Dysgenics and Eugenics
In Dysgenics: Genetic Deterioration in Modern Populations, Lynn reviews the history of eugenics, from the early writings of Bénédict Morel and Francis Galton through the rise of eugenics in the early 20th century and its subsequent collapse. He identifies three main concerns of eugenicists such as himself: deterioration in health, intelligence and conscientiousness. Lynn asserts that natural selection in pre-industrial societies favored traits such as intelligence and character but no longer do so in modern societies. He argues that due to the advance of medicine, selection against those with poor genes for health was relaxed.
Regarding intelligence, Lynn examines sibling studies. Lynn concludes that the tendency of children with a high number of siblings to be the least intelligent is evidence of dysgenic fertility. Lynn concedes that there has been a genuine increase in phenotypic intelligence, but argues that this is caused by environmental factors and is masking a decline in genotypic intelligence.
Lynn points to evidence that those with greater educational achievement have fewer children, while children with lower IQ come from larger families as primary evidence that intelligence and fertility are negatively correlated. Continuing the theme of correlates of fertility, socioeconomic status appears to have a negative effect on fertility, which Lynn thinks is because there is increasingly ineffective use of contraception with declining socioeconomic class. Regarding intelligence, Lynn agrees with Lewis Terman’s comment in 1922 that "he children of successful and cultivated parents test higher than children from wretched and ignorant homes for the simple reason that their heredity is better".
Lynn goes on to present evidence that socio-economic status is negatively correlated with indicators of conscientiousness such as work ethic, moral values and crime. Next the genetic basis of differences in conscientiousness is discussed, and Lynn concludes that twin studies provide evidence of a high heritability for the trait. The less conscientious, such as criminals, have more offspring.
While most of the book discusses evidence for dysgenics in developed countries, Lynn acknowledges that it is less strong in developing countries, but concludes that "dysgenic fertility is a worldwide phenomenon of modern populations" (p. 196).
Lynn concludes with an examination of counter-arguments. These include that the traits discussed are not genetically determined, that intelligence and fertility can be inversely related without dysgenics, that socio-economic classes do not differ genetically, and that there is no such thing as a ‘bad gene’. These arguments are dismissed, and Lynn asserts that these trends represent a serious problem. Finally, he expresses support for eugenics, which is the subject of his next book, Eugenics: A Reassessment.
A review of Dysgenics by W.D. Hamilton, FRS, Royal Society Research Professor in evolutionary biology at the University of Oxford, was published posthumously in 2000. In this lengthy review, written according to the author in "rambling essay format", Hamilton writes that Lynn, "discussing the large bank of evidence that still accumulates on heritability of aptitudes and differentials of fertility, shows in this book that almost all of the worries of the early eugenicists were well-founded, in spite of the relative paucity of their evidence at the time"; in the second half of the review, several directions not covered in Lynn's book are explored.
Another review of Dysgenics was written in 2002 by N.J. Mackintosh, FRS, Emeritus Professor of Experimental Psychology in the University of Cambridge. Mackintosh writes that, "with a cavalier disregard for political correctness, he argues that the ideas of the eugenecists were correct and that we ignore them at our peril." While recognizing that the book provides a valuable and accurate source of information, he criticizes Lynn for "not fully acknowledg the negative relationship between social class and education on the one hand, and infant mortality and life expectancy on the other." He calls into question Lynn's interpretation of data. He also points out that according to Lynn's reading of the theory of natural selection, "if it is true that those with lower IQ and less education are producing more offspring, then they are fitter than those of higher IQ and more education"; he writes that, on the contrary, the eugenecists' arguments rest not as Lynn suggests on some "biological imperative, but rather on a particular set of value judgements."
In Eugenics: A Reassessment (2001), Lynn argues that embryo selection as a form of standard reproductive therapy would raise the average intelligence of the population by 15 IQ points in a single generation (p. 300). If couples produce a hundred embryos, he argues, the range in potential IQ would be around 15 points above and below the parents' IQ. Lynn argues this gain could be repeated each generation, eventually stabilizing the population's IQ at a theoretical maximum of around 200 after as little as six or seven generations.
Eugenics received praise in the American Psychological Association Review of Books (Lykken 2004) as " excellent, scholarly book ...one cannot reasonably disagree with him on any point unless one can find an argument he has not already refuted.".
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