Race and intelligence
Discussions of race and intelligence—specifically regarding claims of differences in intelligence along racial lines—have appeared in both popular science and academic research since the modern concept of race was first introduced. With the inception of IQ testing in the early 20th century, differences in average test performance between racial groups have been observed, though these differences have fluctuated and in many cases steadily decreased over time. Complicating the issue, modern science has concluded that race is a socially constructed phenomenon rather than a biological reality, and there exist various conflicting definitions of intelligence. In particular, the validity of IQ testing as a metric for human intelligence is disputed. Today, the scientific consensus is that genetics does not explain differences in IQ test performance between groups, and that observed differences are environmental in origin.
Pseudoscientific claims of inherent differences in intelligence between races have played a central role in the history of scientific racism. The first tests showing differences in IQ scores between different population groups in the United States were those of United States Army recruits in World War I. In the 1920s, groups of eugenics lobbyists argued that these results demonstrated that African Americans and certain immigrant groups were of inferior intellect to Anglo-Saxon white people, and that this was due to innate biological differences. In turn, they used such beliefs to justify policies of racial segregation. However, other studies soon appeared, contesting these conclusions and arguing that the Army tests had not adequately controlled for environmental factors, such as socioeconomic and educational inequality between the groups.
Later observations of phenomena such as the Flynn effect and disparities in access to prenatal care highlighted ways in which environmental factors affect group IQ differences. In recent decades, as understanding of human genetics has advanced, claims of inherent differences in intelligence between races have been broadly rejected by scientists on both theoretical and empirical grounds.
History of the controversy
Claims of differences in intelligence between races have been used to justify colonialism, slavery, racism, social Darwinism, and racial eugenics. Claims of intellectual inferiority were used to justify British wars and colonial campaigns in Asia. Racial thinkers such as Arthur de Gobineau in France relied crucially on the assumption that black people were innately inferior to white people in developing their ideologies of white supremacy. Even Enlightenment thinkers such as Thomas Jefferson, a slave owner, believed black people to be innately inferior to white people in physique and intellect. At the same time in the United States, prominent examples of African-American genius such the autodidact and abolitionist Frederick Douglass, the pioneering sociologist W. E. B. Du Bois, and the poet Paul Laurence Dunbar stood as high-profile counterexamples to widespread stereotypes of black intellectual inferiority. In Britain, Japan's military victory over Russia in the Russo-Japanese War began to reverse negative stereotypes of "oriental" inferiority.Early IQ testing
The first practical intelligence test, the Binet-Simon Intelligence Test, was developed between 1905 and 1908 by Alfred Binet and Théodore Simon in France for school placement of children. Binet warned that results from his test should not be assumed to measure innate intelligence or used to label individuals permanently. Binet's test was translated into English and revised in 1916 by Lewis Terman and published under the name Stanford–Binet Intelligence Scales. In 1916 Terman wrote that Mexican-Americans, African-Americans, and Native Americans have a mental "dullness seems to be racial, or at least inherent in the family stocks from which they come."The US Army used a different set of tests developed by Robert Yerkes to evaluate draftees for World War I. Based on the Army's data, prominent psychologists and eugenicists such as Henry H. Goddard, Harry H. Laughlin, and Princeton professor Carl Brigham wrote that people from southern and eastern Europe were less intelligent than native-born Americans or immigrants from the Nordic countries, and that black Americans were less intelligent than white Americans. The results were widely publicized by a lobby of anti-immigration activists, including the conservationist and theorist of scientific racism Madison Grant, who considered the so-called Nordic race to be superior, but under threat because of immigration by "inferior breeds." In his influential work, A Study of American Intelligence, psychologist Carl Brigham used the results of the Army tests to argue for a stricter immigration policy, limiting immigration to countries considered to belong to the "Nordic race".
In the 1920s, some US states enacted eugenic laws, such as Virginia's 1924 Racial Integrity Act, which established the one-drop rule as law. Many scientists reacted negatively to eugenicist claims linking abilities and moral character to racial or genetic ancestry. They pointed to the contribution of environment to test results. By the mid-1930s, many psychologists in the US had adopted the view that environmental and cultural factors played a dominant role in IQ test results. The psychologist Carl Brigham repudiated his own earlier arguments, explaining that he had come to realize that the tests were not a measure of innate intelligence.
Discussions of the issue in the United States, especially in the writings of Madison Grant, influenced German Nazi claims that the "Nordics" were a "master race". As American public sentiment shifted against the Germans, claims of racial differences in intelligence increasingly came to be regarded as problematic. Anthropologists such as Franz Boas, Ruth Benedict, and Gene Weltfish did much to demonstrate that claims about racial hierarchies of intelligence were unscientific. Nonetheless, a powerful eugenics and segregation lobby funded largely by textile-magnate Wickliffe Draper continued to use intelligence studies as an argument for eugenics, segregation, and anti-immigration legislation.
Pioneer Fund and ''The Bell Curve''
In 1937, Draper founded the Pioneer Fund with the mission "to advance the scientific study of heredity and human differences". This fund would become a central driver of research into race and intelligence. The Southern Poverty Law Center lists the Pioneer Fund as a hate group, and numerous scholars have criticized it for promoting scientific racism, eugenics and white supremacy.As the desegregation of the United States gained traction in the 1950s, debate about black intelligence resurfaced. Audrey Shuey, funded by the Pioneer Fund, published a new analysis of Yerkes' tests, concluding that black people really were of inferior intellect to white people. This study was used by segregationists to argue that it was to the advantage of black children to be educated separately from the superior white children. In the 1960s, the debate was revived when William Shockley publicly defended the view that black children were innately unable to learn as well as white children. Arthur Jensen expressed similar opinions in his Harvard Educational Review article, "How Much Can We Boost IQ and Scholastic Achievement?," which questioned the value of compensatory education for African-American children. He suggested that poor educational performance in such cases reflected an underlying genetic cause rather than lack of stimulation at home or other environmental factors.
Another revival of public debate followed the appearance of The Bell Curve, a book by Richard Herrnstein and Charles Murray that supported the general viewpoint of Jensen. Many of the references and sources used in the book were advocates for racial hygiene, whose research was funded by Pioneer Fund and published in its affiliated journal Mankind Quarterly. A statement in support of Herrnstein and Murray titled "Mainstream Science on Intelligence," was published in The Wall Street Journal. The Bell Curve also led to critical responses in a statement titled "Intelligence: Knowns and Unknowns" by the American Psychological Association and in several books, including The Bell Curve Debate, Inequality by Design and a second edition of The Mismeasure of Man by Stephen Jay Gould.
Some of the authors proposing genetic explanations for group differences have received funding from the Pioneer Fund, which was headed by J. Philippe Rushton until his death in 2012. Arthur Jensen, who jointly with Rushton published a 2005 review article arguing that the difference in average IQs between blacks and whites is partly due to genetics, received $1.1 million in grants from the Pioneer Fund. According to Ashley Montagu, "The University of California's Arthur Jensen, cited twenty-three times in The Bell Curves bibliography, is the book's principal authority on the intellectual inferiority of blacks."
Additional books by psychologist Pioneer Fund board member Richard Lynn and political scientist Tatu Vanhanen titled IQ and the Wealth of Nations and IQ and Global Inequality, where they try to find a correlation between national IQ test scores and the size of a country's economy, also fueled the debate, with several researchers criticizing their conclusions. 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. They concluded, "Any conclusions drawn from analyses which use these data are therefore unsound, and no reliable evolutionary work should be using these data."
On 24 January 2026, the New York Times reported that a group of fringe researchers with a long history of racist pseudoscience had used deception to access protected NIH data. The group, which included Bryan Pesta, Jordan Lasker, John G. R. Fuerst, and Emil Kirkegaard and was funded in part by the Pioneer Fund, used the data "to produce at least 16 papers purporting to find biological evidence for differences in intelligence between races, ranking ethnicities by I.Q. scores and suggesting Black people earn less because they are not very smart. Mainstream geneticists have rejected their work as biased and unscientific. Yet by relying on genetic and other personal data from the prominent project, known as the Adolescent Brain Cognitive Development Study, the researchers gave their theories an air of analytical rigor.” These papers sparked a new wave of online disinformation about race and intelligence. Pesta, the only one of the group to hold a university position, was fired from Cleveland State University because of this scientific misconduct.