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
Origins of Hutu, Tutsi and Twa largely of Bantu extraction (60% E1b1a, 20% B, 4% E3). Paternal genetic influences associated with the Horn of Africa and North Africa are few (under 3% E1b1b), and are ascribed to much earlier inhabitants who were assimilated. However, the Tutsi have considerably more haplogroup B paternal lineages (14.9% B) than do the Hutu (4.3% B). Trombetta et al. (2015) found 22.2% of E1b1b in a small sample of Tutsis from Burundi, but no bearers of the haplogroup among the local Hutu and Twa populations. The subclade was of the M293 variety, which suggests that the ancestors of Tutsis in this