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:This article is about biological evolution. For other possible meanings, see Evolution (disambiguation).Evolution generally refers to any process of change over time. However, in the context of the life sciences, evolution is a change in the genetic makeup of a group—a population of interbreeding individuals within a species. Such a population shares a gene pool and members exhibit a degree of genetic relatedness. Since the emergence of modern genetics in the 1940s, evolution was defined more specifically as a change in the frequency of alleles from one generation to the next. Evolution's two-stage process involves, first, the production and redistribution of genetic variation (see Differential survival of traits ); and, second, natural selection acting on this variation.
The word "evolution" is often used as a shorthand for the modern theory of evolution of species based upon Darwin's theory of natural selection. This theory states that all species today are the result of an extensive process of evolution that began several billion years ago with simple single- celled organisms, and that evolution via natural selection accounts for the great diversity of life, extinct and extant.
As the theory of evolution has become almost universally accepted in the scientific community, it has repeatedly been suggested that it provides an explanation as to the origin of life as well as its diversity. However these are two separate issues, and while the theory of evolution is widely accepted, the question of the origin of life remains controversial.
This controversy has resulted in a common misconception that controversy also exists concerning the theory itself. In public discussion the two issues are frequently confused, either accidentally or in attempts to either promote or discredit religious beliefs. See origin of life, spontaneous generation, abiogenesisAbiogenesis in its most general sense, is the hypothetical generation of life from non-living matter. Today, the term is primarily used in the context of biology and the origin of life. Some confusion exists on this topic, because early concepts of abioge, Young Earth creationismYoung Earth creationism is the belief that the Earth, and usually the universe, were created by a direct action of God a relatively short time ago. Such a belief is almost invariably held in conjunction with fundamentalist Christian beliefs, in which the, Miller and Urey, Creation vs. evolution debateThis article is explicitly about the debate between advocates of "creationism" and the advocates of "evolution" in attempting to explain the origins of life. For an exposition of the tenets of "creationism," see Creationism. For an exposition of the theor.
1 Scientific theory
Currently, the modern synthesis is by scientific consensusScientific consensus refers to the agreement, reached through a process of experimentation through the application of scientific method, theoretical reasoning, and peer review, within a particular field of science that a set of theories fit the current ev the best theory of the evolution of species. This is the synthesis of Darwin's theory of evolution by natural selection and MendelGregor Johann Mendel ( July 22, 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. Mendel was born in Heinzendorf, Austria (now Hyncice, Czech Republic). During h's theory of the gene made possible by population genetics. This theory conceives of evolution as any change in the frequency of an allele within a gene pool. In modern synthesis, change may be caused by a number of different mechanisms, such as natural selection or genetic drift. The genetic isolation of two populations, which allows their gene pools to diverge, results in speciation.
The commonly accepted scientific theory about how life has changed since it originated has three major aspects:
- The common descent of all organisms from (more or less) a single ancestor.
- The origin of novel traits in a lineage.
- The mechanisms that cause some traits to persist while others perish.
