This paper analyzes biological and scientific discourses about the racial composition of the Brazilian population, between 1832 and 1911. The first of these dates represents Darwin’s first arrival in the South-American country during his voyage on H.M.S. Beagle. The study ends in 1911, with the celebration of the First universal Races congress in London, where the Brazilian physical anthropologist J.B. Lacerda predicted the complete extinction of black Brazilians by the year 2012. Contemporary European and North-American racial theories had a profound (...) influence in Brazilian scientific debates on race and miscegenation. These debates also reflected a wider political and cultural concern, shared by most Brazilian scholars, about the future of the Nation. With few known exceptions, Brazilian evolutionists, medical doctors, physical anthropologists, and naturalists, considered that the racial composition of the population was a handicap to the commonly shared nationalistic goal of creating a modern and progressive Brazilian Republic. (shrink)