They base this argument on the finding that nations' average IQs have a strong correlation with several such factors, among them adult literacy (0.64), tertiary education (0.75), life expectancy (0.77), and democratization (0.57).

[6] University of Reading geographer Stephen Morse also criticized the book (as well as IQ and the Wealth of Nations), arguing that the authors' hypothesis rests on "serious flaws".

Morse also argued: "The central dilemma of the Lynn and Vanhanen case rests with their assumption that national IQ data are primarily (not wholly) a function of innate ability, which in turn is at least partly generated by genes.

"[7] Psychologist J. Philippe Rushton, president of the Pioneer Fund that has been a long time funder of research by Lynn,[8][9] reviewed the book in 2006 for Personality and Individual Differences.

Other problems identified with this study include that Kanazawa incorrectly assumed that individuals migrated from Africa to other continents along linear trajectories, irrespective of physical boundaries, and ignored the fact that geographic distance and evolutionary novelty do not always correspond to each other.

[11] In an article published in the European Journal of Personality, Heiner Rindermann compared the IQ scores from the book to a large number of international student assessment studies on subjects such as reading, mathematics, science, and problem solving, and found them to be highly intercorrelated.

[12] In a 2008 study published in the journal Intelligence, Garry Gelade reported a strong relationship between the book's national IQ estimates and the country's geographical location.

As Lynn rightly remarked during the 2006 conference of the International Society for Intelligence Research (ISIR), performing a literature review involves making a lot of choices.

He considers that by their negligence of observing good scientific practice Lynn and Vanhanen are not living up to the basic responsibility of scientists to make sure that their results can function as reasonable empirical support for policy decisions.

[19] On July 27, 2020, the European Human Behavior and Evolution Association issued a formal statement opposing the utilization of Lynn's national IQ dataset, citing various methodological concerns.