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Gradualism
Gradualism, from the Latin ''gradus'' ("step"), is a hypothesis, a theory or a tenet assuming that change comes about gradually or that variation is gradual in nature and happens over time as opposed to in large steps. Uniformitarianism, incrementalism, and reformism are similar concepts. Geology and biology In the natural sciences, gradualism is the theory which holds that profound change is the cumulative product of slow but continuous processes, often contrasted with catastrophism. The theory was proposed in 1795 by James Hutton, a Scottish geologist, and was later incorporated into Charles Lyell's theory of uniformitarianism. Tenets from both theories were applied to biology and formed the basis of early evolutionary theory. Charles Darwin was influenced by Lyell's ''Principles of Geology'', which explained both uniformitarian methodology and theory. Using uniformitarianism, which states that one cannot make an appeal to any force or phenomenon which cannot presently be obs ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Punctuated Equilibrium
In evolutionary biology, punctuated equilibrium (also called punctuated equilibria) is a Scientific theory, theory that proposes that once a species appears in the fossil record, the population will become stable, showing little evolution, evolutionary change for most of its geological history. : ''Reprinted in'' * * This state of little or no morphological change is called ''stasis''. When significant evolutionary change occurs, the theory proposes that it is generally restricted to rare and geologic time scale, geologically rapid events of branching speciation called cladogenesis. Cladogenesis is the process by which a species splits into two distinct species, rather than one species gradually transforming into another. Punctuated equilibrium is commonly contrasted with phyletic gradualism, the idea that evolution generally occurs uniformly by the steady and gradual transformation of whole lineages (anagenesis). In 1972, paleontologists Niles Eldredge and Stephen Jay ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phyletic Gradualism
Phyletic gradualism is a model of evolution which theorizes that most speciation is slow, uniform and gradual.Eldredge, N. and S. J. Gould (1972)"Punctuated equilibria: an alternative to phyletic gradualism"In T.J.M. Schopf, ed., ''Models in Paleobiology''. San Francisco: Freeman Cooper. p. 84. When evolution occurs in this mode, it is usually by the steady transformation of a whole species into a new one (through a process called anagenesis). In this view no clear line of demarcation exists between an ancestral species and a descendant species, unless splitting occurs. The theory is contrasted with punctuated equilibrium. History The word ''phyletic'' derives from the Greek φυλετικός ''phūletikos'', which conveys the meaning of a line of descent. Phyletic gradualism contrasts with the theory of punctuated equilibrium, which proposes that most evolution occurs isolated in rare episodes of rapid evolution, when a single species splits into two distinct species, follow ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stephen Jay Gould
Stephen Jay Gould (; September 10, 1941 – May 20, 2002) was an American paleontologist, evolutionary biologist, and historian of science. He was one of the most influential and widely read authors of popular science of his generation. Gould spent most of his career teaching at Harvard University and working at the American Museum of Natural History in New York. In 1996, Gould was hired as the Vincent Astor Visiting Research Professor of Biology at New York University, after which he divided his time teaching between there and Harvard. Gould's most significant contribution to evolutionary biology was the theory of punctuated equilibrium developed with Niles Eldredge in 1972.Eldredge, Niles, and S. J. Gould (1972)"Punctuated equilibria: an alternative to phyletic gradualism."In T.J.M. Schopf, ed., ''Models in Paleobiology''. San Francisco: Freeman, Cooper and Company, pp. 82–115. The theory proposes that most evolution is characterized by long periods of evolutionary stability, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Saltation (biology)
In biology, saltation () is a sudden and large mutational change from one generation to the next, potentially causing single-step speciation. This was historically offered as an alternative to Darwinism. Some forms of mutationism were effectively saltationist, implying large discontinuous jumps. Speciation, such as by polyploidy in plants, can sometimes be achieved in a single and in evolutionary terms sudden step. Evidence exists for various forms of saltation in a variety of organisms. History Prior to Charles Darwin most evolutionary scientists had been saltationists. Jean-Baptiste Lamarck was a gradualist but similar to other scientists of the period had written that saltational evolution was possible. Étienne Geoffroy Saint-Hilaire endorsed a theory of saltational evolution that "monstrosities could become the founding fathers (or mothers) of new species by instantaneous transition from one form to the next." Geoffroy wrote that environmental pressures could produce sudden ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Uniformitarianism
Uniformitarianism, also known as the Doctrine of Uniformity or the Uniformitarian Principle, is the assumption that the same natural laws and processes that operate in our present-day scientific observations have always operated in the universe in the past and apply everywhere in the universe., "''The assumption of spatial and temporal invariance of natural laws is by no means unique to geology since it amounts to a warrant for inductive inference'' which, as Bacon showed nearly four hundred years ago, is ''the basic mode of reasoning in empirical science. Without assuming this spatial and temporal invariance, we have no basis for extrapolating from the known to the unknown'' and, therefore, no way of reaching general conclusions from a finite number of observations." It refers to invariance in the metaphysical principles underpinning science, such as the constancy of cause and effect throughout space-time, but has also been used to describe spatiotemporal invariance of physical ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Uniformitarianism (science)
Uniformitarianism, also known as the Doctrine of Uniformity or the Uniformitarian Principle, is the assumption that the same natural laws and processes that operate in our present-day scientific observations have always operated in the universe in the past and apply everywhere in the universe., "''The assumption of spatial and temporal invariance of natural laws is by no means unique to geology since it amounts to a warrant for inductive inference'' which, as Bacon showed nearly four hundred years ago, is ''the basic mode of reasoning in empirical science. Without assuming this spatial and temporal invariance, we have no basis for extrapolating from the known to the unknown'' and, therefore, no way of reaching general conclusions from a finite number of observations." It refers to invariance in the metaphysical principles underpinning science, such as the constancy of cause and effect throughout space-time, but has also been used to describe spatiotemporal invariance of physical ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Catastrophism
In geology, catastrophism theorises that the Earth has largely been shaped by sudden, short-lived, violent events, possibly worldwide in scope. This contrasts with uniformitarianism (sometimes called gradualism), according to which slow incremental changes, such as erosion, brought about all the Earth's geological features. The proponents of uniformitarianism held that the present was "the key to the past", and that all geological processes (such as erosion) throughout the past resembled those that can be observed today. Since the 19th-century disputes between catastrophists and uniformitarians, a more inclusive and integrated view of geologic events has developed, in which the scientific consensus accepts that some catastrophic events occurred in the geologic past, but regards these as explicable as extreme examples of natural processes which can occur. Proponents of catastrophism proposed that each geological epoch ended with violent and sudden natural catastrophes such as m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Reformism
Reformism is a political doctrine advocating the reform of an existing system or institution instead of its abolition and replacement. Within the socialist movement, reformism is the view that gradual changes through existing institutions can eventually lead to fundamental changes in a society's political and economic systems. Reformism as a political tendency and hypothesis of social change grew out of opposition to revolutionary socialism, which contends that revolutionary upheaval is a necessary precondition for the structural changes necessary to transform a capitalist system to a qualitatively different socialist system. Responding to a pejorative conception of reformism as non-transformational, non-reformist reform was conceived as a way to prioritize human needs over capitalist needs. As a doctrine, centre-left reformism is distinguished from centre-right or pragmatic reform which instead aims to safeguard and permeate the '' status quo'' by preventing fundamental structura ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Drift (linguistics)
Two types of language change can be characterized as linguistic drift: a unidirectional short-term and cyclic long-term drift. Short-term unidirectional drift According to Sapir, drift is the unconscious change in natural language. He gives the example ''Whom did you see?'' which is grammatically correct but is generally replaced by ''Who did you see?'' Structural symmetry seems to have brought about the change: all other ''wh-'' words are monomorphic (consisting of only one morpheme). The drift of speech changes dialects and, in long terms, it generates new languages. Although it may appear these changes have no direction, in general they do. For example, in the English language, there was the Great Vowel Shift, a chain shift of long vowels first described and accounted for in terms of drift by Jespersen (1860–1943). Another example of drift is the tendency in English to eliminate the ''-er'' comparative formative and to replace it with the more analytic ''more''. Thus, in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Charles Lyell
Sir Charles Lyell, 1st Baronet, (14 November 1797 – 22 February 1875) was a Scottish geologist who demonstrated the power of known natural causes in explaining the earth's history. He is best known as the author of ''Principles of Geology'' (1830–33), which presented to a wide public audience the idea that the earth was shaped by the same natural processes still in operation today, operating at similar intensities. The philosopher William Whewell termed this gradualistic view "uniformitarianism" and contrasted it with catastrophism, which had been championed by Georges Cuvier and was better accepted in Europe. The combination of evidence and eloquence in ''Principles'' convinced a wide range of readers of the significance of " deep time" for understanding the earth and environment. Lyell's scientific contributions included a pioneering explanation of climate change, in which shifting boundaries between oceans and continents could be used to explain long-term variati ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Evolution
Evolution is change in the heritable characteristics of biological populations over successive generations. These characteristics are the expressions of genes, which are passed on from parent to offspring during reproduction. Variation tends to exist within any given population as a result of genetic mutation and recombination. Evolution occurs when evolutionary processes such as natural selection (including sexual selection) and genetic drift act on this variation, resulting in certain characteristics becoming more common or more rare within a population. The evolutionary pressures that determine whether a characteristic is common or rare within a population constantly change, resulting in a change in heritable characteristics arising over successive generations. It is this process of evolution that has given rise to biodiversity at every level of biological organisation, including the levels of species, individual organisms, and molecules. The theory of evolution by ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Revolutionary Socialism
Revolutionary socialism is a political philosophy, doctrine, and tradition within socialism that stresses the idea that a social revolution is necessary to bring about structural changes in society. More specifically, it is the view that revolution is a necessary precondition for transitioning from a capitalist to a socialist mode of production. Revolution is not necessarily defined as a violent insurrection; it is defined as a seizure of political power by mass movements of the working class so that the state is directly controlled or abolished by the working class as opposed to the capitalist class and its interests.Thompson, Carl D. (October 1903)"What Revolutionary Socialism Means" ''The Vanguard''. Green Bay: Socialist Party of America. 2 (2): 13. Retrieved 31 August 2020 – via the Marxist Internet Archive. Revolutionary socialists believe such a state of affairs is a precondition for establishing socialism and orthodox Marxists believe it is inevitable but not predetermin ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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