- [Out] of necessity the earliest humans were ethnically homogeneous and Black. Gloger’s law, which would also appear to be applicable to human beings, lays it down that warm-blooded animals evolving in a warm humid climate will secrete a black pigment (eumelanin). Hence if humankind originated in the tropics around the latitude of the great lakes, he was bound to have brown pigmentation from the start, and it was by differentiation in other climates that the original stock later split into different races;
- There were only two routes available by which these early humans could move out to peopling the other continents, namely, the Sahara and the Nile valley.
Proceedings of the Seventh Pan-African Congress of Pre-History and Quaternary Studies, December 1971.