View source for Extinction

{{Short description|Termination of an organism by the death of its last member}}
{{Redirect|Extinct|other uses|Extinct (disambiguation)|and|Extinction (disambiguation)|lists|Lists of extinct species}}
{{Use dmy dates|date=July 2022}}
[[File:Thylacinus cynocephalus (Gould).jpg|thumb|The [[thylacine]] (''Thylacinus cynocephalus'') is an example of a recently extinct [[species]].]]
[[File:Museum of Natural History Palaeotherium magnum.jpg|thumb|''[[Palaeotherium]]'' is an example of an extinct [[genus]] that is only recorded from fossil records before the existence of [[Hominid|hominids]].]]
{{Conservation status}}
{{Evolutionary biology}}
'''Extinction''' is the termination of an [[organism]] by the [[death]] of its [[Endling|last member]]. A [[taxon]] may become [[Functional extinction|functionally extinct]] before the death of its last member if it loses the capacity to [[Reproduction|reproduce]] and recover. As a [[species]]' potential [[Range (biology)|range]] may be very large, determining this moment is difficult, and is usually done retrospectively. This difficulty leads to phenomena such as [[Lazarus taxon|Lazarus taxa]], where a species presumed extinct abruptly "reappears" (typically in the [[Fossil|fossil record]]) after a period of apparent absence.

Over five billion species<ref name=":0">{{cite book |doi=10.1007/978-94-011-5874-9_7 |chapter=How do rare species avoid extinction? A paleontological view |title=The Biology of Rarity |year=1997 |last1=McKinney |first1=Michael L. |pages=110–129 |isbn=978-94-010-6483-5 |editor1-last=Kunin |editor1-first=W. E. |editor2-last=Gaston |editor2-first=K. J. |chapter-url=https://books.google.com/books?id=4LHnCAAAQBAJ&pg=PA110 |access-date=26 May 2015 |archive-date=3 February 2023 |archive-url=https://web.archive.org/web/20230203051637/https://books.google.com/books?id=4LHnCAAAQBAJ&pg=PA110 |url-status=live}}</ref> are estimated to have [[died]] out.<ref name="Jablonski2004">{{cite journal |title=Extinction: past and present |last=Jablonski |first=D. |journal=Nature |year=2004 |volume=427 |issue=6975 |page=589 |doi=10.1038/427589a |pmid=14961099 |bibcode=2004Natur.427..589J |s2cid=4412106 |doi-access=free}}</ref><ref name="StearnsStearns2000">{{cite book |last1=Stearns |first1=Beverly Peterson |last2=Stearns |first2=S.C. |last3=Stearns |first3=Stephen C. |title=Watching, from the Edge of Extinction |url=https://books.google.com/books?id=0BHeC-tXIB4C&q=99%20percent |year=2000 |publisher=[[Yale University Press]] |isbn=978-0-300-08469-6 |page=preface x |access-date=30 May 2017 |archive-date=3 February 2023 |archive-url=https://web.archive.org/web/20230203051614/https://books.google.com/books?id=0BHeC-tXIB4C&q=99%20percent |url-status=live}}</ref><ref name="NYT-20141108-MJN">{{cite news |last=Novacek |first=Michael J. |author-link=Michael J. Novacek |title=Prehistory's Brilliant Future |url=https://www.nytimes.com/2014/11/09/opinion/sunday/prehistorys-brilliant-future.html |date=8 November 2014 |work=[[The New York Times]] |access-date=2014-12-25 |archive-date=29 December 2014 |archive-url=https://web.archive.org/web/20141229225657/http://www.nytimes.com/2014/11/09/opinion/sunday/prehistorys-brilliant-future.html |url-status=live}}</ref><ref name="Newman" /> It is estimated that there are currently around 8.7&nbsp;million species of [[eukaryote]]s globally,<ref name="PLoSbiologyspeciescensus">{{Cite journal |doi=10.1371/journal.pbio.1001127 |title=How Many Species Are There on Earth and in the Ocean? |year=2011 |last1=Mora |first1=Camilo |last2=Tittensor |first2=Derek P. |last3=Adl |first3=Sina |last4=Simpson |first4=Alastair G. B. |last5=Worm |first5=Boris |journal=PLOS Biology |volume=9 |issue=8 |article-number=e1001127 |pmid=21886479 |pmc=3160336 |doi-access=free}}</ref> possibly many times more if [[microorganism]]s are included.<ref name="NSF-2016002">{{cite news |author=<!--Staff writer(s); no by-line.--> |title=Researchers find that Earth may be home to one trillion species |url=https://www.nsf.gov/news/news_summ.jsp?cntn_id=138446 |date=2 May 2016 |work=[[National Science Foundation]] |access-date=6 May 2016 |archive-date=4 May 2016 |archive-url=https://web.archive.org/web/20160504111108/https://www.nsf.gov/news/news_summ.jsp?cntn_id=138446 |url-status=live}}</ref> Notable extinct animal species include [[Dinosaur|non-avian dinosaurs]], [[Machairodontinae|saber-toothed cats]], and [[mammoth]]s. Through [[evolution]], species arise through the process of [[speciation]]. Species become extinct when they are no longer able to survive in changing conditions or against superior [[Competition (biology)|competition]]. The relationship between animals and their ecological niches has been firmly established.<ref name="SahneyBentonFerry2010LinksDiversityVertebrates">{{cite journal |last1=Sahney |first1=S. |last2=Benton |first2=M.J. |last3=Ferry |first3=P.A. |year=2010 |title=Links between global taxonomic diversity, ecological diversity and the expansion of vertebrates on land |journal=Biology Letters |doi=10.1098/rsbl.2009.1024 |volume=6 |pages=544–547 |issue=4 |pmid=20106856 |pmc=2936204}}</ref> A typical species becomes extinct within 10&nbsp;million years of its first appearance,<ref name="Newman">{{cite journal |last1=Newman |first1=Mark |year=1997 |title=''A model of mass extinction'' |journal=Journal of Theoretical Biology |volume=189 |issue=3 |pages=235–252 |doi=10.1006/jtbi.1997.0508 |pmid=9441817 |arxiv=adap-org/9702003 |bibcode=1997JThBi.189..235N |s2cid=9892809}}</ref> although some species, called [[living fossil]]s, survive with little to no [[morphology (biology)|morphological]] change for hundreds of millions of years, though this claim has been disputed.<ref name="Casane">{{Cite journal|title = Why coelacanths are not 'living fossils'|journal = BioEssays|date = 2013-04-01|issn = 1521-1878|pages = 332–338|volume = 35|issue = 4|doi = 10.1002/bies.201200145|language = en|first1 = Didier|last1 = Casane|first2 = Patrick|last2 = Laurenti|pmid=23382020|s2cid = 2751255|doi-access = free}}</ref><ref>{{Cite journal|title = Multiple global radiations in tadpole shrimps challenge the concept of 'living fossils'|journal = PeerJ|pmc = 3628881|pmid = 23638400|volume = 1|doi = 10.7717/peerj.62|first1 = Thomas C.|last1 = Mathers|first2 = Robert L.|last2 = Hammond|first3 = Ronald A.|last3 = Jenner|first4 = Bernd|last4 = Hänfling|first5 = Africa|last5 = Gómez|pages=e62|year = 2013 | doi-access=free }}</ref><ref>{{Cite journal|title = Relict species: a relict concept?|journal = Trends in Ecology & Evolution|date = 2014-01-12|issn = 0169-5347|pmid = 25454211|pages = 655–663|volume = 29|issue = 12|doi = 10.1016/j.tree.2014.10.002|language = en|first1 = Philippe|last1 = Grandcolas|first2 = Romain|last2 = Nattier|first3 = Steve|last3 = Trewick| bibcode=2014TEcoE..29..655G }}</ref>

[[Extinction event|Mass extinctions]] are relatively rare events; however, isolated extinctions of species and clades are quite common, and are a natural part of the evolutionary process.<ref name="Sudakow2022">{{cite journal |last1=Sudakow |first1=Ivan |last2=Myers |first2=Corinne |last3=Petrovskii |first3=Sergei |last4=Sumrall |first4=Colin D. |last5=Witts |first5=James |date=July 2022 |title=Knowledge gaps and missing links in understanding mass extinctions: Can mathematical modeling help? |journal=Physics of Life Reviews |volume=41 |pages=22–57 |doi=10.1016/j.plrev.2022.04.001 |pmid=35523056 |bibcode=2022PhLRv..41...22S |s2cid=248215038 |doi-access=free}}</ref> Only recently have extinctions begun to be recorded, and there is an [[Holocene extinction#Contemporary extinction|ongoing mass extinction event]] caused by human activity.<ref name="MSNBC">{{cite news |title=Species disappearing at an alarming rate, report says |url=https://www.nbcnews.com/id/wbna6502368 |work=NBC News |date=17 November 2004 |access-date=9 February 2022 |archive-date=9 February 2022 |archive-url=https://web.archive.org/web/20220209131517/https://www.nbcnews.com/id/wbna6502368 |url-status=live}}</ref><ref>{{YouTube|z9gHuAwxwAs|The Sixth Extinction}} ([[PBS Digital Studios]], November 17, 2014)</ref><ref>{{cite journal |last1=Ceballos |first1=Gerardo |last2=Ehrlich |first2=Paul R. |last3=Barnosky |first3=Anthony D. |author-link3=Anthony David Barnosky |last4=García |first4=Andrés |last5=Pringle |first5=Robert M. |last6=Palmer |first6=Todd M. |year=2015 |title=Accelerated modern human–induced species losses: Entering the sixth mass extinction |journal=[[Science Advances]] |volume=1 |issue=5 |article-number=e1400253 |doi=10.1126/sciadv.1400253 |pmid=26601195 |pmc=4640606 |bibcode=2015SciA....1E0253C}}</ref><ref>{{cite journal |vauthors=Ripple WJ, Wolf C, Newsome TM, Galetti M, Alamgir M, Crist E, Mahmoud MI, Laurance WF |title=World Scientists' Warning to Humanity: A Second Notice |journal=[[BioScience]] |date=13 November 2017 |volume=67 |issue=12 |pages=1026–1028 |doi=10.1093/biosci/bix125 |quote=Moreover, we have unleashed a mass extinction event, the sixth in roughly 540 million years, wherein many current life forms could be annihilated or at least committed to extinction by the end of this century. |title-link=World Scientists' Warning to Humanity |doi-access=free |hdl=11336/71342 |hdl-access=free}}</ref><ref>{{cite journal |last1=Cowie |first1=Robert H. |last2=Bouchet |first2=Philippe |last3=Fontaine |first3=Benoît |title=The Sixth Mass Extinction: fact, fiction or speculation? |journal=Biological Reviews |date=10 January 2022 |volume=97 |issue=2 |pages=640–663 |doi=10.1111/brv.12816 |pmid=35014169 |pmc=9786292 |s2cid=245889833 |url=https://hal.sorbonne-universite.fr/hal-03525883/document |doi-access=free |access-date=9 February 2022 |archive-date=9 February 2022 |archive-url=https://web.archive.org/web/20220209132106/https://hal.sorbonne-universite.fr/hal-03525883/document |url-status=live}}</ref> Most species that become extinct are never scientifically documented. Some scientists estimate that up to half of presently existing plant and animal species may become extinct by 2100.<ref name="Wilson">[[E.O. Wilson|Wilson, E.O.]], ''The Future of Life'' (2002) ({{ISBN|0-679-76811-4}}). See also: [[Richard Leakey|Leakey, Richard]], ''The Sixth Extinction : Patterns of Life and the Future of Humankind'', {{ISBN|0-385-46809-1}}</ref> A 2018 report indicated that the [[Phylogenetics|phylogenetic diversity]] of 300 mammalian species erased during the human era since the [[Late Pleistocene]] would require 5 to 7&nbsp;million years to recover.<ref name="davis2018">{{cite journal |pmid=30322924 |pmc=6217385 |doi=10.1073/pnas.1804906115 |journal=Proc Natl Acad Sci |year=2018 |volume=115 |issue=44 |pages=11262–11267 |title=Mammal diversity will take millions of years to recover from the current biodiversity crisis |vauthors=Davis M, Faurby S, Svenning JC |bibcode=2018PNAS..11511262D |doi-access=free}}</ref>

According to the 2019 ''[[Global Assessment Report on Biodiversity and Ecosystem Services]]'' by [[IPBES]], the biomass of wild mammals has fallen by 82%, natural ecosystems have lost about half their area and a million species are at risk of extinction—all largely as a result of human actions. Twenty-five percent of plant and animal species are [[Threatened species|threatened]] with extinction.<ref>{{cite news |last=Watts |first=Jonathan |date=May 6, 2019 |title=Human society under urgent threat from loss of Earth's natural life |url=https://www.theguardian.com/environment/2019/may/06/human-society-under-urgent-threat-loss-earth-natural-life-un-report |work=[[The Guardian]] |access-date=May 6, 2019 |archive-date=14 June 2019 |archive-url=https://web.archive.org/web/20190614160705/https://www.theguardian.com/environment/2019/may/06/human-society-under-urgent-threat-loss-earth-natural-life-un-report |url-status=live}}</ref><ref name="NYT-20190506">{{cite news |last=Plumer |first=Brad |title=Humans Are Speeding Extinction and Altering the Natural World at an 'Unprecedented' Pace |url=https://www.nytimes.com/2019/05/06/climate/biodiversity-extinction-united-nations.html |date=May 6, 2019 |work=[[The New York Times]] |access-date=May 6, 2019 |archive-date=14 June 2019 |archive-url=https://web.archive.org/web/20190614201836/https://www.nytimes.com/2019/05/06/climate/biodiversity-extinction-united-nations.html |url-status=live}}</ref><ref name="IPBES-20190506">{{cite news |author=<!--Staff writer(s); no by-line.--> |title=Media Release: Nature's Dangerous Decline 'Unprecedented'; Species Extinction Rates 'Accelerating' |url=https://www.ipbes.net/news/Media-Release-Global-Assessment |date=May 6, 2019 |work=[[Intergovernmental Science-Policy Platform on Biodiversity and Ecosystem Services]] |access-date=May 6, 2019 |archive-date=14 June 2019 |archive-url=https://web.archive.org/web/20190614220133/https://www.ipbes.net/news/Media-Release-Global-Assessment |url-status=live}}</ref> In a subsequent report, IPBES listed unsustainable fishing, hunting and logging as being some of the primary drivers of the global extinction crisis.<ref>{{cite news |last=Briggs |first=Helen |date=July 8, 2022 |title=Unsustainable logging, fishing and hunting 'driving extinction' |url=https://www.bbc.com/news/science-environment-62094405 |work=BBC |location= |access-date=August 2, 2022 |archive-date=1 August 2022 |archive-url=https://web.archive.org/web/20220801105751/https://www.bbc.com/news/science-environment-62094405 |url-status=live}}</ref>  In June 2019, one million species of plants and animals were at risk of extinction. At least 571 plant species have been lost since 1750. The main cause of the extinctions is the destruction of natural habitats by human activities, such as cutting down forests and converting land into fields for farming.<ref>{{cite web |url=https://www.theguardian.com/environment/2019/jun/10/frightening-number-of-plant-extinctions-found-in-global-survey |title='Frightening' number of plant extinctions found in global survey |website=The Guardian |date=10 June 2019 |access-date=11 June 2019 |archive-date=22 April 2021 |archive-url=https://web.archive.org/web/20210422133201/https://www.theguardian.com/environment/2019/jun/10/frightening-number-of-plant-extinctions-found-in-global-survey |url-status=live}}</ref>

A [[Dagger (mark)|dagger symbol]] (†) placed next to the name of a species or other taxon normally indicates its status as extinct.

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==Definition==
[[File:LepidodendronOhio.jpg|thumb|right|External mold of the extinct ''[[Lepidodendron]]'' from the [[Upper Carboniferous]] of [[Ohio]]<ref>{{cite book |last1=Kenrick |first1=Paul |last2=Davis |first2=Paul |title=Fossil Plants |date=2004 |publisher=Smithsonian Books |isbn=978-0-565-09176-7}}{{page needed|date=February 2022}}</ref><ref>{{cite book |last1=Moran |first1=Robbin Craig |title=A Natural History of Ferns |date=2004 |publisher=Timber Press |isbn=978-0-88192-667-5}}{{page needed|date=February 2022}}</ref>]]
A species is extinct when the last existing member dies. Extinction therefore becomes a certainty when there are no surviving individuals that can reproduce and create a new generation. A species may become [[functional extinction|functionally extinct]] when only a handful of individuals survive, which cannot reproduce due to poor health, age, sparse distribution over a large range, a lack of individuals of both sexes (in [[sexual reproduction|sexually reproducing]] species), or other reasons.

Pinpointing the extinction (or [[pseudoextinction]]) of a species requires a [[Theory of species|clear definition of that species]]. If it is to be declared extinct, the species in question must be uniquely distinguishable from any ancestor or daughter species, and from any other closely related species. Extinction of a species (or replacement by a daughter species) plays a key role in the [[punctuated equilibrium]] hypothesis of [[Stephen Jay Gould]] and [[Niles Eldredge]].<ref>See: Niles Eldredge, ''Time Frames: Rethinking of Darwinian Evolution and the Theory of Punctuated Equilibria'', 1986, Heinemann {{ISBN|0-434-22610-6}}</ref>

[[File:Various dinosaurs.png|thumb|left|Skeleton of various extinct [[dinosaur]]s; some other dinosaur lineages still flourish in the form of [[birds]]]]
In [[ecology]], ''extinction'' is sometimes used informally to refer to [[local extinction]], in which a species ceases to exist in the chosen area of study, despite still existing elsewhere. Local extinctions may be made good by the reintroduction of individuals of that species taken from other locations; [[wolf reintroduction]] is an example of this. Species that are not globally extinct are termed [[Extant taxon|extant]]. Those species that are extant, yet are threatened with extinction, are referred to as [[threatened]] or [[endangered species]].

[[File:Edwards' Dodo.jpg|thumb|The [[dodo]] of [[Mauritius]], shown here in a 1626 illustration by [[Roelant Savery]], is an often-cited example of [[Holocene extinction|modern extinction]].<ref name="Diamond">{{cite book |last=Diamond |first=Jared |author-link=Jared Diamond |title=Guns, Germs, and Steel |publisher=W.W. Norton |year=1999 |isbn=978-0-393-31755-8 |pages=[https://archive.org/details/gunsgermssteelfa00diam/page/43 43–44] |chapter=Up to the Starting Line |title-link=Guns, Germs, and Steel}}</ref>]]
Currently, an important aspect of extinction is human attempts to preserve critically endangered species. These are reflected by the creation of the [[conservation status]] [[extinct in the wild|"extinct in the wild" (EW)]]. Species listed under this status by the [[International Union for Conservation of Nature]] (IUCN) are not known to have any living specimens in the wild and are maintained only in [[zoo]]s or other artificial environments. Some of these species are functionally extinct, as they are no longer part of their natural habitat and it is unlikely the species will ever be restored to the wild.<ref name="Maas">Maas, Peter. "[http://www.petermaas.nl/extinct/wilduk.htm Extinct in the Wild" ''The Extinction Website''. URL accessed January 26 2007.] {{webarchive |url=https://web.archive.org/web/20070216030551/http://www.petermaas.nl/extinct/wilduk.htm |date=February 16, 2007 }}</ref> When possible, modern [[zoology|zoological]] institutions try to maintain a [[viable population]] for species preservation and possible future [[reintroduction]] to the wild, through use of carefully planned [[breeding program]]s.

The extinction of one species' wild population can have knock-on effects, causing further extinctions. These are also called "chains of extinction".<ref>{{cite journal |last1=Quince |first1=Christopher |last2=Higgs |first2=Paul G. |last3=McKane |first3=Alan J. |title=Deleting species from model food webs |journal=Oikos |date=August 2005 |volume=110 |issue=2 |pages=283–296 |doi=10.1111/j.0030-1299.2005.13493.x |arxiv=q-bio/0401037 |bibcode=2005Oikos.110..283Q |s2cid=16750824}}</ref> This is especially common with extinction of [[keystone species]].

A 2018 study indicated that the [[sixth mass extinction]] started in the [[Late Pleistocene]] could take up to 5 to 7&nbsp;million years to restore mammal diversity to what it was before the human era.<ref name=davis2018/><ref>{{cite news |last1=Mosbergen |first1=Dominique |title=Mammals Will Still Be Recovering From Human Destruction Long After We're Gone |url=https://www.huffpost.com/entry/mammal-diversity-extinction-study_n_5bc59f68e4b055bc94796ecf |work=HuffPost |date=16 October 2018 |access-date=9 February 2022 |archive-date=9 February 2022 |archive-url=https://web.archive.org/web/20220209131519/https://www.huffpost.com/entry/mammal-diversity-extinction-study_n_5bc59f68e4b055bc94796ecf |url-status=live}}</ref>

===Pseudoextinction===
{{Main|Pseudoextinction}}

Extinction of a parent species where daughter species or subspecies are still extant is called pseudoextinction or phyletic extinction. Effectively, the old taxon vanishes, transformed ([[anagenesis]]) into a successor,<ref>{{cite book |last1=King |first1=Michael |last2=Mulligan |first2=Pamela |last3=Stansfield |first3=William |title=A Dictionary of Genetics |chapter=Pseudoextinction |date=2014 |publisher=Oxford University Press |edition=8th |isbn=978-0-19-976644-4 |url=https://www.oxfordreference.com/display/10.1093/acref/9780199766444.001.0001/acref-9780199766444-e-5536?rskey=f8g543&result=5527 |access-date=12 November 2023 |archive-date=21 March 2024 |archive-url=https://web.archive.org/web/20240321194758/https://www.oxfordreference.com/display/10.1093/acref/9780199766444.001.0001/acref-9780199766444-e-5536?rskey=f8g543&result=5527 |url-status=live}}</ref> or split into more than one ([[cladogenesis]]).<ref>{{Cite journal |last=Leighton |first=Lindsey R. |title=Taxon Characteristics That Promote Survivorship Through the Permian-Triassic Interval: Transition from the Paleozoic to the Mesozoic Brachiopod Fauna |journal=Paleobiology |date=2009 |volume=34 |pages=65–79 |doi=10.1666/06082.1 |s2cid=86843206}}</ref>

Pseudoextinction is difficult to demonstrate unless one has a strong chain of evidence linking a living species to members of a pre-existing species. For example, it is sometimes claimed that the extinct ''[[Hyracotherium]]'', which was an early horse that shares a common ancestor with the modern [[horse]], is pseudoextinct, rather than extinct, because there are several extant species of ''[[Equus (genus)|Equus]]'', including [[zebra]] and [[donkey]]; however, as fossil species typically leave no genetic material behind, one cannot say whether ''Hyracotherium'' [[Evolution of the horse|evolved into more modern horse species]] or merely evolved from a common ancestor with modern horses. Pseudoextinction is much easier to demonstrate for larger taxonomic groups.

===Lazarus taxa===
{{Main|Lazarus taxon}}
A Lazarus taxon or Lazarus species refers to instances where a species or taxon was thought to be extinct, but was later rediscovered. It can also refer to instances where large gaps in the fossil record of a taxon result in fossils reappearing much later, although the taxon may have ultimately become extinct at a later point.

The [[coelacanth]], a fish related to [[lungfish]] and [[tetrapod]]s, is an example of a Lazarus taxon that was known only from the fossil record and was considered to have been extinct since the end of the [[Cretaceous Period]]. In 1938, however, a living specimen was found off the [[Chalumna River]] (now Tyolomnqa) on the east coast of South Africa.<ref name="dinofish">{{cite web |url=http://www.dinofish.com/discoa.htm |title="Discovery" of the Coelacanth |access-date=2 March 2013 |archive-date=21 January 2013 |archive-url=https://archive.today/20130121205250/http://www.dinofish.com/discoa.htm |url-status=live}}</ref> ''[[Calliostoma bullatum]]'', a species of deepwater [[sea snail]] originally described from fossils in 1844 proved to be a Lazarus species when extant individuals were described in 2019.<ref>{{Cite journal |last1=Freiwald |first1=André |last2=Lavaleye |first2=Marc |last3=Heugten |first3=Bart Van |last4=Beuck |first4=Lydia |last5=Hoffman |first5=Leon |date=4 June 2019 |title=Last snails standing since the Early Pleistocene, a tale of Calliostomatidae (Gastropoda) living in deep-water coral habitats in the north-eastern Atlantic |journal=Zootaxa |language=en |volume=4613 |issue=1 |pages=93–110 |doi=10.11646/zootaxa.4613.1.4 |pmid=31716426 |issn=1175-5334 |doi-access=free}}</ref>

[[Zaglossus attenboroughi|Attenborough's long-beaked echidna]] (''Zaglossus attenboroughi'') is an example of a Lazarus species from [[Papua New Guinea]] that had last been sighted in 1962 and believed to be possibly extinct, until it was recorded again in November 2023.<ref>{{Cite news |date=2023-11-10 |title=First-ever images prove 'lost echidna' not extinct |language=en-GB |url=https://www.bbc.com/news/science-environment-67363874 |access-date=2023-11-25}}</ref>

Some species thought to be extinct have had ongoing speculation that they may still exist, and in the event of rediscovery would be considered Lazarus species. Examples include the [[thylacine]], or Tasmanian tiger (''Thylacinus cynocephalus''), the last known example of which died in Hobart Zoo in Tasmania in 1936; the [[Honshū wolf|Japanese wolf]] (''Canis lupus hodophilax''), last sighted over 100 years ago; the [[Ivory-billed woodpecker|American ivory-billed woodpecker]] (''Campephilus principalis''), with the last universally accepted sighting in 1944; and the [[slender-billed curlew]] (''Numenius tenuirostris''), not seen since 2007.<ref>{{cite web |last1=Platt |first1=John R. |title=4 Extinct Species That People Still Hope to Rediscover |url=https://blogs.scientificamerican.com/extinction-countdown/4-extinct-species-hope-rediscover/ |work=Scientific American Blog Network |date=21 February 2013 |access-date=9 February 2022 |archive-date=9 February 2022 |archive-url=https://web.archive.org/web/20220209131524/https://blogs.scientificamerican.com/extinction-countdown/4-extinct-species-hope-rediscover/ |url-status=live}}{{self-published inline|date=February 2022}}</ref>

==Causes==
[[File:Ectopistes migratoriusMCN2P28CA.jpg|thumb|upright|The [[passenger pigeon]], one of the hundreds of species of extinct birds, was hunted to extinction over the course of a few decades.]]

As long as species have been evolving, species have been going extinct. It is estimated that over 99.9% of all species that ever lived are extinct. The average lifespan of a species is 1–10&nbsp;million years,<ref>{{Cite book |title=Conservation of Wildlife Populations: Demography, Genetics and Management |url=https://books.google.com/books?id=fVLEV64qYfcC |publisher=John Wiley & Sons |year=2009 |isbn=978-1-4443-0893-8 |language=en |first=L. Scott |last=Mills |page=13}}</ref> although this varies widely between taxa.
A variety of causes can contribute directly or indirectly to the extinction of a species or group of species. "Just as each species is unique", write Beverly and [[Stephen C. Stearns]], "so is each extinction&nbsp;... the causes for each are varied—some subtle and complex, others obvious and simple".<ref name="Stearns">{{cite book |last=Stearns |first=Beverly Peterson and Stephen C. |title=Watching, from the Edge of Extinction |publisher=Yale University Press |year=2000 |isbn=978-0-300-08469-6 |page=x |chapter=Preface |url=https://archive.org/details/isbn_9780300084696}}</ref> Most simply, any species that cannot [[Survival skills|survive]] and [[reproduction|reproduce]] in its environment and cannot move to a new environment where it can do so, dies out and becomes extinct. Extinction of a species may come suddenly when an otherwise healthy species is wiped out completely, as when [[toxic]] [[pollution]] renders its entire [[habitat]] unliveable; or may occur gradually over thousands or millions of years, such as when a species gradually loses out in competition for food to better adapted competitors. Extinction may occur a long time after the events that set it in motion, a phenomenon known as [[extinction debt]].

Assessing the relative importance of genetic factors compared to environmental ones as the causes of extinction has been compared to the debate on [[nature and nurture]].<ref name="Raup">{{cite journal |last=Raup |first=David M. |author2=J. John Sepkoski Jr. |s2cid=43002817 |date=March 1982 |title=Mass extinctions in the marine fossil record |journal=Science |volume=215 |issue=4539 |pages=1501–1503 |doi=10.1126/science.215.4539.1501 |pmid=17788674 |bibcode=1982Sci...215.1501R}}</ref> The question of whether more extinctions in the [[fossil]] record have been caused by [[evolution]] or by competition or by predation or by disease or by catastrophe is a subject of discussion; Mark Newman, the author of ''Modeling Extinction'', argues for a mathematical model that falls in all positions.<ref name="Newman" /> By contrast, [[conservation biology]] uses the [[extinction vortex]] model to classify extinctions by cause. When concerns about [[human extinction]] have been raised, for example in Sir [[Martin Rees]]' 2003 book ''[[Our Final Hour]]'', those concerns lie with the effects of [[climate change]] or [[technology|technological]] disaster.

Human-driven extinction started as humans migrated out of Africa more than 60,000 years ago.<ref>{{cite journal |editor1-last=Johns |editor1-first=David |editor2-last=Crist |editor2-first=Eileen |editor3-last=Sahgal |editor3-first=Bittu |date=2022 |title=Ending the Colonization of the Non-Human World |url=https://www.sciencedirect.com/journal/biological-conservation/special-issue/10574WDL8SQ |journal=[[Biological Conservation (journal)|Biological Conservation]] |volume= |issue= |pages= |doi= |archive-date=18 November 2022 |archive-url=https://web.archive.org/web/20221118015916/https://www.sciencedirect.com/journal/biological-conservation/special-issue/10574WDL8SQ |url-status=live}}</ref> Currently, environmental groups and some governments are concerned with the extinction of species caused by humanity, and they try to prevent further extinctions through a variety of [[conservation movement|conservation]] programs.<ref name="MSNBC" /> Humans can cause extinction of a species through [[overharvesting]], [[pollution]], [[habitat destruction]], introduction of [[invasive species]] (such as new [[predator]]s and food [[competitors]]), overhunting, and other influences. Explosive, unsustainable human [[population growth]] and [[Overconsumption|increasing per capita consumption]] are essential drivers of the extinction crisis.<ref name="Ceballos2017"/><ref>{{cite journal |last1=Stokstad |first1=Erik |title=Landmark analysis documents the alarming global decline of nature |journal=Science |date=6 May 2019 |doi=10.1126/science.aax9287 |s2cid=166478506}}</ref><ref>{{cite journal |last1=Andermann |first1=Tobias |last2=Faurby |first2=Søren |last3=Turvey |first3=Samuel T. |last4=Antonelli |first4=Alexandre |last5=Silvestro |first5=Daniele |title=The past and future human impact on mammalian diversity |journal=Science Advances |date=1 September 2020 |volume=6 |issue=36 |article-number=eabb2313 |doi=10.1126/sciadv.abb2313 |pmid=32917612 |s2cid=221498762 |doi-access=free |pmc=7473673 |bibcode=2020SciA....6.2313A}} [[File:CC-BY icon.svg|50px]]  Text and images are available under a [https://creativecommons.org/licenses/by/4.0/  Creative Commons Attribution 4.0 International License] {{Webarchive|url=https://web.archive.org/web/20171016050101/https://creativecommons.org/licenses/by/4.0/ |date=16 October 2017 }}.</ref><ref>{{cite news |last=Lewis |first=Sophie |date=September 9, 2020 |title=Animal populations worldwide have declined by almost 70% in just 50 years, new report says |url=https://www.cbsnews.com/news/biodiversity-endangered-species-animal-population-decline-world-wildlife-fund-report-2020-09-09/ |work=[[CBS News]] |access-date=October 22, 2020 |archive-date=10 September 2020 |archive-url=https://web.archive.org/web/20200910152119/https://www.cbsnews.com/news/biodiversity-endangered-species-animal-population-decline-world-wildlife-fund-report-2020-09-09/ |url-status=live}}</ref> According to the [[International Union for Conservation of Nature]] (IUCN), 784 extinctions have been recorded since the year 1500, the arbitrary date selected to define "recent" extinctions, up to the year 2004; with many more likely to have gone unnoticed. Several species have also been listed as extinct since 2004.<ref name="IUCNno">{{cite web |publisher=[[World Conservation Union]] |url=http://www.iucn.org/themes/ssc/red_list_2004/GSAexecsumm_EN.htm |archive-url=https://web.archive.org/web/20060827093621/http://www.iucn.org/themes/ssc/red_list_2004/GSAexecsumm_EN.htm |archive-date=27 August 2006 |title=2004 Red List |work=IUCN Red List of Threatened Species |access-date=September 20, 2006}}</ref>

=== Genetics and demographic phenomena ===
{{See also|Extinction vortex|Genetic erosion|Mutational meltdown}}
If [[adaptation]] increasing population [[fitness (biology)|fitness]] is slower than [[environmental degradation]] plus the accumulation of slightly deleterious [[mutation]]s, then a population will go extinct.<ref>{{cite journal |last1=Bertram |first1=J |last2=Gomez |first2=K |last3=Masel |first3=J |title=Predicting patterns of long-term adaptation and extinction with population genetics |journal=Evolution |date=February 2017 |volume=71 |issue=2 |pages=204–214 |doi=10.1111/evo.13116 |pmid=27868195 |arxiv=1605.08717 |s2cid=4705439}}</ref> Smaller populations have fewer beneficial mutations entering the population each generation, slowing adaptation. It is also easier for slightly deleterious mutations to [[fixation (population genetics)|fix]] in small populations; the resulting positive feedback loop between small population size and low fitness can cause [[mutational meltdown]].

Limited geographic range is the most important determinant of [[genus]] extinction at background rates but becomes increasingly irrelevant as [[#Mass extinctions|mass extinction]] arises.<ref>{{cite journal |author1=Payne, J.L. |author2=S. Finnegan |year=2007 |title=The effect of geographic range on extinction risk during background and mass extinction |journal=[[PNAS|Proc. Natl. Acad. Sci.]] |volume=104 |issue=25 |pages=10506–10511 |doi=10.1073/pnas.0701257104 |pmid=17563357 |pmc=1890565 |bibcode=2007PNAS..10410506P |doi-access=free}}</ref> Limited geographic range is a cause both of small population size and of greater vulnerability to local environmental catastrophes.

Extinction rates can be affected not just by population size, but by any factor that affects [[evolvability]], including [[balancing selection]], [[cryptic genetic variation]], [[phenotypic plasticity]], and [[robustness (evolution)|robustness]]. A diverse or deep [[gene pool]] gives a population a higher chance in the short term of surviving an adverse change in conditions. Effects that cause or reward a loss in [[genetic diversity]] can increase the chances of extinction of a species. [[Population bottleneck]]s can dramatically reduce genetic diversity by severely limiting the number of reproducing individuals and make [[inbreeding]] more frequent.

=== Genetic pollution ===
{{Main|Genetic pollution}}
Extinction sometimes results for species evolved to specific ecologies<ref>{{cite journal |last=Mooney |first=H.A. |author2=Cleland, E.E. |year=2001 |title=The evolutionary impact of invasive species |journal=[[Proceedings of the National Academy of Sciences|PNAS]] |volume=98 |issue=10 |pages=5446–5451 |doi=10.1073/pnas.091093398 |pmid=11344292 |pmc=33232 |bibcode=2001PNAS...98.5446M |doi-access=free}}</ref> that are subjected to [[genetic pollution]]—i.e., uncontrolled [[Hybrid (biology)|hybridization]], [[introgression]] and genetic swamping that lead to homogenization or [[Fitness (biology)|out-competition]] from the introduced ([[Heterosis|or hybrid]]) species.<ref>{{cite web |url=http://www.nativeseednetwork.org/article_view?id=13 |title=Glossary: definitions from the following publication: Aubry, C., R. Shoal and V. Erickson. 2005. Grass cultivars: their origins, development, and use on national forests and grasslands in the Pacific Northwest. USDA Forest Service. 44 pages, plus appendices.; Native Seed Network (NSN), Institute for Applied Ecology, 563 SW Jefferson Ave, Corvallis, OR 97333, USA |archive-url=https://web.archive.org/web/20060222092651/http://www.nativeseednetwork.org/article_view?id=13 |archive-date=22 February 2006 }}</ref> Endemic populations can face such extinctions when new populations are imported or [[selective breeding|selectively bred]] by people, or when habitat modification brings previously isolated species into contact. Extinction is likeliest for [[rare species]] coming into contact with more abundant ones;<ref name="RareEucalypts"/> [[interbreeding]] can swamp the rarer gene pool and create hybrids, depleting the purebred gene pool (for example, the endangered [[wild water buffalo]] is most threatened with extinction by genetic pollution from [[Water buffalo|the abundant domestic water buffalo]]). Such extinctions are not always apparent from [[morphology (biology)|morphological]] (non-genetic) observations. Some degree of [[gene flow]] is a normal evolutionary process; nevertheless, hybridization (with or without introgression) threatens rare species' existence.<ref>{{cite journal |title=Extinction by Hybridization and Introgression |first1=J.M. |last1=Rhymer |first2=D. |last2=Simberloff |journal=Annual Review of Ecology and Systematics |date=November 1996 |volume=27 |issue=1 |pages=83–109 |doi=10.1146/annurev.ecolsys.27.1.83 |publisher=Annual Reviews |quote=Introduced species, in turn, are seen as competing with or preying on native species or destroying their habitat. Introduces species (or [[subspecies]]), however, can generate another kind of extinction, a genetic extinction by hybridization and introgression with native flora and fauna |jstor=2097230 |bibcode=1996AnRES..27...83R}}</ref><ref>{{cite book |title=Genetic pollution from farm forestry using eucalypt species and hybrids: a report for the RIRDC/L&WA/FWPRDC Joint Venture Agroforestry Program |first1=Brad M. |last1=Potts |others=Robert C. Barbour, Andrew B. Hingston |date=September 2001 |isbn=978-0-642-58336-9 |publisher=Australian Government, Rural Industrial Research and Development Corporation}}</ref>

The gene pool of a [[species]] or a [[population]] is the variety of genetic information in its living members. A large gene pool (extensive [[genetic diversity]]) is associated with robust populations that can survive bouts of intense [[Selection (biology)|selection]]. Meanwhile, low genetic diversity (see [[inbreeding]] and [[population bottlenecks]]) reduces the range of adaptions possible.<ref>
{{cite web |url=http://adl.brs.gov.au/data/warehouse/brsShop/data/12858_10_1_3.pdf |title=Genetic diversity |page=104 |year=2003 |access-date=2010-05-30 |quote=In other words, greater genetic diversity can offer greater resilience. In order to maintain the capacity of our forests to [[adaption|adapt]] to future changes, therefore, genetic diversity must be preserved |archive-url=https://web.archive.org/web/20110313092336/http://adl.brs.gov.au/data/warehouse/brsShop/data/12858_10_1_3.pdf |archive-date=2011-03-13}}</ref> Replacing native with alien genes narrows genetic diversity within the original population,<ref name="RareEucalypts">
{{cite web |url=http://adl.brs.gov.au/data/warehouse/brsShop/data/12858_10_1_3.pdf |title=Australia's state of the forests report |page=107 |year=2003 |archive-url=https://web.archive.org/web/20110313092336/http://adl.brs.gov.au/data/warehouse/brsShop/data/12858_10_1_3.pdf |archive-date=2011-03-13}}</ref><ref>{{cite journal |last1=Lindenmayer |first1=D. B. |last2=Hobbs |first2=R. J. |last3=Salt |first3=D. |title=Plantation forests and biodiversity conservation |journal=Australian Forestry |date=January 2003 |volume=66 |issue=1 |pages=62–66 |doi=10.1080/00049158.2003.10674891 |bibcode=2003AuFor..66...62L |s2cid=53968395 |url=https://researchrepository.murdoch.edu.au/id/eprint/4637/1/plantation_forests.pdf |access-date=9 February 2022 |archive-date=17 February 2022 |archive-url=https://web.archive.org/web/20220217143102/https://researchrepository.murdoch.edu.au/id/eprint/4637/1/plantation_forests.pdf |url-status=live}}</ref> thereby increasing the chance of extinction.

=== Habitat degradation ===
{{Main|Habitat destruction}}
[[File:DirkvdM santa fe scorched.jpg|thumb|upright=1.2|Scorched land resulting from [[slash-and-burn]] agriculture]]
Habitat degradation is currently the main anthropogenic cause of species extinctions. The main cause of habitat degradation worldwide is agriculture, with [[urban sprawl]], logging, mining, and some fishing practices close behind. The degradation of a species' [[habitat (ecology)|habitat]] may alter the [[fitness landscape]] to such an extent that the species is no longer able to survive and becomes extinct. This may occur by direct effects, such as the environment becoming [[toxicity|toxic]], or indirectly, by limiting a species' ability to compete effectively for diminished resources or against new competitor species.

Habitat destruction, particularly the removal of vegetation that stabilizes soil, enhances erosion and diminishes nutrient availability in terrestrial ecosystems. This degradation can lead to a reduction in agricultural productivity. Furthermore, increased erosion contributes to poorer water quality by elevating the levels of sediment and pollutants in rivers and streams.<ref>{{Cite web |title=Habitat loss / restoration |url=https://ugc.berkeley.edu/background-content/habitat-loss-restoration/ |access-date=2024-04-12 |website=Understanding Global Change |language=en-US}}</ref>

Habitat degradation through toxicity can kill off a species very rapidly, by killing all living members through [[contamination]] or [[Sterilization (microbiology)|sterilizing]] them. It can also occur over longer periods at lower toxicity levels by affecting life span, reproductive capacity, or competitiveness.

Habitat degradation can also take the form of a physical destruction of niche habitats. The widespread destruction of [[tropical rainforest]]s and replacement with open pastureland is widely cited as an example of this;<ref name="Wilson" /> elimination of the dense forest eliminated the infrastructure needed by many species to survive. For example, a [[fern]] that depends on dense shade for protection from direct sunlight can no longer survive without forest to shelter it. Another example is the destruction of ocean floors by [[bottom trawling]].<ref>{{cite book |last=Clover |first=Charles |year=2004 |title=The End of the Line: How overfishing is changing the world and what we eat |publisher=Ebury Press |location=London |isbn=978-0-09-189780-2}}</ref>

Diminished resources or introduction of new competitor species also often accompany habitat degradation. [[Global warming]] has allowed some species to expand their range, bringing competition to other species that previously occupied that area. Sometimes these new competitors are predators and directly affect prey species, while at other times they may merely outcompete vulnerable species for limited resources. Vital resources including [[water]] and food can also be limited during habitat degradation, leading to extinction.

=== Predation, competition, and disease ===
{{See also|Island restoration}}
[[File:Bufo periglenes2.jpg|thumb|The [[golden toad]] was last seen on May 15, 1989. [[Decline in amphibian populations]] is ongoing worldwide.]]
In the natural course of events, species become extinct for a number of reasons, including but not limited to: extinction of a necessary host, prey or pollinator, [[interspecific competition]], inability to deal with evolving diseases and changing environmental conditions (particularly sudden changes) which can act to introduce novel predators, or to remove prey. Recently in geological time, humans have become an additional cause of extinction of some species, either as a new mega-predator or by [[introduced species|transporting]] [[animal]]s and [[plant]]s from one part of the world to another. Such introductions have been occurring for thousands of years, sometimes intentionally (e.g. [[livestock]] released by sailors on islands as a future source of food) and sometimes accidentally (e.g. [[rat]]s escaping from boats). In most cases, the introductions are unsuccessful, but when an [[Invasive species|invasive alien species]] does become established, the consequences can be catastrophic. Invasive alien species can affect [[Endemic (ecology)|native]] species directly by eating them, competing with them, and introducing [[pathogen]]s or [[parasite]]s that sicken or kill them; or indirectly by destroying or degrading their habitat. Human populations may themselves act as invasive predators. According to the "overkill hypothesis", the swift extinction of the [[megafauna]] in areas such as Australia (40,000 years before present), [[North America|North]] and [[South America]] (12,000 years before present), [[Madagascar]], [[Hawaii]] (AD 300–1000), and New Zealand (AD 1300–1500), resulted from the sudden introduction of human beings to environments full of animals that had never seen them before and were therefore completely unadapted to their predation techniques.<ref name="Lee">Lee, Anita. "[http://geography.berkeley.edu/ProgramCourses/CoursePagesFA2002/geog148/Term%20Papers/Anita%20Lee/THEPLE~1.html The Pleistocene Overkill Hypothesis] {{webarchive |url=https://web.archive.org/web/20061014100508/http://geography.berkeley.edu/ProgramCourses/CoursePagesFA2002/geog148/Term%20Papers/Anita%20Lee/THEPLE~1.html |date=October 14, 2006 }}." ''University of California at Berkeley Geography Program.'' Retrieved January 11, 2007.</ref>

=== Coextinction ===
{{Main|Coextinction}}
[[File:Giant Haasts eagle attacking New Zealand moa.jpg|thumb|The large [[Haast's eagle]] and [[moa]] from New Zealand]]

Coextinction refers to the loss of a species due to the extinction of another; for example, the extinction of [[parasitism|parasitic]] insects following the loss of their hosts. Coextinction can also occur when a species loses its [[pollinator]], or to [[predator]]s in a [[food chain]] who lose their prey. "Species coextinction is a manifestation of one of the interconnectednesses of organisms in complex ecosystems&nbsp;... While coextinction may not be the most important cause of species extinctions, it is certainly an insidious one."<ref name="Koh">{{cite journal |last1=Koh |first1=Lian Pin |last2=Dunn |first2=Robert R. |last3=Sodhi |first3=Navjot S. |last4=Colwell |first4=Robert K. |last5=Proctor |first5=Heather C. |last6=Smith |first6=Vincent S. |title=Species Coextinctions and the Biodiversity Crisis |journal=Science |date=10 September 2004 |volume=305 |issue=5690 |pages=1632–1634 |doi=10.1126/science.1101101 |pmid=15361627 |bibcode=2004Sci...305.1632K |s2cid=30713492 }}</ref> Coextinction is especially common when a [[keystone species]] goes extinct. Models suggest that coextinction is the most common form of [[biodiversity loss]]. There may be a cascade of coextinction across the [[trophic level]]s. Such effects are most severe in [[mutualism (biology)|mutualistic]] and parasitic relationships. An example of coextinction is the [[Haast's eagle]] and the [[moa]]: the Haast's eagle was a predator that became extinct because its food source became extinct. The moa were several species of flightless birds that were a food source for the Haast's eagle.<ref>{{cite journal |last1=Dunn |first1=Robert R. |last2=Harris |first2=Nyeema C. |last3=Colwell |first3=Robert K. |last4=Koh |first4=Lian Pin |last5=Sodhi |first5=Navjot S. |title=The sixth mass coextinction: are most endangered species parasites and mutualists? |journal=Proceedings of the Royal Society B: Biological Sciences |date=7 September 2009 |volume=276 |issue=1670 |pages=3037–3045 |doi=10.1098/rspb.2009.0413 |pmid=19474041 |pmc=2817118}}</ref>

=== Climate change ===
{{Main|Extinction risk from climate change}}
{{See also|Effect of climate change on plant biodiversity|Effects of climate change on marine mammals}}

Extinction as a result of [[climate change]] has been confirmed by fossil studies.<ref name="SahneyBentonFalconLang 2010RainforestCollapse">{{cite journal |url=http://geology.geoscienceworld.org/cgi/content/abstract/38/12/1079 |last1=Sahney |first1=S. |last2=Benton |first2=M.J. |last3=Falcon-Lang |first3=H.J. |year=2010 |title=Rainforest collapse triggered Pennsylvanian tetrapod diversification in Euramerica |journal=Geology |doi=10.1130/G31182.1 |volume=38 |pages=1079–1082 |format=PDF |issue=12 |bibcode=2010Geo....38.1079S |access-date=28 August 2011 |archive-date=11 October 2011 |archive-url=https://web.archive.org/web/20111011144357/http://geology.geoscienceworld.org/cgi/content/abstract/38/12/1079 |url-status=live|url-access=subscription }}</ref> Particularly, the extinction of amphibians during the [[Carboniferous Rainforest Collapse]], 305&nbsp;million years ago.<ref name="SahneyBentonFalconLang 2010RainforestCollapse" /> A 2003 review across 14 biodiversity research centers predicted that, because of climate change, 15–37% of land species would be "committed to extinction" by 2050.<ref>{{cite journal |last1=Thomas |first1=Chris D. |last2=Cameron |first2=Alison |last3=Green |first3=Rhys E. |last4=Bakkenes |first4=Michel |last5=Beaumont |first5=Linda J. |last6=Collingham |first6=Yvonne C. |last7=Erasmus |first7=Barend F. N. |last8=de Siqueira |first8=Marinez Ferreira |last9=Grainger |first9=Alan |last10=Hannah |first10=Lee |last11=Hughes |first11=Lesley |last12=Huntley |first12=Brian |last13=van Jaarsveld |first13=Albert S. |last14=Midgley |first14=Guy F. |last15=Miles |first15=Lera |last16=Ortega-Huerta |first16=Miguel A. |last17=Townsend Peterson |first17=A. |last18=Phillips |first18=Oliver L. |last19=Williams |first19=Stephen E. |title=Extinction risk from climate change |journal=Nature |date=January 2004 |volume=427 |issue=6970 |pages=145–148 |doi=10.1038/nature02121 |pmid=14712274 |bibcode=2004Natur.427..145T |s2cid=969382 |url=https://pure.qub.ac.uk/ws/files/733227/Thomas%26Cameron_Extinctions_Cover%26Article_Nature_2004.pdf |access-date=30 November 2019 |archive-date=29 April 2019 |archive-url=https://web.archive.org/web/20190429130413/https://pure.qub.ac.uk/ws/files/733227/Thomas%26Cameron_Extinctions_Cover%26Article_Nature_2004.pdf |url-status=live}}</ref><ref name="Bhattacharya">{{cite magazine |url=https://www.newscientist.com/article/dn4545-global-warming-threatens-millions-of-species.html |title=Global warming threatens millions of species |date=7 January 2004 |magazine=[[New Scientist]] |access-date=2010-05-28 |last=Bhattacharya |first=Shaoni |quote=the effects of climate change should be considered as great a threat to biodiversity as the "Big Three"—[[habitat destruction]], [[Invasive species|invasions by alien species]] and overexploitation by humans. |archive-date=21 April 2010 |archive-url=https://web.archive.org/web/20100421082210/http://www.newscientist.com/article/dn4545-global-warming-threatens-millions-of-species.html |url-status=live}}</ref> The ecologically rich areas that would potentially suffer the heaviest losses include the [[Cape Floristic Region]] and the [[Caribbean Basin]]. These areas might see a doubling of present carbon dioxide levels and rising temperatures that could eliminate 56,000 plant and 3,700 animal species.<ref>{{cite web |last1=Handwerk |first1=Brian |last2=Hendwerk |first2=Brian |title=Global Warming Could Cause Mass Extinctions by 2050, Study Says |publisher=National Geographic News |date=April 2006 |url=https://news.nationalgeographic.com/news/2006/04/0412_060412_global_warming.html |access-date=27 October 2017 |archive-date=12 June 2017 |archive-url=https://web.archive.org/web/20170612161507/http://news.nationalgeographic.com/news/2006/04/0412_060412_global_warming.html }}</ref> Climate change has also been found to be a factor in [[habitat loss]] and [[desertification]].<ref>{{cite journal |last1=Gibbon |first1=J. Whitfield |last2=Scott |first2=David E. |last3=Ryan |first3=Travis J. |last4=Buhlmann |first4=Kurt A. |last5=Tuberville |first5=Tracey D. |last6=Metts |first6=Brian S. |last7=Greene |first7=Judith L. |last8=Mills |first8=Tony |last9=Leiden |first9=Yale |last10=Poppy |first10=Sean |last11=Winne |first11=Christopher T. |title=The Global Decline of Reptiles, Déjà Vu Amphibians |journal=BioScience |date=2000 |volume=50 |issue=8 |page=653 |doi=10.1641/0006-3568(2000)050[0653:TGDORD]2.0.CO;2 |s2cid=12094030 |url=https://digitalcommons.butler.edu/facsch_papers/536 |access-date=14 July 2019 |archive-date=13 December 2019 |archive-url=https://web.archive.org/web/20191213114220/https://digitalcommons.butler.edu/facsch_papers/536/ |url-status=live|url-access=subscription }}</ref>

=== Sexual selection and male investment ===
Studies of fossils following species from the time they evolved to their extinction show that species with high [[sexual dimorphism]], especially characteristics in males that are used to compete for mating, are at a higher risk of extinction and die out faster than less sexually dimorphic species, the least sexually dimorphic species surviving for millions of years while the most sexually dimorphic species die out within mere thousands of years. Earlier studies based on counting the number of currently living species in modern taxa have shown a higher number of species in more sexually dimorphic taxa which have been interpreted as higher survival in taxa with more sexual selection, but such studies of modern species only measure indirect effects of extinction and are subject to error sources such as dying and doomed taxa speciating more due to splitting of habitat ranges into more small isolated groups during the habitat retreat of taxa approaching extinction. Possible causes of the higher extinction risk in species with more sexual selection shown by the comprehensive fossil studies that rule out such error sources include expensive sexually selected ornaments having negative effects on the ability to survive [[natural selection]], as well as [[sexual selection]] removing a diversity of genes that under current ecological conditions are neutral for natural selection but some of which may be important for surviving climate change.<ref>{{cite journal |last1=Martins |first1=Maria João Fernandes |last2=Puckett |first2=T. Markham |last3=Lockwood |first3=Rowan |last4=Swaddle |first4=John P. |last5=Hunt |first5=Gene |title=High male sexual investment as a driver of extinction in fossil ostracods |journal=Nature |date=April 2018 |volume=556 |issue=7701 |pages=366–369 |doi=10.1038/s41586-018-0020-7 |pmid=29643505 |bibcode=2018Natur.556..366M |s2cid=4925632 |url=https://aquila.usm.edu/cgi/viewcontent.cgi?article=17927&context=fac_pubs |access-date=16 September 2022 |archive-date=2 October 2022 |archive-url=https://web.archive.org/web/20221002122147/https://aquila.usm.edu/cgi/viewcontent.cgi?article=17927&context=fac_pubs |url-status=live|url-access=subscription }}</ref>

== Mass extinctions ==
{{Main|Extinction event}}
{{annotated image/Extinction|float=right}}
There have been at least five mass extinctions in the history of life on earth, and four in the last 350&nbsp;million years in which many species have disappeared in a relatively short period of geological time. A massive eruptive event that released large quantities of [[tephra]] particles into the atmosphere is considered to be one likely cause of the "[[Permian–Triassic extinction event]]" about 250&nbsp;million years ago,<ref name="SahneyBenton2008RecoveryFromProfoundExtinction">{{ cite journal |url= |last1=Sahney |first1=S. |last2=Benton |first2=M.J. |year=2008 |title=Recovery from the most profound mass extinction of all time |journal=Proceedings of the Royal Society B: Biological Sciences |doi=10.1098/rspb.2007.1370 |volume=275 |pages=759–765 |pmid=18198148 |issue=1636 |pmc=2596898}}</ref> which is estimated to have killed 90% of species then existing.<ref>{{cite book |last=Benton |first=M.J. |year=2005 |title=When Life Nearly Died: The Greatest Mass Extinction of All Time |publisher=Thames & Hudson |isbn=978-0-500-28573-2}}</ref> There is also evidence to suggest that this event was preceded by another mass extinction, known as [[Olson's Extinction]].<ref name="SahneyBenton2008RecoveryFromProfoundExtinction" /> The [[Cretaceous–Paleogene extinction event]] (K–Pg) occurred 66&nbsp;million years ago, at the end of the [[Cretaceous]] period; it is best known for having wiped out non-avian [[dinosaur]]s, among many other species.

=== Modern extinctions ===
{{Main|Holocene extinction}}
{{Further|Anthropocene|Defaunation|Deforestation}}
[[File:Decline-of-the-worlds-wild-mammals.png|thumb|upright=1.5|The changing distribution of the world's land mammals in tonnes of carbon. The [[Biomass (ecology)|biomass]] of wild land mammals has declined by 85% since the emergence of humans.<ref>{{cite web |url=https://ourworldindata.org/wild-mammal-decline |title=Wild mammals have declined by 85% since the rise of humans, but there is a possible future where they flourish |last=Ritchie |first=Hannah |author1-link=Hannah Ritchie |date=April 20, 2021 |website=[[Our World in Data]] |publisher= |access-date=April 19, 2023 |quote= |archive-date=16 February 2023 |archive-url=https://web.archive.org/web/20230216013950/https://ourworldindata.org/wild-mammal-decline |url-status=live}}</ref>]]

According to a 1998 survey<!-- Needs updating. Survey is now 20+ years old.  --> of 400 biologists conducted by [[New York City|New York]]'s [[American Museum of Natural History]], nearly 70% believed that the Earth is currently in the early stages of a human-caused mass extinction,<ref name="AMNH">[[American Museum of Natural History]]. "[http://www.well.com/~davidu/amnh.html National Survey Reveals Biodiversity Crisis – Scientific Experts Believe We are in the Midst of the Fastest Mass Extinction in Earth's History] {{Webarchive|url=https://web.archive.org/web/20120410162439/http://www.well.com/~davidu/amnh.html |date=10 April 2012 }}". Retrieved September 20, 2006.</ref> known as the [[Holocene extinction]]. In that survey, the same proportion of respondents agreed with the prediction that up to 20% of all living populations could become extinct within 30 years (by 2028). A 2014 special edition of ''[[Science (journal)|Science]]'' declared there is widespread consensus on the issue of human-driven mass species extinctions.<ref>{{Cite journal |date=25 July 2014 |title=Vanishing fauna (Special issue) |journal=[[Science (journal)|Science]] |volume=345 |issue=6195 |pages=392–412 |doi=10.1126/science.345.6195.392 |pmid=25061199 |bibcode=2014Sci...345..392V |last=Vignieri |first=S. |doi-access=free}}</ref>  A 2020 study published in ''[[PNAS]]'' stated that the contemporary extinction crisis "may be the most serious environmental threat to the persistence of civilization, because it is irreversible."<ref>{{cite journal |last1=Ceballos |first1=Gerardo |last2=Ehrlich |first2=Paul R. |last3=Raven |first3=Peter H. |date=June 1, 2020 |title=Vertebrates on the brink as indicators of biological annihilation and the sixth mass extinction |journal=[[PNAS]] |volume=117 |issue=24 |pages=13596–13602 |doi=10.1073/pnas.1922686117 |pmid=32482862 |pmc=7306750 |bibcode=2020PNAS..11713596C |doi-access=free}}</ref> A 2025 study found that human activities are to blame for biodiversity loss across all species and ecosystems.<ref>{{cite news |last=Weston |first=Phoebe |date=March 26, 2025 |title=Biodiversity loss in all species and every ecosystem linked to humans – report |url=https://www.theguardian.com/environment/2025/mar/26/human-link-biodiversity-loss-species-ecosystems-climate-pollution-eawag-study-nature-aoe |location= |work=[[The Guardian]] |access-date=April 4, 2025}}</ref>

Biologist [[E. O. Wilson]] estimated<ref name="Wilson" /> in 2002 that if current rates of human destruction of the biosphere continue, one-half of all plant and animal species of life on earth will be extinct in 100 years.<ref name="Wilson2">{{cite interview |last=Wilson |first=E.O. |interviewer=Lisa Hymas |title="E. O. Wilson wants to know why you're not protesting in the streets" |url=http://grist.org/article/e-o-wilson-wants-to-know-why-youre-not-protesting-in-the-streets/ |date=April 30, 2012 |work=Grist |access-date=January 16, 2014 |archive-date=4 November 2017 |archive-url=https://web.archive.org/web/20171104234523/http://grist.org/article/e-o-wilson-wants-to-know-why-youre-not-protesting-in-the-streets/ |url-status=live}} E.O. Wilson repeats his estimation in 2012.</ref> More significantly, the current rate of global species extinctions is estimated as 100 to 1,000 times "background" rates (the average extinction rates in the [[evolution]]ary time scale of planet Earth),<ref>J.H.Lawton and R.M.May, ''Extinction rates'', [[Oxford University]] Press, Oxford, UK</ref><ref name="DeVos2014">{{cite journal |last1=De Vos |first1=Jurriaan M. |last2=Joppa |first2=Lucas N. |last3=Gittleman |first3=John L. |last4=Stephens |first4=Patrick R. |last5=Pimm |first5=Stuart L. |title=Estimating the normal background rate of species extinction: Background Rate of Extinction |journal=Conservation Biology |date=April 2015 |volume=29 |issue=2 |pages=452–462 |doi=10.1111/cobi.12380 |pmid=25159086 |bibcode=2015ConBi..29..452D |s2cid=19121609 |url=https://www.zora.uzh.ch/id/eprint/98443/1/Conservation_Biology_2014_early-view.pdf |access-date=30 November 2019 |archive-date=4 November 2018 |archive-url=https://web.archive.org/web/20181104111411/https://www.zora.uzh.ch/id/eprint/98443/1/Conservation_Biology_2014_early-view.pdf |url-status=live}}</ref> faster than at any other time in human history,<ref>{{cite news |vauthors=Carrington D |date=February 2, 2021 |title=Economics of biodiversity review: what are the recommendations? |url=https://www.theguardian.com/environment/2021/feb/02/economics-of-biodiversity-review-what-are-the-recommendations |work=[[The Guardian]] |location= |access-date=December 21, 2021 |archive-date=24 May 2022 |archive-url=https://web.archive.org/web/20220524182314/https://www.theguardian.com/environment/2021/feb/02/economics-of-biodiversity-review-what-are-the-recommendations |url-status=live}}</ref><ref>{{cite web |url=https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/957629/Dasgupta_Review_-_Headline_Messages.pdf |title=The Economics of Biodiversity: The Dasgupta Review Headline Messages |last=Dasgupta |first=Partha |author-link=Partha Dasgupta |date=2021 |website= |publisher=UK government |page=1 |access-date=December 21, 2021 |quote=Biodiversity is declining faster than at any time in human history. Current extinction rates, for example, are around 100 to 1,000 times higher than the baseline rate, and they are increasing. |archive-date=20 May 2022 |archive-url=https://web.archive.org/web/20220520070152/https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/957629/Dasgupta_Review_-_Headline_Messages.pdf |url-status=live}}</ref> while future rates are likely 10,000 times higher.<ref name=DeVos2014 /> However, some groups are going extinct much faster. Biologists [[Paul R. Ehrlich]] and [[Stuart Pimm]], among others, contend that human [[population growth]] and [[overconsumption]] are the main drivers of the modern extinction crisis.<ref name="Ceballos2017">{{cite journal |last1=Ceballos |first1=Gerardo |last2=Ehrlich |first2=Paul R |last3=Dirzo |first3=Rodolfo |date=23 May 2017 |title=Biological annihilation via the ongoing sixth mass extinction signaled by vertebrate population losses and declines |journal=[[Proceedings of the National Academy of Sciences of the United States of America|PNAS]] |doi=10.1073/pnas.1704949114 |pmc=5544311 |pmid=28696295 |volume=114 |issue=30 |pages=E6089–E6096 |bibcode=2017PNAS..114E6089C |quote=Much less frequently mentioned are, however, the ultimate drivers of those immediate causes of biotic destruction, namely, human overpopulation and continued population growth, and overconsumption, especially by the rich. These drivers, all of which trace to the fiction that perpetual growth can occur on a finite planet, are themselves increasing rapidly. |doi-access=free}}</ref><ref>{{cite journal |last1=Pimm |first1=S. L. |last2=Jenkins |first2=C. N. |last3=Abell |first3=R. |last4=Brooks |first4=T. M. |last5=Gittleman |first5=J. L. |last6=Joppa |first6=L. N. |last7=Raven |first7=P. H. |last8=Roberts |first8=C. M. |last9=Sexton |first9=J. O. |title=The biodiversity of species and their rates of extinction, distribution, and protection |journal=Science |date=30 May 2014 |volume=344 |issue=6187 |article-number=1246752 |doi=10.1126/science.1246752 |pmid=24876501 |s2cid=206552746}}</ref><ref>{{cite web |url=http://www.cnn.com/2016/12/12/world/sutter-vanishing-help/ |title=How to stop the sixth mass extinction |first=John D. |last=Sutter |date=December 12, 2016 |work=CNN |access-date=January 3, 2017 |archive-date=13 December 2016 |archive-url=https://web.archive.org/web/20161213131234/http://www.cnn.com/2016/12/12/world/sutter-vanishing-help/ |url-status=live}}</ref><ref>{{cite news |last=Graham |first=Chris |date=July 11, 2017 |title=Earth undergoing sixth 'mass extinction' as humans spur 'biological annihilation' of wildlife |url=https://www.telegraph.co.uk/news/2017/07/11/earth-undergoing-sixth-mass-extinction-humans-spur-biological/ |archive-url=https://ghostarchive.org/archive/20220111/https://www.telegraph.co.uk/news/2017/07/11/earth-undergoing-sixth-mass-extinction-humans-spur-biological/ |archive-date=2022-01-11 |url-access=subscription |url-status=live |work=The Telegraph |access-date=July 23, 2017}}{{cbignore}}</ref>

In January 2020, the UN's [[Convention on Biological Diversity]] drafted a plan to mitigate the contemporary extinction crisis by establishing a deadline of 2030 to protect 30% of the Earth's land and oceans and reduce pollution by 50%, with the goal of allowing for the restoration of ecosystems by 2050.<ref>{{cite news |last=Greenfield |first=Patrick |date=January 13, 2020 |title=UN draft plan sets 2030 target to avert Earth's sixth mass extinction |url=https://www.theguardian.com/environment/2020/jan/13/un-draft-plan-sets-2030-target-to-avert-earths-sixth-mass-extinction-aoe |work=The Guardian |access-date=January 14, 2020 |archive-date=24 February 2021 |archive-url=https://web.archive.org/web/20210224095816/https://www.theguardian.com/environment/2020/jan/13/un-draft-plan-sets-2030-target-to-avert-earths-sixth-mass-extinction-aoe |url-status=live}}</ref><ref>{{cite news |last=Yeung |first=Jessie |date=January 14, 2020 |title=We have 10 years to save Earth's biodiversity as mass extinction caused by humans takes hold, UN warns |url=https://www.cnn.com/2020/01/14/world/un-biodiversity-draft-plan-intl-hnk-scli-scn/index.html |work=CNN |access-date=January 14, 2020 |archive-date=15 February 2021 |archive-url=https://web.archive.org/web/20210215051020/https://www.cnn.com/2020/01/14/world/un-biodiversity-draft-plan-intl-hnk-scli-scn/index.html |url-status=live}}</ref> The 2020 [[United Nations]]' ''Global Biodiversity Outlook'' report stated that of the 20 biodiversity goals laid out by the Aichi Biodiversity Targets in 2010, only 6 were "partially achieved" by the deadline of 2020.<ref>{{cite news |last=Cohen |first=Li |date=September 15, 2020 |title=More than 150 countries made a plan to preserve biodiversity a decade ago. A new report says they mostly failed. |url=https://www.cbsnews.com/news/more-than-150-countries-made-a-plan-to-save-the-worlds-species-and-ecosystems-a-decade-ago-a-new-report-says-they-mostly-failed/ |work=[[CBS News]] |access-date=September 23, 2020 |archive-date=15 May 2022 |archive-url=https://web.archive.org/web/20220515192230/https://www.cbsnews.com/news/more-than-150-countries-made-a-plan-to-save-the-worlds-species-and-ecosystems-a-decade-ago-a-new-report-says-they-mostly-failed/ |url-status=live}}</ref> The report warned that biodiversity will continue to decline if the status quo is not changed, in particular the "currently unsustainable patterns of production and consumption, population growth and technological developments".<ref>{{cite news |last=Yeung |first=Jessie |date=September 16, 2020 |title=The world set a 2020 deadline to save nature but not a single target was met, UN report says |url=https://edition.cnn.com/2020/09/16/world/un-biodiversity-report-intl-hnk-scli-scn/ |work=[[CNN]] |access-date=September 23, 2020 |archive-date=15 May 2022 |archive-url=https://web.archive.org/web/20220515192230/https://edition.cnn.com/2020/09/16/world/un-biodiversity-report-intl-hnk-scli-scn/ |url-status=live}}</ref> In a 2021 report published in the journal ''Frontiers in Conservation Science'', some top scientists asserted that even if the Aichi Biodiversity Targets set for 2020 had been achieved, it would not have resulted in a significant mitigation of biodiversity loss. They added that failure of the global community to reach these targets is hardly surprising given that biodiversity loss is "nowhere close to the top of any country's priorities, trailing far behind other concerns such as employment, healthcare, economic growth, or currency stability."<ref>{{cite news |last=Weston |first=Phoebe |date=January 13, 2021 |title=Top scientists warn of 'ghastly future of mass extinction' and climate disruption |url=https://www.theguardian.com/environment/2021/jan/13/top-scientists-warn-of-ghastly-future-of-mass-extinction-and-climate-disruption-aoe |work=[[The Guardian]] |location= |access-date=January 19, 2021 |archive-date=13 January 2021 |archive-url=https://web.archive.org/web/20210113050606/https://www.theguardian.com/environment/2021/jan/13/top-scientists-warn-of-ghastly-future-of-mass-extinction-and-climate-disruption-aoe |url-status=live}}</ref><ref>{{cite journal |last1=Bradshaw |first1=Corey J. A. |last2=Ehrlich |first2=Paul R. |last3=Beattie |first3=Andrew |last4=Ceballos |first4=Gerardo |last5=Crist |first5=Eileen |last6=Diamond |first6=Joan |last7=Dirzo |first7=Rodolfo |last8=Ehrlich |first8=Anne H. |last9=Harte |first9=John |last10=Harte |first10=Mary Ellen |last11=Pyke |first11=Graham |last12=Raven |first12=Peter H. |last13=Ripple |first13=William J. |last14=Saltré |first14=Frédérik |last15=Turnbull |first15=Christine |last16=Wackernagel |first16=Mathis |last17=Blumstein |first17=Daniel T. |date=2021 |title=Underestimating the Challenges of Avoiding a Ghastly Future |journal=Frontiers in Conservation Science |volume=1 |issue= |article-number=615419 |doi=10.3389/fcosc.2020.615419 |doi-access=free |bibcode=2021FrCS....1.5419B}}</ref>

== History of scientific understanding ==
[[File:Tyrannosaurus-rex-Profile-steveoc86.png|thumb|''[[Tyrannosaurus]]'', one of the many extinct dinosaur genera. The cause of the [[Cretaceous–Paleogene extinction event]] is a subject of much debate amongst researchers.]]
[[File:Anoplotherium_1812_Skeleton_Sketch.jpg|thumb|Georges Cuvier's 1812 unpublished version of the skeletal reconstruction of ''[[Anoplotherium]] commune'' with muscles. Today, the [[Paleogene]] mammal is thought to have gone extinct from the [[Grande Coupure]] extinction event in western Europe.<ref>{{cite journal |last1=Hooker |first1=Jerry J. |last2=Collinson |first2=Margaret E. |author-link=Margaret Collinson |last3=Sille |first3=Nicholas P. |year=2004 |title=Eocene–Oligocene mammalian faunal turnover in the Hampshire Basin, UK: calibration to the global time scale and the major cooling event |journal=Journal of the Geological Society |volume=161 |issue=2 |pages=161–172 |doi=10.1144/0016-764903-091 |bibcode=2004JGSoc.161..161H |s2cid=140576090 |url=http://doc.rero.ch/record/13418/files/PAL_E228.pdf |access-date=25 August 2023 |archive-date=8 August 2023 |archive-url=https://web.archive.org/web/20230808072039/https://doc.rero.ch/record/13418/files/PAL_E228.pdf |url-status=live}}</ref>]]
[[File:Cuvier elephant jaw.jpg|thumb|[[Georges Cuvier]] compared fossil [[mammoth]] jaws to those of living elephants, concluding that they were distinct from any known living species.<ref name=":52">{{Cite web |url=http://evolution.berkeley.edu/evolibrary/article/history_08 |title=Extinctions: Georges Cuvier |website=evolution.berkeley.edu |access-date=2017-05-04 |archive-date=29 April 2017 |archive-url=https://web.archive.org/web/20170429200852/http://evolution.berkeley.edu/evolibrary/article/history_08 |url-status=live}}</ref>]]

For much of history, the modern understanding of extinction as the end of a [[species]] was incompatible with the prevailing worldview. Prior to the 19th century, much of Western society adhered to the belief that the world was created by God and as such was complete and perfect.<ref name=":02">{{Cite journal |last=Rowland |first=Stephen |date=2009 |title=Thomas Jefferson, extinction, and the evolving view of Earth history in the late eighteenth and early nineteenth centuries |url=http://memoirs.gsapubs.org/content/203/225.abstract |journal=GSA Memoirs |volume=203 |pages=225–246 |access-date=5 May 2017 |archive-date=1 September 2015 |archive-url=https://web.archive.org/web/20150901223048/http://memoirs.gsapubs.org/content/203/225.abstract |url-status=live}}</ref> This concept reached its heyday in the 1700s with the peak popularity of a theological concept called the [[great chain of being]], in which all life on earth, from the tiniest microorganism to God, is linked in a continuous chain.<ref name=":12">{{Cite book |url=http://www.gutenberg.org/files/33224/33224-h/33224-h.htm |title=The Principles of Geology or, The Modern Changes of the Earth and its Inhabitants Considered as Illustrative of Geology |last=Lyells |first=Charles |publisher=Appleton Co |year=1854 |location=New York |access-date=5 May 2017 |archive-date=25 October 2016 |archive-url=https://web.archive.org/web/20161025005756/http://www.gutenberg.org/files/33224/33224-h/33224-h.htm |url-status=live}}</ref> The extinction of a species was impossible under this model, as it would create gaps or missing links in the chain and destroy the natural order.<ref name=":02" /><ref name=":12" /> [[Thomas Jefferson]] was a firm supporter of the great chain of being and an opponent of extinction,<ref name=":02" /><ref name=":32">{{cite web |last1=Bressan |first1=David |title=On the Extinction of Species |url=https://blogs.scientificamerican.com/history-of-geology/on-the-extinction-of-species/ |work=Scientific American Blog Network |date=17 August 2011 |access-date=5 May 2017 |archive-date=22 December 2017 |archive-url=https://web.archive.org/web/20171222105110/https://blogs.scientificamerican.com/history-of-geology/on-the-extinction-of-species/ |url-status=live}}{{self-published inline|date=February 2022}}</ref> famously denying the extinction of the [[woolly mammoth]] on the grounds that nature never allows a race of animals to become extinct.<ref name=":42">{{cite book |last1=Vidal |first1=Fernando |last2=Dias |first2=Nélia |title=Endangerment, Biodiversity and Culture |date=2015 |publisher=Routledge |isbn=978-1-317-53807-3}}{{page needed|date=February 2022}}</ref>

A series of fossils were discovered in the late 17th century that appeared unlike any living species. As a result, the scientific community embarked on a voyage of creative rationalization, seeking to understand what had happened to these species within a framework that did not account for total extinction. In October 1686, [[Robert Hooke]] presented an impression of a [[nautilus]] to the [[Royal Society]] that was more than two feet in diameter,<ref>{{Cite book |url=https://archive.org/details/forgottengeniusb0000inwo |url-access=registration |page=[https://archive.org/details/forgottengeniusb0000inwo/page/403 403] |quote=hooke nautilus. |title=The Forgotten Genius: The Biography of Robert Hooke, 1635–1703 |last=Inwood |first=Stephen |date=2005 |publisher=MacAdam/Cage Publishing |isbn=978-1-59692-115-3 |language=en}}</ref> and morphologically distinct from any known living species. Hooke theorized that this was simply because the species lived in the deep ocean and no one had discovered them yet.<ref name=":12" /> While he contended that it was possible a species could be "lost", he thought this highly unlikely.<ref name=":12" /> Similarly, in 1695, [[Sir Thomas Molyneux]] published an account of enormous antlers found in [[Ireland]] that did not belong to any extant taxa in that area.<ref name=":32" /><ref name=":22">{{cite journal |last1=Molyneux |first1=Thomas |author-link1=Sir Thomas Molyneux, 1st Baronet |title=II. A discourse concerning the large horns frequently found under ground in Ireland, concluding from them that the great American deer, call'd a moose, was formerly common in that Island: with remarks on some other things natural to that country |journal=Philosophical Transactions of the Royal Society of London |date=April 1697 |volume=19 |issue=227 |pages=489–512 |doi=10.1098/rstl.1695.0083 |bibcode=1695RSPT...19..489M |s2cid=186207711}}</ref> Molyneux reasoned that they came from the North American [[moose]] and that the animal had once been common on the [[British Isles]].<ref name=":32" /><ref name=":22" /> Rather than suggest that this indicated the possibility of species going extinct, he argued that although organisms could become locally extinct, they could never be entirely lost and would continue to exist in some unknown region of the globe.<ref name=":22" /> The antlers were later confirmed to be from the extinct [[deer]] ''[[Megaloceros]]''.<ref name=":32" /> Hooke and Molyneux's line of thinking was difficult to disprove. When parts of the world had not been thoroughly examined and charted, scientists could not rule out that animals found only in the fossil record were not simply "hiding" in unexplored regions of the Earth.<ref name="Watson2">''Ideas: A History from Fire to Freud'' ([[Peter Watson (business writer)|Peter Watson]] Weidenfeld & Nicolson {{ISBN|0-297-60726-X}}){{page needed|date=February 2022}}</ref>

[[Georges Cuvier]] is credited with establishing the modern conception of extinction in a 1796 lecture to the [[French Institute]],<ref name=":52" /><ref name=":42"/> though he would spend most of his career trying to convince the wider scientific community of his theory.<ref name=":62">{{Cite book |title=Perilous planet earth: catastrophes and catastrophism through the ages |last=Trevor |first=Palmer |date=2003 |publisher=Cambridge University Press |isbn=978-0-521-81928-2 |oclc=912273245}}{{page needed|date=February 2022}}</ref> Cuvier was a well-regarded geologist, lauded for his ability to reconstruct the anatomy of an unknown species from a few fragments of bone.<ref name=":52" /> His primary evidence for extinction came from mammoth skulls found near [[Paris]].<ref name=":52" /> Cuvier recognized them as distinct from any known living species of elephant, and argued that it was highly unlikely such an enormous animal would go undiscovered.<ref name=":52" /> In 1798, he studied a fossil from the [[Paris Basin]] that was first observed by [[Robert de Lamanon]] in 1782, first hypothesizing that it belonged to a canine but then deciding that it instead belonged to an animal that was unlike living ones. His study paved the way to his naming of the extinct mammal genus ''[[Palaeotherium]]'' in 1804 based on the skull and additional fossil material along with another extinct contemporary mammal genus ''[[Anoplotherium]]''. In both genera, he noticed that their fossils shared some similarities with other mammals like [[ruminant]]s and [[rhinoceros]]es but still had distinct differences.<ref>{{cite book |editor-last1=Chemla |editor-first1=Karine |editor-last2=Keller |editor-first2=Evelyn Fox |last=Belhoste |first=Bruno |year=2017 |title=Cultures without Culturalism: The Making of Scientific Knowledge |chapter=Chapter 10: From Quarry to Paper. Cuvier's Three Epistemological Cultures |publisher=Duke University Press |pages=250–277}}</ref> In 1812, Cuvier, along with [[Alexandre Brongniart]] and [[Isidore Geoffroy Saint-Hilaire|Geoffroy Saint-Hilaire]], mapped the [[Stratum|strata]] of the Paris basin.<ref name=":12" /> They saw alternating saltwater and freshwater deposits, as well as patterns of the appearance and disappearance of fossils throughout the record.<ref name=":32" /><ref name=":62" /> From these patterns, Cuvier inferred historic cycles of catastrophic flooding, extinction, and repopulation of the earth with new species.<ref name=":32" /><ref name=":62" />

Cuvier's fossil evidence showed that very different life forms existed in the past than those that exist today, a fact that was accepted by most scientists.<ref name=":02" /> The primary debate focused on whether this turnover caused by extinction was gradual or abrupt in nature.<ref name=":62" /> Cuvier understood extinction to be the result of cataclysmic events that wipe out huge numbers of species, as opposed to the gradual decline of a species over time.<ref name=":8">{{Cite book |last1=M. J. S. |first1=Rudwick |title=Georges Cuvier, fossil bones, and geological catastrophes: new translations & interpretations of the primary texts |last2=Cuvier |first2=Georges |author-link2=Georges Cuvier |date=1998 |publisher=University of Chicago Press |isbn=978-0-226-73106-3 |oclc=45730036}}{{page needed|date=February 2022}}</ref> His catastrophic view of the nature of extinction garnered him many opponents in the newly emerging school of [[uniformitarianism]].<ref name=":8" />

[[Jean-Baptiste Lamarck]], a [[Gradualism|gradualist]] and colleague of Cuvier, saw the fossils of different life forms as evidence of the mutable character of species.<ref name=":62" /> While Lamarck did not deny the possibility of extinction, he believed that it was exceptional and rare and that most of the change in species over time was due to gradual change.<ref name=":62" /> Unlike Cuvier, Lamarck was skeptical that catastrophic events of a scale large enough to cause total extinction were possible. In his geological history of the earth titled Hydrogeologie, Lamarck instead argued that the surface of the earth was shaped by gradual erosion and deposition by water, and that species changed over time in response to the changing environment.<ref name=":62" /><ref>{{Cite book |title=The age of Lamarck: evolutionary theories in France, 1790–1830 |last=Corsi |first=Pietro |publisher=University of California Press |isbn=978-0-520-05830-9 |oclc=898833548 |year=1988}}{{page needed|date=February 2022}}</ref>

[[Charles Lyell]], a noted geologist and founder of [[uniformitarianism]], believed that past processes should be understood using present day processes. Like Lamarck, Lyell acknowledged that extinction could occur, noting the total extinction of the [[dodo]] and the extirpation of [[History of the horse in Britain|indigenous horses]] to the British Isles.<ref name=":12" /> He similarly argued against [[mass extinction]]s, believing that any extinction must be a gradual process.<ref name=":52"/><ref name=":42" /> Lyell also showed that Cuvier's original interpretation of the Parisian strata was incorrect. Instead of the catastrophic floods inferred by Cuvier, Lyell demonstrated that patterns of saltwater and freshwater [[Deposition (geology)|deposits]], like those seen in the Paris basin, could be formed by a slow rise and fall of [[sea level]]s.<ref name=":32" />

The concept of extinction was integral to [[Charles Darwin]]'s ''[[On the Origin of Species]]'', with less fit lineages disappearing over time. For Darwin, extinction was a constant side effect of [[Competition (biology)|competition]].<ref>{{cite magazine |title=The Lost World |url=https://www.newyorker.com/magazine/2013/12/16/the-lost-world-2 |magazine=The New Yorker |date=9 December 2013 |access-date=9 February 2022 |archive-date=3 February 2023 |archive-url=https://web.archive.org/web/20230203051615/https://www.newyorker.com/magazine/2013/12/16/the-lost-world-2 |url-status=live}}</ref> Because of the wide reach of ''On the Origin of Species'', it was widely accepted that extinction occurred gradually and evenly (a concept now referred to as [[Background extinction rate|background extinction]]).<ref name=":42" /> It was not until 1982, when [[David M. Raup|David Raup]] and [[Jack Sepkoski]] published their seminal paper on mass extinctions, that Cuvier was vindicated and catastrophic extinction was accepted as an important mechanism{{Citation needed|reason=A lot of history separates Cuvier from Raup and Sepkoski's 1982 work, including such figures as Bretz from the University of Chicago|date=February 2024}}. The current understanding of extinction is a synthesis of the cataclysmic extinction events proposed by Cuvier, and the background extinction events proposed by Lyell and Darwin.

== Human attitudes and interests ==
[[File:Sphyrna mokarran fishing.jpg|thumb|upright|A [[great hammerhead]] caught by a sport fisherman. Human exploitation now threatens the survival of this species. [[Overfishing]] is the primary driver of shark population declines, which have fallen over 71% since 1970.<ref>{{cite news |last=Einhorn |first=Catrin |date=January 27, 2021 |title=Shark Populations Are Crashing, With a 'Very Small Window' to Avert Disaster |url=https://www.nytimes.com/2021/01/27/climate/sharks-population-study.html |work=[[The New York Times]] |location= |access-date=January 31, 2021 |archive-date=31 January 2021 |archive-url=https://web.archive.org/web/20210131005226/https://www.nytimes.com/2021/01/27/climate/sharks-population-study.html |url-status=live}}</ref><ref>{{cite journal |last1=Pacoureau |first1=Nathan |last2=Rigby |first2=Cassandra L. |last3=Kyne |first3=Peter M. |last4=Sherley |first4=Richard B. |last5=Winker |first5=Henning |last6=Carlson |first6=John K. |last7=Fordham |first7=Sonja V. |last8=Barreto |first8=Rodrigo |last9=Fernando |first9=Daniel |last10=Francis |first10=Malcolm P. |last11=Jabado |first11=Rima W. |last12=Herman |first12=Katelyn B. |last13=Liu |first13=Kwang-Ming |last14=Marshall |first14=Andrea D. |last15=Pollom |first15=Riley A. |last16=Romanov |first16=Evgeny V. |last17=Simpfendorfer |first17=Colin A. |last18=Yin |first18=Jamie S. |last19=Kindsvater |first19=Holly K. |last20=Dulvy |first20=Nicholas K. |title=Half a century of global decline in oceanic sharks and rays |journal=Nature |date=28 January 2021 |volume=589 |issue=7843 |pages=567–571 |doi=10.1038/s41586-020-03173-9 |pmid=33505035 |bibcode=2021Natur.589..567P |hdl=10871/124531 |s2cid=231723355 |hdl-access=free}}</ref> ]]

Extinction is an important research topic in the field of [[zoology]], and [[biology]] in general, and has also become an area of concern outside the scientific community. A number of organizations, such as the [[WWF (conservation organization)|Worldwide Fund for Nature]], have been created with the goal of preserving species from extinction. [[Government]]s have attempted, through enacting laws, to avoid habitat destruction, agricultural over-harvesting, and [[pollution]]. While many human-caused extinctions have been accidental, humans have also engaged in the deliberate destruction of some species, such as dangerous [[virus]]es, and the total destruction of other problematic species has been suggested. Other species were deliberately driven to extinction, or nearly so, due to [[poaching]] or because they were "undesirable", or to push for other human agendas. One example was the near extinction of the [[American bison]], which was nearly wiped out by mass hunts sanctioned by the United States government, to force the removal of [[Indigenous peoples of the Americas|Native Americans]], many of whom relied on the bison for food.<ref name="Kotzman">{{cite book |author1=C. Cormack Gates |author2=Curtis H. Freese |author3=Peter J.P. Gogan |author4=Mandy Kotzman |title=American bison: status survey and conservation guidelines 2010 |url=https://books.google.com/books?id=koUrGx-i2ucC&pg=PR15 |access-date=6 November 2011 |publisher=IUCN |isbn=978-2-8317-1149-2 |page=15 |year=2010}}</ref>

Biologist [[Bruce Walsh (scientist)|Bruce Walsh]] states three reasons for scientific interest in the preservation of species: [[genetic resources]], ecosystem stability, and [[ethics]]; and today the scientific community "stress[es] the importance" of maintaining biodiversity.<ref name="Walsh">[[Bruce Walsh (scientist)|Walsh, Bruce]]. [http://nitro.biosci.arizona.edu/courses/EEB105/lectures/extinction/extinction.html Extinction] {{webarchive|url=https://web.archive.org/web/19970802184301/http://nitro.biosci.arizona.edu/courses/EEB105/lectures/extinction/extinction.html |date=1997-08-02 }}. Bioscience at University of Arizona. Retrieved July 26, 2006.</ref><ref name="CREOcare">Committee on Recently Extinct Organisms. "[http://creo.amnh.org/care.html Why Care About Species That Have Gone Extinct?] {{Webarchive|url=https://web.archive.org/web/20060713045653/http://creo.amnh.org/care.html |date=13 July 2006 }}". Retrieved July 30, 2006.</ref>

In modern times, commercial and industrial interests often have to contend with the effects of production on plant and animal life. However, some technologies with minimal, or no, proven harmful effects on ''[[Homo sapiens]]'' can be devastating to wildlife (for example, [[DDT]]).<ref name="INCHEM">International Programme on Chemical Safety (1989). "[http://www.inchem.org/documents/ehc/ehc/ehc83.htm DDT and its Derivatives – Environmental Aspects] {{Webarchive|url=https://web.archive.org/web/20060927215945/http://www.inchem.org/documents/ehc/ehc/ehc83.htm |date=27 September 2006 }}". Environmental Health Criteria 83. Retrieved September 20, 2006.</ref><ref>{{Cite web |url=http://www.inchem.org/documents/ehc/ehc/ehc009.htm |title=DDT and its derivatives (EHC 9, 1979) |access-date=26 September 2020 |archive-date=25 February 2021 |archive-url=https://web.archive.org/web/20210225180744/http://www.inchem.org/documents/ehc/ehc/ehc009.htm |url-status=live}}</ref> [[Biogeography|Biogeographer]] [[Jared Diamond]] notes that while [[big business]] may label environmental concerns as "exaggerated", and often cause "devastating damage", some corporations find it in their interest to adopt good conservation practices, and even engage in preservation efforts that surpass those taken by [[national park]]s.<ref name="DiamondCollapse">{{cite book |last=Diamond |first=Jared |author-link=Jared Diamond |title=Collapse |publisher=Penguin |year=2005 |isbn=978-0-670-03337-9 |pages=15–17 |chapter=A Tale of Two Farms |chapter-url-access=registration |chapter-url=https://archive.org/details/collapsehowsocie00diam}}</ref>

Governments sometimes see the loss of native species as a loss to [[ecotourism]],<ref name="Drewry">Drewry, Rachel. "[http://www.insideindonesia.org/edit51/orang.htm Ecotourism: Can it save the orangutans?] {{webarchive |url=https://web.archive.org/web/20070216200744/http://www.insideindonesia.org/edit51/orang.htm |date=February 16, 2007 }}" ''Inside Indonesia''. Retrieved January 26, 2007.</ref> and can enact laws with severe punishment against the trade in native species in an effort to prevent extinction in the wild. [[Nature preserve]]s are created by governments as a means to provide continuing habitats to species crowded by human expansion. The 1992 [[Convention on Biological Diversity]] has resulted in international [[Biodiversity Action Plan]] programmes, which attempt to provide comprehensive guidelines for government biodiversity conservation. Advocacy groups, such as The Wildlands Project<ref name="WildlandsProject">[http://www.wild-earth.org/cms/page1090.cfm The Wildlands Project] {{webarchive |url=https://web.archive.org/web/20051122155849/http://www.wild-earth.org/cms/page1090.cfm |date=November 22, 2005 }}. Retrieved January 26, 2007.</ref> and the Alliance for Zero Extinctions,<ref>[http://www.zeroextinction.org/ Alliance for Zero Extinctions] {{webarchive |url=https://web.archive.org/web/20110423151342/http://www.zeroextinction.org/ |date=April 23, 2011 }}. Retrieved January 26, 2007.</ref> work to educate the public and pressure governments into action.

People who live close to nature can be dependent on the survival of all the species in their environment, leaving them highly exposed to extinction [[risk]]s. However, people prioritize day-to-day survival over species conservation; with [[human overpopulation]] in tropical [[developing country|developing countries]], there has been enormous pressure on forests due to [[subsistence agriculture]], including [[slash-and-burn]] agricultural techniques that can reduce endangered species's habitats.<ref>{{Cite book |first1=Anne |last1=Ehrlich |title=Extinction: The Causes and Consequences of the Disappearance of Species |publisher=Random House, New York |year=1981 |isbn=978-0-394-51312-6}}</ref>

[[Antinatalist]] philosopher [[David Benatar]] concludes that any popular concern about non-human species extinction usually arises out of concern about how the loss of a species will impact human wants and needs, that "we shall live in a world impoverished by the loss of one aspect of faunal diversity, that we shall no longer be able to behold or use that species of animal." He notes that typical concerns about possible human extinction, such as the loss of individual members, are not considered in regards to non-human species extinction.<ref>{{cite book |last=Benatar |first=David |author-link=David Benatar |date=2008 |title=Better Never to Have Been: The Harm of Coming into Existence |url=https://archive.org/details/betternevertohav0000bena/page/197 |publisher=Oxford University Press |page=[https://archive.org/details/betternevertohav0000bena/page/197 197] |isbn=978-0-19-954926-9 |quote=It is noteworthy that human concern about human extinction takes a different form from human concern (where there is any) about the extinction of non-human species. Most humans who are concerned about the extinction of non-human species are not concerned about the individual animals whose lives are cut short in the passage to extinction, even though that is one of the best reasons to be concerned about extinction (at least in its killing form). The popular concern about animal extinction is usually concern for humans—that we shall live in a world impoverished by the loss of one aspect of faunal diversity, that we shall no longer be able to behold or use that species of animal. In other words, none of the typical concerns about human extinction are applied to non-human species extinction.}}</ref> Anthropologist [[Jason Hickel]] speculates that the reason humanity seems largely indifferent to anthropogenic mass species extinction is that we see ourselves as separate from the natural world and the organisms within it. He says that this is due in part to the logic of [[capitalism]]: "that the world is not really alive, and it is certainly not our kin, but rather just stuff to be extracted and discarded – and that includes most of the human beings living here too."<ref>{{cite book |last=Hickel |first=Jason |author-link=Jason Hickel |title=Less is More: How Degrowth Will Save the World |year=2021 |publisher=Windmill Books |page=80 |isbn=978-1-78609-121-5 |quote=It's no wonder that we react so nonchalantly to the ever-mounting statistics about the crisis of mass extinction. We have a habit of taking this information with surprising calm. We don't weep. We don't get worked up. Why? Because we see humans as fundamentally separate from the rest of the living community. Those species are out there, in the environment. They aren't in here; they aren't part of us. It is not surprising that we behave this way. After all, this is the core principle of capitalism: that the world is not really alive, and it is certainly not our kin, but rather just stuff to be extracted and discarded – and that includes most of the human beings living here too. From its very first principles, capitalism has set itself at war against life itself.}}</ref>

=== Planned extinction ===<!-- This section is linked from [[Gene knockout]] -->
{{Main|Eradication of infectious diseases}}

==== Completed ====
* The [[smallpox]] virus is now extinct in the wild,<ref name=WHO_Factsheet>{{cite web |title=Smallpox |work=WHO Factsheet |url=https://www.who.int/mediacentre/factsheets/smallpox/en/ |archive-url=https://web.archive.org/web/20070921235036/http://www.who.int/mediacentre/factsheets/smallpox/en/ |archive-date=2007-09-21}}</ref> although samples are retained in laboratory settings.
* The [[rinderpest]] virus, which [[Cattle diseases|infected domestic cattle]], is now extinct in the wild.<ref name="Normile2008">{{cite journal |last1=Normile |first1=Dennis |title=Driven to Extinction |journal=Science |date=21 March 2008 |volume=319 |issue=5870 |pages=1606–1609 |doi=10.1126/science.319.5870.1606 |pmid=18356500 |s2cid=46157093}}</ref>

==== Proposed ====
===== Disease agents =====
The [[poliovirus]] is now confined to small parts of the world due to extermination efforts.<ref name="polio">{{cite web |url=http://www.polioeradication.org/Dataandmonitoring.aspx |title=Polio cases in the world in 2015 |publisher=The Global Polio Eradication Initiative |access-date=17 February 2016 |archive-date=19 February 2016 |archive-url=https://web.archive.org/web/20160219015412/http://www.polioeradication.org/Dataandmonitoring.aspx |url-status=live}}</ref>

''[[Dracunculus medinensis]]'', or Guinea worm, a parasitic worm which causes the disease [[dracunculiasis]], is now close to eradication thanks to efforts led by the [[Carter Center]].<ref>{{cite magazine |url=https://time.com/3680439/guinea-worm-almost-extinct/ |title=This Species is Close to Extinction and That's a Good Thing |date=23 January 2015 |magazine=Time |access-date=17 February 2016 |archive-date=24 February 2016 |archive-url=https://web.archive.org/web/20160224032526/http://time.com/3680439/guinea-worm-almost-extinct/ |url-status=live}}</ref>

''[[Treponema pallidum|Treponema pallidum pertenue]]'', a bacterium which causes the disease [[yaws]], is in the process of being eradicated.

===== Disease vectors =====
Biologist [[Olivia Judson]] has advocated the deliberate extinction of certain disease-carrying [[mosquito]] species. In an article in ''[[The New York Times]]'' on 25 September 2003, she advocated "specicide" of thirty mosquito species by introducing a genetic element that can insert itself into another crucial gene, to create [[recessive]] "[[Gene knockout|knockout genes]]".<ref name="Judson"/> She says that the ''[[Anopheles]]'' mosquitoes (which spread [[malaria]]) and ''[[Aedes]]'' mosquitoes (which spread [[dengue fever]], [[yellow fever]], [[elephantiasis tropica|elephantiasis]], and other diseases) represent only 30 of around 3,500 mosquito species; eradicating these would save at least one million human lives per year, at a cost of reducing the [[genetic diversity]] of the family [[Culicidae]] by only 1%. She further argues that since species become extinct "all the time" the disappearance of a few more will not destroy the [[ecosystem]]: "We're not left with a wasteland every time a species vanishes. Removing one species sometimes causes shifts in the populations of other species—but different need not mean worse." In addition, anti-malarial and [[Mosquito#Control|mosquito control programs]] offer little realistic hope to the 300&nbsp;million people in [[developing nation]]s who will be infected with acute illnesses this year. Although trials are ongoing, she writes that if they fail "we should consider the ultimate swatting".<ref name="Judson">{{cite news |url=https://www.nytimes.com/2003/09/25/opinion/a-bug-s-death.html |title=A Bug's Death |date=September 25, 2003 |last=Judson |first=Olivia |author-link=Olivia Judson |newspaper=The New York Times |access-date=17 February 2016 |archive-date=6 March 2016 |archive-url=https://web.archive.org/web/20160306163542/http://www.nytimes.com/2003/09/25/opinion/a-bug-s-death.html |url-status=live}}</ref>

Biologist [[E. O. Wilson]] has advocated the eradication of several species of mosquito, including malaria vector ''[[Anopheles gambiae]]''. Wilson stated, "I'm talking about a very small number of species that have co-evolved with us and are preying on humans, so it would certainly be acceptable to remove them. I believe it's just common sense."<ref>{{cite news |last1=Paulson |first1=Steve |title=Why a famous biologist wants to eradicate killer mosquitoes |url=https://theworld.org/stories/2016-04-04/why-famous-biologist-wants-eradicate-killer-mosquitoes |work=The World from PRX |date=4 April 2016 |access-date=9 February 2022 |archive-date=9 February 2022 |archive-url=https://web.archive.org/web/20220209131520/https://theworld.org/stories/2016-04-04/why-famous-biologist-wants-eradicate-killer-mosquitoes |url-status=live}}</ref>

There have been many campaigns – some successful – to locally eradicate [[tsetse fly|tsetse flies]] and their [[trypanosoma|trypanosome]]s in areas, countries, and islands of Africa (including [[Príncipe]]).<ref name="Costa-et-al-1916">{{cite book |title=Sleeping Sickness, A Record of Four Years' War against It in the Island of Principe |first1=B. F. |last1=Bruto da Costa |first2=J. F. |last2=Sant' Anna |first3=A. C. |last3=dos Santos |first4=M. G. |last4=de Araujo Alvares |translator-first=J. A. |translator-last=Wyllie |pages=xxii+260 |publisher=Centro Colonial ([[Baillière Tindall]] and Cox) |location=[[Lisbon]] |date=1916 |s2cid=82867664}} (Other {{S2CID|82229617}})</ref><ref name="Nature-book-review-1916">{{cite journal |author=J. W. W. S. |title=The Eradication of Sleeping Sickness from Principe |journal=[[Nature (journal)|Nature]] |publisher=[[Nature Research]] |volume=98 |issue=2460 |year=1916 |doi=10.1038/098311a0 |pages=311–312 |bibcode=1916Natur..98..311J |s2cid=3964040 |doi-access=free}}</ref> There are currently serious efforts to do away with them all across Africa, and this is generally viewed as beneficial and morally necessary,<ref name="Simarro-et-al-2008">{{cite journal |last1=Simarro |first1=Pere P. |last2=Jannin |first2=Jean |last3=Cattand |first3=Pierre |title=Eliminating Human African Trypanosomiasis: Where Do We Stand and What Comes Next? |journal=[[PLOS Medicine]] |publisher=[[Public Library of Science]] (PLoS) |volume=5 |issue=2 |date=2008-02-26 |doi=10.1371/journal.pmed.0050055 |article-number=e55 |pmid=18303943 |pmc=2253612 |s2cid=17608648 |doi-access=free}}</ref> although not always.<ref name="Bouyer-et-al-2018">{{cite journal |last1=Bouyer |first1=Jérémy |last2=Carter |first2=Neil H |last3=Batavia |first3=Chelsea |last4=Nelson |first4=Michael Paul |author-link4=Michael P. Nelson |title=The Ethics of Eliminating Harmful Species: The Case of the Tsetse Fly |journal=[[BioScience]] |publisher=[[American Institute of Biological Sciences]] and [[Oxford University Press]] |volume=69 |issue=2 |date=2018-12-19 |doi=10.1093/biosci/biy155 |pages=125–135 |pmid=30792543 |pmc=6377282 |s2cid=67788418 |doi-access=free}}</ref>

=== Cloning ===
{{Main|De-extinction}}
[[File:Pyrenean Ibex.png|thumb|upright|The [[Pyrenean ibex]], the only animal to have been brought back from extinction and the only one to go extinct twice. The ibex apparently only lived for several minutes.]]

Some, such as Harvard geneticist [[George M. Church]], believe that ongoing technological advances will let us "bring back to life" an extinct species by [[Cloning#Cloning extinct and endangered species|cloning]], using [[DNA]] from the remains of that species. Proposed targets for cloning include the [[mammoth]], the [[thylacine]], and the [[Pyrenean ibex]]. For this to succeed, enough individuals would have to be cloned, from the DNA of different individuals (in the case of sexually reproducing organisms) to create a viable population. Though [[bioethics|bioethical]] and [[philosophy|philosophical]] objections have been raised,<ref>{{cite news |url=http://articles.latimes.com/2000/dec/24/news/mn-4250/2 |title=Cloned Goat Would Revive Extinct Line |author=A. Zitner |date=2000-12-24 |work=[[Los Angeles Times]] |access-date=2010-05-17 |archive-date=25 August 2011 |archive-url=https://web.archive.org/web/20110825212540/http://articles.latimes.com/2000/dec/24/news/mn-4250/2 }}</ref> the cloning of extinct creatures seems theoretically possible.<ref>{{cite news |url=https://www.nytimes.com/2008/11/20/science/20mammoth.html?_r=1 |title=Regenerating a Mammoth for $10 Million |author=Nicholas Wade |author-link=Nicholas Wade |date=2008-11-19 |access-date=2010-05-17 |work=The New York Times |archive-date=12 March 2017 |archive-url=https://web.archive.org/web/20170312075740/http://www.nytimes.com/2008/11/20/science/20mammoth.html?_r=1 |url-status=live |quote=The cell could be converted into an embryo and brought to term by an elephant, a project he estimated would cost some $10 million. 'This is something that could work, though it will be tedious and expensive,&nbsp;...'}}</ref>

In 2003, scientists tried to clone the extinct Pyrenean ibex (''C. p. pyrenaica'').<ref>{{cite journal |last1=Folch |first1=J. |last2=Cocero |first2=M. J. |last3=Chesné |first3=P. |last4=Alabart |first4=J. L. |last5=Domínguez |first5=V. |display-authors=1 |date=2009 |title=First birth of an animal from an extinct subspecies (Capra pyrenaica pyrenaica) by cloning |journal=Theriogenology |volume=71 |issue=6 |pages=1026–1034 |doi=10.1016/j.theriogenology.2008.11.005 |pmid=19167744 |doi-access=free}}</ref> This attempt failed: of the 285 embryos reconstructed, 54 were transferred to 12 [[Spanish ibex]]es and ibex–domestic [[goat]] hybrids, but only two survived the initial two months of gestation before they, too, died.<ref>{{cite news |url=https://www.independent.co.uk/news/science/cloned-goat-dies-after-attempt-to-bring-species-back-from-extinction-1522974.html |title=Cloned goat dies after attempt to bring species back from extinction |author=Steve Connor |date=2009-02-02 |work=[[The Independent]] |access-date=2010-05-17 |location=London |archive-date=13 October 2017 |archive-url=https://web.archive.org/web/20171013205333/http://www.independent.co.uk/news/science/cloned-goat-dies-after-attempt-to-bring-species-back-from-extinction-1522974.html |url-status=live}}</ref> In 2009, a second attempt was made to clone the Pyrenean ibex: one clone was born alive, but died seven minutes later, due to physical defects in the lungs.<ref>{{cite news |title=Extinct ibex is resurrected by cloning |url=https://www.telegraph.co.uk/news/science/science-news/4409958/Extinct-ibex-is-resurrected-by-cloning.html |archive-url=https://ghostarchive.org/archive/20220111/https://www.telegraph.co.uk/news/science/science-news/4409958/Extinct-ibex-is-resurrected-by-cloning.html |archive-date=2022-01-11 |url-access=subscription |url-status=live |newspaper=The Telegraph |date=31 Jan 2009 |location=London |first1=Richard |last1=Gray |first2=Roger |last2=Dobson}}{{cbignore}}</ref>

==See also==
{{Portal|Environment|Biology|Ecology}}
{{cmn|colwidth=30em|
* [[Bioevent]]
* [[Empty forest]]
* [[Endling]]
* [[Extinction: The Facts|''Extinction: The Facts'' (2020 documentary)]]
* [[Genocide]]
* [[Habitat fragmentation]]
* [[Lists of extinct animals]]
* [[List of extinct birds]]
* [[Living Planet Index]]
* [[Our Final Hour]]
* [[Refugium (population biology)]]
* [[Sepilok Orangutan Rehabilitation Centre]]
* ''[[The Sixth Extinction: An Unnatural History|The Sixth Extinction]]'' (2014 book)
* [[Voluntary Human Extinction Movement]]
}}

==References==
{{Reflist}}

==Further reading==
* {{cite book |last1=Day |first1=David |title=The Doomsday Book of Animals: A Natural History of Vanished Species |date=1981 |publisher=Viking Press |location=New York |isbn=978-0-670-27987-6}}
* {{cite journal |last1=Dirzo |first1=Rodolfo |author-link1=Rodolfo Dirzo |last2=Ceballos |first2=Gerardo |last3=Ehrlich |first3=Paul R. |author-link3=Paul R. Ehrlich |date=2022 |title=Circling the drain: the extinction crisis and the future of humanity |url= |journal=[[Philosophical Transactions of the Royal Society B]] |volume=377 |issue=1857 |article-number=20210378 |doi=10.1098/rstb.2021.0378 |pmid=35757873 |pmc=9237743}}
* {{cite web |title=Bringing back the woolly mammoth and other extinct creatures may be impossible |website=Science |author=Elizabeth Pennisi |author-link=Elizabeth Pennisi |date=9 Mar 2022 |url=https://www.science.org/content/article/bringing-back-woolly-mammoth-and-other-extinct-creatures-may-be-impossible}}
*{{cite news |last=Pelley |first=Scott |author-link=Scott Pelley |date=1 January 2023 |title=Scientists say planet in midst of sixth mass extinction, Earth's wildlife running out of places to live |url=https://www.cbsnews.com/news/earth-mass-extinction-60-minutes-2023-01-01/ |work=[[CBS News]] |location= }}

== External links ==
{{Wiktionary|extinction}}
{{Commons category|Extinction}}
{{Wikiquote}}
{{NIE Poster|Extinction of Species}}
* [http://creo.amnh.org Committee on recently extinct organisms]
* [https://www.theguardian.com/environment/series/the-age-of-extinction The age of extinction] series in ''[[The Guardian]]''
* [http://sresearch.scienceontheweb.net/evolution.php Extincion events connected with New theory of evolution]

{{Extinction|state=expanded}}
{{Doomsday}}
{{Zoos}}
{{Deforestation and desertification}}
{{Death}}
{{Authority control}}

[[Category:Extinction| ]]
[[Category:Biota by conservation status]]
[[Category:Environmental conservation]]
[[Category:Evolutionary biology]]
[[Category:IUCN Red List]]