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The Edge of Evolution

"There's a lot more to modern evolutionary theory than natural selection. The problem with natural selection is that if it explains everything, it explains nothing, and instead it becomes an exercise in story telling." (1).

Either Design or Common Descent

Michael Behe (2007) The Edge of Evolution.
The Search for the Limits of Darwinism, Free Press.

Review by Gert Korthof, 22 July 2007 (1 correction 17 Oct, note added 24 jan 2013)

Common Descent is based on genetic continuity in the history of life on earth. Design, according to Michael Behe, is based on genetic discontinuities in the Tree of Life. Therefore, Design and Common Descent are not compatible. Make your choice: it is either Design or Common Descent. Contrary to Behe, both cannot be true.
  1. The Search for Intelligent Design Theory
  2. Design conflicts with common descent
  3. Behe's evidence for common descent
  4. The link between design and the limitations
  5. Are common descent and the mechanism independent?
  6. Common Descent evidence depends on random mutation
  7. What Darwinism can do: random mutation and natural selection
  8. What Darwinism can't do
  9. Designed barriers to the origin and evolution of life?
  10. DNA and randomness
  11. 'The-Designer-Wouldn't-Do-That' argument
  12. Malaria, morality and education
  13. Conclusions

      1. The Search for Intelligent Design Theory

Readers interested in "Intelligent Design Theory" will be disappointed. The reader won't find an exposition of the Intelligent Design Theory. Nine out of ten chapters are about the limitations of neo-Darwinian evolution and the last chapter is about fine-tuning. There is no chapter devoted to design theory. Not even one paragraph describing what design theory actually is. Remarkably, the word "design" does not even appear in the title of the book. Despite the fact that Behe presents himself as an "Intelligent Design proponent". However, I found that the words "intelligent" and "design" do appear frequently in the book:

    intelligent design theory 0
    intelligent design16
    design theory2
random mutation171
nonrandom mutation3

The phrase "intelligent design theory" does not occur in the book. The only two instances of "design theory" are other people using the word, not Behe describing the theory. Of the 16 occurrences of the words "intelligent design" only one explains the concept with an analogy: "Imagine that, like Tom Hanks in Cast Away, you wash up on a tropical island". But an analogy doesn't constitute a theory. This is really a remarkable fact! Behe has the complete freedom to write about design theory, but no coherent treatment of the theory can be found. Professor Jerry Coyne stated "his theory is flat wrong" (here). But, there is no design theory in this book. There are a bunch of observations and suggestive allusions to a theory. But not a coherent treatment of design theory. Even "nonrandom mutation", which is an important part of Behe's design claims, occurs only 3 times in contrast to "random mutation" which occurs 171 times. Is it really unfair or unreasonable to expect in this book a coherent description of design theory after more than 10 years since his Darwin's Black Box?

If there is no elaborated design theory in the book, then surely there must be at least a strong link between design and the limitations of Darwinian evolution? I will focus on that link in par4. Although there is no elaborated design theory in the book, there is a framework which I will use as a guide for traveling to and beyond The Edge. This framework is important for Behe, it is presented opposite the title page of the book and repeated in the last chapter. I will then zoom into some important details such as common descent and random mutation.

Fine-tuning of Nature
for Life on Earth
The Tentative Edge of Random Evolution Contingency
in Biology
  1. Laws of nature
  2. Physical constants
  3. Ratios of fundamental constants
  4. Amount of matter in the universe
  5. Speed of expansion in the universe
  6. Properties of elements such as carbon
  7. Properties of chemicals such as water
  8. Location of solar system in the galaxy
  9. Location of planet in the solar system
  10. Origin and properties of Earth/Moon
  11. Properties of biochemicals such as DNA
  12. Origin of life
  13. Cells
  14. Genetic code
  15. Multiprotein complexes
  16. Molecular machines
  17. Biological kingdoms
  18. Developmental genetic programs
  19. Integrated protein networks
  20. Phyla
  21. Cell types
  22. Classes
  1. Orders
  2. Families
  3. Genera
  1. Species
  2. Varieties
  3. Individuals
  4. Random mutations
  5. Environmental accidents

In fact Behe's worldview divides the world into two parts. The middle part is a temporary part, which will be included in the first and/or the third as soon as new knowledge becomes available. For the rest of my discussion I will assume a two-worlds view: the world of design and the world of chance. The dividing line in Behe's two-worlds view is his edge of evolution: what Darwinian evolution cannot do is at the left side and what Darwinism can do is at the right side of the dividing line. At this moment I will not discuss the correctness of this dividing line, but instead I will look at its logical coherence and compatibility with other claims.


The "designed group" contains at least Kingdoms, Phyla, Classes (and maybe Orders, Families and Genera). Behe's "randomness group" cointains at least species (and maybe genera, families and orders).
"Explicit design appears to reach into biology to a certain level, to the level of the vertebrate class, but not necessarily further" (p.220)
Apparently the vertebrate class is explicitly designed. That means that at a certain moment in the history of the earth the first vertebrate "was designed". The fundamental problem here is that the reason for invoking design is that natural processes are not sufficient to produce vertebrates. However, as soon as one single nonnatural event is invoked during the history of life, the genetic continuity of life is broken. Common Descent is based on the vertical (sometimes horizontal) transmission of genetic information. Without that genetic continuity, Common Descent breaks down. And, as we will see, Behe accepts Common Descent. Now, have a look at what Behe has to say about breaking the law:
"intelligent design is quite compatible with the view that the universe operates by unbroken natural law, with the design of life perhaps packed into its initial set-up." (p.166)
It is great to know that Behe adheres to unbroken natural law, because science is all about discovering natural laws. Furthermore, Common Descent also rests upon unbroken natural law. These two nicely fit together. He apparently senses that explicit design of the vertebrate class conflicts with unbroken law and adds the claim about set-up. Problem fixed? You cannot have it both ways. When "The design of life is perhaps packed into its initial set-up" it is apparently at the origin of life. The "explicit design on the level of the vertebrate class" must have occurred at least 3 billion years later (see: Box "Nonrandom mutation").

Box: Nonrandom mutation

"If random mutation is inadequate, then (since common descent with modification strongly appears to be true) of course the answer must be nonrandom mutation. That is, alterations to DNA over the course of the history of life on earth must have included many changes that we have no statistical right to expect, ones that were beneficial beyond the wildest reach of probability."
This quote shows again that nonrandom mutation occurs during the history of life, so is incompatible with Behe's hypothetical set-up at the origin of life. Obviously, designs as "developmental genetic programs" (in his ft-list) do not exist in bacteria, so cannot be included in a hypothetical "set-up".
Most importantly, no experimental data supporting helpful nonrandom mutation exist.

So, it is either "The design of life is packed into its initial set-up" or: Kingdoms, Phyla, and Classes are designed separately. Both cannot be true.
We have already seen that design on the higher biological group levels violates Common Descent. Since Behe accepts Common Descent he should opt for a set-up of life. Now we have two simultaneous contradictions in Behe's claims: (1) the claim of design of the vertebrate class contradicts Common Descent and unbroken law and (2) explicit design of the vertebrate class conflicts with an initial set-up of life. What about the set-up scenario itself? For theoretical population-genetics reasons ("use it or loose it") this set-up option is impossible. Behe knows this when discussing the limitations of the software program Avida:

"Biological organisms show the opposite behavior - genes that are useless in the real world are not rewarded; the genes are rapidly lost or degraded by mutation."
Indeed, a complete set of genes for vertebrates, and most certainly for bats, whales, and giraffes, will be useless for the first cells and will be lost. Now we have a third contradiction produced by Behe himself: (3) he claims a set-up and he knows a set-up won't work. If you have that many internal contradictions, you don't have a coherent theory. The remarkable thing is that Michael Behe does claim that he accepts Common Descent. It is time to examine what evidence Behe presents for Common Descent. That will show how serious he is about it.


"Let's acknowledge that genetics has yielded yet more terrific (and totally unanticipated) evidence of common descent.". Behe presents 3 proofs for Common Descent:
1. vitamin C pseudogene: "Both humans and chimps have a broken copy of a gene that in other mammals helps make vitamin C." (71); "It's hard to imagine how there could be stronger evidence for common ancestry of chimps and humans." (72)
2. hemoglobine pseudogene: "More compelling evidence for the shared ancestry of humans and other primates comes from (...) a broken hemoglobin gene." (71)
3. yeast whole-genome-duplication: "Although duplicated genes can be used to trace common ancestry" (74)
This is the good news: Behe accepts a most important pillar of evolution and he presents evidence for it. But is it really new? No. Behe accepted Common Descent of life already in Darwin's Black Box (DBB) back in 1996. Or did he? Did he present evidence at the time? The hemoglobin pseudogenes are present in his DBB, but amazingly, instead of presenting them as evidence for Common Descent, he attacks them:
"This argument is unconvincing for three reasons. First, because we have not yet discovered a use for a structure does not mean that no use exists." (page 226, DBB).
Here Behe argues against Ken Miller. Miller claimed that Intelligent Design cannot explain pseudogenes of hemoglobin in humans, because it would mean that "the designer made serious errors, wasting millions of bases of DNA on a blueprint full of junk. Evolution can explain them as nothing more than failed experiments". Indeed, it is true that in general one cannot conclude from structures with unknown function to no function at all, but the pseudogene is not an unknown structure, but a copy of a known functional gene with mutations which make it non-functional. So Behe's critique fails. Behe's second argument against pseudogenes as evidence for Common Descent is that "even if pseudogenes have no function, evolution has "explained" nothing about how pseudogenes arose" (DBB,226) and his third is that "these chance events do not mean that the initial biochemical systems were not designed." (DBB,228).
My point is not to refute Behe's arguments, but simply point out the amazing and extraordinary fact that Behe in Darwin's Black Box dismissed exactly the same evidence that he now accepts without any explanation. In The Edge he simply states "a broken hemoglobin gene" and forgets that he stated 10 years ago that "this argument is unconvincing for three reasons". What was exactly wrong with his arguments in DBB? He has obviously changed his mind, but he owes his readers an explanation for the change and he owes Miller an apology (7).
Can we really trust Behe's claim that he accepts Common Descent if he did not explain what was wrong with his own arguments in DBB? This is one of the many dilemmas the reader of The Edge has to resolve. If Behe truly believes in Common Descent and unbroken natural law, then there is no place for design (whether as set-up or as interrupting events). If he truly believes in design, then there is no place for Common Descent and unbroken natural law. I concluded above in section 2 that Behe's explicitly designed vertebrate class conflicted with the fundamental genetic continuity underlying Common Descent. Now we have two reasons to doubt Michael Behe's assertion that he accepts Common Descent. We should end our review at this point, but there is still a question unanswered and that is: Why did he split up the world in two partitions in the first place? What is this mysterious Edge of Random Evolution?


Basically, the two-worlds view is based on design, and design is based on the limitations of Darwinian evolution. Here is the link between Design and the Limitations of Darwinian evolution (it is the central claim of The Edge):
"Most mutations that built the great structures of life must have been nonrandom." (p.82)
"Random mutation does not account for the "mind-boggling" systems discovered in the cell. So what does? If random mutation is inadequate, then (since common descent with modification strongly appears to be true) of course the answer must be nonrandom mutation." (p.165)
But what is the link between nonrandom mutation and design?

Then a miracle occurs

"I'll plainly treat the other side of the edge of evolution
as the domain of design." (p.166)
Yes, you can plainly treat the other side of the edge of evolution as the domain of design. Or, you can plainly treat this side of the edge of evolution as the domain of design. (Behe gives no reason why a designer could not guide mutations which seem random to us). Or, you can plainly treat both sides of the edge of evolution as the domain of design. The important question is: why should we? Behe does not give the reader any good reason why we should treat the other side of the edge of evolution as the domain of design. This is the weakest link in his book. This basic error can be found in an arbitrary creationist book: "Indeed, the origin of the first self-reproducing system is recognized by many scientists as an unsolved problem for evolution, and thus evidence for a Creator." (9). The point here is that I am not denying limits to the power of evolution (see section 8). The point here is that Behe assumes that the designer would first setup life for evolution, let it run until it halts, add DNA and let it evolve again, until it halts again, add DNA again and let it evolve further until it halts, etc. Why would a designer design by endlessly mutating his designs instead of designing from scratch? Behe does not tell us. If we cannot claim that "God wouldn't have done it that way", Behe himself cannot know that God would have done it in that way either (see section 11).
    Furthermore, there is no cognitive gain of introducing an all-powerful designer to solve evolutionary problems. That merely substitutes a process -evolution- which is accessible to human investigation and which has computable limitations, with something -a designer- that has no limitations at all, is essentially incomputable, and is not accessible to human investigation. I prefer the limitations of a natural process, because we at least have a clearly defined problem to focus on and a starting point for further research. Limitations do give us the edge of knowledge. Experience tells us that this eventually triggers new knowledge. Behe confuses the edge of evolution with the edge of our knowledge. Philosopher Philip Kitcher (2007) asks the right question in his Living with Darwin (8):
"Why do intelligent design-ers ignore the basic problem of explaining the power and direction of the mechanism they invoke, a problem that strikes at the heart of their theory?" (p.108)

Behe takes it on himself to find the limitations of Darwinian evolution. His answer is: a process (?) or a mechanism (?) or a person (?) with no limitations. At least, he does not say what the limitations of the designer are. Behe does not proceed from a positive theory of a designer with specified goals, methods and power.
    Here we see a possible reason why there is no design theory in this book: design is negatively defined. There is no theory that positively tries to define the power and abilities of the designer. Behe does not reveal why his designer primarily works with protein-protein binding sites. Instead, Behe describes the biochemical systems with hyperboles such as:

  • astonishingly complex, coherent systems that fill the cell
  • stupendously complex systems
  • enormously complex cellular mechanisms
  • startlingly complex pathway of flagellum assembly
  • staggering complexity of modern biology
  • tremendously complex
  • elegant complexity
  • stunning complexity
  • enormously complex
  • coherent molecular machinery
  • elegant molecular outboard motors
  • elegant immune system
  • intricate genetic control programs
  • stupendously intricate cellular machines
  • sophisticated living machinery
  • highly sophisticated, automated mechanisms
  • ultrasophisticated molecular machinery
  • exquisitely purposeful arrangement of parts

These are subjective concepts, not solid scientific notions. Furthermore, Behe did not give a reason why they should be connected with design. We should stop here our review, but just out of curiosity: what are these mysterious nonrandom mutations that are awaiting us at the other side of the edge? Before entering the mysterious world of nonrandom mutations, I must dwell on Behe's claim that Common Descent is independent of the mechanism of evolution.


Behe claims that he has empirical reasons that the standard Darwinian mechanism of random mutation plus natural selection is unable to create the complete tree of life! He rejects that the majority of adaptations at the molecular level are caused by random mutation. Random Mutation and Natural Selection can only create minor adaptations. At the same time he says he fully accepts Common Descent. We have seen his proofs. How can Behe doubt the mechanism of evolution and at the same time accept Common Descent (CD)? How does he do that? and why? It is easy to see why Behe wants the two theories to be independent. It is because he wants to be able to accept full CD and at the same time reject the ability of Random Mutation and Natural Selection to produce to full tree of life. It would be a lot easier, and, yes, elegant, if he rejected both CD and Random Mutation and Natural Selection, or accepted both. According to standard scientific logic, if CD is true than it automatically follows that all species we see are created by Random Mutation and Natural Selection. This is how Darwinists reason and Behe criticises them for it. According to Behe, common descent and the mechanism are two different and independent theories. In support of his claim he quotes Ernst Mayr (1991) One long argument, who distinguished 5 theories in Darwin's work (3). It is true that CD is distinct from the mechanism of natural selection acting on random mutation. But are they independent? No. Maybe they were separate and independent at Darwin's time, but not today. New scientific discoveries have revealed deep connections between previously unconnected theories. So, Mayr is simply not relevant for Behe's argument. I will show that in the next section. Just one nice quote from an author who lumps mechanism and common descent together:
"To say that Darwinian evolution cannot explain everything in nature is not to say that evolution, random mutation, and natural selection do not occur; they have been observed (at least in cases of microevolution) many different times. Like the sequence analysts, I believe the evidence strongly supports common descent." (page 176 Darwin's Black Box)
Who is mixing up random mutation and common descent?


The link between mechanism and CD is much stronger than Behe realizes. Behe, unknowingly, presents evidence for the fact that CD and mechanism are closely interwoven in the chapter "What Darwinism Can Do". Here are Behe's proofs for Common Descent:
- "Both humans and chimps have a broken copy of a gene that in other mammals helps make vitamin C." (p.71)
- "More compelling evidence for the shared ancestry of humans and other primates comes from (...) a broken hemoglobin gene." (p.71)
- "Although duplicated genes can be used to trace common ancestry" [yeast] (p.74)
Please note that these examples are all based on random mutation. Behe describes these broken genes as "mutational mistakes". So, Behe knows that "genetics has supported common descent". The nature of the evidence for CD is random mutation. Whatever his claims about the limitations of Darwinism, Behe uses cases of random mutation as evidence for CD. I think the connection between CD and Random Mutation and Natural Selection could be elaborated much more. Probably all DNA evidence for CD is based on random mutation supplemented with neutral evolution, genetic drift and horizontal gene transfer (5). Immediately following the three proofs of CD, but out of the blue sky, Behe states in italic:
"Something that is nonrandom must account for the common descent of life."


Although Behe claims that the main driving force of evolutin is nonrandom evolution, it does not follow that he denies any role for random mutation and natural selection. Certainly not. Behe has a chapter "What Darwinism Can Do" in which he presents evidence for the role of random mutation. Behe's evidence for random mutation and natural selection:
  1. Sickle cell mutation, thalassemia.
  2. the mutations that confer chloroquine resistance on malaria
  3. resistance to the drug pyrimethamine (this is gradual! but he treats it as a double mutation, but still possible by chance.)
  4. malaria transmitting mosquito evolved DDT resistance with one amino acid change; and adding other mutations in the right places could increase that resistance (in the lab). (p.76)
  5. the resistance mutation to warfarin has arisen independently about seven times in the same protein of rats. (p.77)
  6. antifreeze proteins (cold tolerance) is an example of gene-duplication and gradualism (p.80). Behe admits gradualism: tiny steps, each is improvement.

Clearly Behe admits here that random mutation and natural selection can produce adaptations. What's more he admits gradual evolution:

-"Although the first mutation (at position 108 of the protein) grants some resistance to the drug [pyrimethamine], the malaria is still vulnerable to larger doses. Adding more mutations (at positions 51, 59, and a few others) can increase the level of resistance. (75)
- "adding other mutations in the right places could increase that resistance". (76)
This is significant because his famous concept IC is based on the impossibility of gradual evolution.


"If two mutations have to occur before there is a net beneficial effect - if an intermediate state is harmful, or less fit than the starting state - then there is already a big evolutionary problem." (p.106)

"Straightforward extrapolations from malaria data allow us to set tentative, reasonable limits on what to expect from random mutation, even for all of life on earth in the past several billion years." (p.13)

Is neo-Darwinism "damaged" by these claims? First, Behe's limits of Darwinian evolution are, indeed as he says, tentative. They need peer-review (6), not an Amazon Blog. The question is not whether there are limitations. Limitations do exist. The real question is how to investigate those limitations in a meaningful way. The limitations of the mechanism of evolution are interesting and important for the field of evolutionary biology. The question of limitations of the power of the neo-Darwinian mechanism can appropriately be compared with the question of embryonic development: "Is the information in the fertilised egg of an animal fully sufficient to produce an adult animal or is anything else required?". This historical controversy produced the opposing theories preformation and epigenesis (see beautiful account of Iris Fry: 16). The theory of preformation claimed that the process of development was simply the growing of a miniature organism already present in the egg or sperm. It postulated the divine origin at the moment of the original creation of the germs that contained the future embryos of all living creatures. Compare this with Behe's divinely created DNA in his "set-up scenario". Scientists today are not yet able to give a complete account of embryonic development, but nonetheless work according to the basic assumption that the problem can be solved without resorting to preformatism or vitalism. Similarly, neo-Darwinists today do not have full understanding of all the details of how the tree of life has been produced, nevertheless work according to the assumption that no unnatural mechanisms are needed. As far as I am aware of, no ID-ist accuses embryologists of a naturalistic bias, so why should they accuse evolutionary biologists of such a bias?
Amazingly for such an interesting question, in its full scope it has only been taken up sofar by off-road researchers such as Fred Hoyle, Lee Spetner and Mark A. Ludwig (19), who primarily seek the shortest way to refute neo-Darwinism. Which is a pity. The question of limitations of the mechanism of evolution is worthy of serious unbiased investigation, but mainstream attempts are disappointing too (17). Behe quoted evolutionary biologist H. A. Orr (5). But Orr does not dwell on the question what his results mean for evolution as a whole. Which is a pity. Yet, the goal of making the theory of evolution more exact and predictive is a perfect scientific goal. To be able to estimate or compute the power of evolution would be scientific progress. It could give us a good idea about the status of our current understanding of evolution. The fact that we cannot yet do so is a pity, but is not in the slightest degree something to be ashamed of, or something to hide for the general public. That is what Michael Behe should have told the public. Especially, since Behe did not even start to compute the power of the designer. That should be his focus and priority. At least, if he really wants to be an "intelligent design proponent" and have a design theory. Therefore, I did not go into the details of Behe's malaria case. It would distract from my main arguments in this review: the lack of a design theory.


Behe: the universe is fine-tuned!
The universe is fine-tuned for me!

In the final chapter Behe argues for fine-tuning for "intelligent life". What does fine-tuning mean exactly? Is fine-tuning different from design? Does fine-tuning mean anything more than the trivial statement that certain properties of matter are necessary for the origin and the existence of life? Could it mean that the fine-tuning is both necessary and sufficient? If fine-tuning is not sufficient, additional designing or intervention must be done? What facts are predicted? Is intelligent life only an euphemism for the human species? Or does fine-tuning also predict apes, dolphins, crows, grey parrots, but nothing more? Then, what have such creatures as bats, whales, and giraffes, which are designed according to Behe, to do with the goal of fine-tuning? Does fine-tuning predict malaria and thousands of organisms that parasitize or prey on humans? How specific is fine-tuning really? Does it predict evolution and Common Descent? Does it predict both Common Descent and the limitations of random evolution? What would falsify Fine-Tuning? If the purpose of fine-tuning is the spontaneous evolution of intelligent life, then the inherent limitations of Darwinian evolution prove the failure of fine-tuning. Also, if the properties of carbon, water, DNA, and the conditions on the early earth count as evidence for fine-tuning for life, then the impossibility of the spontaneous origin of life must count as evidence against fine-tuning. Does it make sense to fine-tune everything in the universe for life on earth, to let species evolve by natural common descent, and implement such severe restrictions on the evolutionary mechanisms that the major architectural features of life - molecular machinery, cells, genetic circuitry - have to be added separately one-by-one by hand at widely different times in a manner that violates the genetic continuity of life? In this way a comfortable and unfalsifiable mixture of fine-tuning and design (intervention!) produces everything you want in every possible way.


For Behe random mutations can produce only unimportant decorations: "Darwin decorates the spandrels. The cathedral is designed." Let's revisit Behe's fine-tuning table:

Fine-tuning of Nature
for Life on Earth
The Tentative Edge of Random Evolution Contingency
in Biology
  1. Laws of nature
  2. Physical constants
  3. Ratios of fundamental constants
  4. Amount of matter in the universe
  5. Speed of expansion in the universe
  6. Properties of elements such as carbon
  7. Properties of chemicals such as water
  8. Location of solar system in the galaxy
  9. Location of planet in the solar system
  10. Origin and properties of Earth/Moon
  11. Properties of biochemicals such as DNA
  12. Origin of life
  13. Cells
  14. Genetic code
  15. Multiprotein complexes
  16. Molecular machines
  17. Biological kingdoms
  18. Developmental genetic programs
  19. Integrated protein networks
  20. Phyla
  21. Cell types
  22. Classes
  1. Orders
  2. Families
  3. Genera
  1. Species
  2. Varieties
  3. Individuals
  4. Random mutations
  5. Environmental accidents

Why does Behe classify random mutations in the contingency category and not in the same category as the Laws of nature? The law like behaviour on macroscopic scales arises from combined effects of random microscopic events. For example, Boyle's Law is based on blind purposeless random collisions of gas molecules. Similarly, the fact of random mutation is not an accident! It follows from the biochemical properties of DNA. Behe classifies these as fine-tuned. One of the chemical properties of DNA replication is that it is very reliable, but not error-free. DNA copying errors are essentially of a statistical nature. On the other hand, nonrandom mutation, certainly of the helpful type, is not a known property of DNA. (Why don't we see helpful nonrandom mutation in his ft list?) You cannot place the fundamental properties of DNA and random mutation in separate worlds. Seen from that perspective, there might exist evolutionary limitations, but not necessarily so strong that evolution could not produce the tree of life. Furthermore, when we add genetic continuity inherent in common descent and unbroken natural law to the story, we arrive at the conclusion that there can be no limitations to the evolutionary processes that produced the tree of life. What would be the point of Common Descent from the point of view of the designer? Why design Common Descent anyway? Finally, why the deep rooted worries about randomness? Christian geneticist Francis Collins said it thus:

"Evolution could appear to us to be driven by chance, but from God's perspective the outcome would be entirely specified. Thus God could be completely and intimately involved in the creation of all species, while from our perspective, limited as it is by the tyranny of linear time, this would appear a random and undirected process." (p.205, The Language of God).
And Christian biochemist Kenneth Miller (1999) wrote:
"A clever and subtle God could influence events in ways that are profound, but scientifically undetectable to us. Those events could include the appearance of mutations." (p.241, Finding Darwin's God).
Christian physicist Arthur Peacocke (2004) wrote:
"To postulate a "special creation" of species or that God injected "life" into the universe or that God somehow directly and personally directs the processes of biological evolution by means other than that inherent in the nature of matter and its "laws" are all errors on Christian premises." (p.63, Evolution. The disguised friend of faith?)
Behe's view that the designer acts by manipulating mutations is a theological position. It is a claim about how God would create:


"Biophysicist Cornelius Hunter argues perceptively that the main supporting pole of the Darwinian tent has always been a theological assertion: 'God wouldn't have done it that way'. Rather than demonstrating that evolution is capable of the wonders they attribute to it, Darwinists rely on a man-made version of God to argue that He never would have made life with the particular suite of features we observe."
(Michael Behe on the back cover of Cornelis Hunter's Darwin's God).
Biochemist Michael Behe never demonstrated that his designer is capable of the wonders he attributes to him, and his own position is very much a theological position (see Arthur Peacocke quote above). Behe escaped having "a man-made version of God"? My conclusion from the above statement is: if one cannot know what the designer wouldn't do, one cannot know what the designer would do either. God wouldn't have made evolution so powerful that it could produce humans autonomously is the hidden theological assumption in Behe's own thinking. If Behe did follow the logic of his own statement, he should have concluded that no theory about the designer is possible. Furthermore, the lack of an elaborated and coherent design theory in The Edge leaves Behe empty handed.
    One good point here is that evolutionary biologists need to demonstrate that evolution is capable of the wonders they attribute to it. That's their job. Behe's perceived limitations of Darwinian evolution are in fact limitations of our knowledge of evolution. From the point of view of the power of the designer, it does not make sense that he could create 3 simultaneous beneficial mutations, and was unable to create 1 or 2 simultaneous mutations. If a designer can create a castle, he must be able to build a house.


"Malaria was intentionally designed. The molecular machinery with which the parasite invades red blood cells is an exquisitely purposeful arrangement of parts. (...) What sort of designer is that? What sort of "fine-tuning" leads to untold human misery? To countless mothers mourning countless children? Did a hateful, malign being make intelligent life in order to torture it? One who relishes cries of pain? Maybe. Maybe not." (p.237) (21)
Personally, I find this the most shocking passage of the entire book. If malaria is intelligently designed, then it is a form of biological warfare or bioterrorism, just as the intelligently designed spread of anthrax spores by mail in 2001 (18). The difference is that malaria killed millions and that the killing continues on a daily basis. Behe follows his own logic to the bitter end (23). From a logical point of view, that is the only positive thing that can be said. However, alarm bells should have been ringing by the result of that logic. What is really bad from a moral point of view, is that first having blessed malaria with a divine origin, subsequently his "Maybe. Maybe not" avoids any answer to his own question "What sort of designer is that?". A question of the highest moral, humanitarian, medical and educational importance. It is not only about malaria. If I understand Behe correctly then 99% of life on earth is designed (Properties of biochemicals such as DNA, Origin of life, Cells, Genetic code, Multiprotein complexes, Molecular machines, Developmental genetic programs, Integrated protein networks are all designed). That includes probably all pathogenic organisms. Who dares to eradicate malaria if it is a divine creation? (15). I am worried about what happens to children when they learn that God intentionally designed malaria. But also what happens to parents already in the habit of opposition to vaccination on the grounds that "man must not, by using vaccines, interfere with God's will"? (10). Will they now object to fighting malaria on the same grounds? Or, following the logic of the Designer to the bitter end, help the malaria mosquito to multiply as much as possible?
Behe says he does not have the answers, except he knows one thing for sure:
"Of the many possible opinions, only one is really indefensible, the one held by Darwin. In a letter to Asa Gray, he wrote: "I cannot persuade myself that a beneficent and omnipotent God would have designedly created the Ichneumonidae with the express intention of their feeding within the living body of caterpillars." (p.238)
"So did Darwin conclude that the designer was not beneficent? Maybe not omnipotent? No. He decided -based on squeamishness- that no designer existed. Because it is horrific, it was not designed - a better example of the fallacy of non sequitur would be hard to find. Revulsion is not a scientific argument." (p. 239)
Here, Behe misinterprets what Darwin wrote in a private letter (this was not in The Origin of Species). Darwin did not write "God does not exist" as everybody can see. Darwin simply said that his observations are not compatible with a beneficent and omnipotent God -the centuries old God of the theologians. Not a God of Darwin's own invention. Darwin simply compared observation and centuries old theological tradition. A question of logic. So Behe's triumphant "Revulsion is not a scientific argument" is irrelevant (12). We "know now" from Behe that Darwin was squeamish (22), (24). I wonder what would happen to children when they do not only learn "Malaria was intentionally designed", but also that they should not be so squeamish about it as Darwin and that it is not yet known whether the malaria-God is malicious or good-natured (20).

    Another question is the compatibility of the malaria-God with the goals of the Intelligent Design movement:

* "To defeat scientific materialism and its destructive moral, cultural, and political legacies"
* "To replace materialistic explanations with the theistic understanding that nature and human beings are created by God" (11)
Does that mean that "malaria was created by Darwinian evolution" must be replaced by "malaria was created by God"? I suggest that this destructive insight must not "permeate religious, cultural, moral and political life" before a satisfactory answer has been given to the problem of natural evil. Even Cornelius Hunter who wrote a book specifically addressing the question evolution and the problem of evil did not even try to begin to answer the question.
    And what about the basis of morality? (13). Is morality not based on "an emotional feeling of the way things ought to be"? (7). Darwin's empathy, condescendingly described by Behe as squeamishness, is indeed not a basis for science, but it is generally recognized as the biological basis of morality ('do no harm'). This is especially destructive for Behe's morality, because Behe just destroyed the religious foundation for morality (14). Why waste time and energy to prove a link between Darwin and Hitler (Richard Weikart), when the designer-god is killing millions of innocent people every year? I myself don't understand what drives people to religion. However, if religion is about comfort and consolation, then I am seriously and honestly bewildered, baffled, and perplexed that a human mind can find consolation in the sort of designer Michael Behe just created. A designer who excels in creating "ultrasophisticated molecular machinery", but who doesn't care about human well-being. I would be scared to death by such a designer.


It is possible that some readers will find new facts or insights in The Edge of Evolution. It depends on the reader. However, let this not distract us from the fact that the book does not deliver a theory of design, but instead discusses the limits of evolution. That is remarkable for someone who calls himself a proponent of intelligent design. Yet, design dominates Behe's thinking, but it easily escapes our notice that a crucial logical step is without justification. Behe has given no reason for the main claim of his book that the other side of the edge of evolution is the domain of design. Indeed, why would a designer act according to design principles determined completely by our 21st century knowledge of the world? On an even deeper level it is unclear why a god would create anything at all. One reason for the absence of a design theory is that one cannot know what a designer would do or would not do, effectively closing of any knowledge about the designers goals and methods. How can one search for proofs under such conditions? The lack of positive knowledge of design and designer forces Behe to focus exclusively on the limits of Darwinian evolution. Another reason is that you can't construct a theory on broken natural laws. That Behe still managed to write an ID-book must be explained by the fact that he most certainly has a theological theory - in his head. Driven by theological notions, but prevented by a self-imposed restriction to talk about it, Behe persistently searches for proofs of God in nature at all costs. The final result is a clumsy, inefficient DNA-manipulator who needs billions of years to create a human being and is a bioterrorist who excels in making human life as miserable as possible. There could be no greater incompatibility between claims that 99% of life was designed and common descent. Common Descent is based on genetic continuity in the history of life on earth and ultimately based on unbroken natural law. Design, as Behe describes it, is based on the discontinuity of the tree of life (broken natural law). Therefore, design and common descent are incompatible. It is either design or common descent. It is logically impossible to hold both.


  1. Daniel Hartl (2007) 'The spandrels of the genome'. Nature Genetics, 39, 811 (2007). It shows, that one does not need ID for criticism. Also that Random Mutation can be accepted as an explanation for certain features of organisms, without invoking natural selection.
  2. Douglas H. Erwin (2007) Darwin Still Rules, but Some Biologists Dream of a Paradigm Shift, The New York Times, 2007
  3. Behe refers to One Long Argument, but the 5 theories idea is already present in The Growth of Biological Thought Ernst Mayr, 1982. If two theories are dependent, does this refute Mayr's five theories idea? Only when interpreted as being 5 independent theories. However, it is not so difficult to see why. Mayr worked in a pre-genomics area. Darwin's time they were probably factually independent, and in Mayr's pre-genomics times the link was somewhat stronger.
  4. He could use special creation at the family level and explain away pseudogenes.
  5. H. A. Orr (2003) "A minimum on the mean number of steps taken in adaptive walks." Theor. Biol. 220:241-47.
  6. Nicholas J. Matzke (in press TREE) shows that Behe's estimates for the probability of a simultaneous double mutation in P. falciparum's chloroquine resistance is wrong. And his subsequent estimate of 3 simultaneous mutations is based on that estimate, so is also wrong.
  7. Cornelius Hunter (2001) Darwin's God. Evolution and the Problem of Evil, page 168, is also unconvinced by the pseudogene argument but for an extremely bizarre reason: 'that the pseudogene is a result of mutation is nothing more than evolutionary speculation'! On the other hand Francis Collins accepted broken genes as evidence for Common Descent.
  8. Philip Kitcher (2007) Living with Darwin. Evolution, Design, and the Future of Faith, Oxford University Press, hb 192 pages. Recommended reading!
  9. Jonathan Sarfati, 2000, 'Refuting Evolution, p.125, my emphasis.
  10. "The history of Edward Jenner and the first vaccine (smallpox) along with the difficulty of its contamination with diverse infectious agents are well detailed. Interestingly, the religious objection dating back to Jenner's time in the late 1700s that man must not, by using vaccines, interfere with God's will has not abated." Review of Arthur Allen (2007) 'Vaccine: The Controversial Story of Medicine's Greatest Lifesaver', Nature 448, 137 (12 July 2007). If one reads on page 34 of the book how people did think about God and disease in 1721, then one comes to the shocking conclusion that 300 years later Michael Behe has exactly the same primitive belief. An example: "Death by infection was distributed by God and thus, if sorrowful, at least nothing to be regeretted; a natural death would at least give "the refreshment to think this is God's doing" (p.34). By a natural death Winthrop means death by smallpox and so he was opposed to vaccination.
  11. Wedge strategy in wiki.
  12. This is not a new argument. In his DBB Behe already used it: "The debater has reached his conclusion in favour of Darwinism based solely on an emotional feeling of the way things ought to be." (p.224).
  13. See about the basis of morality my review of Francis Collins' The Language of God.
  14. Before The Edge Christians had an absolute basis of morality: God. Therefore, they had a reason to cure malaria patients. I myself think malaria is a bad thing. But this is only a subjective feeling, and since I do not have an absolute morality, I cannot justify helping malaria patients.
  15. That malaria was designed by God must be bad news for faith-based organizations in controlling malaria in Africa (Laura Bush Praises Private Sector Efforts To Fight Malaria, 16 February 2007)
  16. Iris Fry (2000) 'The emergence of life on earth. A historical and scientific overview'.
  17. Michael T. Clegg (2000) 'Limits to knowledge in evolutionary genetics'. (Evolutionary Biology Vol 32) and also: Fyodor A Kondrashov (2005) 'In search of the limits of evolution', Nature Genetics 37, 9 - 10 (2005) ("Evolution can proceed only along ridges of high fitness and must avoid fitness valleys. Therefore, the ruggedness of fitness ridges defines how evolution must proceed in genotype space")
  18. They are appropriately called designer diseases by Madeline Drexler (2002) Secret Agents. The menace of emerging infections, page 243.
  19. Mark Ludwig (review) asked already in 1993 the big question: "Are the mechanisms proposed by biologists powerful enough to produce all life on Earth?". Behe does not mention him.
  20. In an often quoted passage Francis Collins wrote: "That young woman was my daughter. Never was pure evil more apparent to me than that night, and never did I more passionately wish that God would have intervened somehow to stop this terrible crime. Why didn't He cause the perpetrator to be struck with a bolt of lightning, or at least a pang of conscience?" (p.44 The Language of God). Behe must reject Collins' feelings as squeamish. (However, Collins solution is bizar: utlimately it boils down to the free will of the raper). Francisco Ayala (2007) views evolution as a solution to the problem of physical evil: "I do not attribute all this misery, cruelty, and destruction to the specific design of the Creator." and: "I shudder in terror at the thought of that some people of faith would implicitly attribute this calamity to the Creator's faulty desgin." (page xi from Preface Darwin's Gift: To Science and Religion). Allthough Ayala doesn't mention Behe, it is squarely opposed to Behe's view. Behe would accuse Ayala of squeamishness. Ayala would accuse Behe of blasphemy: "Attributing these [imperfections] to specific agency by the Creator amounts to blasphemy. Proponents of ID are surely well-meaning people who do not intend such blasphemy, but this is how matters appear to a biologist concerned that God not be slandered with the imputation of incompetent design." (page 160) and: "The God of love and mercy could not have planned all this." (p.159). Anyway, ID-proponents have to answer –since Behe's Edge– an old question similar to "Where Was God on September 11?"
  21. "Chimpanzees don't get sick from the human malaria parasite, Plasmodium falciparum. Conversely, humans can't be infected with P. reichenowi, the malaria parasite that plagues chimpanzees." The human susceptibility to Plasmodium falciparum is the result of a simple mutation. (Ajit Varki, Nature, 3 Jul 2008). Behe only talks about the malaria parasite, not about human susceptibility. Must we suppose that the malaria susceptibility mutation was also designed?
    On 7 Aug 2009 Science published compelling evidence that the parasite, Plasmodium falciparum, evolved from a relative called P. reichenowi that infects chimpanzees'.
  22. We 'know' this also from other sources: "His squeamishness inhibited his study of dissection, and human anatomy and anthropology were his weaknesses" (source). Also in Adrian Desmond & James Moore (2009) " Darwin's Sacred Cause: Race, Slavery and the Quest for Human Origins" Darwin is described as: "As his squeamishness had shown in Edinburgh, when he fled the operating theatre" (p.59) and "Sensitive, squeamish, Darwin was tortured himself" (p. 108) which refers to hearing the torture of a slave in Brazil. Behe makes fun of Darwin's squeamishness, but is he able to torture a man or animal? [ 7 Dec 2012 ]
  23. Denyse O'Learly (2004) writes in By Design or by Chance?: "Evil design, especially. cries out for explanation today, as much as in Darwin's day. And that is the major theological challenge that ID theory poses. It restores design of all kinds, including evil design." (p. 216) [ 24 Jan 2013 ]
  24. The word 'Squeamishness' appears in Nature 18 Jul 13: "Squeamishness among parents being asked to vaccinate 11-year-olds against a sexually transmitted disease is understandable. But in the face of such a clearly effective means of protecting our young people, ducking the issue, hoping for the best or relying on the responsible actions of others is not." ('Active protection. Parents should vaccinate their children against human papillomavirus.')

      Other reviews of The Edge of Evolution

      Further Reading

  • Michael Behe Response to Critics, Part 1: Jerry Coyne, Amazon, June 24, 2007
  • Michael Behe 'Response to Critics, Part 2: Sean Carroll, Amazon, June 26, 2007.
  • Michael Behe Back and Forth with Jerry Coyne, Part 3, Amazon, July 10, 2007 "I don't go into it in detail in the book (Chapter 10 was already too long), but in essence the scientific rationale is the arguments of Michael Denton in Nature's Destiny and Ward & Brownlee in Rare Earth (which I cite). Both of those books argue that the requirements in nature for intelligent life are much greater than for 'simple' life, such as bacteria. If one takes the 'purposeful arrangement of parts' as empirical (scientific) evidence of design, as I do, then the intricate arrangement of parts in nature needed for intelligent life points to that as a design goal."
  • Michael Behe Beyond the Edge of Evolution: The New York Times Story, Amazon, 24 aug 2007
  • Michael Behe Korthof and Pseudogenes: Part 4, Amazon blog October 15, 2007 10:26 AM PDT
  • Michael Behe (2007) 'Addressing Cumulative Selection', Science 12 October 2007 is a reply to Sean Carroll's review of his Edge. With a response from Sean B. Carroll on the same page.
  • Michael Behe (2007) Trends in Ecology and Evolution follows the trend, Part I, Part II, Part III. This is a response to N.J. Matzke in TREE.
  • Michael Behe (2008) Multiple Mutations Needed for E. Coli in which he responds to: Zachary D. Blount, Christina Z. Borland, and Richard E. Lenski (2008) 'Historical contingency and the evolution of a key innovation in an experimental population of Escherichia coli', PNAS, June 4, 2008.
  • Matzke N. J., The edge of creationism, Trends Ecol. Evol. (2007) (full text).
  • My review of Michael Behe (1996) Darwin's Black Box.
  • Burckhard Seelig & Jack W. Szostak (2007) 'Selection and evolution of enzymes from a partially randomized non-catalytic scaffold', Nature, 48, 828-831 (16 August 2007).
  • Renyi Liu, Howard Ochman (2007) 'Stepwise formation of the bacterial flagellar system', Open Access article PNAS April 24, 2007 vol. 104 no. 17 7116-7121
  • Paul Draper (2007) Natural Selection and the Problem of Evil. This page is part of God or Blind Nature? Philosophers Debate the Evidence. Infidels.org.
  • Michael Behe (2009) Letter to the editor, Genetics: Published Articles Ahead of Print, published on February 2, 2009.
  • Durrett R, Schmidt D. Response to the Letters to the Editor "Response to Durrett and Schmidt" by Michael Behe. Genetics. 2009 Feb 2.
  • Behe's latest book Darwin Devolves is reviewed in Science, 8 Feb 2019: "Ultimately, Darwin Devolves fails to challenge modern evolutionary science because, once again, Behe does not fully engage with it. He misrepresents theory and avoids evidence that challenges him.".

See also
my review of Behe's
'Darwin's Black Box':

Darwin's Black Box
See also:

Michael Behe
SARS-CoV-2 was designed says Intelligent Design Theorist Michael Behe.
26 Feb 2021.


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Copyright ©G. Korthof 2007 First published: 22 Jul 2007 Updated: 18 Aug 2007 F.R./Notes: 1 Mar 2021