The modern evolutionary synthesis (often referred to simply as the modern synthesis or the evolutionary synthesis), neo-Darwinian synthesis or neo-Darwinism, generally denotes the combination of Charles Darwin's theory of the evolution of species by natural selection, Gregor Mendel's theory of genetics as the basis for biological inheritance, and mathematical population genetics. Major figures in the development of the modern synthesis include Thomas Hunt Morgan, Ronald Fisher, Theodosius Dobzhansky, J.B.S. Haldane, Sewall Wright, William D. Hamilton, Cyril Darlington, Julian Huxley, Ernst Mayr, George Gaylord Simpson, and G. Ledyard Stebbins. Essentially, the modern synthesis introduced the connection between two important discoveries; the units of evolution (genes) with the mechanism of evolution (selection). It also represents a unification of several branches of biology that previously had little in common, particularly genetics, cytology, systematics, botany, and paleontology. In his lifetime Charles Darwin gained international fame as an influential scientist examining controversial topics. ... A speculatively rooted phylogenetic tree of all living things, based on rRNA gene data, showing the separation of the three domains, bacteria, archaea, and eukaryotes, as described initially by Carl Woese. ... In biology, a species is the basic unit of biodiversity. ... Natural selection is the metaphor Charles Darwin used in 1859 to name the process he postulated to drive the adaptation of organisms to their environments and the origin of new species. ... Gregor Johann Mendel Gregor Johann Mendel (July 20, 1822 – January 6, 1884) was an Austrian monk who is often called the father of genetics for his study of the inheritance of traits in pea plants. ... Genetics (from the Greek genno γεννώ= give birth) is the science of genes, heredity, and the variation of organisms. ... Population genetics is the study of the distribution of and change in allele frequencies under the influence of the five evolutionary forces: natural selection, genetic drift, mutation, migration and nonrandom mating. ... Thomas Hunt Morgan Thomas Hunt Morgan (September 25, 1866 — December 4, 1945) was an American geneticist. ... Sir Ronald Fisher Sir Ronald Aylmer Fisher, FRS (17 February 1890 – 29 July 1962) was a British eugenicist, evolutionary biologist, geneticist and statistician. ... Theodosius Grigorevich Dobzhansky (Russian — Феодосий Григорьевич Добржанский; sometimes anglicized to Theodore Dobzhansky; January 25, 1900 - December 18, 1975) was a noted geneticist and evolutionary biologist. ... John Burdon Sanderson Haldane (November 5, 1892 - December 1, 1964), who normally used J.B.S. as a first name, was a geneticist born in Scotland and educated at Eton and Oxford University. ... Sewall Green Wright (December 21, 1889– March 3, 1988) was an American geneticist known for his influential work on evolutionary theory. ... This article is about the British biologist Bill Hamilton. ... Professor Cyril Dean Darlington FRS (19 December 1903 - 26 March 1981) was a British biologist, who, with Ronald Fisher established the journal Heredity. ... Sir Julian Sorell Huxley, FRS (June 22, 1887 – February 14, 1975) was a British biologist, author, humanist and internationalist, known for his popularisations of science in books and lectures. ... This article has been identified as possibly containing errors. ... George Gaylord Simpson (June 16, 1902 - October 6, 1984) was an American paleontologist. ... George Ledyard Stebbins, Jr (January 6, 1906 — January 19, 2000) was a American botanist and one of the architects of the modern evolutionary synthesis. ... This stylistic schematic diagram shows a gene in relation to the double helix structure of DNA and to a chromosome (right). ... Natural selection is the metaphor Charles Darwin used in 1859 to name the process he postulated to drive the adaptation of organisms to their environments and the origin of new species. ... Genetics (from the Greek genno γεννώ= give birth) is the science of genes, heredity, and the variation of organisms. ... Cytology (also known as Cell biology) is the scientific study of cells. ... Systematics is the term used by John G Bennett for the study of multi-term systems. ... Botany is the scientific study of plant life. ... A paleontologist carefully chips rock from a column of dinosaur vertebrae. ...

History

George John Romanes coined the term neo-Darwinism to refer to the theory of evolution preferred by Alfred Russel Wallace et al. Wallace rejected the Lamarckian idea of inheritance of acquired characteristics, something that Darwin, Huxley et al wouldn't rule out. The mechanism of inheritance wasn't discovered in Darwin or Wallace's time, however, so the debate was never settled. A 19th century naturalist, George John Romanes (May 19, 1848 - May 23, 1894), coined the term, and laid the foundation of, comparative psychology, and postulated a similarity of cognitive processes and mechanisms between humans and animals. ... Alfred Russel Wallace for the Cornish painter see Alfred Wallis Alfred Russel Wallace, OM , FRS (January 8, 1823 – November 7, 1913) was a British naturalist, geographer, anthropologist and biologist. ... Lamarckism was a theory of biological evolution proposed by French biologist Jean-Baptiste Pierre Antoine de Monet, Chevalier de Lamarck, since disproven. ... Thomas Huxley Thomas Henry Huxley F.R.S. (May 4, 1825 - June 29, 1895) was a British biologist, known as Darwins Bulldog for his defence of Charles Darwins theory of evolution. ...

Mendelian genetics was rediscovered in 1900. However, there were differences of opinion as to what was the variation that natural selection acted upon. The biometric school, led by Karl Pearson followed Darwin's idea that small differences were important for evolution. The Mendelian school, led by William Bateson, however, thought that Mendel's work gave an evolutionary mechanism with large differences. Mendelian inheritance (or Mendelian genetics or Mendelism) is a set of primary tenets that underlie much of genetics developed by Gregor Mendel in the latter part of the 19th century. ... 1900 (MCM) is a common year starting on Monday. ... This page is a candidate to be moved to Wiktionary. ... Karl Pearson (pencil sketch in notebook; there is some see-through of writing on next page) Karl Pearson (March 27, 1857 – April 27, 1936) was a major contributor to the early development of statistics as a serious scientific discipline in its own right. ... William Bateson (August 8, 1861—February 8, 1926) was a British geneticist. ...

A critical link between experimental biology and evolution, as well as between Mendelian genetics, natural selection, and the chromosome theory of inheritance, arose from T. H. Morgan's work with the fruit fly Drosophila melanogaster. In 1910, Morgan discovered a mutant fly with solid white eyes (wild-type Drosophila have red eyes), and found that this condition—though appearing only in males—was inherited precisely as a Mendelian recessive trait. In the subsequent years, he and his colleagues developed the Mendelian-Chromosome theory of inheritance and Morgan and his colleagues published The Mechanism of Mendelan Inheritance in 1915. By that time, most biologists accepted that genes situated linearly on chromosomes were the primary mechanism of inheritance, although how this could be compatible with natural selection and gradual evolution remained unclear. Thomas Hunt Morgan Thomas Hunt Morgan (September 25, 1866 — December 4, 1945) was an American geneticist. ... Binomial name Drosophila melanogaster Meigen, 1830 dorsal view Drosophila melanogaster Meigen , 1830 (Black-bellied Dew-lover) a dipteran (two-winged) insect, is the species of fruit fly that is commonly used in genetic experiments; it is among the most important model organisms. ...

This issue was partially resolved by Ronald Fisher, who in 1918 produced a paper entititled "The Correlation Between Relatives on the Supposition of Mendelian Inheritance", which showed using a model how continuous variation could be the result of the action of many discrete loci. This is sometimes regarded as the starting point of the synthesis. Sir Ronald Fisher Sir Ronald Aylmer Fisher, FRS (17 February 1890 – 29 July 1962) was a British eugenicist, evolutionary biologist, geneticist and statistician. ... 1918 (MCMXVIII) was a common year starting on Tuesday of the Gregorian calendar (see link for calendar) or a common year starting on Wednesday of the Julian calendar. ... The Correlation Between Relatives on the Supposition of Mendelian Inheritance is a scientific paper by Ronald Fisher which was published in the Philosophical Transactions of the Royal Society of Edinburgh in 1918, (volume 52, pages 399—433). ... The word locus (plural loci) is Latin for place. In biology, a locus is the position of a gene (or other significant sequence) on a chromosome. ...

Morgan's student Theodosius Dobzhansky was the first to apply Morgan's chromosome theory and the mathematics of population genetics to natural populations of organisms, in particular Drosophila pseudoobscura. His 1937 work Genetics and the Origin of Species is usually considered the first mature work of neo-Darwinism, and works by Ernst Mayr (Systematics and the Origin of Species- systematics), G. G. Simpson (Tempo and Mode in Evolution - paleontology) , G. Ledyard Stebbins (Variation and Evolution in Plants - botany), these are considered the four canonical works of the modern synthesis. C. D. Darlington (cytology) and Julian Huxley also wrote on the topic; Huxley coined both evolutionary synthesis and modern synthesis in his semi-popular work Evolution: The Modern Synthesis in 1942. Theodosius Grigorevich Dobzhansky (Russian — Феодосий Григорьевич Добржанский; sometimes anglicized to Theodore Dobzhansky; January 25, 1900 - December 18, 1975) was a noted geneticist and evolutionary biologist. ... Tempo and Mode in Evolution is a 1944 book by the American paleontologist George Gaylord Simpson. ... Variation and Evolution in Plants is a book written by G. Ledyard Stebbins. ... Sir Julian Sorell Huxley, FRS (June 22, 1887 – February 14, 1975) was a British biologist, author, humanist and internationalist, known for his popularisations of science in books and lectures. ...

Tenets of the modern synthesis

According to the modern synthesis as established in the 1930s and 1940s, genetic variation in populations arises by chance through mutation (this is now known to be sometimes caused by mistakes in DNA replication) and recombination (crossing over of homologous chromosomes during meiosis). Evolution consists primarily of changes in the frequencies of alleles between one generation and another as a result of genetic drift, gene flow and natural selection. Speciation occurs gradually when populations are reproductively isolated, e.g. by geographic barriers. // Events and trends A public speech by Benito Mussolini, founder of the Fascist movement The 1930s were described as an abrupt shift to more radical lifestyles, as countries were struggling to find a solution to the global depression. ... // Events and trends World War II was a truly global conflict with many facets: immense human suffering, fierce indoctrination, and the use of new, extremely devastating weapons such as the atomic bomb. ... In biology, mutations are changes to the genetic material (usually DNA or RNA). ... DNA replication. ... Genetic recombination is the transmission-genetic process by which the combinations of alleles observed at different loci (plural of locus) in two parental individuals become shuffled in offspring individuals. ... Figure 1: Chromosome. ... In biology, meiosis is the process that transforms one diploid cell into four haploid cells in eukaryotes in order to redistribute the diploids cells genome. ... Allele frequency is a term of population genetics that is used in characterizing the genetic diversity of a species population, or equivalently the richness of its gene pool. ... Genetic drift is a contributing factor in biological evolution, in which traits which do not affect reproductive fitness change in a population over time. ... Gene flow (also known as gene migration) is the transfer of genes from one population to another. ... Natural selection is the metaphor Charles Darwin used in 1859 to name the process he postulated to drive the adaptation of organisms to their environments and the origin of new species. ... Speciation refers to the evolutionary process by which new biological species arise. ...

Further advances

The modern evolutionary synthesis continued to be developed and refined after the initial establishment in the 1930s and 1940s. The work of W. D. Hamilton, George C. Williams, John Maynard Smith and others led to the development of a gene-centric view of evolution in the 1960s. The synthesis as it exists now has extended the scope of the Darwinian idea of natural selection, specifically to include subsequent scientific discoveries and concepts unknown to Darwin such as DNA and genetics that allow rigorous, in many cases mathematical, analyses of phenomena such as kin selection, altruism, and speciation. W. D. Hamilton Professor William Donald Bill Hamilton, F.R.S. (1 August 1936 — 7 March 2000) was a British evolutionary biologist. ... Professor George C. Williams is emeritus professor of biology at the State University of New York at Stony Brook. ... John Maynard Smith Professor John Maynard Smith, F.R.S. (6 January 1920 – 19 April 2004) was a British evolutionary biologist and geneticist. ... This article needs to be cleaned up to conform to a higher standard of quality. ... Space-filling model of a section of DNA molecule Deoxyribonucleic acid (DNA) is a nucleic acid that contains the genetic instructions specifying the biological development of all cellular forms of life (and most viruses). ... Genetics (from the Greek genno γεννώ= give birth) is the science of genes, heredity, and the variation of organisms. ... Kin selection was first suggested by Darwin as an explanation of the sterile castes of social insects and has later been mathematically defined by W. D. Hamilton as a mechanism for the evolution of apparently altruistic acts. ... Altruism is alternately a belief, a practice, a habit, or an ethical doctrine. ... Speciation refers to the evolutionary process by which new biological species arise. ...

A particular interpretation of neo-Darwinism most commonly associated with Richard Dawkins asserts that the gene is the only true unit of selection. Dawkins further extended the Darwinian idea to include non-biological systems exhibiting the same type of selective behavior of the 'fittest' such as memes in culture. Richard Dawkins Clinton Richard Dawkins, FRS (born March 26, 1941), known as Richard Dawkins, is a British ethologist and popular science writer. ... A Unit of Selection, is, in evolutionary theory theory, the hypothetical basis upon which organisms diverge and mutate. ... This article is in need of attention from an expert on the subject. ...

"Increasingly, studies of genes and genomes are indicating that considerable horizontal transfer has occurred between prokaryotes." [1] Horizontal Gene Transfer is called by some "A New Paradigm for Biology " [2] and emphasised by others as an important factor in "The Hidden Hazards of Genetic Engineering". "While horizontal gene transfer is well-known among bacteria, it is only within the past 10 years that its occurrence has become recognized among higher plants and animals. The scope for horizontal gene transfer is essentially the entire biosphere, with bacteria and viruses serving both as intermediaries for gene trafficking and as reservoirs for gene multiplication and recombination (the process of making new combinations of genetic material)." [3]. Horizontal gene transfer (HGT), also Lateral gene transfer (LGT) is any process in which an organism transfers genetic material (i. ...

See also

• Population genetics

Population genetics is the study of the distribution of and change in allele frequencies under the influence of the five evolutionary forces: natural selection, genetic drift, mutation, migration and nonrandom mating. ...

References

• Fisher, R. A. The Genetical Theory of Natural Selection, Clarendon Press, 1930 ISBN 0-1985-0440-3
• Haldane, J. B. S. The Causes of Evolution, Longman, Green and Co., 1932; Princeton University Press reprint, ISBN 0-6910-2442-1
• Dobzhansky, T. Genetics and the Origin of Species, Columbia University Press, 1937 ISBN 0-2310-5475-0
• Huxley, J. S., ed. The New Systematics, Oxford University Press, 1940 ISBN 0-4030-1786-6
• Huxley, J. S. Evolution: The Modern Synthesis, Allen and Unwin, 1942 ISBN 0-0284-6800-7
• Mayr, E. Systematics and the Origin of Species, Columbia University Press, 1942; Harvard University Press reprint ISBN 0-6748-6250-3
• Simpson, G. G. Tempo and Mode in Evolution, Columbia University Press, 1944 ISBN 0-2310-5847-0
• Wright, S. 1931. "Evolution in Mendelian populations". Genetics 16: 97-159.
• Allen, Garland. Thomas Hunt Morgan: The Man and His Science, Princeton University Press, 1978 ISBN 0691082006
• Mayr, E. and W. B. Provine, eds. The Evolutionary Synthesis: Perspectives on the Unification of Biology, Harvard University Press, 1980 ISBN 0-674-27226-9
• Dawkins, Richard. The Blind Watchmaker, W.W. Norton and Company, Reissue Edition 1996 ISBN 0-393-31570-3
• Smocovitis, V. Betty. Unifying Biology: The Evolutionary Synthesis and Evolutionary Biology, Princeton University Press, 1996 ISBN 0-691-03343-9