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Does Irreducible Complexity refute neo-Darwinism?
a review of Michael Behe's 'Darwin's Black Box' by Gert Korthof
Irreducible Complexity is a good test for neo-Darwinism:
Well, biochemist Michael Behe in Darwin's Black Box. The biochemical challenge to evolution (1996) specifies a few things that exist and should not exist according to neo-Darwinism. Behe assumes neo-Darwinism claims :
StepwiseThese are hard constraints on all possible neo-Darwinistic explanations. Stepwise creation and the beneficial nature of intermediate steps are the most important building blocks of the neo-Darwinist explanation of the adaptations of living organisms. Through Behe's account one starts to realise that these rules are strong constraints indeed. Contrary to what the textbooks seem to tell us, evolution is not easy and surely evolutionary improvement and innovation are not inevitable. The picture that Behe paints is not a distortion of neo-Darwinism. It is neo-Darwinism in a nutshell: "If there is no stepwise path up the mountain, natural selection won't climb it" as evolutionary biologist John Maynard Smith pointed out (9).
Evolutionary intermediates represented a central preoccupation for Charles Darwin in his case for the theory of evolution. He remarked, for example: '...why, if species have descended from other species by insensibly fine gradations, do we not everywhere see innumerable transitional forms?' (On the Origin of Species). Although Darwin developed a convincing rationale for their absence, he did realize that the lack of intermediates as proof leaves room for criticism. He noted, for instance:
'If it could be demonstrated that any complex organ existed which could not possibly have been formed by numerous, successive, slight modifications, my theory would absolutely break down.' (On the Origin of Species) (45).So, Behe just followed up Darwin's suggestion.
Behe should not be attacked for claiming to have refuted neo-Darwinism. If these cases trigger new research, new questions and new answers, then Behe indirectly stimulated science. It is now clear that Behe did indeed stimulate scientific thinking (10, 37, 38). However, it is also true that he did not publish his ideas in a peer-reviewed biological or biochemical journal, but in a book for the general public. A book is a way to side-step review by peers. Behe did publish in philosophical journals (14). But Darwinism is a biological theory, not a philosophical theory.
General versus specificPlease note that Behe did not claim that the Darwinian explanation is wrong in all cases, but that neo-Darwinism cannot explain some cases (such as bacterial flagellum and the blood clotting system). This means that irreducible complexity is not a general falsificator of natural selection or neo-Darwinism, but a specific falsificator for specific cases. Behe did not bother to point out that all other cases are explainable by Darwinism. Please note that Behe did not attack common descent of all life (evolution as a fact) (26). Accepting common descent and rejecting the mechanism of evolution is not a contradiction, because we are talking about two separate theories and the evidence for both theories is different too.
Furthermore, Behe did not claim that there could never be any functional intermediates on the way to any irreducibly complex system. Irreducible complexity does rule out direct routes, but it does not rule out indirect routes. According to Behe, indirect routes are quite implausible.
The definition of ICIrreducible Complexity is defined by Behe as a single system which is composed of several well-matched, interacting parts that contribute to the basic function, and where removal of any one of the parts causes the system to effectively cease functioning.
The Logic of the Concept ICTwo aspects must be clearly separated: the state of a system and the origin of the system. To call something 'irreducible complex' is a description of the state of the system. It means that all parts of that system are necessary for the functioning of the whole system. According to Behe, each part has no value except within the context of the whole functional unit. The state of being irreducible complex does not say anything about its origin. There are many irreducible systems in your house, the most simple ones are:
The solution is: start with supporting stones and place the final stones on top of it, then remove the supporting stones. Removing one of the stones of the finished arch destroys the whole arch. The stone arch itself cannot be made gradually, but it certainly can be constructed one stone at a time with the help of temporary supporting stones. The first phase of the stone arch is a nonfunctional intermediate, because it does not function as an arch.
The history of the conceptBehe's household example of Irreducible Complexity was the mousetrap. Behe's biological examples of an IC system were cilia, flagellum and the blood clotting system. He borrowed the cilia from Michael Denton (1986) (19). Michael Denton came close to inventing Irreducible Complexity. Denton claimed 'intermediates do not exist'. Behe went one step further: 'intermediates cannot exist', which is a stronger claim. Origin of life researcher A.G. Cairns-Smith used in 1985 the idea of the stone arch as a metaphor for the interdependencies in the biochemistry of the cell. The anatomist Mivart listed in 1871 a number of organs that would not (he thought) be advantageous in their initial stages, for example the famous "What use is half a wing?" (41). But Darwin himself had a notion of the idea of 'Irreducible Complexity': "If it could be demonstrated that any complex organ existed, which could not possibly have been formed by numerous, successive, slight modifications, my theory would absolutely break down" (31).
The idea of useless intermediate stages of a useful adaptation is even older than Darwin. William Paley used it as an argument for design and against a natural origin, as S.J. Gould pointed out (33).
Biochemical mousetrapsA potential example of irreducible complexity not given by Behe is the interdependence of DNA and proteins, which results in the notorious difficulty of explaining the origin of life. Maybe all Irreducibly Complex systems are examples of another famous problem: the chicken and egg problem: no chicken without egg, no egg without chicken. A biological example of a potential IC system with two parts is the key-and-lock system such as a hormone and hormone-receptor. There is no point in having an elaborate key if there is no matching lock, and there is no point in having an elaborate lock if there is no matching key. Building a lock-and-key system appears to require at least two changes to happen simultaneously (37).
FalsifiabilityAccording to Phillip Johnson "Darwin himself established the tradition of explaining away the fossil record" and "The central Darwinist concept that later came to be called the "fact of evolution" -descent with modification- was thus from the start protected from empirical testing" (6). This amounts to saying Darwinists made Darwinism unfalsifiable. However, Michael Behe unintentionally shows clearly why Phillip Johnson is wrong in claiming that Darwin and Darwinists created a nonfalsifiable theory! Darwinism is risky! However, if scientists claim (as a reaction to Behe) that neo-Darwinism is true and therefore cannot be refuted, then Johnson as yet is right.
It is not right to call 'Irreducible Complexity' just a gap in our knowledge, because a gap in our knowledge can be neutral to a theory, whereas a potential falsificator is contra evidence for a theory. A falsificator is stronger than an unexplained phenomenon.
Did Behe falsify neo-Darwinism? Above we saw that irreducible complexity is not a general falsificator, but a falsificator for specific cases. Therefore, a general refutation of neo-Darwinism is out of the scope of irreducible complexity. Furthermore, a mousetrap will not do: it is irreducible by definition. Behe needs an empirical demonstration that a specific biochemical system is irreducible. He must show that all 200 parts of the cilium are necessary! Only then, one can establish that the removal of one component destroys the function of the system. To do that, one must know exactly how many parts the system has. Behe is not precise about that: "a cilium contains over two hundred different kinds of proteins" (p.72, my emphasis). Without a precise list of parts, he never can determine whether the cilium is irreducibly complex.
Furthermore, he must show that these parts do not have a second function. For, it they have a second function, they are maintained by natural selection. And this circumvents the requirement for usefulness of each intermediate step of proteins involved in the first function (motor function of the cilium or flagellum). For example, flagella are also essential for viability of the single-cell African parasite trypanosome, because they are essential for trypanosome cell division (36). Empirical evidence has the last word, not mousetraps (7). If Behe fails to come up with a case of irreducible complexity, that withstands all criticism, then neo-Darwinism survived another failed falsification. Precisely that is the right sort of positive evidence for a theory. It is evidence that counts. Actually the best possible confirmation for any scientific theory!
Finally: the fact that Behe proposes 'design' as an alternative explanation, does not affect in the fact that 'Irreducible Complexity' is an interesting falsificator. 'Irreducible Complexity' itself is not a religious concept. Behe was smart enough to make his central concept non-religious. Behe's religious motives are also irrelevant for the evaluation of the correctness of 'Irreducible Complexity'. Even if Behe's hybrid hypothesis 'design and/or evolution' (4) is unfalsifiable, this does not affect the value of 'Irreducible Complexity' as a potential falsificator of the neo-Darwinian mechanism. Indeed, the value of 'Irreducible Complexity' as a falsificator is logically and factually independent of any alternative hypothesis.
Undermining the falsificatorUnfortunately, but honestly Behe later stated: "Demonstration that a system is irreducibly complex is not a proof that there is absolutely no gradual route to its production" (21), thereby undermining the beauty and power of his falsificator. But Behe did more to undermine his falsificator of Darwinism. In an article in the journal Biology and Philosophy (29) Behe stated "A weak point of Darwinian theory is its resistance to falsification. What experimental evidence could possibly be found that would falsify the contention that complex molecular machines evolved by a Darwinian mechanism? I can think of none". I can think of none? This is an extremely amazing claim. Behe forgets his own biochemical mousetraps! What was the point of writing Darwin's Black Box? What was the point of the concept 'irreducible complexity'? What was the point of the bacterial flagellum and the blood clotting system, if not refuting their Darwinian origin?
Recently, it has been shown how a seemingly irreducible complex system could originate by a step-by-step Darwinian process (37,38). The system consists of two key-and-lock systems: the aldosterone and cortisol receptor system. It has been shown that these particular hormone-receptor systems evolved from a duplicated receptor-gene. The two copies differentiated by 2 point mutations and so an exclusive aldosterone sensitive and an exclusive cortisol sensitive receptor resulted. The two pairs now have different physiological functions. Experimentally, it has been shown that an evolutionary path exists from ancestor
system to the recent aldosterone and cortisol system through 2 useful intermediate steps. Therefore, it has been shown that two seemingly irreducible complex key-and-lock systems evolved in a Darwinian way and that a designer was not necessary to explain them.
Another famous irreducible complex system, the flagellum, has been refuted by a detailed step by step evolutionary model, which is beautifully explained in this animation at YouTube:
Common DescentTo my surprise Behe stated: "I believe the evidence strongly supports common descent" (p.176) and he has repeated this in later publications (26). Behe did not bother to present the evidence for common descent. Is he interested at all in the evidence for common descent? Does he know or understand the evidence? Behe does not seem to realise the consequences of his statement.
Common descent of life means that all life is descended from the first form of life.
Common descent of life means that all life on Earth is physically, historically and genetically connected. It is one unbroken chain of ancestors and descendants.
Common descent of life means that there is only one tree of life.
Common descent of life means that gaps in the fossil record are gaps in the record, and not in the tree of life.
Common descent of life means that whatever the mechanism, every organism inherited its genes and all its so-called 'irreducibly complex' systems from the previous generation and so on until first life. Every intervention would be a violation of common descent.
2 May 2011
Macro-evolutionTo my surprise Behe rejects macro-evolution: "Many people have followed Darwin in proposing that huge changes can be broken down into plausible, small steps over great periods of time. Persuasive evidence to support that position, however, has not been forthcoming." (p.15). How can one reject macro-evolution while at the same time accepting common descent? Common descent implies macro-evolution.
Behe is a theistic evolutionistBehe accepts that evolution occurred and accepts common descent, however he thinks that evolution was 'guided by God' (15). That makes him a theistic evolutionist. However, Behe does not give a rigorous definition of 'guided evolution', so I don't know whether 'guided evolution' is the same as 'supernatural intervention' or contradicting common descent.
Unhistorical nature of Design
"The irreducibly complex biochemical systems that I have discussed in this book did not have to be produced recently. It is entirely possible (...) that they were designed billions of years ago and have been passed down to the present...I overlooked this passage when I first read Behe's book, but I found it in Kenneth Miller's review (11). The problem with Behe's reasoning is that population genetics predicts that genes which are not "turned on", accumulate random mutations because they escape natural selection. They surely do so over "billions of years". Behe should explain what keeps them intact. Do we need a designer again to turn those silent genes on? When? Where? How? It is easy to suggest all these things as Behe does, but he did not work out the details as he himself demands again and again of Darwinists. Remarkably, Fred Hoyle (12) also proposes that genes where kept silent for millions of years until needed. The difference is that Hoyle's genes came from space! But Hoyle runs into the same problems (see review of John Maynard Smith (9) ).
A fundamental difference between evolution and creation/design is that evolution needs precursors and creation/design does not need precursors. The creation/design view is clearly opposed to evolution and neo-Darwinism: completely specified genes waiting millions of years before they are turned on. Genes without any history, without any signs of their origin, without any relation to precursor genes. To be honest: Behe stated that the design hypothesis does not depend on 'when' in the history of the Earth. This is a disadvantage. It strikes me that 'design' is so unhistorical. For example: because the blood clotting system doesn't need to be based on pre-existing parts, it could be created anytime in the history of the Earth. 'Intelligent Design Theory' has nothing to say about when for example humans should appear in the fossil record. Therefore humans could appear before the first mammals; birds could appear before reptiles and land vertebrates could appear before fishes, etc. Because the Design theory is unhistorical, it is unsuitable for the study of life, since life itself is closely connected to the history of the Earth. It is not a coincident that Michael Behe has been educated in an unhistorical science (biochemistry). Biology has a significant historical component.
Unbiological nature of DesignBehe did not search for flagella in related species, neither did he search for simpler flagella. Yet, there are simpler variants of flagella as can be seen from the illustrations below:
Vitamin C as an example of Irreducible ComplexityIrreducible Complexity means that removal of a component destroys the function, because there are no redundant components available to take over. These non-redundant systems are "best explained as the result of deliberate intelligent design." (14).
Redundant complexity means that removal of a component does not destroy the function, because there are redundant components that can compensate for the lost function. In a reply to criticism (14) Behe mentions that humans cannot produce vitamin C (ascorbic acid), because the gene that is responsible for the last step in the synthesis of vitamin C is not functional in humans. It is functional in other animals. Since vitamin C is made by no other pathway (16), it is a case of non-redundant (or irreducible) complexity. It doesn't matter if the mutation is actually present. It is the construction of the pathway that makes it redundant or not. Behe successfully refuted the claim that all biochemical systems have redundant components. Indeed all genetic diseases – more than thousand have now been found in humans – are examples of non-redundant or irreducible biochemical systems. All genetic diseases apparently have no compensating pathways. This is another way of looking at genetic diseases, but otherwise not remarkable. What is remarkable is what follows from Behe's logic:
Finally: why did the Designer create a vitamin-C pseudogene (17) in humans and intact vitamin-C genes in other animals? A beautiful animation of this can be found at YouTube (recommended!).
Muscular Dystrophy as an example of Hidden Redundant ComplexityBy Hidden Redundant Complexity I mean that a copy of a gene exists, but is not expressed. This may result in a genetic disease. For example Duchenne Muscular Dystrophy (a devastating muscular disorder) is caused by a mutation in the dystrophin gene. So this seems to be a case of nonredundant or irreducible complexity, because the defect is not compensated. However there is a fully functional fetal version of the gene (utrophin) that is active in the fetus, but not in the adult. There is evidence (18) that this fetal gene could cure Duchenne patients if only the gene was expressed after birth! So in fact this is a case of hidden redundant or reducible complexity, because a 'redundant' copy of the gene is present. Wouldn't it be easy for an Intelligent Designer to implement a switch mechanism that turned on a (fetal) copy of a gene in case a (adult) gene is damaged? (23). It is tragic that children have to die because an intact gene that could save their lives is not turned on! And why did the designer not install a backup copy of the dystrophin gene in the first place?
Implementing design in DNAIf a human designer implements his design in wood and if his product must be permanent then he should prevent rot. If a human designer uses iron to implement his design he should prevent oxidation if his creation must be permanent. He had better use gold instead or eliminate oxygen from the atmosphere. If a human designer implements his design in DNA he should know that DNA is mutable. If he wants a permanent product then DNA is not the best choice. Beforehand it is known that mutations arise with a predictable frequency. That follows from the laws of physics and chemistry. And that is what we observe. So far the design language. In scientific language we say that mutations create, modify or destroy genes. DNA is stable enough to permit long term inheritance, but unstable enough to permit evolution.
Unethical designIn chapter 3 Behe concludes that the cilium is irreducibly complex (p65) and that Darwinian theory has given no explanation for the cilium or flagellum (p73). In other words: the cilium is intelligently designed.
I discovered that Trypanosoma brucei, the cause of sleeping sickness in humans, has a cilium. This single-celled parasite is passed to humans through the bite of the tsetse fly. If left untreated, the infection progresses to death within months or years. Pharmaceutical industry is not interested in production of the medicines because African countries are too poor to buy them.
Stage II sleeping sickness involves the nervous system. Gambian sleeping sickness, in particular, has a clearly delineated phase in which the predominant symptoms involve the brain. The patient's speech becomes slurred, mental processes slow, and the patient sits and stares for long periods of time, or sleeps. Other symptoms resemble Parkinson's disease, including imbalance when walking, slow and shuffling gait, trembling of the limbs, involuntary movements, muscle tightness, and increasing mental confusion. Untreated, these symptoms eventually lead to coma and then to death (20).Now why would an Intelligent Designer give such a destructive parasite a beautifully designed irreducibly complex cilium? And why would an Intelligent Designer create such a cruel parasite in the first place? Of course this is not a disproof of a Designer, it is only a disproof of a benevolent Designer. If Irreducible complexity leads to a designer then it is a designer who allows or creates suffering (22). It is not my idea to introduce ethics in the discussion of the evolution-creation controversy. It was already present in the tradition of British natural theology:
"the Power, Wisdom, and Goodness of God, as manifested in his Creation" (27)
Other examples of un-ethical intelligent design are: Salmonella bacterium with flagellum (see illustrations above) which causes salmonellosis (food poisoning) in humans (43); in Legionella the presence of flagella is necessary for infection, resulting in a potentially fatal form of pneumonia and an estimated 800 - 2700 deaths per year in the USA; the requirement for vitamins and genetic diseases such as muscular dystrophy, which I mentioned above. Vitamin A deficiency in developing countries results in the premature death of about a million children a year and leaves another five million children permanently blind. The dependence on an external source (diet) of essential vitamins is clearly not an ethical design of the human genome. The intelligent designer could have easily included the appropriate genes in the human genome, thereby preventing pain, suffering and death of millions of innocent children. That would be a morally useful form of 'guided evolution'. That would be a morally useful form of 'supernatural intervention'. But that does not happen.
Is design a scientific explanation?
By "intelligent design" I mean to imply design beyond the laws of nature." (13). (my emphasis).He means beyond the fine tuning of the laws of nature. Beyond the laws of nature is beyond biological science. So design is beyond biological science. Michael Ruse (2005) asked Behe "Do you mean that the Intelligent Designer suspends the laws of physics through working a miracle?", Behe replied "YES"." (35) Design is a miracle.
Design is like vitalismAccording to vitalism the difference between living and nonliving matter is that life has a 'vital force' which is absent from matter. That's why life cannot arise from non-life according to vitalism. The belief that living creatures contain molecules that cannot be made from nonliving precursors, or that living matter contains "vital force", died out in the nineteenth century (24). The refutation of vitalism was the synthesis of urea from inorganic substances by Friedrich Wöhler in 1828 and the synthesis of acetic acid from carbon disulfide by Adolph Kolbe in 1845. Just like nineteenth century scientists believed that 'organic' substances cannot be formed by dead substances, Michael Behe believes that 'irreducible' complex systems cannot be formed by a natural process such as evolution. Behe's 'intelligent designer' is an occult and immaterial force, just as vitalism was an occult and immaterial force. Biologists have come to despise vitalism and everything similar for good reasons (34).
Design is mentalismMentalistic explanations are explanations using psychological concepts such as intention, purpose and motive. The history of biology is a struggle to eliminate mentalism. To Behe's credit Irreducible Complexity itself is not a mentalistic concept. However the concept of 'Irreducible Complexity' is strongly connected with the concept 'Intelligent Designer'. The concept of an Intelligent Designer certainly is a mentalistic concept, because it is a person with a mind, motives and intentions (25). So Behe tried to introduce into biology something that biologists eliminated more than a century ago. Obviously a regression.
Design is essentialismEssentialism means biological species (organisms, genes) have an essence and variations are unimportant. Ernst Mayr (30) pointed out that biologists before Darwin were essentialists. This was under the influence of physics and chemistry. All atoms of oxygen are the same. There are no variations. But biologists after Darwin recognised that species and individuals have no essence and that variations are crucial. Mayr called this new way of thinking 'population thinking'. Design thinking is essentialism because it beliefs that the created Genesis kinds ('basic types') are important and that variations are limited and unimportant. Typically in design thinking, variations and mutations are interpreted as degeneration of the 'original' type. In population thinking variations are the raw material for natural selection and evolution.
Design is scientifically a dead end'Design' is a sterile hypothesis. 'Design' is scientifically a dead end, because it discourages research into the possible natural mechanisms that could have produced design-like features. Design is a lazy explanation. It stops research. And since there is no independent scientific method to know more about the hypothetical designer, we had better study nature directly as it is. So 'design' is a superfluous concept in science. Compare 'design' with evolution: evolutionists cannot repeat 3 billion years of evolution in the lab, but they can subject a laboratory population of fish, flies or bacteria to selection, vary selection intensity, vary mutation rates, etc and study the outcomes. So evolutionary research is experimental. How can an 'Intelligent Design Theorist' do laboratory experiments with God's powers?
God in the laboratoryDespite the fact that evolution is a historical process, evolutionary mechanisms are operating now in nature and in the lab. Is the designer operating now and not only during the six creation days? Then that should also be demonstrable in nature and in the lab. Additionally: how do we perform the control experiments where the God-factor is excluded? If design is beyond the laws of nature, then demonstrating the designer's actions in the laboratory is impossible by definition. Then 'intelligent design' cannot be science.
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|Copyright © 1997 G.Korthof||First published: Apr 26 1997||Update: 2 May 2011 Notes/F.R.: 23 Mar 2012|