Dysgenics (also known as cacogenics) 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.
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. 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.
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. 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.
Lynn and Harvey (2008) 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. The Chinese one-child policy was an example of how fertility can be regulated by authoritarian means.Geoffrey Miller claims the one-child policy was implemented to reduce China's population explosion, and "to reduce dysgenic fertility among rural peasants." 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."
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.
^"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.
^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.
^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.
^"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.
Devlin, Bernie; Fienberg, Stephen E.; Resnick, Daniel P.; et al., eds. (1997). Intelligence, Genes, and Success: Scientists Respond to the Bell Curve. New York (NY): Springer. ISBN978-0-387-94986-4. Lay summary (13 November 2010).