daedalus2u says:

    I think the heart is considered irreducibly complex because the heart supplies blood for its own operation. How can a mass of tissue without a blood supply beat and supply itself with blood by beating? The YEC says it can’t, therefore God. The scientist says “I don’t know” and watches a heart during development in a transparent organism like a zebra fish and finds out.

    If a heart can develop from zero heart cells to many heart cells, why can’t a heart evolve from zero heart cells to many heart cells?

  11. lfvvb says:

    Steve, I would like to add the immense body of evidence that experimental directed evolution in bacteria has provided for the evolution of biochemical complexity in the cell.


  12. RickK says:


    I’m with you. I’m disgusted by someone who cares so little about intellectual honesty and who is either lying or afraid to question his own beliefs. Don is so concerned about protecting his ideological shell that he’s quite happy to spout nonsense, inaccuracies and falsehoods.

    If someone spends so much energy spewing BS in one dimension of his life, how can anyone trust anything he says in any other part of his life?

    Part of being trustworthy is at least making an attempt to be correct.

  13. Robert says:

    I think Don’s arguments sound a little indicative of the Dunning-Kruger effect, and similar to a lot of the “internet scientists” who seek to overturn solid scientific ideas with little or no in depth knowledge about the subject area. If he is genuinely basing his ideas on high school level science this is a big mistake, from experience I know that in physics there are a lot of things which are taught at high school which are approximations and simplified versions which can be more easily understood.

  14. ccbowers says:

    “If the heart is irreducibly complex, then Creation Scientists should have videos of hearts “poofing” into existence….

    Actually poofing into existence is exactly what creationists have in mind, and that is why they find the irrudibly complex argument compelling.

    “If a heart can develop from zero heart cells to many heart cells, why can’t a heart evolve from zero heart cells to many heart cells?”

    Of course it can, and it has since hearts exist. I would guess that creationists would argue that during development, the mother is providing the ‘services’ that the heart provides while it is developing, at least in many organisms such as mammals. The evolution of a circulatory system is not hard to imagine. A circulatory system is a way of moving nutrients, gases, and waste around so they get where you want them to go faster and more precisely. Without a circulatory system, an organism would have to relay on diffusion primarily for this function. Prior to the heart evolving, even the development of a moving area of tissue to move fluids around in the organism could have been beneficial to a small mulicellular animal, and in fact there are many examples of this today.

    The irriducibly complexity argument is a specific form of ‘argument from incredulity,’ and references to complexity being a problem are really variations of this faulty argument.

    Actually while I was typing this I found an article titled
    “Evolution of the heart from bacteria to man,” which gives an overview of the topic:

  15. BillyJoe7 says:

    I’ve just come across this quote from Isaac Asimov in my weekend reading.

    Imagine the people who believe such things and who are not ashamed to ignore, totally, all the patient findings of thinking minds through all the centuries since the Bible was written. And it is these ignorant people, the most uneducated, the most unimaginative, the most unthinking among us, who would make themselves the guides and leaders of us all; who would force their feeble and childish beliefs on us; who would invade our schools and libraries and homes. I personally resent it bitterly.

    Remind you of someone?

  16. norrisL says:

    Faith has nothing to do with science, but faith is where people like the Donster get much of their scientific information from. What’s that book called? Ah, yes, the bible. Full of so many contradictions, that if it was a scientific book, it would not get past an initial examination by an editor.

    eg: for god so loved the world that he sent a big flood and drowned everyone on earth, except for Noah and his family.

    Note to self, check up on how Noah’s family procreated after the big flood when every other family had been drowned .The same applies to Adam and Eve who were the first humans created by the godster. Seems like Kane must have procreated with……his MOTHER and Noah’s sons must have procreated with their MOTHER, or did they have sisters? Either way, blech!

    Who could believe any of the crap in the bible, and crap is what it is.

    What do creationists say about the fact that human embryos develop gills and some human babies are born with such a large tail that it requires amputation?

    steve12, christians, and I am quite sure almost every other religion on earth, claim to have humility, but of course, the untruth of this becomes clear when they get into a civilised debate that goes against them.

    I was going to say that there is no use debating clowns, but I guess, as someone else said in the comments above, we might change the mind of the odd fence sitter.

    My view on religion is that it is one of the worst evils inflicted upon humans by humans. Teaching small children that there is some supernatural deity who knows everything they do and even think, even if that thought blinks into their mind for a mere instant, that the deity will then send them to burn in hell forever amounts to nothing more than some of the worst child abuse imagineable.

  17. says:

    This is my first post to the NeuroLogica Blog.

    I listened to the interview with Don McLeroy today while driving in driving rain.

    But that doesn’t really account for the irritation I felt.

    All the best counter-arguments have been taken in other comments.

    Perhaps I felt a sense of this interviewee being maybe the best opponent I have heard in such a debate. It’s usually easy to dismiss creationists. But this guy’s fallacies were more subtle than most. Such as conflating “underlying” in the physically subvenient sense with “underlying” in the logical inference sense.

    He didn’t land any body blows against evolution, which was a plus side of a discussion with such a capable opponent.

    And while I know he was separating his theism from his opposition to evolution (and motivation is bordering on an ad hominem argument) I do wonder why no theist questions why their god hasn’t created a website, an email account, a Twitter account, or even a Facebook account. It would be so easy for such a god to convey some really convincing evidence for his existence. So easy. He could even communicate privately to his own elect, who could make some amazing predictions as to where to find amazing fossils. Perhaps he would even explain exactly how he created a cell.

  18. BillyJoe7 says:

    I must admit, I missed the equivocation over ‘underlying’.
    Out of interest, where did he do that?

  19. Jim Shaver says:

    Steve, here’s one typo you might want to correct in the penultimate paragraph:

    “As a research paradigm, evolution has proven to be very powerful and successful. He shows no signs of ever being overturned – no more so than any foundational scientific theory.”

    It should read, “This theory shows no signs of ever being overturned…”


  20. Davdoodles says: “And while I know he was separating his theism from his opposition to evolution (and motivation is bordering on an ad hominem argument) I do wonder why no theist questions why their god hasn’t created a website, an email account, a Twitter account, or even a Facebook account. It would be so easy for such a god to convey some really convincing evidence for his existence. So easy. He could even communicate privately to his own elect, who could make some amazing predictions as to where to find amazing fossils. Perhaps he would even explain exactly how he created a cell.”

    But, you see, god works in mysterious ways, with one strict exception: Its “ways”, and the results thereof, are always indistinguishable from the non-existence of god.

    What religious people call “faith”.

  21. cbecke says:

    Does Don Mcleroy realize that if his tactics were applied to his own beliefs, they would disprove the Bible? Since Don can’t tell us what Jesus had for breakfast the day of his seventeenth birthday, the biblical evidence is incomplete and therefore cannot be believed.

  22. sonic says:

    These comments are not intended to endorse a literal reading of the bible (YEC)-

    I have looked at a number of current attempts to explain cell complexity- including those linked to by Dr. N.
    I am reminded of when I read Lynn Margulis book- very interesting stuff, but–

    I find the evidence and explanations less convincing than the evidence and expalnation for gravity(general relativity), quantum mechanics, the periodic table, the composition of water, ohm’s law, boyle’s law,…in fact I find the expalnations less convincing than anything that has been demonstrated experimentally.

    That is a rather long list.

    I would note this-
    Carl Woese, who originated the RNA hypothesis as well as identifying Archaea and horizontal gene transfer, had a number of interesting things to say on this subject (including an endorsement of Shapiro’s ideas ..)

    Is it really hard to maintain serious doubt in circumstances like this?

  23. Sonic – None of the examples you gave are historical sciences. Perhaps you are just unfamiliar or uncomfortable with the methods of historical sciences.

    And are you just talking about the complexity of the cell or evolution in total?

    Woes comments don’t have anything to do with common descent or the basic idea of evolution. He is talking about the relative contributions of various mechanisms. Citing that as reason for serious doubt is absurd – a classic denialist strategy.

  24. BillyJoe7 says:

    “These comments are not intended to endorse a literal reading of the bible (YEC)”
    Even I don’t think you’re that bad. |:

    “Carl Woese, who originated the RNA hypothesis as well as identifying Archaea and horizontal gene transfer, had a number of interesting things to say on this subject…
    So interesting there’s not a single comment after six months.

    “(including an endorsement of Shapiro’s ideas ..)”
    Oh dear…

  25. Jared Olsen says:

    This is relatively off topic, and a blatant and shameful Ad Hominem, but I propose we change the term
    Young Earth Creationist (YEC) to Young Universe Creationist (YUC). 😉

  26. sonic says:

    Dr. N.-
    I do find ‘historical’ sciences less convincing than experimental science.
    Shouldn’t everyone?

    The interview with Woese I linked to where common descent is ‘chiefly grounded in analogy’ and ‘Shapiro’s ideas represent the future’ and ‘Darwin could go the way of Freud’…

    Evolution had been defined as ‘common descent through unguided process’, right?
    But that’s what those statements bring into question- not that life forms have changed overtime–

    To clarify– I find the explanations for complexity less convincing that anything ever demonstrated experimentally. While they might be plausible- and even correct– the most basic ‘show me’ is missing. That’s what impresses me about science– the ability to demonstrate the principles through experiment.
    Missing in this case.

    A side point is that Woese– who is most associated with the explanations for complexity– seemingly also questioned both ‘common descent’ and the ‘unguided’ nature of evolution as the interview linked to indicates.

    Perhaps it is more clear how I could maintain doubt given the situation above.

  27. sonic says:

    When Woese mentions Shapiro, he is questioning that evolution is ‘unguided’, correct?
    Is it ‘denialist’ to notice that?
    I’m asking you because I think you are aware of Shapiro and you know the usage of the word ‘denialist’ better than I do–

    And don’t you just love that closing remark Woese made? 🙂

  28. BillyJoe7 says:


    “When Woese mentions Shapiro, he is questioning that evolution is ‘unguided’, correct?”


    Shapiro is grounded in microbiology where he is an expert, but he has strayed into the foreign fields of evolution and evolutionary biology where he has no grounding whatsoever. As a result he has come to unwarranted conclusions. He has also created a popular following, not through peer review, but through direct appeals to the public through venues such as the Huffington Post. It has gotmto the stage where it would now be impossible for him to retract from his position which it is possible for him to continue to maintain only through a process of cognitive dissonance.

    “Is it ‘denialist’ to notice that?”


    But it’s denialism for you to continue to believe in Shapiro’s long discredited argument when it has been explained to you, time and again, how “Darwinian” mechanisms can fully account for all the features that microbiologists like Shapiro complain require a paradigm shift in thinking about evolution.
    This is especially so when you have never, to my knowledge, raised any counter-argument to the “Darwinian” explanation or provided an alternative mechanism but, instead, just continue to repeat Shapiro’s long discredited mantra.

    “I’m asking you because I think you are aware of Shapiro and you know the usage of the word ‘denialist’ better than I do”

    You just don’t recognise the word ‘denialism’ because you’ve hidden it undeservedly behind the word ‘doubt’. Shapiro raises no reasons to doubt random mutation and natural selection as the mechanism of evolutionary change characterised by common descent.

  29. jcgooch says:

    This attacking of specific targeted weaknesses strikes me as analogous to a defense lawyer attempting to prevent a murder conviction when you have: a) a murder weapon, b) finger prints on the murder weapon, c) witness testimony, d) a confession, but are unable to pin down the time of death between 4:00 PM and 5:00 PM.

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