Dysgenics refers to any decrease in the prevalence of traits deemed to be either socially desirable or generally adaptive to their environment due to selective pressure disfavouring their reproduction,[1]
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.[2][3] 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.[4]
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.[5][6]
Despite these concerns, genetic studies have shown no evidence for dysgenic effects in human populations.[5][7][8][9] Reviewing Lynn's book, the scholar John R. Wilmoth notes: "Overall, the most puzzling aspect of Lynn's alarmist position is that the deterioration of average intelligence predicted by the eugenicists has not occurred."[10]
Since the nineteenth century, a 'race deterioration' has been repeatedly predicted as a result of the excessive multiplication of less gifted people. 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, 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. There is neither evidence nor proof for this theory.Citations in original omitted.
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 produce changes in the population mean.
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