Origins of Hutu, Tutsi and Twa adults has a high capacity for lactose digestion, a surprisingly high number for an agrarian people, which Mamdani suggests may be the result of centuries of intermarriage with Tutsi. Bethwell Ogot in the 1988 UNESCO "General History" further notes that the number of pastoralists in Rwanda increased sharply around the fifteenth century. Although Luis et al. (2004) in a more general study on bi-allelic markers in many African countries found a statistically significant genetic difference between Tutsi and Hutu, the overall difference were not large. Modern-day genetic studies of the Y-chromosome generally indicate that the Tutsi, like the Hutu, are
Tutsi closely related to each other than to faraway groups. There are essentially two groups of Tutsi in the Congo (DRC). There is the Banyamulenge that live in the southern tip of South Kivu. They are descendants of migrating Rwandan, Burundian and Tanzanian pastoralists. And secondly there are Tutsi in North Kivu and Kalehe in South Kivu - being part of the Banyarwanda (Hutu and Tutsi) community. These are not Banyamulenge. Some of these Banyarwanda are descendants of people that lived long before colonial rule in Rutshuru - on what's currently Congolese territory. Others migrated or were "transplanted" by the Belgian