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Dysgenics is the evolutionary weakening of a population of organisms relative to its environment, often due to relaxation of natural selection or the occurrence of negative selection. This can happen when negative mutations occur without ramification to the organism and accumulate in the species.
In biology, "dysgenesis" refers to faulty or abnormal organ or development — in such cases the organ is then said to be dysgenic.
Dysgenic decline in intelligence
Most of the focus on dysgenics in human populations in recent years has investigated the change in genotypic intelligence. Demographic studies generally indicate that the more intelligent and better educated women in affluent nations have much lower reproductive rates than the less educated, which has led to concern regarding the future of intelligence in these nations. The most cited work is Vining's 1982 study on the fertility of 2,539 U.S. women aged 25 to 34; the average fertility is correlated at -0.86 in IQ for white women and -0.96 for black women, and indicated a drop in the genotypic average IQ of 1.6 per generation for the white population and 2.4 points per generation for the black population. A 2003 study by Richard Lynn and Marian Van Court (2003) returned similar results, with the genotypic decline measuring at 0.9 IQ points for the total sample and 0.75 IQ points for whites only.
These genetic changes may not have yet become apparent in IQ tests due to improved environment and education which is known as the Flynn Effect.
History of the term
According to the Oxford English Dictionary, the term "dysgenic" was first used as an adjective as early as 1915 to describe the "dysgenic effect" of World War I. Amongst eugenicists of this time period, war was initially thought to have a eugenic effect, as it killed off the less fit men of a population. During WWI, however, it became quickly clear that even the fit men were as likely to die from modern warfare as anyone else, and war was seen as killing off only the physically fit male members of the population whilst the disabled stayed safely at home.
The term fell out of use after eugenic thought lost popularity in the 1940s, and when used again by William Shockley (a Nobel laureate in the field of electronics) in his controversial advocacy of eugenics from the mid 1960's until the early 1990's; he and his theories were unfavorably portrayed in the press.
Dysgenics: Genetic deterioration in modern populations is also the title of a controversial 1996 book by the psychologist Richard Lynn, in which he argued that intelligence in Western nations had been decreasing due to dysgenics and conjectures that China may overtake the West due to continued deterioration of intelligence in the Western nations, especially the USA.
The issolated effect of dysgenics may have been masked by the countervailing Flynn effect, the steady increase of IQ in Asian and Western nations during the 20th century, thought to be related to better diets and other environmental factors. Current research shows that the Flynn effect might have already ended around 1990 in several European nations. Teasdale & Owen (2005) "report intelligence test results from over 500,000 young Danish men, tested between 1959 and 2004, showing that performance peaked in the late 1990s, and has since declined moderately to pre-1991 levels." They speculate that "a contributing factor in this recent fall could be a simultaneous decline in proportions of students entering 3-year advanced-level school programs for 16–18 year olds."
Another recent study done by Professor of Education Philip Adey and psychology professor Michael Shayer also show that the Flynn effect may have ended in the United Kingdom. According to Professor Adey, "The intelligence of 11-year-olds has fallen by three years' worth in the past two decades."  The study compared results of IQ tests taken by eleven-year-old children in 2005, the mid 1990s, and 1976, showing a precipitous drop in average IQ.
Cyril M. Kornbluth's short story The Marching Morons is a good example of dysgenic fiction.
Mike Judge's film Idiocracy is a comedy about the decline of intelligence in the future.
- Thomas W. Teasdale and David R. Owen (2005). "A long-term rise and recent decline in intelligence test performance: The Flynn Effect in reverse." Personality and Individual Differences 39(4), pp 837–843.
- Shockley on Eugenics and Race: The Application of Science to the Solution of Human Problems Scott-Townsend, 1992
- Dysgenics Genetic Deterioration in Modern Populations, Richard Lynn, Praeger Publishers, 1996
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