Emil O. W. Kirkegaard

Ulster Institute for Social Research

Many studies have examined the correlations between national IQs and various country-level indexes of well-being. The analyses have been unsystematic and not gathered in one single analysis or dataset. In this paper I gather a large sample of country-level indexes and show that there is a strong general socioeconomic factor (S factor) which is high...

We conducted novel analyses regarding the association between continental racial ancestry, cognitive ability and socioeconomic outcomes across 6 datasets: states of Mexico, states of the United States, states of Brazil, departments of Colombia, sovereign nations and all units together. We find that European ancestry is consistently and usually stro...

The media are often said to be left-leaning in most or all Western countries, but this has been disputed by others. There are multiple ways to examine the question, e.g. content analysis of stories, interviewee choices, think tank citations etc. Here we focus on the political leanings of journalists, specifically on voting behavior as this avoids i...

Since Lynn and Vanhanen's book IQ and the Wealth of Nations (2002), many publications have evidenced a relationship between national IQ and national prosperity. The strongest statistical case for this lies in Jones and Schneider's (2006) use of Bayesian model averaging to run thousands of regressions on GDP growth (1960-1996), using different combi...

It has been claimed that left-wingers or liberals (US sense) tend to more often suffer from mental illness than right-wingers or conservatives. This potential link was investigated using the General Social Survey cumulative cross-sectional dataset (1972-2018). A search of the available variables resulted in 5 items measuring one's own mental illnes...

We scraped user pages of 7,739 Wikipedia editors. Of these, 224 users positioned themselves politically using the semi-standardized "userboxes". Based on this sample, Wikipedia editors' views had a strong tilt towards the left. The results are congruent with the political leanings of related occupations, such as journalists and academics.

A prior study found that general intelligence (g) is highly predictable from the items of the MMPI-2 (Minnesota Multiphasic Personality Inventory), achieving a cross-validated correlation of .85 in the Vietnam Experience Study, a sample of American military men. Here, the validity of a reduced version of this prediction model with 107 MMPI items wa...

This study assesses the predictive accuracy of polygenic scores (PGS) from a variety of genome-wide association studies (GWAS) in a dataset of 28 Chinese provinces, with a focus on educational attainment (EA) and height. European-derived EA PGSs showed stronger correlations with average IQs of Chinese provinces (r = .52) than did East Asian-derived...

Many studies have found that conservatives show an advantage in mental health and happiness and various causes of this have been debated (e.g., religiousness, ideology, or genetics). However, not much attention has been given to examining whether this advantage is psychometrically real, or whether it is due to test bias. We analyzed data from two l...

Using 47 indicators of socioeconomic development and various sources of performance on cognitive tests, we constructed the SDI (socioeconomic development index) and a set of national IQs for 197 nations, the latter using no geographic imputations. Combining the various datasets reduced the estimated standard error of national IQs from 5.41 to 2.58,...

Some studies have indicated that there may be intelligence differences between different sexual orientations or gender identifications. We investigated whether intelligence was predicted by sexual orientation and gender identity in a large sample of dating site users from OKCupid (N = ~36,866). In our regression model, we found that homosexuals wer...

Previous studies have found a high degree of assortative mating for educational attainment (r = .56). However, this can be confounded by cohort effects or country effects, where certain nations may have more pronounced assortative mating than others. In addition, method variance regarding how educational attainment is measured may also result in he...

Jackson and Winston (“JW;” 2021) recently argued that no real taboos exist regarding the study of potential genetic links between race and IQ test scores. Instead, the authors essentially claimed that researchers in this area have protested too much. JW offered several arguments that presumably supported their claims, which we rebut here first. Emp...

This study examines the temporal and geographical evolution of polygenic scores (PGSs) across cognitive measures (Educational Attainment [EA], Intelligence Quotient [IQ]), Socioeconomic Status (SES), and psychiatric conditions (Autism Spectrum Disorder [ASD], schizophrenia [SCZ]) in various populations. Our findings indicate positive directional se...

Leslie et al. (2015) advocated a model where a stereotype that a given field requires brilliance to succeed scares women away from the field, thus resulting in a self-fulfilling prophecy similar to stereotype threat. Leslie however ignored decades of findings in stereotype accuracy research, where stereotypes are generally known to accurately track...

Previous research has indicated that religiousness may moderate the negative effect of intelligence on fertility which is found in modern populations. We studied this question using the Vietnam Experience Study, a public dataset of 4,462 American Vietnam-era veterans. In line with prior research, we found that, net of controls, intelligence predict...

A body of research indicates that people who are more intelligent tend to have fewer children than do those who are less intelligent, at least since around 1900 (Lynn, 2011). Nyborg (2012) has predicted that the consequent IQ decline will lead to the eventual decay of Western civilization. However, there is little research on fertility intentions a...

Structural racism has often been invoked to explain observed disparities in social outcomes, such as in educational attainment and income, among different American racial/ethnic groups. Theorists of structural racism typically argue that racial categories are socially constructed and do not correspond with genetic ancestry; additionally, they argue...

We analysed 127 Ancient Roman genomes with a view to understanding the possible reasons for the fall of the Roman Empire. Taking the polygenic score for educational attainment (EA4) as a proxy for intelligence, we find that intelligence increased from the Neolithic Era (Z= -0.77) to the Iron Age (Z= 0.86), declines after the Republic Period and dur...

Research shows that honesty correlates positively with intelligence. Similarly, there are racial differences in honesty, with Europeans being more honest than various other ethnic groups. It is currently unknown to what degree race differences in intelligence can explain the differences in honesty. We investigated this question using data from the...

Racial differences in sexuality are difficult to study due to the privacy of sexual intercourse and the questionable validity of self-reports. We use a novel method to study racial differences: surveying sex workers. We surveyed 129 American female sex workers. We asked them to rate the ethnicities with whom they had had intercourse on thirteen tra...

At first glance international prison rates, measured by prisoners per 100,000 population, appear to be uncorrelated with national intelligence and with racial diversity, which contradicts both a priori expectations and individual level observations that higher intelligence (IQ) generally reduces criminality, although GDP per capita shows a small po...

We utilised data from the OkCupid dating site to study preferences for body parts in attraction judgements. We found that most people (71%) have a stated preference for faces, with non-Europeans finding other parts more important: lower parts ("butt/legs"; 8%), chest ("chest/breasts"; 3%), and Other (18%). We regressed these preferences on likely c...

Intelligence tests are excellent predictors of school and job performance, and racial/ethnic differences in mean IQ are common. Based on five lines of evidence, Warne (2021) builds a case for partly genetic causes of differences in general intelligence (g) across American self/parental-identified race or ethnicity (SIRE). Based on a careful reading...

This article evaluates the relationship between inequality in cognitive test scores across countries and income inequality. By meta-analyzing the standard deviations in PISA results from 2000 to 2018, the authors construct a measure of intelligence inequalities across countries. They then test this measure to investigate if it has any association w...

Here we reply to Giangrande and Turkheimer's (2022; G&T) recent critique of a meta-analysis we published in Intelligence regarding the Scarr-Rowe Hypothesis and the apparent lack of putative race/ethnic group differences in the heritability of intelligence (Pesta et al., 2020). Our rebuttal is divided into three sections that address ubiquitous mis...

We used data from the Adolescent Brain Cognitive Development Study to create a multimodal MRI-based predictor of intelligence. We applied the elastic net algorithm to over 50,000 neurological variables. We find that race can confound models when a multiracial training sample is used, because models learn to predict race and use race to predict inte...

One commonly studied aspect of the importance of IQ is its validity in predicting job performance. Previous research on this subject has yielded impressive results, regularly finding operational validities for general mental ability exceeding 0.50. In 2015, Ken Richardson and Sarah Norgate criticized the research on the relationship between IQ and...

Systemic racism theory predicts that counties where there are more White people and where people are more racist against non-Whites should have larger race gaps on cognitive measures. We used county-level data from the United States to test these predictions of the systemic racism model. We used cognitive test results from state scholastic tests fr...

Research has shown that intelligence correlates with different ideological and political beliefs, even when extensive controls are used. Based on data from the NLSY97 dataset, Belief in Governmental Responsibility (BGR) (r = -.35, 95 % CI -.40, -.30) and Belief in Individual Responsibility (BIR) (r = -.25, 95 % CI -.30, -.20) were both negatively c...

Scores for country-of-origin immigrant groups on mandatory 5th and 8th grade mathematics tests in Norway were published in a 2015 report, covering 47 origins. We studied whether these could be predicted by country-of-origin average intelligence. All data concerned second-generation immigrants (defined as those born in Norway), and included a variet...

Permanent adipose breasts are unique to humans among primates. We propose that permanent breasts, and a preference for them, are an adaptation for pair bonding and a slow life history strategy. This theory predicts that races with a slower life history strategy will prefer breasts to buttocks. To test our hypothesis, we predict preferences for brea...

Research suggests that mixed-race adolescents are more likely than monoracial adolescents to use drugs or engage in violent behavior, and that interracial relationships contain more conflict than monoracial ones. However, it is not clear whether these outcomes are caused by racial conflict and identity or by self-selection. To determine this, we us...

Previous studies have found that the ability of a country’s cognitive elite is generally more predictive than the average ability. However, these studies have relied on sub-optimal methods. Here, the authors tested smart fraction theory, as it is known, using a pre-residualization approach, which obviates the problem of collinearity. For outcome va...

This brief report analyzes data from a series of studies carried out by Bates and Gignac (2022), collected from paid survey takers on the Prolific platform (total n = 3357). In this UK sample, Black-White gap sizes on cognitive tests were substantial with an overall effect size d of 0.99 standard deviations adjusted for unreliability (unadjusted me...

A recent study by Dutton et al. (J Relig Health 59:1567–1579. https://doi.org/10.1007/s10943-019-00926-3, 2020) found that the religiousness-IQ nexus is not on g when comparing different groups with various degrees of religiosity and the non-religious. It suggested, accordingly, that the nexus related to the relationship between specialized analyti...

Intelligence tests are excellent predictors of school and job performance and racial/ethnic differences in mean IQ are common. Based on five lines of evidence, Warne (2021) builds a case for partly genetic causes of differences in general intelligence (g) across American Self/Parental-identified race or ethnicity. Based on a careful reading of Warn...

There is solid evidence that human populations have been selecting against intelligence-related genetic variants since the mid to late 1800s. The selection is generally weak, but varies by ethnic group and sex. Since religious teachings usually include strong pro-natalist components, we investigated whether this might also affect the selection for...

A number of lines of evidence, such as studies of religious converts and members of conspicuous subcultures, have found a relationship between holding and expressing a strong counter-cultural identity and mental instability. Here we test whether dying your hair an unnatural colour - something which conspicuously expresses non-conformity - is relate...

We investigated how genetically measured ancestry relates to social status in Chile. Our study is based on a dataset of 1,805 subjects previously analyzed in another study. Ancestry was measured using genetic analysis based on microarray data. Overall we find that compared to European ancestry (44%), the Amerindian ancestries Mapuche (central Chile...

The editorial boards of academic journals overrepresent men, even above their proportion in university faculties. We test whether this sex disparity is caused by anti-female bias, supposing that anti-female discrimination means women must have a higher research output than men to overcome bias against them. We collect a dataset of the research outp...

Recent research has provided strong demonstrations to the effects that education improves scores on intelligence tests. We tested whether the improvements elicited by education were consistent with raised intelligence or enhancements to specific skills involved in intelligence testing. We used the structural equation models from Ritchie, Bates & De...

Species and subspecies differ substantially in the size of their testicles. A study has found differences in average testis size when comparing Europeans and Northeast Asians. Other studies have found differences in testosterone levels between Blacks, Whites and Northeast Asians. We sought to replicate and extend these findings in a dataset of 4,46...

Italy shows a strong north-south gradient in measures of well-being, with the northern areas being far wealthier than the southern. Less well known is that there is also a latitudinal gradient in intelligence. We combined numeracy scores based on age heaping data for Italian provinces from the censuses of 1861, 1871, and 1881 with modern data about...

It has been claimed that social race and genetic ancestry are at best weakly related. Here we test this claim by applying predictive modeling in both directions, i.e., predicting genetic ancestry from social race(s), and predicting social race(s) from genetic ancestry. We utilize the public Pediatric Imaging, Neurocognition, and Genetics (PING) dat...

Amongst admixed American populations, polygenic scores for educational attainment and intelligence (eduPGS), genetic ancestry, and cognitive ability covary. We argue that this plausibly could be due to either confounding or to causally-relevant genetic differences between ancestral groups. It is important to determine which scenario is the case in...

The Dunning-Kruger effect is a well-known psychological finding. Unfortunately, there are two aspects of the finding, one trivial, indeed a simple statistically necessary empirical pattern, and the other an unsupported theory that purports to explain this pattern. Recently, Gignac & Zajenkowski (2020) suggested two ways to operationalize and test t...

Chronotype and cognitive ability are two human phenotypes with an uneven geographic distribution due to both selective migration and causal environmental effects. In our study, we aimed to examine the relationship between geographic variables, cognitive ability and chronotype. We used a large anonymized sample (n = 25,700, mostly from the USA, UK,...

We gathered survey data on journalists' political views in 17 Western countries. We then matched these data to outcomes from national elections, and constructed metrics of journalists' relative preference for different political parties. Compared to the general population of voters, journalists prefer parties that have more left-wing positions over...

We examined data from the popular free online 45-item “Vocabulary IQ Test” from https://openpsychometrics.org/tests/VIQT/. We used data from native English speakers (n = 9,278). Item response theory analysis (IRT) showed that most items had substantial g-loadings (mean = .59, sd = .22), but that some were problematic (4 items being lower than .25)....

In this pre-registered study, we gathered two online samples totaling 615 subjects. The first sample was nationally representative with regards to age, sex and education, the second was an online convenience sample with mostly younger people. We measured intelligence (vocabulary and science knowledge, 20 items each) using newly constructed Dutch la...

Prior research has indicated that one can summarize the variation in psychopathology measures in a single dimension, labeled P by analogy with the g factor of intelligence. Research shows that this P factor has a weak to moderate negative relationship to intelligence. We used data from the Vietnam Experience Study to reexamine the relations between...

There are few empirically derived theories explaining group differences in cognitive ability. Spearman's hypothesis is one such theory which holds that group differences are a function of a given test's relationship to general intelligence, g. Research into this hypothesis has generally been limited to the application of a single method lacking sen...

Using a sample of ~3,100 U.S. counties, we tested geoclimatic explanations for why cognitive ability varies across geography. These models posit that geoclimatic factors will strongly predict cognitive ability across geography, even when a variety of common controls appear in the regression equations. Our results generally do not support UV radiati...

Statistical methods are presented to a linguistics audience. Statistical methods are then applied to the large WALS dataset to show that automated methods can identify patterns among language features. These results are shown to be more extreme than one would expect based on chance variation. Furthermore, it is shown numerically that language featu...

Immigrants to Western countries typically have worse social outcomes than natives, but country of origin immigrant groups differ widely. We studied school performance in Denmark for 116 immigrant groups measured by the grade point average (GPA) of the 9th grade exam at the end of compulsory schooling. General intelligence is a strong causal factor...

Assortative mating for both physical and psychological traits is well-established in many animal species, including humans. Most studies, however, only compute linear measures of mate similarity, typically Pearson correlations. However, it is possible that trait similarity, or dissimilarity, has complex patterns missed by the correlation metric. We...

Patient people fare better in life than impatient people. Based on this and on economic models, many economists have claimed that more patient countries should fare better than less patient countries. We utilize cross-national data in non-cognitive traits measured in the Global Preference Survey (GPS). This survey measured six non-cognitive traits...

We examined regional inequality in Belgium, both in the 19 communes of Brussels and in the country as a whole (n = 589 communes). We find very strong relationships between Muslim% of the population and a variety of social outcomes such as crime rate, educational attainment, and median income. For the 19 communes of Brussels, we find a correlation o...

There are a few scattered reports that uric acid level predicts various forms of academic achievement beyond any associations with intelligence, but all these studies are old and small. Given the potential importance of this relationship for interventions, there is a need for a more recent, larger study. We use archival data from the Vietnam Experi...

Chronotype and cognitive ability are two psychological phenotypes with an uneven geographical distribution due to both selective migration and causal environmental effects. In our study we aimed to unravel the relationship between geographical variables, cognitive ability and chronotype. We used a large anonymized sample (N=25700) of dating site us...

A recent study by Tsukahara et al. (2016) found correlations between pupil size and measures of intelligence, with r values around .30. We attempted to replicate this association in a large dataset of US military personnel (n = 4,462). General intelligence, g, was extracted from 19 diverse tests. We first confirmed that right and left eye pupil siz...

Taking countermeasures to protect against future events requires predicting what the future will be like. In late 2019, a novel coronavirus known as NCov-2019 emerged in Wuhan, China, and has since spread to most countries in the world. Anticipatory responses by civilians facing the crisis have included self-isolation measures, extreme stockpiling...

Stereotypes about 32 country-of-origin groups were measured using an online survey of the adult, non-elderly Danish population (n = 476 after quality control). Participants were asked to estimate each group’s net fiscal contribution in Denmark. These estimates were then compared to the actual net fiscal contributions for the 32 groups, taken from a...

It has been claimed that left-wingers or liberals (US sense) tend to be more mentally ill than right-wingers or conservatives. This potential link was investigated using the General Social Survey. A search found 5 items measuring one's own mental illness in different ways (e.g."Do you have any emotional or mental disability?"). All of these items w...

We estimated crime rates among 70 origin-based immigrant groups in the Netherlands for the years 2005-2018. Results indicated that crime rates have overall been falling for each group in the period of study, and in the country as a whole, with about a 50% decline since 2005. Immigrant groups varied widely in crime rates, with East Asian countries b...

Human Diversity is Charles Murray’s latest book. This review evaluates the claims made in the book and places both the author’s theses and their criticisms in their historical context. It concludes that this book is valuable as an updated summary of current knowledge about psychological differences (in the averages) between genders, races, and soci...

Human Diversity is Charles Murray’s latest book. This review evaluates the claims made in the book and places both the author’s theses and their criticisms in their historical context. It concludes that this book is valuable as an updated summary of current knowledge about psychological differences (in the averages) between genders, races, and soci...

We sought to assess whether previous findings regarding the relationship between cognitive ability and religiosity could be replicated in a large dataset of online daters (maximum n = 67k). We found that self-declared religious people had lower IQs than nonreligious people (atheists and agnostics). Furthermore, within most religious groups, a negat...

The nature of race differences, and even the mere “existence” of human races, continues to be a major source of controversy and confusion. This brief review summarizes the empirical evidence about race differences and the conceptual issues related to taxonomy, as well as practical implications for medicine and the social sciences. The review shows...

A small research stream exists which focuses on relationships between political ideology (inferred from voting behavior) and the intelligence of geopolitical subdivisions such as the 50 U.S. states. With U.S. state-level data, IQ scores positively predict votes cast for Democrats, but only when controlling for state racial composition. Here, howeve...

Via meta-analysis, we examined whether the heritability of intelligence varies across racial or ethnic groups. Specifically, we tested a hypothesis predicting an interaction whereby those racial and ethnic groups living in relatively disadvantaged environments display lower heritability and higher environmentality. The reasoning behind this predict...