Lynn, Richard and Tatu Vanhanen. IQ and the Wealth of Nations. Westport, CT: Praeger, 2002. ISBN 0-275-97510-X.
Kofi Annan, Secretary General of the United Nations, said in April 2000 that intelligence “is one commodity equally distributed among the world's people”. But is this actually the case? Numerous studies of the IQ of the populations of various countries have been performed from the 1930s to the present and with few exceptions, large variations have been found in the mean IQs of countries—more than two standard deviations between the extremes—while different studies of the same population show remarkable consistency, and countries with similar populations in the same region of the world tend to have roughly the same mean IQ. Many social scientists believe that these results are attributable to cultural bias in IQ tests, or argue that IQ tests measure not intelligence, but rather proficiency in taking IQ tests, which various educational systems and environments develop to different degrees. The authors of this book accept the IQ test results at face value and pose the question, “Whatever IQ measures, how accurately does the average IQ of a country's population correlate with its economic success, measured both by per capita income and rate of growth over various historical periods?” From regression studies of 81 countries whose mean population IQ is known and 185 countries where IQ is known or estimated based on neighbouring countries, they find that IQ correlates with economic development better than any other single factor advanced in prior studies. IQ, in conjunction with a market economy and, to a lesser extent, democratic governance “explains” (in the strict sense of the square of the correlation coefficient) more than 50% of the variation in GDP per capita and other measures of economic development (of course, IQ, economic freedom, and democracy may not be independent variables). Now, correlation is not causation, but the evidence that IQ stabilises early in childhood and remains largely constant afterward allows one to rule out many potential kinds of influence by economic development on IQ, strengthening the argument for causation. If this is the case, the consequences for economic assistance are profound. For example, providing adequate nutrition during pregnancy and for children, which is known to substantially increase IQ, may not only be the humanitarian thing to do but could potentially promote economic progress more than traditional forms of development assistance. Estimating IQ and economic development for a large collection of disparate countries is a formidable challenge, and this work contains more correction, normalisation, and adjustment factors than a library full of physics research—close to half the book is data tables and source documentation, and non-expert readers cannot be certain that source data might not have been selected which tend to confirm the hypothesis and others excluded. But this is a hypothesis which can be falsified by further research, which would seem well-warranted. Scientists and policy makers must live in the real world and are ill advised to ignore aspects of it which make them uncomfortable. (If these comments move you to recommend Stephen Jay Gould's The Mismeasure of Man, you needn't—I've read it twice before I started keeping this list, and found it well-argued. But you may also want to weigh the points raised in J. Philippe Rushton's critique of Gould's book.)

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