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Do not fill this in! === Evolution of life === {{main|Evolutionary history of life|Timeline of evolutionary history of life}} {{PhylomapA|size=320px|align=right|caption=[[Phylogenetic tree|Evolutionary tree]] showing the divergence of modern species from their common ancestor in the centre.<ref name="Ciccarelli">{{cite journal |last1=Ciccarelli |first1=Francesca D. |last2=Doerks |first2=Tobias |last3=von Mering |first3=Christian |last4=Creevey |first4=Christopher J. |last5=Snel |first5=Berend |last6=Bork |first6=Peer |s2cid=1615592 |author-link6=Peer Bork |date=3 March 2006 |title=Toward Automatic Reconstruction of a Highly Resolved Tree of Life |journal=Science |volume=311 |issue=5765 |pages=1283β1287 |bibcode=2006Sci...311.1283C |doi=10.1126/science.1123061 |issn=0036-8075 |pmid=16513982 |display-authors=3 |url=http://bioinformatics.bio.uu.nl/pdf/Ciccarelli.s06-311.pdf |url-status=live |archive-url=https://web.archive.org/web/20160304035346/http://bioinformatics.bio.uu.nl/pdf/Ciccarelli.s06-311.pdf |archive-date=4 March 2016 |citeseerx=10.1.1.381.9514}}</ref> The three [[Domain (biology)|domains]] are coloured, with bacteria blue, [[archaea]] green and [[eukaryote]]s red.}} Prokaryotes inhabited the Earth from approximately 3β4 billion years ago.<ref name="Cavalier-Smith">{{cite journal |last=Cavalier-Smith |first=Thomas |author-link=Thomas Cavalier-Smith |date=29 June 2006 |title=Cell evolution and Earth history: stasis and revolution |journal=Philosophical Transactions of the Royal Society B |volume=361 |issue=1470 |pages=969β1006 |doi=10.1098/rstb.2006.1842 |issn=0962-8436 |pmc=1578732 |pmid=16754610}}</ref><ref>{{cite journal |last=Schopf |first=J. William |date=29 June 2006 |title=Fossil evidence of Archaean life |journal=Philosophical Transactions of the Royal Society B |volume=361 |issue=1470 |pages=869β885 |doi=10.1098/rstb.2006.1834 |pmc=1578735 |pmid=16754604}} * {{cite journal |last1=Altermann |first1=Wladyslaw |last2=Kazmierczak |first2=JΓ³zef |date=November 2003 |title=Archean microfossils: a reappraisal of early life on Earth |journal=Research in Microbiology |volume=154 |issue=9 |pages=611β617 |doi=10.1016/j.resmic.2003.08.006 |pmid=14596897 |ref=none|doi-access=free }}</ref> No obvious changes in morphology or cellular organisation occurred in these organisms over the next few billion years.<ref>{{cite journal |last=Schopf |first=J. William |date=19 July 1994 |title=Disparate rates, differing fates: tempo and mode of evolution changed from the Precambrian to the Phanerozoic |journal=PNAS |volume=91 |issue=15 |pages=6735β6742 |bibcode=1994PNAS...91.6735S |doi=10.1073/pnas.91.15.6735 |pmc=44277 |pmid=8041691|doi-access=free }}</ref> The eukaryotic cells emerged between 1.6 and 2.7 billion years ago. The next major change in cell structure came when bacteria were engulfed by eukaryotic cells, in a cooperative association called [[endosymbiont|endosymbiosis]].<ref name="rgruqh">{{cite journal |last1=Poole |first1=Anthony M. |last2=Penny |first2=David |date=January 2007 |title=Evaluating hypotheses for the origin of eukaryotes |journal=BioEssays |volume=29 |issue=1 |pages=74β84 |doi=10.1002/bies.20516 |issn=0265-9247 |pmid=17187354}}</ref><ref name="Dyall">{{cite journal |last1=Dyall |first1=Sabrina D. |last2=Brown |first2=Mark T. |last3=Johnson |first3=Patricia J. |s2cid=19424594 |author-link3=Patricia J. Johnson |date=9 April 2004 |title=Ancient Invasions: From Endosymbionts to Organelles |journal=Science |volume=304 |issue=5668 |pages=253β257 |bibcode=2004Sci...304..253D |doi=10.1126/science.1094884 |pmid=15073369}}</ref> The engulfed bacteria and the host cell then underwent coevolution, with the bacteria evolving into either mitochondria or [[hydrogenosome]]s.<ref>{{cite journal |last=Martin |first=William |date=October 2005 |title=The missing link between hydrogenosomes and mitochondria |journal=Trends in Microbiology |volume=13 |issue=10 |pages=457β459 |doi=10.1016/j.tim.2005.08.005 |pmid=16109488}}</ref> Another engulfment of [[cyanobacteria]]l-like organisms led to the formation of chloroplasts in algae and plants.<ref>{{cite journal |last1=Lang |first1=B. Franz |last2=Gray |first2=Michael W. |last3=Burger |first3=Gertraud |date=December 1999 |title=Mitochondrial genome evolution and the origin of eukaryotes |journal=[[Annual Review of Genetics]] |volume=33 |pages=351β397 |doi=10.1146/annurev.genet.33.1.351 |issn=0066-4197 |pmid=10690412}} * {{cite journal |last=McFadden |first=Geoffrey Ian |date=1 December 1999 |title=Endosymbiosis and evolution of the plant cell |journal=Current Opinion in Plant Biology |volume=2 |issue=6 |pages=513β519 |doi=10.1016/S1369-5266(99)00025-4 |pmid=10607659 |bibcode=1999COPB....2..513M |ref=none}}</ref> The history of life was that of the [[Unicellular organism|unicellular]] eukaryotes, prokaryotes and archaea until about 610 million years ago when multicellular organisms began to appear in the oceans in the [[Ediacara biota|Ediacaran]] period.<ref name="Cavalier-Smith" /><ref>{{cite journal |last1=DeLong |first1=Edward F. |author-link1=Edward DeLong |last2=Pace |first2=Norman R. |author-link2=Norman R. Pace |date=1 August 2001 |title=Environmental Diversity of Bacteria and Archaea |url=https://archive.org/details/sim_systematic-biology_2001-08_50_4/page/470 |journal=[[Systematic Biology]] |volume=50 |issue=4 |pages=470β478 |doi=10.1080/106351501750435040 |issn=1063-5157 |pmid=12116647 |citeseerx=10.1.1.321.8828}}</ref> The [[Multicellular evolution|evolution of multicellularity]] occurred in multiple independent events, in organisms as diverse as [[sponge]]s, [[brown algae]], cyanobacteria, [[Slime mold|slime moulds]] and [[myxobacteria]].<ref>{{cite journal |last=Kaiser |first=Dale |s2cid=18276422 |author-link=A. Dale Kaiser |date=December 2001 |title=Building a multicellular organism |journal=[[Annual Review of Genetics]] |volume=35 |pages=103β123 |doi=10.1146/annurev.genet.35.102401.090145 |issn=0066-4197 |pmid=11700279}}</ref> In January 2016, scientists reported that, about 800 million years ago, a minor genetic change in a single molecule called GK-PID may have allowed organisms to go from a single cell organism to one of many cells.<ref name="NYT-20160107">{{cite news |last=Zimmer |first=Carl |author-link=Carl Zimmer |title=Genetic Flip Helped Organisms Go From One Cell to Many |url=https://www.nytimes.com/2016/01/12/science/genetic-flip-helped-organisms-go-from-one-cell-to-many.html |date=7 January 2016 |newspaper=The New York Times |location=New York |issn=0362-4331 |access-date=7 January 2016 |url-status=live |archive-url=https://web.archive.org/web/20160107204432/http://www.nytimes.com/2016/01/12/science/genetic-flip-helped-organisms-go-from-one-cell-to-many.html |archive-date=7 January 2016}}</ref> Soon after the emergence of these first multicellular organisms, a remarkable amount of biological diversity appeared over approximately 10 million years, in an event called the [[Cambrian explosion]]. Here, the majority of [[Phylum|types]] of modern animals appeared in the fossil record, as well as unique lineages that subsequently became extinct.<ref name="Valentine_1999">{{cite journal |last1=Valentine |first1=James W. |author-link1=James W. Valentine |last2=Jablonski |first2=David |last3=Erwin |first3=Douglas H. |author-link3=Douglas Erwin |date=1 March 1999 |title=Fossils, molecules and embryos: new perspectives on the Cambrian explosion |url=http://dev.biologists.org/content/126/5/851.full.pdf+html |journal=[[Development (journal)|Development]] |volume=126 |issue=5 |pages=851β859 |doi=10.1242/dev.126.5.851 |issn=0950-1991 |pmid=9927587 |access-date=30 December 2014 |url-status=live |archive-url=https://web.archive.org/web/20150301063309/http://dev.biologists.org/content/126/5/851.full.pdf+html |archive-date=1 March 2015}}</ref> Various triggers for the Cambrian explosion have been proposed, including the accumulation of oxygen in the atmosphere from photosynthesis.<ref>{{cite journal |last=Ohno |first=Susumu |s2cid=21879320 |date=January 1997 |title=The reason for as well as the consequence of the Cambrian explosion in animal evolution |journal=Journal of Molecular Evolution |volume=44 |issue=Suppl. 1 |pages=S23βS27 |doi=10.1007/PL00000055 |issn=0022-2844 |pmid=9071008|bibcode=1997JMolE..44S..23O}} * {{cite journal |last1=Valentine |first1=James W. |last2=Jablonski |first2=David |title=Morphological and developmental macroevolution: a paleontological perspective |url=http://www.ijdb.ehu.es/web/paper.php?doi=14756327 |year=2003 |journal=The International Journal of Developmental Biology |volume=47 |issue=7β8 |pages=517β522 |issn=0214-6282 |pmid=14756327 |access-date=30 December 2014 |url-status=live |archive-url=https://web.archive.org/web/20141024234611/http://www.ijdb.ehu.es/web/paper.php?doi=14756327 |archive-date=24 October 2014 |ref=none}}</ref> About 500 million years ago, plants and fungi colonised the land and were soon followed by arthropods and other animals.<ref>{{cite journal |last=Waters |first=Elizabeth R. |date=December 2003 |title=Molecular adaptation and the origin of land plants |journal=[[Molecular Phylogenetics and Evolution]] |volume=29 |issue=3 |pages=456β463 |doi=10.1016/j.ympev.2003.07.018 |issn=1055-7903 |pmid=14615186}}</ref> Insects were particularly successful and even today make up the majority of animal species.<ref>{{cite journal |last=Mayhew |first=Peter J. |author-link=Peter Mayhew (biologist) |date=August 2007 |title=Why are there so many insect species? Perspectives from fossils and phylogenies |url=https://archive.org/details/sim_biological-reviews_2007-08_82_3/page/425 |journal=Biological Reviews |volume=82 |issue=3 |pages=425β454 |doi=10.1111/j.1469-185X.2007.00018.x |issn=1464-7931 |pmid=17624962|s2cid=9356614 }}</ref> [[Amphibian]]s first appeared around 364 million years ago, followed by early [[amniote]]s and birds around 155 million years ago (both from "reptile"-like lineages), [[mammal]]s around 129 million years ago, [[Homininae]] around 10 million years ago and [[Anatomically modern humans|modern humans]] around 250,000 years ago.<ref>{{cite journal |last=Carroll |first=Robert L. |author-link=Robert L. Carroll |date=May 2007 |title=The Palaeozoic Ancestry of Salamanders, Frogs and Caecilians |journal=[[Zoological Journal of the Linnean Society]] |volume=150 |issue=Supplement s1 |pages=1β140 |doi=10.1111/j.1096-3642.2007.00246.x |issn=1096-3642|doi-access=free }}</ref><ref>{{cite journal |last1=Wible |first1=John R. |last2=Rougier |first2=Guillermo W. |last3=Novacek |first3=Michael J. |last4=Asher |first4=Robert J. |date=21 June 2007 |title=Cretaceous eutherians and Laurasian origin for placental mammals near the K/T boundary |url=https://archive.org/details/sim_nature-uk_2007-06-21_447_7147/page/1003 |journal=Nature |volume=447 |issue=7147 |pages=1003β1006 |bibcode=2007Natur.447.1003W |doi=10.1038/nature05854 |issn=0028-0836 |pmid=17581585|s2cid=4334424 }}</ref><ref>{{cite journal |last=Witmer |first=Lawrence M. |s2cid=205066360 |author-link=Lawrence Witmer |date=28 July 2011 |title=Palaeontology: An icon knocked from its perch |journal=Nature |volume=475 |issue=7357 |pages=458β459 |doi=10.1038/475458a |issn=0028-0836 |pmid=21796198}}</ref> However, despite the evolution of these large animals, smaller organisms similar to the types that evolved early in this process continue to be highly successful and dominate the Earth, with the majority of both biomass and species being prokaryotes.<ref name="Schloss" /> Summary: Please note that all contributions to Christianpedia may be edited, altered, or removed by other contributors. 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