Editing Punctuated equilibrium

{{Short description|Theory in evolutionary biology}}
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[[File:PunctuatedEquilibrium.png|thumb|The punctuated equilibrium model (top) consists of [[Morphology (biology)|morphological]] stability followed by rare bursts of evolutionary change via rapid cladogenesis – vertical equilibrium states separated by horizontal "jump" phases. In contrast, [[phyletic gradualism]] (below), is a more gradual, continuous model of evolution – with accumulation of small incremental changes represented by slanted bars that split at branch-points, where two separate modes of life are feasible but of which, each prospers best with divergent specializations.]]
{{evolutionary biology}}

In [[evolutionary biology]], '''punctuated equilibrium''' (also called '''punctuated equilibria''') is a [[Scientific theory|theory]] that proposes that once a [[species]] appears in the [[fossil record]], the population will become stable, showing little [[evolution|evolutionary change]] for most of its geological history.<ref name="pe1972">{{cite book
 |author1=Eldredge, Niles
 |author1-link=Niles Eldredge
 |author2=Gould, S.J.
 |author2-link=Stephen Jay Gould
 |year=1972
 |section=Punctuated equilibria: An alternative to phyletic gradualism
 |editor1=Schopf, T.J.M.
 |title=Models in Paleobiology
 |place=San Francisco, CA
 |publisher=Freeman Cooper
 |pages=82–115
 |section-url=http://www.blackwellpublishing.com/ridley/classictexts/eldredge.asp
 }}
:
''Reprinted in'' <br/>
{{cite book |editor=Eldredge, N. |title=Time Frames |place=Princeton, NJ |publisher=Princeton University Press |year=1985 |pages=193–223 |url=http://www.somosbacteriasyvirus.com/phyletic.pdf |access-date=2018-01-27 |archive-date=2020-01-13 |archive-url=https://web.archive.org/web/20200113152717/http://www.somosbacteriasyvirus.com/phyletic.pdf |url-status=dead }}
* {{cite journal
 |title=2nd draft (unpublished)
 |year=1972
 |doi=10.5531/sd.paleo.4
 |hdl=2246/6564
 |last1=Eldredge
 |first1=Niles
 |doi-access=free
 |hdl-access=free
 }}
* {{cite journal
 |title=3rd draft (final, published)
 |year=1972
 |doi=10.5531/sd.paleo.7
 |hdl=2246/6567
 |last1=Eldredge
 |first1=Niles
 |last2=Gould
 |first2=Stephen Jay
 |doi-access=free
 |hdl-access=free
 }}</ref> This state of little or no morphological change is called ''stasis''. When significant evolutionary change occurs, the theory proposes that it is generally restricted to rare and [[geologic time scale|geologically rapid]] events of branching speciation called [[cladogenesis]]. Cladogenesis is the process by which a species splits into two distinct species, rather than one species gradually transforming into another.

Punctuated equilibrium is commonly contrasted with [[phyletic gradualism]], the idea that evolution generally occurs uniformly by the steady and gradual transformation of whole lineages ([[anagenesis]]).<ref name="GouldNewScientist">{{cite magazine
 |author=Gould, S.J.
 |author-link=Stephen Jay Gould
 |date=15 April 1982
 |title=Punctuated equilibrium — a different way of seeing
 |magazine=[[New Scientist]]
 |volume=94
 |pages=137–139
 |url=https://books.google.com/books?id=504iVZyopJ8C&pg=PA137
 |via=Google Books
 }}{{Dead link|date=June 2024 |bot=InternetArchiveBot |fix-attempted=yes }}</ref>

In 1972, paleontologists [[Niles Eldredge]] and [[Stephen Jay Gould]] published a landmark paper developing their theory and called it ''punctuated equilibria''.<ref name="pe1972"/> Their paper built upon [[Ernst Mayr]]'s model of [[peripatric speciation|geographic speciation]],<ref name=Mayr1954>
{{cite book
 |author=Mayr, Ernst
 |year=1954
 |section=Change of genetic environment and evolution
 |editor1=Huxley, J. |editor2=Hardy, A.C. |editor3=Ford, E.B. 
 |title=Evolution as a Process
 |place=London, UK
 |publisher=Allen and Unwin
 |pages=157–180
 |section-url=http://www.blackwellpublishing.com/ridley/classictexts/mayr.asp
 |via=Blackwell Publishing
}}
</ref> [[I. Michael Lerner|I. M. Lerner]]'s theories of [[developmental homeostasis|developmental]] and [[genetic homeostasis]],<ref>
{{cite book 
 |author-link=I. Michael Lerner |author=Lerner, I.M.
 |year=1954
 |title=Genetic Homeostasis
 |place=New York, NY
 |publisher=John Wiley
}}
</ref>
and their own [[empirical research]].<ref name=eldredge1971>
{{cite journal
 |last=Eldredge |first=Niles |author-link=Niles Eldredge
 |date=1971
 |title=The allopatric model and phylogeny in Paleozoic invertebrates
 |journal=[[Evolution (journal)|Evolution]]
 |volume=25 |issue=1 |pages=156–167
 |doi=10.2307/2406508 |pmid=28562952
 |jstor=2406508 |hdl=2246/6568
}}
</ref><ref>
{{cite journal
 |last=Gould |first=S.J. |author-link=Stephen Jay Gould
 |date=1969
 |title=An evolutionary microcosm: Pleistocene and recent history of the land snail ''P.'' (''Poecilozonites'') in Bermuda
 |journal=Bull. Mus. Comp. Zool.
 |volume=138 |pages=407–532
}}
</ref> Eldredge and Gould proposed that the degree of gradualism commonly attributed to [[Charles Darwin]]<ref name="Rhodes">
{{cite journal
 |last1=Rhodes |first1=F.H.T. |author1-link=Frank H. T. Rhodes
 |year=1983
 |title=Gradualism, punctuated equilibrium and the ''Origin of Species''
 |journal=[[Nature (journal)|Nature]]
 |volume=305 |issue=5932 |pages=269–272
 |doi=10.1038/305269a0 |pmid=6353241
 |bibcode=1983Natur.305..269R |s2cid=32953263
 |url=http://www.stephenjaygould.org/library/rhodes_gradualism-origin.html
}}
</ref>
is virtually nonexistent in the fossil record, and that stasis dominates the history of most [[fossil]] species.

== History ==

Punctuated equilibrium originated as a logical consequence of [[Ernst Mayr]]'s concept of [[Founder effect|genetic revolutions]] by [[allopatric speciation|allopatric]] and especially [[peripatric speciation]] as applied to the fossil record. Although the sudden appearance of species and its relationship to speciation was proposed and identified by Mayr in 1954,<ref name=Mayr1954 /> [[history of science|historians of science]] generally recognize the 1972 Eldredge and Gould paper as the basis of the new [[paleobiology|paleobiological]] research program.<ref name="Mayr1992">[[Ernst Mayr|Mayr, Ernst]] (1992). "Speciational Evolution or Punctuated Equilibria." In Albert Somit and Steven Peterson ''The Dynamics of Evolution''. New York: Cornell University Press, pp. 21-48.</ref><ref>Shermer, Michael (2001). ''The Borderlands of Science''. New York: Oxford University Press, pp. [https://www.docdroid.net/29yd6nq/michael-shermer-the-paradox-of-the-paradigm.pdf 97-116.]{{Dead link|date=May 2025 |bot=InternetArchiveBot |fix-attempted=yes }}</ref><ref>Geary, Dana (2008). [https://books.google.com/books?id=6iVOHEVeSFMC&pg=PA127 "The Legacy of Punctuated equilibrium."] In Warren D. Allmon et al. ''Stephen Jay Gould: Reflections on His View of Life''. Oxford: Oxford University Press, pp. 127-145.</ref><ref>Prothero, D. (2007). [https://archive.org/details/evolutionwhatfos00prot_0/page/78 "Punk eek, Transitional Formsand Quote Miners."] In ''Evolution: what the fossils say and why it matters''. New York: Columbia University Press, pp.&nbsp;78–85.</ref> Punctuated equilibrium differs from Mayr's ideas mainly in that Eldredge and Gould placed considerably greater emphasis on stasis, whereas Mayr was concerned with explaining the [[Morphology (biology)|morphological]] discontinuity (or "sudden jumps")<ref>Schindewolf, Otto (1936). ''Paldontologie, Entwicklungslehre und Genetik''. Berlin: Borntraeger.</ref> found in the fossil record.<ref name="Mayr1992"/> Mayr later complimented Eldredge and Gould's paper, stating that evolutionary stasis had been "unexpected by most evolutionary biologists" and that punctuated equilibrium "had a major impact on paleontology and evolutionary biology."<ref name=Mayr1992 />

A year before their 1972 Eldredge and Gould paper, [[Niles Eldredge]] published a paper in the journal ''[[Evolution (journal)|Evolution]]'' which suggested that gradual evolution was seldom seen in the fossil record and argued that Ernst Mayr's standard mechanism of [[allopatric speciation]] might suggest a possible resolution.<ref name=eldredge1971 />

The Eldredge and Gould paper was presented at the [[Geological Society of America|Annual Meeting of the Geological Society of America]] in 1971.<ref name=pe1972/> The symposium focused its attention on how modern [[microevolution]]ary studies could revitalize various aspects of paleontology and macroevolution. Tom Schopf, who organized that year's meeting, assigned Gould the topic of speciation. Gould recalls that "Eldredge's 1971 publication [on [[Paleozoic]] [[trilobite]]s] had presented the only new and interesting ideas on the paleontological implications of the subject—so I asked Schopf if we could present the paper jointly."<ref name="StructureofEvolutionaryTheory">{{cite book |last=Gould |first=S. J. |author-link=Stephen Jay Gould |date=2002 |title=The Structure of Evolutionary Theory |publisher=The Belknap Press of Harvard University Press |location=Cambridge, Massachusetts |isbn=978-0-674-00613-3 |page=[https://archive.org/details/structureofevolu00goul/page/775 775] |url-access=registration |url=https://archive.org/details/structureofevolu00goul/page/775 }}</ref> According to Gould "the ideas came mostly from Niles, with yours truly acting as a sounding board and eventual scribe. I coined the term ''punctuated equilibrium'' and wrote most of our 1972 paper, but Niles is the proper first author in our pairing of Eldredge and Gould."<ref name=Opus200>[[Stephen Jay Gould|S. J. Gould]] (1991). [http://www.stephenjaygould.org/library/gould_opus200.html "Opus 200"] ''Natural History'' 100 (August): 12-18.</ref> In his book ''Time Frames'' Eldredge recalls that after much discussion the pair "each wrote roughly half. Some of the parts that would seem obviously the work of one of us were actually first penned by the other—I remember for example, writing the section on Gould's snails. Other parts are harder to reconstruct. Gould edited the entire manuscript for better consistency. We sent it in, and Schopf reacted strongly against it—thus signaling the tenor of the reaction it has engendered, though for shifting reasons, down to the present day."<ref>[[Niles Eldredge|Eldredge, Niles]] (1985) ''Time Frames: The evolution of punctuated equilibria''. Princeton: [[Princeton University Press]], p. 120.</ref>

John Wilkins and Gareth Nelson have argued that French architect [[Pierre Trémaux]] proposed an "anticipation of the theory of punctuated equilibrium of Gould and Eldredge."<ref>{{cite journal |last1=Wilkins |first1=John S. |last2=Nelson |first2=G. J. |year=2008 |title=Trémaux on species: A theory of allopatric speciation (and punctuated equilibrium) before Wagner |url=http://philsci-archive.pitt.edu/3881/1/Tremaux-on-species.pdf |journal=History and Philosophy of the Life Sciences |volume=30 |issue=2|pages=179–206 |pmid=19203015 }}</ref>

==Evidence from the fossil record==
{{Main|Rate of evolution}}

The fossil record includes well documented examples of both phyletic gradualism and punctuational evolution.<ref name="BentonHarper" /> As such, much debate persists over the prominence of stasis in the fossil record.<ref name="Futuyma86" /><ref>Erwin, D. H. and R. L. Anstey (1995) ''New approaches to speciation in the fossil record''. New York : Columbia University Press.</ref> Before punctuated equilibrium, most evolution biologists considered stasis to be rare or unimportant.<ref name="Mayr1992" /><ref>[[Stephen Jay Gould|S. J. Gould]] 2002. ''[[The Structure of Evolutionary Theory]]''. Cambridge MA: Harvard University Press, p. [https://books.google.com/books?id=nhIl7e61WOUC&pg=PA1154 875].</ref><ref>{{cite journal |last1=Wake |first1=David B. |last2=Roth |first2=G. |last3=Wake |first3=M. H. |date=1983 |title=On the problem of stasis in organismal evolution |journal=Journal of Theoretical Biology |doi=10.1016/0022-5193(83)90335-1 |volume=101 |issue=2 |page=212|bibcode=1983JThBi.101..211W }}</ref> The paleontologist [[George Gaylord Simpson]], for example, believed that phyletic gradual evolution (called ''horotely'' in his terminology) comprised 90% of evolution.<ref>Simpson, G. G. (1944). ''Tempo and Mode in Evolution''. Columbia University Press. New York, p. 203.</ref> More modern studies,<ref name="Campbell">Campbell, N.A. (1990) ''Biology'' p. 450–451, 487–490, 499–501. Redwood City CA: Benjamin Cummings Publishing Company.</ref><ref name=Gould&Eldredge1977>[[Stephen Jay Gould|S. J. Gould]], & [[Niles Eldredge|Eldredge, Niles]] (1977). [http://www.johnboccio.com/courses/SOC26/Bak-Sneppan/07_Gould.pdf "Punctuated equilibria: the tempo and mode of evolution reconsidered."] {{Webarchive|url=https://web.archive.org/web/20180508075839/http://www.johnboccio.com/courses/SOC26/Bak-Sneppan/07_Gould.pdf |date=2018-05-08 }} ''Paleobiology'' '''3''' (2): 115-151. (p.145)</ref><ref name="McCarthy">McCarthy, T. & Rubridge, B. (2005) ''The Story of Earth and Life''. Cape Town: Struik Publishers. {{ISBN|1-77007-148-2}}.</ref> including a [[meta-analysis]] examining 58 published studies on speciation patterns in the fossil record showed that 71% of species exhibited stasis,<ref>{{cite journal |last1=de Brito Neto |first1=S. G. |last2=Fernando Alves |first2=E. |last3=Cavalcante e Almeida Sá |first3=Mariana |date=2017 |title=Speciation in real time and historical-archaeological and its absence in geological time |url=https://www.academia.edu/39120976 |journal=Academia Journal of Scientific Research |doi=10.15413/ajsr.2017.0413 |doi-broken-date=1 November 2024|issn=2315-7712}}</ref> and 63% were associated with punctuated patterns of evolutionary change.<ref>Erwin, D. H. and Anstey, R. L (1995). [http://somosbacteriasyvirus.com/speciation.pdf "Speciation in the fossil record."] {{Webarchive|url=https://web.archive.org/web/20190323135919/http://www.somosbacteriasyvirus.com/speciation.pdf |date=2019-03-23 }} In Erwin, D. H. & Anstey, R. L. (eds). ''New Approaches to Speciation in the Fossil Record''. Columbia University Press, New York, pp. 11–39.</ref> According to [[Michael Benton]], "it seems clear then that stasis is common, and that had not been predicted from modern genetic studies."<ref name="BentonHarper">Benton, Michael and David Harper (2009) ''Introduction to Paleobiology and the Fossil Record'' New York: John Wiley & Sons, [https://books.google.com/books?id=ZQ1U9wmoensC&pg=PT227 pp. 123-124.]</ref> A paramount example of evolutionary stasis is the fern ''[[Osmunda claytoniana]]''. Based on paleontological evidence it has remained unchanged, even at the level of fossilized nuclei and chromosomes, for at least 180 million years.<ref name="pmid24653037">{{cite journal |last1=Bomfleur |first1=B. |last2=McLoughlin |first2=S. |last3=Vajda |first3=V. |date=March 2014 |title=Fossilized nuclei and chromosomes reveal 180 million years of genomic stasis in royal ferns |journal=Science |pmid=24653037 |doi=10.1126/science.1249884 |volume=343 |issue=6177 |pages=1376–1377 |url=http://nrm.diva-portal.org/smash/get/diva2:719316/FULLTEXT01 |bibcode=2014Sci...343.1376B |s2cid=38248823 }}</ref>

==Theoretical mechanisms==
===Punctuational change===

When Eldredge and Gould published their 1972 paper, [[allopatric speciation]] was considered the "standard" model of speciation.<ref name=pe1972 /> This model was popularized by Ernst Mayr in his 1954 paper "Change of genetic environment and evolution,"<ref name=Mayr1954 /> and his classic volume ''Animal Species and Evolution'' (1963).<ref name="Mayr1963">[[Ernst Mayr|Mayr, Ernst]] (1963). ''Animal Species and Evolution''. Cambridge, MA: [[Harvard University Press]].</ref>

Allopatric speciation suggests that species with large central populations are stabilized by their large volume and the process of [[gene flow]]. New and even [[Mutation#Beneficial mutations|beneficial mutations]] are diluted by the population's large size and are unable to reach fixation, due to such factors as constantly changing environments.<ref name="Mayr1963" /> If this is the case, then the transformation of whole lineages should be rare, as the fossil record indicates. Smaller populations on the other hand, which are isolated from the parental stock, are decoupled from the [[wikt:Homogeneous|homogenizing]] effects of gene flow. In addition, pressure from [[natural selection]] is especially intense, as peripheral isolated populations exist at the outer edges of [[ecological tolerance]]. If most evolution happens in these rare instances of allopatric speciation then evidence of gradual evolution in the fossil record should be rare. This [[hypothesis]] was alluded to by Mayr in the closing paragraph of his 1954 paper:

{{Blockquote|Rapidly evolving peripherally isolated populations may be the place of origin of many evolutionary novelties. Their isolation and comparatively small size may explain phenomena of rapid evolution and lack of documentation in the fossil record, hitherto puzzling to the palaeontologist.<ref name=Mayr1954 />}}

Although punctuated equilibrium generally applies to sexually reproducing organisms,<ref>[[Niles Eldredge|Eldredge, Niles]] and [[Stephen Jay Gould|S. J. Gould]] (1997). [http://www.stephenjaygould.org/library/science_on-punctuated-equilibria.html "On punctuated equilibria (letter)."] ''Science'' 276 (5311): 337-341.</ref> some biologists have applied the model to non-sexual species like [[virus]]es,<ref>Nichol, S.T, Joan Rowe, and Walter M. Fitch (1993). [http://www.pnas.org/content/90/22/10424.full.pdf "Punctuated equilibrium and positive Darwinian evolution in vesicular stomatitis virus."] ''Proceedings of the National Academy of Sciences'' 90 (Nov.): 10424-28.</ref><ref>Elena S.F., V.S. Cooper, and R. Lenski (1996). [https://web.archive.org/web/20030514101700/http://myxo.css.msu.edu/lenski/pdf/1996,%20Science,%20Elena%20et%20al.pdf "Punctuated Evolution Caused by Selection of Rare Beneficial Mutations."] ''Science'' 272 (June 21): 1802-1804.</ref> which cannot be stabilized by conventional gene flow. As time went on biologists like Gould moved away from wedding punctuated equilibrium to allopatric speciation, particularly as evidence accumulated in support of other modes of speciation.<ref name="GouldNewScientist"/> Gould, for example, was particularly attracted to [[Douglas J. Futuyma|Douglas Futuyma's]] work on the importance of reproductive isolating mechanisms.<ref>{{cite journal |last=Futuyma |first=Douglas |date=1987 |title=On the role of species in anagenesis |journal=[[The American Naturalist|American Naturalist]] |doi=10.1086/284724 |volume=130 |issue=3 |pages=465–473|bibcode=1987ANat..130..465F |s2cid=83546424 }}</ref>

===Stasis===
Many hypotheses have been proposed to explain the [[wikt:putative|putative]] causes of stasis. Gould was initially attracted to [[I. Michael Lerner]]'s theories of developmental and genetic homeostasis. However this hypothesis was rejected over time,<ref>[[Stephen Jay Gould|S. J. Gould]] 2002. ''[[The Structure of Evolutionary Theory]]''. Cambridge, Massachusetts: Harvard University Press, p. [https://books.google.com/books?id=nhIl7e61WOUC&pg=PA39 39].</ref> as evidence accumulated against it.<ref name=Futuyma86>Futuyma, Douglas (2005). ''Evolution''. Sunderland, MA: Sinauer Associates, p. 86.</ref> Other plausible mechanisms which have been suggested include: habitat tracking,<ref>{{cite book |last1=Eldredge |first1=Niles |author1-link=Niles Eldredge |last2=Gould |first2=S. J. |title=Evolutionary Biology |chapter=Morphological Transformation, the Fossil Record, and the Mechanisms of Evolution: A Debate |author2-link=Stephen Jay Gould |date=1974 |volume=7 |pages=305–306 |doi=10.1007/978-1-4615-6944-2_8 |isbn=978-1-4615-6946-6 }}</ref><ref>Niles Eldredge (1989). ''Time Frames''. Princeton University Press, pp. 139-141.</ref> [[stabilizing selection]],<ref name="Lieberman">{{cite journal |last1=Lieberman |first1=B. S. |last2=Dudgeon |first2=S. |date=1996 |title=An evaluation of stabilizing selection as a mechanism for stasis |journal=Palaeogeogr. Palaeoclimatol. Palaeoecol. |doi=10.1016/S0031-0182(96)00097-1 |volume=127 |issue=1–4 |pages=229–238|bibcode=1996PPP...127..229L |doi-access=free }}</ref> the Stenseth-Maynard Smith stability hypothesis,<ref>{{cite journal |last1=Stenseth |first1=N. C. |last2=Maynard Smith |first2=John |author-link=John Maynard Smith |date=1984 |title=Coevolution in ecosystems: Red Queen evolution or stasis? |journal=Evolution |doi=10.2307/2408397 |volume=38 |issue=4 |pages=870–880|jstor=2408397 |pmid=28555824 }}</ref> constraints imposed by the nature of subdivided populations,<ref name="Lieberman" /> normalizing clade selection,<ref>[[George C. Williams (biologist)|Williams, G. C.]] (1992). ''Natural Selection: Domains, Levels and Challenges''. New York: Oxford University Press, p. 132.</ref> and [[koinophilia]].<ref name= "Koeslag, 1990">{{cite journal |last1=Koeslag |first1=J. H. |year=1990 |title=Koinophilia groups sexual creatures into species, promotes stasis, and stabilizes social behaviour |journal=Journal of Theoretical Biology |volume=144 |issue=1 |pages=15–35 |doi=10.1016/s0022-5193(05)80297-8 |pmid=2200930 |bibcode=1990JThBi.144...15K }}</ref><ref name= "Koeslag, 1995">Koeslag, J.H. (1995). On the engine of speciation. [http://www.sciencedirect.com/science?_ob=MImg&_imagekey=B6WMD-45S96TH-5-1&_cdi=6932&_user=613892&_orig=search&_coverDate=12%2F21%2F1995&_sk=998229995&view=c&wchp=dGLbVzb-zSkzS&md5=5ca90c43829c1ac4503e69973e9de576&ie=/sdarticle.pdf ''J. theor. Biol.'' '''177''', 401-409]</ref>

Evidence for stasis has also been corroborated from the genetics of [[sibling species]], species which are morphologically indistinguishable, but whose proteins have diverged sufficiently to suggest they have been separated for millions of years.<ref>{{cite book |last=Maynard Smith |first=John |author-link=John Maynard Smith |year=1989 |title=Did Darwin Get it Right? |location=New York |publisher=Chapman and Hall |page=126}}</ref> Fossil evidence of reproductively isolated extant species of sympatric Olive Shells (''[[Amalda]]'' sp.) also confirm morphological stasis in multiple lineages over three million years.<ref>{{Cite journal |last1=Gemmell |first1=Michael R. |last2=Trewick |first2=Steven A. |last3=Hills |first3=Simon F. K. |last4=Morgan-Richards |first4=Mary |date=2019 |title=Phylogenetic topology and timing of New Zealand olive shells are consistent with punctuated equilibrium |journal=Journal of Zoological Systematics and Evolutionary Research |volume=58 |issue=1 |pages=209–220 |doi=10.1111/jzs.12342 |s2cid=213493738 |doi-access=free }}</ref><ref>{{Cite journal |last=Michaux |first=B. |date=1989 |title=Morphological variation of species through time |journal=Biological Journal of the Linnean Society |volume=38 |issue=3 |pages=239–255 |doi=10.1111/j.1095-8312.1989.tb01577.x}}</ref>

According to Gould, "stasis may emerge as the theory's most important contribution to evolutionary science."<ref>[[Stephen Jay Gould|S. J. Gould]] 2002. ''[[The Structure of Evolutionary Theory]]''. Cambridge MA: Harvard University Press, p. [https://books.google.com/books?id=nhIl7e61WOUC&pg=PA1155 872.]</ref> Philosopher [[Kim Sterelny]] in clarifying the meaning of stasis adds, "In claiming that species typically undergo no further evolutionary change once speciation is complete, they are not claiming that there is no change at all between one generation and the next. Lineages do change. But the change between generations does not accumulate. Instead, over time, the species wobbles about its [[Phenotype|phenotypic]] mean. [[Jonathan Weiner]]'s ''[[The Beak of the Finch]]'' describes this very process."<ref>Sterelny, Kim (2007). ''[[Dawkins vs. Gould|Dawkins vs. Gould: Survival of the Fittest]]''. Cambridge, U.K.: Icon Books, p. 96.</ref>

===Hierarchical evolution===
Punctuated equilibrium has also been cited as contributing to the hypothesis that species are [[Unit of selection|Darwinian individuals]], and not just [[class (biology)|classes]], thereby providing a stronger framework for a [[Unit of selection#Species selection and selection at higher taxonomic levels|hierarchical theory]] of evolution.<ref name="CoordinatedStasis">{{cite journal |last1=Brett |first1=Carlton E. |last2=Ivany |first2=Linda C. |last3=Schopf |first3=Kenneth M. |date=1996 |title=Coordinated stasis: An overview |journal=Palaeogeography, Palaeoclimatology, Palaeoecology |doi=10.1016/S0031-0182(96)00085-5 |volume=127 |issue=1–4 |pages=1–20|bibcode=1996PPP...127....1B |doi-access=free }}</ref>

==Common misconceptions==
Much confusion has arisen over what proponents of punctuated equilibrium actually argued, what mechanisms they advocated, how fast the punctuations were, what taxonomic scale their theory applied to, how revolutionary their claims were intended to be, and how punctuated equilibrium related to other ideas like [[Saltation (biology)|saltationism]], [[quantum evolution]], and [[mass extinction]].<ref name="gould_pe-fact-theory">[[Stephen Jay Gould|S. J. Gould]] (1992) [http://systematicbiology.co.nf/Gould_1989_PunctuatedEquilibriumFactTheory.pdf "Punctuated equilibrium in fact and theory."] {{Webarchive|url=https://web.archive.org/web/20180126071002/http://systematicbiology.co.nf/Gould_1989_PunctuatedEquilibriumFactTheory.pdf |date=2018-01-26 }} In Albert Somit and Steven Peterson ''The Dynamics of Evolution''. New York: Cornell University Press. pp.&nbsp;54–84.</ref>

===Saltationism===
[[File:Punctuated Equilibrium.svg|thumb|upright=1.5|Alternative explanations for the punctuated pattern of evolution observed in the fossil record. Both [[macromutation]] and seemingly "rapid" episodes of gradual evolution could give the appearance of instantaneous change, since 10,000&nbsp;years seldom registers in the geological record.]]

The punctuational nature of punctuated equilibrium has engendered perhaps the most confusion over Eldredge and Gould's theory. Gould's sympathetic treatment of [[Richard Goldschmidt]],<ref>{{cite magazine |author-link=Stephen Jay Gould |first=S.J. |last=Gould |date=June–July 1976 |url=http://www.stephenjaygould.org/library/gould_hopeful-monsters.html |title=The return of hopeful monsters |magazine=[[Natural History (magazine)|Natural History]] |volume=86 |pages=22–30}}</ref> the controversial [[geneticist]] who advocated the idea of "[[hopeful monster]]s," led some biologists to conclude that Gould's punctuations were occurring in single-generation jumps.<ref>{{cite book |author=Mayr, Ernst |year=1982 |title=Growth of Biological Thought |publisher=Harvard University Press |page=[http://www.stephenjaygould.org/library/mayr_macroevolutionary-diversity.pdf 617] |url=http://www.stephenjaygould.org/library/mayr_macroevolutionary-diversity.pdf |archive-url=https://web.archive.org/web/20160623211259/http://www.stephenjaygould.org/library/mayr_macroevolutionary-diversity.pdf |archive-date=2016-06-23}}</ref><ref>{{cite journal |author-link=John Maynard Smith |last=Maynard Smith |first=J. |year=1983 |title=The genetics of stasis and punctuations |journal=Annual Review of Genetics |volume=17 |page=12 |url=http://teosinte.wisc.edu/gen677_pdfs/Maynard_Smith.pdf |archive-url=https://web.archive.org/web/20101206232444/http://teosinte.wisc.edu/gen677_pdfs/Maynard_Smith.pdf |archive-date=2010-12-06}}</ref><ref>{{cite book |author=Ruse, Michael |year=1985 |title=Sociobiology, Sense or Nonsense? |place=New York, NY |publisher=Springer |page=[https://books.google.com/books?id=LdSgNlQgdlkC&pg=PA216 216]}}</ref><ref>''For reply see'':
* {{cite book |author-link=Stephen Jay Gould |first=S.J. |last=Gould |title=Structure |year=2002 |pages=765, 778, 1001, 1005, 1009}}
* {{cite book |first=R. |last=Dawkins |author-link=Richard Dawkins |title=The Blind Watchmaker |year=1996 |pages=[https://books.google.com/books?id=sPpaZnZMDG0C&pg=PA231 230-236] |publisher=W. W. Norton & Company |isbn=9780393315707 |url=https://books.google.com/books?id=sPpaZnZMDG0C&pg=PA231 |via=Google Books}}
* {{cite book |first=D. |last=Dennett |title=Darwin's Dangerous Idea |year=1996 |pages=[https://books.google.com/books?id=FvRqtnpVotwC&pg=PA288 288–289] |publisher=Simon and Schuster |isbn=9780684824710 |url=https://books.google.com/books?id=FvRqtnpVotwC&pg=PA288 |via=Google Books}}</ref> This interpretation has frequently been used by [[creationism|creationists]] to characterize the weakness of the [[Paleontology|paleontological]] record, and to portray contemporary evolutionary biology as advancing neo-saltationism.<ref>{{cite book |author-link=Hank Hanegraaff |author=Hanegraaff, H. |year=1998 |title=The Face that Demonstrates the Farce of Evolution |place=Nashville, TN |publisher=Word Publishing |pages=[https://books.google.com/books?id=Ta-qOuhtGkAC&pg=PA40 40-45] |isbn=9781418515096 |url=https://books.google.com/books?id=Ta-qOuhtGkAC&pg=PA40 |via=Google Books}}</ref>

In an often quoted remark, Gould stated,
: "Since we proposed punctuated equilibria to explain trends, it is infuriating to be quoted again and again by creationists – whether through design or stupidity, I do not know – as admitting that the fossil record includes no [[Transitional fossil|transitional forms]]. Transitional forms are generally lacking at the species level, but they are [[List of transitional fossils|abundant between larger groups]]."<ref>{{cite magazine |author-link=Stephen Jay Gould |first=S.J. |last=Gould |date=May 1981 |title=Evolution as fact and theory |magazine=[[Discover (magazine)|Discover]] |volume=2 |pages=34–37 |url=http://www.stephenjaygould.org/library/gould_fact-and-theory.html}}</ref>

Although there exist some debate over how long the punctuations last, supporters of punctuated equilibrium generally place the figure between 50,000 and 100,000&nbsp;years.<ref>{{cite journal |last1=Ayala |first1=F. |date=2005 |title=The structure of evolutionary theory |journal=Theology and Science |volume=3 |issue=1 |page=104 |doi=10.1080/14746700500039800 |s2cid=4293004 |url=http://www.stephenjaygould.org/reviews/ayala_structure.pdf |url-status=dead |access-date=2007-04-22 |archive-url=https://web.archive.org/web/20180923235159/http://www.stephenjaygould.org/reviews/ayala_structure.pdf |archive-date=2018-09-23}}</ref>

===Quantum evolution===

[[Quantum evolution]] was a controversial hypothesis advanced by [[Columbia University]] paleontologist [[George Gaylord Simpson]], regarded by Gould as "the greatest and most biologically astute paleontologist of the twentieth century."<ref>[[Stephen Jay Gould|S. J. Gould]] (2007) ''Punctuated equilibrium''. Cambridge MA: Harvard University Press, p. 26.</ref> Simpson's conjecture was that according to the geological record, on very rare occasions evolution would proceed very rapidly to form entirely new [[Family (biology)|families]], [[Order (biology)|orders]], and [[Class (biology)|classes]] of organisms.<ref name=Simpson1944>Simpson, G. G. (1944). ''[[Tempo and Mode in Evolution]]''. New York: Columbia Univ. Press, p. 206</ref><ref>Fitch, W. J. and F. J. Ayala (1995) [https://download.nap.edu/cart/download.cgi?record_id=4910 ''Tempo and mode in evolution: genetics and paleontology 50 years after Simpson''.] Washington, D.C.: National Academy Press.</ref> This hypothesis differs from punctuated equilibrium in several respects. First, punctuated equilibrium was more modest in scope, in that it was addressing evolution specifically at the [[species]] level.<ref name=Gould&Eldredge1977/> Simpson's idea was principally concerned with evolution at higher taxonomic groups.<ref name=Simpson1944/> Second, Eldredge and Gould relied upon a different mechanism. Where Simpson relied upon a [[Synergy|synergistic]] interaction between [[genetic drift]] and a shift in the [[fitness landscape|adaptive fitness landscape]],<ref>Simpson, G. G. (1953). [http://www.stephenjaygould.org/library/simpson_evolutionary-rates.html ''The Major Features of Evolution''] {{Webarchive|url=https://web.archive.org/web/20190421001618/http://www.stephenjaygould.org/library/simpson_evolutionary-rates.html |date=2019-04-21 }}. New York: Columbia Univ. Press, p. 390.</ref> Eldredge and Gould relied upon ordinary speciation, particularly Ernst Mayr's concept of allopatric speciation. Lastly, and perhaps most significantly, quantum evolution took no position on the issue of stasis. Although Simpson acknowledged the existence of stasis in what he called the bradytelic mode, he considered it (along with rapid evolution) to be unimportant in the larger scope of evolution.<ref name="Simpson1944p206">Simpson, G. G. (1944). ''[[Tempo and Mode in Evolution]]''. New York: Columbia Univ. Press, [https://books.google.com/books?id=f5qucNebo-kC&pg=PA205 pp. 205-206.]</ref> In his ''Major Features of Evolution'' Simpson stated, "Evolutionary change is so nearly the universal rule that a state of motion is, figuratively, normal in evolving populations. The state of rest, as in bradytely, is the exception and it seems that some restraint or force must be required to maintain it." Despite such differences between the two models, earlier critiques—from such eminent commentators as [[Sewall Wright]] as well as Simpson himself—have argued that punctuated equilibrium is little more than quantum evolution relabeled.<ref>{{cite journal |last=Wright |first=Sewall |date=1982 |title=Character change, speciation, and the higher taxa |journal=Evolution |doi=10.2307/2408092 |volume=56 |issue=3 |pages=427–443 |url=http://stewardshipofcreationenabler.giving.officelive.com/Documents/21_Wright1982.pdf |url-status=dead |archive-url=https://web.archive.org/web/20110828022050/http://stewardshipofcreationenabler.giving.officelive.com/Documents/21_Wright1982.pdf |archive-date=2011-08-28 |jstor=2408092 |pmid=28568042 }}</ref><ref>Simpson, G. G. (1984) ''Tempo and Mode in Evolution''. Reprint. Columbia University Press, p. xxv.</ref>

===Multiple meanings of gradualism===
Punctuated equilibrium is often portrayed to oppose the concept of [[Gradualism#Geology and biology|gradualism]], when it is actually a form of gradualism.<ref name="Dawkins, Richard 1996 p. 224-252">[[Richard Dawkins|Dawkins, Richard]] (1996). ''[[The Blind Watchmaker]]''. New York: W. W. Norton & Co., Chapter 9. (p. 224-252)</ref> This is because even though evolutionary change appears instantaneous between geological sedimentary layers, change is still occurring incrementally, with no great change from one generation to the next. To this end, Gould later commented that "Most of our [[paleontology|paleontological colleagues]] missed this insight because they had not studied evolutionary theory and either did not know about [[allopatric speciation]] or had not considered its translation to geological time. Our [[Population genetics|evolutionary colleagues]] also failed to grasp the implication(s), primarily because they did not think at geological scales".<ref name=Opus200/>

[[Richard Dawkins]] dedicates a chapter in ''[[The Blind Watchmaker]]'' to correcting, in his view, the wide confusion regarding ''rates of change''. His first point is to argue that [[phyletic gradualism]]—understood in the sense that evolution proceeds at a single uniform speed, called "constant speedism" by Dawkins—is a "caricature of Darwinism"<ref>Dawkins, Richard (1996). ''[[The Blind Watchmaker]]''. New York: W. W. Norton & Co., p. 227.</ref> and "does not really exist".<ref>[[Richard Dawkins|Dawkins, Richard]]  (1996). The Blind Watchmaker, p. 228. Dawkins' exception to this rule is the non-adaptive evolution observed in molecular evolution.</ref> His second argument, which follows from the first, is that once the caricature of "constant speedism" is dismissed, we are left with one logical alternative, which Dawkins terms "variable speedism". Variable speedism may also be distinguished one of two ways: "''discrete variable'' speedism" and "''continuously variable'' speedism". Eldredge and Gould, proposing that evolution jumps between stability and relative rapidity, are described as "discrete variable speedists", and "in this respect they are genuinely radical."<ref>[[Richard Dawkins|Dawkins, Richard]] (1996) ''[[The Blind Watchmaker]]'', p. 245.</ref> They assert that evolution generally proceeds in bursts, or not at all. "Continuously variable speedists", on the other hand, advance that "evolutionary rates fluctuate continuously from very fast to very slow and stop, with all intermediates. They see no particular reason to emphasize certain speeds more than others. In particular, stasis, to them, is just an extreme case of ultra-slow evolution. To a punctuationist, there is something very special about stasis."<ref>Dawkins, Richard (1996). The Blind Watchmaker, p. 245-246.</ref>

==Criticism==
{{See also|Species#The species problem|l1=Species problem|Species complex|Push of the past}}

[[Richard Dawkins]] regards the apparent gaps represented in the fossil record as documenting migratory events rather than evolutionary events. According to Dawkins, evolution certainly occurred but "probably gradually" elsewhere.<ref>Dawkins, Richard (1996). ''[[The Blind Watchmaker]]'', p. 240.</ref> However, the punctuational equilibrium model may still be inferred from both the observation of stasis and examples of rapid and episodic speciation events documented in the fossil record.<ref>{{cite journal |last1=Cheetham |first1=Alan |author-link1=Alan Cheetham |last2=Jackson |first2=Jeremy |last3=Hayek |first3=Lee-Ann |author3-link= Lee-Ann C. Hayek |date=1994 |title=Quantitative genetics of bryozoan phenotypic evolution |journal=Evolution |doi=10.2307/2410098 |volume=48 |issue=2 |pages=360–375|jstor=2410098 }}</ref>

Dawkins also emphasizes that punctuated equilibrium has been "oversold by some journalists",<ref>Dawkins, Richard (1996). ''[[The Blind Watchmaker]]'', p. 250-251.</ref> but partly due to Eldredge and Gould's "later writings".<ref>[[Richard Dawkins|Dawkins, Richard]]  (1996). ''[[The Blind Watchmaker]]'', p. 241.</ref> Dawkins contends that the hypothesis "does not deserve a particularly large measure of publicity".<ref>Dawkins, Richard (1996). ''[[The Blind Watchmaker]]'', p. 250.</ref> It is a "minor gloss," an "interesting but minor wrinkle on the surface of neo-Darwinian theory," and "lies firmly within the neo-Darwinian synthesis".<ref>Dawkins, Richard (1996). ''[[The Blind Watchmaker]]'', p. 251.</ref>

In his book ''[[Darwin's Dangerous Idea]]'', philosopher [[Daniel Dennett]] is especially critical of Gould's presentation of punctuated equilibrium. Dennett argues that Gould alternated between revolutionary and conservative claims, and that each time Gould made a revolutionary statement—or appeared to do so—he was criticized, and thus retreated to a traditional neo-Darwinian position.<ref>Dennett, Daniel (1995). ''[[Darwin's Dangerous Idea]]''. New York: Simon & Schuster, pp. 282-299.</ref> Gould responded to Dennett's claims in ''[[The New York Review of Books]]'',<ref>[[Stephen Jay Gould|Gould, S. J.]] (1997). [http://www.nybooks.com/articles/1151 "Darwinian Fundamentalism"] ''The New York Review of Books'', June 12, pp. 34-37; and [https://web.archive.org/web/20161110121332/http://www.stephenjaygould.org/reviews/gould_pluralism.html "Evolution: The Pleasures of Pluralism"] ''The New York Review of Books'', June 26, pp. 47-52.</ref> and in his technical volume ''[[The Structure of Evolutionary Theory]]''.<ref>{{Cite web |date=2019-10-19 |title=Stephen Jay Gould, "Punctuated Equilibrium's Threefold History," 2002 |url=http://www.stephenjaygould.org/library/gould_structure.html |access-date=2022-02-16 |website= |archive-url=https://web.archive.org/web/20191019050215/http://www.stephenjaygould.org/library/gould_structure.html |archive-date=19 October 2019 |url-status=dead}}</ref>

English professor Heidi Scott argues that Gould's talent for writing vivid prose, his use of metaphor, and his success in building a popular audience of nonspecialist readers altered the "climate of specialized scientific discourse" favorably in his promotion of punctuated equilibrium.<ref name=scott>{{cite journal |last=Scott |first=Heidi |date=2007 |title=Stephen Jay Gould and the Rhetoric of Evolutionary Theory |journal=Rhetoric Review |doi=10.1080/07350190709336705 |volume=26 |issue=2 |pages=120–141|s2cid=144947503 }}</ref> While Gould is celebrated for the color and energy of his prose, as well as his interdisciplinary knowledge, critics such as Scott, Richard Dawkins, and Daniel Dennett have concerns that the theory has gained undeserved credence among non-scientists because of Gould's rhetorical skills.<ref name=scott /> Philosopher John Lyne and biologist Henry Howe believed punctuated equilibrium's success has much more to do with the nature of the geological record than the nature of Gould's rhetoric. They state, a "re-analysis of existing fossil data has shown, to the increasing satisfaction of the paleontological community, that Eldredge and Gould were correct in identifying periods of evolutionary stasis which are interrupted by much shorter periods of evolutionary change."<ref>{{cite journal |last1=Lyne |first1=John |last2=Howe |first2=Henry F. |title="Punctuated equilibria": Rhetorical dynamics of a scientific controversy |journal=Quarterly Journal of Speech |date=1986 |volume=72 |issue=2 |pages=132–147 [135] |doi=10.1080/00335638609383764}}</ref>

Evolutionary biologist [[Robert Trivers]] accused Gould of being "something of an intellectual fraud" for using claims that were "well known from the time of Darwin" (that evolution displayed "periods of long stasis interspersed with periods of rapid change") to support distinct but more "grandiose" claims regarding [[Unit of selection#Species and higher levels|species selection]], despite the "rate of species turnover [having] nothing to do with the traits within species—only with the relative frequency of species showing these traits".<ref>{{Cite web |last=Trivers |first=Robert |date=October 4, 2012 |title=Fraud in the Imputation of Fraud |url=https://www.psychologytoday.com/us/blog/the-folly-fools/201210/fraud-in-the-imputation-fraud |access-date=2023-02-26 |website=Psychology Today |language=en-US}}</ref>

Some critics jokingly referred to the theory of punctuated equilibrium as "evolution by jerks",<ref>{{cite magazine |author=Turner, John |year=1984 |url=https://repository.library.georgetown.edu/handle/10822/538970 |title=Why we need evolution by jerks |magazine=New Scientist |volume=101 |issue=Feb. 9 |pages=34–35 }}</ref> which reportedly prompted punctuationists to describe [[phyletic gradualism]] as "evolution by creeps."<ref>[[Stephen Jay Gould|Gould, S. J.]] and Steven Rose, ed. (2007). ''The Richness of Life: The Essential Stephen Jay Gould''. New York: W. W. Norton & Co., [https://archive.org/details/richnessoflifees0000goul/page/6 p. 6.]</ref>

==Darwin's theory==
The sudden appearance of most species in the geologic record and the lack of evidence of substantial gradual change in most [[species]]—from their initial appearance until their extinction—has [[Speciation#Darwin's dilemma: Why do species exist?|long been noted]], including by [[Charles Darwin]], who appealed to the imperfection of the record as the favored explanation.<ref>Darwin, Charles (1859). ''[[On the Origin of Species]]''. London: John Murray, p. 301.</ref><ref>Darwin, Charles (1871). ''[[The Origin of Species]]''. London: John Murray, p. 119-120.</ref> When presenting his ideas against the prevailing influences of [[catastrophism]] and [[progressive creationism]], which envisaged species being supernaturally created at intervals, Darwin needed to forcefully stress the gradual nature of [[evolution]] in accordance with the [[gradualism]] promoted by his friend [[Charles Lyell]]. He privately expressed concern, noting in the margin of his 1844 ''Essay'', "Better begin with this: If species really, after catastrophes, created in showers world over, my theory false."<ref name=VQR>Eldredge, Niles (2006) [http://www.vqronline.org/articles/2006/spring/eldredge-confessions-darwinist/ "Confessions of a Darwinist."] {{Webarchive|url=https://web.archive.org/web/20131224110620/http://www.vqronline.org/articles/2006/spring/eldredge-confessions-darwinist/ |date=2013-12-24 }} ''[[The Virginia Quarterly Review]]'' 82 (Spring): 32-53.</ref>

It is often incorrectly assumed that he insisted that the rate of change must be constant, or nearly so, but even the first edition of ''[[On the Origin of Species]]'' states that "Species of different genera and classes have not changed at the same rate, or in the same degree. In the oldest tertiary beds a few living shells may still be found in the midst of a multitude of extinct forms... The Silurian ''Lingula'' differs but little from the living species of this genus". ''[[Lingula (genus)|Lingula]]'' is among the few brachiopods surviving today but also known from fossils over 500 million years old.<ref>Darwin, Charles (1859). ''On the Origin of Species''. London: John Murray. [http://darwin-online.org.uk/content/frameset?viewtype=text&itemID=F373&pageseq=331 p. 313].</ref> In the fourth edition (1866) of ''On the Origin of Species'' Darwin wrote that "the periods during which species have undergone modification, though long as measured in years, have probably been short in comparison with the periods during which they retain the same form."<ref>Darwin, Charles (1869). ''The Origin of Species''. London: John Murray. 5th edition, [http://darwin-online.org.uk/content/frameset?viewtype=text&itemID=F387&pageseq=583 p. 551].</ref> Thus punctuationism in general is consistent with Darwin's conception of evolution.<ref name=VQR/>

According to early versions of punctuated equilibrium, "peripheral isolates" are considered to be of critical importance for speciation. However, Darwin wrote, "''I can by no means agree'' ... that immigration and isolation are necessary elements. ... Although isolation is of great importance in the production of new species, on the whole I am inclined to believe that largeness of area is still more important, especially for the production of species which shall prove capable of enduring for a long period, and of spreading widely."<ref>Darwin, Charles (1869). ''The Origin of Species''. London: John Murray. 5th edition, [http://darwin-online.org.uk/content/frameset?itemID=F387&viewtype=text&pageseq=1 pp. 120-121.]</ref>

The importance of isolation in forming species had played a significant part in Darwin's early thinking, as shown in his ''Essay'' of 1844. But by the time he wrote the ''Origin'' he had downplayed its importance.<ref name=VQR/> He explained the reasons for his revised view as follows:
<blockquote>Throughout a great and open area, not only will there be a greater chance of favourable variations, arising from the large number of individuals of the same species there supported, but the conditions of life are much more complex from the large number of already existing species; and if some of these species become modified and improved, others will have to be improved in a corresponding degree, or they will be exterminated. Each new form, also, as soon as it has been improved, will be able to spread over the open and continuous area, and will thus come into competition with many other forms&nbsp;... the new forms produced on large areas, which have already been victorious over many competitors, will be those that will spread most widely, and will give rise to the greatest number of new varieties and species. They will thus play a more important role in the changing history of the organic world.<ref>Darwin, Charles (1869). ''The Origin of Species''. London: John Murray. 5th edition, [http://darwin-online.org.uk/content/frameset?itemID=F387&viewtype=text&pageseq=1 pp. 121-122.]</ref></blockquote>

Thus punctuated equilibrium is incongruous with some of Darwin's ideas regarding the specific mechanisms of evolution, but generally accords with Darwin's theory of evolution by natural selection.<ref name=VQR/><ref name="ComesOfAge">{{Citation |last1=Gould |first1=Stephen Jay |author-link1=Stephen Jay Gould |last2=Eldredge |first2=Niles |author-link2=Niles Eldredge |date=1993 |title=Punctuated equilibrium comes of age |journal=Nature |doi=10.1038/366223a0 |pmid=8232582|volume=366 |issue=6452 |pages=223–227 |url=http://www.stephenjaygould.org/library/gould_comes-of-age.html|bibcode=1993Natur.366..223G |s2cid=4253816 }}</ref>

==Supplemental modes of rapid evolution==
{{See also|Rapid modes of evolution}}
Recent work in [[developmental biology]] has identified dynamical and physical mechanisms of [[morphogenesis|tissue morphogenesis]] that may underlie abrupt morphological transitions during evolution. Consequently, consideration of mechanisms of phylogenetic change that have been found in reality to be non-gradual is increasingly common in the field of [[evolutionary developmental biology]], particularly in studies of the origin of morphological novelty. A description of such mechanisms can be found in the multi-authored volume ''[[Origination of Organismal Form]]'' (MIT Press; 2003).

==Language change==
{{See also|Language change}}
In linguistics, [[R. M. W. Dixon]] has proposed a punctuated equilibrium model for language histories,<ref>Dixon, R.M.W. (1997). ''The rise and fall of languages'' Cambridge: Cambridge University Press.</ref> with reference particularly to the prehistory of the [[indigenous languages of Australia]] and his objections to the proposed [[Pama–Nyungan languages|Pama–Nyungan]] language family there. Although his model has raised considerable interest, it does not command majority support within linguistics.<ref>{{Cite book|title=Australian Languages|volume=249|date=2004-03-18|publisher=John Benjamins Publishing Company|isbn=9789027295118|editor-last=Bowern|editor-first=Claire|language=en|doi=10.1075/cilt.249|editor2-last=Koch|editor2-first=Harold|series=Current Issues in Linguistic Theory}}</ref>

Separately, recent work using [[computational phylogenetics|computational phylogenetic]] methods claims to show that punctuational bursts play an important factor when [[language change|languages split from one another]], accounting for anywhere from 10 to 33% of the total divergence in vocabulary.<ref>{{cite journal |last1=Atkinson |first1=Quentin D. |last2=Meade |first2=Andrew |last3=Venditti |first3=Chris |last4=Greenhill |first4=Simon J. |last5=Pagel |first5=Mark |date=2008 |title=Languages Evolve in Punctuational Bursts |journal=[[Science (journal)|Science]] |doi=10.1126/science.1149683 |pmid=18239118 |volume=319 |issue=5863 |page=588 |hdl=1885/33371 |s2cid=29740420 |hdl-access=free }}; Dan Dediu mail, Stephen C. Levinson, [http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0045198 Abstract Profiles of Structural Stability Point to Universal Tendencies, Family-Specific Factors, and Ancient Connections between Languages], ''PLoS ONE'',7(9), 2012, e451982012.</ref>

==Mythology==
Punctuational evolution has been argued to explain changes in folktales and mythology over time.<ref>Julien d'Huy, [https://www.academia.edu/3045718/PREPRINT_A_Cosmic_Hunt_in_the_Berber_sky_a_phylogenetic_reconstruction_of_Palaeolithic_mythology._Les_Cahiers_de_lAARS_15_2012_ A Cosmic Hunt in the Berber sky : a phylogenetic reconstruction of Palaeolithic mythology]. ''Les Cahiers de l'AARS'', 15, 2012; [http://nouvellemythologiecomparee.hautetfort.com/archive/2013/01/20/julien-d-huy-polyphemus-aa-th-1137.html Polyphemus (Aa. Th. 1137) A phylogenetic reconstruction of a prehistoric tale.] ''Nouvelle Mythologie Comparée / New Comparative Mythology'' 1, 2013; [https://www.academia.edu/4478823/Les_mythes_evolueraient_par_ponctuations._-_Mythologie_francaise_252_2013_8-12 Les mythes évolueraient par ponctuations] {{Webarchive|url=https://web.archive.org/web/20200528230437/https://www.academia.edu/4478823/2013._Les_mythes_%C3%A9volueraient_par_ponctuations._-_Mythologie_fran%C3%A7aise_252_8-12 |date=2020-05-28 }}. ''Mythologie française'', 252, 2013, 8-12.</ref>

==See also==
{{Columns-list|colwidth=30em|
*[[Speciation#Punctuated evolution|Speciation]]
*[[Adaptive radiation]]
*[[Catastrophe theory]]
*[[Convergent evolution]]
*[[Court Jester Hypothesis]]
*[[Critical juncture theory]]
*[[Evolutionary capacitance]]
*[[Gene orders]]
*[[Koinophilia]]
*[[Punctuated equilibrium in social theory]]
*[[Punctuated gradualism]]
}}

==References==
{{Reflist|30em}}

==External links==
{{Commons category}}

*[https://books.google.com/books?id=cgKUZXeRoOYC ''Punctuated Equilibrium''] - by Stephen Jay Gould
*[http://www.donaldprothero.com/files/47440356.pdf Punctuated Equilibrium at Twenty] - by Donald R. Prothero
*[http://www.talkorigins.org/faqs/punc-eq.html Punctuated Equilibria?] - by Wesley Elsberry, [[TalkOrigins Archive]]
*[http://www.scholarpedia.org/article/Punctuated_equilibria Scholarpedia: Punctuated equilibria] - by Bruce Lieberman and Niles Eldredge
*[http://theobald.brandeis.edu/pe.html All you need to know about Punctuated Equilibrium (almost)] - by Douglas Theobald
*[http://www.stephenjaygould.org/library/newsweek_sjgould.html Enigmas of Evolution] - by Jerry Adler and John Carey, ''Newsweek''

{{speciation}}
{{Evolution}}
{{Evolutionary psychology}}
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[[Category:Punctuated equilibrium|Punctuated equilibrium]]
[[Category:Biology theories]]
[[Category:Evolutionary biology]]
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[[Category:Rate of evolution]]
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[[Category:Stephen Jay Gould]]