Origins of Hutu, Tutsi and Twa of neighboring people, it was almost non-existent among Rwandan Tutsi. Presence of the sickle cell trait is evidence of survival in the presence of malaria over many centuries, suggesting differing origins. Regional studies of the ability to digest lactose are also supportive. The ability to digest lactose among adults is widespread only among desert-dwelling nomadic groups that have depended upon milk for millennia. Three quarters of the adult Tutsi of Rwanda and Burundi have a high ability to digest lactose, while only 5% of the adults of the neighboring Shi people of eastern Congo can. Among Hutu, one in three
Hutu Power and declared that any Hutu who did business with a Tutsi was a traitor to the Hutu people. The Commandments declared that "The Hutu should stop having mercy on the Tutsi" and referred to the Tutsis as "common Tutsi enemy". The Rwandan kingdom was traditionally ruled by a Tutsi mwami, or king; Historical evidence suggests that Hutu and Twa were included in government, although the Twa significantly less so than Hutu, who were more numerous. The Tutsi/Hutu divide has been referred to as a caste system. A Hutu could gain Tutsi status through marriage or through success. Tutsis, being primarily