Race science is the belief that human races are biologically distinct in ways that determine intelligence, morality, behavior, and social worth — and that those differences can be scientifically measured and ranked.

Emerging in the 18th and 19th centuries, race science used tools like skull measurements, IQ testing, and later genetics to argue that white Europeans were naturally superior to other groups. These ideas were presented as objective science, but they were deeply shaped by social prejudice and political agendas. Race science helped justify slavery, colonialism, segregation, and the American eugenics movement, including forced sterilizations upheld by the U.S. Supreme Court in the early 20th century.

Although mainstream biology today rejects the idea that race is a fixed biological hierarchy — modern genetics shows more variation within racial groups than between them — the language of race science has periodically resurfaced in new forms. Instead of explicit claims of superiority, it may appear as debates about IQ gaps, heredity, or “genetic differences,” often stripped of historical context.

Understanding race science isn’t just about studying bad ideas from the past. It’s about recognizing how scientific language can be used to legitimize inequality — and how those ideas have evolved rather than disappeared.