Employs anthropology (notably physical anthropology) and other disciplines or pseudo-disciplines, in proposing anthropological typologies supporting the classification of human populations into physically discrete human races that might be asserted to be superior or inferior. Scientific racism was common during the period from 1600s to the end of World War I. Since the second half of 20th century, scientific racism has been criticized as obsolete and discredited, yet historically has persistently been used to support or validate racist world-views, based upon belief in the existence and significance of racial categories and a hierarchy of superior and inferior races.