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In Biology , evolution is the change in the Inherited Traits of a Population from generation to generation. These traits are the Expression of Gene s that are copied and passed on to offspring during Reproduction . Mutation s in these genes can produce new or altered traits, resulting in heritable differences ( Genetic Variation ) between organisms. New traits can also come from transfer of genes between populations, as in migration, or between species, in Horizontal Gene Transfer . Evolution occurs when these heritable differences become more common or rare in a population, either non-randomly through Natural Selection or randomly through Genetic Drift . Natural selection is a process that causes heritable traits that are helpful for survival and reproduction to become more common, and harmful traits to become rarer. This occurs because organisms with advantageous traits pass on more copies of these traits to the next generation.1 Over many generations, Adaptation s occur through a combination of successive, small, random changes in traits, and natural selection of those variants best-suited for their environment.2 In contrast, Genetic Drift produces random changes in the frequency of traits in a population. Genetic drift arises from the element of chance involved in which individuals survive and reproduce. One definition of a Species is a group of organisms that can reproduce with one another and produce fertile offspring. However, when a species is separated into populations that are Prevented From Interbreeding , mutations, genetic drift, and the selection of novel traits cause the accumulation of differences over generations and the emergence of New Species .3 The similarities between organisms suggest that all known species are Descended From A Common Ancestor (or ancestral gene pool) through this process of gradual divergence.4 HEREDITY are in the center, surrounded by phosphate–sugar chains in a Double Helix ]] Inheritance in organisms occurs through discrete Traits – particular characteristics of an organism. In humans, for example, Eye Color is an inherited characteristic, which individuals can inherit from one of their parents.9 Inherited traits are controlled by Gene s and the complete set of genes within an organism's Genome is called its Genotype .10 The complete set of observable traits that make up the structure and behavior of an organism is called its Phenotype . These traits come from the interaction of its genotype with the environment.11 As a result, not every aspect of an organism's phenotype is inherited. Suntanned skin results from the interaction between a person's genotype and sunlight; thus, a suntan is not hereditary. However, people have different responses to sunlight, arising from differences in their genotype; a striking example is individuals with the inherited trait of Albinism , who do not tan and are highly sensitive to Sunburn .12 Gene s are regions within DNA molecules that contain genetic information. DNA is a long molecule with four types of Bases attached along its length. Different genes have different sequences of bases; it is the sequence of these bases that encodes genetic information. Within Cells , the long strands of DNA associate with proteins to form structures called Chromosome s. A specific location within a chromosome is known as a Locus . If the DNA sequence at a locus varies between individuals, the different forms of this sequence are called Allele s. DNA sequences can change through Mutation s, producing new alleles. If a mutation occurs within a gene, the new allele may affect the trait that the gene controls, altering the phenotype of the organism. However, while this simple correspondence between an allele and a trait works in some cases, most traits are more complex and are controlled by Multiple Interacting Genes .1314 VARIATION Because an individual's Phenotype results from the interaction of their Genotype with the environment, the variation in phenotypes in a population reflects the variation in these organisms' genotypes. The Modern Evolutionary Synthesis defines evolution as the change over time in this genetic variation.15 The frequency of one particular allele will fluctuate, becoming more or less prevalent relative to other forms of that gene. Evolutionary forces act by driving these changes in allele frequency in one direction or another. Variation disappears when an allele reaches the point of Fixation — when it either disappears from the population or replaces the ancestral allele entirely.16
Mutation Genetic variation comes from Random mutations that occur in the genomes of organisms. Mutations are changes in the DNA sequence of a cell's genome and are caused by Radiation , Virus es, Transposon s and Mutagenic Chemicals , as well as errors that occur during Meiosis or DNA Replication .212223 These mutagens produce several different types of change in DNA sequences; these can either have no effect, alter the Product Of A Gene , or prevent the gene from functioning. Studies in the fly '' Drosophila Melanogaster '' suggest that about 70 percent of mutations are deleterious, and the remainder are either neutral or have a weak beneficial effect.24 Due to the damaging effects that mutations can have on cells, organisms have evolved mechanisms such as DNA Repair to remove mutations. Therefore, the optimal mutation rate for a species is a trade-off between short-term costs, such as the risk of cancer, and the long-term benefits of advantageous mutations.25 ]] Large sections of DNA can also be and one for Night Vision ; all four arose from a single ancestral gene.30 An advantage of duplicating a gene (or even an ( Entire Genome ) is that overlapping or Redundant Functions in multiple genes allows alleles to be retained that would otherwise be harmful, thus increasing genetic diversity.31 Changes in chromosome number may also involve the breakage and rearrangement of DNA within chromosomes. For example, two chromosomes in the ''Homo'' genus fused to produce human chromosome 2; this fusion did not occur in the chimpanzee Lineage and chimpanzees retain these separate chromosomes.32 In evolution, the most important role of such chromosomal rearrangements may be to accelerate the divergence of a population into new species by preserving genetic differences within populations.33 Sequences of DNA that can move about the genome, such as Transposon s, make up a major fraction of the genetic material of plants and animals, and may have been important in the evolution of genomes.34 For example, more than a million copies of the Alu Sequence are present in the Human Genome , and these sequences have now been recruited to perform functions such as regulating Gene Expression .35 Another effect of these mobile DNA sequences is that when they move within a genome, they can mutate or delete existing genes and thereby produce genetic diversity.36 Recombination In asexual organisms, genes are inherited together, or ''linked'', as they cannot mix with genes in other organisms during reproduction. However, the offspring of Sex ual organisms contain a random mixture of their parents' chromosomes that is produced through Independent Assortment . In the related process of Genetic Recombination , sexual organisms can also exchange DNA between two matching chromosomes.37 These shuffling processes can allow even alleles that are close together in a strand of DNA to be Inherited Independently . However, as only about one recombination event occurs per million Base Pair s in humans, genes close together on a chromosome may not be shuffled away from each other, and tend to be inherited together.38 This tendency is measured by finding how often two alleles occur together, which is called their Linkage Disequilibrium . A set of alleles that is usually inherited in a group is called a Haplotype , and this co-inheritance can indicate that the locus is under positive selection ( See Below ).39 Recombination in sexual organisms helps to remove harmful mutations and retain beneficial mutations.40 Consequently, when alleles cannot be separated by recombination – such as in mammalian Y Chromosome s, which pass intact from fathers to sons – harmful Mutations Accumulate .4142 In addition, recombination can produce individuals with new and advantageous gene combinations. These positive effects of recombination are balanced by the fact that this process can cause mutations and separate beneficial combinations of genes. The optimal rate of recombination for a species is therefore a trade-off between conflicting factors. MECHANISMS There are three basic mechanisms of evolutionary change: Natural Selection , Genetic Drift , and Gene Flow . Natural selection favors genes that improve capacity for survival and reproduction. Genetic drift is the random sampling of a generation's genes during reproduction, causing random changes in the frequency of alleles, and gene flow is the transfer of genes within and between populations. The relative importance of natural selection and genetic drift in a population varies depending on the strength of the selection and the Effective Population Size , which is the number of individuals capable of breeding.43 Natural selection usually predominates in large populations, while genetic drift dominates in small populations. The dominance of genetic drift in small populations can even lead to the fixation of slightly deleterious mutations.44 As a result, changing population size can dramatically influence the course of evolution. Population Bottleneck s, where the population shrinks temporarily and therefore loses genetic variation, result in a more uniform population. Bottlenecks also result from alterations in gene flow such as decreased migration, Expansions Into New Habitats , or population subdivision. Natural selection of a population for dark coloration.]] Natural Selection is the process by which genetic mutations that enhance reproduction become, and remain, more common in successive generations of a population. It has often been called a "self-evident" mechanism because it necessarily follows from three simple facts:
These conditions produce competition between organisms for survival and reproduction. Consequently, organisms with traits that give them an advantage over their competitors pass these advantageous traits on, while traits that do not confer an advantage are not passed on to the next generation. The central concept of natural selection is the . Conversely, the lower fitness caused by having a less beneficial or deleterious allele results in this allele becoming rarer — they are "selected ''against''". Importantly, the fitness of an allele is not a fixed characteristic, if the environment changes, previously neutral or harmful traits may become beneficial and previously beneficial traits become harmful. Natural selection within a population for a trait that can vary across a range of values, such as height, can be categorized into three different types. The first is Directional Selection , which is a shift in the average value of a trait over time — for example organisms slowly getting taller.46 Secondly, Disruptive Selection is selection for extreme trait values and often results in Two Different Values becoming most common, with selection against the average value. This would be when either short or tall organisms had an advantage, but not those of medium height. Finally, in Stabilizing Selection there is selection against extreme trait values on both ends, which causes a decrease in Variance around the average value.47 This would, for example, cause organisms to slowly become all the same height. A special case of natural selection is Sexual Selection , which is selection for any trait that increases mating success by increasing the attractiveness of an organism to potential mates.48 Traits that evolved through sexual selection are particularly prominent in males of some animal species, despite traits such as cumbersome antlers, mating calls or bright colors that attract predators, decreasing the survival of individual males.49 This survival disadvantage is balanced by higher reproductive success in males that show these Hard To Fake , sexually selected traits.50 An active area of research is the Unit Of Selection , with natural selection being proposed to work at the level of genes, cells, individual organisms, groups of organisms and even species.5152 None of these models are mutually-exclusive and selection may act on multiple levels simultaneously.53 Below the level of the individual, genes called transposons try to copy themselves throughout the Genome .54 Selection at a level above the individual, such as Group Selection , may allow the evolution of co-operation, as discussed below.55 of 20 unlinked alleles in populations of 10 (top) and 100 (bottom). Drift is more rapid in the smaller population.]] Genetic drift Genetic drift is the change in allele frequency from one generation to the next that occurs because alleles in the offspring generation are a Random Sample of those in the parent generation, and are thus subject to Sampling Error . As a result, when selective forces are absent or relatively weak, allele frequencies tend to "drift" upward or downward in a Random Walk . This drift halts when an allele eventually becomes Fixed , either by disappearing from the population, or replacing the other alleles entirely. Genetic drift may therefore eliminate some alleles from a population due to chance alone, and two separate populations that began with the same genetic structure can drift apart by random fluctuation into two divergent populations with different sets of alleles.56 The time for an allele to become fixed by genetic drift depends on population size, with fixation occurring more rapidly in smaller populations.57 Although natural selection is responsible for adaptation, the relative importance of the two forces of natural selection and genetic drift in driving evolutionary change in general is an area of current research in evolutionary biology.58 These investigations were prompted by the Neutral Theory Of Molecular Evolution , which proposed that most evolutionary changes are the result the fixation of Neutral Mutation s that do not have any immediate effects on the fitness of an organism.59 Hence, in this model, most genetic changes in a population are the result of constant mutation pressure and genetic drift.60 Gene flow s leave the pride where they are born and take over a new pride to mate. This results in Gene Flow between prides.]] Gene Flow is the exchange of genes between populations, which are usually of the same species.61 Examples of gene flow within a species include the migration and then breeding of organisms, or the exchange of Pollen . Gene transfer between species includes the formation of Hybrid organisms and Horizontal Gene Transfer . Migration into or out of a population can change allele frequencies. Immigration may add new genetic material to the established Gene Pool of a population. Conversely, emigration may remove genetic material. As Barriers To Reproduction between two diverging populations are required for the populations to Become New Species , gene flow may slow this process by spreading genetic differences between the populations. Gene flow is hindered by mountain ranges, oceans and deserts or even man-made structures such as the Great Wall Of China , which has hindered the flow of plant genes.62 Depending on how far two species have diverged since their Last Common Ancestor , it may still be possible for them to produce offspring, as with Horse s and Donkey s mating to produce Mule s.63 Such Hybrid s are generally Infertile , due to the two different sets of chromosomes being unable to pair up during Meiosis . In this case, closely-related species may regularly interbreed, but hybrids will be selected against and the species will remain distinct. However, viable hybrids are occasionally formed and these new species can either have properties intermediate between their parent species, or possess a totally new phenotype.64 Hybridization rarely leads to New Species in animals, although this has been seen in Gray Tree Frog .65 Hybridization is, however, an important means of speciation in plants, since Polyploidy (having more than two copies of each chromosome) is tolerated in plants more readily than in animals.66 Polyploidy is important in hybrids as it allows reproduction, with the two different sets of chromosomes each being able to pair with an identical partner during meiosis.67 Polyploids also have more genetic diversity, which allows them to avoid Inbreeding Depression in small populations.68 Horizontal Gene Transfer is the transfer of genetic material from one organism to another organism that is not its offspring, this is most common among Bacteria .69 In medicine, this contributes to the spread of Antibiotic Resistance , as when one bacteria acquires resistance genes it can rapidly transfer them to other species.70 Horizontal transfer of genes from bacteria to eukaryotes such as the yeast '' Saccharomyces Cerevisiae '' and the adzuki bean beetle ''Callosobruchus chinensis'' may also have occurred.7172 Virus es can also carry DNA between organisms, allowing transfer of genes even across Biological Domains .73 Gene transfer has also occurred within Eukaryotic Cells , from the Chloroplast and Mitochondria l genomes to Nuclear Genomes .74 OUTCOMES Evolution influences every aspect of the form and behavior of organisms. Most prominent are the specific behavioral and physical Adaptation s that are the outcome of natural selection. These adaptations increase fitness by aiding activities such as finding food, avoiding predators or attracting mates. Organisms can also respond to selection by Co-operating with each other, usually by aiding their relatives or engaging in mutually-beneficial Partnerships . In the longer term, evolution produces new species through splitting ancestral populations of organisms into new groups that are unable to breed with one another. These outcomes of evolution are sometimes divided into Macroevolution , which is evolution that occurs at or above the level of species, such as Speciation , and Microevolution , which is smaller evolutionary changes, such as adaptations, within a species or population. In general, macroevolution is the outcome of long periods of microevolution.75 Thus, the distinction between micro- and macroevolution is not a fundamental one - the difference is simply the time involved.76 However, in macroevolution, the traits of the entire species are important. For instance, a large amount of variation among individuals allows a species to rapidly adapt to new habitats, lessening the chance of it going extinct, while a wide geographic range increases the chance of speciation, by making it more likely that part of the population will become isolated. In this sense, microevolution and macroevolution can sometimes be separate.77 pp. 657–58 A common misconception is that evolution is "progressive," but natural selection has no long-term goal and does not necessarily produce greater complexity. Scientific American; Biology: Is the human race evolving or devolving? , see also Biological Devolution . Although Complex Species have evolved, this occurs as a side effect of the overall number of organisms increasing, and simple forms of life remain more common.78 For example, the overwhelming majority of species are microscopic Prokaryote s, which form about half the world's biomass despite their small size,79 and constitute the vast majority of Earth's biodiversity.80 Simple organisms therefore remain the dominant form of life on Earth, and complex life appears more diverse only because it is More Noticeable .81 Adaptation Adaptations are structures or behaviors that enhance a specific function, causing organisms to become better at surviving and reproducing. They are produced by a combination of the continuous production of small, random changes in traits, followed by natural selection of the variants best-suited for their environment.82 This process can cause either the gain of a new feature, or the loss of an ancestral feature. An example that shows both types of change is bacterial adaptation to Antibiotic selection, with mutations causing Antibiotic Resistance by either modifying the target of the drug, or removing the transporters that allow the drug into the cell.83 However, many traits that appear to be simple adaptations are in fact Exaptation s: structures originally adapted for one function, but which coincidentally became somewhat useful for some other function in the process.84 pp. 1235–36 One example is the African lizard ''Holapsis guentheri'', which developed an extremely flat head for hiding in crevices, as can be seen by looking at its near relatives. However, in this species, the head has become so flattened that it assists in gliding from tree to tree - an exaptation. skeleton, ''a'' and ''b'' label leg bones.85]] As adaptation occurs through the gradual modification of existing structures, structures with similar internal organization may have very different functions in related organisms. This is the result of a single Ancestral Structure being adapted to function in different ways. The bones within bat wings, for example, are structurally similar to both human hands and seal flippers, due to the common descent of these structures from an ancestor that also had five digits at the end of each forelimb. Other idiosyncratic anatomical features, such as Bones In The Wrist of the Panda being formed into a false "thumb," indicate that an organism's evolutionary lineage can limit what adaptations are possible.86 During adaption, some structures may lose their original function and become Vestigial Structure s.87 Such structures may have little or no function in a current species, yet have a clear function in ancestral species, or other closely-related species. Examples include the non-functional remains of eyes in blind cave-dwelling fish,88 wings in flightless birds,89 and the presence of hip bones in whales and snakes.90 Examples of vestigial structures in humans include Wisdom Teeth ,91 the Coccyx , and the Vermiform Appendix .
Co-evolution Co-operation
Coalitions between organisms of the same species have also evolved. An extreme case is the Eusociality found in Social Insect s, such as Bee s, Termite s and Ant s, where sterile insects feed and guard the small number of organisms in a Colony that are able to reproduce. On an even smaller scale, the Somatic Cell s that make up the body of an animal are limited in their capacity to reproduce in order to maintain a stable organism which then supports a small number of the animal's Germ Cell s to produce offspring. Here, somatic cells respond to specific signals that instruct them to either Grow or Kill Themselves . If cells ignore these signals and attempt to multiply inappropriately, their uncontrolled growth causes Cancer . These examples of cooperation within species are thought to have evolved through the process of Kin Selection , which is where one organism acts to help raise a relative's offspring.104 This activity is selected for because if the ''helping'' individual contains alleles which promote the helping activity, it is likely that its kin will ''also'' contain these alleles and thus those alleles will be passed on.105 Other processes that may promote cooperation include Group Selection , where cooperation provides benefits to a group of organisms.106 Speciation .]]
The second mechanism of speciation is Peripatric Speciation , which occurs when small populations of organisms become isolated in a new environment. This differs from allopatric speciation in that the isolated populations are numerically much smaller than the parental population. Here, the Founder Effect causes rapid speciation through both rapid genetic drift and selection on a small gene pool.112 The third mechanism of speciation is Parapatric Speciation . This is similar to peripatric speciation in that a small population enters a new habitat, but differs in that there is no physical separation between these two populations. Instead, speciation results from the evolution of mechanisms that reduce gene flow between the two populations. Generally this occurs when there has been a drastic change in the environment within the parental species' habitat. One example is the grass '' Anthoxanthum Odoratum '', which can undergo parapatric speciation in response to localized metal pollution from mines.113 Here, plants evolve that have resistance to high levels of metals in the soil. Selection against interbreeding with the metal-sensitive parental population produces a change in flowering time of the metal-resistant plants, causing reproductive isolation. Selection against hybrids between the two populations may cause ''reinforcement'', which is the evolution of traits that promote mating within a species, as well as Character Displacement , which is when two species become more distinct in appearance.114 of Finches on the Galápagos Islands produced over a dozen new species.]]
Indeed, chromosome doubling can itself cause reproductive isolation, as half the doubled chromosomes will be unmatched when breeding with undoubled organisms.118 Speciation events are important in the theory of Punctuated Equilibrium , which accounts for the pattern in the fossil record of short "bursts" of evolution interspersed with relatively long periods of stasis, where species remain relatively unchanged.119 In this theory, speciation and rapid evolution are linked, with natural selection and genetic drift acting most strongly on organisms undergoing speciation in novel habitats or small populations. As a result, the periods of stasis in the fossil record correspond to the parental population, and the organisms undergoing speciation and rapid evolution are found in small populations or geographically-restricted habitats, and therefore rarely being preserved as fossils.120 Extinction '' skeleton. Non- Avian Dinosaur s died out in a Mass Extinction at the end of the Cretaceous period.]]
The role of extinction in evolution depends on which type is considered. The causes of the continuous "low-level" extinction events, which form the majority of extinctions, are not well understood and may be the result of competition between species for shared resources. If competition from other species does alter the probability that a species will become extinct, this could produce Species Selection as a level of natural selection. The intermittent mass extinctions are also important, but instead of acting as a selective force, they drastically reduce diversity in a nonspecific manner and promote bursts of Rapid Evolution and speciation in survivors. EVOLUTIONARY HISTORY OF LIFE Origin of life The origin of Life is a necessary precursor for biological evolution, but understanding that evolution occurred once organisms appeared and investigating how this happens, does not depend on understanding exactly how life began. Accessed 13 May 2007 The current Scientific Consensus is that the complex Biochemistry that makes up life came from simpler chemical reactions, but it is unclear how this occurred.128 Not much is certain about the earliest developments in life, the structure of the first living things, or the identity and nature of any Last Universal Common Ancestor or ancestral gene pool.129130131 Consequently, there is no scientific consensus on how life began, but proposals include self-replicating molecules such as RNA ,132 and the assembly of simple cells.133 Common descent are descendants of a Common Ancestor .]] All Organisms on Earth are descended from a common ancestor or ancestral gene pool.134 Current species are a stage in the process of evolution, with their diversity the product of a long series of speciation and extinction events.135 The Common Descent of organisms was first deduced from four simple facts about organisms: First, they have geographic distributions that cannot be explained by local adaptation. Second, the diversity of life is not a set of completely unique organisms, but organisms that share morphological similarities. Third, vestigial traits with no clear purpose resemble functional ancestral traits, and finally, that organisms can be classified using these similarities into a hierarchy of nested groups. Past species have also left records of their evolutionary history. Fossil s, along with the comparative anatomy of present-day organisms, constitute the morphological, or anatomical, record.136 By comparing the anatomies of both modern and extinct species, paleontologists can infer the lineages of those species. However, this approach is most successful for organisms that had hard body parts, such as shells, bones or teeth. Further, as prokaryotes such as Bacteria and Archaea share a limited set of common morphologies, their fossils do not provide information on their ancestry. More recently, evidence for common descent has come from the study of produced by mutations.138 For example, these DNA sequence comparisons have revealed the close genetic similarity between humans and chimpanzees and shed light on when the common ancestor of these species existed.139 showing the divergence of modern species from their common ancestor in the center.140 The three Domains are colored, with Bacteria blue, Archaea green, and Eukaryote s red.]] Evolution of life
The history of life was that of the unicellular eukaryotes, prokaryotes, and archaea until about a billion years ago when multicellular organisms began to appear in the oceans in the Ediacaran period.150 The Evolution Of Multicellularity occurred in multiple independent events, in organisms as diverse as Sponge s, Brown Algae , Cyanobacteria , Slime Mould s and Myxobacteria .151
HISTORY OF EVOLUTIONARY THOUGHT at age 51, just after publishing '' The Origin Of Species ''.]] Evolutionary ideas such as in 1745, and with contributions from natural philosophers such as Erasmus Darwin and Jean-Baptiste Lamarck .158 In 1858, Charles Darwin and Alfred Russel Wallace jointly proposed the theory of evolution by natural selection to the Linnean Society Of London in Separate Papers .159 Shortly after, Darwin's publication of '' The Origin Of Species '' provided detailed support for the theory and led to increasingly wide acceptance of the occurrence of evolution. Nonetheless, Darwin's specific ideas about evolution, such as Gradualism and the mechanisms of natural selection, were strongly contested at first. Lamarckists argued that Transmutation Of Species occurred as parents Passed On Adaptations Acquired during their lifetimes.160 Eventually, when experiments failed to support it, this idea was abandoned in favor of Darwinism.161 More significantly, Darwin could not account for how traits were passed down from generation to generation. A mechanism was provided in 1865 by Gregor Mendel , who found that traits were Inherited in a predictable manner.162 When Mendel's work was rediscovered in 1900, disagreements over the rate of evolution predicted by early geneticists and Biometricians led to a rift between the Mendelian and Darwinian models of evolution. , who laid the foundation for Genetics .]] This contradiction was reconciled in the 1930s by biologists such as Ronald Fisher . The end result was a combination of evolution by natural selection and Mendelian inheritance, the Modern Evolutionary Synthesis .163 In the 1940s, the identification of DNA as the genetic material by Oswald Avery and colleagues and the subsequent publication of the structure of DNA by James Watson and Francis Crick in 1953, demonstrated the physical basis for inheritance. Since then, Genetics and Molecular Biology have become core parts of Evolutionary Biology and have revolutionized the field of Phylogenetics .164 In its early history, evolutionary biology primarily drew in scientists from traditional taxonomically-oriented disciplines, whose specialist training in particular organisms addressed general questions in evolution. As evolutionary biology expanded as an academic discipline, particularly after the development of the modern evolutionary synthesis, it began to draw more widely from the biological sciences. Currently the study of evolutionary biology involves scientists from fields as diverse as Biochemistry , Ecology , Genetics and Physiology , and evolutionary concepts are used in even more distant disciplines such as Psychology , Medicine , Philosophy and Computer Science . SOCIAL AND RELIGIOUS CONTROVERSIES as an Ape , reflecting the cultural backlash against evolution.]]
As Darwin recognized early on, the most controversial aspect of evolutionary thought is its Application To Humans . Specifically, some people object to the idea that humans arose through Natural processes without supernatural intervention. Although Many Religions And Denominations have reconciled their beliefs with evolution through Theological Development , several denominations contain Creationists who object to evolution, as it contradicts their literal interpretation of Origin Belief s.169 In some countries – notably the United States – these tensions between scientific and religious teachings have fueled the ongoing Creation–evolution Controversy , a religious conflict focusing on Politics and Public Education .170 While other scientific fields such as Cosmology 171 and Earth Science 172 also conflict with literal interpretations of many religious texts, evolutionary biology has borne the brunt of religious objection. Evolution has also attracted controversy because it has been used to support philosophical positions that promote Discrimination and Racism . For example, the Eugenic ideas of Francis Galton were developed into arguments that the human gene pool should be improved by Selective Breeding policies, including incentives for those considered "good stock" to reproduce, and the Compulsory Sterilization , Prenatal Testing , Birth Control , and even Killing , of those considered ''bad stock''.173 Another example of an extension of evolutionary theory that is now widely regarded as unwarranted is " Social Darwinism ," a term given to the 19th century Whig Malthusian theory developed by Herbert Spencer into ideas about " Survival Of The Fittest " in commerce and human societies as a whole, and by others into claims that Social Inequality , racism, and Imperialism were justified.On the history of eugenics and evolution, see 174 However, contemporary scientists and philosophers consider these ideas to have been neither mandated by evolutionary theory nor supported by data. Darwin strongly disagreed with attempts by Herbert Spencer and others to extrapolate evolutionary ideas to all possible subjects; see 175176 USES IN TECHNOLOGY A major technological application of the power of evolution is Artificial Selection , which is the intentional selection of certain traits in a population of organisms. Humans have used artificial selection for thousands of years in the Domestication of plants and animals.177 More recently, such selection has become a vital part of Genetic Engineering , with Selectable Marker s such as antibiotic resistance genes being used to manipulate DNA in Molecular Biology . As evolution can produce highly optimized processes and networks, it has many applications in Computer Science . Here, simulations of evolution using Evolutionary Algorithm s and Artificial Life started with the work of Nils Aall Barricelli in the 1960s, and was extended by Alex Fraser , who published a series of papers on simulation of Artificial Selection .178 Artificial Evolution became a widely recognized optimization method as a result of the work of Ingo Rechenberg in the 1960s and early 1970s, who used Evolution Strategies to solve complex engineering problems.179 Genetic Algorithms in particular became popular through the writing of John Holland .180 As academic interest grew, dramatic increases in the power of computers allowed practical applications. Evolution algorithms are now used to solve multi-dimensional problems more quickly than software produced by human designers, and also to optimize the design of systems.181 FURTHER READING Introductory reading History of evolutionary thought Advanced reading EXTERNAL LINKS General information
History of evolutionary thought
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