Genetic deterioration

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.

Dysgenic mutations have been studied in animals such as the mouse and the fruit fly.

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.

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.

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.

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