Hutu and 14% of residents in Rwanda and Burundi, respectively. The Twa pygmies, the smallest of the two countries' principal populations, also share language and culture with the Hutu and Tutsi. However, they are distinguished by a considerably shorter stature. The Hutu are believed to have first emigrated to the Great Lake region from West Africa in the great Bantu expansion. Various theories have emerged to explain the purported physical differences between them and their fellow Bantu-speaking neighbors, the Tutsi. One such thesis, largely based on oral tradition, posits that the Tutsi experienced some admixture with or were partially descended from
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