Evolution is the change in the inherited characteristics of biological populations over successive generations. Evolutionary processes give rise to diversity at every level of biological organisation, including species, individual organisms and molecules such as DNA and proteins.
Life on Earth originated and then evolved from a universal common ancestor approximately 3.8 billion years ago. Repeated speciation and the divergence of life can be inferred from shared sets of biochemical and morphological traits, or by shared DNA sequences. These homologous traits and sequences are more similar among species that share a more recent common ancestor, and can be used to reconstruct evolutionary histories, using both existing species and the fossil record. Existing patterns of biodiversity have been shaped both by speciation and by extinction.
Charles Darwin was the first to formulate a scientific argument for the theory of evolution by means of natural selection. Evolution by natural selection is a process that is inferred from three facts about populations: 1) more offspring are produced than can possibly survive, 2) traits vary among individuals, leading to differential rates of survival and reproduction, and 3) trait differences are heritable. Thus, when members of a population die they are replaced by the progeny of parents that were better adapted to survive and reproduce in the environment in which natural selection took place. This process creates and preserves traits that are seemingly fitted for the functional roles they perform. Natural selection is the only known cause of adaptation, but not the only known cause of evolution. Other, nonadaptive causes of evolution include mutation and genetic drift.
In the early 20th century, genetics was integrated with Darwin's theory of evolution by natural selection through the discipline of population genetics. The importance of natural selection as a cause of evolution was accepted into other branches of biology. Moreover, previously held notions about evolution, such as orthogenesis and "progress" became obsolete. Scientists continue to study various aspects of evolution by forming and testing hypotheses, constructing scientific theories, using observational data, and performing experiments in both the field and the laboratory. Biologists agree that descent with modification is one of the most reliably established facts in science. Discoveries in evolutionary biology have made a significant impact not just within the traditional branches of biology, but also in other academic disciplines (e.g., anthropology and psychology) and on society at large.
Read more about Evolution: History of Evolutionary Thought, Heredity, Variation, Mechanisms, Outcomes, Evolutionary History of Life, Applications, Social and Cultural Responses
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... the crew finds evidence of a form of quasi-life, born through evolution of autonomous, self-replicating machines, apparently left behind by an alien civilization that visited the planet a very long time ... The evolution was controlled by "robot wars", and the only form that survived were swarms of minuscule, insect-like micromachines ... In particular, it is an imaginary experiment to demonstrate that evolution may not necessarily lead to dominance by intellectually superior life forms ...
... Further information Social effect of evolutionary theory and Objections to evolution In the 19th century, particularly after the publication of On the Origin of Species in 1859, the idea that life had ... However, evolution remains a contentious concept for some theists ... have reconciled their beliefs with evolution through concepts such as theistic evolution, there are creationists who believe that evolution is contradicted by the creation myths found in their religions and ...
2005, Wells participated in the Kansas evolution hearings, which were boycotted by mainstream scientists ... There Wells testified Prior to the evolution hearings, in December 2000 after the Pratt County, Kansas school board revised its tenth-grade biology curriculum at the ... characterized by creationists as revealing some fatal flaw in the theory of evolution ...
... Ridge Ministries, Johnson gave a speech called How the Evolution Debate Can Be Won ... the battle "To talk of a purposeful or guided evolution is not to talk about evolution at all ... that way, you realize that the Darwinian theory of evolution contradicts not just the Book of Genesis, but every word in the Bible from beginning to end ...
1997 Marie-Charlotte Anstett Facilitation and constraints in the evolution of mutualism 1999 Nicolas Galtier Non stationary models of nucleotide substitution and the evolution of base composition 2001 ...
Famous quotes containing the word evolution:
“Like Freud, Jung believes that the human mind contains archaic remnants, residues of the long history and evolution of mankind. In the unconscious, primordial “universally human images” lie dormant. Those primordial images are the most ancient, universal and “deep” thoughts of mankind. Since they embody feelings as much as thought, they are properly “thought feelings.” Where Freud postulates a mass psyche, Jung postulates a collective psyche.”
—Patrick Mullahy (b. 1912)
“The more specific idea of evolution now reached is—a change from an indefinite, incoherent homogeneity to a definite, coherent heterogeneity, accompanying the dissipation of motion and integration of matter.”
—Herbert Spencer (1820–1903)
“As a natural process, of the same character as the development of a tree from its seed, or of a fowl from its egg, evolution excludes creation and all other kinds of supernatural intervention.”
—Thomas Henry Huxley (1825–95)