AskDefine | Define dysgenic

Dictionary Definition

dysgenic adj : pertaining to or causing degeneration in the offspring produced [syn: cacogenic] [ant: eugenic]

User Contributed Dictionary



  1. of or relating to, or causing degeneration or deterioration in offspring


Extensive Definition

Dysgenics is a term describing a system of breeding where selection is for deleterious traits. Similarly, it is also described as "the study of factors relating to or causing a decrease in the survival of the genetically well-adapted members of a line of descent." Dysgenic mutations have been studied in a variety of animals such as the mouse and the fruit fly . The existence of a dysgenic trend in humans is often proposed by supporters of eugenics; however, the existence of a dysgenic effect has never been proven in humans, and is generally considered a fringe or even a junk science concept.

History of the term

The term first came into use as an opposite of eugenics, a social philosophy advocating improvement of human hereditary qualities, often by social programs or government intervention.
According to the Oxford English Dictionary, the term "dysgenic" was first used as an adjective as early as 1915 by David Starr Jordan to describe the "dysgenic effect" of World War I. He believed that 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 while the disabled stayed safely at home.
In 1963, Weyl and Possony asserted that comparatively small differences in average IQ can become very large differences in the very high IQ ranges. A decline in average IQ of only a few points will mean a much smaller population of gifted individuals.
A dysgenic effect caused by lead was blamed as the culprit of the Decline of the Roman Empire , however that theory was refuted after measurements of lead from the bones of Roman-era skeletons did not prove to be high enough to adversely affect their health.
William Shockley (a Nobel laureate in Physics) used the term in his controversial advocacy of eugenics from the mid 1960s through the 1980s. Shockley argued that "the future of the population was threatened because people with low IQs had more children than those with high IQs," and his theories "became increasingly controversial and race-based".
Robert K. Graham in 1998 argued that genocide and class warfare, in cases ranging from the French Revolution to the present, have had a dysgenic effect through the killing of the more intelligent by the less intelligent, and "might well incline humanity toward a more primitive, more brutish level of evolutionary achievement."
"Dysgenics" is rarely mentioned in the modern sciences of genetics, evolution, biology or population genetics. The term is omitted from major science dictionaries, encyclopedias and handbooks, and does not appear in The History and Geography of Human Genes, a standard reference on human genetic variation.

Research on differential fertility

A small group of researchers, alleged by some to be motivated by political ideology or racism, has studied differential fertility throughout the first world; demographic studies indicate that, in affluent nations, women with higher IQs and better education have much lower reproductive rates than women with lower IQs and less education. Because IQ and educational attainment are known to be correlated and IQ is in part heritable, these researchers argued that this could cause a decline in IQ in these nations.
Studies into the subject were carried out on individuals starting even before the advent of IQ testing, in the late 19th century. The results obtained were often contradictory.

The Flynn Effect

The most important evidence contradicts claims of dysgenic decline, in fact IQ scores themselves have been increasing, in a trend known as the Flynn Effect. As noted by Steve Connor in his refutation of the existence of a dysgenic trend: "intelligence as measured by IQ tests has actually increased over the past 50 years."
If it is true that the genes underlying IQ have been shifting, it is reasonable to expect that IQ throughout the population should also shift in the same direction, yet the reverse has clearly occurred. Retherford & Sewell claimed that genotypic IQ may fall even while phenotypic IQ rises throughout the population due to environmental effects (e.g. better schooling, nutrition, television, and so on). The Flynn Effect has increased IQ scores as much as 15 points throughout the first world, but some researchers claim that this trend now shows signs of reversal.

Dysgenic fallacy

It is well-established that a negative correlation between fertility and IQ has existed in many parts of the world at various times. It has even been argued that this was true of Ancient Rome.

In music, film and literature

See also



dysgenic in German: Dysgenik
dysgenic in Dutch: Dysgenetica
dysgenic in Portuguese: Disgenia
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