Tutsi rule. The Tutsi aristocracy or elite was distinguished from Tutsi commoners, and wealthy Hutu were often indistinguishable from upper-class Tutsi. When the Belgian colonists conducted censuses, they wanted to identify the people throughout Rwanda-Burundi according to a simple classification scheme. They defined "Tutsi" as anyone owning more than ten cows (a sign of wealth) or with the physical feature of a longer nose, or longer neck, commonly associated with the Tutsi. The Belgians believed that some Tutsis had facial characteristics that were generally atypical of other Bantus. They sought to explain these purported divergent physical traits by postulating admixture with
Origins of Hutu, Tutsi and Twa communities (17.7% Afro-Asiatic genes found in the mixed Hutu/Tutsi population). While most supporters of the migration theory are also supporters of the "Hamitic theory", namely that the Tutsi came from the Horn of Africa, a later theory proposed that the Tutsi had instead migrated from nearby interior East Africa, and that the physical differences were the result of natural selection in a dry arid climate over millennia. Among the most detailed theories was one put forward by Jean Hiernaux, based on studies of blood factors and archeology. Noting the fossil record of a tall people with narrow facial features several