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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 [[reproductive isolation|prevented from interbreeding]], mutations, genetic drift, and the selection of novel traits cause the accumulation of differences over generations and the emergence of [[speciation|new species]]. Stephen Gould, The Structure of Evolutionary Theory, Belknap Press, ISBN 0-674-00613-5 . The similarities between organisms suggest that all known species are [[common descent|descended from a common ancestor]] (or ancestral gene pool) through this process of gradual divergence. {Douglas J. Futuyma, Evolution, Sinauer Associates, Sunderland, Massachusetts,  ISBN 0-87893-187-2 )

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 [[reproductive isolation|prevented from interbreeding]], mutations, genetic drift, and the selection of novel traits cause the accumulation of differences over generations and the emergence of [[speciation|new species]]. Stephen Gould, The Structure of Evolutionary Theory, Belknap Press, ISBN 0-674-00613-5 . The similarities between organisms suggest that all known species are [[common descent|descended from a common ancestor]] (or ancestral gene pool) through this process of gradual divergence. {Douglas J. Futuyma, Evolution, Sinauer Associates, Sunderland, Massachusetts,  ISBN 0-87893-187-2 )

[[Image:Darwin_tree_sm.jpg|left]]

[[Image:Darwin_tree_sm.jpg|left]]

The [[Theory#Science|theory]] of evolution by natural selection was first proposed by [[Charles Darwin]] and [[Alfred Russel Wallace]] and set out in detail in Darwin's 1859 book ''[[The Origin of Species|On the Origin of Species]]''. On the Origin of Species [http://darwin-online.org.uk/content/frameset?itemID=F373&viewtype=text&pageseq=16]. Related earlier ideas were acknowledged in http://darwin-online.org.uk/content/frameset?itemID=F381&viewtype=text&pageseq=20] In the 1930s, Darwinian natural selection was combined with [[Gregor Mendel|Mendelian]] [[Mendelian inheritance|inheritance]] to form the [[modern evolutionary synthesis]], "understanding evolution"  in which the connection between the ''units'' of evolution ([[gene]]s) and the ''mechanism'' of evolution (natural selection) was made. This powerful explanatory and [[predictive power|predictive]] theory has become the central organizing principle of modern biology, providing a unifying explanation for the [[biodiversity|diversity of life]] on Earth. [http://www.interacademies.net/Object.File/Master/6/150/Evolution%20statement.pdf] Statement on the Teaching of Evolution, The Interacademy Panel on International Issues, [http://www.aaas.org/news/releases/2006/pdf/0219boardstatement.pdf] Statement on the Teaching of Evolution, American Association for the Advancement of Science.  

The [[Theory#Science|theory]] of evolution by natural selection was first proposed by [[Charles Darwin]] and [[Alfred Russel Wallace]] and set out in detail in Darwin's 1859 book ''[[The Origin of Species|On the Origin of Species]]''. On the Origin of Species [http://darwin-online.org.uk/content/frameset?itemID=F373&viewtype=text&pageseq=16]. Related earlier ideas were acknowledged in http://darwin-online.org.uk/content/frameset?itemID=F381&viewtype=text&pageseq=20] In the 1930s, Darwinian natural selection was combined with [[Gregor Mendel|Mendelian]] [[Mendelian inheritance|inheritance]] to form the [[modern evolutionary synthesis]], "understanding evolution"  in which the connection between the ''units'' of evolution ([[gene]]s) and the ''mechanism'' of evolution (natural selection) was made. This powerful explanatory and [[predictive power|predictive]] theory has become the central organizing principle of modern biology, providing a unifying explanation for the [[biodiversity|diversity of life]] on Earth. [http://www.interacademies.net/Object.File/Master/6/150/Evolution%20statement.pdf] Statement on the Teaching of Evolution, The Interacademy Panel on International Issues, *http://www.aaas.org/news/releases/2006/pdf/0219boardstatement.pdf] Statement on the Teaching of Evolution, American Association for the Advancement of Science.  

 

==Heredity==

==Heredity==

===Common descent===

===Common descent===

All [[organisms]] on [[Earth]] are descended from a common ancestor or ancestral gene pool.  Current species are a stage in the process of evolution, with their diversity the product of a long series of speciation and extinction events.  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.

All [[organisms]] on [[Earth]] are descended from a common ancestor or ancestral gene pool.  Current species are a stage in the process of evolution, with their diversity the product of a long series of speciation and extinction events.  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.

===Evolution of life===

===Evolution of life===

Despite the uncertainty on how life began, it is clear that [[prokaryote]]s were the first organisms to inhabit Earth,[http://www.journals.royalsoc.ac.uk/content/0164755512w92302/fulltext.pdf]  approximately 3 - 4 billion years ago.  No obvious changes in [[morphology (biology)|morphology]] or cellular organization occurred in these organisms over the next few billion years. [http://www.pnas.org/cgi/reprint/91/15/6735]  

Despite the uncertainty on how life began, it is clear that [[prokaryote]]s were the first organisms to inhabit Earth,[http://www.journals.royalsoc.ac.uk/content/0164755512w92302/fulltext.pdf]  approximately 3 - 4 billion years ago.  No obvious changes in [[morphology (biology)|morphology]] or cellular organization occurred in these organisms over the next few billion years. [http://www.pnas.org/cgi/reprint/91/15/6735]  

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 (scientist)|Alex Fraser]], who published a series of papers on simulation of [[artificial selection]]. [[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. [[Genetic algorithms]] in particular became popular through the writing of [[John Henry Holland|John Holland]]. Adaptation in Natural and Artificial Systems, University of Michigan Press, ISBN 0262581116 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.

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 (scientist)|Alex Fraser]], who published a series of papers on simulation of [[artificial selection]]. [[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. [[Genetic algorithms]] in particular became popular through the writing of [[John Henry Holland|John Holland]]. Adaptation in Natural and Artificial Systems, University of Michigan Press, ISBN 0262581116 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.

==Further reading==

==Further reading==

==External links==

==External links==

'''General information'''

'''General information'''

* [http://evolution.berkeley.edu/ Understanding Evolution from University of California, Berkeley]

* [http://evolution.berkeley.edu/ Understanding Evolution from University of California, Berkeley]

* [http://nationalacademies.org/evolution/ National Academies Evolution Resources]

* [http://nationalacademies.org/evolution/ National Academies Evolution Resources]