Race differences in intelligence: A global perspective

Evolutionary Trends of Polygenic Scores in European Populations From the Paleolithic to Modern Times

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 selection for EA, IQ, and SES traits over the past 12,000 years. Schizophrenia and autism, while similar, showed different temporal patterns, aligning with theories suggesting they are psychological opposites. We observed a decline in PGS for neuroticism and depression, likely due to their genetic correlations and pleiotropic effects on intelligence. Significant PGS shifts from the Upper Paleolithic to the Neolithic periods suggest lifestyle and cognitive demand changes, particularly during the Neolithic Revolution. The study supports a mild hypothesis of Gregory Clark's model, showing a noticeable rise in genetic propensities for intelligence, academic achievement and professional status across Europe from the Middle Ages to the present. While latitude strongly influenced height, its impact on schizophrenia and autism was smaller and varied. Contrary to the cold winters theory, the study found no significant correlation between latitude and intelligence.

Reply to Van Lange et al.: Proximate and ultimate distinctions must be made to the CLASH model

Transcending reviewed proximate theories, Van Lange et al.'s CLASH model attempts to ultimately explain the poleward declension of aggression and violence. Seasonal cold is causal, but, we contend, principally as an ecologically relevant evolutionary pressure. We further argue that futurity and restraint are life history variables, and that Life History Theory evolutionarily explains the biogeography of aggression and violence as strategic adaptation.

African IQ and Mental Retardation

Rushton and Jensen (2005), in an extensive review of racial differences in intelligence test scores, assert that some part of the difference between blacks and whites in mean intelligence (IQ) scores is genetic in origin. They cite earlier reviews by Lynn (1991) and by Lynn and Vanhanen (2002), as well as several more recent studies, which are said to indicate that the mean IQ of sub-Saharan black Africans is about 70 - at the borderline of mental retardation. The present article reviews critically both the original studies and the ways in which the reviewers have described the findings of the studies.

Survey of Expert Opinion on Intelligence: Causes of International Differences in Cognitive Ability Tests

Following Snyderman and Rothman (1987, 1988), we surveyed expert opinions on the current state of intelligence research. This report examines expert opinions on causes of international differences in student assessment and psychometric IQ test results. Experts were surveyed about the importance of culture, genes, education (quantity and quality), wealth, health, geography, climate, politics, modernization, sampling error, test knowledge, discrimination, test bias, and migration. The importance of these factors was evaluated for diverse countries, regions, and groups including Finland, East Asia, sub-Saharan Africa, Southern Europe, the Arabian-Muslim world, Latin America, Israel, Jews in the West, Roma (gypsies), and Muslim immigrants. Education was rated by N = 71 experts as the most important cause of international ability differences. Genes were rated as the second most relevant factor but also had the highest variability in ratings. Culture, health, wealth, modernization, and politics were the next most important factors, whereas other factors such as geography, climate, test bias, and sampling error were less important. The paper concludes with a discussion of limitations of the survey (e.g., response rates and validity of expert opinions).

Considerations Relating to the Study of Group Differences in Intelligence

There are signs that the debate over racial and gender differences in intelligence is about to begin again. In this article we will be concerned primarily with racial differences but will make remarks about gender differences where applicable. Previously there have been bitter arguments over whether or not races exist, over whether it is either important or proper to study racial and gender differences in intelligence, and over the conclusions that have been drawn about environmental and genetic causes as determinants of these differences. We argue that races do, indeed, exist and that studying differences in cognitive competence between groups is a reasonable thing to do. We also point out that past research on both racial and gender differences in intelligence has been marked by methodological errors and overgeneralizations by researchers on all sides of the issue. We propose ten principles of design, analysis, and reporting that ought to be considered carefully when doing or evaluating research in this area.

A critical review of Richard Lynn's reports on reaction time and race

In the early 1990s, psychologist Richard Lynn published papers documenting average reaction times and decision times in samples of nine-year-olds taken from across the world. After summarizing these data, Lynn interpreted his results as evidence of national and racial differences in decision time and general intelligence. Others have also interpreted Lynn's data as evidence of racial differences in decision time and intelligence. However, comparing Lynn's summaries with his original reports shows that Lynn misreported and omitted some of his own data. Once these errors are fixed the rankings of nations in Lynn's datasets are unstable across different decision time measures. This instability, as well as within-race heterogeneity and between-race overlap in decision times, implies that Lynn's reaction time data do not permit generalizations about the decision times and intelligence of people of different races.

Association of Race and Color with Mean IQ across Nations

This study investigated the correlation of both race and skin color in the distribution of mean IQ for 129 countries with primarily indigenous populations. Skin color correlated most highly with mean IQ across the Caucasoid countries ( r = −.86), somewhat less across the Mongoloid countries ( r = −.66), and nonsignificantly across the Negroid countries ( r = .06). When the Negroid and Caucasoid countries were combined, both race and skin color yielded high correlations with IQ ( r = .87, –.95, respectively). When the Negroid and Mongoloid countries were combined, both race and skin color yielded high correlations with IQ ( r = .91, –.91, respectively). When Caucasoid and Mongoloid countries were combined, skin color yielded a high correlation, but race did not correlate significantly with IQ. The greater importance of Negroid race was regarded as congruent with the 1998 generalization of Jensen that the genetic distance between Mongoloids and Caucasoid is less than the genetic distance of these two groups from Negroid.

A Psicologia racial no Brasil (1918-1929)

As teorias raciais chegaram ao Brasil por volta de 1869. Neste artigo procuramos demonstrar como estas teorias entraram no âmbito das ciências psicológicas e direcionaram conceitos e práticas. Foram analisados os anais da Sociedade Eugênica de São Paulo (1919) e os trabalhos apresentados no 1º Congresso Brasileiro de Eugenia (1929), que tiveram como meta "melhorar a raça nacional". Tanto aquela instituição quanto este evento científico contaram com a participação de psicólogos, psiquiatras e antropólogos que se aproximaram do racismo científico, muito difundido pelo mundo no início do século XX. Esta aproximação gerou uma "Psicologia Racial" no Brasil, a qual pretendia reduzir os saberes psicológicos a uma suposta problemática racial.

A study of intelligence in Estonia

The Standard Progressive Matrices was standardised in Estonia in 2001 on a sample of 2,689 12- to 18-yr.-olds. The mean IQ of the Estonian sample was approximately 5 points higher than British IQ norms of 1979. Adjustment for the estimated secular increase of intelligence in Britain reduces the mean IQ of the Estonian sample to 100.2, in relation to a British mean of 100. A particular interest of the result from Estonia is that the intelligence of a European population is apparently not impaired by decades of low living standards.

Toward a racial abyss: eugenics, Wickliffe Draper, and the origins of The Pioneer Fund

The Pioneer Fund was created in 1937 "to conduct or aid in conducting study and research into problems of heredity and eugenics . . . and problems of race betterment with special reference to the people of the United States." The Fund was endowed by Colonel Wickliffe Preston Draper, a New England textile heir, and perpetuates his legacy through an active program of grants, some of the more controversial in aid of research on racial group differences. Those presently associated with the Fund maintain that it has made a substantial contribution to the behavioral and social sciences, but insider accounts of Pioneer's history oversimplify its past and smooth over its more tendentious elements. This article examines the social context and intellectual background to Pioneer's origins, with a focus on Col. Draper himself, his concerns about racial degeneration, and his relation to the eugenics movement. In conclusion, it evaluates the official history of the fund.

Contributions to the history of psychology: CXII. Intelligence, behavior genetics, and the Pioneer Fund

Since World War I, political controversies have complicated the long-standing debate on nature versus nurture, especially the question of the source of the observed mean difference in intelligence between white and black groups. The Pioneer Fund, one of the few nonprofit foundations making grants for study and research into human individual and group differences, has been widely and unfairly attacked by those who believe any such research jeopardizes political commitment to legal equality. The four main scholarly areas of research financially supported by Pioneer have been behavioral genetics, cognitive ability, demographic characteristics, and racial variation. This article provides a unique perspective on the history of the Pioneer Fund and some of the controversies that have taken place.

Visual memory skills in Japanese and Caucasians

Two visual memory tasks were administered to 80 subjects, 48 Japanese and 32 Caucasian, 49 female and 31 male. Japanese subjects were divided into 2 groups, those brought up in Japan with knowledge of kanji and Americans of Japanese ancestry with no kanji experience. The Caucasian subjects were subdivided into two groups, those who had learned kanji as adults, and others without knowledge of kanji. The purpose of the experiment was to examine the possible influence of kanji on the finding that Japanese children and adults score higher than their Caucasian peers in tests of visual ability. A knowledge of kanji did not appear to influence the scoring pattern.

FURTHER EVIDENCE FOR THE EXISTENCE OF RACE AND SEX DIFFERENCES IN CRANIAL CAPACITY

Cranial capacities were calculated from the external head measurements reported for 36 samples of 7 to 15 year olds gathered by the Philadelphia Growth Center (Krogman, 1970). The core sample consisted of 169 white males, 224 black males, 135 white females, and 220 black females. After adjusting for the effects of age, stature and sex, white children averaged 1250 cm3and black children averaged 1236 cm3. After adjusting for the effects of age, stature and race, boys averaged 1300 cm2and girls averaged 1186 cm3.