In the late 19th century, the emergence of scientific racism and Social Darwinism, linking social differences with racial differences, provided the German public with pseudoscientific justifications for prejudices against Jews and Roma. During this period, "the concept of race was systematically employed in order to explain social phenomena." This approach attempted to validate the belief that races were not variations of a single species of man but had distinctly different biological origins. It established a purportedly scientifically-backed racial hierarchy, which defined certain minority groups as the other on the basis of biology.