Content deleted Content added
Undid revision 721936689 by 75.139.222.177 (talk) |
m clean up using AWB |
||
Line 29:
====Up to the 18th century====
[[Galen]] (1st and 2nd centuries AD) wrote about the large number of parts of the body and their relationships, which observation was cited as evidence for creation.<ref>''De Formatione Foetus''=''The Construction of the Embryo'', chapter 11 in ''Galen: Selected Works'', translated by P. N. Singer, ''The World's Classics'', Oxford, Oxford University Press, 1997 ISBN 978-0-19-282450-9. One 18th-century reference to Galen is [http://www.anselm.edu/homepage/dbanach/dnr.htm#A13 [[David Hume]] ''[[Dialogues Concerning Natural Religion]]'', 1779, Part 12], § 3, page 215. Also see Galen's ''De Usu Partium''=''On the Usefulness of the Parts of the Body'', translated and edited by Margaret Tallmadge May, Ithaca, New York, Cornell University Press, 1968, especially book XVII. For a relevant discussion of Galen and other ancients see pages 121-122, {{cite book |author=Goodman, Lenn Evan |title=Creation and evolution |___location=Milton Park, Abingdon, Oxon and New York |publisher=Routledge |year=2010 |isbn=978-0-415-91380-5}}</ref> The idea that the interdependence between parts would have implications for the origins of living things was raised by writers starting with [[Pierre Gassendi]] in the mid-17th century<ref>''De Generatione Animalium'', chapter III. Partial translation in: Howard B. Adelmann, ''Marcello Malpighi and the Evolution of Embryology'' Ithaca, New York, Cornell University Press, 1966, volume 2, pages 811-812.</ref> and [[John Wilkins]], who wrote (citing Galen), "Now to imagine, that all these things, according to their several kinds, could be brought into this regular frame and order, to which such an infinite number of Intentions are required, without the contrivance of some wise Agent, must needs be irrational in the highest degree."<ref>John Wilkins,''Of the Principles and Duties of Natural Religion'', London, 1675, book I, chapter 6, page 82.</ref> In the late 17th century, [[Thomas Burnet]] referred to "a multitude of pieces aptly joyn'd" to argue against the [[eternity]] of life.<ref>[http://www.sacred-texts.com/earth/ste/ste07.htm ''The Sacred Theory of the Earth''], 2nd edition, London: Walter Kettilby, 1691. Book I Chapter IV page 43</ref> In the early 18th century, [[Nicolas Malebranche]]<ref>{{cite book|author=Nicolas Malebranche|title=De la recherche de la verité: où l'on traite de la nature de l'esprit de l'homme, & de l'usage qu'il en doit faire pour éviter l'erreur dans les sciences|edition=6ième|___location=Paris|publisher=Chez Michel David|year=1712|url=https://books.google.com/books?id=Gi0_AAAAcAAJ&pg=RA1-PA57&vq=%22d%C3%A9pendent%20mutuellement%22}} Livre 6ième, 2ième partie, chapître 4; English translation: {{cite book|author=Nicholas Malebranche|title=The Search After Truth: With Elucidations of The Search After Truth|
====19th century====
Line 49:
A book-length study of a concept similar to irreducible complexity, explained 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 of this investigation, 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 |
In 1985 [[Graham Cairns-Smith|Cairns-Smith]] wrote of "interlocking": "How can a complex collaboration between components evolve in small steps?" and used the analogy of the scaffolding called [[centring|centering]] used to [[arch#Construction|build an arch]] then removed afterwards: "Surely there was 'scaffolding'. Before the multitudinous components of present biochemistry could come to lean together ''they had to lean on something else.''"<ref>{{cite book |author=Cairns-Smith, A. G. |title=Seven clues to the origin of life: a scientific detective story |publisher=Cambridge University Press |___location=Cambridge, UK |year=1985 |pages=39, 58–64 |isbn=0-521-27522-9}}</ref><ref>McShea, Daniel W. and Wim Hordijk. "[http://link.springer.com/article/10.1007%2Fs11692-013-9227-6 Complexity by Subtraction]." ''Evolutionary Biology'' (April 2013). [http://www.worldwidewanderings.net/Professional/Publications/complsub.pdf PDF].</ref> However, neither Muller or Cairns-Smith claimed that their ideas were evidence of something supernatural.<ref>{{cite journal |url=http://www.skeptic.com/the_magazine/ |title=Bacteria Flagella Look Like Man-made Machines |author=[[Mark Perakh]] |publisher=''[[Skeptic (U.S. magazine)]]'' |year=2008 |volume=14 |issue=3 |accessdate=2008-12-06}}</ref>
An essay in support of [[creationism]] published in 1994 referred to bacterial flagella as showing "multiple, integrated components", where "nothing about them works unless every one of their complexly fashioned and integrated components are in place" and asked the reader to "imagine the effects of natural selection on those organisms that fortuitously evolved the flagella ... without the concommitant {{sic}} control mechanisms".<ref>{{cite journal |author=Lumsden RD |title=Not So Blind A Watchmaker |journal=Creation Research Society Quarterly |volume=31 |issue=1 |pages=13–22, quotations from 13, 20 |date=June 1994}}</ref><ref>{{cite journal |
An early concept of irreducibly complex systems comes from [[Ludwig von Bertalanffy]], a 20th-century Austrian biologist.<ref>Ludwig von Bertalanffy (1952). ''Problems of Life: An Evaluation of Modern Biological and Scientific Thought, pg 148'' ISBN 1-131-79242-4</ref> He believed that complex systems must be examined as complete, [[irreducibility|irreducible]] systems in order to fully understand how they work. He extended his work on biological complexity into a general theory of systems in a book titled ''[[systems theory|General Systems Theory]]''.
Line 108:
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 assumes that the necessary parts of a system have always been necessary, and therefore could not have been added sequentially. However, 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 |
The "improbability argument" also misrepresents 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 is based on small accumulated changes that take place without a final goal. Each step must be advantageous in its own right, 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>
Line 121:
[[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, 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 increasingly supported the idea of a common ancestry for all eyes.<ref>{{cite journal |
Current evidence does suggest 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 recognized by modern 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>
Behe maintains that the complexity of light sensitivity at the molecular level and 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|
===Flagella===
Line 131:
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'''. In contrast to Behe's claims, many proteins can be deleted or mutated and the flagellum still works, even though sometimes at reduced efficiency.<ref>{{cite journal |
'''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 negates 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>
Line 141:
===Reducibility of "irreducible" systems===
Researchers have proposed potentially viable 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 |
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 |
A computer model of the 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].)
Line 155:
Evolution can act to simplify as well as to complicate. This raises the possibility that seemingly irreducibly complex biological features may have been achieved with a period of increasing complexity, followed by a period of simplification.
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 |
Irreducible complexity may not actually exist in nature, and the examples given by Behe and others may not in fact represent irreducible complexity, but can be explained in terms of simpler precursors. The theory of [[facilitated variation]] challenges irreducible complexity. [[Marc W. Kirschner]], a professor and chair of Department of Systems Biology at [[Harvard Medical School]], and [[John C. Gerhart]], a professor in Molecular and Cell Biology, [[University of California, Berkeley]], presented this theory in 2005. They describe how certain mutation and changes can cause apparent irreducible complexity. Thus, seemingly irreducibly complex structures are merely "very complex", or they are simply misunderstood or misrepresented.
Line 161:
===Gradual adaptation to new functions===
{{Main|Exaptation}}
The precursors of complex systems, when they are not useful in themselves, may be useful to perform other, unrelated functions. Evolutionary biologists argue that evolution often works in this kind of blind, haphazard manner in which the function of an early form is not necessarily the same as the function of the later form. The term used for this process is [[exaptation]]. The [[evolution of mammalian auditory ossicles|mammalian middle ear]] (derived from a jawbone) and the [[giant panda|panda]]'s thumb (derived from a wrist bone spur) provide classic examples. A 2006 article in ''Nature'' demonstrates intermediate states leading toward the development of the ear in a [[Devonian]] fish (about 360 million years ago).<ref>{{cite journal |journal= Nature |volume= 439 |pages= 318–21 |date= January 19, 2006 |
Arguments for irreducibility often assume that things started out the same way they ended up—as we see them now. However, that may not necessarily be the case. In the ''Dover'' trial an expert witness for the plaintiffs, Ken Miller, demonstrated this possibility using Behe's mousetrap analogy. By removing several parts, Miller made the object unusable as a mousetrap, but he pointed out that it was now a perfectly functional, if unstylish, [[tie clip]].<ref name=Only/><ref name=NOVAChapter8>{{cite web |url= http://www.pbs.org/wgbh/nova/transcripts/3416_id_08.html |title=NOVA: Transcripts: Judgment Day: Intelligent Design on Trial Chapter 8 |date= November 13, 2007 |publisher= [[Public Broadcasting Service|PBS]] |accessdate= 2008-12-17}}</ref>
Line 203:
*{{cite book |last= Denton |first= Michael |title= [[Evolution: A Theory in Crisis]] |publisher= Adler & Adler |___location= Bethesda, Md |year= 1986 |isbn= 0-917561-05-8 |ref= harv}}
*{{cite journal |author=Macnab RM |title=Type III flagellar protein export and flagellar assembly |journal=Biochim Biophys Acta |year=2004 |pages=207–17 |volume=1694 |issue=1-3 |pmid=15546667 |doi=10.1016/j.bbamcr.2004.04.005}}
*{{cite journal|
*Sunderland, Luther D. (March 1976). Miraculous Design in Woodpeckers. ''Creation Research Society Quarterly''.
*[http://www.carlzimmer.com/articles/2005/articles_2005_Avida.html Testing Darwin] [[Discover Magazine]] [http://www.discovermagazine.com/issues/feb-05/cover/ Vol. 26 No. 02] |February 2005
| |||