Darwinism
Darwinism is a term that is generally considered synonymous with the theory of natural selection. This theory, which was developed by Charles Darwin, holds that natural selection is the directive or creative force of evolution.
The term "Darwinism" has also been applied to the evolutionary theories of Charles Darwin in general, rather than just the theory of natural selection.
According to Mayr (1991), how the term has been used depends on who is using it and the time period. On the other hand, Harvard evolutionist Stephen Jay Gould, himself a popular writer on evolution, maintains that although the popular literature often equates Darwinism with evolution itself, the scientific community generally agrees that the term "should be restricted to the worldview encompassed by the theory of natural selection itself." That is, the term should be limited to the philosophical concept of Darwin's theory of mechanism for evolutionary change.
Theory of natural selection
The theory of natural selection is one of two major theories advanced by Darwin, the other bieng the theory of descent with modification. The theory of descent with modification deals with the pattern of evolution: that groups of organisms descended from common ancestors, with the descendant species being modified in some manner from each other over time. The theory of natural selection (or "theory of modification through natural selection") deals with the process or mechanism of evolution: how the evolution occured in order to arrive at the pattern.
expound of theory
microevolution
macroevolution
this is a copy and needs to be rewritten: "Natural selection may be defined as the mechanism whereby biological individuals that are endowed with favorable or deleterious traits reproduce more or less than other individuals that do not possess such traits.
According to this theory, natural selection is the directing or creative force of evolution. Natural selection is considered far more than just a minor force for weeding out unfit organisms. Even Paley and other natural theologians accepted natural selection, albeit as a devise for removing unfit organisms, rather than as a directive force for creating new species and new designs.
Concrete evidence for the theory of modification by natural selection is limited to microevolution — that is, evolution at or below the level of species. The evidence that natural selection directs changes on the macroevolutionary level — such as the major transitions between higher taxa and the origination of new designs — necessarily involves extrapolation from these evidences on the microevolutionary level. The validity of making such extrapolations has recently been challenged by some prominent evolutionists.
The theory of natural selection received a much more contentious response that did the theory of descent with modification. One of Darwin's chief purposes in publishing the Origin of Species was to show that natural selection had been the chief agent of the changes presented in the theory of descent with modification. While the theory of descent with modification was accepted by the scientific community soon after its introduction, the theory of natural selection took until the mid-1900s to be accepted. However, even today, this theory remains controversial, with detractors in both the scientific and religious communities. (See Natural selection.) "
Darwinian processes
In a modern definition of the term, a Darwinian process requires the following schema:
- Self-replication/Inheritance: Some number of entities must be capable of producing copies of themselves, and those copies must also be capable of reproduction. The new copies must inherit the traits of old ones. Sometimes the different variations are recombined in sexual reproduction.
- Variation: There must be a range of different traits in the population of entities, and there must be a mechanism for introducing new variations into the population.
- Selection: Inherited traits must somehow affect the ability of the entities to reproduce themselves, either by survival, or natural selection, or by ability to produce offspring by finding partners, or sexual selection.
If the entity or organism survives to reproduce, the process restarts. Sometimes, in stricter formulations, it is required that variation and selection act on different entities, variation on the replicator (genotype) and selection on the interactor (phenotype).
Darwinism asserts that any system given these conditions, by whatever means, evolution is likely to occur. That is, over time, the entities will accumulate complex traits that favor their reproduction. This is called Universal Darwinism, a term coined by Richard Dawkins in his 1972 book Selfish Gene.
some, as Darwin, believe that natural selection only works on individuals
Others, such as Gould, believes hierachical — can act on individuals, populations, species, etc.
Dawkins believed worked on level of gene
Most obviously, this can refer to biological evolution. However, it has other potential spheres, the best known of which is the meme, a concept of inheritance and modification of ideas introduced by Richard Dawkins in his 1976 book The Selfish Gene and further refined by researchers such as Richard Brodie and Susan Blackmore. It has been disputed if this was a Darwinian process, since it is unproven that memes undergo random mutations.
Perhaps surprisingly Darwinian theories have been proposed as explanations of the origin of the universe we live in. Lee Smolin's theory Cosmological natural selection explains the selection of a universe with the correct fundamental physical parameters to support complex matter such as stars and ourselves. Wojciech Zurek's theory of Quantum darwinism explains the selection of the our classical macroscopic world from underlying quantum processes.
Another example to illustrate are computer systems (PCs). Taking the software as the replicator and the whole system as the interactor, it could be seen as a Darwinian system, however, the code does not change randomly, but is directionally changed or rewritten from scratch; also systems do not reproduce.
Daniel Dennett (1995) in Darwin's Dangerous Idea argues for Universal Darwinism.
History of the term Darwinism
In the 19th-century context in which Darwin's Origin of Species was first received, "Darwinism" came to stand for an entire range of evolutionary (and often revolutionary) philosophies about both biology and society. One of the more prominent approaches was that summed in the phrase "survival of the fittest" by the philosopher Herbert Spencer, which was later taken to be emblematic of Darwinism even though Spencer's own understanding of evolution was more Lamarckian than Darwinian, and predated the publication of Darwin's theory. What we now call "Social Darwinism" was, in its day, synonymous with "Darwinism" — the application of Darwinian principles of "struggle" to society, usually in support of anti-philanthropic political agendas. Another interpretation, one notably favored by Darwin's cousin Francis Galton, was that Darwinism implied that because natural selection was apparently no longer working on "civilized" people it was possible for "inferior" strains of people (who would normally be filtered out of the gene pool) to overwhelm the "superior" strains, and corrective measures would have to be undertaken — the foundation of eugenics.
In Darwin's day there was no rigid definition of the term "Darwinism", and it was used by opponents and proponents of Darwin's biological theory alike to mean whatever they wanted it to in a larger context. The ideas had international influence, and Ernst Haeckel developed what was known as Darwinismus in Germany; though it should be noted that, like Spencer, Haeckel's "Darwinism" had only a rough resemblance to the theory of Charles Darwin, and was not centered around natural selection at all.
To distinguish themselves from the very loose meaning of "Darwinism" prevalent in the 19th century, those who advocated evolution by natural selection after the death of Darwin became known as neo-Darwinists. The term "neodarwinism" itself was coined by George John Romanes in 1896 to designate "the Darwinism proposed by Weismann and Wallace, in which an inheritance of acquired characteristics is rejected". (Mayr 1991). battle with neo_Lamarckism
Larmarcking aprnicpel of use and disuse versus the exlusivity of natural selection by August Weismann and his school, various labelled as strict, ultra or neo Darinism. hot debate at end of 19th century. Alfred Russel Wallace and August Weismann — the two principle "neo-Darwinians" of the late 19th Century. As Gould notes, "In the late 19th century, "Neo-Darwinism," a term coined by Romanes, referred to the panselectionist school of Wallace and Weismann, not to the pluralism of Darwin himself. The modern meaning, associated with the evolutionary synthesis of the 1930's and onward, is not genealogically linked to this earlier definition.).p 216.
The term neo-Darwinism was not terribly popular in the scientific community until after the development of the modern evolutionary synthesis in the 1930s, when the term became synonomyous with this term.
One Long Argument: Charles Darwin and the Genesis of Modern Evolutionary Thought, Ernst Mayr, Harvard University Press, Cambridge Massachusetts 1991. ISBN 0-674-63905-7. QH371.M336 1991. 575 - dc20.
Darwinism and other -isms
In the United States, the term "Darwinism" is sometimes used by creationists as a somewhat derogatory term for "evolutionary biology". Casting evolution as an "ism" — a doctrine or belief — is used to strengthen calls for "equal time" for other beliefs such as creationism. However, in other countries — such as the United Kingdom — "Darwinism" carries no such derogatory connotations and is freely used by evolutionary scientists. A notable example of a scientist who uses the term in a positive sense is Richard Dawkins.
Darwinism may also refer to a specific strand within evolutionary biology, dealing with the mechanism of natural selection, which Darwin studied, as opposed to evolutionary processes that were unknown in Darwin's day, such as genetic drift and gene flow. It may also refer specifically to the role of Charles Darwin as opposed to others in the history of evolutionary thought — particularly contrasting Darwin's results with those of earlier theories such as Lamarckism or later ones such as the modern synthesis.
Challenges to Darwinism
IN addition to the lack of evidence for natural seleciton as the causal agent on macroevolutionary levels, there are challenges to the theory of natural selection. Many of these relate to religious viewpoitns. However, young-earth creationism is pretty well refruted.
List challenges and discuss each here
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