Editing Atavism (section)

==Biology==
Evolutionarily traits that have disappeared phenotypically do not necessarily disappear from an organism's DNA. The gene sequence often remains, but is inactive. Such an unused gene may remain in the genome for many generations.<ref name=nt/><ref>{{Cite journal| last1 = Collin | first1 = R.| last2 = Cipriani | first2 = R.| year = 2003| title = Dollo's law and the re-evolution of shell coiling| journal = Proceedings of the Royal Society B| volume = 270 | issue = 1533 | pages = 2551–2555| doi = 10.1098/rspb.2003.2517| pmc = 1691546| pmid = 14728776}}</ref> As long as the gene remains intact, a fault in the genetic control suppressing the gene can lead to it being expressed again. Sometimes, the expression of dormant genes can be induced by artificial stimulation.

Atavisms have been observed in humans, such as with infants born with [[vestigial tail]]s (called a "coccygeal process", "coccygeal projection", or "caudal appendage").<ref name="talkorigins">{{cite web|url=http://www.talkorigins.org/faqs/comdesc/section2.html#atavisms|title=29+ Evidences for Macroevolution: Part 2|access-date=2006-11-08| archive-url= https://web.archive.org/web/20061029220608/http://www.talkorigins.org/faqs/comdesc/section2.html| archive-date= 29 October 2006 | url-status= live}}</ref> Atavism can also be seen in humans who possess large teeth, like those of other primates.<ref>{{Cite journal|url=https://www.latimes.com/archives/la-xpm-2007-feb-15-ed-tails15-story.html|title=What our tails tell us|journal=[[Los Angeles Times]]|date=2007-02-15|access-date=2009-03-08|url-status=live|archive-url=https://web.archive.org/web/20090312093607/http://articles.latimes.com/2007/feb/15/opinion/ed-tails15|archive-date=12 March 2009}}</ref> In addition, a case of "snake heart", the presence of "coronary circulation and myocardial architecture [that closely] resemble those of the reptilian heart", has also been reported in medical literature.<ref>{{Cite journal | last1 = Walia | first1 = I. | last2 = Arora | first2 = H. S. | last3 = Barker | first3 = E. A. | last4 = Delgado R.M. | first4 = III | last5 = Frazier | first5 = O. H. | title = Snake Heart: A Case of Atavism in a Human Being | journal = Texas Heart Institute Journal| volume = 37 | issue = 6 | pages = 687–690 | year = 2010 | pmid = 21224948 | pmc = 3014134}}</ref> Atavism has also recently been induced in avian dinosaur (bird) fetuses to express dormant ancestral non-avian dinosaur (non-bird) features, including teeth.<ref>{{Cite news|url=https://www.livescience.com/50886-scientific-progress-dino-chicken.html|title = Dino-Chicken Gets One Step Closer|website = [[Live Science]]|date = 19 May 2015}}</ref>

Other examples of observed atavisms include:
*Hind limbs in [[cetacean]]s and [[sirenia]]ns.<ref name="Briankhall1"/><ref>{{Citation | url=http://www.livescience.com/4298-dolphin-remains-legs.html | title=Dolphin May Have 'Remains' of Legs | author=Hiroko Tabuchi | author-link=Hiroko Tabuchi |publisher=Livescience.com | date=November 5, 2006}}</ref>
*Extra toes of the modern horse.<ref name="Briankhall1"/><ref>{{cite journal |vauthors=Tyson R, Graham JP, Colahan PT, Berry CR |title=Skeletal atavism in a miniature horse |journal=Veterinary Radiology & Ultrasound |volume=45 |issue=4 |pages=315–7 |year=2004 |pmid=15373256 |doi=10.1111/j.1740-8261.2004.04060.x }}</ref><ref>{{Citation | title=Horses: The story of the horse family in the modern world and through sixty million years of evolution| author=Simpson, G. G.| date=1951| publisher=Oxford University Press}}{{page needed|date=May 2019}}</ref>
*Reappearance of limbs in [[limbless vertebrate]]s.<ref name="Briankhall1"/><ref name="Briankhall2">{{Citation | title=Atavisms and atavistic mutations| author=Brian K. Hall| journal=Nature Genetics| year=1995| volume=10| issue=2| pages=126–127| doi=10.1038/ng0695-126| pmid=7663504| s2cid=27868367}}</ref><ref>{{Citation | title=Somites and early morphogenesis in reptile limbs. In Vertebrate Limb and Somite Morphogenesis| author=Raynauad, A.| date=1977| pages=373–386| publisher=Cambridge University Press, London}}</ref>
*Re-evolution of sexuality from [[parthenogenesis]] in [[Oribatida|oribatid mites]].<ref>{{Citation | title=Reevolution of sexuality breaks Dollo's law|author1=Katja Domes | journal=Proc. Natl. Acad. Sci. U.S.A.| year=2007| volume=104| issue=17| pages=7139–7144|display-authors=etal|doi=10.1073/pnas.0700034104| pmid=17438282| pmc=1855408|bibcode=2007PNAS..104.7139D |doi-access=free }}</ref>
*Teeth in avian [[dinosaur]]s ([[bird]]s).<ref>{{Citation | title=The Development of Archosaurian First-Generation Teeth in a Chicken Mutant|author1=Matthew P. Harris | journal=Current Biology| year=2006| volume=16| issue=4| pages=371–377| doi=10.1016/j.cub.2005.12.047| pmid=16488870|display-authors=etal| doi-access=free|bibcode=2006CBio...16..371H }}</ref>
*[[Dewclaw]]s in dogs.<ref name="Briankhall1"/>
*Reappearance of [[Prothorax|prothoracic]] wings in [[insect]]s.<ref>{{cite journal |last1=Elias-Neto |first1=Moysés |last2=Belles |first2=Xavier |title=Tergal and pleural structures contribute to the formation of ectopic prothoracic wings in cockroaches |journal=Royal Society Open Science |date=3 August 2016 |volume=3 |issue=8 |pages=160347 |doi=10.1098/rsos.160347 |pmid=27853616 |pmc=5108966 |bibcode=2016RSOS....360347E }}</ref><ref>{{cite journal |last1=Kukalová-Peck |first1=Jarmila |title=Phylogeny of Higher Taxa in Insecta: Finding Synapomorphies in the Extant Fauna and Separating Them from Homoplasies |journal=Evolutionary Biology |date=11 March 2008 |volume=35 |issue=1 |pages=4–51 |doi=10.1007/s11692-007-9013-4 |bibcode=2008EvBio..35....4K |s2cid=25126171 }}</ref>
*Reappearance of wings on wingless [[Phasmatodea|stick insects and leaf insects]]<ref>{{Citation | title=Loss and recovery of wings in stick insects|author1=Michael F. Whiting | journal=Nature| year=2003| volume=421| issue=6920| pages=264–267| doi=10.1038/nature01313| pmid=12529642|display-authors=etal|bibcode=2003Natur.421..264W |s2cid=962571 }}</ref> and [[earwig]]s.<ref name="Briankhall1"/>
*Atavistic muscles in several [[bird]]s<ref name="Raikowetal">{{Citation | title=The evolutionary re-establishment of a lost ancestral muscle in the bowerbird assemblage.|author1=Robert J. Raikow | journal= Condor| year=1979| volume=81| issue=2| pages=203–206| doi=10.2307/1367290|display-authors=etal|jstor=1367290 }}</ref><ref>{{Citation | title=The evolutionary reappearance of ancestral muscles as developmental anomalies in two species of birds| author=Robert J. Raikow| journal=Condor| year=1975| volume=77| issue=4| pages=514–517| doi=10.2307/1366113| jstor=1366113}}</ref> and [[mammal]]s such as the [[beagle]]<ref>{{Citation | title=Hyoid muscle anomalies in the dog (Canis familiaris)| author=E. Evansh| journal=Anatomical Record| year=1959| volume=133| issue=2| pages=145–162| doi=10.1002/ar.1091330204| pmid=13670435| s2cid=33397424}}</ref> and the [[jerboa]].<ref name="Raikowetal"/>
*Extra toes in [[guinea pigs]].<ref name="Briankhall1"/><ref>{{Citation | title=The origin of a polydactylous race of guinea-pigs| edition=49| author=William E. Castle| date=1906| publisher=Carnegie Institution of Washington}}</ref>
*Reemergence of sexual reproduction in the [[flowering plant]] ''[[Hieracium pilosella]]'' and the [[Crotoniidae]] family of mites.<ref>{{Cite journal | last1 = Domes | first1 = K. | last2 = Norton | first2 = R. A. | last3 = Maraun | first3 = M.| last4 = Scheu | first4 = S. | title = Reevolution of sexuality breaks Dollo's law | doi = 10.1073/pnas.0700034104 | journal = Proceedings of the National Academy of Sciences | volume = 104 | issue = 17 | pages = 7139–7144 | year = 2007 | pmid = 17438282| pmc =1855408 
| bibcode = 2007PNAS..104.7139D | doi-access = free }}</ref>
*Webbed feet in adult [[axolotl]]s.<ref>{{cite journal| last=Meyer-Rochow| first= Victor Benno| year= 1989|title= A report of webbed feet in a mature axolotl ''Siredon mexicanum'' and remarks on webbed feet in Urodela generally| journal= Amphibia-Reptilia| volume= 10|pages=89–92| doi=10.1163/156853889x00340}}</ref>
*[[Human vestigiality|Human tails]] (not pseudo-tails)<ref name=nt/><ref>{{Citation | title=Human tails and pseudotails|author1=Anh H. Dao |author2=Martin G. Netsky | journal=Human Pathology| year=1984| volume=15| issue=5| pages=449–453| doi=10.1016/S0046-8177(84)80079-9| pmid=6373560}}</ref> and [[supernumerary nipples]] in humans (and other primates).<ref name="Briankhall1"/>
*[[Color blindness]] in humans.<ref>{{cite book |doi=10.7551/mitpress/9780262013857.003.0012 |chapter=How do Things Look to the Color-Blind? |title=Color Ontology and Color Science |pages=258–290 |year=2010 |last1=Byrne |first1=Alex |last2=Hilbert |first2=David R. |isbn=978-0-262-01385-7 |url=https://philarchive.org/rec/HILHDT }}</ref>