atavism

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.{{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}} 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 tails (called a "coccygeal process", "coccygeal projection", or "caudal appendage").{{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}} Atavism can also be seen in humans who possess large teeth, like those of other primates.{{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}} 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.{{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}} Atavism has also recently been induced in avian dinosaur (bird) fetuses to express dormant ancestral non-avian dinosaur (non-bird) features, including teeth.{{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}}

Other examples of observed atavisms include:

• Hind limbs in cetaceans and sirenians.{{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}}
• Extra toes of the modern horse.{{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 }}{{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}}
• Reappearance of limbs in limbless vertebrates.{{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}}{{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}}
• Re-evolution of sexuality from parthenogenesis in oribatid mites.{{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 }}
• Teeth in avian dinosaurs (birds).{{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 }}
• Dewclaws in dogs.
• Reappearance of prothoracic wings in insects.{{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 }}{{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 }}
• Reappearance of wings on wingless stick insects and leaf insects{{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 }} and earwigs.
• Atavistic muscles in several birds{{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 }}{{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}} and mammals such as the beagle{{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}} and the jerboa.
• Extra toes in guinea pigs.{{Citation | title=The origin of a polydactylous race of guinea-pigs| edition=49| author=William E. Castle| date=1906| publisher=Carnegie Institution of Washington}}
• Reemergence of sexual reproduction in the flowering plant Hieracium pilosella and the Crotoniidae family of mites.{{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 }}

• Webbed feet in adult axolotls.{{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}}
• Human tails (not pseudo-tails){{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}} and supernumerary nipples in humans (and other primates).
• Color blindness in humans.{{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 }}

Atavism is a term in Joseph Schumpeter's explanation of World War I in twentieth-century liberal Europe. He defends the liberal international relations theory that an international society built on commerce will avoid war because of war's destructiveness and comparative cost. His reason for World War I is termed "atavism", in which he asserts that senescent governments in Europe (those of the German Empire, Russian Empire, Ottoman Empire, and Austro-Hungarian Empire) pulled the liberal Europe into war, and that the liberal regimes of the other continental powers did not cause it. He used this idea to say that liberalism and commerce would continue to have a soothing effect in international relations, and that war would not arise between nations which are connected by commercial ties.{{cite book | chapter=Imperialism and Capitalism | title=Imperialism and Social Classes | author=Joseph Schumpeter | place=Cleveland | publisher=The World Publishing Company | year=1969| author-link=Joseph Schumpeter }} This latter idea is very similar to the later Golden Arches theory.

University of London professor Guy Standing has identified three distinct sub-groups of the precariat, one of which he refers to as "atavists", who long for what they see as a lost past.{{cite web|url=https://www.weforum.org/agenda/2016/11/precariat-global-class-rise-of-populism|title=Meet the precariat, the new global class fuelling the rise of populism|author=Guy Standing|date=2016-11-09|publisher=World Economic Forum}}

{{more citations needed section|date=May 2023}}

During the interval between the acceptance of evolution in the mid-1800s and the rise of the modern understanding of genetics in the early 1900s, atavism was used to account for the reappearance in an individual of a trait after several generations of absence—often called a "throw-back".{{Citation needed|date=January 2017}} The idea that atavisms could be made to accumulate by selective breeding, or breeding back, led to breeds such as Heck cattle.{{Citation needed|date=January 2017}} This had been bred from ancient landraces with selected primitive traits, in an attempt of "reviving" the aurochs, an extinct species of wild cattle.{{Citation needed|date=January 2017}} The same notions of atavisms were used by social Darwinists, who claimed that "inferior" races displayed atavistic traits, and represented more primitive traits than other races.{{Citation needed|date=January 2017}} Both atavism's and Ernst Haeckel's recapitulation theory are related to evolutionary progress, as development towards a greater complexity and a superior ability.{{Citation needed|date=January 2017}}

In addition, the concept of atavism as part of an individualistic explanation of the causes of criminal deviance was popularised by the Italian criminologist Cesare Lombroso in the 1870s.{{cite web|url=http://www.criminology.fsu.edu/crimtheory/lombroso.htm |title=Lombroso and the pathological perspective can be traced back to the 19th century following a history of demonic and classical perspectives |publisher=Criminology.fsu.edu |date=2000-11-27 |access-date=2013-12-04 |url-status=dead |archive-url=https://web.archive.org/web/20130923231227/http://www.criminology.fsu.edu/crimtheory/lombroso.htm |archive-date=2013-09-23 }} He attempted to identify physical characteristics common to criminals and labeled those he found as atavistic, 'throw-back' traits that determined 'primitive' criminal behavior. His statistical evidence and the closely related idea of eugenics have long since been abandoned by the scientific community, but the concept that physical traits may affect the likelihood of criminal or unethical behavior in a person still has some scientific support.{{Cite journal | last1 = Haselhuhn | first1 = M. P. | last2 = Wong | first2 = E. M. | title = Bad to the bone: Facial structure predicts unethical behaviour | doi = 10.1098/rspb.2011.1193 | journal = Proceedings of the Royal Society B| year = 2011 | pmid = 21733897 | volume=279 | issue=1728 | pages=571–576| pmc = 3234568 }}

• Atavistic regression
• Exaptation
• Spandrel (biology)
• Torna atrás

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{{Wiktionary|atavism}}

{{Wikiquote}}

• {{cite journal |last1=Bar-Maor |first1=JA |last2=Kesner |first2=KM |last3=Kaftori |first3=JK |title=Human tails |journal=The Journal of Bone and Joint Surgery. British Volume |date=November 1980 |volume=62-B |issue=4 |pages=508–510 |doi=10.1302/0301-620x.62b4.7430236 |pmid=7430236 }}
• [https://web.archive.org/web/20130413103330/http://www.scheffel.og.bw.schule.de/faecher/science/biologie/evolution/2befunde/atav.gif Photograph of an additional (third) hoof of cows]

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Category:Evolutionary biology

Category:Genetics