Punctuated Equilibrium - Wikipedia

7/30/2019 Punctuated Equilibrium - Wikipedia

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9/12 Punctuated equilibrium - Wikipedia, the free encyclopedia

.wikipedia.org/wiki/Punctuated_equilibrium

Punctuated equilibrium, bottom, consists of

morphological stability and rare bursts of

evolutionary change

Punctuated equilibriumFrom Wikipedia, the free encyclopedia

Punctuated equilibrium (also called punctuated

equilibria) is a theory in evolutionary biology which

proposes that most species will exhibit little net

evolutionary change for most of their geological history,

remaining in an extended state called stasis. Whensignificant evolutionary change occurs, the theory

proposes that it is generally restricted to rare and

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.[1]

Punctuated equilibrium is commonly contrasted against

the theory of phyletic gradualism, which states that

evolution generally occurs uniformly and by the steadyand gradual transformation of whole lineages (called

anagenesis). In this view, evolution is seen as generally

smooth and continuous.

In 1972, paleontologists Niles Eldredge and Stephen Jay

Gould published a landmark paper developing this theory

and called itpunctuated equilibria.[2] Their paper built

upon Ernst Mayr's theory of geographic speciation,[3] I.

Michael Lerner's theories of developmental and genetic

homeostasis,[4] as well as their own empirical

research.[5][6] Eldredge and Gould proposed that the

degree of gradualism commonly attributed to Charles Darwin is virtually nonexistent in the fossil record, and

that stasis dominates the history of most fossil species.

Contents

1 A history of the theory

2 Theoretical mechanisms2.1 Punctuational change2.2 Stasis2.3 Hierarchical evolution

3 Common misconceptions3.1 Saltationism3.2 Quantum evolution3.3 The multiple meanings of gradualism

4 Criticism


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5 Relation to Darwin's theories6 Supplemental modes of rapid evolution7 Punctuated equilibrium in social theory8 Punctuated equilibrium in international relations9 In language change10 See also11 References12 Further reading

13 External links

A history of the theory

Punctuated equilibrium originated as a logical extension of Ernst Mayr's concept of genetic revolutions by

allopatric and especially peripatric speciation as applied to the fossil record. Although some of the basic

workings of the theory were proposed and identified by Rudolf Kaufmann and then by Mayr in 1954,[3]

historians of science generally recognize the 1972 paper by Niles Eldredge and Stephen Jay Gould as thefoundational document of the new paleobiological research program.[7][8][9] Punctuated equilibrium differs

from Mayr's hypothesis mainly in that Eldredge and Gould placed considerably greater emphasis on stasis,

whereas Mayr was generally concerned with explaining the morphological discontinuity (or "sudden

umps")[10] found in the fossil record.[7] 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."[7]

A year before their 1972 Eldredge and Gould paper, Niles Eldredge published a paper in the journalEvolutio

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.[5]

The Eldredge and Gould paper was presented at the Annual Meeting of the Geological Society of America in

1971.[2] The symposium focused its attention on the possibility that modern microevolutionary 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 Paleozo

trilobites] 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."[11] According to Gould "the ideas came mostly from

Niles, with yours truly acting as a sounding board and eventual scribe. I coined the termpunctuated

equilibrium and wrote most of our 1972 paper, but Niles is the proper first author in our pairing of Eldredge

and Gould."[12] Eldredge in his book Time Frames recalls that the pair "after much discussion, each wrote

roughly half. Some of the parts that would seem obviously the work of one of us were actually first penned b

the otherI remember for example, writing the section on Gould's snails. Other parts are harder to reconstruc

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."[13]

Nowadays Pierre Trmaux, author of the book Origine et transformations de lhomme et des autres tres


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(1865) is considered as the antedecent and predecessor of this theory (Wilkins and Nelson, 2008).[14]

Theoretical mechanisms

Punctuational change

When Eldredge and Gould published their 1972 paper, allopatric speciation was considered the "standard"

theory of speciation.[2] This theory was popularized by Ernst Mayr in his 1954 paper "Change of genetic

environment and evolution,"[3] and his classic volumeAnimal Species and Evolution (1963).[15]

Allopatric speciation suggests that species with large central populations are stabilized by their large volume

and the process gene flow. New and even beneficial mutations are diluted by the population's large size and

are unable to reach fixation, due to such factors as constantly changing environments.[15] 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 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 allopatricspeciation then evidence of gradual evolution in the fossil record should be rare. This stimulating hypothesis

was alluded to by Mayr in the closing paragraph of his 1954 paper (p. 179).

As time went on Gould moved away from wedding punctuated equilibrium to allopatric speciation,

particularly as evidence accumulated in support of other modes of speciation.[16] Gould was particularly

attracted to Douglas Futuyma's work on the importance of reproductive isolating mechanisms. [17]

Other biologists have also applied punctuated equilibrium to non-sexual species, including the evolution of

viruses.[18]

Stasis

Before Eldredge and Gould alerted their colleagues to the prominence of stasis in the fossil record, most

evolutionists considered stasis to be rare or unimportant.[7][19][20] George Gaylord Simpson for example

believed that phyletic gradual evolution (called horotely in his terminology) comprised "nine-tenths" (90%) o

evolution.[21] Many hypotheses have been proposed to explain the 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,[22] as evidence accumulated against it.[23] Other plausible mechanisms

which have been suggested include: habitat tracking,[24][25] stabilizing selection,[26] the Stenseth-Maynard

Smith stability hypothesis,[27] constraints imposed by the nature of subdivided populations,[26] and

normalizing clade selection.[28]

Evidence for the existence of 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.[29] According to Gould "stasis may emerge as the theory's most

important contribution to evolutionary science."[30]


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Philosopher Kim Sterelny 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 th

next. Lineages do change. But the change between generations does not accumulate. Instead, over time, the

species wobbles about its phenotypic mean. Jonathan Weiner's The Beak of the Finch describes this very

process."[31]

The fossil record includes well documented examples of phyletic gradualism and punctuational evolution. As

such, much debate persist over the prominence of stasis in the fossil record.[23]

Hierarchical evolution

Punctuated equilibrium has also been cited as contributing to the theory that species are Darwinian individual

and not just classes, thereby providing a stronger framework for a hierarchical theory of evolution.

Common misconceptions

Much confusion has arisen over what proponents of punctuated equilibrium actually argued, what mechanism

they advocated, how fast the punctuations were, what taxonomic scale their theory applied to, howrevolutionary their claims were intended to be, and how punctuated equilibrium related to other ideas like

quantum evolution, saltationism, and mass extinction.

Saltationism

The punctuational nature of punctuated equilibrium has engendered perhaps the most confusion over Eldredg

and Gould's theory. Gould's sympathetic treatment of Richard Goldschmidt,[32] the controversial geneticist

who advocated the idea of "hopeful monsters," only exacerbated the matter, which lead some biologists to

conclude that Gould's punctuations were occurring in single-generation jumps.[33][34][35][36] This

interpretation has frequently been exploited by creationists to mischaracterize the weakness of the

paleontological record, and to portray contemporary evolutionary biology as advancing neo-saltationism.[37]

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 creationistswhether through design or stupidity, I do not know

as admitting that the fossil record includes no transitional forms. Transitional forms are generally lacking at

the species level, but they are abundant between larger groups." [38] 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 years.[39]

Quantum evolution

Quantum evolution was a controversial hypothesis advanced by Columbia University paleontologist George

Gaylord Simpson, who was regarded by Stephen Jay Gould as "the greatest and most biologically astute

paleontologist of the twentieth century."[40] Simpson's conjecture was that according to the geological record

on very rare occasions evolution would proceed very rapidly to form entirely new families, orders, and classe

of organisms.[41] This hypothesis differs from punctuated equilibrium in many respects. First, punctuated

equilibrium was much more modest in scope, in that it was addressing evolution specifically at the species


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level.[1] Simpson's idea was principally concerned with evolution at higher taxonomic groups. [41] Second,

Eldredge and Gould relied upon an entirely different mechanism. Where Simpson relied upon a synergistic

interaction between genetic drift and a shift in the adaptive fitness landscape,[42] 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 allowed for the

existence of stasis in what he called the bradytelic mode, Simpson considered it (along with rapid evolution) t

be insignificant in the larger scope of evolution. In hisMajor Features of Evolution Simpson stated,

"Evolutionary change is so nearly the universal rule that a state of motion is, figuratively, normal in evolvingpopulations. 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 critiquesfrom such

eminent commentators as Sewall Wright and G. G. Simpsonhave argued that punctuated equilibrium is litt

more than quantum evolution relabeled.[43][44]

The multiple meanings of gradualism

Punctuated equilibrium is often portrayed to oppose the concept of gradualism, when it is actually a form of

gradualism.[45] This is because even though evolutionary change appears instantaneous between geological

sediments, change is still occurring incrementally, with no great change from one generation to the next. Tothis end, Gould later commented that "Most of our 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 evolutionary colleagues also failed to grasp the implication(s), primarily

because they did not think at geological scales".[12]

Richard Dawkins dedicated 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 rate of speed, called "constant speedism" by Dawkins is a

"caricature of Darwinism"[46] and "does not really exist."[47] 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, believing that

evolution jumps between stability and relative rapidity, are described as "discrete variable speedists," and "in

this respect they are genuinely radical."[48] They believe that evolution generally proceeds in bursts, or not at

all. "Continuously variable speedists," on the other hand believe that "evolutionary rates fluctuate continuous

from very fast to very slow and stop, with all intermediates. They see no particular reason to emphasize certai

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."[49] Dawkins therefore commits himself here to a

empirical claim about the geological record, in contrast to his earlier claim that, "The paleontological evidenccan be argued about, and I am not qualified to judge it."[50] It is this particular commitment that Eldredge and

Gould have aimed to overturn.

The relationship between punctuationism and gradualism can be better appreciated by considering an exampl

Suppose the average length of a limb in a particular species grows 50 centimeters (20 inches) over 70,000

yearsa large amount in a geologically short period of time. If the average generation is seven years, then ou

given time span corresponds to 10,000 generations. It is therefore reasonable to conclude that if the limb size

in our hypothetical population evolved in the most conservative manner, it need only increase at a rate of


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0.005 cm per generation (= 50 cm/10,000), despite its abrupt appearance in the geological

record.[citation needed]

Criticism

Richard Dawkins believes that the apparent gaps represented in the fossil record document migratory events

rather than evolutionary events. According to Dawkins, evolution certainly occurred but "probably gradually

elsewhere.[51] However, the punctuational equilibrium model may still be inferred from both the observance

of stasis and documented examples of rapid and episodic speciation events documented in the fossil record. [5

Dawkins also emphasizes that punctuated equilibrium has been "oversold by some journalists",[53] but partly

due to Eldredge and Gould's "later writings".[54] Dawkins contends that the theory "does not deserve a

particularly large measure of publicity".[55] 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". [56]

In his bookDarwin's Dangerous Idea, philosopher Daniel Dennett is especially critical of Gould's

presentation of punctuated equilibrium. Dennett argues that Gould alternated between revolutionary andconservative claims about the theory, and that each time Gould made a revolutionary statementor appeared

to do sohe was criticized, and thus retreated to a traditional neo-Darwinian position. [57] Gould responded t

Dennett's claims in The New York Review of Books,[58] and in his technical volume The Structure of

Evolutionary Theory.[59]

Literary scholar Heidi Scott argued that Gould's use of analogy and metaphor constitutes a non-scientific

discourse serving to validate a scientific theory.[60] She claims that Gouldparticularly in his popular essays

uses a variety of strategies from literature, political science, and personal anecdotes to substantiate the

general pattern of punctuated equilibrium (long periods of stasis interrupted by rapid, catastrophic change).

Gould responded that critics often made the mistake of confusing the context of discovery with the context ofustification. While Gould is celebrated for the color and energy of his prose, as well as his massive

interdisciplinary knowledge, critics such as Scott have concerns that the theory has gained undeserved

credence among non-scientists because of Gould's rhetorical skills.[60]

Randy Allen Harris, Professor of Rhetoric at the University of Waterloo, in a more positive evaluation, states

that "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."[61]

Relation to Darwin's theories

The sudden appearance of most species in the geologic record and the lack of evidence of substantial gradual

change in most speciesfrom their initial appearance until their extinctionhas long been noted, including b

Charles Darwin who appealed to the imperfection of the record as the favored explanation.[62][63] 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


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nature of evolution in accordance with the gradualism promoted by his friend Charles Lyell. He privately

expressed concern, noting in the margin of his 1844Essay, "Better begin with this: If species really, after

catastrophes, created in showers world over, my theory false."[64]

It is often incorrectly assumed that he insisted that the rate of change must be constant, or nearly so, but even

the first edition ofOn 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 is among the few brachiopods surviving today but also known from fossils

over 500 million years old.[65] In the fourth edition (1866) ofOn the Origin of Species Darwin wrote that "th

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." [66] Thus punctuationism

in general is consistent with Darwin's conception of evolution.[64]

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 productioof species which shall prove capable of enduring for a long period, and of spreading widely." [67]

The importance of isolation in forming species had played a significant part in Darwin's early thinking, as

shown in hisEssay of 1844. But by the time he wrote the Origin he had downplayed its importance.[64] He

explained the reasons for his revised view as follows:

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 acorresponding 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 ... 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.[68]

Thus punctuated equilibrium contradicts some of Darwin's ideas regarding the specific mechanisms of

evolution, but generally accords with Darwin's theory of evolution by natural selection. [64]

Supplemental modes of rapid evolution

See also: Rapid modes of evolution

Recent work in developmental biology has identified dynamical and physical mechanisms of 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


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increasingly common in the field of evolutionary developmental biology, particularly in studies of the origin o

morphological novelty. A description of such mechanisms can be found in the multi-authored volume

Origination of Organismal Form (MIT Press; 2003).

Punctuated equilibrium in social theory

See also: Punctuated equilibrium in social theory

Punctuated equilibrium in social theory is a method of understanding change in complex social systems,

particularly how policy change and the development of conflicts seem to progress in extended periods of

stasis, punctuated by sudden shifts in radical change.

Punctuated equilibrium in international relations

Recent work in international relations suggests that punctuated equilibrium can also be used to describe the

pattern of change and innovation in a cluster of international organizations known as a regime complex. [69]

In language change

In linguistics, R.M.W. Dixon has proposed a punctuated equilibrium model for language histories, with

reference particularly to the prehistory of the indigenous languages of Australia and his objections to the

proposed PamaNyungan language family there. Although his model has raised considerable interest, it does

not command majority support within linguistics. Separately, recent work using computational phylogenetic

methods claims to show that punctuational bursts play an important factor when languages split from one

another, accounting for anywhere from 10 to 33% of the total divergence in vocabulary.[70]

See also

Adaptive radiationEvolutionary capacitanceGene ordersKoinophiliaHopeful MonsterPunctuated gradualismCourt Jester Hypothesis

References

1. ^ ab Gould, Stephen Jay, & Eldredge, Niles (1977). "Punctuated equilibria: the tempo and mode of evolution

reconsidered." (http://www.nileseldredge.com/pdf_files/Punctuated_Equilibria_Gould_Eldredge_1977.pdf)

Paleobiology3 (2): 115-151. (p.145)

2. ^ abc Eldredge, Niles and S. J. Gould (1972). "Punctuated equilibria: an alternative to phyletic gradualism"

(http://www.blackwellpublishing.com/ridley/classictexts/eldredge.asp) In T.J.M. Schopf, ed., Models in

Paleobiology. San Francisco: Freeman Cooper. pp. 82-115. Reprinted in N. Eldredge Time frames. Princeton:


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Princeton Univ. Press, 1985, pp. 193-223 (http://www.nileseldredge.com/NELE.htm) .

3. ^ abc Mayr, Ernst (1954). "Change of genetic environment and evolution"

(http://www.blackwellpublishing.com/ridley/classictexts/mayr.asp) In J. Huxley, A. C. Hardy and E. B. Ford.

Evolution as a Process. London: Allen and Unwin, pp. 157-180.

4. ^ Lerner, Israel Michael (1954). Genetic Homeostasis. New York: John Wiley.

5. ^ ab Eldredge, Niles (1971). "The allopatric model and phylogeny in Paleozoic invertebrates"

(http://www.nileseldredge.com/pdf_files/Allopatric_Model_Phylogeny_Paleozoic_Invertebrates_Eldredge_1971.p

f) .Evolution25 (1): 156167. doi:10.2307/2406508 (http://dx.doi.org/10.2307%2F2406508) . JSTOR 2406508

(http://www.jstor.org/stable/2406508) .http://www.nileseldredge.com/pdf_files/Allopatric_Model_Phylogeny_Paleozoic_Invertebrates_Eldredge_1971.pd

6. ^ Gould, S. J. (1969). "An evolutionary microcosm: Pleistocene and Recent history of the land snail P.

(Poecilozonites) in Bermuda".Bull. Mus. Comp. Zool.138: 407532.

7. ^ abcd Mayr, Ernst (1992). "Speciational Evolution or Punctuated Equilibria."

(http://www.stephenjaygould.org/library/mayr_punctuated.html) In Albert Somit and Steven Peterson The

Dynamics of Evolution. New York: Cornell University Press, pp. 21-48.

8. ^ Shermer, Michael (2001). The Borderlands of Science. New York: Oxford University Press.

9. ^ Geary, Dana (2008). "The Legacy of Punctuated equilibrium." (http://books.google.com/books?

id=6iVOHEVeSFMC&pg=PA127) In Warren D. Allmon et al. Stephen Jay Gould: Reflections on His View of

Life. Oxford: Oxford University Press, pp. 127-145.

10. ^ Schindewolf, Otto (1936). Paldontologie, Entwicklungslehre und Genetik. Berlin: Borntraeger.11. ^ Gould, Stephen Jay (2002). The Structure of Evolutionary Theory. Cambridge, Massachusetts: The Belknap Pre

of Harvard University Press. p. 775.. ISBN 0-674-00613-5.

12. ^ ab Gould, S. J. (1991). "Opus 200" (http://www.stephenjaygould.org/library/gould_opus200.html) Natural

History 100 (August): 12-18.

13. ^ Eldredge, N. 1985. Time Frames: The evolution of punctuated equilibria. Princeton: Princeton University Press

p. 120.

14. ^ Wilkins, J.S and Nelson, G.J. (2008). Trmaux on species: A theory of allopatric speciation (and punctuated

equilibrium) before Wagner. Archives of Philosophy of the Science. University of Pittsburgh USA. pdf:

http://philsci-archive.pitt.edu/3881/1/Tremaux-on-species.pdf. Published online as "pre-print" format in this digita

library and definitively published inHistory and Philosophy of the Life Sciences (Hist. Philos. Life Sci, 2008,

30:179-206).15. ^ ab Mayr, Ernst (1963). Animal Species and Evolution. Cambridge, MA: Harvard University Press.

16. ^ Gould, S. J. (1982). "Punctuated EquilibriumA Different Way of Seeing," (http://books.google.com/books?

id=504iVZyopJ8C&pg=PA137) New Scientist94 (April 15): 138.

17. ^ Futuyma, Douglas (1987). "On the role of species in anagenesis". American Naturalist130 (3): 465473.

doi:10.1086/284724 (http://dx.doi.org/10.1086%2F284724) .

18. ^ Nichol, S.T, Joan Rowe, and Wlater M. Fitch (1993). "Punctuated equilibrium and positive Darwinian evolutio

in vesicular stomatitis virus." (http://www.pnas.org/content/90/22/10424.full.pdf) Proceedings of the National

Academy of Sciences 90 (Nov.): 10424-28.

19. ^ Gould, S. J. 2002. The Structure of Evolutionary Theory. Cambridge MA: Harvard University Press, p. 875

(http://books.google.com/books?id=nhIl7e61WOUC&pg=PA1154) .

20. ^ Wake, David B.; Roth, G.; Wake, M. H. (1983). "On the problem of stasis in organismal evolution".Journal of

Theoretical Biology101 (2): 212.

21. ^ Simpson, G. G. (1944). Tempo and Mode in Evolution. Columbia University Press. New York, p. 203.



23. ^ ab Futuyma, Douglas (2005).Evolution. Sunderland, MA: Sinauer Associates, p. 86.

24. ^ Eldredge, N.; Gould, S. J. (1974). "Reply to Hecht". Evolutionary Biology7: 305306.

25. ^ Niles Eldredge (1989). Time Frames. Princeton University Press, pp. 139-141.

26. ^ ab Lieberman, B. S.; Dudgeon, S. (1996). "An evaluation of stabilizing selection as a mechanism for stasis".

Palaeogeog. Palaeoclimat. Palaeoecol127: 229238.


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27. ^ Stenseth, N. C.; Smith, J. Maynard (1984). "Coevolution in ecosystems: Red Queen evolution or stasis?".

Evolution38 (4): 870880.

28. ^ Williams, G. C. (1992).Natural Selection: Domains, Levels and Challenges. NY: Oxford University Press, p.

132.

29. ^ Maynard Smith, John (1989). Did Darwin Get it Right? New York: Chapman and Hall, p. 126.



31. ^ Sterelny, Kim (2007).Dawkins vs. Gould: Survival of the Fittest. Cambridge, U.K.: Icon Books, p. 96.

32. ^ Gould, S. J. (1976). "The Return of Hopeful Monsters," (http://www.stephenjaygould.org/library/gould_hopefu

monsters.html) Natural History 86 (June/July): 22-30.

33. ^ Mayr, Ernst (1982). Growth of Biological Thought. Harvard University Press, p. 617

34. ^ Maynard Smith, J. (1983) "The genetics of stasis and punctuations."

(http://teosinte.wisc.edu/gen677_pdfs/Maynard_Smith.pdf) Annual Review of Genetics 17: 12.

35. ^ Ruse, Michael (1985) Sociobiology, Sense or Nonsense? New York: Springer, p. 216.

(http://books.google.com/books?id=LdSgNlQgdlkC&pg=PA216)

36. ^ For reply see S. J. Gould Structure. 2002, pp. 765, 778, 1001, 1005, 1009; R. Dawkins The Blind Watchmaker

1996, pp. 230-36 (http://books.google.com/books?id=sPpaZnZMDG0C&pg=PA231) ; and D. Dennett Darwin's

Dangerous Idea. 1996, pp. 288-289 (http://books.google.com/books?id=FvRqtnpVotwC&pg=PA288) .

37. ^ Hanegraaff, Hank (1998). The Face That Demonstrates the Farce of Evolution. Nashville, TN: Word Publishin

pp. 40-45. (http://books.google.com/books?id=Ta-qOuhtGkAC&pg=PA40)

38. ^ Gould, S. J. (1981). "Evolution as Fact and Theory," (http://www.stephenjaygould.org/library/gould_fact-and-

theory.html)Discover 2 (May): 34-37.

39. ^ Ayala, F. (2005). "The Structure of Evolutionary Theory"

(http://www.stephenjaygould.org/reviews/ayala_structure.pdf) (PDF). Theology and Science3 (1): 104.

http://www.stephenjaygould.org/reviews/ayala_structure.pdf.

40. ^ Gould, S. J. (2007) Punctuated equilibrium. Cambridge MA: Harvard University Press, p. 26.

41. ^ ab Simpson, G. G. (1944). Tempo and Mode in Evolution. New York: Columbia Univ. Press, p. 206

42. ^ Simpson, G. G. (1953). The Major Features of Evolution

(http://www.stephenjaygould.org/library/simpson_evolutionary-rates.html) . New York: Columbia Univ. Press, p.

390.

43. ^ Wright, Sewall (1982). "Character change, speciation, and the higher taxa"

(http://stewardshipofcreationenabler.giving.officelive.com/Documents/21_Wright1982.pdf) (PDF).Evolution56(3): 427. http://stewardshipofcreationenabler.giving.officelive.com/Documents/21_Wright1982.pdf.

44. ^ Simpson, G. G. (1984) Tempo and Mode in Evolution. Reprint. Columbia University Press, p. xxv.

45. ^ Dawkins, Richard (1996). The Blind Watchmaker. New York: W. W. Norton & Co., Chapter 9. (p. 224-252)

46. ^ Dawkins, Richard (1996). The Blind Watchmaker. New York: W. W. Norton & Co., p. 227.

47. ^ Dawkins, Richard (1996). The Blind Watchmaker, p. 228. Dawkins' exception to this rule is the non-adaptive

evolution observed in molecular evolution.

48. ^ Dawkins, Richard (1996). The Blind Watchmaker, p. 245.

49. ^ Dawkins, Richard (1996). The Blind Watchmaker, p. 245-246.

50. ^ Dawkins, R (1982) The Extended Phenotype. London: Oxford University Press, p. 102.


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58. ^ Gould, S. J. (1997). "Darwinian Fundamentalism" (http://www.nybooks.com/articles/1151) The New York

Review of Books, June 12, pp. 34-37; and "Evolution: The Pleasures of Pluralism"

htt ://www.ste hen a ould.or /reviews/ ould_ luralism.html The New York Review o Books, June 26, . 47-


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59. ^ Gould, S. J. (2002). The Structure of Evolutionary Theory, pp. 1006-1021. Online here

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63. ^ Darwin, Charles (1871). The Origin of Species. London: John Murray, p. 119-120.64. ^ abcd Eldredge, Niles (2006) "Confessions of a Darwinist."

(http://www.vqronline.org/articles/2006/spring/eldredge-confessions-darwinist/) The Virginia Quarterly Review 82

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68. ^ Darwin, Charles (1869). The Origin of Species. London: John Murray. 5th edition, pp. 121-122. (http://darwin-

online.org.uk/content/frameset?itemID=F387&viewtype=text&pageseq=1)69. ^ http://www.springerlink.com/content/g52862pp15572540/

70. ^ Atkinson, Quentin, et al. (2008). "Languages Evolve in Punctuational Bursts". Science319: 588.

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Further reading

Adler, J. and Carey, J. (1982) "Enigmas of Evolution"(http://www.stephenjaygould.org/library/newsweek_sjgould.html) Newsweek, March 29, 1982.

Brett, C. E., L. C. Ivany, and K. M. Schopf (1996). "Coordinated stasis: An overview".Palaeogeography Palaeoclimatology Palaeoecology127 (14): 120. doi:10.1016/S0031-0182(96)00085-5 (http://dx.doi.org/10.1016%2FS0031-0182%2896%2900085-5) .Erwin, D. H. and R. L. Anstey (1995)New approaches to speciation in the fossil record. NewYork : Columbia University Press.Fitch, W. J. and F. J. Ayala (1995) Tempo and mode in evolution: genetics and paleontology 50

years after Simpson. Washington, D.C.: National Academy Press.Gould, S. J. (1982) "Punctuated EquilibriumA Different Way of Seeing."(http://books.google.com/books?id=504iVZyopJ8C&pg=PA137)New Scientist94 (Apr. 15): 137139.Gould, S. J. (1992) "Punctuated equilibrium in fact and theory." In Albert Somit and StevenPeterson The Dynamics of Evolution. New York: Cornell University Press. pp. 5484.Gould, S. J. and N. Eldredge (1993). "Punctuated equilibrium comes of age"(http://www.stephenjaygould.org/library/gould_comes-of-age.html) .Nature366 (6452): 223227doi:10.1038/366223a0 (http://dx.doi.org/10.1038%2F366223a0) . PMID 8232582(http://www.ncbi.nlm.nih.gov/pubmed/8232582) .http://www.stephenjaygould.org/library/gould_comes-of-age.html.Prothero, D. (2007). "Punk eek, Transitional Formsand Quote Miners."(http://books.google.com/books?id=QeKWpRX77JgC&pg=PA78) InEvolution: what the fossils


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say and why it matters. New York: Columbia University Press, pp. 7885.Rhodes, R. H. T. (1983). "Gradualism, punctuated equilibrium and the Origin of Species".Nature305 (5932): 269272. doi:10.1038/305269a0 (http://dx.doi.org/10.1038%2F305269a0) .PMID 6353241 (http://www.ncbi.nlm.nih.gov/pubmed/6353241) .Turner, John (1984). "Why we need evolution by jerks." (http://books.google.com/books?id=6idhDboGmZoC&pg=PA34)New Scientist101 (Feb. 9): 34-35.

External links

Opus 200 (http://www.stephenjaygould.org/library/gould_opus200.html) - by Stephen Jay GouldPunctuated Equilibrium (http://books.google.com/books?hl=en&id=cgKUZXeRoOYC&printsec=frontcover) - by Stephen Jay GouldPunctuated Equilibria: An Alternative to Phyletic Gradualism(http://www.blackwellpublishing.com/ridley/classictexts/eldredge.asp) - by Niles Eldredge andStephen Jay GouldPunctuated Equilibria: The Tempo and Mode of Evolution Reconsidered(http://www.nileseldredge.com/pdf_files/Punctuated_Equilibria_Gould_Eldredge_1977.pdf) - byStephen Jay Gould and Niles Eldredge

Speciational Evolution or Punctuated Equilibria(http://www.stephenjaygould.org/library/mayr_punctuated.html) - by Ernst MayrPunctuated Equilibrium Comes of Age (http://www.stephenjaygould.org/library/gould_comes-of-age.html) - by Stephen Jay Gould and Niles EldredgePunctuated EquilibriaWhere is the Evidence?(http://we.vub.ac.be/~dglg/Web/Teaching/Les/Discussions/PunctEq/Gingerich-1984.pdf) - by PhilD. GingerichPunctuated Equilibrium at Twenty (http://faculty.oxy.edu/prothero/papers/1992_puncuated.pdf) - bDonald R. ProtheroOn Punctuated Equilibria (http://www.stephenjaygould.org/library/science_on-punctuated-

equilibria.html) - by Niles Eldredge and Stephen Jay GouldPunctuated Equilibrium's Threefold History(http://www.stephenjaygould.org/library/gould_structure.html) - by Stephen Jay GouldThe Dynamics of Evolutionary Stasis(http://www.nileseldredge.com/pdf_files/Dynamics_of_Evolutionary_Stasis.pdf) - by NilesEldredgePunctuated Equilibria? (http://www.talkorigins.org/faqs/punc-eq.html) - by Wesley Elsberry,TalkOrigins ArchiveScholarpedia: Punctuated equilibria (http://www.scholarpedia.org/article/Punctuated_equilibria) - bBruce Lieberman and Niles EldredgeAll you need to know about Punctuated Equilibrium (almost) (http://theobald.brandeis.edu/pe.html

- by Douglas Theobald

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