The Modern Synthesis

Author(s):  
Vassiliki Betty Smocovitis

The “modern synthesis” generally refers to the early to mid-century formulation of evolutionary theory that reconciled classical Darwinian selection theory with a newer population-oriented view of Mendelian genetics that attempted to explain the origin of biological diversity. It draws on the title of zoologist Julian S. Huxley’s book of 1943 titled Evolution: The Modern Synthesis, a semi-popular account of evolution that ushered in this “modern” synthetic view of evolution. Covering an interval of time approximately between 1920–1950, it also refers to developments in understanding evolution that drew on a range of disciplines that were synthesized or brought to consensus that generally include systematics, paleontology, and botany with a populational view of evolutionary genetics. Whether or not it served to unify the study of evolution, or to unify the disparate biological sciences—and whether or not it led to the emergence of a science of evolutionary biology, as some of its proponents have claimed—remains a topic for discussion. Though they do not refer to precisely the same things or share identical meanings, the phrase “modern synthesis” has overlapped with terms such as the “evolutionary synthesis,” coined and used especially by Ernst Mayr and William B. Provine, to refer to the historical event, as well as terms such as Neo-Darwinian theory or Neo-Darwinism (though criticism has been made regarding the latter term’s applicability to the mid-century developments in evolutionary theory). As Ernst Mayr noted, the term “Neo-Darwinism” was first coined and used by George John Romanes in 1895 to refer to a revision of Charles Darwin’s theory first formulated in 1859, which included Lamarckian inheritance. The extent to which the modern synthesis, and the evolutionary synthesis map with what is also called the synthetic theory, is open for discussion as is specific understanding of the term. For the most part, there is little in the way of consensus or agreement by scientists, philosophers, and historians as to what “the synthesis” (the abbreviated reference) precisely means, and what (if anything) specifically occurred of a general nature in studies of evolution, broadly construed, in the interval of time between 1920–1950.

2003 ◽  
Vol 30 (1) ◽  
pp. 85-96 ◽  
Author(s):  
Kim Kleinman

On at least four occasions, Edgar Anderson (1897–1969) began revising his book Plants, man and life (1952). Given both its place in Anderson's career and his place in the development of evolutionary theory in the mid-twentieth century, the emendations are noteworthy. Though a popular work, Plants, man and life served as the distillation of Anderson's ideas on hybridization as an evolutionary mechanism, the need for more scientific attention on domesticated and semi-domesticated plants, and the opportunities such plants provided for the study of evolution. Anderson was an active participant in several key events in what historians have come to call the Evolutionary Synthesis. For example, he and Ernst Mayr shared the 1941 Jesup Lectures on “Systematics and the origin of species”. Anderson's proposed revisions to his book reflect both an attempt to soften certain acerbic comments as well as an attempt to recast the book as a whole.


2017 ◽  
Vol 7 (5) ◽  
pp. 20160145 ◽  
Author(s):  
Douglas J. Futuyma

Evolutionary theory has been extended almost continually since the evolutionary synthesis (ES), but except for the much greater importance afforded genetic drift, the principal tenets of the ES have been strongly supported. Adaptations are attributable to the sorting of genetic variation by natural selection, which remains the only known cause of increase in fitness. Mutations are not adaptively directed, but as principal authors of the ES recognized, the material (structural) bases of biochemistry and development affect the variety of phenotypic variations that arise by mutation and recombination. Against this historical background, I analyse major propositions in the movement for an ‘extended evolutionary synthesis’. ‘Niche construction' is a new label for a wide variety of well-known phenomena, many of which have been extensively studied, but (as with every topic in evolutionary biology) some aspects may have been understudied. There is no reason to consider it a neglected ‘process’ of evolution. The proposition that phenotypic plasticity may engender new adaptive phenotypes that are later genetically assimilated or accommodated is theoretically plausible; it may be most likely when the new phenotype is not truly novel, but is instead a slight extension of a reaction norm already shaped by natural selection in similar environments. However, evolution in new environments often compensates for maladaptive plastic phenotypic responses. The union of population genetic theory with mechanistic understanding of developmental processes enables more complete understanding by joining ultimate and proximate causation; but the latter does not replace or invalidate the former. Newly discovered molecular phenomena have been easily accommodated in the past by elaborating orthodox evolutionary theory, and it appears that the same holds today for phenomena such as epigenetic inheritance. In several of these areas, empirical evidence is needed to evaluate enthusiastic speculation. Evolutionary theory will continue to be extended, but there is no sign that it requires emendation.


Author(s):  
Alexander Vucinich

The Russian scientific community welcomed Darwin’s evolutionary theory and made it a basis of research in a wide range of biological sciences. Russian evolutionary studies in embryology, paleontology, microbiology and pathology attracted international attention. The vast scope of Darwin’s popularity in Russia was dramatically manifested in 1909, on the occasion of the national celebration of the 100th anniversary of the birth of the great English scientist and the 50th anniversary of the publication of The Origin of Species. All universities, naturalist societies, and many newspapers and popular journals took part in the celebration, which produced a hundred praiseful publications on Darwinian themes. University philosophers, steeped in metaphysical idealism and spiritualism, linked Darwinism to what they called ‘modern scientific materialism’ and rejected it wholly. They were strongly predisposed to welcome modern revivals of metaphysical vitalism. Freelance philosophers, usually associated with heterodox ideological movements and influenced by Auguste Comte’s positivism or various modern neopositivist and Neo-Kantian currents, credited Darwinism with making science a major topic of modern philosophy. A new discipline, known as ‘scientific philosophy’, rapidly developing in the West, made its first appearance in Russia. In the Soviet Union, Darwin’s evolutionary theory followed a course of cataclysmic ruptures. During the 1920s, Soviet scientists made significant contributions to the study of the role of the genetic environment in biological evolution and helped set the stage for an evolutionary synthesis of Darwinism and genetics. The Stalinist era (1929–53) marked a drastic departure from the prevalent currents in evolutionary biology. It was dominated by the rise of Lysenkoism, a pseudo-science identified as ‘creative Darwinism’, and was guided by a diluted version of the Lamarckian idea of evolution as a product of the inheritance of acquired characteristics. Lysenkoism rejected the Darwinian conception of natural selection, downgraded the role of physico-chemical analysis in biology, and paid no attention to molecular biology. In 1948 Lysenkoism was officially recognized as the Marxist theory of evolution. Under Lysenko’s influence, genetics was proclaimed a ‘bourgeois science’ and was made illegal. The downfall of Lysenkoism in 1964 brought the re-establishment of genetics, a full-scale return to true Darwinism, and a re-intensified interest in ‘evolutionary synthesis’.


2019 ◽  
Author(s):  
Victor A. Meszaros ◽  
Miles D. Miller-Dickson ◽  
C. Brandon Ogbunugafor

In silicoapproaches have served a central role in the development of evolutionary theory for generations. This especially applies to the concept of the fitness landscape, one of the most important abstractions in evolutionary genetics, and one which has benefited from the presence of large empirical data sets only in the last decade or so. In this study, we propose a method that allows us to generate enormous data sets that walk the line betweenin silicoand empirical: word usage frequencies as catalogued by the Google ngram corpora. These data can be codified or analogized in terms of a multidimensional empirical fitness landscape towards the examination of advanced concepts—adaptive landscape by environment interactions, clonal competition, higher-order epistasis and countless others. We argue that the greaterLexical Landscapesapproach can serve as a platform that offers an astronomical number of fitness landscapes for exploration (at least) or theoretical formalism (potentially) in evolutionary biology.


Author(s):  
Anya Plutynski

Huxley coined the phrase, the ‘modern synthesis’ to refer to the acceptance by a vast majority of biologists in the mid-twentieth century of a ‘synthetic’ view of evolution. According to its main chroniclers, Mayr and Provine, the ‘synthesis’ consisted in the acceptance of natural selection acting on minor hereditary variation as the primary cause of both adaptive change within populations and major changes, such as speciation, and the evolution of higher taxa (e.g. families and genera). However, the dating and substance of the synthesis is controversial. The evolutionary synthesis may be broken down into two periods, the ‘early’ synthesis from 1918 to 1932, and the later, ‘modern synthesis’ from 1936 to 1947. The authors most commonly associated with the early synthesis are J. B. S. Haldane, R. A. Fisher, and S. Wright. These three authored a number of important advances; first, they demonstrated the compatibility of a Mendelian theory of inheritance with the results of Biometry, a study of the correlations of measures of traits between relatives. Second, they developed the theoretical framework for evolutionary biology, classical population genetics. This is a family of mathematical models representing evolution as change in genotype frequencies, from one generation to the next, as a product of selection, mutation, migration, and drift, or chance. Third, there was a broader synthesis of population genetics with cytology (cell biology), genetics, and biochemistry, as well as both empirical and mathematical demonstrations to the effect that very small selective forces acting over a relatively long time were able to generate substantial evolutionary change. The later ‘modern’ synthesis is most often identified with the work of Mayr, Dobzhansky and Simpson. There was a major institutional change in biology at this stage, insofar as different subdisciplines formerly housed in different departments, and using different methods, were united under the institutional umbrella of ‘evolutionary biology’. Mayr played an important role as a community architect, in founding the Society for the Study of Evolution, and the journal Evolution, which drew together work in systematics, biogeography, paleontology, and theoretical population genetics. The synthesis presents an occasion for addressing a number of important philosophical questions about the nature of theories, explanation, progress in science, theory unification, and reduction.


2001 ◽  
Vol 73 (3) ◽  
pp. 385-395 ◽  
Author(s):  
JEAN R. DAVID

Developmental biology and evolutionary biology are both mature integrative disciplines which started in the 19th century and then followed parallel and independent scientific pathways. Recently, a genetical component has stepped into both disciplines (developmental genetics and evolutionary genetics) pointing out the need for future convergent maturation. Indeed, the Evo-Devo approach is becoming popular among developmental biologists, based on the facts that distant groups share a common ancestry, that precise phylogenies can be worked out and that homologous genes often play similar roles during the development of very different organisms. In this essay, I try to show that the real future of Evo-Devo thinking is still broader. The evolutionary theory is a set of diverse concepts which can and should be used in any biological field. Evolutionary thinking trains to ask « why » questions and to provide logical and plausible answers. It can shed some light on a diversity of general problems such as how to distinguish homologies from analogies, the costs and benefits of multicellularity, the origin of novel structures (e.g. the head), or the evolution of sexual reproduction. In the next decade, we may expect a progressive convergence between developmental genetics and quantitative genetics.


Author(s):  
Gunter Wagner ◽  
Gary Tomlinson

Since its inception, evolutionary theory has experienced a number of extensions. The most important of these took the forms of the Modern Evolutionary Synthesis (MES), embracing genetics and population biology in the early 20th century, and the Extended Evolutionary Synthesis (EES) of the last thirty years, embracing, among other factors, non-genetic forms of inheritance. While we appreciate the motivation for this recent extension, we argue that it does not go far enough, since it restricts itself to widening explanations of adaptation by adding mechanisms of inheritance and variation. Here we argue that a more thoroughgoing extension is needed, one that broadens the explanatory scope of evolutionary theory. In addition to adaptation and its various mechanisms, evolutionary theory must recognize as a distinct intellectual challenge the origin of what we call “historical kinds.” Under historical kinds we include any process that acquires a quasi-independent and traceable lineage-history in biological and cultural evolution. A limited number of historical kinds have been recognized in evolutionary biology, and corresponding research programs have been formed around them. The best characterized examples are biological species and genes. We propose that the conceptual category of historical kinds can and needs to be extended, and we develop the notion of a historical kind in a series of paradigmatic exemplars, from genes and cell types to rituals and music. The explanation of the origin of historical kinds should be a main objective of biological and cultural sciences.


2015 ◽  
Vol 282 (1813) ◽  
pp. 20151019 ◽  
Author(s):  
Kevin N. Laland ◽  
Tobias Uller ◽  
Marcus W. Feldman ◽  
Kim Sterelny ◽  
Gerd B. Müller ◽  
...  

Scientific activities take place within the structured sets of ideas and assumptions that define a field and its practices. The conceptual framework of evolutionary biology emerged with the Modern Synthesis in the early twentieth century and has since expanded into a highly successful research program to explore the processes of diversification and adaptation. Nonetheless, the ability of that framework satisfactorily to accommodate the rapid advances in developmental biology, genomics and ecology has been questioned. We review some of these arguments, focusing on literatures (evo-devo, developmental plasticity, inclusive inheritance and niche construction) whose implications for evolution can be interpreted in two ways—one that preserves the internal structure of contemporary evolutionary theory and one that points towards an alternative conceptual framework. The latter, which we label the ‘extended evolutionary synthesis' (EES), retains the fundaments of evolutionary theory, but differs in its emphasis on the role of constructive processes in development and evolution, and reciprocal portrayals of causation. In the EES, developmental processes, operating through developmental bias, inclusive inheritance and niche construction, share responsibility for the direction and rate of evolution, the origin of character variation and organism–environment complementarity. We spell out the structure, core assumptions and novel predictions of the EES, and show how it can be deployed to stimulate and advance research in those fields that study or use evolutionary biology.


2019 ◽  
Vol 59 (3) ◽  
pp. 493-502 ◽  
Author(s):  
Mark E Olson

AbstractPlant ecology is increasingly turning to evolutionary questions, just as evolutionary biology pushes out of the strictures of the Modern Synthesis into what some regard as an “Extended Evolutionary Synthesis.” As plant ecology becomes increasingly evolutionary, it is essential to ask how aspects of the Extended Synthesis might impinge on plant ecological theory and practice. I examine the contribution of plant evolutionary ecology to niche construction theory, as well as the potential for developmental systems theory and genes-as-followers adaptive evolution, all important post-Modern Synthesis themes, in providing novel perspectives for plant evolutionary ecology. I also examine ways that overcoming dichotomies such as “genetic vs. plastic” and “constraint vs. adaptation” provide fertile opportunities for plant evolutionary ecologists. Along the same lines, outgrowing vague concepts such as “stress” and replacing them with more precise terminology in all cases provides vastly increased causal clarity. As a result, the synthetic path that plant ecologists are blazing, becoming more evolutionary every year, bodes extremely well for the field, with vast potential for expansion into important scientific territory.


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