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Punctuated Equilibrium
In 1972 Stephen Jay Gould took the scientific world by storm with his paper on punctuated equilibrium, written with Niles Eldredge. Challenging a core assumption of Darwin's theory of evolution, it launched the career of one of the most influential evolutionary biologists of our time--perhaps the best known since Darwin.
Now, thirty-five years later, and five years after his untimely death, Punctuated Equilibrium (originally published as the central chapter of Gould's masterwork, The Structure of Evolutionary Theory) offers his only book-length testament on an idea he fiercely promoted, repeatedly refined, and tirelessly defended. Punctuated equilibrium holds that the great majority of species originate in geological moments (punctuations) and persist in stasis. The idea was hotly debated because it forced biologists to rethink entrenched ideas about evolutionary patterns and processes. But as Gould shows here in his typically exhaustive coverage, the idea has become the foundation of a new view of hierarchical selection and macroevolution.
What emerges strikingly from this book is that punctuated equilibrium represents a much broader paradigm about the nature of change--a worldview that may be judged as a distinctive and important movement within recent intellectual history. Indeed we may now be living within a punctuation, and our awareness of what this means may be the enduring legacy of one of America's best-loved scientists.
Now, thirty-five years later, and five years after his untimely death, Punctuated Equilibrium (originally published as the central chapter of Gould's masterwork, The Structure of Evolutionary Theory) offers his only book-length testament on an idea he fiercely promoted, repeatedly refined, and tirelessly defended. Punctuated equilibrium holds that the great majority of species originate in geological moments (punctuations) and persist in stasis. The idea was hotly debated because it forced biologists to rethink entrenched ideas about evolutionary patterns and processes. But as Gould shows here in his typically exhaustive coverage, the idea has become the foundation of a new view of hierarchical selection and macroevolution.
What emerges strikingly from this book is that punctuated equilibrium represents a much broader paradigm about the nature of change--a worldview that may be judged as a distinctive and important movement within recent intellectual history. Indeed we may now be living within a punctuation, and our awareness of what this means may be the enduring legacy of one of America's best-loved scientists.
408 pages, Paperback
First published May 31, 2007
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Displaying 1 - 14 of 14 reviews
June 22, 2022
A not so easy book to read yet an important book to read. The book is a defense of Stephen J. Gould thoery of Pumctuated Equilibrium in contrast to the original idea of slow evolution known as " Gradualism" ! H does not negate in totality the idea of slow evolution across geological time but he points out of instances of relative "not so slow" evolution across thousande of years and not neccassrily millions of years! Worth reading!
June 16, 2024
EXCERPTS FROM GOULD’S LARGER BOOK
[NOTE: This posthumously-published book contains material reprinted from Chapters 1 and 9 of ‘The Structure of Evolutionary Theory.”]
The Introduction states, “punctuated equilibrium stands for a larger and coherent set of mostly iconoclastic concerns… As I began my professional preparation for a career in paleontology … [a] vague dissatisfaction coagulated into two operational foci of discontent. First… I became deeply troubled by the Darwinian convention that attributed all non-gradualistic literal appearances to imperfections of the geological record… Second, I became increasingly disturbed that, at the higher level of evolutionary trends within clades, the majority of well documented examples… have never been adequately explained in the terms demanded by Darwinian convention---that is, as adaptive improvements of constituent organisms in anagenetic sequences. Most so-called explanations amounted to little more than … plausible claims without tested evidence, whereas other prominent trends couldn’t even generate a plausible story in adaptationist terms at all.
“As [Niles] Eldredge and I devised punctuated equilibrium, I did use the theory to resolve these two puzzles to my satisfaction, and each resolution… led to my two major critiques of the first two branches of the essential triad of Darwinian central logic… By accepting the geologically abrupt appearance and subsequent extended stasis of species as a fair description of an evolutionary reality… we soon recognized that species met all criteria for definition and operation as genuine Darwinian individuals in the higher-level domain of macroevolution---and this insight … led us to concepts of species selection in particular and, eventually, to the full hierarchical model of selection as an interesting theoretical challenge and contrast to Darwinian convictions about the exclusivity of organismal selection.” (Pg. 1-3)
He notes “a primary inference of punctuated equilibrium---that a local pattern of abrupt replacement does not signify macromutational transformation in situ, but an origin of the later species from an ancestral population living elsewhere, followed by migration into the local region,” (Pg. 17-18)
He points out “the cardinal and dominant fact of the fossil record… the great majority of species appear with geological abruptness in the fossil record and then persist in stasis until their extinction… the last remnants of a species usually look pretty much like the first representatives… Paleontologists have always recognized the longterm stability of most species, but we had become more than a bit ashamed by this strong and literal signal, for the dominant theory of our scientific culture told us to look for the opposite results of gradualism as the primary empirical expression of every biologist’s favorite subject—evolution itself.” (Pg. 19)
He summarizes, “the potentially reformative role of punctuated equilibrium resides in .. [that it] merely honored the firmest and eldest of all paleontological observations---the documentable stasis of most fossil morphologies---by promoting this pattern to central recognition as an expected result of evolution’s proper expression at the scale of geological time.” (Pg. 38) He continues, “punctuated equilibrium holds that the great majority of species… originate in geological moments (punctuations) and then persist in stasis throughout their long durations… species meet all definitional criteria for operating as Darwinian individuals… in the domain of microevolution.” (Pg. 40) Later, he adds, “punctuated equilibrium makes its major contribution to evolutionary theory, not by revising evolutionary mechanics, but by individuating species…” (Pg. 58)
He explains, “the theory of punctuated equilibrium adopts a very conservative position. The theory… merely takes a standard microevolutionary model and elucidates its expected expression when properly scaled into geologic time. This scaling, however, did provoke a radical reinterpretation of paleontological data—for we argued that the literal appearance of the fossil record, though conventionally dismissed as an artifact of imperfect evidence, may actually be recording the workings of evolution.” (Pg. 54)
He suggests, “If evolutionary rate correlates primarily with frequency of speciation---the cardinal prediction of punctuate equilibrium---then living fossils may simply represent those groups … that have persisted through geological time at consistently and varyingly low species diversity… and have therefore never experienced substantial opportunity for extensive change at this level.” (Pg. 101-102)
He says, “the stress placed by punctuated equilibrium upon the phenomenon of stasis may emerge as the theory’s most important contribution to evolutionary science… punctuated equilibrium largely ‘created’ the category of stasis as an important item in evolutionary theory through a four-step process of (1) defining stasis as a positive ‘thing’ with properties and boundaries… rather than an unnamed and unrecognized absence of evolution; (2) bringing stasis to visibility as the expectation of a particular theory of evolutionary modalities; (3) suggesting methods for the active and rigorous study of stasis, so that the concept could be operationalized as a subject for empirical research; and (4) granting interest and importance to stasis as a controversial topic with broad implications for revising traditional modes of thought in evolutionary theory.” (Pg. 172-173)
He argues, “if stasis merely reflects excellent adaptation to environment, then why do we frequently observe such profound stasis during major climatic shifts like ice-age cycles… or through the largest environmental change in a major interval of time…? More importantly, conventional arguments about stabilizing selection have been framed for discrete populations on adaptive peaks, not for the TOTALITY of a species---the proper scale of punctuated equilibrium.” (Pg. 176)
He acknowledges, “I now believe that these criticisms, with respect to the issue of stasis, in paleospecies through geological time, were largely justified—and that the theme of constraint, while not irrelevant to the causes of stasis in punctuated equilibrium, does not play the strong role that I initially advocated.” (Pg. 179)
He states, “[if] stasis emerges as an active norm, not merely a passive consequence… then evolutionary change itself must be reconceptualized as the infrequent breaking of a conventional and expected state, rather than as an inherent and continually operating property of biological materials, ecologies, and populations.” (Pg. 184-185)
He says, “[I] mean to assert the hypothesis of no overall preference for increasing complexity among items added to the distribution… I do not deny, of course, that individual lineages in such systems may develop increasing complexity for conventional adaptive reasons… why should we target increasing complexity as a favored hypothesis for a general pattern in the history of life?” (Pg. 203)
He admits, “if I were to cite any one factor as probably the most important among the numerous influences that predisposed my own mind toward joining Niles Eldredge in the formulation of punctuated equilibrium, I would mention my reading, as a first-year graduate student in 1962, of one of the 20th century’s most influential works at the interface of philosophy, sociology and the history of ideas; Thomas S. Kuhn’s ‘The Structure of Scientific Revolutions.’” (Pg. 283)
He summarizes, “I can at least assert that punctuated equilibrium unites three definitive themes---the three legs of my tripod of support for an expansion of Darwinian theory, thereby leading me to conclude that an empirically legitimate and logically sound structure does encompass and unite these three arguments into a coherent and general reformulation and extension of the Darwinian paradigm: the hierarchical theory of selection on leg one, the structuralist critique of Darwinian functionalism and adaptationism on leg two, and the paleontologist’s conviction (leg three) that general microevolutionary processes and mechanisms cannot be fully elucidated by uniformitarian extrapolation from the smallest scale of our experiments and personal observations.” (Pg. 287)
He concludes, “Punctuated equilibrium has proven its mettle in: 1. Elucidating and epitomizing what may be the primary process of a distinctive level in the evolutionary hierarchy: the role of species as Darwinian individuals… 2. Defining … the issue of stasis as a subject for study… 3. Stressing that level-bound punctuational breaks preclude the prediction or full understanding of extensive temporal change from principles of anagenetic transformation at the lowest level… thus emphasizing contingency and denying extrapolationist premises and methodologies.” (Pg. 287-288)
For Gould’s “last word” on punctuated equilibrium, this book will be “must reading” for students of evolutionary theory.
[NOTE: This posthumously-published book contains material reprinted from Chapters 1 and 9 of ‘The Structure of Evolutionary Theory.”]
The Introduction states, “punctuated equilibrium stands for a larger and coherent set of mostly iconoclastic concerns… As I began my professional preparation for a career in paleontology … [a] vague dissatisfaction coagulated into two operational foci of discontent. First… I became deeply troubled by the Darwinian convention that attributed all non-gradualistic literal appearances to imperfections of the geological record… Second, I became increasingly disturbed that, at the higher level of evolutionary trends within clades, the majority of well documented examples… have never been adequately explained in the terms demanded by Darwinian convention---that is, as adaptive improvements of constituent organisms in anagenetic sequences. Most so-called explanations amounted to little more than … plausible claims without tested evidence, whereas other prominent trends couldn’t even generate a plausible story in adaptationist terms at all.
“As [Niles] Eldredge and I devised punctuated equilibrium, I did use the theory to resolve these two puzzles to my satisfaction, and each resolution… led to my two major critiques of the first two branches of the essential triad of Darwinian central logic… By accepting the geologically abrupt appearance and subsequent extended stasis of species as a fair description of an evolutionary reality… we soon recognized that species met all criteria for definition and operation as genuine Darwinian individuals in the higher-level domain of macroevolution---and this insight … led us to concepts of species selection in particular and, eventually, to the full hierarchical model of selection as an interesting theoretical challenge and contrast to Darwinian convictions about the exclusivity of organismal selection.” (Pg. 1-3)
He notes “a primary inference of punctuated equilibrium---that a local pattern of abrupt replacement does not signify macromutational transformation in situ, but an origin of the later species from an ancestral population living elsewhere, followed by migration into the local region,” (Pg. 17-18)
He points out “the cardinal and dominant fact of the fossil record… the great majority of species appear with geological abruptness in the fossil record and then persist in stasis until their extinction… the last remnants of a species usually look pretty much like the first representatives… Paleontologists have always recognized the longterm stability of most species, but we had become more than a bit ashamed by this strong and literal signal, for the dominant theory of our scientific culture told us to look for the opposite results of gradualism as the primary empirical expression of every biologist’s favorite subject—evolution itself.” (Pg. 19)
He summarizes, “the potentially reformative role of punctuated equilibrium resides in .. [that it] merely honored the firmest and eldest of all paleontological observations---the documentable stasis of most fossil morphologies---by promoting this pattern to central recognition as an expected result of evolution’s proper expression at the scale of geological time.” (Pg. 38) He continues, “punctuated equilibrium holds that the great majority of species… originate in geological moments (punctuations) and then persist in stasis throughout their long durations… species meet all definitional criteria for operating as Darwinian individuals… in the domain of microevolution.” (Pg. 40) Later, he adds, “punctuated equilibrium makes its major contribution to evolutionary theory, not by revising evolutionary mechanics, but by individuating species…” (Pg. 58)
He explains, “the theory of punctuated equilibrium adopts a very conservative position. The theory… merely takes a standard microevolutionary model and elucidates its expected expression when properly scaled into geologic time. This scaling, however, did provoke a radical reinterpretation of paleontological data—for we argued that the literal appearance of the fossil record, though conventionally dismissed as an artifact of imperfect evidence, may actually be recording the workings of evolution.” (Pg. 54)
He suggests, “If evolutionary rate correlates primarily with frequency of speciation---the cardinal prediction of punctuate equilibrium---then living fossils may simply represent those groups … that have persisted through geological time at consistently and varyingly low species diversity… and have therefore never experienced substantial opportunity for extensive change at this level.” (Pg. 101-102)
He says, “the stress placed by punctuated equilibrium upon the phenomenon of stasis may emerge as the theory’s most important contribution to evolutionary science… punctuated equilibrium largely ‘created’ the category of stasis as an important item in evolutionary theory through a four-step process of (1) defining stasis as a positive ‘thing’ with properties and boundaries… rather than an unnamed and unrecognized absence of evolution; (2) bringing stasis to visibility as the expectation of a particular theory of evolutionary modalities; (3) suggesting methods for the active and rigorous study of stasis, so that the concept could be operationalized as a subject for empirical research; and (4) granting interest and importance to stasis as a controversial topic with broad implications for revising traditional modes of thought in evolutionary theory.” (Pg. 172-173)
He argues, “if stasis merely reflects excellent adaptation to environment, then why do we frequently observe such profound stasis during major climatic shifts like ice-age cycles… or through the largest environmental change in a major interval of time…? More importantly, conventional arguments about stabilizing selection have been framed for discrete populations on adaptive peaks, not for the TOTALITY of a species---the proper scale of punctuated equilibrium.” (Pg. 176)
He acknowledges, “I now believe that these criticisms, with respect to the issue of stasis, in paleospecies through geological time, were largely justified—and that the theme of constraint, while not irrelevant to the causes of stasis in punctuated equilibrium, does not play the strong role that I initially advocated.” (Pg. 179)
He states, “[if] stasis emerges as an active norm, not merely a passive consequence… then evolutionary change itself must be reconceptualized as the infrequent breaking of a conventional and expected state, rather than as an inherent and continually operating property of biological materials, ecologies, and populations.” (Pg. 184-185)
He says, “[I] mean to assert the hypothesis of no overall preference for increasing complexity among items added to the distribution… I do not deny, of course, that individual lineages in such systems may develop increasing complexity for conventional adaptive reasons… why should we target increasing complexity as a favored hypothesis for a general pattern in the history of life?” (Pg. 203)
He admits, “if I were to cite any one factor as probably the most important among the numerous influences that predisposed my own mind toward joining Niles Eldredge in the formulation of punctuated equilibrium, I would mention my reading, as a first-year graduate student in 1962, of one of the 20th century’s most influential works at the interface of philosophy, sociology and the history of ideas; Thomas S. Kuhn’s ‘The Structure of Scientific Revolutions.’” (Pg. 283)
He summarizes, “I can at least assert that punctuated equilibrium unites three definitive themes---the three legs of my tripod of support for an expansion of Darwinian theory, thereby leading me to conclude that an empirically legitimate and logically sound structure does encompass and unite these three arguments into a coherent and general reformulation and extension of the Darwinian paradigm: the hierarchical theory of selection on leg one, the structuralist critique of Darwinian functionalism and adaptationism on leg two, and the paleontologist’s conviction (leg three) that general microevolutionary processes and mechanisms cannot be fully elucidated by uniformitarian extrapolation from the smallest scale of our experiments and personal observations.” (Pg. 287)
He concludes, “Punctuated equilibrium has proven its mettle in: 1. Elucidating and epitomizing what may be the primary process of a distinctive level in the evolutionary hierarchy: the role of species as Darwinian individuals… 2. Defining … the issue of stasis as a subject for study… 3. Stressing that level-bound punctuational breaks preclude the prediction or full understanding of extensive temporal change from principles of anagenetic transformation at the lowest level… thus emphasizing contingency and denying extrapolationist premises and methodologies.” (Pg. 287-288)
For Gould’s “last word” on punctuated equilibrium, this book will be “must reading” for students of evolutionary theory.
April 18, 2023
This book is actually the central section of Gould's definitive treatise on punctuated equilibrium, The Structure of Evolution Theory. But it is still a detailed study of over 400 pages. Biological science is not my speciality. So I found myself having to look up the terms regularly. The book also cites an embarrassment of richness of references of case studies every step of the way on every topic presented. The famous new theory of evolution introduced by Gould and Eldeedge is an approach that treats stasis (equilibrium) as a norm while change (punctuation) as a rare occurrence. Punctuated equilibrium explains the process of macroevolution in terms of speciation and stasis at the level of species and in geological time, while treating species as Darwinian individual. A stasis can be as short as 4 million years. Changes are not only caused by speciation. They can be caused by a variety of mechanisms in addition, such as environmental change, bolide impact, or species migration. Punctuation is a short event lasting as short as tens of thousand of years on a bedding plane.
In chapter 3, Gould discussed various debates or critiques of punctuated equilibrium. A criticism is definability of paleontological species. Gould thinks as long as there is not a high frequency of paleospecies and neontological species non-correlation, and there are fossil records of correlation, definibility is not an untestable issue. Other criticisms are denying events of speciation as main locus of change and alleged failures of empirical results for affirming the predictions of punctuated equilibrium. Gould thinks branching species in peripheral next to the parental in fossils offers data support of punctuated equilibrium version of speciation as locus of change. Speciation provides morphological changes with enough permanence to register in fossil records. In terms of empirical results for affirming the predictions of punctuated equilibrium, the critiques pertain to the frequency of data supporting punctuated equilibrium or gradualism while no single case can ever decide for one or the other in terms of phylogeny. While there maybe data that supports gradualism bifurcated version of speciation, there is no lack of data to support punctuated equilibrium cladogenetic version of speciation with ancestor surviving along side descendant species. Gould cited one study of 42 gastropod speciations, only 6 suggests gradualism version while the rest shows cladogenetic punctuated version.
The chapter on Sources of data supporting punctuated equilibrium begins with showing stasis has become a vibrant study of unbranched lineage with many cases documented, to include from stasis of ostracods in Pleistocene for over 100k years, stasis of rodent species over 5 million years and to spotty stasis study of hominids from homoerectus to australopithecus robustus for 0.8 million years. Another source is by dissecting punctuation by tempo and mode. The tempo is exemplified in direct paleontological data of 10:1 ratio for puntuated vs gradual origins of species in Ordovician tribolites in rapid sedimentation compressed vertically of bedding planes for temporal resolution and punctuated origin of just 5000 years for quarternary evolution of dwarfed woolly mammoths. The mode is the morphometric mode by considering morphological transition between ancestral and descendant species. Variations of a punctuated event were observed of cretaceous echinoids. A third important source of testing data is the relative frequency of punctuated equilibrium. Finally a most important source of data that supports the relative frequencies is the large fauna of the White River group in the Badlands of south Dakota showing a large sample of mammalian species between 30 to 37 million years in the eocene to Ogliocen transition. The data showed 2 to 4 million years of punctuated equilibrium stasis for 177 mammalian species while only 3 samples showed gradualism.
Chapter 5 examines the implications of punctuated equilibrium, to include punctuation below and above the species level, and punctuated equilibrium as a model to interpret other areas of change of natural sciences. Gould is cautious to insist one should not use superficial analogy to graph such interpretation without careful homological consideration.
In chapter 3, Gould discussed various debates or critiques of punctuated equilibrium. A criticism is definability of paleontological species. Gould thinks as long as there is not a high frequency of paleospecies and neontological species non-correlation, and there are fossil records of correlation, definibility is not an untestable issue. Other criticisms are denying events of speciation as main locus of change and alleged failures of empirical results for affirming the predictions of punctuated equilibrium. Gould thinks branching species in peripheral next to the parental in fossils offers data support of punctuated equilibrium version of speciation as locus of change. Speciation provides morphological changes with enough permanence to register in fossil records. In terms of empirical results for affirming the predictions of punctuated equilibrium, the critiques pertain to the frequency of data supporting punctuated equilibrium or gradualism while no single case can ever decide for one or the other in terms of phylogeny. While there maybe data that supports gradualism bifurcated version of speciation, there is no lack of data to support punctuated equilibrium cladogenetic version of speciation with ancestor surviving along side descendant species. Gould cited one study of 42 gastropod speciations, only 6 suggests gradualism version while the rest shows cladogenetic punctuated version.
The chapter on Sources of data supporting punctuated equilibrium begins with showing stasis has become a vibrant study of unbranched lineage with many cases documented, to include from stasis of ostracods in Pleistocene for over 100k years, stasis of rodent species over 5 million years and to spotty stasis study of hominids from homoerectus to australopithecus robustus for 0.8 million years. Another source is by dissecting punctuation by tempo and mode. The tempo is exemplified in direct paleontological data of 10:1 ratio for puntuated vs gradual origins of species in Ordovician tribolites in rapid sedimentation compressed vertically of bedding planes for temporal resolution and punctuated origin of just 5000 years for quarternary evolution of dwarfed woolly mammoths. The mode is the morphometric mode by considering morphological transition between ancestral and descendant species. Variations of a punctuated event were observed of cretaceous echinoids. A third important source of testing data is the relative frequency of punctuated equilibrium. Finally a most important source of data that supports the relative frequencies is the large fauna of the White River group in the Badlands of south Dakota showing a large sample of mammalian species between 30 to 37 million years in the eocene to Ogliocen transition. The data showed 2 to 4 million years of punctuated equilibrium stasis for 177 mammalian species while only 3 samples showed gradualism.
Chapter 5 examines the implications of punctuated equilibrium, to include punctuation below and above the species level, and punctuated equilibrium as a model to interpret other areas of change of natural sciences. Gould is cautious to insist one should not use superficial analogy to graph such interpretation without careful homological consideration.
July 10, 2019
Mi sono laureato in biologia oramai 23 anni fa, e sono quello che Gould chiamerebbe un neontologo. All’epoca non sapevo nemmeno che esistesse questa differenza tra paleontologi e neontologi, ma è ovvia da comprendere. Meno ovvie sono le implicazioni che comporta. Tra queste, nel mio caso, la principale è che nel corso di studi non era previsto l’insegnamento ne della cladistica ne degli equilibri punteggiati.
Ovvio che poi, tra di noi e anche con qualche docente, se ne parlasse, ma era considerato materiale da Ph.D. e non da laurea. Quello che sapevo, prima di questa lettura, erano accenni vaghi di analisi statistiche perlopiù applicate alla genetica di popolazione e la concezione del “tempo profondo” o “deep time” per dirla all’inglese. Concetto per nulla semplice da capire: a parole è semplice, ma quando affronti e dati le serie stratigrafiche e le devi spiegare alla gente ti rendi conto che davvero aveva ragione chi diceva “puoi dire di conoscere veramente una cosa quando riesci a spiegarla e farla capire a tua nonna” (credo fosse Einstein).
Ecco, non so potrei spiegare a mia madre, la teoria degli equilibri punteggiati ma credo di avere compreso i tratti principali della teoria e la sua applicazione. Di certo sarebbe interessante poter seguire uno studio reale, con tanto di scavo paleontologico e interazione con specialisti di varie discipline. Perché non c'è niente di meglio che applicare le cose che si crede di aver imparato per essere certi di averle imparate.
Come lettura richiede una preparazione specifica, non è un libro divulgativo come altri, è un libro divulgativo per specialisti. Senza la laurea in biologia, con le sole conoscenze liceali, non credo proprio che sarei riuscito a leggere il volume. Ed io ho avuto al liceo due ottime professoresse di biologia.
La parte più interessante comunque sono gli ultimi due capitoli, ossia quello sull’applicazione della teoria ad altri campi diversi dalla biologia evoluzionistica, e quello sulle diatribe sollevate e su come una certa stampa le ha interpretate a favore del creazionismo, ossia la favola che sia esistito un dio creatore che 6000 anni fa più o meno ha creato l’universo in 7 giorni (uno per ogni nano di Biancaneve mi vien da pensare) o qualsiasi altra banale variazione su questa favola.
Ovvio che poi, tra di noi e anche con qualche docente, se ne parlasse, ma era considerato materiale da Ph.D. e non da laurea. Quello che sapevo, prima di questa lettura, erano accenni vaghi di analisi statistiche perlopiù applicate alla genetica di popolazione e la concezione del “tempo profondo” o “deep time” per dirla all’inglese. Concetto per nulla semplice da capire: a parole è semplice, ma quando affronti e dati le serie stratigrafiche e le devi spiegare alla gente ti rendi conto che davvero aveva ragione chi diceva “puoi dire di conoscere veramente una cosa quando riesci a spiegarla e farla capire a tua nonna” (credo fosse Einstein).
Ecco, non so potrei spiegare a mia madre, la teoria degli equilibri punteggiati ma credo di avere compreso i tratti principali della teoria e la sua applicazione. Di certo sarebbe interessante poter seguire uno studio reale, con tanto di scavo paleontologico e interazione con specialisti di varie discipline. Perché non c'è niente di meglio che applicare le cose che si crede di aver imparato per essere certi di averle imparate.
Come lettura richiede una preparazione specifica, non è un libro divulgativo come altri, è un libro divulgativo per specialisti. Senza la laurea in biologia, con le sole conoscenze liceali, non credo proprio che sarei riuscito a leggere il volume. Ed io ho avuto al liceo due ottime professoresse di biologia.
La parte più interessante comunque sono gli ultimi due capitoli, ossia quello sull’applicazione della teoria ad altri campi diversi dalla biologia evoluzionistica, e quello sulle diatribe sollevate e su come una certa stampa le ha interpretate a favore del creazionismo, ossia la favola che sia esistito un dio creatore che 6000 anni fa più o meno ha creato l’universo in 7 giorni (uno per ogni nano di Biancaneve mi vien da pensare) o qualsiasi altra banale variazione su questa favola.
June 25, 2021
Stephen Jay Gould, like his MIT compatriot, Noam Chomsky, writes in a dense academese dialect of English. He also spends an inordinate amount of time explaining and justifying every nuance of his basic statements.
That said, he makes a very coherent and convincing argument for punctuated equilibrium - the concept that evolution is not a slow steady creep of miniscule changes but rather long periods of equilibrium - not significant change - interspersed with bursts of significant change - punctuations.
A corollary of this theory is that the tree of life is not a constant increasing branching but rather a burst of branches off a new trunk, followed by pruning/extinctions of the less successful new species.
Because I am very interested in evolution, I plowed through this book. It was worth it to me, but it is not an easy read.
Spoiler alert - he is probably right.
That said, he makes a very coherent and convincing argument for punctuated equilibrium - the concept that evolution is not a slow steady creep of miniscule changes but rather long periods of equilibrium - not significant change - interspersed with bursts of significant change - punctuations.
A corollary of this theory is that the tree of life is not a constant increasing branching but rather a burst of branches off a new trunk, followed by pruning/extinctions of the less successful new species.
Because I am very interested in evolution, I plowed through this book. It was worth it to me, but it is not an easy read.
Spoiler alert - he is probably right.
November 19, 2024
As someone with a general interest in evolutionary theory and a background in a different area of science, I don't think this book was for me. It's wordy, repetitive and detailed. I had to look up a lot of terms. I did finish it, but probably didn't gain much from large parts and found myself scanning to no real detriment to my understanding. SJG certainly likes his parentheses, which I also found made for a difficult/cumbersome read. These criticisms are as a "general reader" and may not apply to you. I didn't feel justified giving it fewer than 4 stars given perhaps it was "my fault" for not enjoying it so much.
February 4, 2023
I guess it's a big deal for an academic to create a term used widely in their scientific discipline. That's the impression I got from this book. I'd much prefer to read some near poetic description of how punctuated equilibrium created some of the most magnificent organisms in our world But that was not to be... instead we had to hear about the theory and the debate between the uniformitarianists and the counter culture catastrophists given punctuated equilibrium and stasis as mechanisms for the flow of biologic evolution. . I'm really not impressed with Gould's book here.
December 16, 2022
Puntuated equilibrium has become a powerful theory in evolution 🧬 I've learned many things from Stephen Jay Gould!
February 23, 2011
I confess to not having read the whole book cover to cover. There are places where the technical terminology gets a little thick, and whole chapters dedicated to material of interest primarily to evolutionary scientists interested in a detailed accont of the scientific community's debates on the subject. A more general reader such as myself can afford to skip around.
Of interest to general readers will be chapters 1 and 2, parts of chapter 5, and parts of the appendix. Chapter 1 is a contextual background of evolutionary theory and assumptions before punctuated equilibrium, while chapter 2 is a statement of the theory. In chapter 5 Gould speculats on the implications for a theory of punctuated change versus graudual change in other fields outside of evoultionary biology that study complex systems. Appendix A is an addimitedly biased author;s response to the social bru-ha-ha that followed the publication of the theory, including comments on creationists' misappropriation of it. These less scientific parts are perhaps the most entertaining features of the book.
Of interest to general readers will be chapters 1 and 2, parts of chapter 5, and parts of the appendix. Chapter 1 is a contextual background of evolutionary theory and assumptions before punctuated equilibrium, while chapter 2 is a statement of the theory. In chapter 5 Gould speculats on the implications for a theory of punctuated change versus graudual change in other fields outside of evoultionary biology that study complex systems. Appendix A is an addimitedly biased author;s response to the social bru-ha-ha that followed the publication of the theory, including comments on creationists' misappropriation of it. These less scientific parts are perhaps the most entertaining features of the book.
August 24, 2009
This book is a must for anyone who really wants to understand the structure of evolutionary theory. I read it, not knowing what to expect, but still wanting to get a classic under my belt, and was surprised at how much I did not fully understand. Its quite informative and really elucidates the fine points of evolution - and fully explicates the theory of evolution from Darwin to 1999. It has changed, this theory, but it is quite effective, what stands in the way of our understanding is our own assumptions and bias' (I have decided).
November 19, 2013
S.J. Gould fu un ottimo scienziato e un eccellente divulgatore e “L'equilibrio punteggiato” rappresenta la sintesi delle due nature. Il libro fa il punto della situazione dell'omonima teoria (http://it.wikipedia.org/wiki/Teoria_d...) che Eldredge e l'autore proposero all'inizio degli anni settanta del '900, descrivendone i fondamenti, il dibattito scientifico e le fonti di dati (le prove) e delineando le conseguenze dell'equilibrio punteggiato sulla teoria evolutiva e più in generale sulle conoscenze del cambiamento. Fondamentale.
December 29, 2014
Punctuated Equilibrium attempts to explain the seemingly large discrepancy of the number of species now as compared to the past and why there are so few today. While it is diffcult worth reading bec ause it is the best explanation to date for species evolution and disappearance.
Want to read
September 12, 2009Takes a bit to get one's head around, but vast and wonderful
April 23, 2011
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