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
Rwandan genocide only one dominated by an opposition party. Opposing the genocide, Habyalimana was able to keep relative calm in the province, until he was deposed by the extremist Sylvain Ndikumana. Finding the population of Butare resistant to murdering their fellow citizens, the government flew in militia from Kigali by helicopter, and they readily killed the Tutsi. Most of the victims were killed in their own villages or in towns, often by their neighbors and fellow villagers. The militia typically murdered victims with machetes, although some army units used rifles. The Hutu gangs searched out victims hiding in churches and school buildings,