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Evolution

The tree of life showing the three domains of life on Earth

Evolution is a biological process. It is how living things change over time and how new species develop. The theory of evolution explains how evolution works, and how living and extinct things have come to be the way they are.[1]

The theory of evolution is an essential idea in biology. Theodosius Dobzhansky, a well-known evolutionary biologist, said: "Nothing in biology makes sense except in the light of evolution".[2]

Evolution has been happening since life started on Earth and is happening now. Evolution is caused mostly by natural selection. Living things are not identical to each other. Even living things of the same species look, move, and behave differently to some extent. Some differences make it easier for living things to survive and reproduce.

Differences may make it easier to find food, hide from danger, or give birth to offspring which survive. The offspring will have some of the things which made it easier for their parents to have and raise them. Over time, these good differences continue and are spread through the population. Many generations pass and living things change enough to become new species.

Individuals who have differences that make it harder to find food, have offspring or avoid being eaten are likely not to have offspring at all and so will not give rise to future generations.

It is known that living things have changed over time, because their remains can be seen in the rocks. These remains are called 'fossils'. This proves that the animals and plants of today are different from those of long ago. The older the fossils, the bigger the differences from modern forms.[3] This has happened because evolution has taken place. That evolution has taken place is a fact, because it is overwhelmingly supported by many lines of evidence.[4][5][6] At the same time, evolutionary questions are still being actively researched by biologists.

Comparison of DNA sequences allows organisms to be grouped by how similar their sequences are. In 2010 an analysis compared sequences to phylogenetic trees, and supported the idea of common descent. There is now "strong quantitative support, by a formal test",[7] for the unity of life.[8]

  1. ↑ Mayr, Ernst. 2001. What evolution is. Weidenfeld & Nicolson, London. ISBN 0-465-04426-3
  2. ↑ Dobzhansky, Theodosius 1973. Nothing in biology makes sense except in the light of evolution. American Biology Teacher 35, 125-129. http://www.2think.org/dobzhansky.shtml
  3. ↑ Levin, Harold L. 2005. The Earth through time. 8th ed, Wiley, N.Y. Chapter 6: Life on Earth: what do fossils reveal?
  4. ↑ Futuyma, Douglas J. 1997. Evolutionary biology, 3rd ed. Sinauer Associates. ISBN 0-87893-189-9.
  5. ↑ Dawkins, Richard; Coyne, Jerry (1 September 2005). "One side can be wrong". guardian.co.uk. Retrieved 29 January 2011.
  6. ↑ Muller, H.J. (1959). "One hundred years without Darwin are enough". School Science and Mathematics. 59: 304–305. doi:10.1111/j.1949-8594.1959.tb08235.x. ISSN 0036-6803. Archived from the original on 2016-03-03. Retrieved 2009-11-18. Reprinted in: Zetterberg, Peter, ed. (1983). Evolution versus creationism: the public education controversy. Phoenix AZ: ORYX Press. ISBN 0897740610.
  7. ↑ Theobald, Douglas L. (2010). "A formal test of the theory of universal common ancestry". Nature. 465 (7295): 219–222. Bibcode:2010Natur.465..219T. doi:10.1038/nature09014. PMID 20463738. S2CID 4422345.
  8. ↑ Steel, Mike; Penny, David (2010). "Origins of life: common ancestry put to the test". Nature. 465 (7295): 168–9. Bibcode:2010Natur.465..168S. doi:10.1038/465168a. PMID 20463725. S2CID 205055573.

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