A science which treats of the human race as grouped in tribes or nations, but limits itself to tracing the origin and distribution of races, and investigating the physical and mental peculiarities and differences exhibited by men over all parts of the globe; the chief problem of the science is to decide between the monogenous and polygenous theories of the origin of the race, and investigation inclines to favour the former view. The polygenous argument, based on the diversity of languages, has been discarded, as, if valid, necessitating about a thousand different origins, while the monogenous position is strengthened by the ascertained facts that the different racial groups are fruitful amongst themselves, and present points of mental and physical similarity which accord well with this theory. Ethnologists now divide the human race into three main groups: the Ethiopian or negro, the Mongolic or yellow, and the Caucasic or white.