Despite disagreement and controversy surrounding attempts to categorize humans by race, an early system based on geographic origin and physical characteristics names Caucasoids, Negroids, Mongoloids and Australoids as the four major races of humans. Sub-groups exist within each group, although the distinction between classifications is often difficult to determine due to intermingling and migration. There are also cultural sensitivities, stirred by studies that attempt to link racial categories with traits such as intelligence, physical ability or social behavior.
The Caucasoid race originates from the Eurasian area of the Caucasus, and includes various Aryan Indo-European, Semitic Arab and Hebrew, and North African sub-groups based on geographic location and language. These people have pale to light brown skin, blond to black hair, narrow nasal ridges and prominent eyes.
Negroids originate from the equatorial regions of Africa and India and include Pygmy, Sudantic and Bantu sub-groups. They typically have darkly pigmented brown to black skin, coarse black hair and wide nasal ridges, lips and brows.
Mongoloids include Asian and Native American groups divided into Neo-Mongoloid Eskimo, Chinese and other pale-skinned sub-groups adapted to cold environments, and Paleo-Mongoloid Native American, Polynesian, Filipino, and Southeast Asian sub-groups with darker skin colors adapted to tropical environments. They typically have straight black hair, small almond-shaped eyes and lean muscular frames. This group include Dravidians of the Indian subcontinent sometimes treated as a separate group.
Australoids include subgroups more properly classified as Negroid subgroups according to ethnologists, such as the aboriginal and southern Pacific and Asian groups with dark skin and coarse hair.