World Library  
Flag as Inappropriate
Email this Article
 

Atavism

Early embryos of various species display some ancestral features, like the tail on this human foetus. These features normally disappear in later development, but it may not happen if the animal has an atavism.[1]

Atavism is the tendency to revert to ancestral type. In biology, an atavism is an evolutionary throwback, such as traits reappearing which had disappeared generations before.[2] Atavisms can occur in several ways. One way is when genes for previously existing phenotypical features are preserved in DNA, and these become expressed through a mutation that either knock out the overriding genes for the new traits or make the old traits override the new one. A number of traits can vary as a result of shortening of the fetal development of a trait (neoteny) or by prolongation of the same. In such a case, a shift in the time a trait is allowed to develop before it is fixed can bring forth an ancestral phenotype.[3]

In the social sciences, atavism is a cultural tendency—for example, people in the modern era reverting to the ways of thinking and acting of a former time. The word atavism is derived from the Latin atavus. An atavus is a great-great-great-grandfather or, more generally, an ancestor.

Contents

  • Biology 1
  • Social Darwinism 2
  • Culture 3
  • See also 4
  • References 5
  • External links 6

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.[4] 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 as well. Babies have been born with a vestigial tail, called "coccygeal process", "coccygeal projection", and "caudal appendage".[2] Atavism can also be seen in humans who possess large teeth, like those of other primates.[5] In addition, a case of "snake heart", the presence of "coronary circulation and myocardial architecture [which resemble] those of the reptilian heart", has also been reported in medical literature.[6]

Examples of observed atavisms in animals include:

Social Darwinism

During the interval between the acceptance of evolution and the rise of modern understanding of genetics, atavism was used to account for the reappearance in an individual of a trait after several generations of absence. Such an individual was sometimes called a "throwback". The notion that somehow, atavisms could be made to accumulate by selective breeding, or breeding back, led to breeds such as the Heck cattle. This had been bred from ancient landraces with selected primitive traits, in an attempt of "reviving" the extinct aurochs.

The notion of atavism was used frequently by social Darwinists, who claimed that inferior races displayed atavistic traits, and represented more primitive traits than their own race. Both the notion of atavism, and Haeckel's recapitulation theory, are related to notions of evolution as progress, as development towards greater complexity and superior ability.

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.[10] He attempted to identify physical characteristics common to criminals and labeled those he found as atavistic, 'throwback' 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.[11]

Culture

The term atavism is sometimes also applied in the discussion of culture.[12] Some social scientists describe the return of older, "more primitive" tendencies (e.g. warlike attitudes, "clan identity", anything suggesting the social and political atmosphere of thousands of years ago) as "atavistic". "Resurgent atavism" is a common name for the belief that people in the modern era are beginning to revert to ways of thinking and acting that are throwbacks to a former time. This is especially used by sociologists in reference to violence.

The neo-pagan subculture also uses this same terminology ("atavism" or "resurgent atavism") to describe how modern, western countries are experiencing both the decline of Christianity and the rise of religious movements inspired by the pagan religions of centuries past. Some cite the rise of environmentalism, scientific inquiry, and liberalization of society as contributing to an increasingly secular society, one in which religious sentiments are more frequently tied with an appreciation of the physical world rather than set against it. The book Lords of Chaos portrays pagan and occult atavism as an inherently destructive thing, stating that a rash of church burnings across Scandinavia is part of this trend, because many of the perpetrators were pagans seeking to overthrow the establishment they deemed to be the result of centuries of religious oppression of native European religion by Christianity.

Atavism is a key term in Joseph Schumpeter's explanation of World War I in 20th 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 WWI 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.[13]

See also

Related evolutionary concepts:

References

  1. ^
  2. ^ a b c d
  3. ^
  4. ^
  5. ^
  6. ^
  7. ^
  8. ^
  9. ^ Gould, S.J. "Hen's Teeth and Horses' Toes" In: Hen's Teeth and Horse's Toes, New York: W. W. Norton, ISBN 978-0-393-01716-8
  10. ^
  11. ^
  12. ^ An example of this usage of the term can be found in
  13. ^

External links

  • Photograph, X-ray and description of three cases of human tail
  • Photograph of an additional (third) hoof of cows
This article was sourced from Creative Commons Attribution-ShareAlike License; additional terms may apply. World Heritage Encyclopedia content is assembled from numerous content providers, Open Access Publishing, and in compliance with The Fair Access to Science and Technology Research Act (FASTR), Wikimedia Foundation, Inc., Public Library of Science, The Encyclopedia of Life, Open Book Publishers (OBP), PubMed, U.S. National Library of Medicine, National Center for Biotechnology Information, U.S. National Library of Medicine, National Institutes of Health (NIH), U.S. Department of Health & Human Services, and USA.gov, which sources content from all federal, state, local, tribal, and territorial government publication portals (.gov, .mil, .edu). Funding for USA.gov and content contributors is made possible from the U.S. Congress, E-Government Act of 2002.
 
Crowd sourced content that is contributed to World Heritage Encyclopedia is peer reviewed and edited by our editorial staff to ensure quality scholarly research articles.
 
By using this site, you agree to the Terms of Use and Privacy Policy. World Heritage Encyclopedia™ is a registered trademark of the World Public Library Association, a non-profit organization.
 



Copyright © World Library Foundation. All rights reserved. eBooks from World eBook Library are sponsored by the World Library Foundation,
a 501c(4) Member's Support Non-Profit Organization, and is NOT affiliated with any governmental agency or department.