Irreducible complexity: Difference between revisions

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{{Intelligent Design}}

'''Irreducible complexity''' ('''IC''') is a seen as [[pseudoscience|pseudoscientific]] argument by pro-evolutionary sources, because it argues that certain [[biological system]]s cannot [[evolution|evolve]] by successive small modifications to pre-existing functional systems through [[natural selection]].<ref>*{{cite book |last= Forrest |first= Barbara |author-link= Barbara Forrest |url= http://www.centerforinquiry.net/uploads/attachments/intelligent-design.pdf |format= PDF |title= Understanding the Intelligent Design Creationist Movement: Its True Nature and Goals. A Position Paper from the Center for Inquiry, Office of Public Policy |date= May 2007 |publisher= Center for Inquiry, Inc. |place= Washington, D.C. |accessdate= 2007-08-22 |ref= harv}}.

*{{cite book |last= Smith |first= Jonathan C. |title= Pseudoscience and Extraordinary Claims of the Paranormal: A Critical Thinker's Toolkit |page= 307 |isbn= 1-40518-122-2 |ref= harv}}

*{{cite book |last= Shermer |first= Michael |title= The Skeptic Encyclopedia of Pseudoscience |publisher= ABC-CLIO |___location= Santa Barbara |year= 2002 |isbn= 1-57607-653-9 |page= 450 |ref= harv}}

*{{cite book |last= Shulman |first= Seth |title= Undermining Science |publisher= University of California Press |___location= Berkeley |year= 2008 |isbn= 0-520-25626-3 |page=139}}

*{{cite book |last= Pigliucci |first= Massimo |title= Nonsense on Stilts |publisher= University of Chicago Press |___location= Chicago |year= 2010 |isbn= 0-226-66786-3 |pages=177, 180–183}}</ref> Central to the [[creationism|creationist]] concept of [[intelligent design]], IC is rejected by the pro-evolutionary [[scientific community]],<ref name="dover_behe_ruling">"We therefore find that Professor Behe's claim for irreducible complexity has been refuted in peer-reviewed research papers and has been rejected by the scientific community at large." [[s:Kitzmiller v. Dover Area School District/4:Whether ID Is Science#Page 79 of 139|Ruling, Judge John E. Jones III, ''Kitzmiller v. Dover Area School District'']]</ref> which regards intelligent design as pseudoscience.<ref>"True in this latest creationist variant, advocates of so-called intelligent design ... use more slick, pseudoscientific language. They talk about things like 'irreducible complexity'" {{cite book |author=Shulman, Seth |title=Undermining science: suppression and distortion in the Bush Administration |publisher=University of California Press |___location=Berkeley |year=2006 |page=13 |isbn=0-520-24702-7}} "for most members of the mainstream scientific community, ID is not a scientific theory, but a creationist pseudoscience."<br/>{{cite journal |author=David Mu |title=Trojan Horse or Legitimate Science: Deconstructing the Debate over Intelligent Design |journal=Harvard Science Review |volume=19 |issue=1 |date=Fall 2005 |doi= |url=http://www.hcs.harvard.edu/~hsr/fall2005/mu.pdf}}<br/>{{cite journal |author=Perakh M |title=Why Intelligent Design Isn't Intelligent — Review of: Unintelligent Design |journal=Cell Biol Educ. |volume=4 |issue=2 |pages=121–2 |date=Summer 2005 |doi=10.1187/cbe.05-02-0071 |pmc=1103713}}<br/>Mark D. Decker. College of Biological Sciences, General Biology Program, University of Minnesota [http://www.texscience.org/files/faqs.htm Frequently Asked Questions About the Texas Science Textbook Adoption Controversy] "The Discovery Institute and ID proponents have a number of goals that they hope to achieve using disingenuous and mendacious methods of marketing, publicity, and political persuasion. They do not practice real science because that takes too long, but mainly because this method requires that one have actual evidence and logical reasons for one's conclusions, and the ID proponents just don't have those. If they had such resources, they would use them, and not the disreputable methods they actually use."<br/>See also [[list of scientific societies explicitly rejecting intelligent design]]</ref> Irreducible complexity is one of two main arguments used by intelligent design proponents, the other being [[specified complexity]].<ref name="LiveScience- msnbc.com">{{cite web |url=http://www.msnbc.msn.com/id/9452500/ns/technology_and_science-science/ |title=Why scientists dismiss 'intelligent design' - LiveScience |author=Ker Than|date=September 23, 2005 |publisher=[[msnbc.com]] |accessdate=2010-05-17}}</ref>

[[Michael Behe]], a professor of biochemistry at Lehigh University, first argued that irreducible complexity made evolution purely through natural selection of random mutations impossible.<ref>*{{cite book |last= Behe |first= Michael |title= Darwin's Black Box |publisher= Free Press |___location= New York |year= 1996 |isbn= 978-0-684-82754-4}}</ref> However, some evolutionists [[evolutionary biology|evolutionary biologists]] have demonstratedclaimed how such systems could have evolved naturally.<ref name="thornton2006"/><ref name="Redundant Complexity"/> There are many examples documented through comparative genomics showingproposing that complex molecular systems are formed by the addition of components as revealed by different temporal origins of their proteins.<ref>http://www.nature.com/nature/journal/v481/n7381/full/nature10724.html</ref><ref>http://www.biomedcentral.com/1471-2148/10/341</ref>

In the 2005 ''[[Kitzmiller v. Dover Area School District]]'' trial, Behe gave testimony on the subject of irreducible complexity. The court found that "Professor Behe's claim for irreducible complexity has been refuted in peer-reviewed research papers and has been rejected by the scientific community at large."<ref name="dover_behe_ruling"/> Yet, peer reviews are subject to the views (or bias) of those involved.

==Definitions==

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[[Georges Cuvier]] applied his principle of the ''correlation of parts'' to describe an animal from fragmentary remains. For Cuvier, this was related to another principle of his, the ''conditions of existence'', which excluded the possibility of [[transmutation of species]].<ref>See especially chapters VI and VII of {{cite book|author=William Coleman |title=Georges Cuvier, Zoologist: A Study in the History of Evolution Theory |___location=Cambridge, Massachusetts |publisher=Harvard University Press |year=1964}} See also the discussion of these principles in the Wikipedia article on Cuvier.</ref>

While he did not originate the term, [[Charles Darwin]] identified the argument as a possible way to falsify a prediction of the theory of evolution at the outset. In ''[[The Origin of Species]]'', he wrote, "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. But I can find out no such case."<ref>[[Charles Darwin|Darwin, Charles]] (1859). ''[[The Origin of Species|On the Origin of Species]]''. London: John Murray. [http://darwin-online.org.uk/content/frameset?itemID=F373&viewtype=side&pageseq=207 page 189, Chapter VI]</ref> Darwin's theory of evolution challenges the teleological argument by postulating an alternative explanation to that of an intelligent designer—namely, evolution by natural selection. By showingclaiming howthat simple unintelligent forces can ratchet up designs of extraordinary complexity without invoking outside design, Darwin showedbelieved that an intelligent designer was not the necessary conclusion to draw from complexity in nature. The argument from irreducible complexity attempts to demonstrate that certain biological features cannot be purely the product of Darwinian evolution.<ref>See for example, {{cite book|author=Alan R. Rogers|title=The Evidence for Evolution|___location=Chicago|publisher=University of Chicago Press|year=2011|isbn=978-0-226-72382-2|pages=37–38, 48–49}} citing Joseph John Murphy accepting natural selection within limits, excepting "the eye" with its multiple parts. {{cite news|author=Joseph John Murphy|title=Presidential Address to the Belfast Natural History and Philosophical Society|journal=Northern Whig|___location=Belfast|date=November 19, 1866|url=http://darwin-online.org.uk/content/frameset?viewtype=image&itemID=CUL-DAR226.1.118-119&pageseq=1}}</ref>

In the late 19th century, in a dispute between supporters of the adequacy of [[natural selection]] and those who held for [[inheritance of acquired characteristics]], one of the arguments made repeatedly by [[Herbert Spencer]], and followed by others, depended on what Spencer referred to as ''co-adaptation'' of ''co-operative'' parts, as in: "We come now to Professor [[August Weismann|Weismann]]'s endeavour to disprove my second thesis — that it is impossible to explain by natural selection alone the co-adaptation of co-operative parts. It is thirty years since this was set forth in "The Principles of Biology." In §166, I instanced the enormous horns of the extinct [[Irish elk]], and contended that in this and in kindred cases, where for the efficient use of some one enlarged part many other parts have to be simultaneously enlarged, it is out of the question to suppose that they can have all spontaneously varied in the required proportions."<ref>Page 594 in: {{cite journal|author=Herbert Spencer|title=Weismannism Once More|journal=[[The Contemporary Review]]|date= October 1894|volume=66 |pages=592–608}} Another essay of his treating this concept is: {{cite journal|author=Herbert Spencer |title=The Inadequacy of "Natural Selection" |journal=The Contemporary Review |volume= 63 |year=1893 |pages= 153–166}} (Part I: February) and pages 439-456 (Part II: March). These essays were reprinted in {{cite book|author=Herbert Spencer|title=The Works of Herbert Spencer|year=1891|place=London|publisher=Williams and Norgate|volume=17}} (also Osnabrück: Otto Zeller, 1967). See also part III, Chapter XII, §166, pages 449-457 in: {{cite book |author=Herbert Spencer |title= Principles of Biology |year= 1864 |place=London |publisher=Williams and Norgate|volume=I}} And: {{cite journal|journal=[[The Nineteenth Century (periodical)|The Nineteenth Century]] |author=Herbert Spencer|title=The Factors of Organic Evolution |volume=19 |year=1886 |pages=570–589}} (Part I: April) and pages 749-770 (Part II: May). "Factors" was reprinted in pages 389-466 of {{cite book|author=Herbert Spencer|title=The Works of Herbert Spencer|volume=13|___location=London|publisher=Williams and Norgate|year=1891}} (also Osnabrück: Otto Zeller, 1967)= volume 1 of ''Essays: Scientific, Political, and Speculative''.</ref><ref>One example of a response was in Section III(γ) pages 32-42 of {{cite book|author=August Weismann |chapter=The Selection theory |pages=19–65 |title=Darwin and Modern Science: Essays in Commemoration of the Centenary of the Birth of Charles Darwin and of the Fiftieth Anniversary of the Publication of The Origin of Species|editor=[[Albert Charles Seward]]|___location=Cambridge |publisher=Cambridge University Press |year=1909}} See also Chapter VII, §12(1), pages 237-238 in: {{cite book|author=[[J. Arthur Thomson]]|title=Heredity|place=London|publisher=John Murray|year=1908}} Both of these referred to what has become known as the [[Baldwin effect]]. An analysis of both sides of the issue is: {{cite book |author=[[George John Romanes]] |title=Darwin and After Darwin: Post-Darwinian Questions, Heredity, Utility |volume=II |chapter=III: Characters as Hereditary and Acquired (continued) |pages=60–102 |place=London |publisher=Longman, Green |year=1895}}</ref> Darwin responded to Spencer's objections in chapter XXV of ''[[The Variation of Animals and Plants under Domestication]]''.<ref>{{cite book|title=The Variation of Animals and Plants under Domestication|author=Charles Darwin|year=1868|___location=London|publisher=John Murray|chapter=XXV. Laws of Variation ''continued'' - Correlated Variability|volume=2|pages=321–338|url=http://darwin-online.org.uk/content/frameset?keywords=co%20ordinated&pageseq=236&itemID=F877.2&viewtype=text}} especially page 333 and following.</ref> The history of this concept in the dispute has been characterized: "An older and more religious tradition of idealist thinkers were committed to the explanation of complex adaptive contrivances by intelligent design. ... Another line of thinkers, unified by the recurrent publications of Herbert Spencer, also saw [[co-adaptation]] as a composed, irreducible whole, but sought to explain it by the inheritance of acquired characteristics."<ref>Pages 67-68 in: {{cite journal|author=[[Mark Ridley (zoologist)|Mark Ridley]]|title=Coadapatation and the Inadequacy of Natural Selection|journal=British Journal for the History of Science |volume=15|issue=1 |date=March 1982 |pages=45–68 |doi=10.1017/S0007087400018938}}</ref>

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In 1974, [[young Earth creationism|young Earth creationist]] [[Henry M. Morris]] introduced a similar concept in his book ''Scientific Creationism'' in which he wrote; "This issue can actually be attacked quantitatively, using simple principles of mathematical probability. The problem is simply whether a complex system, in which many components function unitedly together, and in which each component is uniquely necessary to the efficient functioning of the whole, could ever arise by random processes."<ref>{{cite book |author=[[Henry M. Morris|Morris, Henry]] |title=Scientific creationism |publisher=Creation-Life Publishers |___location=San Diego, Calif |year=1974 |page=59 |isbn=0-89051-003-2 |edition=2nd}}</ref>

A book-length study of a concept similar to irreducible complexity, explainedattempted to explain by gradual, step-wise, non-teleological evolution, was published in 1975 by [[Thomas H. Frazzetta]]. "A complex adaptation is one constructed of ''several'' components that must blend together operationally to make the adaptation "work". It is analogous to a machine whose performance depends upon careful cooperation among its parts. In the case of the machine, no single part can greatly be altered without changing the performance of the entire machine." The machine that he chose as an analog is the [[Peaucellier–Lipkin linkage]], and one biological system given extended description was the jaw apparatus of a python. The conclusion ofhe thisasserted investigationwas, rather than that evolution of a complex adaptation was impossible, "awed by the adaptations of living things, to be stunned by their complexity and suitability", was "to accept the inescapable but not humiliating fact that much of mankind can be seen in a tree or a lizard."<ref>T. H. Frazzetta, ''Complex Adaptations in Evolving Populations'', Sunderland, Massachusetts: Sinauer Associates, 1975. ISBN 0-87893-194-5. Referencing pages 3, 4-7, 7-20, and xi, respectively.</ref>

In 1981, Ariel Roth, in defense of the [[creation science]] position in the trial ''[[McLean v. Arkansas]]'', said of "complex integrated structures" that "This system would not be functional until all the parts were there ... How did these parts survive during evolution ...?"<ref>{{cite book |author1=Keough, Mark J. |author2=Geisler, Norman L. |title=The Creator in the courtroom "Scopes II": the 1981 Arkansas creation-evolution trial |publisher=Mott Media |___location=Milford, Mich |year=1982 |page=146 |isbn=0-88062-020-X |url=http://www.antievolution.org/projects/mclean/new_site/docs/geislerbook.htm#Chapter%20Seven}}</ref>

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Behe additionally testified that the presence of irreducible complexity in organisms would not rule out the involvement of evolutionary mechanisms in the development of organic life. He further testified that he knew of no earlier "peer reviewed articles in scientific journals discussing the intelligent design of the blood clotting cascade," but that there were "probably a large number of peer reviewed articles in science journals that demonstrate that the blood clotting system is indeed a purposeful arrangement of parts of great complexity and sophistication."<ref>Behe, Michael 2005 [[Wikisource:Kitzmiller v. Dover Area School District/4:Whether ID Is Science#Page 88 of 139|Kitzmiller v. Dover Area School District 4: whether ID is science (p. 88)]]</ref> (The judge ruled that "intelligent design is not science and is essentially religious in nature".)<ref>[[s:Kitzmiller v. Dover Area School District/6:Curriculum, Conclusion#H. Conclusion|Kitzmiller v. Dover Area School District 6: Conclusion, section H]]</ref>

According to the theory of evolution, genetic variations occur without specific design or intent. The environment "selects" the variants that have the highest fitness by random chance, which are then passed on to the next generation of organisms. Change occurs by the gradual operation of designed natural forces over time, perhaps slowly, perhaps more quickly (see [[punctuated equilibrium]]). This process is able to luckily [[adaptation|adapt]] complex structures from simpler beginnings, or accidentally convert complex structures from one function to another (see [[spandrel (biology)|spandrel]]). MostSome intelligent design advocates acceptthink that evolution occurs through mutation and natural selection at the "[[microevolution|micro level]]", such as changing the relative frequency of various beak lengths in finches, but assert that it cannot account for irreducible complexity, because none of the parts of an irreducible system would be functional or advantageous until the entire system is in place. Others reject that mutations can cause any trans-formative benefit beyond the micro-evolutionary level, since a finch is still a finch whether its beak is longer or shorter or curved.

===The mousetrap example===

[[File:Mausefalle 300px.jpg|thumb|200px|[[Michael Behe]] believes that many aspects of life show evidence of design, using the [[mousetrap]] in an analogy disputed by others.<ref name=trap>[http://udel.edu/~mcdonald/mousetrap.html A reducibly complex mousetrap] (graphics-intensive, requires [[JavaScript]])</ref>]]

Behe uses the mousetrap as an illustrative example of this concept. A mousetrap consists of five interacting pieces: the base, the catch, the spring, the hammer, and the hold-down bar. All of these must be in place for the mousetrap to work, as the removal of any one piece destroys the function of the mousetrap. Likewise, he asserts that biological systems require multiple parts working together in order to function. Intelligent design advocates claim that natural selection could not create from scratch those systems for which science is currently unable to find a viable evolutionary pathway of successive, slight modifications, because the selectable function is only present when all parts are assembled and the intermediary steps involve in its supposed formation involve multiple non-functional changes.

In his 2008 book ''[[Only A Theory]]'', biologist [[Kenneth R. Miller]] challenges Behe's claim that the mousetrap is irreducibly complex. Miller observesasserts that various subsets of the five components can be devised to form cooperative units, ones that have different functions from the mousetrap and so, in biological terms, could form functional [[spandrel (biology)|spandrels]] before being adapted to the new function of catching mice. In an example taken from his high school experience, Miller recalls that one of his classmates<blockquote>...struck upon the brilliant idea of using an old, broken mousetrap as a spitball catapult, and it worked brilliantly.... It had worked perfectly as something other than a mousetrap.... my rowdy friend had pulled a couple of parts --probably the hold-down bar and catch-- off the trap to make it easier to conceal and more effective as a catapult... [leaving] the base, the spring, and the hammer. Not much of a mousetrap, but a helluva spitball launcher.... I realized why [Behe's] mousetrap analogy had bothered me. It was wrong. The mousetrap is not irreducibly complex after all.<ref name=Only>{{cite book |title= Only A Theory |first= Kenneth R. |last= Miller |___location= New York |year= 2008 |publisher= Viking Penguin |pages= 54–55 |isbn= 978-0-670-01883-3}}</ref></blockquote>

Other systems identified by Miller that include mousetrap components include the following:<ref name= Only/>

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*remove the hold-down bar for use as a toothpick (single element system)

The pointclaim of the reduction is that - in biology - most or all of the components were asserted to be already at hand, by the time it became necessary to build a mousetrap. Such a supposition, though, does not explain the development of those precursor parts, nor how they came together to form a completely new mechanism. As such, it requiredalleges farthat fewerit stepsfar easier to developbuild a mousetrapmouse trap than toIntelligent designDesigner allproponents suggest. Yet, Evolutionists incorrectly simplify the componentsissue as a "one step" assembly of already existing parts by glossing over the complexity of those parts and their supposed final assembly into a new, fromfunctioning scratchmechanism.

Behe refutes the attempt to over simplify the mouse trap <ref>http://www.arn.org/docs/behe/mb_mousetrapdefended.htm</ref>. He argues that a "conceptual precursor" is not the same thing as a "physical precursor". In other words, similarity in appearance does not prove, explain or substantiate a physical step by step development.

Thus the development of the mousetrap, said to consist of five different parts which had no function on their own, has been reduced to one step: the assembly from parts that are already present, performing other functions.

The Intelligent Design argument focuses on the functionality to catch mice. It skips over the case that many, if not all, parts are already available in their own right, at the time that the need for a mousetrap arises.

===Consequences of irreducible complexity===

Supporters of intelligent design argue that anything less than the complete form of such a system or organ would not work at all, or would in fact be a ''detriment'' to the organism, and would therefore never survive the process of natural selection. Although theysome Creationists have acceptaccepted that some complex systems and organs ''can'' be explained by evolution, they claim that organs and biological features which are ''irreducibly complex'' cannot be explained by current models, and that an intelligent designer must have created life or guided its evolution. Yet, Creationists who take this view are seen as compromising with Evolutionary bias and peer pressure. Accordingly, the debate on irreducible complexity concerns two questions: whether irreducible complexity can be found in nature, and what significance it would have if it did exist in nature.{{Citation needed|date=January 2012}}

Behe's original examples of irreducibly complex mechanisms included the bacterial [[flagellum]] of ''[[Escherichia coli|E. coli]]'', [[coagulation|the blood clotting cascade]], [[cilia]], and the [[adaptive immune system]].

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<blockquote>An irreducibly complex system cannot be produced directly (that is, by continuously improving the initial function, which continues to work by the same mechanism) by slight, successive modifications of a precursor system, because any precursor to an irreducibly complex system that is missing a part is by definition nonfunctional.</blockquote>

IrreducibleSome see irreducible complexity is not anas argumenta thatdenial of evolution does not occur, but rather an argument that it is "incomplete". In the last chapter of ''[[Darwin's Black Box]]'', Behe goes on to explain his view that irreducible complexity is evidence for [[intelligent design]]. Mainstream critics, however, argue that irreducible complexity, as defined by Behe, can be generated by known evolutionary mechanisms. Behe's claim that no scientific literature adequately modeled the origins of biochemical systems through evolutionary mechanisms has been challenged by [[TalkOrigins Archive|TalkOrigins]].<ref>[http://www.talkorigins.org/indexcc/CA/CA350.html Claim CA350: Professional literature is silent on the subject of the evolution of biochemical systems] TalkOrigins Archive.</ref><ref>{{cite book |last= Behe |first= Michael J. |authorlink= Michael Behe |title= Darwin's black box: the biochemical challenge to evolution |isbn= 0-684-82754-9 |page= 72 |chapter= |quote= "Yet here again the evolutionary literature is totally missing. No scientist has ever published a model to account for the gradual evolution of this extraordinary molecular machine." |year= 1996 |publisher= Free Press |___location= New York, NY |origyear= 1996}}</ref> The judge in the ''Dover'' trial wrote "By defining irreducible complexity in the way that he has, Professor Behe attempts to exclude the phenomenon of [[exaptation]] by definitional fiat, ignoring as he does so abundant evidence which refutes his argument. Notably, the [[United States National Academy of Sciences|NAS]] has rejected Professor Behe's claim for irreducible complexity..."<ref name=kitz74>[[s:Kitzmiller v. Dover Area School District/4:Whether ID Is Science#Page 74 of 139|Ruling]], [[Kitzmiller v. Dover Area School District]], December 2005. Page 74.</ref>

==Stated examples==

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The process of blood clotting or [[coagulation]] cascade in vertebrates is a complex biological pathway which is given as an example of apparent irreducible complexity.<ref>Action, George [http://www.talkorigins.org/origins/postmonth/feb97.html "Behe and the Blood Clotting Cascade"]</ref>

The irreducible complexity argument assumesreasons that since the removal of parts produces a complete collapse, the necessary parts of a system must have always been necessary,present and therefore could not have been added sequentially. However, some allege that in evolution, something which is at first merely advantageous can later become necessary.<ref>{{cite journal |last=Boudry |first=Maarten |authorlink=Maarten Boudry |last2=Blancke |first2=Stefaan |last3=Braeckman |first3=Johan |authorlink3=Johan Braeckman |title=Irreducible Incoherence and Intelligent Design: A Look into the Conceptual Toolbox of a Pseudoscience |journal=[[Quarterly Review of Biology]] |volume=85 |issue=3 |pages=473–82 |publisher= |date=September 2010 |url=http://sites.google.com/site/maartenboudry/irreducible-incoherence |issn= |doi=10.1086/656904 |accessdate= |pmid=21243965}}</ref> [[Natural selection]] can lead to complex biochemical systems being built up from simpler systems, or to existing functional systems being recombined as a new system with a different function.<ref name=kitz74/> For example, one of the clotting factors that Behe listed as a part of the clotting cascade ([[Factor XII]], also called Hageman factor) was later found to be absent in whales, demonstrating that it is not essential for a clotting system.<ref>{{cite journal |vauthors=Semba U, Shibuya Y, Okabe H, Yamamoto T |title=Whale Hageman factor (factor XII): prevented production due to pseudogene conversion |journal=Thromb Res |year=1998 |pages=31–7 |volume=90 |issue=1 |pmid=9678675 |doi= 10.1016/S0049-3848(97)00307-1}}</ref> Many purportedly irreducible structures can be found in other organisms as much simpler systems that utilize fewer parts. These systems, in turn, may have had even simpler precursors that are now extinct. Behe has responded to critics of his clotting cascade arguments by suggesting that [[homology (biology)|homology]] is evidence for evolution, but not for natural selection.<ref>Behe, Michael [http://www.arn.org/docs/behe/mb_indefenseofbloodclottingcascade.htm "In Defense of the Irreducibility of the Blood Clotting Cascade: Response to Russell Doolittle, Ken Miller and Keith Robison"]</ref>

The "improbability argument" is also misrepresentsdenied by evolutionists as a misrepresentation of natural selection. It is correct to say that a set of simultaneous mutations that form a complex protein structure is so unlikely as to be unfeasible, but that is not what Darwin advocated. His explanation iswas based on small accumulated physical changes thatto takethe placemacro structure without a final goal in mind. Each step must be advantageous in its own right, he claimed, although biologists may not yet understand the reason behind all of them—for example, [[jawless fish]] accomplish blood clotting with just six proteins instead of the full ten.<ref>[http://www.newscientist.com/article/mg18725073.800 Creationism special: A sceptic's guide to intelligent design], New Scientist, 9 July 2005</ref> Still, the statistical improbability of one beneficial mutation after the other, building up again and again is staggeringly prohibitive.

===Eye===

{{Main|Evolution of the eye}}

[[File:Stages in the evolution of the eye.png|thumb|300px|Stages in the evolution of the eye<br/>(a) A pigment spot<br/>(b) A simple pigment cup<br/>(c) The simple optic cup found in [[abalone]]<br/>(d) The complex lensed eye of the marine snail and the octopus]]

The [[eye]] is an example of a supposedly irreducibly complex structure, due to its many elaborate and interlocking parts, seemingly all dependent upon one another. It is frequently cited by intelligent design and creationism advocates as an example of irreducible complexity. Behe used the "development of the eye problem" as evidence for intelligent design in ''Darwin's Black Box''. Although Behe acknowledged that the evolution of the larger anatomical features of the eye have been well-explained, he claimed that the complexity of the minute biochemical reactions required at a molecular level for light sensitivity still defies explanation. Creationist [[Jonathan Sarfati]] has described the eye as evolutionary biologists' "greatest challenge as an example of superb 'irreducible complexity' in God's creation", specifically pointing to the supposed "vast complexity" required for transparency.<ref name="aig">[[Jonathan Sarfati|Sarfati, Jonathan]] (2000). [http://www.answersingenesis.org/home/area/re2/chapter10.asp Argument: 'Irreducible complexity'], from ''[[Refuting Evolution]]'' ([[Answers in Genesis]]).</ref>{{failed verification|redirects to http://www.answersingenesis.org/get-answers/topic/design-features, an unauthored blog|date=June 2012}}

InEvolutionists anclaim that Darwin is often misquoted <ref>[http://www.talkorigins.org/indexcc/CA/CA113_1.html CA113.1: Evolution of the eye]</ref> passage fromin ''[[On the Origin of Species]]'', since [[Charles Darwin]] appears to acknowledgeacknowledges the eye's development as a difficulty for his theory. However, the quote in context shows that Darwin actually had a very good understanding of the evolution of the eye (see [[fallacy of quoting out of context]]). He notes that "to suppose that the eye ... could have been formed by natural selection, seems, I freely confess, absurd in the highest possible degree". Yet this observation was merely a [[procatalepsis|rhetorical device]] for Darwin. Heagain goes on to explain that if gradual evolution of the eye could be shown to be possiblestates, "the difficulty of believing that a perfect and complex eye could be formed by natural selection ... can hardly be considered real". He then proceeded to roughlyspeculate map outon a likelypossible course for evolution using examples of gradually more complex eyes of various species.<ref>[[Charles Darwin|Darwin, Charles]] (1859). ''[[The Origin of Species|On the Origin of Species]]''. London: John Murray. [http://darwin-online.org.uk/content/frameset?itemID=F373&viewtype=side&pageseq=204 pages 186ff, Chapter VI]</ref> This explanation, though, is suspect does to its speculative nature. As Behe explains in "Darwin's Black Box" and on his website, a "conceptual precursor" does not prove that a "physical precursor" has occurred. Also, even a "simple" eye is composed of not so simple cells in a not so simple arrangement. Irreducible complexity is inescapable in any form of eye apparatus.

[[File:Evolution eye.svg|thumb|left|200px|The eyes of vertebrates (left) and invertebrates such as the [[octopus]] (right) developed independently: vertebrates evolved an inverted [[retina]] with a [[blind spot (vision)|blind spot]] over their [[optic disc]], whereas octopuses avoided this with a non-inverted retina.]]

Since Darwin's day, evolutionists' claim that the eye's ancestry has become much better understood. Although learning about the construction of ancient eyes through fossil evidence is problematic due to the soft tissues leaving no imprint or remains, genetic and comparative anatomical evidence has increasinglybeen supportedclaimed as support for the idea of a common ancestry for all eyes.<ref>{{cite journal |vauthors=Halder G, Callaerts P, Gehring WJ |title=New perspectives on eye evolution |journal=Current Opinion in Genetics & Development |volume=5 |issue=5 |pages=602–9 |date=October 1995 |pmid=8664548 |url=http://linkinghub.elsevier.com/retrieve/pii/0959-437X(95)80029-8 |doi=10.1016/0959-437X(95)80029-8}}</ref><ref>{{cite journal |vauthors=Halder G, Callaerts P, Gehring WJ |title=Induction of ectopic eyes by targeted expression of the eyeless gene in Drosophila |journal=Science |volume=267 |issue=5205 |pages=1788–92 |date=March 1995 |pmid=7892602 |url=http://www.sciencemag.org/cgi/pmidlookup?view=long&pmid=7892602 |doi=10.1126/science.7892602 |bibcode=1995Sci...267.1788H}}</ref><ref>{{cite journal |vauthors=Tomarev SI, Callaerts P, Kos L, etal |title=Squid Pax-6 and eye development |journal=Proc Natl Acad Sci USA. |volume=94 |issue=6 |pages=2421–6 |date=March 1997 |pmid=9122210 |pmc=20103 |url=http://www.pnas.org/cgi/pmidlookup?view=long&pmid=9122210 |doi=10.1073/pnas.94.6.2421 |bibcode=1997PNAS...94.2421T}}</ref> Yet again, similarity in concept does not prove something to be a physical precursor.

CurrentEvolutionists evidenceclaim doesthat current evidence suggestsuggests possible evolutionary lineages for the origins of the anatomical features of the eye. One likely chain of development is that the eyes originated as "simple patches" of [[photoreceptor cell]]s that could detect the presence or absence of light, but not its direction. When, via "random mutation" across the population, the photosensitive cells happened to have developed on a small depression, it endowed the organism with a better sense of the light's source. This small change gave the organism an advantage over those without the mutation. This genetic trait would then be "selected for" as those with the trait would have an increased chance of survival, and therefore progeny, over those without the trait. Individuals with deeper depressions would be able to discern changes in light over a wider field than those individuals with shallower depressions. As ever deeper depressions were advantageous to the organism, gradually, this depression would become a pit into which light would strike certain cells depending on its angle. The organism slowly gained increasingly precise visual information. And again, this gradual process continued as individuals having a slightly shrunken [[aperture]] of the eye had an advantage over those without the mutation as an aperture increases how [[collimated]] the light is at any one specific group of photoreceptors. As this trait developed, the eye became effectively a [[pinhole camera]] which allowed the organism to dimly make out shapes—the [[nautilus]] is a modern example of an animal with such an eye. Finally, via this same selection process, a protective layer of transparent cells over the aperture was differentiated into a crude [[lens (anatomy)|lens]], and the interior of the eye was filled with humours to assist in focusing images.<ref>Fernald, Russell D. (2001). [http://www.karger.com/gazette/64/fernald/art_1_1.htm The Evolution of Eyes: Why Do We See What We See?] ''Karger Gazette'' 64: "The Eye in Focus".</ref><ref>{{cite book |author=Fernald RD |chapter=Aquatic Adaptations in Fish Eyes |editor=Atema J |title=Sensory biology of aquatic animals |publisher=Springer-Verlag |___location=Berlin |year=1988 |isbn=0-387-96373-1}}</ref><ref>{{cite journal |author=Fernald RD |title=The evolution of eyes |journal=Brain Behav Evol. |volume=50 |issue=4 |pages=253–9 |year=1997 |pmid=9310200 |doi=10.1159/000113339}}</ref> In this way, eyes are recognizedsupposed by modern evolutionary biologists as actually a relatively unambiguous and simple structure to evolve, and many of the major developments of the eye's evolution are believed to have taken place over only a few million years, during the [[Cambrian explosion]].<ref>{{cite book |author=Conway-Morris S |title=The Crucible of Creation: The Burgess Shale and the Rise of Animals |publisher=Oxford University Press |___location=Oxford [Oxfordshire] |year=1999 |pages= |isbn=0-19-286202-2}}</ref>

But Michael Behe maintains that such explanations tend to simplify and gloss over the complexity of light sensitivity at the molecular level and that the minute biochemical reactions required for those first "simple patches of photoreceptor[s]" still defies explanation. Other intelligent design proponents claim that the evolution of the entire visual system would be difficult rather than the eye alone.<ref>{{cite book|title=A Meaningful World|year=2006|author1=Benjamin Wiker |author2=Jonathan Witt |page=44}}</ref>

===Flagella===

Line 131 ⟶ 129:

The [[flagella]] of certain bacteria constitute a [[molecular motor]] requiring the interaction of about 40 different protein parts. Behe presents this as a prime example of an irreducibly complex structure defined as "a single system composed of several well-matched, interacting parts that contribute to the basic function, wherein the removal of any one of the parts causes the system to effectively cease functioning", and argues that since "an irreducibly complex system that is missing a part is by definition nonfunctional", it could not have evolved gradually through [[natural selection]].<ref name="Flagellum Unspun"/>

'''Reducible complexity'''. InSome contrastassert tothat Behe's claims are false, pointing to the many proteins that can be deleted or mutated and the flagellum still works, even though sometimes at reduced efficiency.<ref>{{cite journal |vauthors=Rajagopala SV, Titz B, Goll J, Parrish JR, Wohlbold K, McKevitt MT, Palzkill T, Mori H, ((Finley RL Jr)), Uetz P |year= 2007 |title= The protein network of bacterial motility |url= |journal= Mol Syst Biol. |volume= 3 |issue= |page= 128 |doi= 10.1038/msb4100166 |pmid= 17667950 |pmc=1943423}}</ref> InIt fact,is true that the composition of flagella is surprisingly diverse across bacteria with many proteins only found in some species but not others.<ref>{{cite journal |vauthors=Titz B, Rajagopala SV, Ester C, Häuser R, Uetz P |date= Nov 2006 |title= Novel conserved assembly factor of the bacterial flagellum |url= |journal= J Bacteriol |volume= 188 |issue= 21 |pages= 7700–6 |doi= 10.1128/JB.00820-06 |pmid= 16936039}}</ref> HenceBut thethis flagellardoes apparatusnot isprove clearlythat verythe flexibleapparatus evolved in evolutionarystages termsat and perfectly able to lose or gainthe protein componentslevel. Further studies have shownbeen that, contraryappealed to claims of "irreducible complexity", flagella and related [[protein targeting|protein transport mechanisms]], showto evidence ofsupport evolution through Darwinian processes, providingasserting case studies in howthat complex systems can evolve from simpler components.<ref>{{cite journal |last1= Pallen |first1= M. J. |last2= Gophna |first2= U. |doi= 10.1159/000107602 |title= Bacterial Flagella and Type III Secretion: Case Studies in the Evolution of Complexity |journal= Gene and Protein Evolution |series= Genome Dynamics |volume= 3 |pages= 30–47 |year= 2007 |isbn= 3-8055-8340-0 |pmid= |pmc=}}</ref><ref>{{cite journal |last1= Clements |first1= A. |last2= Bursac |first2= D. |last3= Gatsos |first3= X. |last4= Perry |first4= A. |last5= Civciristov |first5= S. |last6= Celik |first6= N. |last7= Likic |first7= V. |last8= Poggio |first8= S. |last9= Jacobs-Wagner |first9= C. |last10= Strugnell |first10= R. A. |last11= Lithgow |first11= T. |title= The reducible complexity of a mitochondrial molecular machine |journal= Proceedings of the National Academy of Sciences of the United States of America |volume= 106 |issue= 37 |pages= 15791–15795 |year= 2009 |pmid= 19717453 |pmc= 2747197 |doi= 10.1073/pnas.0908264106|bibcode= 2009PNAS..10615791C}}</ref> Yet, a flagella made of differing proteins is still a flagella.

'''Evolution from Type Three Secretion Systems'''. Scientists regard this argument as having been disproved in the light of research dating back to 1996 as well as more recent findings.<ref name="Flagellum Unspun">Miller, Kenneth R. [http://www.millerandlevine.com/km/evol/design2/article.html The Flagellum Unspun: The Collapse of "Irreducible Complexity"] with reply here [http://www.designinference.com/documents/2003.02.Miller_Response.htm]</ref><ref>{{cite journal |last1=Pallen |first1=M.J. |last2=Matzke |first2=N.J. |year=2006 |title=From ''The Origin of Species'' to the origin of bacterial flagella |journal=Nature Reviews Microbiology |volume=4 |issue= 10|pages=784–790 |publisher= |doi=10.1038/nrmicro1493 |url= |accessdate= |pmid=16953248}}</ref> They point out that the basal body of the flagella has been found to be similar to the [[Type three secretion system|Type III secretion system]] (TTSS), a needle-like structure that pathogenic germs such as ''[[Salmonella]]'' and ''[[Yersinia pestis]]'' use to inject [[toxin]]s into living [[eucaryote]] cells. The needle's base has ten elements in common with the flagellum, but it is missing forty of the proteins that make a flagellum work.<ref>[http://www.youtube.com/watch?v=RQQ7ubVIqo4 Kenneth Miller's The Collapse of Intelligent Design: Section 5 Bacterial Flagellum] (Case Western Reserve University, 2006 January 3)</ref> The TTSS system negatesclaims to negate Behe's claim that taking away any one of the flagellum's parts would prevent the system from functioning. On this basis, [[Kenneth R. Miller|Kenneth Miller]] notes that, "The parts of this supposedly irreducibly complex system actually have functions of their own."<ref>[http://web.archive.org/web/20071010035647/http://debatebothsides.com/showthread.php?t=38338 Unlocking cell secrets bolsters evolutionists] (Chicago Tribune, 2006 February 13)</ref><ref>[http://www.talkdesign.org/faqs/flagellum.html Evolution in (Brownian) space: a model for the origin of the bacterial flagellum] (Talk Design, 2006 September)</ref> The concept of the wheel has been applied in many forms. Yet, who will say that a bicycle wheel is an evolutionary, physical precursor to a car tire? Similarity in parts does not prove that one functioning part evolved to form a new functioning mechanism.

Dembski has argued that phylogenetically, the TTSS is found in a narrow range of bacteria which makes it seem to him to be a late innovation, whereas flagella are widespread throughout many bacterial groups, and he argues that it was an early innovation.<ref>[http://www.evolutionnews.org/2010/01/spinning_tales_about_the_bacte031141.html Spinning Tales About the Bacterial Flagellum]</ref><ref>Dembski, [http://www.designinference.com/documents/2005.09.Expert_Rebuttal_Dembski.pdf Rebuttal to Reports by Opposing Expert Witnesses, p. 52]</ref> Against Dembski's argument, different flagella use completely different mechanisms, and publications showallege a plausible path in which bacterial flagella could have evolved from a secretion system.<ref name="CB200.1:">{{cite web |last= Isaak |first= Mark |title= CB200.1: Bacterial flagella and Irreducibly Complexity |url= http://www.talkorigins.org/indexcc/CB/CB200_1.html |publisher= TalkOrigins Archive |year= 2006 |accessdate= 25 June 2013}}</ref>

==Response of the scientific community==

Like intelligent design, the concept it seeks to support, irreducible complexity has failedbeen toridiculed gainand anymarginalized notableby acceptanceevolutionists withinin the [[scientific community]]. One science writer called it a "full-blown intellectual surrender strategy".<ref>Mirsky, Steve [http://www.sciam.com/article.cfm?articleID=00022DE1-0C15-11E6-B75283414B7F0000 Sticker Shock: In the beginning was the cautionary advisory] ''Scientific American'', February 2005</ref> Never-the-less, evolutionary scientists cannot accurately claim to stand uniquely above the rest of the scientific community <ref>http://www.scienceagainstevolution.org/v5i10f.htm</ref>.

===Reducibility of "irreducible" systems===

Researchers have proposed potentially viablepotential evolutionary pathways for allegedly irreducibly complex systems such as blood clotting, the immune system<ref>Matt Inlay, 2002. "[http://www.talkdesign.org/faqs/Evolving_Immunity.html Evolving Immunity]." In ''TalkDesign.org''.</ref> and the flagellum<ref>Nicholas J. Matzke, 2003. "[http://www.talkdesign.org/faqs/flagellum_background.html Evolution in (Brownian) space: a model for the origin of the bacterial flagellum]."</ref><ref>{{cite journal |vauthors=Pallen MJ, Matzke NJ |title= From The Origin of Species to the origin of bacterial flagella |journal= Nature Reviews Microbiology |volume= 4 |issue= 10 |pages= 784–90 |date= October 2006 |pmid= 16953248 |doi= 10.1038/nrmicro1493 |url= http://www.pandasthumb.org/archives/2006/09/flagellum_evolu.html}}</ref> - the three examples Behe proposed. John H. McDonald even showed his example of a mousetrap to be reducible.<ref name=trap/> IfIt is claimed that if irreducible complexity is an insurmountable obstacle to evolution, it should not be possible to conceive of such pathways.<ref>Pigliucci, Massimo [http://www.infidels.org/library/modern/features/2000/pigliucci1.html] Collaboration Sept. 2001</ref> But as Behe has indicated, a conceptual precursor is not the same as a physical precursor. Just because one can imagine and conceptualize intermediary steps, does not prove that physical precursors have occurred.

Niall Shanks and Karl H. Joplin, both of [[East Tennessee State University]], have shownclaim that systems satisfying Behe's characterization of irreducible biochemical complexity can arise naturally and spontaneously as the result of self-organizing chemical processes.<ref name="Redundant Complexity">{{cite journal |doi=10.1086/392687 |author1=Shanks, Niall |author2=Joplin, Karl H. |title=Redundant Complexity: A Critical Analysis of Intelligent Design in Biochemistry |journal=Philosophy of Science |year= 1999 |pages= 268–282 |volume= 66 |issue= 2, June |publisher=The University of Chicago Press |jstor=188646}}</ref><!--not working <ref>Niall Shanks and Karl H. Joplin. [http://www.asa3.org/ASA/topics/Apologetics/POS6-99ShenksJoplin.html Redundant Complexity:A Critical Analysis of Intelligent Design in Biochemistry.] East Tennessee State University.</ref>--> They also assert that what evolved biochemical and molecular systems actually exhibit is "redundant complexity"—a kind of complexity that is the product of an evolved biochemical process. They claim that Behe overestimated the significance of irreducible complexity because of his simple, linear view of biochemical reactions, resulting in his taking snapshots of selective features of biological systems, structures, and processes, while ignoring the redundant complexity of the context in which those features are naturally embedded. They also criticized his over-reliance of overly simplistic metaphors, such as his mousetrap.

A computer model of the supposed co-evolution of proteins binding to DNA in the peer-reviewed journal ''[[Nucleic Acids Research]]'' consisted of several parts (DNA binders and DNA binding sites) which contribute to the basic function; removal of either one leads immediately to the death of the organism. This model fits the definition of irreducible complexity exactly, yet it evolves.<ref>{{cite journal |author=[[Thomas D. Schneider|Schneider TD]] |title=Evolution of Biological Information |journal= Nucleic Acids Research |year=2000 |pages=2794–2799 |volume=28 |issue=14 |pmid=10908337 |doi=10.1093/nar/28.14.2794}}</ref> (The program can be run from [http://alum.mit.edu/www/toms/papers/ev/ Ev program].)

Niall Shanks and Karl H. Joplin, both of [[East Tennessee State University]], have shown that systems satisfying Behe's characterization of irreducible biochemical complexity can arise naturally and spontaneously as the result of self-organizing chemical processes.<ref name="Redundant Complexity">{{cite journal |doi=10.1086/392687 |author1=Shanks, Niall |author2=Joplin, Karl H. |title=Redundant Complexity: A Critical Analysis of Intelligent Design in Biochemistry |journal=Philosophy of Science |year= 1999 |pages= 268–282 |volume= 66 |issue= 2, June |publisher=The University of Chicago Press |jstor=188646}}</ref><!--not working <ref>Niall Shanks and Karl H. Joplin. [http://www.asa3.org/ASA/topics/Apologetics/POS6-99ShenksJoplin.html Redundant Complexity:A Critical Analysis of Intelligent Design in Biochemistry.] East Tennessee State University.</ref>--> They also assert that what evolved biochemical and molecular systems actually exhibit is "redundant complexity"—a kind of complexity that is the product of an evolved biochemical process. They claim that Behe overestimated the significance of irreducible complexity because of his simple, linear view of biochemical reactions, resulting in his taking snapshots of selective features of biological systems, structures, and processes, while ignoring the redundant complexity of the context in which those features are naturally embedded. They also criticized his over-reliance of overly simplistic metaphors, such as his mousetrap.

AIn computeraddition, modelresearch of the co-evolution of proteins binding to DNApublished in the peer-reviewed journal ''[[NucleicNature Acids Research]](journal)|''Nature'']] consistedhas ofalleged severalthat partscomputer (DNAsimulations bindersof andevolution DNAdemonstrate bindingthat sites)it whichis contributepossible tofor thecomplex basic function; removal of either one leads immediatelyfeatures to the death of the organism. This model fits the definition of irreducible complexity exactly, yet itevolve evolvesnaturally.<ref>{{cite journal |author= [[Thomas D.Richard SchneiderLenski|SchneiderLenski TDRE]], Ofria C, Pennock RT, Adami C |title=Evolution The evolutionary origin of Biologicalcomplex Informationfeatures |journal= Nucleic Acids ResearchNature |year=2000 2003 |pages=2794–2799 139–44 |volume=28 423 |issue=14 6936 |pmid=10908337 12736677 |doi= 10.10931038/nar/28nature01568|bibcode= 2003Natur.14423.2794.139L}}</ref> (The program can be run from [http://alum.mit.edu/www/toms/papers/ev/ Ev program].)

OneIn canan compareattempt ato debunk the mousetrap withanalogy, some have compared a catmousetrap inwith thisa contextcat. Both normally function so as to control the mouse population. The cat has many parts that can be removed leaving it still functional; for example, its tail can be bobbed, or it can lose an ear in a fight. Comparing the cat and the mousetrap, then, oneevolutionists seesassert that the mousetrap (which is not alive) offers better evidence, in terms of irreducible complexity, for intelligent design than the cat.; Evenyet lookingproceed at the mousetrap analogy, several critics haveto described ways in which the parts of the mousetrap could have independent uses or could develop in stages, demonstrating that it is not irreducibly complex.<ref name=trap/><ref name=Only/> But again, Behe's book and website answer this. Conceptual similarities do not prove actual, real precursors. And adjustments to the perifieral anatomy of the cat (ears and tail) are irrelevant to the "irreducible complexity" argument.

In addition, research published in the peer-reviewed journal [[Nature (journal)|''Nature'']] has shown that computer simulations of evolution demonstrate that it is possible for complex features to evolve naturally.<ref>{{cite journal |author= [[Richard Lenski|Lenski RE]], Ofria C, Pennock RT, Adami C |title= The evolutionary origin of complex features |journal= Nature |year= 2003 |pages= 139–44 |volume= 423 |issue= 6936 |pmid= 12736677 |doi= 10.1038/nature01568|bibcode= 2003Natur.423..139L}}</ref>

One can compare a mousetrap with a cat in this context. Both normally function so as to control the mouse population. The cat has many parts that can be removed leaving it still functional; for example, its tail can be bobbed, or it can lose an ear in a fight. Comparing the cat and the mousetrap, then, one sees that the mousetrap (which is not alive) offers better evidence, in terms of irreducible complexity, for intelligent design than the cat. Even looking at the mousetrap analogy, several critics have described ways in which the parts of the mousetrap could have independent uses or could develop in stages, demonstrating that it is not irreducibly complex.<ref name=trap/><ref name=Only/>

Moreover,Some evolutionists affirm that even cases where removing a certain component in an organic system will cause the system to fail do not demonstrate that the system could not have been formed in a step-by-step, evolutionary process. ByYet, analogysuch an assertion falls short of answering irreducible complexity nor does it prove that gradual steps have occurred. In an attempted rebuttal of irreducible complexity, some appeal to stone arches which are asserted as irreducibly complex&mdash; that if you remove any stone the arch will collapse—yet humans [[arch#Construction|build them]] easily enough, one stone at a time, by building over [[centring|centering]] that is removed afterward. SimilarlyThe argument goes that, since [[natural arch|naturally occurring arches]] of stone form by the weathering away of bits of stone from a large concretion that has formed previously then this "proves" that the whole argument of irreducible complexity if false. Yet the argument for irreducible complexity is not answered by this. The argument is not that nothing is reducible; but that irreducibly complex things prove a necessary external input by intelligence. To sustain evolutionary opposition to the "irreducible complexity" argument, one would have to show actual examples of how irreducibly complex systems developed, not analogies of other reducible systems.

Evolution canis actclaimed to be able to both simplify as well as to complicate. This raises the possibilityarguable point that seemingly irreducibly complex biological features may have been achieved with a period of increasing complexity, followed by a period of simplification. Yet assertion alone is not proof. The scientific method demands more than hypothesizing as evidence.

A team led by [[Joseph Thornton (biologist)|Joseph Thornton]], assistant professor of biology at the [[University of Oregon]]'s Center for Ecology and Evolutionary Biology, using techniques for resurrecting ancient genes, reconstructed the evolution of an apparently irreducibly complex molecular system. The April 7, 2006 issue of ''Science'' published this research.<ref name="thornton2006">{{cite journal |vauthors=Bridgham JT, Carroll SM, Thornton JW |title=Evolution of hormone-receptor complexity by molecular exploitation |journal=Science |volume=312 |issue=5770 |pages=97–101 |date=April 2006 |pmid=16601189 |doi=10.1126/science.1123348 |bibcode= 2006Sci...312...97B}}</ref><ref>[http://www.discovery.org/scripts/viewDB/filesDB-download.php?command=download&id=746 Press release] University of Oregon, April 4, 2006.</ref>