IQ and Global Inequality

IQ and Global Inequality is a 2006 book by psychologist Richard Lynn and political scientist Tatu Vanhanen, published by Washington Summit Publishers, a publisher associated with white nationalism. It follows their 2002 book IQ and the Wealth of Nations, expanding its arguments and responding to some of the criticism it received. Its central claim is that intelligence, as measured by IQ tests, makes a significant contribution to national wealth and to social indicators such as adult literacy, tertiary education, life expectancy and the degree of democratization. The authors argue that these differences between countries correlate with average national IQ scores, and they attribute part of the cause to a gene-environment interaction model in which higher IQ leads to better nutrition, education and healthcare, which in turn raises IQ further. They also contend that the racial composition of countries is an important factor, since national IQs can largely be predicted from it and tend to cluster among racially similar countries.

To answer objections about the reliability of their data, the authors estimated national IQs for 71 countries using two different methods and found a correlation of 0.95 between them. Their data came from studies covering 113 nations; for another 79 they estimated the mean from neighbouring countries. All results were adjusted for the Flynn effect and expressed relative to a British mean of 100 with a standard deviation of 15.

The book drew sharp academic criticism of both its methods and its conclusions. Richard E. Nisbett objected to reliance on small, haphazard samples and to the neglect of data that contradicted the thesis, while geographer Stephen Morse judged the hypothesis to rest on serious flaws and unproven causal assumptions. Other researchers, including Heiner Rindermann and Jelte Wicherts and colleagues, examined the estimates for sub-Saharan Africa and found them unreliable or implausibly low. Earl Hunt cited the work as an example of the irresponsible use of science to support policy recommendations. In 2020 the European Human Behavior and Evolution Association issued a statement opposing the use of this national IQ dataset.