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Topic: Theory of Punctuated Equilibrium


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In the News (Thu 20 Jun 19)

  
  Punctuated equilibrium - Wikipedia, the free encyclopedia
Punctuated equilibrium is commonly contrasted against the theory of phyletic gradualism, which hypothesizes that most evolution occurs uniformly and by the steady and gradual transformation of whole lineages (anagenesis).
Punctuated equilibrium differed from Mayr simply in that Eldredge and Gould had placed considerably greater emphasis on stasis, whereas Mayr was generally concerned with explaining the morphological discontinuity (or punctuational patterns) found in the fossil record.
Punctuated equilibrium is often confused with George Gaylord Simpson's quantum evolution, Richard Goldschmidt's saltationism, pre-Lyellian catastrophism, and the phenomenon of mass extinction.
en.wikipedia.org /wiki/Punctuated_equilibrium   (1595 words)

  
 Punctuated equilibrium
Punctuated equilibrium is a theory of evolution which postulates that changes such as speciation can occur very quickly, with long periods of little change (equilibria) in between.
The theory of punctuated equilibrium was proposed by Niles Eldredge and Stephen Jay Gould in the 1970s.
The theory of punctuated equilibrium is often misstated as being an explanation for purported "gaps in the fossil record", i.e.
www.guajara.com /wiki/en/wikipedia/p/pu/punctuated_equilibrium_1.html   (303 words)

  
 Punctuated equilibria - EvoWiki
Creationists commonly advance punctuated equilibrium as concession on the part of the paleontological community that evolution is not borne out by the fossil record, largely due to the way in which S. Gould presented it.
Punctuated equilibrium as advanced by Stanley (1975, 1981, 1982), Gould and Eldredge (1972, 1977), Eldredge (1984, 1985), Eldredge and Stanley (1984) and Gould (1980, 1982) and most vociferously espoused by Gould throughout the latter portion of his career, has come under significant criticism by a number of evolutionary biologists.
Carroll (1987; 1997) has emphasized that the defense of punctuated equilibrium using operational taxonomic units, per the method of Stanley (1981), is inherently flawed due to the limitations of the Linnean terminological infrastructure employed by taxonomic science, and emphasized that attention to anatomical detail and not taxonomic convention, precludes creating punctuated equilibria where none exist.
wiki.cotch.net /wiki.phtml?title=Punctuated_equilibrium   (600 words)

  
 Punctuated Equilibrium
Punctuated equilibrium, also called punctuated equilibria or the punctuational model, holds that genetic change occurs relatively rapidly on a geological timescale, and these shorter periods of evolution are sandwiched between longer periods of “stasis,”
Proponents of the punctuational model have relied heavily upon the work of mathematician Sewall Wright, who observed that novel variation was more likely to become fixed in small populations which were reproductively isolated (often due to geographic factors) from the main population.
One primary difference between the punctuational and gradualistic models of evolution is thus that under the gradualistic model, the entire parent population slowly morphs into the descendant species.
www.iscid.org /encyclopedia/Punctuated_Equilibrium   (703 words)

  
 The Dynamics of Evolution (Albert Somit, Steven Peterson)
Punctuated equilibrium is the idea that "most" evolutionary change happens in geologically "brief" speciation events separated by long periods of "stasis".
His essay is a general attack on the theory of punctuated equilibrium; he claims that the weak form (that rates of evolutionary change vary) is trivial and says nothing that wasn't known to Darwin, the strong from (macromutations and saltationism) is false, and the moderate form (widespread stasis in evolutionary lineages) is untestable.
Susan Cachel's "Punctuated Equilibrium and Evolutionary Anthropology" is rather peripheral to punctuated equilibrium, being an attack on the misuse of cladistic systematics in palaeoanthropology.
dannyreviews.com /h/The_Dynamics_of_Evolution.html   (1333 words)

  
 Evolution - A-Z - Punctuated equilibrium   (Site not responding. Last check: 2007-10-03)
Punctuated equilibrium is the theory put forward by Eldredge and Gould to explain the fact that the fossil record does not show smooth evolutionary transitions.
According to the theory of punctuated equilibrium, evolution proceeds relatively rapidly during speciation: between speciation events the population remains relatively constant in a condition called stasis.
Punctuated equilibrium can be contrasted with evolution by phyletic gradualism in which evolution occurs at a constant rate.
www.blackwellpublishing.com /ridley/a-z/Punctuated_equilibrium.asp   (176 words)

  
 Punctuated Equilibrium
Punctuated equilibrium should not be confused with saltationism, a theory in which a new species may arise in single generation through a macromutation.
Punctuated equilibrium predicts that the fossil record will display long gaps during which species change little or not at all, and that is exactly what the fossils do show (Ridley 1993, 513).
Dawkins (1986, 240-252) argues that punctuated equilibrium is not a "new" theory.
www.geocities.com /ginkgo100/pe.html   (2053 words)

  
 punctuated equilibrium
Fossil record gaps are identified as punctuated equilibrium in evolution — long stable periods interrupted by a series of sporadic durations of rapid radical...
There are two broad theories of evolution today: neo-Darwinism, represented by the likes of Richard Dawkins; and punctuated equilibrium, as held by the late...
I mentioned "punctuated equilibrium" (a term from evolutionary biology) yesterday as a balance between gradual and radical change; as used here, it means a...
www.mongabay.com /igapo/biotech/punctuated_equilibrium.html   (382 words)

  
 [No title]
To do this, I explore a theory of punctuated equilibrium, based on the emergence and recession of policy issues from the transnational policy agenda. Defining the current equilibrium and how it is punctuated is one goal of this paper.
Equilibrium Stability Walking through the creation and reformation of SF policy has demonstrated that stability is not always the result stemming from a punctuated equilibrium.
To this end, I demonstrated the utility of the theory by first identifying the status quo and how it was punctuated, and then moved to discuss the role of enlargement, as the “window of opportunity” for the innovation of SF policy.
international.tamu.edu /eunotes/Vol1_Issue4d.doc   (3025 words)

  
 Gradualism - CreationWiki
This concept, which is also known as phyletic gradualism, is in sharp contrast to the punctuated equilibrium theory later proposed by Niles Eldredge and Stephen Jay Gould to explain the absence of the intermediate fossils that Darwin predicted should exist if the theory of evolution were true.
Darwin predicted, in his book, that if his theory of evolution were true, there should be innumerable fossil creatures in the ground showing the change from one form of organism to another.
In an attempt to reconcile the differences between the fossil record and evolutionary theory, some evolutionists have adopted the theory of "punctuated equilibrium." Not surprisingly, many critics of evolution view "punctuated equilibrium" as simply an excuse for the absence of fossil evidence.
www.creationwiki.net /index.php?title=Gradualism   (578 words)

  
 Gould Strikes Back At Creationists   (Site not responding. Last check: 2007-10-03)
They have used Professor Gould's theory – which proposes long periods of stable "equilibrium" punctuated by sudden changes that are not captured as fossils – as proof that Darwinist "gradualism" was wrong and it should therefore be taught, at the very minimum, alongside creationism in schools.
Punctuated equilibrium is basically an attempt to down-play the lack of evidence in the fossils for phylogeny.
Punctuated equilibrium and neo-Darwinism are both now part of the evolutionists' grab-bag of conflicting theories as Gould now views punctuated equilibrium as an addition to evolutionary theory rather than an alternative.
www.freerepublic.com /focus/news/662640/posts   (4309 words)

  
 March 2001
Punctuated equilibrium posits a natural world that manifests species stability for great periods of time but occasionally ruptures or leaps from one species to another.
Not surprisingly, Marxist biologists are using the inability of the fossil record to sustain the weight of the Darwinian theory to bolster their theory of punctuated equilibrium.
In fact, the Marxist theory of history and society is merely an extension and distortion of Darwin’s theory of evolution.
www.schwarzreport.org /SchwarzReport/2001/may01.html   (4043 words)

  
 Stephen Jay Gould, "Opus 200," 1991
Punctuated equilibrium gains its rationale from the ideal also a standard component of the allopatric speciation theory, that most peripherally isolated populations are relatively small and undergo their characteristic changes at a rate that translates into geological time as an instant.
(Punctuated equilibrium, on the other hand, is a different theory of intermediacy for evolutionary trends—pushing a ball up an inclined plane for gradualism, climbing a staircase for punctuated equilibrium.) Some of our colleagues, in an all too common and literally perverse reaction, blamed us for this mayhem upon our theory.
Punctuated equilibrium has provided a new context for the most important phenomenon of paleontology—evolutionary trends (larger size in horses, more complex sutures in ammonites, bigger brains in humans).
www.stephenjaygould.org /library/gould_opus200.html   (3653 words)

  
 F550-599.p65
So it's not true to say that punctuated equilibrium is just an argument born of despair, because you don't see transitional forms.
First, it's been claimed that punctuated equilibrium is a theory of truly sudden saltation, that is, jump to a new form of life in a single generation.
The punctuations in punctuated equilibrium are in much smaller scale record the origin of new species.
www.antievolution.org /projects/mclean/mva_tt_p_f550-599.htm   (8566 words)

  
 Punctuated Equilibrium
According to this theory, history was punctuated by several catastrophes (I can't remember if they were all floods or not) that wiped out existing species, each followed by a brand new creation.
This theory proposes that new species arise in a *single* *generation*, by means of macromutations.
If one is going to discuss punctuated equilibrium and gradualism without a lot of confusion and misapprehension, then it is very important that the terms be defined as they were originally used by Eldridge and Gould (the authors of the original paper defining p.e.
www.dinosauria.com /jdp/evol/punk.htm   (1497 words)

  
 [No title]   (Site not responding. Last check: 2007-10-03)
Whether and when a policy equilibrium is punctuated depends on how the issues are portrayed, what symbols are used, and which institutions have jurisdiction over an issue.
Punctuations in the equilibrium occur when policy image changes and institutional changes combine to produce.
Conclusion: Teachers Unions and the Two Policy Process Theories I conclude that Baumgartner and Jones’s (1993) punctuated equilibrium theory does a better job than Kingdon’s (1984, 1995) of illustrating what I believe to be the power of teachers unions.
www.neiu.edu /~ourgift/media/FOR_DAY_THREE_Punctuated_Equilibrium_Theory_Primer.doc   (1365 words)

  
 Punctuated Equilibria
In this matter, the person attempting to come to a better understanding of punctuated equilibria will find that he or she may be hampered by the popular writings of those same authors rather than helped.
PE is not a saltational theory of evolution.
Punctuated equilibria: the tempo and mode of evolution reconsidered.
www.talkorigins.org /faqs/punc-eq.html   (3019 words)

  
 Conclusions -- Mass Extinction Events
In 1972, Eldredge and Gould introduced the idea of punctuated equilibrium; in contrast to phyletic gradualism, this theory states that long periods of evolutionary stasis are interrupted, or punctuated, by times of rapid evolution and speciation.
The extinction record itself is similar to the punctuated equilibrium pattern in that long stretches of low extinction rates (background rate) are interspersed with mass extincion events, which are analagous to Eldredge and Gould's rapid speciative bursts.
Thus, not only do punctuated equilibrium and the extinction record share a similar pattern, they are causitively related as well; that is speciation record could be seen almost as a time-lagged response to extinction.
www.earth.rochester.edu /ees207/Mass_Ext/higgins_mass5.html   (462 words)

  
 PUNCTUATED EQUILIBRIUM: AN ORGANIC MODEL FOR THE LEARNING ORGANISATION
We explain here the concept of punctuated equilibrium, as derived from geology and biology, and why it is important for managers to understand.
His answer was the theory of natural selection; the gradual re-enforcement through hundreds of generations of small differences between members of a species until gradually species were transmuted into new forms.
The punctuated equilibrium theory, applied to organisational evolution explains why entrepreneurship works, and incidentally why some organisations are unable to sustain excellence in the long term (see above on IBM case).
members.aol.com /ifprice/peqforum.html   (3404 words)

  
 Punctuated Equilibrium
instead of a slow, continuous movement, evolution tends to be characterized by long periods of virtual standstill ("equilibrium"), "punctuated" by episodes of very fast development of new forms.
The "punctuated equilibrium" theory of Niles Eldredge and Stephen Jay Gould was proposed as a criticism of the traditional Darwinian theory of evolution.
Punctuated equilibrium is more an observation than a theory of evolution.
pespmc1.vub.ac.be /punctueq.html   (587 words)

  
 [No title]   (Site not responding. Last check: 2007-10-03)
In the 1970s, Stephen Gould and his colleague Niles Eldredge proposed the theory of Punctuated Equilibrium, which was a resurgence of the ideas of Richard Goldschmidt as well as fundamental ideas dating back to Darwin.
This theory attempted to compensate for problems with the long established theory of phyletic gradualism that was proposed by Darwin.
The theory, defined as long periods of very little evolution [stasis] interrupted by periods of relatively rapid evolutionary change [punctuations], attempts to incorporate these two previously ignored classes of information.
www.cs.wisc.edu /~yandell/pbpg/Thompson.doc   (431 words)

  
 All You Need to Know about Punctuated Equilibrium (almost)
It is also probable that each great period of subsidence would be interrupted by oscillations of level, and that slight climatical changes would intervene during such lengthy periods; and in these cases the inhabitants of the archipelago would migrate, and no closely consecutive record of their modifications could be preserved in any one formation.
Eldredge and Gould based their theory of PE on the neontological theory of allopatric speciation (especially the allopatric theory of Ernst Mayr, which he called "peripatric" speciation) (Mayr 1963, 1971).
Punctuated equilibrium is a valid scientific hypothesis, and when geological strata are complete with good temporal resolution and the fossil record is well-represented, the hypothesis is testable.
ucsu.colorado.edu /~theobal/PE.html   (3214 words)

  
 CC201.1: Punctuated equilibrium for the gaps   (Site not responding. Last check: 2007-10-03)
The theory of punctuated equilibrium was proposed ad hoc to explain away the embarrassing gaps in the fossil record.
The theory of punctuated equilibrium is based on positive evidence, including extensive studies of living and extinct species groups (Eldredge and Gould 1972).
The idea of phyletic gradualism, which is invoked to justify a lack of gaps, fails to fit the evidence of population biology.
www.talkorigins.org /indexcc/CC/CC201_1.html   (110 words)

  
 Punctuated Equilibrium and Patterns from the Fossil Record   (Site not responding. Last check: 2007-10-03)
One strength of this theory is that Gould and Eldredge claim it is predicted by population genetics.
Yet punctuated equilibrium denies evolutionary change both these advantages as it compress the vast majority of origin of macroevolutionary change and biological novelty into the vast minority of the time, and small populations.
Punctuated equilibrium accepts the conventional idea that species form over hundreds or thousands of generations and through a series of intermediate stages.
acs.ucsd.edu /~idea/punceq.htm   (4529 words)

  
 SUBJECT: Book Review - The Dynamics of Evolution The Dynamics of Evolution - The Punctuate   (Site not responding. Last check: 2007-10-03)
Again it is evident that there is confusion as to whether (and how strongly) Gould actually pushed saltationism, but it is clear that he no longer does so; hence criticism of the "strong" version of punctuated equilibrium is now peripheral to the main debate.
On a similar note Brian Gladue argues that the punctuated equilibrium debate is irrelevant to psychobiology.
It seems to me that a punctuated model of human evolution could have important consequences; even if there is not enough data to say anything definite a bit of wild theorising wouldn't have gone amiss.
www.skepticfiles.org /evo2/puncteq.htm   (1239 words)

  
 Remembering Stephen Jay Gould (1941-2002)
This theory, known as punctuated equilibrium, was part of Dr. Gould's work that brought a forsaken paleontological perspective to the evolutionary mainstream.
Among scientists, he was known as a champion of the theory of "punctuated equilibria," which maintains that evolution is not a long and gradual process, but rather one that comes in sudden spurts after long stretches of little or no change in an organism.
The theory is based on the claim that the history of life is not one of smooth unbroken change, progressing always in an orderly and controlled matter, but is rather one of continency and sharp breaks, as life moves in jumps from one form to another.
www.stephenjaygould.org /inremembrance.html   (18910 words)

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