Darwinists Refute ID “Irreducible Complexity” Argument

first_img“New book explains how evolution really works, rebuts intelligent design.”  That’s the triumphant title of a new book announcement from Harvard Medical School, reported on EurekAlert.  According to the release, Marc W. Kirschner (Harvard Medical School) and John C. Gerhart (UC Berkeley) have addressed a “key problem in evolutionary theory that has puzzled scientists from Darwin on and which is now under intense scrutiny by proponents of intelligent design: where do the big jumps come from in evolution?” (emphasis added in all quotes.)  The product of their investigation is their new book The Plausibility of Life: Resolving Darwin’s Dilemma (Yale Univ. Press, 2005).  The answer, they claim, lies in newly-discovered molecular properties of organisms:The origin of novelty, the development of new arrangements of interlocking parts that some call “irreducibly complex,” can only be understood in the light of the last 20 years of research in cell biology and development.    We now know that the ‘parts’ that make up a living organism are very unlike the rigid parts designed for machines.  Instead, they can flexibly connect and re-connect, using the same pieces over and over to make new functions.    For example, one might think that a mutation that makes the neck of a giraffe longer would have to be accompanied by several other mutations, one that expands the length of the muscles of the neck, another that makes the blood vessels longer, and so on.  But instead, the muscles grow to fit the length of the bone and the blood vessels grow until all the muscles have a sufficient supply of oxygen.  Apparently very complex adaptations can therefore be achieved with few, simple mutations.    Today, it is understood for the first time that all animals use the same set of core processes to develop into adult forms.  Applying this knowledge to evolution, the authors show that novel traits emerge from the ways the organism is constructed: its complex mechanisms for adapting to the environment, its modular construction, and its internal circuitry that can be re-specified and reconnected.At first glance this sounds very Lamarckian, so let’s examine a book review by another evolutionist who published his remarks in the journal Cell.1  Douglas Erwin of the National Museum of Natural History in Washington DC was not all that impressed with their arguments.  In fact, he thinks the authors didn’t to their homework researching the abundant literature on the subject.  He did, however, appreciate the magnitude of the problem the book tried to address:The diversity and complexity of life on Earth—from bacteria and fungi to plants and animals—suggest the generation of remarkable variation upon which natural selection can act.  But how do new traits—new morphological architectures (bodyplans), developmental processes, and behaviors—arise?  Did the vertebrate brain and neural crest arise through processes that are different from those that generated new hairs on the legs of the fruit fly?  Can major evolutionary transitions in the history of life be explained by random variation—variation that is random with respect to the future needs of the organism—filtered through the process of natural selection?  These questions are not new, but the promise of a more mechanistic basis for answering them through comparative developmental biology imbues them with a fresh urgency.Erwin summarizes their argument: animals have evolved to evolve.  Variations acted on by natural selection have produced “phenotypic plasticity” or evolvability – they ability to adapt to changing environments (see 08/04/2004 entry on this idea).In Kirschner and Gerhart’s view, there are four aspects of gene regulation and development in animals that constrain the direction of heritable variation.  These are the extensive conservation across metazoa of certain regulatory patterns; a modular pattern of organismal design; what the authors term “weak linkages” in gene regulation, caused by, in their view, regulatory interactions that do not specify outcomes; and nondeterministic outcomes of development.To Erwin, what they are saying is, “natural selection needs some help.”  He denies it.  Natural selection can get along just fine without “random genetic variation that is biased toward viability, functional utility, and relevance to environmental conditions.”  He thinks that Kirschner and Gerhart don’t understand what random means:This is the first place where the authors get into trouble; for through much of the book they seem to fundamentally misunderstand how evolutionary biologists use the term “random.”  By random mutation, evolutionary biologists mean random with respect to the adaptive needs of the organism, not, as the authors would have it in the early part of the book, completely random in the sense that many nonevolutionary biologists may think of the word “random.”  One of Charles Darwin’s key insights was that the combination of undirected mutation and natural selection is a powerful positive force for evolutionary creativity (and not, as so many later biologists have suggested, merely a negative force).  Evolutionary biologists have long understood that the nature of variation depends critically on what has already evolved.  Indeed, there is a rich literature discussing how phylogeny, function, structure, and other features constrain evolutionary variation.  Kirschner and Gerhart ignore this uncomfortable fact, dismissing constraint as “a minor effect, or trivial, for example, in explaining why mollusks (sic) and echinoderms were less able to evolve wings than vertebrates.”  They refer to variation as random alterations that can have little positive impact or that “lead to catastrophic failure.”  This results in the appearance of some odd comments as, for example, when the authors claim that evolutionary biologists “do not commonly appreciate…”  that “present-day organisms come from previous organisms.”  Indeed.Want to meet a few?  he asks in effect.  He accuses them of a “limited view of the evolutionary literature” on the subject which “undercuts most of their own arguments” in favor of “facilitated variation.”    Erwin puts this new book into a new genre of books finding the current model of evolution incomplete.  Most other authors, however, have had the good sense not to proclaim a “major new scientific theory” or “an original, far-reaching recasting of evolutionary theory,” as these do in their Preface.  Erwin mentions several books that do a better job attempting to “solve problems of evolutionary innovation that remain unresolved by the Modern Synthesis, the reigning paradigm of evolution developed in the 1940s by Mayr, Simpson, Wright, Haldane, Dozhansky, Fischer, and others.”  He is not sure, though, that any combination of these books amounts to a revision of the Modern Synthesis.    Looking at the thesis of the book in more detail, Erwin cuts to the chase.  He says that Kirschner and Gerhart don’t recognize the effect of environment on variation. Presenting no evidence, they claim that these waves of innovation are not linked to changes in the physical environment.  In fact, one of the most exciting areas of current research addresses how the origin and spread of these innovations are linked to a variety of geochemical, climatic, and other changes.  These core processes—DNA, RNA, and protein synthesis, formation of the cytoskeleton, and limb patterning—have descended relatively unchanged since they first arose.Erwin does agree with them on one point: “most evolution within the Animal Kingdom since the Cambrian radiation of metazoans involved the carefully regulated deployment of these core processes,” and that environmental conditions can become a “rich source of new phenotypes” that can become “developmentally integrated and viable.”  For instance, mutations might exhibit “exploratory behavior” and the most useful will become stabilized:Kirschner and Gerhart invoke exploratory behavior as a means of avoiding what they view as an otherwise insurmountable difficulty: that novelty appears to require multiple, correlated changes from phenotype to function.Does a bacterial flagellum come to mind here?  Erwin also likes their “wonderful and most appropriate” term for the compartmentalization of network modules: “invisible anatomy.”  Here he praises the book:The most important part of this book is, in my view, the authors’ description of the evolutionary significance of the interactions between compartments and the conserved regulatory networks that underlie them via weak linkages [i.e., signals that trigger a response without specifying information about what the response should be].  Although the authors do not emphasize this sufficiently (at least for a paleontologist), this network of relationships imposes a developmental reality to the architectural forms described as body plans and generally characterized within Linnean systematics as phyla and classes.  As Kirschner and Gerhart note, this modularity of design often allows relatively independent evolution of different body parts without greatly increasing the coordination among them.  The gills, paddles, mouthparts, claws, and walking legs of various arthropods are all modifications of a single ancestral structure.  The modularity of arthropod body plans has enabled the rapid adaptation of limbs without inhibiting the workings of the whole animal.Now, to the “troubling” parts of the book.  Erwin is glad they have tackled “one of the most challenging issues in evolution,” and appreciates their insights as far as they go and as incomplete as their theory is.  But he criticizes the lack of justification and depth of detail that “leave far too much to the imagination of the reader.”  The book, therefore, “feels more like a vision of where the field should go rather than a thoroughly constructed theory of the origins of phenotypic novelty.”    To their credit, Kirschner and Gerhart tackle the problem of phenotypic novelty more forthrightly than other “revisionist” books like those of the late Stephen Jay Gould.  This leads Erwin to list some of the outstanding problems.  Some seem strong enough to make one wonder if evolutionary theory has ever really addressed the core questions Charles Darwin set out to solve:The generation of morphological variants is a critical issue, and several of these book authors have raised important questions and proposed new viewpoints.  But the generation of variation is only the beginning of the problem of evolutionary novelty.  Novel phenotypes succeed or fail based on their ecological relationships with other organisms and with the physical environment.  This ecological dimension is conspicuously lacking in these books, yet we cannot really understand novelty without it.  In particular, evolutionary biologists need to address such issues as how phenotypic “space” expands, how new niches are constructed, and related ecological events.One thing Erwin is sure of: in spite of all these fundamental issues challenging evolutionary theory, no one outside the Darwinian camp need apply:Is the neo-Darwinian view of evolution in need of reformation?  Certainly the diversity of rumblings indicates some degree of unhappiness, but evolutionary biologists have regularly published new models of evolution since the late 19th century (see Bowler, The Eclipse of Darwinism, Johns Hopkins, 1993).  Is there reason to think that our view of evolution needs to change?  The answer is almost certainly yes, although not, as the purveyors of creationism/intelligent design would have it, because the reality of evolution is under question.  Rather, we need to revise our view of evolution to reflect a more detailed understanding of how genetics and development both allow and facilitate phenotypic variation, to take into account the temporal dynamics of changes in the environment, and to incorporate the likelihood that there is selection and feedback at multiple levels (cell, tissue, organism, clade).  The central issues that need to be incorporated into evolutionary theory are the origin of phenotypic novelty and the discontinuous patterns of appearance of new phenotypes.Now wait – wasn’t that EurekAlert said that this book solves, putting to rest the claims of the intelligent design movement?  At the end of Erwin’s book review, is he still at square one?  He dismisses The Plausibility of Life as an “entertaining read” of only “introductory” value into recent trends in evolutionary theory.  In sum, it contains a lot of sound and fury, signifying little: “But with its sometimes troubling limitations, the book falls short of the major new theory that the authors promise in their introduction.”1Douglas H. Erwin, “A Variable Look at Evolution,” Cell, Volume 123, Issue 2, 21 October 2005, Pages 177-179, doi:10.1016/j.cell.2005.10.003.If you get a kick out of watching villains shoot themselves in the foot, you will rollick with this entry.  We provided extended quotes to let you savor the moment.  Here is the biggest problem in the history of evolutionary thought: the abrupt appearance of new body plans and complex structures with interrelated parts each necessary for function.  The Darwinists realize that the creationists and intelligent design proponents have been hammering them on the fact that they have no answers.  And finally, here was the new book that EurekAlert said was going to put those criticisms to rest once for all.  And what is it?  Blind search!  “Exploratory behavior” is putting feelers out in the dark and seeing if anything sticks.  But then what is leading the blind: the blind random variations in the molecules, or the blind random variations in the environment?  Can anyone really believe that a succession of blind actions will produce irreducibly complex systems like wings, gills, paddles, mouthparts, claws, legs, and rotating motors of exquisite design and efficiency?  If this book had the answer, Erwin would not have left it (“the origin of phenotypic novelty”) and “the discontinuous patterns of appearance” (e.g., the Cambrian Explosion), as unsolved problems.  Then Erwin did us the favor of pointing out that all the other books don’t solve them, either – though they have been trying since the 19th century.  [Quiz question: in what century did Charles Darwin write his famous book?]    If you found anything other than smoke and mirrors in all the mumbo-jumbo they came up with, go ahead and put your money in Darwin Circus stock.  That’s where the magicians have mastered the art of mass hypnosis, pointing their fingers into the air and and saying “watch this space” (e.g., 08/19/2004) till everyone is staring, mind-numbed, at nothing.  That’s where the clowns, wearing pink-tassled slippers and conical hats (see 04/01/2005) end their long comedy of errors act by shooting each other’s feet simultaneously.  One of their lines is starting to go over like a lead balloon, though.  That’s when they say the real clowns are the ones across the street at Philharmonic Hall, listening with soaring hearts and minds as the Maestro conducts hundreds of skilled players and singers in his masterpiece, The Creation.(Visited 23 times, 1 visits today)FacebookTwitterPinterestSave分享0last_img