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Evolution Now
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- GenresBiology
239 pages, Paperback
First published June 1, 1982
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About the author
John Maynard Smith
41 books78 followersJohn Maynard Smith FRS was a British theoretical and mathematical evolutionary biologist and geneticist. Originally an aeronautical engineer during the Second World War, he took a second degree in genetics under the well-known biologist J. B. S. Haldane
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January 16, 2025
A COLLECTION OF ESSAYS ILLUSTRATING ISSUES BEING DATED
This 1982 book of essays was published in cooperation with the editorial staff of the journal ‘Nature.’ Editor John Maynard Smith provides an introductory commentary to each of the essays.
Smith wrote in the Introduction, “In recent years there have been claims---in the daily press, on television, and by retired cosmologists---that Darwin may have got it wrong… Darwin has indeed been criticized by scientists working in a variety of fields…The most controversial of these issues are debated in this book… This volume presents some current controversies and recent advances in evolutionary biology. But let me… first give a brief history of evolutionary ideas since Darwin. In the ‘Origin of Species,’ Darwin… argued that evolution had in fact happened… [and] that the main cause of evolutionary change was… natural selection… The next important step was the rediscovery of Mendel’s laws… and the formulation of the chromosome theory of heredity… The work of the population geneticists prepared the way for the ‘modern synthesis’… Since 1950, developments in molecular biology have had a growing influence… There is, however, one area of molecular biology which seems to me to lag behind the rest. This is the study of the evolution of prokaryotes (organisms … lacking a proper cell nucleus)… The papers printed below … have concentrated on the more controversial fields…”
The first essay (by Eigen, Gardiner, Schuster, and Winkler-Oswatitsch) states, “The primitive soup did face an energy crisis: early life forms needed somehow to extract chemical energy from the molecules in the soup. For the story we have to tell here it is not important how they did so; some system of energy storage and delivery based on phosphates can be assumed…” (Pg. 12)
Smith explains in an introduction, “Perhaps the most difficult step to explain in the origin of life is that from the replication of molecules (RNA for example) in the absence of specific proteins, to the appearance of polymerases and other proteins involved in the replication of RNA… one cannot have accurate replication without a length of RNA of, say, 2,000 or more base pairs, and one cannot have that much RNA without accurate replication. This is the central problem discussed in [the following papers].” (Pg. 34)
Doolittle and Sapienza wrote, “It is inevitable that natural selection … will favor the development within genomes of DNAs whose only ‘function’ is survival within genomes. When a given DNA, or class of DNAs, of unproven phenotypic function can be shown to have evolved a strategy (such as transposition) which ensures its genomic survival, then no other explanation for its existence is necessary. The search for other explanations may prove, if not intellectually sterile, ultimately futile.” (Pg. 64)
Leslie Orgel and Francis Crick state, “In summary… there is a large amount of evidence which suggests, but does not prove, that much DNA in higher organisms is little better than junk. We shall assume, for the rest of this article, that this hypothesis is true. We therefore need to explain how such DNA arose in the first place any why it is not speedily eliminated, since, by definition, it contributes little or nothing to the fitness of the organism.” (Pg. 68)
Jeffries observes, “This apparently rapid rate of pseudogene divergence is consistent with the notion that these sequences are junk and free from selective constraint.” (Pg. 86)
Stephen Jay Gould recounts, “I well remember how the synthetic theory beguiled me with its unifying power when I was a graduate student… Since then I have been watching it slowly unravel as a universal description of evolution. The molecular assault came first, followed quickly by renewed attention to unorthodox theories of speciation and by challenges at the level of macroevolution itself. I have been reluctant to admit it… but if [Ernst] Mayr’s characterization of the synthetic theory is accurate, then that theory, as a general proposition, is effectively dead, despite its persistence as textbook orthodoxy.” (Pg. 131)
He argues, “in saltational, chromosomal speciation, reproductive isolation comes first and cannot be considered as an adaptation at all. It is a stochastic event that establishes a species by the technical definition of reproductive isolation. To be sure, the later success of this species in competition may depend upon its subsequent acquisition of adaptation, but the origin itself may be non-adaptive. We can, in fact, reverse the conventional view and argue that speciation, by forming new entities stochastically, provides raw material for selection… Speciation, [Richard] Goldschmidt argues, occurs at different rates and uses different kinds of genetic variation… his explicit anti-extrapolationist statement is the epitome and foundation of emerging views on speciation… There is a discontinuity in cause and explanation between adaptation in local populations and speciation; they represent two distinct, though interacting, views of evolution.” (Pg. 136-137)
He continues, “[Niles] Eldredge and I have argued that imperfections in the [fossil] record cannot explain all discontinuity (and certainly not stasis). We regard stasis and discontinuity as an expression of how evolution works… Thus, our model of ‘punctuated equilibria’ holds that evolution is concentrated in events of speciation and that the successful speciation is an infrequent event punctuating the statis of large populations that do not alter in fundamental ways during the millions of years that they endure.” (Pg. 138)
He goes on, “I do not doubt the supreme importance of preadaptation, but the other alternative… now deserves a rehearing in the light of renewed interest in development: perhaps, in many cases, the intermediates never existed. I do not refer to the saltational origin of entire new designs, complete in all their complex and integrated features---a fantasy that would be truly anti-Darwinian in denying any creativity to selection… Instead, I envisage a potential saltational origin for the essential features of key adaptations. Why may we not imagine that gill arch bones of an ancestral agnathan moved forward in one step to surround the mouth and form proto-jaws?...” (Pg. 140)
Russell Lande notes, “Mutations of large effect are almost always deleterious due either to their main effect or to pleiotropic side effects… In contrast, simultaneous changes in the frequencies of many genes with small pleiotropic effects allow loci with compensatory action to minimize the expression of deleterious traits in evolution.” (Pg. 148) He continues, “Advocates of punctuated equilibrium and macromutation cite as evidence the frequent absence of transitional forms from the fossil record… This negative information is not convincing, especially in view of the claim that morphological evolution typically occurs in geographically restricted populations, which are unlikely to be fossilized and discovered. Gaps between fossil or living taxa do not imply that the forms evolved rapidly… or that macromutations were involved… Even supergenes controlling major color polymorphisms probably originated by the accumulation of linked and unlinked modifiers.” (Pg. 149)
P.G. Williamson observes, “Events during the radiation of several lineages in the Lower Member of the Koobi Fora are typical of the fossil record in that intermediates between the derivative and ancestral taxa are not documented. However, events as the Suregei tuff and Guomde levels are significant in that they provide, for the first time, details of allopatric speciation during the ‘punctuation’ of cladogenesis; they allow an unprecedented resolution of the fine structure of events during speciation.” (Pg. 164)
J.S. Jones says, "In the 13 lineages common enough for detailed analysis, long periods of morphological stability are interrupted by fossil beds in which relatively rapid changes in shell shape take place… This apparent ability of an asexual species to evolve as rapidly as its sexual relatives casts some doubt on the many theories which claim that sexual reproduction increases evolutionary flexibility… Reproductive isolation, the central element of speciation, can also be achieved by simple Darwinian selection in a period much shorter than that assessed by Williamson and others as evidence for the inadequacy of Darwinian theory… Once evolutionary change in the fossil record… is placed in the context of the known ability of living organisms to respond to the forces of classical Darwinian natural selection, it becomes clear that it is not necessary to invoke evolutionary forces ‘qualitatively different’ from those emphasized by Darwin.” (Pg. 167, 169)
Williamson answers Jones, “The principal problem is morphological stasis. A theory is only as good as its prediction, and conventional neo-Darwinism, which claims to be a comprehensive explanation of evolutionary process, has failed to predict the widespread long-term morphological status now recognized as one of the most striking aspects of the fossil record. The long-term morphological stasis noted by punctuationists in the fossil record is clearly mirrored by the relative morphological uniformity of most widely distributed modern species.” (Pg. 172)
More than 40 years after this book was published, there have certainly been subsequent developments in evolutionary theory; e.g., so-called ‘junk’ DNA is increasingly being found to have a legitimate purpose (e.g., controlling the rates of development). But this collection will still be of keen interest to those studying evolutionary theory.
This 1982 book of essays was published in cooperation with the editorial staff of the journal ‘Nature.’ Editor John Maynard Smith provides an introductory commentary to each of the essays.
Smith wrote in the Introduction, “In recent years there have been claims---in the daily press, on television, and by retired cosmologists---that Darwin may have got it wrong… Darwin has indeed been criticized by scientists working in a variety of fields…The most controversial of these issues are debated in this book… This volume presents some current controversies and recent advances in evolutionary biology. But let me… first give a brief history of evolutionary ideas since Darwin. In the ‘Origin of Species,’ Darwin… argued that evolution had in fact happened… [and] that the main cause of evolutionary change was… natural selection… The next important step was the rediscovery of Mendel’s laws… and the formulation of the chromosome theory of heredity… The work of the population geneticists prepared the way for the ‘modern synthesis’… Since 1950, developments in molecular biology have had a growing influence… There is, however, one area of molecular biology which seems to me to lag behind the rest. This is the study of the evolution of prokaryotes (organisms … lacking a proper cell nucleus)… The papers printed below … have concentrated on the more controversial fields…”
The first essay (by Eigen, Gardiner, Schuster, and Winkler-Oswatitsch) states, “The primitive soup did face an energy crisis: early life forms needed somehow to extract chemical energy from the molecules in the soup. For the story we have to tell here it is not important how they did so; some system of energy storage and delivery based on phosphates can be assumed…” (Pg. 12)
Smith explains in an introduction, “Perhaps the most difficult step to explain in the origin of life is that from the replication of molecules (RNA for example) in the absence of specific proteins, to the appearance of polymerases and other proteins involved in the replication of RNA… one cannot have accurate replication without a length of RNA of, say, 2,000 or more base pairs, and one cannot have that much RNA without accurate replication. This is the central problem discussed in [the following papers].” (Pg. 34)
Doolittle and Sapienza wrote, “It is inevitable that natural selection … will favor the development within genomes of DNAs whose only ‘function’ is survival within genomes. When a given DNA, or class of DNAs, of unproven phenotypic function can be shown to have evolved a strategy (such as transposition) which ensures its genomic survival, then no other explanation for its existence is necessary. The search for other explanations may prove, if not intellectually sterile, ultimately futile.” (Pg. 64)
Leslie Orgel and Francis Crick state, “In summary… there is a large amount of evidence which suggests, but does not prove, that much DNA in higher organisms is little better than junk. We shall assume, for the rest of this article, that this hypothesis is true. We therefore need to explain how such DNA arose in the first place any why it is not speedily eliminated, since, by definition, it contributes little or nothing to the fitness of the organism.” (Pg. 68)
Jeffries observes, “This apparently rapid rate of pseudogene divergence is consistent with the notion that these sequences are junk and free from selective constraint.” (Pg. 86)
Stephen Jay Gould recounts, “I well remember how the synthetic theory beguiled me with its unifying power when I was a graduate student… Since then I have been watching it slowly unravel as a universal description of evolution. The molecular assault came first, followed quickly by renewed attention to unorthodox theories of speciation and by challenges at the level of macroevolution itself. I have been reluctant to admit it… but if [Ernst] Mayr’s characterization of the synthetic theory is accurate, then that theory, as a general proposition, is effectively dead, despite its persistence as textbook orthodoxy.” (Pg. 131)
He argues, “in saltational, chromosomal speciation, reproductive isolation comes first and cannot be considered as an adaptation at all. It is a stochastic event that establishes a species by the technical definition of reproductive isolation. To be sure, the later success of this species in competition may depend upon its subsequent acquisition of adaptation, but the origin itself may be non-adaptive. We can, in fact, reverse the conventional view and argue that speciation, by forming new entities stochastically, provides raw material for selection… Speciation, [Richard] Goldschmidt argues, occurs at different rates and uses different kinds of genetic variation… his explicit anti-extrapolationist statement is the epitome and foundation of emerging views on speciation… There is a discontinuity in cause and explanation between adaptation in local populations and speciation; they represent two distinct, though interacting, views of evolution.” (Pg. 136-137)
He continues, “[Niles] Eldredge and I have argued that imperfections in the [fossil] record cannot explain all discontinuity (and certainly not stasis). We regard stasis and discontinuity as an expression of how evolution works… Thus, our model of ‘punctuated equilibria’ holds that evolution is concentrated in events of speciation and that the successful speciation is an infrequent event punctuating the statis of large populations that do not alter in fundamental ways during the millions of years that they endure.” (Pg. 138)
He goes on, “I do not doubt the supreme importance of preadaptation, but the other alternative… now deserves a rehearing in the light of renewed interest in development: perhaps, in many cases, the intermediates never existed. I do not refer to the saltational origin of entire new designs, complete in all their complex and integrated features---a fantasy that would be truly anti-Darwinian in denying any creativity to selection… Instead, I envisage a potential saltational origin for the essential features of key adaptations. Why may we not imagine that gill arch bones of an ancestral agnathan moved forward in one step to surround the mouth and form proto-jaws?...” (Pg. 140)
Russell Lande notes, “Mutations of large effect are almost always deleterious due either to their main effect or to pleiotropic side effects… In contrast, simultaneous changes in the frequencies of many genes with small pleiotropic effects allow loci with compensatory action to minimize the expression of deleterious traits in evolution.” (Pg. 148) He continues, “Advocates of punctuated equilibrium and macromutation cite as evidence the frequent absence of transitional forms from the fossil record… This negative information is not convincing, especially in view of the claim that morphological evolution typically occurs in geographically restricted populations, which are unlikely to be fossilized and discovered. Gaps between fossil or living taxa do not imply that the forms evolved rapidly… or that macromutations were involved… Even supergenes controlling major color polymorphisms probably originated by the accumulation of linked and unlinked modifiers.” (Pg. 149)
P.G. Williamson observes, “Events during the radiation of several lineages in the Lower Member of the Koobi Fora are typical of the fossil record in that intermediates between the derivative and ancestral taxa are not documented. However, events as the Suregei tuff and Guomde levels are significant in that they provide, for the first time, details of allopatric speciation during the ‘punctuation’ of cladogenesis; they allow an unprecedented resolution of the fine structure of events during speciation.” (Pg. 164)
J.S. Jones says, "In the 13 lineages common enough for detailed analysis, long periods of morphological stability are interrupted by fossil beds in which relatively rapid changes in shell shape take place… This apparent ability of an asexual species to evolve as rapidly as its sexual relatives casts some doubt on the many theories which claim that sexual reproduction increases evolutionary flexibility… Reproductive isolation, the central element of speciation, can also be achieved by simple Darwinian selection in a period much shorter than that assessed by Williamson and others as evidence for the inadequacy of Darwinian theory… Once evolutionary change in the fossil record… is placed in the context of the known ability of living organisms to respond to the forces of classical Darwinian natural selection, it becomes clear that it is not necessary to invoke evolutionary forces ‘qualitatively different’ from those emphasized by Darwin.” (Pg. 167, 169)
Williamson answers Jones, “The principal problem is morphological stasis. A theory is only as good as its prediction, and conventional neo-Darwinism, which claims to be a comprehensive explanation of evolutionary process, has failed to predict the widespread long-term morphological status now recognized as one of the most striking aspects of the fossil record. The long-term morphological stasis noted by punctuationists in the fossil record is clearly mirrored by the relative morphological uniformity of most widely distributed modern species.” (Pg. 172)
More than 40 years after this book was published, there have certainly been subsequent developments in evolutionary theory; e.g., so-called ‘junk’ DNA is increasingly being found to have a legitimate purpose (e.g., controlling the rates of development). But this collection will still be of keen interest to those studying evolutionary theory.
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