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.