Human racial classification may refer to any effort to socially or biologically categorize human beings into different racial groupings based on physical attributes, language, culture or places of geographical origin. However, despite proposed differences between races, modern scientists recognize all such groupings as belonging to the species Homo sapien, as well as the sub-species Homo sapien sapiens.
Formal scientific attempts to classify human races began in the 18th century, particularly with the work of Swedish naturalist Carolus Linnaeus. Linnaeus offered four biologically determined human sub-species: Homo sapiens Eoropeus albescens (white Europeans), Homo sapiens Africanus negreus (Black African), Homo sapiens Americanus rubescens (Native American) and Homo sapiens Asiaticus fucus (Asian). These categories depended largely on skin color and other physical features that Linnaeus believed were unique to those races. However, subsequent science has disproved the notion that any one biological trait is unambiguously unique to a single demographic, suggesting instead that they are more often variables than constants.
The implications of racial classification have been extremely dangerous historically. Particularly, 19th and 20th century ideologies rooted in Social Darwinism claimed that some races were more advanced than others, and that lower-ranked races therefore required instruction by the greater, or that they could even be subject to enslavement or extermination. These theories ultimately colluded with such phenomena as the international slave trade, European imperialism and colonialism, and the genocidal behavior of Nazi Germany and Axis Japan.