Editing Evolution (section)

=== Origin of life ===
{{Further|Abiogenesis|Earliest known life forms|Panspermia|RNA world hypothesis}}

The Earth is [[Age of Earth|about 4.54&nbsp;billion years old]].<ref name="USGS-2007">{{cite web |url=http://pubs.usgs.gov/gip/geotime/age.html |title=Age of the Earth |date=9 July 2007 |publisher=[[United States Geological Survey]] |access-date=31 May 2015 |url-status=live |archive-url=https://web.archive.org/web/20051223072700/http://pubs.usgs.gov/gip/geotime/age.html |archive-date=23 December 2005}}</ref><ref name="Dalrymple-2001">{{harvnb|Dalrymple|2001|pp=205–221}}</ref><ref name="Manhesa-1980">{{cite journal |last1=Manhesa |first1=Gérard |last2=Allègre |first2=Claude J. |author-link2=Claude Allègre |last3=Dupréa |first3=Bernard |last4=Hamelin |first4=Bruno |date=May 1980 |title=Lead isotope study of basic-ultrabasic layered complexes: Speculations about the age of the earth and primitive mantle characteristics |url=https://archive.org/details/sim_earth-and-planetary-science-letters_1980-05_47_3/page/370 |journal=[[Earth and Planetary Science Letters]] |volume=47 |issue=3 |pages=370–382 |bibcode=1980E&PSL..47..370M |doi=10.1016/0012-821X(80)90024-2 |issn=0012-821X}}</ref> The earliest undisputed evidence of life on Earth dates from at least 3.5&nbsp;billion years ago,<ref name="Schopf-2007">{{cite journal |last1=Schopf |first1=J. William |author-link1=J. William Schopf |last2=Kudryavtsev |first2=Anatoliy B. |last3=Czaja |first3=Andrew D. |last4=Tripathi |first4=Abhishek B. |date=5 October 2007 |title=Evidence of Archean life: Stromatolites and microfossils |journal=[[Precambrian Research]] |volume=158 |pages=141–155 |issue=3–4 |doi=10.1016/j.precamres.2007.04.009 |issn=0301-9268 |bibcode=2007PreR..158..141S}}</ref><ref name="RavenJohnson2002">{{harvnb|Raven|Johnson|2002|p=68}}</ref> during the [[Eoarchean]] Era after a geological [[Crust (geology)|crust]] started to solidify following the earlier molten [[Hadean]] Eon. Microbial mat fossils have been found in 3.48&nbsp;billion-year-old sandstone in Western Australia.<ref name="Borenstein-2013">{{cite news |last=Borenstein |first=Seth |date=13 November 2013 |title=Oldest fossil found: Meet your microbial mom |url=http://apnews.excite.com/article/20131113/DAA1VSC01.html |work=[[Excite (web portal)|Excite]] |location=Yonkers, New York |publisher=[[Mindspark Interactive Network]] |agency=[[Associated Press]] |access-date=31 May 2015 |url-status=live |archive-url=https://web.archive.org/web/20150629230719/http://apnews.excite.com/article/20131113/DAA1VSC01.html |archive-date=29 June 2015}}</ref><ref name="Pearlman-2013">{{cite news |last=Pearlman |first=Jonathan |date=13 November 2013 |title=Oldest signs of life on Earth found |url=https://www.telegraph.co.uk/news/science/science-news/10445788/Oldest-signs-of-life-on-Earth-found.html |newspaper=[[The Daily Telegraph]] |location=London |access-date=15 December 2014 |url-status=live |archive-url=https://web.archive.org/web/20141216062531/http://www.telegraph.co.uk/news/science/science-news/10445788/Oldest-signs-of-life-on-Earth-found.html |archive-date=16 December 2014}}</ref><ref name="Noffke-2013">{{cite journal |last1=Noffke |first1=Nora |author1-link=Nora Noffke |last2=Christian |first2=Daniel |last3=Wacey |first3=David |last4=Hazen |first4=Robert M. |author-link4=Robert Hazen |date=16 November 2013 |title=Microbially Induced Sedimentary Structures Recording an Ancient Ecosystem in the ''ca.'' 3.48 Billion-Year-Old Dresser Formation, Pilbara, Western Australia |journal=[[Astrobiology (journal)|Astrobiology]] |volume=13 |issue=12 |pages=1103–1124 |bibcode=2013AsBio..13.1103N |doi=10.1089/ast.2013.1030 |issn=1531-1074 |pmc=3870916 |pmid=24205812}}</ref> Other early physical evidence of a biogenic substance is graphite in 3.7&nbsp;billion-year-old [[metasediment]]ary rocks discovered in Western Greenland<ref name="Ohtomo-2014">{{cite journal |last1=Ohtomo |first1=Yoko |last2=Kakegawa |first2=Takeshi |last3=Ishida |first3=Akizumi |last4=Nagase |first4=Toshiro |last5=Rosing |first5=Minik T. |display-authors=3 |date=January 2014 |title=Evidence for biogenic graphite in early Archaean Isua metasedimentary rocks |journal=[[Nature Geoscience]] |volume=7 |issue=1 |pages=25–28 |bibcode=2014NatGe...7...25O |doi=10.1038/ngeo2025 |issn=1752-0894}}</ref> as well as "remains of [[biotic life]]" found in 4.1&nbsp;billion-year-old rocks in Western Australia.<ref name="Borenstein-2015">{{cite news |last=Borenstein |first=Seth |title=Hints of life on what was thought to be desolate early Earth |url=http://apnews.excite.com/article/20151019/us-sci--earliest_life-a400435d0d.html |date=19 October 2015 |work=[[Excite (web portal)|Excite]] |location=Yonkers, NY |publisher=[[Mindspark Interactive Network]] |agency=[[Associated Press]] |archive-url=https://web.archive.org/web/20151023200248/http://apnews.excite.com/article/20151019/us-sci--earliest_life-a400435d0d.html |archive-date=23 October 2015 |access-date=8 October 2018}}</ref><ref name="Bell-2015">{{cite journal |last1=Bell |first1=Elizabeth A. |last2=Boehnike |first2=Patrick |last3=Harrison |first3=T. Mark |last4=Mao |first4=Wendy L. |author4-link=Wendy Mao |date=24 November 2015 |title=Potentially biogenic carbon preserved in a 4.1 billion-year-old zircon |url=http://www.pnas.org/content/early/2015/10/14/1517557112.full.pdf |journal=PNAS |volume=112 |issue=47 |pages=14518–14521 |doi=10.1073/pnas.1517557112 |issn=0027-8424 |access-date=30 December 2015 |pmid=26483481 |pmc=4664351 |bibcode=2015PNAS..11214518B |url-status=live |archive-url=https://web.archive.org/web/20151106021508/http://www.pnas.org/content/early/2015/10/14/1517557112.full.pdf |archive-date=6 November 2015 |doi-access=free}}</ref> Commenting on the Australian findings, [[Stephen Blair Hedges]] wrote: "If life arose relatively quickly on Earth, then it could be common in the universe."<ref name="Borenstein-2015" /><ref>{{cite news |last=Schouten |first=Lucy |date=20 October 2015 |title=When did life first emerge on Earth? Maybe a lot earlier than we thought |url=https://www.csmonitor.com/Science/2015/1020/When-did-life-first-emerge-on-Earth-Maybe-a-lot-earlier-than-we-thought |work=[[The Christian Science Monitor]] |location=Boston, Massachusetts |publisher=[[Christian Science Publishing Society]] |issn=0882-7729 |archive-url=https://web.archive.org/web/20160322214217/http://www.csmonitor.com/Science/2015/1020/When-did-life-first-emerge-on-Earth-Maybe-a-lot-earlier-than-we-thought |archive-date=22 March 2016 |url-status=live |access-date=11 July 2018}}</ref> <!---Nevertheless, [[Late Heavy Bombardment#Geological consequences on Earth|several studies]] suggest that life on Earth may have started even earlier,<ref name="AB-20021014">{{cite web |last=Tenenbaum |first=David |title=When Did Life on Earth Begin? Ask a Rock |url=http://www.astrobio.net/exclusive/293/when-did-life-on-earth-begin-ask-a-rock |date=14 October 2002 |work=Astrobiology Magazine |access-date=13 April 2014 |archive-url=https://web.archive.org/web/20210628022131/https://www.astrobio.net/news-exclusive/when-did-life-on-earth-begin-ask-a-rock/ |archive-date=28 June 2021 |url-status=usurped}}</ref> as early as 4.25 billion years ago according to one study,<ref name="NS-20080702">{{cite web |last=Courtland |first=Rachel |title=Did newborn Earth harbour life? |url=https://www.newscientist.com/article/dn14245-did-newborn-earth-harbour-life.html |date=2 July 2008 |work=[[New Scientist]] |access-date=13 April 2014}}</ref> and 4.4 billion years ago according to another study.<ref name="RN-20090520">{{cite web |last=Steenhuysen |first=Julie |title=Study turns back clock on origins of life on Earth |url=https://www.reuters.com/article/2009/05/20/us-asteroids-idUSTRE54J5PX20090520 |date=20 May 2009 |work=[[Reuters]] |access-date=13 April 2014}}</ref>---> In July 2016, scientists reported identifying a set of 355 [[gene]]s from the [[last universal common ancestor]] (LUCA) of all organisms living on Earth.<ref name="Wade-2016">{{cite news |last=Wade |first=Nicholas |author-link=Nicholas Wade |title=Meet Luca, the Ancestor of All Living Things |url=https://www.nytimes.com/2016/07/26/science/last-universal-ancestor.html |date=25 July 2016 |newspaper=[[The New York Times]] |location=New York |issn=0362-4331 |access-date=25 July 2016 |url-status=live |archive-url=https://web.archive.org/web/20160728053822/http://www.nytimes.com/2016/07/26/science/last-universal-ancestor.html |archive-date=28 July 2016}}</ref>

More than 99% of all species, amounting to over five billion species,<ref name="Book-Biology">{{harvnb|McKinney|1997|p=[https://books.google.com/books?id=4LHnCAAAQBAJ&pg=PA110 110]}}</ref> that ever lived on Earth are estimated to be extinct.<ref name="Stearns-1999" /><ref name="Novacek-2014">{{cite news |last=Novacek |first=Michael J. |date=8 November 2014 |title=Prehistory's Brilliant Future |url=https://www.nytimes.com/2014/11/09/opinion/sunday/prehistorys-brilliant-future.html |newspaper=The New York Times |location=New York |issn=0362-4331 |access-date=25 December 2014 |url-status=live |archive-url=https://web.archive.org/web/20141229225657/http://www.nytimes.com/2014/11/09/opinion/sunday/prehistorys-brilliant-future.html |archive-date=29 December 2014}}</ref> Estimates on the number of Earth's current species range from 10&nbsp;million to 14&nbsp;million,<ref name="Mora-2011">{{cite journal |last1=Mora |first1=Camilo |last2=Tittensor |first2=Derek P. |last3=Adl |first3=Sina |last4=Simpson |first4=Alastair G. B. |last5=Worm |first5=Boris |author-link5=Boris Worm |display-authors=3 |date=23 August 2011 |title=How Many Species Are There on Earth and in the Ocean? |journal=PLOS Biology |volume=9 |issue=8 |page=e1001127 |doi=10.1371/journal.pbio.1001127 |issn=1545-7885 |pmc=3160336 |pmid=21886479 |doi-access=free}}</ref><ref name="Miller">{{harvnb|Miller|Spoolman|2012|p=[https://books.google.com/books?id=NYEJAAAAQBAJ&pg=PA62 62]}}</ref> of which about 1.9&nbsp;million are estimated to have been named<ref name="Chapman2009">{{harvnb|Chapman|2009}}</ref> and 1.6&nbsp;million documented in a central database to date,<ref name="Roskov-2016">{{cite web |url=http://www.catalogueoflife.org/annual-checklist/2016/info/ac |title=Species 2000 & ITIS Catalogue of Life, 2016 Annual Checklist |year=2016 |editor-last=Roskov |editor-first=Y. |editor2-last=Abucay |editor2-first=L. |editor3-last=Orrell |editor3-first=T. |editor4-last=Nicolson |editor4-first=D. |editor5-last=Flann |editor5-first=C. |editor6-last=Bailly |editor6-first=N. |editor7-last=Kirk |editor7-first=P. |editor8-last=Bourgoin |editor8-first=T. |editor9-last=DeWalt |editor9-first=R. E. |editor10-last=Decock |editor10-first=W. |editor11-last=De Wever |editor11-first=A. |display-editors=4 |website=Species 2000 |publisher=[[Naturalis Biodiversity Center]] |location=Leiden, Netherlands |issn=2405-884X |access-date=6 November 2016 |url-status=live |archive-url=https://web.archive.org/web/20161112121623/http://www.catalogueoflife.org/annual-checklist/2016/info/ac |archive-date=12 November 2016}}</ref> leaving at least 80% not yet described.

Highly energetic chemistry is thought to have produced a self-replicating molecule around 4&nbsp;billion years ago, and half a billion years later the last common ancestor of all life existed.<ref name="Doolittle-2000" /> The current scientific consensus is that the complex biochemistry that makes up life came from simpler chemical reactions.<ref>{{cite journal |last=Peretó |first=Juli |date=March 2005 |title=Controversies on the origin of life |url=http://www.im.microbios.org/0801/0801023.pdf |journal=International Microbiology |volume=8 |issue=1 |pages=23–31 |issn=1139-6709 |pmid=15906258 |archive-url=https://web.archive.org/web/20150824074726/http://www.im.microbios.org/0801/0801023.pdf |archive-date=24 August 2015}}</ref><ref name="BBC-20201111">{{cite news |last=Marshall |first=Michael |title=Charles Darwin's hunch about early life was probably right – In a few scrawled notes to a friend, biologist Charles Darwin theorised how life began. Not only was it probably correct, his theory was a century ahead of its time. |url=https://www.bbc.com/future/article/20201110-charles-darwin-early-life-theory |date=11 November 2020 |work=[[BBC News]] |access-date=11 November 2020 |archive-date=11 November 2020 |archive-url=https://web.archive.org/web/20201111015900/https://www.bbc.com/future/article/20201110-charles-darwin-early-life-theory |url-status=live}}</ref> The beginning of life may have included self-replicating molecules such as [[RNA]]<ref>{{cite journal |last=Joyce |first=Gerald F. |author-link=Gerald Joyce |date=11 July 2002 |title=The antiquity of RNA-based evolution |journal=Nature |volume=418 |issue=6894 |pages=214–221 |bibcode=2002Natur.418..214J |doi=10.1038/418214a |pmid=12110897 |s2cid=4331004}}</ref> and the assembly of simple cells.<ref>{{cite journal |last1=Trevors |first1=Jack T. |last2=Psenner |first2=Roland |date=December 2001 |title=From self-assembly of life to present-day bacteria: a possible role for nanocells |journal=FEMS Microbiology Reviews |volume=25 |issue=5 |pages=573–582 |doi=10.1111/j.1574-6976.2001.tb00592.x |issn=1574-6976 |pmid=11742692 |doi-access=free}}</ref>