National IQ Research Articles

COMMENTS ON THE PAPER BY LYNN ET AL. ON THE INTERPRETATION OF CORRELATIONS BETWEEN IQ AND ACHIEVEMENT TEST SCORES

In a recent article in this journal, Lynn et al. (2007) found a high correlation between average national IQs and achievement test scores in 67 countries and concluded ‘The correlation is so high that national IQs and educational achievement appear to be measures of the same construct.’ The author finds here the data do not support this conclusion.

Cross-National Social Ecology of Intelligence and Suicide Prevalence: Integration, Refinement, and Update of Studies

This study integrates, refines, and updates previous findings pertaining to positive ecologic (population-level) associations between intelligence and suicide prevalence across nations by using corrected and revised national IQ estimates and, further, a quality-of-human-conditions index, both recently published by Lynn and Vanhanen. Across a global 85-nation sample of sex-specific total suicide rates and a Eurasian 48-nation sample of sex-specific elderly suicide rates, these were positively associated with updated national IQ estimates. The associations were stronger for the general population than for elderly persons, independent of the quality of human conditions, and notedly stronger in exponential fitting of suicide rates with national IQ than in linear fitting, thereby indicating that shifts or differences in national IQ correspond to proportional, not absolute, changes in suicide rates. Implications of these findings and the question of generalizability of such associations to the individual level are discussed.

The geography of IQ

This paper examines the distribution of national IQ in geographical space. When the heritability of IQ and its dependence on eco-social factors are considered from a global perspective, they suggest that the IQs of neighboring countries should be similar. Using previously published IQ data for 113 nations (Lynn, R., & Vanhanen, T., (2006). IQ and global inequality. Athens, GA: Washington Summit Publishers.) the relationship between geographical location and national IQ is formally tested using spatial statistics. It is found that as predicted, nations that are geographical neighbors have more similar IQs than nations that are far apart. National IQ varies strikingly with position around the globe; the relationship between location and national IQ is even stronger than the relationship between location and national average temperature. The findings suggest that Lynn & Vanhanen's national IQ measures are reliable and adequately representative, and that their procedures for estimating missing national IQ scores from the scores of nearby nations are defensible.

Review Essay: Lynn and Vanhanen, IQ and Global Inequality

IQ and Global Inequality is a sequel to the authors' earlier IQ and the Wealth of Nations wherein they argued that “… national differences in intelligence are an important factor contributing to differences in national wealth and rates of economic growth” (p. 2). Or, later more precisely stated, that “… national IQ is the single most powerful explanatory variable, but because the explained part of the variation does not rise higher than 40–60 percent, this explanation leaves room for other explanatory factors”(p. 13). Not surprisingly, even so qualified, this thesis triggered a “mixed reception.” As the authors relate with refreshing candor, some of the reviewers denounced them for “jumping to conclusions,” took issue with their “relatively weak statistical evidence and dubious presumptions,” found the study “neither methodologically nor theoretically convincing,” and dismissed the evidence as “virtually meaningless” (p. 3).

National IQ Means, Calibrated and Transformed from Educational Attainment, and Their Underlying Gene Frequencies

Any general statement as to whether the secular trend of a society is eugenic or dysgenic depends upon a reliable calibration of the measurement of general intelligence. Richard Lynn set the mean IQ of the United Kingdom at 100 with a standard deviation of 15, and he calculated the mean IQs of other countries in relation to this “Greenwich IQ”. But because the UK test scores could be declining, the present paper recalibrates the mean IQ 100 to the average of seven countries having a historical mean IQ of 100. By comparing Lynn-Vanhanen-IQ with PISA scores and educational attainment of native and foreign born populations transformed into the IQ metric, we confirmed brain gain and brain drain in a number of nations during recent decades. Furthermore, the growth of gross domestic product per capita can be derived as a linear function of the percentage of people with an IQ above 105 and its underlying frequency of a hypothetical major gene of intelligence.

NATIONAL IQS PREDICT DIFFERENCES IN SCHOLASTIC ACHIEVEMENT IN 67 COUNTRIES

This paper examines the relationship of the national IQs reported by Lynn & Vanhanen (2002, 2006) to national achievement in mathematics and science among 8th graders in 67 countries. The correlation between the two is 0.92 and is interpreted as establishing the validity of the national IQs. The correlation is so high that national IQs and educational achievement appear to be measures of the same construct. National differences in educational achievement are greater than differences in IQ, suggesting an amplifier effect such that national differences in IQs amplify differences in educational achievement. Controlling for national differences in IQ, slight inverse relationships of educational achievement are observed with political freedom, subjective well-being, income inequality, and GDP. However, public expenditure on education (as % of GDP) was not a significant predictor of differences in educational achievement.

National Intelligence and Suicide Rate across Europe: An Alternative Test Using Educational Attainment Data

National mean scores on a historical knowledge test (taken as a proxy for intelligence), stemming from representative samples of male (and female) 9th-grade school students from 26 European countries in a 1999 report by Wilberg and Lynn, were significantly positively associated with the national male (and female) suicide rates, independent of the general quality-of-living conditions in these countries. This finding replicates previous evidence from cross-national studies (by Lester and by Voracek), of a correspondence of higher national IQ to higher suicide rates, with an alternative measure of national IQ that is independent of the national IQ estimates recently published by Lynn and Vanhanen which have been used in prior studies.

National Differences in Intelligence and Population Rates of Suicidal Ideation, Suicide Plans, and Attempted Suicide

Population rates of suicidal ideation, suicide plans or attempted suicide from three independent multinational epidemiological surveys (the WHO/EURO and WHO SUPRE-MISS studies and a third one) were not significantly associated with national IQ figures. This result conflicts with previous evidence from cross-national studies (by Lester and by Voracek) of a positive ecological correlation between level of national intelligence and rates of completed suicide. Across nations, the indicators for the prevalence of suicidal behavior also lacked close correspondence with suicide rates, which may be due to the higher unreliability of assessing covert suicidal behavior (suicide ideas, thoughts, plans, and, to a lesser extent, also suicide attempts) as compared to suicidal behavior that is indisputably overt (completed suicide). Several alternative explanations for the current nil findings are also discussed.

Regional Intelligence and Suicide Rate: New Data for Australia and a Synthesis of Research

Previous research has shown for the most part positive correlations between intelligence and suicide prevalence on the national level. However, this study found proxies for regional intelligence in Australia (international average domain scores from the PISA 2000 study) to be significantly negatively correlated with the total, male, and female suicide rates of the different administrative divisions of Australia, and this finding was independent of regional wealth. A research synthesis of the current results and those from similar studies of other countries (positive correlations for Austria, Belarus, The British Isles, Denmark, and The Netherlands; inconclusive findings for France, Germany, and the USA) was conducted. This synthesis of research findings showed that positive ecological correlations of intelligence with suicide rate were more likely observed for nations with higher suicide rates and poorer general living conditions, whereas there was no relation with national IQ.

Temperature and evolutionary novelty as forces behind the evolution of general intelligence

How did human intelligence evolve to be so high? Lynn [Lynn, R. (1991). The evolution of race differences in intelligence. Mankind Quarterly, 32, 99–173] and Rushton [Rushton, J.P. (1995). Race, evolution, and behavior: A life history perspective. New Brunswick: Transaction] suggest that the main forces behind the evolution of human intelligence were the cold climate and harsh winters, which selected out individuals of lower intelligence. In contrast, Kanazawa [Kanazawa, S. (2004). General intelligence as a domain-specific adaptation. Psychological Review, 111, 512–523] contends that it is the evolutionary novelty of the environment which increased general intelligence. Multiple regression analyses support both theories. Annual mean temperature and evolutionary novelty (measured by latitude, longitude, and distance from the ancestral environment) simultaneously have independent effects on average intelligence of populations. Temperature and evolutionary novelty together explain half to two-thirds of variance in national IQ.

Health, wealth and IQ in sub‐Saharan Africa: Challenges facing the Savanna Principle as an explanation for global inequalities in health

Kanazawa's (2006) national- and individual-level analyses seem to support his hypothesis that: IQ scores are better predictors of health than wealth or inequality, except in 'evolutionarily familiar' sub-Saharan Africa which offers limited selection for intelligence (British Journal of Health Psychology 11: 623-42). However, the present paper exposes the flawed assumptions, questionable data, inappropriate analyses and biased interpretations on which this thesis was based. It questions the assumptions that: IQ scores are markers of adaptive genetic differences in intelligence; humans evolved within a predictable 'environment of evolutionary adaptedness': and this environment characterizes contemporary sub-Saharan Africa, offering little selection for intelligence. It also demonstrates that the macro-level data on which these analyses were based were collected across a range of different years, using a range of different sources, and were significantly intercorrelated. While none of these analyses adjusted for study year or study type, all were susceptible to multicollinearity and the 'ecological fallacy'. These flaws were compounded by the selective presentation and partial interpretation of the analyses, which focused on the absence of an 'independent' relationship between 'national IQ' and health within sub-Saharan Africa, but ignored the fact that this is also true for every other region of the world. Likewise, the individual-level analyses did not explore the relationship between IQ scores, self-reported income and health by race, which would have demonstrated the impact of the ecological fallacy. Instead, Kanazawa (2006) mistook statistical associations for evidence of causality and falsely concluded that populations in sub-Saharan Africa are less healthy because they are unintelligent and not because they are poor.

Literacy not intelligence moderates the relationships between economic development, income inequality and health

Kanazawa (2006) presented data allegedly supporting a racist version of evolutionary psychology that claims that the populations of wealthier and more egalitarian societies live longer and stay healthier, not because they are wealthier and more egalitarian, but because they are more intelligent. The objectives of this study are: (i) to determine the relationship between IQ and literacy in Kanazawa's sample of countries and (ii) to reanalyse Kanazawa's dataset using measures of literacy in lieu of national IQ test scores. Correlation and regression were employed. National literacy scores across the countries in the sample are highly skewed. In spite of this, the literacy measures are highly correlated with alleged differences in national IQ (r = .83-.86). The measure of literacy together with economic development (GDPpc) and income inequality (Gini coefficient) control at least 59-64% of the variance in national life expectancy at birth. There is no scientific justification for believing that alleged intelligence differences play any role in explaining international differences in health status. Measures of alleged national IQ scores are highly confounded with differences in literacy. Literacy is a key factor in the health of any community and policies designed to enhance the literacy of a population are expected to lead to significant improvements in health status.

IQ and fertility: A cross-national study

Many studies have found a small to moderate negative correlation between IQ and fertility rates. However, these studies have been limited to the United States and some European countries. The present study was a between-nation study using national IQ scores and national fertility rates. There were strong negative correlations found between national IQ and three national indicators of fertility.

Black intellectual genocide: An essay review of IQ and the Wealth of Nations.

I review the book IQ and the Wealth of Nations, written by Richard Lynn and Tatu Vanhanen. I critique the authors’ major assertion that a significant part of the gap between rich and poor countries is due to differences in national intelligence. The authors claim that they have evidence that differences in national IQ account for substantial variation in per capita income and growth of a nation. This essay review debunks their assumptions that intellectual and income differences between nations stem from genetic differences. This critique provides an extended review of the research literature that argues against these assumptions and presents a different picture from that presented by Lynn and Vanhanen about the concept of intelligence, what IQ measures and does not measure. The essay exposes the racist, sexist, and antihuman nature of the research tradition in which the authors anchored their studies and the deep methodological flaws and theoretical assumptions that appear in their book. The low standards of scholarship evident in the book render it largely irrelevant for modern science. This essay specifically deals with the IQ value of Ethiopian immigrants that came from Israel, used by the authors as representing the National

National differences in intelligence and educational attainment

We examine the correlations between the national IQs of Lynn and Vanhanen (Lynn, R. and Vanhanen, T. (2002). IQ and the wealth of nations. Westport, CT: Praeger. Westport, CT: Praeger, Lynn, R. and Vanhanen, T. (2006). IQ and global inequality. Athens, GA: Washington Summit Books.) and educational attainment scores in math and science for 10- and 14-year olds in 25 countries and 46 countries (respectively) given in the TIMSS 2003 reports. It was found that national IQs had (attenuation corrected) correlations of between 0.92 and 1.00 with scores in math and science. The results are interpreted as a validation of the national IQs. They suggest that national differences in educational attainment may be attributable to differences in IQ, or alternatively that national IQs and in educational attainment are both indicators of the mental ability of national populations. It is also shown that national IQs are positively associated with national per capita income ( r = .61). It is proposed that these have a reciprocal positive feedback relationship such that each augments the other.

Exponential Fitting of Suicide Rate and National Intelligence Estimates

Positive ecological (group-level) associations of Lynn and Vanhanen's 2002 national intelligence (IQ) estimates with the suicide rates of men and women across 85 countries and with the suicide rates of the male, female, and total elderly population across 48 Eurasian countries reported recently is extended by the finding that this ecological association was notedly better accounted for by exponential fitting than by linear fitting. This evidence implies that the effect of a shift in the national IQ on the suicide rate is proportional, not absolute. As a rule of thumb, a 5-point shift in national IQ roughly corresponds to a 50% change in the national suicide rate.

IQ and the wealth of states

In IQ and the Wealth of Nations (2002), Lynn and Vanhanen estimate the mean IQs of 185 nations and demonstrate that national IQs strongly correlate with the macroeconomic performance of the nations, explaining about half of the variance in GDP per capita. I seek to replicate Lynn and Vanhanen's results across states within the United States. I first estimate “state IQs” from the SAT data, and show that the state IQs correlate moderately with the economic performance of the states, explaining about a quarter of the variance in GSP (gross state product) per capita.

Intelligence, Human Capital, and Economic Growth: A Bayesian Averaging of Classical Estimates (BACE) Approach

Human capital plays an important role in the theory of economic growth, but it has been difficult to measure this abstract concept. We survey the psychological literature on cross-cultural IQ tests and conclude that intelligence tests provide one useful measure of human capital. Using a new database of national average IQ, we show that in growth regressions that include only robust control variables, IQ is statistically significant in 99.8% of these 1330 regressions, easily passing a Bayesian model-averaging robustness test. A 1 point increase in a nation’s average IQ is associated with a persistent 0.11% annual increase in GDP per capita.

IQ in the Ramsey Model: A Naive Calibration

I show that in a conventional Ramsey model, between one-fourth and one-half of income differences across countries can be explained by a single factor: The steady-state effect of large, persistent differences in national average IQ on worker productivity. These differences in cognitive ability - which are well-supported in the psychology literature - are likely to be malleable through better nutrition, better education, and better health care in the world's poorest countries. A simple calibration exercise in the spirit of Bils and Klenow (AER, 2000) and Castro (Rev. Ec. Dyn., 2005) is conducted. According to the model, a move from the bottom decile of the global IQ distribution to the top decile will cause steady-state living standards to rise by between 75 and 350 percent. I provide evidence that little of IQ-productivity relationship is likely to be due to reverse causality.

Making development simple. The genetic deterministic hypothesis for economic development

This paper discusses the dangers inherent in attempting to simplify something as complex as development. It does this by exploring the Lynn and Vanhanen theory of deterministic development which asserts that varying levels of economic development seen between countries can be explained by differences in ‘national intelligence’ (national IQ). Assuming that intelligence is genetically determined, and as different races have been shown to have different IQ, then they argue that economic development (measured as GDP/capita) is largely a function of race and interventions to address imbalances can only have a limited impact. The paper presents the Lynne and Vanhanen case and critically discusses the data and analyses (linear regression) upon which it is based. It also extends the cause–effect basis of Lynne and Vanhanen's theory for economic development into human development by using the Human Development Index (HDI). It is argued that while there is nothing mathematically incorrect with their calculations, there are concerns over the data they employ. Even more fundamentally it is argued that statistically significant correlations between the various components of the HDI and national IQ can occur via a host of cause–effect pathways, and hence the genetic determinism theory is far from proven. The paper ends by discussing the dangers involved in the use of over-simplistic measures of development as a means of exploring cause–effect relationships. While the creators of development indices such as the HDI have good intentions, simplistic indices can encourage simplistic explanations of under-development.