Developmental biology is the study of the process by which animals and plants grow and develop. Developmental biology also encompasses the biology of regeneration, asexual reproduction, metamorphosis, and the growth and differentiation of stem cells in the adult organism.
Introduction
Developmental biology
Developmental biology | Introduction
It is the study of the process by which animals and plants grow and develop. It is the study of the process by which animals and plants grow and develop. It  is the study of the process by which animals and plants grow and develop. It is the study of the process by which animals and plants grow and develop.
which of the following is the ultimate result of evolution
user
Sorry. I cannot find the answer based on the context.
assistant
what is evolution?
user
It is change in the heritable characteristics of biological populations over successive generations.
assistant
who was the first to study this?
user
Charles Darwin and Alfred Russel Wallace
assistant
when was the first one born?
user
Shrewsbury, Shropshire
assistant
did he suffer from any illness?
user
He had "an uncomfortable palpitation of the heart".
assistant
did he publish anything?
user
Yes, his theory of evolution with compelling evidence in his 1859 book "On the Origin of Species".
assistant
what does modern synthesis state about evolution?
user
It explained patterns observed across species in populations, through fossil transitions in palaeontology, and complex cellular mechanisms in developmental biology.
assistant
what is the last type of biology about?
user
In the 1920s and 1930s the so-called modern synthesis connected natural selection and population genetics, based on Mendelian inheritance, into a unified theory that applied generally to any branch of biology. The modern synthesis explained patterns observed across species in populations, through fossil transitions in palaeontology, and complex cellular mechanisms in developmental biology. The publication of the structure of DNA by James Watson and Francis Crick with contribution of Rosalind Franklin in 1953 demonstrated a physical mechanism for inheritance. Molecular biology improved understanding of the relationship between genotype and phenotype. Advancements were also made in phylogenetic systematics, mapping the transition of traits into a comparative and testable framework through the publication and use of evolutionary trees.
Evolution | The 'modern synthesis'
In the 1980s, developmental biology re-entered evolutionary biology from its initial exclusion from the modern synthesis through the study of evolutionary developmental biology. Related fields often considered part of evolutionary biology are phylogenetics, systematics, and taxonomy.
Zoology | Evolutionary
These have included such diverse fields as the study of society, developmental biology, epigenetics, molecular biology, microbiology, genomics, symbiogenesis, and horizontal gene transfer. The physiologist Denis Noble argues that these additions render neo-Darwinism in the sense of the early 20th century's modern synthesis "at the least, incomplete as a theory of evolution", and one that has been falsified by later biological research. Michael Rose and Todd Oakley note that evolutionary biology, formerly divided and "Balkanized", has been brought together by genomics. It has in their view discarded at least five common assumptions from the modern synthesis, namely that the genome is always a well-organised set of genes; that each gene has a single function; that species are well adapted biochemically to their ecological niches; that species are the durable units of evolution, and all levels from organism to organ, cell and molecule within the species are characteristic of it; and that the design of every organism and cell is efficient.
Modern synthesis (20th century) | Later syntheses
Modern synthesis or modern evolutionary synthesis refers to several perspectives on evolutionary biology, namely:
Modern synthesis | Introduction
In the so-called modern synthesis of the early 20th century, Ronald Fisher brought together Darwin's theory of evolution, with its insistence on natural selection, heredity, and variation, and Gregor Mendel's laws of genetics into a coherent structure for evolutionary biology. Biologists assumed that an organism was a straightforward reflection of its component genes: the genes coded for proteins, which built the organism's body. Biochemical pathways (and, they supposed, new species) evolved through mutations in these genes. It was a simple, clear and nearly comprehensive picture: but it did not explain embryology. The evolutionary embryologist Gavin de Beer anticipated evolutionary developmental biology in his 1930 book "Embryos and Ancestors", by showing that evolution could occur by heterochrony, such as in the retention of juvenile features in the adult.
Evolutionary developmental biology | The modern synthesis of the early 20th century
This, de Beer argued, could cause apparently sudden changes in the fossil record, since embryos fossilise poorly. As the gaps in the fossil record had been used as an argument against Darwin's gradualist evolution, de Beer's explanation supported the Darwinian position. However, despite de Beer, the modern synthesis largely ignored embryonic development to explain the form of organisms, since population genetics appeared to be an adequate explanation of how forms evolved.
Evolutionary developmental biology | The modern synthesis of the early 20th century
Some researchers in the field of evolutionary developmental biology proposed another synthesis. They argue that the modern and extended syntheses should mostly center on genes and suggest an integration of embryology with molecular genetics and evolution, aiming to understand how natural selection operates on gene regulation and deep homologies between organisms at the level of highly conserved genes, transcription factors and signalling pathways. By contrast, a different strand of evo-devo following an organismal approach contributes to the extended synthesis by emphasizing (amongst others) developmental bias (both through facilitation and constraint), evolvability, and inherency of form as primary factors in the evolution of complex structures and phenotypic novelties.
Extended evolutionary synthesis | Contributions from evolutionary developmental biology
They argue that the "new biology" integrates genomics, bioinformatics, and evolutionary genetics into a general-purpose toolkit for a "Postmodern Synthesis".
Modern synthesis (20th century) | Later syntheses
Since then, the modern synthesis has been further extended to explain biological phenomena across the full and integrative scale of the biological hierarchy, from genes to species. One extension, known as evolutionary developmental biology and informally called "evo-devo," emphasises how changes between generations (evolution) acts on patterns of change within individual organisms (development). Since the beginning of the 21st century and in light of discoveries made in recent decades, some biologists have argued for an extended evolutionary synthesis, which would account for the effects of non-genetic inheritance modes, such as epigenetics, parental effects, ecological inheritance and cultural inheritance, and evolvability.
Evolution | Further syntheses
Evolutionary biology is the subfield of biology that studies the evolutionary processes (natural selection, common descent, speciation) that produced the diversity of life on Earth. In the 1930s, the discipline of evolutionary biology emerged through what Julian Huxley called the modern synthesis of understanding, from previously unrelated fields of biological research, such as genetics and ecology, systematics and paleontology. The investigational range of current research widened to encompass the genetic architecture of adaptation, molecular evolution, and the different forces that contribute to evolution, such as sexual selection, genetic drift, and biogeography. Moreover, the newer field of evolutionary developmental biology ("evo-devo") investigates how embryogenesis, the development of the embryo, is controlled, thus yielding a wider synthesis that integrates developmental biology with the fields of study covered by the earlier evolutionary synthesis.
Evolutionary biology | Introduction
In 1982, a historical note on a series of evolutionary biology books could state without qualification that evolution is the central organizing principle of biology. Smocovitis commented on this that "What the architects of the synthesis had worked to construct had by 1982 become a matter of fact", adding in a footnote that "the centrality of evolution had thus been rendered tacit knowledge, part of the received wisdom of the profession". By the late 20th century, however, the modern synthesis was showing its age, and fresh syntheses to remedy its defects and fill in its gaps were proposed from different directions.
Modern synthesis (20th century) | Later syntheses
Mayr, on the basis of an understanding of genes and direct observations of evolutionary processes from field research, introduced the biological species concept, which defined a species as a group of interbreeding or potentially interbreeding populations that are reproductively isolated from all other populations. Both Dobzhansky and Mayr emphasised the importance of subspecies reproductively isolated by geographical barriers in the emergence of new species. The palaeontologist George Gaylord Simpson helped to incorporate palaeontology with a statistical analysis of the fossil record that showed a pattern consistent with the branching and non-directional pathway of evolution of organisms predicted by the modern synthesis.
Introduction to evolution | Modern synthesis
In the view of the evolutionary biologist Eugene Koonin in 2009, the modern synthesis will be replaced by a 'post-modern' synthesis that will include revolutionary changes in molecular biology, the study of prokaryotes and the resulting tree of life, and genomics.
Modern synthesis (20th century) | Introduction
The traditional view is that developmental biology played little part in the modern synthesis, but in his 1930 book "Embryos and Ancestors", the evolutionary embryologist Gavin de Beer anticipated evolutionary developmental biology by showing that evolution could occur by heterochrony, such as in the retention of juvenile features in the adult. This, de Beer argued, could cause apparently sudden changes in the fossil record, since embryos fossilise poorly. As the gaps in the fossil record had been used as an argument against Darwin's gradualist evolution, de Beer's explanation supported the Darwinian position. However, despite de Beer, the modern synthesis largely ignored embryonic development to explain the form of organisms, since population genetics appeared to be an adequate explanation of how forms evolved.
Modern synthesis (20th century) | De Beer's embryology, 1930
Biologists, alongside scholars of the history and philosophy of biology, have continued to debate the need for, and possible nature of, a replacement synthesis. For example, in 2017 Philippe Huneman and Denis M. Walsh stated in their book "Challenging the Modern Synthesis" that numerous theorists had pointed out that the disciplines of embryological developmental theory, morphology, and ecology had been omitted. They noted that all such arguments amounted to a continuing desire to replace the modern synthesis with one that united "all biological fields of research related to evolution, adaptation, and diversity in a single theoretical frame." They observed further that there are two groups of challenges to the way the modern synthesis viewed inheritance.
Modern synthesis (20th century) | Towards a replacement synthesis
After the synthesis, evolutionary biology continued to develop with major contributions from workers including W. D. Hamilton, George C. Williams, E. O. Wilson, Edward B. Lewis and others.
Modern synthesis (20th century) | After the synthesis
Lamm notes, too, that Huxley anticipated evolutionary developmental biology's attention to embryonic development for understanding evolution. Finally, the review observes that "It has long been debated whether the so-called Modern Synthesis was overall a positive force in biology, or whether its lacunae [gaps] undermine its contributions" and notes that people (such as Massimo Pigliucci) have called for a renewed synthesis, though biologists differ about its direction.
Evolution: The Modern Synthesis | Modern
Brian Hall traces the roots of evolutionary developmental biology in his 2012 paper on its past present and future. He begins with Darwinian evolution and Mendel's genetics, noting the tendency of the followers of both men in the early 20th century to follow separate paths and to set aside and ignore apparently inexplicable problems. Greater understanding of genotypic and phenotypic structures from the 1940s enabled the unification of evolution and genetics in the modern synthesis. Molecular biology then enabled researchers to explore the mechanisms and evolution of embryonic development in molecular detail, including in humans.
Human evolutionary developmental biology | History
Modern evolutionary biology has terminology suggesting both continuous change, such as genetic drift, and discontinuous variation, such as mutation. However, as the basic structure of DNA is discrete, nature is now widely understood to make jumps at the biological level, if only on a very small scale.
Natura non facit saltus | Overview
Ledyard Stebbins. The emerging synthesis was called the evolutionary synthesis by Julian Huxley in his book, "". In 1947, a diverse collection of biologists met at a symposium in Princeton and declared their acceptance of this synthesis. However, it was not yet complete. Developmental biologists did not accept that the theory explained their observations, and it was not until the 1970s and 1980s that molecular biology bridged the gap. Also, for decades there was disagreement over whether the unit of selection was the gene or the individual as a whole. In 1974 all the living founders of the modern synthesis (with the exception of Simpson and Bernhard Rensch) met with historians of biology in a conference to evaluate their work.
Genetics and the Origin of Species | Historical impact
In the 1944 book "Tempo and Mode in Evolution", George Gaylord Simpson showed that the fossil record was consistent with the irregular non-directional pattern predicted by the developing evolutionary synthesis, and that the linear trends that earlier paleontologists had claimed supported orthogenesis and neo-Lamarckism did not hold up to closer examination. In 1950, G. Ledyard Stebbins published "Variation and Evolution in Plants", which helped to integrate botany into the synthesis. The emerging cross-disciplinary consensus on the workings of evolution would be known as the modern synthesis. It received its name from the 1942 book "" by Julian Huxley.
History of evolutionary thought | The modern synthesis
The idea of evolution by natural selection was proposed by Charles Darwin in 1859, but evolutionary biology, as an academic discipline in its own right, emerged during the period of the modern synthesis in the 1930s and 1940s. It was not until the 1980s that many universities had departments of evolutionary biology. In the United States, many universities have created departments of "molecular and cell biology" or "ecology and evolutionary biology", in place of the older departments of botany and zoology. Palaeontology is often grouped with earth science. Microbiology too is becoming an evolutionary discipline, now that microbial physiology and genomics are better understood.
Evolutionary biology | History
Current research in evolutionary biology covers diverse topics and incorporates ideas from diverse areas, such as molecular genetics and computer science. First, some fields of evolutionary research try to explain phenomena that were poorly accounted for in the modern evolutionary synthesis. These include speciation, the evolution of sexual reproduction, the evolution of cooperation, the evolution of ageing, and evolvability. Second, biologists ask the most straightforward evolutionary question: "what happened and when?". This includes fields such as paleobiology, as well as systematics and phylogenetics.
Evolutionary biology | Current research topics
It was evident that the gene must be ancient, dating back to the last common ancestor of bilateral animals (before the Ediacaran Period, which began some 635 million years ago). Evo-devo had started to uncover the ways that all animal bodies were built during development.
Evolutionary developmental biology | The birth of evo-devo and a second synthesis
But for the next century, without molecular evidence, progress stalled.
Evolutionary developmental biology | Evolutionary morphology
The biologist Eugene Koonin wrote in 2009 that "the new developments in evolutionary biology by no account should be viewed as refutation of Darwin. On the contrary, they are widening the trails that Darwin blazed 150 years ago and reveal the extraordinary fertility of his thinking."
Extended evolutionary synthesis | Recent history
In 1977, a revolution in thinking about evolution and developmental biology began, with the arrival of recombinant DNA technology in genetics, and the works "Ontogeny and Phylogeny" by Stephen J. Gould and "Evolution by Tinkering" by François Jacob. Gould laid to rest Haeckel's interpretation of evolutionary embryology, while Jacob set out an alternative theory. This led to a second synthesis, at last including embryology as well as molecular genetics, phylogeny, and evolutionary biology to form evo-devo. In 1978, Edward B. Lewis discovered homeotic genes that regulate embryonic development in "Drosophila" fruit flies, which like all insects are arthropods, one of the major phyla of invertebrate animals.
Evolutionary developmental biology | The birth of evo-devo and a second synthesis
The modern synthesis refers to the merger of genetics with natural selection which occurred in the 1930s and 1940s and offers a reasonably complete framework for understanding the emergence of biological complexity. Although there remain significant gaps in biological knowledge surrounding questions such as the origin of life and the emergence of sexual reproduction, the modern synthesis represents the most complete and well-substantiated joint point.
Tree of knowledge system | The modern synthesis
In 1973, evolutionary biologist Theodosius Dobzhansky penned that "nothing in biology makes sense except in the light of evolution," because it has brought to light the relations of what first seemed disjointed facts in natural history into a coherent explanatory body of knowledge that describes and predicts many observable facts about life on this planet.
Evolution | The 'modern synthesis'
These developments led to advances in the field of evolutionary developmental biology towards understanding how the various body plans of the animal phyla have evolved and how they are related to one another.
History of biology | Molecular systematics and genomics
In 2009, Darwin's 200th anniversary, the "Origin of Species" 150th, and the 200th of Lamarck's "early evolutionary synthesis", "Philosophie Zoologique", the evolutionary biologist Eugene Koonin stated that while "the edifice of the [early 20th century] Modern Synthesis has crumbled, apparently, beyond repair", a new 21st century synthesis could be glimpsed. Three interlocking revolutions had, he argued, taken place in evolutionary biology: molecular, microbiological, and genomic. The molecular revolution included the neutral theory, that most mutations are neutral and that negative selection happens more often than the positive form, and that all current life evolved from a single common ancestor. In microbiology, the synthesis has expanded to cover the prokaryotes, using ribosomal RNA to form a tree of life.
Modern synthesis (20th century) | Koonin's 'post-modern' evolutionary synthesis, 2009
Evolution: The Modern Synthesis, a popularising 1942 book by Julian Huxley (grandson of T.H. Huxley), set out his vision of the modern synthesis of evolutionary biology of the mid-20th century. It was enthusiastically reviewed in academic biology journals.
Evolution: The Modern Synthesis | Introduction
It includes multilevel selection, transgenerational epigenetic inheritance, niche construction, evolvability, and several concepts from evolutionary developmental biology. Not all biologists have agreed on the need for, or the scope of, an extended synthesis. Many have collaborated on another synthesis in evolutionary developmental biology, which concentrates on developmental molecular genetics and evolution to understand how natural selection operated on developmental processes and deep homologies between organisms at the level of highly conserved genes.
Extended evolutionary synthesis | Introduction
In the 1930s, work by Fisher and others resulted in a combination of Mendelian and biometric schools into the modern evolutionary synthesis. The modern synthesis bridged the gap between experimental geneticists and naturalists; and between both and palaeontologists, stating that: The idea that speciation occurs after populations are reproductively isolated has been much debated. In plants, polyploidy must be included in any view of speciation. Formulations such as 'evolution consists primarily of changes in the frequencies of alleles between one generation and another' were proposed rather later. The traditional view is that developmental biology ('evo-devo') played little part in the synthesis, but an account of Gavin de Beer's work by Stephen Jay Gould suggests he may be an exception.
Heredity | Modern development of genetics and heredity
In the 1980s and 1990s, the tenets of the modern evolutionary synthesis came under increasing scrutiny. There was a renewal of structuralist themes in evolutionary biology in the work of biologists such as Brian Goodwin and Stuart Kauffman, which incorporated ideas from cybernetics and systems theory, and emphasized the self-organizing processes of development as factors directing the course of evolution. The evolutionary biologist Stephen Jay Gould revived earlier ideas of heterochrony, alterations in the relative rates of developmental processes over the course of evolution, to account for the generation of novel forms, and, with the evolutionary biologist Richard Lewontin, wrote an influential paper in 1979 suggesting that a change in one biological structure, or even a structural novelty, could arise incidentally as an accidental result of selection on another structure, rather than through direct selection for that particular adaptation.
History of evolutionary thought | From spandrels to evolutionary developmental biology
The modern synthesis was the widely accepted early-20th-century synthesis reconciling Charles Darwin's theory of evolution by natural selection and Gregor Mendel's theory of genetics in a joint mathematical framework. It established evolution as biology's central paradigm. The 19th-century ideas of natural selection by Darwin and Mendelian genetics were united by researchers who included Ronald Fisher, one of the three founders of population genetics, and J. B. S. Haldane and Sewall Wright, between 1918 and 1932. Julian Huxley introduced the phrase "modern synthesis" in his 1942 book, "".
Extended evolutionary synthesis | The preceding "modern synthesis"
Evolutionary developmental biology (informally, evo-devo) is a field of biological research that compares the developmental processes of different organisms to infer the ancestral relationships between them and how developmental processes evolved. The field grew from 19th-century beginnings, where embryology faced a mystery: zoologists did not know how embryonic development was controlled at the molecular level. Charles Darwin noted that having similar embryos implied common ancestry, but little progress was made until the 1970s. Then, recombinant DNA technology at last brought embryology together with molecular genetics. A key early discovery was of homeotic genes that regulate development in a wide range of eukaryotes.
Evolutionary developmental biology | Introduction
The modern evolutionary synthesis is based on the concept that populations of organisms have significant genetic variation caused by mutation and by the recombination of genes during sexual reproduction. It defines evolution as the change in allelic frequencies within a population caused by genetic drift, gene flow between sub populations, and natural selection. Natural selection is emphasised as the most important mechanism of evolution; large changes are the result of the gradual accumulation of small changes over long periods of time. The modern evolutionary synthesis is the outcome of a merger of several different scientific fields to produce a more cohesive understanding of evolutionary theory.
Introduction to evolution | Modern synthesis
The past century witnessed a rapid progress in the study of plant anatomy. The focus shifted from the population level to more reductionist levels. While the first half of the century saw expansion in developmental knowledge at the tissue and the organ level, in the latter half, especially since the 1990s, there has also been a strong impetus on gaining molecular information. Edward Charles Jeffrey was one of the early evo-devo researchers of the 20th century. He performed a comparative analyses of the vasculatures of living and fossil gymnosperms and came to the conclusion that the storage parenchyma has been derived from tracheids.
Plant evolutionary developmental biology | 1900 to the present
Additionally, the modern evolutionary synthesis draws no distinction in the processes described by the theory of evolution when considering macroevolution and microevolution as the former is simply at the species level or above and the latter is below the species level. An example of this is ring species.
Objections to evolution | Lack of observation
Their descendants in the modern angiosperms also are expressed only in the stamens, the male reproductive organ. Thus, the same, then-existing components were used by the plants in a novel manner to generate the first flower. This is a recurring pattern in evolution.
Plant evolutionary developmental biology | Evolution of the MADS-box family
The principal focus of dispute with neo-Darwinists is over the source of variation on which natural selection can operate. Supporters of the extended synthesis deny that these arise from "random copying errors" in DNA replication. In fact they often assert that development of an improved organism by such a mechanism – even occasionally – would violate Shannon's principles of information theory.
Extended evolutionary synthesis | Contributions from evolutionary developmental biology
They called such incidental structural changes "spandrels" after an architectural feature. Later, Gould and Elisabeth Vrba discussed the acquisition of new functions by novel structures arising in this fashion, calling them "exaptations." Molecular data regarding the mechanisms underlying development accumulated rapidly during the 1980s and 1990s. It became clear that the diversity of animal morphology was not the result of different sets of proteins regulating the development of different animals, but from changes in the deployment of a small set of proteins that were common to all animals. These proteins became known as the "developmental-genetic toolkit." Such perspectives influenced the disciplines of phylogenetics, paleontology and comparative developmental biology, and spawned the new discipline of evolutionary developmental biology also known as evo-devo.
History of evolutionary thought | From spandrels to evolutionary developmental biology
In 2007, more than half a century after the modern synthesis, Massimo Pigliucci called for an extended evolutionary synthesis to incorporate aspects of biology that had not been included or had not existed in the mid-20th century. It revisits the relative importance of different factors, challenges assumptions made in the modern synthesis, and adds new factors such as multilevel selection, transgenerational epigenetic inheritance, niche construction, and evolvability.
Modern synthesis (20th century) | Pigliucci's extended evolutionary synthesis, 2007
Evolutionary research is concerned with the origin and descent of species, and their change over time. It employs scientists from many taxonomically oriented disciplines; for example, those with special training in particular organisms such as mammalogy, ornithology, botany, or herpetology, but are of use in answering more general questions about evolution. Evolutionary biology is partly based on paleontology, which uses the fossil record to answer questions about the mode and tempo of evolution, and partly on the developments in areas such as population genetics. In the 1980s, developmental biology re-entered evolutionary biology after its initial exclusion from the modern synthesis through the study of evolutionary developmental biology.
Biology | Evolutionary
The first is that other modes such as epigenetic inheritance, phenotypic plasticity, the Baldwin effect, and the maternal effect allow new characteristics to arise and be passed on, and for the genes to catch up with the new adaptations later. The second is that all such mechanisms are part, not of an inheritance system, but a developmental system: the fundamental unit is not a discrete selfishly competing gene, but a collaborating system that works at all levels from genes and cells to organisms and cultures to guide evolution.
Modern synthesis (20th century) | Towards a replacement synthesis
Von Baer instead recognised four distinct animal body plans: radiate, like starfish; molluscan, like clams; articulate, like lobsters; and vertebrate, like fish. Zoologists then largely abandoned recapitulation, though Ernst Haeckel revived it in 1866.
Evolutionary developmental biology | Recapitulation
Other major figures in the synthesis included E. B. Ford, Bernhard Rensch, Ivan Schmalhausen, and George Gaylord Simpson. An early event in the modern synthesis was R. A. Fisher's 1918 paper on mathematical population genetics, but William Bateson, and separately Udny Yule, were already starting to show how Mendelian genetics could work in evolution in 1902. Different syntheses followed, accompanying the gradual breakup of the early 20th century synthesis, including with social behaviour in E. O. Wilson's sociobiology in 1975, evolutionary developmental biology's integration of embryology with genetics and evolution, starting in 1977, and Massimo Pigliucci's proposed extended evolutionary synthesis of 2007.
Modern synthesis (20th century) | Introduction
In the first few decades of the 20th century, most field naturalists continued to believe that alternative mechanisms of evolution such as Lamarckism and orthogenesis provided the best explanation for the complexity they observed in the living world. But as the field of genetics continued to develop, those views became less tenable. Theodosius Dobzhansky, a postdoctoral worker in Thomas Hunt Morgan's lab, had been influenced by the work on genetic diversity by Russian geneticists such as Sergei Chetverikov. He helped to bridge the divide between the foundations of microevolution developed by the population geneticists and the patterns of macroevolution observed by field biologists, with his 1937 book "Genetics and the Origin of Species".
History of evolutionary thought | The modern synthesis
Riedl held the opinion that the modern synthesis of the mid-20th century had ignored the role of development and morphology in evolution. He argued that the modern synthesis had failed to explain the origin of body plans and patterns at the macroevolutionary level. He presented his evolutionary theory in "Order in Living Organisms: A Systems Analysis of Evolution" (translated, 1978). He called for an extended evolutionary synthesis to integrate processes from developmental biology and macroevolutionary perspectives. Riedl and Michael Conrad in the 1970s were the first two scientists to propose explicit mechanisms for the evolution of evolvability.
Rupert Riedl | Evolutionary views
Developmental biology is the study of the process by which animals and plants grow and develop. Developmental biology also encompasses the biology of regeneration, asexual reproduction, metamorphosis, and the growth and differentiation of stem cells in the adult organism.
Developmental biology | Introduction
But present-day biology is far from providing even a chemical proposal for body plan changes, let alone a data-substantiated chemical mechanism." In his lectures, Tour has referred to modern biology’s explanations for evolution of complex systems as little more than story-telling.
James Tour | A Scientific Dissent From Darwinism
Biologists disagree on the need for an extended synthesis. Opponents contend that the modern synthesis is able to fully account for the newer observations, whereas others criticize the extended synthesis for not being radical enough. Proponents think that the conceptions of evolution at the core of the modern synthesis are too narrow and that even when the modern synthesis allows for the ideas in the extended synthesis, using the modern synthesis affects the way that biologists think about evolution. For example, Denis Noble says that using terms and categories of the modern synthesis distort the picture of biology that modern experimentation has discovered.
Extended evolutionary synthesis | Status
In this sense it is plant evolutionary developmental biology (plant evo-devo). According to Zimmermann, diversity in plant evolution occurs though various developmental processes. Three very basic processes are heterochrony (changes in the timing of developmental processes), heterotopy (changes in the relative positioning of processes), and heteromorphy (changes in form processes).
Plant evolutionary developmental biology | 1900 to the present
Noble has called for an extended evolutionary synthesis, and more controversially a replacement for the modern synthesis. He has argued that from research in epigenetics, acquired characteristics can be inherited and in contrast to the modern synthesis, genetic change is "far from random" and not always gradual. He has also claimed that the central dogma of molecular biology has been broken as an "embodiment of the Weismann Barrier", and a new synthesis will integrate research from physiology with evolutionary biology.
Denis Noble | Evolution
Looking back at the conflicting accounts of the modern synthesis, the historian Betty Smocovitis notes in her 1996 book "Unifying Biology: The Evolutionary Synthesis and Evolutionary Biology" that both historians and philosophers of biology have attempted to grasp its scientific meaning, but have found it "a moving target"; the only thing they agreed on was that it was a historical event. In her words"by the late 1980s the notoriety of the evolutionary synthesis was recognized ... So notorious did 'the synthesis' become, that few serious historically minded analysts would touch the subject, let alone know where to begin to sort through the interpretive mess left behind by the numerous critics and commentators".
Modern synthesis (20th century) | Historiography
In the early 20th century, the rediscovery of Mendel's work led to the rapid development of genetics by Thomas Hunt Morgan and his students, and by the 1930s the combination of population genetics and natural selection in the "neo-Darwinian synthesis". New disciplines developed rapidly, especially after Watson and Crick proposed the structure of DNA. Following the establishment of the Central Dogma and the cracking of the genetic code, biology was largely split between "organismal biology"—the fields that deal with whole organisms and groups of organisms—and the fields related to "cellular and molecular biology". By the late 20th century, new fields like genomics and proteomics were reversing this trend, with organismal biologists using molecular techniques, and molecular and cell biologists investigating the interplay between genes and the environment, as well as the genetics of natural populations of organisms.
History of biology | Introduction
This was part of a larger transition in world views (the rise of the mechanical philosophy) that continued into the 17th century, as the traditional metaphor of "nature as organism" was replaced by the "nature as machine" metaphor.
History of biology | Renaissance and early modern developments
During the 1950s, the English biologist C. H. Waddington called for an extended synthesis based on his research on epigenetics and genetic assimilation. An extended synthesis was also proposed by the Austrian zoologist Rupert Riedl, with the study of evolvability. In 1978, Michael J. D. White wrote about an extension of the modern synthesis based on new research from speciation.
Extended evolutionary synthesis | Early history
The quick generation time of bacteria and viruses such as bacteriophages makes it possible to explore evolutionary questions. Many biologists have contributed to shaping the modern discipline of evolutionary biology. Theodosius Dobzhansky and E. B. Ford established an empirical research programme. Ronald Fisher, Sewall Wright and J. S. Haldane created a sound theoretical framework. Ernst Mayr in systematics, George Gaylord Simpson in paleontology and G. Ledyard Stebbins in botany helped to form the modern synthesis. James Crow, Richard Lewontin, Dan Hartl, Marcus Feldman, and Brian Charlesworth trained a generation of evolutionary biologists.
Evolutionary biology | History
Human evolutionary developmental biology or informally human evo-devo is the human-specific subset of evolutionary developmental biology. Evolutionary developmental biology is the study of the evolution of developmental processes across different organisms. It is utilized within multiple disciplines, primarily evolutionary biology and anthropology. Groundwork for the theory that "evolutionary modifications in primate development might have led to … modern humans" was laid by Geoffroy Saint-Hilaire, Ernst Haeckel, Louis Bolk, and Adolph Schultz. Evolutionary developmental biology is primarily concerned with the ways in which evolution affects development, and seeks to unravel the causes of evolutionary innovations. The approach is relatively new, but has roots in Schultz's "The physical distinctions of man," from the 1940s.
Human evolutionary developmental biology | Introduction
Allen & Unwin, London. (1942, reprinted 1943, 1944, 1945, 1948, 1955; 2nd ed, with new introduction and bibliography by the author, 1963; 3rd ed, with new introduction and bibliography by nine contributors, 1974). U.S. first edition by Harper, 1943.
Evolution: The Modern Synthesis | Publication history
In 1977, recombinant DNA technology enabled biologists to start to explore the genetic control of development. The growth of evolutionary developmental biology from 1978, when Edward B. Lewis discovered homeotic genes, showed that many so-called toolkit genes act to regulate development, influencing the expression of other genes. It also revealed that some of the regulatory genes are extremely ancient, so that animals as different as insects and mammals share control mechanisms; for example, the "Pax6" gene is involved in forming the eyes of mice and of fruit flies. Such deep homology provided strong evidence for evolution and indicated the paths that evolution had taken.
Modern synthesis (20th century) | Lewis's homeotic genes, 1978
In "Biology Takes Form: Animal Morphology and the German Universities, 1800–1900" (1994) she studies a wide variety of movements and institutions, seeking coherence in the history of the life sciences in nineteenth century German thought. Adapting a framework from E. S. Russell, she examines initially loosely defined morphological approaches, to trace the multi-stranded development of "scientific zoology". Two evolutionary morphologist who she discusses in detail are Carl Gegenbaur and Ernst Haeckel. This has been applauded as "a very ambitious book that tries to do many things and does most of them quite well." "Modern Nature: The Rise of the Biological Perspective in Germany" (2009) examines the transition from a natural science of collecting and taxonomic classification to a dynamic examination of the interactions of organisms, with each other and within their environments.
Lynn K. Nyhart | Career
From the early 19th century through most of the 20th century, embryology faced a mystery. Animals were seen to develop into adults of widely differing body plan, often through similar stages, from the egg, but zoologists knew almost nothing about how embryonic development was controlled at the molecular level, and therefore equally little about how developmental processes had evolved. Charles Darwin argued that a shared embryonic structure implied a common ancestor. As an example of this, Darwin cited in his 1859 book "On the Origin of Species" the shrimp-like larva of the barnacle, whose sessile adults looked nothing like other arthropods; Linnaeus and Cuvier had classified them as molluscs.
Evolutionary developmental biology | Evolutionary morphology
The section describes the distribution of social behaviour in different taxa. The theme is that evolution is progressive, with four pinnacles of social evolution, namely the colonial invertebrates such as corals, the social insects, mammals other than humans, and finally humans. The last chapter argues that natural selection has made humans far more flexible in social organisation than any other species.
Sociobiology: The New Synthesis | Part III. The Social Species
The field is characterised by some key concepts which took evolutionary biologists by surprise. One is deep homology, the finding that dissimilar organs such as the eyes of insects, vertebrates and cephalopod molluscs, long thought to have evolved separately, are controlled by similar genes such as "pax-6", from the evo-devo gene toolkit. These genes are ancient, being highly conserved among phyla; they generate the patterns in time and space which shape the embryo, and ultimately form the body plan of the organism. Another is that species do not differ much in their structural genes, such as those coding for enzymes; what does differ is the way that gene expression is regulated by the toolkit genes.
Evolutionary developmental biology | Introduction
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 increasingly common in the field of evolutionary developmental biology, particularly in studies of the origin of morphological novelty. A description of such mechanisms can be found in the multi-authored volume "Origination of Organismal Form" (MIT Press; 2003).
Punctuated equilibrium | Supplemental modes of rapid evolution
Paleontology has joined with evolutionary biology to share the interdisciplinary task of outlining the tree of life, which inevitably leads backwards in time to Precambrian microscopic life when cell structure and functions evolved. Earth's deep time in the Proterozoic and deeper still in the Archean is only "recounted by microscopic fossils and subtle chemical signals." Molecular biologists, using phylogenetics, can compare protein amino acid or nucleotide sequence homology (i.e., similarity) to evaluate taxonomy and evolutionary distances among organisms, with limited statistical confidence. The study of fossils, on the other hand, can more specifically pinpoint when and in what organism a mutation first appeared.
Fossil | Modern era
All I can presently say is that my chemical tools do not permit my assessment of intelligent design." He explained that he felt the explanations offered by evolution are incomplete, and he found it hard to believe that nature can produce the machinery of cells through random processes. On his website, he writes that "In biology, the mechanisms for such transformations are complete mysteries. I posit that the gross chemical changes needed for macroevolution (defined here as origin of the major organism groups, i.e. of body plans) are not understood and presently we cannot even suggest the mechanisms, let alone observe them…One day the requisite chemical basis might become apparent so that the questions can be answered.
James Tour | A Scientific Dissent From Darwinism
Embryos do undergo a period or phylotypic stage where their morphology is strongly shaped by their phylogenetic position, rather than selective pressures, but that means only that they resemble other embryos at that stage, not ancestral adults as Haeckel had claimed. The modern view is summarised by the University of California Museum of Paleontology:
Recapitulation theory | Modern status
The early chapters still seemed a "lucid and engaging" introduction to population biology, but much of the rest seemed after 25 years to lack "methodological breadth", given that it did not cover the new fields that had emerged; while barely mentioning the growing importance of phylogenetic systematics seemed "curious". They pointed out that comparing human and "animal" social evolution "is tantamount to making homology" claims, but Wilson had said nothing about the need for a methodology to test behavioural homology. The reviewers were also troubled by Wilson's attitude to the debate, remaining "contemptuous of his anti-sociobiological opposition" and "opprobrium towards Marxism" (especially Gould and Lewontin).
Sociobiology: The New Synthesis | Retrospective
George Gaylord Simpson was responsible for showing that the modern synthesis was compatible with palaeontology in his 1944 book "Tempo and Mode in Evolution". Simpson's work was crucial because so many palaeontologists had disagreed, in some cases vigorously, with the idea that natural selection was the main mechanism of evolution. It showed that the trends of linear progression (in for example the evolution of the horse) that earlier palaeontologists had used as support for neo-Lamarckism and orthogenesis did not hold up under careful examination. Instead the fossil record was consistent with the irregular, branching, and non-directional pattern predicted by the modern synthesis.
Modern synthesis (20th century) | Simpson's palaeontology, 1944
Almost all aspects of the synthesis have been challenged at times, with varying degrees of success. There is no doubt, however, that the synthesis was a great landmark in evolutionary biology. It cleared up many confusions, and was directly responsible for stimulating a great deal of research in the post-World War II era.
Heredity | Modern development of genetics and heredity
In current biology, fundamental research in developmental biology and evolutionary developmental biology is no longer driven by morphological comparisons between embryos, but more by molecular biology. This is partly because Haeckel's drawings were very inaccurate.
Embryo drawing | Use of embryo drawings and photography in contemporary biology
Since the advent of the modern evolutionary synthesis, evolutionary theory has been primarily "gene-centric", and developmental processes have often been seen as incidental. Evolutionary biologist Richard Dawkins's appraisal of development in 1973 illustrates this shift: "The details of embryological developmental processes, interesting as they may be, are irrelevant to evolutionary considerations." Similarly, sociobiologist E. O. Wilson regarded ontogenetic variation as "developmental noise". As a consequence of this shift in perspective, many biologists interested in topics such as embryology and developmental systems subsequently branched off into evolutionary developmental biology.
Evolutionary developmental psychology | Development and evolution
Evolutionary developmental biology (evo-devo) is the study of developmental programs and patterns from an evolutionary perspective. It seeks to understand the various influences shaping the form and nature of life on the planet. Evo-devo arose as a separate branch of science rather recently. An early sign of this occurred in 1999. Most of the synthesis in evo-devo has been in the field of animal evolution, one reason being the presence of model systems like "Drosophila melanogaster", "C. elegans", zebrafish and "Xenopus laevis". However, since 1980, a wealth of information on plant morphology, coupled with modern molecular techniques has helped shed light on the conserved and unique developmental patterns in the plant kingdom also.
Plant evolutionary developmental biology | Introduction
Modern evolutionary developmental biology (evo-devo) follows von Baer, rather than Darwin, in pointing to active evolution of embryonic development as a significant means of changing the morphology of adult bodies. Two of the key principles of evo-devo, namely that changes in the timing (heterochrony) and positioning (heterotopy) within the body of aspects of embryonic development would change the shape of a descendant's body compared to an ancestor's, were however first formulated by Haeckel in the 1870s. These elements of his thinking about development have thus survived, whereas his theory of recapitulation has not. The Haeckelian form of recapitulation theory is considered defunct.
Recapitulation theory | Modern status
Work in developmental biology has identified dynamical and physical mechanisms of tissue morphogenesis that may underlie such abrupt morphological transitions. Consequently, consideration of mechanisms of phylogenetic change that are actually (not just apparently) non-gradual is increasingly common in the field of evolutionary developmental biology, particularly in studies of the origin of morphological novelty. A description of such mechanisms can be found in the multi-authored volume "Origination of Organismal Form".
Rapid modes of evolution | Evolutionary developmental biology
With the development of the modern evolutionary synthesis in the 1930s and 1940s, Darwin's concept of evolutionary adaptation through natural selection became central to modern evolutionary theory, and it has now become the unifying concept of the life sciences.
On the Origin of Species | Introduction
Departments and disciplines fractured as organismic biologists asserted their importance and independence: Theodosius Dobzhansky made the famous statement that "nothing in biology makes sense except in the light of evolution" as a response to the molecular challenge. The issue became even more critical after 1968; Motoo Kimura's neutral theory of molecular evolution suggested that natural selection was not the ubiquitous cause of evolution, at least at the molecular level, and that molecular evolution might be a fundamentally different process from morphological evolution. (Resolving this "molecular/morphological paradox" has been a central focus of molecular evolution research since the 1960s.)
History of biology | Expansion of molecular biology
The mathematics of population genetics were originally developed as the beginning of the modern synthesis. Authors such as Beatty have asserted that population genetics defines the core of the modern synthesis. For the first few decades of the 20th century, most field naturalists continued to believe that Lamarckism and orthogenesis provided the best explanation for the complexity they observed in the living world. During the modern synthesis, these ideas were purged, and only evolutionary causes that could be expressed in the mathematical framework of population genetics were retained. Consensus was reached as to which evolutionary factors might influence evolution, but not as to the relative importance of the various factors.
Population genetics | Modern synthesis
By 1911 Castle noted that the results could be explained by Darwinian selection on heritable variation of a sufficient number of Mendelian genes.
Modern synthesis (20th century) | Castle's hooded rats, 1911
During the war, Mayr edited a series of bulletins of the Committee on Common Problems of Genetics, Paleontology, and Systematics, formed in 1943, reporting on discussions of a "synthetic attack" on the interdisciplinary problems of evolution. In 1946, the committee became the Society for the Study of Evolution, with Mayr, Dobzhansky and Sewall Wright the first of the signatories. Mayr became the editor of its journal, "Evolution". From Mayr and Dobzhansky's point of view, suggests the historian of science Betty Smocovitis, Darwinism was reborn, evolutionary biology was legitimised, and genetics and evolution were synthesised into a newly unified science. Everything fitted in to the new framework, except "heretics" like Richard Goldschmidt who annoyed Mayr and Dobzhansky by insisting on the possibility of speciation by macromutation, creating "hopeful monsters".
Modern synthesis (20th century) | The Society for the Study of Evolution, 1946
The end of the 19th century saw the fall of spontaneous generation and the rise of the germ theory of disease, though the mechanism of inheritance remained a mystery. In the early 20th century, the rediscovery of Mendel's work led to the rapid development of genetics, and by the 1930s the combination of population genetics and natural selection in the modern synthesis created evolutionary biology.
Zoology | Post-Darwin
The journals "Genetics" and "PLoS Genetics" overlap with molecular genetics questions that are not obviously evolutionary in nature.
Evolutionary biology | Journals
The evolution of the MADS-box family has been extensively studied. These genes are present even in pteridophytes, but the spread and diversity is many times higher in angiosperms. There appears to be quite a bit of pattern into how this family has evolved. Consider the evolution of the C-region gene "AGAMOUS (AG)". It is expressed in today's flowers in the stamens, and the carpel, which are reproductive organs. It's ancestor in gymnosperms also has the same expression pattern. Here, it is expressed in the strobili, an organ that produces pollens or ovules. Similarly, the B-genes' "(AP3 and PI)" ancestors are expressed only in the male organs in gymnosperms.
Plant evolutionary developmental biology | Evolution of the MADS-box family
For example, the research suggests "Markuelia" has closest affinity to priapulid worms, and is adjacent to the evolutionary branching of Priapulida, Nematoda and Arthropoda.
Fossil | Modern era
The conventional view had been that developmental biology had little influence on the modern synthesis, but the following assessment suggests otherwise, at least as far as de Beer is concerned: In his 1971 work "Homology: An Unsolved Problem", de Beer summarized that: "It is now clear that the pride with which it was assumed that the inheritance of homologous structures from a common ancestor explained homology was misplaced; for such inheritance cannot be ascribed to identity of genes. The attempt to find 'homologous' genes, except in closely related species, has been given up as hopeless."
Gavin de Beer | De Beer and the modern synthesis
After the 1950s, with the DNA helical structure being unraveled and the increasing knowledge in the field of molecular biology, developmental biology emerged as a field of study which attempts to correlate the genes with morphological change, and so tries to determine which genes are responsible for each morphological change that takes place in an embryo, and how these genes are regulated. As of today, human embryology is taught as a cornerstone subject in medical schools, as well as in biology and zoology programs at both an undergraduate and graduate level. As of today, human embryology is taught as a cornerstone subject in medical schools, as well as in biology and zoology programs at both an undergraduate and graduate level.
Embryology | Birth of Developmental Biology
Ecological evolutionary developmental biology () integrates research from developmental biology and ecology to examine their relationship with evolutionary theory. Researchers study concepts and mechanisms such as developmental plasticity, epigenetic inheritance, genetic assimilation, niche construction and symbiosis.
Evolutionary developmental biology | Ecological evolutionary developmental biology
The idea of an extended evolutionary synthesis is to extend the 20th century modern synthesis to include concepts and mechanisms such as multilevel selection theory, transgenerational epigenetic inheritance, niche construction and evolvability—though several different such syntheses have been proposed, with no agreement on what exactly would be included.
History of evolutionary thought | Extended evolutionary syntheses
These suggest multiple biomechanical differences from modern species.
Goniopholididae | Biology
The inheritance of acquired characters was rejected, while mutationism gave way as genetic theories matured. In the second half of the century the ideas of population genetics began to be applied in the new discipline of the genetics of behavior, sociobiology, and, especially in humans, evolutionary psychology. In the 1960s W.D. Hamilton and others developed game theory approaches to explain altruism from an evolutionary perspective through kin selection. The possible origin of higher organisms through endosymbiosis, and contrasting approaches to molecular evolution in the gene-centered view (which held selection as the predominant cause of evolution) and the neutral theory (which made genetic drift a key factor) spawned perennial debates over the proper balance of adaptationism and contingency in evolutionary theory.
History of biology | Classical genetics, the modern synthesis, and evolutionary theory
The modern synthesis was the early 20th-century synthesis reconciling Charles Darwin's theory of evolution and Gregor Mendel's ideas on heredity in a joint mathematical framework. Julian Huxley coined the term in his 1942 book, "". The 19th century ideas of natural selection and Mendelian genetics were put together with population genetics, early in the twentieth century. The modern synthesis also addressed the relationship between the broad-scale changes of macroevolution seen by palaeontologists and the small-scale microevolution of local populations of living organisms. The synthesis was defined differently by its founders, with Ernst Mayr in 1959, G. Ledyard Stebbins in 1966 and Theodosius Dobzhansky in 1974 offering differing numbers of basic postulates, though they all included natural selection, working on heritable variation supplied by mutation.
Modern synthesis (20th century) | Introduction
Developmental Biology is a peer-reviewed scientific journal. It was established in 1959 and is the official journal of the Society for Developmental Biology. It publishes research on the mechanisms of development, differentiation, and growth in animals and plants at the molecular, cellular, and genetic levels. The journal is published twice a month by Elsevier.
Developmental Biology (journal) | Introduction
Huxley's belief in progress within evolution and evolutionary humanism was shared in various forms by Dobzhansky, Mayr, Simpson and Stebbins, all of them writing about "the future of Mankind". Both Huxley and Dobzhansky admired the palaeontologist priest Pierre Teilhard de Chardin, Huxley writing the introduction to Teilhard's 1955 book on orthogenesis, "The Phenomenon of Man". This vision required evolution to be seen as the central and guiding principle of biology.
Modern synthesis (20th century) | Huxley's popularising synthesis, 1942
His 1937 work "Genetics and the Origin of Species" was a key step in bridging the gap between population geneticists and field naturalists. It presented the conclusions reached by Fisher, Haldane, and especially Wright in their highly mathematical papers in a form that was easily accessible to others. Further, Dobzhansky asserted that evolution was based on material genes, arranged in a string on physical hereditary structures, the chromosomes, and linked more or less strongly to each other according to their physical distances from each other on the chromosomes. As with Haldane and Fisher, Dobzhansky's "evolutionary genetics" was a genuine science, now unifying cell biology, genetics, and both micro- and macroevolution.
Modern synthesis (20th century) | Dobzhansky's evolutionary genetics, 1937
Evolution & Development is a peer-reviewed scientific journal publishing material at the interface of evolutionary and developmental biology. Within evolutionary developmental biology, it has the aim of aiding a broader synthesis of biological thought in these two areas. Its scope ranges from paleontology and population biology, to developmental and molecular biology, including mathematics and the history and philosophy of science. It was established in 1999 by five biologists: Wallace Arthur, Sean B. Carroll, Michael Coates, Rudolf Raff, and Gregory Wray. It is published by Wiley-Blackwell on behalf of the Society for Integrative and Comparative Biology.
Evolution &amp; Development | Introduction
It was not until the modern evolutionary synthesis in the 1930s and 1940s that a model of heredity became completely integrated with a model of variation. This modern evolutionary synthesis had been dubbed Neo Darwinian Evolution because it encompasses Charles Darwin's theories of evolution with Gregor Mendel's theories of genetic inheritance.
On the Origin of Species | Variation and heredity