Dysgenics (also known as cacogenics) is the decrease in prevalence of traits deemed to be either socially desirable or well adapted to their environment due to selective pressure disfavoring the reproduction of those traits.
The adjective "dysgenic" is the antonym of "eugenic". In 1915 the term was used by David Starr Jordan to describe the supposed deleterious effects of modern warfare on group-level genetic fitness because of its tendency to kill physically healthy men while preserving the disabled at home. Similar concerns had been raised by early eugenicists and social Darwinists during the 19th century, and continued to play a role in scientific and public policy debates throughout the 20th century. More recent concerns about supposed dysgenic effects in human populations have been advanced by the controversial psychologist Richard Lynn, notably in his 1996 book Dysgenics: Genetic Deterioration in Modern Populations, which argued that a reduction in selection pressures and decreased infant mortality since the Industrial Revolution have resulted in an increased propagation of deleterious traits and genetic disorders. In popular culture, concerns about dysgenics have also formed the basis for speculative fiction, notably the 2006 film Idiocracy.
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 Marching Morons", civilization is kept afloat by a small group of dedicated geniuses, in Idiocracy, voluntary childlessness among high-IQ couples leaves only automated systems to fill that role.
- Rédei, George P. (2008). Encyclopedia of Genetics, Genomics, Proteomics, and Informatics, Volume 1. Springer. p. 572. ISBN 978-1-4020-6755-6.
- Jordan, David Starr (2003). War and the Breed: The Relation of War to the Downfall of Nations (Reprint ed.). Honolulu: University Press of the Pacific. ISBN 978-1-4102-0900-9.
- Carlson, Elof Axel (2001). The Unfit: A History of a Bad Idea. Cold Spring Harbor Laboratory Press. pp. 189–193. ISBN 9780879695873.
- Carlson, Elof Axel (2001). The Unfit: A History of a Bad Idea. Cold Spring Harbor Laboratory Press. ISBN 9780879695873.
- Richard Lynn: Dysgenics: genetic deterioration in modern populations Westport, Connecticut. : Praeger, 1996., ISBN 978-0-275-94917-4.
- Fischbach, Karl-Friedrich; Niggeschmidt, Martin (2022). "Do the Dumb Get Dumber and the Smart Get Smarter?". Heritability of Intelligence. Springer. pp. 37–39. doi:10.1007/978-3-658-35321-6_9. ISBN 978-3-658-35321-6. S2CID 244640696.
Since the nineteenth century, a 'race deterioration' has been repeatedly predicted as a result of the excessive multiplication of less gifted people (Galton 1869; see also Fig. 9.1). Nevertheless, the educational and qualification level of people in the industrialized countries has risen strongly. The fact that the 'test intelligence' has also significantly increased (Flynn 2013), is difficult to explain for supporters of the dysgenic thesis: they suspect that the 'phenotypic intelligence' has increased for environmental reasons, while the 'genotypic quality' secretly decreases (Lynn 1996, p. 111). There is neither evidence nor proof for this theory.
- Conley, Dalton; Laidley, Thomas; Belsky, Daniel W.; Fletcher, Jason M.; Boardman, Jason D.; Domingue, Benjamin W. (14 June 2016). "Assortative mating and differential fertility by phenotype and genotype across the 20th century". Proceedings of the National Academy of Sciences. 113:24 (24): 6647–6652. doi:10.1073/pnas.1523592113. PMC 4914190. PMID 27247411.
- Bratsberg, Bernt; Rogeberg, Ole (26 June 2018). "Flynn effect and its reversal are both environmentally caused". Proceedings of the National Academy of Sciences. 115:26 (26): 6674–6678. doi:10.1073/pnas.1718793115. PMC 6042097. PMID 29891660.
- Neisser, Ulric (1998). The Rising Curve: Long-Term Gains in IQ and Related Measures. American Psychological Association. pp. xiii–xiv. ISBN 978-1557985033.
There is no convincing evidence that any dysgenic trend exists. . . . It turns out, counterintuitively, that differential birth rates (for groups scoring high and low on a trait) do not necessarily produces changes in the population mean.
- Mitchell, Dan (2006-09-09). "Shying away from Degeneracy". The New York Times. Retrieved 2008-06-29.
- Devlin, Bernie; Fienberg, Stephen E.; Resnick, Daniel P.; et al., eds. (1997). Intelligence, Genes, and Success: Scientists Respond to the Bell Curve. New York: Springer. ISBN 978-0-387-94986-4.
- Neisser, Ulric, ed. (1998). The Rising Curve: Long-Term Gains in IQ and Related Measures. APA Science Volume Series. Washington, DC: American Psychological Association. ISBN 978-1-55798-503-3.
- Beauchamp, Jonathan P. (11 July 2016). "Genetic evidence for natural selection in humans in the contemporary United States". Proceedings of the National Academy of Sciences. 113 (28): 7774–7779. doi:10.1073/pnas.1600398113. PMC 4948342. PMID 27402742.
- Barban et al. 2016, "Genome-wide analysis identifies 12 loci influencing human reproductive behavior"