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
History of Burundi that provided for a president, non-ethnic government, and a parliament. Burundi's first Hutu president, Melchior Ndadaye, of the Hutu-dominated Front for Democracy in Burundi (FRODEBU) Party, was elected in 1993. Ndadaye was assassinated three months later, in October 1993, by Tutsi army extremists. The country’s situation rapidly declined as Hutu peasants began to rise up and massacre Tutsi. In acts of brutal retribution, the Tutsi army proceeded to round up thousands of Hutu and kill them. The Rwandan Genocide in 1994, sparked by the killing of Ndadaye’s successor Cyprien Ntaryamira, further aggravated the conflict in Burundi by sparking additional massacres