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Two toes in horses ( Equus ): Instead of the stylus bone (rudimentary lateral toe ray), a small, complete toe with a hoof is formed (polydactyly)

An atavism (from Latin atavus `` ancestor ''), outdated also setback , is the reappearance of anatomical features in a living being that were developed in more distant phylogenetic ancestors, but were reduced in the immediate ancestors because they no longer have any function for the current stage of development have. Often atavisms are therefore perceived as malformations . Like the rudiments , they are among the classic evidences of evolution and can occur equally in all living beings.

In a broader sense, the term is also used in ethology for developmentally original behavior of common evolutionary ancestors. Since these are genetically fixed behaviors, ethological atavisms are necessarily innate, never learned .

Anatomical atavisms

With people

Excess nipple in a man

In animals

  • Formation of surplus claws in cattle, camels, horses and goats, a form of polydactyly
  • Formation of the rear extremities in marine mammals such as whales and dolphins or snakes
  • Formation of teeth in the beaks of chickens in talpid2 mutants (could be viewed as artificially induced atavism).
  • spontaneous reappearance of wings in wingless flying insects

With plants

Atavisms in plants are less well known, but they were researched as early as the 19th century. These include, among other things, the formation of peloria in flowering plants, ash trees with only single or triple leaves (single-leaf ash) and cacti with emerging leaves.

For bacteria, fungi and eukaryotic protozoa

Basically, atavistic forms should also occur in bacteria, fungi and protozoa. However, due to the great variability of these organisms and partly not fully understood parentage relationships, they are more difficult to clearly identify and differentiate from neoplasms.

Causes of atavisms

The formation of atavisms can have the following causes:

  • Inhibition of malformations ( paratypical atavism): the species-typical differentiation of organ formation stages temporarily passed through by the embryo with recapitulation of earlier features breaks off due to exogenous disturbance;
  • Mutative atavism: through mutation of certain genes or changes in gene regulation with renewed activation of repressed (latent) genes, phenotypically similarity to an ancestral form arises ;
  • Hybrid -Atavism ( combination of satavism): phenotypically distinctly different genotypes of descendants emerged from a parent form . Their crossing ( hybridization ) results in a gene constellation that is very similar to the genotype of the parent form and also causes a phenotypic similarity.

Behavioral atavism

Behavioral atavisms are innate behaviors that have been discarded in the course of tribal history. For example, individual house sparrows occasionally do not build their nests as usual, but instead set up spherical nests, as are characteristic of original weaver birds . These atavistic spherical nests are not created by imitating a model, but the shape of its nesting place is innate, so the bird acts purely instinctively .

The fight-or-flight syndrome in humans can also be regarded as a behavioral avism, because its species-specific cognitive and communicative abilities take a back seat in favor of instinct-controlled, often irrational reactions.


  • Ulrich Kutschera : Evolutionary Biology. 3rd edition, Ulmer, Stuttgart 2008, ISBN 978-3-8252-8318-6 .
  • Martin Brandt: About 2 cases of abnormal origin and course of the art. Subclavia dextra, at the same time a contribution to the question of secondary atavism. From the Pathological Institute of the University of Wroclaw. Breslau 1921, DNB 570018307 (Medical dissertation University of Breslau 1921, 2 sheets, 8).
  • Reinhard Junker: Rudimentary Organs and Atavisms. Design flaws in life? (= Studium integrale: Biologie. ) Zeitjournal Verlag, Berlin 1989, ISBN 3-927390-03-8 .
  • Christian Köppel, Axel Steiner: A winged female of Operophtera brumata (Lin NAEUS, 1758): A case of atavism . In: Atalanta . tape 25 , no. 3/4 , December 1994, ISSN  0171-0079 , p. 567-569 ( PDF on ZOBODAT ).

Web links

Wiktionary: Atavism  - explanations of meanings, word origins, synonyms, translations

Illustrations of atavisms in humans:

Illustrations of atavisms in animals:

Individual evidence

  1. Atavism . In: Lexicon of Biology . Spectrum Academic Publishing House. Heidelberg. 1999. Retrieved August 17, 2017.
  2. a b Ulrich Lehmann : Paleontological dictionary . 4th edition. Ferdinand Enke Verlag, Stuttgart 1996, p. 23 .
  3. Jimmy Shad, Rakesh Biswas: An infant with caudal appendage . In: BMJ Case Reports . bcr1120115160, 2012, ISSN  1757-790X , doi : 10.1136 / bcr.11.2011.5160 , PMID 22604513 , PMC 3339178 (free full text).
  4. a b c d e Jan Zrzavý, David Storch, Stanislav Mihulka: Evolution A reading textbook . Springer, Berlin Heidelberg 2009, ISBN 978-3-642-39695-3 .
  5. Peter Altmeyer et al.: Dermatological differential diagnosis: The way to clinical diagnosis . Springer Science & Business Media, Berlin 2011, ISBN 978-3-540-39001-5 , p. 594 .
  6. ^ Zuhair Bani-Ismail, Jan F. Hawkins, Jeffrey J. Siems: Surgical correction of polydactyly in a camel (Camelus dromedarius) . In: Journal of Zoo and Wildlife Medicine: Official Publication of the American Association of Zoo Veterinarians . tape 30 , no. 2 , June 1999, ISSN  1042-7260 , p. 301-304 , PMID 10484151 , JSTOR : 20095863 .
  7. Ch. Stanek, Edith Hantak: Bilateral atavistic polydactyly in a colt and its dam . In: Equine Veterinary Journal . tape 18 , no. 1 , 1986, ISSN  0425-1644 , pp. 76-79 , doi : 10.1111 / j.2042-3306.1986.tb03546.x , PMID 3948838 .
  8. ^ Spencer M. Barber: Unusual polydactylism in a foal. A case report . In: Veterinary surgery: VS . tape 19 , no. 3 , May 1990, ISSN  0161-3499 , pp. 203-207 , doi : 10.1111 / j.1532-950X.1990.tb01169.x , PMID 2349776 .
  9. FK Al-Ani, NQ Hailat, MA Fathalla: Polydactyly in Shami breed goats in Jordan . In: Small Ruminant Research . tape 26 , no. 1 , December 1997, ISSN  0921-4488 , p. 177-179 , doi : 10.1016 / S0921-4488 (96) 00955-8 .
  10. Christian Köppel, Axel Steiner: A winged female of Operophtera brumata (Lin NAEUS, 1758): A case of atavism . In: Atalanta . tape 25 , no. 3/4 , December 1994, ISSN  0171-0079 , p. 567-569 ( PDF on ZOBODAT ).
  11. Konstantin Freiherr von Ettingshausen, Franz Krasan: Contributions to the research of the atavistic forms in living plants and their relationships to the species of their genus . 3 parts (1888-1889). K. & K. Hof- und Staatsdruckerei, Vienna ( PDF on ZOBODAT , II. Episode (PDF) on ZOBODAT , III. Episode and conclusion (PDF) on ZOBODAT ).
  12. Atavism . In: Lexikonredaktion of the Bibliographisches Institut (Ed.): Meyers Großes Taschenlexikon . tape 2 . Anh - Bahn . Mannheim / Vienna / Zurich 1983, ISBN 3-411-02102-0 , pp. 210 .