Darwin Devolves : The New Science About DNA That Challenges Evolution by Michael J. Behe

My rating: 5 of 5 stars


Of the many books on Darwinian evolution that I have read, the best fall into three different categories:

1. Scholastic dispute – these books start with a statement of the question to be addressed, such as “What is the origin of life?” or “What caused the Cambrian explosion?”, then consider philosophically the methodological tools to be used to answer the question, then look at the complete range of attempted solutions, and finally present the correct solution. Stephen Meyer’s books Signature in the Cell and Darwin’s Doubt are of this form.
2. Engineering problem – the angle of this type of book is to consider what it would take to build a living cell or an animal body or some other biological component. Based on our detailed knowledge of the components of living things, what would it take to assemble the parts? Michael Behe’s first two books Darwin’s Black Box and The Edge of Evolution are of this form.
3. Assumption checking – this last approach considers the fact that Darwin proposed his theory of random mutation and natural selection as a possible explanation of the emergence of new biological forms, that the theory relied on various assumptions that he made about nature, that science had not advanced sufficiently at the time to test those assumptions rigorously, but we are in a position now, 150 years later, to evaluate those assumptions with precise scientific data. The New Biology by Robert Augros and George Stanciu follows this approach.

Behe, in Darwin Devolves, definitely engages in the type of engineering analysis that made his first two books so effective, and dabbles in scholastic disputation, but the book as a whole is of the third type. Time and again, he repeats that we have much more scientific information available today that we did a century and a half ago, and even than we did twenty years ago. For instance, in the final chapter, Behe states:

Darwin did not show that apparently purposeful systems could be built by natural selection acting on random variation. Rather, he just proposed that they might. His theory had yet to be tested at the profound depths of life. In fact, no one then even realized life had such depths. Darwin built a case with the best science available in the nineteenth century. The case was pretty strong for a few of his theory’s multiple aspects, including the descent of modern organisms from earlier ones. It was extremely weak for his proposed mechanism of evolution. A major reason for its weakness is that the science of Darwin’s day had no understanding of the molecular foundation of life. Only now, only within the past twenty years has science advanced sufficiently to examine life in the molecular detail necessary to rigorously test Darwin’s ideas. (pp. 255-256)

So, that is exactly what Behe the biochemist sets out to do:
1. Note Darwin’s assumptions about the capabilities of random mutation and natural selection to account for the origin of new biological species.
2. Use the incredible advances of today’s science in the understanding of life’s molecular processes to evaluate what random mutation and natural selection can actually accomplish.
3. Compare the evidence of science with Darwin’s assumptions and draw conclusions about the real explanatory power of Darwin’s evolutionary mechanism.

So, first of all, what were Darwin’s assumptions (chapter 3)?

Darwin’s last theory—call it the ‘theory of natural coherence’—is the presumption that repeated rounds of random variation and natural selection would, by a succession of separate steps, build elegant compound interactive biological systems. (p. 89)

The important thing to note about this assumption is that Darwin makes evolution out to be a process that perfects in a cumulative fashion. It has successive stages that build on one another. It is not just a question of one change happening here and another disconnected change happening over there. Rather, it is change built upon change built upon change, over long periods of time, that progressively produces the panorama of living things.

Before using modern science to see whether these expectations of Darwin can be squared with biological reality, Behe first spends two chapters considering how other scientists have attempted to reconcile today’s knowledge with a century-and-a-half-old theory. All of these scientists realize that they have an extremely tough job on their hands, and they give it their best shot.

Chapter 4 speaks of neutral theory, which speculates that mutations that are neither advantageous nor disadvantageous pave the way for later advantageous mutations and so bring about new biological features; web of life theory, which opines that species of microorganisms might pass genes among themselves and so the long history of life has just been a constant interchange of genetic material that originated because we are part of an infinite multiverse in which everything possible happens an infinite number of times (not a joke!); and self-organization theory, which holds as a possibility that living things have the built-in capacity, under the right conditions, to organize themselves into other more complex living things.

Chapter 5 considers attempted improvements to neo-Darwinism that are classified as being part of an extended evolutionary synthesis (EES). The proponents of EES posit various mechanisms as being capable of enhancing the chances for Darwin’s theory to be plausible, such as:
• master genes: perhaps random changes in those genes could cause the development of new and complex features
• inclusive inheritance: perhaps traits that are not coded in DNA and are passed on to successive generations can cause more variations for natural selection to choose from
• niche construction: perhaps the way that animals interact with their environment causes genetic changes in animals
• developmental plasticity: perhaps plants and animals, in adjusting to their environments, alter their behavior so that they survive and, in doing so, pass on those alterations to the next generation
All of these ideas that are meant to help modern Darwinists to the explanatory finish line suffer from the same defect:

[N]either neutral theory nor complexity theory, neither the ideas of the extended evolutionary synthesis nor the latest Darwinian innovations—none of them even try to account for the sophisticated machinery of life. None even try to account for the purposeful arrangement of parts. (p. 137)

That is the million-dollar question to which Behe continually returns: where did ancestral plants and animals get their traits, and how did their lineages come to differ? EES does not attempt to answer that question and so is not able to really boost evolution’s explanatory power.

This leaves us with classic random mutation and natural selection. Are they able to account for the origin of species, as Darwin thought they could? Based on what we know today, the answer is: certainly not.
In chapter 6, Behe showcases various field studies that help us determine the reach of random mutation. Peter and Rosemary Grant did exhaustive investigations of the Galapagos finches and, using newly-developed techniques, sequenced the genomes of 120 of them, enabling them to determine which genes cause variation in the finches’ beak size. Similar studies were done on hundreds of species of cichlid fish in African lakes, with differences being traced all the way down to the level of the genome. In those cases and others cited by Behe, the changes were quite small and they were never sufficient to introduce a new biological family into the world (in the Linnaean system of taxonomical classification, species is the lowest level, then genus, then family).

We reach the heart of the book in chapter 7, as it provides the new information about random mutation that Darwin could not know:

The amazing but in retrospect unsurprising fact established by the diligent work of many investigators in laboratory evolution over decades is that the great majority of even beneficial positively selected mutations damage an organism’s genetic information—either degrading or outright destroying functional coded elements. (p. 183)

In other words, when random mutation provides a benefit to a plant or animal, it almost always does so by damaging its genetic material. Just as throwing cargo overboard can sometimes make for the survival of the crew, so too, in the world of life, the destruction of certain functions has sometimes provided lifeforms with a survival advantage. When it does, natural selection steps in to conserve the damaged genetic material. The plants or animals with certain debilitated functions are the ones that survive. Knowing this, we arrive at the shocking realization that the mechanism which Darwin hoped would cause an evolution actually causes a devolution.

Chapter 8 tracks what happens from there. After a random mutation that destroys functionality causes a survival advantage, the damaged genetic material spreads throughout a population. Once that takes place, there is no getting the good genes back again. You throw the cargo overboard in order to obtain a temporary advantage, but you have to suffer the long-term consequences: there is no way to retrieve the cargo.

Degrading machinery can be useful for some purposes—perhaps because its function is unneeded at the time, and so the scrapped machine doesn’t waste energy; or because in changed circumstances the product the machine made is now detrimental; or some other reason. But natural selection can’t build a coherent new system. (p. 201)

Natural selection preserves the degradation, and it cannot reconstruct the missing function. The reason is that natural selection is blind. Behe explains that it is a mere metaphor; there is no actual selection taking place. If there were, the selector could note that damaged animals might have a temporary survival advantage, but retaining them in the population would not be good in the long run. Since natural selection is blind—since it is simply a term saying that those who survive in nature are the ones more apt to survive—it “will favor the increase in the number of organisms that do better in their environment for any reason, regardless of the basis of the variation” (p. 203). And, as we have seen, in the vast majority of cases, the basis for doing better is a damaging of the genome.

What we have learned, then, through a more detailed knowledge of the molecular basis of life, is that the little variation that we are able to observe in nature as being caused by random mutation and natural selection—the appearance of new species and genera—is actually the result of loss of function and so devolution, reduces the possibility of any further change by restricting the variability of the genome, and provides no explanation for any notable feature of the biological world.

To emphasize just how inadequate empirical data has shown the Darwinian mechanism to be, Behe revisits his famous notion of “irreducible complexity” in chapter 9. There, he shows that we not only have no reasonable expectation that random mutation and natural selection can build systems that need all parts to be present for them to be functional (irreducibly complex systems), we can’t even expect it to be able to build the parts of those parts in anything close to the time needed (mini-irreducibly complex systems).

Behe is extremely kind to evolutionists throughout the book—including some vociferous opponents of his science—but be he ever so kind, or be he ever so Behe, he does have to ask the question: why are so many 21st century scientists sold on an idea that their own science has shown definitively to be utterly inadequate? Effectively, he believes it is due to two reasons (p. 218): a) they are believers in outdated mathematical studies that did not take into account biological reality as we know it today; b) they are unable to see the real problem that they have to solve, which is also the hardest problem, the million-dollar question mentioned above. Quoting Chesterton, he notes that they are “in the clean and well-lit prison of one idea” (p. 245).

The obsession with Darwinism leads some scientists to come up with the craziest of proposals—that mind is just the product of neural impulses, that our free will and desires do not really exist, and that reality is just a computer simulation. Besides the fact that these ideas, which Behe treats in chapter 10, destroy all scientific endeavor, they also manifest how humans can sometimes be willing to sacrifice their very rationality in order to hold on to a cherished idea.

It has been obvious to most everyone in the history of the world that the purposeful arrangement of parts that is manifest in every member of the biological world is the product of mind. Atheists like Richard Dawkins were hoping that random mutation and natural selection could prove that lifeforms are only apparently designed. People of common sense knew all along that they were building castles in the air. But now that Darwin’s mechanism has been tested at the molecular level of life, we can definitively show its utter inadequacy to account for anything of real moment in the world around us.

I highly recommend Darwin Devolves for an authentic 21st century scientific account of the explanatory power of Darwin’s theory. And while Behe does engage in some geek-talk occasionally, overall the book is extremely readable. It is loaded with the analogies for which Behe has a gift, movie references, and helpful diagrams and tables. Even for someone who is not conversant with the literature treating evolution, Darwin Devolves promises to be an interesting read.




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