Racism existed during the 19th century as "scientific racism", which attempted to provide a racial classification of humanity. In 1775 Johann Blumenbach divided the world's population into five groups according to skin color (Caucasians, Mongols, etc.), positing the view that the non-Caucasians had arisen through a process of degeneration. Another early view in scientific racism was the polygenist view, which held that the different races had been separately created. Polygenist Christoph Meiners for example, split mankind into two divisions which he labeled the "beautiful White race" and the "ugly Black race". In Meiners' book, The Outline of History of Mankind, he claimed that a main characteristic of race is either beauty or ugliness. He viewed only the white race as beautiful. He considered ugly races to be inferior, immoral and animal-like.
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.
Scientific racism fell strongly out of favor in the early 20th century, but the origins of fundamental human and societal differences are still researched within academia, in fields such as human genetics including paleogenetics, social anthropology, comparative politics, history of religions, history of ideas, prehistory, history, ethics, and psychiatry. There is widespread rejection of any methodology based on anything similar to Blumenbach's races. It is more unclear to which extent and when ethnic and national stereotypes are accepted.
Although after World War II and the Holocaust, racist ideologies were discredited on ethical, political and scientific grounds, racism and racial discrimination have remained widespread around the world. From time to time when there is a revival of social and political tensions, new works are published which repeat past and discredited racial views such as J R Baker's "Race". Because of the social disapproval of explicit expressions of racism, contemporary authors may achieve a similar effect by insinuating subtle unstated stereotypes in their work as in Gladwell's The Tipping Point, a tactic President Obama called "dog whistle racism".
Du Bois observed that it is not so much "race" that we think about, but culture: "... a common history, common laws and religion, similar habits of thought and a conscious striving together for certain ideals of life". Late 19th century nationalists were the first to embrace contemporary discourses on "race", ethnicity, and "survival of the fittest" to shape new nationalist doctrines. Ultimately, race came to represent not only the most important traits of the human body, but was also regarded as decisively shaping the character and personality of the nation. According to this view, culture is the physical manifestation created by ethnic groupings, as such fully determined by racial characteristics. Culture and race became considered intertwined and dependent upon each other, sometimes even to the extent of including nationality or language to the set of definition. Pureness of race tended to be related to rather superficial characteristics that were easily addressed and advertised, such as blondness. Racial qualities tended to be related to nationality and language rather than the actual geographic distribution of racial characteristics. In the case of Nordicism, the denomination "Germanic" was equivalent to superiority of race.
Bolstered by some nationalist and ethnocentric values and achievements of choice, this concept of racial superiority evolved to distinguish from other cultures that were considered inferior or impure. This emphasis on culture corresponds to the modern mainstream definition of racism: "[r]acism does not originate from the existence of 'races'. It creates them through a process of social division into categories: anybody can be racialised, independently of their somatic, cultural, religious differences."
This definition explicitly ignores the biological concept of race, which is still subject to scientific debate. In the words of David C. Rowe, "[a] racial concept, although sometimes in the guise of another name, will remain in use in biology and in other fields because scientists, as well as lay persons, are fascinated by human diversity, some of which is captured by race."
Racial prejudice became subject to international legislation. For instance, the Declaration on the Elimination of All Forms of Racial Discrimination, adopted by the United Nations General Assembly on November 20, 1963, address racial prejudice explicitly next to discrimination for reasons of race, colour or ethnic origin (Article I).