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Dysgenics (also known as cacogenics)[1] is the study of factors producing the accumulation and perpetuation of defective or disadvantageous genes and traits in offspring of a particular population or species.[2][3]

The adjective "dysgenic" is the antonym of "eugenic". It was first used c. 1915 by David Starr Jordan, describing the supposed dysgenic effects of World War I.[4] Jordan believed that healthy men were as likely to die in modern warfare as anyone else and that war killed only the physically healthy men of the populace whilst preserving the disabled at home.[5]

In the context of human genetics, a dysgenic effect is the projected or observed tendency of a reduction in selection pressures and decreased infant mortality since the Industrial Revolution resulting in the increased propagation of deleterious traits and genetic disorders. Richard Lynn in his Dysgenics: Genetic Deterioration in Modern Populations (1996) identified three main concerns: deterioration in health, in intelligence, and in conscientiousness.

Genetic disorders[edit]

Rui Nunes wrote that dysgenics is the selection of genetic traits that are "commonly accepted as a disabling condition," and like eugenics, dysgenics can be positively selected or negatively selected.[6] Nunes defined positive dysgenics as a selection that increases the number of individuals with dysgenic traits, while negative dysgenics is the discarding of genetics that cause disability.[6]

Improved medical and social care may possibly lead to increased incidence of genetic disorders. Practices such as genetic counselling and prenatal screening may counteract this effect.[7][8]

Fertility and intelligence[edit]

Lynn argued that natural selection in pre-industrial societies favored traits such as intelligence and character but no longer does so in modern societies.[9] The hypothesized dysgenic decline in human intelligence is traced to a change in the distribution in fertility and intelligence by Woodley (2015).[10]

Lynn (1996) has received both favourable[11][12][13][14][clarification needed] and unfavourable[15] reviews.[16][17][clarification needed]

Selective fertility[edit]

Lynn and Harvey (2008)[18] suggest that designer babies may have an important counter-acting effect in the future. Initially this may be limited to wealthy couples, who may possibly travel abroad for the procedure if prohibited in their own country and then gradually spread to increasingly larger groups. Alternatively, authoritarian states may decide to impose measures such as a licensing requirement for having a child, which would only be given to persons of a certain minimum intelligence.[citation needed] The Chinese one-child policy was an example of how fertility can be regulated by authoritarian means.[19] Geoffrey Miller claims the one-child policy was implemented to reduce China's population explosion, and "to reduce dysgenic fertility among rural peasants."[20] While the one-child policy made exceptions for rural families so that those families could have 2 children, this only applied "if their first-born is a girl."[21]

In fiction[edit]

Cyril M. Kornbluth's 1951 short story "The Marching Morons" is an example of dysgenic fiction, describing a man who accidentally ends up in the distant future and discovers that dysgenics has resulted in mass stupidity. Mike Judge's 2006 film Idiocracy has the same premise, with the main character the subject of a military hibernation experiment that goes awry, taking him 500 years into the future. While in the Kornbluth short story, civilization is kept afloat by a small group of dedicated geniuses, in Judge's film, voluntary childlessness wipes out the bloodlines of above-average intelligence and leaves only automated systems to fill that role in Idiocracy.[22]

See also[edit]

  • Eugenics
  • Devolution (biology)
  • Heritability of IQ
  • List of congenital disorders
  • List of biological development disorders


  1. "cacogenics". Freedictionary.com. Retrieved 2008-06-29. Cacogenics, the study of the operation of factors that cause degeneration in offspring, especially as applied to factors unique to separate races. Also called dysgenics.
  2. "Bartleby.com: Great Books Online -- Quotes, Poems, Novels, Classics and hundreds more". www.bartleby.com. Archived from the original on 2009-03-18. Unknown parameter |url-status= ignored (help)
  3. "Definition of dysgenics". Merriam-Webster Medical Dictionary.
  4. Oxford English Dictionary
  5. Jordan, David Starr (2003). War and the Breed: The Relation of War to the Downfall of Nations (Reprint ed.). Honolulu, Hawaii: University Press of the Pacific. ISBN 978-1-4102-0900-9. Search this book on Amazon.com Logo.png
  6. 6.0 6.1 Nunes, Rui (March 2006). "Deafness, genetics and dysgenics". Medicine, Health Care and Philosophy. 9 (1): 25–31. doi:10.1007/s11019-005-2852-9. PMID 16645795. Unknown parameter |s2cid= ignored (help)
  7. Holloway, S. M.; Smith, C. (1975). "Effects of various medical and social pracitices on the frequency of genetic disorders". American Journal of Human Genetics. 27 (5): 614–627. PMC 1762830. PMID 1163536.
  8. Matsunaga, E. (1983). "Perspectives in mutation epidemiology: 5. Modern medical practice versus environmental mutagens: Their possible dysgenic impact". Mutation Research/Reviews in Genetic Toxicology. 114 (3): 449–457. doi:10.1016/0165-1110(83)90040-4. PMID 6835245.
  9. Lynn, R. (2008). "Dysgenic fertility for criminal behaviour". Journal of Biosocial Science. 27 (4): 405–408. doi:10.1017/S0021932000023014. PMID 7593047.
  10. Woodley, Michael A. (2015). "How fragile is our intellect? Estimating losses in general intelligence due to both selection and mutation accumulation". Personality and Individual Differences. 75: 80–84. doi:10.1016/j.paid.2014.10.047.
  11. Hamilton, W. D. (2000). "A review of Dysgenics: Genetic Deterioration in Modern Populations". Annals of Human Genetics. 64 (4): 363–374. doi:10.1046/j.1469-1809.2000.6440363.x.[permanent dead link]
  12. Loehlin JC (1999). "Dysgenics: Genetic Deterioration in Modern Populations, reviewed by John C. Loehlin". Annals of the American Academy of Political and Social Science. 561: 216–217. doi:10.1177/0002716299561001039. JSTOR 1049316.
  13. Vining DR (1998). "Dysgenics: Genetic Deterioration in Modern Populations, reviewed by Daniel R. Vining, Jr". Population Studies. 52 (1): 120–121. doi:10.1080/0032472031000150216. JSTOR 2584772.
  14. "Dysgenics: Genetic deterioration in modern populations: by Richard Lynn. Westport, CT: Praeger, 1996, 238 pp. $59.95". Journal of Social and Evolutionary Systems. 21 (3): 343–345. 1998. doi:10.1016/S1061-7361(98)80008-8. This could be one of the most important books written in the last fifty years.
  15. Leon K (February 1995). "The Bell Curve: Intelligence and Class Structure in American Life". Scientific American. 272. Archived from the original on 2007-10-22. Lynn's distortions and misrepresentations of the data constitute a truly venomous racism, combined with scandalous disregard for scientific objectivity. Unknown parameter |url-status= ignored (help)
  16. Rosenthal S. "Academic Nazism". Department of Sociology, Hampton University. Retrieved 2008-06-28.
  17. Berhanu G. "Black Intellectual Genocide: An Essay Review of IQ of Wealth of Nations" (PDF). Gotberg University, Sweden. Archived from the original (PDF) on 2008-07-20. Retrieved 2008-06-28. Unknown parameter |url-status= ignored (help)
  18. Lynn, Richard; Harveyb, John (2008). "The decline of the world's IQ". Intelligence. 36 (2): 112–120. doi:10.1016/j.intell.2007.03.004.
  19. Lynn, R.; Harvey, J. (2008). "The decline of the world's IQ". Intelligence. 36 (2): 112–120. doi:10.1016/j.intell.2007.03.004.
  20. Edge, Chinese Eugenics, http://edge.org/response-detail/23838/
  21. Tsintolas, Alexa. "Exceptions - China's One-Child Policy". Retrieved 14 June 2018.
  22. Mitchell, Dan (2006-09-09). "Shying away from Degeneracy". The New York Times. Retrieved 2008-06-29.

Further reading[edit]

External links[edit]

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