Evolution
Evolution is change in the heritable characteristics of biological populations over successive generations. Different characteristics tend to exist within any given population as a result of mutation, genetic recombination and other sources of genetic variation. Evolution occurs when evolutionary processes such as natural selection and genetic drift act on this variation, resulting in certain characteristics becoming more common or rare within a population.
About Evolution in brief
Evolution is change in the heritable characteristics of biological populations over successive generations. Different characteristics tend to exist within any given population as a result of mutation, genetic recombination and other sources of genetic variation. Evolution occurs when evolutionary processes such as natural selection and genetic drift act on this variation, resulting in certain characteristics becoming more common or rare within a population. 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 scientific theory of evolution by natural selection was conceived independently by Charles Darwin and Alfred Russel Wallace in the mid-19th century and was set out in detail in Darwin’s book On the Origin of Species. All life on Earth shares a last universal common ancestor that lived approximately 3. 5–3. 8 billion years ago. Existing patterns of biodiversity have been shaped by repeated formations of new species, changes within species and loss of species throughout the evolutionary history of life onEarth. The proposal that one type of organism could descend from another type goes back to some of the first pre-Socratic Greek philosophers, such as Anaximander and Empedocles. Such proposals survived into Roman times. In the 17th century, the new method of modern science rejected the Aristotelian approach. It sought explanations of natural phenomena in terms of physical laws that were the same for all visible things and that did not require the existence of any fixed natural categories or divine cosmic order. The biological classification introduced by Carl Linnaeus in 1735 still viewed species as fixed according to divine nature.
Other natural time speculated on the evolutionary change of species according to natural laws. In 1751, Pierre Louis Maupertuis wrote of natural modifications occurring during reproduction and accumulating over many generations to produce new species. Comte de Buffon suggested that species could degenerate into different organisms, and Erasmus Buffon proposed that all warm-blooded animals could have descended from a single microorganism. The first full-fledged evolutionary scheme was Jean-Baptiste Lamarck’s theory of 1809, which envisaged continually developing simple forms of life with an inherent tendency to develop in greater complexity in greater and greater parallel with greater complexity. This was the last bastion of the concept of fixed natural types, but he strictly identified each type of living thing as a species and proposed that each species could be defined by the features that perpetuated themselves generation after generation. John Ray applied one of the previously more general terms for fixed natural type, \”species\”, to plant and animal types, and said they could be identified by the characteristics that they had developed over time. The idea of species being fixed accordingto divine nature was rejected in the 19th century by the biological sciences, but still viewed as the hierarchical nature of species relationships. The modern synthesis reconciled Darwinian evolution with classical genetics, which established adaptive evolution as being caused by natural Selection acting on Mendelian genetic variation, and can be used to reconstruct phylogenetic trees.
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This page is based on the article Evolution published in Wikipedia (as of Nov. 30, 2020) and was automatically summarized using artificial intelligence.
