Darwinism

 

concept of evolution developed in the mid-19th cent. by Charles Robert Darwin. Darwin's meticulously documented observations led him to question the then current belief in special creation of each species. After years of studying and correlating the voluminous notes he had made as naturalist on H.M.S. Beagle, he was prompted by the submission (1858) of an almost identical theory by A. R. Wallace to present his evidence for the descent of all life from a common ancestral origin; his monumental Origin of Species was published in 1859. Darwin observed (as had Malthus) that although all organisms tend to reproduce in a geometrically increasing ratio, the numbers of a given species remain more or less constant. From this he deduced that there is a continuing struggle for existence, for survival. He pointed out the existence of variations—differences among members of the same species—and suggested that the variations that prove helpful to a plant or an animal in its struggle for existence better enable it to survive and reproduce. These favorable variations are thus transmitted to the offspring of the survivors and spread to the entire species over successive generations. This process he called the principle of natural selection (the expression “survival of the fittest” was later coined by Herbert Spencer). In the same way, sexual selection (factors influencing the choice of mates among animals) also plays a part. In developing his theory that the origin and diversification of species results from gradual accumulation of individual modifications, Darwin was greatly influenced by Sir Charles Lyell's treatment of the doctrine of uniformitarianism. Darwin's evidence for evolution rested on the data of comparative anatomy, especially the study of homologous structures in different species and of rudimentary (vestigial) organs; of the recapitulation of past racial history in individual embryonic development; of geographical distribution, extensively documented by Wallace; of the immense variety in forms of plants and animals (to the degree that often one species is not distinct from another); and, to a lesser degree, of paleontology. As originally formulated, Darwinism did not distinguish between acquired characteristics, which are not transmissible by heredity, and genetic variations, which are inheritable. Modern knowledge of heredity—especially the concept of mutation, which provides an explanation of how variations may arise—has supplemented and modified the theory, but in its basic outline Darwinism is now universally accepted by scientists.

This article is about Darwinism as a philosophical concept; see evolution for the page on biological evolution; modern evolutionary synthesis for neo-Darwinism; and also evolution (disambiguation).

Darwinism is a term for the underlying theory in those ideas of Charles Darwin concerning evolution and natural selection. Discussions of Darwinism usually focus on evolution by natural selection, but sometimes Darwinism is taken to mean evolution more broadly, or other ideas not directly associated with the work of Darwin.

Other Usages of the Term

The term Darwinism is often used by promotors of creationism to describe evolution, notably by leading members of the intelligent design movement.^[1] In this usage, the term has connotations of atheism. For example, in Charles Hodge's book What Is Darwinism?, Hodge answers the question posed in the book's title by concluding: "It is Atheism."^[2][3][4] Creationists use the term Darwinism, often pejoratively, to imply that the theory has been held as true only by Darwin and a core group of his followers, who they cast as dogmatic and inflexible in their belief.^[5] Casting evolution as a doctrine or belief bolsters religiously motivated political arguments to mandate equal time for the teaching of creationism in public schools.

However, Darwinism is also used neutrally within the scientific community to distinguish modern evolutionary theories from those first proposed by Darwin, as well as by historians to differentiate it from other evolutionary theories from around the same period. For example, Darwinism may be used to refer to Darwin's proposed mechanism of natural selection, in comparison to more recent theories 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. A notable example of a scientist who uses the term in a positive sense is Richard Dawkins^{[citation needed]}.

Classical 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 half-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, although, 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.

While the reaction against Darwin's ideas is nowadays often thought to have been widespread immediately, in 1886 Wallace went on a lecture tour across the United States, starting in New York and going via Boston, Washington, Kansas, Iowa and Nebraska to California, lecturing on what he called Darwinism without any problems.^[6]

Darwinism as selectionism

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. August Weismann was the most prominent member of this school, and further articulated that neo-Darwinism referred to evolution specifically by forms of "selection" (natural selection, including sexual selection), and that it was articulated around the idea that the hereditary material of an organism was not modified by the further development of the organism. Neo-Darwinism poised itself against neo-Lamarckism, also popular at the end of the 19th century and beginning of the 20th century, which argued that bodily modifications acquired during the lifetime of the organism could be hereditarily passed on to the next generation. Weismann's neo-Darwinism, on the other hand, argued that all of an organism's hereditary material was kept in its germ plasm, which existed separately from the rest of the organism's development.

Neo-Darwinism was not terribly popular in the scientific community, as most biologists felt that the complete segregation of development and heredity actions seems unlikely or unwarranted. After the development of the modern evolutionary synthesis in the 1930s, however, the selection theory became increasingly popular amongst biologists, and codified the more modern definition of Darwinism which we have today.

Darwinian processes

In a modern definition of the term, a Darwinian process requires the following schema:

1. 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.
2. 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.
3. Selection: Inherited traits must somehow affect the ability of the entities to reproduce themselves, either by survival (natural selection), or by ability to produce offspring by finding partners (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 1976 book The Selfish Gene^{[citation needed]} .

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 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. However, it is noted many times in discussions of Universal Darwinism that the variation within a population need not be random. In fact Richard Dawkins states that the fact that Darwinian evoulution can occur "even if" the mutation/variation is random or directed to a degree away from the direction of the selection pressure.

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.

References

1. ^ Johnson, Phillip E.. What is Darwinism?. Retrieved on 2007-01-04.
2. ^ Matthew, Ropp. Charles Hodge and His Objection to Darwinism. Retrieved on 2007-01-04.
3. ^ Hodge, Charles. What is Darwinism?. Retrieved on 2007-01-04.
4. ^ Hodge, Charles (1874). What is Darwinism?. Scribner, Armstrong, and Company. OCLC 11489956. 
5. ^ From the Beagle to the School Board: God Goes Back to School, Morris Sullivan, Impact Press, Spring 2005.
6. ^ Evolution and Wonder - Understanding Charles Darwin - Speaking of Faith® from American Public Media. Retrieved on 2007-07-27.

See also

• Modern evolutionary synthesis
• Neural Darwinism
• Social Darwinism
• Darwin Awards
• Corporate Darwinism

External links

• Universal Darwinism
• Stanford Encyclopedia of Philosophy entry
• What is Darwinism
• 'Darwinism' is Still a Fighting Word in the Culture Wars

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