 Anders Retzius demonstrated that neither Europeans nor others are one "pure race", but of mixed origins.While discredited, derivations of Blumenbach's taxonomy are still widely used for the classification of the population in the United States.Hans Peder Steensby, while strongly emphasizing that all humans today are of mixed origins, in 1907 claimed that the origins of human differences must be traced extraordinarily far back in time, and conjectured that the "purest race" today would be the Australian Aboriginals.