Academic journal article The Journal of Social, Political, and Economic Studies

Differential Intelligence and National Income

Academic journal article The Journal of Social, Political, and Economic Studies

Differential Intelligence and National Income

Article excerpt

IQ and the Wealth of Nations Richard Lynn and Tatu Vanhanen Praeger, Westport Connecticut 2002 256 pp., U.S. $64.95, ISBN 0-275-97510-X

That populations which possess high average IQ (probably for genetic reasons) tend to have high incomes is an obvious hypothesis, but a very politically incorrect one. Hence it is one that has seldom been even mentioned in the literature on economic development. However, Richard Lynn and Tatu Vanhanen in their IQ and the Wealth of Nations have not only put forward this hypothesis, but tested it. Lynn, a United Kingdom psychologist, is probably the world's leading expert on international comparisons of intelligence. In the course of other work he has accumulated a massive database of studies in which IQ tests were given in different countries. Because there are a variety of different tests, scored in different ways, an appreciable amount of work had to be done to make all of the scores compatible. Because tests scores appear to be increasing over time (for reasons that are unknown, although Lynn has speculated that improved nutrition is a major part of the explanation), scores also had to be adjusted for when the tests were given. Vanhanen, a Finnish political scientist, has specialized in comparisons of different nations with different political systems. The result of this international collaboration is a highly provocative book that is a major contribution to the literature on economic development.

Most readers who are interested in why some nations are more highly developed than others (economists, sociologists, political scientists) know little about intelligence. Lynn and Vanhanen start by summarizing the literature on the nature of intelligence, material that is found in books by Jensen (1998), Seligman (1992) and Snyderman and Rothman (1988). While many mental abilities have been identified, these all prove to be correlated with each other. With factorial analysis a common factor can be extracted. This is usually referred to as g and is the best measure of intelligence. However, various intelligence tests are correlated with g and provide adequate measurements of the concept. In the earliest literature, intellectual ability of children was measured by mental age. This was converted to the intelligence quotient by dividing the mental age by the chronological age. Today intelligence scores are measured on a relative scale, but the scores are adjusted to give a measure that is roughly equivalent to the ratio of the mental age to the chronological age. This is referred to as the intelligence quotient, abbreviated IQ.

Within countries intelligence scores have repeatedly been shown to relate to earnings. The best known book discussing this is The Bell Curve (Herrnstein & Murray, 1994). Other relevant material is found in Gottfredson & Sharf (1988) and Hartigan & Wigdor (1989). It is not hard to discover why intelligent people earn more. Intelligence is closely related to both trainability and proficiency. The more intelligent people are more easily trained, and can be taught skills that are virtually impossible for the less intelligent to learn. As a result intelligence is found to be closely related to how far in the education system an individual goes. Secondary school graduate are found to be more intelligent than primary school graduate, university graduates more intelligent than secondary school graduates, and graduate school graduates more intelligent than the typical university graduate. High intelligence is required for success in the professions, including engineering, science, and medicine.

To some this might merely seem to be evidence that intelligence is a learned trait that is taught by the education system. However, the evidence does not support this. At early ages children have not yet been exposed to much education. All the children in a particular school will have been given the same education. Yet the children differ widely in which items on a test they pass, and hence on measured IQ. …

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