The concepts of race and racial types, and especially the idea of racial and cultural hierarchies, prompted skepticism and activism within international scientific circles long before World War II. It was, however, after the war that thanks to continued racial discrimination around the world and accumulating scientific evidence, scientists, activists, and politicians spoke out against racism. Starting in the 1950s, UNESCO—the educational and scientific arm of the United Nations—began issuing Statements on race. These became a symbol for postwar anti-racism and a prime example of science’s engagement with international politics.

The Statements pointed to popular misunderstandings and political abuses of the concept of race. They also introduced a new way of regarding races as populations with differing gene frequencies. The authors were leading science experts in the relevant fields. Despite diverging opinions, they all agreed that humans belonged to the same species, Homo sapiens, and that human groups did not differ in their innate capacities for intellectual and cultural development.  Many biologists continued to study races defined as genetically distinct populations. These Statements contributed to an understanding that racial categories were not to be found in nature but were instead products of cultural and social conventions, and therefore open to change. The struggle against racism continues to unfold in our societies.