Intelligence, Race, and Genetics: Conversations with Arthur R. Jensen
Westview Press, Boulder, Colorado and Oxford, England, 2002
In 1969 the respected Harvard Educational Review, published a sensational 123 page article which made history and changed the course of research and debate in the area of intelligence, the heritability of intelligence, and its essential relevance not only to academic achievement but also to the likelihood of success in life. This renowned paper was entitled "How can we Boost IQ and Scholastic Achievement," and it appeared at a time when America was struggling to raise the economic level of its substantial black minority by an extensive range of educational programs and policies, as few of these seemed to be having much effect. Written by a 46 year old Berkeley psychologist, who was already well-known in his discipline, this momentous, almost book length article convincingly showed that intelligence was in the largest part genetically controlled, and that although improvements in environmental conditions could undoubtedly raise a child's academic performance, when environmental circumstances were equal, substantial differences in intelligence and intellectual ability often remained and that these were determined by heredity.
The author of this paper, Arthur R. Jensen, had already published extensively in related areas of psychology, but from that time on he became one of the best known names in American academia. Vehemently attacked by a few, but increasingly accepted and respected by a majority of his colleagues, Jensen continued to research and publish in this area, so that he is now the author of more than 400 books and articles, on intelligence, educational psychology, and individual and group differences. Frank Miele's recent book is an excellent introduction to the role of heredity in determining human behavior, since it surveys Jensen's current views on the subject as developed in a further 45 years of research and publishing since that momentous HER article appeared.
The first chapter clarifies for the layman the nature of IQ. Aside from the obvious fact that the Intelligence Quotient is a figure that reflects our ability to perform efficiently in IQ tests, it is well established that persons with a high IQ tend to be more successful throughout their careers. Known as g (for general mental ability) intelligence is a property of the brain that is linked to the individual's ability to perform all kinds of cognitive tasks. An individual's ability to perform specific tasks that are not purely cognitive is affected by a range of special abilities, but intelligence is of paramount importance in any task that requires reasoning ability.
Jensen's rise to fame was rooted in his ability, through an extensive survey of the literature, to advance the study of the relationship between IQ and heredity beyond the level achieved by earlier exponents of the genetic basis of intelligence. Jensen's views on this important topic are synopsized by Miele and presented in the chapter entitled, 'Nature, Nurture, or Both?' The many studies of twins that have been conducted show clearly that the IQ of identical twins (who by definition share virtually 100% of their genes), reared in the same environment (life history cannot be exactly the same for any two individuals no matter how similar the environment), correlates to the level of .86. By comparison, the IQ of twins reared in separate families (in some instances studied, even in different countries) still correlates at the level of .78. And by contrast, the IQ of siblings, who share only 50% of their genes, correlates at .47 if raised in the same home, and only .24 when reared apart. Other case studies show that the intelligence of parents tends to correlate to the level of .42 with that of their natural children raised at home but at the level of only .19 with the intelligence of children they have adopted and raised in their home. …